WO2018107109A1 - Novel anti-kremen2 antibodies and methods of use - Google Patents

Novel anti-kremen2 antibodies and methods of use Download PDF

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Publication number
WO2018107109A1
WO2018107109A1 PCT/US2017/065445 US2017065445W WO2018107109A1 WO 2018107109 A1 WO2018107109 A1 WO 2018107109A1 US 2017065445 W US2017065445 W US 2017065445W WO 2018107109 A1 WO2018107109 A1 WO 2018107109A1
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seq
antibody
cancer
kremen2
antibodies
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PCT/US2017/065445
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French (fr)
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Samuel A. Williams
Sarah FONG
David Liu
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Abbvie Stemcentrx Llc
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K16/00—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies
    • C07K16/18—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans
    • C07K16/28—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans against receptors, cell surface antigens or cell surface determinants
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K39/00—Medicinal preparations containing antigens or antibodies
    • A61K39/395—Antibodies; Immunoglobulins; Immune serum, e.g. antilymphocytic serum
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K47/00—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient
    • A61K47/50—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates
    • A61K47/51—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent
    • A61K47/68—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent the modifying agent being an antibody, an immunoglobulin or a fragment thereof, e.g. an Fc-fragment
    • A61K47/6801—Drug-antibody or immunoglobulin conjugates defined by the pharmacologically or therapeutically active agent
    • A61K47/6803—Drugs conjugated to an antibody or immunoglobulin, e.g. cisplatin-antibody conjugates
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K47/00—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient
    • A61K47/50—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates
    • A61K47/51—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent
    • A61K47/68—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent the modifying agent being an antibody, an immunoglobulin or a fragment thereof, e.g. an Fc-fragment
    • A61K47/6835—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent the modifying agent being an antibody, an immunoglobulin or a fragment thereof, e.g. an Fc-fragment the modifying agent being an antibody or an immunoglobulin bearing at least one antigen-binding site
    • A61K47/6849—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent the modifying agent being an antibody, an immunoglobulin or a fragment thereof, e.g. an Fc-fragment the modifying agent being an antibody or an immunoglobulin bearing at least one antigen-binding site the antibody targeting a receptor, a cell surface antigen or a cell surface determinant
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K47/00—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient
    • A61K47/50—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates
    • A61K47/51—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent
    • A61K47/68—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent the modifying agent being an antibody, an immunoglobulin or a fragment thereof, e.g. an Fc-fragment
    • A61K47/6889—Conjugates wherein the antibody being the modifying agent and wherein the linker, binder or spacer confers particular properties to the conjugates, e.g. peptidic enzyme-labile linkers or acid-labile linkers, providing for an acid-labile immuno conjugate wherein the drug may be released from its antibody conjugated part in an acidic, e.g. tumoural or environment
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
    • A61P35/00—Antineoplastic agents
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K14/00—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof
    • C07K14/435—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof from animals; from humans
    • C07K14/705—Receptors; Cell surface antigens; Cell surface determinants
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
    • G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
    • G01N33/53—Immunoassay; Biospecific binding assay; Materials therefor
    • G01N33/574—Immunoassay; Biospecific binding assay; Materials therefor for cancer
    • G01N33/57484—Immunoassay; Biospecific binding assay; Materials therefor for cancer involving compounds serving as markers for tumor, cancer, neoplasia, e.g. cellular determinants, receptors, heat shock/stress proteins, A-protein, oligosaccharides, metabolites
    • G01N33/57492—Immunoassay; Biospecific binding assay; Materials therefor for cancer involving compounds serving as markers for tumor, cancer, neoplasia, e.g. cellular determinants, receptors, heat shock/stress proteins, A-protein, oligosaccharides, metabolites involving compounds localized on the membrane of tumor or cancer cells
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K39/00—Medicinal preparations containing antigens or antibodies
    • A61K2039/505—Medicinal preparations containing antigens or antibodies comprising antibodies
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2317/00—Immunoglobulins specific features
    • C07K2317/20—Immunoglobulins specific features characterized by taxonomic origin
    • C07K2317/24—Immunoglobulins specific features characterized by taxonomic origin containing regions, domains or residues from different species, e.g. chimeric, humanized or veneered
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2317/00—Immunoglobulins specific features
    • C07K2317/30—Immunoglobulins specific features characterized by aspects of specificity or valency
    • C07K2317/33—Crossreactivity, e.g. for species or epitope, or lack of said crossreactivity
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2317/00—Immunoglobulins specific features
    • C07K2317/50—Immunoglobulins specific features characterized by immunoglobulin fragments
    • C07K2317/52—Constant or Fc region; Isotype
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2317/00—Immunoglobulins specific features
    • C07K2317/50—Immunoglobulins specific features characterized by immunoglobulin fragments
    • C07K2317/55—Fab or Fab'
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2317/00—Immunoglobulins specific features
    • C07K2317/70—Immunoglobulins specific features characterized by effect upon binding to a cell or to an antigen
    • C07K2317/76—Antagonist effect on antigen, e.g. neutralization or inhibition of binding
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2317/00—Immunoglobulins specific features
    • C07K2317/70—Immunoglobulins specific features characterized by effect upon binding to a cell or to an antigen
    • C07K2317/77—Internalization into the cell
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2317/00—Immunoglobulins specific features
    • C07K2317/90—Immunoglobulins specific features characterized by (pharmaco)kinetic aspects or by stability of the immunoglobulin
    • C07K2317/92—Affinity (KD), association rate (Ka), dissociation rate (Kd) or EC50 value

Definitions

  • This application generally relates to anti-KREMEN2 antibodies or immunoreactive fragments or derivatives thereof, including antibody drug conjugates, and compositions comprising the same for the treatment, diagnosis or prophylaxis of cancer and any recurrence or metastasis thereof.
  • Selected embodiments of the invention provide for the use of such anti-KREMEN2 antibodies or antibody drug conjugates for the treatment of cancer comprising a reduction in tumorigenic cell frequency.
  • Differentiation and proliferation of stem cells and progenitor cells are normal ongoing processes that act in concert to support tissue growth during organogenesis, cell repair and cell replacement.
  • the system is tightly regulated to ensure that only appropriate signals are generated based on the needs of the organism.
  • Cell proliferation and differentiation normally occur only as necessary for the replacement of damaged or dying cells or for growth.
  • disruption of these processes can be triggered by many factors including the under- or overabundance of various signaling chemicals, the presence of altered microenvironments, genetic mutations or a combination thereof.
  • Disruption of normal cellular proliferation and/or differentiation can lead to various disorders including proliferative diseases such as cancer.
  • the present invention provides novel antibodies, and corresponding antibody drug or diagnostic conjugates (ADCs), or compositions thereof, which specifically bind to human KREMEN2 determinants.
  • the KREMEN2 determinant is a KREMEN2 protein expressed on tumor cells while in other embodiments the KREMEN2 determinant is expressed on tumor initiating cells.
  • the antibodies of the invention bind to a KREMEN2 protein and compete for binding with an antibody that binds to an epitope on human KREMEN2 protein.
  • the invention comprises an antibody that comprises or competes for binding with an isolated antibody that binds to a cell expressing human KREMEN2 having SEQ ID NO: 1, wherein the isolated antibody comprises: (1) a light chain variable region (VL) of SEQ ID NO: 21 and a heavy chain variable region (VH) of SEQ ID NO: 23; or (2) a VL of SEQ ID NO: 25 and a VH of SEQ ID NO: 27; or (3) a VL of SEQ ID NO: 29 and a VH of SEQ ID NO: 31; or (4) a VL of SEQ ID NO: 33 and a VH of SEQ ID NO: 35; or (5) a VL of SEQ ID NO: 37 and a VH of SEQ ID NO: 39; or (6) a VL of SEQ ID NO: 41 and a VH of SEQ ID NO: 43; or (7) a VL of SEQ ID NO: 45 and a VH of SEQ ID NO: 47; or (8) a VL of S
  • the invention comprises an antibody that binds to KREMEN2 comprising a light chain variable region and a heavy chain variable region, wherein the light chain variable region has three CDRs of a light chain variable region set forth as SEQ ID NO: 21, SEQ ID NO: 25, SEQ ID NO: 29, SEQ ID NO: 33, SEQ ID NO: 37, SEQ ID NO: 41, SEQ ID NO: 45, SEQ ID NO: 49, SEQ ID NO: 53, SEQ ID NO: 57, SEQ ID NO: 61, SEQ ID NO: 65, SEQ ID NO: 69, SEQ ID NO: 73 and SEQ ID NO: 77 and the heavy chain variable region has three CDRs of a heavy chain variable region set forth as SEQ ID NO: 23, SEQ ID NO: 27, SEQ ID NO: 31, SEQ ID NO: 35, SEQ ID NO: 39, SEQ ID NO: 43, SEQ ID NO: 47, SEQ ID NO: 51, SEQ ID NO: 55, SEQ ID NO:59, SEQ ID NO:
  • the invention comprises a humanized antibody wherein the humanized antibody comprises a light chain variable region (VL) of SEQ ID NO: 101 and a heavy chain variable region (VH) of SEQ ID NO: 103; or a VL of SEQ ID NO: 105 and a VH of SEQ ID NO: 107; or a VL of SEQ ID NO: 109 and a VH of SEQ ID NO: 107; or a VL of SEQ ID NO: 113 and a VH of SEQ ID NO: 115; or a VL of SEQ ID NO: 117 and a VH of SEQ ID NO: 119.
  • these humanized antibodies will comprise site-specific antibodies.
  • such antibodies will comprise an N297A mutation (MJ mutation).
  • the invention will comprise a humanized antibody wherein the antibody comprises a light chain of SEQ ID NO: 130 and a heavy chain of SEQ ID NO: 131; or a light chain of SEQ ID NO: 130 and a heavy chain of SEQ ID NO: 133; or a light chain of SEQ ID NO: 130 and a heavy chain of SEQ ID NO: 135; or a light chain of SEQ ID NO: 136 and a heavy chain of SEQ ID NO: 137; or a light chain of SEQ ID NO: 136 and a heavy chain of SEQ ID NO: 139; or a light chain of SEQ ID NO: 136 and a heavy chain of SEQ ID NO : 141; or a light chain of SEQ ID NO: 142 and a heavy chain of SEQ ID NO: 137; or a light chain of SEQ ID NO: 142 and a heavy chain of SEQ ID NO: 139; or a light chain of SEQ ID NO: 144 and a heavy chain of SEQ ID NO: 131;
  • the antibody comprises a chimeric, CDR grafted, humanized or human antibody or an immunoreactive fragment thereof.
  • the antibody preferably comprising all or part of the aforementioned sequences, is an internalizing antibody.
  • the antibodies will comprise site-specific antibodies.
  • the invention comprises antibody drug conjugates incorporating any of the aforementioned antibodies.
  • the invention comprises a nucleic acid encoding an anti-KREMEN2 antibody of the invention or a fragment thereof.
  • the invention comprises a vector comprising one or more of the above described nucleic acids or a host cell comprising said vector.
  • the present invention also provides anti-KREMEN2 antibody drug conjugates where antibodies as disclosed herein are conjugated to a payload.
  • the antibody drug conjugate, or a pharmaceutically acceptable salt thereof comprises a monoclonal antibody conjugated, linked, or otherwise associated with a cytotoxic agent, wherein the antibody binds to a human KREMEN2 protein.
  • the present invention comprises ADCs that immunopreferentially associate or bind to hKREMEN2.
  • Compatible anti-KREMEN2 antibody drug conjugates (ADCs) of the invention may generally comprise the formula:
  • a) Ab comprises an anti-KREMEN2 antibody
  • L comprises an optional linker
  • c) D comprises a drug
  • n is an integer from about 1 to about 20.
  • the ADCs of the invention comprise an anti-KREMEN2 antibody such as those described above or an immunoreactive fragment thereof.
  • the ADCs of the invention comprise a cytotoxic compound selected from radioisotopes, calicheamicins, pyrrolobenzodiazepines, benzodiazepine derivatives, auristatins, duocarmycins, maytansinoids or an additional therapeutic moiety described herein.
  • the disclosed ADC s will compri se a PBD .
  • pharmaceutical compositions comprising an anti-KREMEN2 ADC as disclosed herein.
  • compositions will comprise a selected drug-antibody ratio (DAR) of greater than about 50%, greater than about 60%, greater than about 70%, greater than about 80%, greater than about 90% or even greater than about 95%.
  • DAR drug-antibody ratio
  • the selected DAR will be two, while in other embodiments the selected DAR will be four and in other embodiments the selected DAR will be six and in yet other embodiments the selected DAR will be eight.
  • Another aspect of the invention is a method of treating cancer comprising administering a pharmaceutical composition such as those described herein to a subject in need thereof.
  • the cancer comprises a hematologic malignancy such as, for example, acute myeloid leukemia or diffuse large B-cell lymphoma.
  • the subject will be suffering from a solid tumor.
  • the cancer is preferably selected from the group consisting of adrenal cancer, liver cancer, kidney cancer, bladder cancer, breast cancer, gastric cancer, ovarian cancer, cervical cancer, uterine cancer, esophageal cancer, colorectal cancer, prostate cancer, pancreatic cancer, lung cancer (both small cell and non-small cell), thyroid cancer and glioblastoma.
  • the subject will be suffering from squamous cell carcinoma of the lung (or squamous cell lung cancer). In other embodiments the subject will be suffering from breast cancer and, in certain embodiments, luminal B breast cancer. Further, in selected embodiments the method of treating cancer described above comprises administering to the subject at least one additional therapeutic moiety besides the anti-KREMEN2 ADCs of the invention.
  • the invention comprises a method of reducing tumor initiating cells in a tumor cell population, wherein the method comprises contacting (e.g. in vitro or in vivo) a tumor initiating cell population with an ADCs or antibodies as described herein whereby the frequency of the tumor initiating cells is reduced.
  • the invention comprises a method of delivering a cytotoxin to a cell comprising contacting the cell with any of the above described ADCs.
  • the invention comprises a method of detecting, diagnosing, or monitoring cancer (e.g., breast cancer or squamous cell lung cancer) in a subject, the method comprising the steps of contacting (e.g. in vitro or in vivo) tumor cells with an KREMEN2 detection agent and detecting the KREMEN2 agent associated with the tumor cells.
  • the detection agent will comprise an anti-KREMEN2 antibody or a nucleic acid probe that associates with a KREMEN2 genotypic determinant.
  • the anti-KREMEN2 antibody may comprise SC78.29 (VL of SEQ ID NO: 53 and VH of SEQ ID NO: 55) or an immunoreactive fragment thereof.
  • the diagnostic method will comprise immunohistochemistry (IHC) or in situ hybridization (ISH).
  • IHC immunohistochemistry
  • ISH in situ hybridization
  • KREMEN2 detection agents may be labeled or associated with effectors, markers or reporters as disclosed below and detected using any one of a number of standard in vivo imaging techniques (e.g., MRI, CAT scan, PET scan, etc.).
  • kits or devices and associated methods that are useful in the diagnosis, monitoring or treatment of KREMEN2 associated disorders such as cancer.
  • the present invention preferably provides an article of manufacture useful for detecting, diagnosing or treating KREMEN2 associated disorders comprising a receptacle containing a KREMEN2 ADC and instructional materials for using said KREMEN2 ADC to treat, monitor or diagnose the KREMEN2 associated disorder or provide a dosing regimen for the same.
  • kits for delivery of a cytotoxin to a cell will comprise the step of contacting at least one circulating tumor cell.
  • the disclosed kits will comprise instructions, labels, inserts, readers or the like indicating that the kit or device is used for the diagnosis, monitoring or treatment of a KREMEN2 associated cancer or provide a dosing regimen for the same.
  • Yet other aspects relate to methods of determining cytotoxicity of an anti-KREMEN2 antibody drug conjugate, or a pharmaceutically acceptable salt thereof.
  • such methods comprise the step of contacting a cancer cell with the antibody drug conjugate ⁇ e.g., an antibody drug conjugate comprising an anti-KREMEN2 antibody conjugated, linked or otherwise associated with a cytotoxic agent).
  • Some aspects further comprise the step of determining killing of the cancer cell.
  • FIG. 1 provides an annotated amino acid sequence of the protein KREMEN2.
  • FIG. 2 shows expression levels of KREMEN2 as measured using whole transcriptome
  • CSC non-tumorigenic cells
  • NTG non-tumorigenic
  • FIG. 3 depicts the relative expression levels of KREMEN2 transcripts as measured by qRT- PCR in RNA samples isolated from normal tissue and from a variety of PDX tumors;
  • FIG. 4 shows the normalized intensity value of KREMEN2 transcript expression measured by microarray hybridization in normal tissues and a variety of PDX cell lines
  • FIG. 5 shows expression of KREMEN2 transcripts in normal tissues and primary tumors from
  • TCGA Cancer Genome Atlas
  • FIGS. 6A - 6J provide annotated amino acid and nucleic acid sequences of murine anti-
  • FIGS. 6 A and 6B show contiguous amino acid sequences of the light chain (FIG. 6A) and heavy chain (FIG. 6B) variable regions (SEQ ID NOS: 21 -81, odd numbers) of exemplary murine anti-KREMEN2 antibodies
  • FIG. 6C shows nucleic acid sequences encoding the aforementioned light and heavy chain variable regions (SEQ ID NOS: 20-80, even numbers)
  • FIGS. 6D and 6E depict, respectively, amino acid sequences and nucleic acid sequences of humanized VL and VH domains of anti-KREMEN2 antibodies
  • FIG. 6F shows amino acid sequences of full length heavy and light chain constructs
  • FIGS. 6G - 6 J depict the CDRs of the light and heavy chain variable regions of the SC78.9, SC78.43, SC78.56 and SC78.59 murine antibodies as determined using Kabat, Chothia, ABM and Contact methodology;
  • FIG. 7 provides, in a tabular form, isotype, binning, affinity and cross reactivity characteristics of exemplary anti-KREMEN2 antibodies
  • FIG. 8 shows that selected anti-KREMEN2 antibodies may interfere with the binding of
  • FIG. 9 demonstrates that the KREMEN2 protein is expressed on the surface of a number of PDX tumor cell lines.
  • FIG. 10 shows expression levels of KREMEN2 on various lung, ovarian and breast PDX tumor cell lines as determined by immunohistochemistry using SC78.29 antibody;
  • FIGS. 11A -l lC demonstrate that the KREMEN2 protein is expressed on primary patient ovarian (FIG. 11 A), lung (FIG. 11B), and breast (FIG. 11C) tumors as determined by immunohistochemistry using SC78.29 antibody;
  • FIGS. 12A - 12C show KREMEN2 protein expression on the surface of NSCLC (FIG. 12A), Ovarian (FIG. 12B), or breast (FIG. 12C), PDX CSC subpopulations (black line) and NTG subpopulations (dotted line) compared to an isotype-control stained population (solid gray), along with tables summarizing the AMFI for these populations;
  • FIG. 13 demonstrates that exemplary KREMEN2 antibodies of the instant invention effectively mediate the delivery and internalization of cytotoxic agents to KREMEN2+ cells;
  • FIGS. 14A and 14B establish that KREMEN2 determinants are associated with tumor initiating cells in exemplary lung (FIG. 14A) and ovarian (FIG. 14B) PDX cell lines as shown by using FACS generated KREMEN2+ tumorigenic cell subpopulations to recapitulate heterogeneous tumors when implanted in immunodeficient mice;
  • FIGS. 15A and 15B demonstrate that certain somatic mutations predict the expression of KREMEN2 in NSCLC PDX tumor cell lines (FIG. 15 A) and that PTCH 1 mutations predict the expression of KREMEN2 in various PDX tumor cell lines (FIG. 15B);
  • FIG. 16 graphically illustrates that KREMEN2 antibody drug conjugates produce durable remissions in lung squamous cell carcinoma, breast, and ovarian cancer PDX-bearing mice.
  • FIG. 17 shows that that KREMEN2 antibody drug conjugates effectively deplete cancer stem cell populations in lung squamous cell carcinoma PDX tumors.
  • NCBI GenBank ® archival sequence database unless otherwise noted.
  • KREMEN2 phenotypic determinants are clinically associated with various proliferative disorders, including neoplasia, and that KREMEN2 protein and variants or isoforms thereof provide useful tumor markers which may be exploited in the treatment of related diseases.
  • the present invention provides antibody drug conjugates comprising an engineered anti-KREMEN2 antibody targeting agent and cytotoxic payload.
  • the disclosed anti- KREMEN2 ADCs are particularly effective at eliminating tumorigenic cells and therefore useful for the treatment and prophylaxis of certain proliferative disorders or the progression or recurrence thereof.
  • KREMEN2 markers or determinants such as cell surface
  • KREMEN2 protein are therapeutically associated with cancer stem cells (also known as tumor perpetuating cells) and may be effectively exploited to eliminate or silence the same.
  • cancer stem cells also known as tumor perpetuating cells
  • the ability to selectively reduce or eliminate cancer stem cells through the use of anti-KREMEN2 conjugates as disclosed herein is surprising in that such cells are known to generally be resistant to many conventional treatments. That is, the effectiveness of traditional, as well as more recent targeted treatment methods, is often limited by the existence and/or emergence of resistant cancer stem cells that are capable of perpetuating tumor growth even in face of these diverse treatment methods. Further, determinants associated with cancer stem cells often make poor therapeutic targets due to low or inconsistent expression, failure to remain associated with the tumorigenic cell or failure to present at the cell surface. In sharp contrast to the teachings of the prior art, the instantly disclosed ADCs and methods effectively overcome this inherent resistance and to specifically eliminate, deplete, silence or promote the differentiation of such cancer stem cells thereby negating their ability to sustain or re-induce the underlying tumor growth.
  • KREMEN2 conjugates such as those disclosed herein may advantageously be used in the treatment and/or prevention of selected proliferative (e.g., neoplastic) disorders or progression or recurrence thereof.
  • proliferative e.g., neoplastic
  • KREMEN2 conjugates such as those disclosed herein may advantageously be used in the treatment and/or prevention of selected proliferative (e.g., neoplastic) disorders or progression or recurrence thereof.
  • Kringle domain-containing transmembrane protein 2 (KREMEN2, also known as KRM2, Kringle-containing protein marking the eye and nose) is a 49 kDa protein that serves as a high- affinity receptor for the Dickkopf homolog 1 protein, DKKl .
  • KREMEN2 co-operates with DKKl to form a ternary complex with LRP6, a co-receptor for Wnt proteins, and this KREMEN2:DKK1 :LRP6 complex is rapidly endocytosed to remove LRP6 from the plasma membrane, modulating Wnt signaling (PMID: 12050670).
  • KREMEN2 protein orthologs include, but are not limited to, human ( P_757384), chimpanzee (XP_009428528), cynomolgus monkey (XP_005591068), rat ( P_001099237) and mouse ( P_082692).
  • the KREMEN2 gene consists of 8 exons spanning approximately 4 kBp at chromosome 16pl3.3.
  • RNA_757384 SEQ ID NO: 1, FIG. 1
  • This protein is comprised of a signal peptide, followed by an extracellular domain consisting of a Kringle domain, a WSC domain (a putative carbohydrate binding domain) and a CUB domain, followed by a transmembrane spanning domain and a cytoplasmic tail.
  • KREMEN2 is a cell surface receptor with shown to have high affinity for DKKl, DKK2, and DKK4 (PMID: 120506705, PMID: 12527209). KREMEN2 complexes with DKKl and LRP6 to interfere with LRP6 interactions with Frizzled and extracellular Wnt proteins, abrogating intracellular Wnt-mediated Wnt/p-catenin signaling and further downregulating the expression of surface LRP6 (PMID: 20543981). Overexpression and knockdown experiments involving KREMEN2 suggest that KREMEN2 is involved in anterior posterior patterning via Wnt signaling inhibition in Xenopus embryogenesis (PMID: 12421700).
  • a tumor comprises non-tumorigenic cells and tumorigenic cells.
  • Non-tumorigenic cells do not have the capacity to self-renew and are incapable of reproducibly forming tumors, even when transplanted into immunocompromised mice in excess cell numbers.
  • Tumorigenic cells also referred to herein as "tumor initiating cells” (TICs), which typically make up a fraction of the tumor's cell population of 0.01-10% , have the ability to form tumors.
  • TICs tumor perpetuating cells (TPCs), referred to interchangeably as cancer stem cells (CSCs), and tumor progenitor cells (TProgs).
  • CSCs like normal stem cells that support cellular hierarchies in normal tissue, are able to self- replicate indefinitely while maintaining the capacity for multilineage differentiation.
  • CSCs are able to generate both tumorigenic progeny and non-tumorigenic progeny and are able to completely recapitulate the heterogeneous cellular composition of the parental tumor as demonstrated by serial isolation and transplantation of low numbers of isolated CSCs into immunocompromised mice.
  • Evidence indicates that unless these "seed cells" are eliminated tumors are much more likely to metastasize or reoccur leading to relapse and ultimate progression of the disease.
  • TProgs like CSCs have the ability to fuel tumor growth in a primary transplant. However, unlike CSCs, they are not able to recapitulate the cellular heterogeneity of the parental tumor and are less efficient at reinitiating tumorigenesis in subsequent transplants because TProgs are typically only capable of a finite number of cell divisions as demonstrated by serial transplantation of low numbers of highly purified TProg into immunocompromised mice. TProgs may further be divided into early TProgs and late TProgs, which may be distinguished by phenotype (e.g., cell surface markers) and their different capacities to recapitulate tumor cell architecture.
  • phenotype e.g., cell surface markers
  • CSCs exhibit higher tumorigenicity and are often relatively more quiescent than: (i) TProgs (both early and late TProgs); and (ii) non-tumorigenic cells such as terminally differentiated tumor cells and tumor-infiltrating cells, for example, fibroblasts/stroma, endothelial and hematopoietic cells that may be derived from CSCs and typically comprise the bulk of a tumor.
  • TProgs both early and late TProgs
  • non-tumorigenic cells such as terminally differentiated tumor cells and tumor-infiltrating cells, for example, fibroblasts/stroma, endothelial and hematopoietic cells that may be derived from CSCs and typically comprise the bulk of a tumor.
  • CSCs are relatively chemoresistant to conventional therapies.
  • Other characteristics that may make CSCs relatively chemoresistant to conventional therapies are increased expression of multi-drug resistance transporters, enhanced DNA repair mechanisms and anti-apoptotic gene expression.
  • Such CSC properties have been implicated in the failure of standard treatment regimens to provide a lasting response in patients with advanced stage neoplasia as standard chemotherapy does not effectively target the CSCs that actually fuel continued tumor growth and recurrence.
  • KREMEN2 expression is associated with various tumorigenic cell subpopulations in a manner which renders them susceptible to treatment as set forth herein.
  • the invention provides anti- KREMEN2 antibodies that may be particularly useful for targeting tumorigenic cells and may be used to silence, sensitize, neutralize, reduce the frequency, block, abrogate, interfere with, decrease, hinder, restrain, control, deplete, moderate, mediate, diminish, reprogram, eliminate, kill or otherwise inhibit (collectively, "inhibit") tumorigenic cells, thereby facilitating the treatment, management and/or prevention of proliferative disorders (e.g. cancer).
  • proliferative disorders e.g. cancer
  • the anti- KREMEN2 antibodies of the invention may be selected so they preferably reduce the frequency or tumorigenicity of tumorigenic cells upon administration to a subject regardless of the form of the KREMEN2 determinant (e.g., phenotypic or genotypic).
  • the reduction in tumorigenic cell frequency may occur as a result of (i) inhibition or eradication of tumorigenic cells; (ii) controlling the growth, expansion or recurrence of tumorigenic cells; (iii) interrupting the initiation, propagation, maintenance, or proliferation of tumorigenic cells; or (iv) by otherwise hindering the survival, regeneration and/or metastasis of the tumorigenic cells.
  • the inhibition of tumorigenic cells may occur as a result of a change in one or more physiological pathways.
  • the change in the pathway whether by inhibition or elimination of the tumorigenic cells, modification of their potential (for example, by induced differentiation or niche disruption) or otherwise interfering with the ability of tumorigenic cells to influence the tumor environment or other cells, allows for the more effective treatment of KREMEN2 associated disorders by inhibiting tumorigenesis, tumor maintenance and/or metastasis and recurrence. It will further be appreciated that the same characteristics of the disclosed antibodies make them particularly effective at treating recurrent tumors which have proved resistant or refractory to standard treatment regimens.
  • Methods that can be used to assess the reduction in the frequency of tumorigenic cells include but are not limited to, cytometric or immunohistochemical analysis, preferably by in vitro or in vivo limiting dilution analysis (Dylla et al. 2008, PMID: PMC2413402 and Hoey et al. 2009, PMID: 19664991).
  • In vitro limiting dilution analysis may be performed by culturing fractionated or unfractionated tumor cells (e.g. from treated and untreated tumors, respectively) on solid medium that fosters colony formation and counting and characterizing the colonies that grow.
  • the tumor cells can be serially diluted onto plates with wells containing liquid medium and each well can be scored as either positive or negative for colony formation at any time after inoculation but preferably more than 10 days after inoculation.
  • In vivo limiting dilution is performed by transplanting tumor cells, from either untreated controls or from tumors exposed to selected therapeutic agents, into immunocompromised mice in serial dilutions and subsequently scoring each mouse as either positive or negative for tumor formation.
  • the scoring may occur at any time after the implanted tumors are detectable but is preferably done 60 or more days after the transplant.
  • the analysis of the results of limiting dilution experiments to determine the frequency of tumorigenic cells is preferably done using Poisson distribution statistics or assessing the frequency of predefined definitive events such as the ability to generate tumors in vivo or not (Fazekas et al., 1982, PMTD: 7040548).
  • Flow cytometry and immunohistochemistry may also be used to determine tumorigenic cell frequency. Both techniques employ one or more antibodies or reagents that bind art recognized cell surface proteins or markers known to enrich for tumorigenic cells (see WO 2012/031280). As known in the art, flow cytometry (e.g. florescence activated cell sorting (FACS)) can also be used to characterize, isolate, purify, enrich or sort for various cell populations including tumorigenic cells. Flow cytometry measures tumorigenic cell levels by passing a stream of fluid, in which a mixed population of cells is suspended, through an electronic detection apparatus which is able to measure the physical and/or chemical characteristics of up to thousands of particles per second. Immunohistochemistry provides additional information in that it enables visualization of tumorigenic cells in situ (e.g., in a tissue section) by staining the tissue sample with labeled antibodies or reagents which bind to tumorigenic cell markers.
  • FACS florescence activated cell sorting
  • the antibodies of the invention may be useful for identifying, characterizing, monitoring, isolating, sectioning or enriching populations or subpopulations of tumorigenic cells through methods such as, for example, flow cytometry, magnetic activated cell sorting (MACS), laser mediated sectioning or FACS.
  • FACS is a reliable method used to isolate cell subpopulations at more than 99.5% purity based on specific cell surface markers.
  • Other compatible techniques for the characterization and manipulation of tumorigenic cells including CSCs can be seen, for example, in U.S.P.N.s 12/686,359, 12/669,136 and 12/757,649.
  • markers that have been associated with CSC populations and have been used to isolate or characterize CSCs ABCAl, ABCA3, ABCB5, ABCG2, ADAM9, ADCY9, ADORA2A, ALDH, AFP, AXIN1, B7H3, BCL9, Bmi-1, BMP-4, C20orf52, C4.4A, carboxypeptidase M, CAV1, CAV2, CD105, CD117, CD123, CD133, CD14, CD16, CD166, CD16a, CD16b, CD2, CD20, CD24, CD29, CD3, CD31, CD324, CD325, CD33, CD34, CD38, CD44, CD45, CD46, CD49b, CD49f, CD56, CD64, CD74, CD9, CD90, CD96, CEACAM6, CELSR1, CLEC12A, CPD, CRIM1, CX3CL1, CXCR4, DAF, decorin, easyhl, easyh2, EDG3, EGFR, E PP1, EPCAM,
  • non-limiting examples of cell surface phenotypes associated with CSCs of certain tumor types include DA ⁇ DIA 1 TM , ALDH + , CD133 + , CD123 + , CD34 + CD38 " , CD44 + CD24 “ , D46 C 24 + D66c , CD133 + CD34 + CD10XD19 ⁇ , CD138 " CD34 " CD19 + , CD133 + RC2 + , ⁇ 44 + ⁇ 2 ⁇ 3 ⁇ 4 ⁇ 133 + , CD44 + CD24 + ESA + , CD271 + , ABCB5 + as well as other CSC surface phenotypes that are known in the art.
  • CSC preparations comprising CD46 M CD324 + phenotypes in solid tumors and CD34 + CD38 " in leukemias.
  • “Positive,” “low” and “negative” expression levels as they apply to markers or marker phenotypes are defined as follows.
  • Cells with negative expression i.e.”-
  • fluorescence minus one or "FMO" staining.
  • Cells with expression greater than the 95th percentile of expression observed with an isotype control antibody using the FMO staining procedure described above are herein defined as "positive” (i.e.”+”). As defined herein there are various populations of cells broadly defined as “positive.”
  • a cell is defined as positive if the mean observed expression of the antigen is above the 95th percentile determined using FMO staining with an isotype control antibody as described above.
  • the positive cells may be termed cells with low expression (i.e. "lo") if the mean observed expression is above the 95 th percentile determined by FMO staining and is within one standard deviation of the 95 th percentile.
  • the positive cells may be termed cells with high expression (i.e.
  • the 99th percentile may preferably be used as a demarcation point between negative and positive FMO staining and in some embodiments the percentile may be greater than 99%.
  • the CD46 M CD324 + or CD34 + CD38 " marker phenotype and those exemplified immediately above may be used in conjunction with standard flow cytometric analysis and cell sorting techniques to characterize, isolate, purify or enrich TIC and/or TPC cells or cell populations for further analysis.
  • the ability of the antibodies of the current invention to reduce the frequency of tumorigenic cells can therefore be determined using the techniques and markers described above.
  • the anti-KREMEN2 antibodies may reduce the frequency of tumorigenic cells by 10%>, 15%), 20%), 25%), 30%) or even by 35%.
  • the reduction in frequency of tumorigenic cells may be in the order of 40%, 45%, 50%, 55%, 60% or 65%.
  • the disclosed compounds may reduce the frequency of tumorigenic cells by 70%, 75%), 80%), 85%o, 90%) or even 95%. It will be appreciated that any reduction of the frequency of tumorigenic cells is likely to result in a corresponding reduction in the tumorigenicity, persistence, recurrence and aggressiveness of the neoplasia.
  • Antibodies and variants and derivatives thereof including accepted nomenclature and numbering systems, have been extensively described, for example, in Abbas et al. (2010), Cellular and Molecular Immunology (6 th Ed.), W.B. Saunders Company; or Murphey et al. (2011), Janeway's Immunobiology (8 th Ed ), Garland Science.
  • an “antibody” or “intact antibody” typically refers to a Y-shaped tetrameric protein comprising two heavy (H) and two light (L) polypeptide chains held together by covalent disulfide bonds and non-covalent interactions. Each light chain is composed of one variable domain (VL) and one constant domain (CL). Each heavy chain comprises one variable domain (VH) and a constant region, which in the case of IgG, IgA, and IgD antibodies, comprises three domains termed CHI, CH2, and CH3 (IgM and IgE have a fourth domain, CH4).
  • IgG, IgA, and IgD classes the CHI and CH2 domains are separated by a flexible hinge region, which is a proline and cysteine rich segment of variable length (from about 10 to about 60 amino acids in various IgG subclasses).
  • the variable domains in both the light and heavy chains are joined to the constant domains by a "J" region of about 12 or more amino acids and the heavy chain also has a "D" region of about 10 additional amino acids.
  • Each class of antibody further comprises inter-chain and intra-chain disulfide bonds formed by paired cysteine residues.
  • antibody includes polyclonal antibodies, multi clonal antibodies, monoclonal antibodies, chimeric antibodies, humanized and primatized antibodies, CDR grafted antibodies, human antibodies (including recombinantly produced human antibodies), recombinantly produced antibodies, intrabodies, multispecific antibodies, bispecific antibodies, monovalent antibodies, multivalent antibodies, anti -idiotypic antibodies, synthetic antibodies, including muteins and variants thereof, immunospecific antibody fragments such as Fd, Fab, F(ab') 2 , F(ab') fragments, single-chain fragments (e.g.
  • the term further comprises all classes of antibodies (i.e. IgA, IgD, IgE, IgG, and IgM) and all subclasses (i.e., IgGl, IgG2, IgG3, IgG4, IgAl, and IgA2).
  • Heavy-chain constant domains that correspond to the different classes of antibodies are typically denoted by the corresponding lower case Greek letter ⁇ , ⁇ , ⁇ , ⁇ , and ⁇ , respectively.
  • Light chains of the antibodies from any vertebrate species can be assigned to one of two clearly distinct types, called kappa ( ⁇ ) and lambda ( ⁇ ), based on the amino acid sequences of their constant domains.
  • variable domains of antibodies show considerable variation in amino acid composition from one antibody to another and are primarily responsible for antigen recognition and binding. Variable regions of each light/heavy chain pair form the antibody binding site such that an intact IgG antibody has two binding sites (i.e. it is bivalent). VH and VL domains comprise three regions of extreme variability, which are termed hypervariable regions, or more commonly, complementarity-determining regions (CDRs), framed and separated by four less variable regions known as framework regions (FRs). Non-covalent association between the VH and the VL region forms the Fv fragment (for "fragment variable") which contains one of the two antigen-binding sites of the antibody.
  • CDRs complementarity-determining regions
  • FRs framework regions
  • the assignment of amino acids to each domain, framework region and CDR may be in accordance with one of the schemes provided by Kabat et al (1991) Sequences of Proteins of Immunological Interest (5 th Ed.), US Dept. of Health and Human Services, PHS, NIH, NIH Publication no. 91-3242; Chothia et al, 1987, PMID: 3681981; Chothia et al, 1989, PMID: 2687698; MacCallum et al, 1996, PMID: 8876650; or Dub el, Ed.
  • variable region residue numbering is typically as set forth in Chothia or Kabat. Amino acid residues which comprise CDRs as defined by Kabat, Chothia, MacCallum (also known as Contact) and AbM as obtained from the Abysis website database (infra.) are set out below in Table 1. Note that MacCallum uses the Chothia numbering system.
  • Variable regions and CDRs in an antibody sequence can be identified according to general rules that have been developed in the art (as set out above, such as, for example, the Kabat numbering system) or by aligning the sequences against a database of known variable regions. Methods for identifying these regions are described in Kontermann and Dubel, eds., Antibody Engineering, Springer, New York, NY, 2001 and Dinarello et al, Current Protocols in Immunology, John Wiley and Sons Inc., Hoboken, NJ, 2000. Exemplary databases of antibody sequences are described in, and can be accessed through, the "Abysis" website at www.bioinf.org.uk/abs (maintained by A.C.
  • the sequences are analyzed using the Abysis database, which integrates sequence data from Kabat, EVIGT and the Protein Data Bank (PDB) with structural data from the PDB. See Dr. Andrew C. R. Martin's book chapter Protein Sequence and Structure Analysis of Antibody Variable Domains. In: Antibody Engineering Lab Manual (Ed. : Duebel, S. and Kontermann, R., Springer- Verlag, Heidelberg, ISBN-13 : 978-3540413547, also available on the website bioinforg.uk/abs).
  • the Abysis database website further includes general rules that have been developed for identifying CDRs which can be used in accordance with the teachings herein.
  • RTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDS KDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRGEC (SEQ ID NO: 5).
  • QPKANPTVTLFPPSSEELQANKATLVCLISDFYPGAVTVAWKADGSPVKAGVETTKPSKQS NNKYAASSYLSLTPEQWKSHRSYSCQVTHEGSTVEKTVAPTECS SEQ ID NO: 8).
  • IgGl heavy chain constant region amino acid sequence compatible with the present invention is set forth immediately below: ASTKGP S VFPLAP S SK ST SGGT AALGCLVKD YFPEP VT VS WNSGALT SGVHTFP AVLQ S SGL YSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVF LFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYR VVSVLTVLHQDWLNGKEYKCKVS KALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQ VSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVF SCSVMHEALHNHYTQKSLSPG (SEQ ID NO: 2).
  • heavy and light chain constant region sequences either wild-type (e.g., see SEQ ID NOS: 2, 5 or 8) or engineered as disclosed herein to provide unpaired cysteines (e.g., see SEQ ID NOS: 3, 4, 6, 7, 9 or 10) may be operably associated with the disclosed heavy and light chain variable regions using standard molecular biology techniques to provide full-length antibodies that may be incorporated in the KREMEN2 antibody drug conjugates of the instant invention. Sequences of full-length heavy and light chains comprising selected antibodies of the instant invention are set forth in FIG. 6F appended hereto.
  • interchain and intrachain disulfide bonds There are two types of disulfide bridges or bonds in immunoglobulin molecules: interchain and intrachain disulfide bonds. As is well known in the art the location and number of interchain disulfide bonds vary according to the immunoglobulin class and species. While the invention is not limited to any particular class or subclass of antibody, the IgGl immunoglobulin shall be used throughout the instant disclosure for illustrative purposes. In wild-type IgGl molecules there are twelve intrachain disulfide bonds (four on each heavy chain and two on each light chain) and four interchain disulfide bonds. Intrachain disulfide bonds are generally somewhat protected and relatively less susceptible to reduction than interchain bonds.
  • interchain disulfide bonds are located on the surface of the immunoglobulin, are accessible to solvent and are usually relatively easy to reduce.
  • Two interchain disulfide bonds exist between the heavy chains and one from each heavy chain to its respective light chain. It has been demonstrated that interchain disulfide bonds are not essential for chain association.
  • the IgGl hinge region contain the cysteines in the heavy chain that form the interchain disulfide bonds, which provide structural support along with the flexibility that facilitates Fab movement.
  • the heavy/heavy IgGl interchain disulfide bonds are located at residues C226 and C229 (Eu numbering) while the IgGl interchain disulfide bond between the light and heavy chain of IgGl (heavy/light) are formed between C214 of the kappa or lambda light chain and C220 in the upper hinge region of the heavy chain.
  • Antibodies of the invention can be produced using a variety of methods known in the art.
  • polyclonal antibodies in various host animals is well known in the art (see for example, Harlow and Lane (Eds.) (1988) Antibodies: A Laboratory Manual, CSH Press; and Harlow et al. (1989) Antibodies, NY, Cold Spring Harbor Press).
  • an immunocompetent animal e.g., mouse, rat, rabbit, goat, non-human primate, etc.
  • an antigenic protein or cells or preparations comprising an antigenic protein.
  • polyclonal antibody-containing serum is obtained by bleeding or sacrificing the animal.
  • the serum may be used in the form obtained from the animal or the antibodies may be partially or fully purified to provide immunoglobulin fractions or isolated antibody preparations.
  • antibodies of the invention may be generated from any KREMEN2 determinant that induces an immune response in an immunocompetent animal.
  • determinant or “target” means any detectable trait, property, marker or factor that is identifiably associated with, or specifically found in or on a particular cell, cell population or tissue. Determinants or targets may be morphological, functional or biochemical in nature and are preferably phenotypic.
  • a determinant is a protein that is differentially expressed (over- or under-expressed) by specific cell types or by cells under certain conditions (e.g., during specific points of the cell cycle or cells in a particular niche).
  • a determinant preferably is differentially expressed on aberrant cancer cells and may comprise a KREMEN2 protein, or any of its splice variants, isoforms, homologs or family members, or specific domains, regions or epitopes thereof.
  • An "antigen”, “immunogenic determinant”, “antigenic determinant” or “immunogen” means any KREMEN2 protein or any fragment, region or domain thereof that can stimulate an immune response when introduced into an immunocompetent animal and is recognized by the antibodies produced by the immune response.
  • the presence or absence of the KREMEN2 determinants contemplated herein may be used to identify a cell, cell subpopulation or tissue (e.g., tumors, tumorigenic cells or CSCs).
  • antigen any form of antigen, or cells or preparations containing the antigen, can be used to generate an antibody that is specific for the KREMEN2 determinant.
  • antigen is used in a broad sense and may comprise any immunogenic fragment or determinant of the selected target including a single epitope, multiple epitopes, single or multiple domains or the entire extracellular domain (ECD) or protein.
  • the antigen may be an isolated full-length protein, a cell surface protein (e.g., immunizing with cells expressing at least a portion of the antigen on their surface), or a soluble protein (e.g., immunizing with only the ECD portion of the protein) or protein construct (e.g., Fc-antigen).
  • the antigen may be produced in a genetically modified cell. Any of the aforementioned antigens may be used alone or in combination with one or more immunogenicity enhancing adjuvants known in the art.
  • DNA encoding the antigen may be genomic or non-genomic (e.g., cDNA) and may encode at least a portion of the ECD, sufficient to elicit an immunogenic response.
  • Any vectors may be employed to transform the cells in which the antigen is expressed, including but not limited to adenoviral vectors, lentiviral vectors, plasmids, and non- viral vectors, such as cationic lipids.
  • the invention contemplates use of monoclonal antibodies.
  • monoclonal antibody or “mAb” refers to an antibody obtained from a population of substantially homogeneous antibodies, i.e., the individual antibodies comprising the population are identical except for possible mutations (e.g., naturally occurring mutations), that may be present in minor amounts.
  • Monoclonal antibodies can be prepared using a wide variety of techniques known in the art including hybridoma techniques, recombinant techniques, phage display technologies, transgenic animals (e.g., a XenoMouse ® ) or some combination thereof.
  • monoclonal antibodies can be produced using hybridoma and biochemical and genetic engineering techniques such as described in more detail in An, Zhigiang (ed.) Therapeutic Monoclonal Antibodies: From Bench to Clinic, John Wiley and Sons, 1 st ed. 2009; Shire et. al. (eds.) Current Trends in Monoclonal Antibody Development and Manufacturing, Springer Science + Business Media LLC, 1 st ed.
  • the antibodies may comprise fully human antibodies.
  • human antibody refers to an antibody which possesses an amino acid sequence that corresponds to that of an antibody produced by a human and/or has been made using any of the techniques for making human antibodies described below.
  • Human antibodies can be produced using various techniques known in the art.
  • One technique is phage display in which a library of (preferably human) antibodies is synthesized on phages, the library is screened with the antigen of interest or an antibody -binding portion thereof, and the phage that binds the antigen is isolated, from which one may obtain the immunoreactive fragments.
  • Methods for preparing and screening such libraries are well known in the art and kits for generating phage display libraries are commercially available (e.g., the Pharmacia Recombinant Phage Antibody System, catalog no. 27-9400-01; and the Stratagene SurfZAPTM phage display kit, catalog no. 240612).
  • recombinant human antibodies may be isolated by screening a recombinant combinatorial antibody library prepared as above.
  • the library is a scFv phage display library, generated using human VL and VH cDNAs prepared from mRNA isolated from B-cells.
  • the antibodies produced by naive libraries can be of moderate affinity (K a of about 10 6 to 10 7 M "1 ), but affinity maturation can also be mimicked in vitro by constructing and reselecting from secondary libraries as described in the art. For example, mutation can be introduced at random in vitro by using error-prone polymerase (reported in Leung et al., Technique, 1 : 11-15 (1989)).
  • affinity maturation can be performed by randomly mutating one or more CDRs, e.g. using PCR with primers carrying random sequence spanning the CDR of interest, in selected individual Fv clones and screening for higher-affinity clones.
  • WO 9607754 described a method for inducing mutagenesis in a CDR of an immunoglobulin light chain to create a library of light chain genes.
  • Another effective approach is to recombine the VH or VL domains selected by phage display with repertoires of naturally occurring V domain variants obtained from unimmunized donors and to screen for higher affinity in several rounds of chain reshuffling as described in Marks et al., Biotechnol., 10: 779-783 (1992).
  • This technique allows the production of antibodies and antibody fragments with a dissociation constant K D (k 0ff /k on ) of about 10 "9 M or less.
  • eukaryotic cells e.g., yeast
  • the human antibody is selected from a phage library, where that phage library expresses human antibodies (Vaughan et al. Nature Biotechnology 14:309-314 (1996): Sheets et al. Proc. Natl. Acad. Sci. USA 95:6157-6162 (1998).
  • human binding pairs may be isolated from combinatorial antibody libraries generated in eukaryotic cells such as yeast. See e.g., U. S.P.N. 7,700,302.
  • Such techniques advantageously allow for the screening of large numbers of candidate modulators and provide for relatively easy manipulation of candidate sequences (e.g., by affinity maturation or recombinant shuffling).
  • Human antibodies can also be made by introducing human immunoglobulin loci into transgenic animals, e.g., mice in which the endogenous immunoglobulin genes have been partially or completely inactivated and human immunoglobulin genes have been introduced. Upon challenge, human antibody production is observed, which closely resembles that seen in humans in all respects, including gene rearrangement, assembly, and antibody repertoire.
  • This approach is described, for example, in U.S.P.Ns. 5,545,807; 5,545,806; 5,569,825; 5,625, 126; 5,633,425; 5,661,016, and U.S.P.Ns. 6,075, 181 and 6,150,584 regarding XenoMouse ® technology; and Lonberg and Huszar, Intern.
  • the human antibody may be prepared via immortalization of human B lymphocytes producing an antibody directed against a target antigen (such B lymphocytes may be recovered from an individual suffering from a neoplastic disorder or may have been immunized in vitro). See, e.g., Cole et al, Monoclonal Antibodies and Cancer Therapy, Alan R. Liss, p. 77 (1985); Boerner et al., J. Immunol, 147 (1): 86- 95 (1991); and U.S.P.N. 5,750,373.
  • the human antibody sequence may be fabricated using art-known molecular engineering techniques and introduced into expression systems and host cells as described herein.
  • Such non-natural recombinantly produced human antibodies (and subject compositions) are entirely compatible with the teachings of this disclosure and are expressly held to be within the scope of the instant invention.
  • the KREMEN2 ADCs of the invention will comprise a recombinantly produced human antibody acting as a cell binding agent.
  • source antibodies may be further altered to provide anti-KREMEN2 antibodies having improved pharmaceutical characteristics.
  • the source antibodies are modified or altered using known molecular engineering techniques to provide derived antibodies having the desired therapeutic properties.
  • Selected embodiments of the invention comprise murine monoclonal antibodies that immunospecifically bind to KREMEN2 and which can be considered “source” antibodies.
  • antibodies of the invention can be derived from such "source” antibodies through optional modification of the constant region and/or the epitope-binding amino acid sequences of the source antibody.
  • an antibody is "derived” from a source antibody if selected amino acids in the source antibody are altered through deletion, mutation, substitution, integration or combination.
  • a "derived” antibody is one in which fragments of the source antibody (e.g., one or more CDRs or domains or the entire heavy and light chain variable regions) are combined with or incorporated into an acceptor antibody sequence to provide the derivative antibody (e.g.
  • derived antibodies can be generated using genetic material from the antibody producing cell and standard molecular biological techniques as described below, such as, for example, to improve affinity for the determinant; to improve antibody stability; to improve production and yield in cell culture; to reduce immunogenicity in vivo; to reduce toxicity; to facilitate conjugation of an active moiety; or to create a multispecific antibody.
  • Such antibodies may also be derived from source antibodies through modification of the mature molecule (e.g., glycosylation patterns or pegylation) by chemical means or post-translational modification.
  • the antibodies of the invention comprise chimeric antibodies that are derived from protein segments from at least two different species or class of antibodies that have been covalently joined.
  • the term "chimeric" antibody is directed to constructs in which a portion of the heavy and/or light chain is identical or homologous to corresponding sequences in antibodies from a particular species or belonging to a particular antibody class or subclass, while the remainder of the chain(s) is identical or homologous to corresponding sequences in antibodies from another species or belonging to another antibody class or subclass, as well as fragments of such antibodies (U.S. P.N. 4,816,567).
  • chimeric antibodies of the instant invention may comprise all or most of the selected murine heavy and light chain variable regions operably linked to human light and heavy chain constant regions.
  • anti-KREMEN2 antibodies may be "derived" from the mouse antibodies disclosed herein and comprise less than the entire heavy and light chain variable regions.
  • chimeric antibodies of the invention are "CDR-grafted" antibodies, where the CDRs (as defined using Kabat, Chothia, McCallum, etc.) are derived from a particular species or belonging to a particular antibody class or subclass, while the remainder of the antibody is largely derived from an antibody from another species or belonging to another antibody class or subclass.
  • CDRs as defined using Kabat, Chothia, McCallum, etc.
  • rodent CDRs e.g., mouse CDRs
  • the CDR grafted antibodies will comprise one or more CDRs obtained from a mouse incorporated in a human framework sequence. Similar to the CDR-grafted antibody is a "humanized” antibody.
  • a "humanized” antibody is a human antibody (acceptor antibody) comprising one or more amino acid sequences (e.g. CDR sequences) derived from one or more non-human antibodies (donor or source antibody).
  • back mutations can be introduced into the humanized antibody, in which residues in one or more FRs of the variable region of the recipient human antibody are replaced by corresponding residues from the non-human species donor antibody. Such back mutations may to help maintain the appropriate three-dimensional configuration of the grafted CDR(s) and thereby improve affinity and antibody stability.
  • Antibodies from various donor species may be used including, without limitation, mouse, rat, rabbit, or non-human primate.
  • humanized antibodies may comprise new residues that are not found in the recipient antibody or in the donor antibody to, for example, further refine antibody performance.
  • CDR grafted and humanized antibodies compatible with the instant invention comprising murine components from source antibodies and human components from acceptor antibodies may be provided as set forth in the Examples below.
  • V-BASE directory (VBASE2 - Retter et al, Nucleic Acid Res. 33; 671-674, 2005) which provides a comprehensive directory of human immunoglobulin variable region sequences (compiled by Tomlinson, I. A. et al. MRC Centre for Protein Engineering, Cambridge, UK) may also be used to identify compatible acceptor sequences. Additionally, consensus human framework sequences described, for example, in U. S.P.N. 6,300,064 may also prove to be compatible acceptor sequences are can be used in accordance with the instant teachings.
  • human framework acceptor sequences are selected based on homology with the murine source framework sequences along with an analysis of the CDR canonical structures of the source and acceptor antibodies.
  • the derived sequences of the heavy and light chain variable regions of the derived antibody may then be synthesized using art recognized techniques.
  • CDR grafted and humanized antibodies, and associated methods are described in U.S.P.Ns. 6, 180,370 and 5,693,762. For further details, see, e.g., Jones et al, 1986, (PMID: 3713831); and U.S.P.Ns. 6,982,321 and 7,087,409.
  • sequence identity or homology of the CDR grafted or humanized antibody variable region to the human acceptor variable region may be determined as discussed herein and, when measured as such, will preferably share at least 60% or 65% sequence identity, more preferably at least 70%, 75%, 80%, 85%, or 90% sequence identity, even more preferably at least 93%, 95%, 98%) or 99%) sequence identity.
  • residue positions which are not identical differ by conservative amino acid substitutions.
  • a "conservative amino acid substitution” is one in which an amino acid residue is substituted by another amino acid residue having a side chain (R group) with similar chemical properties (e.g., charge or hydrophobicity).
  • R group side chain
  • a conservative amino acid substitution will not substantially change the functional properties of a protein.
  • the percent sequence identity or degree of similarity may be adjusted upwards to correct for the conservative nature of the substitution.
  • FIGS. 6A and 6B are defined as per Kabat et al. using a proprietary Abysis database.
  • FIGS.6G - 6J one skilled in the art could readily identify CDRs in accordance with definitions provided by Chothia et al., ABM or MacCallum et al as well as Kabat et al.
  • anti-KREMEN2 humanized antibodies comprising one or more CDRs derived according to any of the aforementioned systems are explicitly held to be within the scope of the instant invention.
  • the antibodies of the instant invention may be engineered to facilitate conjugation to a cytotoxin or other anti-cancer agent (as discussed in more detail below). It is advantageous for the antibody drug conjugate (ADC) preparation to comprise a homogenous population of ADC molecules in terms of the position of the cytotoxin on the antibody and the drug to antibody ratio (DAR). Based on the instant disclosure one skilled in the art could readily fabricate site-specific engineered constructs as described herein.
  • a "site-specific antibody” or “site- specific construct” means an antibody, or immunoreactive fragment thereof, wherein at least one amino acid in either the heavy or light chain is deleted, altered or substituted (preferably with another amino acid) to provide at least one free cysteine.
  • a "site-specific conjugate” shall be held to mean an ADC comprising a site-specific antibody and at least one cytotoxin or other compound (e.g., a reporter molecule) conjugated to the unpaired or free cysteine(s).
  • the unpaired cysteine residue will comprise an unpaired intrachain cysteine residue.
  • the free cysteine residue will comprise an unpaired interchain cysteine residue.
  • the free cysteine may be engineered into the amino acid sequence of the antibody (e.g., in the CH3 domain).
  • the site-specific antibody can be of various isotypes, for example, IgG, IgE, IgA or IgD; and within those classes the antibody can be of various subclasses, for example, IgGl, IgG2, IgG3 or IgG4.
  • the light chain of the antibody can comprise either a kappa or lambda isotype each incorporating a C214 that, in selected embodiments, may be unpaired due to a lack of a C220 residue in the IgGl heavy chain.
  • free cysteine or “unpaired cysteine” may be used interchangeably unless otherwise dictated by context and shall mean any cysteine (or thiol containing) constituent (e.g., a cysteine residue) of an antibody, whether naturally present or specifically incorporated in a selected residue position using molecular engineering techniques, that is not part of a naturally occurring (or “native") disulfide bond under physiological conditions.
  • the free cysteine may comprise a naturally occurring cysteine whose native interchain or intrachain disulfide bridge partner has been substituted, eliminated or otherwise altered to disrupt the naturally occurring disulfide bridge under physiological conditions thereby rendering the unpaired cysteine suitable for site-specific conjugation.
  • the free or unpaired cysteine will comprise a cysteine residue that is selectively placed at a predetermined site within the antibody heavy or light chain amino acid sequences.
  • free or unpaired cysteines may be present as a thiol (reduced cysteine), as a capped cysteine (oxidized) or as part of a non-native intra- or intermolecular disulfide bond (oxidized) with another cysteine or thiol group on the same or different molecule depending on the oxidation state of the system.
  • mild reduction of the appropriately engineered antibody construct will provide thiols available for site-specific conjugation.
  • the free or unpaired cysteines (whether naturally occurring or incorporated) will be subject to selective reduction and subsequent conjugation to provide homogenous DAR compositions.
  • the favorable properties exhibited by the disclosed engineered conjugate preparations is predicated, at least in part, on the ability to specifically direct the conjugation and largely limit the fabricated conjugates in terms of conjugation position and the absolute DAR value of the composition.
  • the present invention need not rely entirely on partial or total reduction of the antibody to provide random conjugation sites and relatively uncontrolled generation of DAR species.
  • the present invention preferably provides one or more predetermined unpaired (or free) cysteine sites by engineering the targeting antibody to disrupt one or more of the naturally occurring (i.e., "native") interchain or intrachain disulfide bridges or to introduce a cysteine residue at any position.
  • a cysteine residue may be incorporated anywhere along the antibody (or immunoreactive fragment thereof) heavy or light chain or appended thereto using standard molecular engineering techniques.
  • disruption of native disulfide bonds may be effected in combination with the introduction of a non-native cysteine (which will then comprise the free cysteine) that may then be used as a conjugation site.
  • the engineered antibody comprises at least one amino acid deletion or substitution of an intrachain or interchain cysteine residue.
  • intrachain cysteine residue means a cysteine residue that is involved in a native disulfide bond either between the light and heavy chain of an antibody or between the two heavy chains of an antibody while an "intrachain cysteine residue” is one naturally paired with another cysteine in the same heavy or light chain.
  • the deleted or substituted interchain cysteine residue is involved in the formation of a disulfide bond between the light and heavy chain.
  • the deleted or substituted cysteine residue is involved in a disulfide bond between the two heavy chains.
  • an interchain cysteine residue is deleted.
  • an interchain cysteine is substituted for another amino acid (e.g., a naturally occurring amino acid).
  • the amino acid substitution can result in the replacement of an interchain cysteine with a neutral (e.g. serine, threonine or glycine) or hydrophilic (e.g. methionine, alanine, valine, leucine or isoleucine) residue.
  • a neutral e.g. serine, threonine or glycine
  • hydrophilic e.g. methionine, alanine, valine, leucine or isoleucine
  • the deleted or substituted cysteine residue is on the light chain (either kappa or lambda) thereby leaving a free cysteine on the heavy chain. In other embodiments the deleted or substituted cysteine residue is on the heavy chain leaving the free cysteine on the light chain constant region.
  • cysteine at position 214 (C214) of the IgG light chain is deleted or substituted.
  • cysteine at position 220 (C220) on the IgG heavy chain is deleted or substituted.
  • cysteine at position 226 or position 229 on the heavy chain is deleted or substituted.
  • C220 on the heavy chain is substituted with serine (C220S) to provide the desired free cysteine in the light chain.
  • C214 in the light chain is substituted with serine (C214S) to provide the desired free cysteine in the heavy chain.
  • Exemplary engineered light and heavy chain constant regions compatible with site-specific constructs of the instant invention are set forth immediately below where SEQ ID NOS: 3 and 4 comprise, respectively, C220S IgGl and C220A IgGl heavy chain constant regions, SEQ ID NOS: 6 and 7 comprise, respectively, C214S and C214A kappa light chain constant regions and SEQ ID NOS: 9 and 10 comprise, respectively, exemplary C214S and C214A lambda light chain constant regions.
  • SEQ ID NOS: 3 and 4 comprise, respectively, C220S IgGl and C220A IgGl heavy chain constant regions
  • SEQ ID NOS: 6 and 7 comprise, respectively, C214S and C214A kappa light chain constant regions
  • SEQ ID NOS: 9 and 10 comprise, respectively, exemplary C214S and C214A lambda light chain constant regions.
  • the site of the altered or deleted amino acid is underlined.
  • each of the heavy and light chain variants may be operably associated with the disclosed heavy and light chain variable regions (or derivatives thereof such as humanized or CDR grafted constructs) to provide site-specific anti-KREMEN2 antibodies as disclosed herein.
  • Such engineered antibodies are particularly compatible for use in the disclosed ADCs.
  • cysteine(s) may be introduced in the CHI domain, the CH2 domain or the CH3 domain or any combination thereof depending on the desired DAR, the antibody construct, the selected payload and the antibody target.
  • cysteines may be introduced into a kappa or lambda CL domain and, in particularly preferred embodiments, in the c- terminal region of the CL domain.
  • substituted residues occur at any accessible sites of the antibody.
  • reactive thiol groups are thereby positioned at readily accessible sites on the antibody and may be selectively reduced as described further herein.
  • the substituted residues occur at accessible sites of the antibody.
  • reactive thiol groups are thereby positioned at accessible sites of the antibody and may be used to selectively conjugate the antibody.
  • any one or more of the following residues may be substituted with cysteine: V205 (Kabat numbering) of the light chain; A118 (Eu numbering) of the heavy chain; and S400 (Eu numbering) of the heavy chain Fc region. Additional substitution positions and methods of fabricating compatible site-specific antibodies are set forth in U.S.P.N. 7,521,541 which is incorporated herein in its entirety.
  • Selected embodiments of the present invention may also comprise substitutions or modifications of the constant region (i.e. the Fc region), including without limitation, amino acid residue substitutions, mutations and/or modifications, which result in a compound with characteristics including, but not limited to: altered pharmacokinetics, increased serum half-life, increase binding affinity, reduced immunogenicity, increased production, altered Fc ligand binding to an Fc receptor (FcR), enhanced or reduced ADCC or CDC, altered glycosylation and/or disulfide bonds and modified binding specificity.
  • the constant region i.e. the Fc region
  • FcyRI, FcyRIIA and B, FcyRIII and FcRn an Fc receptor
  • FcyRI, FcyRIIA and B, FcyRIII and FcRn an Fc receptor
  • cytotoxicity and/or altered pharmacokinetics such as increased serum half-life
  • antibodies with increased in vivo half-lives can be generated by modifying (e.g., substituting, deleting or adding) amino acid residues identified as involved in the interaction between the Fc domain and the FcRn receptor (see, e.g., International Publication Nos. WO 97/34631; WO 04/029207; U.S.P.N. 6,737,056 and U.S.P.N. 2003/0190311).
  • Fc variants may provide half-lives in a mammal, preferably a human, of greater than 5 days, greater than 10 days, greater than 15 days, preferably greater than 20 days, greater than 25 days, greater than 30 days, greater than 35 days, greater than 40 days, greater than 45 days, greater than 2 months, greater than 3 months, greater than 4 months, or greater than 5 months.
  • the increased half-life results in a higher serum titer which thus reduces the frequency of the administration of the antibodies and/or reduces the concentration of the antibodies to be administered.
  • Binding to human FcRn in vivo and serum half-life of human FcRn high affinity binding polypeptides can be assayed, e.g., in transgenic mice or transfected human cell lines expressing human FcRn, or in primates to which the polypeptides with a variant Fc region are administered.
  • WO 2000/42072 describes antibody variants with improved or diminished binding to FcRns. See also, e.g., Shields et al. J. Biol. Chem. 9(2):6591-6604 (2001).
  • Fc alterations may lead to enhanced or reduced ADCC or CDC activity.
  • CDC refers to the lysing of a target cell in the presence of complement
  • ADCC refers to a form of cytotoxicity in which secreted Ig bound onto FcRs present on certain cytotoxic cells (e.g., Natural Killer cells, neutrophils, and macrophages) enables these cytotoxic effector cells to bind specifically to an antigen-bearing target cell and subsequently kill the target cell with cytotoxins.
  • antibody variants are provided with "altered" FcR binding affinity, which is either enhanced or diminished binding as compared to a parent or unmodified antibody or to an antibody comprising a native sequence FcR.
  • Such variants which display decreased binding may possess little or no appreciable binding, e.g., 0- 20% binding to the FcR compared to a native sequence, e.g. as determined by techniques well known in the art.
  • the variant will exhibit enhanced binding as compared to the native immunoglobulin Fc domain. It will be appreciated that these types of Fc variants may advantageously be used to enhance the effective anti -neoplastic properties of the disclosed antibodies.
  • such alterations lead to increased binding affinity, reduced immunogenicity, increased production, altered glycosylation and/or disulfide bonds (e.g., for conjugation sites), modified binding specificity, increased phagocytosis; and/or down regulation of cell surface receptors (e.g. B cell receptor; BCR), etc.
  • B cell receptor e.g. B cell receptor; BCR
  • Still other embodiments comprise one or more engineered glycoforms, e.g., a site-specific antibody comprising an altered glycosylation pattern or altered carbohydrate composition that is covalently attached to the protein (e.g., in the Fc domain).
  • Engineered glycoforms may be useful for a variety of purposes, including but not limited to enhancing or reducing effector function, increasing the affinity of the antibody for a target or facilitating production of the antibody.
  • the molecule may be engineered to express an aglycosylated form.
  • Fc variants include an Fc variant that has an altered glycosylation composition, such as a hypofucosylated antibody having reduced amounts of fucosyl residues or an antibody having increased bisecting GlcNAc structures. Such altered glycosylation patterns have been demonstrated to increase the ADCC ability of antibodies.
  • Engineered glycoforms may be generated by any method known to one skilled in the art, for example by using engineered or variant expression strains, by co-expression with one or more enzymes (for example N- acetylglucosaminyltransferase III (GnTIII)), by expressing a molecule comprising an Fc region in various organisms or cell lines from various organisms or by modifying carbohydrate(s) after the molecule comprising Fc region has been expressed (see, for example, WO 2012/117002).
  • one or more enzymes for example N- acetylglucosaminyltransferase III (GnTIII)
  • GnTIII N- acetylglucosaminyltransferase III
  • an antibody fragment comprises at least a portion of an intact antibody.
  • fragment of an antibody molecule includes antigen-binding fragments of antibodies, and the term “antigen-binding fragment” refers to a polypeptide fragment of an immunoglobulin or antibody that immunospecifically binds or reacts with a selected antigen or immunogenic determinant thereof or competes with the intact antibody from which the fragments were derived for specific antigen binding.
  • immunoreactive fragments include: variable light chain fragments (VL), variable heavy chain fragments (VH), scFvs, F(ab')2 fragment, Fab fragment, Fd fragment, Fv fragment, single domain antibody fragments, diabodies, linear antibodies, single-chain antibody molecules and multispecific antibodies formed from antibody fragments.
  • an active site-specific fragment comprises a portion of the antibody that retains its ability to interact with the antigen/substrates or receptors and modify them in a manner similar to that of an intact antibody (though maybe with somewhat less efficiency).
  • Such antibody fragments may further be engineered to comprise one or more free cysteines as described herein.
  • the KREMEN2 binding domain will comprise a scFv construct.
  • a "single chain variable fragment (scFv)" means a single chain polypeptide derived from an antibody which retains the ability to bind to an antigen.
  • An example of the scFv includes an antibody polypeptide which is formed by a recombinant DNA technique and in which Fv regions of immunoglobulin heavy chain and light chain fragments are linked via a spacer sequence.
  • Various methods for preparing an scFv are known, and include methods described in U.S.P.N. 4,694,778.
  • an antibody fragment is one that comprises the Fc region and that retains at least one of the biological functions normally associated with the Fc region when present in an intact antibody, such as FcRn binding, antibody half-life modulation, ADCC function and complement binding.
  • an antibody fragment is a monovalent antibody that has an in vivo half-life substantially similar to an intact antibody.
  • such an antibody fragment may comprise an antigen binding arm linked to an Fc sequence comprising at least one free cysteine capable of conferring in vivo stability to the fragment.
  • fragments can be obtained by molecular engineering or via chemical or enzymatic treatment (such as papain or pepsin) of an intact or complete antibody or antibody chain or by recombinant means. See, e.g., Fundamental Immunology, W. E. Paul, ed., Raven Press, N.Y. (1999), for a more detailed description of antibody fragments.
  • the antibodies and conjugates of the invention may be monovalent or multivalent (e.g., bivalent, trivalent, etc.).
  • valency refers to the number of potential target binding sites associated with an antibody. Each target binding site-specifically binds one target molecule or specific position or locus or epitope on a target molecule. When an antibody is monovalent, each binding site of the molecule will specifically bind to a single antigen position or epitope. When an antibody comprises more than one target binding site (multivalent), each target binding site may specifically bind the same or different molecules (e.g., may bind to different ligands or different antigens, or different epitopes or positions on the same antigen). See, for example, U.S.P.N. 2009/0130105.
  • the antibodies are bispecific antibodies in which the two chains have different specificities, as described in Millstein et al., 1983, Nature, 305:537-539 and WO 2014/124326.
  • Other embodiments include antibodies with additional specificities such as trispecific antibodies.
  • Other more sophisticated compatible multispecific constructs and methods of their fabrication are set forth in U.S.P.N. 2009/0155255, as well as WO 94/04690; Suresh et al, 1986, Methods in Enzymology, 121 :210; and WO96/27011.
  • Multivalent antibodies may immunospecifically bind to different epitopes of the desired target molecule or may immunospecifically bind to both the target molecule as well as a heterologous epitope, such as a heterologous polypeptide or solid support material. While selected embodiments may only bind two antigens (i.e. bispecific antibodies), antibodies with additional specificities such as trispecific antibodies are also encompassed by the instant invention. Bispecific antibodies also include cross-linked or "heteroconjugate" antibodies. For example, one of the antibodies in the heteroconjugate can be coupled to avidin, the other to biotin. Such antibodies have, for example, been proposed to target immune system cells to unwanted cells (U.S.P.N.
  • Heteroconjugate antibodies may be made using any convenient cross-linking methods. Suitable cross-linking agents are well known in the art, and are disclosed in U.S. P.N. 4,676,980, along with a number of cross- linking techniques. 5. Recombinant production of antibodies
  • Antibodies and fragments thereof may be produced or modified using genetic material obtained from antibody producing cells and recombinant technology (see, for example; Dubel and Reichert (Eds.) (2014) Handbook of Therapeutic Antibodies, 2 nd Edition, Wiley-Blackwell GmbH; Sambrook and Russell (Eds.) (2000) Molecular Cloning: A Laboratory Manual (3 rd Ed.), NY, Cold Spring Harbor Laboratory Press; Ausubel et al. (2002) Short Protocols in Molecular Biology: A Compendium of Methods from Current Protocols in Molecular Biology, Wiley, John & Sons, Inc.; and U.S.P.N. 7,709,611).
  • nucleic acid molecules that encode the antibodies of the invention.
  • the nucleic acids may be present in whole cells, in a cell lysate, or in a partially purified or substantially pure form.
  • a nucleic acid is "isolated” or rendered substantially pure when separated from other cellular components or other contaminants, e.g., other cellular nucleic acids or proteins, by standard techniques, including alkaline/SDS treatment, CsCl banding, column chromatography, agarose gel electrophoresis and others well known in the art.
  • a nucleic acid of the invention can be, for example, DNA (e.g.
  • genomic DNA e.g., genomic DNA, cDNA), RNA and artificial variants thereof (e.g., peptide nucleic acids), whether single-stranded or double-stranded or RNA, RNA and may or may not contain introns.
  • the nucleic acid is a cDNA molecule.
  • Nucleic acids of the invention can be obtained using standard molecular biology techniques.
  • cDNAs encoding the light and heavy chains of the antibody can be obtained by standard PCR amplification or cDNA cloning techniques.
  • nucleic acid molecules encoding the antibody can be recovered from the library.
  • DNA fragments encoding VH and VL segments can be further manipulated by standard recombinant DNA techniques, for example to convert the variable region genes to full-length antibody chain genes, to Fab fragment genes or to a scFv gene.
  • a VL- or VH-encoding DNA fragment is operatively linked to another DNA fragment encoding another protein, such as an antibody constant region or a flexible linker.
  • the term "operatively linked”, as used in this context, means that the two DNA fragments are joined such that the amino acid sequences encoded by the two DNA fragments remain in-frame.
  • the isolated DNA encoding the VH region can be converted to a full-length heavy chain gene by operatively linking the VH-encoding DNA to another DNA molecule encoding heavy chain constant regions (CHI, CH2 and CH3 in the case of IgGl).
  • the sequences of human heavy chain constant region genes are known in the art (see e.g., Kabat, et al. (1991) ⁇ supra)) and DNA fragments encompassing these regions can be obtained by standard PCR amplification.
  • the heavy chain constant region can be an IgGl, IgG2, IgG3, IgG4, IgA, IgE, IgM or IgD constant region, but most preferably is an IgGl or IgG4 constant region.
  • An exemplary IgGl constant region is set forth in SEQ ID NO: 2.
  • the VH-encoding DNA can be operatively linked to another DNA molecule encoding only the heavy chain CHI constant region.
  • Isolated DNA encoding the VL region can be converted to a full-length light chain gene (as well as a Fab light chain gene) by operatively linking the VL-encoding DNA to another DNA molecule encoding the light chain constant region, CL.
  • the sequences of human light chain constant region genes are known in the art (see e.g., Kabat, et al. (1991) ⁇ supra)) and DNA fragments encompassing these regions can be obtained by standard PCR amplification.
  • the light chain constant region can be a kappa or lambda constant region, but most preferably is a kappa constant region.
  • An exemplary compatible kappa light chain constant region is set forth in SEQ ID NO: 5 while an exemplary compatible lambda light chain constant region is set forth in SEQ ID NO: 8.
  • VH or VL domains may be operatively linked to their respective constant regions (CH or CL) where the constant regions are site-specific constant regions and provide site- specific antibodies.
  • the resulting site-specific antibodies will comprise two unpaired cysteines on the heavy chains while in other embodiments the site-specific antibodies will comprise two unpaired cysteines in the CL domain.
  • polypeptides e.g. antigens or antibodies
  • sequence identity e.g. sequence similarity
  • sequence homology e.g., sequence homology to the polypeptides of the invention.
  • a derived humanized antibody VH or VL domain may exhibit a sequence similarity with the source (e.g., murine) or acceptor (e.g., human) VH or VL domain.
  • a "homologous" polypeptide may exhibit 65%, 70%, 75%, 80%, 85%, or 90% sequence identity. In other embodiments a "homologous" polypeptides may exhibit 93%, 95% or 98% sequence identity.
  • the percent homology between two amino acid sequences is equivalent to the percent identity between the two sequences.
  • the comparison of sequences and determination of percent identity between two sequences can be accomplished using a mathematical algorithm, as described in the non-limiting Examples below.
  • the percent identity between two amino acid sequences can be determined using the algorithm of E. Meyers and W. Miller (Comput. Appl. Biosci. ,4: 11-17 (1988)) which has been incorporated into the ALIGN program (version 2.0), using a PAM120 weight residue table, a gap length penalty of 12 and a gap penalty of 4.
  • the percent identity between two amino acid sequences can be determined using the Needleman and Wunsch (J. Mol. Biol.
  • the protein sequences of the present invention can further be used as a "query sequence" to perform a search against public databases to, for example, identify related sequences.
  • Such searches can be performed using the XBLAST program (version 2.0) of Altschul, et al. (1990) J. Mol. Biol. 215:403-10.
  • Gapped BLAST can be utilized as described in Altschul et al., (1997) Nucleic Acids Res. 25(17):3389-3402.
  • the default parameters of the respective programs e.g., XBLAST and NBLAST
  • the default parameters of the respective programs e.g., XBLAST and NBLAST
  • Residue positions which are not identical may differ by conservative amino acid substitutions or by non-conservative amino acid substitutions.
  • a "conservative amino acid substitution” is one in which an amino acid residue is substituted by another amino acid residue having a side chain with similar chemical properties (e.g., charge or hydrophobicity).
  • a conservative amino acid substitution will not substantially change the functional properties of a protein.
  • the percent sequence identity or degree of similarity may be adjusted upwards to correct for the conservative nature of the substitution.
  • polypeptide exhibiting sequence identity will retain the desired function or activity of the polypeptide of the invention (e.g., antibody.)
  • nucleic acids that exhibit "sequence identity", sequence similarity" or “sequence homology” to the nucleic acids of the invention are also contemplated herein.
  • a “homologous sequence” means a sequence of nucleic acid molecules exhibiting at least about 65%, 70%, 75%, 80%, 85%, or 90% sequence identity.
  • a "homologous sequence" of nucleic acids may exhibit 93%, 95% or 98% sequence identity to the reference nucleic acid.
  • the instant invention also provides vectors comprising such nucleic acids described above, which may be operably linked to a promoter (see, e.g., WO 86/05807; WO 89/01036; and U.S.P.N. 5, 122,464); and other transcriptional regulatory and processing control elements of the eukaryotic secretory pathway.
  • the invention also provides host cells harboring those vectors and host- expression systems.
  • host-expression system includes any kind of cellular system that can be engineered to generate either the nucleic acids or the polypeptides and antibodies of the invention.
