EP1740220A2 - Non-natural ribonuclease conjugates as cytotoxic agents - Google Patents
Non-natural ribonuclease conjugates as cytotoxic agentsInfo
- Publication number
- EP1740220A2 EP1740220A2 EP05779321A EP05779321A EP1740220A2 EP 1740220 A2 EP1740220 A2 EP 1740220A2 EP 05779321 A EP05779321 A EP 05779321A EP 05779321 A EP05779321 A EP 05779321A EP 1740220 A2 EP1740220 A2 EP 1740220A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- ribonuclease
- composition
- cell
- human
- cells
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
- C12N9/00—Enzymes; Proenzymes; Compositions thereof; Processes for preparing, activating, inhibiting, separating or purifying enzymes
- C12N9/14—Hydrolases (3)
- C12N9/16—Hydrolases (3) acting on ester bonds (3.1)
- C12N9/22—Ribonucleases RNAses, DNAses
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
- A61K47/00—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient
- A61K47/50—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates
- A61K47/51—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent
- A61K47/68—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent the modifying agent being an antibody, an immunoglobulin or a fragment thereof, e.g. an Fc-fragment
- A61K47/6801—Drug-antibody or immunoglobulin conjugates defined by the pharmacologically or therapeutically active agent
- A61K47/6803—Drugs conjugated to an antibody or immunoglobulin, e.g. cisplatin-antibody conjugates
- A61K47/6811—Drugs conjugated to an antibody or immunoglobulin, e.g. cisplatin-antibody conjugates the drug being a protein or peptide, e.g. transferrin or bleomycin
- A61K47/6815—Enzymes
Definitions
- the present invention is directed toward the delivery of a toxic protein to pathogenic cells, particularly cancer cells.
- the toxic protein is a ribonuclease that has been modified to make it toxic to target cells and that can be conjugated to a target cell-specific delivery vector, such as an antibody, for delivery to pathogenic cells.
- chemotherapy simply means the treatment of disease with chemical substances.
- the present invention relates to the use (e.g., therapeutic use, diagnostic use, research use) of proteins to target cancers and other diseases and conditions (e.g., viral or pathogen infections) where selectively killing pathogenic cells is desired.
- the present invention relates to the production and delivery of a cytotoxic protein to pathogenic cells such as tumor cells or virus-infected cells.
- the ribonuclease can also be used to degrade pathogenic RNA outside of the cell.
- the present invention provides the use of ribonuclease proteins (e.g., human ribonuclease proteins) that are altered in their amino acid sequence (i.e., non-natural) to make them cytotoxic.
- these mutated proteins are specifically delivered to pathogenic cells by conjugation to targeting vectors (e.g., human or humanized protein) that are specific for or at least partially selective for the pathogenic target cells.
- targeting vectors include, but are not limited to, antibodies, receptors, ligands, peptides, nucleic acids, lipids, polymers, small molecules, and synthetic compounds.
- mutant ribonuclease genes are delivered as DNA or RNA via expression vectors.
- the ribonuclease genes may be expressed alone, or may be expressed as chimerical conjugates of the ribonuclease gene with a cell-specific targeting moiety.
- the present invention also provides methods comprising the delivery of the cytotoxic ribonucleases under conditions that minimize or eliminate the human immune response against the proteins and delivery vectors.
- This present invention further provides methods for selective inhibition of cellular growth and/or viral replication in target cells through the action of the mutated ribonucleases.
- the present invention provides a novel family of proteins for treating, characterizing, or understanding disease.
- the compositions of the present invention are used therapeutically, alone or in combination with other compounds or interventions (e.g., to augment existing therapies for treatment of human cancers).
- the present invention provides a composition comprising a non-natural ribonuclease (e.g., human ribonuclease) conjugated to a cell-specific targeting moiety, wherein the ribonuclease is configured to kill the cell.
- the non-natural human ribonuclease comprises a non-natural human ribonuclease one (RNase 1).
- RNase 1 examples include, but are not limited to, those having a variant sequence compared to a natural ribonuclease one as shown in Table 1.
- a plurality of different ribonucleases and/or targeting moieties are provided in a composition (e.g., a kit, a pharmaceutical preparation, etc.)
- the present invention is not limited by the nature of or location of the target cell.
- the cell is a cancer cell, a cell that expresses a marker associated with viral infection, a cell that is associated with an inflammatory response, and a cell is associated with an autoimmune disease (e.g., a cell expressing markers or otherwise characterized as aberrantly failing to undergo cell death or presenting autoantigens).
- the cell resides in vitro (e.g., in culture).
- the cell resides in vivo (e.g., in a tissue, as a transplanted cell, in a test animal, in a subject suspected of or diagnosed as having a disease or condition — e.g., cancer).
- the ribonuclease is conjugated to the cell-specific targeting moiety by a linker.
- the present invention is not limited by the nature of the linker.
- Linkers suitable for use with the present invention include, but are not limited to, linkers attached to a non-native cysteine of the ribonuclease, non-cleavable linkers, cleavable linker, and linkers attached within a loop region of the ribonuclease corresponding to amino acids
- the ribonuclease is made as a fusion protein with a disease- specific protein, such as an antibody or antibody fragment.
- a disease-specific protein such as an antibody or antibody fragment.
- the present invention is not limited by the nature of the cell-specific targeting moiety.
- Targeting moieties include, but are not limited to, immunoglobulms (e.g., antibodies, humanized or partially humanized antibodies, antibody fragments, etc.), proteins, peptides, receptor ligands, aptamers, small molecules, nucleic acid molecules, lipids, etc.
- the components of the composition e.g., the ribonuclease, the cell specific-targeting moieity
- the present invention further provides methods of killing cell using any of the compositions discussed herein.
- FIGURES Figure 1A shows a graph demonstrating the growth inhibiting effect of QBI-119 on tumor volume (A549 cells) over a number of days, and Figure IB shows a graph depicting the lack of toxicity of QBI-119.
- Figure 2 A shows a graph demonstrating the growth inhibiting effect of QBI-119 on tumor volume (Bx-PC-3 cells) over a number of days, and Figure 2B shows a graph depicting the lack of toxicity of QBI-119.
- Immunoglobulin refers to proteins that bind a specific antigen.
- Immunoglobulins include, but are not limited to, polyclonal, monoclonal, chimeric, and humanized antibodies, Fab fragments, F(ab') 2 fragments, and includes immunoglobulins of the following classes: IgG, IgA, IgM, IgD, IbE, and secreted immunoglobulins (slg).
- Immunoglobulins generally comprise two identical heavy chains and two light chains.
- antibody and “immunoglobulin” also encompass single chain antibodies and two chain antibodies.
- antigen binding protein refers to proteins that bind to a specific antigen.
- Antigen binding proteins include, but are not limited to, immunoglobulins, including polyclonal, monoclonal, chimeric, and humanized antibodies; Fab fragments, F(ab') 2 fragments, and Fab expression libraries; and single chain antibodies.
- epipe refers to that portion of an antigen that makes contact with a particular immunoglobulin.
- an antigenic determinant may compete with the intact antigen (i.e., the "immunogen" used to elicit the immune response) for binding to an antibody.
- telomere binding when used in reference to the interaction of an antibody and a protein or peptide means that the interaction is dependent upon the presence of a particular structure (i.e., the antigenic determinant or epitope) on the protein; in other words the antibody is recognizing and binding to a specific protein structure rather than to proteins in general. For example, if an antibody is specific for epitope "A,” the presence of a protein containing epitope A (or free, unlabelled A) in a reaction containing labeled "A" and the antibody will reduce the amount of labeled A bound to the antibody.
