WO2022256498A1 - Protéines trispécifiques ciblant la msln et méthodes d'utilisation - Google Patents

Protéines trispécifiques ciblant la msln et méthodes d'utilisation Download PDF

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WO2022256498A1
WO2022256498A1 PCT/US2022/031916 US2022031916W WO2022256498A1 WO 2022256498 A1 WO2022256498 A1 WO 2022256498A1 US 2022031916 W US2022031916 W US 2022031916W WO 2022256498 A1 WO2022256498 A1 WO 2022256498A1
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dose
msln
administered
weeks
domain
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WO2022256498A9 (fr
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Holger Wesche
Che-Leung Law
Vaishnavi GANTI
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Harpoon Therapeutics, Inc.
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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
    • A61P35/00—Antineoplastic agents
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
    • A61P35/00—Antineoplastic agents
    • A61P35/02—Antineoplastic agents specific for leukemia
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
    • A61P35/00—Antineoplastic agents
    • A61P35/04—Antineoplastic agents specific for metastasis
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
    • A61P37/00—Drugs for immunological or allergic disorders
    • A61P37/02—Immunomodulators
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
    • A61P37/00—Drugs for immunological or allergic disorders
    • A61P37/02—Immunomodulators
    • A61P37/04—Immunostimulants
    • 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
    • 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
    • C07K16/2803—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans against receptors, cell surface antigens or cell surface determinants against the immunoglobulin superfamily
    • C07K16/2809—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans against receptors, cell surface antigens or cell surface determinants against the immunoglobulin superfamily against the T-cell receptor (TcR)-CD3 complex
    • 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
    • C07K16/30—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans against receptors, cell surface antigens or cell surface determinants from tumour 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
    • 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
    • A61K2039/545—Medicinal preparations containing antigens or antibodies characterised by the dose, timing or administration schedule
    • 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
    • C07K2317/31—Immunoglobulins specific features characterized by aspects of specificity or valency multispecific
    • 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
    • C07K2317/56—Immunoglobulins specific features characterized by immunoglobulin fragments variable (Fv) region, i.e. VH and/or VL
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2317/00—Immunoglobulins specific features
    • C07K2317/50—Immunoglobulins specific features characterized by immunoglobulin fragments
    • C07K2317/56—Immunoglobulins specific features characterized by immunoglobulin fragments variable (Fv) region, i.e. VH and/or VL
    • C07K2317/569—Single domain, e.g. dAb, sdAb, VHH, VNAR or nanobody®
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2317/00—Immunoglobulins specific features
    • C07K2317/60—Immunoglobulins specific features characterized by non-natural combinations of immunoglobulin fragments
    • C07K2317/62—Immunoglobulins specific features characterized by non-natural combinations of immunoglobulin fragments comprising only variable region components
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2317/00—Immunoglobulins specific features
    • C07K2317/60—Immunoglobulins specific features characterized by non-natural combinations of immunoglobulin fragments
    • C07K2317/62—Immunoglobulins specific features characterized by non-natural combinations of immunoglobulin fragments comprising only variable region components
    • C07K2317/622—Single chain antibody (scFv)
    • 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
    • C07K2317/73—Inducing cell death, e.g. apoptosis, necrosis or inhibition of cell proliferation
    • 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
    • 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

  • NK natural killer
  • CTLs cytotoxic T lymphocytes
  • MSLN Mesothelin
  • MSLN is a GPI-linked membrane bound tumor antigen MSLN is overexpressed ovarian, pancreatic, lung and triple-negative breast cancers and mesothelioma. Normal tissue expression of MSLN is restricted to single-cell, mesothelial layers lining the pleural, pericardial, and peritoneal cavities. Overexpression of MSLN is associated with poor prognosis in lung adenocarcinoma and triple-negative breast cancer. MSLN has been used as cancer antigen for numerous modalities, including immunotoxins, vaccines, antibody drug conjugates and CAR-T cells. Early signs of clinical efficacy have validated MSLN as a target, but therapies with improved efficacy are needed to treat MSLN-expressing cancers.
  • a method of treating cancer comprising administration of an effective amount of a mesothelin (MSLN) targeting trispecific protein to a subject, wherein said protein comprises (a) a first domain (A) which specifically binds to human CD3; (b) a second domain (B) which is a half-life extension domain; and (c) a third domain (C) which specifically binds to MSLN, wherein the domains are linked in the order H2N-(C)-(B)-(A)- COOH, or by linkers LI and L2, and wherein the MSLN targeting trispecific protein is administered at a dosage of about 1 ng/kg to about 10 mg/kg.
  • MSLN mesothelin
  • the MSLN targeting trispecific protein is administered at a dosage of about 1 ng/kg to about 100,000 ng/kg. In some embodiments, the MSLN targeting trispecific protein is administered at a dosage of about 1 ng/kg to about 50,000 ng/kg. In some embodiments, the MSLN targeting trispecific protein is administered at a dosage of about 1 ng/kg to about 20,000 ng/kg. In some embodiments, the MSLN targeting trispecific protein is administered at a dosage of about 1 ng/kg to about 5,000 ng/kg. In some embodiments, the MSLN targeting trispecific protein is administered at a dosage of about 6 ng/kg to about 14,400 ng/kg.
  • the MSLN targeting trispecific protein is administered once a week. In some embodiments, the MSLN targeting trispecific protein is administered twice per week. In some embodiments, the MSLN targeting trispecific protein is administered every other week. In some embodiments, the MSLN targeting trispecific protein is administered every three weeks. In some embodiments, the MSLN targeting trispecific protein is administered intravenously, intraperitoneally, subcutaneously, intramuscularly, topically or intradermally.
  • Described herein is a method of treating cancer, the method comprising administration of an effective amount of a MSLN targeting trispecific protein to a subject, wherein said protein comprises (a) a first domain (A) which specifically binds to human CD3; (b) a second domain (B) which is a half-life extension domain; and (c) a third domain (C) which specifically binds to MSLN, wherein the domains are linked in the order H2N-(A)-(B)-(C)-COOH, or by linkers LI and L2, and wherein the MSLN targeting trispecific protein is administered according to a schedule comprising the following steps: (i) administration of a first dose of the MSLN targeting trispecific protein, and (ii) administration of a second dose of the MSLN targeting trispecific protein, wherein the second dose is higher than the first dose.
  • a schedule comprising the following steps: (i) administration of a first dose of the MSLN targeting trispecific protein, and (ii) administration of
  • the first dose is about 10 ng/kg to about 5000 ng/kg. In some embodiments, the first dose is about 10 ng/kg to about 2000 ng/kg. In some embodiments, the first dose is about 10 ng/kg to about 1000 ng/kg. In some embodiments, the first dose is about 10 ng/kg to about 500 ng/kg. In some embodiments, the first dose is about 10 ng/kg to about 300 ng/kg. In some embodiments, the first dose is about 200 ng/kg. In some embodiments, the first dose is about 500 ng/kg. In some embodiments, the first dose is administered for about 1 week to about 36 weeks. In some embodiments, the first dose is administered for about 1 week to about 27 weeks.
  • the first dose is administered for about 1 week to about 18 weeks. In some embodiments, the first dose is administered for about 1 week to about 9 weeks. In some embodiments, the first dose is administered once a day. In some embodiments, the first dose is administered twice a day. In some embodiments, the first dose is administered three times a day. In some embodiments, the first dose is administered five times a day. In some embodiments, the first dose is administered once a week. In some embodiments, the first dose is administered twice per week. In some embodiments, the first dose is administered every other week. In some embodiments, the first dose is administered every three weeks. In some embodiments, the first dose is administered intravenously, intraperitoneally, subcutaneously, intramuscularly, topically or intradermally.
  • the second dose is about 10 ng/kg to about 100,000 ng/kg. In some embodiments, the second dose is about 100 ng/kg to about 100,000 ng/kg. In some embodiments, the second dose is about 100 ng/kg to about 50,000 ng/kg. In some embodiments, the second dose is about 10 ng/kg to about 50,000 ng/kg. In some embodiments, the second dose is about 10 ng/kg to about 10,000 ng/kg. In some embodiments, the second dose is about 100 ng/kg to about 10,000 ng/kg. In some embodiments, the second dose is about 900 ng/kg. In some embodiments, the second dose is about 1200 ng/kg.
  • the second dose is about 1800 ng/kg. In some embodiments, the second dose is about 3600 ng/kg. In some embodiments, the second dose is about 7200 ng/kg. In some embodiments, the second dose is about 14400 ng/kg. In some embodiments, the second dose is administered for about 1 week to about 36 weeks. In some embodiments, the second dose is administered for about 1 week to about 27 weeks. In some embodiments, the second dose is administered for about 1 week to about 18 weeks. In some embodiments, the second dose is administered for about 1 week to about 9 weeks. In some embodiments, the second dose is administered once a day. In some embodiments, the second dose is administered twice a day. In some embodiments, the second dose is administered three times a day.
  • the second dose is administered five times a day. In some embodiments, the second dose is administered once a week. In some embodiments, the second dose is administered twice per week. In some embodiments, the second dose is administered every other week. In some embodiments, the second dose is administered every three weeks. In some embodiments, the second dose is maintained to the end of the schedule after the administration of the first dose. In some embodiments, the second dose is administered intravenously, intraperitoneally, subcutaneously, intramuscularly, topically or intradermally.
  • the schedule further comprises: (iii) administration of a third dose of the MSLN targeting trispecific protein, wherein the third dose is higher than the second dose.
  • the third dose is about 10 ng/kg to about 100,000 ng/kg. In some embodiments, the third dose is about 100 ng/kg to about 100,000 ng/kg. In some embodiments, the third dose is about 100 ng/kg to about 50,000 ng/kg. In some embodiments, the third dose is about 10 ng/kg to about 50,000 ng/kg. In some embodiments, the third dose is about 10 ng/kg to about 10,000 ng/kg. In some embodiments, the third dose is about 100 ng/kg to about 10,000 ng/kg.
  • the third dose is about 900 ng/kg. In some embodiments, the third dose is about 1200 ng/kg. In some embodiments, the third dose is about 1800 ng/kg. In some embodiments, the third dose is about 3600 ng/kg. In some embodiments, the third dose is about 7200 ng/kg. In some embodiments, the third dose is about 14400 ng/kg. In some embodiments, the third dose is administered for about 1 week to about 36 weeks. In some embodiments, the third dose is administered for about 1 week to about 27 weeks. In some embodiments, the third dose is administered for about 1 week to about 18 weeks. In some embodiments, the third dose is administered for about 1 week to about 9 weeks. In some embodiments, the third dose is administered once a day.
  • the third dose is administered twice a day. In some embodiments, the third dose is administered three times a day. In some embodiments, the third dose is administered five times a day. In some embodiments, the third dose is administered once a week. In some embodiments, the third dose is administered twice per week. In some embodiments, the third dose is administered every other week. In some embodiments, the third dose is administered every three weeks. In some embodiments, the third dose is maintained to the end of the schedule after the administration of the second dose. In some embodiments, the third dose is administered intravenously, intraperitoneally, subcutaneously, intramuscularly, topically or intradermally.
  • the MSLN targeting trispecific protein has an elimination half time of at least 12 hours, at least 20 hours, at least 25 hours, at least 30 hours, at least 35 hours, at least 40 hours, at least 45 hours, at least 50 hours, or at least 100 hours.
  • the third domain comprises a VHH domain.
  • the VHH domain is human, humanized, affinity matured, or a combination thereof.
  • the third domain comprises one or more sequences selected from the group consisting of SEQ ID NO: 1-40 and 102-105.
  • the first domain comprises a variable light chain and variable heavy chain each of which is capable of specifically binding to human CD3.
  • the first domain is humanized or human.
  • the second domain binds human serum albumin.
  • the second domain comprises a scFv, a VHH domain, a variable heavy domain (VH), a variable light domain (VL), a peptide, a ligand, or a small molecule.
  • linkers LI and L2 are each independently selected from (GS) n (SEQ ID NO: 87), (GGS) n (SEQ ID NO: 88), (GGGS) n (SEQ ID NO: 89), (GGSG) n (SEQ ID NO: 90), (GGSGG) n (SEQ ID NO: 91), (GGGGS) n (SEQ ID NO: 92), or GGGGSGGGS (SEQ ID NO: 380), wherein n is 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10.
  • linkers LI and L2 are each independently (GGGGS) 4 (SEQ ID NO: 95), (GGGGS) 3 (SEQ ID NO: 96) or GGGGSGGGS (SEQ ID NO: 380).
  • the domains are linked in the order H 2 N-(C)-Ll-(B)-L2-(A)-COOH.
  • the MSLN targeting trispecific protein is less than about 80 kDa. In some embodiments, the MSLN targeting trispecific protein is about 50 to about 75 kDa. In some embodiments, the MSLN targeting trispecific protein is less than about 60 kDa.
  • the MSLN targeting trispecific protein comprises a sequence selected from the group consisting of SEQ ID NO: 58-86 and 98-101. In some embodiments, the MSLN targeting trispecific protein comprises a sequence as set forth in SEQ ID NO: 98.
  • the cancer is a tumorous disease, an autoimmune disease or an infection disease associated with MSLN. In some embodiments, the tumorous disease comprises a solid tumor disease. In some embodiments, the solid tumor disease comprises mesothelioma, lung cancer, gastric cancer, ovarian cancer, or triple negative breast cancer.
  • FIG. 1 is schematic representation of an exemplary MSLN targeting trispecific antigen-binding protein where the protein has an constant core element comprising an anti-CD3e single chain variable fragment (scFv) and an anti-ALB variable heavy chain region; and an anti- MSLN binding domain that can be a VHH, a VH, scFv, a non-Ig binder, or a ligand.
  • scFv single chain variable fragment
  • ALB variable heavy chain region an anti- MSLN binding domain that can be a VHH, a VH, scFv, a non-Ig binder, or a ligand.
  • Figure 2 illustrates the effectivity of exemplary TriTAC molecules (2A2 and 2A4) in killing of OVCAR8 cells that expresses the target protein MSLN.
  • FIG. 3 illustrates that an exemplary TriTAC molecule of this disclosure (MH6T TriTAC) was able to direct T cells from five donors (donor 02; donor 86; donor 41; donor 81; and donor 35) to kill Caov3 cells.
  • the figure also illustrates that a control TriTAC molecule (GFP TriTAC) was not able to direct T cells from the five donors (donor 02; donor 86; donor 41; donor 81; and donor 35) to kill Caov3 cells.
  • FIG. 4 illustrates that an exemplary TriTAC molecule of this disclosure (MH6T TriTAC) was able to direct T cells from five donors (donor 02; donor 86; donor 41; donor 81; and donor 35) to kill OVCAR3 cells.
  • the figure also illustrates that a control TriTAC molecule (GFP TriTAC) was not able to direct T cells from the five donors (donor 02; donor 86; donor 41; donor 81; and donor 35) to kill OVCAR3 cells.
  • FIG. 5 illustrates that an exemplary TriTAC molecule of this disclosure (MH6T TriTAC) was able to direct T cells from a healthy donor to kill cells that express MSLN (OVCAR3 cells; Caov4 cells; OVCAR3 cells; and OVCAR8 cells).
  • the figure also illustrates that the MH6T TriTAC was not able to direct T cells from the healthy donor to kill cells that do not express MSLN (MDAPCa2b cells; and NCI-H510A cells).
  • FIG. 6 illustrates that an exemplary TriTAC molecule of this disclosure (MH6T TriTAC) was able to direct T cells from cynomolgus monkeys to kill human ovarian cancer cell line (OVCAR3 cells; Caov3 cells).
  • the figure also illustrates that a control TriTAC molecule (GFP TriTAC) was not able to direct the T cells from cynomolgus monkeys to kill human ovarian cancer cells lines (OVCAR3 cells; Caov3 cells).
  • FIG. 7 illustrates that an exemplary TriTAC molecule of this disclosure (MH6T TriTAC) was able to direct killing of MSLN expressing NCI-H2052 mesothelioma cells by T cells, in the presence or absence of human serum albumin (HSA).
  • HSA human serum albumin
  • FIG. 8 illustrates that an exemplary TriTAC molecule of this disclosure (MH6T TriTAC) was able to activate T cells from four healthy donors (donor 2; donor 86; donor 35; and donor 81), as demonstrated by secretion of TNF-a from the T cells, in presence of the MH6T TriTAC and MSLN-expressing Caov4 cells.