  • host-expression systems include, but are not limited to microorganisms (e.g., E. coli or B.
  • subtilis transformed or transfected with recombinant bacteriophage DNA or plasmid DNA; yeast (e.g., Saccharomyces) transfected with recombinant yeast expression vectors; or mammalian cells (e.g., COS, CHO-S, HEK293T, 3T3 cells) harboring recombinant expression constructs containing promoters derived from the genome of mammalian cells or viruses (e.g., the adenovirus late promoter).
  • the host cell may be co-transfected with two expression vectors, for example, the first vector encoding a heavy chain derived polypeptide and the second vector encoding a light chain derived polypeptide.
  • the host cell may also be engineered to allow the production of an antigen binding molecule with various characteristics (e.g. modified glycoforms or proteins having GnTIII activity).
  • cell lines that stably express the selected antibody may be engineered using standard art recognized techniques and form part of the invention.
  • host cells can be transformed with DNA controlled by appropriate expression control elements (e.g., promoter or enhancer sequences, transcription terminators, polyadenylation sites, etc.), and a selectable marker.
  • appropriate expression control elements e.g., promoter or enhancer sequences, transcription terminators, polyadenylation sites, etc.
  • selectable marker e.g., promoter or enhancer sequences, transcription terminators, polyadenylation sites, etc.
  • Any of the selection systems well known in the art may be used, including the glutamine synthetase gene expression system (the GS system) which provides an efficient approach for enhancing expression under selected conditions.
  • the GS system is discussed in whole or part in connection with EP 0 216 846, EP 0 256 055, EP 0 323 997 and EP 0 338 841 and U.S.P.N.s 5,591,639 and 5,879,936.
  • Another compatible expression system for the development of stable cell lines is the FreedomTM CHO-S Kit (Life Technologies).
  • an antibody of the invention may be purified or isolated by methods known in the art in that it is identified and separated and/or recovered from its natural environment and separated from contaminants that would interfere with diagnostic or therapeutic uses for the antibody or related ADC.
  • Isolated antibodies include antibodies in situ within recombinant cells.
  • isolated preparations may be purified using various art-recognized techniques, such as, for example, ion exchange and size exclusion chromatography, dialysis, diafiltration, and affinity chromatography, particularly Protein A or Protein G affinity chromatography. Compatible methods are discussed more fully in the Examples below.
  • antibody producing cells e.g., hybridomas, yeast colonies, etc.
  • Hybridomas can be expanded in vitro in cell culture or in vivo in syngeneic immunocompromised animals. Methods of selecting, cloning and expanding hybridomas and/or colonies are well known to those of ordinary skill in the art. Once the desired antibodies are identified the relevant genetic material may be isolated, manipulated and expressed using common, art-recognized molecular biology and biochemical techniques.
  • the antibodies produced by naive libraries may be of moderate affinity (K a of about 10 6 to 10 7 M "1 ).
  • affinity maturation may be mimicked in vitro by constructing antibody libraries (e.g., by introducing random mutations in vitro by using error-prone polymerase) and reselecting antibodies with high affinity for the antigen from those secondary libraries (e.g. by using phage or yeast display).
  • WO 9607754 describes a method for inducing mutagenesis in a CDR of an immunoglobulin light chain to create a library of light chain genes.
  • phage or yeast display in which a library of human combinatorial antibodies or scFv fragments is synthesized on phages or yeast, the library is screened with the antigen of interest or an antibody-binding portion thereof, and the phage or yeast that binds the antigen is isolated, from which one may obtain the antibodies or immunoreactive fragments (Vaughan et a/. , 1996, PMID: 9630891; Sheets et a/., 1998, PMID: 9600934; Boder et a/., 1997, PMID: 9181578; Pepper et a/., 2008, PMID: 18336206).
  • Kits for generating phage or yeast display libraries are commercially available. There also are other methods and reagents that can be used in generating and screening antibody display libraries (see U.S.P.N. 5,223,409; WO 92/18619, WO 91/17271, WO 92/20791, WO 92/15679, WO 93/01288, WO 92/01047, WO 92/09690; and Barbas et a/., 1991, PMID: 1896445). Such techniques advantageously allow for the screening of large numbers of candidate antibodies and provide for relatively easy manipulation of sequences (e.g., by recombinant shuffling).
  • antibody-producing cells e.g., hybridomas or yeast colonies
  • antibody-producing cells may be selected, cloned and further screened for favorable properties including, for example, robust growth, high antibody production and, as discussed in more detail below, desirable site-specific antibody characteristics.
  • characteristics of the antibody may be imparted by selecting a particular antigen (e.g., a specific KREMEN2 isoform) or immunoreactive fragment of the target antigen for inoculation of the animal.
  • the selected antibodies may be engineered as described above to enhance or refine immunochemical characteristics such as affinity or pharmacokinetics.
  • the antibodies of the invention may be "antagonists" or “neutralizing” antibodies, meaning that the antibody may associate with a determinant and block or inhibit the activities of said determinant either directly or by preventing association of the determinant with a binding partner such as a ligand or a receptor, thereby interrupting the biological response that otherwise would result from the interaction of the molecules.
  • a neutralizing or antagonist antibody will substantially inhibit binding of the determinant to its ligand or substrate when an excess of antibody reduces the quantity of binding partner bound to the determinant by at least about 20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 95%, 97%, 99% or more as measured, for example, by target molecule activity or in an in vitro competitive binding assay.
  • modified activity may be measured directly using art recognized techniques or may be measured by the impact the altered activity has downstream (e.g., oncogenesis or cell survival).
  • Certain exemplary antibodies that block the binding of KREMEN2 to its ligand DKK1 are shown in the Examples below and the disclosed assay may be used to determine which antibodies are neutralizing in accordance with the instant invention.
  • the antibodies may comprise internalizing antibodies such that the antibody will bind to a determinant and will be internalized (along with any conjugated pharmaceutically active moiety) into a selected target cell including tumorigenic cells.
  • the number of antibody molecules internalized may be sufficient to kill an antigen-expressing cell, especially an antigen-expressing tumorigenic cell.
  • the uptake of a single antibody molecule into the cell may be sufficient to kill the target cell to which the antibody binds.
  • KREMEN2 protein there is evidence that a substantial portion of expressed KREMEN2 protein remains associated with the tumorigenic cell surface, thereby allowing for localization and internalization of the disclosed antibodies or ADCs.
  • such antibodies will be associated with, or conjugated to, one or more drugs that kill the cell upon internalization.
  • the ADCs of the instant invention will comprise an internalizing site-specific ADC.
  • an antibody that "internalizes" is one that is taken up (along with any conjugated cytotoxin) by a target cell upon binding to an associated determinant.
  • the number of such ADCs internalized will preferably be sufficient to kill the determinant-expressing cell, especially a determinant expressing cancer stem cell.
  • the uptake of a few antibody molecules into the cell is sufficient to kill the target cell to which the antibody binds.
  • certain drugs such as PBDs or calicheamicin are so potent that the internalization of a few molecules of the toxin conjugated to the antibody is sufficient to kill the target cell.
  • Whether an antibody internalizes upon binding to a mammalian cell can be determined by various art-recognized assays (e.g., saporin assays such as Mab-Zap and Fab-Zap; Advanced Targeting Systems) including those described in the Examples below. Methods of detecting whether an antibody internalizes into a cell are also described in U.S.P.N. 7,619,068.
  • saporin assays such as Mab-Zap and Fab-Zap; Advanced Targeting Systems
  • the antibodies of the invention are depleting antibodies.
  • the term "depleting” antibody refers to an antibody that preferably binds to an antigen on or near the cell surface and induces, promotes or causes the death of the cell (e.g., by CDC, ADCC or introduction of a cytotoxic agent).
  • the selected depleting antibodies will be conjugated to a cytotoxin.
  • a depleting antibody will be able to kill at least 20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 95%, 97%, or 99% of KREMEN2-expressing cells in a defined cell population.
  • the cell population may comprise enriched, sectioned, purified or isolated tumorigenic cells, including cancer stem cells.
  • the cell population may comprise whole tumor samples or heterogeneous tumor extracts that comprise cancer stem cells. Standard biochemical techniques may be used to monitor and quantify the depletion of tumorigenic cells in accordance with the teachings herein. D. Binding affinity
  • K D refers to the dissociation constant or apparent affinity of a particular antibody-antigen interaction.
  • An antibody of the invention can immunospecifically bind its target antigen when the dissociation constant K D (k of f/k on ) is ⁇ 10 "7 M.
  • the antibody specifically binds antigen with high affinity when the K D is ⁇ 5x10 "9 M, and with very high affinity when the K D is ⁇ 5xlO "10 M.
  • the antibody has a K D of ⁇ 10 "9 M and an off- rate of about lxlO "4 /sec.
  • the off-rate is ⁇ lxlO "5 /sec.
  • the antibodies will bind to a determinant with a K D of between about 10 "7 M and 10 "10 M, and in yet another embodiment it will bind with a K D ⁇ 2x10 "10 M.
  • Still other selected embodiments of the invention comprise antibodies that have a K D (k 0 ff/k on ) of less than 10 "6 M, less than 5xlO "6 M, less than 10 "7 M, less than 5xlO "7 M, less than 10 "8 M, less than 5xl0 "8 M, less than 10 "9 M, less than 5xl0 "9 M, less than 10 "10 M, less than 5xl0 "10 M, less than 10 "11 M, less than 5xl0 "u M, less than 10 "12 M, less than 5xlO "12 M, less than 10 "13 M, less than 5xl0 "13 M, less than 10 " 14 M, less than 5xl0 "14 M, less than 10 "15 M or less than 5xl0 "15 M.
  • an antibody of the invention that immunospecifically binds to a determinant e.g. KREMEN2 may have an association rate constant or k on (or k a) rate (antibody + antigen (Ag) k on ⁇ — antibody- Ag) of at least 10 5 MV, at least 2xl0 5 MV, at least 5xl0 5 MV, at least 10 6 MV, at least 5X10 6 MV, at least 10 7 MV, at least 5X10 7 MV, or at least 10 8 MV.
  • an antibody of the invention that immunospecifically binds to a determinant e.g. KREMEN2 may have a disassociation rate constant or k 0 ff ⁇ or k rate (antibody + antigen (Ag) k off ⁇ — antibody-Ag) of less than 10 "1 s " l , less than 5xl0 _1 s “ l , less than 10 "2 s “ l , less than 5xl0 "2 s “ l , less than 10 "3 s “ l , less than 5xl0 "3 s “ l , less than 10 "4 s " l , less than 5xl0 4 s " l , less than 10 "5 s " l , less than 5xl0 “5 s " l , less than 10 "6 s “ l , less than 5xl0 “6 s “ 1 less than 10 "7 s " l , less than 5xl0 “7
  • Binding affinity may be determined using various techniques known in the art, for example, surface plasmon resonance, bio-layer interferometry, dual polarization interferometry, static light scattering, dynamic light scattering, isothermal titration calorimetry, ELISA, analytical ultracentrifugation, and flow cytometry.
  • Antibodies disclosed herein may be characterized in terms of the discrete epitope with which they associate.
  • An "epitope” is the portion(s) of a determinant to which the antibody or immunoreactive fragment specifically binds. Immunospecific binding can be confirmed and defined based on binding affinity, as described above, or by the preferential recognition by the antibody of its target antigen in a complex mixture of proteins and/or macromolecules (e.g. in competition assays).
  • a “linear epitope” is formed by contiguous amino acids in the antigen that allow for immunospecific binding of the antibody. The ability to preferentially bind linear epitopes is typically maintained even when the antigen is denatured.
  • a “conformational epitope” usually comprises non-contiguous amino acids in the antigen's amino acid sequence but, in the context of the antigen's secondary, tertiary or quaternary structure, are sufficiently proximate to be bound concomitantly by a single antibody.
  • An epitope typically includes at least 3, and more usually, at least 5 or 8-10 or 12-20 amino acids in a unique spatial conformation.
  • Competing antibodies may be determined by an assay in which the antibody or immunologically functional fragment being tested prevents or inhibits specific binding of a reference antibody to a common antigen.
  • an assay involves the use of purified antigen (e.g., KREMEN2 or a domain or fragment thereof) bound to a solid surface or cells, an unlabeled test antibody and a labeled reference antibody.
  • binning or competitive binding may be determined using various art-recognized techniques, such as, for example, immunoassays such as western blots, radioimmunoassays, enzyme linked immunosorbent assay (ELISA), "sandwich” immunoassays, immunoprecipitation assays, precipitin reactions, gel diffusion precipitin reactions, immunodiffusion assays, agglutination assays, complement-fixation assays, immunoradiometric assays, fluorescent immunoassays and protein A immunoassays.
  • immunoassays such as western blots, radioimmunoassays, enzyme linked immunosorbent assay (ELISA), "sandwich” immunoassays, immunoprecipitation assays, precipitin reactions, gel diffusion precipitin reactions, immunodiffusion assays, agglutination assays, complement-fixation assays, immunoradiometric assays, fluorescent immunoassays and protein A immunoassay
  • cross-blocking assays may be used (see, for example, WO 2003/48731; and Harlow et al. (1988) Antibodies, A Laboratory Manual, Cold Spring Harbor Laboratory, Ed Harlow and David Lane).
  • Luminex is a bead-based immunoassay platform that enables large scale multiplexed antibody pairing. The assay compares the simultaneous binding patterns of antibody pairs to the target antigen.
  • One antibody of the pair is bound to Luminex beads, wherein each capture mAb is bound to a bead of a different color.
  • the other antibody (detector mAb) is bound to a fluorescent signal (e.g. phycoerythrin (PE)).
  • PE phycoerythrin
  • the assay analyzes the simultaneous binding (pairing) of antibodies to an antigen and groups together antibodies with similar pairing profiles. Similar profiles of a detector mAb and a capture mAb indicates that the two antibodies bind to the same or closely related epitopes.
  • pairing profiles can be determined using Pearson correlation coefficients to identify the antibodies which most closely correlate to any particular antibody on the panel of antibodies that are tested.
  • a test/detector mAb will be determined to be in the same bin as a reference/capture mAb if the Pearson's correlation coefficient of the antibody pair is at least 0.9. In other embodiments the Pearson's correlation coefficient is at least 0.8, 0.85, 0.87 or 0.89. In further embodiments, the Pearson's correlation coefficient is at least 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99 or 1. Other methods of analyzing the data obtained from the Luminex assay are described in U.S. P.N. 8,568,992.
  • Luminex to analyze 100 different types of beads (or more) simultaneously provides almost unlimited antigen and/or antibody surfaces, resulting in improved throughput and resolution in antibody epitope profiling over a biosensor assay (Miller, et al., 2011, PMID: 21223970).
  • surface plasmon resonance refers to an optical phenomenon that allows for the analysis of real-time specific interactions by detection of alterations in protein concentrations within a biosensor matrix. Using commercially available equipment such as the BIAcoreTM 2000 system it may readily be determined if selected antibodies compete with each other for binding to a defined antigen.
  • bio-layer interferometry an optical analytical technique that analyzes the interference pattern of white light reflected from two surfaces: a layer of immobilized protein on a biosensor tip, and an internal reference layer. Any change in the number of molecules bound to the biosensor tip causes a shift in the interference pattern that can be measured in real-time.
  • biolayer interferometry assays may be conducted using a ForteBio ® Octet RED machine as follows. A reference antibody (Abl) is captured onto an anti -mouse capture chip, a high concentration of non-binding antibody is then used to block the chip and a baseline is collected.
  • Monomeric, recombinant target protein is then captured by the specific antibody (Abl) and the tip is dipped into a well with either the same antibody (Abl) as a control or into a well with a different test antibody (Ab2). If no further binding occurs, as determined by comparing binding levels with the control Abl, then Abl and Ab2 are determined to be "competing" antibodies. If additional binding is observed with Ab2, then Abl and Ab2 are determined not to compete with each other. This process can be expanded to screen large libraries of unique antibodies using a full row of antibodies in a 96-well plate representing unique bins.
  • a test antibody will compete with a reference antibody if the reference antibody inhibits specific binding of the test antibody to a common antigen by at least 40%, 45%, 50%, 55%, 60%, 65%, 70% or 75%. In other embodiments, binding is inhibited by at least 80%, 85%, 90%, 95%, or 97% or more.
  • Domain-level epitope mapping may be performed using a modification of the protocol described by Cochran et al., 2004, PMTD: 15099763. Fine epitope mapping is the process of determining the specific amino acids on the antigen that comprise the epitope of a determinant to which the antibody binds.
  • fine epitope mapping can be performed using phage or yeast display.
  • Other compatible epitope mapping techniques include alanine scanning mutants, peptide blots (Reineke, 2004, PMTD: 14970513), or peptide cleavage analysis.
  • enzymes such as proteolytic enzymes (e.g., trypsin, endoproteinase Glu-C, endoproteinase Asp-N, chymotrypsin, etc.); chemical agents such as succinimidyl esters and their derivatives, primary amine-containing compounds, hydrazines and carbohydrazines, free amino acids, etc.
  • proteolytic enzymes e.g., trypsin, endoproteinase Glu-C, endoproteinase Asp-N, chymotrypsin, etc.
  • chemical agents such as succinimidyl esters and their derivatives, primary amine-containing compounds, hydrazines and carbohydrazines, free amino acids, etc.
  • Modification-Assisted Profiling also known as Antigen Structure-based Antibody Profiling (ASAP) can be used to categorize large numbers of monoclonal antibodies directed against the same antigen according to the similarities of the binding profile of each antibody to chemically or enzymatically modified antigen surfaces (U.S.P.N. 2004/0101920).
  • a desired epitope on an antigen is determined, it is possible to generate additional antibodies to that epitope, e.g., by immunizing with a peptide comprising the selected epitope using techniques described herein.
  • the antibodies of the invention may be conjugated with pharmaceutically active or diagnostic moieties to form an "antibody drug conjugate” (ADC) or "antibody conjugate".
  • ADC antibody drug conjugate
  • conjugate is used broadly and means the covalent or non- covalent association of any pharmaceutically active or diagnostic moiety with an antibody of the instant invention regardless of the method of association. In certain embodiments the association is effected through a lysine or cysteine residue of the antibody.
  • the pharmaceutically active or diagnostic moieties may be conjugated to the antibody via one or more site-specific free cysteine(s).
  • the disclosed ADCs may be used for therapeutic and diagnostic purposes.
  • the ADCs of the instant invention may be used to selectively deliver predetermined warheads to the target location (e.g., tumorigenic cells and/or cells expressing KREMEN2).
  • the terms "drug” or “warhead” may be used interchangeably and will mean any biologically active (e.g., a pharmaceutically active compound or therapeutic moiety) or detectable molecule or compound that has a physiological effect or reporter function when introduced into a subject.
  • warheads include the anti -cancer agents or cytotoxins as described below.
  • a "payload” may comprise a drug or warhead in combination with an optional linker compound (e.g., a therapeutic payload) that preferably provides a relatively stable pharmaceutical complex until the ADC reaches the target.
  • the warhead or drug on the conjugate may comprise peptides, proteins or prodrugs which are metabolized to an active agent in vivo, polymers, nucleic acid molecules, small molecules, binding agents, mimetic agents, synthetic drugs, inorganic molecules, organic molecules and radioisotopes.
  • the drug or warhead will be covalently conjugated to the antibody through a linker.
  • the drug or warhead will be directly conjugated to, or incorporated in, the antibody.
  • the disclosed ADCs will direct the bound payload (e.g., drug linker) to the target site in a relatively unreactive, non-toxic state before releasing and activating the warhead (e.g., PBDS 1-5 as disclosed herein).
  • This targeted release of the warhead is preferably achieved through stable conjugation of the payloads (e.g., via one or more cysteines or lysines on the antibody) and relatively homogeneous composition of the ADC preparations which minimize over-conjugated toxic ADC species.
  • the conjugates of the instant invention can substantially reduce undesirable non-specific toxicity. This advantageously provides for relatively high levels of the active cytotoxin at the tumor site while minimizing exposure of non-targeted cells and tissue thereby providing an enhanced therapeutic index.
  • any disclosure directed to exemplary therapeutic payloads is also applicable to payloads comprising diagnostic agents or biocompatible modifiers as discussed herein unless otherwise dictated by context.
  • the selected payload may be covalently or non-covalently linked to the antibody and exhibit various stoichiometric molar ratios depending, at least in part, on the method used to effect the conjugation.
  • Conjugates of the instant invention may be generally represented by the formula:
  • a) Ab comprises an anti-KREMEN2 antibody
  • L comprises an optional linker
  • c) D comprises a drug
  • n is an integer from about 1 to about 20.
  • conjugates according to the aforementioned formula may be fabricated using a number of different linkers and drugs and that conjugation methodology will vary depending on the selection of components.
  • any drug or drug linker compound that associates with a reactive residue (e.g., cysteine or lysine) of the disclosed antibodies are compatible with the teachings herein.
  • any reaction conditions that allow for conjugation (including site-specific conjugation) of the selected drug to an antibody are within the scope of the present invention.
  • some preferred embodiments of the instant invention comprise selective conjugation of the drug or drug linker to free cysteines using stabilization agents in combination with mild reducing agents as described herein. Such reaction conditions tend to provide more homogeneous preparations with less non-specific conjugation and contaminants and correspondingly less toxicity.
  • antibodies of the invention may be conjugated, linked or fused to or otherwise associated with any pharmaceutically active compound comprising a therapeutic moiety or a drug such as an anti-cancer agent including, but not limited to, cytotoxic agents (or cytotoxins), cytostatic agents, anti-angiogenic agents, debulking agents, chemotherapeutic agents, radiotherapeutic agents, targeted anti-cancer agents, biological response modifiers, cancer vaccines, cytokines, hormone therapies, anti-metastatic agents and immunotherapeutic agents.
  • an anti-cancer agent including, but not limited to, cytotoxic agents (or cytotoxins), cytostatic agents, anti-angiogenic agents, debulking agents, chemotherapeutic agents, radiotherapeutic agents, targeted anti-cancer agents, biological response modifiers, cancer vaccines, cytokines, hormone therapies, anti-metastatic agents and immunotherapeutic agents.
  • Exemplary anti-cancer agents or cytotoxins comprise 1-dehydrotestosterone, anthramycins, actinomycin D, bleomycin, calicheamicins (including n-acetyl calicheamicin), colchicin, cyclophosphamide, cytochalasin B, dactinomycin (formerly actinomycin), dihydroxy anthracin, dione, duocarmycin, emetine, epirubicin, ethidium bromide, etoposide, glucocorticoids, gramicidin D, lidocaine, maytansinoids such as DM-1 and DM-4 (Immunogen), benzodiazepine derivatives (Immunogen), mithramycin, mitomycin, mitoxantrone, paclitaxel, procaine, propranolol, puromycin, tenoposide, tetracaine and pharmaceutically acceptable salts or solvates
  • Additional compatible cytotoxins comprise dolastatins and auristatins, including monomethyl auristatin E (MMAE) and monomethyl auristatin F (MMAF) (Seattle Genetics), amanitins such as alpha-amanitin, beta-amanitin, gamma-amanitin or epsilon-amanitin (Heidelberg Pharma), DNA minor groove binding agents such as duocarmycin derivatives (Syntarga), alkylating agents such as modified or dimeric pyrrolobenzodiazepines (PBD), mechlorethamine, thioepa, chlorambucil, melphalan, carmustine (BCNU), lomustine (CCNU), cyclothosphamide, busulfan, dibromomannitol, streptozotocin, mitomycin C and cisdichlorodiamine platinum (II) (DDP) cisplatin, splicing inhibitors such as me
  • tubular binding agents such as epothilone analogs and tubulysins, paclitaxel and DNA damaging agents such as calicheamicins and esperamicins
  • antimetabolites such as methotrexate, 6-mercaptopurine, 6-thioguanine, cytarabine, and 5-fluorouracil decarbazine
  • anti- mitotic agents such as vinblastine and vincristine and anthracyclines such as daunombicin (formerly daunomycin) and doxorubicin and pharmaceutically acceptable salts or solvates, acids or derivatives of any of the above.
  • the antibodies of the instant invention may be associated with anti- CD3 binding molecules to recruit cytotoxic T-cells and have them target tumorigenic cells (BiTE technology; see e.g., Fuhrmann et. al. (2010) Annual Meeting of AACR Abstract No. 5625).
  • ADCs of the invention may comprise cytotoxins comprising therapeutic radioisotopes conjugated using appropriate linkers.
  • cytotoxins comprising therapeutic radioisotopes conjugated using appropriate linkers.
  • 131 125 123 121 be compatible with such embodiments include, but are not limited to, iodine ( I, I, I, I,), carbon ( 14 C), copper ( 62 Cu, 64 Cu, 67 Cu), sulfur ( 35 S), radium ( 223 R), tritium ( 3 H), indium ( 115 In, 113 In, 112 In, m In,), bismuth ( 212 Bi, 213 Bi), technetium ( 99 Tc), thallium ( 201 Ti), gallium ( 68 Ga, 67 Ga), palladium ( 103 Pd), molybdenum ( 99 Mo), xenon ( 133 Xe), fluorine ( 18 F), 153 Sm, 177 Lu, 159 Gd, 149 Pm, 140 La, 175 Yb, 166 Ho, 90 Y, 47 Sc, 186 Re, 188 Re, 142 Pr, 105 Rh, 97 Ru, 68 Ge, 57 Co, 65 Zn, 85 Sr, 32 P, 153 Gd,
  • the ADCs of the instant invention will be conjugated to a cytotoxic benzodiazepine derivative warhead.
  • Compatible benzodiazepine derivatives (and optional linkers) that may be conjugated to the disclosed antibodies are described, for example, in U. S.P.N. 8,426,402 and PCT filings WO2012/128868 and WO2014/031566.
  • PBDs compatible benzodiazepine derivatives are believed to bind in the minor grove of DNA and inhibit nucleic acid synthesis.
  • Such compounds reportedly have potent antitumor properties and, as such, are particularly suitable for use in the ADCs of the instant invention.
  • the ADCs of the invention may comprise PBDs, and pharmaceutically acceptable salts or solvates, acids or derivatives thereof, as warheads.
  • PBDs are alkylating agents that exert antitumor activity by covalently binding to DNA in the minor groove and inhibiting nucleic acid synthesis.
  • PBDs have been shown to have potent antitumor properties while exhibiting minimal bone marrow depression.
  • PBDs compatible with the invention may be linked to an antibody using several types of linkers (e.g., a peptidyl linker comprising a maleimido moiety with a free sulfhydryl), and in certain embodiments are dimeric in form (i.e., PBD dimers).
  • PBDs have been shown to have potent antitumor properties while exhibiting minimal bone marrow depression.
  • PBDs compatible with the present invention may be linked to the KREMEN2 targeting agent using any one of several types of linker (e.g., a peptidyl linker comprising a maleimido moiety with a free sulfhydryl) and, in certain embodiments are dimeric in form (i.e., of the general structure:
  • compatible PBDs that may be conjugated to the disclosed modulators are described, in U.S. P.N. 2011/0256157.
  • PBD dimers i.e. those comprising two PBD moieties may be preferred.
  • preferred conjugates of the present invention are those having the formula (AB) or (AC):
  • R D is independently selected from R, C0 2 R, COR, CHO, C0 2 H, and halo;
  • R 6 and R 9 are independently selected from H, R, OH, OR, SH, SR, H 2 , NHR, NRR',
  • R 7 is independently selected from H, R, OH, OR, SH, SR, NH 2 , NHR, NRR', N0 2 , Me 3 Sn and halo;
  • R 10 is a linker connected to a KREMEN2 antibody or fragment or derivative thereof, as described herein;
  • Q is independently selected from O, S and NH;
  • R 11 is either H, or R or, where Q is O, S0 3 M, where M is a metal cation;
  • X is selected from O, S, or N(H) and in selected embodiments comprises O;
  • R" is a C3-12 alkylene group, which chain may be interrupted by one or more heteroatoms (e.g., O, S, N(H), Me and/or aromatic rings, e.g. benzene or pyridine, which rings are optionally substituted);
  • heteroatoms e.g., O, S, N(H), Me and/or aromatic rings, e.g. benzene or pyridine, which rings are optionally substituted
  • R and R' are each independently selected from optionally substituted C 1-12 alkyl
  • R , R , R , X", Q" and R are as defined according to R , R 6 , R 7 , R 9 , X, Q and R 11 respectively, and R c is a capping group.
  • a double bond is present between C2 and C3 when R 2 is C5-20 aryl or Ci. 12 alkyl.
  • R 2 comprises a methyl group.
  • the dotted lines indicate the optional presence of a double bond between CI and C2, as shown below:
  • a double bond is present between CI and C2 when R 2 is C 5-2 o aryl or Ci. 12 alkyl.
  • R 2 comprises a methyl group.
  • R 2 is independently H.
  • R 2 is independently R wherein R comprises CH 3 .
  • the configuration is configuration (I).
  • R 2 is independently R.
  • R 2 is independently optionally substituted 0 5-2 ⁇ aryl.
  • R 2 is independently optionally substituted C 1-12 alkyl.
  • R 2 is independently optionally substituted C 5-20 aryl.
  • R 2 is independently optionally substituted C 5 - 7 aryl.
  • R 2 is independently optionally substituted C 8 -io aryl.
  • R 2 is independently optionally substituted phenyl.
  • R 2 is independently optionally substituted napthyl.
  • R 2 is independently optionally substituted pyridyl. In one embodiment, R 2 is independently optionally substituted quinolinyl or isoquinolinyl.
  • R 2 bears one to three substituent groups, with 1 and 2 being more preferred, and singly substituted groups being most preferred.
  • the substituents may be any position.
  • R 2 is a C5-7 aryl group
  • a single substituent is preferably on a ring atom that is not adjacent the bond to the remainder of the compound, i.e. it is preferably ⁇ or ⁇ to the bond to the remainder of the compound. Therefore, where the C 5- 7 aryl group is phenyl, the substituent is preferably in the meta- or para- positions, and more preferably is in the para- position.
  • R 2 is selected from:
  • R 2 is a C 8 -io aryl group, for example quinolinyl or isoquinolinyl, it may bear any number of substituents at any position of the quinoline or isoquinoline rings. In some embodiments, it bears one, two or three substituents, and these may be on either the proximal and distal rings or both (if more than one substituent).
  • R 2 is optionally substituted
  • the substituents are selected from those substituents given in the substituent section below.
  • R is optionally substituted
  • the substituents are preferably selected from:
  • R or R 2 is optionally substituted
  • the substituents are selected from the group consisting of R, OR, SR, NRR', N0 2 , halo, C0 2 R, COR, CO H 2 , CO HR, and CONRR'.
  • R 2 is C i-i 2 alkyl
  • the optional substituent may additionally include C 3-2 o heterocyclyl and C 5-20 aryl groups.
  • R 2 is C 3-2 o heterocyclyl
  • the optional substituent may additionally include C 1-12 alkyl and C5 -2 o aryl groups.
  • R 2 is C 5-20 aryl groups
  • the optional substituent may additionally include C 3-20 heterocyclyl and C 1-12 alkyl groups.
  • alkyl encompasses the sub-classes alkenyl and alkynyl as well as cycloalkyl.
  • R 2 is optionally substituted C 1-12 alkyl
  • the alkyl group optionally contains one or more carbon-carbon double or triple bonds, which may form part of a conjugated system.
  • the optionally substituted C 1-12 alkyl group contains at least one carbon-carbon double or triple bond, and this bond is conjugated with a double bond present between CI and C2, or C2 and C3.
  • the C 1-12 alkyl group is a group selected from saturated C 1-12 alkyl, C 2 . 12 alkenyl, C 2 . 12 alkynyl and C 3 . 12 cycloalkyl.
  • a substituent on R 2 is halo, it is preferably F or CI, more preferably CI.
  • a substituent on R 2 is ether, it may in some embodiments be an alkoxy group, for example, a Ci-7 alkoxy group (e.g. methoxy, ethoxy) or it may in some embodiments be a C5-7 aryloxy group (e.g phenoxy, pyridyloxy, furanyloxy).
  • R 2 is C 1-7 alkyl, it may preferably be a C 1-4 alkyl group (e.g. methyl, ethyl, propyl, butyl).
  • a substituent on R 2 is C3-7 heterocyclyl, it may in some embodiments be C 6 nitrogen containing heterocyclyl group, e.g. morpholino, thiomorpholino, piperidinyl, piperazinyl. These groups may be bound to the rest of the PBD moiety via the nitrogen atom. These groups may be further substituted, for example, by C 1-4 alkyl groups.
  • R 2 is bis-oxy-Ci -3 alkylene, this is preferably bis-oxy-methylene or bis-oxy- ethylene.
  • substituents for R 2 include methoxy, ethoxy, fluoro, chloro, cyano, bis- oxy-methylene, methyl-piperazinyl, morpholino and methyl-thienyl.
  • Particularly preferred substituted R 2 groups include, but are not limited to, 4-methoxy-phenyl, 3-methoxyphenyl, 4-ethoxy-phenyl, 3-ethoxy-phenyl, 4-fluoro-phenyl, 4-chloro-phenyl, 3,4- bisoxymethylene-phenyl, 4-methylthienyl, 4-cyanophenyl, 4-phenoxyphenyl, quinolin-3-yl and quinolin-6-yl, isoquinolin-3-yl and isoquinolin-6-yl, 2-thienyl, 2-furanyl, methoxynaphthyl, and naphthyl.
  • R 2 is halo or dihalo. In one embodiment, R 2 is -F or -F 2 , which substituents are illustrated below as (III) and (IV) respectively:
  • R is independently selected from R, C0 2 R, COR, CHO, C0 2 H, and halo.
  • R D is independently R.
  • R D is independently halo.
  • R 6 is independently selected from H, R, OH, OR, SH, SR, NH 2 , NHR, NRR', N0 2 , Me 3 Sn- and Halo.
  • R 6 is independently selected from H, OH, OR, SH, NH 2 , N0 2 and Halo. In one embodiment, R 6 is independently selected from H and Halo.
  • R 6 is independently H.
  • R 6 and R 7 together form a group -0-(CH 2 ) p -0-, where p is 1 or 2.
  • R' is independently selected from H, R, OH, OR, SH, SR, NH 2 , NHR, NRR', N0 2 , Me 3 Sn and halo.
  • R 7 is independently OR.
  • R 7 is independently OR 7A , where R 7A is independently optionally substituted Ci -6 alkyl.
  • R 7A is independently optionally substituted saturated Ci -6 alkyl.
  • R 7A is independently optionally substituted C 2-4 alkenyl.
  • R 7A is independently Me.
  • R 7A is independently CH 2 Ph.
  • R 7A is independently allyl.
  • the compound is a dimer where the R groups of each monomer form together a dimer bridge having the formula X-R"-X linking the monomers.
  • R 9 is independently selected from H, R, OH, OR, SH, SR, H 2 , HR,
  • R 9 is independently H.
  • R 9 is independently R or OR.
  • compatible linkers such as those described herein attach the KREMEN2 antibody to the PBD drug moiety through covalent bond(s) at the R 10 position (i.e., N10).
  • Q is independently selected from O, S and NH.
  • Q is independently O.
  • Q is independently S.
  • Q is independently NH.
  • R 11 is either H, or R or, where Q is O, may be S0 3 M where M is a metal cation.
  • the cation may be Na + .
  • R 11 is H.
  • R 11 is R.
  • R 11 is S0 3 M where M is a metal cation.
  • the cation may be Na + .
  • R 11 is H.
  • R 11 is R.
  • X is selected from O, S, or N(H).
  • X is O. l
  • R" is a C3-12 alkylene group, which chain may be interrupted by one or more heteroatoms, e.g. O, S, N(H), NMe and/or aromatic rings, e.g. benzene or pyridine, which rings are optionally substituted.
  • heteroatoms e.g. O, S, N(H), NMe and/or aromatic rings, e.g. benzene or pyridine, which rings are optionally substituted.
  • R" is a C 3- i 2 alkylene group, which chain may be interrupted by one or more heteroatoms and/or aromatic rings, e.g. benzene or pyridine.
  • the alkylene group is optionally interrupted by one or more heteroatoms selected from O, S, and NMe and/or aromatic rings, which rings are optionally substituted.
  • the aromatic ring is a C 5-2 o arylene group, where arylene pertains to a divalent moiety obtained by removing two hydrogen atoms from two aromatic ring atoms of an aromatic compound, which moiety has from 5 to 20 ring atoms.
  • R" is a C 3- i 2 alkylene group, which chain may be interrupted by one or more heteroatoms, e.g. O, S, N(H), NMe and/or aromatic rings, e.g. benzene or pyridine, which rings are optionally substituted by NH 2 .
  • heteroatoms e.g. O, S, N(H), NMe and/or aromatic rings, e.g. benzene or pyridine, which rings are optionally substituted by NH 2 .
  • R" is a C 3- i 2 alkylene group.
  • R" is selected from a C 3 , C 5 , C 7 , C9 and a Cn alkylene group.
  • R" is selected from a C 3 , C 5 and a C 7 alkylene group.
  • R" is selected from a C 3 and a C 5 alkylene group.
  • R" is a C 3 alkylene group.
  • R" is a C 5 alkylene group.
  • alkylene groups listed above may be optionally interrupted by one or more heteroatoms and/or aromatic rings, e.g. benzene or pyridine, which rings are optionally substituted.
  • alkylene groups listed above may be optionally interrupted by one or more heteroatoms and/or aromatic rings, e.g. benzene or pyridine.
  • alkylene groups listed above may be unsubstituted linear aliphatic alkylene groups.
  • R and R' In one embodiment, R is independently selected from optionally substituted C 1-12 alkyl, C3-20 heterocyclyl and C5-20 aryl groups.
  • R is independently optionally substituted C 1-12 alkyl.
  • R is independently optionally substituted C 3-2 o heterocyclyl.
  • R is independently optionally substituted C5-20 aryl.
  • R 2 Described above in relation to R 2 are various embodiments relating to preferred alkyl and aryl groups and the identity and number of optional substituents.
  • the preferences set out for R 2 as it applies to R are applicable, where appropriate, to all other groups R, for examples where R 6 , R 7 , R 8 or R 9 is R.
  • a compound having a substituent group -NRR' having a substituent group -NRR'.
  • R and R' together with the nitrogen atom to which they are attached form an optionally substituted 4-, 5-, 6- or 7-membered heterocyclic ring.
  • the ring may contain a further heteroatom, for example N, O or S.
  • the heterocyclic ring is itself substituted with a group R.
  • the substituent may be on the N heteroatom.
  • PBDs 1 - 5 In addition to the aforementioned PBDs certain dimeric PBDs have been shown to be particularly active and may be used in conjunction with the instant invention.
  • antibody drug conjugates i.e., ADCs 1 - 6 as disclosed herein
  • PBDs 1-5 comprise the cytotoxic warhead released following separation of a linker such as those described in more detail herein.
  • the synthesis of each of PBD 1 - 5 as a component of drug-linker compounds is presented in great detail in WO 2014/130879 which is hereby incorporated by reference as to such synthesis.
  • cytotoxic compounds that may comprise selected warheads of the ADCs of the present invention could readily be generated and employed as set forth herein.
  • PBD compounds that may be released from the disclosed ADCs upon separation from a linker are set forth immediately below:
  • each of the aforementioned dimeric PBD warheads would be preferably be released upon internalization by the target cell and destruction of the linker.
  • certain linkers will comprise cleavable linkers which may incorporate a self-immolation moiety that allows release of the active PBD warhead without retention of any part of the linker.
  • the PBD warhead Upon release the PBD warhead will then bind and cross-link with the target cell's DNA. Such binding reportedly blocks division of the target cancer cell without distorting its DNA helix, thus potentially avoiding the common phenomenon of emergent drug resistance.
  • the warhead may be attached to the KREMEN2 targeting moiety through a cleavable linker that does not comprise a self-immolating moiety.
  • each of the disclosed PBDs have two sp 2 centers in each C-ring, which may allow for stronger binding in the minor groove of DNA (and hence greater toxicity), than for compounds with only one sp 2 center in each C-ring.
  • the disclosed PBDs may prove to be particularly effective for the treatment of proliferative disorders.
  • the antibodies of the present invention may also be conjugated to biological response modifiers.
  • the biological response modifier will comprise interleukin 2, interferons, or various types of colony-stimulating factors (e.g., CSF, GM-CSF, G-CSF).
  • the associated drug moiety can be a polypeptide possessing a desired biological activity.
  • proteins may include, for example, a toxin such as abrin, ricin A, Onconase (or another cytotoxic RNase), pseudomonas exotoxin, cholera toxin, diphtheria toxin; an apoptotic agent such as tumor necrosis factor e.g.
  • TNF- a or TNF- ⁇ a-interferon, ⁇ -interferon, nerve growth factor, platelet derived growth factor, tissue plasminogen activator, AFM I (WO 97/33899), AFM II (WO 97/34911), Fas Ligand (Takahashi et al, 1994, PMID: 7826947), and VEGI (WO 99/23105), a thrombotic agent, an anti -angiogenic agent, e.g., angiostatin or endostatin, a lymphokine, for example, interleukin- 1 (IL-1), interleukin-2 (IL-2), interleukin-6 (IL-6), granulocyte macrophage colony stimulating factor (GM-CSF), and granulocyte colony stimulating factor (G-CSF), or a growth factor e.g., growth hormone (GH).
  • IL-1 interleukin- 1
  • IL-2 interleukin-2
  • IL-6 interleukin-6
  • the antibodies of the invention, or fragments or derivatives thereof are conjugated to a diagnostic or detectable agent, marker or reporter which may be, for example, a biological molecule (e.g., a peptide or nucleotide), a small molecule, fluorophore, or radioisotope.
  • a diagnostic or detectable agent e.g., a biological molecule (e.g., a peptide or nucleotide), a small molecule, fluorophore, or radioisotope.
  • Labeled antibodies can be useful for monitoring the development or progression of a hyperproliferative disorder or as part of a clinical testing procedure to determine the efficacy of a particular therapy including the disclosed antibodies (i.e. theragnostics) or to determine a future course of treatment.
  • markers or reporters may also be useful in purifying the selected antibody, for use in antibody analytics (e.g., epitope binding or antibody binning), separating or isolating tumorigenic cells or in preclin
  • Such diagnosis, analysis and/or detection can be accomplished by coupling the antibody to detectable substances including, but not limited to, various enzymes comprising for example horseradish peroxidase, alkaline phosphatase, beta-galactosidase, or acetylcholinesterase; prosthetic groups, such as but not limited to streptavidinlbiotin and avidin/biotin; fluorescent materials, such as but not limited to, umbelliferone, fluorescein, fluorescein isothiocynate, rhodamine, dichlorotriazinylamine fluorescein, dansyl chloride or phycoerythrin; luminescent materials, such as but not limited to, luminol; bioluminescent materials, such as but not limited to, luciferase, luciferin,
  • radioactive materials such as but not limited to iodine ( I, I, I, I,), carbon ( 14 C), sulfur ( 35 S), tritium ( 3 H), indium ( 115 In, 113 In, 112 In, m In), technetium ( 99 Tc), thallium ( 201 Ti), gallium ( 68 Ga, 67 Ga), palladium ( 103 Pd), molybdenum ( 99 Mo), xenon ( 133 Xe), fluorine ( 18 F), 153 Sm, 177 Lu, 159 Gd, 149 Pm, 140 La, 175 Yb, 166 Ho, 90 Y, 47 Sc, 186 Re, 188 Re, 142 Pr, 105 Rh, 97 Ru, 68 Ge, 57 Co, 65 Zn, 85 Sr, 32 P, 89 Zr, 153 Gd, 169 Yb, 51 Cr, 54 Mn, 75 Se, 113 Sn, and 117 Tin;
  • radioactive materials such as but not limited to iodine
  • the antibodies or fragments thereof can be fused or conjugated to marker sequences or compounds, such as a peptide or fluorophore to facilitate purification or diagnostic or analytic procedures such as immunohistochemistry, bio-layer interferometry, surface plasmon resonance, flow cytometry, competitive ELISA, FACs, etc.
  • the marker comprises a histidine tag such as that provided by the pQE vector (Qiagen), among others, many of which are commercially available.
  • peptide tags useful for purification include, but are not limited to, the hemagglutinin "HA” tag, which corresponds to an epitope derived from the influenza hemagglutinin protein (Wilson et al., 1984, Cell 37:767) and the "flag" tag (U.S.P.N. 4,703,004).
  • the antibodies of the invention may be conjugated with biocompatible modifiers that may be used to adjust, alter, improve or moderate antibody characteristics as desired.
  • biocompatible modifiers that may be used to adjust, alter, improve or moderate antibody characteristics as desired.
  • antibodies or fusion constructs with increased in vivo half- lives can be generated by attaching relatively high molecular weight polymer molecules such as commercially available polyethylene glycol (PEG) or similar biocompatible polymers.
  • PEG polyethylene glycol
  • PEG polyethylene glycol
  • PEG can be attached to antibodies or antibody fragments or derivatives with or without a multifunctional linker either through conjugation of the PEG to the N- or C- terminus of said antibodies or antibody fragments or via epsilon-amino groups present on lysine residues.
  • Linear or branched polymer derivatization that results in minimal loss of biological activity may be used.
  • the degree of conjugation can be closely monitored by SDS-PAGE and mass spectrometry to ensure optimal conjugation of PEG molecules to antibody molecules.
  • Unreacted PEG can be separated from antibody-PEG conjugates by, e.g., size exclusion or ion-exchange chromatography.
  • the disclosed antibodies can be conjugated to albumin in order to make the antibody or antibody fragment more stable in vivo or have a longer half-life in vivo.
  • the techniques are well known in the art, see e.g., WO 93/15199, WO 93/15200, and WO 01/77137; and EP 0 413, 622.
  • Other biocompatible conjugates are evident to those of ordinary skill and may readily be identified in accordance with the teachings herein.
  • payloads compatible with the instant invention comprise one or more warheads and, optionally, a linker associating the warheads with the antibody targeting agent.
  • Numerous linker compounds can be used to conjugate the antibodies of the invention to the relevant warhead.
  • the linkers merely need to covalently bind with the reactive residue on the antibody (preferably a cysteine or lysine) and the selected drug compound. Accordingly, any linker that reacts with the selected antibody residue and may be used to provide the relatively stable conjugates (site-specific or otherwise) of the instant invention is compatible with the teachings herein.
  • Compatible linkers can advantageously bind to reduced cysteines and lysines, which are nucleophilic.
  • Conjugation reactions involving reduced cysteines and lysines include, but are not limited to, thiol-maleimide, thiol -halogeno (acyl halide), thiol-ene, thiol-yne, thiol-vinylsulfone, thiol-bisulfone, thiol-thiosulfonate, thiol-pyridyl disulfide and thiol-parafluoro reactions.
  • thiol-maleimide bioconjugation is one of the most widely used approaches due to its fast reaction rates and mild conjugation conditions.
  • One issue with this approach is the possibility of the retro-Michael reaction and loss or transfer of the maleimido-linked payload from the antibody to other proteins in the plasma, such as, for example, human serum albumin.
  • the use of selective reduction and site-specific antibodies as set forth herein in the Examples below may be used to stabilize the conjugate and reduce this undesired transfer.
  • Thiol-acyl halide reactions provide bioconjugates that cannot undergo retro-Michael reaction and therefore are more stable.
  • thiol-halide reactions in general have slower reaction rates compared to maleimide-based conjugations and are thus not as efficient in providing undesired drug to antibody ratios.
  • Thiol-pyridyl disulfide reaction is another popular bioconjugation route. The pyridyl disulfide undergoes fast exchange with free thiol resulting in the mixed disulfide and release of pyridine-2-thione. Mixed disulfides can be cleaved in the reductive cell environment releasing the payload.
  • Other approaches gaining more attention in bioconjugation are thiol-vinylsulfone and thiol-bisulfone reactions, each of which are compatible with the teachings herein and expressly included within the scope of the invention.
  • compatible linkers will confer stability on the ADCs in the extracellular environment, prevent aggregation of the ADC molecules and keep the ADC freely soluble in aqueous media and in a monomeric state.
  • the ADC Before transport or delivery into a cell, the ADC is preferably stable and remains intact, i.e. the antibody remains linked to the drug moiety. While the linkers are stable outside the target cell they may be designed to be cleaved or degraded at some efficacious rate inside the cell. Accordingly, an effective linker will: (i) maintain the specific binding properties of the antibody; (ii) allow intracellular delivery of the conjugate or drug moiety; (iii) remain stable and intact, i.e.
  • the stability of the ADC may be measured by standard analytical techniques such as HPLC/UPLC, mass spectroscopy, HPLC, and the separation/analysis techniques LC/MS and LC/MS/MS.
  • covalent attachment of the antibody and the drug moiety requires the linker to have two reactive functional groups, i.e. bivalency in a reactive sense.
  • Bivalent linker reagents that are useful to attach two or more functional or biologically active moieties, such as MMAE and antibodies are known, and methods have been described to provide resulting conjugates compatible with the teachings herein.
  • Linkers compatible with the present invention may broadly be classified as cleavable and non- cleavable linkers.
  • Cleavable linkers which may include acid-labile linkers (e.g., oximes and hydrozones), protease cleavable linkers and disulfide linkers, are internalized into the target cell and are cleaved in the endosomal-lysosomal pathway inside the cell. Release and activation of the cytotoxin relies on endosome/lysosome acidic compartments that facilitate cleavage of acid-labile chemical linkages such as hydrazone or oxime.
  • acid-labile linkers e.g., oximes and hydrozones
  • protease cleavable linkers and disulfide linkers are internalized into the target cell and are cleaved in the endosomal-lysosomal pathway inside the cell. Release and activation of the cytotoxin relies on endosome/lyso
  • linkers containing mixed disulfides provide an approach by which cytotoxic payloads are released intracellularly as they are selectively cleaved in the reducing environment of the cell, but not in the oxygen-rich environment in the bloodstream.
  • compatible non- cleavable linkers containing amide linked polyethylene glycol or alkyl spacers liberate toxic payloads during lysosomal degradation of the ADC within the target cell.
  • selection of linker will depend on the particular drug used in the conjugate, the particular indication and the antibody target.
  • certain embodiments of the invention comprise a linker that is cleavable by a cleaving agent that is present in the intracellular environment (e.g., within a lysosome or endosome or caveolae).
  • the linker can be, for example, a peptidyl linker that is cleaved by an intracellular peptidase or protease enzyme, including, but not limited to, a lysosomal or endosomal protease.
  • the peptidyl linker is at least two amino acids long or at least three amino acids long.
  • Cleaving agents can include cathepsins B and D and plasmin, each of which is known to hydrolyze dipeptide drug derivatives resulting in the release of active drug inside target cells.
  • Exemplary peptidyl linkers that are cleavable by the thiol -dependent protease cathepsin-B are peptides comprising Phe-Leu since cathepsin-B has been found to be highly expressed in cancerous tissue. Other examples of such linkers are described, for example, in U.S. P.N. 6,214,345.
  • the peptidyl linker cleavable by an intracellular protease is a Val-Cit linker, a Val-Ala linker or a Phe-Lys linker.
  • intracellular proteolytic release of the therapeutic agent is that the agent is typically attenuated when conjugated and the serum stabilities of the conjugates are relatively high.
  • the cleavable linker is pH-sensitive.
  • the pH-sensitive linker will be hydrolyzable under acidic conditions.
  • an acid-labile linker that is hydrolyzable in the lysosome e.g., a hydrazone, oxime, semicarbazone, thiosemicarbazone, cis-aconitic amide, orthoester, acetal, ketal, or the like
  • Such linkers are relatively stable under neutral pH conditions, such as those in the blood, but are unstable (e.g., cleavable) at below pH 5.5 or 5.0 which is the approximate pH of the lysosome.
  • the linker is cleavable under reducing conditions (e.g., a disulfide linker).
  • a disulfide linker e.g., a disulfide linker.
  • disulfide linkers are known in the art, including, for example, those that can be formed using SAT A (N-succinimidyl-S-acetylthioacetate), SPDP (N-succinimidyl-3-(2- pyridyldithio)propionate), SPDB (N-succinimidyl-3-(2-pyridyldithio) butyrate) and SMPT (N- succinimidyl-oxycarbonyl-alpha-methyl-alpha-(2-pyridyl-dithio)toluene).
  • SAT A N-succinimidyl-S-acetylthioacetate
  • SPDP N-succinimidyl-3-(2- pyri
  • the linker is a malonate linker (Johnson et al., 1995, Anticancer Res. 15: 1387-93), a maleimidobenzoyl linker (Lau et al., 1995, Bioorg-Med-Chem. 3(10): 1299-1304), or a 3'-N-amide analog (Lau et al., 1995, Bioorg-Med-Chem. 3(10): 1305-12).
  • the selected linker will comprise a compound of the formula:
  • CBA i.e. cell binding agent
  • L 1 comprises a linker unit and optionally a cleavable linker unit
  • A is a connecting group (optionally comprising a spacer) connecting L 1 to a reactive residue on the antibody
  • L 2 is preferably a covalent bond
  • U which may or may not be present, can comprise all or part of a self-immolative unit that facilitates a clean separation of the linker from the warhead at the tumor site.
  • compatible linkers may comprise:
  • CBA i.e. cell binding agent
  • L 1 comprises a linker and optionally a cleavable linker
  • A is a connecting group (optionally comprising a spacer) connecting L 1 to a reactive residue on the antibody
  • L 1 and L 2 can vary widely. These groups are chosen on the basis of their cleavage characteristics, which may be dictated by the conditions at the site to which the conjugate is delivered. Those linkers that are cleaved by the action of enzymes are preferred, although linkers that are cleavable by changes in pH (e.g. acid or base labile), temperature or upon irradiation (e.g. photolabile) may also be used. Linkers that are cleavable under reducing or oxidizing conditions may also find use in the present invention.
  • pH e.g. acid or base labile
  • temperature or upon irradiation e.g. photolabile
  • L 1 may comprise a contiguous sequence of amino acids.
  • the amino acid sequence may be the target substrate for enzymatic cleavage, thereby allowing release of the drug.
  • L 1 is cleavable by the action of an enzyme.
  • the enzyme is an esterase or a peptidase.
  • L 1 is as a cathepsin labile linker.
  • L 1 comprises a dipeptide.
  • the dipeptide may be represented as -NH-X 1 -X 2 -CO-, where -NH- and -CO- represent the N- and C-terminals of the amino acid groups X 1 and X 2 respectively.
  • the amino acids in the dipeptide may be any combination of natural amino acids.
  • the linker is a cathepsin labile linker
  • the dipeptide may be the site of action for cathepsin-mediated cleavage.
  • CO and H may represent that side chain functionality.
  • the group -X 1 -X 2 - in dipeptide, - H-X 1 -X 2 -CO- is selected from: -Phe- Lys-, -Val-Ala-, -Val-Lys-, -Ala-Lys-, -Val-Cit-, -Phe-Cit-, -Leu-Cit-, -Ile-Cit-, -Phe-Arg- and -Trp- Cit- where Cit is citrulline.
  • the group -Xi-X 2 - in dipeptide, - H-Xi-X 2 -CO- is selected from:-Phe-Lys-, -Val- Ala-, -Val-Lys-, -Ala-Lys-, and -Val-Cit-.
  • the group -Xi-X 2 - in dipeptide, - H-X 1 -X 2 -CO-, is -Phe-Lys- or -Val-Ala- or Val-Cit.
  • the dipeptide will comprise -Val-Ala-.
  • L 2 is present in the form of a covalent bond.
  • the enzyme cleaves the bond between L 1 and L 2 .
  • An amino group of L 1 that connects to L 2 may be the N-terminus of an amino acid or may be derived from an amino group of an amino acid side chain, for example a lysine amino acid side chain.
  • a carboxyl group of L 1 that connects to L 2 may be the C-terminus of an amino acid or may be derived from a carboxyl group of an amino acid side chain, for example a glutamic acid amino acid side chain.
  • a hydroxyl group of L 1 that connects to L 2 may be derived from a hydroxyl group of an amino acid side chain, for example a serine amino acid side chain.
  • amino acid side chain includes those groups found in: (i) naturally occurring amino acids such as alanine, arginine, asparagine, aspartic acid, cysteine, glutamine, glutamic acid, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, and valine; (ii) minor amino acids such as ornithine and citrulline; (iii) unnatural amino acids, beta-amino acids, synthetic analogs and derivatives of naturally occurring amino acids; and (iv) all enantiomers, diastereomers, isomerically enriched, isotopically labelled (e.g. 2 H, 3 H, 14 C, 15 N), protected forms, and racemic mixtures thereof.
  • naturally occurring amino acids such as alanine, arginine, asparagine, aspartic acid, cysteine, glutamine
  • n is 0 to 3.
  • the phenylene ring is optionally substituted with one, two or three substituents. In one embodiment, the phenylene group is optionally substituted with halo, N0 2 , alkyl or hydroxyalkyl.
  • Y is NH
  • n is 0 or 1. Preferably, n is 0.
  • the self-immolative linker may be referred to as a p-aminobenzylcarbonyl linker (PABC).
  • PABC p-aminobenzylcarbonyl linker
  • the linker may include a self-immolative linker and the dipeptide together form the group -NH-Val-Cit-CO-NH-PABC-.
  • the linker may comprise the group -NH-Val-Ala-CO-NH-PABC-, which is illustrated below:
  • the asterisk indicates the point of attachment to the selected cytotoxic moiety
  • the wavy line indicates the point of attachment to the remaining portion of the linker (e.g., the spacer- antibody binding segments) which may be conjugated to the antibody.
  • A is a covalent bond.
  • L 1 and the antibody are directly connected.
  • L 1 comprises a contiguous amino acid sequence
  • the N-terminus of the sequence may connect directly to the antibody residue.
  • A is a spacer group.
  • L 1 and the antibody are indirectly connected.
  • the drug linkers of the instant invention will preferably be linked to reactive thiol nucleophiles on cysteines, including free cysteines.
  • the cysteines of the antibodies may be made reactive for conjugation with linker reagents by treatment with various reducing agent such as DTT or TCEP or mild reducing agents as set forth herein.
  • the drug linkers of the instant invention will preferably be linked to a lysine.
  • the linker contains an electrophilic functional group for reaction with a nucleophilic functional group on the antibody.
  • Nucleophilic groups on antibodies include, but are not limited to: (i) N-terminal amine groups, (ii) side chain amine groups, e.g. lysine, (iii) side chain thiol groups, e.g. cysteine, and (iv) sugar hydroxyl or amino groups where the antibody is glycosylated.
  • Amine, thiol, and hydroxyl groups are nucleophilic and capable of reacting to form covalent bonds with electrophilic groups on linker moieties and linker reagents including: (i) maleimide groups (ii) activated disulfides, (iii) active esters such as NHS (N-hydroxysuccinimide) esters, HOBt (N-hydroxybenzotriazole) esters, haloformates, and acid halides; (iv) alkyl and benzyl halides such as haloacetamides; and (v) aldehydes, ketones and carboxyl groups.
  • maleimide groups ii) activated disulfides, (iii) active esters such as NHS (N-hydroxysuccinimide) esters, HOBt (N-hydroxybenzotriazole) esters, haloformates, and acid halides
  • active esters such as NHS (N-hydroxysuccinimide) esters, HOB
  • connection between a cysteine (including a free cysteine of a site-specific antibody) and the drug-linker moiety is through a thiol residue and a terminal maleimide group of present on the linker.
  • the connection between the antibody and the drug-linker may be:
  • the S atom is preferably derived from a site-specific free cysteine.
  • the binding moiety may comprise a terminal bromo or iodoacetamide that may be reacted with activated residues on the antibody to provide the desired conjugate.
  • a compatible anti-KREMEN2 antibody including site-specific antibodies
  • the invention provides methods of making compatible antibody drug conjugates comprising conjugating an anti- KREMEN2 antibody with a drug-linker compound selected from the group consisting of:
  • DL will be used as an abbreviation for "drug- linker” (or linker-drug “L-D” in the formula Ab-[L-D]n ) and will comprise drug linkers 1 - 6 (i.e., DL1, DL2, DL3, DL4 DL5, and DL6) as set forth above.
  • drug linkers 1 - 6 i.e., DL1, DL2, DL3, DL4 DL5, and DL6
  • DL1 and DL6 comprise the same warhead and same dipeptide subunit but differ in the connecting group spacer. Accordingly, upon cleavage of the linker both DL1 and DL6 will release PBD1.
  • linker appended terminal maleimido moiety (DL1 - DL4 and DL6) or iodoacetamide moiety (DL5) may be conjugated to free sulfhydryl(s) on the selected KREMEN2 antibody using art-recognized techniques.
  • Synthetic routes for the aforementioned compounds are set forth in WO2014/130879 which is incorporated herein by reference explicitly for the synthesis of the aforementioned DL compounds while specific methods of conjugating such PBDs linker combinations are set forth in the Examples below.
  • the present invention relates to KREMEN2 antibodies conjugated to the disclosed DL moieties to provide KREMEN2 immunoconjugates substantially set forth in ADCs 1 - 6 immediately below. Accordingly, in certain aspects the invention is directed to an antibody drug conjugate selected from the group consisting of:
  • ADC 6 wherein Ab comprises an anti-KREMEN2 antibody or immunoreactive fragment thereof and n is an integer from 1 to 20. In certain embodiments n will comprise an integer from 1 to 8 and in selected embodiments n will comprise 2 or 4.
  • ADC6 as set forth above may comprise a KREMEN2 antibody conjugated to 1, 2, 3, 4, 5, 6, 7 or 8 or more payloads and that compositions of such ADCs will generally comprise a mixture of drug loaded species.
  • the KREMEN2 PBD ADCs of the invention will comprise an anti- KREMEN2 antibody as set forth in the appended Examples or an immunoreactive fragment thereof.
  • ADC 3 will comprise hSC78.43sslMJ (e.g., hSC78.43sslMJ PBD1).
  • the KREMEN2 PBD ADCs of the invention will comprise hSC78.56sslMJ (e.g., hSC78.56sslMJ PBD1).
  • the ADCs will preferably comprise 2 payloads.
  • the KREMEN2 ADC will comprise ADC6 wherein n is 2.
  • ADCs of the instant invention may be generated through conjugation of drugs to solvent-exposed amino groups of lysine residues present in the selected antibody.
  • Still other embodiments comprise activation of N-terminal threonine and serine residues which may then be used to attach the disclosed payloads to the antibody.
  • the selected conjugation methodology will preferably be tailored to optimize the number of drugs attached to the antibody and provide a relatively high therapeutic index.
  • cysteine residues will be deprotonated to generate a thiolate nucleophile which may be reacted with soft electrophiles such as maleimides and iodoacetamides.
  • soft electrophiles such as maleimides and iodoacetamides.
  • reagents for such conjugations may react directly with a cysteine thiol to form the conjugated protein or with a linker-drug to form a linker-drug intermediate.
  • linker In the case of a linker, several routes, employing organic chemistry reactions, conditions, and reagents are known to those skilled in the art, including: (1) reaction of a cysteine group of the protein of the invention with a linker reagent, to form a protein-linker intermediate, via a covalent bond, followed by reaction with an activated compound; and (2) reaction of a nucleophilic group of a compound with a linker reagent, to form a drug-linker intermediate, via a covalent bond, followed by reaction with a cysteine group of a protein of the invention.
  • bifunctional (or bivalent) linkers are useful in the present invention.
  • the bifunctional linker may comprise a thiol modification group for covalent linkage to the cysteine residue(s) and at least one attachment moiety (e.g., a second thiol modification moiety) for covalent or non-covalent linkage to the compound.
  • antibodies Prior to conjugation, antibodies may be made reactive for conjugation with linker reagents by treatment with a reducing agent such as dithiothreitol (DTT) or (tm(2-carboxyethyl)phosphine (TCEP).
  • a reducing agent such as dithiothreitol (DTT) or (tm(2-carboxyethyl)phosphine (TCEP).
  • additional nucleophilic groups can be introduced into antibodies through the reaction of lysines with reagents, including but not limited to, 2-iminothiolane (Traut's reagent), SAT A, SATP or SAT(PEG)4, resulting in conversion of an amine into a thiol.
  • cysteine thiol or lysine amino groups are nucleophilic and capable of reacting to form covalent bonds with electrophilic groups on linker reagents or compound-linker intermediates or drugs including: (i) active esters such as NHS esters, HOBt esters, haloformates, and acid halides; (ii) alkyl and benzyl halides, such as haloacetamides; (iii) aldehydes, ketones, carboxyl, and maleimide groups; and (iv) disulfides, including pyridyl disulfides, via sulfide exchange.
  • active esters such as NHS esters, HOBt esters, haloformates, and acid halides
  • alkyl and benzyl halides such as haloacetamides
  • aldehydes ketones, carboxyl, and maleimide groups
  • disulfides including pyridyl disulfides, via s
  • Nucleophilic groups on a compound or linker include, but are not limited to amine, thiol, hydroxyl, hydrazide, oxime, hydrazine, thiosemicarbazone, hydrazine carboxylate, and arylhydrazide groups capable of reacting to form covalent bonds with electrophilic groups on linker moieties and linker reagents.
  • Conjugation reagents commonly include maleimide, haloacetyl, iodoacetamide succinimidyl ester, isothiocyanate, sulfonyl chloride, 2,6-dichlorotriazinyl, pentafluorophenyl ester, and phosphoramidite, although other functional groups can also be used.
  • methods include, for example, the use of maleimides, iodoacetimides or haloacetyl/alkyl halides, aziridne, acryloyl derivatives to react with the thiol of a cysteine to produce a thioether that is reactive with a compound.
  • Disulphide exchange of a free thiol with an activated piridyldisulphide is also useful for producing a conjugate (e.g., use of 5-thio-2-nitrobenzoic (T B) acid).
  • a maleimide is used.
  • lysine may also be used as a reactive residue to effect conjugation as set forth herein.
  • the nucleophilic lysine residue is commonly targeted through amine- reactive succinimidylesters.
  • the pH of the aqueous solution must be below the pKa of the lysine ammonium group, which is around 10.5, so the typical pH of the reaction is about 8 and 9.
  • the common reagent for the coupling reaction is NHS-ester which reacts with nucleophilic lysine through a lysine acylation mechanism.
  • isocyanates and isothiocyanates which also may be used in conjunction with the teachings herein to provide ADCs.
  • Methods are also known in the art for conjugating a compound to a threonine or serine residue (preferably a N-terminal residue).
  • a threonine or serine residue preferably a N-terminal residue.
  • carbonyl precursors are derived from the 1,2-aminoalcohols of serine or threonine, which can be selectively and rapidly converted to aldehyde form by periodate oxidation.
  • Reaction of the aldehyde with a 1,2- aminothiol of cysteine in a compound to be attached to a protein of the invention forms a stable thiazolidine product. This method is particularly useful for labeling proteins at N-terminal serine or threonine residues.
  • reactive thiol groups may be introduced into the selected antibody (or fragment thereof) by introducing one, two, three, four, or more free cysteine residues (e.g., preparing antibodies comprising one or more free non-native cysteine amino acid residues).
  • free cysteine residues e.g., preparing antibodies comprising one or more free non-native cysteine amino acid residues.
  • site-specific antibodies or engineered antibodies allow for conjugate preparations that exhibit enhanced stability and substantial homogeneity due, at least in part, to the provision of engineered free cysteine site(s) and/or the novel conjugation procedures set forth herein.
  • the present invention additionally provides for the selective reduction of certain prepared free cysteine sites and attachment of the drug linker to the same.
  • the conjugation specificity promoted by the engineered sites and the selective reduction allows for a high percentage of site directed conjugation at the desired positions.
  • efficient conjugation rates may be obtained which considerably reduces unwanted high-DAR contaminants and non-specific toxicity.
  • the engineered constructs and disclosed novel conjugation methods comprising selective reduction provide ADC preparations having improved pharmacokinetics and/or pharmacodynamics and, potentially, an improved therapeutic index.
  • site-specific constructs present free cysteine(s) which, when reduced, comprise thiol groups that are nucleophilic and capable of reacting to form covalent bonds with electrophilic groups on linker moieties such as those disclosed above.
  • antibodies of the instant invention may have reducible unpaired interchain or intrachain cysteines or introduced non-native cysteines, i.e. cysteines providing such nucleophilic groups.
  • the reaction of free sulfhydryl groups of the reduced free cysteines and the terminal maleimido or haloacetamide groups of the disclosed drug-linkers will provide the desired conjugation.
  • free cysteines of the antibodies may be made reactive for conjugation with linker reagents by treatment with a reducing agent such as dithiothreitol (DTT) or (tris (2- carboxyethyl)phosphine (TCEP).
  • DTT dithiothreitol
  • TCEP tris (2- carboxyethyl)phosphine
  • the free cysteines of engineered antibodies may be selectively reduced to provide enhanced site-directed conjugation and a reduction in unwanted, potentially toxic contaminants.
  • More specifically "stabilizing agents” such as arginine have been found to modulate intra- and inter-molecular interactions in proteins and may be used, in conjunction with selected reducing agents (preferably relatively mild), to selectively reduce the free cysteines and to facilitate site-specific conjugation as set forth herein.
  • selected reducing agents preferably relatively mild
  • this selective reduction may be effected by the use of certain reducing agents or certain reducing agent concentrations.
  • selective reduction of an engineered construct will comprise the use of stabilization agents in combination with reducing agents (including mild reducing agents).
  • stabilization agents e.g., arginine
  • the term "selective conjugation” shall mean the conjugation of an engineered antibody that has been selectively reduced in the presence of a cytotoxin as described herein.
  • stabilizing agents e.g., arginine
  • compatible antibody constructs and selective conjugation techniques and reagents are extensively disclosed in WO2015/031698 which is incorporated herein specifically as to such methodology and constructs.
  • such stabilizing agents may act to modulate the electrostatic microenvironment and/or modulate conformational changes at the desired conjugation site, thereby allowing relatively mild reducing agents (which do not materially reduce intact native disulfide bonds) to facilitate conjugation at the desired free cysteine site(s).
  • Such agents e.g., certain amino acids
  • Such agents are known to form salt bridges (via hydrogen bonding and electrostatic interactions) and can modulate protein-protein interactions in such a way as to impart a stabilizing effect that may cause favorable conformational changes and/or reduce unfavorable protein-protein interactions.
  • such agents may act to inhibit the formation of undesired intramolecular (and intermolecular) cysteine-cysteine bonds after reduction thus facilitating the desired conjugation reaction wherein the engineered site-specific cysteine is bound to the drug (preferably via a linker). Since selective reduction conditions do not provide for the significant reduction of intact native disulfide bonds, the subsequent conjugation reaction is naturally driven to the relatively few reactive thiols on the free cysteines (e.g., preferably 2 free thiols per antibody). As previously alluded to, such techniques may be used to considerably reduce levels of non-specific conjugation and corresponding unwanted DAR species in conjugate preparations fabricated in accordance with the instant disclosure.
  • stabilizing agents compatible with the present invention will generally comprise compounds with at least one moiety having a basic pKa.
  • the moiety will comprise a primary amine while in other embodiments the amine moiety will comprise a secondary amine.
  • the amine moiety will comprise a tertiary amine or a guanidinium group.
  • the amine moiety will comprise an amino acid while in other compatible embodiments the amine moiety will comprise an amino acid side chain.
  • the amine moiety will comprise a proteinogenic amino acid.
  • the amine moiety comprises a non- proteinogenic amino acid.
  • compatible stabilizing agents may comprise arginine, lysine, proline and cysteine. In certain preferred embodiments the stabilizing agent will comprise arginine. In addition, compatible stabilizing agents may include guanidine and nitrogen containing heterocycles with basic pKa.
  • compatible stabilizing agents comprise compounds with at least one amine moiety having a pKa of greater than about 7.5, in other embodiments the subject amine moiety will have a pKa of greater than about 8.0, in yet other embodiments the amine moiety will have a pKa greater than about 8.5 and in still other embodiments the stabilizing agent will comprise an amine moiety having a pKa of greater than about 9.0.
  • Other embodiments will comprise stabilizing agents where the amine moiety will have a pKa of greater than about 9.5 while certain other embodiments will comprise stabilizing agents exhibiting at least one amine moiety having a pKa of greater than about 10.0.
  • the stabilizing agent will comprise a compound having the amine moiety with a pKa of greater than about 10.5, in other embodiments the stabilizing agent will comprise a compound having a amine moiety with a pKa greater than about 11.0, while in still other embodiments the stabilizing agent will comprise a amine moiety with a pKa greater than about 11.5. In yet other embodiments the stabilizing agent will comprise a compound having an amine moiety with a pKa greater than about 12.0, while in still other embodiments the stabilizing agent will comprise an amine moiety with a pKa greater than about 12.5. Those of skill in the art will understand that relevant pKa's may readily be calculated or determined using standard techniques and used to determine the applicability of using a selected compound as a stabilizing agent.
  • the disclosed stabilizing agents are shown to be particularly effective at targeting conjugation to free site-specific cysteines when combined with certain reducing agents.
  • compatible reducing agents may include any compound that produces a reduced free site-specific cysteine for conjugation without significantly disrupting the native disulfide bonds of the engineered antibody.
  • the activated drug linker is largely limited to binding to the desired free site-specific cysteine site(s). Relatively mild reducing agents or reducing agents used at relatively low concentrations to provide mild conditions are particularly preferred.
  • the terms "mild reducing agent” or “mild reducing conditions” shall be held to mean any agent or state brought about by a reducing agent (optionally in the presence of stabilizing agents) that provides thiols at the free cysteine site(s) without substantially disrupting native disulfide bonds present in the engineered antibody. That is, mild reducing agents or conditions (preferably in combination with a stabilizing agent) are able to effectively reduce free cysteine(s) (provide a thiol) without significantly disrupting the protein's native disulfide bonds.
  • the desired reducing conditions may be provided by a number of sulfhydryl-based compounds that establish the appropriate environment for selective conjugation.
  • mild reducing agents may comprise compounds having one or more free thiols while in some embodiments mild reducing agents will comprise compounds having a single free thiol.
  • Non-limiting examples of reducing agents compatible with the selective reduction techniques of the instant invention comprise glutathione, n-acetyl cysteine, cysteine, 2-aminoethane-l -thiol and 2-hydroxy ethane- 1- thiol.
  • conjugation efficiency in site-specific antibodies may be determined by various art-accepted techniques.
  • the efficiency of the site-specific conjugation of a drug to an antibody may be determined by assessing the percentage of conjugation on the target conjugation site(s) (e.g. free cysteines on the c-terminus of each light chain) relative to all other conjugated sites.
  • the method herein provides for efficiently conjugating a drug to an antibody comprising free cysteines.
  • the conjugation efficiency is at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 70%, at least 75%, at least 80%, at least 85%), at least 90%, at least 95%, at least 98% or more as measured by the percentage of target conjugation relative to all other conjugation sites.
  • engineered antibodies capable of conjugation may contain free cysteine residues that comprise sulfhydryl groups that are blocked or capped as the antibody is produced or stored. Such caps include small molecules, proteins, peptides, ions and other materials that interact with the sulfhydryl group and prevent or inhibit conjugate formation.
  • the unconjugated engineered antibody may comprise free cysteines that bind other free cysteines on the same or different antibodies. As discussed herein such cross-reactivity may lead to various contaminants during the fabrication procedure.
  • the engineered antibodies may require uncapping prior to a conjugation reaction.
  • antibodies herein are uncapped and display a free sulfhydryl group capable of conjugation.
  • antibodies herein are subjected to an uncapping reaction that does not disturb or rearrange the naturally occurring disulfide bonds. It will be appreciated that in most cases the uncapping reactions will occur during the normal reduction reactions (reduction or selective reduction).
  • conjugation and purification methodology compatible with the present invention advantageously provides the ability to generate relatively homogeneous ADC preparations comprising a narrow DAR distribution.
  • the disclosed constructs e.g., site-specific constructs
  • selective conjugation provides for homogeneity of the ADC species within a sample in terms of the stoichiometric ratio between the drug and the engineered antibody and with respect to the toxin location.
  • drug to antibody ratio or “DAR” refers to the molar ratio of drug to antibody in an ADC preparation.
  • a conjugate preparation may be substantially homogeneous with respect to its DAR distribution, meaning that within the ADC preparation is a predominant species of site-specific ADC with a particular drug loading (e.g., a drug loading of 2 or 4) that is also preferably uniform with respect to the site of loading (i.e., on the free cysteines).
  • a particular drug loading e.g., a drug loading of 2 or 4
  • the desired homogeneity may be achieved through the use of site-specific constructs in combination with selective reduction.
  • compatible preparations may be purified using analytical or preparative chromatography techniques to provide the desired homogeneity.
  • the homogeneity of the ADC sample can be analyzed using various techniques known in the art including but not limited to mass spectrometry, HPLC (e.g. size exclusion HPLC, RP-HPLC, HIC-HPLC etc.) or capillary electrophoresis.
  • HPLC e.g. size exclusion HPLC, RP-HPLC, HIC-HPLC etc.
  • capillary electrophoresis e.g. size exclusion HPLC, RP-HPLC, HIC-HPLC etc.
  • standard pharmaceutical preparative methods may be employed to obtain the desired purity.
  • liquid chromatography methods such as reverse phase (RP) and hydrophobic interaction chromatography (HIC) may separate compounds in the mixture by drug loading value.
  • IEC ion-exchange
  • MMC mixed-mode chromatography
  • the disclosed ADCs and preparations thereof may comprise drug and antibody moieties in various stoichiometric molar ratios depending on the configuration of the antibody and, at least in part, on the method used to effect conjugation.
  • the drug loading per ADC may comprise from 1-20 warheads (i.e., n is 1-20).
  • Other selected embodiments may comprise ADCs with a drug loading of from 1 to 15 warheads.
  • the ADCs may comprise from 1-12 warheads or, more preferably, from 1-10 warheads.
  • the ADCs will comprise from 1 to 8 warheads.
  • drug loading may be relatively high, practical limitations such as free cysteine cross reactivity and warhead hydrophobicity tend to limit the generation of homogeneous preparations comprising such DAR due to aggregates and other contaminants. That is, higher drug loading, e.g. >8 or 10, may cause aggregation, insolubility, toxicity, or loss of cellular permeability of certain antibody-drug conjugates depending on the payload.
  • drug loading provided by the instant invention preferably ranges from 1 to 8 drugs per conjugate, i.e. where 1, 2, 3, 4, 5, 6, 7, or 8 drugs are covalently attached to each antibody (e.g., for IgGl, other antibodies may have different loading capacity depending the number of disulfide bonds).
  • the DAR of compositions of the instant invention will be approximately 2, 4 or 6 and in some embodiments the DAR will comprise approximately 2.
  • the disclosed compositions actually comprise a mixture of conjugates with a range of drug compounds (potentially from 1 to 8 in the case of an IgGl).