- non-specific binding and background binding when used in reference to the interaction of an antibody and a protein or peptide refer to an interaction that is not dependent on the presence of a particular structure (i.e., the antibody is binding to proteins in general rather that a particular structure such as an epitope).
- the term “subject” refers to any animal (e.g., a mammal), including, but not limited to, humans, non-human primates, rodents, and the like, which is to be the recipient of a particular treatment.
- the terms “subject” and “patient” are used interchangeably herein in reference to a human subject.
- the term "subject suspected of having cancer” refers to a subject that presents one or more symptoms indicative of a cancer (e.g., a noticeable lump or mass) or is being screened for a cancer (e.g., during a routine physical).
- a subject suspected of having cancer may also have one or more risk factors.
- a subject suspected of having cancer has generally not been tested for cancer.
- a "subject suspected of having cancer” encompasses an individual who has received a preliminary diagnosis (e.g., a CT scan showing a mass or increased PSA level) but for whom a confirmatory test (e.g., biopsy and/or histology) has not been done or for whom the stage of cancer is not known.
- the term further includes people who once had cancer (e.g., an individual in remission).
- a "subject suspected of having cancer” is sometimes diagnosed with cancer and is sometimes found to not have cancer.
- the term "subject diagnosed with a cancer” refers to a subject who has been tested and found to have cancerous cells. The cancer may be diagnosed using any suitable method, including but not limited to, biopsy, x-ray, blood test, and the diagnostic methods of the present invention.
- a “preliminary diagnosis” is one based only on visual (e.g., CT scan or the presence of a lump) and antigen tests (e.g., PSA).
- the term “subject at risk for cancer” refers to a subject with one or more risk factors for developing a specific cancer.
- Risk factors include, but are not limited to, gender, age, genetic predisposition, environmental exposure, and previous incidents of cancer, preexisting non-cancer diseases, and lifestyle.
- non-human animals refers to all non-human animals including, but are not limited to, vertebrates such as rodents, non-human primates, ovines, bovines, ruminants, lagomorphs, porcines, caprines, equines, canines, felines, aves, etc.
- the term “gene transfer system” refers to any means of delivering a composition comprising a nucleic acid sequence to a cell or tissue.
- gene transfer systems include, but are not limited to, vectors (e.g., retroviral, adenoviral, adeno- associated viral, and other nucleic acid-based delivery systems), microinjection of naked nucleic acid, polymer-based delivery systems (e.g., liposome-based and metallic particle- based systems), biolistic injection, and the like.
- vectors e.g., retroviral, adenoviral, adeno- associated viral, and other nucleic acid-based delivery systems
- microinjection of naked nucleic acid e.g., polymer-based delivery systems (e.g., liposome-based and metallic particle- based systems), biolistic injection, and the like.
- viral gene transfer system refers to gene transfer systems comprising viral elements (e.g. , intact viruses, modified viruses and viral components such as nucleic acids or proteins) to facilitate delivery of the sample to a desired cell or tissue.
- adenovirus gene transfer system refers to gene transfer systems comprising intact or altered viruses belonging to the family Adenoviridae.
- Amino acid sequence and tenns such as “polypeptide” or “protein” are not meant to limit the amino acid sequence to the complete, native amino acid sequence associated with the recited protein molecule.
- test compound and “candidate compound” refer to any chemical or biological entity, pharmaceutical, drug, and the like that is a candidate for use to treat or prevent a disease, illness, sickness, or disorder of bodily function (e.g., cancer).
- Test compounds comprise both known and potential therapeutic compounds.
- a test compound can be determined to be therapeutic by screening using the screening methods of the present invention.
- sample is used in its broadest sense. In one sense, it is meant to include a specimen or culture obtained from any source, as well as biological and environmental samples. Biological samples may be obtained from animals (including humans) and encompass fluids, solids, tissues, and gases. Biological samples include blood products, such as plasma, serum and the like. Environmental samples include environmental material such as surface matter, soil, water and industrial samples. Such examples are not however to be construed as limiting the sample types applicable to the present invention.
- gene refers to a nucleic acid (e.g., DNA) sequence that comprises coding sequences necessary for the production of a polypeptide or precursor (e.g., ribonucleases or ribonuclease conjugates of the present invention).
- the polypeptide can be encoded by a full length coding sequence or by any portion of the coding sequence so long as the desired activity or functional properties (e.g., enzymatic activity, etc.) of the full-length or fragment are retained.
- the term also encompasses the coding region of a structural gene and the including sequences located adjacent to the coding region on both the 5' and 3' ends for a distance of about 1 kb on either end such that the gene corresponds to the length of the full- length mRNA.
- the sequences that are located 5' of the coding region and which are present on the mRNA are referred to as 5' untranslated sequences.
- the sequences that are located 3' or downstream of the coding region and that are present on the mRNA are referred to as 3' untranslated sequences.
- gene encompasses both cDNA and genomic forms of a gene.
- a genomic form or clone of a gene contains the coding region interrupted with non- coding sequences termed "introns” or “intervening regions” or “intervening sequences.”
- Introns are segments of a gene that are transcribed into nuclear RNA (hnRNA); introns may contain regulatory elements such as enhancers. Introns are removed or “spliced out” from the nuclear or primary transcript; introns therefore are absent in the messenger RNA (mRNA) transcript.
- mRNA messenger RNA
- the mRNA functions during translation to specify the sequence or order of amino acids in a nascent polypeptide.
- wild-type refers to a gene or gene product that has the characteristics of that gene or gene product when isolated from a naturally occurring source.
- a wild-type gene is that which is most frequently observed in a population and is thus arbitrarily designed the "normal” or “wild-type” form of the gene.
- the terms "modified”, “mutant”, and “variant” refer to a gene or gene product that displays modifications in sequence and or functional properties (z ' .e., altered characteristics) when compared to the wild-type gene or gene product. It is noted that naturally-occurring mutants can be isolated; these are identified by the fact that they have altered characteristics when compared to the wild-type gene or gene product. This is in contrast to synthetic mutants that are changes made in a sequence through human (or machine) intervention.
- fragment refers to a polypeptide that has an amino-terminal and/or carboxy-terminal deletion as compared to the native protein, but where the remaining amino acid sequence is identical to the corresponding positions in the amino acid sequence deduced from a full-length cDNA sequence. Fragments typically are at least 4 amino acids long, preferably at least 20 amino acids long, usually at least 50 amino acids long or longer, and span the portion of the polypeptide required for intermolecular binding of the compositions with its various ligands and/or substrates. As used herein, the term “purified” or “to purify” refers to the removal of impurities and contaminants from a sample.
- antibodies are purified by removal of non- immunoglobulin proteins; they are also purified by the removal of immunoglobulin that does not bind an intended target molecule.
- the removal of non-immunoglobulin proteins and/or the removal of immunoglobulins that do not bind an intended target molecule results in an increase in the percent of target-reactive immunoglobulins in the sample.
- recombinant polypeptides are expressed in host cells and the polypeptides are purified by the removal of host cell proteins; the percent of recombinant polypeptides is thereby increased in the sample.
- expression vector refers to a recombinant DNA molecule containing a desired coding sequence and appropriate nucleic acid sequences necessary for the expression of the operably linked coding sequence in a particular host organism.
- Nucleic acid sequences necessary for expression in prokaryotes usually include a promoter, an operator (optional), and a ribosome-binding site, often along with other sequences.
- Eukaryotic cells are known to utilize promoters, enhancers, and termination and polyadenylation signals.
- the term "host cell” refers to any eukaryotic or prokaryotic cell (e.g., bacterial cells such as E. coli, yeast cells, mammalian cells, avian cells, amphibian cells, plant cells, fish cells, and insect cells), whether located in vitro ' or in vivo.
- host cells may be located in a transgenic animal.
