Patent Publication Number: US-2009220527-A1

Title: Affinity optimized epha2 agonistic antibodies and methods of use thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to and benefit of U.S. Provisional Patent Application 60/751,964, filed on Dec. 21, 2005, the disclosure of which is incorporated by reference herein in its entirety for all purposes. 
    
    
     1. FIELD OF THE INVENTION 
     The present invention provides antibodies that specifically bind to EphA2 and compositions comprising said antibodies. The present invention further relates to methods and compositions designed for the treatment, management, or prevention of cancer. The methods of the invention comprise the administration of an effective amount of one or more antibodies specific for EphA2 that are EphA2 agonists and/or preferentially bind epitopes on EphA2 that are selectively exposed or increased on cancer cells relative to non-cancer cells. The invention also provides pharmaceutical compositions comprising one or more antibodies of the invention either alone or in combination with one or more other agents useful for cancer therapy. Diagnostic methods and methods for screening for therapeutically useful anti-EphA2 antibodies are also provided. 
     2. BACKGROUND OF THE INVENTION 
     Cancer 
     A neoplasm, or tumor, is a neoplastic mass resulting from abnormal uncontrolled cell growth that can be benign or malignant. Benign tumors generally remain localized. Malignant tumors are collectively termed cancers. The term “malignant” generally means that the tumor can invade and destroy neighboring body structures and spread to distant sites to cause death (for review, see Robbins and Angell, 1976 , Basic Pathology,  2d Ed., W. B. Saunders Co., Philadelphia, pp. 68-122). Cancer can arise in many sites of the body and behave differently depending upon its origin. Cancerous cells destroy the part of the body in which they originate and then spread to other part(s) of the body where they start new growth and cause more destruction. 
     More than 1.2 million Americans develop cancer each year. Cancer is the second leading case of death in the United States and, if current trends continue, cancer is expected to be the leading cause of the death by the year 2010. Lung and prostate cancer are the top cancer killers for men in the United States. Lung and breast cancer are the top cancer killers for women in the United States. One in two men in the United States will be diagnosed with cancer at some time during his lifetime. One in three women in the United States will be diagnosed with cancer at some time during her lifetime. Current treatment options, such as surgery, chemotherapy and radiation treatment, are often either ineffective or present serious side effects. 
     Metastasis 
     The most life-threatening forms of cancer often arise when a population of tumor cells gains the ability to colonize distant and foreign sites in the body. These metastatic cells survive by overriding restrictions that normally constrain cell colonization into dissimilar tissues. For example, typical mammary epithelial cells will generally not grow or survive if transplanted to the lung, yet lung metastases are a major cause of breast cancer morbidity and mortality. Recent evidence suggests that dissemination of metastatic cells through the body can occur long before clinical presentation of the primary tumor. These micrometastatic cells may remain dormant for many months or years following the detection and removal of the primary tumor. Thus, a better understanding of the mechanisms that allow for the growth and survival of metastatic cells in a foreign microenvironment is critical for the improvement of therapeutics designed to fight metastatic cancer and diagnostics for the early detection and localization of metastases. 
     Cancer Cell Signaling 
     Cancer is a disease of aberrant signal transduction. Aberrant cell signaling overrides anchorage-dependent constraints on cell growth and survival (Rhim, et al.,  Critical Reviews in Oncogenesis  8:305, 1997; Patarca,  Critical Reviews in Oncogenesis  7:343, 1996; Malik, et al.,  Biochimica et Biophysica Acta  1287:73, 1996; Cance, et al.,  Breast Cancer Res Treat  35:105, 1995). Tyrosine kinase activity is induced by ECM anchorage and indeed, the expression or function of tyrosine kinases is usually increased in malignant cells (Rhim, et al.,  Critical Reviews in Oncogenesis  8:305, 1997; Cance, et al.,  Breast Cancer Res Treat  35:105, 1995; Hunter,  Cell  88:333; 1997). Based on evidence that tyrosine kinase activity is necessary for malignant cell growth, tyrosine kinases have been targeted with new therapeutics (Levitzki, et al.,  Science  267:1782, 1995; Kondapaka, et al.,  Molecular  &amp;  Cellular Endocrinology  1117:53, 1996; Fry, et al.,  Current Opinion in BioTechnology  6: 662, 1995). Unfortunately, obstacles associated with specific targeting to tumor cells often limit the application of these drugs. In particular, tyrosine kinase activity is often vital for the function and survival of benign tissues (Levitzki, et al.,  Science  267:1782, 1995). To minimize collateral toxicity, it is critical to identify and then target tyrosine kinases that are selectively overexpressed in tumor cells. 