  • the disclosed ADC compositions include mixtures of conjugates where most of the constituent antibodies are covalently linked to one or more drug moieties and (despite the relative conjugate specificity provided by engineered constructs and selective reduction) where the drug moieties may be attached to the antibody by various thiol groups.
  • compositions of the invention will comprise a mixture of ADCs with different drug loads (e.g., from 1 to 8 drugs per IgGl antibody) at various concentrations (along with certain reaction contaminants primarily caused by free cysteine cross reactivity).
  • drug loads e.g., from 1 to 8 drugs per IgGl antibody
  • concentrations e.g., from 1 to 8 drugs per IgGl antibody
  • the conjugate compositions may be driven to the point where they largely contain a single predominant desired ADC species (e.g., with a drug loading of 2) with relatively low levels of other ADC species (e.g., with a drug loading of 1, 4, 6, etc.).
  • the average DAR value represents the weighted average of drug loading for the composition as a whole (i.e., all the ADC species taken together).
  • compositions comprising a measured average DAR within the range (i.e., 1.5 to 2.5) would be used in a pharmaceutical setting.
  • the present invention will comprise compositions having an average DAR of 1, 2, 3, 4, 5, 6, 7 or 8 each +/- 0.5. In other embodiments the present invention will comprise an average DAR of 2, 4, 6 or 8 +/- 0.5. Finally, in selected embodiments the present invention will comprise an average DAR of 2 +/- 0.5 or 4 +/- 0.5. It will be appreciated that the range or deviation may be less than 0.4 in some embodiments. Thus, in other embodiments the compositions will comprise an average DAR of 1, 2, 3, 4, 5, 6, 7 or 8 each +/- 0.3, an average DAR of 2, 4, 6 or 8 +/- 0.3, even more preferably an average DAR of 2 or 4 +/- 0.3 or even an average DAR of 2 +/- 0.3.
  • IgGl conjugate compositions will preferably comprise a composition with an average DAR of 1, 2, 3, 4, 5, 6, 7 or 8 each +/- 0.4 and relatively low levels (i.e., less than 30%) of non-predominant ADC species.
  • the ADC composition will comprise an average DAR of 2, 4, 6 or 8 each +/- 0.4 with relatively low levels ( ⁇ 30%>) of non- predominant ADC species.
  • the ADC composition will comprise an average DAR of 2 +/- 0.4 with relatively low levels ( ⁇ 30%>) of non-predominant ADC species.
  • the predominant ADC species (e.g., with a drug loading of 2 or drug loading of 4) will be present at a concentration of greater than 50%>, at a concentration of greater than 55%>, at a concentration of greater than 60 %>, at a concentration of greater than 65%>, at a concentration of greater than 70%>, at a concentration of greater than 75%>, at a concentration of greater that 80%>, at a concentration of greater than 85%>, at a concentration of greater than 90%>, at a concentration of greater than 93%>, at a concentration of greater than 95%> or even at a concentration of greater than 97%) when measured against all other DAR species present in the composition.
  • the distribution of drugs per antibody in preparations of ADC from conjugation reactions may be characterized by conventional means such as UV-Vis spectrophotometry, reverse phase HPLC, HIC, mass spectroscopy, ELISA, and electrophoresis.
  • the quantitative distribution of ADC in terms of drugs per antibody may also be determined.
  • ELISA the averaged value of the drugs per antibody in a particular preparation of ADC may be determined.
  • the distribution of drug per antibody values is not discernible by the antibody-antigen binding and detection limitation of ELISA.
  • ELISA assay for detection of antibody-drug conjugates does not determine where the drug moieties are attached to the antibody, such as the heavy chain or light chain fragments, or the particular amino acid residues.
  • the invention provides in vitro and in vivo methods for detecting, diagnosing or monitoring proliferative disorders and methods of screening cells from a patient to identify tumor cells including tumorigenic cells.
  • Such methods include identifying an individual having cancer for treatment or monitoring progression of a cancer, comprising contacting the patient or a sample obtained from a patient (either in vivo or in vitro) with a detection agent (e.g., an antibody or nucleic acid probe) capable of specifically recognizing and associating with a KREMEN2 determinant and detecting the presence or absence, or level of association of the detection agent in the sample.
  • a detection agent e.g., an antibody or nucleic acid probe
  • the detection agent will comprise an antibody associated with a detectable label or reporter molecule as described herein.
  • the KREMEN2 antibody will be administered and detected using a secondary labelled antibody (e.g., an anti -murine antibody).
  • a secondary labelled antibody e.g., an anti -murine antibody.
  • a nucleic acid probe that reacts with a genomic KREMEN2 determinant will be used in the detection, diagnosis or monitoring of the proliferative disorder.
  • KREMEN2 determinants may be measured using any of a number of techniques available to the person of ordinary skill in the art for protein or nucleic acid analysis, e.g., direct physical measurements (e.g., mass spectrometry), binding assays (e.g., immunoassays, agglutination assays, and immunochromatographic assays), Polymerase Chain Reaction (PCR, RT-PCR; RT-qPCR) technology, branched oligonucleotide technology, Northern blot technology, oligonucleotide hybridization technology and in situ hybridization technology.
  • direct physical measurements e.g., mass spectrometry
  • binding assays e.g., immunoassays, agglutination assays, and immunochromatographic assays
  • Polymerase Chain Reaction PCR, RT-PCR; RT-qPCR
  • branched oligonucleotide technology branched oligonucleotide technology
  • the method may also comprise measuring a signal that results from a chemical reaction, e.g., a change in optical absorbance, a change in fluorescence, the generation of chemiluminescence or electrochemiluminescence, a change in reflectivity, refractive index or light scattering, the accumulation or release of detectable labels from the surface, the oxidation or reduction or redox species, an electrical current or potential, changes in magnetic fields, etc.
  • a chemical reaction e.g., a change in optical absorbance, a change in fluorescence, the generation of chemiluminescence or electrochemiluminescence, a change in reflectivity, refractive index or light scattering, the accumulation or release of detectable labels from the surface, the oxidation or reduction or redox species, an electrical current or potential, changes in magnetic fields, etc.
  • Suitable detection techniques may detect binding events by measuring the participation of labeled binding reagents through the measurement of the labels via their photoluminescence (e.g., via measurement of fluorescence, time-resolved fluorescence, evanescent wave fluorescence, up-converting phosphors, multi-photon fluorescence, etc.), chemiluminescence, electrochemiluminescence, light scattering, optical absorbance, radioactivity, magnetic fields, enzymatic activity (e.g., by measuring enzyme activity through enzymatic reactions that cause changes in optical absorbance or fluorescence or cause the emission of chemiluminescence).
  • photoluminescence e.g., via measurement of fluorescence, time-resolved fluorescence, evanescent wave fluorescence, up-converting phosphors, multi-photon fluorescence, etc.
  • chemiluminescence e.g., via measurement of fluorescence, time-resolved fluorescence, evanescent wave fluorescence, up-
  • detection techniques may be used that do not require the use of labels, e.g., techniques based on measuring mass (e.g., surface acoustic wave measurements), refractive index (e.g., surface plasmon resonance measurements), or the inherent luminescence of an anal yte.
  • the association of the detection agent with particular cells or cellular components in the sample indicates that the sample may contain tumorigenic cells, thereby denoting that the individual having cancer may be effectively treated with an antibody or ADC as described herein.
  • the assays may comprise immunohistochemistry (IHC) assays or variants thereof (e.g., fluorescent, chromogenic, standard ABC, standard LSAB, etc.), immunocytochemistry or variants thereof (e.g., direct, indirect, fluorescent, chromogenic, etc.) or In situ hybridization (ISH) or variants thereof (e.g., chromogenic in situ hybridization (CISH) or fluorescence in situ hybridization (DNA-FISH or RNA-FISH]))
  • IHC immunohistochemistry
  • ISH In situ hybridization
  • CISH chromogenic in situ hybridization
  • DNA-FISH DNA-FISH or RNA-FISH]
  • KREMEN2 IHC immunohistochemistry
  • KREMEN2 IHC may be used as a diagnostic tool to aid in the diagnosis of various proliferative disorders and to monitor the potential response to treatments including KREMEN2 antibody therapy.
  • the KREMEN2 will be conjugated to one or more reporter molecules.
  • the KREMEN2 antibody will be unlabeled and will be detected with a separate agent (e.g., an anti-murine antibody) associated with one or more reporter molecules.
  • compatible diagnostic assays may be performed on tissues that have been chemically fixed (including but not limited to: formaldehyde, gluteraldehyde, osmium tetroxide, potassium dichromate, acetic acid, alcohols, zinc salts, mercuric chloride, chromium tetroxide and picric acid) and embedded (including but not limited to: glycol methacrylate, paraffin and resins) or preserved via freezing.
  • Such assays can be used to guide treatment decisions and determine dosing regimens and timing.
  • ISH in situ hybridization technology
  • cells are fixed and detectable probes which contain a specific nucleotide sequence are added to the fixed cells. If the cells contain complementary nucleotide sequences, the probes, which can be detected, will hybridize to them.
  • probes can be designed to identify cells that express genotypic KREMEN2 determinants. Probes preferably hybridize to a nucleotide sequence that corresponds to such determinants.
  • Hybridization conditions can be routinely optimized to minimize background signal by non-fully complementary hybridization though preferably the probes are preferably fully complementary to the selected KREMEN2 determinant.
  • the probes are labeled with fluorescent dye attached to the probes that is readily detectable by standard fluorescent methodology.
  • Compatible in vivo theragnostics or diagnostic assays may comprise art-recognized imaging or monitoring techniques such as magnetic resonance imaging, computerized tomography (e.g. CAT scan), positron tomography (e.g., PET scan) radiography, ultrasound, etc., as would be known by those skilled in the art.
  • art-recognized imaging or monitoring techniques such as magnetic resonance imaging, computerized tomography (e.g. CAT scan), positron tomography (e.g., PET scan) radiography, ultrasound, etc., as would be known by those skilled in the art.
  • the antibodies of the instant invention may be used to detect and quantify levels of a particular determinant (e.g., KREMEN2 protein) in a patient sample (e.g., plasma or blood) which may, in turn, be used to detect, diagnose or monitor proliferative disorders that are associated with the relevant determinant.
  • a patient sample e.g., plasma or blood
  • blood and bone marrow samples may be used in conjunction with flow cytometry to detect and measure KREMEN2 expression (or another co-expressed marker) and monitor the progression of the disease and/or response to treatment.
  • the antibodies of the instant invention may be used to detect, monitor and/or quantify circulating tumor cells either in vivo or in vitro (WO 2012/0128801).
  • the circulating tumor cells may comprise tumorigenic cells.
  • the tumorigenic cells in a subject or a sample from a subject may be assessed or characterized using the disclosed antibodies prior to therapy or regimen to establish a baseline.
  • the tumorigenic cells can be assessed from a sample that is derived from a subject that was treated.
  • the invention provides a method of analyzing cancer progression and/or pathogenesis in vivo.
  • analysis of cancer progression and/or pathogenesis in vivo comprises determining the extent of tumor progression.
  • analysis comprises the identification of the tumor.
  • analysis of tumor progression is performed on the primary tumor.
  • analysis is performed over time depending on the type of cancer as known to one skilled in the art.
  • further analysis of secondary tumors originating from metastasizing cells of the primary tumor is conducted in vivo.
  • the size and shape of secondary tumors are analyzed.
  • further ex vivo analysis is performed.
  • the invention provides a method of analyzing cancer progression and/or pathogenesis in vivo including determining cell metastasis or detecting and quantifying the level of circulating tumor cells.
  • analysis of cell metastasis comprises determination of progressive growth of cells at a site that is discontinuous from the primary tumor.
  • procedures may be undertaken to monitor tumor cells that disperse via blood vasculature, lymphatics, within body cavities or combinations thereof.
  • cell metastasis analysis is performed in view of cell migration, dissemination, extravasation, proliferation or combinations thereof.
  • the tumorigenic cells in a subject or a sample from a subject may be assessed or characterized using the disclosed antibodies prior to therapy to establish a baseline.
  • the sample is derived from a subject that was treated.
  • the sample is taken from the subject at least about 1, 2, 4, 6, 7, 8, 10, 12, 14, 15, 16, 18, 20, 30, 60, 90 days, 6 months, 9 months, 12 months, or >12 months after the subject begins or terminates treatment.
  • the tumorigenic cells are assessed or characterized after a certain number of doses (e.g., after 2, 5, 10, 20, 30 or more doses of a therapy).
  • the tumorigenic cells are characterized or assessed after 1 week, 2 weeks, 1 month, 2 months, 1 year, 2 years, 3 years, 4 years or more after receiving one or more therapies.
  • antibodies of the instant invention can be used to screen samples in order to identify compounds or agents (e.g., antibodies or ADCs) that alter a function or activity of tumor cells by interacting with a determinant.
  • tumor cells are put in contact with an antibody or ADC and the antibody or ADC can be used to screen the tumor for cells expressing a certain target (e.g. KREMEN2) in order to identify such cells for purposes, including but not limited to, diagnostic purposes, to monitor such cells to determine treatment efficacy or to enrich a cell population for such target-expressing cells.
  • a certain target e.g. KREMEN2
  • a method includes contacting, directly or indirectly, tumor cells with a test agent or compound and determining if the test agent or compound modulates an activity or function of the determinant-associated tumor cells for example, changes in cell morphology or viability, expression of a marker, differentiation or de-differentiation, cell respiration, mitochondrial activity, membrane integrity, maturation, proliferation, viability, apoptosis or cell death.
  • a direct interaction is physical interaction
  • an indirect interaction includes, for example, the action of a composition upon an intermediary molecule that, in turn, acts upon the referenced entity (e.g., cell or cell culture).
  • Screening methods include high throughput screening, which can include arrays of cells (e.g., microarrays) positioned or placed, optionally at pre-determined locations, for example, on a culture dish, tube, flask, roller bottle or plate.
  • High-throughput robotic or manual handling methods can probe chemical interactions and determine levels of expression of many genes in a short period of time. Techniques have been developed that utilize molecular signals, for example via fluorophores or microarrays (Mocellin and Rossi, 2007, PMID: 17265713) and automated analyses that process information at a very rapid rate (see, e.g., Pinhasov et al , 2004, PMID: 15032660).
  • Libraries that can be screened include, for example, small molecule libraries, phage display libraries, fully human antibody yeast display libraries (Adimab), siRNA libraries, and adenoviral transfection vectors.
  • the antibodies or ADCs of the invention can be formulated in various ways using art recognized techniques.
  • the therapeutic compositions of the invention can be administered neat or with a minimum of additional components while others may optionally be formulated to contain suitable pharmaceutically acceptable carriers.
  • pharmaceutically acceptable carriers comprise excipients, vehicles, adjuvants and diluents that are well known in the art and can be available from commercial sources for use in pharmaceutical preparation (see, e.g., Gennaro (2003) Remington: The Science and Practice of Pharmacy with Facts and Comparisons: Drugfacts Plus, 20th ed., Mack Publishing; Ansel et al.
  • Suitable pharmaceutically acceptable carriers comprise substances that are relatively inert and can facilitate administration of the antibody or ADC or can aid processing of the active compounds into preparations that are pharmaceutically optimized for delivery to the site of action.
  • Such pharmaceutically acceptable carriers include agents that can alter the form, consistency, viscosity, pH, tonicity, stability, osmolality, pharmacokinetics, protein aggregation or solubility of the formulation and include buffering agents, wetting agents, emulsifying agents, diluents, encapsulating agents and skin penetration enhancers.
  • Certain non-limiting examples of carriers include saline, buffered saline, dextrose, arginine, sucrose, water, glycerol, ethanol, sorbitol, dextran, sodium carboxymethyl cellulose and combinations thereof.
  • Antibodies for systemic administration may be formulated for enteral, parenteral or topical administration. Indeed, all three types of formulation may be used simultaneously to achieve systemic administration of the active ingredient. Excipients as well as formulations for parenteral and nonparenteral drug delivery are set forth in Remington: The Science and Practice of Pharmacy (2000) 20th Ed. Mack Publishing.
  • Suitable formulations for enteral administration include hard or soft gelatin capsules, pills, tablets, including coated tablets, elixirs, suspensions, syrups or inhalations and controlled release forms thereof.
  • Formulations suitable for parenteral administration include aqueous or non-aqueous, isotonic, pyrogen-free, sterile liquids (e.g., solutions, suspensions), in which the active ingredient is dissolved, suspended, or otherwise provided (e.g., in a liposome or other microparticulate).
  • Such liquids may additionally contain other pharmaceutically acceptable carriers, such as anti -oxidants, buffers, preservatives, stabilizers, bacterio stats, suspending agents, thickening agents, and solutes that render the formulation isotonic with the blood (or other relevant bodily fluid) of the intended recipient.
  • excipients include, for example, water, alcohols, polyols, glycerol, vegetable oils, and the like.
  • suitable isotonic pharmaceutically acceptable carriers for use in such formulations include Sodium Chloride Injection, Ringer's Solution, or Lactated Ringer's Injection.
  • compositions of the present invention may be lyophilized to provide a powdered form of the antibody or ADC that may then be reconstituted prior to administration.
  • Sterile powders for the preparation of injectable solutions may be generated by fyophilizing a solution comprising the disclosed antibodies or ADCs to yield a powder comprising the active ingredient along with any optional co-solubilized biocompatible ingredients.
  • dispersions or solutions are prepared by incorporating the active compound into a sterile vehicle that contains a basic dispersion medium or solvent (e.g., a diluent) and, optionally, other biocompatible ingredients.
  • a compatible diluent is one which is pharmaceutically acceptable (safe and non-toxic for administration to a human) and is useful for the preparation of a liquid formulation, such as a formulation reconstituted after iyophiiization.
  • exemplary diluents include sterile water, bacteriostatic water for injection (BWFI), a pH buffered solution (e.g. phosphate- buffered saline), sterile saline solution, Ringer's solution or dextrose solution.
  • BWFI bacteriostatic water for injection
  • a pH buffered solution e.g. phosphate- buffered saline
  • sterile saline solution e.g. phosphate- buffered saline
  • Ringer's solution or dextrose solution e.g. sterile saline solution
  • diluents can include aqueous solutions of salts and/or buffers.
  • the anti-KREMEN2 antibodies or ADCs will be lyophilized in combination with a pharmaceutically acceptable sugar.
  • a "pharmaceutically acceptable sugar” is a molecule which, when combined with a protein of interest, significantly prevents or reduces chemical and/or physical instability of the protein upon storage. When the formulation is intended to be lyophilized and then reconstituted.
  • pharmaceutically acceptable sugars may also be referred to as a "lyoproiectani".
  • Exemplary sugars and their corresponding sugar alcohols include; an amino acid such as monosodium glutamate or histidine; a methylamine such as betaine; a lyotropic salt such as magnesium sulfate; a polyol such as trihydric or higher molecular weight sugar alcohols, e.g. glycerin, dextran, erythritol, glycerol, arabitol, xylitoi, sorbitol, and mannitol; propylene glycol; polyethylene glycol; PLURONICS*'; and combinations thereof.
  • an amino acid such as monosodium glutamate or histidine
  • a methylamine such as betaine
  • a lyotropic salt such as magnesium sulfate
  • a polyol such as trihydric or higher molecular weight sugar alcohols, e.g. glycerin, dextran, erythritol, glycerol, arabitol,
  • Additional exemplary lyoprotectants include glycerin and gelatin, and the sugars mellibiose, melezitose, raffinose, mannotriose and stachyose.
  • reducing sugars include glucose, maltose, lactose, maltulose, iso-maltulose and lactulose.
  • non- reducing sugars include non-reducing glycosides of polyhydroxy compounds selected from sugar alcohols and other straight chain polyalcohols.
  • Preferred sugar alcohols are monoglycosides, especially those compounds obtained by reduction of disaccharides such as lactose, maltose, lactulose and maltutose.
  • the glycosidic side group can be either glucosidic or galactosidic.
  • Additional examples of sugar alcohols are glucitol, maititoi, lactitol and iso-niaitulose.
  • the preferred pharniaceutically-acceptable sugars are the non-reducing sugars trehalose or sucrose.
  • Pharmaceutically acceptable sugars are added to the formulation in a "protecting amount" (e.g. pre- iyophilization) which means that the protein essentially retains its physical and chemical stability and integrity during storage (e.g., after reconstitution and storage).
  • the liquid KREMEN2 ADC formulations may be further diluted (preferably in an aqueous carrier) prior to administration.
  • the aforementioned liquid formulations may further be diluted into an infusion bag containing 0.9% Sodium Chloride Injection, USP, or equivalent ⁇ mutatis mutandis), to achieve the desired dose level for administration.
  • the fully diluted KREMEN2 ADC solution will be administered via intravenous infusion using an IV apparatus.
  • the administered KREMEN2 ADC drug solution is clear, colorless and free from visible particulates.
  • the compounds and compositions of the invention may be administered in vivo, to a subject in need thereof, by various routes, including, but not limited to, oral, intravenous, intra-arterial, subcutaneous, parenteral, intranasal, intramuscular, intracardiac, intraventricular, intratracheal, buccal, rectal, intraperitoneal, intradermal, topical, transdermal, and intrathecal, or otherwise by implantation or inhalation.
  • compositions may be formulated into preparations in solid, semi-solid, liquid, or gaseous forms; including, but not limited to, tablets, capsules, powders, granules, ointments, solutions, suppositories, enemas, injections, inhalants, and aerosols.
  • the appropriate formulation and route of administration may be selected according to the intended application and therapeutic regimen.
  • the particular dosage regimen i.e., dose, timing and repetition, will depend on the particular individual, as well as empirical considerations such as pharmacokinetics (e.g., half-life, clearance rate, etc.). Determination of the frequency of administration may be made by persons skilled in the art, such as an attending physician based on considerations of the condition and severity of the condition being treated, age and general state of health of the subject being treated and the like. Frequency of administration may be adjusted over the course of therapy based on assessment of the efficacy of the selected composition and the dosing regimen. Such assessment can be made on the basis of markers of the specific disease, disorder or condition.
  • these include direct measurements of tumor size via palpation or visual observation; indirect measurement of tumor size by x-ray or other imaging techniques; an improvement as assessed by direct tumor biopsy and microscopic examination of a tumor sample; the measurement of an indirect tumor marker (e.g., PSA for prostate cancer) or an antigen identified according to the methods described herein; reduction in the number of proliferative or tumorigenic cells, maintenance of the reduction of such neoplastic cells; reduction of the proliferation of neoplastic cells; or delay in the development of metastasis.
  • an indirect tumor marker e.g., PSA for prostate cancer
  • the KREMEN2 antibodies or ADCs of the invention may be administered in various ranges. These include about 5 ⁇ g/kg body weight to about 100 mg/kg body weight per dose; about 50 ⁇ g/kg body weight to about 5 mg/kg body weight per dose; about 100 ⁇ g/kg body weight to about 10 mg/kg body weight per dose. Other ranges include about 100 ⁇ g/kg body weight to about 20 mg/kg body weight per dose and about 0.5 mg/kg body weight to about 20 mg/kg body weight per dose.
  • the dosage is at least about 100 ⁇ g/kg body weight, at least about 250 ⁇ g/kg body weight, at least about 750 ⁇ g/kg body weight, at least about 3 mg/kg body weight, at least about 5 mg/kg body weight, at least about 10 mg/kg body weight.
  • the KREMEN2 antibodies or ADCs will be administered (preferably intravenously) at approximately 10, 20, 30, 40, 50, 60, 70, 80, 90 or 100 ⁇ g/kg body weight per dose.
  • Other embodiments may comprise the administration of antibodies or ADCs at about 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900 or 2000 ⁇ g/kg body weight per dose.
  • the disclosed conjugates will be administered at 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 9 or 10 mg/kg.
  • the conjugates may be administered at 12, 14, 16, 18 or 20 mg/kg body weight per dose.
  • the conjugates may be administered at 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 90 or 100 mg/kg body weight per dose.
  • BSA Body Surface Area
  • 800 mg/m 2 from 50 mg/m 2 to 500 mg/m 2 and at dosages of 100 mg/m 2 , 150 mg/m 2 , 200 mg/m 2 , 250 mg/m 2 , 300 mg/m 2 , 350 mg/m 2 , 400 mg/m 2 or 450 mg/m 2. It will also be appreciated that art recognized and empirical techniques may be used to determine appropriate dosage.
  • Anti-KREMEN2 antibodies or ADCs may be administered on a specific schedule. Generally, an effective dose of the KREMEN2 conjugate is administered to a subject one or more times. More particularly, an effective dose of the ADC is administered to the subject once a month, more than once a month, or less than once a month. In certain embodiments, the effective dose of the KREMEN2 antibody or ADC may be administered multiple times, including for periods of at least a month, at least six months, at least a year, at least two years or a period of several years.
  • the course of treatment involving conjugated antibodies will comprise multiple doses of the selected drug product over a period of weeks or months. More specifically, antibodies or ADCs of the instant invention may administered once every day, every two days, every four days, every week, every ten days, every two weeks, every three weeks, every month, every six weeks, every two months, every ten weeks or every three months. In this regard it will be appreciated that the dosages may be altered or the interval may be adjusted based on patient response and clinical practices. The invention also contemplates discontinuous administration or daily doses divided into several partial administrations.
  • compositions of the instant invention and anti-cancer agent may be administered interchangeably, on alternate days or weeks; or a sequence of antibody treatments may be given, followed by one or more treatments of anti-cancer agent therapy.
  • chemotherapeutic agents will be generally around those already employed in clinical therapies wherein the chemotherapeutics are administered alone or in combination with other chemotherapeutics.
  • the KREMEN2 antibodies or ADCs of the instant invention may be used in maintenance therapy to reduce or eliminate the chance of tumor recurrence following the initial presentation of the disease.
  • the disorder will have been treated and the initial tumor mass eliminated, reduced or otherwise ameliorated so the patient is asymptomatic or in remission.
  • the subject may be administered pharmaceutically effective amounts of the disclosed antibodies one or more times even though there is little or no indication of disease using standard diagnostic procedures.
  • the modulators of the present invention may be used to prophylactically or as an adjuvant therapy to prevent or reduce the possibility of tumor metastasis following a debulking procedure.
  • a "debulking procedure” means any procedure, technique or method that reduces the tumor mass or ameliorates the tumor burden or tumor proliferation.
  • Exemplary debulking procedures include, but are not limited to, surgery, radiation treatments (i.e., beam radiation), chemotherapy, immunotherapy or ablation.
  • the disclosed ADCs may be administered as suggested by clinical, diagnostic or theragnostic procedures to reduce tumor metastasis.
  • the antibodies or ADCs of the instant invention may be used in a truly preventative sense and given to patients that have been examined or tested and have one or more noted risk factors (e.g., genomic indications, family history, in vivo or in vitro test results, etc.) but have not developed neoplasia.
  • risk factors e.g., genomic indications, family history, in vivo or in vitro test results, etc.
  • Dosages and regimens may also be determined empirically for the disclosed therapeutic compositions in individuals who have been given one or more administration(s). For example, individuals may be given incremental dosages of a therapeutic composition produced as described herein. In selected embodiments the dosage may be gradually increased or reduced or attenuated based respectively on empirically determined or observed side effects or toxicity. To assess efficacy of the selected composition, a marker of the specific disease, disorder or condition can be followed as described previously.
  • these include direct measurements of tumor size via palpation or visual observation, indirect measurement of tumor size by x-ray or other imaging techniques; an improvement as assessed by direct tumor biopsy and microscopic examination of the tumor sample; the measurement of an indirect tumor marker (e.g., PSA for prostate cancer) or a tumorigenic antigen identified according to the methods described herein, a decrease in pain or paralysis; improved speech, vision, breathing or other disability associated with the tumor; increased appetite; or an increase in quality of life as measured by accepted tests or prolongation of survival.
  • an indirect tumor marker e.g., PSA for prostate cancer
  • combination therapies may be particularly useful in decreasing or inhibiting unwanted neoplastic cell proliferation, decreasing the occurrence of cancer, decreasing or preventing the recurrence of cancer, or decreasing or preventing the spread or metastasis of cancer.
  • the antibodies or ADCs of the instant invention may function as sensitizing or chemosensitizing agents by removing CSCs that would otherwise prop up and perpetuate the tumor mass and thereby allow for more effective use of current standard of care debulking or anti -cancer agents. That is, the disclosed antibodies or ADCs may, in certain embodiments, provide an enhanced effect (e.g., additive or synergistic in nature) that potentiates the mode of action of another administered therapeutic agent.
  • combination therapy shall be interpreted broadly and merely refers to the administration of an anti-KREMEN2 antibody or ADC and one or more anti-cancer agents that include, but are not limited to, cytotoxic agents, cytostatic agents, anti-angiogenic agents, debulking agents, chemotherapeutic agents, radiotherapy and radiotherapeutic agents, targeted anti-cancer agents (including both monoclonal antibodies and small molecule entities), BRMs, therapeutic antibodies, cancer vaccines, cytokines, hormone therapies, radiation therapy and anti-metastatic agents and immunotherapeutic agents, including both specific and non-specific approaches.
  • cytotoxic agents include, but are not limited to, cytotoxic agents, cytostatic agents, anti-angiogenic agents, debulking agents, chemotherapeutic agents, radiotherapy and radiotherapeutic agents, targeted anti-cancer agents (including both monoclonal antibodies and small molecule entities), BRMs, therapeutic antibodies, cancer vaccines, cytokines, hormone therapies, radiation therapy and anti-metastatic agents and immunotherapeutic agents, including both specific and
  • the combined results are additive of the effects observed when each treatment (e.g., antibody and anti-cancer agent) is conducted separately. Although at least additive effects are generally desirable, any increased anti-tumor effect above one of the single therapies is beneficial. Furthermore, the invention does not require the combined treatment to exhibit synergistic effects. However, those skilled in the art will appreciate that with certain selected combinations that comprise preferred embodiments, synergism may be observed.
  • the combination therapy has therapeutic synergy or improves the measurable therapeutic effects in the treatment of cancer over (i) the anti-KREMEN2 antibody or ADC used alone, or (ii) the therapeutic moiety used alone, or (iii) the use of the therapeutic moiety in combination with another therapeutic moiety without the addition of an anti-KREMEN2 antibody or ADC.
  • therapeutic synergy means the combination of an anti- KREMEN2 antibody or ADC and one or more therapeutic moiety(ies) having a therapeutic effect greater than the additive effect of the combination of the anti-KREMEN2 antibody or ADC and the one or more therapeutic moiety(ies).
  • Desired outcomes of the disclosed combinations are quantified by comparison to a control or baseline measurement.
  • relative terms such as “improve,” “increase,” or “reduce” indicate values relative to a control, such as a measurement in the same individual prior to initiation of treatment described herein, or a measurement in a control individual (or multiple control individuals) in the absence of the anti-KREMEN2 antibodies or ADCs described herein but in the presence of other therapeutic moiety(ies) such as standard of care treatment.
  • a representative control individual is an individual afflicted with the same form of cancer as the individual being treated, who is about the same age as the individual being treated (to ensure that the stages of the disease in the treated individual and the control individual are comparable).
  • a synergistic therapeutic effect may be an effect of at least about two-fold greater than the therapeutic effect elicited by a single therapeutic moiety or anti-KREMEN2 antibody or ADC, or the sum of the therapeutic effects elicited by the anti-KREMEN2 antibody or ADC or the single therapeutic moiety(ies) of a given combination, or at least about five-fold greater, or at least about ten-fold greater, or at least about twenty-fold greater, or at least about fifty-fold greater, or at least about one hundred-fold greater.
  • a synergistic therapeutic effect may also be observed as an increase in therapeutic effect of at least 10% compared to the therapeutic effect elicited by a single therapeutic moiety or anti-KREMEN2 antibody or ADC, or the sum of the therapeutic effects elicited by the anti-KREMEN2 antibody or ADC or the single therapeutic moiety(ies) of a given combination, or at least 20%, or at least 30%, or at least 40%, or at least 50%, or at least 60%, or at least 70%, or at least 80%, or at least 90%, or at least 100%, or more.
  • a synergistic effect is also an effect that permits reduced dosing of therapeutic agents when they are used in combination.
  • the anti-KREMEN2 antibody or ADC and therapeutic moiety(ies) may be administered to the subject simultaneously, either in a single composition, or as two or more distinct compositions using the same or different administration routes.
  • treatment with the anti-KREMEN2 antibody or ADC may precede or follow the therapeutic moiety treatment by, e.g., intervals ranging from minutes to weeks.
  • both the therapeutic moiety and the antibody or ADC are administered within about 5 minutes to about two weeks of each other.
  • several days (2, 3, 4, 5, 6 or 7), several weeks (1, 2, 3, 4, 5, 6, 7 or 8) or several months (1, 2, 3, 4, 5, 6, 7 or 8) may lapse between administration of the antibody and the therapeutic moiety.
  • the combination therapy can be administered until the condition is treated, palliated or cured on various schedules such as once, twice or three times daily, once every two days, once every three days, once weekly, once every two weeks, once every month, once every two months, once every three months, once every six months, or may be administered continuously.
  • the antibody and therapeutic moiety(ies) may be administered on alternate days or weeks; or a sequence of anti- KREMEN2 antibody or ADC treatments may be given, followed by one or more treatments with the additional therapeutic moiety.
  • an anti-KREMEN2 antibody or ADC is administered in combination with one or more therapeutic moiety(ies) for short treatment cycles.
  • the combination treatment is administered for long treatment cycles.
  • the combination therapy can be administered via any route.
  • the compounds and compositions of the present invention may be used in conjunction with checkpoint inhibitors such as PD-1 inhibitors or PD-Ll inhibitors.
  • PD-1 together with its ligand PD-Ll, are negative regulators of the antitumor T lymphocyte response.
  • the combination therapy may comprise the administration of anti-KREMEN2 antibodies or ADCs together with an anti-PD-1 antibody (e.g. pembrolizumab, nivolumab, pidilizumab) and optionally one or more other therapeutic moiety(ies).
  • the combination therapy may comprise the administration of anti- KREMEN2 antibodies or ADCs together with an anti -PD-Ll antibody (e.g.
  • the combination therapy may comprise the administration of anti-KREMEN2 antibodies or ADCs together with an anti PD-1 antibody or anti-PD-Ll administered to patients who continue progress following treatments with checkpoint inhibitors and/or targeted BRAF combination therapies (e.g. vemurafenib or dabrafinib).
  • anti-KREMEN2 antibodies or ADCs together with an anti PD-1 antibody or anti-PD-Ll administered to patients who continue progress following treatments with checkpoint inhibitors and/or targeted BRAF combination therapies (e.g. vemurafenib or dabrafinib).
  • the anti-KREMEN2 antibodies or ADCs may be used in combination with various first line cancer treatments.
  • the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and a cytotoxic agent such as ifosfamide, mitomycin C, vindesine, vinblastine, etoposide, ironitecan, gemcitabine, taxanes, vinorelbine, methotrexate, and pemetrexed) and optionally one or more other therapeutic moiety(ies).
  • a cytotoxic agent such as ifosfamide, mitomycin C, vindesine, vinblastine, etoposide, ironitecan, gemcitabine, taxanes, vinorelbine, methotrexate, and pemetrexed
  • the disclosed ADCs may be used in combination with cytotoxic agents such as cytarabine (AraC) plus an anthracycyline (aclarubicin, amsacrine, doxorubicin, daunorubicin, idarubixcin, etc.) or mitoxantrone, fludarabine; hydroxyurea, clofarabine, cloretazine.
  • cytotoxic agents such as cytarabine (AraC) plus an anthracycyline (aclarubicin, amsacrine, doxorubicin, daunorubicin, idarubixcin, etc.) or mitoxantrone, fludarabine; hydroxyurea, clofarabine, cloretazine.
  • the ADCs of the invention may be administered in combination with G-CSF or GM-CSF priming, demethylating agents such as azacitidine or decitabine, FLT3 -selective tyrosine kinase inhibitors (eg, midostaurin, lestaurtinib and sunitinib), all-trans retinoic acid (ATRA) and arsenic trioxide (where the last two combinations may be particularly effective for acute promyelocytic leukemia (API.,)).
  • demethylating agents such as azacitidine or decitabine, FLT3 -selective tyrosine kinase inhibitors (eg, midostaurin, lestaurtinib and sunitinib), all-trans retinoic acid (ATRA) and arsenic trioxide (where the last two combinations may be particularly effective for acute promyelocytic leukemia (API.,)).
  • the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and a platinum-based drug (e.g. carboplatin or cisplatin) and optionally one or more other therapeutic moiety(ies) (e.g. vinorelbine; gemcitabine; a taxane such as, for example, docetaxel or paclitaxel; irinotecan; or pemetrexed).
  • a platinum-based drug e.g. carboplatin or cisplatin
  • other therapeutic moiety(ies) e.g. vinorelbine; gemcitabine; a taxane such as, for example, docetaxel or paclitaxel; irinotecan; or pemetrexed.
  • the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and one or more therapeutic moieties described as "hormone therapy”.
  • hormone therapy refers to, e.g., tamoxifen; gonadotropin or luteinizing releasing hormone (GnRH or LHRH); everolimus and exemestane; toremifene; or aromatase inhibitors (e.g. anastrozole, letrozole, exemestane or fulvestrant).
  • the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and trastuzumab or ado-trastuzumab emtansine (Kadcyla) and optionally one or more other therapeutic moiety(ies) (e.g. pertuzumab and/or docetaxel).
  • an anti-KREMEN2 antibody or ADC and trastuzumab or ado-trastuzumab emtansine (Kadcyla) and optionally one or more other therapeutic moiety(ies) (e.g. pertuzumab and/or docetaxel).
  • the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and a taxane (e.g. docetaxel or paclitaxel) and optionally an additional therapeutic moiety(ies), for example, an anthracycline (e.g. doxorubicin or epirubicin) and/or eribulin.
  • a taxane e.g. docetaxel or paclitaxel
  • an additional therapeutic moiety(ies) for example, an anthracycline (e.g. doxorubicin or epirubicin) and/or eribulin.
  • the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and megestrol and optionally an additional therapeutic moiety(ies).
  • the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and a poly ADP ribose polymerase (PARP) inhibitor (e.g. BMN-673, olaparib, rucaparib and veliparib) and optionally an additional therapeutic moiety(ies).
  • PARP poly ADP ribose polymerase
  • the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and a PARP inhibitor and optionally one or more other therapeutic moiety(ies).
  • the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and cyclophosphamide and optionally an additional therapeutic moiety(ies) (e.g. doxorubicin, a taxane, epirubicin, 5-FU and/or methotrexate.
  • an additional therapeutic moiety(ies) e.g. doxorubicin, a taxane, epirubicin, 5-FU and/or methotrexate.
  • combination therapy for the treatment of EGFR-positive NSCLC comprises the use of an anti-KREMEN2 antibody or ADC and afatinib and optionally one or more other therapeutic moiety(ies) (e.g. erlotinib and/or bevacizumab).
  • combination therapy for the treatment of EGFR-positive NSCLC comprises the use of an anti-KREMEN2 antibody or ADC and erlotinib and optionally one or more other therapeutic moiety(ies) (e.g. bevacizumab).
  • combination therapy for the treatment of ALK-positive NSCLC comprises the use of an anti-KREMEN2 antibody or ADC and ceritinib (Zykadia) and optionally one or more other therapeutic moiety(ies).
  • combination therapy for the treatment of ALK-positive NSCLC comprises the use of an anti-KREMEN2 antibody or ADC and crizotinib (Xalcori) and optionally one or more other therapeutic moiety(ies).
  • the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and bevacizumab and optionally one or more other therapeutic moiety(ies) (e.g. gemcitabine or a taxane such as, for example, docetaxel or paclitaxel; and/or a platinum analog).
  • an anti-KREMEN2 antibody or ADC and bevacizumab and optionally one or more other therapeutic moiety(ies) (e.g. gemcitabine or a taxane such as, for example, docetaxel or paclitaxel; and/or a platinum analog).
  • other therapeutic moiety(ies) e.g. gemcitabine or a taxane such as, for example, docetaxel or paclitaxel; and/or a platinum analog.
  • the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and bevacizumab and optionally cyclophosphamide.
  • the combination therapy for the treatment of platinum -resistant tumors comprises the use of an anti-KREMEN2 antibody or ADC and doxorubicin and/or etoposide and/or gemcitabine and/or vinorelbine and/or ifosfamide and/or leucovorin-modulated 5-fluoroucil and/or bevacizumab and/or tamoxifen; and optionally one or more other therapeutic moiety(ies).
  • the disclosed antibodies and ADCs may be used in combination with certain steroids to potentially make the course of treatment more effective and reduce side effects such as inflammation, nausea and hypersensitivity.
  • the steroid will comprise dexamethasone
  • the anti-KREMEN2 antibodies or ADCs may be used in combination with various first line melanoma treatments.
  • the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and dacarbazine and optionally one or more other therapeutic moiety(ies).
  • the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and temozolamide and optionally one or more other therapeutic moiety(ies).
  • the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and a platinum-based therapeutic moiety (e.g. carboplatin or cisplatin) and optionally one or more other therapeutic moiety(ies).
  • the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and a vinca alkaloid therapeutic moiety (e.g. vinblastine, vinorelbine, vincristine, or vindesine) and optionally one or more other therapeutic moiety(ies).
  • a vinca alkaloid therapeutic moiety e.g. vinblastine, vinorelbine, vincristine, or vindesine
  • the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and interleukin-2 and optionally one or more other therapeutic moiety(ies).
  • the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and interferon-alpha and optionally one or more other therapeutic moiety(ies).
  • the anti-KREMEN2 antibodies or ADCs may be used in combination with adjuvant melanoma treatments and/or a surgical procedure (e.g. tumor resection.)
  • the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and interferon-alpha and optionally one or more other therapeutic moiety(ies).
  • the invention also provides for the combination of anti-KREMEN2 antibodies or ADCs with radiotherapy.
  • radiotherapy means, any mechanism for inducing DNA damage locally within tumor cells such as gamma-irradiation, X-rays, UV-irradiation, microwaves, electronic emissions and the like.
  • Combination therapy using the directed delivery of radioisotopes to tumor cells is also contemplated, and may be used in combination or as a conjugate of the anti- KREMEN2 antibodies disclosed herein.
  • radiation therapy is administered in pulses over a period of time from about 1 to about 2 weeks.
  • the radiation therapy may be administered as a single dose or as multiple, sequential doses.
  • an anti-KREMEN2 antibody or ADC may be used in combination with one or more of the chemotherapeutic agents described below.
  • anti-cancer agent as used herein is one subset of “therapeutic moieties”, which in turn is a subset of the agents described as “pharmaceutically active moieties”. More particularly "anti-cancer agent” means any agent (or a pharmaceutically acceptable salt thereof) that can be used to treat a cell proliferative disorder such as cancer, and includes, but is not limited to, cytotoxic agents, cytostatic agents, anti-angiogenic agents, debulking agents, chemotherapeutic agents, radiotherapeutic agents, targeted anti-cancer agents, biological response modifiers, therapeutic antibodies, cancer vaccines, cytokines, hormone therapy, anti-metastatic agents and immunotherapeutic agents.
  • anti-cancer agents are not exclusive of each other and that selected agents may fall into one or more categories.
  • a compatible anti-cancer agent may be classified as a cytotoxic agent and a chemotherapeutic agent. Accordingly, each of the foregoing terms should be construed in view of the instant disclosure and then in accordance with their use in the medical arts.
  • an anti-cancer agent can include any chemical agent (e.g., a chemotherapeutic agent) that inhibits or eliminates, or is designed to inhibit or eliminate, a cancerous cell or a cell likely to become cancerous or generate tumorigenic progeny (e.g., tumorigenic cells).
  • a chemical agent e.g., a chemotherapeutic agent
  • selected chemical agents are often directed to intracellular processes necessary for cell growth or division, and are thus particularly effective against cancerous cells, which generally grow and divide rapidly. For example, vincristine depolymerizes microtubules and thus inhibits rapidly dividing tumor cells from entering mitosis.
  • the selected chemical agents are cell-cycle independent agents that interfere with cell survival at any point of its lifecycle and may be effective in directed therapeutics (e.g., ADCs).
  • ADCs directed therapeutics
  • certain pyrrolobenzodiazepines bind to the minor groove of cellular DNA and inhibit transcription upon delivery to the nucleus.
  • combination therapy or selection of an ADC component it will be appreciated that one skilled in the art could readily identify compatible cell-cycle dependent agents and cell-cycle independent agents in view of the instant disclosure.
  • the selected anti -cancer agents may be administered in combination with each other (e.g., CHOP therapy) in addition to the disclosed anti-KREMEN2 antibodies and ADCs disclosed herein.
  • such anti-cancer agents may comprise conjugates and may be associated with antibodies prior to administration.
  • the disclosed anticancer agent will be linked to an anti-KREMEN2 antibody to provide an ADC as disclosed herein.
  • cytotoxic agent generally means a substance that is toxic to cells in that it decreases or inhibits cellular function and/or causes the destruction of tumor cells.
  • the substance is a naturally occurring molecule derived from a living organism or an analog thereof (purified from natural sources or synthetically prepared).
  • cytotoxic agents include, but are not limited to, small molecule toxins or enzymatically active toxins of bacteria (e.g., calicheamicin, Diptheria toxin, Pseudomonas endotoxin and exotoxin, Staphylococcal enterotoxin A), fungal (e.g., a-sarcin, restrictocin), plants (e.g., abrin, ricin, modeccin, viscumin, pokeweed anti-viral protein, saporin, gelonin, momoridin, trichosanthin, barley toxin, Aleurites fordii proteins, dianthin proteins, Phytolacca mericana proteins [PAPI, PAPII, and PAP-S], Momordica charantia inhibitor, curcin, crotin, saponaria officinalis inhibitor, mitegellin, restrictocin, phenomycin, neomycin, and the tricothecenes) or
  • cytotoxic agents or anti-cancer agents that may be used in combination with (or conjugated to) the antibodies of the invention include, but are not limited to, alkylating agents, alkyl sulfonates, anastrozole, amanitins, aziridines, ethylenimines and methylamelamines, acetogenins, a camptothecin, BEZ-235, bortezomib, bryostatin, callystatin, CC- 1065, ceritinib, crizotinib, cryptophycins, dolastatin, duocarmycin, eleutherobin, erlotinib, pancratistatin, a sarcodictyin, spongistatin, nitrogen mustards, antibiotics, enediyne dynemicin, bisphosphonates, esperamicin, chromoprotein enediyne antiobiotic chromophores, aclacino
  • anti-hormonal agents that act to regulate or inhibit hormone action on tumors
  • anti-estrogens and selective estrogen receptor antibodies aromatase inhibitors that inhibit the enzyme aromatase, which regulates estrogen production in the adrenal glands, and anti- androgens
  • troxacitabine a 1,3- dioxolane nucleoside cytosine analog
  • antisense oligonucleotides, ribozymes such as a VEGF expression inhibitor and a HER2 expression inhibitor
  • vaccines PROLEUKIN ® rIL-2; LURTOTECAN ® topoisomerase 1 inhibitor; ABARELLX ® rmRH; Vinorelbine and Esperamicins and pharmaceutically acceptable salts or solvates, acids or derivatives of any of the above.
  • Compatible cytotoxic agents or anti-cancer agents may also comprise commercially or clinically available compounds such as erlotinib (TARCEVA , Genentech/OSI Pharm.), docetaxel (TAXOTERE ® , Sanofi-Aventis), 5-FU (fluorouracil, 5-fluorouracil, CAS No. 51-21-8), gemcitabine (GEMZAR ® , Lilly), PD-0325901 (CAS No. 391210-10-9, Pfizer), cisplatin (cis- diamine, dichloroplatinum(II), CAS No. 15663-27-1), carboplatin (CAS No.
  • erlotinib TARCEVA , Genentech/OSI Pharm.
  • TXOTERE ® Sanofi-Aventis
  • 5-FU fluorouracil, 5-fluorouracil, CAS No. 51-21-8
  • gemcitabine GEMZAR ® , Lilly
  • paclitaxel TAXOL ® , Bristol-Myers Squibb Oncology, Princeton, N.J.
  • trastuzumab HERCEPTIN ® , Genentech
  • temozolomide 4-methyl-5-oxo- 2,3,4,6,8-pentazabicyclo [4.3.0] nona-2,7,9-triene- 9-carboxamide, CAS No.
  • Additional commercially or clinically available anti-cancer agents comprise ibrutinib (J BRUVICA ® , Abb Vie) oxaliplatin (ELOXATIN ® , Sanofi), bortezomib (VELCADE ® , Millennium Pharm.), sutent (SUNITINIB ® , SU11248, Pfizer), letrozole (FEMARA ® , Novartis), imatinib mesylate (GLEEVEC ® , Novartis), XL-518 (Mek inhibitor, Exelixis, WO 2007/044515), ARRY-886 (Mek inhibitor, AZD6244, Array BioPharma, Astra Zeneca), SF-1126 (PI3K inhibitor, Semafore Pharmaceuticals), BEZ-235 (PI3K inhibitor, Novartis), XL-147 (PI3K inhibitor, Exelixis), PTK787/ZK 222584 (Novartis), fulvest
  • salts means organic or inorganic salts of a molecule or macromolecule. Acid addition salts can be formed with amino groups. Exemplary salts include, but are not limited, to sulfate, citrate, acetate, oxalate, chloride, bromide, iodide, nitrate, bisulfate, phosphate, acid phosphate, isonicotinate, lactate, salicylate, acid citrate, tartrate, oleate, tannate, pantothenate, bitartrate, ascorbate, succinate, maleate, gentisinate, fumarate, gluconate, glucuronate, saccharate, formate, benzoate, glutamate, methanesulfonate, ethanesulfonate, benzenesulfonate, p-toluenesulfonate, and pamoate (i.e., 1,1 ' methylene bis
  • a pharmaceutically acceptable salt may involve the inclusion of another molecule such as an acetate ion, a succinate ion or other counterion.
  • the counterion may be any organic or inorganic moiety that stabilizes the charge on the parent compound.
  • a pharmaceutically acceptable salt may have more than one charged atom in its structure. Where multiple charged atoms are part of the pharmaceutically acceptable salt, the salt can have multiple counter ions. Hence, a pharmaceutically acceptable salt can have one or more charged atoms and/or one or more counterion.
  • solvate refers to an association of one or more solvent molecules and a molecule or macromolecule.
  • solvents that form pharmaceutically acceptable solvates include, but are not limited to, water, isopropanol, ethanol, methanol, DMSO, ethyl acetate, acetic acid, and ethanolamine.
  • the antibodies or ADCs of the instant invention may be used in combination with any one of a number of antibodies (or immunotherapeutic agents) presently in clinical trials or commercially available.
  • the disclosed antibodies may be used in combination with an antibody selected from the group consisting of abagovomab, adecatumumab, afutuzumab, alemtuzumab, altumomab, amatuximab, anatumomab, arcitumomab, atezolizumab, avelumab, bavituximab, bectumomab, bevacizumab, bivatuzumab, blinatumomab, brentuximab, cantuzumab, catumaxomab, cetuximab, citatuzumab, cixutumumab, clivatuzumab, conatumumab, dacetuzumab, dalotuzuma
  • inventions comprise the use of antibodies approved for cancer therapy including, but not limited to, rituximab, gemtuzumab ozogamcin, alemtuzumab, ibritumomab tiuxetan, tositumomab, bevacizumab, cetuximab, patitumumab, ofatumumab, ipilimumab and brentuximab vedotin.
  • antibodies approved for cancer therapy including, but not limited to, rituximab, gemtuzumab ozogamcin, alemtuzumab, ibritumomab tiuxetan, tositumomab, bevacizumab, cetuximab, patitumumab, ofatumumab, ipilimumab and brentuximab vedotin.
  • rituximab gemtuzuma
  • the present invention also provides for the combination of antibodies or ADCs with radiotherapy (i.e., any mechanism for inducing DNA damage locally within tumor cells such as gamma-irradiation, X-rays, UV-irradiation, microwaves, electronic emissions and the like).
  • radiotherapy i.e., any mechanism for inducing DNA damage locally within tumor cells such as gamma-irradiation, X-rays, UV-irradiation, microwaves, electronic emissions and the like.
  • Combination therapy using the directed delivery of radioisotopes to tumor cells is also contemplated, and the disclosed antibodies or ADCs may be used in connection with a targeted anticancer agent or other targeting means.
  • radiation therapy is administered in pulses over a period of time from about 1 to about 2 weeks.
  • the radiation therapy may be administered to subjects having head and neck cancer for about 6 to 7 weeks.
  • the radiation therapy may be administered as a single dose or as multiple, sequential doses.
  • the invention provides for the use of antibodies and ADCs of the invention for the diagnosis, theragnosis, treatment and/or prophylaxis of various disorders including neoplastic, inflammatory, angiogenic and immunologic disorders and disorders caused by pathogens.
  • the diseases to be treated comprise neoplastic conditions comprising solid tumors.
  • the diseases to be treated comprise hematologic malignancies.
  • the antibodies or ADCs of the invention will be used to treat tumors or tumorigenic cells expressing a KREMEN2 determinant.
  • the "subject" or "patient” to be treated will be human although, as used herein, the terms are expressly held to comprise any mammalian species.
  • the compounds and compositions of the instant invention may be used to treat subjects at various stages of disease and at different points in their treatment cycle. Accordingly, in certain embodiments the antibodies and ADCs of the instant invention will be used as a front line therapy and administered to subjects who have not previously been treated for the cancerous condition. In other embodiments the antibodies and ADCs of the invention will be used to treat second and third line patients (i.e., those subjects that have previously been treated for the same condition one or two times respectively). Still other embodiments will comprise the treatment of fourth line or higher patients (e.g., gastric or colorectal cancer patients) that have been treated for the same or related condition three or more times with the disclosed KREMEN2 ADCs or with different therapeutic agents.
  • fourth line or higher patients e.g., gastric or colorectal cancer patients
  • the compounds and compositions of the present invention will be used to treat subjects that have previously been treated (with antibodies or ADCs of the present invention or with other anti-cancer agents) and have relapsed or are determined to be refractory to the previous treatment.
  • the compounds and compositions of the instant invention may be used to treat subjects that have recurrent tumors.
  • the proliferative disorder will comprise a solid tumor including, but not limited to, adrenal, liver, kidney, bladder, breast, gastric, ovarian, cervical, uterine, esophageal, colorectal, prostate, pancreatic, lung (both small cell and non-small cell including lung adenocarcinoma), thyroid, carcinomas, sarcomas, glioblastomas and various head and neck tumors.
  • the disclosed ADCs are particularly effective at treating squamous cell lung cancer (SCC-LU) and, in selected aspects, luminal B breast cancer B (BR-LumB).
  • the lung cancer is refractory, relapsed or resistant to anthracyclines and/or a taxane (e.g., docetaxel, paclitaxel, larotaxel or cabazitaxel).
  • a taxane e.g., docetaxel, paclitaxel, larotaxel or cabazitaxel.
  • the disclosed antibodies and ADCs may be used for the treatment of medullary thyroid cancer, large cell neuroendocrine carcinoma (LC EC), glioblastoma, neuroendocrine prostate cancer (NEPC), high-grade gastroenteropancreatic cancer (GEP) and malignant melanoma.
  • the ADCs of the instant invention may be used to treat colorectal cancer.
  • colonal cancer is meant to include the well- accepted medical definition that defines colorectal cancer as a medical condition characterized by cancer of cells of the intestinal tract below the small intestine (i.e. the large intestine (colon), including the cecum, ascending colon, transverse colon, descending colon, and sigmoid colon, and rectum). Additionally, as used herein, the term “colorectal cancer” is meant to further include medical conditions that are characterized by cancer of cells of the duodenum and small intestine (jejunum and ileum).
  • colorectal cancer used herein is more expansive than the common medical definition but is provided as such since the cells of the duodenum and small intestine may also be amenable to the methods of the present invention.
  • the compounds of the invention may be used to treat stage I colorectal cancer, stage II colorectal cancer, stage III colorectal cancer or stage IV colorectal cancer.
  • the compounds and compositions of the instant invention may be used to treat gastric cancer.
  • compositions disclosed herein may be used to treat acinar cell pancreatic carcinoma, duodenal pancreatic carcinoma, mucinous pancreatic adenocarcinoma, neuroendocrine pancreatic cancer, pancreatic adenocarcinoma, pancreatic adenocarcinoma exocrine type, ductal pancreatic adenocarcinoma and ampullary pancreatic adenocarcinoma.
  • More generally exemplary neoplastic conditions subject to treatment in accordance with the instant invention may be benign or malignant; solid tumors or hematologic malignancies; and may be selected from the group including, but not limited to: adrenal gland tumors, AIDS-associated cancers, alveolar soft part sarcoma, astrocytic tumors, autonomic ganglia tumors, bladder cancer (squamous cell carcinoma and transitional cell carcinoma), blastocoelic disorders, bone cancer (adamantinoma, aneurismal bone cysts, osteochondroma, osteosarcoma), brain and spinal cord cancers, metastatic brain tumors, breast cancer, carotid body tumors, cervical cancer, chondrosarcoma, chordoma, chromophobe renal cell carcinoma, clear cell carcinoma, colon cancer, colorectal cancer, cutaneous benign fibrous histiocytomas, desmoplastic small round cell tumors, ependymomas, epithelial disorders, Ewing's tumors, extra
  • the compounds and compositions of the instant invention will be used as a front line therapy and administered to subjects who have not previously been treated for the cancerous condition.
  • the compounds and compositions of the present invention will be used to treat subjects that have previously been treated (with antibodies or ADCs of the present invention or with other anti-cancer agents) and have relapsed or determined to be refractory to the previous treatment.
  • the compounds and compositions of the instant invention may be used to treat subjects that have recurrent tumors.
  • the compounds and compositions of the instant invention will be used as a front line therapy and administered to subjects who have not previously been treated for the cancerous condition.
  • the compounds and compositions of the present invention will be used to treat subjects that have previously been treated (with antibodies or ADCs of the present invention or with other anti-cancer agents) and have relapsed or determined to be refractory to the previous treatment.
  • the compounds and compositions of the instant invention may be used to treat subjects that have recurrent tumors.
  • the compounds and methods of the present invention may be particularly effective in treating a variety of leukemias including acute myeloid leukemia (AML, cognizant of its various subtypes based on the FAB nomenclature (M0-M7), WHO classification, molecular marker/mutations, karyotype, morphology, and other characteristics), lineage acute lymphoblastic leukemia (ALL), chronic myeloid leukemia (CML), chronic lymphocytic leukemia (CLL), hairy cell leukemia (HCL), chronic myelomonocytic leukemia (CMML), juvenile myelomonocytic leukemia (JMML) and large granular lymphocytic leukemia (LGL) as well as B-cell lymphomas, including Hodgkin's lymphoma (classic Hodgkin's lymphoma and nodular lymphocyte-predominant Hodgkin lymphoma), Non-cell lymphomas, including Hodgkin's lymphoma
  • lymphomas will often have different names due to changing systems of classification, and that patients having lymphomas classified under different names may also benefit from the combined therapeutic regimens of the present invention.
  • the disclosed ADCs are effective at treating gastric cancers, including intestinal type, diffuse type, gastric cardia, gastric stromal type, carcinoid, and signet ring cell gastric adenocarcinomas.
  • gastric cancer is refractory, relapsed or resistant to a radiation, 5-fluorouracil, platinum-based agents (e.g. carboplatin, cisplatin, oxaliplatin), or combinations thereof.
  • the antibodies and ADCs can be administered to patients exhibiting non-metastatic or metastatic gastric cancers.
  • the disclosed conjugated antibodies will be administered to refractory patients (i.e., those whose disease recurs during or shortly after completing a course of initial therapy); sensitive patients (i.e., those whose relapse is longer than 2-3 months after primary therapy); or patients exhibiting resistance to radiation, 5-fluorouracil, and/or a platinum based agent (e.g. carboplatin, cisplatin, oxaliplatin).
  • refractory patients i.e., those whose disease recurs during or shortly after completing a course of initial therapy
  • sensitive patients i.e., those whose relapse is longer than 2-3 months after primary therapy
  • a platinum based agent e.g. carboplatin, cisplatin, oxaliplatin.
  • compatible ADCs may be used in combination with other anti-cancer agents depending on the selected dosing regimen and the clinical diagnosis.
  • the disclosed ADCs are especially effective at treating colorectal cancers, including adenocarcinomas, mucinous adenocarcinomas, intestinal carcinoid, intestinal stromal, leiomyosarcoma, squamous cell carcinoma, neuroendocrine carcinoma, and signet ring cell carcinomas of the small intestine, colon, and rectum.
  • the colorectal cancer is refractory, relapsed or resistant to a radiation, 5-fluorouracil, platinum-based agents (e.g.
  • the antibodies and ADCs can be administered to patients exhibiting non-metastatic or metastatic colorectal cancers.
  • the disclosed conjugated antibodies will be administered to refractory patients (i.e., those whose disease recurs during or shortly after completing a course of initial therapy); sensitive patients (i.e., those whose relapse is longer than 2-3 months after primary therapy); or patients exhibiting resistance to radiation, 5-fluorouracil, platinum-based agents (e.g. carboplatin, cisplatin, oxaliplatin), VEGF-A-targeted agents, VEGF receptor-targeted agents, and/or EGFR-targeted agents.
  • platinum-based agents e.g. carboplatin, cisplatin, oxaliplatin
  • VEGF-A-targeted agents e.g. carboplatin, cisplatin, oxaliplatin
  • VEGF-A-targeted agents e.g. carboplatin, cisplatin, oxaliplatin
  • VEGF-A-targeted agents e.g. carbop
  • the disclosed ADCs are effective at treating lung cancers, including lung adenocarcinoma, small lung cancer (SCLC) and non-small cell lung cancer (NSCLC) (e.g., squamous cell non-small cell lung cancer or squamous cell small cell lung cancer).
  • lung cancer is refractory, relapsed or resistant to a platinum based agent (e.g., carboplatin, cisplatin, oxaliplatin) and/or a taxane (e.g., docetaxel, paclitaxel, larotaxel or cabazitaxel).
  • LC EC large cell neuroendocrine carcinoma
  • the KREMEN2 ADCs of the instant invention may be administered to frontline patients suffering from squamous cell lung cancer. In other embodiments the KREMEN2 ADCs of the instant invention may be administered to second line patients suffering from the same afflictions. In still other embodiments the KREMEN2 ADCs of the instant invention may be administered to third line patients having squamous cell lung cancer.
  • the disclosed antibodies and ADCs are effective at treating lung cancer, including the following subtypes: small cell lung cancer and non-small cell lung cancer (e.g. squamous cell lung cancer).
  • the disclosed compositions may be used to treat lung adenocarcinoma.
  • the antibodies and ADCs can be administered to patients exhibiting limited stage disease or extensive stage disease.
  • the disclosed conjugated antibodies will be administered to refractory patients (i.e., those whose disease recurs during or shortly after completing a course of initial therapy); sensitive patients (i.e., those whose relapse is longer than 2-3 months after primary therapy); or patients exhibiting resistance to a platinum based agent (e.g.
  • the KREMEN2 ADCs of the instant invention may be administered to frontline patients.
  • the KREMEN2 ADCs of the instant invention may be administered to second line patients.
  • the KREMEN2 ADCs of the instant invention may be administered to third line patients.
  • compatible ADCs may be used in combination with other anti-cancer agents depending the selected dosing regimen and the clinical diagnosis.
  • breast cancer is a heterogeneous disease with several biologic subtypes identified.
  • breast cancer is now recognized as comprising at least four distinct neoplastic subtypes based on the expression of estrogen receptor (ER), progesterone receptor (PR), and erbB2/Her2. These subtypes include: basal-like/triple negative breast cancer, Her2 -positive breast cancer, luminal A breast cancer and luminal B breast cancer.
  • Luminal A is the most common breast cancer subtype (40% of all invasive breast cancer) and is characterized by ER+ and/or PR+/Her2- status, low-grade tumors and good prognosis.
  • Luminal B subtype accounts for roughly 25% of all invasive breast cancer and is distinguished by ER+ and/or PR+/Her2+ status with poor outcomes.
  • Breast cancer subtypes (20% of all invasive breast cancer) with negative ER, PR and Her2 status are typically called triple negative breast cancer or basal-like breast cancer.
  • the Her2-enriched subtype (Her2+/ER-/PR-) is least common, with 15% of all invasive breast cancer.
  • the antibodies and ADCs of the instant invention may be used to treat all different types of KREMEN2 positive breast cancers, it may be particularly effective treating basal-like breast cancer and luminal-B breast cancer, where therapeutic resistance is common and, as shown in the Examples below, where molecular profiling has identified KREMEN2 as a promising new therapeutic target.
  • luminal-A and luminal-B subtypes have expression patterns reminiscent of the luminal epithelial component of the breast, including expression of luminal cytokeratins 8/18, ER and genes associated with ER activation such as CC D1 (cyclin Dl).
  • luminal B has lower expression of ER-related genes and higher expression of proliferative genes.
  • a review of several gene expression studies noted that approximately 20% of luminal-B breast cancers were HER2-positive by immunohistochemistry. Approximately 30% of HER2-positive tumors defined by immunohistochemistry are assigned to the luminal-B subtype.
  • luminal-B breast cancer has been defined as ER-positive breast cancer with increased proliferation.
  • proliferation genes such as CCNBl, MKI67 and MYBL2 are more highly expressed in luminal-B compared with luminal-A subtypes, correlating with a higher proportion of histological grade III also observed in luminal-B cancers.
  • Proliferation has been consistently identified as the most important feature of several prognostic multigene signatures, including the intrinsic molecular classification.
  • proliferation is the strongest predictor of early relapse risk that differentiates high-risk luminal-B tumors from low-risk luminal-A tumors.
  • luminal breast cancers appear to have a predilection for metastasis to lung, bone and pleura.
  • luminal-B breast cancer is relatively insensitive to endocrine therapy compared with luminal-A breast cancer, and to chemotherapy compared with HER2-enriched and basal-like breast cancers.
  • the ADCs and antibodies of the instant invention have been shown to exhibit anti-tumor activity as shown in the Examples below. More specifically the disclosed anti-KREMEN2 ADCs are shown to effectively and specifically associate with tumorigenic cells in luminal-B breast cancer. This targeting of the selected tumor cells is indicative of agents with substantial therapeutic potential.
  • the invention includes pharmaceutical packs and kits comprising one or more containers or receptacles, wherein a container can comprise one or more doses of an antibody or ADC of the invention.
  • kits or packs may be diagnostic or therapeutic in nature.
  • the pack or kit contains a unit dosage, meaning a predetermined amount of a composition comprising, for example, an antibody or ADC of the invention, with or without one or more additional agents and optionally, one or more anti-cancer agents.
  • the pack or kit contains a detectable amount of an anti-KREMEN2 antibody or ADC, with or without an associated reporter molecule and optionally one or more additional agents for the detection, quantitation and/or visualization of cancerous cells.
  • kits of the invention will generally comprise an antibody or ADC of the invention in a suitable container or receptacle a pharmaceutically acceptable formulation and, optionally, one or more anti-cancer agents in the same or different containers.
  • the kits may also contain other pharmaceutically acceptable formulations or devices, either for diagnosis or combination therapy.
  • diagnostic devices or instruments include those that can be used to detect, monitor, quantify or profile cells or markers associated with proliferative disorders (for a full list of such markers, see above).
  • the devices may be used to detect, monitor and/or quantify circulating tumor cells either in vivo or in vitro (see, for example, WO 2012/0128801).
  • the circulating tumor cells may comprise tumorigenic cells.
  • the kits contemplated by the invention can also contain appropriate reagents to combine the antibody or ADC of the invention with an anti-cancer agent or diagnostic agent (e.g., see U. S.P.N. 7,422,739).
  • the liquid solution can be non-aqueous, though typically an aqueous solution is preferred, with a sterile aqueous solution being particularly preferred.
  • the formulation in the kit can also be provided as dried powder(s) or in lyophilized form that can be reconstituted upon addition of an appropriate liquid.
  • the liquid used for reconstitution can be contained in a separate container.
  • Such liquids can comprise sterile, pharmaceutically acceptable buffer(s) or other diluent(s) such as bacteriostatic water for injection, phosphate-buffered saline, Ringer's solution or dextrose solution.
  • the solution may be pre-mixed, either in a molar equivalent combination, or with one component in excess of the other.
  • the antibody or ADC of the invention and any optional anti-cancer agent or other agent e.g., steroids
  • kits comprising compositions of the invention will comprise a label, marker, package insert, bar code and/or reader indicating that the kit contents may be used for the treatment, prevention and/or diagnosis of cancer.
  • the kit may comprise a label, marker, package insert, bar code and/or reader indicating that the kit contents may be administered in accordance with a certain dosage or dosing regimen to treat a subject suffering from cancer.
  • the label, marker, package insert, bar code and/or reader indicates that the kit contents may be used for the treatment, prevention and/or diagnosis of lung cancer or provide dosages or a dosing regimen for treatment of the same.
  • the label, marker, package insert, bar code and/or reader indicates that the kit contents may be used for the treatment, prevention and/or diagnosis of breast cancer (e.g., luminal B breast cancer) or a dosing regimen for treatment of the same.
  • breast cancer e.g., luminal B breast cancer
  • Suitable containers or receptacles include, for example, bottles, vials, syringes, infusion bags
  • the containers can be formed from a variety of materials such as glass or pharmaceutically compatible plastics.
  • the receptacle(s) can comprise a sterile access port.
  • the container may be an intravenous solution bag or a vial having a stopper that can be pierced by a hypodermic injection needle.
  • the kit can contain a means by which to administer the antibody and any optional components to a patient, e.g., one or more needles or syringes (pre-filled or empty), an eye dropper, pipette, or other such like apparatus, from which the formulation may be injected or introduced into the subject or applied to a diseased area of the body.
  • the kits of the invention will also typically include a means for containing the vials, or such like, and other components in close confinement for commercial sale, such as, e.g., blow-molded plastic containers into which the desired vials and other apparatus are placed and retained.
  • Table 3 provides a summary of amino acid and nucleic acid sequences included herein.
  • VK08 full length light chain protein
  • PDX tumor cell types are denoted by an abbreviation followed by a number, which indicates the particular tumor cell line.
  • the passage number of the tested sample is indicated by p0-p# appended to the sample designation where pO is indicative of an unpassaged sample obtained directly from a patient tumor and p# is indicative of the number of times the tumor has been passaged through a mouse prior to testing.
  • the abbreviations of the tumor types and subtypes are shown in Table 4 as follows:
  • a large PDX tumor bank was developed and maintained using art recognized techniques.
  • the PDX tumor bank comprising a large number of discrete tumor cell lines, was propagated in immunocompromised mice through multiple passages of tumor cells originally obtained from cancer patients afflicted by a variety of solid tumor malignancies.
  • Low passage PDX tumors are representative of tumors in their native environments, providing clinically relevant insight into underlying mechanisms driving tumor growth and resistance to current therapies.
  • tumor cells may be divided broadly into two types of cell subpopulations: non-tumori genie cells (NTG) and tumor initiating cells (TICs).
  • NTG non-tumori genie cells
  • TICs tumor initiating cells
  • CSCs Cancer stem cells
  • NTGs while sometimes able to grow in vivo, will not form tumors that recapitulate the heterogeneity of the original tumor when implanted.
  • PDX tumors were resected from mice after reaching 800 - 2,000 mm 3 or for AML after the leukemia was established in the bone marrow ( ⁇ 5% of bone marrow cellularity of human origin). Resected PDX tumors were dissociated into single cell suspensions using art-recognized enzymatic digestion techniques (see, for example, U. S.P.N. 2007/0292414). Dissociated bulk tumor cells were incubated with 4',6-diamidino-2-phenylindole (DAPI) to detect dead cells, anti-mouse CD45 and H-2K d antibodies to identify mouse cells and anti-human EPCAM antibody to identify human cells.
  • DAPI 4',6-diamidino-2-phenylindole
  • the tumor cells were incubated with fluorescently conjugated anti-human CD46 and/or CD324 antibodies to identify CD324 + CSCs or CD324 " NTG cells and were then sorted using a FACS Aria cell sorter (BD Biosciences) (see U.S.P. Ns 2013/0260385, 2013/0061340 and 2013/0061342).
  • Anti-human CD49f and EPCAM antibodies were also used to identify four different subpopulations as described by Lim et. al., 2009 (PMID: 19648928) within the normal human breast, including differentiated luminal, progenitor and mammary stem/basal epithelial cells, as well as stromal cells.
  • a normal lung epithelial population was sorted using anti-human EPCAM.
  • Illumina whole transcriptome analysis was performed with cDNA that was generated using 5 ng total RNA extracted from either bulk or sorted subpopulations that were isolated as described above.
  • the library was created using the TruSeq RNA Sample Preparation Kit v2 (Illumina, Inc.).
  • the resulting cDNA library was fragmented and barcoded. Sequencing data from the Illumina platform is nominally represented as a fragment expression value using the metric FPKM (fragment per kilobase per million) mapped to exon regions of genes, enabling basic gene expression analysis to be normalized and enumerated as FPKM transcript.
  • KREMEN2 mRNA expression is upregulated CSC populations from luminal B PDX tumors (black bars), and in CSC populations from non-small cell lung cancer tumors (grey bars) relative to matched NTG populations (white bars) from these same tumors.
  • KREMEN2 expression was generally higher in tumor samples than KREMEN2 expression in both normal tissues and various sorted normal breast and normal lung epithelial populations.
  • KREMEN2 has potential as a diagnostic and immunotherapeutic target. Furthermore, increased expression of KREMEN2 in sorted populations indicates that KREMEN2 is a good marker of tumorigenic cells.
  • KREMEN2 expression in normal tissues was compared to expression in various molecular subtypes of breast (BR) tumors - unclassified BR, BR-Basal Like, BR-CLDN low, BR-HER2 positive, BR-LumA, and BR-LumB, as well as NSCLC (LU-Ad and LU-SCC), endometrial (EM), ovarian (OV-serous/papillary serous and MMMT) and MEL (FIG. 3; each dot represents the average relative expression of each individual tissue or PDX cell line, with the small horizontal line representing the geometric mean).
  • Normalx represents samples of various normal tissues as follows: adrenal, colon, dorsal root ganglion, endothelial cells (artery, vein), esophagus, heart, kidney, liver, lung, pancreas, skeletal muscle, skin (fibroblasts, keratinocytes), small intestine, spleen, stomach, and trachea.
  • Normal represents the following samples of normal tissue with a presumed lower risk for toxicity in relation to ADC-type drugs: peripheral blood mononuclear cells and various sorted subpopulations (B cells, monocytes, NK cells, neutrophils, T cells), adipose, bladder, brain, breast, cervix, fetal liver, melanocytes, normal bone marrow and various sorted subpopulations, ovary, prostate, testes, thymus, thyroid and uterus.
  • B cells peripheral blood mononuclear cells and various sorted subpopulations (B cells, monocytes, NK cells, neutrophils, T cells), adipose, bladder, brain, breast, cervix, fetal liver, melanocytes, normal bone marrow and various sorted subpopulations, ovary, prostate, testes, thymus, thyroid and uterus.
  • FIG. 3 shows that on average KREMEN2 expression was elevated in subsets of BR PDX of varying subtypes, with the majority of LumB samples showing elevated expression. Similarly, the majority of OV tumors were strongly positive for KREMEN2 expression. Additionally, subsets of EM, LU-Ad, LU-SCC, and MEL PDX were elevated in KREMEN2 expression. Most normal and norm tox tissues expressed low levels of KREMEN2, with exceptions of strong (>10 4 ) relative expression in esophagus, skin, pancreas and trachea in this assay. Normal tissues with significant signals were thymus and normal bone marrow, which in turn were likely due to detected RNA expression in lymphocytes. These data support the earlier finding of elevated expression of KREMEN2 in LumB and in addition highlights overexpression in significant subsets of PDX tumors of various types compared to most normal tissues.
  • RNA samples were analyzed using the Agilent SurePrint GE Human 8x60 v2 microarray platform, which contains 50,599 biological probes designed against 27,958 genes and 7,419 IncRNAs in the human genome. Standard industry practices were used to normalize and transform the intensity values to quantify gene expression for each sample.
  • the normalized intensity of KREMEN2 expression in each sample is plotted in FIG. 4 and the geometric mean derived for each tumor type is indicated by the horizontal bar.
  • KREMEN2 expression is on average upregulated in BR, EN, LU-Ad, LU-SCC, OV and MEL relative to that observed for normal tissues, although within each PDX type there typically is a wide spread in KREMEN2 expression levels.
  • the elevated KREMEN2 in the BR-LumB subtype as well as OV.
  • the normal tissue with the highest expression of KREMEN2 was skin, with most other normal tissues expressing at least 30-fold less KREMEN2.
  • the observation of elevated KREMEN2 expression in the aforementioned tumor types confirms the results of the previous Examples.
  • KREMEN2 expression data from the IlluminaHiSeq_RNASeqV2 platform and the IlluminaHiSeq RNASeq platform was downloaded from the TCGA Data Portal (h p / icun-- d ata . nci . m h . gov/ tc ga/'tc gaD o n I oad . j sp ) and parsed to aggregate the reads from the individual exons of each gene to generate a single value read per kilobase of exon per million mapped reads (RPKM).
  • KREMEN2 expression in FIG. 5 is elevated in primary BL, BR, ES, HN, LY, LU, OV, OR, SK, and UT tumors, relative to normal tissues found in the TCGA database. These data imply there is a good therapeutic index above normal tissues and therefore anti-KREMEN2 antibodies and ADCs may be useful therapeutics for the treatment of these tumors.
  • Example 5
  • hKREMEN2 human KREMEN2 (hKREMEN2) protein
  • GenBank accession NP_757384, SEQ ID NO: 1 a synthetic DNA fragment encoding the mature hKREMEN2 protein ECD (residues G26-A364) was ordered from GeneArt (Therm oFisher Scientific) using NCBI accession NM_172229 as reference.
  • the synthetic gene fragment was codon optimized for expression in mammalian lines. This DNA fragment was used for all subsequent engineering of constructs expressing fusion or tagged proteins containing the hKREMEN2 ECD, or fragments thereof.
  • constructs were generated in which this DNA fragment was fused in-frame to DNA encoding either a 9x-Histidine tag (hKREMEN2-ECD-His), or a human IgG2 Fc protein (hKREMEN2-ECD-Fc), using standard molecular techniques.
  • hKREMEN2-ECD-His 9x-Histidine tag
  • hKREMEN2-ECD-Fc human IgG2 Fc protein
  • HEK293T cells Suspension or adherent cultures of HEK293T cells, or suspension CHO-S cells were transfected with either hKREMEN2-ECD-His or hKREMEN2-ECD-Fc, using polyethylenimine polymer as the transfecting reagent.