  • MH6T TriTAC TriTAC
  • FIG. 9 illustrates that an exemplary TriTAC molecule of this disclosure (MH6T TriTAC) was able to activate T cells from four healthy donors (donor 2; donor 86; donor 35; and donor 81), as demonstrated by activation of CD69 expression on the T cells, in presence of the MH6T TriTAC and MSLN-expressing OVCAR8 cells.
  • MH6T TriTAC TriTAC
  • Figure 10 illustrates binding of an exemplary TriTAC molecule of this disclosure (MH6T TriTAC) to MSLN expressing cell lines or MSLN non-expressing cell lines.
  • Figure 10A shows binding of the MH6T TriTAC with MSLN expressing cells (Caov3 cells-top left panel; Caov4 cells-top right panel; OVCAR3 cells-bottom left panel; OVCAR8 cells- bottom right panel);
  • Figure 10A further illustrates lack of binding of a control TriTAC (GFP TriTAC) to the same cell lines.
  • Figure 10B shows lack of binding of both the MH6T TriTAC and the GFP TriTAC to MSLN non-expressing cell lines (MDCA2b cells-left panel; NCI-H510A cells- right panel).
  • FIG 11 illustrates binding of an exemplary TriTAC molecule of this disclosure (MH6T TriTAC) to T cells from four healthy donors (donor 2-top left panel; donor 35-top right panel; donor 41-bottom left panel; donor 81-bottom right panel).
  • FIG. 12 illustrates that an exemplary TriTAC molecule of this disclosure (MH6T TriTAC) was able to inhibit tumor growth in NCG mice implanted with MSLN expressing NCI- H292 cells.
  • Figure 13 illustrates pharmacokinetic profile of an exemplary TriTAC molecule of this disclosure, MH6T TriTAC. Serum levels of the MH6T TriTAC molecule, at various time points following injection into two cynomolgus monkeys, are shown in the plot.
  • Figure 14 shows results from binding affinity measurements of two exemplary trispecific molecules of this disclosure, TriTAC 74 and TriTAC 75, and EC50 values for killing of SKOV3 and OVCAR cells by the two TriTAC molecules.
  • FIG. 15 illustrates pharmacokinetic profiles of two exemplary TriTAC molecules of this disclosure, TriTAC 75 and TriTAC 74. Serum levels of the TriTAC molecules, at various time points following injection into cynomolgus monkeys, are shown in the plot.
  • Figure 16 illustrates MSLN trispecific antigen-binding protein Phase l/2a trial design.
  • Figure 17 illustrates patients time on treatment from clinical database for platinum relapsed/refractory ovarian cancer.
  • Figure 18 illustrates percent change of target lesion after MSLN trispecific antigen binding protein treatment. Target lesion reductions were observed.
  • Figure 19 illustrates the pharmacokinetic data of the MSLN trispecific antigen-binding protein for the different dosing cohorts.
  • Figure 19A illustrates the Mean (SD) Cmax.
  • Figure 19B illustrates the Mean (SD) AUClast.
  • MSLN mesothelin
  • nucleic acids recombinant expression vectors and host cells for making such proteins thereof.
  • methods of using the disclosed MSLN targeting trispecific proteins in the prevention, and/or treatment of diseases, conditions and disorders are capable of specifically binding to MSLN as well as CD3 and have a half-life extension domain, such as a domain binding to human albumin (ALB).
  • ALB domain binding to human albumin
  • Figure 1 depicts one non-limiting example of a trispecific MSLN-binding protein.
  • the MSLN targeting trispecific proteins comprise a domain (A) which specifically binds to CD3, a domain (B) which specifically binds to human albumin (ALB), and a domain (C) which specifically binds to MSLN.
  • the three domains in MSLN targeting trispecific proteins are arranged in any order.
  • the domain order of the MSLN targeting trispecific proteins are:
  • the MSLN targeting trispecific proteins have a domain order of H2N-(A)-(B)-(C)-COOH. In some embodiments, the MSLN targeting trispecific proteins have a domain order of H2N-(A)-(C)-(B)-COOH. In some embodiments, the MSLN targeting trispecific proteins have a domain order of H2N-(B)-(A)-(C)-COOH.
  • the MSLN targeting trispecific proteins have a domain order of H2N-(B)-(C)-(A)-COOH. In some embodiments, the MSLN targeting trispecific proteins have a domain order of H2N-(C)-(B)-(A)- COOH. In some embodiments, the MSLN targeting trispecific proteins have a domain order of H 2 N-(C)-(A)-(B)-COOH.
  • the MSLN targeting trispecific proteins have the HSA binding domain as the middle domain, such that the domain order is H2N-(A)-(B)-(C)-COOH or ELN- (C)-(B)-(A)-COOH. It is contemplated that in such embodiments where the ALB binding domain as the middle domain, the CD3 and MSLN binding domains are afforded additional flexibility to bind to their respective targets.
  • the MSLN targeting trispecific proteins described herein comprise a polypeptide having a sequence described in Table 1 (SEQ ID NO: 58-86, 98, 100, and 101) and subsequences thereof.
  • the trispecific antigen binding protein comprises a polypeptide having at least 70%-95% or more homology to a sequence described in Table 1 (SEQ ID NO: 58-86, 98, 100 and 101).
  • the trispecific antigen binding protein comprises a polypeptide having at least 70%, 75%, 80%,
  • the MSLN targeting trispecific proteins described herein are designed to allow specific targeting of cells expressing MSLN by recruiting cytotoxic T cells. This improves efficacy compared to ADCC (antibody dependent cell-mediated cytotoxicity), which is using full length antibodies directed to a sole antigen and is not capable of directly recruiting cytotoxic T cells.
  • ADCC antibody dependent cell-mediated cytotoxicity
  • the MSLN targeting trispecific proteins can crosslink cytotoxic T cells with cells expressing MSLN in a highly specific fashion, thereby directing the cytotoxic potential of the T cell towards the target cell.
  • the MSLN targeting trispecific proteins described herein engage cytotoxic T cells via binding to the surface-expressed CD3 proteins, which form part of the TCR. Simultaneous binding of several MSLN trispecific antigen-binding protein to CD3 and to MSLN expressed on the surface of particular cells causes T cell activation and mediates the subsequent lysis of the particular MSLN expressing cell.
  • MSLN targeting trispecific proteins are contemplated to display strong, specific and efficient target cell killing.
  • the MSLN targeting trispecific proteins described herein stimulate target cell killing by cytotoxic T cells to eliminate pathogenic cells (e.g ., tumor cells expressing MSLN). In some of such embodiments, cells are eliminated selectively, thereby reducing the potential for toxic side effects.
  • the MSLN targeting trispecific proteins described herein confer further therapeutic advantages over traditional monoclonal antibodies and other smaller bispecific molecules. Generally, the effectiveness of recombinant protein pharmaceuticals depends heavily on the intrinsic pharmacokinetics of the protein itself.
  • One such benefit here is that the MSLN targeting trispecific proteins described herein have extended pharmacokinetic elimination half time due to having a half-life extension domain such as a domain specific to HSA.
  • the MSLN targeting trispecific proteins described herein have an extended serum elimination half-time of about two, three, about five, about seven, about 10, about 12, or about 14 days in some embodiments. This contrasts to other binding proteins such as BiTE or DART molecules which have relatively much shorter elimination half-times.
  • the BiTE CD19xCD3 bispecific scFv-scFv fusion molecule requires continuous intravenous infusion (i.v.) drug delivery due to its short elimination half-time.
  • the longer intrinsic half-times of the MSLN targeting trispecific proteins solve this issue thereby allowing for increased therapeutic potential such as low-dose pharmaceutical formulations, decreased periodic administration and/or novel pharmaceutical compositions.
  • the MSLN targeting trispecific proteins described herein also have an optimal size for enhanced tissue penetration and tissue distribution. Larger sizes limit or prevent penetration or distribution of the protein in the target tissues.
  • the MSLN targeting trispecific proteins described herein avoid this by having a small size that allows enhanced tissue penetration and distribution. Accordingly, the MSLN targeting trispecific proteins described herein, in some embodiments have a size of about 50 kD to about 80 kD, about 50 kD to about 75 kD, about 50 kD to about 70 kD, or about 50 kD to about 65 kD.
  • the size of the MSLN targeting trispecific proteins is advantageous over IgG antibodies which are about 150 kD and the BiTE and DART diabody molecules which are about 55 kD but are not half-life extended and therefore cleared quickly through the kidney.
  • the MSLN targeting trispecific proteins described herein have an optimal size for enhanced tissue penetration and distribution.
  • the MSLN targeting trispecific proteins are constructed to be as small as possible, while retaining specificity toward its targets. Accordingly, in these embodiments, the MSLN targeting trispecific proteins described herein have a size of about 20 kD to about 40 kD or about 25 kD to about 35 kD to about 40 kD, to about 45 kD, to about 50 kD, to about 55 kD, to about 60 kD, to about 65 kD.
  • the MSLN targeting trispecific proteins described herein have a size of about 50kD, 49, kD, 48 kD, 47 kD, 46 kD, 45 kD, 44 kD, 43 kD, 42 kD, 41 kD, 40 kD, about 39 kD, about 38 kD, about 37 kD, about 36 kD, about 35 kD, about 34 kD, about 33 kD, about 32 kD, about 31 kD, about 30 kD, about 29 kD, about 28 kD, about 27 kD, about 26 kD, about 25 kD, about 24 kD, about 23 kD, about 22 kD, about 21 kD, or about 20 kD.
  • an exemplary approach to the small size is through the use of single domain antibody (sdAb) fragments for each of the domains.
  • sdAb single domain antibody
  • a particular MSLN trispecific antigen-binding protein has an anti-CD3 sdAb, anti-ALB sdAb and an sdAb for MSLN. This reduces the size of the exemplary MSLN trispecific antigen-binding protein to under 60 kD.
  • the domains of the MSLN targeting trispecific proteins are all single domain antibody (sdAb) fragments.
  • the MSLN targeting trispecific proteins described herein comprise small molecule entity (SME) binders for ALB and/or the MSLN.
  • SME small molecule entity
  • SME binders are small molecules averaging about 500 to 2000 Da in size and are attached to the MSLN targeting trispecific proteins by known methods, such as sortase ligation or conjugation.
  • one of the domains of MSLN trispecific antigen-binding protein is a sortase recognition sequence, e.g ., LPETG (SEQ ID NO: 97).
  • the protein is incubated with a sortase and a SME binder whereby the sortase attaches the SME binder to the recognition sequence.
  • Known SME binders include MIP-1072 and MIP-1095 which bind to mesothelin.
  • the domain which binds to MSLN of MSLN targeting trispecific proteins described herein comprise a knottin peptide for binding MSLN.
  • Knottins are disufide- stabilized peptides with a cysteine knot scaffold and have average sizes about 3.5 kD. Knottins have been contemplated for binding to certain tumor molecules such as MSLN.
  • domain which binds to MSLN of MSLN targeting trispecific proteins described herein comprise a natural MSLN ligand.
  • MSLN targeting trispecific proteins described herein are of a single-polypeptide design with flexible linkage of their domains. This allows for facile production and manufacturing of the MSLN targeting trispecific proteins as they can be encoded by single cDNA molecule to be easily incorporated into a vector. Further, because the MSLN targeting trispecific proteins described herein are a monomeric single polypeptide chain, there are no chain pairing issues or a requirement for dimerization. It is contemplated that the MSLN targeting trispecific proteins described herein have a reduced tendency to aggregate unlike other reported molecules such as bispecific proteins with Fc-gamma immunoglobulin domains.
  • the domains are linked by internal linkers LI and L2, where LI links the first and second domain of the MSLN targeting trispecific proteins and L2 links the second and third domains of the MSLN targeting trispecific proteins.
  • Linkers LI and L2 have an optimized length and/or amino acid composition. In some embodiments, linkers LI and L2 are the same length and amino acid composition. In other embodiments, LI and L2 are different.
  • internal linkers LI and/or L2 are "short", z.e., consist of 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12 amino acid residues. Thus, in certain instances, the internal linkers consist of about 12 or less amino acid residues.
  • the internal linker is a peptide bond.
  • internal linkers LI and/or L2 are "long", z.e., consist of 15, 20 or 25 amino acid residues. In some embodiments, these internal linkers consist of about 3 to about 15, for example 8, 9 or 10 contiguous amino acid residues.
  • peptides are selected with properties that confer flexibility to the MSLN targeting trispecific proteins, do not interfere with the binding domains as well as resist cleavage from proteases. For example, glycine and serine residues generally provide protease resistance.
  • Examples of internal linkers suitable for linking the domains in the MSLN targeting trispecific proteins include but are not limited to (GS) n (SEQ ID NO: 87), (GGS) n (SEQ ID NO: 88), (GGGS) n (SEQ ID NO: 89), (GGSG) n (SEQ ID NO: 90), (GGSGG) n (SEQ ID NO: 91), (GGGGS) n (SEQ ID NO: 92), (GGGGG) n (SEQ ID NO: 93), (GGG) n (SEQ ID NO: 94), or GGGGSGGGS (SEQ ID NO: 380), wherein n is 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10.
  • internal linker LI and/or L2 is (GGGGS) 4 (SEQ ID NO: 95) or (GGGGS) 3 (SEQ ID NO: 96).
  • CD3 is a protein complex that includes a CD3y (gamma) chain, a CD35 (delta) chain, and two CD3e (epsilon) chains which are present on the cell surface.
  • CD3 associates with the a (alpha) and b (beta) chains of the TCR as well as CD3 z (zeta) altogether to comprise the complete TCR.
  • Clustering of CD3 on T cells, such as by immobilized anti-CD3 antibodies leads to T cell activation similar to the engagement of the T cell receptor but independent of its clone- typical specificity.
  • the MSLN targeting trispecific proteins described herein comprise a domain which specifically binds to CD3. In one aspect, the MSLN targeting trispecific proteins described herein comprise a domain which specifically binds to human CD3. In some embodiments, the MSLN targeting trispecific proteins described herein comprise a domain which specifically binds to CD3y. In some embodiments, the MSLN targeting trispecific proteins described herein comprise a domain which specifically binds to CD35. In some embodiments, the MSLN targeting trispecific proteins described herein comprise a domain which specifically binds to CD3e. [0044] In further embodiments, the MSLN targeting trispecific proteins described herein comprise a domain which specifically binds to the TCR.
  • the MSLN targeting trispecific proteins described herein comprise a domain which specifically binds the a chain of the TCR. In certain instances, the MSLN targeting trispecific proteins described herein comprise a domain which specifically binds the b chain of the TCR.
  • the CD3 binding domain of the MSLN targeting trispecific proteins described herein exhibit not only potent CD3 binding affinities with human CD3, but show also excellent crossreactivity with the respective cynomolgus monkey CD3 proteins.
  • the CD3 binding domain of the MSLN targeting trispecific proteins are cross reactive with CD3 from cynomolgus monkey.
  • human xynomolgous KD ratios for CD3 are between 5 and 0.2.
  • the CD3 binding domain of the MSLN trispecific antigen-binding protein can be any domain that binds to CD3 including but not limited to domains from a monoclonal antibody, a polyclonal antibody, a recombinant antibody, a human antibody, a humanized antibody.
  • the antigen-binding domain comprises a humanized or human antibody or an antibody fragment, or a murine antibody or antibody fragment.
  • the humanized or human anti-CD3 binding domain comprises one or more (e.g, all three) light chain complementary determining region 1 (LC CDR1), light chain complementary determining region 2 (LC CDR2), and light chain complementary determining region 3 (LC CDR3) of a humanized or human anti- CD3 binding domain described herein, and/or one or more (e.g, all three) heavy chain complementary determining region 1 (HC CDR1), heavy chain complementary determining region 2 (HC CDR2), and heavy chain complementary determining region 3 (HC CDR3) of a humanized or human anti-CD3 binding domain described herein, e.g, a humanized or human anti-CD3 binding domain comprising one or more, e.g, all three, LC CDRs and one or more, e.g, all three, HC CDRs.
  • the humanized or human anti-CD3 binding domain comprises a humanized or human light chain variable region specific to CD3 where the light chain variable region specific to CD3 comprises human or non-human light chain CDRs in a human light chain framework region.