- the present invention is directed toward the delivery of a toxic protein to pathogenic cells, particularly cancer cells.
- the toxic protein may also have benefit when delivered to diseased areas without being toxic to the diseased cells.
- the toxic protein is a ribonuclease that has been modified to make it toxic to target cells and that can be conjugated to a target cell-specific delivery vector, such as an antibody, for delivery to pathogenic cells.
- Preferred embodiments of the present invention are based on the conversion of naturally occurring ribonucleases (e.g., human ribonucleases) into toxic proteins that are used to treat or cure diseases, particularly cancer and viral infections.
- compositions also find use in diagnostic applications (e.g., associated with drug screening or cancer characterization) and research applications.
- These ribonucleases can be used as stand alone reagents or they may be incorporated into general or specific delivery systems such as polymers, dendrimers, liposomes, polymeric nanoparticles, or block copolymer micelles.
- a feature of these proteins is that they are proteins that have been engineered to be toxic to the cells to which they are delivered. This feature provides a toxin conjugate that is less susceptible to naturally occurring inhibitors of the toxin.
- Another feature is that their starting point was preferably a natural protein (e.g., a natural human protein) and not a non-natural (e.g., non-human) protein that had to be modified (e.g., humanized) significantly to escape the immune system.
- a natural protein e.g., a natural human protein
- a non-natural protein e.g., non-human protein that had to be modified (e.g., humanized) significantly to escape the immune system.
- One embodiment of this invention is to combine these protein toxins with antibodies (e.g., humanized or human antibodies) for targeting to specific pathogenic cells.
- antibodies e.g., humanized or human antibodies
- the present invention provides conjugates of the EVADE human ribonuclease (Quintessence Biosciences, Madison, Wisconsin) with a targeting component.
- the EVADE human ribonucleases exhibit improved efficacy compared to the amphibian ribonucleases because the specific ribonucleolytic activity is higher and the likelihood of side effects and inducing a human immune response is lower, i addition, binding to the native inhibitor, ribonuclease inhibitor, is disrupted for the EVADE ribonucleases.
- the EVADE ribonucleases inhibit the cellular growth of the tumors and also enhances the anti-cancer effects of conventional therapies, including chemotherapy and radiation. It is also contemplated that EVADE human ribonucleases are not retained in the human kidney, as are amphibian ribonucleases.
- Renal toxicity of the amphibian ribonucleases is dose limiting in mice and humans. With conventional chemotherapy, it is often a problem that membrane based drug pumps can eliminate the small molecule anti-cancer drugs from the cancerous cell. This requires that higher doses of the toxic drugs be used. Like the amphibian ribonuclease, it is expected that the EVADE ribonucleases are able to make these resistant cells susceptible to standard levels of treatment so that lower doses are effective and side effects reduced. In addition, the EVADE ribonucleases are contemplated to provide benefit when used in combination with radiotherapy or other convention interventions.
- compositions and methods of the present invention are used to treat diseased cells, tissues, organs, or pathological conditions and/or disease states in a subject organism (e.g., a mammalian subject including, but not limited to, humans and veterinary animals), or in in vitro and/or ex vivo cells, tissues, and organs.
- a subject organism e.g., a mammalian subject including, but not limited to, humans and veterinary animals
- various diseases and pathologies are amenable to treatment or prophylaxis using the present methods and compositions.
- a non-limiting exemplary list of these diseases and conditions includes, but is not limited to, breast cancer, prostate cancer, lymphoma, skin cancer, pancreatic cancer, colon cancer, melanoma, malignant melanoma, ovarian cancer, brain cancer, primary brain carcinoma, head-neck cancer, glioma, glioblastoma, liver cancer, bladder cancer, non-small cell lung cancer, head or neck carcinoma, breast carcinoma, ovarian carcinoma, lung carcinoma, small-cell lung carcinoma, Wilms' tumor, cervical carcinoma, testicular carcinoma, bladder carcinoma, pancreatic carcinoma, stomach carcinoma, colon carcinoma, prostatic carcinoma, genitourinary carcinoma, thyroid carcinoma, esophageal carcinoma, myeloma, multiple myeloma, adrenal carcinoma, renal cell carcinoma, endometrial carcinoma, adrenal cortex carcinoma, malignant pancreatic insulinoma, malignant carcinoid carcinoma, choriocarcinoma, mycosis fungoides, malignant hypercalcemia, cervical hyperplasia, leuk
- the cancer cells being treated are metastatic.
- the ribonuclease or ribonuclease conjugates of the present invention are co-administered with other medical interventions, either simultaneously or sequentially.
- any oncolytic agent that is routinely used in a cancer therapy may be co-administered with the compositions and methods of the present invention.
- the U.S. Food and Drug Administration maintains a formulary of oncolytic agents approved for use in the United States. International counterpart agencies to the U.S.F.D.A. maintain similar formularies. Table 4 provides a list of exemplary antineoplastic agents approved for use in the U.S.
- a current and still developing approach to cancer therapy involves using cancer cell- specific reagents to target a malignant tumor. These toxic reagents can be produced by attaching a toxic payload to a cell-specific delivery vector.
- tumor-specific targeting proteins including antibodies, antibody fragments, and ligands for cell surface receptors have been developed and clinically tested.
- These targeting molecules have been conjugated to several classes of therapeutic toxins such as small molecule drugs, enzymes, radioisotopes, protein toxins, and other toxins for specific delivery to patients. While these efforts have made meaningful inroads to treat cancers, significant challenges lie ahead to develop more effective toxins, to create more robust and specific delivery systems, and to design therapeutic proteins and protein vectors that evade immune surveillance in humans.
- Ribonuclease (RNase) proteins have been tested as human therapeutics because they selectively target tumor cells; this has been demonstrated most clearly with an RNase from Ranapipiens early embryos.
- Ranapipiens is a species of leopard frogs and its embryonic RNase is distantly related to the more highly conserved bovine and human pancreatic ribonucleases.
- pancreatic-type ribonucleases such as RNase A, are secretory enzymes that catalyze the degradation of RNA to ribonucleotides and their activity is inhibited by binding to ribonuclease inhibitor (RI), a ubiquitous cytosolic protein.
- RI ribonuclease inhibitor
- Ribonuclease inhibitor binds exceptionally tight to pancreatic-type RNases, abating their activity and thereby making them non-toxic to normal or cancer cells. If the RNase activity is inhibited, the cellular RNA is undamaged and the cell remains viable. In normal cells the ribonuclease activity is tightly controlled, but if ribonuclease activity is uncontrolled, the ribonucleolytic activity destroys cellular RNA and kills the cell.
- the frog (Rana pipiens) ribonuclease when placed in a human cell, is not strongly inhibited by RI and its RNase activity destroys cellular RNA and kills the target cell.
- Ranpirnase is generic name of the pharmaceutical that is described and claimed in U.S. Pat. No. 5,559,212 and that is presently known by the registered trademark ONCONASE.
- the second approach is to mutate mammalian ribonucleases so that they maintain high levels of ribonucleolytic activity but are not significantly inhibited by human ribonuclease inhibitor.
- the present invention provides ribonuclease conjugates that are derived from mutated RNases that exhibit low immunogenicity and side effects and still maintain high ribonucleolytic activity resulting in cancer-specific toxicity. Certain preferred embodiments of the present invention are described below. While these embodiments are illustrated with variant human ribonuclease proteins and antibody targeting moieties, the present invention is not so limited.
- Antibodies are glycoprotein molecules produced by white blood cells (B- lymphocytes) of the immune system and their function is to recognize and bind to matter harmful to the organism. Once an antigen is marked by an antibody, it is destroyed by other components of the immune system. A typical organism makes millions of different antibodies, each designed to bind a specific epitope (or antigenic detenninant) on the foreign antigen. Antibodies naturally combine specificity (the ability to extremely discriminate diverse harmful molecules) and affinity (the ability to tightly lock onto those targets) with the ability to recruit effector functions of the immune system such as antibody- and complement- mediated cytolysis and antibody-dependent cell-mediated cytotoxicity (ADCC).