  • the recombinant proteins were purified from clarified cell-supernatants using either Nickel-EDTA (Qiagen) or MabSelect SuReTM Protein A (GE Healthcare Life Sciences) columns as appropriate to the tag.
  • lentiviral vectors containing an open reading frame encoding the mature hKREMENZ protein were constructed as follows. First, standard molecular cloning techniques were used to introduce nucleotide sequences encoding an IgK signal peptide followed by a poly-Asp Lys epitope tag upstream of the multiple cloning site of pCDH-CMV-MCS-EFl-copGFP (System Biosciences), creating the vector pLMEGPA.
  • This dual promoter construct employs a CMV promoter to drive expression of the epitope-tagged cell surface proteins independent of a downstream EF1 promoter that drives expression of the copGFP T2A Puro reporter and selectable marker.
  • the T2A sequence in pLMEGPA promotes ribosomal skipping of a peptide bond condensation, resulting in expression of two independent proteins: high level expression of the reporter copGFP encoded upstream of the T2A peptide, with co-expression of the Puro selectable marker protein encoded downstream of the T2A peptide allowing selection in the presence of puromycin.
  • a synthetic DNA fragment encoding the mature hKREMEN2 protein was ordered from GeneArt (ThermoFisher Scientific) using NCBI accession M_172229 as reference.
  • the synthetic gene was codon optimized for expression in mammalian lines, and was flanked with restriction endonuclease sites to enable in-frame subcloning downstream of the IgK signal peptide-epitope tag in pLMEGPA. This yielded the pLMEGPA-hKREMEN2-NFlag lentiviral vector, which encodes a fusion protein with the epitope tag appended to the N-terminus of the mature hKREMEN2 protein.
  • GenBank accession NM_001105767 was used as reference to design synthetic cDNA fragments encoding either the mature ECD (NP_001099237; amino acids G25-R373) or mature full length (NP OO 1099237; amino acids G25-L468) rKREMEN2 proteins.
  • GenBank accession XM_005591011 was used as a reference to design synthetic cDNA fragments encoding either the mature ECD (XP 005591068; amino acids G26-A364) or mature full length (XP_005591068; amino acids G26-L462) cKREMEN2 proteins. All synthetic DNA fragments were codon optimized for expression in mammalian lines.
  • Chimeric fusion genes for either the rat or cynomolgus KREMEN2 ECD and a 9-Histidine tag or human IgG2 Fc tag were constructed by subcloning the DNA fragment encoding the respective mature ECD fragment into a CMV driven expression vector in-frame and downstream of an IgK signal peptide sequence and upstream of either a 9-Histidine tag or a human IgG2 Fc cDNA, using standard molecular techniques.
  • CMV-driven expression vectors were used to transfect suspension or adherent cultures of HEK-293T cells, or suspension CHO-S cells to produce recombinant protein, as described previously for the analogous hKREMEN2 fusion proteins, above.
  • lentiviral vectors containing an open reading frame encoding the respective mature rKREMEN2 or CKREMEN2 proteins were constructed using standard molecular techniques, to subclone either the mature full length rKREMEN2 or cKREMEN2 open reading frame downstream of the IgK signal peptide-epitope tag in pLMEGPA, yielding pLMEGPA-rKREMEN2- Flag or pLMEGPA- cKREMEN2- Flag, respectively.
  • Engineered cell lines overexpressing the hKREMEN2, rKREMEN2 or cKREMEN2 proteins were constructed using the respective pLMEGPA vectors, described above, to transduce HEK-293T cell lines using standard lentiviral transduction techniques well known to those skilled in the art.
  • KREMEN2 -positive cells in each instance were selected using fluorescent activated cell sorting (FACS) of puromycin resistant, high-expressing FIEK-293T subclones (e.g., cells that were resistant to puromycin and strongly positive for both GFP and the epitope tag).
  • FACS fluorescent activated cell sorting
  • Anti-KREMEN2 mouse antibodies were produced by inoculating one BALB/c mouse, one CD-I mouse, and one FVB mouse with 10 ⁇ g hKREMEN2 protein, emulsified with an equal volume of TiterMax ® Gold Adjuvant (Sigma Aldrich #H4 T2684-1ML). Following the initial inoculation, the mice were injected at weekly intervals, 9 times with 10 ⁇ g hKREMEN2 protein emulsified with an equal volume of Imject ® Alum (ThermoScientific) plus "CpG" (InvivoGen). The final injection prior to the fusion was with 10 ⁇ g hKREMEN2 in PBS.
  • mice were sacrificed, and draining lymph nodes (popliteal, inguinal, and medial iliac) were dissected and used as a source for antibody producing cells.
  • a single-cell suspension of B cells was produced and (3 xlO 8 cells) were fused with non-secreting SP2/0-Agl4 myeloma cells (ATCC # CRL-1581) at a ratio of 1 : 1 by electro cell fusion using a model BTX Hybrimmune System (BTX Harvard Apparatus).
  • Hybridoma selection medium consisting of DMEM medium supplemented with azaserine, 15% fetal clone I serum (Thermo #SH30080-03), 10% BM condimed (Roche # 10663573001), 1 mM nonessential amino acids (Corning #25-025-0) 1 mM HEPES Corning #25-060-0), 100 IU penicillin-streptomycin (Corning #30-002-0), 100 IU L- glutamine (Corning #25-005-0) and were cultured in three T225 flasks containing 100 mL selection medium. The flasks were placed in a humidified 37°C incubator containing 7% C0 2 and 95% air for 6 days.
  • hybridoma cells were sorted from the flask and plated at one cell per well (using a BD FACSAria cell sorter) in 90 of supplemented hybridoma selection medium (as described above) into 12 Falcon 384-well plates. Remaining unused hybridoma library cells were frozen in liquid nitrogen for future library testing and screening.
  • Sorted clonal hybridomas were cultured for 8 days and the supernatants were collected, re- arrayed onto 384-well plates, and screened for antibodies specific to hKREMEN2 expressed on the surface of transduced HEK/293T cells (ATCC CRL-11268) using flow cytometry, as follows. 293T cells stably transduced with hKREMEN2 in each well were incubated for 30 minutes with 25 ⁇ L hybridoma supernatant and then washed with PBS/2% FCS.
  • An ELISA assay was also used to screen the hybridoma supernatants for antibodies that bound to rKREMEN2.
  • the ELISA was performed as follows. Plates were coated with purified rKREMEN2-His at 0.5 ⁇ g/mL in PBS buffer and incubated at 4 °C overnight. Plates were then washed with PBST and blocked with PBS with 5% FBS for 30 min. at 37 °C. The blocking solution was removed and 15 ⁇ PBST was added to the wells. 25 ⁇ of hybridoma supernatant was added and incubated for 1 hour at room temperature.
  • RNA samples were sequenced as described below.
  • Total RNA was purified from selected hybridoma cells using the RNeasy Miniprep Kit (Qiagen) according to the manufacturer's instructions. Between 10 4 and 10 5 cells were used per sample. Isolated RNA samples were stored at minus 80 °C until used.
  • variable region of the Ig heavy chain of each hybridoma was amplified using two 5' primer mixes comprising eighty-six mouse specific leader sequence primers designed to target the complete mouse VH repertoire in combination with a 3' mouse Cy primer specific for all mouse Ig isotypes.
  • two primer mixes containing sixty-four 5' VK leader sequences designed to amplify each of the VK mouse families was used in combination with a single reverse primer specific to the mouse kappa constant region in order to amplify and sequence the kappa light chain.
  • the VH and VL transcripts were amplified from 100 ng total RNA using the Qiagen One Step RT- PCR kit as follows.
  • PCR reaction mixtures included 1.5 ⁇ , of RNA, 0.4 ⁇ _, of 100 ⁇ of either heavy chain or kappa light chain primers (custom synthesized by Integrated DNA Technologies), 5 of 5x RT-PCR buffer, 1 dNTPs, and 0.6 ⁇ of enzyme mix containing reverse transcriptase and DNA polymerase.
  • the thermal cycler program was RT step 50 °C for 60 min., 95 °C for 15 min. followed by 35 cycles of (94.5 °C for 30 seconds, 57 °C for 30 seconds, 72 °C for 1 min.). There was then a final incubation at 72 °C for 10 min.
  • the extracted PCR products were sequenced using the same specific variable region primers as described above for the amplification of the variable regions. PCR products were sent to an external sequencing vendor (MCLAB) for PCR purification and sequencing services. Nucleotide sequences were analyzed using the EVIGT sequence analysis tool (http://www.imgt.org/IMGTmedical/sequence_analysis.htmn to identify germline V, D and J gene members with the highest sequence homology. The derived sequences were compared to known germline DNA sequences of the Ig V- and J-regions by alignment of VH and VL genes to the mouse germline database using a proprietary antibody sequence database.
  • FIG. 6A depicts the contiguous amino acid sequences of novel murine light chain variable regions from anti-KREMEN2 antibodies while FIG. 6B depicts the contiguous amino acid sequences of novel murine heavy chain variable regions from the same anti-KREMEN2 antibodies.
  • murine light and heavy chain variable region amino acid sequences are provided in SEQ ID NOS: 21 - 81 odd numbers.
  • FIG. 6C provides the nucleic acid sequences (SEQ ID NOS: 20-80, even numbers) encoding the amino acid sequences set forth in FIGS. 6A and 6B.
  • FIGS. 6A and 6B provide the annotated sequences of murine anti- KREMEN2 antibodies comprising: (1) a light chain variable region (VL) of SEQ ID NO: 21 and a heavy chain variable region (VH) of SEQ ID NO: 23; or (2) a VL of SEQ ID NO: 25 and a VH of SEQ ID NO: 27; or (3) a VL of SEQ ID NO: 29 and a VH of SEQ ID NO: 31; or (4) a VL of SEQ ID NO: 33 and a VH of SEQ ID NO: 35; or (5) a VL of SEQ ID NO: 37 and a VH of SEQ ID NO: 39; or (6) a VL of SEQ ID NO: 41 and a VH of SEQ ID NO: 43; or (7) a VL of SEQ ID NO: 45 and a VH of SEQ ID NO: 47; or (8) a VL of SEQ ID NO: 49 and a VH of SEQ ID NO: 51;
  • VL and VH amino acid sequences in FIGS. 6 A and 6B are annotated to identify the framework regions (i.e. FR1 - FR4) and the complementarity determining regions (i.e., CDRL1 - CDRL3 in FIG. 6A or CDRH1 - CDRH3 in FIG. 6B), defined as per Kabat et al.
  • the variable region sequences were analyzed using a proprietary version of the Abysis database to provide the CDR and FR designations. Though the CDRs are defined as per Kabat et al., those skilled in the art will appreciate that compatible CDR and FR designations can also be defined according to Chothia, McCallum or any other accepted nomenclature system (e.g., see FIGS. 6G - 6J).
  • monoclonal anti-KREMEN2 antibody SC78.1 comprises amino acid SEQ ID NOS.
  • SC78.4 comprises SEQ ID NOS: 21 and 23 for the light and heavy chain variable regions respectively;
  • SC78.4 comprises SEQ ID NOS: 21 and 23 for the light and heavy chain variable regions respectively;
  • SC78.3 comprises SEQ ID NOS: 29 and 31, and so on.
  • the exception to the sequential numbering scheme set forth in FIGS. 6A and 6B is at the end of Table 5 and comprises
  • SC78.39 which shares a light chain variable region (VL) with SC78.25.
  • SC78.39 comprises a light chain variable region (VL) comprising SEQ ID NO: 49 and a heavy chain variable region (VH) comprising SEQ ID NO: 81.
  • the corresponding nucleic acid sequence encoding the murine antibody amino acid sequence (set forth in FIG. 6C) has a SEQ ID NO: immediately preceding the corresponding amino acid SEQ ID NO.
  • the SEQ ID NOS: of the nucleic acid sequences of the VL and VH of the SC78.1 antibody are SEQ ID NOS: 20 and 22, respectively.
  • FIGS. 6G - 6 J provide CDR designations for the light and heavy chain variable regions of SC78.9, SC78.43, SC78.56 and SC78.59 as determined using Kabat, Chothia, ABM and Contact methodology.
  • the CDR designations depicted in FIGS. 6G - 6J were derived using a proprietary version of the Abysis database as discussed above.
  • the disclosed murine CDRs may be grafted into human framework sequences to provide CDR grafted or humanized anti-KREMEN2 antibodies in accordance with the instant invention.
  • Chimeric anti-KREMEN2 antibodies were generated using art-recognized techniques as follows. Total RNA was extracted from the hybridomas and PCR amplified. Data regarding V, D and J gene segments of the VH and VL chains of the following murine antibodies: SC78.9, SC78.43, SC78.56 and SC78.59 were obtained from an analysis of the subject nucleic acid sequences (see FIG. 6C for nucleic acid sequences). Primer sets specific to the framework sequence of the VH and VL chains of the antibodies were designed using the following restriction sites: Agel and Xhol for the VH fragments, and Xmal and Dralll for the VL fragments.
  • PCR products were purified with a Qiaquick PCR purification kit (Qiagen), followed by digestion with restriction enzymes Agel and Xhol for the VH fragments and Xmal and Dralll for the VL fragments.
  • the VH and VL digested PCR products were purified and ligated into IgH or IgK expression vectors, respectively. Ligation reactions were performed in a total volume of 10 with 200U T4-DNA Ligase (New England Biolabs), 7.5 of digested and purified gene-specific PCR product and 25 ng linearized vector DNA. Competent E.
  • coli DH10B bacteria (Life Technologies) were transformed via heat shock at 42 °C with 3 ⁇ L ligation product and plated onto ampicillin plates at a concentration of 100 ⁇ g/mL.
  • the VH fragment was cloned into the Agel-Xhol restriction sites of the pEE6.4 expression vector (Lonza) comprising HulgGI and the VL fragment was cloned into the Xmal-Dralll restriction sites of the pEE12.4 expression vector (Lonza) comprising Hu-Kappa light constant region.
  • Chimeric antibodies comprising the entire murine heavy and light chain variable regions (SC78.9, SC78.43, SC78.56 and SC78.59) and human constant regions were expressed by co- transfection of CHO-S cells with pEE6.4HuIgGl and pEE12.4Hu-Kappa expression vectors and PEI as a transfection reagent. Supernatants were harvested three to six days after transfection. Culture supernatants containing recombinant chimeric antibodies were cleared from cell debris by centrifugation at 800xg for 10 mins. and stored at 4 °C. Recombinant chimeric antibodies were purified with Protein A beads.
  • Murine anti-KREMEN2 antibodies were also CDR grafted or humanized using a proprietary computer-aided CDR-grafting method (Abysis Database, UCL Business) and standard molecular engineering techniques as follows. Human framework regions of the variable regions were designed based on the highest homology between the framework sequences and CDR canonical structures of human germline antibody sequences, and the framework sequences and CDRs of the relevant mouse antibodies. For the purpose of the analysis the assignment of amino acids to each of the CDR domains was done in accordance with Kabat et al. numbering. In this regard FIGS. 6G to 6J show heavy and light CDRs derived using various analytical schemes for the murine antibodies SC78.9, SC78.43, SC78.56 and SC78.59. Once the variable regions comprising murine Kabat CDRs and the selected human frameworks were designed, they were generated from synthetic gene segments (Integrated DNA Technologies). Humanized antibodies were then cloned and expressed using methods substantially as described above for chimeric antibodies.
  • VL and VH amino acid sequences of humanized antibodies hSC78.9 (SEQ ID NOS: 101 and 103), hSC78.43 (SEQ ID NOS: 105 and 107), hSC78.43 VK08 (SEQ ID NOS: 109 and 107), hSC78.56 (SEQ ID NOS: 113 and 115), and hSC78.59 (SEQ ID NOS: 117 and 119) are shown in FIG. 6D and are derived from the VL and VH sequences of the corresponding murine antibodies (e.g. hSC78.9 is derived from SC78.9).
  • hSC78.43 VK08 comprises a different light chain framework (SEQ ID NO: 109) than the humanized hSC78.43 antibody (SEQ ID NO: 105) though they share a common heavy chain.
  • SEQ ID NO: 109 The corresponding nucleic acid sequences of the VL and VH are set forth in FIG. 6E (SEQ ID NOS: 100 - 118, even numbers) where SEQ ID NO: 110 comprises a codon optimized NA sequence that expresses hSC78.43 heavy chain (SEQ ID NO: 107).
  • Table 6 shows the components used to fabricate the humanized constructs and, in some cases, that selected framework changes were introduced to maintain the favorable properties of the selected antibodies.
  • N297A mutation (EU numbering) was introduced to selected humanized antibodies to reduce the binding of antibodies to Fc receptors, which is believed to be a source of off-target toxicity.
  • This modification could be introduced in either the ssl or the wild type human IgGl constructs.
  • the N297A modification was introduced into the hSC78.9ssl and hSC78.43ssl antibodies as denoted by the MJ suffix (i.e., hSC78.9sslMJ and hSC78.43sslMJ).
  • the mutation was introduced using the Quikchange mutagenesis kit on the plasmid for heavy chain expression, and the antibody was expressed and purified using the same methods described above.
  • the exemplary humanized antibodies set forth in Table 6 demonstrate that a number of clinically compatible antibodies may be generated and derived as disclosed herein. In certain aspects of the instant invention such antibodies may be incorporated in KREMEN2 ADCs to provide compositions comprising a favorable therapeutic index.
  • FIG. 6F provides full length heavy and light chain amino acid sequences for the exemplary humanized antibody constructs set forth in Table 6. It will be appreciated that FIG. 6F is annotated to designate the location of the site-specific mutations (underlined along with flanking AAs) giving rise to a free cysteine that may be conjugated as discussed herein and the N297A position (underlined and bolded along with flanking AAs) that may be mutated to reduce Fc receptor binding.
  • Engineered human IgGl/kappa anti-KREMEN2 site-specific antibodies were constructed comprising a native light chain (LC) constant region and mutated heavy chain (HC) constant region, wherein cysteine 220 (C220) in the upper hinge region of the HC, which forms an interchain disulfide bond with cysteine 214 (C214) in the LC, was substituted with serine (C220S).
  • LC native light chain
  • HC mutated heavy chain
  • cysteine 220 cysteine 220
  • C214 cysteine 214
  • serine C220S
  • the HCs and LCs form an antibody comprising two free cysteines that are suitable for conjugation to a therapeutic agent.
  • all numbering of constant region residues is in accordance with the EU numbering scheme as set forth in Kabat et al.
  • the VH nucleic acids were cloned onto an expression vector containing the C220S mutation in the constant region of the HC.
  • the vector encoding the mutant C220S HC of hSC78.9, hSC78.43, hSC78.56 or hSC78.59 was co-transfected in CHO-S cells with a vector encoding the native IgGl kappa LC of hSC78.9, hSC78.43, hSC78.43 VK08, hSC78.56 or hSC78.59, and expressed using a mammalian transient expression system.
  • the engineered anti-KREMEN2 site-specific antibody containing the C220S mutant was termed hSC78.9ssl, hSC78.43ssl, hSC78.43ssl VK08, hSC78.56ssl or hSC78.59ssl, respectively.
  • the N297A mutation was also introduced into two of the C220S mutated heavy chains to provide hSC78.9sslMJ and hSC78.43sslMJ.
  • the amino acid sequences of the full length heavy chains (HC) of the hSC78.9ssl, hSC78.9sslMJ, hSC78.43ssl, hSC78.43sslMJ, hSC78.56ssl, hSC78.56sslMJ or hSC78.59ssl site- specific antibodies are shown in FIG. 6F (SEQ ID NOS: 133, 135, 139, 141, 147, 149 and 153, respectively).
  • the amino acid sequence of the light chains (LC) of hSC78.9ssl and hSC78.9sslMJ are identical (SEQ ID NO: 130) as are the amino acid sequences of each of the LCs of hSC78.43ssl and hSC78.43sslMJ (SEQ ID NO: 136) and each of the LCs of hSC78.56ssl and hSC78.56sslMJ (SEQ ID NO: 144) while the LCs of hSC78.43ssl VK08 or hSC78.59ssl comprise SEQ ID NOS: 142 and 150, respectively.
  • the site-specific antibodies comprise, respectively, light and heavy chains as set forth in SEQ ID NO: 130 and SEQ ID NO: 133 (hSC78.9ssl), SEQ ID NO: 130 and SEQ ID NO: 135 (hSC78.9sslMJ), SEQ ID NO: 136 and SEQ ID NO: 139 (hSC78.43ssl), SEQ ID NO: 136 and SEQ ID NO: 141 (hSC78.43sslMJ), SEQ ID NO: 142 and SEQ ID NO: 139 (hSC78.43ssl VK08), SEQ ID NO: 144 and SEQ ID NO: 147 (hSC78.56ssl), SEQ ID NO: 144 and SEQ ID NO: 149 (hSC78.56sslMJ) and SEQ ID NO: 150 and SEQ ID NO: 153 (hSC78.59ssl).
  • the engineered anti-KREMEN2 site-specific antibodies were characterized by SDS-PAGE to confirm that the correct mutants had been generated.
  • SDS-PAGE was conducted on a pre-cast 10% Tris-Glycine mini gel from Life Technologies in the presence and absence of a reducing agent such as DTT (dithiothreitol). Following electrophoresis, the gels were stained with a colloidal coomassie solution (data not shown). Under reducing conditions, two bands corresponding to the free LCs and free HCs, were observed. This pattern is typical of IgG molecules in reducing conditions. Under non-reducing conditions, the band patterns were different from native IgG molecules, indicative of the absence of a disulfide bond between the HC and LC.
  • Native and site-specific anti-KREMEN2 antibodies such as those set forth in Table 7 were conjugated to a pyrrol Strukturzodiazepine (PBD1 and PBD3 respectively) via a terminal maleimido moiety with a free sulfhydryl group to create antibody drug conjugates (i.e., ADC3 and ADC6).
  • PBD1 and PBD3 pyrrol Strukturzodiazepine
  • ADC3 and ADC6 antibody drug conjugates
  • the native anti-KREMEN2 ADCs were prepared as follows.
  • KREMEN2 antibodies were partially reduced with a pre-determined molar addition of mol tris(2- carboxyethyl)-phosphine (TCEP) per mol antibody for 90 min. at room temperature in phosphate buffered saline (PBS) with 5 mM EDTA.
  • PBS phosphate buffered saline
  • TCEP carboxyethyl-phosphine
  • the resulting partially reduced preparations were then conjugated to PBD3 (the structure of PBD3 is provided above in the current specification) via a maleimide linker for a minimum of 30 mins. at room temperature.
  • the reaction was then quenched with the addition of excess N-acetyl cysteine (NAC) compared to linker-drug using a 10 mM stock solution prepared in water.
  • NAC N-acetyl cysteine
  • the pH was adjusted to 6.0 with the addition of 0.5 M acetic acid.
  • the preparations of the ADCs were buffer exchanged into diafiltration buffer by diafiltration using a 30 kDa membrane.
  • the dialfiltered anti-KREMEN2 ADCs were then formulated with sucrose and polysorbate-20 to the target final concentration.
  • the resulting anti-KREMEN2 ADCs were analyzed for protein concentration (by measuring UV), aggregation (SEC), drug to antibody ratio (DAR) by reverse-phase HPLC (RP-HPLC) and activity ⁇ in vitro cytotoxicity).
  • the site-specific humanized anti-KREMEN2 ADCs were conjugated using a modified partial reduction process.
  • the antibodies were selectively reduced using a process comprising a stabilizing agent (e.g. L-arginine) and a mild reducing agent (e.g. glutathione) prior to conjugation with the linker-drug, followed by a diafiltration and formulation step.
  • a stabilizing agent e.g. L-arginine
  • a mild reducing agent e.g. glutathione
  • a preparation of each antibody was partially reduced in a buffer containing 1M L- arginine/5mM EDTA with a pre-determined concentration of reduced glutathione (GSH), pH 8.0 for a minimum of two hours at room temperature. All preparations were then buffer exchanged into a 20 mM Tris/3.2 mM EDTA, pH 7.0 buffer using a 30 kDa membrane (Millipore Amicon Ultra) to remove the reducing buffer. The resulting partially reduced preparations were then conjugated to DL3 and DL6 (the structure of the drug linkers are provided above in the current specification) via a maleimide linker for a minimum of 30 mins. at room temperature.
  • the reaction was then quenched with the addition of excess NAC compared to linker-drug using a 10 mM stock solution prepared in water. After a minimum quench time of 20 minutes, the pH was adjusted to 6.0 with the addition of 0.5 M acetic acid.
  • the preparations of the ADCs were buffer exchanged into diafiltration buffer by diafiltration using a 30 kDa membrane.
  • the dialfiltered anti-KREMEN2 ADC was then formulated with buffers to the target final concentration.
  • the resulting anti-KREMEN2 ADCs were analyzed for protein concentration (by measuring UV), aggregation (SEC), drug to antibody ratio (DAR) by reverse-phase HPLC (RP-HPLC) and activity ⁇ in vitro cytotoxicity).
  • FIG. 7 provides a table summarizing the aforementioned characteristics for a number of exemplary murine antibodies (upper table) and selected humanized constructs (lower table).
  • a blank cell or "N/D" indicates that the data was not generated in that instance.
  • the isotype of a representative number of antibodies was determined by RNA sequencing (see Example 7).
  • the affinity of selected humanized antibodies for human (hKREMEN2-His), cyno (cKREMEN2-His)and rat (rKREMEN2-His) was qualitatively determined from kinetics curves generated with a ForteBio RED as follows: Anti-KREMEN2 antibodies were immobilized onto anti-mouse Fc capture biosensors with a contact time of 3 min. and a flow rate of 1000 rpm. The captured antibody loading from baseline was constant at 0.3-1 units. Following antibody capture and 50 second baseline, the biosensors were dipped into a 300 nM solution of hKREMEN2-His, cKREMEN2-His or rKREMEN2-His for a 4 min. association phase followed by a 4 min.
  • the affinity of select antibodies for human, rat and cynomolgus monkeys (hKREMEN2, cKREMEN2 and rKREMEN2) protein was quantitated using surface pi asm on resonance using a Biacore T200 instrument (GE Healthcare).
  • An anti-mouse antibody capture kit was used to immobilize anti-mouse antibodies for capture of mouse anti-KREMEN2 antibodies on a CM5 biosensor chip.
  • murine antibodies at a concentration 5 ⁇ g/mL were captured on the surface with a contact time of 30 seconds and a flow rate of 20 ⁇ / ⁇ .
  • the captured antibody loading from baseline was between 80-120 response units.
  • hKREMEN2-His antigen generated in Example 4 was flowed over the surface at varying concentrations for a 60 second association phase followed by a 4 min. dissociation phase at a flow rate of 50 ⁇ / ⁇ .
  • a similar protocol was used for measuring binding affinity of humanized antibodies except that an anti -human antibody capture kit was used. The data was processed by subtracting a control non-binding antibody surface response from the specific antibody surface. The resulting response curves were used to fit a 1 : 1 Langmuir binding model and to generate an equilibrium dissociation constant using the calculated k a and k d kinetics constants the Biacore T200 Evaluation software (GE Healthcare).
  • the antibodies exhibited affinities for hKREMEN2, cKREMEN2 and rKREMEN2 in the nanomolar range (data not shown).
  • Antibodies were grouped into bins using a multiplexed competition immunoassay (Luminex
  • each anti-KREMEN2 antibody capture mAb
  • 100 ⁇ of each anti-KREMEN2 antibody (capture mAb) at a concentration of 10 ⁇ g/mL was incubated for 1 hour with magnetic beads (Luminex) that had been conjugated to an anti-mouse kappa antibody (Miller et al., 2011, PMID: 21223970).
  • the capture mAb/conjugated bead complexes were washed with PBSTA buffer (1% BSA in PBS with 0.05% Tween20) and then pooled. Following removal of residual wash buffer the beads were incubated for 1 hour with 2 ⁇ g/mL hKREMEN2-His protein, washed and then resuspended in PBSTA.
  • the pooled bead mixture was distributed into a 96 well plate, each well containing an anti-KREMEN2 antibody (detector mAb) and incubated for 1 hour with shaking. Following a wash step, anti-mouse kappa antibody (the same as that used above), conjugated to PE, was added at a concentration of 5 ⁇ g/ml to the wells and incubated for 1 hour. Beads were washed again and resuspended in PBSTA. Mean fluorescence intensity (MFI) values were measured with a Luminex MAGPIX instrument. Antibody pairing was visualized as a dendrogram of a distance matrix computed from the Pearson correlation coefficients of the antibody pairs.
  • MFI mean fluorescence intensity
  • FIG. 7 shows that the anti- KREMEN2 antibodies that were screened can be grouped into at least five unique bins, A, B, C, D, E on the hKREMEN2 protein.
  • the WNT pathway is a critical developmental and stem cell-associated signaling pathway regulating cell growth and differentiation.
  • WNT ligands bind a complex of a Frizzled (FZD) receptor and a LRP5/6 co-receptor, initiating the signaling cascade resulting in the inhibition of the protein GSK3, one result of which is the stabilization of the normally labile ⁇ -catenin protein found in the cytoplasm. Stabilized ⁇ -catenin is then able to accumulate, enter the nucleus, and form complexes with TCF/LEF transcription factors to activate genes containing binding sites for these transcriptional activators.
  • Frizzled FZD
  • LRP5/6 co-receptor LRP5/6 co-receptor
  • the canonical WNT pathway is regulated extensively at the receptor-ligand level, with multiple activating and inhibitory feedback loops comprised of various soluble decoy receptors (e.g., SFRPs and FRZB), factors that bind WNT itself or modulate its bioactivity (e.g., WIF and NOTUM), or factors that modulate FZD receptor turnover (e.g., KREMEN2, ZNRF3), and still more elaborate loops comprised of proteins that modulate the modulators (e.g., LGRs and RSPOs).
  • SFRPs and FRZB soluble decoy receptors
  • factors that bind WNT itself or modulate its bioactivity e.g., WIF and NOTUM
  • FZD receptor turnover e.g., KREMEN2, ZNRF3
  • LGRs and RSPOs proteins that modulate the modulators
  • An electrochemiluminscence ELISA assay was developed using the MSD Discovery Platform (Meso Scale Discovery, MSD) to test the ability of the anti-KREMEN2 antibodies generated in Example 7 to block binding of KREMEN2 to DKK-1.
  • MSD standard plates were coated with human KREMEN2 (R&D Systems; #1956-KR-025), at 0.5 ug mL in PBS and incubated overnight at 4 °C. After the plates were washed with PBS, 0.05% tween20 (PBST), they were blocked with 3% (w/v) BSA in PBS for 1 hour at room temperature.
  • the plates were washed in PBST and anti -DKK-1 polyclonal antibody (R&D Systems; #AF1096), which was then sulfo- tagged using an MSD® SULFO-TAG NHS Ester according to the manufacturer's protocol, was added at 0.5 ⁇ for 45 minutes. Plates were washed in PBST. MSD Read Buffer T with surfactant was diluted to IX in water and 150 ⁇ _, was added to each well. Plates were read on an MSD Sector Imager 2400.
  • KREMEN2 mRNA transcript levels associated with various tumors described in the Examples above work was undertaken to test whether KREMEN2 protein expression was also elevated in PDX tumors.
  • an electrochemiluminscence KREMEN2 sandwich ELISA assay was developed using the MSD Discovery Platform (Meso Scale Discovery).
  • PDX tumors were excised from mice and flash frozen on dry ice/ethanol.
  • Protein Extraction Buffer Biochain Institute
  • the protein lysates were normalized to 5 mg/mL and stored at -80 °C until assayed. Normal tissues were purchased from a commercial source and processed as described above.
  • KREMEN2 protein concentrations from the lysate samples were determined by interpolating the values from a standard protein concentration curve that was generated using purified recombinant KREMEN2 protein with a histidine tag.
  • the KREMEN2 protein standard curve and protein quantification assay were conducted as follows:
  • MSD 384 well standard plates were coated overnight at 4 °C with 15 ⁇ ⁇ of an anti- KREMEN2 capture antibody at 2 ⁇ g/mL in PBS. Plates were washed in PBST and blocked in 35 ⁇ ⁇ MSD 3% Blocker A solution for one hour while shaking. Plates were again washed in PBST. 10 ⁇ ⁇ of 5x diluted lysate or serially diluted recombinant KREMEN2 standard in MSD 1% Blocker A containing 10% Protein Extraction Buffer was added to the wells and incubated for two hours while shaking. Plates were again washed in PBST.
  • the anti-KREMEN2 detection antibody was then sulfo-tagged using an MSD® SULF0-TAG NHS Ester according to the manufacturer's protocol. 10 ⁇ of the tagged anti-KREMEN2 detection antibody was added to the washed plates at 0.5 ⁇ g/mL in MSD 1% Blocker A for 1 hour at room temperature while shaking. Plates were washed in PBST. MSD Read Buffer T with surfactant was diluted to IX in water and 35 ⁇ was added to each well. Plates were read on an MSD Sector Imager 2400 using an integrated software analysis program to derive KREMEN2 concentrations in lysate samples via interpolation from the standard curve. Values were then divided by total protein concentration to yield nanograms of KREMEN2 per milligram of total lysate protein.
  • each spot represents KREMEN2 protein concentrations derived from a single PDX tumor line. While each spot is derived from a single PDX line, in most cases multiple biological samples were tested from the same PDX line and values were averaged to provide the data point.
  • FIG. 9 shows that exemplary PDX tumor cell lines exhibit high KREMEN2 protein expression compared to normal tissues.
  • Normal tissues that were tested include adrenal gland, artery, colon, esophagus, gall bladder, heart, kidney, liver, lung, peripheral and sciatic nerve, pancreas, skeletal muscle, skin, small intestine, spleen, stomach, trachea, red and white blood cells and platelets, bladder, brain, breast, eye, lymph node, ovary, pituitary gland, prostate and spinal cord.
  • Immunohistochemistry was performed on PDX tumors and patient biopsies to assess the expression and location of KREMEN2 in tumor cells.
  • IHC was performed on PDX tumor cell line pellets using the anti-KREMEN2 antibody SC78.29. More particularly IHC was performed, as described below, on PDX tumor cell pellets that were formalin fixed and paraffin embedded (FFPE) as is standard in the art.
  • FFPE formalin fixed and paraffin embedded
  • FFPE slides were incubated with biotin-conjugated horse anti-mouse antibody (Vector Laboratories), diluted to 2.5 ⁇ g/ml in 3% BSA/PBS, for 30 minutes at room temperature followed by incubation in streptavidin-HRP (ABC Elite Kit; Vector Laboratories). Chromogenic detection was developed with 3,3'-diaminobenzidine (Thermo Scientific) for 5 minutes at room temperature and tissues were counterstained with Meyer's hematoxylin (IHC World), dehydrated with alcohol and immersed in xylene. Stained slides were analyzed by light microscopy. An H-score was utilized to quantify staining.
  • the H-score is a method of assessing the extent of staining by utilizing the following formula: 3X percentage of tumor cells staining at 3+ intensity + 2X percentage of tumor cells staining at 2+ intensity + IX percentage of tumor cells staining at 1+ intensity, giving a range from 0 to 300.
  • the anti-KREMEN2 antibody was able to determine whether hKREMEN2 was expressed in various lung, ovarian and breast PDX models and provide an H-score as set forth above.
  • a review of the data shows KREMEN2 protein expression is exhibited in 9/29 (31%) of lung PDX tumor samples, 5/11 (45%) of ovarian PDX tumor samples, and 10/15 (67%) of breast PDX tumor samples.
  • FIG. 11 A shows that KREMEN2 is expressed in 12/92 (13%) of ovarian serous papillary carcinoma and 12/54 (22%) of endometrioid adenocarcinoma.
  • FIG. 1 1B shows that KREMEN2 is expressed in 8/82 (10%) of breast invasive ductal carcinoma and 2/26 (8%) of invasive ductal carcinoma with diagnosed as luminal B.
  • FIG. 11C shows that KREMEN2 is expressed in 3/58 (5%) of lung adenocarcinoma, 29/187 (16%)) of lung squamous cell carcinoma and 2/12 (17%) of small cell lung cancer.
  • KREMEN2 protein is expressed on a substantial percentage of various tumors and reinforces the viability of using the determinant as a diagnostic and therapeutic target.
  • the ability of the antibodies of the invention to bind KREMEN2 expressed on PDX tumor cells was assessed as follows.
  • PDX tumors were harvested and dissociated using art-recognized enzymatic tissue digestion techniques to obtain single cell suspensions of PDX tumor cells (see, for example, U. S.P.N. 2007/0292414).
  • PDX tumor single cell suspensions were incubated with anti-mouse CD45 and H- 2K d antibodies to identify mouse cells, and anti-human EPCAM antibody to identify human cells.
  • the tumor cells were incubated with anti-human CD46 AlexaFluor-647 and CD324 PerCP Cy5.5 in order to identify tumorigenic cells (e.g., CSCs, TICs) (see U.S.P.N.s 2013/0260385, 2013/0061340 and 2013/0061342).
  • the PDX tumor cells were incubated with anti- KREMEN2 biotinylated clone SC78.40 to determine cell surface expression of KREMEN2 on PDX subpopulations.
  • the isolated cells were incubated for 30 min. with primary antibodies or with isotype matched control antibodies and washed twice in PBS/2%> FCS. The cells were incubated for 15 min.
  • FIGS. 12A - 12C show that NSCLC (FIG. 12 A), OV (FIG. 12B), and BR (FIG. 12C) PDX expressed detectable levels of KREMEN2 protein on live human tumor cells (LU85, LU306, LU409, LU296, LU450, BR163, BR164, BR165) and CSC subpopulations (solid black line; LU37, LU300, LU120, LU253, LU128, OV27, OV72MET, OV63MET, OV89) whereas NTG cells (not expressing CD324 or CD46) (dashed line) demonstrated significantly less staining with anti- KREMEN2 antibodies.
  • Fluorescence minus one (FMO) and isotype control antibodies were employed to confirm staining specificity (gray-filled).
  • a table summarizing the differential staining of anti-KREMEN2 antibodies observed on the surface of CSC and NTG cells is shown in each of FIGS. 12A - 12C, with expression enumerated as the change in geometric mean fluorescence intensity (AMFI) between the indicated anti-KREMEN2 antibody and the isotype control for the respective tumor cell subpopulations. This data further confirms the elevated expression of KREMEN2 on tumorigenic cells and the ability of antibodies of the instant invention to selectively bind to such cells.
  • AMDFI geometric mean fluorescence intensity
  • the functional CSC subpopulation in most NSCLC and OV-S PDX is ⁇ 1 : 100 cells, while phenotypic cell surface markers of cell populations that include the CSC subpopulation ranges from 1-94% of NSCLC and OV-S PDX tumors.
  • KREMEN2 is observed to be elevated in the CSC subpopulation which is only part of a bulk tumor, there is a greater expression differential between CSC populations and normal tissue expression as compared to whole PDX tumor expression compared to normal tissues. This results in a larger expression differential of KREMEN2 between CSC in tumors and normal tissue expression, pointing towards the beneficial use of anti-KREMEN2 modulators in treating tumors with expression of KREMEN2 in CSC subpopulations
  • Anti-KREMEN2 Antibodies Facilitate Delivery of Cytotoxic Agents
  • an in vitro cell killing assay was performed using selected anti-KREMEN2 antibodies and saporin linked to a secondary anti-mouse antibody FAB fragment.
  • Saporin is a plant toxin that deactivates ribosomes, thereby inhibiting protein synthesis and resulting in the death of the cell. Saporin is only cytotoxic inside the cell where it has access to ribosomes, but is unable to internalize on its own.
  • saporin- mediated cellular cytotoxicity in these assays is indicative of the ability of the anti-mouse FAB- Saporin construct to internalize upon binding and internalization of the associated murine or humanized anti-KREMEN2 antibodies into the target cells.
  • Single cell suspensions of HEK293T cells overexpressing hKREMEN2 were plated at 500 cells per well into BD Tissue Culture plates (BD Biosciences).
  • anti-KREMEN2 murine antibodies at a concentration of 100 pM effectively killed HEK293T cells overexpressing hKREMEN2 with varying efficacy whereas the mouse IgG2b isotype control antibody (mIgG2b) at the same concentration did not (data not shown).
  • the anti-KREMEN2 humanized antibodies (hSC78.9, hSC78.43, hSC78.56, and hSC78.59) and corresponding chimeric antibody control effectively killed HEK293T cells overexpressing KREMEN2 (FIG. 13).
  • the humanized antibodies showed comparable efficacy to the chimeric antibody (in the case of hSC78.9, hSC78.56 and hSC78.59) from which they were derived (hSC78.43 chimeric antibody did not bind KREMEN2 and was not available as a control).
  • Example 15 above demonstrates that expression of KREMEN2 may be associated with phenotypic tumor initiating cells in NSCLC and OV-S PDX.
  • LU205 LU-AD
  • OV89 OV-S
  • High and low/negative live, human tumor cells expressing KREMEN2 were isolated using fluorescent-activated cell sorting with BD FACS ARIA II flow cytometer. Isolated tumor cells were separated into Eppendorf tubes containing PBS/2% FCS. SC78-positive and SC78-negative isolated tumor cells were injected subcutaneously into 5 recipient mice each at an inoculum of 50 cells per recipient mouse for LU205 and 180 cells per recipient mouse for OV89.
  • Positive tumor growth is defined as growth of a tumor exceeding 200 mm3.
  • 5/5 mice injected with KREMEN2 -positive tumor cells grew tumors, while only 3/5 mice injected with KREMEN2-negative tumor cells grew tumors (FIG. 14A).
  • 5/5 mice injected with KREMEN2-positive tumor cells grew tumors, while 4/10 mice injected with KREMEN2 -negative tumor cells grew tumors (FIG. 14B).
  • BR patient derived xenograft
  • PDX patient derived xenograft
  • Targeted re-sequencing of gDNA may be performed using gDNA from each BR, NSCLC, OV PDX cell line to generate a library with the Ion AmpliSeq Library Kit 2.0 and a custom panel of AmpliSeq primers (Life Technologies) encompassing over 3000 amplicons of up to 250 bp, and covering coding and non-coding regions of multiple genes.
  • Each sample may be ligated to an Ion Xpress Barcode Adapter (Life Technologies) to allow pooling of multiple samples for each sequencing run. Sequencing can then be performed on an Ion Torrent PGM machine (Life Technologies), and data analysis can be carried out to identify variations in sequence of tumor- related genes that lead to changes at the gDNA, mRNA transcript and protein levels.
  • the mutational status of tumor-related genes can be used as a surrogate biomarker (as described in more detail below) to determine whether there is a correlation between various genetic mutations and the expression of KREMEN2, which may be informative of the effectiveness of treating a tumor (e.g. BR, NSCLC, OV-S) with the anti- KREMEN2 antibodies or ADCs of the invention.
  • a tumor e.g. BR, NSCLC, OV-S
  • the mutational status of the BR, NSCLC, and OV- related genes can be used to determine whether there is a correlation between genetic mutations and the response to treatment with the anti- KREMEN2antibodies or ADCs of the invention.
  • the mutational status of the BR, NSCLC, or OV-S-related genes can be used to determine effective combination therapies.
  • BR, NSCLC, and OV-S PDX tumors were evaluated for targeted re-sequencing of major cancer driver genes using Ion Ampliseq and Ion Torrent PGM technologies described above.
  • BR, NSCLC, and OV-S tumors with high and low in expression of KREMEN2 were determined by microarray and used to correlate mutation data with KREMEN2 expression.
  • a coding mutation is defined by any non-synonymous alteration occurring in the protein-coding region of the sequenced gene, including missense non-synonymous, insertions or deletions of codons, amplicon deletions or amplicon amplifications, nonsense non-synonymous, frameshift, and mutations that lead to altered splice-site variants of the gene sequenced.
  • the results of the analysis are set forth in Tables 8 and 9 below and in FIGS. 15A and 15B appended hereto.
  • NSCLC PDX tumors highly expressing KREMEN2 were found to associate with PDX lines carrying mutational variation (e.g. non-synonymous coding-mutations, deleted and gained exons) in
  • NSCLC PDX tumors lines containing a coding mutation or deletion in FGFR2 were significantly associated with a 3.6-fold lower expression of
  • KREMEN2A deletions of GRIN2A exons for NSCLC PDX datasets may be due to the relative infrequency of this mutation in the PDX dataset or to a low frequency tumor cell clone carrying the mutation within a NSCLC PDX tumor.
  • the ADCs comprise humanized site-specific anti-KREMEN2 antibodies comprising an N297A mutation to reduce non-specific Fc-mediated binding conjugated to PBDl using a cleavable linker (i.e. ADC6).
  • NOD/SCID mice bearing PDX tumors were randomized when tumor volume was 100-250 mm3 into groups of at least 5 animals and treated with a single dose of vehicle or 0.4 mg/kg humanized IgGl isotype control ADC, hSC78.43ssl PBDl, hSC78.43sslMJ PBDl or hSC78.56sslMJ PBDl by intraperitoneal injection. Tumor volumes were measured and recorded weekly after treatment, and animals were sacrificed when tumor volumes exceeded 1000 mm3 or after 130 days of study duration. The results are graphically shown in FIG. 16.
  • ovarian O VI 19MET-b earing mice treated with a single dose of hSC78.43ssl PBDl exhibited durable, curative responses for at least 128 days after dosing, whereas all animals treated with vehicle or human IgGl LD6.23 ADC control recurred.
  • LDA in vivo limiting dilution analysis
  • NOD/SCID animals bearing LU450 lung squamous cell carcinoma PDX tumors were randomized and treated as above with vehicle, or 0.1 mg/kg of either humanized IgGl isotype ADC control, hSC78.43sslMJ PBD3 or hSC78.56sslMJ PBD3 (i.e., both ADC3).
  • Isotype control ADC (3002, 1002, 3002, 102 cells per mouse),
  • hSC78.43sslMJ PBD3 (3003, 1003, 303, 103 cells per mouse)
  • hSC78.56sslMJ PBD3 (3004, 1004, 304, 104 cells per mouse)
  • Tumor initiating (TIC) frequency was determined by Poisson distribution analysis using L-Calc (STEMCELL Technologies).
  • Vehicle and isotype control ADC treated animals grew tumors in all surviving animals in each dilution group assessed, projecting TIC frequencies of at least 23.3 and 22.7 per 1000 cells, respectively (FIG. 17).
  • no tumors grew in any inoculum level of hSC78.43sslMJ PBD3 or hSC78.56sslMJ PBD3 treated animals, projecting TIC frequencies of less than 0.03 and 0.02 per 1000 cells, respectively.

Abstract

Provided are novel anti-KREMEN2 antibodies and antibody drug conjugates, and methods of using such anti-KREMEN2 antibodies and antibody drug conjugates to treat cancer.

Description

NOVEL ANTI-KREMEN2 ANTIBODIES AND METHODS OF USE
CROSS REFERENCED APPLICATIONS
This application claims the benefit of U.S. Provisional Application No. 62/432,050 filed on December 9, 2016 and U.S. Provisional Application No. 62/593,901 filed on December 2, 2017, each of which is incorporated herein by reference in its entirety.
SEQUENCE LISTING
This application contains a sequence listing which has been submitted in ASCII format via EFS-Web and is hereby incorporated by reference in its entirety. Said ASCII copy, created on December 7, 2017, is named S69697_1440WO_SC7801WOOl_ST25.txt and is 139 KB (143,277 bytes) in size.
FIELD OF THE INVENTION
This application generally relates to anti-KREMEN2 antibodies or immunoreactive fragments or derivatives thereof, including antibody drug conjugates, and compositions comprising the same for the treatment, diagnosis or prophylaxis of cancer and any recurrence or metastasis thereof. Selected embodiments of the invention provide for the use of such anti-KREMEN2 antibodies or antibody drug conjugates for the treatment of cancer comprising a reduction in tumorigenic cell frequency.
BACKGROUND OF THE INVENTION
Differentiation and proliferation of stem cells and progenitor cells are normal ongoing processes that act in concert to support tissue growth during organogenesis, cell repair and cell replacement. The system is tightly regulated to ensure that only appropriate signals are generated based on the needs of the organism. Cell proliferation and differentiation normally occur only as necessary for the replacement of damaged or dying cells or for growth. However, disruption of these processes can be triggered by many factors including the under- or overabundance of various signaling chemicals, the presence of altered microenvironments, genetic mutations or a combination thereof. Disruption of normal cellular proliferation and/or differentiation can lead to various disorders including proliferative diseases such as cancer.
Conventional therapeutic treatments for cancer include chemotherapy, radiotherapy and immunotherapy. Often these treatments are ineffective and surgical resection may not provide a viable clinical alternative. Limitations in the current standard of care are particularly evident in those cases where patients undergo first line treatments and subsequently relapse. In such cases refractory tumors, often aggressive and incurable, frequently arise. The overall survival rates for many tumors have remained largely unchanged over the years due, at least in part, to the failure of existing therapies to prevent relapse, tumor recurrence and metastasis. There remains therefore a great need to develop more targeted and potent therapies for proliferative disorders. The current invention addresses this need.
SUMMARY OF THE INVENTION
In a broad aspect the present invention provides novel antibodies, and corresponding antibody drug or diagnostic conjugates (ADCs), or compositions thereof, which specifically bind to human KREMEN2 determinants. In certain embodiments the KREMEN2 determinant is a KREMEN2 protein expressed on tumor cells while in other embodiments the KREMEN2 determinant is expressed on tumor initiating cells. In other embodiments the antibodies of the invention bind to a KREMEN2 protein and compete for binding with an antibody that binds to an epitope on human KREMEN2 protein.
In selected embodiments the invention comprises an antibody that comprises or competes for binding with an isolated antibody that binds to a cell expressing human KREMEN2 having SEQ ID NO: 1, wherein the isolated antibody comprises: (1) a light chain variable region (VL) of SEQ ID NO: 21 and a heavy chain variable region (VH) of SEQ ID NO: 23; or (2) a VL of SEQ ID NO: 25 and a VH of SEQ ID NO: 27; or (3) a VL of SEQ ID NO: 29 and a VH of SEQ ID NO: 31; or (4) a VL of SEQ ID NO: 33 and a VH of SEQ ID NO: 35; or (5) a VL of SEQ ID NO: 37 and a VH of SEQ ID NO: 39; or (6) a VL of SEQ ID NO: 41 and a VH of SEQ ID NO: 43; or (7) a VL of SEQ ID NO: 45 and a VH of SEQ ID NO: 47; or (8) a VL of SEQ ID NO: 49 and a VH of SEQ ID NO: 51; or (9) a VL of SEQ ID NO: 53 and a VH of SEQ ID NO: 55; or (10) a VL of SEQ ID NO: 57 and a VH of SEQ ID NO: 59; or (11) a VL of SEQ ID NO: 61 and a VH of SEQ ID NO: 63; or (12) a VL of SEQ ID NO: 65 and a VH of SEQ ID NO: 67; or (13) a VL of SEQ ID NO: 69 and a VH of SEQ ID NO: 71; or (14) a VL of SEQ ID NO: 73 and a VH of SEQ ID NO: 75; or (15) a VL of SEQ ID NO: 77 and a VH of SEQ ID NO: 79; or (16) a VL of SEQ ID NO: 49 and a VH of SEQ ID NO: 81.
In a further aspect, the invention comprises an antibody that binds to KREMEN2 comprising a light chain variable region and a heavy chain variable region, wherein the light chain variable region has three CDRs of a light chain variable region set forth as SEQ ID NO: 21, SEQ ID NO: 25, SEQ ID NO: 29, SEQ ID NO: 33, SEQ ID NO: 37, SEQ ID NO: 41, SEQ ID NO: 45, SEQ ID NO: 49, SEQ ID NO: 53, SEQ ID NO: 57, SEQ ID NO: 61, SEQ ID NO: 65, SEQ ID NO: 69, SEQ ID NO: 73 and SEQ ID NO: 77 and the heavy chain variable region has three CDRs of a heavy chain variable region set forth as SEQ ID NO: 23, SEQ ID NO: 27, SEQ ID NO: 31, SEQ ID NO: 35, SEQ ID NO: 39, SEQ ID NO: 43, SEQ ID NO: 47, SEQ ID NO: 51, SEQ ID NO: 55, SEQ ID NO:59, SEQ ID NO: 63, SEQ ID NO: 67, SEQ ID NO: 71, SEQ ID NO: 75, SEQ ID NO: 77 and SEQ ID NO: 81.
In other aspects the invention comprises a humanized antibody wherein the humanized antibody comprises a light chain variable region (VL) of SEQ ID NO: 101 and a heavy chain variable region (VH) of SEQ ID NO: 103; or a VL of SEQ ID NO: 105 and a VH of SEQ ID NO: 107; or a VL of SEQ ID NO: 109 and a VH of SEQ ID NO: 107; or a VL of SEQ ID NO: 113 and a VH of SEQ ID NO: 115; or a VL of SEQ ID NO: 117 and a VH of SEQ ID NO: 119. In certain embodiments these humanized antibodies will comprise site-specific antibodies. In other embodiments such antibodies will comprise an N297A mutation (MJ mutation).
In other selected embodiments the invention will comprise a humanized antibody wherein the antibody comprises a light chain of SEQ ID NO: 130 and a heavy chain of SEQ ID NO: 131; or a light chain of SEQ ID NO: 130 and a heavy chain of SEQ ID NO: 133; or a light chain of SEQ ID NO: 130 and a heavy chain of SEQ ID NO: 135; or a light chain of SEQ ID NO: 136 and a heavy chain of SEQ ID NO: 137; or a light chain of SEQ ID NO: 136 and a heavy chain of SEQ ID NO: 139; or a light chain of SEQ ID NO: 136 and a heavy chain of SEQ ID NO : 141; or a light chain of SEQ ID NO: 142 and a heavy chain of SEQ ID NO: 137; or a light chain of SEQ ID NO: 142 and a heavy chain of SEQ ID NO: 139; or a light chain of SEQ ID NO: 144 and a heavy chain of SEQ ID NO: 145; or a light chain of SEQ ID NO: 144 and a heavy chain of SEQ ID NO: 147; or a light chain of SEQ ID NO: 144 and a heavy chain of SEQ ID NO: 149; or a light chain of SEQ ID NO: 150 and a heavy chain of SEQ ID NO: 151; or a light chain of SEQ ID NO: 150 and a heavy chain of SEQ ID NO: 153. In some aspects of the invention the antibody comprises a chimeric, CDR grafted, humanized or human antibody or an immunoreactive fragment thereof. In other aspects of the invention the antibody, preferably comprising all or part of the aforementioned sequences, is an internalizing antibody. In yet other embodiments the antibodies will comprise site-specific antibodies. In other selected embodiments the invention comprises antibody drug conjugates incorporating any of the aforementioned antibodies.
In certain aspects the invention comprises a nucleic acid encoding an anti-KREMEN2 antibody of the invention or a fragment thereof. In other embodiments the invention comprises a vector comprising one or more of the above described nucleic acids or a host cell comprising said vector.
As alluded to above the present invention also provides anti-KREMEN2 antibody drug conjugates where antibodies as disclosed herein are conjugated to a payload. In some aspects, the antibody drug conjugate, or a pharmaceutically acceptable salt thereof, comprises a monoclonal antibody conjugated, linked, or otherwise associated with a cytotoxic agent, wherein the antibody binds to a human KREMEN2 protein. In certain aspects the present invention comprises ADCs that immunopreferentially associate or bind to hKREMEN2. Compatible anti-KREMEN2 antibody drug conjugates (ADCs) of the invention may generally comprise the formula:
Ab-[L-D]n or a pharmaceutically acceptable salt thereof wherein
a) Ab comprises an anti-KREMEN2 antibody;
b) L comprises an optional linker;
c) D comprises a drug; and
d) n is an integer from about 1 to about 20. In one aspect the ADCs of the invention comprise an anti-KREMEN2 antibody such as those described above or an immunoreactive fragment thereof. In other embodiments the ADCs of the invention comprise a cytotoxic compound selected from radioisotopes, calicheamicins, pyrrolobenzodiazepines, benzodiazepine derivatives, auristatins, duocarmycins, maytansinoids or an additional therapeutic moiety described herein. In certain preferred embodiments the disclosed ADC s will compri se a PBD . Further provided are pharmaceutical compositions comprising an anti-KREMEN2 ADC as disclosed herein. In certain embodiments the compositions will comprise a selected drug-antibody ratio (DAR) of greater than about 50%, greater than about 60%, greater than about 70%, greater than about 80%, greater than about 90% or even greater than about 95%. In some embodiments the selected DAR will be two, while in other embodiments the selected DAR will be four and in other embodiments the selected DAR will be six and in yet other embodiments the selected DAR will be eight.
Another aspect of the invention is a method of treating cancer comprising administering a pharmaceutical composition such as those described herein to a subject in need thereof. In certain aspects the cancer comprises a hematologic malignancy such as, for example, acute myeloid leukemia or diffuse large B-cell lymphoma. In other aspects the subject will be suffering from a solid tumor. With regard to such embodiments the cancer is preferably selected from the group consisting of adrenal cancer, liver cancer, kidney cancer, bladder cancer, breast cancer, gastric cancer, ovarian cancer, cervical cancer, uterine cancer, esophageal cancer, colorectal cancer, prostate cancer, pancreatic cancer, lung cancer (both small cell and non-small cell), thyroid cancer and glioblastoma. In certain embodiments the subject will be suffering from squamous cell carcinoma of the lung (or squamous cell lung cancer). In other embodiments the subject will be suffering from breast cancer and, in certain embodiments, luminal B breast cancer. Further, in selected embodiments the method of treating cancer described above comprises administering to the subject at least one additional therapeutic moiety besides the anti-KREMEN2 ADCs of the invention.
In still another embodiment the invention comprises a method of reducing tumor initiating cells in a tumor cell population, wherein the method comprises contacting (e.g. in vitro or in vivo) a tumor initiating cell population with an ADCs or antibodies as described herein whereby the frequency of the tumor initiating cells is reduced.
In one aspect, the invention comprises a method of delivering a cytotoxin to a cell comprising contacting the cell with any of the above described ADCs.
In another aspect, the invention comprises a method of detecting, diagnosing, or monitoring cancer (e.g., breast cancer or squamous cell lung cancer) in a subject, the method comprising the steps of contacting (e.g. in vitro or in vivo) tumor cells with an KREMEN2 detection agent and detecting the KREMEN2 agent associated with the tumor cells. In selected embodiments the detection agent will comprise an anti-KREMEN2 antibody or a nucleic acid probe that associates with a KREMEN2 genotypic determinant. In such aspects of the invention the anti-KREMEN2 antibody may comprise SC78.29 (VL of SEQ ID NO: 53 and VH of SEQ ID NO: 55) or an immunoreactive fragment thereof. In related embodiments the diagnostic method will comprise immunohistochemistry (IHC) or in situ hybridization (ISH). Those of skill in the art will further appreciate that such KREMEN2 detection agents may be labeled or associated with effectors, markers or reporters as disclosed below and detected using any one of a number of standard in vivo imaging techniques (e.g., MRI, CAT scan, PET scan, etc.).
In a similar vein the present invention also provides kits or devices and associated methods that are useful in the diagnosis, monitoring or treatment of KREMEN2 associated disorders such as cancer. To this end the present invention preferably provides an article of manufacture useful for detecting, diagnosing or treating KREMEN2 associated disorders comprising a receptacle containing a KREMEN2 ADC and instructional materials for using said KREMEN2 ADC to treat, monitor or diagnose the KREMEN2 associated disorder or provide a dosing regimen for the same. Also provided are kits for delivery of a cytotoxin to a cell. In selected embodiments the devices and associated methods will comprise the step of contacting at least one circulating tumor cell. In other embodiments the disclosed kits will comprise instructions, labels, inserts, readers or the like indicating that the kit or device is used for the diagnosis, monitoring or treatment of a KREMEN2 associated cancer or provide a dosing regimen for the same.
Yet other aspects relate to methods of determining cytotoxicity of an anti-KREMEN2 antibody drug conjugate, or a pharmaceutically acceptable salt thereof. In some aspects, such methods comprise the step of contacting a cancer cell with the antibody drug conjugate {e.g., an antibody drug conjugate comprising an anti-KREMEN2 antibody conjugated, linked or otherwise associated with a cytotoxic agent). Some aspects further comprise the step of determining killing of the cancer cell.
The foregoing is a summary and thus contains, by necessity, simplifications, generalizations, and omissions of detail; consequently, those skilled in the art will appreciate that the summary is illustrative only and is not intended to be in any way limiting. Other aspects, features, and advantages of the methods, compositions and/or devices and/or other subject matter described herein will become apparent in the teachings set forth herein. The summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description.
BRIEF DESCRIPTION OF THE FIGURES FIG. 1 provides an annotated amino acid sequence of the protein KREMEN2.
FIG. 2 shows expression levels of KREMEN2 as measured using whole transcriptome
(Ulumina) sequencing of RNA derived from patient derived xenograft (PDX) cancer stem cells
(CSC) and non-tumorigenic (NTG) cells as well as normal tissue;
FIG. 3 depicts the relative expression levels of KREMEN2 transcripts as measured by qRT- PCR in RNA samples isolated from normal tissue and from a variety of PDX tumors;
FIG. 4 shows the normalized intensity value of KREMEN2 transcript expression measured by microarray hybridization in normal tissues and a variety of PDX cell lines;
FIG. 5 shows expression of KREMEN2 transcripts in normal tissues and primary tumors from
The Cancer Genome Atlas (TCGA), a publicly available dataset;
FIGS. 6A - 6J provide annotated amino acid and nucleic acid sequences of murine anti-
KREMEN2 antibodies wherein FIGS. 6 A and 6B show contiguous amino acid sequences of the light chain (FIG. 6A) and heavy chain (FIG. 6B) variable regions (SEQ ID NOS: 21 -81, odd numbers) of exemplary murine anti-KREMEN2 antibodies, FIG. 6C shows nucleic acid sequences encoding the aforementioned light and heavy chain variable regions (SEQ ID NOS: 20-80, even numbers), FIGS. 6D and 6E depict, respectively, amino acid sequences and nucleic acid sequences of humanized VL and VH domains of anti-KREMEN2 antibodies, FIG. 6F shows amino acid sequences of full length heavy and light chain constructs, and FIGS. 6G - 6 J depict the CDRs of the light and heavy chain variable regions of the SC78.9, SC78.43, SC78.56 and SC78.59 murine antibodies as determined using Kabat, Chothia, ABM and Contact methodology;
FIG. 7 provides, in a tabular form, isotype, binning, affinity and cross reactivity characteristics of exemplary anti-KREMEN2 antibodies;
FIG. 8 shows that selected anti-KREMEN2 antibodies may interfere with the binding of
KREMEN2 to its ligand DKK1;
FIG. 9 demonstrates that the KREMEN2 protein is expressed on the surface of a number of PDX tumor cell lines.
FIG. 10 shows expression levels of KREMEN2 on various lung, ovarian and breast PDX tumor cell lines as determined by immunohistochemistry using SC78.29 antibody;
FIGS. 11A -l lC demonstrate that the KREMEN2 protein is expressed on primary patient ovarian (FIG. 11 A), lung (FIG. 11B), and breast (FIG. 11C) tumors as determined by immunohistochemistry using SC78.29 antibody;
FIGS. 12A - 12C show KREMEN2 protein expression on the surface of NSCLC (FIG. 12A), Ovarian (FIG. 12B), or breast (FIG. 12C), PDX CSC subpopulations (black line) and NTG subpopulations (dotted line) compared to an isotype-control stained population (solid gray), along with tables summarizing the AMFI for these populations;
FIG. 13 demonstrates that exemplary KREMEN2 antibodies of the instant invention effectively mediate the delivery and internalization of cytotoxic agents to KREMEN2+ cells;
FIGS. 14A and 14B establish that KREMEN2 determinants are associated with tumor initiating cells in exemplary lung (FIG. 14A) and ovarian (FIG. 14B) PDX cell lines as shown by using FACS generated KREMEN2+ tumorigenic cell subpopulations to recapitulate heterogeneous tumors when implanted in immunodeficient mice;
FIGS. 15A and 15B demonstrate that certain somatic mutations predict the expression of KREMEN2 in NSCLC PDX tumor cell lines (FIG. 15 A) and that PTCH 1 mutations predict the expression of KREMEN2 in various PDX tumor cell lines (FIG. 15B);
FIG. 16 graphically illustrates that KREMEN2 antibody drug conjugates produce durable remissions in lung squamous cell carcinoma, breast, and ovarian cancer PDX-bearing mice; and
FIG. 17 shows that that KREMEN2 antibody drug conjugates effectively deplete cancer stem cell populations in lung squamous cell carcinoma PDX tumors.
DETAILED DESCRIPTION OF THE INVENTION
The invention may be embodied in many different forms. Disclosed herein are non-limiting, illustrative embodiments of the invention that exemplify the principles thereof. Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described. For the purposes of the instant disclosure all identifying sequence accession numbers may be found in the NCBI Reference Sequence (RefSeq) database and/or the
NCBI GenBank® archival sequence database unless otherwise noted.
It has surprisingly been found that KREMEN2 phenotypic determinants are clinically associated with various proliferative disorders, including neoplasia, and that KREMEN2 protein and variants or isoforms thereof provide useful tumor markers which may be exploited in the treatment of related diseases. In this regard the present invention provides antibody drug conjugates comprising an engineered anti-KREMEN2 antibody targeting agent and cytotoxic payload. As discussed in more detail below and set forth in the appended Examples, the disclosed anti- KREMEN2 ADCs are particularly effective at eliminating tumorigenic cells and therefore useful for the treatment and prophylaxis of certain proliferative disorders or the progression or recurrence thereof. In addition, the disclosed ADC compositions may exhibit a relatively high DAR=2 percentage and unexpected stability that can provide for an improved therapeutic index when compared with conventional ADC compositions comprising the same components.
Moreover, it has been found that KREMEN2 markers or determinants such as cell surface
KREMEN2 protein are therapeutically associated with cancer stem cells (also known as tumor perpetuating cells) and may be effectively exploited to eliminate or silence the same. The ability to selectively reduce or eliminate cancer stem cells through the use of anti-KREMEN2 conjugates as disclosed herein is surprising in that such cells are known to generally be resistant to many conventional treatments. That is, the effectiveness of traditional, as well as more recent targeted treatment methods, is often limited by the existence and/or emergence of resistant cancer stem cells that are capable of perpetuating tumor growth even in face of these diverse treatment methods. Further, determinants associated with cancer stem cells often make poor therapeutic targets due to low or inconsistent expression, failure to remain associated with the tumorigenic cell or failure to present at the cell surface. In sharp contrast to the teachings of the prior art, the instantly disclosed ADCs and methods effectively overcome this inherent resistance and to specifically eliminate, deplete, silence or promote the differentiation of such cancer stem cells thereby negating their ability to sustain or re-induce the underlying tumor growth.
As such KREMEN2 conjugates such as those disclosed herein may advantageously be used in the treatment and/or prevention of selected proliferative (e.g., neoplastic) disorders or progression or recurrence thereof. It will be appreciated that, while preferred embodiments of the invention will be discussed extensively below, particularly in terms of particular domains, regions or epitopes or in the context of cancer stem cells or tumors comprising neuroendocrine features and their interactions with the disclosed antibody drug conjugates, those skilled in the art will appreciate that the scope of the instant invention is not limited by such exemplary embodiments. Rather, the most expansive embodiments of the present invention and the appended claims are broadly and expressly directed to anti-KREMEN2 antibodies and conjugates, including those disclosed herein, and their use in the treatment and/or prevention of a variety of KREMEN2 associated or mediated disorders, including neoplastic or cell proliferative disorders, regardless of any particular mechanism of action or specifically targeted tumor, cellular or molecular component. I. KREMEN2 Physiology
Kringle domain-containing transmembrane protein 2 (KREMEN2, also known as KRM2, Kringle-containing protein marking the eye and nose) is a 49 kDa protein that serves as a high- affinity receptor for the Dickkopf homolog 1 protein, DKKl . KREMEN2 co-operates with DKKl to form a ternary complex with LRP6, a co-receptor for Wnt proteins, and this KREMEN2:DKK1 :LRP6 complex is rapidly endocytosed to remove LRP6 from the plasma membrane, modulating Wnt signaling (PMID: 12050670). Representative KREMEN2 protein orthologs include, but are not limited to, human ( P_757384), chimpanzee (XP_009428528), cynomolgus monkey (XP_005591068), rat ( P_001099237) and mouse ( P_082692). In humans, the KREMEN2 gene consists of 8 exons spanning approximately 4 kBp at chromosome 16pl3.3. Transcription of the human ASCL1 locus yields multiple alternative spliced mRNAs encoding different sized proteins including the canonical reference isoform which is encoded by a 2068 nucleotide transcript ( M_172229) yielding a 462 amino acid protein (NP_757384, SEQ ID NO: 1, FIG. 1). This protein is comprised of a signal peptide, followed by an extracellular domain consisting of a Kringle domain, a WSC domain (a putative carbohydrate binding domain) and a CUB domain, followed by a transmembrane spanning domain and a cytoplasmic tail. Mutagenesis studies have suggested that each of the extracellular domains is required for functional interaction with the DKKl protein and subsequent inhibition of the Wnt signal, as is the presence of a membrane anchoring domain, whereas the cytoplasmic tail is not required for function (PMID: 120506705). Additional splice variants are reported at NCBI, UniProt and Ensemble, the function and biological relevance of which are unclear.
KREMEN2 is a cell surface receptor with shown to have high affinity for DKKl, DKK2, and DKK4 (PMID: 120506705, PMID: 12527209). KREMEN2 complexes with DKKl and LRP6 to interfere with LRP6 interactions with Frizzled and extracellular Wnt proteins, abrogating intracellular Wnt-mediated Wnt/p-catenin signaling and further downregulating the expression of surface LRP6 (PMID: 20543981). Overexpression and knockdown experiments involving KREMEN2 suggest that KREMEN2 is involved in anterior posterior patterning via Wnt signaling inhibition in Xenopus embryogenesis (PMID: 12421700). Regarding cancer, heightened KREMEN2 expression has been reported on bone stromal cells in multiple myeloma cell lines and in patients, while secreted DKK1 may participate in a DKK-1 :KREMEN2 complex that acts on stromal cells to restructure the bone marrow microenvironment (PMID: 20846389). qRT-PCR and immunohistochemistry experiments with cell lines and esophageal, colorectal, pancreatic, gastric and other gastrointestinal tumors demonstrated some expression of KREMEN2 in both tumor and normal adjacent tissue, but KREMEN2 was not consistently expressed among tumors in these indications (PMID: 1846165). Microarray analysis of colorectal cell lines treated in vitro and in vivo with lemalidomide, an FDA-approved immunomodulatory therapeutic, demonstrated that KREMEN2 is upregulated in vitro, but not in vivo, and that discordance in these results may be due to immune cell infiltration and inflammatory responses of the tumor microenvironment in vivo (PMID: 19597962). In pancreatic cancer cell lines, negative regulation of Wnt/p-catenin signaling by antisense microRNA MiR-29a led to an increase in the expression of KREMEN2, which sensitized tumor cells to gemcitabine treatment (PMID: 23900458). The inventors are not aware of any reports in the literature that demonstrating expression of KREMEN2 in non-small cell lung, breast, or ovarian cancers.
II. Cancer Stem Cells
According to current models, a tumor comprises non-tumorigenic cells and tumorigenic cells. Non-tumorigenic cells do not have the capacity to self-renew and are incapable of reproducibly forming tumors, even when transplanted into immunocompromised mice in excess cell numbers. Tumorigenic cells, also referred to herein as "tumor initiating cells" (TICs), which typically make up a fraction of the tumor's cell population of 0.01-10% , have the ability to form tumors. For hematopoietic malignancies TICs can be very rare ranging from 1 : 104 to 1 : 107 in particular in Acute Myeloid Malignancies (AML) or very abundant for example in lymphoma of the B cell lineage. Tumorigenic cells encompass both tumor perpetuating cells (TPCs), referred to interchangeably as cancer stem cells (CSCs), and tumor progenitor cells (TProgs).
CSCs, like normal stem cells that support cellular hierarchies in normal tissue, are able to self- replicate indefinitely while maintaining the capacity for multilineage differentiation. In this regard CSCs are able to generate both tumorigenic progeny and non-tumorigenic progeny and are able to completely recapitulate the heterogeneous cellular composition of the parental tumor as demonstrated by serial isolation and transplantation of low numbers of isolated CSCs into immunocompromised mice. Evidence indicates that unless these "seed cells" are eliminated tumors are much more likely to metastasize or reoccur leading to relapse and ultimate progression of the disease.
TProgs, like CSCs have the ability to fuel tumor growth in a primary transplant. However, unlike CSCs, they are not able to recapitulate the cellular heterogeneity of the parental tumor and are less efficient at reinitiating tumorigenesis in subsequent transplants because TProgs are typically only capable of a finite number of cell divisions as demonstrated by serial transplantation of low numbers of highly purified TProg into immunocompromised mice. TProgs may further be divided into early TProgs and late TProgs, which may be distinguished by phenotype (e.g., cell surface markers) and their different capacities to recapitulate tumor cell architecture. While neither can recapitulate a tumor to the same extent as CSCs, early TProgs have a greater capacity to recapitulate the parental tumor's characteristics than late TProgs. Notwithstanding the foregoing distinctions, it has been shown that some TProg populations can, on rare occasion, gain self-renewal capabilities normally attributed to CSCs and can themselves become CSCs.
CSCs exhibit higher tumorigenicity and are often relatively more quiescent than: (i) TProgs (both early and late TProgs); and (ii) non-tumorigenic cells such as terminally differentiated tumor cells and tumor-infiltrating cells, for example, fibroblasts/stroma, endothelial and hematopoietic cells that may be derived from CSCs and typically comprise the bulk of a tumor. Given that conventional therapies and regimens have, in large part, been designed to debulk tumors and attack rapidly proliferating cells, CSCs are therefore more resistant to conventional therapies and regimens than the faster proliferating TProgs and other bulk tumor cell populations such as non-tumorigenic cells. Other characteristics that may make CSCs relatively chemoresistant to conventional therapies are increased expression of multi-drug resistance transporters, enhanced DNA repair mechanisms and anti-apoptotic gene expression. Such CSC properties have been implicated in the failure of standard treatment regimens to provide a lasting response in patients with advanced stage neoplasia as standard chemotherapy does not effectively target the CSCs that actually fuel continued tumor growth and recurrence.
It has surprisingly been discovered that KREMEN2 expression is associated with various tumorigenic cell subpopulations in a manner which renders them susceptible to treatment as set forth herein. The invention provides anti- KREMEN2 antibodies that may be particularly useful for targeting tumorigenic cells and may be used to silence, sensitize, neutralize, reduce the frequency, block, abrogate, interfere with, decrease, hinder, restrain, control, deplete, moderate, mediate, diminish, reprogram, eliminate, kill or otherwise inhibit (collectively, "inhibit") tumorigenic cells, thereby facilitating the treatment, management and/or prevention of proliferative disorders (e.g. cancer). Advantageously, the anti- KREMEN2 antibodies of the invention may be selected so they preferably reduce the frequency or tumorigenicity of tumorigenic cells upon administration to a subject regardless of the form of the KREMEN2 determinant (e.g., phenotypic or genotypic). The reduction in tumorigenic cell frequency may occur as a result of (i) inhibition or eradication of tumorigenic cells; (ii) controlling the growth, expansion or recurrence of tumorigenic cells; (iii) interrupting the initiation, propagation, maintenance, or proliferation of tumorigenic cells; or (iv) by otherwise hindering the survival, regeneration and/or metastasis of the tumorigenic cells. In some embodiments, the inhibition of tumorigenic cells may occur as a result of a change in one or more physiological pathways. The change in the pathway, whether by inhibition or elimination of the tumorigenic cells, modification of their potential (for example, by induced differentiation or niche disruption) or otherwise interfering with the ability of tumorigenic cells to influence the tumor environment or other cells, allows for the more effective treatment of KREMEN2 associated disorders by inhibiting tumorigenesis, tumor maintenance and/or metastasis and recurrence. It will further be appreciated that the same characteristics of the disclosed antibodies make them particularly effective at treating recurrent tumors which have proved resistant or refractory to standard treatment regimens.
Methods that can be used to assess the reduction in the frequency of tumorigenic cells, include but are not limited to, cytometric or immunohistochemical analysis, preferably by in vitro or in vivo limiting dilution analysis (Dylla et al. 2008, PMID: PMC2413402 and Hoey et al. 2009, PMID: 19664991).
In vitro limiting dilution analysis may be performed by culturing fractionated or unfractionated tumor cells (e.g. from treated and untreated tumors, respectively) on solid medium that fosters colony formation and counting and characterizing the colonies that grow. Alternatively, the tumor cells can be serially diluted onto plates with wells containing liquid medium and each well can be scored as either positive or negative for colony formation at any time after inoculation but preferably more than 10 days after inoculation. In vivo limiting dilution is performed by transplanting tumor cells, from either untreated controls or from tumors exposed to selected therapeutic agents, into immunocompromised mice in serial dilutions and subsequently scoring each mouse as either positive or negative for tumor formation. The scoring may occur at any time after the implanted tumors are detectable but is preferably done 60 or more days after the transplant. The analysis of the results of limiting dilution experiments to determine the frequency of tumorigenic cells is preferably done using Poisson distribution statistics or assessing the frequency of predefined definitive events such as the ability to generate tumors in vivo or not (Fazekas et al., 1982, PMTD: 7040548).
Flow cytometry and immunohistochemistry may also be used to determine tumorigenic cell frequency. Both techniques employ one or more antibodies or reagents that bind art recognized cell surface proteins or markers known to enrich for tumorigenic cells (see WO 2012/031280). As known in the art, flow cytometry (e.g. florescence activated cell sorting (FACS)) can also be used to characterize, isolate, purify, enrich or sort for various cell populations including tumorigenic cells. Flow cytometry measures tumorigenic cell levels by passing a stream of fluid, in which a mixed population of cells is suspended, through an electronic detection apparatus which is able to measure the physical and/or chemical characteristics of up to thousands of particles per second. Immunohistochemistry provides additional information in that it enables visualization of tumorigenic cells in situ (e.g., in a tissue section) by staining the tissue sample with labeled antibodies or reagents which bind to tumorigenic cell markers.
As such, the antibodies of the invention may be useful for identifying, characterizing, monitoring, isolating, sectioning or enriching populations or subpopulations of tumorigenic cells through methods such as, for example, flow cytometry, magnetic activated cell sorting (MACS), laser mediated sectioning or FACS. FACS is a reliable method used to isolate cell subpopulations at more than 99.5% purity based on specific cell surface markers. Other compatible techniques for the characterization and manipulation of tumorigenic cells including CSCs can be seen, for example, in U.S.P.N.s 12/686,359, 12/669,136 and 12/757,649.