  • the light chain framework region is a l (lamda) light chain framework. In other instances, the light chain framework region is a k (kappa) light chain framework.
  • the humanized or human anti-CD3 binding domain comprises a humanized or human heavy chain variable region specific to CD3 where the heavy chain variable region specific to CD3 comprises human or non-human heavy chain CDRs in a human heavy chain framework region.
  • the complementary determining regions of the heavy chain and/or the light chain are derived from known anti-CD3 antibodies, such as, for example, muromonab- CD3 (OKT3), otelixizumab (TRX4), teplizumab (MGA031), visilizumab (Nuvion), SP34, TR- 66 or X35-3, VIT3, BMA030 (BW264/56), CLB-T3/3, CRIS7, YTH12.5, FI 11-409, CLB- T3.4.2, TR-66, WT32, SPv-T3b, 11D8, XIII-141, XIII-46, XIII-87, 12F6, T3/RW2-8C8, T3/RW2-4B6, OKT3D, M-T301, SMC2, F101.01, UCHT-1 and WT-31.
  • known anti-CD3 antibodies such as, for example, muromonab- CD3 (OKT3), otelixizumab (
  • the anti-CD3 binding domain is a single chain variable fragment (scFv) comprising a light chain and a heavy chain of an amino acid sequence provided herein.
  • scFv single chain variable fragment
  • single chain variable fragment or “scFv” refers to an antibody fragment comprising a variable region of a light chain and at least one antibody fragment comprising a variable region of a heavy chain, wherein the light and heavy chain variable regions are contiguously linked via a short flexible polypeptide linker, and capable of being expressed as a single polypeptide chain, and wherein the scFv retains the specificity of the intact antibody from which it is derived.
  • the anti-CD3 binding domain comprises: a light chain variable region comprising an amino acid sequence having at least one, two or three modifications ( e.g ., substitutions) but not more than 30, 20 or 10 modifications (e.g, substitutions) of an amino acid sequence of a light chain variable region provided herein, or a sequence with 95-99% identity with an amino acid sequence provided herein; and/or a heavy chain variable region comprising an amino acid sequence having at least one, two or three modifications (e.g, substitutions) but not more than 30, 20 or 10 modifications (e.g, substitutions) of an amino acid sequence of a heavy chain variable region provided herein, or a sequence with 95-99% identity to an amino acid sequence provided herein.
  • a light chain variable region comprising an amino acid sequence having at least one, two or three modifications (e.g ., substitutions) but not more than 30, 20 or 10 modifications (e.g, substitutions) of an amino acid sequence of a heavy chain variable region provided herein, or a sequence with 95-99% identity to an amino acid
  • the humanized or human anti-CD3 binding domain is a scFv, and a light chain variable region comprising an amino acid sequence described herein, is attached to a heavy chain variable region comprising an amino acid sequence described herein, via a scFv linker.
  • the light chain variable region and heavy chain variable region of a scFv can be, e.g, in any of the following orientations: light chain variable region- scFv linker-heavy chain variable region or heavy chain variable region- scFv linker-light chain variable region.
  • scFv molecules can be produced by linking VH and VL regions together using flexible polypeptide linkers.
  • the scFv molecules comprise a scFv linker (e.g ., a Ser-Gly linker) with an optimized length and/or amino acid composition.
  • the length of the scFv linker is such that the VH or VL domain can associate intermolecularly with the other variable domain to form the CD3 binding site.
  • such scFv linkers are "short", i.e. consist of 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12 amino acid residues.
  • the scFv linkers consist of about 12 or less amino acid residues. In the case of 0 amino acid residues, the scFv linker is a peptide bond. In some embodiments, these scFv linkers consist of about 3 to about 15, for example 8, 9 or 10 contiguous amino acid residues. Regarding the amino acid composition of the scFv linkers, peptides are selected that confer flexibility, do not interfere with the variable domains as well as allow inter-chain folding to bring the two variable domains together to form a functional CD3 binding site. For example, scFv linkers comprising glycine and serine residues generally provide protease resistance.
  • linkers in a scFv comprise glycine and serine residues.
  • the amino acid sequence of the scFv linkers can be optimized, for example, by phage-display methods to improve the CD3 binding and production yield of the scFv.
  • Examples of peptide scFv linkers suitable for linking a variable light domain and a variable heavy domain in a scFv include but are not limited to (GS) n (SEQ ID NO: 87), (GGS) n (SEQ ID NO: 88), (GGGS) n (SEQ ID NO: 89), (GGSG) n (SEQ ID NO: 90), (GGSGG) n (SEQ ID NO: 91), (GGGGS) n (SEQ ID NO: 92), (GGGGG) n (SEQ ID NO: 93), (GGG) n (SEQ ID NO: 94), or GGGGSGGGS (SEQ ID NO: 380), wherein n is 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10.
  • the scFv linker can be (GGGGS) 4 (SEQ ID NO: 95) or (GGGGS) 3 (SEQ ID NO: 96). Variation in the linker length may retain or enhance activity, giving rise to superior efficacy in activity studies.
  • CD3 binding domain of MSLN trispecific antigen-binding protein has an affinity to CD3 on CD3 expressing cells with a KD of 1000 nM or less, 500 nM or less, 200 nM or less, 100 nM or less, 80 nM or less, 50 nM or less, 20 nM or less, 10 nM or less, 5 nM or less, 1 nM or less, or 0.5 nM or less.
  • the CD3 binding domain of MSLN trispecific antigen-binding protein has an affinity to CD3e, g, or d with a KD of 1000 nM or less, 500 nM or less, 200 nM or less, 100 nM or less, 80 nM or less, 50 nM or less, 20 nM or less, 10 nM or less, 5 nM or less, 1 nM or less, or 0.5 nM or less.
  • CD3 binding domain of MSLN trispecific antigen-binding protein has low affinity to CD3, i.e., about 100 nM or greater.
  • the affinity to bind to CD3 can be determined, for example, by the ability of the MSLN trispecific antigen-binding protein itself or its CD3 binding domain to bind to CD3 coated on an assay plate; displayed on a microbial cell surface; in solution; etc.
  • the binding activity of the MSLN trispecific antigen-binding protein itself or its CD3 binding domain of the present disclosure to CD3 can be assayed by immobilizing the ligand (e.g ., CD3) or the MSLN trispecific antigen-binding protein itself or its CD3 binding domain, to a bead, substrate, cell, etc.
  • Agents can be added in an appropriate buffer and the binding partners incubated for a period of time at a given temperature. After washes to remove unbound material, the bound protein can be released with, for example, SDS, buffers with a high pH, and the like and analyzed, for example, by Surface Plasmon Resonance (SPR).
  • SPR Surface Plasmon Resonance
  • domains which extend the half-life of an antigen-binding domain. Such domains are contemplated to include but are not limited to Albumin binding domains, Fc domains, small molecules, and other half-life extension domains known in the art.
  • Human albumin (ALB) (molecular mass ⁇ 67 kDa) is the most abundant protein in plasma, present at about 50 mg/ml (600 mM), and has a half-life of around 20 days in humans. ALB serves to maintain plasma pH, contributes to colloidal blood pressure, functions as carrier of many metabolites and fatty acids, and serves as a major drug transport protein in plasma.
  • Noncovalent association with albumin extends the elimination half-time of short lived proteins.
  • a recombinant fusion of an albumin binding domain to a Fab fragment resulted in an in vivo clearance of 25- and 58-fold and a half-life extension of 26- and 37-fold when administered intravenously to mice and rabbits respectively as compared to the administration of the Fab fragment alone.
  • insulin is acylated with fatty acids to promote association with albumin
  • a protracted effect was observed when injected subcutaneously in rabbits or pigs.
  • the MSLN targeting trispecific proteins described herein comprise a half- life extension domain, for example a domain which specifically binds to ALB.
  • the ALB binding domain of MSLN trispecific antigen-binding protein can be any domain that binds to ALB including but not limited to domains from a monoclonal antibody, a polyclonal antibody, a recombinant antibody, a human antibody, a humanized antibody.
  • the ALB binding domain is a single chain variable fragments (scFv), single domain antibody such as a heavy chain variable domain (VH), a light chain variable domain (VL) and a variable domain (VHH) of camelid derived single domain antibody, peptide, ligand or small molecule entity specific for HSA.
  • the ALB binding domain is a single-domain antibody.
  • the HSA binding domain is a peptide.
  • the HSA binding domain is a small molecule.
  • the HSA binding domain of MSLN trispecific antigen-binding protein is fairly small and no more than 25 kD, no more than 20 kD, no more than 15 kD, or no more than 10 kD in some embodiments. In certain instances, the ALB binding is 5 kD or less if it is a peptide or small molecule entity.
  • the half-life extension domain of MSLN trispecific antigen-binding protein provides for altered pharmacodynamics and pharmacokinetics of the MSLN trispecific antigen-binding protein itself. As above, the half-life extension domain extends the elimination half-time. The half-life extension domain also alters pharmacodynamic properties including alteration of tissue distribution, penetration, and diffusion of the trispecific antigen-binding protein. In some embodiments, the half-life extension domain provides for improved tissue (including tumor) targeting, tissue distribution, tissue penetration, diffusion within the tissue, and enhanced efficacy as compared with a protein without an half-life extension domain. In one embodiment, therapeutic methods effectively and efficiently utilize a reduced amount of the trispecific antigen-binding protein, resulting in reduced side effects, such as reduced non-tumor cell cytotoxicity.
  • the binding affinity of the half-life extension domain can be selected so as to target a specific elimination half-time in a particular trispecific antigen-binding protein.
  • the half-life extension domain has a high binding affinity.
  • the half-life extension domain has a medium binding affinity.
  • the half-life extension domain has a low or marginal binding affinity.
  • Exemplary binding affinities include KD concentrations at 10 nM or less (high), between 10 nM and 100 nM (medium), and greater than 100 nM (low).
  • binding affinities to ALB are determined by known methods such as Surface Plasmon Resonance (SPR).
  • ALB binding domains described herein comprise a single domain antibody.
  • MSLN Mesothelin
  • mesothelin is a glycoprotein present on the surface of cells of the mesothelial lining of the peritoneal, pleural and pericardial body cavities.
  • the mesothelin gene ( MSLN) encodes a 71 kD precursor protein that is processed to a 40 kD protein termed mesothelin, which is a glycosyl-phosphatidylinositol-anchored glycoprotein present on the cell surface (Chang, et al, Proc Natl Acad Sci USA (1996) 93 : 136-40).
  • the mesothelin cDNA was cloned from a library prepared from the HPC-Y5 cell line (Kojima et al.
  • the cDNA also was cloned using the monoclonal antibody Kl, which recognizes mesotheliomas (Chang and Pastan (1996) Proc. Natl. Acad. Sci. USA 93:136-40).
  • Mesothelin is a differentiation antigen whose expression in normal human tissues is limited to mesothelial cells lining the body cavity, such as the pleura, pericardium and peritoneum. Mesothelin is also highly expressed in several different human cancers, including mesotheliomas, pancreatic adenocarcinomas, ovarian cancers, stomach and lung adenocarcinomas.
  • mesothelin can also be used a marker for diagnosis and prognosis of certain types of cancer because trace amounts of mesothelin can be detected in the blood of some patients with mesothelin-positive cancers (Cristaudo et ak, Clin. Cancer Res. 13:5076-5081, 2007). It has been reported that mesothelin may be released into serum through deletion at its carboxyl terminus or by proteolytic cleavage from its membrane bound form (Hassan et al., Clin. Cancer Res. 10:3937-3942, 2004).
  • mesothelin is an appropriate target for methods of disease prevention or treatment and there is a need for effective antibodies specific for mesothelin.
  • cell surface mature mesothelin comprises three distinct domains, namely Regions I (comprising residues 296-390), II (comprising residues 391-486), and III (comprising residue 487-598).
  • Regions I comprising residues 296-390
  • II comprising residues 391-486
  • III comprising residue 487-598.
  • the first antibodies generated against mesothelin for therapeutic intervention were designed to interfere with the interaction between mesothelin and CA-125.
  • Phage display identified the Fv SS, which was affinity optimized and used to generate a recombinant immunotoxin targeting mesothelin, SS1P.
  • the MORAb-009 antibody amatuximab which also uses SSI, recognizes a non-linear epitope in the amino terminal 64 amino acids of mesothelin, within region I.
  • the SSI Fv was also used to generate chimeric antigen receptor-engineered T cells. Recently, new anti-mesothelin antibodies have been reported that recognize other regions of the mesothelin protein.
  • MSLN targeting trispecific proteins containing binding domains which specifically bind to MSLN on the surface of tumor target cells provides, in certain embodiments, MSLN targeting trispecific proteins containing binding domains which specifically bind to MSLN on the surface of tumor target cells.
  • the binding domain to MSLN can be any type of binding domain, including but not limited to, domains from a monoclonal antibody, a polyclonal antibody, a recombinant antibody, a human antibody, a humanized antibody.
  • the binding domain to MSLN is a single chain variable fragments (scFv), single domain antibody such as a heavy chain variable domain (VH), a light chain variable domain (VL) and a variable domain (VHH) of camelid derived single domain antibody.
  • the binding domain to MSLN is a non-Ig binding domain, i.e., antibody mimetic, such as anticalins, affilins, affibody molecules, affimers, affitins, alphabodies, avimers, DARPins, fynomers, kunitz domain peptides, and monobodies.
  • the binding domain to MSLN is a ligand or peptide that binds to or associates with MSLN.
  • the binding domain to MSLN is a knottin.
  • the binding domain to MSLN is a small molecular entity.
  • the MSLN binding domain binds to a protein comprising the sequence of SEQ ID NO: 57. In some embodiments, the MSLN binding domain binds to a protein comprising a truncated sequence compared to SEQ ID NO: 57.
  • the MSLN binding domains disclosed herein recognize full- length mesothelin. In certain instances, the MSLN binding domains disclosed herein recognize an epitope in region I (comprising amino acid residues 296-390 of SEQ ID NO: 57), region II (comprising amino acid residue 391-486 of SEQ ID NO: 57), or region III (comprising amino acid residues 487-598 of SEQ ID NO: 57) of mesothelin. It is contemplated that the MSLN binding domains of the present disclosure may, in some embodiments, recognize and bind to epitopes that are located outside regions I, II, or III of mesothelin. In yet other embodiments are disclosed MSLN binding domains that recognize and bind to an epitope different than the MORAb-009 antibody.
  • the MSLN binding domain is an anti-MSLN antibody or an antibody variant.
  • antibody variant refers to variants and derivatives of an antibody described herein.
  • amino acid sequence variants of the anti- MSLN antibodies described herein are contemplated.
  • amino acid sequence variants of anti-MSLN antibodies described herein are contemplated to improve the binding affinity and/or other biological properties of the antibodies.
  • Exemplary method for preparing amino acid variants include, but are not limited to, introducing appropriate modifications into the nucleotide sequence encoding the antibody, or by peptide synthesis. Such modifications include, for example, deletions from, and/or insertions into and/or substitutions of residues within the amino acid sequences of the antibody.
  • any combination of deletion, insertion, and substitution can be made to arrive at the final construct, provided that the final construct possesses the desired characteristics, e.g ., antigen binding.
  • antibody variants having one or more amino acid substitutions are provided. Sites of interest for substitution mutagenesis include the CDRs and framework regions. Examples of such substitutions are described below. Amino acid substitutions may be introduced into an antibody of interest and the products screened for a desired activity, e.g. , retained/improved antigen binding, decreased immunogenicity, or improved T-cell mediated cytotoxicity (TDCC). Both conservative and non-conservative amino acid substitutions are contemplated for preparing the antibody variants.
  • TDCC T-cell mediated cytotoxicity
  • variant anti-MSLN antibody In another example of a substitution to create a variant anti-MSLN antibody, one or more hypervariable region residues of a parent antibody are substituted. In general, variants are then selected based on improvements in desired properties compared to a parent antibody, for example, increased affinity, reduced affinity, reduced immunogenicity, increased pH dependence of binding.
  • the MSLN binding domain of the MSLN targeting trispecific protein is a single domain antibody such as a heavy chain variable domain (VH), a variable domain (VHH) of a llama derived sdAb, a peptide, a ligand or a small molecule entity specific for mesothelin.