- B- lymphocytes white blood cells
- ADCC antibody-dependent cell-mediated cytotoxicity
- a "toxic payload" such as a radioactive element or a toxin
- a "toxic payload” such as a radioactive element or a toxin
- the following table lists the mechanisms of some cancer therapeutic antibodies, including three antibody conjugates that carry a toxic payload for lymphomas and leukemias. (Drag Discovery Today, Vol. 8, No. 11 June 2003). Two of the conjugates, ZEVALIN and BEXXAR, carry radioactive iodine as the toxin and the third, MYLOTARG, carries a cytotoxic antitumor antibiotic, calicheaminin which is isolated from a bacterial fermentation.
- the Mylotarg antibody binds specifically to the CD33 antigen which is expressed on the surface of leukemic blasts that are found in more than 80% of patients with acute myeloid leukemia (AML).
- the antibody in this conjugate has approximately 98.3% of its amino acid sequences derived from human origins.
- any of the targeting antibodies or agents used in these products may also be employed by the compositions and methods of the present invention.
- the most specific method for targeting toxins is the use of monoclonal antibodies or antibody fragments that are designed to recognize surface antigens specific to tumor cells. Because normal cells lack the surface antigens, they are not targeted and killed by the toxin conjugate.
- Whole antibodies have two domains: a variable domain that gives the antibody its affinity and binding specificity and a constant domain that interacts with other portions of the immune system to stimulate immune responses in the host organism.
- the variable domain is composed of the complementarity determining regions (CDRs), which bind to the antibody's target, and a framework region that anchors the CDRs to the rest of the antibody and helps maintain CDR shape.
- CDRs complementarity determining regions
- the six CDR's in each antibody differ in length and sequence between different antibodies and are mainly responsible for the specificity (recognition) and affinity (binding) of the antibodies to their target markers.
- the functions of antibodies are reflected in their characteristic three-dimensional structure, which is ultimately determined by the primary sequence of amino acids and how .those amino acids fold into a functional 3-dimensional protein chain.
- a step in developing therapeutic monoclonal antibodies is to simultaneously optimize biochemical and cellular functions for anti-cancer performance and still keep the protein as humanlike as possible to minimize any anti-antibody human immune response.
- Monoclonal antibodies were originally produced in mice, but when they are used in human therapeutic applications, they present daunting obstacles. Mouse antibodies are recognized as foreign by the human immune system and thus they provoke the Human Anti- Mouse Antibody or HAMA reaction.
- the HAMA reaction alters the mouse monoclonal effectiveness and can cause severe adverse symptoms in the recipient.
- mouse antibodies are simply not as effective as human antibodies in mediating the human immune system to destroy the malignant cells.
- APC antigen presenting cell
- the efficiency of uptake is in turn influenced by the route of administration, the solubility (or aggregation) of the protein, its receptor binding specificity, and whether the protein is recognized by class II major histocompatibility complex (MHC) molecules, T-cell receptors (TCR), and B-cell receptors (BCR).
- MHC major histocompatibility complex
- TCR T-cell receptors
- BCR B-cell receptors
- One of the most straightforward ways to evade the human immune response is to make the therapeutic protein sequence and structure as humanlike as possible.
- Two main approaches have emerged to produce human or humanized therapeutic monoclonal antibodies, either used alone as a therapeutic or as a carrier for a toxin. . These include 1) 'humanizing' mouse or other non-human antibodies to make them compatible with the human immune system and 2) producing fully human antibodies in transgenic mice or by using genetic engineering methods in the laboratory.
- the processes have produced several categories of monoclonal antibodies. These include mouse, chimaeric, humanized and human antibodies
- Murine Monoclonal antibodies from mice and rats The original Kohler and Milstein technology from 1975 provided mouse monoclonal antibodies using a hybridoma technology. These have been used fherapeutically. In 1986, the first approved use of mouse monoclonals was for transplant patients whose immune system was suppressed to avoid organ rejection. Rodent antibodies tend to provoke strong Human anti-Murine Antibody (HAMA) immune responses that restrict their usefulness for repeated application in the same patient.
- HAMA Human anti-Murine Antibody
- Chimaeric Antibodies These are mutated antibodies in which the entire variable regions of a functional mouse antibody are joined to human constant regions. These antibodies have human effector functions from the constant (Fc regions) such as activating complement and recruiting immune cells.
- chimaeric antibodies also reduce the immunogenicity (HAMA) caused by the mouse constant region.
- Humanized / CDR grafted / Reshaped antibodies These antibodies are more humanlike than chimaeric antibodies because only the complementarity determining regions from the mouse antibody variable regions are combined with framework regions from human variable regions. Because these antibodies are more human-like than chimaeric antibodies, it is expected they could be designed to be less immunogenic when given to human in recurring therapeutic doses. Using computer modeling software to guide the humanization of murine antibodies or random shuffling of sequences followed by screening, it is possible to design an antibody that retains most or all of the binding affinity and specificity of the murine antibody but which is >90% human. 4.
- Human antibodies from immune donors Some antibodies have been rescued from immune human donors using either Epstein Barr Virus transformation of B-cells or by PCR cloning and phage display. By definition these antibodies are completely human in origin. 5.
- Fully human antibodies from phage libraries Synthetic phage libraries have been created which use randomized combinations of synthetic human antibody V- regions. By panning these libraries against a target antigen, these so called 'fully human antibodies' are assumed to be very human but possibly more diverse than natural antibodies. 6.
- Fully human antibodies from transgenic mice Transgenic mice have been created that have functional human immunoglobulin germline genes sequences. These transgenic mice produce human-like antibodies when immunized.
- the human antibodies produced by methods 4, 5, and 6 are typically most desired because they produce a starting antibody that contains no mouse or otherwise "foreign" protein sequences that should stimulate an immune response in human patient.
- This approach in 4, 5, and 6) also can bypass the challenge of substituting mouse CDR regions into human frameworks that often alters the 3-dimensional structure of the variable region, thereby changing the antibody's binding and specificity.
- This approach in 4, 5, 6) successfully produced an anti-CD3 antibody.
- the murine version elicited neutralizing antibodies after a single dose in all patients tested, while a humanized version was only immunogenic in 25% of patients following multiple injections.
- Another approach is to covalently modify the antibody surface with reagents such as polyethylene glycol (PEG) to suppress its antigenicity and improve its solubility. These biochemical modifications also can have several other benefits such as reduced toxicity, increased bioavailability, and improved efficacy.
- Another approach is to use antibody fragments in which the potentially antigenic parts of the mouse antibody, such as the constant region, have been removed. This approach typically works only when the regulatory components within the antibody constant region are not required for therapeutic efficacy. Neither of these approaches has proven completely satisfactory, which has driven the humanization effort to produce 'the ideal' antibody candidate mentioned above.
- toxic molecules can be delivered to cancer cells using several other specific and non-specific vectors including peptides, polymers, dendrimers, liposomes, polymeric nanoparticles, and block copolymer micelles.
- peptides that bind to the leutinizing hormone-releasing hormone have been used to target a small molecule toxin, camptothecin, to ovarian cancer cells (Journal of Controlled Release, 2003, 91, 61-73.).
- Ribonucleases that evade ribonuclease inhibitor protein are effective toxins in human cells, particularly against cancer cells.