Listed below are markers that have been associated with CSC populations and have been used to isolate or characterize CSCs: ABCAl, ABCA3, ABCB5, ABCG2, ADAM9, ADCY9, ADORA2A, ALDH, AFP, AXIN1, B7H3, BCL9, Bmi-1, BMP-4, C20orf52, C4.4A, carboxypeptidase M, CAV1, CAV2, CD105, CD117, CD123, CD133, CD14, CD16, CD166, CD16a, CD16b, CD2, CD20, CD24, CD29, CD3, CD31, CD324, CD325, CD33, CD34, CD38, CD44, CD45, CD46, CD49b, CD49f, CD56, CD64, CD74, CD9, CD90, CD96, CEACAM6, CELSR1, CLEC12A, CPD, CRIM1, CX3CL1, CXCR4, DAF, decorin, easyhl, easyh2, EDG3, EGFR, E PP1, EPCAM, EPHA1, EPHA2, FLJ10052, FLVCR, FZD1, FZD10, FZD2, FZD3, FZD4, FZD6, FZD7, FZD8, FZD9, GD2, GJA1, GLI1, GLI2, GPNMB, GPR54, GPRC5B, HAVCR2, IL1R1, ILIRAP, JAM3, Lgr5, Lgr6, LRP3, LY6E, MCP, mf2, mllt3, MPZL1, MUC1, MUC16, MYC, N33, NANOG, NB84, NES, NID2, NMA, NPCl, OSM, OCT4, OPN3, PCDH7, PCDHAIO, PCDHB2, PPAP2C, PTPN3, PTS, RARRESl, SEMA4B, SLC 19A2, SLClAl, SLC39A1, SLC4A11, SLC6A14, SLC7A8, SMARCA3, SMARCD3, SMARCEl, SMARCA5, SOX1, STAT3, STEAP, TCF4, TEM8, TGFBR3, TMEPAI, TMPRSS4, TFRC, TRKA, WNT10B, WNT16, WNT2, WNT2B, WNT3, WNT5A, YY1 and CTNNBl . See, for example, Schulenburg et al, 2010, PMID: 20185329, U.S.P.N. 7,632,678 and U.S.P.N.s. 2007/0292414, 2008/0175870, 2010/0275280, 2010/0162416 and 2011/0020221.
Similarly, non-limiting examples of cell surface phenotypes associated with CSCs of certain tumor types include DA^ DIA1™ , ALDH+, CD133+, CD123+, CD34+CD38", CD44+CD24", D46 C 24+ D66c , CD133+CD34+CD10XD19~, CD138"CD34"CD19+, CD133+RC2+, Οϋ44+α2βι¾ϋ133+, CD44+CD24+ESA+, CD271+, ABCB5+ as well as other CSC surface phenotypes that are known in the art. See, for example, Schulenburg et al, 2010, supra, Visvader et al, 2008, PMID: 18784658 and U.S.P.N. 2008/0138313. Of particular interest with respect to the instant invention are CSC preparations comprising CD46MCD324+ phenotypes in solid tumors and CD34+CD38" in leukemias.
"Positive," "low" and "negative" expression levels as they apply to markers or marker phenotypes are defined as follows. Cells with negative expression (i.e."-") are herein defined as those cells expressing less than, or equal to, the 95th percentile of expression observed with an isotype control antibody in the channel of fluorescence in the presence of the complete antibody staining cocktail labeling for other proteins of interest in additional channels of fluorescence emission. Those skilled in the art will appreciate that this procedure for defining negative events is referred to as "fluorescence minus one", or "FMO", staining. Cells with expression greater than the 95th percentile of expression observed with an isotype control antibody using the FMO staining procedure described above are herein defined as "positive" (i.e."+"). As defined herein there are various populations of cells broadly defined as "positive." A cell is defined as positive if the mean observed expression of the antigen is above the 95th percentile determined using FMO staining with an isotype control antibody as described above. The positive cells may be termed cells with low expression (i.e. "lo") if the mean observed expression is above the 95th percentile determined by FMO staining and is within one standard deviation of the 95th percentile. Alternatively, the positive cells may be termed cells with high expression (i.e. "hi") if the mean observed expression is above the 95th percentile determined by FMO staining and greater than one standard deviation above the 95th percentile. In other embodiments the 99th percentile may preferably be used as a demarcation point between negative and positive FMO staining and in some embodiments the percentile may be greater than 99%.
The CD46MCD324+ or CD34+CD38" marker phenotype and those exemplified immediately above may be used in conjunction with standard flow cytometric analysis and cell sorting techniques to characterize, isolate, purify or enrich TIC and/or TPC cells or cell populations for further analysis.
The ability of the antibodies of the current invention to reduce the frequency of tumorigenic cells can therefore be determined using the techniques and markers described above. In some instances, the anti-KREMEN2 antibodies may reduce the frequency of tumorigenic cells by 10%>, 15%), 20%), 25%), 30%) or even by 35%. In other embodiments, the reduction in frequency of tumorigenic cells may be in the order of 40%, 45%, 50%, 55%, 60% or 65%. In certain embodiments, the disclosed compounds may reduce the frequency of tumorigenic cells by 70%, 75%), 80%), 85%o, 90%) or even 95%. It will be appreciated that any reduction of the frequency of tumorigenic cells is likely to result in a corresponding reduction in the tumorigenicity, persistence, recurrence and aggressiveness of the neoplasia.
III. Antibodies
A. Antibody structure
Antibodies and variants and derivatives thereof, including accepted nomenclature and numbering systems, have been extensively described, for example, in Abbas et al. (2010), Cellular and Molecular Immunology (6th Ed.), W.B. Saunders Company; or Murphey et al. (2011), Janeway's Immunobiology (8th Ed ), Garland Science.
An "antibody" or "intact antibody" typically refers to a Y-shaped tetrameric protein comprising two heavy (H) and two light (L) polypeptide chains held together by covalent disulfide bonds and non-covalent interactions. Each light chain is composed of one variable domain (VL) and one constant domain (CL). Each heavy chain comprises one variable domain (VH) and a constant region, which in the case of IgG, IgA, and IgD antibodies, comprises three domains termed CHI, CH2, and CH3 (IgM and IgE have a fourth domain, CH4). In IgG, IgA, and IgD classes the CHI and CH2 domains are separated by a flexible hinge region, which is a proline and cysteine rich segment of variable length (from about 10 to about 60 amino acids in various IgG subclasses). The variable domains in both the light and heavy chains are joined to the constant domains by a "J" region of about 12 or more amino acids and the heavy chain also has a "D" region of about 10 additional amino acids. Each class of antibody further comprises inter-chain and intra-chain disulfide bonds formed by paired cysteine residues.
As used herein the term "antibody" includes polyclonal antibodies, multi clonal antibodies, monoclonal antibodies, chimeric antibodies, humanized and primatized antibodies, CDR grafted antibodies, human antibodies (including recombinantly produced human antibodies), recombinantly produced antibodies, intrabodies, multispecific antibodies, bispecific antibodies, monovalent antibodies, multivalent antibodies, anti -idiotypic antibodies, synthetic antibodies, including muteins and variants thereof, immunospecific antibody fragments such as Fd, Fab, F(ab')2, F(ab') fragments, single-chain fragments (e.g. ScFv and ScFvFc); and derivatives thereof including Fc fusions and other modifications, and any other immunoreactive molecule so long as it exhibits preferential association or binding with a determinant. Moreover, unless dictated otherwise by contextual constraints the term further comprises all classes of antibodies (i.e. IgA, IgD, IgE, IgG, and IgM) and all subclasses (i.e., IgGl, IgG2, IgG3, IgG4, IgAl, and IgA2). Heavy-chain constant domains that correspond to the different classes of antibodies are typically denoted by the corresponding lower case Greek letter α, δ, ε, γ, and μ, respectively. Light chains of the antibodies from any vertebrate species can be assigned to one of two clearly distinct types, called kappa (κ) and lambda (λ), based on the amino acid sequences of their constant domains.
The variable domains of antibodies show considerable variation in amino acid composition from one antibody to another and are primarily responsible for antigen recognition and binding. Variable regions of each light/heavy chain pair form the antibody binding site such that an intact IgG antibody has two binding sites (i.e. it is bivalent). VH and VL domains comprise three regions of extreme variability, which are termed hypervariable regions, or more commonly, complementarity-determining regions (CDRs), framed and separated by four less variable regions known as framework regions (FRs). Non-covalent association between the VH and the VL region forms the Fv fragment (for "fragment variable") which contains one of the two antigen-binding sites of the antibody.
As used herein, the assignment of amino acids to each domain, framework region and CDR may be in accordance with one of the schemes provided by Kabat et al (1991) Sequences of Proteins of Immunological Interest (5th Ed.), US Dept. of Health and Human Services, PHS, NIH, NIH Publication no. 91-3242; Chothia et al, 1987, PMID: 3681981; Chothia et al, 1989, PMID: 2687698; MacCallum et al, 1996, PMID: 8876650; or Dub el, Ed. (2007) Handbook of Therapeutic Antibodies, 3rd Ed., Wily-VCH Verlag GmbH and Co or AbM (Oxford Molecular/MSI Pharmacopia) unless otherwise noted. As is well known in the art variable region residue numbering is typically as set forth in Chothia or Kabat. Amino acid residues which comprise CDRs as defined by Kabat, Chothia, MacCallum (also known as Contact) and AbM as obtained from the Abysis website database (infra.) are set out below in Table 1. Note that MacCallum uses the Chothia numbering system.
TABLE 1
Figure imgf000020_0001
Variable regions and CDRs in an antibody sequence can be identified according to general rules that have been developed in the art (as set out above, such as, for example, the Kabat numbering system) or by aligning the sequences against a database of known variable regions. Methods for identifying these regions are described in Kontermann and Dubel, eds., Antibody Engineering, Springer, New York, NY, 2001 and Dinarello et al, Current Protocols in Immunology, John Wiley and Sons Inc., Hoboken, NJ, 2000. Exemplary databases of antibody sequences are described in, and can be accessed through, the "Abysis" website at www.bioinf.org.uk/abs (maintained by A.C. Martin in the Department of Biochemistry & Molecular Biology University College London, London, England) and the VBASE2 website at www.vbase2.org, as described in Retter et al, Nucl. Acids Res., 33 (Database issue): D671 -D674 (2005).
Preferably the sequences are analyzed using the Abysis database, which integrates sequence data from Kabat, EVIGT and the Protein Data Bank (PDB) with structural data from the PDB. See Dr. Andrew C. R. Martin's book chapter Protein Sequence and Structure Analysis of Antibody Variable Domains. In: Antibody Engineering Lab Manual (Ed. : Duebel, S. and Kontermann, R., Springer- Verlag, Heidelberg, ISBN-13 : 978-3540413547, also available on the website bioinforg.uk/abs). The Abysis database website further includes general rules that have been developed for identifying CDRs which can be used in accordance with the teachings herein. FIGS. 6G - 6J appended hereto show the results of such analysis in the annotation of exemplary heavy and light chain variable regions for the SC78.9, SC78.43, SC78.56 and SC78.59 antibodies. Unless otherwise indicated, all CDRs set forth herein are derived according to the Abysis database website as per Kabat et al.
For heavy chain constant region amino acid positions discussed in the invention, numbering is according to the Eu index first described in Edelman et al, 1969, Proc. Natl. Acad. Sci. USA 63(1): 78-85 describing the amino acid sequence of the myeloma protein Eu, which reportedly was the first human IgGl sequenced. The Eu index of Edelman is also set forth in Kabat et al, 1991 {supra). Thus, the terms "Eu index as set forth in Kabat" or "Eu index of Kabat" or "Eu index" or "Eu numbering" in the context of the heavy chain refers to the residue numbering system based on the human IgGl Eu antibody of Edelman et al. as set forth in Kabat et al., 1991 {supra) The numbering system used for the light chain constant region amino acid sequence is similarly set forth in Kabat et al., {supra). Exemplary kappa (SEQ ID NO: 5) and lambda (SEQ ID NO: 8) light chain constant region amino acid sequences compatible with the present invention is set forth immediately below:
RTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDS KDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRGEC (SEQ ID NO: 5). QPKANPTVTLFPPSSEELQANKATLVCLISDFYPGAVTVAWKADGSPVKAGVETTKPSKQS NNKYAASSYLSLTPEQWKSHRSYSCQVTHEGSTVEKTVAPTECS (SEQ ID NO: 8). Similarly, an exemplary IgGl heavy chain constant region amino acid sequence compatible with the present invention is set forth immediately below: ASTKGP S VFPLAP S SK ST SGGT AALGCLVKD YFPEP VT VS WNSGALT SGVHTFP AVLQ S SGL YSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVF LFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYR VVSVLTVLHQDWLNGKEYKCKVS KALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQ VSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVF SCSVMHEALHNHYTQKSLSLSPG (SEQ ID NO: 2).
Those of skill in the art will appreciate that such heavy and light chain constant region sequences, either wild-type (e.g., see SEQ ID NOS: 2, 5 or 8) or engineered as disclosed herein to provide unpaired cysteines (e.g., see SEQ ID NOS: 3, 4, 6, 7, 9 or 10) may be operably associated with the disclosed heavy and light chain variable regions using standard molecular biology techniques to provide full-length antibodies that may be incorporated in the KREMEN2 antibody drug conjugates of the instant invention. Sequences of full-length heavy and light chains comprising selected antibodies of the instant invention are set forth in FIG. 6F appended hereto.
There are two types of disulfide bridges or bonds in immunoglobulin molecules: interchain and intrachain disulfide bonds. As is well known in the art the location and number of interchain disulfide bonds vary according to the immunoglobulin class and species. While the invention is not limited to any particular class or subclass of antibody, the IgGl immunoglobulin shall be used throughout the instant disclosure for illustrative purposes. In wild-type IgGl molecules there are twelve intrachain disulfide bonds (four on each heavy chain and two on each light chain) and four interchain disulfide bonds. Intrachain disulfide bonds are generally somewhat protected and relatively less susceptible to reduction than interchain bonds. Conversely, interchain disulfide bonds are located on the surface of the immunoglobulin, are accessible to solvent and are usually relatively easy to reduce. Two interchain disulfide bonds exist between the heavy chains and one from each heavy chain to its respective light chain. It has been demonstrated that interchain disulfide bonds are not essential for chain association. The IgGl hinge region contain the cysteines in the heavy chain that form the interchain disulfide bonds, which provide structural support along with the flexibility that facilitates Fab movement. The heavy/heavy IgGl interchain disulfide bonds are located at residues C226 and C229 (Eu numbering) while the IgGl interchain disulfide bond between the light and heavy chain of IgGl (heavy/light) are formed between C214 of the kappa or lambda light chain and C220 in the upper hinge region of the heavy chain.
B. Antibody generation and production
Antibodies of the invention can be produced using a variety of methods known in the art.
1. Generation of polyclonal antibodies in host animals
The production of polyclonal antibodies in various host animals is well known in the art (see for example, Harlow and Lane (Eds.) (1988) Antibodies: A Laboratory Manual, CSH Press; and Harlow et al. (1989) Antibodies, NY, Cold Spring Harbor Press). In order to generate polyclonal antibodies, an immunocompetent animal (e.g., mouse, rat, rabbit, goat, non-human primate, etc.) is immunized with an antigenic protein or cells or preparations comprising an antigenic protein. After a period of time, polyclonal antibody-containing serum is obtained by bleeding or sacrificing the animal. The serum may be used in the form obtained from the animal or the antibodies may be partially or fully purified to provide immunoglobulin fractions or isolated antibody preparations.
In this regard antibodies of the invention may be generated from any KREMEN2 determinant that induces an immune response in an immunocompetent animal. As used herein "determinant" or "target" means any detectable trait, property, marker or factor that is identifiably associated with, or specifically found in or on a particular cell, cell population or tissue. Determinants or targets may be morphological, functional or biochemical in nature and are preferably phenotypic. In preferred embodiments a determinant is a protein that is differentially expressed (over- or under-expressed) by specific cell types or by cells under certain conditions (e.g., during specific points of the cell cycle or cells in a particular niche). For the purposes of the instant invention a determinant preferably is differentially expressed on aberrant cancer cells and may comprise a KREMEN2 protein, or any of its splice variants, isoforms, homologs or family members, or specific domains, regions or epitopes thereof. An "antigen", "immunogenic determinant", "antigenic determinant" or "immunogen" means any KREMEN2 protein or any fragment, region or domain thereof that can stimulate an immune response when introduced into an immunocompetent animal and is recognized by the antibodies produced by the immune response. The presence or absence of the KREMEN2 determinants contemplated herein may be used to identify a cell, cell subpopulation or tissue (e.g., tumors, tumorigenic cells or CSCs).
Any form of antigen, or cells or preparations containing the antigen, can be used to generate an antibody that is specific for the KREMEN2 determinant. As set forth herein the term "antigen" is used in a broad sense and may comprise any immunogenic fragment or determinant of the selected target including a single epitope, multiple epitopes, single or multiple domains or the entire extracellular domain (ECD) or protein. The antigen may be an isolated full-length protein, a cell surface protein (e.g., immunizing with cells expressing at least a portion of the antigen on their surface), or a soluble protein (e.g., immunizing with only the ECD portion of the protein) or protein construct (e.g., Fc-antigen). The antigen may be produced in a genetically modified cell. Any of the aforementioned antigens may be used alone or in combination with one or more immunogenicity enhancing adjuvants known in the art. DNA encoding the antigen may be genomic or non-genomic (e.g., cDNA) and may encode at least a portion of the ECD, sufficient to elicit an immunogenic response. Any vectors may be employed to transform the cells in which the antigen is expressed, including but not limited to adenoviral vectors, lentiviral vectors, plasmids, and non- viral vectors, such as cationic lipids.
2. Monoclonal antibodies
In selected embodiments, the invention contemplates use of monoclonal antibodies. As known in the art, the term "monoclonal antibody" or "mAb" refers to an antibody obtained from a population of substantially homogeneous antibodies, i.e., the individual antibodies comprising the population are identical except for possible mutations (e.g., naturally occurring mutations), that may be present in minor amounts.
Monoclonal antibodies can be prepared using a wide variety of techniques known in the art including hybridoma techniques, recombinant techniques, phage display technologies, transgenic animals (e.g., a XenoMouse®) or some combination thereof. For example, monoclonal antibodies can be produced using hybridoma and biochemical and genetic engineering techniques such as described in more detail in An, Zhigiang (ed.) Therapeutic Monoclonal Antibodies: From Bench to Clinic, John Wiley and Sons, 1st ed. 2009; Shire et. al. (eds.) Current Trends in Monoclonal Antibody Development and Manufacturing, Springer Science + Business Media LLC, 1 st ed. 2010; Harlow et al, Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory Press, 2nd ed. 1988; Hammerling, et al, in: Monoclonal Antibodies and T-Cell Hybridomas 563-681 (Elsevier, N.Y., 1981). Following production of multiple monoclonal antibodies that bind specifically to a determinant, particularly effective antibodies may be selected through various screening processes, based on, for example, its affinity for the determinant or rate of internalization. Antibodies produced as described herein may be used as "source" antibodies and further modified to, for example, improve affinity for the target, improve its production in cell culture, reduce immunogenicity in vivo, create multispecific constructs, etc. A more detailed description of monoclonal antibody production and screening is set out below and in the appended Examples. 3. Human antibodies
In another embodiment, the antibodies may comprise fully human antibodies. The term "human antibody" refers to an antibody which possesses an amino acid sequence that corresponds to that of an antibody produced by a human and/or has been made using any of the techniques for making human antibodies described below.
Human antibodies can be produced using various techniques known in the art. One technique is phage display in which a library of (preferably human) antibodies is synthesized on phages, the library is screened with the antigen of interest or an antibody -binding portion thereof, and the phage that binds the antigen is isolated, from which one may obtain the immunoreactive fragments. Methods for preparing and screening such libraries are well known in the art and kits for generating phage display libraries are commercially available (e.g., the Pharmacia Recombinant Phage Antibody System, catalog no. 27-9400-01; and the Stratagene SurfZAP™ phage display kit, catalog no. 240612). There also are other methods and reagents that can be used in generating and screening antibody display libraries (see, e.g., U. S.P.N. 5,223,409; PCT Publication Nos. WO 92/18619, WO 91/17271, WO 92/20791, WO 92/15679, WO 93/01288, WO 92/01047, WO 92/09690; and Barbas et al, Proc. Natl. Acad. Sci. USA 88:7978-7982 (1991)).
In one embodiment, recombinant human antibodies may be isolated by screening a recombinant combinatorial antibody library prepared as above. In one embodiment, the library is a scFv phage display library, generated using human VL and VH cDNAs prepared from mRNA isolated from B-cells. The antibodies produced by naive libraries (either natural or synthetic) can be of moderate affinity (Ka of about 106 to 107 M"1), but affinity maturation can also be mimicked in vitro by constructing and reselecting from secondary libraries as described in the art. For example, mutation can be introduced at random in vitro by using error-prone polymerase (reported in Leung et al., Technique, 1 : 11-15 (1989)). Additionally, affinity maturation can be performed by randomly mutating one or more CDRs, e.g. using PCR with primers carrying random sequence spanning the CDR of interest, in selected individual Fv clones and screening for higher-affinity clones. WO 9607754 described a method for inducing mutagenesis in a CDR of an immunoglobulin light chain to create a library of light chain genes. Another effective approach is to recombine the VH or VL domains selected by phage display with repertoires of naturally occurring V domain variants obtained from unimmunized donors and to screen for higher affinity in several rounds of chain reshuffling as described in Marks et al., Biotechnol., 10: 779-783 (1992). This technique allows the production of antibodies and antibody fragments with a dissociation constant KD (k0ff/kon) of about 10"9 M or less.
In other embodiments, similar procedures may be employed using libraries comprising eukaryotic cells (e.g., yeast) that express binding pairs on their surface. See, for example, U.S. P.N. 7,700,302 and U.S. S.N. 12/404,059. In one embodiment, the human antibody is selected from a phage library, where that phage library expresses human antibodies (Vaughan et al. Nature Biotechnology 14:309-314 (1996): Sheets et al. Proc. Natl. Acad. Sci. USA 95:6157-6162 (1998). In other embodiments, human binding pairs may be isolated from combinatorial antibody libraries generated in eukaryotic cells such as yeast. See e.g., U. S.P.N. 7,700,302. Such techniques advantageously allow for the screening of large numbers of candidate modulators and provide for relatively easy manipulation of candidate sequences (e.g., by affinity maturation or recombinant shuffling).
Human antibodies can also be made by introducing human immunoglobulin loci into transgenic animals, e.g., mice in which the endogenous immunoglobulin genes have been partially or completely inactivated and human immunoglobulin genes have been introduced. Upon challenge, human antibody production is observed, which closely resembles that seen in humans in all respects, including gene rearrangement, assembly, and antibody repertoire. This approach is described, for example, in U.S.P.Ns. 5,545,807; 5,545,806; 5,569,825; 5,625, 126; 5,633,425; 5,661,016, and U.S.P.Ns. 6,075, 181 and 6,150,584 regarding XenoMouse® technology; and Lonberg and Huszar, Intern. Rev. Immunol. 13 :65-93 (1995). Alternatively, the human antibody may be prepared via immortalization of human B lymphocytes producing an antibody directed against a target antigen (such B lymphocytes may be recovered from an individual suffering from a neoplastic disorder or may have been immunized in vitro). See, e.g., Cole et al, Monoclonal Antibodies and Cancer Therapy, Alan R. Liss, p. 77 (1985); Boerner et al., J. Immunol, 147 (1): 86- 95 (1991); and U.S.P.N. 5,750,373.
Whatever the source it will be appreciated that the human antibody sequence may be fabricated using art-known molecular engineering techniques and introduced into expression systems and host cells as described herein. Such non-natural recombinantly produced human antibodies (and subject compositions) are entirely compatible with the teachings of this disclosure and are expressly held to be within the scope of the instant invention. In certain select aspects the KREMEN2 ADCs of the invention will comprise a recombinantly produced human antibody acting as a cell binding agent.
4. Derived antibodies:
Once source antibodies have been generated, selected and isolated as described above they may be further altered to provide anti-KREMEN2 antibodies having improved pharmaceutical characteristics. Preferably the source antibodies are modified or altered using known molecular engineering techniques to provide derived antibodies having the desired therapeutic properties.
4.1. Chimeric and humanized antibodies
Selected embodiments of the invention comprise murine monoclonal antibodies that immunospecifically bind to KREMEN2 and which can be considered "source" antibodies. In selected embodiments, antibodies of the invention can be derived from such "source" antibodies through optional modification of the constant region and/or the epitope-binding amino acid sequences of the source antibody. In certain embodiments an antibody is "derived" from a source antibody if selected amino acids in the source antibody are altered through deletion, mutation, substitution, integration or combination. In another embodiment, a "derived" antibody is one in which fragments of the source antibody (e.g., one or more CDRs or domains or the entire heavy and light chain variable regions) are combined with or incorporated into an acceptor antibody sequence to provide the derivative antibody (e.g. chimeric, CDR grafted or humanized antibodies). These "derived" antibodies can be generated using genetic material from the antibody producing cell and standard molecular biological techniques as described below, such as, for example, to improve affinity for the determinant; to improve antibody stability; to improve production and yield in cell culture; to reduce immunogenicity in vivo; to reduce toxicity; to facilitate conjugation of an active moiety; or to create a multispecific antibody. Such antibodies may also be derived from source antibodies through modification of the mature molecule (e.g., glycosylation patterns or pegylation) by chemical means or post-translational modification.
In one embodiment, the antibodies of the invention comprise chimeric antibodies that are derived from protein segments from at least two different species or class of antibodies that have been covalently joined. The term "chimeric" antibody is directed to constructs in which a portion of the heavy and/or light chain is identical or homologous to corresponding sequences in antibodies from a particular species or belonging to a particular antibody class or subclass, while the remainder of the chain(s) is identical or homologous to corresponding sequences in antibodies from another species or belonging to another antibody class or subclass, as well as fragments of such antibodies (U.S. P.N. 4,816,567). In some embodiments chimeric antibodies of the instant invention may comprise all or most of the selected murine heavy and light chain variable regions operably linked to human light and heavy chain constant regions. In other selected embodiments, anti-KREMEN2 antibodies may be "derived" from the mouse antibodies disclosed herein and comprise less than the entire heavy and light chain variable regions.
In yet other embodiments, chimeric antibodies of the invention are "CDR-grafted" antibodies, where the CDRs (as defined using Kabat, Chothia, McCallum, etc.) are derived from a particular species or belonging to a particular antibody class or subclass, while the remainder of the antibody is largely derived from an antibody from another species or belonging to another antibody class or subclass. For use in humans, one or more selected rodent CDRs (e.g., mouse CDRs) may be grafted into a human acceptor antibody, replacing one or more of the naturally occurring CDRs of the human antibody. These constructs generally have the advantages of providing full strength human antibody functions, e.g., complement dependent cytotoxicity (CDC) and antibody-dependent cell- mediated cytotoxicity (ADCC) while reducing unwanted immune responses to the antibody by the subject. In one embodiment the CDR grafted antibodies will comprise one or more CDRs obtained from a mouse incorporated in a human framework sequence. Similar to the CDR-grafted antibody is a "humanized" antibody. As used herein, a "humanized" antibody is a human antibody (acceptor antibody) comprising one or more amino acid sequences (e.g. CDR sequences) derived from one or more non-human antibodies (donor or source antibody). In certain embodiments, "back mutations" can be introduced into the humanized antibody, in which residues in one or more FRs of the variable region of the recipient human antibody are replaced by corresponding residues from the non-human species donor antibody. Such back mutations may to help maintain the appropriate three-dimensional configuration of the grafted CDR(s) and thereby improve affinity and antibody stability. Antibodies from various donor species may be used including, without limitation, mouse, rat, rabbit, or non-human primate. Furthermore, humanized antibodies may comprise new residues that are not found in the recipient antibody or in the donor antibody to, for example, further refine antibody performance. CDR grafted and humanized antibodies compatible with the instant invention comprising murine components from source antibodies and human components from acceptor antibodies may be provided as set forth in the Examples below.
Various art-recognized techniques can be used to determine which human sequences to use as acceptor antibodies to provide humanized constructs in accordance with the instant invention. Compilations of compatible human germline sequences and methods of determining their suitability as acceptor sequences are disclosed, for example, in Dubel and Reichert (Eds.) (2014) Handbook of Therapeutic Antibodies, 2nd Edition, Wiley-Blackwell GmbH; Tomlinson, I. A. et al. (1992) J. Mol. Biol. 227:776-798; Cook, G. P. et al. (1995) Immunol. Today 16: 237-242; Chothia, D. et al. (1992) J. Mol. Biol. 227:799-817; and Tomlinson et al. (1995) EMBO J 14:4628-4638). The V-BASE directory (VBASE2 - Retter et al, Nucleic Acid Res. 33; 671-674, 2005) which provides a comprehensive directory of human immunoglobulin variable region sequences (compiled by Tomlinson, I. A. et al. MRC Centre for Protein Engineering, Cambridge, UK) may also be used to identify compatible acceptor sequences. Additionally, consensus human framework sequences described, for example, in U. S.P.N. 6,300,064 may also prove to be compatible acceptor sequences are can be used in accordance with the instant teachings. In general, human framework acceptor sequences are selected based on homology with the murine source framework sequences along with an analysis of the CDR canonical structures of the source and acceptor antibodies. The derived sequences of the heavy and light chain variable regions of the derived antibody may then be synthesized using art recognized techniques. By way of example CDR grafted and humanized antibodies, and associated methods, are described in U.S.P.Ns. 6, 180,370 and 5,693,762. For further details, see, e.g., Jones et al, 1986, (PMID: 3713831); and U.S.P.Ns. 6,982,321 and 7,087,409.
The sequence identity or homology of the CDR grafted or humanized antibody variable region to the human acceptor variable region may be determined as discussed herein and, when measured as such, will preferably share at least 60% or 65% sequence identity, more preferably at least 70%, 75%, 80%, 85%, or 90% sequence identity, even more preferably at least 93%, 95%, 98%) or 99%) sequence identity. Preferably, residue positions which are not identical differ by conservative amino acid substitutions. A "conservative amino acid substitution" is one in which an amino acid residue is substituted by another amino acid residue having a side chain (R group) with similar chemical properties (e.g., charge or hydrophobicity). In general, a conservative amino acid substitution will not substantially change the functional properties of a protein. In cases where two or more amino acid sequences differ from each other by conservative substitutions, the percent sequence identity or degree of similarity may be adjusted upwards to correct for the conservative nature of the substitution.
It will be appreciated that the annotated CDRs and framework sequences as provided in the appended FIGS. 6A and 6B are defined as per Kabat et al. using a proprietary Abysis database. However, as discussed herein and shown in FIGS.6G - 6J, one skilled in the art could readily identify CDRs in accordance with definitions provided by Chothia et al., ABM or MacCallum et al as well as Kabat et al. As such, anti-KREMEN2 humanized antibodies comprising one or more CDRs derived according to any of the aforementioned systems are explicitly held to be within the scope of the instant invention.
4.2. Site-specific antibodies
The antibodies of the instant invention may be engineered to facilitate conjugation to a cytotoxin or other anti-cancer agent (as discussed in more detail below). It is advantageous for the antibody drug conjugate (ADC) preparation to comprise a homogenous population of ADC molecules in terms of the position of the cytotoxin on the antibody and the drug to antibody ratio (DAR). Based on the instant disclosure one skilled in the art could readily fabricate site-specific engineered constructs as described herein. As used herein a "site-specific antibody" or "site- specific construct" means an antibody, or immunoreactive fragment thereof, wherein at least one amino acid in either the heavy or light chain is deleted, altered or substituted (preferably with another amino acid) to provide at least one free cysteine. Similarly, a "site-specific conjugate" shall be held to mean an ADC comprising a site-specific antibody and at least one cytotoxin or other compound (e.g., a reporter molecule) conjugated to the unpaired or free cysteine(s). In certain embodiments the unpaired cysteine residue will comprise an unpaired intrachain cysteine residue. In other embodiments the free cysteine residue will comprise an unpaired interchain cysteine residue. In still other embodiments the free cysteine may be engineered into the amino acid sequence of the antibody (e.g., in the CH3 domain). In any event the site-specific antibody can be of various isotypes, for example, IgG, IgE, IgA or IgD; and within those classes the antibody can be of various subclasses, for example, IgGl, IgG2, IgG3 or IgG4. For IgG constructs the light chain of the antibody can comprise either a kappa or lambda isotype each incorporating a C214 that, in selected embodiments, may be unpaired due to a lack of a C220 residue in the IgGl heavy chain.
Thus, as used herein, the terms "free cysteine" or "unpaired cysteine" may be used interchangeably unless otherwise dictated by context and shall mean any cysteine (or thiol containing) constituent (e.g., a cysteine residue) of an antibody, whether naturally present or specifically incorporated in a selected residue position using molecular engineering techniques, that is not part of a naturally occurring (or "native") disulfide bond under physiological conditions. In certain selected embodiments the free cysteine may comprise a naturally occurring cysteine whose native interchain or intrachain disulfide bridge partner has been substituted, eliminated or otherwise altered to disrupt the naturally occurring disulfide bridge under physiological conditions thereby rendering the unpaired cysteine suitable for site-specific conjugation. In other preferred embodiments the free or unpaired cysteine will comprise a cysteine residue that is selectively placed at a predetermined site within the antibody heavy or light chain amino acid sequences. It will be appreciated that, prior to conjugation, free or unpaired cysteines may be present as a thiol (reduced cysteine), as a capped cysteine (oxidized) or as part of a non-native intra- or intermolecular disulfide bond (oxidized) with another cysteine or thiol group on the same or different molecule depending on the oxidation state of the system. As discussed in more detail below, mild reduction of the appropriately engineered antibody construct will provide thiols available for site-specific conjugation. Accordingly, in particularly preferred embodiments the free or unpaired cysteines (whether naturally occurring or incorporated) will be subject to selective reduction and subsequent conjugation to provide homogenous DAR compositions. It will be appreciated that the favorable properties exhibited by the disclosed engineered conjugate preparations is predicated, at least in part, on the ability to specifically direct the conjugation and largely limit the fabricated conjugates in terms of conjugation position and the absolute DAR value of the composition. Unlike most conventional ADC preparations, the present invention need not rely entirely on partial or total reduction of the antibody to provide random conjugation sites and relatively uncontrolled generation of DAR species. Rather, in certain aspects the present invention preferably provides one or more predetermined unpaired (or free) cysteine sites by engineering the targeting antibody to disrupt one or more of the naturally occurring (i.e., "native") interchain or intrachain disulfide bridges or to introduce a cysteine residue at any position. To this end it will be appreciated that, in selected embodiments, a cysteine residue may be incorporated anywhere along the antibody (or immunoreactive fragment thereof) heavy or light chain or appended thereto using standard molecular engineering techniques. In other preferred embodiments disruption of native disulfide bonds may be effected in combination with the introduction of a non-native cysteine (which will then comprise the free cysteine) that may then be used as a conjugation site.
In certain embodiments the engineered antibody comprises at least one amino acid deletion or substitution of an intrachain or interchain cysteine residue. As used herein "interchain cysteine residue" means a cysteine residue that is involved in a native disulfide bond either between the light and heavy chain of an antibody or between the two heavy chains of an antibody while an "intrachain cysteine residue" is one naturally paired with another cysteine in the same heavy or light chain. In one embodiment the deleted or substituted interchain cysteine residue is involved in the formation of a disulfide bond between the light and heavy chain. In another embodiment the deleted or substituted cysteine residue is involved in a disulfide bond between the two heavy chains. In a typical embodiment, due to the complementary structure of an antibody, in which the light chain is paired with the VH and CHI domains of the heavy chain and wherein the CH2 and CH3 domains of one heavy chain are paired with the CH2 and CH3 domains of the complementary heavy chain, a mutation or deletion of a single cysteine in either the light chain or in the heavy chain would result in two unpaired cysteine residues in the engineered antibody.
In some embodiments an interchain cysteine residue is deleted. In other embodiments an interchain cysteine is substituted for another amino acid (e.g., a naturally occurring amino acid). For example, the amino acid substitution can result in the replacement of an interchain cysteine with a neutral (e.g. serine, threonine or glycine) or hydrophilic (e.g. methionine, alanine, valine, leucine or isoleucine) residue. In selected embodiments an interchain cysteine is replaced with a serine.
In some embodiments contemplated by the invention the deleted or substituted cysteine residue is on the light chain (either kappa or lambda) thereby leaving a free cysteine on the heavy chain. In other embodiments the deleted or substituted cysteine residue is on the heavy chain leaving the free cysteine on the light chain constant region. Upon assembly it will be appreciated that deletion or substitution of a single cysteine in either the light or heavy chain of an intact antibody results in a site-specific antibody having two unpaired cysteine residues.
In one embodiment the cysteine at position 214 (C214) of the IgG light chain (kappa or lambda) is deleted or substituted. In another embodiment the cysteine at position 220 (C220) on the IgG heavy chain is deleted or substituted. In further embodiments the cysteine at position 226 or position 229 on the heavy chain is deleted or substituted. In one embodiment C220 on the heavy chain is substituted with serine (C220S) to provide the desired free cysteine in the light chain. In another embodiment C214 in the light chain is substituted with serine (C214S) to provide the desired free cysteine in the heavy chain. Such site-specific constructs are described in more detail in the Examples below. A summary of compatible site-specific constructs is shown in Table 2 immediately below where numbering is generally according to the Eu index as set forth in Kabat, WT stands for "wild-type" or native constant region sequences without alterations and delta (Δ) designates the deletion of an amino acid residue (e.g., C214A indicates that the cysteine residue at position 214 has been deleted).
Table 2
Figure imgf000034_0001
Exemplary engineered light and heavy chain constant regions compatible with site-specific constructs of the instant invention are set forth immediately below where SEQ ID NOS: 3 and 4 comprise, respectively, C220S IgGl and C220A IgGl heavy chain constant regions, SEQ ID NOS: 6 and 7 comprise, respectively, C214S and C214A kappa light chain constant regions and SEQ ID NOS: 9 and 10 comprise, respectively, exemplary C214S and C214A lambda light chain constant regions. In each case the site of the altered or deleted amino acid (along with the flanking residues) is underlined.
ASTKGP S VFPL AP S SK ST SGGT AALGCLVKD YFPEP VT VS WNSGALT SGVHTFP AVLQ S SGL YSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSSDKTHTCPPCPAPELLGGPSVF LFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYR VVS VLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQ VSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVF SCSVMHEALHNHYTQKSLSLSPG (SEQ ID NO: 3)
AS TKGP S VFPL AP S SK S T SGGT AALGCLVKD YFPEP VTVSWNS GALT S GVHTFP A VLQ S S GL YSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSDKTHTCPPCPAPELLGGPSVFL
FPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRV VSVLTVLHQDWLNGKEYKCKVS KALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQV SLTCLVKGFYPSDIAVEWESNGQPE NYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFS CSVMHEALH HYTQKSLSLSPG (SEQ ID NO: 4) RTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDS KDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRGES (SEQ ID NO: 6)
RTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDS KDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRGE_ (SEQ ID NO: 7)
QPKANPTVTLFPPSSEELQANKATLVCLISDFYPGAVTVAWKADGSPVKAGVETTKPSKQS NNKYAASSYLSLTPEQWKSHRSYSCQVTHEGSTVEKTVAPTESS (SEQ ID NO: 9)
QPKANPTVTLFPPSSEELQANKATLVCLISDFYPGAVTVAWKADGSPVKAGVETTKPSKQS NNKYAASSYLSLTPEQWKSHRSYSCQVTHEGSTVEKTVAPTES (SEQ ID NO: 10)
As discussed above each of the heavy and light chain variants may be operably associated with the disclosed heavy and light chain variable regions (or derivatives thereof such as humanized or CDR grafted constructs) to provide site-specific anti-KREMEN2 antibodies as disclosed herein. Such engineered antibodies are particularly compatible for use in the disclosed ADCs.
With regard to the introduction or addition of a cysteine residue or residues to provide a free cysteine (as opposed to disrupting a native disulfide bond) compatible position(s) on the antibody or antibody fragment may readily be discerned by one skilled in the art. Accordingly, in selected embodiments the cysteine(s) may be introduced in the CHI domain, the CH2 domain or the CH3 domain or any combination thereof depending on the desired DAR, the antibody construct, the selected payload and the antibody target. In other preferred embodiments the cysteines may be introduced into a kappa or lambda CL domain and, in particularly preferred embodiments, in the c- terminal region of the CL domain. In each case other amino acid residues proximal to the site of cysteine insertion may be altered, removed or substituted to facilitate molecular stability, conjugation efficiency or provide a protective environment for the payload once it is attached. In particular embodiments, the substituted residues occur at any accessible sites of the antibody. By substituting such surface residues with cysteine, reactive thiol groups are thereby positioned at readily accessible sites on the antibody and may be selectively reduced as described further herein. In particular embodiments, the substituted residues occur at accessible sites of the antibody. By substituting those residues with cysteine, reactive thiol groups are thereby positioned at accessible sites of the antibody and may be used to selectively conjugate the antibody. In certain embodiments, any one or more of the following residues may be substituted with cysteine: V205 (Kabat numbering) of the light chain; A118 (Eu numbering) of the heavy chain; and S400 (Eu numbering) of the heavy chain Fc region. Additional substitution positions and methods of fabricating compatible site-specific antibodies are set forth in U.S.P.N. 7,521,541 which is incorporated herein in its entirety.
The strategy for generating antibody drug conjugates with defined sites and stoichiometries of drug loading, as disclosed herein, is broadly applicable to all anti-KREMEN2 antibodies as it primarily involves engineering of the conserved constant domains of the antibody. As the amino acid sequences and native disulfide bridges of each class and subclass of antibody are well documented, one skilled in the art could readily fabricate engineered constructs of various antibodies without undue experimentation and, accordingly, such constructs are expressly contemplated as being within the scope of the instant invention. This is particularly true of site- specific constructs comprising all or part of heavy and light chain variable region amino acid sequences as set forth in the instant disclosure. 4.3. Constant region modifications and altered glycosylation
Selected embodiments of the present invention may also comprise substitutions or modifications of the constant region (i.e. the Fc region), including without limitation, amino acid residue substitutions, mutations and/or modifications, which result in a compound with characteristics including, but not limited to: altered pharmacokinetics, increased serum half-life, increase binding affinity, reduced immunogenicity, increased production, altered Fc ligand binding to an Fc receptor (FcR), enhanced or reduced ADCC or CDC, altered glycosylation and/or disulfide bonds and modified binding specificity.
Compounds with improved Fc effector functions can be generated, for example, through changes in amino acid residues involved in the interaction between the Fc domain and an Fc receptor (e.g., FcyRI, FcyRIIA and B, FcyRIII and FcRn), which may lead to increased cytotoxicity and/or altered pharmacokinetics, such as increased serum half-life (see, for example, Ravetch and Kinet, Annu. Rev. Immunol 9:457-92 (1991); Capel et al, Immunomethods 4:25-34 (1994); and de Haas et al, J. Lab. Clin. Med. 126:330-41 (1995).
In selected embodiments, antibodies with increased in vivo half-lives can be generated by modifying (e.g., substituting, deleting or adding) amino acid residues identified as involved in the interaction between the Fc domain and the FcRn receptor (see, e.g., International Publication Nos. WO 97/34631; WO 04/029207; U.S.P.N. 6,737,056 and U.S.P.N. 2003/0190311). With regard to such embodiments, Fc variants may provide half-lives in a mammal, preferably a human, of greater than 5 days, greater than 10 days, greater than 15 days, preferably greater than 20 days, greater than 25 days, greater than 30 days, greater than 35 days, greater than 40 days, greater than 45 days, greater than 2 months, greater than 3 months, greater than 4 months, or greater than 5 months. The increased half-life results in a higher serum titer which thus reduces the frequency of the administration of the antibodies and/or reduces the concentration of the antibodies to be administered. Binding to human FcRn in vivo and serum half-life of human FcRn high affinity binding polypeptides can be assayed, e.g., in transgenic mice or transfected human cell lines expressing human FcRn, or in primates to which the polypeptides with a variant Fc region are administered. WO 2000/42072 describes antibody variants with improved or diminished binding to FcRns. See also, e.g., Shields et al. J. Biol. Chem. 9(2):6591-6604 (2001).
In other embodiments, Fc alterations may lead to enhanced or reduced ADCC or CDC activity. As in known in the art, CDC refers to the lysing of a target cell in the presence of complement, and ADCC refers to a form of cytotoxicity in which secreted Ig bound onto FcRs present on certain cytotoxic cells (e.g., Natural Killer cells, neutrophils, and macrophages) enables these cytotoxic effector cells to bind specifically to an antigen-bearing target cell and subsequently kill the target cell with cytotoxins. In the context of the instant invention antibody variants are provided with "altered" FcR binding affinity, which is either enhanced or diminished binding as compared to a parent or unmodified antibody or to an antibody comprising a native sequence FcR. Such variants which display decreased binding may possess little or no appreciable binding, e.g., 0- 20% binding to the FcR compared to a native sequence, e.g. as determined by techniques well known in the art. In other embodiments the variant will exhibit enhanced binding as compared to the native immunoglobulin Fc domain. It will be appreciated that these types of Fc variants may advantageously be used to enhance the effective anti -neoplastic properties of the disclosed antibodies. In yet other embodiments, such alterations lead to increased binding affinity, reduced immunogenicity, increased production, altered glycosylation and/or disulfide bonds (e.g., for conjugation sites), modified binding specificity, increased phagocytosis; and/or down regulation of cell surface receptors (e.g. B cell receptor; BCR), etc.
Still other embodiments comprise one or more engineered glycoforms, e.g., a site-specific antibody comprising an altered glycosylation pattern or altered carbohydrate composition that is covalently attached to the protein (e.g., in the Fc domain). See, for example, Shields, R. L. et al. (2002) J. Biol. Chem. 277:26733-26740. Engineered glycoforms may be useful for a variety of purposes, including but not limited to enhancing or reducing effector function, increasing the affinity of the antibody for a target or facilitating production of the antibody. In certain embodiments where reduced effector function is desired, the molecule may be engineered to express an aglycosylated form. Substitutions that may result in elimination of one or more variable region framework glycosylation sites to thereby eliminate glycosylation at that site are well known (see e.g. U.S.P.Ns. 5,714,350 and 6,350,861). Conversely, enhanced effector functions or improved binding may be imparted to the Fc containing molecule by engineering in one or more additional glycosylation sites.
Other embodiments include an Fc variant that has an altered glycosylation composition, such as a hypofucosylated antibody having reduced amounts of fucosyl residues or an antibody having increased bisecting GlcNAc structures. Such altered glycosylation patterns have been demonstrated to increase the ADCC ability of antibodies. Engineered glycoforms may be generated by any method known to one skilled in the art, for example by using engineered or variant expression strains, by co-expression with one or more enzymes (for example N- acetylglucosaminyltransferase III (GnTIII)), by expressing a molecule comprising an Fc region in various organisms or cell lines from various organisms or by modifying carbohydrate(s) after the molecule comprising Fc region has been expressed (see, for example, WO 2012/117002).
4.4. Fragments
Regardless of which form of antibody (e.g. chimeric, humanized, etc.) is selected to practice the invention it will be appreciated that immunoreactive fragments, either by themselves or as part of an antibody drug conjugate, of the same may be used in accordance with the teachings herein. An "antibody fragment" comprises at least a portion of an intact antibody. As used herein, the term "fragment" of an antibody molecule includes antigen-binding fragments of antibodies, and the term "antigen-binding fragment" refers to a polypeptide fragment of an immunoglobulin or antibody that immunospecifically binds or reacts with a selected antigen or immunogenic determinant thereof or competes with the intact antibody from which the fragments were derived for specific antigen binding.
Exemplary immunoreactive fragments include: variable light chain fragments (VL), variable heavy chain fragments (VH), scFvs, F(ab')2 fragment, Fab fragment, Fd fragment, Fv fragment, single domain antibody fragments, diabodies, linear antibodies, single-chain antibody molecules and multispecific antibodies formed from antibody fragments. In addition, an active site-specific fragment comprises a portion of the antibody that retains its ability to interact with the antigen/substrates or receptors and modify them in a manner similar to that of an intact antibody (though maybe with somewhat less efficiency). Such antibody fragments may further be engineered to comprise one or more free cysteines as described herein.
In particularly preferred embodiments the KREMEN2 binding domain will comprise a scFv construct. As used herein, a "single chain variable fragment (scFv)" means a single chain polypeptide derived from an antibody which retains the ability to bind to an antigen. An example of the scFv includes an antibody polypeptide which is formed by a recombinant DNA technique and in which Fv regions of immunoglobulin heavy chain and light chain fragments are linked via a spacer sequence. Various methods for preparing an scFv are known, and include methods described in U.S.P.N. 4,694,778.
In other embodiments, an antibody fragment is one that comprises the Fc region and that retains at least one of the biological functions normally associated with the Fc region when present in an intact antibody, such as FcRn binding, antibody half-life modulation, ADCC function and complement binding. In one embodiment, an antibody fragment is a monovalent antibody that has an in vivo half-life substantially similar to an intact antibody. For example, such an antibody fragment may comprise an antigen binding arm linked to an Fc sequence comprising at least one free cysteine capable of conferring in vivo stability to the fragment.
As would be well recognized by those skilled in the art, fragments can be obtained by molecular engineering or via chemical or enzymatic treatment (such as papain or pepsin) of an intact or complete antibody or antibody chain or by recombinant means. See, e.g., Fundamental Immunology, W. E. Paul, ed., Raven Press, N.Y. (1999), for a more detailed description of antibody fragments.
4.5. Multivalent constructs
In other embodiments, the antibodies and conjugates of the invention may be monovalent or multivalent (e.g., bivalent, trivalent, etc.). As used herein, the term "valency" refers to the number of potential target binding sites associated with an antibody. Each target binding site-specifically binds one target molecule or specific position or locus or epitope on a target molecule. When an antibody is monovalent, each binding site of the molecule will specifically bind to a single antigen position or epitope. When an antibody comprises more than one target binding site (multivalent), each target binding site may specifically bind the same or different molecules (e.g., may bind to different ligands or different antigens, or different epitopes or positions on the same antigen). See, for example, U.S.P.N. 2009/0130105.
In one embodiment, the antibodies are bispecific antibodies in which the two chains have different specificities, as described in Millstein et al., 1983, Nature, 305:537-539 and WO 2014/124326. Other embodiments include antibodies with additional specificities such as trispecific antibodies. Other more sophisticated compatible multispecific constructs and methods of their fabrication are set forth in U.S.P.N. 2009/0155255, as well as WO 94/04690; Suresh et al, 1986, Methods in Enzymology, 121 :210; and WO96/27011.
Multivalent antibodies may immunospecifically bind to different epitopes of the desired target molecule or may immunospecifically bind to both the target molecule as well as a heterologous epitope, such as a heterologous polypeptide or solid support material. While selected embodiments may only bind two antigens (i.e. bispecific antibodies), antibodies with additional specificities such as trispecific antibodies are also encompassed by the instant invention. Bispecific antibodies also include cross-linked or "heteroconjugate" antibodies. For example, one of the antibodies in the heteroconjugate can be coupled to avidin, the other to biotin. Such antibodies have, for example, been proposed to target immune system cells to unwanted cells (U.S.P.N. 4,676,980), and for treatment of HIV infection (WO 91/00360, WO 92/200373, and EP 03089). Heteroconjugate antibodies may be made using any convenient cross-linking methods. Suitable cross-linking agents are well known in the art, and are disclosed in U.S. P.N. 4,676,980, along with a number of cross- linking techniques. 5. Recombinant production of antibodies
Antibodies and fragments thereof may be produced or modified using genetic material obtained from antibody producing cells and recombinant technology (see, for example; Dubel and Reichert (Eds.) (2014) Handbook of Therapeutic Antibodies, 2nd Edition, Wiley-Blackwell GmbH; Sambrook and Russell (Eds.) (2000) Molecular Cloning: A Laboratory Manual (3rd Ed.), NY, Cold Spring Harbor Laboratory Press; Ausubel et al. (2002) Short Protocols in Molecular Biology: A Compendium of Methods from Current Protocols in Molecular Biology, Wiley, John & Sons, Inc.; and U.S.P.N. 7,709,611).
Another aspect of the invention pertains to nucleic acid molecules that encode the antibodies of the invention. The nucleic acids may be present in whole cells, in a cell lysate, or in a partially purified or substantially pure form. A nucleic acid is "isolated" or rendered substantially pure when separated from other cellular components or other contaminants, e.g., other cellular nucleic acids or proteins, by standard techniques, including alkaline/SDS treatment, CsCl banding, column chromatography, agarose gel electrophoresis and others well known in the art. A nucleic acid of the invention can be, for example, DNA (e.g. genomic DNA, cDNA), RNA and artificial variants thereof (e.g., peptide nucleic acids), whether single-stranded or double-stranded or RNA, RNA and may or may not contain introns. In selected embodiments the nucleic acid is a cDNA molecule.
Nucleic acids of the invention can be obtained using standard molecular biology techniques. For antibodies expressed by hybridomas (e.g., hybridomas prepared as described in the Examples below), cDNAs encoding the light and heavy chains of the antibody can be obtained by standard PCR amplification or cDNA cloning techniques. For antibodies obtained from an immunoglobulin gene library (e.g., using phage display techniques), nucleic acid molecules encoding the antibody can be recovered from the library.
DNA fragments encoding VH and VL segments can be further manipulated by standard recombinant DNA techniques, for example to convert the variable region genes to full-length antibody chain genes, to Fab fragment genes or to a scFv gene. In these manipulations, a VL- or VH-encoding DNA fragment is operatively linked to another DNA fragment encoding another protein, such as an antibody constant region or a flexible linker. The term "operatively linked", as used in this context, means that the two DNA fragments are joined such that the amino acid sequences encoded by the two DNA fragments remain in-frame.
The isolated DNA encoding the VH region can be converted to a full-length heavy chain gene by operatively linking the VH-encoding DNA to another DNA molecule encoding heavy chain constant regions (CHI, CH2 and CH3 in the case of IgGl). The sequences of human heavy chain constant region genes are known in the art (see e.g., Kabat, et al. (1991) {supra)) and DNA fragments encompassing these regions can be obtained by standard PCR amplification. The heavy chain constant region can be an IgGl, IgG2, IgG3, IgG4, IgA, IgE, IgM or IgD constant region, but most preferably is an IgGl or IgG4 constant region. An exemplary IgGl constant region is set forth in SEQ ID NO: 2. For a Fab fragment heavy chain gene, the VH-encoding DNA can be operatively linked to another DNA molecule encoding only the heavy chain CHI constant region.
Isolated DNA encoding the VL region can be converted to a full-length light chain gene (as well as a Fab light chain gene) by operatively linking the VL-encoding DNA to another DNA molecule encoding the light chain constant region, CL. The sequences of human light chain constant region genes are known in the art (see e.g., Kabat, et al. (1991) {supra)) and DNA fragments encompassing these regions can be obtained by standard PCR amplification. The light chain constant region can be a kappa or lambda constant region, but most preferably is a kappa constant region. An exemplary compatible kappa light chain constant region is set forth in SEQ ID NO: 5 while an exemplary compatible lambda light chain constant region is set forth in SEQ ID NO: 8.
In each case the VH or VL domains may be operatively linked to their respective constant regions (CH or CL) where the constant regions are site-specific constant regions and provide site- specific antibodies. In selected embodiments the resulting site-specific antibodies will comprise two unpaired cysteines on the heavy chains while in other embodiments the site-specific antibodies will comprise two unpaired cysteines in the CL domain.
Contemplated herein are certain polypeptides (e.g. antigens or antibodies) that exhibit "sequence identity", sequence similarity" or "sequence homology" to the polypeptides of the invention. For example, a derived humanized antibody VH or VL domain may exhibit a sequence similarity with the source (e.g., murine) or acceptor (e.g., human) VH or VL domain. A "homologous" polypeptide may exhibit 65%, 70%, 75%, 80%, 85%, or 90% sequence identity. In other embodiments a "homologous" polypeptides may exhibit 93%, 95% or 98% sequence identity. As used herein, the percent homology between two amino acid sequences is equivalent to the percent identity between the two sequences. The percent identity between the two sequences is a function of the number of identical positions shared by the sequences (i.e., % homology=# of identical positions/total # of positionsx lOO), taking into account the number of gaps, and the length of each gap, which need to be introduced for optimal alignment of the two sequences. The comparison of sequences and determination of percent identity between two sequences can be accomplished using a mathematical algorithm, as described in the non-limiting Examples below.
The percent identity between two amino acid sequences can be determined using the algorithm of E. Meyers and W. Miller (Comput. Appl. Biosci. ,4: 11-17 (1988)) which has been incorporated into the ALIGN program (version 2.0), using a PAM120 weight residue table, a gap length penalty of 12 and a gap penalty of 4. In addition, the percent identity between two amino acid sequences can be determined using the Needleman and Wunsch (J. Mol. Biol. 48:444-453 (1970)) algorithm which has been incorporated into the GAP program in the GCG software package (available at www.gcg.com), using either a Blossum 62 matrix or a PAM250 matrix, and a gap weight of 16, 14, 12, 10, 8, 6, or 4 and a length weight of 1, 2, 3, 4, 5, or 6.
Additionally, or alternatively, the protein sequences of the present invention can further be used as a "query sequence" to perform a search against public databases to, for example, identify related sequences. Such searches can be performed using the XBLAST program (version 2.0) of Altschul, et al. (1990) J. Mol. Biol. 215:403-10. BLAST protein searches can be performed with the XBLAST program, score=50, wordlength=3 to obtain amino acid sequences homologous to the antibody molecules of the invention. To obtain gapped alignments for comparison purposes, Gapped BLAST can be utilized as described in Altschul et al., (1997) Nucleic Acids Res. 25(17):3389-3402. When utilizing BLAST and Gapped BLAST programs, the default parameters of the respective programs (e.g., XBLAST and NBLAST) can be used.
Residue positions which are not identical may differ by conservative amino acid substitutions or by non-conservative amino acid substitutions. A "conservative amino acid substitution" is one in which an amino acid residue is substituted by another amino acid residue having a side chain with similar chemical properties (e.g., charge or hydrophobicity). In general, a conservative amino acid substitution will not substantially change the functional properties of a protein. In cases where two or more amino acid sequences differ from each other by conservative substitutions, the percent sequence identity or degree of similarity may be adjusted upwards to correct for the conservative nature of the substitution. In cases where there is a substitution with a non-conservative amino acid, in embodiments the polypeptide exhibiting sequence identity will retain the desired function or activity of the polypeptide of the invention (e.g., antibody.) Also contemplated herein are nucleic acids that that exhibit "sequence identity", sequence similarity" or "sequence homology" to the nucleic acids of the invention. A "homologous sequence" means a sequence of nucleic acid molecules exhibiting at least about 65%, 70%, 75%, 80%, 85%, or 90% sequence identity. In other embodiments, a "homologous sequence" of nucleic acids may exhibit 93%, 95% or 98% sequence identity to the reference nucleic acid.
The instant invention also provides vectors comprising such nucleic acids described above, which may be operably linked to a promoter (see, e.g., WO 86/05807; WO 89/01036; and U.S.P.N. 5, 122,464); and other transcriptional regulatory and processing control elements of the eukaryotic secretory pathway. The invention also provides host cells harboring those vectors and host- expression systems.
As used herein, the term "host-expression system" includes any kind of cellular system that can be engineered to generate either the nucleic acids or the polypeptides and antibodies of the invention. Such host-expression systems include, but are not limited to microorganisms (e.g., E. coli or B. subtilis) transformed or transfected with recombinant bacteriophage DNA or plasmid DNA; yeast (e.g., Saccharomyces) transfected with recombinant yeast expression vectors; or mammalian cells (e.g., COS, CHO-S, HEK293T, 3T3 cells) harboring recombinant expression constructs containing promoters derived from the genome of mammalian cells or viruses (e.g., the adenovirus late promoter). The host cell may be co-transfected with two expression vectors, for example, the first vector encoding a heavy chain derived polypeptide and the second vector encoding a light chain derived polypeptide.
Methods of transforming mammalian cells are well known in the art. See, for example, U.S.P.N.s. 4,399,216, 4,912,040, 4,740,461, and 4,959,455. The host cell may also be engineered to allow the production of an antigen binding molecule with various characteristics (e.g. modified glycoforms or proteins having GnTIII activity).
For long-term, high-yield production of recombinant proteins stable expression is preferred.
Accordingly, cell lines that stably express the selected antibody may be engineered using standard art recognized techniques and form part of the invention. Rather than using expression vectors that contain viral origins of replication, host cells can be transformed with DNA controlled by appropriate expression control elements (e.g., promoter or enhancer sequences, transcription terminators, polyadenylation sites, etc.), and a selectable marker. Any of the selection systems well known in the art may be used, including the glutamine synthetase gene expression system (the GS system) which provides an efficient approach for enhancing expression under selected conditions. The GS system is discussed in whole or part in connection with EP 0 216 846, EP 0 256 055, EP 0 323 997 and EP 0 338 841 and U.S.P.N.s 5,591,639 and 5,879,936. Another compatible expression system for the development of stable cell lines is the Freedom™ CHO-S Kit (Life Technologies).
Once an antibody of the invention has been produced by recombinant expression or any other of the disclosed techniques, it may be purified or isolated by methods known in the art in that it is identified and separated and/or recovered from its natural environment and separated from contaminants that would interfere with diagnostic or therapeutic uses for the antibody or related ADC. Isolated antibodies include antibodies in situ within recombinant cells.
These isolated preparations may be purified using various art-recognized techniques, such as, for example, ion exchange and size exclusion chromatography, dialysis, diafiltration, and affinity chromatography, particularly Protein A or Protein G affinity chromatography. Compatible methods are discussed more fully in the Examples below.
6. Post-production selection
No matter how obtained, antibody producing cells (e.g., hybridomas, yeast colonies, etc.) may be selected, cloned and further screened for desirable characteristics including, for example, robust growth, high antibody production and desirable antibody characteristics such as high affinity for the antigen of interest. Hybridomas can be expanded in vitro in cell culture or in vivo in syngeneic immunocompromised animals. Methods of selecting, cloning and expanding hybridomas and/or colonies are well known to those of ordinary skill in the art. Once the desired antibodies are identified the relevant genetic material may be isolated, manipulated and expressed using common, art-recognized molecular biology and biochemical techniques.
The antibodies produced by naive libraries (either natural or synthetic) may be of moderate affinity (Ka of about 106 to 107 M"1). To enhance affinity, affinity maturation may be mimicked in vitro by constructing antibody libraries (e.g., by introducing random mutations in vitro by using error-prone polymerase) and reselecting antibodies with high affinity for the antigen from those secondary libraries (e.g. by using phage or yeast display). WO 9607754 describes a method for inducing mutagenesis in a CDR of an immunoglobulin light chain to create a library of light chain genes.
Various techniques can be used to select antibodies, including but not limited to, phage or yeast display in which a library of human combinatorial antibodies or scFv fragments is synthesized on phages or yeast, the library is screened with the antigen of interest or an antibody-binding portion thereof, and the phage or yeast that binds the antigen is isolated, from which one may obtain the antibodies or immunoreactive fragments (Vaughan et a/. , 1996, PMID: 9630891; Sheets et a/., 1998, PMID: 9600934; Boder et a/., 1997, PMID: 9181578; Pepper et a/., 2008, PMID: 18336206). Kits for generating phage or yeast display libraries are commercially available. There also are other methods and reagents that can be used in generating and screening antibody display libraries (see U.S.P.N. 5,223,409; WO 92/18619, WO 91/17271, WO 92/20791, WO 92/15679, WO 93/01288, WO 92/01047, WO 92/09690; and Barbas et a/., 1991, PMID: 1896445). Such techniques advantageously allow for the screening of large numbers of candidate antibodies and provide for relatively easy manipulation of sequences (e.g., by recombinant shuffling).
IV. Characteristics of Antibodies
In certain embodiments, antibody-producing cells (e.g., hybridomas or yeast colonies) may be selected, cloned and further screened for favorable properties including, for example, robust growth, high antibody production and, as discussed in more detail below, desirable site-specific antibody characteristics. In other cases characteristics of the antibody may be imparted by selecting a particular antigen (e.g., a specific KREMEN2 isoform) or immunoreactive fragment of the target antigen for inoculation of the animal. In still other embodiments the selected antibodies may be engineered as described above to enhance or refine immunochemical characteristics such as affinity or pharmacokinetics.
A. Neutralizing antibodies
In selected embodiments the antibodies of the invention may be "antagonists" or "neutralizing" antibodies, meaning that the antibody may associate with a determinant and block or inhibit the activities of said determinant either directly or by preventing association of the determinant with a binding partner such as a ligand or a receptor, thereby interrupting the biological response that otherwise would result from the interaction of the molecules. A neutralizing or antagonist antibody will substantially inhibit binding of the determinant to its ligand or substrate when an excess of antibody reduces the quantity of binding partner bound to the determinant by at least about 20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 95%, 97%, 99% or more as measured, for example, by target molecule activity or in an in vitro competitive binding assay. It will be appreciated that the modified activity may be measured directly using art recognized techniques or may be measured by the impact the altered activity has downstream (e.g., oncogenesis or cell survival). Certain exemplary antibodies that block the binding of KREMEN2 to its ligand DKK1 are shown in the Examples below and the disclosed assay may be used to determine which antibodies are neutralizing in accordance with the instant invention.
B. Internalizing antibodies
In certain embodiments the antibodies may comprise internalizing antibodies such that the antibody will bind to a determinant and will be internalized (along with any conjugated pharmaceutically active moiety) into a selected target cell including tumorigenic cells. The number of antibody molecules internalized may be sufficient to kill an antigen-expressing cell, especially an antigen-expressing tumorigenic cell. Depending on the potency of the antibody or, in some instances, antibody drug conjugate, the uptake of a single antibody molecule into the cell may be sufficient to kill the target cell to which the antibody binds. With regard to the instant invention there is evidence that a substantial portion of expressed KREMEN2 protein remains associated with the tumorigenic cell surface, thereby allowing for localization and internalization of the disclosed antibodies or ADCs. In selected embodiments such antibodies will be associated with, or conjugated to, one or more drugs that kill the cell upon internalization. In some embodiments the ADCs of the instant invention will comprise an internalizing site-specific ADC.
As used herein, an antibody that "internalizes" is one that is taken up (along with any conjugated cytotoxin) by a target cell upon binding to an associated determinant. The number of such ADCs internalized will preferably be sufficient to kill the determinant-expressing cell, especially a determinant expressing cancer stem cell. Depending on the potency of the cytotoxin or ADC as a whole, in some instances the uptake of a few antibody molecules into the cell is sufficient to kill the target cell to which the antibody binds. For example, certain drugs such as PBDs or calicheamicin are so potent that the internalization of a few molecules of the toxin conjugated to the antibody is sufficient to kill the target cell. Whether an antibody internalizes upon binding to a mammalian cell can be determined by various art-recognized assays (e.g., saporin assays such as Mab-Zap and Fab-Zap; Advanced Targeting Systems) including those described in the Examples below. Methods of detecting whether an antibody internalizes into a cell are also described in U.S.P.N. 7,619,068.
C. Depleting antibodies
In other embodiments the antibodies of the invention are depleting antibodies. The term "depleting" antibody refers to an antibody that preferably binds to an antigen on or near the cell surface and induces, promotes or causes the death of the cell (e.g., by CDC, ADCC or introduction of a cytotoxic agent). In embodiments, the selected depleting antibodies will be conjugated to a cytotoxin.
Preferably a depleting antibody will be able to kill at least 20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 95%, 97%, or 99% of KREMEN2-expressing cells in a defined cell population. In some embodiments the cell population may comprise enriched, sectioned, purified or isolated tumorigenic cells, including cancer stem cells. In other embodiments the cell population may comprise whole tumor samples or heterogeneous tumor extracts that comprise cancer stem cells. Standard biochemical techniques may be used to monitor and quantify the depletion of tumorigenic cells in accordance with the teachings herein. D. Binding affinity
Disclosed herein are antibodies that have a high binding affinity for a specific determinant e.g. KREMEN2. The term "KD" refers to the dissociation constant or apparent affinity of a particular antibody-antigen interaction. An antibody of the invention can immunospecifically bind its target antigen when the dissociation constant KD (koff/kon) is < 10"7 M. The antibody specifically binds antigen with high affinity when the KD is < 5x10"9 M, and with very high affinity when the KD is < 5xlO"10 M. In one embodiment of the invention, the antibody has a KD of < 10"9 M and an off- rate of about lxlO"4 /sec. In one embodiment of the invention, the off-rate is < lxlO"5 /sec. In other embodiments of the invention, the antibodies will bind to a determinant with a KD of between about 10"7 M and 10"10 M, and in yet another embodiment it will bind with a KD < 2x10"10 M. Still other selected embodiments of the invention comprise antibodies that have a KD (k0ff/kon) of less than 10"6 M, less than 5xlO"6 M, less than 10"7 M, less than 5xlO"7 M, less than 10"8 M, less than 5xl0"8 M, less than 10"9 M, less than 5xl0"9 M, less than 10"10 M, less than 5xl0"10 M, less than 10"11 M, less than 5xl0"u M, less than 10"12 M, less than 5xlO"12 M, less than 10"13 M, less than 5xl0"13 M, less than 10" 14 M, less than 5xl0"14 M, less than 10"15 M or less than 5xl0"15 M. In certain embodiments, an antibody of the invention that immunospecifically binds to a determinant e.g. KREMEN2 may have an association rate constant or kon (or ka) rate (antibody + antigen (Ag)k on<— antibody- Ag) of at least 105 MV, at least 2xl05 MV, at least 5xl05 MV, at least 106MV, at least 5X106MV, at least 107MV, at least 5X107MV, or at least 108MV.
In another embodiment, an antibody of the invention that immunospecifically binds to a determinant e.g. KREMEN2 may have a disassociation rate constant or k0ff {or k rate (antibody + antigen (Ag)k off<— antibody-Ag) of less than 10"1 s" l, less than 5xl0_1 s" l, less than 10"2 s" l, less than 5xl0"2 s" l, less than 10"3 s" l, less than 5xl0"3 s" l, less than 10"4 s" l, less than 5xl04 s" l, less than 10"5 s" l, less than 5xl0"5 s" l, less than 10"6 s" l, less than 5xl0"6 s" 1 less than 10"7 s" l, less than 5xl0"7 s" l, less than 10"8 s" less than 5xl0"8 s" less than 10"9 s" less than 5xl0"9 s" 1 or less than 10"10 s" 1.
Binding affinity may be determined using various techniques known in the art, for example, surface plasmon resonance, bio-layer interferometry, dual polarization interferometry, static light scattering, dynamic light scattering, isothermal titration calorimetry, ELISA, analytical ultracentrifugation, and flow cytometry. E. Binning and epitope mapping
Antibodies disclosed herein may be characterized in terms of the discrete epitope with which they associate. An "epitope" is the portion(s) of a determinant to which the antibody or immunoreactive fragment specifically binds. Immunospecific binding can be confirmed and defined based on binding affinity, as described above, or by the preferential recognition by the antibody of its target antigen in a complex mixture of proteins and/or macromolecules (e.g. in competition assays). A "linear epitope", is formed by contiguous amino acids in the antigen that allow for immunospecific binding of the antibody. The ability to preferentially bind linear epitopes is typically maintained even when the antigen is denatured. Conversely, a "conformational epitope", usually comprises non-contiguous amino acids in the antigen's amino acid sequence but, in the context of the antigen's secondary, tertiary or quaternary structure, are sufficiently proximate to be bound concomitantly by a single antibody. When antigens with conformational epitopes are denatured, the antibody will typically no longer recognize the antigen. An epitope (contiguous or non-contiguous) typically includes at least 3, and more usually, at least 5 or 8-10 or 12-20 amino acids in a unique spatial conformation.
It is also possible to characterize the antibodies of the invention in terms of the group or "bin" to which they belong. "Binning" refers to the use of competitive antibody binding assays to identify pairs of antibodies that are incapable of binding an immunogenic determinant simultaneously, thereby identifying antibodies that "compete" for binding. Competing antibodies may be determined by an assay in which the antibody or immunologically functional fragment being tested prevents or inhibits specific binding of a reference antibody to a common antigen. Typically, such an assay involves the use of purified antigen (e.g., KREMEN2 or a domain or fragment thereof) bound to a solid surface or cells, an unlabeled test antibody and a labeled reference antibody. Competitive inhibition is measured by determining the amount of label bound to the solid surface or cells in the presence of the test antibody. Additional details regarding methods for determining competitive binding are provided in the Examples herein. Usually, when a competing antibody is present in excess, it will inhibit specific binding of a reference antibody to a common antigen by at least 30%, 40%, 45%, 50%, 55%, 60%, 65%, 70% or 75%. In some instance, binding is inhibited by at least 80%, 85%, 90%, 95%, or 97% or more. Conversely, when the reference antibody is bound it will preferably inhibit binding of a subsequently added test antibody (i.e., a KREMEN2 antibody) by at least 30%, 40%, 45%, 50%, 55%, 60%, 65%, 70% or 75%. In some instance, binding of the test antibody is inhibited by at least 80%, 85%, 90%, 95%, or 97% or more.
Generally binning or competitive binding may be determined using various art-recognized techniques, such as, for example, immunoassays such as western blots, radioimmunoassays, enzyme linked immunosorbent assay (ELISA), "sandwich" immunoassays, immunoprecipitation assays, precipitin reactions, gel diffusion precipitin reactions, immunodiffusion assays, agglutination assays, complement-fixation assays, immunoradiometric assays, fluorescent immunoassays and protein A immunoassays. Such immunoassays are routine and well known in the art (see, Ausubel et al, eds, (1994) Current Protocols in Molecular Biology, Vol. 1, John Wiley & Sons, Inc., New York). Additionally, cross-blocking assays may be used (see, for example, WO 2003/48731; and Harlow et al. (1988) Antibodies, A Laboratory Manual, Cold Spring Harbor Laboratory, Ed Harlow and David Lane).
Other technologies used to determine competitive inhibition (and hence "bins"), include: surface plasmon resonance using, for example, the BIAcore™ 2000 system (GE Healthcare); bio- layer interferometry using, for example, a ForteBio® Octet RED (ForteBio); or flow cytometry bead arrays using, for example, a FACSCanto II (BD Biosciences) or a multiplex LUMINEX™ detection assay (Luminex). Luminex is a bead-based immunoassay platform that enables large scale multiplexed antibody pairing. The assay compares the simultaneous binding patterns of antibody pairs to the target antigen. One antibody of the pair (capture mAb) is bound to Luminex beads, wherein each capture mAb is bound to a bead of a different color. The other antibody (detector mAb) is bound to a fluorescent signal (e.g. phycoerythrin (PE)). The assay analyzes the simultaneous binding (pairing) of antibodies to an antigen and groups together antibodies with similar pairing profiles. Similar profiles of a detector mAb and a capture mAb indicates that the two antibodies bind to the same or closely related epitopes. In one embodiment, pairing profiles can be determined using Pearson correlation coefficients to identify the antibodies which most closely correlate to any particular antibody on the panel of antibodies that are tested. In embodiments a test/detector mAb will be determined to be in the same bin as a reference/capture mAb if the Pearson's correlation coefficient of the antibody pair is at least 0.9. In other embodiments the Pearson's correlation coefficient is at least 0.8, 0.85, 0.87 or 0.89. In further embodiments, the Pearson's correlation coefficient is at least 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99 or 1. Other methods of analyzing the data obtained from the Luminex assay are described in U.S. P.N. 8,568,992. The ability of Luminex to analyze 100 different types of beads (or more) simultaneously provides almost unlimited antigen and/or antibody surfaces, resulting in improved throughput and resolution in antibody epitope profiling over a biosensor assay (Miller, et al., 2011, PMID: 21223970).
Similarly binning techniques comprising surface plasmon resonance are compatible with the instant invention. As used herein "surface plasmon resonance," refers to an optical phenomenon that allows for the analysis of real-time specific interactions by detection of alterations in protein concentrations within a biosensor matrix. Using commercially available equipment such as the BIAcore™ 2000 system it may readily be determined if selected antibodies compete with each other for binding to a defined antigen.
In other embodiments, a technique that can be used to determine whether a test antibody
"competes" for binding with a reference antibody is "bio-layer interferometry", an optical analytical technique that analyzes the interference pattern of white light reflected from two surfaces: a layer of immobilized protein on a biosensor tip, and an internal reference layer. Any change in the number of molecules bound to the biosensor tip causes a shift in the interference pattern that can be measured in real-time. Such biolayer interferometry assays may be conducted using a ForteBio® Octet RED machine as follows. A reference antibody (Abl) is captured onto an anti -mouse capture chip, a high concentration of non-binding antibody is then used to block the chip and a baseline is collected. Monomeric, recombinant target protein is then captured by the specific antibody (Abl) and the tip is dipped into a well with either the same antibody (Abl) as a control or into a well with a different test antibody (Ab2). If no further binding occurs, as determined by comparing binding levels with the control Abl, then Abl and Ab2 are determined to be "competing" antibodies. If additional binding is observed with Ab2, then Abl and Ab2 are determined not to compete with each other. This process can be expanded to screen large libraries of unique antibodies using a full row of antibodies in a 96-well plate representing unique bins. In embodiments a test antibody will compete with a reference antibody if the reference antibody inhibits specific binding of the test antibody to a common antigen by at least 40%, 45%, 50%, 55%, 60%, 65%, 70% or 75%. In other embodiments, binding is inhibited by at least 80%, 85%, 90%, 95%, or 97% or more.
Once a bin, encompassing a group of competing antibodies, has been defined further characterization can be carried out to determine the specific domain or epitope on the antigen to which that group of antibodies binds. Domain-level epitope mapping may be performed using a modification of the protocol described by Cochran et al., 2004, PMTD: 15099763. Fine epitope mapping is the process of determining the specific amino acids on the antigen that comprise the epitope of a determinant to which the antibody binds.
In certain embodiments fine epitope mapping can be performed using phage or yeast display. Other compatible epitope mapping techniques include alanine scanning mutants, peptide blots (Reineke, 2004, PMTD: 14970513), or peptide cleavage analysis. In addition, methods such as epitope excision, epitope extraction and chemical modification of antigens can be employed (Tomer, 2000, PMID: 10752610) using enzymes such as proteolytic enzymes (e.g., trypsin, endoproteinase Glu-C, endoproteinase Asp-N, chymotrypsin, etc.); chemical agents such as succinimidyl esters and their derivatives, primary amine-containing compounds, hydrazines and carbohydrazines, free amino acids, etc. In another embodiment Modification-Assisted Profiling, also known as Antigen Structure-based Antibody Profiling (ASAP) can be used to categorize large numbers of monoclonal antibodies directed against the same antigen according to the similarities of the binding profile of each antibody to chemically or enzymatically modified antigen surfaces (U.S.P.N. 2004/0101920).