  • the mesothelin binding domain of the MSLN targeting trispecific protein described herein is any domain that binds to mesothelin including but not limited to domains from a monoclonal antibody, a polyclonal antibody, a recombinant antibody, a human antibody, a humanized antibody.
  • the MSLN binding domain is a single-domain antibody.
  • the MSLN binding domain is a peptide.
  • the MSLN binding domain is a small molecule.
  • Single domain antibody as used herein in its broadest sense is not limited to a specific biological source or to a specific method of preparation.
  • Single domain antibodies are antibodies whose complementary determining regions are part of a single domain polypeptide. Examples include, but are not limited to, heavy chain antibodies, antibodies naturally devoid of light chains, single domain antibodies derived from conventional 4-chain antibodies, engineered antibodies and single domain scaffolds other than those derived from antibodies.
  • Single domain antibodies may be any of the art, or any future single domain antibodies.
  • Single domain antibodies may be derived from any species including, but not limited to mouse, human, camel, llama, goat, rabbit, bovine.
  • the single domain antibodies of the disclosure are obtained: (1) by isolating the VHH domain of a naturally occurring heavy chain antibody; (2) by expression of a nucleotide sequence encoding a naturally occurring VHH domain; (3) by "humanization” of a naturally occurring VHH domain or by expression of a nucleic acid encoding a such humanized VHH domain; (4) by "camelization” of a naturally occurring VH domain from any animal species, and in particular from a species of mammal, such as from a human being, or by expression of a nucleic acid encoding such a camelized VH domain; (5) by "camelisation” of a "domain antibody” or “Dab", or by expression of a nucleic acid encoding such a camelized VH domain; (6) by using synthetic or semi-synthetic techniques for preparing proteins, polypeptides or other amino acid sequences; (7) by preparing a nucleic acid encoding a single domain antibody using techniques for
  • a single domain antibody corresponds to the VHH domains of naturally occurring heavy chain antibodies directed against MSLN.
  • VHH sequences can generally be generated or obtained by suitably immunizing a species of Llama with MSLN, (i.e., so as to raise an immune response and/or heavy chain antibodies directed against MSLN), by obtaining a suitable biological sample from said Llama (such as a blood sample, serum sample or sample of B-cells), and by generating VHH sequences directed against MSLN, starting from said sample, using any suitable technique known in the field.
  • VHH domains against MSLN are obtained from naive libraries of Camelid VHH sequences, for example by screening such a library using MSLN, or at least one part, fragment, antigenic determinant or epitope thereof using one or more screening techniques known in the field.
  • libraries and techniques are for example described in WO 99/37681, WO 01/90190, WO 03/025020 and WO 03/035694.
  • improved synthetic or semi-synthetic libraries derived from naive VHH libraries are used, such as VHH libraries obtained from naive VHH libraries by techniques such as random mutagenesis and/or CDR shuffling, as for example described in WO 00/43507.
  • yet another technique for obtaining VHH sequences directed against MSLN involves suitably immunizing a transgenic mammal that is capable of expressing heavy chain antibodies (i.e., so as to raise an immune response and/or heavy chain antibodies directed against MSLN), obtaining a suitable biological sample from said transgenic mammal (such as a blood sample, serum sample or sample of B-cells), and then generating VHH sequences directed against MSLN, starting from said sample, using any suitable technique known in the field.
  • a suitable biological sample such as a blood sample, serum sample or sample of B-cells
  • VHH sequences directed against MSLN starting from said sample, using any suitable technique known in the field.
  • the heavy chain antibody-expressing rats or mice and the further methods and techniques described in WO 02/085945 and in WO 04/049794 can be used.
  • an anti-MSLN single domain antibody of the MSLN targeting trispecific protein comprises a single domain antibody with an amino acid sequence that corresponds to the amino acid sequence of a naturally occurring VHH domain, but that has been "humanized", i.e., by replacing one or more amino acid residues in the amino acid sequence of said naturally occurring VHH sequence (and in particular in the framework sequences) by one or more of the amino acid residues that occur at the corresponding position(s) in a VH domain from a conventional 4-chain antibody from a human being ( e.g ., as indicated above).
  • This can be performed in a manner known in the field, which will be clear to the skilled person, for example on the basis of the further description herein.
  • humanized anti-MSLN single domain antibodies of the disclosure are obtained in any suitable manner known per se (i.e., as indicated under points (l)-(8) above) and thus are not strictly limited to polypeptides that have been obtained using a polypeptide that comprises a naturally occurring VHH domain as a starting material.
  • a single domain anti-MSLN antibody comprises a single domain antibody with an amino acid sequence that corresponds to the amino acid sequence of a naturally occurring VH domain, but that has been "camelized", i.e., by replacing one or more amino acid residues in the amino acid sequence of a naturally occurring VH domain from a conventional 4-chain antibody by one or more of the amino acid residues that occur at the corresponding position(s) in a VHH domain of a heavy chain antibody.
  • the VH sequence that is used as a starting material or starting point for generating or designing the camelized single domain is preferably a VH sequence from a mammal, more preferably the VH sequence of a human being, such as a VH3 sequence.
  • camelized anti-MSLN single domain antibodies of the disclosure are obtained in any suitable manner known in the field (i.e., as indicated under points (l)-(8) above) and thus are not strictly limited to polypeptides that have been obtained using a polypeptide that comprises a naturally occurring VH domain as a starting material.
  • both "humanization” and “camelization” is performed by providing a nucleotide sequence that encodes a naturally occurring VHH domain or VH domain, respectively, and then changing, one or more codons in said nucleotide sequence in such a way that the new nucleotide sequence encodes a "humanized” or “camelized” single domain antibody, respectively.
  • This nucleic acid can then be expressed, so as to provide a desired anti- MSLN single domain antibody of the disclosure.
  • the amino acid sequence of the desired humanized or camelized anti-MSLN single domain antibody of the disclosure, respectively are designed and then synthesized de novo using known techniques for peptide synthesis.
  • a nucleotide sequence encoding the desired humanized or camelized anti-MSLN single domain antibody of the disclosure, respectively is designed and then synthesized de novo using known techniques for nucleic acid synthesis, after which the nucleic acid thus obtained is expressed in using known expression techniques, so as to provide the desired anti-MSLN single domain antibody of the disclosure.
  • VHH sequences for example comprises combining one or more parts of one or more naturally occurring VH sequences (such as one or more framework (FR) sequences and/or complementarity determining region (CDR) sequences), one or more parts of one or more naturally occurring VHH sequences (such as one or more FR sequences or CDR sequences), and/or one or more synthetic or semi-synthetic sequences, in a suitable manner, so as to provide an anti-MSLN single domain antibody of the disclosure or a nucleotide sequence or nucleic acid encoding the same.
  • VH sequences such as one or more framework (FR) sequences and/or complementarity determining region (CDR) sequences
  • CDR complementarity determining region
  • the MSLN binding domain is an anti-MSLN specific antibody comprising a heavy chain variable complementarity determining region CDR1, a heavy chain variable CDR2, a heavy chain variable CDR3, a light chain variable CDR1, a light chain variable CDR2, and a light chain variable CDR3.
  • the MSLN binding domain comprises any domain that binds to MSLN including but not limited to domains from a monoclonal antibody, a polyclonal antibody, a recombinant antibody, a human antibody, a humanized antibody, or antigen binding fragments such as single domain antibodies (sdAb),
  • the MSLN binding domain is a single domain antibody.
  • the anti-MSLN single domain antibody comprises heavy chain variable complementarity determining regions (CDR), CDR1, CDR2, and CDR3.
  • the MSLN binding domain is a polypeptide comprising an amino acid sequence that is comprised of four framework regions/sequences (fl-f4) interrupted by three complementarity determining regions/sequences, as represented by the formula: fl-rl-f2- r2-f3-r3-f4, wherein rl, r2, and r3 are complementarity determining regions CDR1, CDR2, and CDR3, respectively, and fl, f2, f3, and f4 are framework residues.
  • the framework residues of the MSLN binding protein of the present disclosure comprise, for example, 75, 76, 77, 78, 79,
  • the MSLN binding domain comprises an amino acid sequence selected from SEQ ID NOs: 1-40, and 102-105.
  • the framework region 1 of a MSLN binding trispecific protein of this disclosure comprises a sequence as in any one of SEQ ID Nos.: 223-261.
  • the framework region 2 of a MSLN binding trispecific protein of this disclosure comprises a sequence as in any one of SEQ ID Nos.: 262-300.
  • the framework region 3 of a MSLN binding trispecific protein of this disclosure comprises a sequence as in any one of SEQ ID Nos.: 301-339.
  • the framework region 4 of a MSLN binding trispecific protein of this disclosure comprises a sequence as in any one of SEQ ID Nos.: 340- 378.
  • the CDR1 comprises the amino acid sequence as set forth in SEQ ID NO: 51 or a variant having one, two, three, four, five, six, seven, eight, nine, or ten amino acid substitutions in SEQ ID NO: 51.
  • the CDR2 comprises a sequence as set forth in SEQ ID NO: 52 or a variant having one, two, three, four, five, six, seven, eight, nine, or ten amino acid substitutions in SEQ ID NO: 52.
  • the CDR3 comprises a sequence as set forth in SEQ ID NO: 53 or a variant having one, two, three, four, five, six, seven, eight, nine, or ten amino acid substitutions in SEQ ID NO: 53.
  • the CDR1 comprises the amino acid sequence as set forth in SEQ ID NO: 54 or a variant having one, two, three, four, five, six, seven, eight, nine, or ten amino acid substitutions in SEQ ID NO: 54.
  • the CDR2 comprises a sequence as set forth in SEQ ID NO: 55 or a variant having one, two, three, four, five, six, seven, eight, nine, or ten amino acid substitutions in SEQ ID NO: 55.
  • the CDR3 comprises a sequence as set forth in SEQ ID NO: 56 or a variant having one, two, three, four, five, six, seven, eight, nine, or ten amino acid substitutions in SEQ ID NO: 56.
  • the CDR1 comprises the amino acid sequence as set forth in any one of SEQ ID Nos.: 106-144 or a variant having one, two, three, four, five, six, seven, eight, nine, or ten amino acid substitutions in any one of SEQ ID Nos.: 106-144.
  • the CDR2 comprises a sequence as set forth in any one of SEQ ID Nos.: 145-183 or a variant having one, two, three, four, five, six, seven, eight, nine, or ten amino acid substitutions in any one of SEQ ID Nos.: 145-183.
  • the CDR3 comprises a sequence as set forth in any one of SEQ ID Nos.: 184-222 or a variant having one, two, three, four, five, six, seven, eight, nine, or ten amino acid substitutions in any one of SEQ ID Nos.: 184-222.
  • the MSLN binding domains of the present disclosure comprise one or more conserved regions.
  • the conserved regions comprise sequences as set forth in SEQ ID NOs: 41-49, or variants comprising one or more amino acid residue substitutions relative to said sequences.
  • Exemplary embodiments include MSLN binding proteins comprising one or more conserved regions selected from SEQ ID NOs: 41-44, or variants comprising one or more amino acid residue substitutions relative to said sequences.
  • the MSLN binding domain comprises (i) a stretch of amino acids corresponding to SEQ ID NO: 41, (ii) a stretch of amino acids corresponding to SEQ ID NO: 42, (iii) a stretch of amino acids corresponding to SEQ ID NO: 43, and (iv) a stretch of amino acids corresponding to SEQ ID NO: 44.
  • MSLN binding domains comprising one or more conserved regions selected from SEQ ID NOs: 45-50, or variants comprising one or more amino acid residue substitutions relative to said sequences.
  • the MSLN binding domain comprises (i) a stretch of amino acids corresponding to SEQ ID NO: 45, (ii) a stretch of amino acids corresponding to SEQ ID NO: 46, (iii) a stretch of amino acids corresponding to SEQ ID NO: 47, (iv) a stretch of amino acids corresponding to SEQ ID NO: 48, (v) a stretch of amino acid corresponding to SEQ ID NO: 49, and (vi) a stretch of amino acids corresponding to SEQ ID NO: 50.
  • the MSLN binding domain of the present disclosure is at least about 75%, about 76%, about 77%, about 78%, about 79%, about 80%, about 81%, about 82%, about 83%, about 84%, about 85%, about 86%, about 87%, about 88%, about 89%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, about 99%, or about 100% identical to an amino acid sequence selected from SEQ ID NOs: 1- 29.
  • the MSLN binding domain of the present disclosure is at least about 75%, about 76%, about 77%, about 78%, about 79%, about 80%, about 81%, about 82%, about 83%, about 84%, about 85%, about 86%, about 87%, about 88%, about 89%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, about 99%, or about 100% identical to an amino acid sequence selected from SEQ ID NOs: 30- 40, and 102-105.
  • a complementarity determining region of the MSLN binding domain of the present disclosure is at least about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 81%, about 82%, about 83%, about 84%, about 85%, about 86%, about 87%, about 88%, about 89%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, about 99%, or about 100% identical to the amino acid sequence set forth in SEQ ID NO: 51, SEQ ID NO: 54, or any one of SEQ ID Nos.: 106-144.
  • a complementarity determining region of the MSLN binding domain of the present disclosure is at least about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 81%, about 82%, about 83%, about 84%, about 85%, about 86%, about 87%, about 88%, about 89%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, about 99%, or about 100% identical to the amino acid sequence set forth in SEQ ID NO: 52, SEQ ID NO: 55, or any one of SEQ ID Nos.: 145-183.
  • a complementarity determining region of the MSLN binding domain of the present disclosure is at least about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 81%, about 82%, about 83%, about 84%, about 85%, about 86%, about 87%, about 88%, about 89%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, about 99%, or about 100% identical to the amino acid sequence set forth in SEQ ID NO: 53, SEQ ID NO: 56, or any one of SEQ ID Nos.: 184-222.
  • the MSLN binding protein is a single domain antibody comprising the sequence of SEQ ID NO: 1. In some embodiments, the MSLN binding protein, according to any one of the above embodiments, is a single domain antibody comprising the sequence of SEQ ID NO: 2. In some embodiments, the MSLN binding protein, according to any one of the above embodiments, is a single domain antibody comprising the sequence of SEQ ID NO: 3. In some embodiments, the MSLN binding protein, according to any one of the above embodiments, is a single domain antibody comprising the sequence of SEQ ID NO: 4.
  • the MSLN binding protein is a single domain antibody comprising the sequence of SEQ ID NO: 5. In some embodiments, the MSLN binding protein, according to any one of the above embodiments, is a single domain antibody comprising the sequence of SEQ ID NO: 6. In some embodiments, the MSLN binding protein, according to any one of the above embodiments, is a single domain antibody comprising the sequence of SEQ ID NO: 7. In some embodiments, the MSLN binding protein, according to any one of the above embodiments, is a single domain antibody comprising the sequence of SEQ ID NO: 8.
  • the MSLN binding protein is a single domain antibody comprising the sequence of SEQ ID NO: 9. In some embodiments, the MSLN binding protein, according to any one of the above embodiments, is a single domain antibody comprising the sequence of SEQ ID NO: 10. In some embodiments, the MSLN binding protein, according to any one of the above embodiments, is a single domain antibody comprising the sequence of SEQ ID NO: 11. In some embodiments, the MSLN binding protein, according to any one of the above embodiments, is a single domain antibody comprising the sequence of SEQ ID NO: 12.
  • the MSLN binding protein is a single domain antibody comprising the sequence of SEQ ID NO: 13. In some embodiments, the MSLN binding protein, according to any one of the above embodiments, is a single domain antibody comprising the sequence of SEQ ID NO: 14. In some embodiments, the MSLN binding protein, according to any one of the above embodiments, is a single domain antibody comprising the sequence of SEQ ID NO: 15. In some embodiments, the MSLN binding protein, according to any one of the above embodiments, is a single domain antibody comprising the sequence of SEQ ID NO: 16.
  • the MSLN binding protein is a single domain antibody comprising the sequence of SEQ ID NO: 17. In some embodiments, the MSLN binding protein, according to any one of the above embodiments, is a single domain antibody comprising the sequence of SEQ ID NO: 18. In some embodiments, the MSLN binding protein, according to any one of the above embodiments, is a single domain antibody comprising the sequence of SEQ ID NO: 19. In some embodiments, the MSLN binding protein, according to any one of the above embodiments, is a single domain antibody comprising the sequence of SEQ ID NO: 20.