- Non-natural Ribonuclease Polynucleotides As described above, a new family of non-natural ribonuclease proteins that have been discovered. This family was identified by structure-function analys for ribonuclease sequence with desired cytotoxic activities. Accordingly, the present invention provides nucleic acids encoding these novel non-natural ribonucleases, homologs, and variants (e.g., mutations and polyporphisms). In some embodiments, the present invention provides polynucleotide sequences encoding any of the amino acid sequences listed in Tables 1-3.
- the present invention also provides nucleic acid that are capable of hybridizing to such nucleic acid sequences under conditions of low to high stringency as long as the polynucleotide sequence capable of hybridizing encodes a protein that retains a biological activity of a ribonuclease (e.g., cytotoxic activity).
- the above nucleic acid molecules may also be associated with coding sequences of targeting molecules (e.g., antibodies) such that the produced amino acid sequence is a fusion between the ribonuclease and the targeting molecule.
- the nucleotide sequences of the present invention may be engineered in order to alter a ribonuclease coding sequence for a variety of reasons, including but not limited to, alterations which modify the cloning, processing and/or expression of the gene product.
- mutations may be introduced using techniques that are well known in the art (e.g., site-directed mutagenesis to insert new restriction sites, to change codon preference, etc.). It is contemplated that it is possible to modify the structure of a peptide having a function (e.g., ribonuclease function) for such purposes as increasing activity of the ribonuclease (e.g., cytotoxic activity).
- modified peptides are considered functional equivalents of peptides having an activity of a ribonuclease as defined herein.
- a modified peptide can be produced in which the nucleotide sequence encoding the polypeptide has been altered, such as by substitution, deletion, or addition, fn particularly preferred embodiments, these modifications do not significantly reduce the cytotoxic activity of the modified ribonuclease.
- construct "X" can be evaluated in order to determine whether it is a member of the genus of modified or variant ribonucleases of the present invention as defined functionally, rather than structurally.
- the activity of a variant ribonuclease is evaluated by any known screening method, including those described herein expressly or by reference.
- variant forms of ribonucleases as shown in Tables 2 and 3, are provided. Further variations of these compositions are contemplated, including structural and functional equivalents. For example, it is contemplated that isolated replacement of a leucine with an isoleucine or valine, an aspartate with a glutamate, a threonine with a serine, or a similar replacement of an amino acid with a structurally related amino acid (i.e., conservative mutations) will not have a major effect on the biological activity of the resulting molecule. Accordingly, some embodiments of the present invention provide variants of ribonucleases disclosed herein containing conservative replacements. Conservative replacements are those that take place within a family of amino acids that are related in their side chains.
- Genetically encoded amino acids can be divided into four families: (1) acidic (aspartate, glutamate); (2) basic (lysine, arginine, histidine); (3) nonpolar (alanine, valine, leucine, isoleucine, proline, phenylalanine, mefhionine, tryptophan); and (4) uncharged polar (glycine, asparagine, gluta ine, cysteine, serine, threonine, tyrosine). Phenylalanine, tryptophan, and tyrosine are sometimes classified jointly as aromatic amino acids.
- amino acid repertoire can be grouped as (1) acidic (aspartate, glutamate); (2) basic (lysine, arginine, histidine), (3) aliphatic (glycine, alanine, valine, leucine, isoleucine, serine, threonine), with serine and threonine optionally be grouped separately as aliphatic- hydroxyl; (4) aromatic (phenylalanine, tyrosine, tryptophan); (5) amide (asparagine, glutamine); and (6) sulfur-containing (cysteine and methionine) (e.g., Stryer ed., Biochemistry, pg.
- Whether a change in the amino acid sequence of a peptide results in a functional homolog can be readily determined by assessing the ability of the variant peptide to function in a fashion similar to the reference protein. Peptides having more than one replacement can readily be tested in the same manner. More rarely, a variant includes "nonconservative" changes (e.g., replacement of a glycine with a tryptophan). Analogous minor variations can also include amino acid deletions or insertions, or both.
- nucleotide sequences of the present invention may be engineered in order to alter a ribonuclease coding sequence including, but not limited to, alterations that modify the cloning, processing, localization, secretion, and/or expression of the gene product.
- Non-natural Ribonuclease Polypeptides are described in Tables 1-3.
- the present invention also provides fragments, fusion proteins or functional equivalents of these ribonuclease proteins.
- the polynucleotides of the present invention may be employed for producing polypeptides by recombinant techniques.
- the polynucleotide may be included in any one of a variety of expression vectors for expressing a polypeptide.
- vectors include, but are not limited to, chromosomal, nonchromosomal and synthetic DNA sequences (e.g., derivatives of SV40, bacterial plasmids, phage DNA; baculovirus, yeast plasmids, vectors derived from combinations of plasmids and phage DNA, and viral DNA such as vaccinia, adenovirus, fowl pox virus, and pseudorabies). It is contemplated that any vector may be used as long as it is replicable and viable in the host. In particular, some embodiments of the present invention provide recombinant constructs comprising one or more of the sequences as broadly described above.
- the constructs comprise a vector, such as a plasmid or viral vector, into which a sequence of the invention has been inserted, in a forward or reverse orientation.
- the heterologous structural sequence is assembled in appropriate phase with translation initiation and termination sequences.
- the appropriate DNA sequence is inserted into the vector using any of a variety of procedures. In general, the DNA sequence is inserted into an appropriate restriction endonuclease site(s) by procedures known in the art. Large numbers of suitable vectors are known to those of skill in the art, and are commercially available.
- Such vectors include, but are not limited to, the following vectors: 1) Bacterial - pQE70, pQE60, pQE-9 (Qiagen), pBS, pDIO, phagescript, psiX174, pbluescript SK, pBSKS, pNH8A, pNH16a, pNH18A, pNH46A (Stratagene); ptrc99a, pKK223-3, pKK233-3, pDR540, pRIT5 (Pharmacia); and 2) Eukaryotic ⁇ pWLNEO, pSV2CAT, pOG44, PXT1, pSG (Stratagene) pSVK3, pBPV, pMSG, pSVL (Pharmacia).
- vectors include, but are not limited to, the following vectors: 1) Bacterial - pQE70, pQE60, pQE-9 (Qiagen
- mammalian expression vectors comprise an origin of replication, a suitable promoter and enhancer, and also any necessary ribosome binding sites, polyadenylation sites, splice donor and acceptor sites, transcriptional termination sequences, and 5' flanking non-transcribed sequences.
- DNA sequences derived from the SV40 splice, and polyadenylation sites may be used to provide the required non-transcribed genetic elements.
- the DNA sequence in the expression vector is operatively linked to an appropriate expression control sequence(s) (promoter) to direct mRNA synthesis.
- Promoters useful in the present invention include, but are not limited to, the LTR or SV40 promoter, the E. coli lac or trp, the phage lambda PL and PR, T3 and T7 promoters, and the cytomegalovirus (CMV) immediate early, herpes simplex virus (HSV) thymidine kinase, and mouse metallothionein-I promoters and other promoters known to control expression of gene in prokaryotic or eukaryotic cells or their viruses.
- CMV cytomegalovirus
- HSV herpes simplex virus
- thymidine kinase thymidine kinase
- mouse metallothionein-I promoters and other promoters known to control expression of gene in prokaryotic or eukaryotic cells or their viruses include, but are not limited to, the LTR or SV40 promoter, the E. coli lac or trp, the phage lambda
- recombinant expression vectors include origins of replication and selectable markers permitting transformation of the host cell (e.g., dihydrofolate reductase or neomycin resistance for eukaryotic cell culture, or tetracycline or ampicillin resistance in E. coli).
- transcription of the DNA encoding the polypeptides of the present invention by higher eukaryotes is increased by inserting an enhancer sequence into the vector. Enhancers are cis-acting elements of DNA, usually about from 10 to 300 bp that act on a promoter to increase its transcription.