     EphA2 
     EphA2 is a 130 kDa receptor tyrosine kinase that is expressed in adult epithelia, where it is found at low levels and is enriched within sites of cell-cell adhesion (Zantek, et al,  Cell Growth  &amp;  Differentiation  10:629, 1999; Lindberg, et al.,  Molecular  &amp;  Cellular Biology  10: 6316, 1990). This subcellular localization is important because EphA2 binds ligands (known as EphrinsA1 to A5) that are anchored to the cell membrane (Eph Nomenclature Committee, 1997, Cell 90:403; Gale, et al., 1997 , Cell  &amp;  Tissue Research  290: 227). The primary consequence of ligand binding is EphA2 autophosphorylation (Lindberg, et al., 1990, supra). However, unlike other receptor tyrosine kinases, EphA2 retains enzymatic activity in the absence of ligand binding or phosphotyrosine content (Zantek, et al., 1999, supra). EphA2 is upregulated on a large number of aggressive carcinoma cells. 
     Cancer Therapy 
     One barrier to the development of anti-metastasis agents has been the assay systems that are used to design and evaluate these drugs. Most conventional cancer therapies target rapidly growing cells. However, cancer cells do not necessarily grow more rapidly but instead survive and grow under conditions that are non-permissive to normal cells (Lawrence and Steeg, 1996 , World J. Urol.  14:124-130). These fundamental differences between the behaviors of normal and malignant cells provide opportunities for therapeutic targeting. The paradigm that micrometastatic tumors have already disseminated throughout the body emphasizes the need to evaluate potential chemotherapeutic drugs in the context of a foreign and three-dimensional microenvironment. Many standard cancer drug assays measure tumor cell growth or survival under typical cell culture conditions (i.e., monolayer growth). However, cell behavior in two-dimensional assays often does not reliably predict tumor cell behavior in vivo. 
     Currently, cancer therapy may involve surgery, chemotherapy, hormonal therapy and/or radiation treatment to eradicate neoplastic cells in a patient (see, for example, Stockdale, 1998, “Principles of Cancer Patient Management,” in Scientific American: Medicine, vol. 3, Rubenstein and Federman, eds., Chapter 12, Section IV). Recently, cancer therapy may also involve biological therapy or immunotherapy. All of these approaches can pose significant drawbacks for the patient. Surgery, for example, may be contraindicated due to the health of the patient or may be unacceptable to the patient. Additionally, surgery may not completely remove the neoplastic tissue. Radiation therapy is only effective when the neoplastic tissue exhibits a higher sensitivity to radiation than normal tissue, and radiation therapy can also often elicit serious side effects. Hormonal therapy is rarely given as a single agent and, although it can be effective, is often used to prevent or delay recurrence of cancer after other treatments have removed the majority of the cancer cells. Biological therapies/immunotherapies are limited in number and each therapy is generally effective for a very specific type of cancer. 
     With respect to chemotherapy, there are a variety of chemotherapeutic agents available for treatment of cancer. A significant majority of cancer chemotherapeutics act by inhibiting DNA synthesis, either directly, or indirectly by inhibiting the biosynthesis of the deoxyribonucleotide triphosphate precursors, to prevent DNA replication and concomitant cell division (see, for example, Gilman et al., Goodman and Gilman&#39;s: The Pharmacological Basis of Therapeutics, Eighth Ed. (Pergamom Press, New York, 1990)). These agents, which include alkylating agents, such as nitrosourea, anti-metabolites, such as methotrexate and hydroxyurea, and other agents, such as etoposides, campathecins, bleomycin, doxorubicin, daunorubicin, etc., although not necessarily cell cycle specific, kill cells during S phase because of their effect on DNA replication. Other agents, specifically colchicine and the vinca alkaloids, such as vinblastine and vincristine, interfere with microtubule assembly resulting in mitotic arrest. Chemotherapy protocols generally involve administration of a combination of chemotherapeutic agents to increase the efficacy of treatment. 