Once a desired epitope on an antigen is determined, it is possible to generate additional antibodies to that epitope, e.g., by immunizing with a peptide comprising the selected epitope using techniques described herein.
V. Antibody conjugates
In some embodiments the antibodies of the invention may be conjugated with pharmaceutically active or diagnostic moieties to form an "antibody drug conjugate" (ADC) or "antibody conjugate". The term "conjugate" is used broadly and means the covalent or non- covalent association of any pharmaceutically active or diagnostic moiety with an antibody of the instant invention regardless of the method of association. In certain embodiments the association is effected through a lysine or cysteine residue of the antibody. In some embodiments the pharmaceutically active or diagnostic moieties may be conjugated to the antibody via one or more site-specific free cysteine(s). The disclosed ADCs may be used for therapeutic and diagnostic purposes.
It will be appreciated that the ADCs of the instant invention may be used to selectively deliver predetermined warheads to the target location (e.g., tumorigenic cells and/or cells expressing KREMEN2). As set forth herein the terms "drug" or "warhead" may be used interchangeably and will mean any biologically active (e.g., a pharmaceutically active compound or therapeutic moiety) or detectable molecule or compound that has a physiological effect or reporter function when introduced into a subject. For the avoidance of doubt such warheads include the anti -cancer agents or cytotoxins as described below. A "payload" may comprise a drug or warhead in combination with an optional linker compound (e.g., a therapeutic payload) that preferably provides a relatively stable pharmaceutical complex until the ADC reaches the target. By way of example the warhead or drug on the conjugate may comprise peptides, proteins or prodrugs which are metabolized to an active agent in vivo, polymers, nucleic acid molecules, small molecules, binding agents, mimetic agents, synthetic drugs, inorganic molecules, organic molecules and radioisotopes. In certain embodiments the drug or warhead will be covalently conjugated to the antibody through a linker. In other embodiments (e.g., a radioisotope) the drug or warhead will be directly conjugated to, or incorporated in, the antibody.
In preferred embodiments the disclosed ADCs will direct the bound payload (e.g., drug linker) to the target site in a relatively unreactive, non-toxic state before releasing and activating the warhead (e.g., PBDS 1-5 as disclosed herein). This targeted release of the warhead is preferably achieved through stable conjugation of the payloads (e.g., via one or more cysteines or lysines on the antibody) and relatively homogeneous composition of the ADC preparations which minimize over-conjugated toxic ADC species. Coupled with drug linkers that are designed to largely release the warhead upon delivery to the tumor site, the conjugates of the instant invention can substantially reduce undesirable non-specific toxicity. This advantageously provides for relatively high levels of the active cytotoxin at the tumor site while minimizing exposure of non-targeted cells and tissue thereby providing an enhanced therapeutic index.
As alluded to above, while some embodiments of the invention comprise payloads incorporating therapeutic moieties (e.g., cytotoxins), other payloads incorporating diagnostic agents and biocompatible modifiers may benefit from the targeted delivery provided by the disclosed conjugates. Accordingly, any disclosure directed to exemplary therapeutic payloads is also applicable to payloads comprising diagnostic agents or biocompatible modifiers as discussed herein unless otherwise dictated by context. The selected payload may be covalently or non-covalently linked to the antibody and exhibit various stoichiometric molar ratios depending, at least in part, on the method used to effect the conjugation.
Conjugates of the instant invention may be generally represented by the formula:
Ab-[L-D]n or a pharmaceutically acceptable salt thereof wherein:
a) Ab comprises an anti-KREMEN2 antibody;
b) L comprises an optional linker;
c) D comprises a drug; and
d) n is an integer from about 1 to about 20.
Those of skill in the art will appreciate that conjugates according to the aforementioned formula may be fabricated using a number of different linkers and drugs and that conjugation methodology will vary depending on the selection of components. As such, any drug or drug linker compound that associates with a reactive residue (e.g., cysteine or lysine) of the disclosed antibodies are compatible with the teachings herein. Similarly, any reaction conditions that allow for conjugation (including site-specific conjugation) of the selected drug to an antibody are within the scope of the present invention. Notwithstanding the foregoing, some preferred embodiments of the instant invention comprise selective conjugation of the drug or drug linker to free cysteines using stabilization agents in combination with mild reducing agents as described herein. Such reaction conditions tend to provide more homogeneous preparations with less non-specific conjugation and contaminants and correspondingly less toxicity.
A. Payloads and warheads
1. Therapeutic agents
As discussed the antibodies of the invention may be conjugated, linked or fused to or otherwise associated with any pharmaceutically active compound comprising a therapeutic moiety or a drug such as an anti-cancer agent including, but not limited to, cytotoxic agents (or cytotoxins), cytostatic agents, anti-angiogenic agents, debulking agents, chemotherapeutic agents, radiotherapeutic agents, targeted anti-cancer agents, biological response modifiers, cancer vaccines, cytokines, hormone therapies, anti-metastatic agents and immunotherapeutic agents.
Exemplary anti-cancer agents or cytotoxins (including homologs and derivatives thereof) comprise 1-dehydrotestosterone, anthramycins, actinomycin D, bleomycin, calicheamicins (including n-acetyl calicheamicin), colchicin, cyclophosphamide, cytochalasin B, dactinomycin (formerly actinomycin), dihydroxy anthracin, dione, duocarmycin, emetine, epirubicin, ethidium bromide, etoposide, glucocorticoids, gramicidin D, lidocaine, maytansinoids such as DM-1 and DM-4 (Immunogen), benzodiazepine derivatives (Immunogen), mithramycin, mitomycin, mitoxantrone, paclitaxel, procaine, propranolol, puromycin, tenoposide, tetracaine and pharmaceutically acceptable salts or solvates, acids or derivatives of any of the above.
Additional compatible cytotoxins comprise dolastatins and auristatins, including monomethyl auristatin E (MMAE) and monomethyl auristatin F (MMAF) (Seattle Genetics), amanitins such as alpha-amanitin, beta-amanitin, gamma-amanitin or epsilon-amanitin (Heidelberg Pharma), DNA minor groove binding agents such as duocarmycin derivatives (Syntarga), alkylating agents such as modified or dimeric pyrrolobenzodiazepines (PBD), mechlorethamine, thioepa, chlorambucil, melphalan, carmustine (BCNU), lomustine (CCNU), cyclothosphamide, busulfan, dibromomannitol, streptozotocin, mitomycin C and cisdichlorodiamine platinum (II) (DDP) cisplatin, splicing inhibitors such as meayamycin analogs or derivatives (e.g., FR901464 as set forth in U.S.P.N. 7,825,267), tubular binding agents such as epothilone analogs and tubulysins, paclitaxel and DNA damaging agents such as calicheamicins and esperamicins, antimetabolites such as methotrexate, 6-mercaptopurine, 6-thioguanine, cytarabine, and 5-fluorouracil decarbazine, anti- mitotic agents such as vinblastine and vincristine and anthracyclines such as daunombicin (formerly daunomycin) and doxorubicin and pharmaceutically acceptable salts or solvates, acids or derivatives of any of the above.
In selected embodiments the antibodies of the instant invention may be associated with anti- CD3 binding molecules to recruit cytotoxic T-cells and have them target tumorigenic cells (BiTE technology; see e.g., Fuhrmann et. al. (2010) Annual Meeting of AACR Abstract No. 5625).
In further embodiments ADCs of the invention may comprise cytotoxins comprising therapeutic radioisotopes conjugated using appropriate linkers. Exemplary radioisotopes that may
131 125 123 121 be compatible with such embodiments include, but are not limited to, iodine ( I, I, I, I,), carbon (14C), copper (62Cu, 64Cu, 67Cu), sulfur (35S), radium (223R), tritium (3H), indium (115In, 113In, 112In, mIn,), bismuth (212Bi, 213Bi), technetium (99Tc), thallium (201Ti), gallium (68Ga, 67Ga), palladium (103Pd), molybdenum (99Mo), xenon (133Xe), fluorine (18F), 153 Sm, 177Lu, 159Gd, 149Pm, 140La, 175Yb, 166Ho, 90Y, 47Sc, 186Re, 188Re, 142 Pr, 105Rh, 97Ru, 68Ge, 57Co, 65Zn, 85Sr, 32P, 153Gd, 169Yb, 51Cr, 54Mn, 75Se, 113Sn, 117Sn, 76Br, 211At and 225 Ac. Other radionuclides are also available as diagnostic and therapeutic agents, especially those in the energy range of 60 to 4,000 keV.
In other selected embodiments the ADCs of the instant invention will be conjugated to a cytotoxic benzodiazepine derivative warhead. Compatible benzodiazepine derivatives (and optional linkers) that may be conjugated to the disclosed antibodies are described, for example, in U. S.P.N. 8,426,402 and PCT filings WO2012/128868 and WO2014/031566. As with PBDs, compatible benzodiazepine derivatives are believed to bind in the minor grove of DNA and inhibit nucleic acid synthesis. Such compounds reportedly have potent antitumor properties and, as such, are particularly suitable for use in the ADCs of the instant invention.
In some embodiments, the ADCs of the invention may comprise PBDs, and pharmaceutically acceptable salts or solvates, acids or derivatives thereof, as warheads. PBDs are alkylating agents that exert antitumor activity by covalently binding to DNA in the minor groove and inhibiting nucleic acid synthesis. PBDs have been shown to have potent antitumor properties while exhibiting minimal bone marrow depression. PBDs compatible with the invention may be linked to an antibody using several types of linkers (e.g., a peptidyl linker comprising a maleimido moiety with a free sulfhydryl), and in certain embodiments are dimeric in form (i.e., PBD dimers). Compatible PBDs (and optional linkers) that may be conjugated to the disclosed antibodies are described, for example, in U.S.P.N.s 6,362,331, 7,049,311, 7, 189,710, 7,429,658, 7,407,951, 7,741,319, 7,557,099, 8,034,808, 8, 163,736, 2011/0256157 and PCT filings WO2011/130613, WO2011/128650, WO2011/130616, WO2014/057073 and WO2014/057074. Examples of PBD compounds compatible with the instant invention are discussed in more detail immediately below.
With regard to the instant invention PBDs have been shown to have potent antitumor properties while exhibiting minimal bone marrow depression. PBDs compatible with the present invention may be linked to the KREMEN2 targeting agent using any one of several types of linker (e.g., a peptidyl linker comprising a maleimido moiety with a free sulfhydryl) and, in certain embodiments are dimeric in form (i.e., of the general structure:
Figure imgf000057_0001
They differ in the number, type and position of substituents, in both their aromatic A rings and pyrrolo C rings, and in the degree of saturation of the C ring. In the B-ring there is either an imine (N=C), a carbinolamine (NH-CH(OH)), or a carbinolamine methyl ether (NH-CH(OMe)) at the N10-C11 position which is the electrophilic center responsible for alkylating DNA. All of the known natural products have an (^-configuration at the chiral CI la position which provides them with a right-handed twist when viewed from the C ring towards the A ring. This gives them the appropriate three-dimensional shape for isohelicity with the minor groove of B-form DNA, leading to a snug fit at the binding site (Kohn, In Antibiotics III. Springer- Verlag, New York, pp. 3-11 (1975); Hurley and Needham-VanDevanter, Acc. Chem. Res., 19, 230-237 (1986)). Their ability to form an adduct in the minor groove enables them to interfere with DNA processing and act as cytotoxic agents. As alluded to above, in order to increase their potency PBDs are often used in a dimeric form which may be conjugated to anti- KREMEN2 antibodies as described herein.
In particularly preferred embodiments compatible PBDs that may be conjugated to the disclosed modulators are described, in U.S. P.N. 2011/0256157. In this disclosure, PBD dimers, i.e. those comprising two PBD moieties may be preferred. Thus, preferred conjugates of the present invention are those having the formula (AB) or (AC):
Figure imgf000058_0001
Figure imgf000058_0002
wherein:
the dotted lines indicate the optional presence of a double bond between CI and C2 or
C2 and C3;
R2 is independently selected from H, OH, =0, =CH2, CN, R, OR, =CH-RD, =C(RD)2, 0-S02-R, C02R and COR, and optionally further selected from halo or dihalo;
where RD is independently selected from R, C02R, COR, CHO, C02H, and halo;
R6 and R9 are independently selected from H, R, OH, OR, SH, SR, H2, NHR, NRR',
N02, Me3Sn and halo;
R7 is independently selected from H, R, OH, OR, SH, SR, NH2, NHR, NRR', N02, Me3Sn and halo;
R10 is a linker connected to a KREMEN2 antibody or fragment or derivative thereof, as described herein;
Q is independently selected from O, S and NH;
R11 is either H, or R or, where Q is O, S03M, where M is a metal cation; X is selected from O, S, or N(H) and in selected embodiments comprises O;
R" is a C3-12 alkylene group, which chain may be interrupted by one or more heteroatoms (e.g., O, S, N(H), Me and/or aromatic rings, e.g. benzene or pyridine, which rings are optionally substituted);
R and R' are each independently selected from optionally substituted C1-12 alkyl,
C3-20 heterocyclyl and C5-20 aryl groups, and optionally in relation to the group NRR', R and R' together with the nitrogen atom to which they are attached form an optionally substituted 4-, 5-, 6- or 7-membered heterocyclic ring; and
9" 7" Q" 1 1 " ? wherein R , R , R , R , X", Q" and R (where present) are as defined according to R , R6, R7, R9, X, Q and R11 respectively, and Rc is a capping group.
Selected embodiments comprising the aforementioned structures are described in more detail immediately below.
Double Bond
In one embodiment, there is no double bond present between CI and C2, and C2 and C3. In one embodiment, the dotted lines indicate the optional presence of a double bond between and C3, as shown below:
Figure imgf000059_0001
In one embodiment, a double bond is present between C2 and C3 when R2 is C5-20 aryl or Ci. 12 alkyl. In a preferred embodiment R2 comprises a methyl group.
In one embodiment, the dotted lines indicate the optional presence of a double bond between CI and C2, as shown below:
Figure imgf000059_0002
In one embodiment, a double bond is present between CI and C2 when R2 is C5-2o aryl or Ci. 12 alkyl. In a preferred embodiment R2 comprises a methyl group. R:
In one embodiment, R2 is independently selected from H, OH, =0, =CH2, CN, R, OR, =CH- RD, =C(RD)2, 0-S02-R, C02R and COR, and optionally further selected from halo or dihalo.
In one embodiment, R2 is independently selected from H, OH, =0, =CH2, CN, R, OR, =CH- RD, =C(RD)2, 0-S02-R, C02R and COR.
In one embodiment, R2 is independently selected from H, =0, =CH2, R, =CH-RD, and =C(RD)2.
In one embodiment, R2 is independently H.
In one embodiment R2 is independently R wherein R comprises CH3.
In one embodiment, R2 is independently =0.
In one embodiment, R2 is independently =CH2.
In one embodiment, R2 is independently =CH-RD. Within the PBD compound, the group =CH-RD may have either configuration shown below:
Figure imgf000060_0001
(I) (")
In one embodiment, the configuration is configuration (I).
In one embodiment, R2 is independently =C(RD)2.
In one embodiment, R2 is independently =CF2.
In one embodiment, R2 is independently R.
In one embodiment, R2 is independently optionally substituted 05-2ο aryl.
In one embodiment, R2 is independently optionally substituted C1-12 alkyl.
In one embodiment, R2 is independently optionally substituted C5-20 aryl.
In one embodiment, R2 is independently optionally substituted C5 -7 aryl.
In one embodiment, R2 is independently optionally substituted C8-io aryl.
In one embodiment, R2 is independently optionally substituted phenyl.
In one embodiment, R2 is independently optionally substituted napthyl.
In one embodiment, R2 is independently optionally substituted pyridyl. In one embodiment, R2 is independently optionally substituted quinolinyl or isoquinolinyl.
In one embodiment, R2 bears one to three substituent groups, with 1 and 2 being more preferred, and singly substituted groups being most preferred. The substituents may be any position.
Where R2 is a C5-7 aryl group, a single substituent is preferably on a ring atom that is not adjacent the bond to the remainder of the compound, i.e. it is preferably β or γ to the bond to the remainder of the compound. Therefore, where the C5-7 aryl group is phenyl, the substituent is preferably in the meta- or para- positions, and more preferably is in the para- position.
In one embodiment, R2 is selected from:
Figure imgf000061_0001
where the asterisk indicates the point of attachment.
Where R2 is a C8-io aryl group, for example quinolinyl or isoquinolinyl, it may bear any number of substituents at any position of the quinoline or isoquinoline rings. In some embodiments, it bears one, two or three substituents, and these may be on either the proximal and distal rings or both (if more than one substituent).
In one embodiment, where R2 is optionally substituted, the substituents are selected from those substituents given in the substituent section below.
Where R is optionally substituted, the substituents are preferably selected from:
Halo, Hydroxyl, Ether, Formyl, Acyl, Carboxy, Ester, Acyloxy, Amino, Amido, Acylamido, Aminocarbonyloxy, Ureido, Nitro, Cyano and Thioether.
In one embodiment, where R or R2 is optionally substituted, the substituents are selected from the group consisting of R, OR, SR, NRR', N02, halo, C02R, COR, CO H2, CO HR, and CONRR'.
Where R2 is C i-i2 alkyl, the optional substituent may additionally include C3-2o heterocyclyl and C5-20 aryl groups.
Where R2 is C3-2o heterocyclyl, the optional substituent may additionally include C1-12 alkyl and C5-2o aryl groups.
Where R2 is C5-20 aryl groups, the optional substituent may additionally include C3-20 heterocyclyl and C1-12 alkyl groups. It is understood that the term "alkyl" encompasses the sub-classes alkenyl and alkynyl as well as cycloalkyl. Thus, where R2 is optionally substituted C1-12 alkyl, it is understood that the alkyl group optionally contains one or more carbon-carbon double or triple bonds, which may form part of a conjugated system. In one embodiment, the optionally substituted C1-12 alkyl group contains at least one carbon-carbon double or triple bond, and this bond is conjugated with a double bond present between CI and C2, or C2 and C3. In one embodiment, the C1-12 alkyl group is a group selected from saturated C1-12 alkyl, C2.12 alkenyl, C2.12 alkynyl and C3.12 cycloalkyl.
If a substituent on R2 is halo, it is preferably F or CI, more preferably CI.
If a substituent on R2 is ether, it may in some embodiments be an alkoxy group, for example, a Ci-7 alkoxy group (e.g. methoxy, ethoxy) or it may in some embodiments be a C5-7 aryloxy group (e.g phenoxy, pyridyloxy, furanyloxy).
If a substituent on R2 is C1-7 alkyl, it may preferably be a C1-4 alkyl group (e.g. methyl, ethyl, propyl, butyl).
If a substituent on R2 is C3-7 heterocyclyl, it may in some embodiments be C6 nitrogen containing heterocyclyl group, e.g. morpholino, thiomorpholino, piperidinyl, piperazinyl. These groups may be bound to the rest of the PBD moiety via the nitrogen atom. These groups may be further substituted, for example, by C1-4 alkyl groups.
If a substituent on R2 is bis-oxy-Ci-3 alkylene, this is preferably bis-oxy-methylene or bis-oxy- ethylene.
Particularly preferred substituents for R2 include methoxy, ethoxy, fluoro, chloro, cyano, bis- oxy-methylene, methyl-piperazinyl, morpholino and methyl-thienyl.
Particularly preferred substituted R2 groups include, but are not limited to, 4-methoxy-phenyl, 3-methoxyphenyl, 4-ethoxy-phenyl, 3-ethoxy-phenyl, 4-fluoro-phenyl, 4-chloro-phenyl, 3,4- bisoxymethylene-phenyl, 4-methylthienyl, 4-cyanophenyl, 4-phenoxyphenyl, quinolin-3-yl and quinolin-6-yl, isoquinolin-3-yl and isoquinolin-6-yl, 2-thienyl, 2-furanyl, methoxynaphthyl, and naphthyl.
In one embodiment, R2 is halo or dihalo. In one embodiment, R2 is -F or -F2, which substituents are illustrated below as (III) and (IV) respectively:
Figure imgf000063_0001
(III) (IV)
In one embodiment, R is independently selected from R, C02R, COR, CHO, C02H, and halo.
In one embodiment, RD is independently R.
In one embodiment, RD is independently halo.
In one embodiment, R6 is independently selected from H, R, OH, OR, SH, SR, NH2, NHR, NRR', N02, Me3Sn- and Halo.
In one embodiment, R6 is independently selected from H, OH, OR, SH, NH2, N02 and Halo. In one embodiment, R6 is independently selected from H and Halo.
In one embodiment, R6 is independently H.
In one embodiment, R6 and R7 together form a group -0-(CH2)p-0-, where p is 1 or 2.
R' is independently selected from H, R, OH, OR, SH, SR, NH2, NHR, NRR', N02, Me3Sn and halo.
In one embodiment, R7 is independently OR.
In one embodiment, R7 is independently OR7A, where R7A is independently optionally substituted Ci-6 alkyl.
In one embodiment, R7A is independently optionally substituted saturated Ci-6 alkyl.
In one embodiment, R7A is independently optionally substituted C2-4 alkenyl.
In one embodiment, R7A is independently Me.
In one embodiment, R7A is independently CH2Ph.
In one embodiment, R7A is independently allyl. In one embodiment, the compound is a dimer where the R groups of each monomer form together a dimer bridge having the formula X-R"-X linking the monomers.
In one embodiment, R9 is independently selected from H, R, OH, OR, SH, SR, H2, HR,
NRR', N02, Me3Sn- and Halo.
In one embodiment, R9 is independently H.
In one embodiment, R9 is independently R or OR.
Preferably compatible linkers such as those described herein attach the KREMEN2 antibody to the PBD drug moiety through covalent bond(s) at the R10 position (i.e., N10).
Q
In certain embodiments Q is independently selected from O, S and NH.
In one embodiment, Q is independently O.
In one embodiment, Q is independently S.
In one embodiment, Q is independently NH.
In selected embodiments R11 is either H, or R or, where Q is O, may be S03M where M is a metal cation. The cation may be Na+.
In certain embodiments R11 is H.
In certain embodiments R11 is R.
In certain embodiments, where Q is O, R11 is S03M where M is a metal cation. The cation may be Na+.
In certain embodiments where Q is O, R11 is H.
In certain embodiments where Q is O, R11 is R. X In one embodiment, X is selected from O, S, or N(H).
Preferably, X is O. l
R" is a C3-12 alkylene group, which chain may be interrupted by one or more heteroatoms, e.g. O, S, N(H), NMe and/or aromatic rings, e.g. benzene or pyridine, which rings are optionally substituted.
In one embodiment, R" is a C3-i2 alkylene group, which chain may be interrupted by one or more heteroatoms and/or aromatic rings, e.g. benzene or pyridine.
In one embodiment, the alkylene group is optionally interrupted by one or more heteroatoms selected from O, S, and NMe and/or aromatic rings, which rings are optionally substituted.
In one embodiment, the aromatic ring is a C5-2o arylene group, where arylene pertains to a divalent moiety obtained by removing two hydrogen atoms from two aromatic ring atoms of an aromatic compound, which moiety has from 5 to 20 ring atoms.
In one embodiment, R" is a C3-i2 alkylene group, which chain may be interrupted by one or more heteroatoms, e.g. O, S, N(H), NMe and/or aromatic rings, e.g. benzene or pyridine, which rings are optionally substituted by NH2.
In one embodiment, R" is a C3-i2 alkylene group.
In one embodiment, R" is selected from a C3, C5, C7, C9 and a Cn alkylene group.
In one embodiment, R" is selected from a C3, C5 and a C7 alkylene group.
In one embodiment, R" is selected from a C3 and a C5 alkylene group.
In one embodiment, R" is a C3 alkylene group.
In one embodiment, R" is a C5 alkylene group.
The alkylene groups listed above may be optionally interrupted by one or more heteroatoms and/or aromatic rings, e.g. benzene or pyridine, which rings are optionally substituted.
The alkylene groups listed above may be optionally interrupted by one or more heteroatoms and/or aromatic rings, e.g. benzene or pyridine.
The alkylene groups listed above may be unsubstituted linear aliphatic alkylene groups.
R and R' In one embodiment, R is independently selected from optionally substituted C1-12 alkyl, C3-20 heterocyclyl and C5-20 aryl groups.
In one embodiment, R is independently optionally substituted C1-12 alkyl.
In one embodiment, R is independently optionally substituted C3-2o heterocyclyl.
In one embodiment, R is independently optionally substituted C5-20 aryl.
Described above in relation to R2 are various embodiments relating to preferred alkyl and aryl groups and the identity and number of optional substituents. The preferences set out for R2 as it applies to R are applicable, where appropriate, to all other groups R, for examples where R6, R7, R8 or R9 is R.
The preferences for R apply also to R' .
In some embodiments of the invention there is provided a compound having a substituent group -NRR'. In one embodiment, R and R' together with the nitrogen atom to which they are attached form an optionally substituted 4-, 5-, 6- or 7-membered heterocyclic ring. The ring may contain a further heteroatom, for example N, O or S.
In one embodiment, the heterocyclic ring is itself substituted with a group R. Where a further
N heteroatom is present, the substituent may be on the N heteroatom.
In addition to the aforementioned PBDs certain dimeric PBDs have been shown to be particularly active and may be used in conjunction with the instant invention. To this end antibody drug conjugates (i.e., ADCs 1 - 6 as disclosed herein) of the instant invention may comprise a PBD compound set forth immediately below as PBD 1 - 5. Note that PBDs 1-5 below comprise the cytotoxic warhead released following separation of a linker such as those described in more detail herein. The synthesis of each of PBD 1 - 5 as a component of drug-linker compounds is presented in great detail in WO 2014/130879 which is hereby incorporated by reference as to such synthesis.
In view of WO 2014/130879 cytotoxic compounds that may comprise selected warheads of the ADCs of the present invention could readily be generated and employed as set forth herein.
Accordingly, selected PBD compounds that may be released from the disclosed ADCs upon separation from a linker are set forth immediately below:
Figure imgf000067_0001
Figure imgf000067_0002
Figure imgf000067_0003
Figure imgf000067_0004
Figure imgf000067_0005
PBD5
It will be appreciated that each of the aforementioned dimeric PBD warheads would be preferably be released upon internalization by the target cell and destruction of the linker. As described in more detail below, certain linkers will comprise cleavable linkers which may incorporate a self-immolation moiety that allows release of the active PBD warhead without retention of any part of the linker. Upon release the PBD warhead will then bind and cross-link with the target cell's DNA. Such binding reportedly blocks division of the target cancer cell without distorting its DNA helix, thus potentially avoiding the common phenomenon of emergent drug resistance. In other preferred embodiments the warhead may be attached to the KREMEN2 targeting moiety through a cleavable linker that does not comprise a self-immolating moiety.
Delivery and release of such compounds at the tumor site(s) may prove clinically effective in treating or managing proliferative disorders in accordance with the instant disclosure. With regard to the compounds it will be appreciated that each of the disclosed PBDs have two sp2 centers in each C-ring, which may allow for stronger binding in the minor groove of DNA (and hence greater toxicity), than for compounds with only one sp2 center in each C-ring. Thus, when used in KREMEN2 ADCs as set forth herein the disclosed PBDs may prove to be particularly effective for the treatment of proliferative disorders.
The foregoing provides exemplary PBD compounds that are compatible with the instant invention and is in no way meant to be limiting as to other PBDs that may be successfully incorporated in anti- KREMEN2 conjugates according to the teachings herein. Rather, any PBD that may be conjugated to an antibody as described herein and set forth in the Examples below is compatible with the disclosed conjugates and expressly within the metes and bounds of the invention.
In addition to the aforementioned agents the antibodies of the present invention may also be conjugated to biological response modifiers. In certain embodiments the biological response modifier will comprise interleukin 2, interferons, or various types of colony-stimulating factors (e.g., CSF, GM-CSF, G-CSF).
More generally, the associated drug moiety can be a polypeptide possessing a desired biological activity. Such proteins may include, for example, a toxin such as abrin, ricin A, Onconase (or another cytotoxic RNase), pseudomonas exotoxin, cholera toxin, diphtheria toxin; an apoptotic agent such as tumor necrosis factor e.g. TNF- a or TNF-β, a-interferon, β-interferon, nerve growth factor, platelet derived growth factor, tissue plasminogen activator, AFM I (WO 97/33899), AFM II (WO 97/34911), Fas Ligand (Takahashi et al, 1994, PMID: 7826947), and VEGI (WO 99/23105), a thrombotic agent, an anti -angiogenic agent, e.g., angiostatin or endostatin, a lymphokine, for example, interleukin- 1 (IL-1), interleukin-2 (IL-2), interleukin-6 (IL-6), granulocyte macrophage colony stimulating factor (GM-CSF), and granulocyte colony stimulating factor (G-CSF), or a growth factor e.g., growth hormone (GH).
2. Diagnostic or detection agents
In other embodiments, the antibodies of the invention, or fragments or derivatives thereof, are conjugated to a diagnostic or detectable agent, marker or reporter which may be, for example, a biological molecule (e.g., a peptide or nucleotide), a small molecule, fluorophore, or radioisotope. Labeled antibodies can be useful for monitoring the development or progression of a hyperproliferative disorder or as part of a clinical testing procedure to determine the efficacy of a particular therapy including the disclosed antibodies (i.e. theragnostics) or to determine a future course of treatment. Such markers or reporters may also be useful in purifying the selected antibody, for use in antibody analytics (e.g., epitope binding or antibody binning), separating or isolating tumorigenic cells or in preclinical procedures or toxicology studies.
Such diagnosis, analysis and/or detection can be accomplished by coupling the antibody to detectable substances including, but not limited to, various enzymes comprising for example horseradish peroxidase, alkaline phosphatase, beta-galactosidase, or acetylcholinesterase; prosthetic groups, such as but not limited to streptavidinlbiotin and avidin/biotin; fluorescent materials, such as but not limited to, umbelliferone, fluorescein, fluorescein isothiocynate, rhodamine, dichlorotriazinylamine fluorescein, dansyl chloride or phycoerythrin; luminescent materials, such as but not limited to, luminol; bioluminescent materials, such as but not limited to, luciferase, luciferin,
131 125 123 121 and aequorin; radioactive materials, such as but not limited to iodine ( I, I, I, I,), carbon (14C), sulfur (35S), tritium (3H), indium (115In, 113In, 112In, mIn), technetium (99Tc), thallium (201Ti), gallium (68Ga, 67Ga), palladium (103Pd), molybdenum (99Mo), xenon (133Xe), fluorine (18F), 153 Sm, 177Lu, 159Gd, 149Pm, 140La, 175Yb, 166Ho, 90Y, 47Sc, 186Re, 188Re, 142Pr, 105Rh, 97Ru, 68Ge, 57Co, 65Zn, 85Sr, 32P, 89Zr, 153Gd, 169Yb, 51Cr, 54Mn, 75Se, 113Sn, and 117Tin; positron emitting metals using various positron emission tomographies, non-radioactive paramagnetic metal ions, and molecules that are radiolabeled or conjugated to specific radioisotopes. In such embodiments appropriate detection methodology is well known in the art and readily available from numerous commercial sources.
In other embodiments the antibodies or fragments thereof can be fused or conjugated to marker sequences or compounds, such as a peptide or fluorophore to facilitate purification or diagnostic or analytic procedures such as immunohistochemistry, bio-layer interferometry, surface plasmon resonance, flow cytometry, competitive ELISA, FACs, etc. In some embodiments, the marker comprises a histidine tag such as that provided by the pQE vector (Qiagen), among others, many of which are commercially available. Other peptide tags useful for purification include, but are not limited to, the hemagglutinin "HA" tag, which corresponds to an epitope derived from the influenza hemagglutinin protein (Wilson et al., 1984, Cell 37:767) and the "flag" tag (U.S.P.N. 4,703,004).
3. Biocompatible modifiers
In selected embodiments the antibodies of the invention may be conjugated with biocompatible modifiers that may be used to adjust, alter, improve or moderate antibody characteristics as desired. For example, antibodies or fusion constructs with increased in vivo half- lives can be generated by attaching relatively high molecular weight polymer molecules such as commercially available polyethylene glycol (PEG) or similar biocompatible polymers. Those skilled in the art will appreciate that PEG may be obtained in many different molecular weights and molecular configurations that can be selected to impart specific properties to the antibody (e.g. the half-life may be tailored). PEG can be attached to antibodies or antibody fragments or derivatives with or without a multifunctional linker either through conjugation of the PEG to the N- or C- terminus of said antibodies or antibody fragments or via epsilon-amino groups present on lysine residues. Linear or branched polymer derivatization that results in minimal loss of biological activity may be used. The degree of conjugation can be closely monitored by SDS-PAGE and mass spectrometry to ensure optimal conjugation of PEG molecules to antibody molecules. Unreacted PEG can be separated from antibody-PEG conjugates by, e.g., size exclusion or ion-exchange chromatography. In a similar manner, the disclosed antibodies can be conjugated to albumin in order to make the antibody or antibody fragment more stable in vivo or have a longer half-life in vivo. The techniques are well known in the art, see e.g., WO 93/15199, WO 93/15200, and WO 01/77137; and EP 0 413, 622. Other biocompatible conjugates are evident to those of ordinary skill and may readily be identified in accordance with the teachings herein.
B. Linker compounds
As indicated above payloads compatible with the instant invention comprise one or more warheads and, optionally, a linker associating the warheads with the antibody targeting agent. Numerous linker compounds can be used to conjugate the antibodies of the invention to the relevant warhead. The linkers merely need to covalently bind with the reactive residue on the antibody (preferably a cysteine or lysine) and the selected drug compound. Accordingly, any linker that reacts with the selected antibody residue and may be used to provide the relatively stable conjugates (site-specific or otherwise) of the instant invention is compatible with the teachings herein.
Compatible linkers can advantageously bind to reduced cysteines and lysines, which are nucleophilic. Conjugation reactions involving reduced cysteines and lysines include, but are not limited to, thiol-maleimide, thiol -halogeno (acyl halide), thiol-ene, thiol-yne, thiol-vinylsulfone, thiol-bisulfone, thiol-thiosulfonate, thiol-pyridyl disulfide and thiol-parafluoro reactions. As further discussed herein, thiol-maleimide bioconjugation is one of the most widely used approaches due to its fast reaction rates and mild conjugation conditions. One issue with this approach is the possibility of the retro-Michael reaction and loss or transfer of the maleimido-linked payload from the antibody to other proteins in the plasma, such as, for example, human serum albumin. However, in some embodiments the use of selective reduction and site-specific antibodies as set forth herein in the Examples below may be used to stabilize the conjugate and reduce this undesired transfer. Thiol-acyl halide reactions provide bioconjugates that cannot undergo retro-Michael reaction and therefore are more stable. However, the thiol-halide reactions in general have slower reaction rates compared to maleimide-based conjugations and are thus not as efficient in providing undesired drug to antibody ratios. Thiol-pyridyl disulfide reaction is another popular bioconjugation route. The pyridyl disulfide undergoes fast exchange with free thiol resulting in the mixed disulfide and release of pyridine-2-thione. Mixed disulfides can be cleaved in the reductive cell environment releasing the payload. Other approaches gaining more attention in bioconjugation are thiol-vinylsulfone and thiol-bisulfone reactions, each of which are compatible with the teachings herein and expressly included within the scope of the invention.
In selected embodiments compatible linkers will confer stability on the ADCs in the extracellular environment, prevent aggregation of the ADC molecules and keep the ADC freely soluble in aqueous media and in a monomeric state. Before transport or delivery into a cell, the ADC is preferably stable and remains intact, i.e. the antibody remains linked to the drug moiety. While the linkers are stable outside the target cell they may be designed to be cleaved or degraded at some efficacious rate inside the cell. Accordingly, an effective linker will: (i) maintain the specific binding properties of the antibody; (ii) allow intracellular delivery of the conjugate or drug moiety; (iii) remain stable and intact, i.e. not cleaved or degraded, until the conjugate has been delivered or transported to its targeted site; and (iv) maintain a cytotoxic, cell-killing effect or a cytostatic effect of the drug moiety (including, in some cases, any bystander effects). The stability of the ADC may be measured by standard analytical techniques such as HPLC/UPLC, mass spectroscopy, HPLC, and the separation/analysis techniques LC/MS and LC/MS/MS. As set forth above covalent attachment of the antibody and the drug moiety requires the linker to have two reactive functional groups, i.e. bivalency in a reactive sense. Bivalent linker reagents that are useful to attach two or more functional or biologically active moieties, such as MMAE and antibodies are known, and methods have been described to provide resulting conjugates compatible with the teachings herein.
Linkers compatible with the present invention may broadly be classified as cleavable and non- cleavable linkers. Cleavable linkers, which may include acid-labile linkers (e.g., oximes and hydrozones), protease cleavable linkers and disulfide linkers, are internalized into the target cell and are cleaved in the endosomal-lysosomal pathway inside the cell. Release and activation of the cytotoxin relies on endosome/lysosome acidic compartments that facilitate cleavage of acid-labile chemical linkages such as hydrazone or oxime. If a lysosomal-specific protease cleavage site is engineered into the linker the cytotoxins will be released in proximity to their intracellular targets. Alternatively, linkers containing mixed disulfides provide an approach by which cytotoxic payloads are released intracellularly as they are selectively cleaved in the reducing environment of the cell, but not in the oxygen-rich environment in the bloodstream. By way of contrast, compatible non- cleavable linkers containing amide linked polyethylene glycol or alkyl spacers liberate toxic payloads during lysosomal degradation of the ADC within the target cell. In some respect the selection of linker will depend on the particular drug used in the conjugate, the particular indication and the antibody target.
Accordingly, certain embodiments of the invention comprise a linker that is cleavable by a cleaving agent that is present in the intracellular environment (e.g., within a lysosome or endosome or caveolae). The linker can be, for example, a peptidyl linker that is cleaved by an intracellular peptidase or protease enzyme, including, but not limited to, a lysosomal or endosomal protease. In some embodiments, the peptidyl linker is at least two amino acids long or at least three amino acids long. Cleaving agents can include cathepsins B and D and plasmin, each of which is known to hydrolyze dipeptide drug derivatives resulting in the release of active drug inside target cells. Exemplary peptidyl linkers that are cleavable by the thiol -dependent protease cathepsin-B are peptides comprising Phe-Leu since cathepsin-B has been found to be highly expressed in cancerous tissue. Other examples of such linkers are described, for example, in U.S. P.N. 6,214,345. In specific embodiments, the peptidyl linker cleavable by an intracellular protease is a Val-Cit linker, a Val-Ala linker or a Phe-Lys linker. One advantage of using intracellular proteolytic release of the therapeutic agent is that the agent is typically attenuated when conjugated and the serum stabilities of the conjugates are relatively high.
In other embodiments, the cleavable linker is pH-sensitive. Typically, the pH-sensitive linker will be hydrolyzable under acidic conditions. For example, an acid-labile linker that is hydrolyzable in the lysosome (e.g., a hydrazone, oxime, semicarbazone, thiosemicarbazone, cis-aconitic amide, orthoester, acetal, ketal, or the like) can be used (See, e.g., U. S.P.N. 5, 122,368; 5,824,805; 5,622,929). Such linkers are relatively stable under neutral pH conditions, such as those in the blood, but are unstable (e.g., cleavable) at below pH 5.5 or 5.0 which is the approximate pH of the lysosome.
In yet other embodiments, the linker is cleavable under reducing conditions (e.g., a disulfide linker). A variety of disulfide linkers are known in the art, including, for example, those that can be formed using SAT A (N-succinimidyl-S-acetylthioacetate), SPDP (N-succinimidyl-3-(2- pyridyldithio)propionate), SPDB (N-succinimidyl-3-(2-pyridyldithio) butyrate) and SMPT (N- succinimidyl-oxycarbonyl-alpha-methyl-alpha-(2-pyridyl-dithio)toluene). In yet other specific embodiments, the linker is a malonate linker (Johnson et al., 1995, Anticancer Res. 15: 1387-93), a maleimidobenzoyl linker (Lau et al., 1995, Bioorg-Med-Chem. 3(10): 1299-1304), or a 3'-N-amide analog (Lau et al., 1995, Bioorg-Med-Chem. 3(10): 1305-12).
In certain aspects of the invention the selected linker will comprise a compound of the formula:
Figure imgf000073_0001
wherein the asterisk indicates the point of attachment to the drug, CBA (i.e. cell binding agent) comprises the anti-KREMEN2 antibody, L1 comprises a linker unit and optionally a cleavable linker unit, A is a connecting group (optionally comprising a spacer) connecting L1 to a reactive residue on the antibody, L2 is preferably a covalent bond and U, which may or may not be present, can comprise all or part of a self-immolative unit that facilitates a clean separation of the linker from the warhead at the tumor site.
In some embodiments (such as those set forth in U.S. P.N. 2011/0256157) compatible linkers may comprise:
Figure imgf000074_0001
where the asterisk indicates the point of attachment to the drug, CBA (i.e. cell binding agent) comprises the anti-KREMEN2 antibody, L1 comprises a linker and optionally a cleavable linker, A is a connecting group (optionally comprising a spacer) connecting L1 to a reactive residue on the antibody and L2 is a covalent bond or together with -OC(=0)- forms a self-immolative moiety.
It will be appreciated that the nature of L1 and L2, where present, can vary widely. These groups are chosen on the basis of their cleavage characteristics, which may be dictated by the conditions at the site to which the conjugate is delivered. Those linkers that are cleaved by the action of enzymes are preferred, although linkers that are cleavable by changes in pH (e.g. acid or base labile), temperature or upon irradiation (e.g. photolabile) may also be used. Linkers that are cleavable under reducing or oxidizing conditions may also find use in the present invention.
In certain embodiments L1 may comprise a contiguous sequence of amino acids. The amino acid sequence may be the target substrate for enzymatic cleavage, thereby allowing release of the drug.
In one embodiment, L1 is cleavable by the action of an enzyme. In one embodiment, the enzyme is an esterase or a peptidase.
In another embodiment L1 is as a cathepsin labile linker.
In one embodiment, L1 comprises a dipeptide. The dipeptide may be represented as -NH-X1-X2-CO-, where -NH- and -CO- represent the N- and C-terminals of the amino acid groups X1 and X2 respectively. The amino acids in the dipeptide may be any combination of natural amino acids. Where the linker is a cathepsin labile linker, the dipeptide may be the site of action for cathepsin-mediated cleavage.
Additionally, for those amino acids groups having carboxyl or amino side chain functionality, for example Glu and Lys respectively, CO and H may represent that side chain functionality.
In one embodiment, the group -X1-X2- in dipeptide, - H-X1-X2-CO-, is selected from: -Phe- Lys-, -Val-Ala-, -Val-Lys-, -Ala-Lys-, -Val-Cit-, -Phe-Cit-, -Leu-Cit-, -Ile-Cit-, -Phe-Arg- and -Trp- Cit- where Cit is citrulline.
Preferably, the group -Xi-X2- in dipeptide, - H-Xi-X2-CO-, is selected from:-Phe-Lys-, -Val- Ala-, -Val-Lys-, -Ala-Lys-, and -Val-Cit-.
Most preferably, the group -Xi-X2- in dipeptide, - H-X1-X2-CO-, is -Phe-Lys- or -Val-Ala- or Val-Cit. In certain selected embodiments the dipeptide will comprise -Val-Ala-.
In one embodiment, L2 is present in the form of a covalent bond.
In one embodiment, L2 is present and together with -C(=0)0- forms a self-immolative linker. In one embodiment, L2 is a substrate for enzymatic activity, thereby allowing release of the warhead.
In one embodiment, where L1 is cleavable by the action of an enzyme and L2 is present, the enzyme cleaves the bond between L1 and L2.
L1 and L2, where present, may be connected by a bond selected from: -C(=0) H-, -C(=0)0-, - HC(=0)-, -OC(=0)-, -OC(=0)0-, - HC(=0)0-, -OC(=0) H-, and -NHC(=0)NH-.
An amino group of L1 that connects to L2 may be the N-terminus of an amino acid or may be derived from an amino group of an amino acid side chain, for example a lysine amino acid side chain.
A carboxyl group of L1 that connects to L2 may be the C-terminus of an amino acid or may be derived from a carboxyl group of an amino acid side chain, for example a glutamic acid amino acid side chain.
A hydroxyl group of L1 that connects to L2 may be derived from a hydroxyl group of an amino acid side chain, for example a serine amino acid side chain.
The term "amino acid side chain" includes those groups found in: (i) naturally occurring amino acids such as alanine, arginine, asparagine, aspartic acid, cysteine, glutamine, glutamic acid, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, and valine; (ii) minor amino acids such as ornithine and citrulline; (iii) unnatural amino acids, beta-amino acids, synthetic analogs and derivatives of naturally occurring amino acids; and (iv) all enantiomers, diastereomers, isomerically enriched, isotopically labelled (e.g. 2H, 3H, 14C, 15N), protected forms, and racemic mixtures thereof.
In one embodiment, -C(=0)0- and L2 together form the group:
Figure imgf000076_0001
where the asterisk indicates the point of attachment to the drug or cytotoxic agent position, the wavy line indicates the point of attachment to the linker L1, Y is -N(H)-, -0-, -C(=0)N(H)- or -C(=0)0-, and n is 0 to 3. The phenylene ring is optionally substituted with one, two or three substituents. In one embodiment, the phenylene group is optionally substituted with halo, N02, alkyl or hydroxyalkyl.
In one embodiment, Y is NH.
In one embodiment, n is 0 or 1. Preferably, n is 0.
Where Y is NH and n is 0, the self-immolative linker may be referred to as a p-aminobenzylcarbonyl linker (PABC).
In other embodiments the linker may include a self-immolative linker and the dipeptide together form the group -NH-Val-Cit-CO-NH-PABC-. In other selected embodiments the linker may comprise the group -NH-Val-Ala-CO-NH-PABC-, which is illustrated below:
Figure imgf000076_0002
where the asterisk indicates the point of attachment to the selected cytotoxic moiety, and the wavy line indicates the point of attachment to the remaining portion of the linker (e.g., the spacer- antibody binding segments) which may be conjugated to the antibody. Upon enzymatic cleavage of the dipeptide, the self-immolative linker will allow for clean release of the protected compound (i.e., the cytotoxin) when a remote site is activated, proceeding along the lines shown below:
Figure imgf000077_0001
where the asterisk indicates the point of attachment to the selected cytotoxic moiety and where L* is the activated form of the remaining portion of the linker comprising the now cleaved peptidyl unit. The clean release of the warhead ensures it will maintain the desired toxic activity.
In one embodiment, A is a covalent bond. Thus, L1 and the antibody are directly connected. For example, where L1 comprises a contiguous amino acid sequence, the N-terminus of the sequence may connect directly to the antibody residue.
In another embodiment, A is a spacer group. Thus, L1 and the antibody are indirectly connected.
In certain embodiments L1 and A may be connected by a bond selected from: -C(=0) H-, - C(=0)0-, - HC(=0)-, -OC(=0)-, -OC(=0)0-, - HC(=0)0-, -OC(=0)NH-, and -NHC(=0) H-.
As will be discussed in more detail below the drug linkers of the instant invention will preferably be linked to reactive thiol nucleophiles on cysteines, including free cysteines. To this end the cysteines of the antibodies may be made reactive for conjugation with linker reagents by treatment with various reducing agent such as DTT or TCEP or mild reducing agents as set forth herein. In other embodiments the drug linkers of the instant invention will preferably be linked to a lysine.
Preferably, the linker contains an electrophilic functional group for reaction with a nucleophilic functional group on the antibody. Nucleophilic groups on antibodies include, but are not limited to: (i) N-terminal amine groups, (ii) side chain amine groups, e.g. lysine, (iii) side chain thiol groups, e.g. cysteine, and (iv) sugar hydroxyl or amino groups where the antibody is glycosylated. Amine, thiol, and hydroxyl groups are nucleophilic and capable of reacting to form covalent bonds with electrophilic groups on linker moieties and linker reagents including: (i) maleimide groups (ii) activated disulfides, (iii) active esters such as NHS (N-hydroxysuccinimide) esters, HOBt (N-hydroxybenzotriazole) esters, haloformates, and acid halides; (iv) alkyl and benzyl halides such as haloacetamides; and (v) aldehydes, ketones and carboxyl groups.
Exemplary functional groups compatible with the invention are illustrated immediately below:
In some embodiments the connection between a cysteine (including a free cysteine of a site- specific antibody) and the drug-linker moiety is through a thiol residue and a terminal maleimide group of present on the linker. In such embodiments, the connection between the antibody and the drug-linker may be:
Figure imgf000078_0002
where the asterisk indicates the point of attachment to the remaining portion of drug-linker and the wavy line indicates the point of attachment to the remaining portion of the antibody. In this embodiment, the S atom is preferably derived from a site-specific free cysteine.
With regard to other compatible linkers the binding moiety may comprise a terminal bromo or iodoacetamide that may be reacted with activated residues on the antibody to provide the desired conjugate. In any event one skilled in the art could readily conjugate each of the disclosed drug- linker compounds with a compatible anti-KREMEN2 antibody (including site-specific antibodies) in view of the instant disclosure.
In accordance with the instant disclosure the invention provides methods of making compatible antibody drug conjugates comprising conjugating an anti- KREMEN2 antibody with a drug-linker compound selected from the group consisting of:
Figure imgf000079_0001
DL2
Figure imgf000080_0001

Figure imgf000081_0001
For the purposes of then instant application DL will be used as an abbreviation for "drug- linker" (or linker-drug "L-D" in the formula Ab-[L-D]n ) and will comprise drug linkers 1 - 6 (i.e., DL1, DL2, DL3, DL4 DL5, and DL6) as set forth above. Note that DL1 and DL6 comprise the same warhead and same dipeptide subunit but differ in the connecting group spacer. Accordingly, upon cleavage of the linker both DL1 and DL6 will release PBD1.
It will be appreciated that the linker appended terminal maleimido moiety (DL1 - DL4 and DL6) or iodoacetamide moiety (DL5) may be conjugated to free sulfhydryl(s) on the selected KREMEN2 antibody using art-recognized techniques. Synthetic routes for the aforementioned compounds are set forth in WO2014/130879 which is incorporated herein by reference explicitly for the synthesis of the aforementioned DL compounds while specific methods of conjugating such PBDs linker combinations are set forth in the Examples below.
Thus, in selected aspects the present invention relates to KREMEN2 antibodies conjugated to the disclosed DL moieties to provide KREMEN2 immunoconjugates substantially set forth in ADCs 1 - 6 immediately below. Accordingly, in certain aspects the invention is directed to an antibody drug conjugate selected from the group consisting of:
Figure imgf000082_0001
ADC 1,
Figure imgf000082_0002
Figure imgf000082_0003
ADC 3,
Figure imgf000083_0001
ADC 4,
Figure imgf000083_0002
ADC 5,
Figure imgf000083_0003
ADC 6 wherein Ab comprises an anti-KREMEN2 antibody or immunoreactive fragment thereof and n is an integer from 1 to 20. In certain embodiments n will comprise an integer from 1 to 8 and in selected embodiments n will comprise 2 or 4.
Those of skill in the art will appreciate that the aforementioned ADC structures are defined by the formula Ab-[L-D]n and more than one drug linker molecule as depicted therein may be covalently conjugated to the KREMEN2 antibody (e.g., n may be an integer from about 1 to about 20). More particularly, as discussed in more detail below it will be appreciated that more than one payload may be conjugated to each antibody and that the schematic representations above must be construed as such. By way of example ADC6 as set forth above may comprise a KREMEN2 antibody conjugated to 1, 2, 3, 4, 5, 6, 7 or 8 or more payloads and that compositions of such ADCs will generally comprise a mixture of drug loaded species.
In certain aspects the KREMEN2 PBD ADCs of the invention will comprise an anti- KREMEN2 antibody as set forth in the appended Examples or an immunoreactive fragment thereof. In a particular embodiment ADC 3 will comprise hSC78.43sslMJ (e.g., hSC78.43sslMJ PBD1). In other aspects the KREMEN2 PBD ADCs of the invention will comprise hSC78.56sslMJ (e.g., hSC78.56sslMJ PBD1). In such embodiments the ADCs will preferably comprise 2 payloads. In other preferred embodiments the KREMEN2 ADC will comprise ADC6 wherein n is 2.
C. Conjugation
It will be appreciated that a number of well-known reactions may be used to attach the drug moiety and/or linker to the selected antibody. For example, various reactions exploiting sulfhydryl groups of cysteines may be employed to conjugate the desired moiety. Some embodiments will comprise conjugation of antibodies comprising one or more free cysteines as discussed in detail below. In other embodiments ADCs of the instant invention may be generated through conjugation of drugs to solvent-exposed amino groups of lysine residues present in the selected antibody. Still other embodiments comprise activation of N-terminal threonine and serine residues which may then be used to attach the disclosed payloads to the antibody. The selected conjugation methodology will preferably be tailored to optimize the number of drugs attached to the antibody and provide a relatively high therapeutic index. Various methods are known in the art for conjugating a therapeutic compound to a cysteine residue and will be apparent to the skilled artisan. Under basic conditions the cysteine residues will be deprotonated to generate a thiolate nucleophile which may be reacted with soft electrophiles such as maleimides and iodoacetamides. Generally reagents for such conjugations may react directly with a cysteine thiol to form the conjugated protein or with a linker-drug to form a linker-drug intermediate. In the case of a linker, several routes, employing organic chemistry reactions, conditions, and reagents are known to those skilled in the art, including: (1) reaction of a cysteine group of the protein of the invention with a linker reagent, to form a protein-linker intermediate, via a covalent bond, followed by reaction with an activated compound; and (2) reaction of a nucleophilic group of a compound with a linker reagent, to form a drug-linker intermediate, via a covalent bond, followed by reaction with a cysteine group of a protein of the invention. As will be apparent to the skilled artisan from the foregoing, bifunctional (or bivalent) linkers are useful in the present invention. For example, the bifunctional linker may comprise a thiol modification group for covalent linkage to the cysteine residue(s) and at least one attachment moiety (e.g., a second thiol modification moiety) for covalent or non-covalent linkage to the compound.
Prior to conjugation, antibodies may be made reactive for conjugation with linker reagents by treatment with a reducing agent such as dithiothreitol (DTT) or (tm(2-carboxyethyl)phosphine (TCEP). In other embodiments additional nucleophilic groups can be introduced into antibodies through the reaction of lysines with reagents, including but not limited to, 2-iminothiolane (Traut's reagent), SAT A, SATP or SAT(PEG)4, resulting in conversion of an amine into a thiol.
With regard to such conjugations cysteine thiol or lysine amino groups are nucleophilic and capable of reacting to form covalent bonds with electrophilic groups on linker reagents or compound-linker intermediates or drugs including: (i) active esters such as NHS esters, HOBt esters, haloformates, and acid halides; (ii) alkyl and benzyl halides, such as haloacetamides; (iii) aldehydes, ketones, carboxyl, and maleimide groups; and (iv) disulfides, including pyridyl disulfides, via sulfide exchange. Nucleophilic groups on a compound or linker include, but are not limited to amine, thiol, hydroxyl, hydrazide, oxime, hydrazine, thiosemicarbazone, hydrazine carboxylate, and arylhydrazide groups capable of reacting to form covalent bonds with electrophilic groups on linker moieties and linker reagents.
Conjugation reagents commonly include maleimide, haloacetyl, iodoacetamide succinimidyl ester, isothiocyanate, sulfonyl chloride, 2,6-dichlorotriazinyl, pentafluorophenyl ester, and phosphoramidite, although other functional groups can also be used. In certain embodiments methods include, for example, the use of maleimides, iodoacetimides or haloacetyl/alkyl halides, aziridne, acryloyl derivatives to react with the thiol of a cysteine to produce a thioether that is reactive with a compound. Disulphide exchange of a free thiol with an activated piridyldisulphide is also useful for producing a conjugate (e.g., use of 5-thio-2-nitrobenzoic (T B) acid). Preferably, a maleimide is used.
As indicated above, lysine may also be used as a reactive residue to effect conjugation as set forth herein. The nucleophilic lysine residue is commonly targeted through amine- reactive succinimidylesters. To obtain an optimal number of deprotonated lysine residues, the pH of the aqueous solution must be below the pKa of the lysine ammonium group, which is around 10.5, so the typical pH of the reaction is about 8 and 9. The common reagent for the coupling reaction is NHS-ester which reacts with nucleophilic lysine through a lysine acylation mechanism. Other compatible reagents that undergo similar reactions comprise isocyanates and isothiocyanates which also may be used in conjunction with the teachings herein to provide ADCs. Once the lysines have been activated, many of the aforementioned linking groups may be used to covalently bind the warhead to the antibody.
Methods are also known in the art for conjugating a compound to a threonine or serine residue (preferably a N-terminal residue). For example, methods have been described in which carbonyl precursors are derived from the 1,2-aminoalcohols of serine or threonine, which can be selectively and rapidly converted to aldehyde form by periodate oxidation. Reaction of the aldehyde with a 1,2- aminothiol of cysteine in a compound to be attached to a protein of the invention forms a stable thiazolidine product. This method is particularly useful for labeling proteins at N-terminal serine or threonine residues.
In some embodiments reactive thiol groups may be introduced into the selected antibody (or fragment thereof) by introducing one, two, three, four, or more free cysteine residues (e.g., preparing antibodies comprising one or more free non-native cysteine amino acid residues). Such site-specific antibodies or engineered antibodies allow for conjugate preparations that exhibit enhanced stability and substantial homogeneity due, at least in part, to the provision of engineered free cysteine site(s) and/or the novel conjugation procedures set forth herein. Unlike conventional conjugation methodology that fully or partially reduces each of the intrachain or interchain antibody disulfide bonds to provide conjugation sites (and is fully compatible with the instant invention), the present invention additionally provides for the selective reduction of certain prepared free cysteine sites and attachment of the drug linker to the same.
In this regard it will be appreciated that the conjugation specificity promoted by the engineered sites and the selective reduction allows for a high percentage of site directed conjugation at the desired positions. Significantly some of these conjugation sites, such as those present in the terminal region of the light chain constant region, are typically difficult to conjugate effectively as they tend to cross-react with other free cysteines. However, through molecular engineering and selective reduction of the resulting free cysteines, efficient conjugation rates may be obtained which considerably reduces unwanted high-DAR contaminants and non-specific toxicity. More generally the engineered constructs and disclosed novel conjugation methods comprising selective reduction provide ADC preparations having improved pharmacokinetics and/or pharmacodynamics and, potentially, an improved therapeutic index.
In certain embodiments site-specific constructs present free cysteine(s) which, when reduced, comprise thiol groups that are nucleophilic and capable of reacting to form covalent bonds with electrophilic groups on linker moieties such as those disclosed above. As discussed above antibodies of the instant invention may have reducible unpaired interchain or intrachain cysteines or introduced non-native cysteines, i.e. cysteines providing such nucleophilic groups. Thus, in certain embodiments the reaction of free sulfhydryl groups of the reduced free cysteines and the terminal maleimido or haloacetamide groups of the disclosed drug-linkers will provide the desired conjugation. In such cases free cysteines of the antibodies may be made reactive for conjugation with linker reagents by treatment with a reducing agent such as dithiothreitol (DTT) or (tris (2- carboxyethyl)phosphine (TCEP). Each free cysteine will thus present, theoretically, a reactive thiol nucleophile. While such reagents are particularly compatible with the instant invention it will be appreciated that conjugation of site-specific antibodies may be effected using various reactions, conditions and reagents generally known to those skilled in the art.
In addition, it has been found that the free cysteines of engineered antibodies may be selectively reduced to provide enhanced site-directed conjugation and a reduction in unwanted, potentially toxic contaminants. More specifically "stabilizing agents" such as arginine have been found to modulate intra- and inter-molecular interactions in proteins and may be used, in conjunction with selected reducing agents (preferably relatively mild), to selectively reduce the free cysteines and to facilitate site-specific conjugation as set forth herein. As used herein the terms "selective reduction" or "selectively reducing" may be used interchangeably and shall mean the reduction of free cysteine(s) without substantially disrupting native disulfide bonds present in the engineered antibody. In selected embodiments this selective reduction may be effected by the use of certain reducing agents or certain reducing agent concentrations. In other embodiments selective reduction of an engineered construct will comprise the use of stabilization agents in combination with reducing agents (including mild reducing agents). It will be appreciated that the term "selective conjugation" shall mean the conjugation of an engineered antibody that has been selectively reduced in the presence of a cytotoxin as described herein. In this respect the use of such stabilizing agents (e.g., arginine) in combination with selected reducing agents can markedly improve the efficiency of site-specific conjugation as determined by extent of conjugation on the heavy and light antibody chains and DAR distribution of the preparation. Compatible antibody constructs and selective conjugation techniques and reagents are extensively disclosed in WO2015/031698 which is incorporated herein specifically as to such methodology and constructs.
While not wishing to be bound by any particular theory, such stabilizing agents may act to modulate the electrostatic microenvironment and/or modulate conformational changes at the desired conjugation site, thereby allowing relatively mild reducing agents (which do not materially reduce intact native disulfide bonds) to facilitate conjugation at the desired free cysteine site(s). Such agents (e.g., certain amino acids) are known to form salt bridges (via hydrogen bonding and electrostatic interactions) and can modulate protein-protein interactions in such a way as to impart a stabilizing effect that may cause favorable conformational changes and/or reduce unfavorable protein-protein interactions. Moreover, such agents may act to inhibit the formation of undesired intramolecular (and intermolecular) cysteine-cysteine bonds after reduction thus facilitating the desired conjugation reaction wherein the engineered site-specific cysteine is bound to the drug (preferably via a linker). Since selective reduction conditions do not provide for the significant reduction of intact native disulfide bonds, the subsequent conjugation reaction is naturally driven to the relatively few reactive thiols on the free cysteines (e.g., preferably 2 free thiols per antibody). As previously alluded to, such techniques may be used to considerably reduce levels of non-specific conjugation and corresponding unwanted DAR species in conjugate preparations fabricated in accordance with the instant disclosure.
In selected embodiments stabilizing agents compatible with the present invention will generally comprise compounds with at least one moiety having a basic pKa. In certain embodiments the moiety will comprise a primary amine while in other embodiments the amine moiety will comprise a secondary amine. In still other embodiments the amine moiety will comprise a tertiary amine or a guanidinium group. In other selected embodiments the amine moiety will comprise an amino acid while in other compatible embodiments the amine moiety will comprise an amino acid side chain. In yet other embodiments the amine moiety will comprise a proteinogenic amino acid. In still other embodiments the amine moiety comprises a non- proteinogenic amino acid. In some embodiments, compatible stabilizing agents may comprise arginine, lysine, proline and cysteine. In certain preferred embodiments the stabilizing agent will comprise arginine. In addition, compatible stabilizing agents may include guanidine and nitrogen containing heterocycles with basic pKa.
In certain embodiments compatible stabilizing agents comprise compounds with at least one amine moiety having a pKa of greater than about 7.5, in other embodiments the subject amine moiety will have a pKa of greater than about 8.0, in yet other embodiments the amine moiety will have a pKa greater than about 8.5 and in still other embodiments the stabilizing agent will comprise an amine moiety having a pKa of greater than about 9.0. Other embodiments will comprise stabilizing agents where the amine moiety will have a pKa of greater than about 9.5 while certain other embodiments will comprise stabilizing agents exhibiting at least one amine moiety having a pKa of greater than about 10.0. In still other embodiments the stabilizing agent will comprise a compound having the amine moiety with a pKa of greater than about 10.5, in other embodiments the stabilizing agent will comprise a compound having a amine moiety with a pKa greater than about 11.0, while in still other embodiments the stabilizing agent will comprise a amine moiety with a pKa greater than about 11.5. In yet other embodiments the stabilizing agent will comprise a compound having an amine moiety with a pKa greater than about 12.0, while in still other embodiments the stabilizing agent will comprise an amine moiety with a pKa greater than about 12.5. Those of skill in the art will understand that relevant pKa's may readily be calculated or determined using standard techniques and used to determine the applicability of using a selected compound as a stabilizing agent.
The disclosed stabilizing agents are shown to be particularly effective at targeting conjugation to free site-specific cysteines when combined with certain reducing agents. For the purposes of the instant invention, compatible reducing agents may include any compound that produces a reduced free site-specific cysteine for conjugation without significantly disrupting the native disulfide bonds of the engineered antibody. Under such conditions, preferably provided by the combination of selected stabilizing and reducing agents, the activated drug linker is largely limited to binding to the desired free site-specific cysteine site(s). Relatively mild reducing agents or reducing agents used at relatively low concentrations to provide mild conditions are particularly preferred. As used herein the terms "mild reducing agent" or "mild reducing conditions" shall be held to mean any agent or state brought about by a reducing agent (optionally in the presence of stabilizing agents) that provides thiols at the free cysteine site(s) without substantially disrupting native disulfide bonds present in the engineered antibody. That is, mild reducing agents or conditions (preferably in combination with a stabilizing agent) are able to effectively reduce free cysteine(s) (provide a thiol) without significantly disrupting the protein's native disulfide bonds. The desired reducing conditions may be provided by a number of sulfhydryl-based compounds that establish the appropriate environment for selective conjugation. In embodiments mild reducing agents may comprise compounds having one or more free thiols while in some embodiments mild reducing agents will comprise compounds having a single free thiol. Non-limiting examples of reducing agents compatible with the selective reduction techniques of the instant invention comprise glutathione, n-acetyl cysteine, cysteine, 2-aminoethane-l -thiol and 2-hydroxy ethane- 1- thiol.
It will be appreciated that selective reduction process set forth above is particularly effective at targeted conjugation to the free cysteine. In this respect the extent of conjugation to the desired target site (defined here as "conjugation efficiency") in site-specific antibodies may be determined by various art-accepted techniques. The efficiency of the site-specific conjugation of a drug to an antibody may be determined by assessing the percentage of conjugation on the target conjugation site(s) (e.g. free cysteines on the c-terminus of each light chain) relative to all other conjugated sites. In certain embodiments, the method herein provides for efficiently conjugating a drug to an antibody comprising free cysteines. In some embodiments, the conjugation efficiency is at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 70%, at least 75%, at least 80%, at least 85%), at least 90%, at least 95%, at least 98% or more as measured by the percentage of target conjugation relative to all other conjugation sites.
It will further be appreciated that engineered antibodies capable of conjugation may contain free cysteine residues that comprise sulfhydryl groups that are blocked or capped as the antibody is produced or stored. Such caps include small molecules, proteins, peptides, ions and other materials that interact with the sulfhydryl group and prevent or inhibit conjugate formation. In some cases the unconjugated engineered antibody may comprise free cysteines that bind other free cysteines on the same or different antibodies. As discussed herein such cross-reactivity may lead to various contaminants during the fabrication procedure. In some embodiments, the engineered antibodies may require uncapping prior to a conjugation reaction. In specific embodiments, antibodies herein are uncapped and display a free sulfhydryl group capable of conjugation. In specific embodiments, antibodies herein are subjected to an uncapping reaction that does not disturb or rearrange the naturally occurring disulfide bonds. It will be appreciated that in most cases the uncapping reactions will occur during the normal reduction reactions (reduction or selective reduction).
D. PAR distribution and purification
In selected embodiments conjugation and purification methodology compatible with the present invention advantageously provides the ability to generate relatively homogeneous ADC preparations comprising a narrow DAR distribution. In this regard the disclosed constructs (e.g., site-specific constructs) and/or selective conjugation provides for homogeneity of the ADC species within a sample in terms of the stoichiometric ratio between the drug and the engineered antibody and with respect to the toxin location. As briefly discussed above the term "drug to antibody ratio" or "DAR" refers to the molar ratio of drug to antibody in an ADC preparation. In certain embodiments a conjugate preparation may be substantially homogeneous with respect to its DAR distribution, meaning that within the ADC preparation is a predominant species of site-specific ADC with a particular drug loading (e.g., a drug loading of 2 or 4) that is also preferably uniform with respect to the site of loading (i.e., on the free cysteines). In other certain embodiments of the invention it is possible to achieve the desired homogeneity through the use of site-specific antibodies and/or selective reduction and conjugation. In other embodiments the desired homogeneity may be achieved through the use of site-specific constructs in combination with selective reduction. In yet other embodiments compatible preparations may be purified using analytical or preparative chromatography techniques to provide the desired homogeneity. In each of these embodiments the homogeneity of the ADC sample can be analyzed using various techniques known in the art including but not limited to mass spectrometry, HPLC (e.g. size exclusion HPLC, RP-HPLC, HIC-HPLC etc.) or capillary electrophoresis. With regard to the purification of ADC preparations it will be appreciated that standard pharmaceutical preparative methods may be employed to obtain the desired purity. As discussed herein liquid chromatography methods such as reverse phase (RP) and hydrophobic interaction chromatography (HIC) may separate compounds in the mixture by drug loading value. In some cases, ion-exchange (IEC) or mixed-mode chromatography (MMC) may also be used to isolate species with a specific drug load.
In any event the disclosed ADCs and preparations thereof may comprise drug and antibody moieties in various stoichiometric molar ratios depending on the configuration of the antibody and, at least in part, on the method used to effect conjugation. In certain embodiments the drug loading per ADC may comprise from 1-20 warheads (i.e., n is 1-20). Other selected embodiments may comprise ADCs with a drug loading of from 1 to 15 warheads. In still other embodiments the ADCs may comprise from 1-12 warheads or, more preferably, from 1-10 warheads. In some embodiments the ADCs will comprise from 1 to 8 warheads.
While theoretical drug loading may be relatively high, practical limitations such as free cysteine cross reactivity and warhead hydrophobicity tend to limit the generation of homogeneous preparations comprising such DAR due to aggregates and other contaminants. That is, higher drug loading, e.g. >8 or 10, may cause aggregation, insolubility, toxicity, or loss of cellular permeability of certain antibody-drug conjugates depending on the payload. In view of such concerns drug loading provided by the instant invention preferably ranges from 1 to 8 drugs per conjugate, i.e. where 1, 2, 3, 4, 5, 6, 7, or 8 drugs are covalently attached to each antibody (e.g., for IgGl, other antibodies may have different loading capacity depending the number of disulfide bonds). Preferably the DAR of compositions of the instant invention will be approximately 2, 4 or 6 and in some embodiments the DAR will comprise approximately 2.
Despite the relatively high level of homogeneity provided by the instant invention the disclosed compositions actually comprise a mixture of conjugates with a range of drug compounds (potentially from 1 to 8 in the case of an IgGl). As such, the disclosed ADC compositions include mixtures of conjugates where most of the constituent antibodies are covalently linked to one or more drug moieties and (despite the relative conjugate specificity provided by engineered constructs and selective reduction) where the drug moieties may be attached to the antibody by various thiol groups. That is, following conjugation, compositions of the invention will comprise a mixture of ADCs with different drug loads (e.g., from 1 to 8 drugs per IgGl antibody) at various concentrations (along with certain reaction contaminants primarily caused by free cysteine cross reactivity). However, using selective reduction and post-fabrication purification the conjugate compositions may be driven to the point where they largely contain a single predominant desired ADC species (e.g., with a drug loading of 2) with relatively low levels of other ADC species (e.g., with a drug loading of 1, 4, 6, etc.). The average DAR value represents the weighted average of drug loading for the composition as a whole (i.e., all the ADC species taken together). Due to inherent uncertainty in the quantification methodology employed and the difficulty in completely removing the non-predominant ADC species in a commercial setting, acceptable DAR values or specifications are often presented as an average, a range or distribution (i.e., an average DAR of 2 +/- 0.5). Preferably compositions comprising a measured average DAR within the range (i.e., 1.5 to 2.5) would be used in a pharmaceutical setting.
Thus, in some embodiments the present invention will comprise compositions having an average DAR of 1, 2, 3, 4, 5, 6, 7 or 8 each +/- 0.5. In other embodiments the present invention will comprise an average DAR of 2, 4, 6 or 8 +/- 0.5. Finally, in selected embodiments the present invention will comprise an average DAR of 2 +/- 0.5 or 4 +/- 0.5. It will be appreciated that the range or deviation may be less than 0.4 in some embodiments. Thus, in other embodiments the compositions will comprise an average DAR of 1, 2, 3, 4, 5, 6, 7 or 8 each +/- 0.3, an average DAR of 2, 4, 6 or 8 +/- 0.3, even more preferably an average DAR of 2 or 4 +/- 0.3 or even an average DAR of 2 +/- 0.3. In other embodiments IgGl conjugate compositions will preferably comprise a composition with an average DAR of 1, 2, 3, 4, 5, 6, 7 or 8 each +/- 0.4 and relatively low levels (i.e., less than 30%) of non-predominant ADC species. In other embodiments the ADC composition will comprise an average DAR of 2, 4, 6 or 8 each +/- 0.4 with relatively low levels (< 30%>) of non- predominant ADC species. In some embodiments the ADC composition will comprise an average DAR of 2 +/- 0.4 with relatively low levels (< 30%>) of non-predominant ADC species. In yet other embodiments the predominant ADC species (e.g., with a drug loading of 2 or drug loading of 4) will be present at a concentration of greater than 50%>, at a concentration of greater than 55%>, at a concentration of greater than 60 %>, at a concentration of greater than 65%>, at a concentration of greater than 70%>, at a concentration of greater than 75%>, at a concentration of greater that 80%>, at a concentration of greater than 85%>, at a concentration of greater than 90%>, at a concentration of greater than 93%>, at a concentration of greater than 95%> or even at a concentration of greater than 97%) when measured against all other DAR species present in the composition. As detailed in the Examples below the distribution of drugs per antibody in preparations of ADC from conjugation reactions may be characterized by conventional means such as UV-Vis spectrophotometry, reverse phase HPLC, HIC, mass spectroscopy, ELISA, and electrophoresis. The quantitative distribution of ADC in terms of drugs per antibody may also be determined. By ELISA, the averaged value of the drugs per antibody in a particular preparation of ADC may be determined. However, the distribution of drug per antibody values is not discernible by the antibody-antigen binding and detection limitation of ELISA. Also, ELISA assay for detection of antibody-drug conjugates does not determine where the drug moieties are attached to the antibody, such as the heavy chain or light chain fragments, or the particular amino acid residues. VI. Diagnostics and Screening A. Diagnostics
The invention provides in vitro and in vivo methods for detecting, diagnosing or monitoring proliferative disorders and methods of screening cells from a patient to identify tumor cells including tumorigenic cells. Such methods include identifying an individual having cancer for treatment or monitoring progression of a cancer, comprising contacting the patient or a sample obtained from a patient (either in vivo or in vitro) with a detection agent (e.g., an antibody or nucleic acid probe) capable of specifically recognizing and associating with a KREMEN2 determinant and detecting the presence or absence, or level of association of the detection agent in the sample. In selected embodiments the detection agent will comprise an antibody associated with a detectable label or reporter molecule as described herein. In certain other embodiments the KREMEN2 antibody will be administered and detected using a secondary labelled antibody (e.g., an anti -murine antibody). In yet other embodiments (e.g., In situ hybridization or ISH) a nucleic acid probe that reacts with a genomic KREMEN2 determinant will be used in the detection, diagnosis or monitoring of the proliferative disorder.
More generally the presence and/or levels of KREMEN2 determinants may be measured using any of a number of techniques available to the person of ordinary skill in the art for protein or nucleic acid analysis, e.g., direct physical measurements (e.g., mass spectrometry), binding assays (e.g., immunoassays, agglutination assays, and immunochromatographic assays), Polymerase Chain Reaction (PCR, RT-PCR; RT-qPCR) technology, branched oligonucleotide technology, Northern blot technology, oligonucleotide hybridization technology and in situ hybridization technology. The method may also comprise measuring a signal that results from a chemical reaction, e.g., a change in optical absorbance, a change in fluorescence, the generation of chemiluminescence or electrochemiluminescence, a change in reflectivity, refractive index or light scattering, the accumulation or release of detectable labels from the surface, the oxidation or reduction or redox species, an electrical current or potential, changes in magnetic fields, etc. Suitable detection techniques may detect binding events by measuring the participation of labeled binding reagents through the measurement of the labels via their photoluminescence (e.g., via measurement of fluorescence, time-resolved fluorescence, evanescent wave fluorescence, up-converting phosphors, multi-photon fluorescence, etc.), chemiluminescence, electrochemiluminescence, light scattering, optical absorbance, radioactivity, magnetic fields, enzymatic activity (e.g., by measuring enzyme activity through enzymatic reactions that cause changes in optical absorbance or fluorescence or cause the emission of chemiluminescence). Alternatively, detection techniques may be used that do not require the use of labels, e.g., techniques based on measuring mass (e.g., surface acoustic wave measurements), refractive index (e.g., surface plasmon resonance measurements), or the inherent luminescence of an anal yte.
In some embodiments, the association of the detection agent with particular cells or cellular components in the sample indicates that the sample may contain tumorigenic cells, thereby denoting that the individual having cancer may be effectively treated with an antibody or ADC as described herein.
In certain preferred embodiments the assays may comprise immunohistochemistry (IHC) assays or variants thereof (e.g., fluorescent, chromogenic, standard ABC, standard LSAB, etc.), immunocytochemistry or variants thereof (e.g., direct, indirect, fluorescent, chromogenic, etc.) or In situ hybridization (ISH) or variants thereof (e.g., chromogenic in situ hybridization (CISH) or fluorescence in situ hybridization (DNA-FISH or RNA-FISH]))
In this regard certain aspects of the instant invention comprise the use of labeled KREMEN2 for immunohistochemistry (IHC). More particularly KREMEN2 IHC may be used as a diagnostic tool to aid in the diagnosis of various proliferative disorders and to monitor the potential response to treatments including KREMEN2 antibody therapy. In certain embodiments the KREMEN2 will be conjugated to one or more reporter molecules. In other embodiments the KREMEN2 antibody will be unlabeled and will be detected with a separate agent (e.g., an anti-murine antibody) associated with one or more reporter molecules. As discussed herein and shown in the Examples below compatible diagnostic assays may be performed on tissues that have been chemically fixed (including but not limited to: formaldehyde, gluteraldehyde, osmium tetroxide, potassium dichromate, acetic acid, alcohols, zinc salts, mercuric chloride, chromium tetroxide and picric acid) and embedded (including but not limited to: glycol methacrylate, paraffin and resins) or preserved via freezing. Such assays can be used to guide treatment decisions and determine dosing regimens and timing.