- Enhancers useful in the present invention include, but are not limited to, the SV40 enhancer on the late side of the replication origin bp 100 to 270, a cytomegalo virus early promoter enhancer, the polyoma enhancer on the late side of the replication origin, and adenovirus enhancers.
- the expression vector also contains a ribosome-binding site for translation initiation and a transcription terminator.
- the vector may also include appropriate sequences for amplifying expression.
- the present invention provides host cells containing the above-described constructs.
- the host cell is a higher eukaryotic cell (e.g., a mammalian or insect cell).
- the host cell is a lower eukaryotic cell (e.g., a yeast cell).
- the host cell can be a prokaryotic cell (e.g., a bacterial cell).
- host cells include, but are not limited to, Escherichia coli, Salmonella typhimurium, Bacillus subtilis, and various species within the genera Pseudomonas, Streptomyces, and Staphylococcus, as well as Saccharomycees cerivisiae, Schizosaccharomycees pombe, Drosophila S2 cells, Spodoptera Sf9 cells, Chinese hamster ovary (CHO) cells, COS-7 lines of monkey kidney fibroblasts, (Gluzman, Cell 23:175 [1981]), C127, 3T3, 293, 293T, HeLa and BHK cell lines.
- Escherichia coli Salmonella typhimurium
- Bacillus subtilis and various species within the genera Pseudomonas, Streptomyces, and Staphylococcus
- Saccharomycees cerivisiae Schizosaccharomycees pombe
- the constructs in host cells can be used in a conventional manner to produce the gene product encoded by the recombinant sequence.
- introduction of the construct into the host cell can be accomplished by calcium phosphate transfection, DEAE- Dextran mediated transfection, or electroporation (See e.g., Davis et al., Basic Methods in Molecular Biology, [1986]).
- the polypeptides of the invention can be synthetically produced by conventional peptide synthesizers. Proteins can be expressed in mammalian cells, yeast, bacteria, or other cells under the control of appropriate promoters. Cell-free translation systems can also be employed to produce such proteins using RNAs derived from the DNA constructs of the present invention.
- cloning and expression vectors for use with prokaryotic and eukaryotic hosts are described by Sambrook, et al., Molecular Cloning: A Laboratory Manual, Second Edition, Cold Spring Harbor, N.Y., (1989).
- the selected promoter is induced by appropriate means (e.g., temperature shift or chemical induction) and cells are cultured for an additional period.
- cells are typically harvested by centrifugation, disrupted by physical or chemical means, and the resulting crude extract retained for further purification
- microbial cells employed in expression of proteins can be disrupted by any convenient method, including freeze-thaw cycling, sonication, mechanical disruption, or use of cell lysing agents.
- the polypeptides of the present invention may also be chemically synthesized (Gutte, B. and Merrifield, R.B. The synthesis of ribonuclease A. J. Biol. Chem. 1971, 2461, 1722- 1741.).
- the present invention further contemplates methods of generating sets of combinatorial mutants of the present ribonuclease proteins and ribonuclease conjugates.
- Library are screened to generate, for example, novel ribonuclease or ribonulcease conjugate variants with improved properties (e.g., cytotoxicity against target cells, cell targeting, low systemic toxicity, stability, clearance, and improved storage, handling, and administration).
- the amino acid sequences for a population of ribonuclease variants or other related proteins are aligned, preferably to promote the highest homology possible.
- Such a population of variants can include, for example, ribonuclease homologs from one or more species, or ribonuclease variants from the same species but which differ due to mutation. Amino acids that appear at each position of the aligned sequences are selected to create a degenerate set of combinatorial sequences.
- the combinatorial ribonuclease library is produced by way of a degenerate library of genes encoding a library of polypeptides which each include at least a portion of potential ribonuclease protein sequences.
- a mixture of synthetic oligonucleotides can be enzymatically ligated into gene sequences such that the degenerate set of potential ribonuclease sequences are expressible as individual polypeptides, or alternatively, as a set of larger fusion proteins (e.g., for phage display) containing the set of ribonuclease sequences therein.
- the library of potential ribonuclease homologs and variants can be generated from a degenerate oligonucleoti.de sequence.
- chemical synthesis of a degenerate gene sequence is carried out in an automatic DNA synthesizer, and the synthetic genes are ligated into an appropriate gene for expression.
- the purpose of a degenerate set of genes is to provide, in one mixture, all of the sequences encoding the desired set of potential ribonuclease sequences.
- the synthesis of degenerate oligonucleotides is well known in the art (See e.g.,
- artificial evolution is performed by random mutagenesis (e.g., by utilizing error-prone PCR to introduce random mutations into a given coding sequence).
- This method requires that the frequency of mutation be finely tuned.
- beneficial mutations are rare, while deleterious mutations are common. This is because the combination of a deleterious mutation and a beneficial mutation often results in an inactive enzyme.
- the ideal number of base substitutions for targeted gene is usually between 1.5 and 5 (Moore and Arnold, Nat. Biotech, 14, 458- 67 [1996]; Leung et al.
- the polynucleotides of the present invention are used in gene shuffling or sexual PCR procedures (e.g., Smith,
- Gene shuffling involves random fragmentation of several mutant DNAs followed by their reassembly by PCR into full length molecules. Examples of various gene shuffling procedures include, but are not limited to, assembly following DNase treatment, the staggered extension process
- the most widely used techniques for screening large gene libraries typically comprises cloning the gene library into replicable expression vectors, transforming appropriate cells with the resulting library of vectors, and expressing the combinatorial genes under conditions in which detection of a desired activity facilitates relatively easy isolation of the vector encoding the gene whose product was detected.
- Example 1 Exemplary Embodiments The following Example describes a number of exemplary embodiments of the compositions and methods of the present invention.
- Ribonuclease The EVADE family of ribonucleases comprises several members, based on human ribonuclease one (RNase I, also known as human pancreatic ribonuclease, hpRNase or hRNase). Some of the EVADE ribonucleases have been assigned the following numbers (QBI-#####) and the single letters and numbers describe the amino acid changes. For example, N88C refers to a substitution of Cysteine (C) for Asparagine (N) at position 88. Amino acid sequence for bovine ribonuclease A
- EVADE ribonuclease that has been modified to carry a Cys at any amino acid can be readily adapted for use in this conjugation strategy.
- Amino acids in the loop region corresponding to amino acids 84-95 of bovine ribonuclease A are of particular interest for conjugation.
- a preferred conjugation partner is an antibody that binds to a cell-specific epitope (e.g. a cancer marker). The antibody is cross-linked to the EVADE ribonuclease via a non-cleavable or a cleavable cross-linker.
- a non-cleavable chemical cross-linker may include m-maleimidobenzoyl-N-hydroxysuccinimide ester (MBS).
- MBS m-maleimidobenzoyl-N-hydroxysuccinimide ester
- a cleavable linker may be used, with the cleavage occurring as a result of enzymatic activity (e.g, protease or a lactamase) or a change in environment (e.g, reducing or acidic environment).
- enzymatic activity e.g, protease or a lactamase
- a change in environment e.g, reducing or acidic environment.
- a number of chemistries are available for conjugation to an antibody, including an aldehyde (generated by oxidation of carbohydrate), an amine (present on the lysine side chains), or a thiol (particularly useful for conjugation to Fab' fragment or scFv).
- a cleavable cross-linker of particular interest is made by incorporation of a protease sensitive peptide into the cross-linker.
- the protease in some embodiments, is selected from a wide variety of naturally occurring enzymes, including endosomal and lysosomal proteases.
- Cathepsin B (a lysosomal cysteine protease of the papain family) expression is elevated in some cancerous cells, especially at the invasive edge of the tumor.