     Despite the availability of a variety of chemotherapeutic agents, chemotherapy has many drawbacks (see, for example, Stockdale, 1998, “Principles Of Cancer Patient Management” in Scientific American Medicine, vol. 3, Rubenstein and Federman, eds., ch. 12, sect. 10). Almost all chemotherapeutic agents are toxic, and chemotherapy causes significant, and often dangerous, side effects, including severe nausea, bone marrow depression, immunosuppression, etc. Additionally, even with administration of combinations of chemotherapeutic agents, many tumor cells are resistant or develop resistance to the chemotherapeutic agents. In fact, those cells resistant to the particular chemotherapeutic agents used in the treatment protocol often prove to be resistant to other drugs, even those agents that act by mechanisms different from the mechanisms of action of the drugs used in the specific treatment; this phenomenon is termed pleiotropic drug or multidrug resistance. Thus, because of drug resistance, many cancers prove refractory to standard chemotherapeutic treatment protocols. 
     There is a significant need for alternative cancer treatments, particularly for treatment of cancer that has proved refractory to standard cancer treatments, such as surgery, radiation therapy, chemotherapy, and hormonal therapy. Further, it is uncommon for cancer to be treated by only one method. Thus, there is a need for development of new therapeutic agents for the treatment of cancer and new, more effective, therapy combinations for the treatment of cancer. 
     3. SUMMARY OF THE INVENTION 
     The present invention provides antibodies that specifically bind to EphA2. In particular, the invention provides the following antibodies that specifically bind to EphA2: 2A4 or an antigen-binding fragment thereof, 2E7 or an antigen-binding fragment thereof, and 12E2 or an antigen-binding fragment thereof. 
     The present invention provides antibodies that specifically bind to EphA2, said antibodies comprising a variable heavy (“VH”) domain having an amino acid sequence of the VH domain of 2A4 (Seq ID No: 2), 2E7 (Seq ID No: 18), or 12E2 (Seq ID No: 26). The present invention also provides antibodies that specifically bind to EphA2, said antibodies comprising a variable light (“VL”) domain having an amino acid sequence of the VL domain of 2A4 (Seq ID No: 2), 2E7 (Seq ID No: 18), or 12E2 (Seq ID No: 26). The present invention also provides for antibodies that specifically bind to EphA2, said antibodies comprising a VH domain and VL domain having the amino acid sequence of the VH and VL domains of 2A4 (Seq ID No: 2), 2E7 (Seq ID No: 18), or 12E2 (Seq ID No: 26). The invention further provides antibodies that specifically bind to EphA2, said antibodies comprising one or more VH complementarity determining regions (“CDRs”) and/or one or more VL CDRs having the amino acid sequence of one or more of the VH CDRs of 2A4 (Seq ID Nos: 3-5), 2E7 (Seq ID Nos: 19-21), or 12E2 (Seq ID Nos: 27-29) and/or the amino acid sequence of one or more of the VL CDRs of 2A4 (Seq ID Nos: 6-8), 2E7 (Seq ID Nos: 22-24), or 12E2 (Seq ID No: 30-32), respectively. 
     In one embodiment, the invention provides an antibody that specifically binds to EphA2, wherein the antibody comprises the VH domain and/or VL domain of 2A4. In another embodiment, the invention provides an antibody that specifically binds to EphA2, wherein the antibody comprises one, two, or three VH CDRs (including, for example, VH CDR3) of 2A4. In another embodiment, the invention provides an antibody that specifically binds to EphA2, wherein the antibody comprises one, two or three VL CDRs (preferably including, VL CDR3) of 2A4. In yet another embodiment, the invention provides an antibody that specifically binds to EphA2, wherein the antibody comprises one, two or three VH CDRs and one, two or three VL CDRs of 2A4. 
     In one embodiment, the invention provides an antibody that specifically binds to EphA2, wherein the antibody comprises the VH domain and/or VL domain of 2E7. In another embodiment, the invention provides an antibody that specifically binds to EphA2, wherein the antibody comprises one, two, or three VH CDRs (including, for example, VH CDR3) of 2E7. In another embodiment, the invention provides an antibody that specifically binds to EphA2, wherein the antibody comprises one, two or three VL CDRs (preferably including, VL CDR3) of 2E7. In yet another embodiment, the invention provides an antibody that specifically binds to EphA2, wherein the antibody comprises one, two or three VH CDRs and one, two or three VL CDRs of 2E7. 
     In one embodiment, the invention provides an antibody that specifically binds to EphA2, wherein the antibody comprises the VH domain and/or VL domain of 12E2. In another embodiment, the invention provides an antibody that specifically binds to EphA2, wherein the antibody comprises one, two, or three VH CDRs (preferably including, VH CDR3) of 12E2. In another embodiment, the invention provides an antibody that specifically binds to EphA2, wherein the antibody comprises one, two or three VL CDRs (including, for example, VL CDPR3) of 12E2. In yet another embodiment, the invention provides an antibody that specifically binds to EphA2, wherein the antibody comprises one, two or three VH CDRs and one, two or three VL CDRs of 12E2. 