  • the MSLN binding protein is a single domain antibody comprising the sequence of SEQ ID NO: 21. In some embodiments, the MSLN binding protein, according to any one of the above embodiments, is a single domain antibody comprising the sequence of SEQ ID NO: 22. In some embodiments, the MSLN binding protein, according to any one of the above embodiments, is a single domain antibody comprising the sequence of SEQ ID NO: 23. In some embodiments, the MSLN binding protein, according to any one of the above embodiments, is a single domain antibody comprising the sequence of SEQ ID NO: 24.
  • the MSLN binding protein is a single domain antibody comprising the sequence of SEQ ID NO: 25. In some embodiments, the MSLN binding protein, according to any one of the above embodiments, is a single domain antibody comprising the sequence of SEQ ID NO: 26. In some embodiments, the MSLN binding protein, according to any one of the above embodiments, is a single domain antibody comprising the sequence of SEQ ID NO: 27. In some embodiments, the MSLN binding protein, according to any one of the above embodiments, is a single domain antibody comprising the sequence of SEQ ID NO: 28. In some embodiments, the MSLN binding protein, according to any one of the above embodiments, is a single domain antibody comprising the sequence of SEQ ID NO: 29.
  • the MSLN binding protein is a humanized single domain antibody comprising the sequence of SEQ ID NO:
  • the MSLN binding protein is a humanized single domain antibody comprising the sequence of SEQ ID NO:
  • the MSLN binding protein is a humanized single domain antibody comprising the sequence of SEQ ID NO:
  • the MSLN binding protein is a humanized single domain antibody comprising the sequence of SEQ ID NO:
  • the MSLN binding protein is a humanized single domain antibody comprising the sequence of SEQ ID NO:
  • the MSLN binding protein is a humanized single domain antibody comprising the sequence of SEQ ID NO:
  • the MSLN binding protein is a humanized single domain antibody comprising the sequence of SEQ ID NO:
  • the MSLN binding protein is a humanized single domain antibody comprising the sequence of SEQ ID NO:
  • the MSLN binding protein is a humanized single domain antibody comprising the sequence of SEQ ID NO:
  • the MSLN binding protein is a humanized single domain antibody comprising the sequence of SEQ ID NO:
  • the MSLN binding protein is a humanized single domain antibody comprising the sequence of SEQ ID NO:
  • the MSLN binding protein is a humanized single domain antibody comprising the sequence of SEQ ID NO:
  • the MSLN binding protein is a humanized single domain antibody comprising the sequence of SEQ ID NO:
  • the MSLN binding protein is a humanized single domain antibody comprising the sequence of SEQ ID NO:
  • the MSLN binding protein is a humanized single domain antibody comprising the sequence of SEQ ID NO: 105.
  • the MSLN binding domain is cross-reactive with human and cynomolgus mesothelin. In some embodiments, the MSLN binding domain is specific for human mesothelin. In certain embodiments, the MSLN binding domains disclosed herein bind to human mesothelin with a human Kd (hKd). In certain embodiments, the MSLN binding domains disclosed herein bind to cynomolgus mesothelin with a cyno Kd (cKd).
  • the MSLN binding domains disclosed herein bind to both cynomolgus mesothelin and a human mesothelin, with a cyno Kd (cKd) and a human Kd (hKd), respectively.
  • the MSLN binding protein binds to human and cynomolgus mesothelin with comparable binding affinities (i.e., hKd and cKd values do not differ by more than ⁇ 10%).
  • the hKd and the cKd range from about 0.1 nM to about 500 nM.
  • the hKd and the cKd range from about 0.1 nM to about 450 nM. In some embodiments, the hKd and the cKd range from about 0.1 nM to about 400 nM. In some embodiments, the hKd and the cKd range from about 0.1 nM to about 350 nM. In some embodiments, the hKd and the cKd range from about 0.1 nM to about 300 nM . In some embodiments, the hKd and the cKd range from about 0.1 nM to about 250 nM. In some embodiments, the hKd and the cKd range from about 0.1 nM to about 200 nM.
  • the hKd and the cKd range from about 0.1 nM to about 150 nM. In some embodiments, the hKd and the cKd range from about 0.1 nM to about 100 nM. In some embodiments, the hKd and the cKd range from about 0.1 nM to about 90 nM. In some embodiments, the hKd and the cKd range from about 0.2 nM to about 80 nM. In some embodiments, the hKd and the cKd range from about 0.3 nM to about 70 nM. In some embodiments, the hKd and the cKd range from about 0.4 nM to about 50 nM.
  • the hKd and the cKd range from about 0.5 nM to about 30 nM. In some embodiments, the hKd and the cKd range from about 0.6 nM to about 10 nM. In some embodiments, the hKd and the cKd range from about 0.7 nM to about 8 nM. In some embodiments, the hKd and the cKd range from about 0.8 nM to about 6 nM. In some embodiments, the hKd and the cKd range from about 0.9 nM to about 4 nM. In some embodiments, the hKd and the cKd range from about 1 nM to about 2 nM.
  • any of the foregoing MSLN binding domains are affinity peptide tagged for ease of purification.
  • the affinity peptide tag is six consecutive histidine residues, also referred to as 6X-his (SEQ ID NO: 379).
  • the MSLN binding domains of the present disclosure preferentially bind membrane bound mesothelin over soluble mesothelin.
  • Membrane bound mesothelin refers to the presence of mesothelin in or on the cell membrane surface of a cell that expresses mesothelin.
  • Soluble mesothelin refers to mesothelin that is no longer on in or on the cell membrane surface of a cell that expresses or expressed mesothelin.
  • the soluble mesothelin is present in the blood and/or lymphatic circulation in a subject.
  • the MSLN binding domains bind membrane-bound mesothelin at least 5 fold, 10 fold, 15 fold, 20 fold, 25 fold, 30 fold, 40 fold, 50 fold, 100 fold, 500 fold, or 1000 fold greater than soluble mesothelin.
  • the MSLN targeting trispecific antigen binding proteins of the present disclosure preferentially bind membrane-bound mesothelin 30 fold greater than soluble mesothelin. Determining the preferential binding of an antigen binding protein to membrane bound MSLN over soluble MSLN can be readily determined using assays well known in the art.
  • TriTAC molecule also referred to herein as a TriTAC molecule
  • the TriTAC molecule comprises an amino acid sequence as set forth in any one of SEQ ID Nos: 58-86, 98, 100, and 101.
  • a TriTAC molecule of this disclosure comprises an amino acid sequence that is at least about 75%, about 76%, about 77%, about 78%, about 79%, about 80%, about 81%, about 82%, about 83%, about 84%, about 85%, about 86%, about 87%, about 88%, about 89%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, about 99%, or about 100% identical to an amino acid sequence selected from SEQ ID NOs: 58-86, 98, 100, and 101.
  • a TriTAC molecule of this disclosure comprises an amino acid sequence that is at least about 75%, about 76%, about 77%, about 78%, about 79%, about 80%, about 81%, about 82%, about 83%, about 84%, about 85%, about 86%, about 87%, about 88%, about 89%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, about 99%, or about 100% identical to the full length of an amino acid sequence selected from SEQ ID NOs: 58-86, 98, 100, and 101.
  • a TriTAC molecule of this disclosure comprises an amino acid sequence that is at least about 75%, about 76%, about 77%, about 78%, about 79%, about 80%, about 81%, about 82%, about 83%, about 84%, about 85%, about 86%, about 87%, about 88%, about 89%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, about 99%, or about 100% identical to a fraction of the full length of an amino acid sequence selected from SEQ ID NOs: 58-86, 98, 100, and 101. Integration into chimeric antigen receptors (CAR)
  • CAR chimeric antigen receptors
  • the MSLN targeting trispecific antigen binding proteins of the present disclosure can, in certain examples, be incorporated into a chimeric antigen receptor (CAR).
  • An engineered immune effector cell e.g ., a T cell or NK cell, can be used to express a CAR that includes an anti-MSLN targeting trispecific protein containing an anti-MSLN single domain antibody as described herein.
  • the CAR including an anti-MSLN targeting trispecific protein as described herein is connected to a transmembrane domain via a hinge region, and further a costimulatory domain, e.g.
  • the CAR further comprises a sequence encoding a intracellular signaling domain, such as 4-1BB and/or CD3 zeta.
  • the MSLN targeting trispecific proteins of the disclosure reduce the growth of tumor cells in vivo when administered to a subject who has tumor cells that express mesothelin.
  • Measurement of the reduction of the growth of tumor cells can be determined by multiple different methodologies well known in the art. Nonlimiting examples include direct measurement of tumor dimension, measurement of excised tumor mass and comparison to control subjects, measurement via imaging techniques (e.g, CT or MRI) that may or may not use isotopes or luminescent molecules (e.g, luciferase) for enhanced analysis, and the like.
  • administration of the trispecific proteins of the disclosure results in a reduction of in vivo growth of tumor cells as compared to a control antigen binding agent by at least about 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or 100%, with an about 100% reduction in tumor growth indicating a complete response and disappearance of the tumor.
  • administration of the trispecific proteins of the disclosure results in a reduction of in vivo growth of tumor cells as compared to a control antigen binding agent by about 50-100%, about 75-100% or about 90-100%.
  • administration of the trispecific proteins of the disclosure results in a reduction of in vivo growth of tumor cells as compared to a control antigen binding agent by about 50-60%, about 60-70%, about 70-80%, about 80-90%, or about 90-100%.
  • the MSLN targeting trispecific proteins described herein encompass derivatives or analogs in which (i) an amino acid is substituted with an amino acid residue that is not one encoded by the genetic code, (ii) the mature polypeptide is fused with another compound such as polyethylene glycol, or (iii) additional amino acids are fused to the protein, such as a leader or secretory sequence or a sequence for purification of the protein.
  • Typical modifications include, but are not limited to, acetylation, acylation, ADP- ribosylation, amidation, covalent attachment of flavin, covalent attachment of a heme moiety, covalent attachment of a nucleotide or nucleotide derivative, covalent attachment of a lipid or lipid derivative, covalent attachment of phosphatidylinositol, cross-linking, cyclization, disulfide bond formation, demethyl ati on, formation of covalent crosslinks, formation of cystine, formation of pyroglutamate, formylation, gamma carboxyl ati on, glycosylation, GPI anchor formation, hydroxylation, iodination, methylation, myristoylation, oxidation, proteolytic processing, phosphorylation, prenylation, racemization, selenoylation, sulfation, transfer-RNA mediated addition of amino acids to proteins such as arginylation, and ubiquitination.
  • Modifications are made anywhere in MSLN targeting trispecific proteins described herein, including the peptide backbone, the amino acid side-chains, and the amino or carboxyl termini.
  • Certain common peptide modifications that are useful for modification of MSLN targeting trispecific proteins include glycosylation, lipid attachment, sulfation, gamma- carboxylation of glutamic acid residues, hydroxylation, blockage of the amino or carboxyl group in a polypeptide, or both, by a covalent modification, and ADP-ribosylation.
  • polynucleotide molecules encoding an anti- MSLN trispecific binding protein described herein.
  • the polynucleotide molecules are provided as a DNA construct.
  • the polynucleotide molecules are provided as a messenger RNA transcript.
  • the polynucleotide molecules are constructed by known methods such as by combining the genes encoding the three binding domains either separated by peptide linkers or, in other embodiments, directly linked by a peptide bond, into a single genetic construct operably linked to a suitable promoter, and optionally a suitable transcription terminator, and expressing it in bacteria or other appropriate expression system such as, for example CHO cells.
  • the polynucleotides contain genes encoding the CD3 binding domain and the half-life extension domain.
  • the polynucleotides contain genes encoding the domains that bind to CD3 and MSLN.
  • any number of suitable transcription and translation elements including constitutive and inducible promoters, may be used.
  • the promoter is selected such that it drives the expression of the polynucleotide in the respective host cell.
  • the polynucleotide is inserted into a vector, preferably an expression vector, which represents a further embodiment.
  • This recombinant vector can be constructed according to known methods.
  • Vectors of particular interest include plasmids, phagemids, phage derivatives, virii (e.g ., retroviruses, adenoviruses, adeno-associated viruses, herpes viruses, lentiviruses, and the like), and cosmids.
  • a variety of expression vector/host systems may be utilized to contain and express the polynucleotide encoding the polypeptide of the described trispecific antigen-binding protein.
  • Examples of expression vectors for expression in E.coli are pSKK (Le Gall et al., J Immunol Methods. (2004) 285(1): 111-27) or pcDNA5 (Invitrogen) for expression in mammalian cells.
  • the MSLN targeting trispecific proteins as described herein are produced by introducing a vector encoding the protein as described above into a host cell and culturing said host cell under conditions whereby the protein domains are expressed, may be isolated and, optionally, further purified.
  • compositions comprising an anti-MSLN trispecific binding protein described herein, a vector comprising the polynucleotide encoding the polypeptide of the MSLN targeting trispecific proteins or a host cell transformed by this vector and at least one pharmaceutically acceptable carrier.
  • pharmaceutically acceptable carrier includes, but is not limited to, any carrier that does not interfere with the effectiveness of the biological activity of the ingredients and that is not toxic to the patient to whom it is administered. Examples of suitable pharmaceutical carriers are well known in the art and include phosphate buffered saline solutions, water, emulsions, such as oil/water emulsions, various types of wetting agents, sterile solutions etc.
  • compositions are sterile. These compositions may also contain adjuvants such as preservative, emulsifying agents and dispersing agents. Prevention of the action of microorganisms may be ensured by the inclusion of various antibacterial and antifungal agents.
  • a further embodiment provides one or more of the above described MSLN targeting trispecific proteins packaged in lyophilized form, or packaged in an aqueous medium.
  • the MSLN targeting trispecific proteins described herein are encapsulated in nanoparticles.
  • the nanoparticles are fullerenes, liquid crystals, liposome, quantum dots, superparamagnetic nanoparticles, dendrimers, or nanorods.
  • the MSLN trispecific antigen-binding protein is attached to liposomes.
  • the MSLN trispecific antigen-binding protein are conjugated to the surface of liposomes.
  • the MSLN trispecific antigen-binding protein are encapsulated within the shell of a liposome.
  • the liposome is a cationic liposome.
  • the MSLN targeting trispecific proteins described herein are contemplated for use as a medicament.
  • Administration is effected by different ways, e.g. by intravenous, intraperitoneal, subcutaneous, intramuscular, topical or intradermal administration.
  • the route of administration depends on the kind of therapy and the kind of compound contained in the pharmaceutical composition.
  • the dosage regimen will be determined by the attending physician and other clinical factors. Dosages for any one patient depends on many factors, including the patient's size, body surface area, age, sex, the particular compound to be administered, time and route of administration, the kind of therapy, general health and other drugs being administered concurrently.
  • An "effective dose” refers to amounts of the active ingredient that are sufficient to affect the course and the severity of the disease, leading to the reduction or remission of such pathology and may be determined using known methods.
  • the MSLN targeting trispecific proteins of this disclosure are administered at a dosage of up to 10 mg/kg at a frequency of once a week. In some cases, the dosage ranges from about 1 ng/kg to about 10 mg/kg.
  • the dose is from about 1 ng/kg to about 10 ng/kg, about 5 ng/kg to about 15 ng/kg, about 12 ng/kg to about 20 ng/kg, about 18 ng/kg to about 30 ng/kg, about 25 ng/kg to about 50 ng/kg, about 35 ng/kg to about 60 ng/kg, about 45 ng/kg to about 70 ng/kg, about 65 ng/kg to about 85 ng/kg, about 80 ng/kg to about 1 pg/kg, about 0.5 pg/kg to about 5 pg/kg, about 2 pg/kg to about 10 pg/kg, about 7 pg/kg to about 15 pg/kg, about 12 pg/kg to about 25 pg/kg, about 20 pg/kg to about 50 pg/kg, about 35 pg/kg to about 70 pg/kg, about 45 pg/kg to about 80 pg/kg, about 65 pg/kg, about 1
  • the dosage is about 0.1 mg/kg to about 0.2 mg/kg; about 0.25 mg/kg to about 0.5 mg/kg, about 0.45 mg/kg to about 1 mg/kg, about 0.75 mg/kg to about 3 mg/kg, about 2.5 mg/kg to about 4 mg/kg, about 3.5 mg/kg to about 5 mg/kg, about 4.5 mg/kg to about 6 mg/kg, about 5.5 mg/kg to about 7 mg/kg, about 6.5 mg/kg to about 8 mg/kg, about 7.5 mg/kg to about 9 mg/kg, or about 8.5 mg/kg to about 10 mg/kg.