- Cathepsin B preferentially cleaves the Arg-Arg dipeptide, but is promiscuous in its substrate recognition.
- Furin is a cellular endopro tease that catalyzes the proteolytic maturation of proteins in the secretory pathway.
- An alternative strategy is to use a cross linker that is sensitive to ⁇ -lactamase and administer the ⁇ -lactamse concomitantly with the targeted EVADE ribonuclease.
- linkers There are several additional types of linkers that can be cleaved such as peptide bonds, disulfide bonds, hydrazones, and phosphodiesters. The present invention is not limited to the linkers discussed herein. One skilled in the art will appreciate that a variety of linkers will find use with the present invention.
- Conjugating Antibodies Many different antibodies may be conjugated the EVADE ribonuclease to generate conjugates of the present invention.
- the CEA antigen is one of many known protein antigens that are over-expressed on the surface of cancer cells and has been used previously to create targeted therapeutics.
- Another antigen is CD33, which is present on acute myeloid leukemia cells.
- Acute myeloid leukemia (AML) is a cancer that may be treated by an anti-CD33 strategy.
- MYLOTARG is a CD33 antibody-calicheamicin conjugate approved for treatment of AML.
- CD22 is a cell surface receptor found on B-cells which can also be used for antibody-based therapeutics.
- the targeted EVADE ribonucleases may also be made using antibodies against other cancer cell antigens.
- a variety of antibodies may be amenable to such a conjugation strategy.
- the preferred antigens of interest are: • over-expressed on cancer cells relative to normal cells • internalized by the cell (to facilitate ribonuclease entry into the cytosol) • recognized by a monoclonal antibody
- conjugates of humanized M195 (huM195), an antibody specific for CD33 (Immunotoxin Resistance in Multidrug Resistant Cells. Cancer Res, 2003, 63, 72-79.) and an EVADE ribonuclease QBI-50112 (R4C, L86E, N88C, R91D, VI 18C RNase I).
- the linkers are varied and include stable and cleavable linkers.
- Non-cleavable linkers Maleimide-Hydrazine Carbohydrates found in the constant region of an antibody is oxidized to provide an aldehyde, which is reactive with hydrazine.
- the hydrazine of a cross-linker (BMPH, KMUH) is reacted with the aldehydes (oxidized carbohydrates) to form a hydrazone.
- the modified antibody displays a maleimide, which is reacted with the free thiol in a protein to form an antibody-protein conjugate.
- Thioether formation takes place at neutral pH.
- the carbohydrates of huM195 are oxidized with by treatment of the antibody with 10 mM sodium periodate at room temperature for approximately one hour at 4 °C.
- reaction is performed in the dark because sodium periodate is light sensitive.
- a desalting column (Amersham Biosciences, Sephadex G-25 Fine) is used prior to use of oxidized huM195 for conjugation.
- a solution of BMPH is added to the oxidized huM195, and the reaction allowed to proceed for 30-60 minutes at room temperature.
- the reaction is then applied to a desalting column (Amersham Biosciences, Sephadex G-25 Fine) Reaction times, ratios of reagents, solution concentrations, and temperatures may be optimized to increase yield and purity of the conjugate. Fractions are collected, and their absorbance at 280 nm monitored.
- maleimide-huM195 containing fractions are pooled, a solution of the EVADE ribonuclease variant QBI-50112 (20 mM sodium phosphate buffer, 0.15 M NaCl, pH 7.0 (PBS) with 10 mM EDTA) with a free cysteine residue is added in a one to one ratio with maleimide-huM195.
- the reaction is allowed to proceed for 30 minutes and then quenched by the addition of Tris buffer with cysteine.
- the conjugated sample is applied to a desalting column (Amersham Biosciences, Sephadex G-25 Fine) and eluted with buffer (10 mM sodium phosphate, 150 mM NaCl, pH 7.4).
- the fractions are monitored using the 280 nm absorbance.
- the product-containing (huM 195 -QBI-50112) fractions are pooled. Reaction times, ratios of reagents, solution concentrations, and temperatures may be optimized to increase yield and purity of the conjugate.
- the activated ester (an N-hydroxy succinimide) can be selectively reacted with amines in the antibody (typically lysine side chains) without affecting the maleimide. A covalent, chemically stable amide bond is formed.
- the modified antibody is then reacted with the single free thiol in the ribonuclease variant to form the conjugate.
- the reaction of the thiol of the ribonuclease variant with the maleimide is most selective at pH 6.5-7.5.
- a four-fold excess of the crosslinker (EMCS or SMCC; Pierce) is dissolved in DMF (or DMSO if necessary) and is then added to a solution of huM195 in buffer (20 mM sodium phosphate buffer, 0.15 M ⁇ aCl, pH 7.0 (PBS)). The reaction is allowed to proceed for 30 minutes at 4 °C. The reaction mixture is applied to a desalting column (Amersham Biosciences, Sephadex G-25 Fine). Fractions are collected, and their absorbance at 280 nm monitored.
- maleimide-huM195 containing fractions are pooled, a solution of the EVADE ribonuclease variant QBI-50112 (20 mM sodium phosphate buffer, 0.15 M ⁇ aCl, pH 7.0 with 10 mM EDTA) with a free cysteine residue is added in a one to one ratio with maleimide-huM195.
- the reaction is allowed to proceed for 30 minutes and then quenched by the addition of Tris buffer with cysteine.
- the conjugated sample is applied to a desalting column (Amersham Biosciences, Sephadex G-25 Fine) and eluted with buffer (10 mM sodium phosphate, 150 mM NaCl, pH 7.4).
- the fractions are monitored using the 280 nm absorbance.
- the product-containing (huM195-QBI-50112) fractions are pooled. Reaction times, ratios of reagents, solution concentrations, and temperatures may be optimized to increase yield and purity of the conjugate.
- a-Haloacetyl-NHS The activated ester (an N-hydroxy succinimide) is selectively reacted with amines without affecting the haloacetyl.
- the optimal pH for the reaction is pH 7-9.
- the modified antibody is then reacted with the single free thiol in the ribonuclease variant to form the conjugate.
- a solution of crosslinker (SBAP or SIAB) in DMSO is added to huM195 solution (0.1 M sodium phosphate, 0.15 M ⁇ aCl, pH 7.2) and allowed to react for approximately 30 minutes.
- reaction mixture is be run over a desalting column (Amersham Biosciences, Sephadex G-25 Fine) with borate buffer (50 mM sodium borate, pH 8.3, 5 mM EDTA). Fractions are collected, and their absorbance at 280 nm monitored.
- a solution of the EVADE ribonuclease variant QBI-50112 (R4C, L86E, ⁇ 88C, R91D, V118C RNase I) is added, and the reaction of the single free thiol of the RNase with the haloacetyl sits for approximately one hour. These reactions are performed in the dark due to the potential for side products. The reactions are quenched by the addition of Tris buffer with cysteine.
- the quenching reaction is allowed to proceed for 15 minutes at room temperature in the dark.
- the conjugated sample is applied to a desalting column (Amersham Biosciences, Sephadex G-25 Fine) and eluted with buffer (10 mM sodium phosphate, 150 mM NaCl, pH 7.4 (PBS)).
- the fractions are monitored using the 280 nm absorbance.
- the product-containing (huM195- QBI-50112) fractions are pooled. Reaction times, ratios of reagents, solution concentrations, and temperatures may be optimized to increase yield and purity of the conjugate.
- Cleavable linkers These linkers are peptide-based and are be cleaved by a human protease.
- the example describes linkers cleaved by the protease furin. Furin recognizes Arg-Xaa-Yaa-Arg, where Xaa is unspecified and Yaa is Lys or Arg. Hydrolysis occurs after the C-terminal Arg.