     The present invention provides for mixtures of antibodies that specifically bind to EphA2, wherein the mixture comprises at least one, two, three, or more different antibodies of the invention. The present invention also provides for panels of antibodies that specifically bind to EphA2, wherein the panel has at least one, two, three, four, five or more different antibodies of the invention. In specific embodiments, the invention provides for panels of antibodies that have different affinities for EphA2, different specificities for EphA2, or different dissociation rates. The invention provides panels of at least 10, preferably at least 25, at least 50, at least 75, at least 100, at least 125, at least 150, at least 175, at least 200, at least 250, at least 300, at least 350, at least 400, at least 450, at least 500, at least 550, at least 600, at least 650, at least 700, at least 750, at least 800, at least 850, at least 900, at least 950, or at least 1000, antibodies. Panels of antibodies can be used, for example, in 96 well plates for assays such as ELISAs. 
     Differences in the subcellular localization, ligand binding properties or protein organization (e.g., structure, orientation in the cell membrane) can further distinguish the EphA2 that is present on cancer cells from EphA2 on non-cancer cells. In non-cancer cells, EphA2 is expressed at low levels and is localized to sites of cell-cell contact, where it can engage its membrane-anchored ligands. However, cancer cells generally display decreased cell-cell contacts and this can decrease EphA2-ligand binding. Furthermore, the overexpression of EphA2 can cause an excess of EphA2 relative to ligand that increases the amount of non-ligand bound EphA2. Consequently, changes in the subcellular distribution or membrane orientation of EphA2 can cause EphA2 to localize to sites in a cancer cell where it is inaccessible to ligand. Additionally, EphA2 may have altered ligand binding properties (e.g., due to an altered conformation) in cancer cells such that it is incapable of stable interactions with its ligand whether or not it is localized to the cell-cell junction. In each case, these changes can expose certain epitopes on the EphA2 in cancer cells that are not exposed in non-cancer cells. Accordingly, the invention also provides antibodies that specifically bind EphA2 but preferably bind an EphA2 epitope exposed on cancer cells but not on non-cancer cells (“exposed EphA2 epitope antibodies”). Exposing cancer cells to such EphA2 antibodies that preferentially bind epitopes on EphA2 that are selectively exposed or increased on cancer cells but not non-cancer cells targets the therapeutic/prophylactic antibody to cancer cells and prevents or decreases the cells&#39; ability to proliferate while sparing non-cancer cells. 
     The present invention provides for the screening and identification of antibodies that bind to and agonize EphA2 and/or preferentially bind epitopes on EpbA2 that are selectively exposed or increased on cancer cells but not non-cancer cells, preferably monoclonal antibodies. In particular, the antibodies of the invention bind to the extracellular domain of EphA2 and, preferably, elicit EphA2 signaling and EphA2 autophosphorylation. 
     In another particular embodiment, the antibodies of the invention bind to the extracellular domain of EphA2 and, preferably, bind an EphA2 epitope exposed on cancer cells but not non-cancer cells. In one embodiment, the antibodies of the invention are 2A4, 2E7, or 12E2. 
     In one embodiment, to identify antibodies that preferentially bind an EphA2 epitope exposed on cancer cells but not non-cancer cells, antibodies may be screened for the ability to preferentially bind EphA2 not bound to ligand, e.g., Ephrin A1, and that is not localized to cell-cell contacts. Any method known in the art to determine antibody binding/localization on a cell can be used to screen candidate antibodies for desirable binding properties. In a specific embodiment, immunofluorescence microscopy or flow cytometry is used to determine the binding characteristics of an antibody. In this embodiment, antibodies that bind poorly to EphA2 when it is bound to its ligand and localized to cell-cell contacts but bind well to free EphA2 on a cell are encompassed by the invention. In another specific embodiment, EphA2 antibodies are selected for their ability to compete with ligands (e.g., cell-anchored or purified ligands) for binding to EphA2 using cell-based or ELISA assays. 