  • the frequency of administration in some embodiments, is about less than daily, every other day, less than once a day, twice a week, weekly, once in 7 days, once in two weeks, once in two weeks, once in three weeks, once in four weeks, or once a month. In some cases, the frequency of administration is weekly. In some cases, the frequency of administration is weekly and the dosage is up to 10 mg/kg. In some cases, duration of administration is from about 1 day to about 4 weeks or longer.
  • the MSLN targeting trispecific proteins of this disclosure are administered at a dosage of about 1 ng/kg to about 10 ng/kg, about 1 ng/kg to about 20 ng/kg, about 1 ng/kg to about 50 ng/kg, about 1 ng/kg to about 80 ng//kg, about 1 ng/kg to about 100 ng/kg, about lng/kg to about 120 ng/kg, about 1 ng/kg to about 150 ng/kg, about 1 ng/kg to about 180 ng/kg, about 1 ng/kg to about 200 ng/kg, about 1 ng/kg to about 500 ng/kg, about lng/kg to about lgg/kg, about 1 ng/kg to about 10 gg/kg, about 1 ng/kg to about 100 gg/kg, about 1 ng/kg to about 1 mg/kg, about 1 ng/kg to about 10 mg/kg, about 10 ng/kg to about 20 ng/kg, about 10 ng/kg/kg, about 10 ng
  • the MSLN targeting trispecific proteins of this disclosure are administered at a dosage of about 6 ng/kg to about 18 ng/kg, about 6ng/kg to about 54 ng/kg, about 6 ng/kg to about 68 ng/kg, about 6 ng/kg to about 90 ng/kg, about 6 ng/kg to about 120 ng/kg, about 6 ng/kg to about 160 ng/kg, about 6 ng/kg to about 210 ng/kg, about 6 ng/kg to about 280 ng/kg, about 6 ng/kg to about 560 ng/kg, about 6 ng/kg to about 600 ng/kg, about 6 ng/kg to about 900 ng/kg, about 6 ng/kg to about 1200 ng/kg, about 18ng/kg to about 54 ng/kg, about 18 ng/kg to about 68 ng/kg, about 18 ng/kg to about 90 ng/kg, about 18 ng/kg to about 120 ng/kg
  • the MSLN targeting trispecific protein described herein can be administered using different dosages.
  • the MSLN targeting trispecific protein of this disclosure is administered according to a schedule comprising the following steps: (i) administration of a first dose of the MSLN targeting trispecific protein, and (ii) administration of a second dose of the MSLN targeting trispecific protein, wherein the second dose is higher than the first dose.
  • the schedule further comprises step (iii) administration of a third dose of the MSLN targeting trispecific protein, wherein the third dose is higher than the second dose.
  • the schedule further comprises step (iv) administration of a fourth dose of the MSLN targeting trispecific protein, wherein the fourth dose is higher than the third dose.
  • the schedule further comprises step (v) administration of a fifth dose of the MSLN targeting trispecific protein, wherein the fifth dose is higher than the fourth dose.
  • the first dose is about 10 ng/kg to about 100 ng/kg, about 10 ng/kg to about 200 ng/kg, about 10 ng/kg to about 500 ng/kg, about 10 ng/kg to about 1000 ng/kg, about 10 ng/kg to about 2000 ng/kg, about 10 ng/kg to about 5000 ng/kg, about 100 ng/kg to about 200 ng/kg, about 100 ng/kg to about 500 ng/kg, about 100 ng/kg to about 1000 ng/kg, about 100 ng/kg to about 2000 ng/kg, about 100 ng/kg to about 5000 ng/kg, about 200 ng/kg to about 500 ng/kg, about 200 ng/kg to about 1000 ng/kg, about 200 ng/kg to about 2000 ng/kg, about 200 ng/kg to about 5000 ng/kg, about 500 ng/kg to about 1000 ng/kg, about 500 ng/kg, about 500 ng/kg to about 2000 ng/kg, about 200
  • the first dose is administered for about 1 week to about 5 weeks, about 1 week to about 10 weeks, about 1 week to about 20 weeks, about 1 week to about 50 weeks, about 1 week to about 80 weeks, about 1 week to about 100 weeks, about 5 weeks to about 10 weeks, about 5 weeks to about 20 weeks, about 5 weeks to about 50 weeks, about 5 weeks to about 80 weeks, about 5 weeks to about 100 weeks, about 10 weeks to about 20 weeks, about 10 weeks to about 50 weeks, about 10 weeks to about 80 weeks, about 10 weeks to about 100 weeks, about 20 weeks to about 50 weeks, about 20 weeks to about 80 weeks, about 20 weeks to about 100 weeks, about 50 weeks to about 80 weeks, about 50 weeks to about 100 weeks, about 80 weeks to about 100 weeks, about 1 week to about 9 weeks, about 1 week to about 18 weeks, about 1 week to about 27 weeks, about 1 week to about 36 weeks, about 9 weeks to about 18 weeks, about 9 weeks to about 27 weeks, about 9 weeks to about 36 weeks, about 18 weeks to about 27 weeks, about 18 weeks to about 36 weeks, about 18 weeks to about 27 weeks,
  • the first dose is administered once per day, twice per day, three times per day, four times per day, five times per day, six times per day, seven times per day, eight times per day, nine times per day or ten times per day. In some embodiments, the first dose is administered once per week, twice per week, three times per week, four times per week, five times per week, six times per week, once every other week, once every three weeks, once every four week or once every five weeks.
  • the second dose is about 100 ng/kg to about 500 ng/kg, about 100 ng/kg to about 1000 ng/kg, about 100 ng/kg to about 5000 ng/kg, about 100 ng/kg to about 10,000 ng/kg, about 100 ng/kg to about 50,000 ng/kg, about 100 ng/kg to about 100,000 ng/kg, about 500 ng/kg to about 1000 ng/kg, about 500 ng/kg to about 5000 ng/kg, about 500 ng/kg to about 10,000 ng/kg, about 500 ng/kg to about 50,000 ng/kg, about 500 ng/kg to about 100,000 ng/kg, about 1000 ng/kg to about 5000 ng/kg, about 1000 ng/kg to about 10,000 ng/kg, about 1000 ng/kg to about 50,000 ng/kg, about 1000 ng/kg to about 100,000 ng/kg, about 5000 ng/kg, about 1000 ng/kg to about 10,000 ng/kg, about 1000 ng/kg to about 50,000 ng
  • the second dose is about 600 ng/kg. In some embodiments, the second dose is about 900 ng/kg. In some embodiments, the second dose is about 1200 ng/kg. In some embodiments, the second dose is about 1800 ng/kg. In some embodiments, the second dose is about 3600 ng/kg. In some embodiments, the second dose is about 7200 ng/kg. In some embodiments, the second dose is about 14400 ng/kg.
  • the second dose is administered for about 1 week to about 5 weeks, about 1 week to about 10 weeks, about 1 week to about 20 weeks, about 1 week to about 50 weeks, about 1 week to about 80 weeks, about 1 week to about 100 weeks, about 5 weeks to about 10 weeks, about 5 weeks to about 20 weeks, about 5 weeks to about 50 weeks, about 5 weeks to about 80 weeks, about 5 weeks to about 100 weeks, about 10 weeks to about 20 weeks, about 10 weeks to about 50 weeks, about 10 weeks to about 80 weeks, about 10 weeks to about 100 weeks, about 20 weeks to about 50 weeks, about 20 weeks to about 80 weeks, about 20 weeks to about 100 weeks, about 50 weeks to about 80 weeks, about 50 weeks to about 100 weeks, about 80 weeks to about 100 weeks, about 1 week to about 9 weeks, about 1 week to about 18 weeks, about 1 week to about 27 weeks, about 1 week to about 36 weeks, about 9 weeks to about 18 weeks, about 9 weeks to about 27 weeks, about 9 weeks to about 36 weeks, about 18 weeks to about 27 weeks, about 18 weeks to about 36 weeks, about 18 weeks to about 27 weeks,
  • the second dose is administered once per day, twice per day, three times per day, four times per day, five times per day, six times per day, seven times per day, eight times per day, nine times per day or ten times per day. In some embodiments, the second dose is administered once per week, twice per week, three times per week, four times per week, five times per week, six times per week, once every other week, once every three weeks, once every four week or once every five weeks.
  • the third dose is about 100 ng/kg to about 500 ng/kg, about 100 ng/kg to about 1000 ng/kg, about 100 ng/kg to about 5000 ng/kg, about 100 ng/kg to about 10,000 ng/kg, about 100 ng/kg to about 50,000 ng/kg, about 100 ng/kg to about 100,000 ng/kg, about 500 ng/kg to about 1000 ng/kg, about 500 ng/kg to about 5000 ng/kg, about 500 ng/kg to about 10,000 ng/kg, about 500 ng/kg to about 50,000 ng/kg, about 500 ng/kg to about 100,000 ng/kg, about 1000 ng/kg to about 5000 ng/kg, about 1000 ng/kg to about 10,000 ng/kg, about 1000 ng/kg to about 50,000 ng/kg, about 1000 ng/kg to about 100,000 ng/kg, about 5000 ng/kg, about 1000 ng/kg to about 10,000 ng/kg, about 1000 ng/kg to about 50,000 ng
  • the third dose is about 600 ng/kg. In some embodiments, the third dose is about 900 ng/kg. In some embodiments, the third dose is about 1200 ng/kg. In some embodiments, the third dose is about 1800 ng/kg. In some embodiments, the third dose is about 3600 ng/kg. In some embodiments, the third dose is about 7200 ng/kg. In some embodiments, the third dose is about 14400 ng/kg.
  • the third dose is administered for about 1 week to about 5 weeks, about 1 week to about 10 weeks, about 1 week to about 20 weeks, about 1 week to about 50 weeks, about 1 week to about 80 weeks, about 1 week to about 100 weeks, about 5 weeks to about 10 weeks, about 5 weeks to about 20 weeks, about 5 weeks to about 50 weeks, about 5 weeks to about 80 weeks, about 5 weeks to about 100 weeks, about 10 weeks to about 20 weeks, about 10 weeks to about 50 weeks, about 10 weeks to about 80 weeks, about 10 weeks to about 100 weeks, about 20 weeks to about 50 weeks, about 20 weeks to about 80 weeks, about 20 weeks to about 100 weeks, about 50 weeks to about 80 weeks, about 50 weeks to about 100 weeks, about 80 weeks to about 100 weeks, about 1 week to about 9 weeks, about 1 week to about 18 weeks, about 1 week to about 27 weeks, about 1 week to about 36 weeks, about 9 weeks to about 18 weeks, about 9 weeks to about 27 weeks, about 9 weeks to about 36 weeks, about 18 weeks to about 27 weeks, about 18 weeks to about 36 weeks, about 18 weeks to about 27 weeks,
  • the third dose is administered once per day, twice per day, three times per day, four times per day, five times per day, six times per day, seven times per day, eight times per day, nine times per day or ten times per day. In some embodiments, the third dose is administered once per week, twice per week, three times per week, four times per week, five times per week, six times per week, once every other week, once every three weeks, once every four week or once every five weeks.
  • the fourth dose is about 100 ng/kg to about 500 ng/kg, about 100 ng/kg to about 1000 ng/kg, about 100 ng/kg to about 5000 ng/kg, about 100 ng/kg to about 10,000 ng/kg, about 100 ng/kg to about 50,000 ng/kg, about 100 ng/kg to about 100,000 ng/kg, about 500 ng/kg to about 1000 ng/kg, about 500 ng/kg to about 5000 ng/kg, about 500 ng/kg to about 10,000 ng/kg, about 500 ng/kg to about 50,000 ng/kg, about 500 ng/kg to about 100,000 ng/kg, about 1000 ng/kg to about 5000 ng/kg, about 1000 ng/kg to about 10,000 ng/kg, about 1000 ng/kg to about 50,000 ng/kg, about 1000 ng/kg to about 100,000 ng/kg, about 5000 ng/kg, about 1000 ng/kg to about 10,000 ng/kg, about 1000 ng/kg to about 50,000 ng
  • the fourth dose is about 600 ng/kg. In some embodiments, the fourth dose is about 900 ng/kg. In some embodiments, the fourth dose is about 1200 ng/kg. In some embodiments, the fourth dose is about 1800 ng/kg. In some embodiments, the fourth dose is about 3600 ng/kg. In some embodiments, the fourth dose is about 7200 ng/kg. In some embodiments, the fourth dose is about 14400 ng/kg.
  • the fourth dose is administered for about 1 week to about 5 weeks, about 1 week to about 10 weeks, about 1 week to about 20 weeks, about 1 week to about 50 weeks, about 1 week to about 80 weeks, about 1 week to about 100 weeks, about 5 weeks to about 10 weeks, about 5 weeks to about 20 weeks, about 5 weeks to about 50 weeks, about 5 weeks to about 80 weeks, about 5 weeks to about 100 weeks, about 10 weeks to about 20 weeks, about 10 weeks to about 50 weeks, about 10 weeks to about 80 weeks, about 10 weeks to about 100 weeks, about 20 weeks to about 50 weeks, about 20 weeks to about 80 weeks, about 20 weeks to about 100 weeks, about 50 weeks to about 80 weeks, about 50 weeks to about 100 weeks, about 80 weeks to about 100 weeks, about 1 week to about 9 weeks, about 1 week to about 18 weeks, about 1 week to about 27 weeks, about 1 week to about 36 weeks, about 9 weeks to about 18 weeks, about 9 weeks to about 27 weeks, about 9 weeks to about 36 weeks, about 18 weeks to about 27 weeks, about 18 weeks to about 36 weeks, about 18 weeks to about 27 weeks,
  • the fourth dose is administered once per day, twice per day, three times per day, four times per day, five times per day, six times per day, seven times per day, eight times per day, nine times per day or ten times per day. In some embodiments, the fourth dose is administered once per week, twice per week, three times per week, four times per week, five times per week, six times per week, once every other week, once every three weeks, once every four week or once every five weeks.
  • the fifth dose is about 100 ng/kg to about 500 ng/kg, about 100 ng/kg to about 1000 ng/kg, about 100 ng/kg to about 5000 ng/kg, about 100 ng/kg to about 10,000 ng/kg, about 100 ng/kg to about 50,000 ng/kg, about 100 ng/kg to about 100,000 ng/kg, about 500 ng/kg to about 1000 ng/kg, about 500 ng/kg to about 5000 ng/kg, about 500 ng/kg to about 10,000 ng/kg, about 500 ng/kg to about 50,000 ng/kg, about 500 ng/kg to about 100,000 ng/kg, about 1000 ng/kg to about 5000 ng/kg, about 1000 ng/kg to about 10,000 ng/kg, about 1000 ng/kg to about 50,000 ng/kg, about 1000 ng/kg to about 100,000 ng/kg, about 5000 ng/kg, about 1000 ng/kg to about 10,000 ng/kg, about 1000 ng/kg to about 50,000 ng
  • the fifth dose is about 600 ng/kg. In some embodiments, the fifth dose is about 900 ng/kg. In some embodiments, the fifth dose is about 1200 ng/kg. In some embodiments, the fifth dose is about 1800 ng/kg. In some embodiments, the fifth dose is about 3600 ng/kg. In some embodiments, the fifth dose is about 7200 ng/kg. In some embodiments, the fifth dose is about 14400 ng/kg.