- the reactive groups maleimide, hydrazine, N-hydroxy succinimide ester, ⁇ -halo acetyl used in the protease-sensitive cross-linkers are the same as the commercially available linkers.
- Peptides are dissolved in ddH 2 ⁇ and added at a 3 -fold molar excess to a solution of huM195 (0.1 M sodium phosphate, 0.15 M ⁇ aCl, pH 7.2) and allowed to react for approximately 30 minutes.
- the reaction mixture will be run over a desalting column (Amersham Biosciences, Sephadex G-25 Fine) with borate buffer (50 mM sodium borate, pH 8.3, 5 mM EDTA). Fractions are collected, and their absorbance at 280 nm monitored.
- a solution of the EVADE ribonuclease variant QBI-112 in 20 mM sodium phosphate, pH 7.0, containing ⁇ aCl (0.15 M) and EDTA (0.01 M) is added.
- the reaction proceeds at room temperature with stirring. Under these conditions, reaction between the maleimide and a thiol is favored by 1000-fold over reaction between the maleimide and an amine. After 30 min, the reaction will be quenched by addition of a Tris-HCl buffer containing cysteine at a concentration 10-fold greater than that of the peptide substitutent.
- Peptides bearing the a- bromo-acetyl group are conjugated by using identical procedures, with three exceptions.
- Reactions are run in a 20 mM MOPS buffer, pH 8.2, containing ⁇ aCl (150 mM) and EDTA (0.1 mM) for 60 min at 37 °C in the dark.
- the conjugated sample is applied to a desalting column (Amersham Biosciences, Sephadex G-25 Fine) and eluted with buffer (10 mM sodium phosphate, 150 mM NaCl, pH 7.4).
- the fractions are monitored using the 280 nm absorbance.
- the product-containing (huM195-QBI-50112) fractions are pooled. Reaction times, ratios of reagents, solution concentrations, and temperatures may be optimized to increase yield and purity of the conjugate.
- the cDNA encoding an anti-CEA scFv fragment will be fused to the 5 '-end of the cDNA encoding the EVade ribonuclease QBI-50110 (R4C, L86E, N88R, G89D, R91D, VI 18C RNase I) RNase. Six glycine residues will be incorporated between the scFv and the ribonuclease to minimize hindrance.
- the cDNA will be sequenced, cloned in E. coli, and expressed as an insoluble protein sequestered in inclusion bodies. The inclusion bodies will be denatured and refolded. After refolding, the fusion will be purified by standard protein chromatography methods, including size-exclusion and hydrophobic interactions. Production of the anti-CEA scFv-EVade fusion may be optimized to increase yield and or purity.
- Type Culture Collection Number CRL-1687 and Bx-PC-3 pancreatic cells were employed with athymic nude mice. Approximately 2xl0 6 cells were implanted into the right rear flank of 5-6 week old male homozygous (nu/nu) nude mice (Harlan). Tumors were allowed to grow to an average size of ⁇ .75 mm 3 before treatments were initiated. Animals of each tumor type, with the properl) sized tumors, were divided into treatment groups, including one set of animals treated with vehicle (PBS) on the same dosing schedule as the treatment arm. QBI-119 was dosed at 15 mg/kg qdx5 (five times per week) throughout the course of the study. Tumors were measured twice weekly using calipers. Tumor volume (mm 3 ) was determined by using the formula for an ellipsoid sphere:
- the percent tumor growth inhibition is determined using the following formula:
- % TGI Percent tumor growth inhibition
- Figure 1 A shows the tumor growth inhibition caused by QBI-119 on A549 cells was significant (64%), while Figure IB shows that QBI-119 had no significant impact on animal weights at this dosage.
- Figure 2 A shows the tumor growth inhibition caused by QBI-119 on Bx-PC-3 cells was significant (60%), while Figure IB shows that QBI-119 had no significant impact on animal weights at this dosage.
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US56160904P | 2004-04-13 | 2004-04-13 | |
PCT/US2005/012404 WO2005115477A2 (en) | 2004-04-13 | 2005-04-13 | Non-natural ribonuclease conjugates as cytotoxic agents |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1740220A2 true EP1740220A2 (en) | 2007-01-10 |
Family
ID=37487899
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP05779321A Withdrawn EP1740220A2 (en) | 2004-04-13 | 2005-04-13 | Non-natural ribonuclease conjugates as cytotoxic agents |
Country Status (1)
Country | Link |
---|---|
EP (1) | EP1740220A2 (en) |
-
2005
- 2005-04-13 EP EP05779321A patent/EP1740220A2/en not_active Withdrawn
Similar Documents
Publication | Publication Date | Title |
---|---|---|
WO2005115477A2 (en) | Non-natural ribonuclease conjugates as cytotoxic agents | |
ES2279539T3 (en) | ANTI-CEA MONOCLONAL ANTIBODY, CONJUGATES UNDERSTANDING ANTIBODY, AND THERAPEUTIC USE IN AN ADEPT SYSTEM. | |
ES2342929T3 (en) | ANTI-CD22 ANTIBODIES INCREASED BY THE LEUCEMIC CELLS THAT EXPRESS CD22. | |
US8257708B2 (en) | Antibodies against cancer antigen TMEFF2 and uses thereof | |
CN101233236B (en) | Monoclonal antibodies and single chain antibody fragments against cell-surface prostate specific membrane antigen | |
EP2049151A2 (en) | Methods and compositions for the treatment of cancer | |
JP6014206B2 (en) | Therapeutic ribonuclease | |
JP4519464B2 (en) | Humanized collagen antibodies and related methods | |
JPH11505704A (en) | Immunoconjugates Containing Single Chain Variable Region Fragments of Anti-CD-19 Antibodies | |
US20080171039A1 (en) | Compositions Against Cancer Antigen Liv-1 and Uses Thereof | |
EP1740220A2 (en) | Non-natural ribonuclease conjugates as cytotoxic agents | |
JP2010077026A (en) | Solid cancer medicine targeting cancer-related macrophage | |
JP4699450B2 (en) | ADEP construction for CAB molecules and CEA | |
Ibrahim | Current status of immunotoxins application in cancer patient’s treatment | |
EP1691763A4 (en) | Cab molecules | |
Abeer | Current status of immunotoxin application in cancer treatment | |
US20050053611A1 (en) | Pharmaceutical kit comprising anti-human seminal plasma protein single chain antibody/human carboxypeptidase fusion protein and prodrug | |
Cao et al. | Design, development, and characterization of recombinant immunotoxins targeting HER2/neu |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
17P | Request for examination filed |
Effective date: 20061110 |
|
AK | Designated contracting states |
Kind code of ref document: A2 Designated state(s): AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LI LT LU MC NL PL PT RO SE SI SK TR |
|
AX | Request for extension of the european patent |
Extension state: AL BA HR LV MK YU |
|
PUAK | Availability of information related to the publication of the international search report |
Free format text: ORIGINAL CODE: 0009015 |
|
RIC1 | Information provided on ipc code assigned before grant |
Ipc: C07H 21/04 20060101ALI20090506BHEP Ipc: C12P 21/06 20060101ALI20090506BHEP Ipc: C12N 5/00 20060101ALI20090506BHEP Ipc: C12N 9/22 20060101ALI20090506BHEP Ipc: A61K 38/46 20060101ALI20090506BHEP Ipc: A61K 39/00 20060101ALI20090506BHEP Ipc: A61K 39/395 20060101ALI20090506BHEP Ipc: A01N 43/04 20060101ALI20090506BHEP Ipc: A01N 37/18 20060101AFI20090506BHEP |
|
17Q | First examination report despatched |
Effective date: 20100924 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
|
18D | Application deemed to be withdrawn |
Effective date: 20110205 |