     Accordingly, the present invention relates to pharmaceutical compositions and prophylactic and therapeutic regimens designed to prevent, treat, or manage cancer, particularly metastatic cancer, in a subject comprising administering one or more antibodies that specifically bind to and agonize EphA2 and/or preferentially bind epitopes on EphA2 that are selectively exposed or increased on cancer cells but not non-cancer cells. In one embodiment, the cancer is of an epithelial cell origin. In another embodiment, the cancer is a cancer of the skin, lung, colon, breast, prostate, bladder, kidney, or pancreas. In another embodiment, the cancer cells in the cancer to be prevented, treated, or managed overexpress EphA2. In one embodiment, some EphA2 is not bound to ligand, either as a result of decreased cell-cell contacts, altered subcellular localization, or increases in amount of EphA2 relative to ligand. In another embodiment, the methods of the invention are used to prevent, treat, or manage metastasis of tumors. The antibodies of the invention can be administered in combination with one or more other cancer therapies. In particular, the present invention provides methods of preventing, treating, or managing cancer in a subject comprising administering to said subject a therapeutically or prophylactically effective amount of one or more EphA2 antibodies of the invention in combination with the administration of a therapeutically or prophylactically effective amount of one or more chemotherapies, hormonal therapies, biological therapies/immunotherapies and/or radiation therapies other than the administration of an EphA2 antibody of the invention or in combination with surgery. 
     The methods and compositions of the invention are useful not only in untreated patients but are also useful in the treatment of patients partially or completely refractory to current standard and experimental cancer therapies, including but not limited to chemotherapies, hormonal therapies, biological therapies, radiation therapies, and/or surgery as well as to improve the efficacy of such treatments. Accordingly, in one embodiment, the invention provides therapeutic and prophylactic methods for the treatment or prevention of cancer that has been shown to be or may be refractory or non-responsive to therapies other than those comprising administration of EphA2 antibodies of the invention. In a specific embodiment, one or more EphA2 antibodies of the invention are administered to a patient refractory or non-responsive to a non-EphA2-based treatment to render the patient non-refractory or responsive. The treatment to which the patient had previously been refractory or non-responsive can then be administered with therapeutic effect. 
     In addition, the present invention provides methods of screening for EphA2 antibodies of the invention. In particular, antibodies may be screened for binding to EphA2, particularly the extracellular domain of EphA2, using routine immunological techniques. In one embodiment, to identify agonistic EphA2 antibodies, EphA2 antibodies may be screened for the ability to elicit EphA2 signaling, e.g., increase EphA2 phosphorylation and/or to degrade EphA2. 
     In another embodiment, to identify antibodies that preferentially bind an EphA2 epitope exposed on cancer cells but not non-cancer cells, antibodies may be screened for the ability to preferentially bind EphA2 that is not bound to ligand, e.g., Ephrin A1, and that is not localized to cell-cell contacts. Any method known in the art to determine antibody binding/localization on a cell can be used to screen candidate antibodies for desirable binding properties. In a specific embodiment, immunofluorescence microscopy or flow cytometry is used to determine the binding characteristics of an antibody. In this embodiment, antibodies that bind poorly to EphA2 when it is bound to its ligand and localized to cell-cell contacts but bind well to free EphA2 on a cell are encompassed by the invention. In another specific embodiment, EphA2 antibodies are selected for their ability to compete with ligands (e.g., cell-anchored or purified ligands) for binding to EphA2 using cell-based or ELISA assays. 
     The invention further provides diagnostic methods using the EphA2 antibodies of the invention to evaluate the efficacy of cancer treatment, either EphA2-based or not EphA2-based. In general, increased EphA2 expression is associated with increasingly invasive and metastatic cancers. Accordingly, a reduction in EphA2 expression with a particular treatment indicates that the treatment is reducing the invasiveness and/or metastatic potential of cancer. In particular embodiments, the diagnostic methods of the invention provide methods of imaging and localizing metastases and methods of diagnosis and prognosis using tissues and fluids distal to the primary tumor site (as well as methods using tissues and fluids of the primary tumor), for example, whole blood, sputum, urine, serum, fine needle aspirates (i.e., biopsies). In other embodiments, the diagnostic methods of the invention provide methods of imaging and localizing metastases and methods of diagnosis and prognosis in vivo. In such embodiments, primary metastatic tumors are detected using an antibody of the invention, preferably an exposed EphA2 epitope antibody. The antibodies of the invention may also be used for immunohistochemical analyses of frozen or fixed cells or tissue assays. 
     In one embodiment, the antibodies of the invention are human or humanized antibodies. In another embodiment, the antibodies of the invention are conjugated to a detectable substance or a therapeutic agent. In another embodiment, the antibodies of the inventions are not conjugated to a detectable substance or a therapeutic agent. 