  • the fifth dose is administered for about 1 week to about 5 weeks, about 1 week to about 10 weeks, about 1 week to about 20 weeks, about 1 week to about 50 weeks, about 1 week to about 80 weeks, about 1 week to about 100 weeks, about 5 weeks to about 10 weeks, about 5 weeks to about 20 weeks, about 5 weeks to about 50 weeks, about 5 weeks to about 80 weeks, about 5 weeks to about 100 weeks, about 10 weeks to about 20 weeks, about 10 weeks to about 50 weeks, about 10 weeks to about 80 weeks, about 10 weeks to about 100 weeks, about 20 weeks to about 50 weeks, about 20 weeks to about 80 weeks, about 20 weeks to about 100 weeks, about 50 weeks to about 80 weeks, about 50 weeks to about 100 weeks, about 80 weeks to about 100 weeks, about 1 week to about 9 weeks, about 1 week to about 18 weeks, about 1 week to about 27 weeks, about 1 week to about 36 weeks, about 9 weeks to about 18 weeks, about 9 weeks to about 27 weeks, about 9 weeks to about 36 weeks, about 18 weeks to about 27 weeks, about 18 weeks to about 36 weeks, about 18 weeks to about 27 weeks,
  • the fifth dose is administered once per day, twice per day, three times per day, four times per day, five times per day, six times per day, seven times per day, eight times per day, nine times per day or ten times per day. In some embodiments, the fifth dose is administered once per week, twice per week, three times per week, four times per week, five times per week, six times per week, once every other week, once every three weeks, once every four week or once every five weeks.
  • kits and uses for stimulating the immune system of an individual in need thereof comprising administration of an anti-MSLN targeting trispecific protein as described herein.
  • the administration of an anti- MSLN targeting trispecific protein described herein induces and/or sustains cytotoxicity towards a cell expressing a target antigen.
  • the cell expressing a target antigen is a cancer or tumor cell, a virally infected cell, a bacterially infected cell, an autoreactive T or B cell, damaged red blood cells, arterial plaques, or fibrotic tissue.
  • Also provided herein are methods and uses for a treatment of a disease, disorder or condition associated with a target antigen comprising administering to an individual in need thereof an anti- MSLN targeting trispecific protein described herein.
  • Diseases, disorders or conditions associated with a target antigen include, but are not limited to, viral infection, bacterial infection, auto-immune disease, transplant rejection, atherosclerosis, or fibrosis.
  • the disease, disorder or condition associated with a target antigen is a proliferative disease, a tumorous disease, an inflammatory disease, an immunological disorder, an autoimmune disease, an infectious disease, a viral disease, an allergic reaction, a parasitic reaction, a graft-versus-host disease or a host-versus-graft disease.
  • the disease, disorder or condition associated with a target antigen is cancer.
  • Cancers that can be treated, prevented, or managed by the MSLN binding proteins of the present disclosure, and methods of using them, include but are not limited to cancers of an epithelial cell origin.
  • cancers include the following: leukemias, such as but not limited to, acute leukemia, acute lymphocytic leukemia, acute myelocytic leukemias, such as, myeloblastic, promyelocytic, myelomonocytic, monocytic, and erythroleukemia leukemias and myelodysplastic syndrome; chronic leukemias, such as but not limited to, chronic myelocytic (granulocytic) leukemia, chronic lymphocytic leukemia, hairy cell leukemia; polycythemia vera; lymphomas such as but not limited to Hodgkin's disease, non-Hodgkin's disease; multiple myelomas such as but not limited to smoldering multiple myeloma, nonsecretory myeloma, osteosclerotic myeloma, plasma cell leukemia, solitary plasmacytoma and extramedullary plasmacytoma; Waldenstrom
  • cancers include myxosarcoma, osteogenic sarcoma, endotheliosarcoma, lymphangioendotheliosarcoma, mesothelioma, synovioma, hemangioblastoma, epithelial carcinoma, cystadenocarcinoma, bronchogenic carcinoma, sweat gland carcinoma, sebaceous gland carcinoma, papillary carcinoma and papillary adenocarcinomas (for a review of such disorders, see Fishman et al., 1985, Medicine, 2d Ed., J.B. Lippincott Co., Philadelphia and Murphy et al., 1997, Informed Decisions: The Complete Book of Cancer Diagnosis, Treatment, and Recovery, Viking Penguin, Penguin Books U.S.A., Inc., United States of America).
  • the MSLN targeting trispecific proteins of the disclosure are also useful in the treatment or prevention of a variety of cancers or other abnormal proliferative diseases, including (but not limited to) the following: carcinoma, including that of the bladder, breast, colon, kidney, liver, lung, ovary, pancreas, stomach, cervix, thyroid and skin; including squamous cell carcinoma; hematopoietic tumors of lymphoid lineage, including leukemia, acute lymphocytic leukemia, acute lymphoblastic leukemia, B-cell lymphoma, T-cell lymphoma, Burkitf s lymphoma; hematopoietic tumors of myeloid lineage, including acute and chronic myelogenous leukemias and promyelocytic leukemia; tumors of mesenchymal origin, including fibrosarcoma and rhabdomyoscarcoma; other tumors, including melanoma, seminoma, tetratocarcinom
  • cancers caused by aberrations in apoptosis would also be treated by the methods and compositions of the disclosure.
  • Such cancers may include but not be limited to follicular lymphomas, carcinomas with p53 mutations, hormone dependent tumors of the breast, prostate and ovary, and precancerous lesions such as familial adenomatous polyposis, and myelodysplastic syndromes.
  • malignancy or dysproliferative changes are treated or prevented in the skin, lung, colon, breast, prostate, bladder, kidney, pancreas, ovary, or uterus.
  • treatment or “treating” or “treated” refers to therapeutic treatment wherein the object is to slow (lessen) an undesired physiological condition, disorder or disease, or to obtain beneficial or desired clinical results.
  • beneficial or desired clinical results include, but are not limited to, alleviation of symptoms; diminishment of the extent of the condition, disorder or disease; stabilization (i.e., not worsening) of the state of the condition, disorder or disease; delay in onset or slowing of the progression of the condition, disorder or disease; amelioration of the condition, disorder or disease state; and remission (whether partial or total), whether detectable or undetectable, or enhancement or improvement of the condition, disorder or disease.
  • Treatment includes eliciting a clinically significant response without excessive levels of side effects. Treatment also includes prolonging survival as compared to expected survival if not receiving treatment.
  • treatment refers to prophylactic measures, wherein the object is to delay onset of or reduce severity of an undesired physiological condition, disorder or disease, such as, for example is a person who is predisposed to a disease (e.g ., an individual who carries a genetic marker for a disease such as breast cancer).
  • the MSLN targeting trispecific proteins as described herein are administered in combination with an agent for treatment of the particular disease, disorder or condition.
  • Agents include but are not limited to, therapies involving antibodies, small molecules (e.g., chemotherapeutics), hormones (steroidal, peptide, and the like), radiotherapies (g-rays, X-rays, and/or the directed delivery of radioisotopes, microwaves, UV radiation and the like), gene therapies (e.g, antisense, retroviral therapy and the like) and other immunotherapies.
  • an anti-MSLN targeting trispecific protein as described herein is administered in combination with anti-diarrheal agents, anti emetic agents, analgesics, opioids and/or non-steroidal anti-inflammatory agents. In some embodiments, an anti-MSLN targeting trispecific protein as described herein is administered in combination with anti-cancer agents.
  • Nonlimiting examples of anti-cancer agents that can be used in the various embodiments of the disclosure, including pharmaceutical compositions and dosage forms and kits of the disclosure, include: acivicin; aclarubicin; acodazole hydrochloride; acronine; adozelesin; aldesleukin; altretamine; ambomycin; ametantrone acetate; aminoglutethimide; amsacrine; anastrozole; anthramycin; asparaginase; asperlin; azacitidine; azetepa; azotomycin; batimastat; benzodepa; bicalutamide; bisantrene hydrochloride; bisnafide dimesylate; bizelesin; bleomycin sulfate; brequinar sodium; bropirimine; busulfan; cactinomycin; calusterone; caracemide; carbetimer; carboplatin; carmustine; carubic
  • anti-cancer drugs include, but are not limited to: 20-epi-l,25 dihy droxy vitamin D3; 5-ethynyluracil; abiraterone; aclarubicin; acylfulvene; adecypenol; adozelesin; aldesleukin; ALL-TK antagonists; altretamine; ambamustine; amidox; amifostine; aminolevulinic acid; amrubicin; amsacrine; anagrelide; anastrozole; andrographolide; angiogenesis inhibitors; antagonist D; antagonist G; antarelix; anti-dorsalizing morphogenetic protein- 1; antiandrogen, prostatic carcinoma; antiestrogen; antineoplaston; antisense oligonucleotides; aphidicolin glycinate; apoptosis gene modulators; apoptosis regulators; apurinic acid; ara-
  • Additional anti-cancer drugs are 5-fluorouracil and leucovorin. These two agents are particularly useful when used in methods employing thalidomide and a topoisomerase inhibitor.
  • the anti-MSLN targeting trispecific protein of the present disclosure is used in combination with gemcitabine.
  • the anti-MSLN targeting trispecific protein as described herein is administered before, during, or after surgery.
  • kits for detecting expression of mesothelin in vitro or in vivo include the foregoing MSLN targeting trispecific proteins (e.g ., a trispecific protein containing a labeled anti-MSLN single domain antibody or antigen binding fragments thereof), and one or more compounds for detecting the label.
  • the label is selected from the group consisting of a fluorescent label, an enzyme label, a radioactive label, a nuclear magnetic resonance active label, a luminescent label, and a chromophore label.
  • mesothelin expression is detected in a biological sample.
  • the sample can be any sample, including, but not limited to, tissue from biopsies, autopsies and pathology specimens.
  • Biological samples also include sections of tissues, for example, frozen sections taken for histological purposes.
  • Biological samples further include body fluids, such as blood, serum, plasma, sputum, spinal fluid or urine.
  • a biological sample is typically obtained from a mammal, such as a human or non-human primate.
  • a method of determining if a subject has cancer by contacting a sample from the subject with an anti-MSLN single domain antibody as disclosed herein; and detecting binding of the single domain antibody to the sample.
  • An increase in binding of the antibody to the sample as compared to binding of the antibody to a control sample identifies the subject as having cancer.
  • a method of confirming a diagnosis of cancer in a subject by contacting a sample from a subject diagnosed with cancer with an anti-MSLN single domain antibody as disclosed herein; and detecting binding of the antibody to the sample.
  • An increase in binding of the antibody to the sample as compared to binding of the antibody to a control sample confirms the diagnosis of cancer in the subject.
  • the MSLN single domain antibody of the trispecific protein is directly labeled.
  • the methods further include contacting a second antibody that specifically binds the anti-MSLN single domain antibody with the sample; and detecting the binding of the second antibody.
  • An increase in binding of the second antibody to the sample as compared to binding of the second antibody to a control sample detects cancer in the subject or confirms the diagnosis of cancer in the subject.
  • the cancer is mesothelioma, prostate cancer, lung cancer, stomach cancer, squamous cell carcinoma, pancreatic cancer, cholangiocarcinoma, triple negative breast cancer or ovarian cancer, or any other type of cancer that expresses mesothelin.
  • control sample is a sample from a subject without cancer.
  • sample is a blood or tissue sample.
  • the antibody that binds (for example specifically binds) mesothelin is directly labeled with a detectable label.
  • the antibody that binds (for example, specifically binds) mesothelin (the first antibody) is unlabeled and a second antibody or other molecule that can bind the antibody that specifically binds mesothelin is labeled.
  • a second antibody is chosen such that it is able to specifically bind the specific species and class of the first antibody. For example, if the first antibody is a llama IgG, then the secondary antibody may be an anti-llama-IgG.
  • Suitable labels for the antibody or secondary antibody include various enzymes, prosthetic groups, fluorescent materials, luminescent materials, magnetic agents and radioactive materials.
  • suitable enzymes include horseradish peroxidase, alkaline phosphatase, beta-galactosidase, or acetylcholinesterase.
  • suitable prosthetic group complexes include streptavidin/biotin and avidin/biotin.
  • Nonlimiting examples of suitable fluorescent materials include umbelliferone, fluorescein, fluorescein isothiocyanate, rhodamine, dichlorotriazinylamine fluorescein, dansyl chloride or phycoerythrin.
  • a non-limiting exemplary luminescent material is luminol; a non-limiting exemplary a magnetic agent is gadolinium, and non-limiting exemplary radioactive labels include 1251, 1311, 35S or 3H.
  • mesothelin can be assayed in a biological sample by a competition immunoassay utilizing mesothelin standards labeled with a detectable substance and an unlabeled antibody that specifically binds mesothelin.
  • a competition immunoassay utilizing mesothelin standards labeled with a detectable substance and an unlabeled antibody that specifically binds mesothelin.
  • the biological sample, the labeled mesothelin standards and the antibody that specifically bind mesothelin are combined and the amount of labeled mesothelin standard bound to the unlabeled antibody is determined.
  • the amount of mesothelin in the biological sample is inversely proportional to the amount of labeled mesothelin standard bound to the antibody that specifically binds mesothelin.
  • the immunoassays and method disclosed herein can be used for a number of purposes.
  • the antibody that specifically binds mesothelin may be used to detect the production of mesothelin in cells in cell culture.
  • the antibody can be used to detect the amount of mesothelin in a biological sample, such as a tissue sample, or a blood or serum sample.
  • the mesothelin is cell-surface mesothelin.
  • the mesothelin is soluble mesothelin (e.g ., mesothelin in a cell culture supernatant or soluble mesothelin in a body fluid sample, such as a blood or serum sample).
  • kits for detecting mesothelin in a biological sample such as a blood sample or tissue sample.
  • a biological sample such as a blood sample or tissue sample.
  • a biopsy can be performed to obtain a tissue sample for histological examination.
  • a blood sample can be obtained to detect the presence of soluble mesothelin protein or fragment.
  • Kits for detecting a polypeptide will typically comprise a single domain antibody, according to the present disclosure, that specifically binds mesothelin.
  • an antibody fragment such as an scFv fragment, a VH domain, or a Fab is included in the kit.
  • the antibody is labeled (for example, with a fluorescent, radioactive, or an enzymatic label).
  • kits includes instructional materials disclosing means of use of an antibody that binds mesothelin.
  • the instructional materials may be written, in an electronic form (such as a computer diskette or compact disk) or may be visual (such as video files).
  • the kits may also include additional components to facilitate the particular application for which the kit is designed.
  • the kit may additionally contain means of detecting a label (such as enzyme substrates for enzymatic labels, filter sets to detect fluorescent labels, appropriate secondary labels such as a secondary antibody, or the like).
  • the kits may additionally include buffers and other reagents routinely used for the practice of a particular method. Such kits and appropriate contents are well known to those of skill in the art.
  • the diagnostic kit comprises an immunoassay.
  • the method of detecting mesothelin in a biological sample generally includes the steps of contacting the biological sample with an antibody which specifically reacts, under immunologically reactive conditions, to a mesothelin polypeptide.
  • the antibody is allowed to specifically bind under immunologically reactive conditions to form an immune complex, and the presence of the immune complex (bound antibody) is detected directly or indirectly.
  • the antibodies can be conjugated to other compounds including, but not limited to, enzymes, magnetic beads, colloidal magnetic beads, haptens, fluorochromes, metal compounds, radioactive compounds or drugs.
  • the antibodies can also be utilized in immunoassays such as but not limited to radioimmunoassays (RIAs), ELISA, or immunohistochemical assays.
  • the antibodies can also be used for fluorescence activated cell sorting (FACS).
  • FACS employs a plurality of color channels, low angle and obtuse light scattering detection channels, and impedance channels, among other more sophisticated levels of detection, to separate or sort cells (see U.S.
  • Patent No. 5, 061,620 Any of the single domain antibodies that bind mesothelin, as disclosed herein, can be used in these assays.
  • the antibodies can be used in a conventional immunoassay, including, without limitation, an ELISA, an RIA, FACS, tissue immunohistochemistry, Western blot or imunoprecipitation.
  • Example 1 Methods to assess binding and cytotoxic activities of several exemplary MSLN targeting trispecific antigen binding proteins [00143] Protein Production
  • T-cell dependent cellular cytotoxicity (TDCC) assay was used to measure the ability of T cell engagers, including trispecific molecules, to direct T cells to kill tumor cells (Nazarian et al. 2015. J Biomol Screen. 20:519-27).
  • T cells and target cancer cell line cells are mixed together at a 10:1 ratio in a 384 wells plate, and varying amounts of the trispecific proteins being tested are added.
  • the tumor cell lines are engineered to express luciferase protein. After 48 hours, to quantitate the remaining viable tumor cells, Steady-Glo® Luminescent Assay (Promega) was used.