Other particularly compatible aspects of the invention involve the use of in situ hybridization to detect or monitor KREMEN2 determinants. In situ hybridization technology or ISH is well known to those of skill in the art. Briefly, cells are fixed and detectable probes which contain a specific nucleotide sequence are added to the fixed cells. If the cells contain complementary nucleotide sequences, the probes, which can be detected, will hybridize to them. Using the sequence information set forth herein, probes can be designed to identify cells that express genotypic KREMEN2 determinants. Probes preferably hybridize to a nucleotide sequence that corresponds to such determinants. Hybridization conditions can be routinely optimized to minimize background signal by non-fully complementary hybridization though preferably the probes are preferably fully complementary to the selected KREMEN2 determinant. In selected embodiments the probes are labeled with fluorescent dye attached to the probes that is readily detectable by standard fluorescent methodology.
Compatible in vivo theragnostics or diagnostic assays may comprise art-recognized imaging or monitoring techniques such as magnetic resonance imaging, computerized tomography (e.g. CAT scan), positron tomography (e.g., PET scan) radiography, ultrasound, etc., as would be known by those skilled in the art.
In certain embodiments the antibodies of the instant invention may be used to detect and quantify levels of a particular determinant (e.g., KREMEN2 protein) in a patient sample (e.g., plasma or blood) which may, in turn, be used to detect, diagnose or monitor proliferative disorders that are associated with the relevant determinant. For example, blood and bone marrow samples may be used in conjunction with flow cytometry to detect and measure KREMEN2 expression (or another co-expressed marker) and monitor the progression of the disease and/or response to treatment. In related embodiments the antibodies of the instant invention may be used to detect, monitor and/or quantify circulating tumor cells either in vivo or in vitro (WO 2012/0128801). In still other embodiments the circulating tumor cells may comprise tumorigenic cells. In certain embodiments of the invention, the tumorigenic cells in a subject or a sample from a subject may be assessed or characterized using the disclosed antibodies prior to therapy or regimen to establish a baseline. In other examples, the tumorigenic cells can be assessed from a sample that is derived from a subject that was treated.
In another embodiment, the invention provides a method of analyzing cancer progression and/or pathogenesis in vivo. In another embodiment, analysis of cancer progression and/or pathogenesis in vivo comprises determining the extent of tumor progression. In another embodiment, analysis comprises the identification of the tumor. In another embodiment, analysis of tumor progression is performed on the primary tumor. In another embodiment, analysis is performed over time depending on the type of cancer as known to one skilled in the art. In another embodiment, further analysis of secondary tumors originating from metastasizing cells of the primary tumor is conducted in vivo. In another embodiment, the size and shape of secondary tumors are analyzed. In some embodiments, further ex vivo analysis is performed.
In another embodiment, the invention provides a method of analyzing cancer progression and/or pathogenesis in vivo including determining cell metastasis or detecting and quantifying the level of circulating tumor cells. In yet another embodiment, analysis of cell metastasis comprises determination of progressive growth of cells at a site that is discontinuous from the primary tumor. In some embodiments, procedures may be undertaken to monitor tumor cells that disperse via blood vasculature, lymphatics, within body cavities or combinations thereof. In another embodiment, cell metastasis analysis is performed in view of cell migration, dissemination, extravasation, proliferation or combinations thereof.
In certain examples, the tumorigenic cells in a subject or a sample from a subject may be assessed or characterized using the disclosed antibodies prior to therapy to establish a baseline. In other examples the sample is derived from a subject that was treated. In some examples the sample is taken from the subject at least about 1, 2, 4, 6, 7, 8, 10, 12, 14, 15, 16, 18, 20, 30, 60, 90 days, 6 months, 9 months, 12 months, or >12 months after the subject begins or terminates treatment. In certain examples, the tumorigenic cells are assessed or characterized after a certain number of doses (e.g., after 2, 5, 10, 20, 30 or more doses of a therapy). In other examples, the tumorigenic cells are characterized or assessed after 1 week, 2 weeks, 1 month, 2 months, 1 year, 2 years, 3 years, 4 years or more after receiving one or more therapies. B. Screening
In certain embodiments, antibodies of the instant invention can be used to screen samples in order to identify compounds or agents (e.g., antibodies or ADCs) that alter a function or activity of tumor cells by interacting with a determinant. In one embodiment, tumor cells are put in contact with an antibody or ADC and the antibody or ADC can be used to screen the tumor for cells expressing a certain target (e.g. KREMEN2) in order to identify such cells for purposes, including but not limited to, diagnostic purposes, to monitor such cells to determine treatment efficacy or to enrich a cell population for such target-expressing cells.
In yet another embodiment, a method includes contacting, directly or indirectly, tumor cells with a test agent or compound and determining if the test agent or compound modulates an activity or function of the determinant-associated tumor cells for example, changes in cell morphology or viability, expression of a marker, differentiation or de-differentiation, cell respiration, mitochondrial activity, membrane integrity, maturation, proliferation, viability, apoptosis or cell death. One example of a direct interaction is physical interaction, while an indirect interaction includes, for example, the action of a composition upon an intermediary molecule that, in turn, acts upon the referenced entity (e.g., cell or cell culture).
Screening methods include high throughput screening, which can include arrays of cells (e.g., microarrays) positioned or placed, optionally at pre-determined locations, for example, on a culture dish, tube, flask, roller bottle or plate. High-throughput robotic or manual handling methods can probe chemical interactions and determine levels of expression of many genes in a short period of time. Techniques have been developed that utilize molecular signals, for example via fluorophores or microarrays (Mocellin and Rossi, 2007, PMID: 17265713) and automated analyses that process information at a very rapid rate (see, e.g., Pinhasov et al , 2004, PMID: 15032660). Libraries that can be screened include, for example, small molecule libraries, phage display libraries, fully human antibody yeast display libraries (Adimab), siRNA libraries, and adenoviral transfection vectors.
VII. Pharmaceutical Preparations and Therapeutic Uses
A. Formulations and routes of administration
The antibodies or ADCs of the invention can be formulated in various ways using art recognized techniques. In some embodiments, the therapeutic compositions of the invention can be administered neat or with a minimum of additional components while others may optionally be formulated to contain suitable pharmaceutically acceptable carriers. As used herein, "pharmaceutically acceptable carriers" comprise excipients, vehicles, adjuvants and diluents that are well known in the art and can be available from commercial sources for use in pharmaceutical preparation (see, e.g., Gennaro (2003) Remington: The Science and Practice of Pharmacy with Facts and Comparisons: Drugfacts Plus, 20th ed., Mack Publishing; Ansel et al. (2004) Pharmaceutical Dosage Forms and Drug Delivery Systems, 7th ed., Lippencott Williams and Wilkins; Kibbe et a/.(2000) Handbook of Pharmaceutical Excipients, 3rd ed., Pharmaceutical Press.) Suitable pharmaceutically acceptable carriers comprise substances that are relatively inert and can facilitate administration of the antibody or ADC or can aid processing of the active compounds into preparations that are pharmaceutically optimized for delivery to the site of action.
Such pharmaceutically acceptable carriers include agents that can alter the form, consistency, viscosity, pH, tonicity, stability, osmolality, pharmacokinetics, protein aggregation or solubility of the formulation and include buffering agents, wetting agents, emulsifying agents, diluents, encapsulating agents and skin penetration enhancers. Certain non-limiting examples of carriers include saline, buffered saline, dextrose, arginine, sucrose, water, glycerol, ethanol, sorbitol, dextran, sodium carboxymethyl cellulose and combinations thereof. Antibodies for systemic administration may be formulated for enteral, parenteral or topical administration. Indeed, all three types of formulation may be used simultaneously to achieve systemic administration of the active ingredient. Excipients as well as formulations for parenteral and nonparenteral drug delivery are set forth in Remington: The Science and Practice of Pharmacy (2000) 20th Ed. Mack Publishing.
Suitable formulations for enteral administration include hard or soft gelatin capsules, pills, tablets, including coated tablets, elixirs, suspensions, syrups or inhalations and controlled release forms thereof.
Formulations suitable for parenteral administration (e.g., by injection) include aqueous or non-aqueous, isotonic, pyrogen-free, sterile liquids (e.g., solutions, suspensions), in which the active ingredient is dissolved, suspended, or otherwise provided (e.g., in a liposome or other microparticulate). Such liquids may additionally contain other pharmaceutically acceptable carriers, such as anti -oxidants, buffers, preservatives, stabilizers, bacterio stats, suspending agents, thickening agents, and solutes that render the formulation isotonic with the blood (or other relevant bodily fluid) of the intended recipient. Examples of excipients include, for example, water, alcohols, polyols, glycerol, vegetable oils, and the like. Examples of suitable isotonic pharmaceutically acceptable carriers for use in such formulations include Sodium Chloride Injection, Ringer's Solution, or Lactated Ringer's Injection.
In particularly preferred embodiments formulated compositions of the present invention may be lyophilized to provide a powdered form of the antibody or ADC that may then be reconstituted prior to administration. Sterile powders for the preparation of injectable solutions may be generated by fyophilizing a solution comprising the disclosed antibodies or ADCs to yield a powder comprising the active ingredient along with any optional co-solubilized biocompatible ingredients. Generally, dispersions or solutions are prepared by incorporating the active compound into a sterile vehicle that contains a basic dispersion medium or solvent (e.g., a diluent) and, optionally, other biocompatible ingredients. A compatible diluent is one which is pharmaceutically acceptable (safe and non-toxic for administration to a human) and is useful for the preparation of a liquid formulation, such as a formulation reconstituted after iyophiiization. Exemplary diluents include sterile water, bacteriostatic water for injection (BWFI), a pH buffered solution (e.g. phosphate- buffered saline), sterile saline solution, Ringer's solution or dextrose solution. In an alternative embodiment, diluents can include aqueous solutions of salts and/or buffers.
In certain preferred embodiments the anti-KREMEN2 antibodies or ADCs will be lyophilized in combination with a pharmaceutically acceptable sugar. A "pharmaceutically acceptable sugar" is a molecule which, when combined with a protein of interest, significantly prevents or reduces chemical and/or physical instability of the protein upon storage. When the formulation is intended to be lyophilized and then reconstituted. As used herein pharmaceutically acceptable sugars may also be referred to as a "lyoproiectani". Exemplary sugars and their corresponding sugar alcohols include; an amino acid such as monosodium glutamate or histidine; a methylamine such as betaine; a lyotropic salt such as magnesium sulfate; a polyol such as trihydric or higher molecular weight sugar alcohols, e.g. glycerin, dextran, erythritol, glycerol, arabitol, xylitoi, sorbitol, and mannitol; propylene glycol; polyethylene glycol; PLURONICS*'; and combinations thereof. Additional exemplary lyoprotectants include glycerin and gelatin, and the sugars mellibiose, melezitose, raffinose, mannotriose and stachyose. Examples of reducing sugars include glucose, maltose, lactose, maltulose, iso-maltulose and lactulose. Examples of non- reducing sugars include non-reducing glycosides of polyhydroxy compounds selected from sugar alcohols and other straight chain polyalcohols. Preferred sugar alcohols are monoglycosides, especially those compounds obtained by reduction of disaccharides such as lactose, maltose, lactulose and maltutose. The glycosidic side group can be either glucosidic or galactosidic. Additional examples of sugar alcohols are glucitol, maititoi, lactitol and iso-niaitulose. The preferred pharniaceutically-acceptable sugars are the non-reducing sugars trehalose or sucrose. Pharmaceutically acceptable sugars are added to the formulation in a "protecting amount" (e.g. pre- iyophilization) which means that the protein essentially retains its physical and chemical stability and integrity during storage (e.g., after reconstitution and storage).
Whether reconstituted from lyophilized powder or not, the liquid KREMEN2 ADC formulations (e.g., as set forth immediately above) may be further diluted (preferably in an aqueous carrier) prior to administration. For example, the aforementioned liquid formulations may further be diluted into an infusion bag containing 0.9% Sodium Chloride Injection, USP, or equivalent {mutatis mutandis), to achieve the desired dose level for administration. In certain aspects the fully diluted KREMEN2 ADC solution will be administered via intravenous infusion using an IV apparatus. Preferably the administered KREMEN2 ADC drug solution (whether by intravenous (IV) infusion or injection) is clear, colorless and free from visible particulates.
The compounds and compositions of the invention may be administered in vivo, to a subject in need thereof, by various routes, including, but not limited to, oral, intravenous, intra-arterial, subcutaneous, parenteral, intranasal, intramuscular, intracardiac, intraventricular, intratracheal, buccal, rectal, intraperitoneal, intradermal, topical, transdermal, and intrathecal, or otherwise by implantation or inhalation. The subject compositions may be formulated into preparations in solid, semi-solid, liquid, or gaseous forms; including, but not limited to, tablets, capsules, powders, granules, ointments, solutions, suppositories, enemas, injections, inhalants, and aerosols. The appropriate formulation and route of administration may be selected according to the intended application and therapeutic regimen. B. Dosages and dosing regimens
The particular dosage regimen, i.e., dose, timing and repetition, will depend on the particular individual, as well as empirical considerations such as pharmacokinetics (e.g., half-life, clearance rate, etc.). Determination of the frequency of administration may be made by persons skilled in the art, such as an attending physician based on considerations of the condition and severity of the condition being treated, age and general state of health of the subject being treated and the like. Frequency of administration may be adjusted over the course of therapy based on assessment of the efficacy of the selected composition and the dosing regimen. Such assessment can be made on the basis of markers of the specific disease, disorder or condition. In embodiments where the individual has cancer, these include direct measurements of tumor size via palpation or visual observation; indirect measurement of tumor size by x-ray or other imaging techniques; an improvement as assessed by direct tumor biopsy and microscopic examination of a tumor sample; the measurement of an indirect tumor marker (e.g., PSA for prostate cancer) or an antigen identified according to the methods described herein; reduction in the number of proliferative or tumorigenic cells, maintenance of the reduction of such neoplastic cells; reduction of the proliferation of neoplastic cells; or delay in the development of metastasis.
The KREMEN2 antibodies or ADCs of the invention may be administered in various ranges. These include about 5 μg/kg body weight to about 100 mg/kg body weight per dose; about 50 μg/kg body weight to about 5 mg/kg body weight per dose; about 100 μg/kg body weight to about 10 mg/kg body weight per dose. Other ranges include about 100 μg/kg body weight to about 20 mg/kg body weight per dose and about 0.5 mg/kg body weight to about 20 mg/kg body weight per dose. In certain embodiments, the dosage is at least about 100 μg/kg body weight, at least about 250 μg/kg body weight, at least about 750 μg/kg body weight, at least about 3 mg/kg body weight, at least about 5 mg/kg body weight, at least about 10 mg/kg body weight.
In selected embodiments the KREMEN2 antibodies or ADCs will be administered (preferably intravenously) at approximately 10, 20, 30, 40, 50, 60, 70, 80, 90 or 100 μg/kg body weight per dose. Other embodiments may comprise the administration of antibodies or ADCs at about 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900 or 2000 μg/kg body weight per dose. In other embodiments the disclosed conjugates will be administered at 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 9 or 10 mg/kg. In still other embodiments the conjugates may be administered at 12, 14, 16, 18 or 20 mg/kg body weight per dose. In yet other embodiments the conjugates may be administered at 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 90 or 100 mg/kg body weight per dose. With the teachings herein one of skill in the art could readily determine appropriate dosages for various KREMEN2 antibodies or ADCs based on preclinical animal studies, clinical observations and standard medical and biochemical techniques and measurements.
Other dosing regimens may be predicated on Body Surface Area (BSA) calculations as disclosed in U.S. P.N. 7,744,877. As is well known, the BSA is calculated using the patient's height and weight and provides a measure of a subject's size as represented by the surface area of his or her body. In certain embodiments, the conjugates may be administered in dosages from 1 mg/m2 to
800 mg/m 2 , from 50 mg/m 2 to 500 mg/m 2 and at dosages of 100 mg/m 2 , 150 mg/m 2 , 200 mg/m 2 , 250 mg/m 2 , 300 mg/m 2 , 350 mg/m 2 , 400 mg/m 2 or 450 mg/m 2. It will also be appreciated that art recognized and empirical techniques may be used to determine appropriate dosage.
Anti-KREMEN2 antibodies or ADCs may be administered on a specific schedule. Generally, an effective dose of the KREMEN2 conjugate is administered to a subject one or more times. More particularly, an effective dose of the ADC is administered to the subject once a month, more than once a month, or less than once a month. In certain embodiments, the effective dose of the KREMEN2 antibody or ADC may be administered multiple times, including for periods of at least a month, at least six months, at least a year, at least two years or a period of several years. In yet other embodiments, several days (2, 3, 4, 5, 6 or 7), several weeks (1, 2, 3, 4, 5, 6, 7 or 8) or several months (1, 2, 3, 4, 5, 6, 7 or 8) or even a year or several years may lapse between administration of the disclosed antibodies or ADCs.
In some embodiments the course of treatment involving conjugated antibodies will comprise multiple doses of the selected drug product over a period of weeks or months. More specifically, antibodies or ADCs of the instant invention may administered once every day, every two days, every four days, every week, every ten days, every two weeks, every three weeks, every month, every six weeks, every two months, every ten weeks or every three months. In this regard it will be appreciated that the dosages may be altered or the interval may be adjusted based on patient response and clinical practices. The invention also contemplates discontinuous administration or daily doses divided into several partial administrations. The compositions of the instant invention and anti-cancer agent may be administered interchangeably, on alternate days or weeks; or a sequence of antibody treatments may be given, followed by one or more treatments of anti-cancer agent therapy. In any event, as will be understood by those of ordinary skill in the art, the appropriate doses of chemotherapeutic agents will be generally around those already employed in clinical therapies wherein the chemotherapeutics are administered alone or in combination with other chemotherapeutics.
In another embodiment the KREMEN2 antibodies or ADCs of the instant invention may be used in maintenance therapy to reduce or eliminate the chance of tumor recurrence following the initial presentation of the disease. Preferably the disorder will have been treated and the initial tumor mass eliminated, reduced or otherwise ameliorated so the patient is asymptomatic or in remission. At such time the subject may be administered pharmaceutically effective amounts of the disclosed antibodies one or more times even though there is little or no indication of disease using standard diagnostic procedures.
In another preferred embodiment the modulators of the present invention may be used to prophylactically or as an adjuvant therapy to prevent or reduce the possibility of tumor metastasis following a debulking procedure. As used in the instant disclosure a "debulking procedure" means any procedure, technique or method that reduces the tumor mass or ameliorates the tumor burden or tumor proliferation. Exemplary debulking procedures include, but are not limited to, surgery, radiation treatments (i.e., beam radiation), chemotherapy, immunotherapy or ablation. At appropriate times readily determined by one skilled in the art in view of the instant disclosure the disclosed ADCs may be administered as suggested by clinical, diagnostic or theragnostic procedures to reduce tumor metastasis.
Yet other embodiments of the invention comprise administering the disclosed antibodies or
ADCs to subjects that are asymptomatic but at risk of developing cancer. That is, the antibodies or ADCs of the instant invention may be used in a truly preventative sense and given to patients that have been examined or tested and have one or more noted risk factors (e.g., genomic indications, family history, in vivo or in vitro test results, etc.) but have not developed neoplasia.
Dosages and regimens may also be determined empirically for the disclosed therapeutic compositions in individuals who have been given one or more administration(s). For example, individuals may be given incremental dosages of a therapeutic composition produced as described herein. In selected embodiments the dosage may be gradually increased or reduced or attenuated based respectively on empirically determined or observed side effects or toxicity. To assess efficacy of the selected composition, a marker of the specific disease, disorder or condition can be followed as described previously. For cancer, these include direct measurements of tumor size via palpation or visual observation, indirect measurement of tumor size by x-ray or other imaging techniques; an improvement as assessed by direct tumor biopsy and microscopic examination of the tumor sample; the measurement of an indirect tumor marker (e.g., PSA for prostate cancer) or a tumorigenic antigen identified according to the methods described herein, a decrease in pain or paralysis; improved speech, vision, breathing or other disability associated with the tumor; increased appetite; or an increase in quality of life as measured by accepted tests or prolongation of survival. It will be apparent to one of skill in the art that the dosage will vary depending on the individual, the type of neoplastic condition, the stage of neoplastic condition, whether the neoplastic condition has begun to metastasize to other location in the individual, and the past and concurrent treatments being used. C. Combination Therapies
As alluded to above combination therapies may be particularly useful in decreasing or inhibiting unwanted neoplastic cell proliferation, decreasing the occurrence of cancer, decreasing or preventing the recurrence of cancer, or decreasing or preventing the spread or metastasis of cancer. In such cases the antibodies or ADCs of the instant invention may function as sensitizing or chemosensitizing agents by removing CSCs that would otherwise prop up and perpetuate the tumor mass and thereby allow for more effective use of current standard of care debulking or anti -cancer agents. That is, the disclosed antibodies or ADCs may, in certain embodiments, provide an enhanced effect (e.g., additive or synergistic in nature) that potentiates the mode of action of another administered therapeutic agent. In the context of the instant invention "combination therapy" shall be interpreted broadly and merely refers to the administration of an anti-KREMEN2 antibody or ADC and one or more anti-cancer agents that include, but are not limited to, cytotoxic agents, cytostatic agents, anti-angiogenic agents, debulking agents, chemotherapeutic agents, radiotherapy and radiotherapeutic agents, targeted anti-cancer agents (including both monoclonal antibodies and small molecule entities), BRMs, therapeutic antibodies, cancer vaccines, cytokines, hormone therapies, radiation therapy and anti-metastatic agents and immunotherapeutic agents, including both specific and non-specific approaches.
There is no requirement for the combined results to be additive of the effects observed when each treatment (e.g., antibody and anti-cancer agent) is conducted separately. Although at least additive effects are generally desirable, any increased anti-tumor effect above one of the single therapies is beneficial. Furthermore, the invention does not require the combined treatment to exhibit synergistic effects. However, those skilled in the art will appreciate that with certain selected combinations that comprise preferred embodiments, synergism may be observed.
As such, in certain aspects the combination therapy has therapeutic synergy or improves the measurable therapeutic effects in the treatment of cancer over (i) the anti-KREMEN2 antibody or ADC used alone, or (ii) the therapeutic moiety used alone, or (iii) the use of the therapeutic moiety in combination with another therapeutic moiety without the addition of an anti-KREMEN2 antibody or ADC. The term "therapeutic synergy", as used herein, means the combination of an anti- KREMEN2 antibody or ADC and one or more therapeutic moiety(ies) having a therapeutic effect greater than the additive effect of the combination of the anti-KREMEN2 antibody or ADC and the one or more therapeutic moiety(ies).
Desired outcomes of the disclosed combinations are quantified by comparison to a control or baseline measurement. As used herein, relative terms such as "improve," "increase," or "reduce" indicate values relative to a control, such as a measurement in the same individual prior to initiation of treatment described herein, or a measurement in a control individual (or multiple control individuals) in the absence of the anti-KREMEN2 antibodies or ADCs described herein but in the presence of other therapeutic moiety(ies) such as standard of care treatment. A representative control individual is an individual afflicted with the same form of cancer as the individual being treated, who is about the same age as the individual being treated (to ensure that the stages of the disease in the treated individual and the control individual are comparable).
A synergistic therapeutic effect may be an effect of at least about two-fold greater than the therapeutic effect elicited by a single therapeutic moiety or anti-KREMEN2 antibody or ADC, or the sum of the therapeutic effects elicited by the anti-KREMEN2 antibody or ADC or the single therapeutic moiety(ies) of a given combination, or at least about five-fold greater, or at least about ten-fold greater, or at least about twenty-fold greater, or at least about fifty-fold greater, or at least about one hundred-fold greater. A synergistic therapeutic effect may also be observed as an increase in therapeutic effect of at least 10% compared to the therapeutic effect elicited by a single therapeutic moiety or anti-KREMEN2 antibody or ADC, or the sum of the therapeutic effects elicited by the anti-KREMEN2 antibody or ADC or the single therapeutic moiety(ies) of a given combination, or at least 20%, or at least 30%, or at least 40%, or at least 50%, or at least 60%, or at least 70%, or at least 80%, or at least 90%, or at least 100%, or more. A synergistic effect is also an effect that permits reduced dosing of therapeutic agents when they are used in combination.
In practicing combination therapy, the anti-KREMEN2 antibody or ADC and therapeutic moiety(ies) may be administered to the subject simultaneously, either in a single composition, or as two or more distinct compositions using the same or different administration routes. Alternatively, treatment with the anti-KREMEN2 antibody or ADC may precede or follow the therapeutic moiety treatment by, e.g., intervals ranging from minutes to weeks. In one embodiment, both the therapeutic moiety and the antibody or ADC are administered within about 5 minutes to about two weeks of each other. In yet other embodiments, several days (2, 3, 4, 5, 6 or 7), several weeks (1, 2, 3, 4, 5, 6, 7 or 8) or several months (1, 2, 3, 4, 5, 6, 7 or 8) may lapse between administration of the antibody and the therapeutic moiety.
The combination therapy can be administered until the condition is treated, palliated or cured on various schedules such as once, twice or three times daily, once every two days, once every three days, once weekly, once every two weeks, once every month, once every two months, once every three months, once every six months, or may be administered continuously. The antibody and therapeutic moiety(ies) may be administered on alternate days or weeks; or a sequence of anti- KREMEN2 antibody or ADC treatments may be given, followed by one or more treatments with the additional therapeutic moiety. In one embodiment an anti-KREMEN2 antibody or ADC is administered in combination with one or more therapeutic moiety(ies) for short treatment cycles. In other embodiments the combination treatment is administered for long treatment cycles. The combination therapy can be administered via any route.
In selected embodiments the compounds and compositions of the present invention may be used in conjunction with checkpoint inhibitors such as PD-1 inhibitors or PD-Ll inhibitors. PD-1, together with its ligand PD-Ll, are negative regulators of the antitumor T lymphocyte response. In one embodiment the combination therapy may comprise the administration of anti-KREMEN2 antibodies or ADCs together with an anti-PD-1 antibody (e.g. pembrolizumab, nivolumab, pidilizumab) and optionally one or more other therapeutic moiety(ies). In another embodiment the combination therapy may comprise the administration of anti- KREMEN2 antibodies or ADCs together with an anti -PD-Ll antibody (e.g. avelumab, atezolizumab, durvalumab) and optionally one or more other therapeutic moiety(ies). In yet another embodiment, the combination therapy may comprise the administration of anti-KREMEN2 antibodies or ADCs together with an anti PD-1 antibody or anti-PD-Ll administered to patients who continue progress following treatments with checkpoint inhibitors and/or targeted BRAF combination therapies (e.g. vemurafenib or dabrafinib).
In some embodiments the anti-KREMEN2 antibodies or ADCs may be used in combination with various first line cancer treatments. Thus, in selected embodiments the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and a cytotoxic agent such as ifosfamide, mitomycin C, vindesine, vinblastine, etoposide, ironitecan, gemcitabine, taxanes, vinorelbine, methotrexate, and pemetrexed) and optionally one or more other therapeutic moiety(ies). In certain neoplastic indications (e.g., hematological indications such as AML or multiple myeloma) the disclosed ADCs may be used in combination with cytotoxic agents such as cytarabine (AraC) plus an anthracycyline (aclarubicin, amsacrine, doxorubicin, daunorubicin, idarubixcin, etc.) or mitoxantrone, fludarabine; hydroxyurea, clofarabine, cloretazine. In other embodiments the ADCs of the invention may be administered in combination with G-CSF or GM-CSF priming, demethylating agents such as azacitidine or decitabine, FLT3 -selective tyrosine kinase inhibitors (eg, midostaurin, lestaurtinib and sunitinib), all-trans retinoic acid (ATRA) and arsenic trioxide (where the last two combinations may be particularly effective for acute promyelocytic leukemia (API.,)).
In another embodiment the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and a platinum-based drug (e.g. carboplatin or cisplatin) and optionally one or more other therapeutic moiety(ies) (e.g. vinorelbine; gemcitabine; a taxane such as, for example, docetaxel or paclitaxel; irinotecan; or pemetrexed).
In certain embodiments, for example in the treatment of BR-ERPR, BR-ER or BR-PR cancer, the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and one or more therapeutic moieties described as "hormone therapy". "Hormone therapy" as used herein, refers to, e.g., tamoxifen; gonadotropin or luteinizing releasing hormone (GnRH or LHRH); everolimus and exemestane; toremifene; or aromatase inhibitors (e.g. anastrozole, letrozole, exemestane or fulvestrant).
In another embodiment, for example, in the treatment of BR-HER2, the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and trastuzumab or ado-trastuzumab emtansine (Kadcyla) and optionally one or more other therapeutic moiety(ies) (e.g. pertuzumab and/or docetaxel).
In some embodiments, for example, in the treatment of metastatic breast cancer, the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and a taxane (e.g. docetaxel or paclitaxel) and optionally an additional therapeutic moiety(ies), for example, an anthracycline (e.g. doxorubicin or epirubicin) and/or eribulin.
In another embodiment, for example, in the treatment of metastatic or recurrent breast cancer or BRCA-mutant breast cancer, the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and megestrol and optionally an additional therapeutic moiety(ies).
In further embodiments, for example, in the treatment of BR-T BC, the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and a poly ADP ribose polymerase (PARP) inhibitor (e.g. BMN-673, olaparib, rucaparib and veliparib) and optionally an additional therapeutic moiety(ies).
In another embodiment the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and a PARP inhibitor and optionally one or more other therapeutic moiety(ies).
In another embodiment, for example, in the treatment of breast cancer, the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and cyclophosphamide and optionally an additional therapeutic moiety(ies) (e.g. doxorubicin, a taxane, epirubicin, 5-FU and/or methotrexate.
In another embodiment combination therapy for the treatment of EGFR-positive NSCLC comprises the use of an anti-KREMEN2 antibody or ADC and afatinib and optionally one or more other therapeutic moiety(ies) (e.g. erlotinib and/or bevacizumab).
In another embodiment combination therapy for the treatment of EGFR-positive NSCLC comprises the use of an anti-KREMEN2 antibody or ADC and erlotinib and optionally one or more other therapeutic moiety(ies) (e.g. bevacizumab).
In another embodiment combination therapy for the treatment of ALK-positive NSCLC comprises the use of an anti-KREMEN2 antibody or ADC and ceritinib (Zykadia) and optionally one or more other therapeutic moiety(ies).
In another embodiment combination therapy for the treatment of ALK-positive NSCLC comprises the use of an anti-KREMEN2 antibody or ADC and crizotinib (Xalcori) and optionally one or more other therapeutic moiety(ies).
In another embodiment the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and bevacizumab and optionally one or more other therapeutic moiety(ies) (e.g. gemcitabine or a taxane such as, for example, docetaxel or paclitaxel; and/or a platinum analog).
In another embodiment the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and bevacizumab and optionally cyclophosphamide.
In a particular embodiment the combination therapy for the treatment of platinum -resistant tumors comprises the use of an anti-KREMEN2 antibody or ADC and doxorubicin and/or etoposide and/or gemcitabine and/or vinorelbine and/or ifosfamide and/or leucovorin-modulated 5-fluoroucil and/or bevacizumab and/or tamoxifen; and optionally one or more other therapeutic moiety(ies). In selected embodiments the disclosed antibodies and ADCs may be used in combination with certain steroids to potentially make the course of treatment more effective and reduce side effects such as inflammation, nausea and hypersensitivity. Exemplary steroids that may be used on combination with the ADCs of the instant invention include, but are not limited to, hydrocortisone, dexamethasone, methylprednisolone and prednisolone. In particularly preferred aspects the steroid will comprise dexamethasone
In some embodiments the anti-KREMEN2 antibodies or ADCs may be used in combination with various first line melanoma treatments. In one embodiment the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and dacarbazine and optionally one or more other therapeutic moiety(ies). In further embodiments the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and temozolamide and optionally one or more other therapeutic moiety(ies). In another embodiment the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and a platinum-based therapeutic moiety (e.g. carboplatin or cisplatin) and optionally one or more other therapeutic moiety(ies). In some embodiments the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and a vinca alkaloid therapeutic moiety (e.g. vinblastine, vinorelbine, vincristine, or vindesine) and optionally one or more other therapeutic moiety(ies). In one embodiment the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and interleukin-2 and optionally one or more other therapeutic moiety(ies). In another embodiment the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and interferon-alpha and optionally one or more other therapeutic moiety(ies).
In other embodiments, the anti-KREMEN2 antibodies or ADCs may be used in combination with adjuvant melanoma treatments and/or a surgical procedure (e.g. tumor resection.) In one embodiment the combination therapy comprises the use of an anti-KREMEN2 antibody or ADC and interferon-alpha and optionally one or more other therapeutic moiety(ies).
The invention also provides for the combination of anti-KREMEN2 antibodies or ADCs with radiotherapy. The term "radiotherapy", as used herein, means, any mechanism for inducing DNA damage locally within tumor cells such as gamma-irradiation, X-rays, UV-irradiation, microwaves, electronic emissions and the like. Combination therapy using the directed delivery of radioisotopes to tumor cells is also contemplated, and may be used in combination or as a conjugate of the anti- KREMEN2 antibodies disclosed herein. Typically, radiation therapy is administered in pulses over a period of time from about 1 to about 2 weeks. Optionally, the radiation therapy may be administered as a single dose or as multiple, sequential doses.
In other embodiments an anti-KREMEN2 antibody or ADC may be used in combination with one or more of the chemotherapeutic agents described below. D. Anti-Cancer Agents
The term "anti-cancer agent" as used herein is one subset of "therapeutic moieties", which in turn is a subset of the agents described as "pharmaceutically active moieties". More particularly "anti-cancer agent" means any agent (or a pharmaceutically acceptable salt thereof) that can be used to treat a cell proliferative disorder such as cancer, and includes, but is not limited to, cytotoxic agents, cytostatic agents, anti-angiogenic agents, debulking agents, chemotherapeutic agents, radiotherapeutic agents, targeted anti-cancer agents, biological response modifiers, therapeutic antibodies, cancer vaccines, cytokines, hormone therapy, anti-metastatic agents and immunotherapeutic agents. Note that the foregoing classifications of anti-cancer agents are not exclusive of each other and that selected agents may fall into one or more categories. For example, a compatible anti-cancer agent may be classified as a cytotoxic agent and a chemotherapeutic agent. Accordingly, each of the foregoing terms should be construed in view of the instant disclosure and then in accordance with their use in the medical arts.
In preferred embodiments an anti-cancer agent can include any chemical agent (e.g., a chemotherapeutic agent) that inhibits or eliminates, or is designed to inhibit or eliminate, a cancerous cell or a cell likely to become cancerous or generate tumorigenic progeny (e.g., tumorigenic cells). In this regard selected chemical agents (cell-cycle dependent agents) are often directed to intracellular processes necessary for cell growth or division, and are thus particularly effective against cancerous cells, which generally grow and divide rapidly. For example, vincristine depolymerizes microtubules and thus inhibits rapidly dividing tumor cells from entering mitosis. In other cases the selected chemical agents are cell-cycle independent agents that interfere with cell survival at any point of its lifecycle and may be effective in directed therapeutics (e.g., ADCs). By way of example certain pyrrolobenzodiazepines bind to the minor groove of cellular DNA and inhibit transcription upon delivery to the nucleus. With regard to combination therapy or selection of an ADC component it will be appreciated that one skilled in the art could readily identify compatible cell-cycle dependent agents and cell-cycle independent agents in view of the instant disclosure.
In any event, and as alluded to above, it will be appreciated that the selected anti -cancer agents may be administered in combination with each other (e.g., CHOP therapy) in addition to the disclosed anti-KREMEN2 antibodies and ADCs disclosed herein. Moreover, it will further be appreciated that in selected embodiments such anti-cancer agents may comprise conjugates and may be associated with antibodies prior to administration. In certain embodiments the disclosed anticancer agent will be linked to an anti-KREMEN2 antibody to provide an ADC as disclosed herein.
As used herein the term "cytotoxic agent" (or cytotoxin) generally means a substance that is toxic to cells in that it decreases or inhibits cellular function and/or causes the destruction of tumor cells. In certain embodiments the substance is a naturally occurring molecule derived from a living organism or an analog thereof (purified from natural sources or synthetically prepared). Examples of cytotoxic agents include, but are not limited to, small molecule toxins or enzymatically active toxins of bacteria (e.g., calicheamicin, Diptheria toxin, Pseudomonas endotoxin and exotoxin, Staphylococcal enterotoxin A), fungal (e.g., a-sarcin, restrictocin), plants (e.g., abrin, ricin, modeccin, viscumin, pokeweed anti-viral protein, saporin, gelonin, momoridin, trichosanthin, barley toxin, Aleurites fordii proteins, dianthin proteins, Phytolacca mericana proteins [PAPI, PAPII, and PAP-S], Momordica charantia inhibitor, curcin, crotin, saponaria officinalis inhibitor, mitegellin, restrictocin, phenomycin, neomycin, and the tricothecenes) or animals, (e.g., cytotoxic RNases, such as extracellular pancreatic RNases; DNase I, including fragments and/or variants thereof). Additional compatible cytotoxic agents including certain radioisotopes, maytansinoids, auristatins, dolastatins, duocarmycins, amanitins and pyrrolobenzodiazepines are set forth herein.
More generally examples of cytotoxic agents or anti-cancer agents that may be used in combination with (or conjugated to) the antibodies of the invention include, but are not limited to, alkylating agents, alkyl sulfonates, anastrozole, amanitins, aziridines, ethylenimines and methylamelamines, acetogenins, a camptothecin, BEZ-235, bortezomib, bryostatin, callystatin, CC- 1065, ceritinib, crizotinib, cryptophycins, dolastatin, duocarmycin, eleutherobin, erlotinib, pancratistatin, a sarcodictyin, spongistatin, nitrogen mustards, antibiotics, enediyne dynemicin, bisphosphonates, esperamicin, chromoprotein enediyne antiobiotic chromophores, aclacinomysins, actinomycin, authramycin, azaserine, bleomycins, cactinomycin, canfosfamide, carabicin, carminomycin, carzinophilin, chromomycinis, cyclosphosphamide, dactinomycin, daunorubicin, detorubicin, 6-diazo-5-oxo-L-norleucine, doxorubicin, epirubicin, esorubicin, exemestane, fluorouracil, fulvestrant, gefitinib, idarubicin, lapatinib, letrozole, lonafarnib, marcellomycin, megestrol acetate, mitomycins, mycophenolic acid, nogalamycin, olivomycins, pazopanib, peplomycin, potfiromycin, puromycin, quelamycin, rapamycin, rodorubicin, sorafenib, streptonigrin, streptozocin, tamoxifen, tamoxifen citrate, temozolomide, tepodina, tipifarnib, tubercidin, ubenimex, vandetanib, vorozole, XL-147, zinostatin, zorubicin; anti-metabolites, folic acid analogues, purine analogs, androgens, anti -adrenals, folic acid replenisher such as frolinic acid, aceglatone, aldophosphamide glycoside, aminolevulinic acid, eniluracil, amsacrine, bestrabucil, bisantrene, edatraxate, defofamine, demecolcine, diaziquone, elfornithine, elliptinium acetate, epothilone, etoglucid, gallium nitrate, hydroxyurea, lentinan, lonidainine, maytansinoids, mitoguazone, mitoxantrone, mopidanmol, nitraerine, pentostatin, phenamet, pirarubicin, losoxantrone, podophyllinic acid, 2- ethylhydrazide, procarbazine, polysaccharide complex, razoxane; rhizoxin; SF-1126, sizofiran; spirogermanium; tenuazonic acid; triaziquone; 2,2',2"- trichlorotriethylamine; trichothecenes (T-2 toxin, verracurin A, roridin A and anguidine); urethan; vindesine; dacarbazine; mannomustine; mitobronitol; mitolactol; pipobroman; gacytosine; arabinoside; cyclophosphamide; thiotepa; taxoids, chloranbucil; gemcitabine; 6-thioguanine; mercaptopurine; methotrexate; platinum analogs, vinblastine; platinum; etoposide; ifosfamide; mitoxantrone; vincristine; vinorelbine; novantrone; teniposide; edatrexate; daunomycin; aminopterin; xeloda; ibandronate; irinotecan, topoisomerase inhibitor RFS 2000; difluorometlhyl ornithine; retinoids; capecitabine; combretastatin; leucovorin; oxaliplatin; XL518, inhibitors of PKC-alpha, Raf, H-Ras, EGFR and VEGF-A that reduce cell proliferation and pharmaceutically acceptable salts or solvates, acids or derivatives of any of the above. Also included in this definition are anti-hormonal agents that act to regulate or inhibit hormone action on tumors such as anti-estrogens and selective estrogen receptor antibodies, aromatase inhibitors that inhibit the enzyme aromatase, which regulates estrogen production in the adrenal glands, and anti- androgens; as well as troxacitabine (a 1,3- dioxolane nucleoside cytosine analog); antisense oligonucleotides, ribozymes such as a VEGF expression inhibitor and a HER2 expression inhibitor; vaccines, PROLEUKIN® rIL-2; LURTOTECAN® topoisomerase 1 inhibitor; ABARELLX® rmRH; Vinorelbine and Esperamicins and pharmaceutically acceptable salts or solvates, acids or derivatives of any of the above.
Compatible cytotoxic agents or anti-cancer agents may also comprise commercially or clinically available compounds such as erlotinib (TARCEVA , Genentech/OSI Pharm.), docetaxel (TAXOTERE®, Sanofi-Aventis), 5-FU (fluorouracil, 5-fluorouracil, CAS No. 51-21-8), gemcitabine (GEMZAR®, Lilly), PD-0325901 (CAS No. 391210-10-9, Pfizer), cisplatin (cis- diamine, dichloroplatinum(II), CAS No. 15663-27-1), carboplatin (CAS No. 41575-94-4), paclitaxel (TAXOL®, Bristol-Myers Squibb Oncology, Princeton, N.J.), trastuzumab (HERCEPTIN®, Genentech), temozolomide (4-methyl-5-oxo- 2,3,4,6,8-pentazabicyclo [4.3.0] nona-2,7,9-triene- 9-carboxamide, CAS No. 85622-93-1, TEMODAR®, TEMODAL®, Schering Plough), tamoxifen ((Z)-2-[4-(l,2-diphenylbut-l-enyl)phenoxy]-N,N-dimethylethanamine, NOLVADEX®, ISTUBAL®, VALODEX®), and doxorubicin (ADRIAMYCIN®). Additional commercially or clinically available anti-cancer agents comprise ibrutinib (J BRUVICA®, Abb Vie) oxaliplatin (ELOXATIN®, Sanofi), bortezomib (VELCADE®, Millennium Pharm.), sutent (SUNITINIB®, SU11248, Pfizer), letrozole (FEMARA®, Novartis), imatinib mesylate (GLEEVEC®, Novartis), XL-518 (Mek inhibitor, Exelixis, WO 2007/044515), ARRY-886 (Mek inhibitor, AZD6244, Array BioPharma, Astra Zeneca), SF-1126 (PI3K inhibitor, Semafore Pharmaceuticals), BEZ-235 (PI3K inhibitor, Novartis), XL-147 (PI3K inhibitor, Exelixis), PTK787/ZK 222584 (Novartis), fulvestrant (FASLODEX®, AstraZeneca), leucovorin (folinic acid), rapamycin (sirolimus, RAPAMUNE®, Wyeth), lapatinib (TYKERB®, GSK572016, Glaxo Smith Kline), lonafarnib (SARASAR™, SCH 66336, Schering Plough), sorafenib (NEXAVAR®, BAY43- 9006, Bayer Labs), gefitinib (IRESSA®, AstraZeneca), irinotecan (CAMPTOSAR®, CPT-11, Pfizer), tipifarnib (ZARNESTRA™, Johnson & Johnson), ABRAXANE™ (Cremophor-free), albumin-engineered nanoparticle formulations of paclitaxel (American Pharmaceutical Partners, Schaumberg, II), vandetanib (rINN, ZD6474, ZACTJJVIA®, AstraZeneca), chloranmbucil, AG1478, AG1571 (SU 5271; Sugen), temsirolimus (TORISEL®, Wyeth), pazopanib (GlaxoSmithKline), canfosfamide (TELCYTA®, Telik), thiotepa and cyclosphosphamide (CYTOXAN®, NEOSAR®); vinorelbine (NAVELBINE®); capecitabine (XELODA®, Roche), tamoxifen (including NOLVADEX®; tamoxifen citrate, FARESTON® (toremifine citrate) MEGASE® (megestrol acetate), AROMASIN® (exemestane; Pfizer), formestanie, fadrozole, RJVISOR® (vorozole), FEMARA® (letrozole; Novartis), and ARFMIDEX® (anastrozole; AstraZeneca).
The term "pharmaceutically acceptable salt" or "salt" means organic or inorganic salts of a molecule or macromolecule. Acid addition salts can be formed with amino groups. Exemplary salts include, but are not limited, to sulfate, citrate, acetate, oxalate, chloride, bromide, iodide, nitrate, bisulfate, phosphate, acid phosphate, isonicotinate, lactate, salicylate, acid citrate, tartrate, oleate, tannate, pantothenate, bitartrate, ascorbate, succinate, maleate, gentisinate, fumarate, gluconate, glucuronate, saccharate, formate, benzoate, glutamate, methanesulfonate, ethanesulfonate, benzenesulfonate, p-toluenesulfonate, and pamoate (i.e., 1,1 ' methylene bis-(2-hydroxy 3- naphthoate)) salts. A pharmaceutically acceptable salt may involve the inclusion of another molecule such as an acetate ion, a succinate ion or other counterion. The counterion may be any organic or inorganic moiety that stabilizes the charge on the parent compound. Furthermore, a pharmaceutically acceptable salt may have more than one charged atom in its structure. Where multiple charged atoms are part of the pharmaceutically acceptable salt, the salt can have multiple counter ions. Hence, a pharmaceutically acceptable salt can have one or more charged atoms and/or one or more counterion.
Similarly, a "pharmaceutically acceptable solvate" or "solvate" refers to an association of one or more solvent molecules and a molecule or macromolecule. Examples of solvents that form pharmaceutically acceptable solvates include, but are not limited to, water, isopropanol, ethanol, methanol, DMSO, ethyl acetate, acetic acid, and ethanolamine.
In other embodiments the antibodies or ADCs of the instant invention may be used in combination with any one of a number of antibodies (or immunotherapeutic agents) presently in clinical trials or commercially available. The disclosed antibodies may be used in combination with an antibody selected from the group consisting of abagovomab, adecatumumab, afutuzumab, alemtuzumab, altumomab, amatuximab, anatumomab, arcitumomab, atezolizumab, avelumab, bavituximab, bectumomab, bevacizumab, bivatuzumab, blinatumomab, brentuximab, cantuzumab, catumaxomab, cetuximab, citatuzumab, cixutumumab, clivatuzumab, conatumumab, dacetuzumab, dalotuzumab, daratumumab, detumomab, drozitumab, duligotumab, durvalumab, dusigitumab, ecromeximab, elotuzumab, ensituximab, ertumaxomab, etaracizumab, farletuzumab, ficlatuzumab, figitumumab, flanvotumab, futuximab, ganitumab, gemtuzumab, girentuximab, glembatumumab, ibritumomab, igovomab, imgatuzumab, indatuximab, inotuzumab, intetumumab, ipilimumab, iratumumab, labetuzumab, lambrolizumab, lexatumumab, lintuzumab, lorvotuzumab, lucatumumab, mapatumumab, matuzumab, milatuzumab, minretumomab, mitumomab, moxetumomab, narnatumab, naptumomab, necitumumab, nimotuzumab, nivolumab, nofetumomabn, obinutuzumab, ocaratuzumab, ofatumumab, olaratumab, olaparib, onartuzumab, oportuzumab, oregovomab, panitumumab, parsatuzumab, patritumab, pembrolizumab pemtumomab, pertuzumab, pidilizumab, pintumomab, pritumumab, racotumomab, radretumab, ramucirumab, rilotumumab, rituximab, robatumumab, satumomab, selumetinib, sibrotuzumab, siltuximab, simtuzumab, solitomab, tacatuzumab, taplitumomab, tenatumomab, teprotumumab, tigatuzumab, tositumomab, trastuzumab, tucotuzumab, ublituximab, veltuzumab, vorsetuzumab, votumumab, zalutumumab, CC49, 3F8, MEDI0680, MDX-1105 and combinations thereof.
Other embodiments comprise the use of antibodies approved for cancer therapy including, but not limited to, rituximab, gemtuzumab ozogamcin, alemtuzumab, ibritumomab tiuxetan, tositumomab, bevacizumab, cetuximab, patitumumab, ofatumumab, ipilimumab and brentuximab vedotin. Those skilled in the art will be able to readily identify additional anti -cancer agents that are compatible with the teachings herein.
E. Radiotherapy
The present invention also provides for the combination of antibodies or ADCs with radiotherapy (i.e., any mechanism for inducing DNA damage locally within tumor cells such as gamma-irradiation, X-rays, UV-irradiation, microwaves, electronic emissions and the like). Combination therapy using the directed delivery of radioisotopes to tumor cells is also contemplated, and the disclosed antibodies or ADCs may be used in connection with a targeted anticancer agent or other targeting means. Typically, radiation therapy is administered in pulses over a period of time from about 1 to about 2 weeks. The radiation therapy may be administered to subjects having head and neck cancer for about 6 to 7 weeks. Optionally, the radiation therapy may be administered as a single dose or as multiple, sequential doses.
VIII. Indications
The invention provides for the use of antibodies and ADCs of the invention for the diagnosis, theragnosis, treatment and/or prophylaxis of various disorders including neoplastic, inflammatory, angiogenic and immunologic disorders and disorders caused by pathogens. In certain embodiments the diseases to be treated comprise neoplastic conditions comprising solid tumors. In other embodiments the diseases to be treated comprise hematologic malignancies. In certain embodiments the antibodies or ADCs of the invention will be used to treat tumors or tumorigenic cells expressing a KREMEN2 determinant. Preferably the "subject" or "patient" to be treated will be human although, as used herein, the terms are expressly held to comprise any mammalian species. It will be appreciated that the compounds and compositions of the instant invention may be used to treat subjects at various stages of disease and at different points in their treatment cycle. Accordingly, in certain embodiments the antibodies and ADCs of the instant invention will be used as a front line therapy and administered to subjects who have not previously been treated for the cancerous condition. In other embodiments the antibodies and ADCs of the invention will be used to treat second and third line patients (i.e., those subjects that have previously been treated for the same condition one or two times respectively). Still other embodiments will comprise the treatment of fourth line or higher patients (e.g., gastric or colorectal cancer patients) that have been treated for the same or related condition three or more times with the disclosed KREMEN2 ADCs or with different therapeutic agents. In other embodiments the compounds and compositions of the present invention will be used to treat subjects that have previously been treated (with antibodies or ADCs of the present invention or with other anti-cancer agents) and have relapsed or are determined to be refractory to the previous treatment. In selected embodiments the compounds and compositions of the instant invention may be used to treat subjects that have recurrent tumors.
In certain aspects the proliferative disorder will comprise a solid tumor including, but not limited to, adrenal, liver, kidney, bladder, breast, gastric, ovarian, cervical, uterine, esophageal, colorectal, prostate, pancreatic, lung (both small cell and non-small cell including lung adenocarcinoma), thyroid, carcinomas, sarcomas, glioblastomas and various head and neck tumors. In other preferred embodiments the disclosed ADCs are particularly effective at treating squamous cell lung cancer (SCC-LU) and, in selected aspects, luminal B breast cancer B (BR-LumB). In certain embodiments the lung cancer is refractory, relapsed or resistant to anthracyclines and/or a taxane (e.g., docetaxel, paclitaxel, larotaxel or cabazitaxel). In still other aspects of the invention the disclosed antibodies and ADCs may be used for the treatment of medullary thyroid cancer, large cell neuroendocrine carcinoma (LC EC), glioblastoma, neuroendocrine prostate cancer (NEPC), high-grade gastroenteropancreatic cancer (GEP) and malignant melanoma.
In other particularly preferred embodiments the ADCs of the instant invention may be used to treat colorectal cancer. As used herein, the term "colorectal cancer" is meant to include the well- accepted medical definition that defines colorectal cancer as a medical condition characterized by cancer of cells of the intestinal tract below the small intestine (i.e. the large intestine (colon), including the cecum, ascending colon, transverse colon, descending colon, and sigmoid colon, and rectum). Additionally, as used herein, the term "colorectal cancer" is meant to further include medical conditions that are characterized by cancer of cells of the duodenum and small intestine (jejunum and ileum). The definition of colorectal cancer used herein is more expansive than the common medical definition but is provided as such since the cells of the duodenum and small intestine may also be amenable to the methods of the present invention. Moreover, the compounds of the invention may be used to treat stage I colorectal cancer, stage II colorectal cancer, stage III colorectal cancer or stage IV colorectal cancer.
In other selected embodiments the compounds and compositions of the instant invention may be used to treat gastric cancer.
With regard to pancreatic cancer the compositions disclosed herein may be used to treat acinar cell pancreatic carcinoma, duodenal pancreatic carcinoma, mucinous pancreatic adenocarcinoma, neuroendocrine pancreatic cancer, pancreatic adenocarcinoma, pancreatic adenocarcinoma exocrine type, ductal pancreatic adenocarcinoma and ampullary pancreatic adenocarcinoma.
More generally exemplary neoplastic conditions subject to treatment in accordance with the instant invention may be benign or malignant; solid tumors or hematologic malignancies; and may be selected from the group including, but not limited to: adrenal gland tumors, AIDS-associated cancers, alveolar soft part sarcoma, astrocytic tumors, autonomic ganglia tumors, bladder cancer (squamous cell carcinoma and transitional cell carcinoma), blastocoelic disorders, bone cancer (adamantinoma, aneurismal bone cysts, osteochondroma, osteosarcoma), brain and spinal cord cancers, metastatic brain tumors, breast cancer, carotid body tumors, cervical cancer, chondrosarcoma, chordoma, chromophobe renal cell carcinoma, clear cell carcinoma, colon cancer, colorectal cancer, cutaneous benign fibrous histiocytomas, desmoplastic small round cell tumors, ependymomas, epithelial disorders, Ewing's tumors, extraskeletal myxoid chondrosarcoma, fibrogenesis imperfecta ossium, fibrous dysplasia of the bone, gallbladder and bile duct cancers, gastric cancer, gastrointestinal, gestational trophoblastic disease, germ cell tumors, glandular disorders, head and neck cancers, hypothalamic, intestinal cancer, islet cell tumors, Kaposi's Sarcoma, kidney cancer (nephroblastoma, papillary renal cell carcinoma), leukemias, lipoma/benign lipomatous tumors, liposarcoma/malignant lipomatous tumors, liver cancer (hepatoblastoma, hepatocellular carcinoma), lymphomas, lung cancers (small cell carcinoma, adenocarcinoma, squamous cell carcinoma, large cell carcinoma etc.), macrophagal disorders, medulloblastoma, melanoma, meningiomas, medullary thyroid cancer, multiple endocrine neoplasia, multiple myeloma, myelodysplasia syndrome, neuroblastoma, neuroendocrine tumors, ovarian cancer, pancreatic cancers, papillary thyroid carcinomas, parathyroid tumors, pediatric cancers, peripheral nerve sheath tumors, phaeochromocytoma, pituitary tumors, prostate cancer, posterious unveal melanoma, rare hematologic disorders, renal metastatic cancer, rhabdoid tumor, rhabdomysarcoma, sarcomas, skin cancer, soft-tissue sarcomas, squamous cell cancer, stomach cancer, stromal disorders, synovial sarcoma, testicular cancer, thymic carcinoma, thymoma, thyroid metastatic cancer, and uterine cancers (carcinoma of the cervix, endometrial carcinoma, and leiomyoma). In certain embodiments the compounds and compositions of the instant invention will be used as a front line therapy and administered to subjects who have not previously been treated for the cancerous condition. In other embodiments the compounds and compositions of the present invention will be used to treat subjects that have previously been treated (with antibodies or ADCs of the present invention or with other anti-cancer agents) and have relapsed or determined to be refractory to the previous treatment. In selected embodiments the compounds and compositions of the instant invention may be used to treat subjects that have recurrent tumors.
In certain embodiments the compounds and compositions of the instant invention will be used as a front line therapy and administered to subjects who have not previously been treated for the cancerous condition. In other embodiments the compounds and compositions of the present invention will be used to treat subjects that have previously been treated (with antibodies or ADCs of the present invention or with other anti-cancer agents) and have relapsed or determined to be refractory to the previous treatment. In selected embodiments the compounds and compositions of the instant invention may be used to treat subjects that have recurrent tumors.
With regard to hematologic malignancies it will be further be appreciated that the compounds and methods of the present invention may be particularly effective in treating a variety of leukemias including acute myeloid leukemia (AML, cognizant of its various subtypes based on the FAB nomenclature (M0-M7), WHO classification, molecular marker/mutations, karyotype, morphology, and other characteristics), lineage acute lymphoblastic leukemia (ALL), chronic myeloid leukemia (CML), chronic lymphocytic leukemia (CLL), hairy cell leukemia (HCL), chronic myelomonocytic leukemia (CMML), juvenile myelomonocytic leukemia (JMML) and large granular lymphocytic leukemia (LGL) as well as B-cell lymphomas, including Hodgkin's lymphoma (classic Hodgkin's lymphoma and nodular lymphocyte-predominant Hodgkin lymphoma), Non-Hodgkin's lymphoma including diffuse large B-cell lymphoma (DLBCL), follicular lymphoma (FL), low grade/NHL follicular cell lymphoma (FCC), small lymphocytic lymphoma (SLL), mucosa-associated lymphatic tissue (MALT) lymphoma, mantle cell lymphoma (MCL),and Burkitt lymphoma (BL); intermediate grade/follicular NHL, intermediate grade diffuse NHL, high grade immunoblastic NHL, high grade lymphoblastic NHL, high grade small non-cleaved cell NHL, bulky disease NHL, Waldenstrom's Macroglobulinemia, lymphoplasmacytoid lymphoma (LPL), AIDS-related lymphomas, monocytic B cell lymphoma, angioimmunoblastic lymphoadenopathy, diffuse small cleaved cell, large cell immunoblastic lymphoblastoma, small, non-cleaved, Burkitt's and non- Burkitt's, follicular, predominantly large cell; follicular, predominantly small cleaved cell; and follicular, mixed small cleaved and large cell lymphomas. See, Gaidono et al., "Lymphomas", IN CANCER: PRINCIPLES & PRACTICE OF ONCOLOGY, Vol. 2: 213 1-2145 (DeVita et al., eds., 5.sup.th ed. 1997). It should be clear to those of skill in the art that these lymphomas will often have different names due to changing systems of classification, and that patients having lymphomas classified under different names may also benefit from the combined therapeutic regimens of the present invention.
In certain selected aspects the disclosed ADCs are effective at treating gastric cancers, including intestinal type, diffuse type, gastric cardia, gastric stromal type, carcinoid, and signet ring cell gastric adenocarcinomas. In one embodiment, the gastric cancer is refractory, relapsed or resistant to a radiation, 5-fluorouracil, platinum-based agents (e.g. carboplatin, cisplatin, oxaliplatin), or combinations thereof. In selected embodiments, the antibodies and ADCs can be administered to patients exhibiting non-metastatic or metastatic gastric cancers. In other embodiments the disclosed conjugated antibodies will be administered to refractory patients (i.e., those whose disease recurs during or shortly after completing a course of initial therapy); sensitive patients (i.e., those whose relapse is longer than 2-3 months after primary therapy); or patients exhibiting resistance to radiation, 5-fluorouracil, and/or a platinum based agent (e.g. carboplatin, cisplatin, oxaliplatin). In each case it will be appreciated that compatible ADCs may be used in combination with other anti-cancer agents depending on the selected dosing regimen and the clinical diagnosis.
As previously indicated in other selected aspects the disclosed ADCs are especially effective at treating colorectal cancers, including adenocarcinomas, mucinous adenocarcinomas, intestinal carcinoid, intestinal stromal, leiomyosarcoma, squamous cell carcinoma, neuroendocrine carcinoma, and signet ring cell carcinomas of the small intestine, colon, and rectum. In one embodiment, the colorectal cancer is refractory, relapsed or resistant to a radiation, 5-fluorouracil, platinum-based agents (e.g. carboplatin, cisplatin, oxaliplatin), VEGF-A-targeted agents, VEGF receptor-targeted agents, EGFR-targeted agents, and combinations thereof. In selected embodiments, the antibodies and ADCs can be administered to patients exhibiting non-metastatic or metastatic colorectal cancers.
In other embodiments the disclosed conjugated antibodies will be administered to refractory patients (i.e., those whose disease recurs during or shortly after completing a course of initial therapy); sensitive patients (i.e., those whose relapse is longer than 2-3 months after primary therapy); or patients exhibiting resistance to radiation, 5-fluorouracil, platinum-based agents (e.g. carboplatin, cisplatin, oxaliplatin), VEGF-A-targeted agents, VEGF receptor-targeted agents, and/or EGFR-targeted agents. In each case it will be appreciated that compatible ADCs may be used in combination with other anti-cancer agents depending on the selected dosing regimen and the clinical diagnosis.
In yet other selected aspects the disclosed ADCs are effective at treating lung cancers, including lung adenocarcinoma, small lung cancer (SCLC) and non-small cell lung cancer (NSCLC) (e.g., squamous cell non-small cell lung cancer or squamous cell small cell lung cancer). In one embodiment, the lung cancer is refractory, relapsed or resistant to a platinum based agent (e.g., carboplatin, cisplatin, oxaliplatin) and/or a taxane (e.g., docetaxel, paclitaxel, larotaxel or cabazitaxel). In another embodiment the subject to be treated is suffering from large cell neuroendocrine carcinoma (LC EC).
In certain preferred embodiments the KREMEN2 ADCs of the instant invention may be administered to frontline patients suffering from squamous cell lung cancer. In other embodiments the KREMEN2 ADCs of the instant invention may be administered to second line patients suffering from the same afflictions. In still other embodiments the KREMEN2 ADCs of the instant invention may be administered to third line patients having squamous cell lung cancer.
As indicated the disclosed antibodies and ADCs are effective at treating lung cancer, including the following subtypes: small cell lung cancer and non-small cell lung cancer (e.g. squamous cell lung cancer). In other embodiments the disclosed compositions may be used to treat lung adenocarcinoma. In selected embodiments the antibodies and ADCs can be administered to patients exhibiting limited stage disease or extensive stage disease. In other embodiments the disclosed conjugated antibodies will be administered to refractory patients (i.e., those whose disease recurs during or shortly after completing a course of initial therapy); sensitive patients (i.e., those whose relapse is longer than 2-3 months after primary therapy); or patients exhibiting resistance to a platinum based agent (e.g. carboplatin, cisplatin, oxaliplatin) and/or a taxane (e.g. docetaxel, paclitaxel, larotaxel or cabazitaxel). In certain preferred embodiments the KREMEN2 ADCs of the instant invention may be administered to frontline patients. In other embodiments the KREMEN2 ADCs of the instant invention may be administered to second line patients. In still other embodiments the KREMEN2 ADCs of the instant invention may be administered to third line patients. In each case it will be appreciated that compatible ADCs may be used in combination with other anti-cancer agents depending the selected dosing regimen and the clinical diagnosis.
In certain aspects the compounds and compositions of the instant invention may be used to treat breast cancer. It will be appreciated that breast cancer is a heterogeneous disease with several biologic subtypes identified. In this regard breast cancer is now recognized as comprising at least four distinct neoplastic subtypes based on the expression of estrogen receptor (ER), progesterone receptor (PR), and erbB2/Her2. These subtypes include: basal-like/triple negative breast cancer, Her2 -positive breast cancer, luminal A breast cancer and luminal B breast cancer. Luminal A is the most common breast cancer subtype (40% of all invasive breast cancer) and is characterized by ER+ and/or PR+/Her2- status, low-grade tumors and good prognosis. Luminal B subtype accounts for roughly 25% of all invasive breast cancer and is distinguished by ER+ and/or PR+/Her2+ status with poor outcomes. Breast cancer subtypes (20% of all invasive breast cancer) with negative ER, PR and Her2 status are typically called triple negative breast cancer or basal-like breast cancer. The Her2-enriched subtype (Her2+/ER-/PR-) is least common, with 15% of all invasive breast cancer. While the antibodies and ADCs of the instant invention may be used to treat all different types of KREMEN2 positive breast cancers, it may be particularly effective treating basal-like breast cancer and luminal-B breast cancer, where therapeutic resistance is common and, as shown in the Examples below, where molecular profiling has identified KREMEN2 as a promising new therapeutic target.
Multiple gene expression studies have reproduced luminal-A and luminal-B subtypes. Both subtypes have expression patterns reminiscent of the luminal epithelial component of the breast, including expression of luminal cytokeratins 8/18, ER and genes associated with ER activation such as CC D1 (cyclin Dl). The major molecular distinction between the two luminal subtypes is that, in general, luminal B has lower expression of ER-related genes and higher expression of proliferative genes. A review of several gene expression studies noted that approximately 20% of luminal-B breast cancers were HER2-positive by immunohistochemistry. Approximately 30% of HER2-positive tumors defined by immunohistochemistry are assigned to the luminal-B subtype. In many subsequent studies, luminal-B breast cancer has been defined as ER-positive breast cancer with increased proliferation. In gene expression studies, proliferation genes such as CCNBl, MKI67 and MYBL2 are more highly expressed in luminal-B compared with luminal-A subtypes, correlating with a higher proportion of histological grade III also observed in luminal-B cancers. Proliferation has been consistently identified as the most important feature of several prognostic multigene signatures, including the intrinsic molecular classification. In ER- positive/HER2-negative tumors, proliferation is the strongest predictor of early relapse risk that differentiates high-risk luminal-B tumors from low-risk luminal-A tumors.
Overall survival in untreated luminal-B breast cancer is similar to the basal-like and HER2- positive subgroups, which are widely recognized as high risk. In a study using a 50-gene classifier to assign intrinsic subtypes to 761 untreated breast cancer patients, with correlation of subtype with outcome; a multivariate analysis of untreated early breast cancer, using the luminal-A subtype as a reference, luminal-B breast cancers were demonstrated to have a hazard ratio of 2.43 (P < 0.0001) for relapse-free survival (RFS), similar to hazard ratios for erbB2/HER2 amplified (2.53, P = 0.00012) tumors. Triple negative/basal-like breast cancer had intermediate survival times, with deaths occurring earlier than luminal A breast cancer. Survival declined precipitously during the first 3 to 4 years of follow-up for both Her2-enriched and luminal B subtypes, followed by a slowing in the decline over subsequent years of follow-up. The triple negative subtype showed a similar early decline over the first 2 to 2.5 years with a more gradual decline to about 13 years of follow up. Moreover, luminal breast cancers appear to have a predilection for metastasis to lung, bone and pleura. Several studies suggest luminal-B breast cancer is relatively insensitive to endocrine therapy compared with luminal-A breast cancer, and to chemotherapy compared with HER2-enriched and basal-like breast cancers.
In contrast to the current clinical situation, the ADCs and antibodies of the instant invention have been shown to exhibit anti-tumor activity as shown in the Examples below. More specifically the disclosed anti-KREMEN2 ADCs are shown to effectively and specifically associate with tumorigenic cells in luminal-B breast cancer. This targeting of the selected tumor cells is indicative of agents with substantial therapeutic potential. IX. Articles of Manufacture
The invention includes pharmaceutical packs and kits comprising one or more containers or receptacles, wherein a container can comprise one or more doses of an antibody or ADC of the invention. Such kits or packs may be diagnostic or therapeutic in nature. In certain embodiments, the pack or kit contains a unit dosage, meaning a predetermined amount of a composition comprising, for example, an antibody or ADC of the invention, with or without one or more additional agents and optionally, one or more anti-cancer agents. In certain other embodiments, the pack or kit contains a detectable amount of an anti-KREMEN2 antibody or ADC, with or without an associated reporter molecule and optionally one or more additional agents for the detection, quantitation and/or visualization of cancerous cells.
In any event kits of the invention will generally comprise an antibody or ADC of the invention in a suitable container or receptacle a pharmaceutically acceptable formulation and, optionally, one or more anti-cancer agents in the same or different containers. The kits may also contain other pharmaceutically acceptable formulations or devices, either for diagnosis or combination therapy. Examples of diagnostic devices or instruments include those that can be used to detect, monitor, quantify or profile cells or markers associated with proliferative disorders (for a full list of such markers, see above). In some embodiments the devices may be used to detect, monitor and/or quantify circulating tumor cells either in vivo or in vitro (see, for example, WO 2012/0128801). In still other embodiments the circulating tumor cells may comprise tumorigenic cells. The kits contemplated by the invention can also contain appropriate reagents to combine the antibody or ADC of the invention with an anti-cancer agent or diagnostic agent (e.g., see U. S.P.N. 7,422,739).
When the components of the kit are provided in one or more liquid solutions, the liquid solution can be non-aqueous, though typically an aqueous solution is preferred, with a sterile aqueous solution being particularly preferred. The formulation in the kit can also be provided as dried powder(s) or in lyophilized form that can be reconstituted upon addition of an appropriate liquid. The liquid used for reconstitution can be contained in a separate container. Such liquids can comprise sterile, pharmaceutically acceptable buffer(s) or other diluent(s) such as bacteriostatic water for injection, phosphate-buffered saline, Ringer's solution or dextrose solution. Where the kit comprises the antibody or ADC of the invention in combination with additional therapeutics or agents, the solution may be pre-mixed, either in a molar equivalent combination, or with one component in excess of the other. Alternatively, the antibody or ADC of the invention and any optional anti-cancer agent or other agent (e.g., steroids) can be maintained separately within distinct containers prior to administration to a patient.
In certain preferred embodiments the aforementioned kits comprising compositions of the invention will comprise a label, marker, package insert, bar code and/or reader indicating that the kit contents may be used for the treatment, prevention and/or diagnosis of cancer. In other preferred embodiments the kit may comprise a label, marker, package insert, bar code and/or reader indicating that the kit contents may be administered in accordance with a certain dosage or dosing regimen to treat a subject suffering from cancer. In a particularly preferred aspect the label, marker, package insert, bar code and/or reader indicates that the kit contents may be used for the treatment, prevention and/or diagnosis of lung cancer or provide dosages or a dosing regimen for treatment of the same. In other particularly preferred aspects the label, marker, package insert, bar code and/or reader indicates that the kit contents may be used for the treatment, prevention and/or diagnosis of breast cancer (e.g., luminal B breast cancer) or a dosing regimen for treatment of the same.
Suitable containers or receptacles include, for example, bottles, vials, syringes, infusion bags
(i.v. bags), etc. The containers can be formed from a variety of materials such as glass or pharmaceutically compatible plastics. In certain embodiments the receptacle(s) can comprise a sterile access port. For example, the container may be an intravenous solution bag or a vial having a stopper that can be pierced by a hypodermic injection needle.
In some embodiments the kit can contain a means by which to administer the antibody and any optional components to a patient, e.g., one or more needles or syringes (pre-filled or empty), an eye dropper, pipette, or other such like apparatus, from which the formulation may be injected or introduced into the subject or applied to a diseased area of the body. The kits of the invention will also typically include a means for containing the vials, or such like, and other components in close confinement for commercial sale, such as, e.g., blow-molded plastic containers into which the desired vials and other apparatus are placed and retained.
X. Miscellaneous
Unless otherwise defined herein, scientific and technical terms used in connection with the invention shall have the meanings that are commonly understood by those of ordinary skill in the art. Further, unless otherwise required by context, singular terms shall include pluralities and plural terms shall include the singular. In addition, ranges provided in the specification and appended claims include both end points and all points between the end points. Therefore, a range of 2.0 to 3.0 includes 2.0, 3.0, and all points between 2.0 and 3.0.
Generally, techniques of cell and tissue culture, molecular biology, immunology, microbiology, genetics and chemistry described herein are those well-known and commonly used in the art. The nomenclature used herein, in association with such techniques, is also commonly used in the art. The methods and techniques of the invention are generally performed according to conventional methods well known in the art and as described in various references that are cited throughout the present specification unless otherwise indicated.
XI. References
The complete disclosure of all patents, patent applications, and publications, and electronically available material (including, for example, nucleotide sequence submissions in, e.g., GenBank and RefSeq, and amino acid sequence submissions in, e.g., SwissProt, PIR, PRF, PBD, and translations from annotated coding regions in GenBank and RefSeq) cited herein are incorporated by reference, regardless of whether the phrase "incorporated by reference" is or is not used in relation to the particular reference. The foregoing detailed description and the examples that follow have been given for clarity of understanding only. No unnecessary limitations are to be understood therefrom. The invention is not limited to the exact details shown and described. Variations obvious to one skilled in the art are included in the invention defined by the claims. Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.
Certain papers that may be of interest are listed immediately below:
• Davidson G, Mao B, del Barco Barrantes I, Niehrs C. Kremen proteins interact with Dickkopfl to regulate anteroposterior CNS patterning. Development. 2002 Dec; 129(24):5587-96. Erratum in: Development. 2003 Ian; 130(2):425.PMID: 12421700
• Dun X, iang H, Zou I, Shi I, Zhou L, Zhu R, Hou I., Differential expression of DKK-1 binding receptors on stromal cells and myeloma cells results in their distinct response to secreted DKK-1 in myeloma. Mol Cancer. 2010 Sep 16;9:247. doi: 10.1186/1476-4598- 9-247. PMID: 20846389 • Li Y, Lu W, King TD, Liu CC, Bijur GN, Bu G., Dkkl stabilizes Wnt co-receptor LRP6: implication for Wnt ligand-induced LRP6 down -regulation. PLoS One. 2010 Jun 8;5(6):el l014. doi: 10.1371/journal.pone.0011014. PMID: 20543981
• Liu WM, Laux H, Henry JY, Bolton TB, Dalgleish AG, Galustian C. A microarray study of altered gene expression in colorectal cancer cells after treatment with immunomodulatory drugs: differences in action in vivo and in vitro. Mol Biol Rep. 2010 Apr;37(4): 1801-14. doi: 10.1007/sl 1033-009-9614-3. Epub 2009 Jul 14. PMID: 19597962
• Maehata T, Taniguchi H, Yamamoto H, Nosho K, Adachi Y, Miyamoto N, Miyamoto C, Akutsu N, Yamaoka S, Itoh F., Transcriptional silencing of Dickkopf gene family by CpG island hypermethylation in human gastrointestinal cancer. World J Gastroenterol. 2008 May 7; 14(17):2702-14. PMID: 1846165
• Mao B, Wu W, Davidson G, Marhold J, Li M, Mechler BM, Delius H, Hoppe D, Stannek P, Walter C, Glinka A, Niehrs C. Kremen proteins are Dickkopf receptors that regulate Wnt/beta-catenin signalling. Nature. 2002 Jun 6;417(6889):664-7. Epub 2002 May 26. PMID: 120506705
• Mao B, Niehrs C. Kremen2 modulates Dickkopf2 activity during Wnt/LRP6 signaling.
Gene. 2003 Jan 2;302(l-2): 179-83. PMID: 12527209
• Nagano H, Tomimaru Y, Eguchi H, Hama N, Wada H, Kawamoto K, Kobayashi S, Mori M, Doki Y., MicroRNA-29a induces resistance to gemcitabine through the Wnt/β- catenin signaling pathway in pancreatic cancer cells. Int J Oncol. 2013 Oct;43(4): 1066- 72. doi: 10.3892/ijo.2013.2078. Epub 2013 Jul 24. PMID: 23900458
Examples
The invention, generally described above, will be understood more readily by reference to the following examples, which are provided by way of illustration and are not intended to be limiting of the instant invention. The examples are not intended to represent that the experiments below are all or the only experiments performed. Unless indicated otherwise, parts are parts by weight, molecular weight is weight average molecular weight, temperature is in degrees Centigrade, and pressure is at or near atmospheric. Sequence Listing Summary
Table 3 provides a summary of amino acid and nucleic acid sequences included herein.
Table 3
Figure imgf000128_0001
112-113 hSC78.56 VL DNA and protein
114-115 hSC78.56 VH DNA and protein
116-117 hSC78.59 VL DNA and protein
118-119 hSC78.59 VH DNA and protein
120-129 reserved
130 hSC78.9 full length light chain protein
131 hSC78.9 full length heavy chain protein
132 reserved
133 hSC78.9ssl full length heavy chain protein
134 reserved
135 hSC78.9sslMJ full length heavy chain protein
136 hSC78.43 full length light chain protein
137 hSC78.43 full length heavy chain protein
138 reserved
139 hSC78.43ssl full length heavy chain protein
140 reserved
141 hSC78.43sslMJ full length heavy chain protein
142 hSC78.43 full length light chain protein (VK08)
143 reserved
144 hSC78.56 full length light chain protein
145 hSC78.56 full length heavy chain protein
146 reserved
147 hSC78.56ssl full length heavy chain protein
148 reserved
149 hSC78.56sslMJ full length heavy chain protein
150 hSC78.59 full length light chain protein
151 hSC78.59 full length heavy chain protein
152 reserved
153 hSC78.59ssl full length heavy chain protein Tumor Cell Line Summary
PDX tumor cell types are denoted by an abbreviation followed by a number, which indicates the particular tumor cell line. The passage number of the tested sample is indicated by p0-p# appended to the sample designation where pO is indicative of an unpassaged sample obtained directly from a patient tumor and p# is indicative of the number of times the tumor has been passaged through a mouse prior to testing. As used herein, the abbreviations of the tumor types and subtypes are shown in Table 4 as follows:
Table 4
Figure imgf000130_0001
Figure imgf000131_0001
medullary thyroid carcinoma MTC Example 1
Identification of KREMEN2 Expression
Using Whole Transcriptome Sequencing
To characterize the cellular heterogeneity of solid tumors as they exist in cancer patients and identify clinically relevant therapeutic targets, a large PDX tumor bank was developed and maintained using art recognized techniques. The PDX tumor bank, comprising a large number of discrete tumor cell lines, was propagated in immunocompromised mice through multiple passages of tumor cells originally obtained from cancer patients afflicted by a variety of solid tumor malignancies. Low passage PDX tumors are representative of tumors in their native environments, providing clinically relevant insight into underlying mechanisms driving tumor growth and resistance to current therapies.
As discussed herein tumor cells may be divided broadly into two types of cell subpopulations: non-tumori genie cells (NTG) and tumor initiating cells (TICs). TICs have the ability to form tumors when implanted into immunocompromised mice. Cancer stem cells (CSCs) are a subset of TICs that are able to self-replicate indefinitely while maintaining the capacity for multilineage differentiation. NTGs, while sometimes able to grow in vivo, will not form tumors that recapitulate the heterogeneity of the original tumor when implanted.