     In another embodiment, kits comprising the pharmaceutical compositions or diagnostic reagents of the invention are provided. 
     3.1 DEFINITIONS 
     As used herein, the term “agonist” refers to any compound, including a protein, polypeptide, peptide, antibody, antibody fragment, large molecule, or small molecule (less than 10 kD), that increases the activity, activation or function of another molecule. EphA2 agonists cause increased phosphorylation and degradation of EphA2 protein. EphA2 antibodies that agonize EphA2 may or may not preferentially bind an EphA2 epitope that is exposed in a cancer cell relative to a non-cancer cell. 
     The term “antibodies or fragments thereof that specifically bind to EphA2” as used herein refers to antibodies or fragments thereof that specifically bind to an EphA2 polypeptide or a fragment of an EphA2 polypeptide and do not specifically bind to other non-EphA2 polypeptides. Preferably, antibodies or fragments that specifically bind to an EphA2 polypeptide or fragment thereof do not non-specifically cross-react with other antigens (e.g., binding cannot be competed away with a non-EphA2 protein, e.g., BSA in an appropriate immunoassay). Antibodies or fragments that specifically bind to an EphA2 polypeptide can be identified, for example, by immunoassays or other techniques known to those of skill in the art. Antibodies of the invention include, but are not limited to, synthetic monoclonal antibodies, multi specific antibodies (including bi-specific antibodies), human antibodies, humanized antibodies, chimeric antibodies, synthetic antibodies, single-chain Fvs (scFv) (including bi-specific scFvs), single chain antibodies, Fab fragments, F(ab′) fragments, disulfide-linked Fvs (sdFv), and anti-idiotypic (anti-Id) antibodies, and epitope-binding fragments of any of the above. In particular, antibodies of the present invention include immunoglobulin molecules and immunologically active portions of immunoglobulin molecules, i.e., molecules that contain an antigen binding site that specifically binds to an EphA2 antigen (e.g., one or more complementarity determining regions (CDRs) of an anti-EphA2 antibody). Preferably agonistic antibodies or fragments that specifically bind to an EphA2 polypeptide or fragment thereof only agonize EphA2 and do not significantly agonize other activities. 
     As used herein, the term “cancer” refers to a disease involving cells that have the potential to metastasize to distal sites and exhibit phenotypic traits that differ from those of non-cancer cells, for example, formation of colonies in a three-dimensional substrate such as soft agar or the formation of tubular networks or weblike matrices in a three-dimensional basement membrane or extracellular matrix preparation, such as MATRIGEL™. Non-cancer cells do not form colonies in soft agar and form distinct sphere-like structures in three-dimensional basement membrane or extracellular matrix preparations. Cancer cells acquire a characteristic set of functional capabilities during their development, albeit through various mechanisms. Such capabilities include evading apoptosis, self-sufficiency in growth signals, insensitivity to anti-growth signals, tissue invasion/metastasis, limitless replicative potential, and sustained angiogenesis. The term “cancer cell” is meant to encompass both pre-malignant and malignant cancer cells. 
     The term “derivative” as used herein refers to a polypeptide that comprises an amino acid sequence of an EphA2 polypeptide, a fragment of an EphA2 polypeptide, an antibody that specifically binds to an EphA2 polypeptide, or an antibody fragment that specifically binds to an EphA2 polypeptide which has been altered by the introduction of amino acid residue substitutions, deletions or additions (i.e., mutations). In some embodiments, an antibody derivative or fragment thereof comprises amino acid residue substitutions, deletions or additions in one or more CDRs. The antibody derivative may have substantially the same binding, better binding, or worse binding when compared to a non-derivative antibody. In specific embodiments, one, two, three, four, or five amino acid residues of the CDR have been substituted, deleted or added (i.e., mutated). The term “derivative” as used herein also refers to an EphA2 polypeptide, a fragment of an EphA2 polypeptide, an antibody that specifically binds to an EphA2 polypeptide, or an antibody fragment that specifically binds to an EphA2 polypeptide which has been modified, i.e., by the covalent attachment of any type of molecule to the polypeptide. For example, but not by way of limitation, an EphA2 polypeptide, a fragment of an EphA2 polypeptide, an antibody, or antibody fragment may be modified, e.g., by glycosylation, acetylation, pegylation, phosphorylation, amidation, derivatization by known protecting/blocking groups, proteolytic cleavage, linkage to a cellular ligand or other protein, etc. A derivative of an EphA2 polypeptide, a fragment of an EphA2 polypeptide, an antibody, or antibody fragment may be modified by chemical modifications using techniques known to those of skill in the art, including, but not limited to specific chemical cleavage, acetylation, formylation, metabolic synthesis of tunicamycin, etc. Further, a derivative of an EphA2 polypeptide, a fragment of an EphA2 polypeptide, an antibody, or antibody fragment may contain one or more non-classical amino acids. In one embodiment, a polypeptide derivative possesses a similar or identical function as an EphA2 polypeptide, a fragment of an EphA2 polypeptide, an antibody, or antibody fragment described herein. In another embodiment, a derivative of EphA2 polypeptide, a fragment of an EphA2 polypeptide, an antibody, or antibody fragment has an altered activity when compared to an unaltered polypeptide. For example, a derivative antibody or fragment thereof can bind to its epitope more tightly or be more resistant to proteolysis. 