  • TDCC assays T cell Dependent Cell Cytotoxicity assays
  • OVCAR8 mesothelin expressing ovarian cancer cell line
  • TDCC Activity of MSLN targeting trispecific proteins (TriTAC) [00148] Furthermore, it was observed that the TDCC activity of the MSLN targeting trispecific proteins being tested was specific to mesothelin expressing cells, because the trispecific proteins being tested did not mediate T cell killing of LNCaP cells, which do not express mesothelin.
  • Example 2 Xenograft tumor model
  • MSLN targeting trispecific proteins of the previous example is evaluated in a xenograft model.
  • mice Female immune-deficient NOD/scid mice are sub-lethally irradiated (2 Gy) and subcutaneously inoculated with IX 10 6 NCI-H28cells into their right dorsal flank. When tumors reach 100 to 200 mm 3 , animals are allocated into 3 treatment groups. Groups 2 and 3 (8 animals each) are intraperitoneally injected with 1.5xl0 7 activated human T-cells. Three days later, animals from Group 3 are subsequently treated with a total of 9 intravenous doses of 50 pg MSLN trispecific antigen-binding protein of Example 1 (qdx9d). Groups 1 and 2 are only treated with vehicle. Body weight and tumor volume are determined for 30 days.
  • Example 3 Proof-of-Concept clinical trial protocol for administration of the MSLN trispecific antigen-binding protein of Example 1 to ovarian cancer patients [00152] This is a Phase Eli clinical trial for studying the MSLN trispecific antigen-binding protein of Example 1 as a treatment for Ovarian Cancer.
  • MTD maximum tolerated dose
  • MSLN targeting trispecific proteins of the previous examples 1.2 Patients who fulfill eligibility criteria will be entered into the trial to MSLN targeting trispecific proteins of the previous examples. 1.3 The goal is to identify the highest dose of MSLN targeting trispecific proteins of the previous examples that can be administered safely without severe or unmanageable side effects in participants. The dose given will depend on the number of participants who have been enrolled in the study prior and how well the dose was tolerated. Not all participants will receive the same dose.
  • a subsequent phase II section will be treated at the MTD with a goal of determining if therapy with therapy of MSLN targeting trispecific proteins of the previous examples results in at least a 20% response rate.
  • Example 4 MH6T TriTAC directs T cells to kill MSLN expressing ovarian cancer cells
  • TDCC human T-cell dependent cellular cytotoxicity
  • T cells from 5 different healthy donors (donor 02, donor 86, donor 41, donor 81, and donor 34) and target cancer cells Caov3 were mixed together and varying amounts of an exemplary trispecific molecule of this disclosure, MH6T TriTAC (SEQ ID NO: 98) was added and the mixture was incubated for 48 hours at 37 °C.
  • Caov3 cells and T cells were also incubated for 48 hours at 37 °C with a control trispecific molecule, GFP TriTAC (SEQ ID NO: 99), which targets GFP. After 48 hours, the remaining viable tumor cells were quantified by a luminescence assay.
  • Table II ECso values for MH6T TriTAC directed killing of MSLN-expressing ovarian cancer cell lines by T cells from 5 different healthy donors. Represented graphs of the raw data are provided in Figs. 3 and 4.
  • Example 5 MH6T TriTAC directs T cells to kill cells expressing MSLN but not cells that do not express MSLN
  • T cells from a healthy donor was incubated with target cancer cells that express MSLN (Caov3 cells, Caov4 cells, OVCAR3 cells, and OVCAR8 cells) or target cancer cells that do not express MSLN (NCI-H510A cells, MDAPCa2b cells).
  • target cancer cells that express MSLN
  • target cancer cells that do not express MSLN NCI-H510A cells, MDAPCa2b cells.
  • Varying amounts of the MH6T TriTAC (SEQ ID NO: 98) molecule was added to the mixture of T cells and target cancer cells listed above. The mixture was incubated for 48 hours at 37 °C. After 48 hours, the remaining viable target cancer cells were quantified using a luminescent assay.
  • the MH6 TriTAC molecule was able to direct T cells to kill MSLN expressing target cancer cells (i.e., Caoc3, Caov4, OVCAR3, and OVCAR8 cells, as shown in Fig. 5).
  • MSLN expressing target cancer cells i.e., Caoc3, Caov4, OVCAR3, and OVCAR8 cells, as shown in Fig. 5.
  • the MH6T TriTAC molecule was not able to direct T cells to kill MSLN non-expressing target cancer cells (MDAPCa2b and NCI-H510A cells), also shown in
  • Table III ECso values for MH6T TriTAC directed T cell killing of MSLN-expressing cancer cell lines.
  • Example 6 MTT6T TriTAC directed T cells from cynomolgus monkeys to kill human ovarian cancer cell lines
  • peripheral blood mononuclear cells (PBMCs; T cells are a component of the PBMCs) from a cynomolgus monkey donor was mixed with target cancer cells that express MSLN (CaOV3 cells and OVCAR3 cells) and varying amounts of the MH6T TriTAC molecule (SEQ ID NO: 98) was added to the mixture, and incubated for 48 hours at 37 °C.
  • a mixture of cynomolgus PBMCs and MSLN expressing cells, as above were incubated with varying amounts of a control TriTAC molecule GFP TriTAC (SEQ ID NO: 99) that targets GFP, for 48 hours at 37 °C.
  • Target cancer cells used in this assay were engineered to express luciferase. After 48 hours, the remaining viable target cells were quantified using a luminescence assay.
  • MH6 TriTAC molecule was able to efficiently direct cynomolgus PBMCs to kill MSLN expressing cells (i.e., Caov3 and OVCAR, as shown in Fig.
  • the EC50 values for the MH6T TriTAC molecule was 2.9 pM for OVCAR3 cells and 3.0 pM for Caov3 cells, which were not significantly different that EC50 values observed with human T cells, as shown in Table II.
  • Example 7 MTT6T TriTAC molecule directed killing of MSLN-expressing NCI-H2052 mesothelioma cells by T cells in the presence or absence of human serum albumin [00170]
  • HSA human serum albumin
  • MH6T TriTAC molecule impacted the ability of the MH6T TriTAC molecule to direct T cells to kill MSLN-expressing cells.
  • NCI-H2052 mesothelioma cells used in this study were engineered to express luciferase.
  • T cells from a healthy donor and MSLN expressing cells were mixed and varying amounts of the MH6T TriTAC (SEQ ID NO: 98) molecule was added to the mixture.
  • the mixture was incubated for 48 hours at 37 °C, in presence or absence of HSA.
  • a mixture of NCI-H2052 cells and T cells were also incubated for 48 hours at 37 °C with a control trispecific molecule, GFP TriTAC (SEQ ID NO: 99), which targets GFP, in presence or absence of HSA.
  • GFP TriTAC SEQ ID NO: 99
  • Table IV ECso values for MH6T TriTAC directed killing of MSLN-expressing cancer cells by T cells in the presence or absence of HSA
  • Example 8 T cells from 4 different donors secrete TNF-alpha in the presence of MH6T TriTAC and MSLN-expressing Caov4 cells
  • the target cancer cells CaOv4 used in this assay were engineered to express luciferase.
  • T cells from 4 different healthy donors (donor 02, donor 86, donor 35, and donor 81) and Caov4 cells were mixed together and varying amounts of the MH6T TriTAC molecule (SEQ ID NO: 98) was added and the mixture was incubated for 48 hours at 37 °C.
  • Caov4 cells and T cells were also incubated for 48 hours at 37 °C with a control trispecific molecule, GFP TriTAC (SEQ ID NO: 99), which targets GFP.
  • Conditioned medium from the TDCC assay was collected at 48 hours, before measuring the target cancer cell viability, using a luminescence assay. The concentration of TNF-a in the conditioned medium was measured using an AlphaLISA assay kit (Perkin Elmer).
  • TDCC assays were also set up for additional MSLN expressing cell lines (Caov3 cells, OVCAR3 cells, and OVCAR8 cells) and similar TNF-a expression was observed.
  • the ECso values for MH6T TriTAC induced expression of TNF-a are presented in Table V.
  • the assay was carried out using cancer cells that do not express MSLN (NCI-H510A cells, or MDAPCa2b cells), no MH6T TriTAC directed secretion of TNF-a was observed (data not shown).
  • this study demonstrated that the MH6T TriTAC molecule was able to activate T cells in the presence of MSLN-expressing target cancer cells.
  • Table V ECso values for MH6T TriTAC molecule induced expression of TNF-a by T cells from 4 different T cell donors and 4 different MSLN-expressing cell lines
  • Example 9 Activation of CD69 expression on T cells from 4 different donors in presence of MH6T TriTAC and MSLN-expressing OVCAR8 cells
  • the OVCAR8 cells used in this assay were engineered to express luciferase.
  • T cells from 4 different healthy donors donor 02, donor 86, donor 35, and donor 81
  • OVCAR8 cells were mixed together and varying amounts of the MH6T TriTAC molecule (SEQ ID NO: 98) was added and the mixture was incubated for 48 hours at 37 °C.
  • OVCAR8 cells and T cells were also incubated for 48 hours at 37 °C with a control trispecific molecule, GFP TriTAC (SEQ ID NO: 99), which targets GFP.
  • T cells were collected, and CD69 expression on the T cells was measured by flow cytometry.
  • CD69 expression was detected on T cells from all 4 healthy donors in presence of OVCAR8 cells and the MH6T TriTAC molecule but not in presence of the negative control GFP TriTAC and OVCAR8 cells, as shown in Fig. 9.
  • TDCC assays were also set up for additional MSLN expressing cells (Caov3 cells, OVCAR3 cells, and OVCAR8 cells) and similar CD69 expression was observed.
  • the ECso values for MH6T TriTAC induced activation of CD69 in Caov3 cells and OVCAR8 cells are presented in Table VI.
  • Table VI EC50 values for activation of CD69 expression on T cells from 4 different donors in presence of MH6T TriTAC molecule and MSLN-expressing OVCAR8 cells or Caov3 cells.
  • certain target cancer cells that express MSLN (Caov3 cells, CaOV4 cells, OVCAR3 cells, and OVCAR8 cells) and certain cancer cells that do not express MSLN (MDAPCa2b cells, and NCI-H510A cells) were incubated with the MH6 TriTAC molecule (SEQ ID NO: 98) or a control GFP TriTAC molecule (SEQ ID NO: 99). Following incubation, the cells were washed to remove unbound MH6T or GFP TriTAC molecules and further incubated with a secondary antibody conjugated to Alexa Fluor 647, which is able to recognize the anti -albumin domain in the TriTAC molecules,. Binding of the MH6T TriTAC or that of GFP TriTAC to the MSLN expressing or MSLN non-expressing cells was measured by flow cytometry.
  • Fig. 10A top left panel shows binding of MH6T TriTAC to Caov3 cells; top right panel shows binding of MH6T TriTAC to Caov4 cells; bottom left panel shows binding of MH6T TriTAC to OVCAR3 cells; bottom right panel shows binding of MH6T TriTAC to OVCAR8 cells); and no binding was observed in cell lines that do not express MSLN (left panel shows lack of binding of MH6T TriTAC to MDAPCa2b cells and the right panel shows lack of binding of MH6T TriTAC to NCI-H510A cells), as shown in Fig.
  • Example 11 Measurement of MH6T TriTAC binding to T cells from donors [00180]
  • T cells from 4 health donors were incubated with the MH6 TriTAC molecule (SEQ ID NO: 98) or a buffer, as negative control. Following incubation, the cells were washed to remove unbound MH6T TriTAC molecules and further incubated with an Alexa Fluor 647 conjugated secondary antibody, which is able to recognize the anti-albumin domain in the MH6T TriTAC molecule. Binding of the MH6T TriTAC to the cells was measured by flow cytometry.
  • FIG. 11 top left panel shows binding of MH6T TriTAC to T cells from donor 2; top right panel shows binding of MH6T TriTAC to T cells from donor 35; bottom left panel shows binding of MH6T TriTAC to T cells from donor 41; bottom right panel shows binding of MH6T TriTAC to T cells from donor 81).
  • Example 12 Inhibition of tumor growth in mice treated with MTT6T TriTAC molecule
  • 10 7 NCI-H292 cells and 10 7 human PBMCs were co-implanted subcutaneously in two groups of NCG mice (8 mice per group). After 5 days, mice in one group were injected with the MH6T TriTAC molecule (SEQ ID NO: 98), daily for 10 days (days 5-14) at a dose of 0.25 mg/kg; and mice in the other group were injected with a vehicle control. Tumor volumes were measured after every few days and the study was terminated at day 36. Significant inhibition of tumor growth was observed in the mice injected with the MH6 TriTAC molecules, compared to those injected with the vehicle control, as shown in Fig. 12.
  • Example 13 Pharmacokinetics of MH6T TriTAC in cynomolgus monkeys
  • two cynomolgus monkeys were injected with 10 mg/kg dose of MH6T TriTAC molecule (SEQ ID NO: 98), intravenously, and serum samples were collected at various time points after the injection.
  • the amount of the MH6T TriTAC in the serum was measured using anti-idiotype antibodies recognizing the MH6T TriTAC molecule, in an electrochemiluminescient assay.
  • Fig. 13 shows a plot for the serum M6HT TriTAC levels at various time points. The data was then used to calculate the pharmacokinetic properties of MH6T TriTAC molecule, as provided in Table VII.
  • TriTAC 74 SEQ ID NO: 100
  • TriTAC 75 SEQ ID NO: 101
  • TDCC assays were carried out with the TriTAC 74 and TriTAC 75 molecules, using SKOV3 and OVCAR cells.
  • Fig. 14 shows the EC50 values obtained in the TDCC assays.
  • Example 12 MSLN trispecific antigen-binding protein Phase l/2a dose escalation, expansion, safety and pharmacokinetics study
  • Target population is patients with: platinum refractory or platinum resistant epithelial ovarian, fallopian tube, or primary peritoneal cancer; unresectable, locally advanced or metastatic pancreatic adenocarcinoma progressing on or after frontline treatment; malignant pleural or peritoneal mesothelioma with epithelioid histology progressing on or after frontline platinum-based chemotherapy.
  • Trial Design MSLN trispecific antigen-binding protein Phase l/2a trial design is shown in Figure 16. Trail objectives are assessing safety and tolerability at increasing dose levels, generating pharmacokinetic and pharmacodynamic date and evaluate preliminary anti tumor activity.
  • Dosing, administration MSLN trispecific antigen-binding protein (SEQ ID NO: 98) was administered once weekly, for one-hour IV infusion. The starting dose of 6ng/kg was established by minimally anticipated biological effect level.
  • Table IX shows the dosing cohorts and number of subjects. A total number of 60 subjects participated in the trial, including 8.13% mesothelioma, 28.47% ovarian cancers and 24.4% pancreatic cancers.
  • Table IX MSLN trispecific antigen-binding protein dosing cohorts
  • Figure 17 shows the patients time on treatment from clinical database for platinum relapsed/refractory ovarian cancer. Five of 27 (19%) of evaluable patients stay on treatment after 24 weeks.
  • Figure 18 illustrates percent change of target lesion after MSLN trispecific antigen binding protein treatment for ovarian cancer. Target lesion reductions were observed.
  • Figure 19 illustrates the pharmacokinetic data of the MSLN tri specific antigen-binding protein for the different dosing cohorts.
  • Figure 19A illustrates the Mean (SD) Cmax.
  • Figure 19B illustrates the Mean (SD) AUClast. It is observed that dose increase proportionally in Cmax and exposure (AUC) for all fixed dose cohorts, first priming dose and target dose of step dose cohorts.
  • Mean Tl/2 is 71 +/- 30 hrs.
  • Median Tl/2 is 68 hrs (14 - 181 hrs).
  • Tl/2, clearance rate, and volume of distribution are independent of dose.

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Abstract

L'invention concerne des protéines trispécifiques ciblant la mésothéline (MSLN), comprenant un domaine se liant à CD3, un domaine d'extension de demi-vie et un domaine se liant à la MSLN. L'invention concerne également des compositions pharmaceutiques associées, ainsi que des acides nucléiques, des vecteurs d'expression recombinants et des cellules hôtes permettant d'obtenir de telles protéines trispécifiques ciblant la MSLN. L'invention concerne en outre des méthodes d'utilisation des protéines trispécifiques ciblant la MSLN dans la prévention et/ou le traitement de maladies, d'états pathologiques et de troubles.
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