In order to perform whole transcriptome analysis, PDX tumors were resected from mice after reaching 800 - 2,000 mm3 or for AML after the leukemia was established in the bone marrow (<5% of bone marrow cellularity of human origin). Resected PDX tumors were dissociated into single cell suspensions using art-recognized enzymatic digestion techniques (see, for example, U. S.P.N. 2007/0292414). Dissociated bulk tumor cells were incubated with 4',6-diamidino-2-phenylindole (DAPI) to detect dead cells, anti-mouse CD45 and H-2Kd antibodies to identify mouse cells and anti-human EPCAM antibody to identify human cells. In addition, the tumor cells were incubated with fluorescently conjugated anti-human CD46 and/or CD324 antibodies to identify CD324+ CSCs or CD324" NTG cells and were then sorted using a FACS Aria cell sorter (BD Biosciences) (see U.S.P. Ns 2013/0260385, 2013/0061340 and 2013/0061342). Anti-human CD49f and EPCAM antibodies were also used to identify four different subpopulations as described by Lim et. al., 2009 (PMID: 19648928) within the normal human breast, including differentiated luminal, progenitor and mammary stem/basal epithelial cells, as well as stromal cells. Similarly, a normal lung epithelial population was sorted using anti-human EPCAM.
RNA was extracted from tumor cells by lysing the cells in RLTplus RNA lysis buffer (Qiagen) supplemented with 1% 2-mercaptoethanol, freezing the lysates at -80 °C and then thawing the lysates for RNA extraction using an RNeasy isolation kit (Qiagen). RNA was quantified using a Nanodrop spectrophotometer (Thermo Scientific) and/or a Bioanalyzer 2100 (Agilent Technologies). Normal tissue RNA was purchased from various sources (Life Technology, Agilent, ScienCell, BioChain, and Clontech). The resulting total RNA preparations were assessed by genetic sequencing and gene expression analyses. More particularly whole transcriptome sequencing of high quality RNA was performed using Illumina HiSeq 2000 or 2500 next generation sequencing system (Illumina, Inc.).
Illumina whole transcriptome analysis was performed with cDNA that was generated using 5 ng total RNA extracted from either bulk or sorted subpopulations that were isolated as described above. The library was created using the TruSeq RNA Sample Preparation Kit v2 (Illumina, Inc.). The resulting cDNA library was fragmented and barcoded. Sequencing data from the Illumina platform is nominally represented as a fragment expression value using the metric FPKM (fragment per kilobase per million) mapped to exon regions of genes, enabling basic gene expression analysis to be normalized and enumerated as FPKM transcript.
As shown in FIG. 2 KREMEN2 mRNA expression is upregulated CSC populations from luminal B PDX tumors (black bars), and in CSC populations from non-small cell lung cancer tumors (grey bars) relative to matched NTG populations (white bars) from these same tumors. KREMEN2 expression was generally higher in tumor samples than KREMEN2 expression in both normal tissues and various sorted normal breast and normal lung epithelial populations.
The identification of elevated KREMEN2 mRNA expression in BR tumor, non-small cell lung tumor and CSC populations indicated that KREMEN2 has potential as a diagnostic and immunotherapeutic target. Furthermore, increased expression of KREMEN2 in sorted populations indicates that KREMEN2 is a good marker of tumorigenic cells.
Example 2
Expression of KREMEN2 mRNA in Tumors using qRT-PCR
To confirm KREMEN2 RNA expression in tumor cells, qRT-PCR was performed on various PDX cell lines using the Fluidigm BioMark™ HD System according to industry standard protocols. RNA was extracted from bulk PDX tumor cells or sorted CSC and NTG subpopulations as described in Example 1. Following extraction 1.0 ng of RNA was converted to cDNA using the High Capacity cDNA Archive kit (Life Technologies) according to the manufacturer's instructions. cDNA material, pre-amplified using a KREMEN2 probe specific Taqman assay, was then used for subsequent qRT-PCR experiments.
KREMEN2 expression in normal tissues (NormTox or Norm) was compared to expression in various molecular subtypes of breast (BR) tumors - unclassified BR, BR-Basal Like, BR-CLDN low, BR-HER2 positive, BR-LumA, and BR-LumB, as well as NSCLC (LU-Ad and LU-SCC), endometrial (EM), ovarian (OV-serous/papillary serous and MMMT) and MEL (FIG. 3; each dot represents the average relative expression of each individual tissue or PDX cell line, with the small horizontal line representing the geometric mean). "NormTox" represents samples of various normal tissues as follows: adrenal, colon, dorsal root ganglion, endothelial cells (artery, vein), esophagus, heart, kidney, liver, lung, pancreas, skeletal muscle, skin (fibroblasts, keratinocytes), small intestine, spleen, stomach, and trachea. Another set of normal tissues designated "Norm" represents the following samples of normal tissue with a presumed lower risk for toxicity in relation to ADC-type drugs: peripheral blood mononuclear cells and various sorted subpopulations (B cells, monocytes, NK cells, neutrophils, T cells), adipose, bladder, brain, breast, cervix, fetal liver, melanocytes, normal bone marrow and various sorted subpopulations, ovary, prostate, testes, thymus, thyroid and uterus.
FIG. 3 shows that on average KREMEN2 expression was elevated in subsets of BR PDX of varying subtypes, with the majority of LumB samples showing elevated expression. Similarly, the majority of OV tumors were strongly positive for KREMEN2 expression. Additionally, subsets of EM, LU-Ad, LU-SCC, and MEL PDX were elevated in KREMEN2 expression. Most normal and norm tox tissues expressed low levels of KREMEN2, with exceptions of strong (>104) relative expression in esophagus, skin, pancreas and trachea in this assay. Normal tissues with significant signals were thymus and normal bone marrow, which in turn were likely due to detected RNA expression in lymphocytes. These data support the earlier finding of elevated expression of KREMEN2 in LumB and in addition highlights overexpression in significant subsets of PDX tumors of various types compared to most normal tissues. Example 3
Determination of Expression of
KREMEN2 mRNA in Tumors using Microarray Analysis
Microarray experiments to determine the expression levels of KREMEN2 in various tumor cell lines were conducted and data was analyzed as follows. 1 -2 μg of whole tumor total RNA was extracted, substantially as described in Example 1, from PDX lines. Additionally, RNA was extracted from samples of normal tissues (e.g., breast, colon, heart, kidney, liver, lung, ovary, pancreas, skin, spleen, PBMC, and stomach) using substantially the same procedure. The RNA samples were analyzed using the Agilent SurePrint GE Human 8x60 v2 microarray platform, which contains 50,599 biological probes designed against 27,958 genes and 7,419 IncRNAs in the human genome. Standard industry practices were used to normalize and transform the intensity values to quantify gene expression for each sample. The normalized intensity of KREMEN2 expression in each sample is plotted in FIG. 4 and the geometric mean derived for each tumor type is indicated by the horizontal bar.
A closer review of FIG. 4 shows that KREMEN2 expression is on average upregulated in BR, EN, LU-Ad, LU-SCC, OV and MEL relative to that observed for normal tissues, although within each PDX type there typically is a wide spread in KREMEN2 expression levels. Of particular note is the elevated KREMEN2 in the BR-LumB subtype as well as OV. Corresponding to earlier results the normal tissue with the highest expression of KREMEN2 was skin, with most other normal tissues expressing at least 30-fold less KREMEN2. The observation of elevated KREMEN2 expression in the aforementioned tumor types confirms the results of the previous Examples.
Example 4
KREMEN2 Expression in Tumors using The Cancer Genome Atlas
Overexpression of KREMEN2 mRNA in various tumors was confirmed using a large, publicly available dataset of primary tumors and normal samples known as The Cancer Genome Atlas (TCGA). KREMEN2 expression data from the IlluminaHiSeq_RNASeqV2 platform and the IlluminaHiSeq RNASeq platform was downloaded from the TCGA Data Portal (h p / icun-- d ata . nci . m h . gov/ tc ga/'tc gaD o n I oad . j sp ) and parsed to aggregate the reads from the individual exons of each gene to generate a single value read per kilobase of exon per million mapped reads (RPKM). KREMEN2 expression in FIG. 5 is elevated in primary BL, BR, ES, HN, LY, LU, OV, OR, SK, and UT tumors, relative to normal tissues found in the TCGA database. These data imply there is a good therapeutic index above normal tissues and therefore anti-KREMEN2 antibodies and ADCs may be useful therapeutics for the treatment of these tumors. Example 5
Cloning and Expression of Recombinant KREMEN2 Proteins
DNA fragments encoding human KREMEN2 proteins.
To generate fusion proteins required in the present invention pertaining to the human KREMEN2 (hKREMEN2) protein (GenBank accession NP_757384, SEQ ID NO: 1), a synthetic DNA fragment encoding the mature hKREMEN2 protein ECD (residues G26-A364) was ordered from GeneArt (Therm oFisher Scientific) using NCBI accession NM_172229 as reference. The synthetic gene fragment was codon optimized for expression in mammalian lines. This DNA fragment was used for all subsequent engineering of constructs expressing fusion or tagged proteins containing the hKREMEN2 ECD, or fragments thereof. In particular, constructs were generated in which this DNA fragment was fused in-frame to DNA encoding either a 9x-Histidine tag (hKREMEN2-ECD-His), or a human IgG2 Fc protein (hKREMEN2-ECD-Fc), using standard molecular techniques. To produce immunogens that may be used to generate immunoreactive antibodies to the ECD of the hKREMEN2 protein, the chimeric fusion genes described above were subcloned into a CMV driven expression vector in frame and downstream of an immunoglobulin kappa (IgK) signal peptide sequence using standard molecular techniques. The CMV-driven expression vector permits high level transient expression in HEK293T and/or CHO-S cells. Suspension or adherent cultures of HEK293T cells, or suspension CHO-S cells were transfected with either hKREMEN2-ECD-His or hKREMEN2-ECD-Fc, using polyethylenimine polymer as the transfecting reagent. Three to five days after transfection, the recombinant proteins were purified from clarified cell-supernatants using either Nickel-EDTA (Qiagen) or MabSelect SuRe™ Protein A (GE Healthcare Life Sciences) columns as appropriate to the tag.
Full-length hKREMENZ DNA construct
To generate cell lines overexpressing full length hKREMEN2 protein, lentiviral vectors containing an open reading frame encoding the mature hKREMENZ protein were constructed as follows. First, standard molecular cloning techniques were used to introduce nucleotide sequences encoding an IgK signal peptide followed by a poly-Asp Lys epitope tag upstream of the multiple cloning site of pCDH-CMV-MCS-EFl-copGFP (System Biosciences), creating the vector pLMEGPA. This dual promoter construct employs a CMV promoter to drive expression of the epitope-tagged cell surface proteins independent of a downstream EF1 promoter that drives expression of the copGFP T2A Puro reporter and selectable marker. The T2A sequence in pLMEGPA promotes ribosomal skipping of a peptide bond condensation, resulting in expression of two independent proteins: high level expression of the reporter copGFP encoded upstream of the T2A peptide, with co-expression of the Puro selectable marker protein encoded downstream of the T2A peptide allowing selection in the presence of puromycin.
A synthetic DNA fragment encoding the mature hKREMEN2 protein (residues G26-L462) was ordered from GeneArt (ThermoFisher Scientific) using NCBI accession M_172229 as reference. The synthetic gene was codon optimized for expression in mammalian lines, and was flanked with restriction endonuclease sites to enable in-frame subcloning downstream of the IgK signal peptide-epitope tag in pLMEGPA. This yielded the pLMEGPA-hKREMEN2-NFlag lentiviral vector, which encodes a fusion protein with the epitope tag appended to the N-terminus of the mature hKREMEN2 protein.
DNA fragments encoding rat and cynomolgus KREMEN2 proteins.
To generate all molecular and cellular materials required in the present invention pertaining to the rat KREMEN2 protein (rKREMEN2), GenBank accession NM_001105767 was used as reference to design synthetic cDNA fragments encoding either the mature ECD (NP_001099237; amino acids G25-R373) or mature full length (NP OO 1099237; amino acids G25-L468) rKREMEN2 proteins. To generate all molecular and cellular materials required in the present invention pertaining to the cynomolgus monkey (Macaca fascicularis) KREMEN2 protein (cKREMEN2), GenBank accession XM_005591011 was used as a reference to design synthetic cDNA fragments encoding either the mature ECD (XP 005591068; amino acids G26-A364) or mature full length (XP_005591068; amino acids G26-L462) cKREMEN2 proteins. All synthetic DNA fragments were codon optimized for expression in mammalian lines.
Chimeric fusion genes for either the rat or cynomolgus KREMEN2 ECD and a 9-Histidine tag or human IgG2 Fc tag were constructed by subcloning the DNA fragment encoding the respective mature ECD fragment into a CMV driven expression vector in-frame and downstream of an IgK signal peptide sequence and upstream of either a 9-Histidine tag or a human IgG2 Fc cDNA, using standard molecular techniques. These CMV-driven expression vectors were used to transfect suspension or adherent cultures of HEK-293T cells, or suspension CHO-S cells to produce recombinant protein, as described previously for the analogous hKREMEN2 fusion proteins, above.
To generate cell lines overexpressing full length rKREMEN2 or cKREMEN2 protein, lentiviral vectors containing an open reading frame encoding the respective mature rKREMEN2 or CKREMEN2 proteins were constructed using standard molecular techniques, to subclone either the mature full length rKREMEN2 or cKREMEN2 open reading frame downstream of the IgK signal peptide-epitope tag in pLMEGPA, yielding pLMEGPA-rKREMEN2- Flag or pLMEGPA- cKREMEN2- Flag, respectively.
Cell line engineering
Engineered cell lines overexpressing the hKREMEN2, rKREMEN2 or cKREMEN2 proteins were constructed using the respective pLMEGPA vectors, described above, to transduce HEK-293T cell lines using standard lentiviral transduction techniques well known to those skilled in the art. KREMEN2 -positive cells in each instance were selected using fluorescent activated cell sorting (FACS) of puromycin resistant, high-expressing FIEK-293T subclones (e.g., cells that were resistant to puromycin and strongly positive for both GFP and the epitope tag).
Example 6
Generation of Anti-KREMEN2 Antibodies
Anti-KREMEN2 mouse antibodies were produced by inoculating one BALB/c mouse, one CD-I mouse, and one FVB mouse with 10 μg hKREMEN2 protein, emulsified with an equal volume of TiterMax® Gold Adjuvant (Sigma Aldrich #H4 T2684-1ML). Following the initial inoculation, the mice were injected at weekly intervals, 9 times with 10 μg hKREMEN2 protein emulsified with an equal volume of Imject® Alum (ThermoScientific) plus "CpG" (InvivoGen). The final injection prior to the fusion was with 10 μg hKREMEN2 in PBS.
Mice were sacrificed, and draining lymph nodes (popliteal, inguinal, and medial iliac) were dissected and used as a source for antibody producing cells. A single-cell suspension of B cells was produced and (3 xlO8 cells) were fused with non-secreting SP2/0-Agl4 myeloma cells (ATCC # CRL-1581) at a ratio of 1 : 1 by electro cell fusion using a model BTX Hybrimmune System (BTX Harvard Apparatus). Cells were re-suspended in hybridoma selection medium consisting of DMEM medium supplemented with azaserine, 15% fetal clone I serum (Thermo #SH30080-03), 10% BM condimed (Roche # 10663573001), 1 mM nonessential amino acids (Corning #25-025-0) 1 mM HEPES Corning #25-060-0), 100 IU penicillin-streptomycin (Corning #30-002-0), 100 IU L- glutamine (Corning #25-005-0) and were cultured in three T225 flasks containing 100 mL selection medium. The flasks were placed in a humidified 37°C incubator containing 7% C02 and 95% air for 6 days.
On days 6 and 7 after the fusion, the hybridoma cells were sorted from the flask and plated at one cell per well (using a BD FACSAria cell sorter) in 90 of supplemented hybridoma selection medium (as described above) into 12 Falcon 384-well plates. Remaining unused hybridoma library cells were frozen in liquid nitrogen for future library testing and screening.
Sorted clonal hybridomas were cultured for 8 days and the supernatants were collected, re- arrayed onto 384-well plates, and screened for antibodies specific to hKREMEN2 expressed on the surface of transduced HEK/293T cells (ATCC CRL-11268) using flow cytometry, as follows. 293T cells stably transduced with hKREMEN2 in each well were incubated for 30 minutes with 25 \L hybridoma supernatant and then washed with PBS/2% FCS. Cells were incubated for 15 minutes with 25 \L per sample Alexa Fluor® 647 AffiniPure F(ab')2 Fragment Goat Anti-Mouse IgG, Fey Fragment Specific secondary antibody diluted in PBS/2%FCS, washed twice and re-suspended with PBS/2%FCS. The cells were then analyzed by flow cytometry using a BD FACSCanto II machine.
An ELISA assay was also used to screen the hybridoma supernatants for antibodies that bound to rKREMEN2. The ELISA was performed as follows. Plates were coated with purified rKREMEN2-His at 0.5 μg/mL in PBS buffer and incubated at 4 °C overnight. Plates were then washed with PBST and blocked with PBS with 5% FBS for 30 min. at 37 °C. The blocking solution was removed and 15 μΐ PBST was added to the wells. 25 μΐ of hybridoma supernatant was added and incubated for 1 hour at room temperature. After washing with PBST, 30 μΙ,ΛνεΙΙ HRP- labeled goat anti-mouse IgG diluted 1 : 10,000 in PBSA was added for 30 min. at room temperature. The plates were washed and developed by the addition of 25 μίΛνεΙΙ of the TMB substrate solution (Thermo Scientific) for approximately 5 min. at room temperature. An equal volume of 0.2 M H2S04 was added to stop substrate development. The samples were then analyzed by spectrophotometer at OD 450. Samples that had an OD 450 greater than 3 times the background were considered to be cross-reactive.
Using both assays a number of hKREMEN2 immunospecific antibodies were identified. In some cases the identified antibodies cross reacted with rKREMEN2. Example 7
Sequencing of KREMEN2 Antibodies
The anti-KREMEN2 mouse antibodies that were generated in Example 6 were sequenced as described below. Total RNA was purified from selected hybridoma cells using the RNeasy Miniprep Kit (Qiagen) according to the manufacturer's instructions. Between 104 and 105 cells were used per sample. Isolated RNA samples were stored at minus 80 °C until used.
The variable region of the Ig heavy chain of each hybridoma was amplified using two 5' primer mixes comprising eighty-six mouse specific leader sequence primers designed to target the complete mouse VH repertoire in combination with a 3' mouse Cy primer specific for all mouse Ig isotypes. Similarly, two primer mixes containing sixty-four 5' VK leader sequences designed to amplify each of the VK mouse families was used in combination with a single reverse primer specific to the mouse kappa constant region in order to amplify and sequence the kappa light chain. The VH and VL transcripts were amplified from 100 ng total RNA using the Qiagen One Step RT- PCR kit as follows. A total of four RT-PCR reactions were run for each hybridoma, two for the VK light chain and two for the VH heavy chain. PCR reaction mixtures included 1.5 μΐ, of RNA, 0.4 μΙ_, of 100 μΜ of either heavy chain or kappa light chain primers (custom synthesized by Integrated DNA Technologies), 5 of 5x RT-PCR buffer, 1 dNTPs, and 0.6 μί of enzyme mix containing reverse transcriptase and DNA polymerase. The thermal cycler program was RT step 50 °C for 60 min., 95 °C for 15 min. followed by 35 cycles of (94.5 °C for 30 seconds, 57 °C for 30 seconds, 72 °C for 1 min.). There was then a final incubation at 72 °C for 10 min.
The extracted PCR products were sequenced using the same specific variable region primers as described above for the amplification of the variable regions. PCR products were sent to an external sequencing vendor (MCLAB) for PCR purification and sequencing services. Nucleotide sequences were analyzed using the EVIGT sequence analysis tool (http://www.imgt.org/IMGTmedical/sequence_analysis.htmn to identify germline V, D and J gene members with the highest sequence homology. The derived sequences were compared to known germline DNA sequences of the Ig V- and J-regions by alignment of VH and VL genes to the mouse germline database using a proprietary antibody sequence database.
FIG. 6A depicts the contiguous amino acid sequences of novel murine light chain variable regions from anti-KREMEN2 antibodies while FIG. 6B depicts the contiguous amino acid sequences of novel murine heavy chain variable regions from the same anti-KREMEN2 antibodies. Taken together, murine light and heavy chain variable region amino acid sequences are provided in SEQ ID NOS: 21 - 81 odd numbers. In addition, FIG. 6C provides the nucleic acid sequences (SEQ ID NOS: 20-80, even numbers) encoding the amino acid sequences set forth in FIGS. 6A and 6B.
More particularly, FIGS. 6A and 6B provide the annotated sequences of murine anti- KREMEN2 antibodies comprising: (1) a light chain variable region (VL) of SEQ ID NO: 21 and a heavy chain variable region (VH) of SEQ ID NO: 23; or (2) a VL of SEQ ID NO: 25 and a VH of SEQ ID NO: 27; or (3) a VL of SEQ ID NO: 29 and a VH of SEQ ID NO: 31; or (4) a VL of SEQ ID NO: 33 and a VH of SEQ ID NO: 35; or (5) a VL of SEQ ID NO: 37 and a VH of SEQ ID NO: 39; or (6) a VL of SEQ ID NO: 41 and a VH of SEQ ID NO: 43; or (7) a VL of SEQ ID NO: 45 and a VH of SEQ ID NO: 47; or (8) a VL of SEQ ID NO: 49 and a VH of SEQ ID NO: 51; or (9) a VL of SEQ ID NO: 53 and a VH of SEQ ID NO: 55; or (10) a VL of SEQ ID NO: 57 and a VH of SEQ ID NO: 59; or (11) a VL of SEQ ID NO: 61 and a VH of SEQ ID NO: 63; or (12) a VL of SEQ ID NO: 65 and a VH of SEQ ID NO: 67; or (13) a VL of SEQ ID NO: 69 and a VH of SEQ ID NO: 71; or (14) a VL of SEQ ID NO: 73 and a VH of SEQ ID NO: 75; or (15) a VL of SEQ ID NO: 77 and a VH of SEQ ID NO: 79; or (16) a VL of SEQ ID NO: 49 and a VH of SEQ ID NO: 81.
A summary of the disclosed antibodies (or clones producing them), with their respective designation (e.g., SC78.1, SC78.4, etc.) and variable region nucleic acid or amino acid SEQ ID NOS (see FIGS. 6A - 6C) are shown immediately below in Table 5.
Table 5
Figure imgf000142_0001
The VL and VH amino acid sequences in FIGS. 6 A and 6B are annotated to identify the framework regions (i.e. FR1 - FR4) and the complementarity determining regions (i.e., CDRL1 - CDRL3 in FIG. 6A or CDRH1 - CDRH3 in FIG. 6B), defined as per Kabat et al. The variable region sequences were analyzed using a proprietary version of the Abysis database to provide the CDR and FR designations. Though the CDRs are defined as per Kabat et al., those skilled in the art will appreciate that compatible CDR and FR designations can also be defined according to Chothia, McCallum or any other accepted nomenclature system (e.g., see FIGS. 6G - 6J).
As seen in FIGS. 6A and 6B and Table 5 the SEQ ID NOS. of the heavy and light chain variable region amino acid sequences for each particular murine antibody are generally sequential odd numbers. Thus, monoclonal anti-KREMEN2 antibody SC78.1 comprises amino acid SEQ ID
NOS: 21 and 23 for the light and heavy chain variable regions respectively; SC78.4 comprises SEQ
ID NOS: 25 and 27; SC78.3 comprises SEQ ID NOS: 29 and 31, and so on. The exception to the sequential numbering scheme set forth in FIGS. 6A and 6B is at the end of Table 5 and comprises
SC78.39 which shares a light chain variable region (VL) with SC78.25. As such SC78.39 comprises a light chain variable region (VL) comprising SEQ ID NO: 49 and a heavy chain variable region (VH) comprising SEQ ID NO: 81. In any event the corresponding nucleic acid sequence encoding the murine antibody amino acid sequence (set forth in FIG. 6C) has a SEQ ID NO: immediately preceding the corresponding amino acid SEQ ID NO. Thus, for example, the SEQ ID NOS: of the nucleic acid sequences of the VL and VH of the SC78.1 antibody are SEQ ID NOS: 20 and 22, respectively.
In addition to the annotated sequences in FIGS. 6 A - 6C, FIGS. 6G - 6 J provide CDR designations for the light and heavy chain variable regions of SC78.9, SC78.43, SC78.56 and SC78.59 as determined using Kabat, Chothia, ABM and Contact methodology. The CDR designations depicted in FIGS. 6G - 6J were derived using a proprietary version of the Abysis database as discussed above. As shown in subsequent Examples those of skill in the art will appreciate that the disclosed murine CDRs may be grafted into human framework sequences to provide CDR grafted or humanized anti-KREMEN2 antibodies in accordance with the instant invention. Moreover, in view of the instant disclosure one could readily determine the CDRs of any anti-KREMEN2 antibody made and sequenced in accordance with the teachings herein and use the derived CDR sequences to provide CDR grafted or humanized anti-KREMEN2 antibodies of the instant invention. This is particularly true of the antibodies with the heavy and light chain variable region sequences set forth in in FIGS. 6A - 6B.
Example 8
Generation of Chimeric and Humanized anti-KREMEN2 Antibodies Chimeric anti-KREMEN2 antibodies were generated using art-recognized techniques as follows. Total RNA was extracted from the hybridomas and PCR amplified. Data regarding V, D and J gene segments of the VH and VL chains of the following murine antibodies: SC78.9, SC78.43, SC78.56 and SC78.59 were obtained from an analysis of the subject nucleic acid sequences (see FIG. 6C for nucleic acid sequences). Primer sets specific to the framework sequence of the VH and VL chains of the antibodies were designed using the following restriction sites: Agel and Xhol for the VH fragments, and Xmal and Dralll for the VL fragments. PCR products were purified with a Qiaquick PCR purification kit (Qiagen), followed by digestion with restriction enzymes Agel and Xhol for the VH fragments and Xmal and Dralll for the VL fragments. The VH and VL digested PCR products were purified and ligated into IgH or IgK expression vectors, respectively. Ligation reactions were performed in a total volume of 10 with 200U T4-DNA Ligase (New England Biolabs), 7.5 of digested and purified gene-specific PCR product and 25 ng linearized vector DNA. Competent E. coli DH10B bacteria (Life Technologies) were transformed via heat shock at 42 °C with 3 \L ligation product and plated onto ampicillin plates at a concentration of 100 μg/mL. Following purification and digestion of the amplified ligation products, the VH fragment was cloned into the Agel-Xhol restriction sites of the pEE6.4 expression vector (Lonza) comprising HulgGI and the VL fragment was cloned into the Xmal-Dralll restriction sites of the pEE12.4 expression vector (Lonza) comprising Hu-Kappa light constant region.
Chimeric antibodies comprising the entire murine heavy and light chain variable regions (SC78.9, SC78.43, SC78.56 and SC78.59) and human constant regions were expressed by co- transfection of CHO-S cells with pEE6.4HuIgGl and pEE12.4Hu-Kappa expression vectors and PEI as a transfection reagent. Supernatants were harvested three to six days after transfection. Culture supernatants containing recombinant chimeric antibodies were cleared from cell debris by centrifugation at 800xg for 10 mins. and stored at 4 °C. Recombinant chimeric antibodies were purified with Protein A beads.
Murine anti-KREMEN2 antibodies were also CDR grafted or humanized using a proprietary computer-aided CDR-grafting method (Abysis Database, UCL Business) and standard molecular engineering techniques as follows. Human framework regions of the variable regions were designed based on the highest homology between the framework sequences and CDR canonical structures of human germline antibody sequences, and the framework sequences and CDRs of the relevant mouse antibodies. For the purpose of the analysis the assignment of amino acids to each of the CDR domains was done in accordance with Kabat et al. numbering. In this regard FIGS. 6G to 6J show heavy and light CDRs derived using various analytical schemes for the murine antibodies SC78.9, SC78.43, SC78.56 and SC78.59. Once the variable regions comprising murine Kabat CDRs and the selected human frameworks were designed, they were generated from synthetic gene segments (Integrated DNA Technologies). Humanized antibodies were then cloned and expressed using methods substantially as described above for chimeric antibodies.
The VL and VH amino acid sequences of humanized antibodies hSC78.9 (SEQ ID NOS: 101 and 103), hSC78.43 (SEQ ID NOS: 105 and 107), hSC78.43 VK08 (SEQ ID NOS: 109 and 107), hSC78.56 (SEQ ID NOS: 113 and 115), and hSC78.59 (SEQ ID NOS: 117 and 119) are shown in FIG. 6D and are derived from the VL and VH sequences of the corresponding murine antibodies (e.g. hSC78.9 is derived from SC78.9). Note that hSC78.43 VK08 comprises a different light chain framework (SEQ ID NO: 109) than the humanized hSC78.43 antibody (SEQ ID NO: 105) though they share a common heavy chain. The corresponding nucleic acid sequences of the VL and VH are set forth in FIG. 6E (SEQ ID NOS: 100 - 118, even numbers) where SEQ ID NO: 110 comprises a codon optimized NA sequence that expresses hSC78.43 heavy chain (SEQ ID NO: 107). Table 6 below shows the components used to fabricate the humanized constructs and, in some cases, that selected framework changes were introduced to maintain the favorable properties of the selected antibodies.
Table 6
VH
human human VH FR CDR human human VK FR VK CDR in A I) Isot e VH JH chan es Chan es VK JK chan es chan es
Figure imgf000145_0001
As discussed below in Example 9 a number of site-specific constructs were fabricated using the humanized VL and VH sequences set forth in FIG. 6D. In addition, a N297A mutation (EU numbering) was introduced to selected humanized antibodies to reduce the binding of antibodies to Fc receptors, which is believed to be a source of off-target toxicity. This modification could be introduced in either the ssl or the wild type human IgGl constructs. In this case the N297A modification was introduced into the hSC78.9ssl and hSC78.43ssl antibodies as denoted by the MJ suffix (i.e., hSC78.9sslMJ and hSC78.43sslMJ). The mutation was introduced using the Quikchange mutagenesis kit on the plasmid for heavy chain expression, and the antibody was expressed and purified using the same methods described above.
The exemplary humanized antibodies set forth in Table 6 demonstrate that a number of clinically compatible antibodies may be generated and derived as disclosed herein. In certain aspects of the instant invention such antibodies may be incorporated in KREMEN2 ADCs to provide compositions comprising a favorable therapeutic index.
In addition to the aforementioned VH and VL amino acid and nucleic acid sequences, FIG. 6F provides full length heavy and light chain amino acid sequences for the exemplary humanized antibody constructs set forth in Table 6. It will be appreciated that FIG. 6F is annotated to designate the location of the site-specific mutations (underlined along with flanking AAs) giving rise to a free cysteine that may be conjugated as discussed herein and the N297A position (underlined and bolded along with flanking AAs) that may be mutated to reduce Fc receptor binding.
A summary of the nucleic and amino acid sequences associated with each of the humanized constructs (and with FIG. 6) are presented immediately below in Table 7. Note that a number of the constructs employ the same VL, VH or full length sequences in different arrangements.
Table 7
Figure imgf000147_0001
Example 9
Generation of Site-Specific Anti-KREMEN2 Antibodies
Engineered human IgGl/kappa anti-KREMEN2 site-specific antibodies were constructed comprising a native light chain (LC) constant region and mutated heavy chain (HC) constant region, wherein cysteine 220 (C220) in the upper hinge region of the HC, which forms an interchain disulfide bond with cysteine 214 (C214) in the LC, was substituted with serine (C220S). When assembled, the HCs and LCs form an antibody comprising two free cysteines that are suitable for conjugation to a therapeutic agent. Unless otherwise noted, all numbering of constant region residues is in accordance with the EU numbering scheme as set forth in Kabat et al.
The VH nucleic acids were cloned onto an expression vector containing the C220S mutation in the constant region of the HC. The vector encoding the mutant C220S HC of hSC78.9, hSC78.43, hSC78.56 or hSC78.59 was co-transfected in CHO-S cells with a vector encoding the native IgGl kappa LC of hSC78.9, hSC78.43, hSC78.43 VK08, hSC78.56 or hSC78.59, and expressed using a mammalian transient expression system. The engineered anti-KREMEN2 site-specific antibody containing the C220S mutant was termed hSC78.9ssl, hSC78.43ssl, hSC78.43ssl VK08, hSC78.56ssl or hSC78.59ssl, respectively. In addition, the N297A mutation was also introduced into two of the C220S mutated heavy chains to provide hSC78.9sslMJ and hSC78.43sslMJ. The amino acid sequences of the full length heavy chains (HC) of the hSC78.9ssl, hSC78.9sslMJ, hSC78.43ssl, hSC78.43sslMJ, hSC78.56ssl, hSC78.56sslMJ or hSC78.59ssl site- specific antibodies are shown in FIG. 6F (SEQ ID NOS: 133, 135, 139, 141, 147, 149 and 153, respectively). The amino acid sequence of the light chains (LC) of hSC78.9ssl and hSC78.9sslMJ are identical (SEQ ID NO: 130) as are the amino acid sequences of each of the LCs of hSC78.43ssl and hSC78.43sslMJ (SEQ ID NO: 136) and each of the LCs of hSC78.56ssl and hSC78.56sslMJ (SEQ ID NO: 144) while the LCs of hSC78.43ssl VK08 or hSC78.59ssl comprise SEQ ID NOS: 142 and 150, respectively. Thus, as shown in Table 7 above, the site-specific antibodies comprise, respectively, light and heavy chains as set forth in SEQ ID NO: 130 and SEQ ID NO: 133 (hSC78.9ssl), SEQ ID NO: 130 and SEQ ID NO: 135 (hSC78.9sslMJ), SEQ ID NO: 136 and SEQ ID NO: 139 (hSC78.43ssl), SEQ ID NO: 136 and SEQ ID NO: 141 (hSC78.43sslMJ), SEQ ID NO: 142 and SEQ ID NO: 139 (hSC78.43ssl VK08), SEQ ID NO: 144 and SEQ ID NO: 147 (hSC78.56ssl), SEQ ID NO: 144 and SEQ ID NO: 149 (hSC78.56sslMJ) and SEQ ID NO: 150 and SEQ ID NO: 153 (hSC78.59ssl).
The engineered anti-KREMEN2 site-specific antibodies were characterized by SDS-PAGE to confirm that the correct mutants had been generated. SDS-PAGE was conducted on a pre-cast 10% Tris-Glycine mini gel from Life Technologies in the presence and absence of a reducing agent such as DTT (dithiothreitol). Following electrophoresis, the gels were stained with a colloidal coomassie solution (data not shown). Under reducing conditions, two bands corresponding to the free LCs and free HCs, were observed. This pattern is typical of IgG molecules in reducing conditions. Under non-reducing conditions, the band patterns were different from native IgG molecules, indicative of the absence of a disulfide bond between the HC and LC. A band around 98 kD corresponding to the HC-HC dimer was observed. In addition, a faint band corresponding to the free LC and a predominant band around 48 kD that corresponded to a LC-LC dimer was observed. The formation of some amount of LC-LC species is expected due to the free cysteines on the c-terminus of each LC. Example 10
Preparation of Anti-KREMEN26 Antibody-Drug Conjugates
Native and site-specific anti-KREMEN2 antibodies such as those set forth in Table 7 were conjugated to a pyrrol obenzodiazepine (PBD1 and PBD3 respectively) via a terminal maleimido moiety with a free sulfhydryl group to create antibody drug conjugates (i.e., ADC3 and ADC6).
The native anti-KREMEN2 ADCs were prepared as follows. The cysteine bonds of anti-
KREMEN2 antibodies were partially reduced with a pre-determined molar addition of mol tris(2- carboxyethyl)-phosphine (TCEP) per mol antibody for 90 min. at room temperature in phosphate buffered saline (PBS) with 5 mM EDTA. The resulting partially reduced preparations were then conjugated to PBD3 (the structure of PBD3 is provided above in the current specification) via a maleimide linker for a minimum of 30 mins. at room temperature. The reaction was then quenched with the addition of excess N-acetyl cysteine (NAC) compared to linker-drug using a 10 mM stock solution prepared in water. After a minimum quench time of 20 mins., the pH was adjusted to 6.0 with the addition of 0.5 M acetic acid. The preparations of the ADCs were buffer exchanged into diafiltration buffer by diafiltration using a 30 kDa membrane. The dialfiltered anti-KREMEN2 ADCs were then formulated with sucrose and polysorbate-20 to the target final concentration. The resulting anti-KREMEN2 ADCs were analyzed for protein concentration (by measuring UV), aggregation (SEC), drug to antibody ratio (DAR) by reverse-phase HPLC (RP-HPLC) and activity {in vitro cytotoxicity).
The site-specific humanized anti-KREMEN2 ADCs were conjugated using a modified partial reduction process. The desired product is an ADC that is maximally conjugated on the unpaired cysteine (C214) on each LC constant region and that minimizes ADCs having a drug to antibody ratio (DAR) which is greater than 2 (DAR>2) while maximizing ADCs having a DAR of 2 (DAR=2). In order to further improve the specificity of the conjugation, the antibodies were selectively reduced using a process comprising a stabilizing agent (e.g. L-arginine) and a mild reducing agent (e.g. glutathione) prior to conjugation with the linker-drug, followed by a diafiltration and formulation step.
A preparation of each antibody was partially reduced in a buffer containing 1M L- arginine/5mM EDTA with a pre-determined concentration of reduced glutathione (GSH), pH 8.0 for a minimum of two hours at room temperature. All preparations were then buffer exchanged into a 20 mM Tris/3.2 mM EDTA, pH 7.0 buffer using a 30 kDa membrane (Millipore Amicon Ultra) to remove the reducing buffer. The resulting partially reduced preparations were then conjugated to DL3 and DL6 (the structure of the drug linkers are provided above in the current specification) via a maleimide linker for a minimum of 30 mins. at room temperature. The reaction was then quenched with the addition of excess NAC compared to linker-drug using a 10 mM stock solution prepared in water. After a minimum quench time of 20 minutes, the pH was adjusted to 6.0 with the addition of 0.5 M acetic acid. The preparations of the ADCs were buffer exchanged into diafiltration buffer by diafiltration using a 30 kDa membrane. The dialfiltered anti-KREMEN2 ADC was then formulated with buffers to the target final concentration. The resulting anti-KREMEN2 ADCs were analyzed for protein concentration (by measuring UV), aggregation (SEC), drug to antibody ratio (DAR) by reverse-phase HPLC (RP-HPLC) and activity {in vitro cytotoxicity).
Example 11
Characteristics of KREMEN2 Antibodies
Various methods were used to characterize the anti-KREMEN2 mouse antibodies generated in Example 6 in terms of isotype, affinity for hKREMEN2, cross reactivity to cyno and rat KREMEN2 (cKREMEN2 and rKREMEN2) and binding kinetics. FIG. 7 provides a table summarizing the aforementioned characteristics for a number of exemplary murine antibodies (upper table) and selected humanized constructs (lower table). In FIG. 7, a blank cell or "N/D" indicates that the data was not generated in that instance.
The isotype of a representative number of antibodies was determined by RNA sequencing (see Example 7).
The affinity of selected humanized antibodies for human (hKREMEN2-His), cyno (cKREMEN2-His)and rat (rKREMEN2-His) was qualitatively determined from kinetics curves generated with a ForteBio RED as follows: Anti-KREMEN2 antibodies were immobilized onto anti-mouse Fc capture biosensors with a contact time of 3 min. and a flow rate of 1000 rpm. The captured antibody loading from baseline was constant at 0.3-1 units. Following antibody capture and 50 second baseline, the biosensors were dipped into a 300 nM solution of hKREMEN2-His, cKREMEN2-His or rKREMEN2-His for a 4 min. association phase followed by a 4 min. dissociation phase at a shaking rate of 1000 rpm. The biosensors were regenerated by dipping into 10 mM glycine, pH 1.7 following each cycle. The data was processed by subtracting a control mouse IgG surface response from the specific antibody response and data was truncated to the association and dissociation phase. The association and dissociation curves were used to qualitatively estimate the affinities of selected antibodies (data not shown). Antibodies that cross- react with high affinity to rKREMEN2 protein were identified (lower table in FIG. 7).
The affinity of select antibodies for human, rat and cynomolgus monkeys (hKREMEN2, cKREMEN2 and rKREMEN2) protein was quantitated using surface pi asm on resonance using a Biacore T200 instrument (GE Healthcare). An anti-mouse antibody capture kit was used to immobilize anti-mouse antibodies for capture of mouse anti-KREMEN2 antibodies on a CM5 biosensor chip. Prior to each antigen injection cycle, murine antibodies at a concentration 5 μg/mL were captured on the surface with a contact time of 30 seconds and a flow rate of 20 μί/ηιίη. The captured antibody loading from baseline was between 80-120 response units. Following antibody capture and 10 second baseline, hKREMEN2-His antigen generated in Example 4 was flowed over the surface at varying concentrations for a 60 second association phase followed by a 4 min. dissociation phase at a flow rate of 50 μΕ/πώι. A similar protocol was used for measuring binding affinity of humanized antibodies except that an anti -human antibody capture kit was used. The data was processed by subtracting a control non-binding antibody surface response from the specific antibody surface. The resulting response curves were used to fit a 1 : 1 Langmuir binding model and to generate an equilibrium dissociation constant using the calculated ka and kd kinetics constants the Biacore T200 Evaluation software (GE Healthcare). The antibodies exhibited affinities for hKREMEN2, cKREMEN2 and rKREMEN2 in the nanomolar range (data not shown).
Antibodies were grouped into bins using a multiplexed competition immunoassay (Luminex
Corp.). 100 μΐ of each anti-KREMEN2 antibody (capture mAb) at a concentration of 10 μg/mL was incubated for 1 hour with magnetic beads (Luminex) that had been conjugated to an anti-mouse kappa antibody (Miller et al., 2011, PMID: 21223970). The capture mAb/conjugated bead complexes were washed with PBSTA buffer (1% BSA in PBS with 0.05% Tween20) and then pooled. Following removal of residual wash buffer the beads were incubated for 1 hour with 2 μg/mL hKREMEN2-His protein, washed and then resuspended in PBSTA. The pooled bead mixture was distributed into a 96 well plate, each well containing an anti-KREMEN2 antibody (detector mAb) and incubated for 1 hour with shaking. Following a wash step, anti-mouse kappa antibody (the same as that used above), conjugated to PE, was added at a concentration of 5 μg/ml to the wells and incubated for 1 hour. Beads were washed again and resuspended in PBSTA. Mean fluorescence intensity (MFI) values were measured with a Luminex MAGPIX instrument. Antibody pairing was visualized as a dendrogram of a distance matrix computed from the Pearson correlation coefficients of the antibody pairs. Binning was determined on the basis of the dendrogram and analysis of the MFI values of antibody pairs. FIG. 7 shows that the anti- KREMEN2 antibodies that were screened can be grouped into at least five unique bins, A, B, C, D, E on the hKREMEN2 protein.
Example 12
Effect of anti-KREMEN2 Antibodies
on DKK1-KREMEN2 Interaction
The WNT pathway is a critical developmental and stem cell-associated signaling pathway regulating cell growth and differentiation. In the canonical WNT/ -catenin signaling pathway, WNT ligands bind a complex of a Frizzled (FZD) receptor and a LRP5/6 co-receptor, initiating the signaling cascade resulting in the inhibition of the protein GSK3, one result of which is the stabilization of the normally labile β-catenin protein found in the cytoplasm. Stabilized β-catenin is then able to accumulate, enter the nucleus, and form complexes with TCF/LEF transcription factors to activate genes containing binding sites for these transcriptional activators. The canonical WNT pathway is regulated extensively at the receptor-ligand level, with multiple activating and inhibitory feedback loops comprised of various soluble decoy receptors (e.g., SFRPs and FRZB), factors that bind WNT itself or modulate its bioactivity (e.g., WIF and NOTUM), or factors that modulate FZD receptor turnover (e.g., KREMEN2, ZNRF3), and still more elaborate loops comprised of proteins that modulate the modulators (e.g., LGRs and RSPOs). Together these agonist, antagonist and anti- antagonist networks enable a fine control over the strength and duration of a powerful and pleiotropic signaling pathway. Specifically relevant to the present invention is the DKK- 1/LRP6/KREMEN2 interaction which has been show to downregulate Wnt signaling.
An electrochemiluminscence ELISA assay was developed using the MSD Discovery Platform (Meso Scale Discovery, MSD) to test the ability of the anti-KREMEN2 antibodies generated in Example 7 to block binding of KREMEN2 to DKK-1. MSD standard plates were coated with human KREMEN2 (R&D Systems; #1956-KR-025), at 0.5 ug mL in PBS and incubated overnight at 4 °C. After the plates were washed with PBS, 0.05% tween20 (PBST), they were blocked with 3% (w/v) BSA in PBS for 1 hour at room temperature. After the plates were washed with PBST, K^g/ml of SC78 antibodies, msIgG isotype control, no antibody, or anti-KREMEN2 polyclonal antibody (R&D Systems; #AF1946) was added and the plate was incubated for 1 hour at room temperature. Again plates were washed with PBST followed by addition of titration of DKK-1 protein (R&D Systems; #5439-DK-010) for 1 hour at room temperature. The plates were washed in PBST and anti -DKK-1 polyclonal antibody (R&D Systems; #AF1096), which was then sulfo- tagged using an MSD® SULFO-TAG NHS Ester according to the manufacturer's protocol, was added at 0.5 μ^πιΕ for 45 minutes. Plates were washed in PBST. MSD Read Buffer T with surfactant was diluted to IX in water and 150 μΙ_, was added to each well. Plates were read on an MSD Sector Imager 2400.
The results for exemplary KREMEN2-specific antibodies can be seen in FIG 8. Samples were run on different plates and are therefore graphed separately and compared to the appropriate no antibody control on the appropriate plate/graph. Decrease in binding compared to no anti- KREMEN2 antibody or isotype control antibody indicates interference or blocking of the KREMEN2/DKK-1 interaction. The polyclonal anti-KREMEN2 antibody serves as a positive control for interference of the interaction. Two antibodies (SC78.9 and SC78.43) have modest blocking activity whereas SC78.56 and SC78.59 did not affect KREMEN2/DKK- 1 binding.
Example 13
KREMEN2 Protein Expression in Tumors
Given the elevated KREMEN2 mRNA transcript levels associated with various tumors described in the Examples above, work was undertaken to test whether KREMEN2 protein expression was also elevated in PDX tumors. To detect and quantify KREMEN2 protein expression, an electrochemiluminscence KREMEN2 sandwich ELISA assay was developed using the MSD Discovery Platform (Meso Scale Discovery).
PDX tumors were excised from mice and flash frozen on dry ice/ethanol. Protein Extraction Buffer (Biochain Institute) was added to the thawed tumor pieces and tumors were pulverized using a TissueLyser system (Qiagen). Lysates were cleared by centrifugation (20,000 g, 20 mins., 4 °C) and the total protein concentration in each lysate was quantified using bicinchoninic acid. The protein lysates were normalized to 5 mg/mL and stored at -80 °C until assayed. Normal tissues were purchased from a commercial source and processed as described above.
KREMEN2 protein concentrations from the lysate samples were determined by interpolating the values from a standard protein concentration curve that was generated using purified recombinant KREMEN2 protein with a histidine tag. The KREMEN2 protein standard curve and protein quantification assay were conducted as follows:
MSD 384 well standard plates were coated overnight at 4 °C with 15 μΐ^ of an anti- KREMEN2 capture antibody at 2 μg/mL in PBS. Plates were washed in PBST and blocked in 35 μΐ^ MSD 3% Blocker A solution for one hour while shaking. Plates were again washed in PBST. 10 μΐ^ of 5x diluted lysate or serially diluted recombinant KREMEN2 standard in MSD 1% Blocker A containing 10% Protein Extraction Buffer was added to the wells and incubated for two hours while shaking. Plates were again washed in PBST. The anti-KREMEN2 detection antibody was then sulfo-tagged using an MSD® SULF0-TAG NHS Ester according to the manufacturer's protocol. 10 μΕ of the tagged anti-KREMEN2 detection antibody was added to the washed plates at 0.5 μg/mL in MSD 1% Blocker A for 1 hour at room temperature while shaking. Plates were washed in PBST. MSD Read Buffer T with surfactant was diluted to IX in water and 35 μΕ was added to each well. Plates were read on an MSD Sector Imager 2400 using an integrated software analysis program to derive KREMEN2 concentrations in lysate samples via interpolation from the standard curve. Values were then divided by total protein concentration to yield nanograms of KREMEN2 per milligram of total lysate protein.
The results are shown in FIG. 9 wherein each spot represents KREMEN2 protein concentrations derived from a single PDX tumor line. While each spot is derived from a single PDX line, in most cases multiple biological samples were tested from the same PDX line and values were averaged to provide the data point.
FIG. 9 shows that exemplary PDX tumor cell lines exhibit high KREMEN2 protein expression compared to normal tissues. Normal tissues that were tested include adrenal gland, artery, colon, esophagus, gall bladder, heart, kidney, liver, lung, peripheral and sciatic nerve, pancreas, skeletal muscle, skin, small intestine, spleen, stomach, trachea, red and white blood cells and platelets, bladder, brain, breast, eye, lymph node, ovary, pituitary gland, prostate and spinal cord. In a number of the tested PDX cell lines (e.g., BR202, LU120, LU139, LU85, OV89, OV1 19MET, OV27MET, and OV72MET) there was a good correlation between KREMEN2 protein expression and KREMEN2 mRNA expression (as determined either by microarray or qPCR). These data, combined with the mRNA transcription data for KREMEN2 expression set forth above reinforce the proposition that KREMEN2 determinants provide attractive targets for therapeutic intervention. Example 14
Detection of KREMEN2 on Tumors using Immunohistochemistry
Immunohistochemistry (IHC) was performed on PDX tumors and patient biopsies to assess the expression and location of KREMEN2 in tumor cells.
In order to determine the prevalence of KREMEN2, IHC was performed on PDX tumor cell line pellets using the anti-KREMEN2 antibody SC78.29. More particularly IHC was performed, as described below, on PDX tumor cell pellets that were formalin fixed and paraffin embedded (FFPE) as is standard in the art.
Planar sections of cell pellet blocks were cut and mounted on glass microscope slides. After xylene de-paraffinization 5 μπι sections were pre-treated with Antigen Retrieval Solution (Dako) for 20 minutes at 99 °C, cooled to 75 °C and then treated with 3% hydrogen peroxide in PBS followed by Avidin/Biotin Blocking Solution (Vector Laboratories). FFPE slides were then blocked with 10% horse serum in 3% BSA in PBS buffer and incubated with a primary anti- KREMEN2 antibody of the invention, diluted to 10 μg/ml in 3% BSA/PBS, for 30 minutes at room temperature. FFPE slides were incubated with biotin-conjugated horse anti-mouse antibody (Vector Laboratories), diluted to 2.5 μg/ml in 3% BSA/PBS, for 30 minutes at room temperature followed by incubation in streptavidin-HRP (ABC Elite Kit; Vector Laboratories). Chromogenic detection was developed with 3,3'-diaminobenzidine (Thermo Scientific) for 5 minutes at room temperature and tissues were counterstained with Meyer's hematoxylin (IHC World), dehydrated with alcohol and immersed in xylene. Stained slides were analyzed by light microscopy. An H-score was utilized to quantify staining. The H-score is a method of assessing the extent of staining by utilizing the following formula: 3X percentage of tumor cells staining at 3+ intensity + 2X percentage of tumor cells staining at 2+ intensity + IX percentage of tumor cells staining at 1+ intensity, giving a range from 0 to 300.
As shown by the tabular data set forth in FIG. 10 the anti-KREMEN2 antibody was able to determine whether hKREMEN2 was expressed in various lung, ovarian and breast PDX models and provide an H-score as set forth above. A review of the data shows KREMEN2 protein expression is exhibited in 9/29 (31%) of lung PDX tumor samples, 5/11 (45%) of ovarian PDX tumor samples, and 10/15 (67%) of breast PDX tumor samples.
Using substantially the same procedures immunohistochemistry was also performed on ovarian, lung and breast cancer biopsy samples. In this regard FIG. 11 A shows that KREMEN2 is expressed in 12/92 (13%) of ovarian serous papillary carcinoma and 12/54 (22%) of endometrioid adenocarcinoma. FIG. 1 1B shows that KREMEN2 is expressed in 8/82 (10%) of breast invasive ductal carcinoma and 2/26 (8%) of invasive ductal carcinoma with diagnosed as luminal B. And finally, FIG. 11C shows that KREMEN2 is expressed in 3/58 (5%) of lung adenocarcinoma, 29/187 (16%)) of lung squamous cell carcinoma and 2/12 (17%) of small cell lung cancer.
Taken together these data are strongly indicative that KREMEN2 protein is expressed on a substantial percentage of various tumors and reinforces the viability of using the determinant as a diagnostic and therapeutic target.
Example 15
KREMEN2 Protein is Expressed on Tumorigenic Cells
The ability of the antibodies of the invention to bind KREMEN2 expressed on PDX tumor cells was assessed as follows.
PDX tumors were harvested and dissociated using art-recognized enzymatic tissue digestion techniques to obtain single cell suspensions of PDX tumor cells (see, for example, U. S.P.N. 2007/0292414). PDX tumor single cell suspensions were incubated with anti-mouse CD45 and H- 2Kd antibodies to identify mouse cells, and anti-human EPCAM antibody to identify human cells. In addition the tumor cells were incubated with anti-human CD46 AlexaFluor-647 and CD324 PerCP Cy5.5 in order to identify tumorigenic cells (e.g., CSCs, TICs) (see U.S.P.N.s 2013/0260385, 2013/0061340 and 2013/0061342). Finally, the PDX tumor cells were incubated with anti- KREMEN2 biotinylated clone SC78.40 to determine cell surface expression of KREMEN2 on PDX subpopulations. The isolated cells were incubated for 30 min. with primary antibodies or with isotype matched control antibodies and washed twice in PBS/2%> FCS. The cells were incubated for 15 min. with 50 per sample phycoerythrin labeled streptavidin secondary antibody diluted 1 :200 in PBS/2%FCS, washed twice with 1 mL PBS/2% FCS and re-suspended in PBS/2% FCS with 4',6- diamidino-2-phenylindoleanti (DAPI) to differentiated live and dead cells. Antibody binding to the PDX tumor cells was then analyzed by flow cytometry using a BD FACS Canto II flow cytometer in accordance with the manufacturer's instructions.
FIGS. 12A - 12C show that NSCLC (FIG. 12 A), OV (FIG. 12B), and BR (FIG. 12C) PDX expressed detectable levels of KREMEN2 protein on live human tumor cells (LU85, LU306, LU409, LU296, LU450, BR163, BR164, BR165) and CSC subpopulations (solid black line; LU37, LU300, LU120, LU253, LU128, OV27, OV72MET, OV63MET, OV89) whereas NTG cells (not expressing CD324 or CD46) (dashed line) demonstrated significantly less staining with anti- KREMEN2 antibodies. Fluorescence minus one (FMO) and isotype control antibodies were employed to confirm staining specificity (gray-filled). A table summarizing the differential staining of anti-KREMEN2 antibodies observed on the surface of CSC and NTG cells is shown in each of FIGS. 12A - 12C, with expression enumerated as the change in geometric mean fluorescence intensity (AMFI) between the indicated anti-KREMEN2 antibody and the isotype control for the respective tumor cell subpopulations. This data further confirms the elevated expression of KREMEN2 on tumorigenic cells and the ability of antibodies of the instant invention to selectively bind to such cells.
The functional CSC subpopulation in most NSCLC and OV-S PDX is <1 : 100 cells, while phenotypic cell surface markers of cell populations that include the CSC subpopulation ranges from 1-94% of NSCLC and OV-S PDX tumors. As KREMEN2 is observed to be elevated in the CSC subpopulation which is only part of a bulk tumor, there is a greater expression differential between CSC populations and normal tissue expression as compared to whole PDX tumor expression compared to normal tissues. This results in a larger expression differential of KREMEN2 between CSC in tumors and normal tissue expression, pointing towards the beneficial use of anti-KREMEN2 modulators in treating tumors with expression of KREMEN2 in CSC subpopulations
Example 16
Anti-KREMEN2 Antibodies Facilitate Delivery of Cytotoxic Agents To determine whether anti-KREMEN2 antibodies of the invention are able to internalize in order to mediate the delivery of cytotoxic agents to cells, an in vitro cell killing assay was performed using selected anti-KREMEN2 antibodies and saporin linked to a secondary anti-mouse antibody FAB fragment. Saporin is a plant toxin that deactivates ribosomes, thereby inhibiting protein synthesis and resulting in the death of the cell. Saporin is only cytotoxic inside the cell where it has access to ribosomes, but is unable to internalize on its own. Therefore, saporin- mediated cellular cytotoxicity in these assays is indicative of the ability of the anti-mouse FAB- Saporin construct to internalize upon binding and internalization of the associated murine or humanized anti-KREMEN2 antibodies into the target cells. Single cell suspensions of HEK293T cells overexpressing hKREMEN2 were plated at 500 cells per well into BD Tissue Culture plates (BD Biosciences). One day later, various concentrations of purified anti-KREMEN2 antibodies (either murine or humanized) were added to the culture together with a fixed concentration of 2 nM anti-mouse IgG FAB-saporin conjugates (Advanced Targeting Systems) (for testing mouse antibodies) or 2 nM anti -human IgG FAB- saporin conjugates (for testing humanized antibodies). Following incubation for 96 hours, viable cells were enumerated using CellTiter-Glo® (Promega) as per the manufacturer's instructions. Raw luminescence counts using cultures containing cells incubated only with the secondary FAB-saporin conjugate were set as 100% reference values and all other counts were calculated as a percentage of the reference value. A large subset of anti-KREMEN2 murine antibodies at a concentration of 100 pM effectively killed HEK293T cells overexpressing hKREMEN2 with varying efficacy whereas the mouse IgG2b isotype control antibody (mIgG2b) at the same concentration did not (data not shown). In addition, the anti-KREMEN2 humanized antibodies (hSC78.9, hSC78.43, hSC78.56, and hSC78.59) and corresponding chimeric antibody control effectively killed HEK293T cells overexpressing KREMEN2 (FIG. 13). The humanized antibodies showed comparable efficacy to the chimeric antibody (in the case of hSC78.9, hSC78.56 and hSC78.59) from which they were derived (hSC78.43 chimeric antibody did not bind KREMEN2 and was not available as a control).
The above results demonstrate the ability of anti-KREMEN2 antibodies to mediate internalization and their ability to deliver cytotoxic payloads, supporting the hypothesis that anti- KREMEN2 antibodies may have therapeutic utility as the targeting moiety of an ADC.
Example 17
KREMEN2 Surface Marker Expression
Enriches for Tumor Initiating Cells in Tumors in vivo
Example 15 above demonstrates that expression of KREMEN2 may be associated with phenotypic tumor initiating cells in NSCLC and OV-S PDX.
In order to understand the functional capabilities of tumor cells expressing KREMEN2 to act as CSC and re-grow tumors after cell isolation, LU205 (LU-AD) and OV89 (OV-S) were dissociated and stained using the method described in Example 15. High and low/negative live, human tumor cells expressing KREMEN2 were isolated using fluorescent-activated cell sorting with BD FACS ARIA II flow cytometer. Isolated tumor cells were separated into Eppendorf tubes containing PBS/2% FCS. SC78-positive and SC78-negative isolated tumor cells were injected subcutaneously into 5 recipient mice each at an inoculum of 50 cells per recipient mouse for LU205 and 180 cells per recipient mouse for OV89.
Positive tumor growth is defined as growth of a tumor exceeding 200 mm3. In LU205, 5/5 mice injected with KREMEN2 -positive tumor cells grew tumors, while only 3/5 mice injected with KREMEN2-negative tumor cells grew tumors (FIG. 14A). In OV89, 5/5 mice injected with KREMEN2-positive tumor cells grew tumors, while 4/10 mice injected with KREMEN2 -negative tumor cells grew tumors (FIG. 14B). These results suggest that while KREMEN2 does not exclusively mark tumor initiating cells in this model, expression of the marker does enrich for a population of tumor initiating cells more capable of re-growing tumors after cell-isolation than tumor cells that do not express KREMEN2.
The data indicate that KREMEN2 expression on specific cell populations are more aggressive tumorigenic cells within NSCLC and OV-S tumors and that targeted anti-KREMEN2 therapies could effectively target this subpopulation.
Example 18
KREMEN2 Expression Status and Somatic Mutations
The mutational status of various relevant genes in breast, NSCLC, and ovarian
(BR, NSCLC, OV) patient derived xenograft (PDX) line may be determined by performing targeted re-sequencing of genomic DNA (gDNA).
Targeted re-sequencing of gDNA may be performed using gDNA from each BR, NSCLC, OV PDX cell line to generate a library with the Ion AmpliSeq Library Kit 2.0 and a custom panel of AmpliSeq primers (Life Technologies) encompassing over 3000 amplicons of up to 250 bp, and covering coding and non-coding regions of multiple genes. Each sample may be ligated to an Ion Xpress Barcode Adapter (Life Technologies) to allow pooling of multiple samples for each sequencing run. Sequencing can then be performed on an Ion Torrent PGM machine (Life Technologies), and data analysis can be carried out to identify variations in sequence of tumor- related genes that lead to changes at the gDNA, mRNA transcript and protein levels.
In some embodiments, the mutational status of tumor-related genes can be used as a surrogate biomarker (as described in more detail below) to determine whether there is a correlation between various genetic mutations and the expression of KREMEN2, which may be informative of the effectiveness of treating a tumor (e.g. BR, NSCLC, OV-S) with the anti- KREMEN2 antibodies or ADCs of the invention. In other embodiments the mutational status of the BR, NSCLC, and OV- related genes can be used to determine whether there is a correlation between genetic mutations and the response to treatment with the anti- KREMEN2antibodies or ADCs of the invention. In further embodiments the mutational status of the BR, NSCLC, or OV-S-related genes can be used to determine effective combination therapies.
To determine the significance of mutations that correlate with expression of KREMEN2, BR, NSCLC, and OV-S PDX tumors were evaluated for targeted re-sequencing of major cancer driver genes using Ion Ampliseq and Ion Torrent PGM technologies described above. BR, NSCLC, and OV-S tumors with high and low in expression of KREMEN2 were determined by microarray and used to correlate mutation data with KREMEN2 expression. A coding mutation is defined by any non-synonymous alteration occurring in the protein-coding region of the sequenced gene, including missense non-synonymous, insertions or deletions of codons, amplicon deletions or amplicon amplifications, nonsense non-synonymous, frameshift, and mutations that lead to altered splice-site variants of the gene sequenced. The results of the analysis are set forth in Tables 8 and 9 below and in FIGS. 15A and 15B appended hereto.
Table 8
NSCLC PDX Mutations Associated With KREMEN2 Expression
Figure imgf000161_0001
NSCLC PDX tumors highly expressing KREMEN2 were found to associate with PDX lines carrying mutational variation (e.g. non-synonymous coding-mutations, deleted and gained exons) in
FGFR2. KREMEN2 expression was also associated with deletions throughout FGFR2, GRIN2A, and PTCH1 coding exons (FIG. 15A & Table 8). NSCLC PDX tumors lines containing a coding mutation or deletion in FGFR2 were significantly associated with a 3.6-fold lower expression of
KREMEN2 in microarray datasets compared to PDX tumors not carrying mutations as determined by Welch's T-test. Exon deletions in PTCH1 appear to predict 2-fold higher expression of
KREMEN2. The lack of significance observed in deletions of GRIN2A exons for NSCLC PDX datasets may be due to the relative infrequency of this mutation in the PDX dataset or to a low frequency tumor cell clone carrying the mutation within a NSCLC PDX tumor.
TABLE 9
OV and BR PDX PTCHl Mutations Associated with KREMEN2 Expression
Figure imgf000162_0001
For OV-S PDX, coding mutations in PTCHl predicted higher expression of KREMEN2, while deletions of PTCHl exons in both OV-S and BR PDX were observed to be associated with higher expression of KREMEN2 (FIG.15B & Table 9). For OV and BR PDX, the association of PTCHl mutations with KREMEN2 expression was not significant. The lack of significance, again, could be due to the small sample set or an in frequent mutated tumor cell clone residing in the PDX tumor. These data suggest that non-synonymous mutations detected in these genes may correlate with expression or absence of expression of KREMEN2. Thus, such mutations may be useful as biomarkers to predict expression of KREMEN2 in patient populations and more accurately guide treatment for these subsets of tumors. Example 19
Anti-KREMEN2 Antibody Drug Conjugates
Induce Durable Tumor Regression in vivo
To assess the activity of anti-KREMEN2 antibody drug conjugates in a representative tumor environment, in vivo efficacy studies were performed in lung squamous (LU), breast (BR), and ovarian (OV) PDX models. The ADCs comprise humanized site-specific anti-KREMEN2 antibodies comprising an N297A mutation to reduce non-specific Fc-mediated binding conjugated to PBDl using a cleavable linker (i.e. ADC6).
NOD/SCID mice bearing PDX tumors were randomized when tumor volume was 100-250 mm3 into groups of at least 5 animals and treated with a single dose of vehicle or 0.4 mg/kg humanized IgGl isotype control ADC, hSC78.43ssl PBDl, hSC78.43sslMJ PBDl or hSC78.56sslMJ PBDl by intraperitoneal injection. Tumor volumes were measured and recorded weekly after treatment, and animals were sacrificed when tumor volumes exceeded 1000 mm3 or after 130 days of study duration. The results are graphically shown in FIG. 16.
In the lung squamous cell carcinoma model LU495, single dose treatments of hSC78.43sslMJ PBDl or hSC78.56sslMJ PBDl produced durable responses in all animals treated, with no tumor recurrence observed 76 days after dosing, whereas vehicle or isotype ADC control -treated animals exhibited rapid tumor growth requiring termination after 14 days. Similar observations were made in the breast cancer PDX BR202, which exhibited curative durable responses in two of five animals and indolent recurrence in a third animal for over 123 days after treatment with hSC78.43ssl PBDl, whereas vehicle or isotype ADC control -treated animals exceeded 1000 mm3 within 15 and 26 days, respectively. Further, ovarian O VI 19MET-b earing mice treated with a single dose of hSC78.43ssl PBDl exhibited durable, curative responses for at least 128 days after dosing, whereas all animals treated with vehicle or human IgGl LD6.23 ADC control recurred.
These data indicate that SC78-targeted antibody drug conjugates are effective in specifically targeting and eradicating lung, breast, and ovarian tumors in vivo. Example 20
Anti-KREMEN2 Antibody Drug Conjugates
Effectively Deplete Cancer Stem Cells
To investigate the ability of anti-KREMEN2 antibody drug conjugates to target and eliminate cancer stem cell populations, an in vivo limiting dilution analysis (LDA) was performed.
Briefly, NOD/SCID animals bearing LU450 lung squamous cell carcinoma PDX tumors were randomized and treated as above with vehicle, or 0.1 mg/kg of either humanized IgGl isotype ADC control, hSC78.43sslMJ PBD3 or hSC78.56sslMJ PBD3 (i.e., both ADC3). Seven days following dosing, two animals per group were sacrificed, tumors were harvested, disaggregated into single cell suspensions as previously described, and 2 million cells of each group were stained with anti- mouse CD45 FITC, anti-mouse H2kD FITC, anti-human-ESA PE-Cy7, anti-human CD46 APC, and anti-human CD324 PerCP for 20 minutes at 4C in Eppendorf tubes in 50 ul volume. Cells were washed twice successively with 1 mL of PBS/2%FCS, resuspended in PBS/2%FCS containing DAPI, and live human cells were identified and sorted at defined inoculums as DAPI-low, CD45/H2kD FITC-negative, human ESA PE-Cy7-positive with a FACS Aria II cell sorter in the following series:
Vehicle (3001, 1001, 301, 101 cells per mouse)
Isotype control ADC (3002, 1002, 3002, 102 cells per mouse),
hSC78.43sslMJ PBD3 (3003, 1003, 303, 103 cells per mouse)
hSC78.56sslMJ PBD3 (3004, 1004, 304, 104 cells per mouse)
Ten NOD/SCID animals were injected subcutaneously per each inoculum. Animals were monitored weekly and tumor growth was recorded until a 4 week period had elapsed with no additional tumor growth. Animals which had grown tumors in this period were scored as TG+, whereas those which had died prior to tumor growth were censored. Tumor initiating (TIC) frequency was determined by Poisson distribution analysis using L-Calc (STEMCELL Technologies).
Vehicle and isotype control ADC treated animals grew tumors in all surviving animals in each dilution group assessed, projecting TIC frequencies of at least 23.3 and 22.7 per 1000 cells, respectively (FIG. 17). In contrast, no tumors grew in any inoculum level of hSC78.43sslMJ PBD3 or hSC78.56sslMJ PBD3 treated animals, projecting TIC frequencies of less than 0.03 and 0.02 per 1000 cells, respectively.
These data demonstrate that the anti-KREMEN2 ADCs of the invention efficiently deplete tumor initiating cells from human lung squamous cell carcinoma PDX models indicating that the KREMEN2 determinant is a viable therapeutic target.
Those skilled in the art will further appreciate that the present invention may be embodied in other specific forms without departing from the spirit or central attributes thereof. In that the foregoing description of the present invention discloses only exemplary embodiments thereof, it is to be understood that other variations are contemplated as being within the scope of the present invention. Accordingly, the present invention is not limited to the particular embodiments that have been described in detail herein. Rather, reference should be made to the appended claims as indicative of the scope and content of the invention.

Claims

CLAIMS:
1. A monoclonal antibody that binds to tumor initiating cells expressing KREMEN2.
2. A monoclonal antibody that binds to human KREMEN2 comprising SEQ ID NO: 1. 3. A monoclonal antibody that binds to human KREMEN2 and comprises or competes for binding with an antibody comprising:
a light chain variable region (VL) of SEQ ID NO: 21 and a heavy chain variable region (VH) of SEQ ID NO: 23; or
a VL of SEQ ID NO: 25 and a VH of SEQ ID NO: 27; or
a VL of SEQ ID NO: 29 and a VH of SEQ ID NO: 31; or
a VL of SEQ ID NO: 33 and a VH of SEQ ID NO: 35; or
a VL of SEQ ID NO: 37 and a VH of SEQ ID NO: 39; or
a VL of SEQ ID NO: 41 and a VH of SEQ ID NO: 43; or
a VL of SEQ ID NO: 45 and a VH of SEQ ID NO: 47; or
a VL of SEQ ID NO: 49 and a VH of SEQ ID NO: 51; or
a VL of SEQ ID NO: 53 and a VH of SEQ ID NO: 55; or
a VL of SEQ ID NO: 57 and a VH of SEQ ID NO: 59; or
a VL of SEQ ID NO: 61 and a VH of SEQ ID NO: 63; or
a VL of SEQ ID NO: 65 and a VH of SEQ ID NO: 67; or
a VL of SEQ ID NO: 69 and a VH of SEQ ID NO: 71; or
a VL of SEQ ID NO: 73 and a VH of SEQ ID NO: 75; or
a VL of SEQ ID NO: 77 and a VH of SEQ ID NO: 79; or
a VL of SEQ ID NO: 49 and a VH of SEQ ID NO: 81.
4. The monoclonal antibody of any of claims 1-3, which is an internalizing antibody. 5. The monoclonal antibody of any of claims 1-4, which is a chimeric, CDR grafted, humanized or human antibody, or an immunoreactive fragment thereof.
6. The monoclonal antibody of any of claims 1-5 wherein the antibody comprises a light chain variable region (VL) of SEQ ID NO: 101 and a heavy chain variable region (VH) of SEQ ID NO: 103; or a VL of SEQ ID NO: 105 and a VH of SEQ ID NO: 107; or a VL of SEQ ID NO: 109 and a VH of SEQ ID NO: 107; or a VL of SEQ ID NO: 113 and a VH of SEQ ID NO: 115; or a VL of SEQ ID NO: 117 and a VH of SEQ ID NO: 119.
7. The monoclonal antibody of any of claims 1-6 wherein the antibody comprises a light chain of SEQ ID NO: 130 and a heavy chain of SEQ ID NO: 131; or a light chain of SEQ ID NO: 130 and a heavy chain of SEQ ID NO: 133; or a light chain of SEQ ID NO: 130 and a heavy chain of SEQ ID NO: 135; or a light chain of SEQ ID NO: 136 and a heavy chain of SEQ ID NO: 137; or a light chain of SEQ ID NO: 136 and a heavy chain of SEQ ID NO: 139; or a light chain of SEQ ID NO: 136 and a heavy chain of SEQ ID NO: 141; or a light chain of SEQ ID NO: 142 and a heavy chain of SEQ ID NO: 137; or a light chain of SEQ ID NO: 142 and a heavy chain of SEQ ID NO: 139; or a light chain of SEQ ID NO: 144 and a heavy chain of SEQ ID NO: 145; or a light chain of SEQ ID NO: 144 and a heavy chain of SEQ ID NO: 147; or a light chain of SEQ ID NO: 144 and a heavy chain of SEQ ID NO: 149; or a light chain of SEQ ID NO: 150 and a heavy chain of SEQ ID NO: 151; or a light chain of SEQ ID NO: 150 and a heavy chain of SEQ ID NO: 153.
8. The monoclonal antibody of any of claims 1-6 wherein the antibody comprises a site- specific antibody.
9. The antibody of any one of claims 1-8, wherein the antibody is conjugated to a payload. 10. A pharmaceutical composition comprising an antibody of any one of claims 1 - 8.
11. A nucleic acid encoding all or part of an antibody of any one of claims 1 - 8.
12. A vector comprising the nucleic acid of claim 11.
13. A host cell comprising the nucleic acid of claim 11 or the vector of claim 12.
14. An antibody drug conjugate (ADC), or a pharmaceutically acceptable salt thereof, comprising a monoclonal antibody conjugated, linked or otherwise associated with a cytotoxic agent, wherein the monoclonal antibody binds to a human KREMEN2 protein.
15. The ADC of claim 14 comprising the formula Ab-[L-D]n wherein:
a) Ab comprises the anti-KREMEN2 antibody;
b) L comprises an optional linker;
c) D comprises a drug, which is the cytotoxic agent; and
d) n is an integer from about 1 to about 20.
16. The ADC of claim 14 or 15, wherein the anti-KREMEN2 antibody comprises a chimeric, CDR grafted, humanized or human antibody or an immunoreactive fragment thereof.
17. The ADC of any one of claims 14-16 wherein Ab is the anti-KREMEN2 antibody of any one of claims 1-8.
18. The ADC of any one of claims 15-17, wherein drug loading is from about 2 to about 8.
19. The ADC of any one of claims 14-18 wherein the cytotoxic agent comprises a compound selected from the group consisting of auristatins, maytansinoids, pyrrolobenzodiazepines (PBDs), benzodiazepine derivatives, calicheamicin and amanitins.
20. An ADC of the formula Ab-[L-D]n comprising a structure selected from the group consisting of:
Figure imgf000169_0001
Figure imgf000169_0002
Figure imgf000169_0003
167
Figure imgf000170_0001
Figure imgf000170_0002
Figure imgf000170_0003
ADC 6 wherein Ab comprises an anti-KREMEN2 antibody or immunoreactive fragment thereof and n is an integer from about 1 to about 8.
21. The ADC of claim 20 wherein anti -KREMEN2 antibody comprises hSC78.43sslMJ (SEQ ID NOS: 136 and 141). 22. The ADC of claim 20 wherein anti-KREMEN2 antibody comprises hSC78.56sslMJ
(SEQ ID NOS: 144 and 149). -[L-D]n comprising the structure:
Figure imgf000171_0001
wherein Ab comprises hSC78.43sslMJ (SEQ ID NOS: 136 and 141) and
24. A pharmaceutical composition comprising an ADC of any one of claims 14 to 23.
25. A method of treating cancer comprising administering a pharmaceutical composition of claim 10 or claim 24 to a subject in need thereof.
26. The method of claim 25 wherein the cancer comprises a solid tumor.
27. The method of any one of claim 25 or 26 wherein the cancer is selected from the group consisting of adrenal cancer, liver cancer, kidney cancer, bladder cancer, breast cancer, gastric cancer, ovarian cancer, cervical cancer, uterine cancer, esophageal cancer, colorectal cancer, prostate cancer, melanoma, pancreatic cancer, lung cancer (both small cell and non-small cell), thyroid cancer and glioblastoma.
28. The method of claim 27, wherein the cancer is non-small cell lung cancer and the non- small cell cancer comprises squamous cell lung carcinoma.
29. The method of claim 27 wherein the cancer is breast cancer and the breast cancer is luminal B breast cancer.
30. A method of reducing tumor initiating cells in a tumor cell population, wherein the method comprises contacting a tumor cell population comprising tumor initiating cells and tumor cells other than tumor initiating cells, with an ADC of any one of claims 14 - 23 or the pharmaceutical composition of claim 10 or 24, whereby the frequency of tumor initiating cells is reduced.
31. A method of delivering a cytotoxin to a cell comprising contacting the cell with an ADC of any one of claims 14 to 23 or the pharmaceutical composition of claim 10 or 24.
32. A method of detecting, diagnosing, or monitoring cancer in a subject, the method comprising the steps of (a) contacting tumor cells with an antibody of any one of claims 1 - 9; and (b) detecting the antibody on the tumor cells.
33. A method of producing an ADC of any one of claims 14-23 comprising the step of conjugating an anti-KREMEN2 antibody (Ab) with a drug (D).
34. A kit comprising:
one or more containers containing a pharmaceutical composition of claim 10 or 24, or the ADC of any one of claims 14-23; and
a label or package insert associated with the one or more containers indicating that the composition or ADC is for treating a subject having cancer.
35. A kit comprising:
one or more containers containing a pharmaceutical composition of claim 10 or 24, or the ADC of any one of claims 14-23; and a label or package insert associated with one or more containers indicating a dosage regimen for a subject having cancer.
36. The kit of claim 34 or claim 35 wherein the cancer is lung cancer.
37. A kit comprising:
one or more containers containing a pharmaceutical composition of claim 10 or 24, or the ADC of any one of claims 14-23; and
a label or package insert associated with the one or more containers indicating that the composition or ADC is for delivery of a cytotoxin to a cell.
38. A method of determining cytotoxicity of an anti-KREMEN2 antibody drug conjugate, or a pharmaceutically acceptable salt thereof, comprising the steps of:
(a) contacting a cancer cell with the antibody drug conjugate, wherein the antibody drug conjugate comprises an anti-KREMEN2 antibody conjugated, linked or otherwise associated with a cytotoxic agent and
(b) determining killing of the cancer cell.
39. The method of claim 38, wherein the antibody drug conjugate is the antibody drug conjugate of any one of claims 14-23.
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