     The term “epitopes” as used herein refers to a portion of an EphA2 polypeptide having antigenic or immunogenic activity in an animal, preferably in a mammal, and most preferably in a mouse or a human. An epitope having immunogenic activity is a portion of an EphA2 polypeptide that elicits an antibody response in an animal. An epitope having antigenic activity is a portion of an EphA2 polypeptide to which an antibody specifically binds as determined by any method well known in the art, for example, by immunoassays. Antigenic epitopes need not necessarily be immunogenic. 
     The “fragments” described herein include a peptide or polypeptide comprising an amino acid sequence of at least 5 contiguous amino acid residues, at least 10 contiguous amino acid residues, at least 15 contiguous amino acid residues, at least 20 contiguous amino acid residues, at least 25 contiguous amino acid residues, at least 40 contiguous amino acid residues, at least 50 contiguous amino acid residues, at least 60 contiguous amino residues, at least 70 contiguous amino acid residues, at least contiguous 80 amino acid residues, at least contiguous 90 amino acid residues, at least contiguous 100 amino acid residues, at least contiguous 125 amino acid residues, at least 150 contiguous amino acid residues, at least contiguous 175 amino acid residues, at least contiguous 200 amino acid residues, or at least contiguous 250 amino acid residues of the amino acid sequence of an EphA2 polypeptide or an antibody that specifically binds to an EphA2 polypeptide. Preferably, antibody fragments are epitope-binding fragments. 
     As used herein, the term “humanized antibody” refers to forms of non-human (e.g., murine) antibodies that are chimeric antibodies which contain minimal sequence derived from non-human immunoglobulin. For the most part, humanized antibodies are human immunoglobulins (recipient antibody) in which hypervariable region residues of the recipient are replaced by hypervariable region residues from a non-human species (donor antibody) such as mouse, rat, rabbit or non-human primate having the desired specificity, affinity, and capacity. In some instances, Framework Region (FR) residues of the human immunoglobulin are replaced by corresponding non-human residues. Furthermore, humanized antibodies may comprise residues which are not found in the recipient antibody or in the donor antibody. These modifications are made to further refine antibody performance. In general, the humanized antibody will comprise substantially all of at least one, and typically two, variable domains, in which all or substantially all of the hypervariable regions correspond to those of a non-human immunoglobulin and all or substantially all of the FRs are those of a human immunoglobulin sequence. The humanized antibody optionally also will comprise at least a portion of an immunoglobulin constant region (Fc), typically that of a human immunoglobulin that specifically binds to an EphA2 polypeptide, that has been altered by the introduction of amino acid residue substitutions, deletions or additions (i.e., mutations). In some embodiments, a humanized antibody is a derivative. Such a humanized antibody comprises amino acid residue substitutions, deletions or additions in one or more non-human CDRs. The humanized antibody derivative may have substantially the same binding, better binding, or worse binding when compared to a non-derivative humanized antibody. In specific embodiments, one, two, three, four, or five amino acid residues of the CDR have been substituted, deleted or added (i.e., mutated). For further details in humanizing antibodies, see European Patent Nos. EP 239,400, EP 592,106, and EP 519,596; International Publication Nos. WO 91/09967 and WO 93/17105; U.S. Pat. Nos. 5,225,539, 5,530,101, 5,565,332, 5,585,089, 5,766,886, and 6,407,213; and Padlan, 1991 , Molecular Immunology  28(4/5):489-498; Studnicka et al., 1994 , Protein Engineering  7(6):805-814; Roguska et al., 1994 , PNAS  91:969-973; Tan et al., 2002 , J. Immunol.  169:1119-25; Caldas et al., 2000 , Protein Eng.  13:353-60; Morea et al., 2000 , Methods  20:267-79; Baca et al., 1997 , J. Biol. Chem.  272:10678-84; Roguska et al., 1996 , Protein Eng.  9:895-904; Couto et al., 1995 , Cancer Res.  55 (23 Supp):5973s-5977s; Couto et al., 1995 , Cancer Res.  55:1717-22; Sandhu, 1994 , Gene  150:409-10; Pedersen et al., 1994 , J. Mol. Biol.  235:959-73; Jones et al., 1986 , Nature  321:522-525; Reichmann et al., 1988 , Nature  332:323-329; and Presta, 1992 , Curr. Op. Struct. Biol.  2:593-596. 
     As used herein, the term “hypervariable region” refers to the amino acid residues of an antibody which are responsible for antigen binding. The hypervariable region comprises amino acid residues from a “Complementarity Determining Region” or “CDR” (i.e. residues 24-34 (L1), 50-56 (L2) and 89-97 (L3) in the light chain variable domain and 31-35 (H1), 50-65 (H2) and 95-102 (H3) in the heavy chain variable domain; Kabat et al.,  Sequences of Proteins of Immunological Interest,  5th Ed. Public Health Service, National Institutes of Health, Bethesda, Md. (1991)) and/or those residues from a “hypervariable loop” (i.e. residues 26-32 (L1), 50-52 (L2) and 91-96 (L3) in the light chain variable domain and 26-32 (H1), 53-55 (H2) and 96-101 (H3) in the heavy chain variable domain; Chothia and Lesk, 1987 , J. Mol. Biol.  196:901-917). CDR residues for 2A4, 2E7, and 12E2 are listed in  FIG. 3 . “Framework Region” or “FR” residues are those variable domain residues other than the hypervariable region residues as herein defined. 
     As used herein, the term “in combination” refers to the use of more than one prophylactic and/or therapeutic agents. The use of the term “in combination” does not restrict the order in which prophylactic and/or therapeutic agents are administered to a subject with a hyperproliferative cell disorder, especially cancer. A first prophylactic or therapeutic agent can be administered prior to (e.g., 1 minute, 5 minutes, 15 minutes, 30 minutes, 45 minutes, 1 hour, 2 hours, 4 hours, 6 hours, 12 hours, 24 hours, 48 hours, 72 hours, 96 hours, 1 week, 2 weeks, 3 weeks, 4 weeks, 5 weeks, 6 weeks, 8 weeks, or 12 weeks before), concomitantly with, or subsequent to (e.g., 1 minute, 5 minutes, 15 minutes, 30 minutes, 45 minutes, 1 hour, 2 hours, 4 hours, 6 hours, 12 hours, 24 hours, 48; hours, 72 hours, 96 hours, 1 week, 2 weeks, 3 weeks, 4 weeks, 5 weeks, 6 weeks, 8 weeks, or 12 weeks after) the administration of a second prophylactic or therapeutic agent to a subject which had, has, or is susceptible to a hyperproliferative cell disorder, especially cancer. The prophylactic or therapeutic agents are administered to a subject in a sequence and within a time interval such that the agent of the invention can act together with the other agent to provide an increased benefit than if they were administered otherwise. Any additional prophylactic or therapeutic agent can be administered in any order with the other additional prophylactic or therapeutic agents. 
     As used herein, the phrase “low tolerance” refers to a state in which the patient suffers from side effects from treatment so that the patient does not benefit from and/or will not continue therapy because of the adverse effects and/or the harm from the side effects outweighs the benefit of the treatment. 
     As used herein, the terms “manage,” “managing” and “management” refer to the beneficial effects that a subject derives from administration of a prophylactic or therapeutic agent, which does not result in a cure of the disease. In certain embodiments, a subject is administered one or more prophylactic or therapeutic agents to “manage” a disease so as to prevent the progression or worsening of the disease. 
     As used herein, the phrase “non-responsive/refractory” is used to describe patients treated with one or more currently available therapies (e.g., cancer therapies) such as chemotherapy, radiation therapy, surgery, hormonal therapy and/or biological therapy/immunotherapy, particularly a standard therapeutic regimen for the particular cancer, wherein the therapy is not clinically adequate to treat the patients such that these patients need additional effective therapy, e.g., remain unsusceptible to therapy. The phrase can also describe patients who respond to therapy yet suffer from side effects, relapse, develop resistance, etc. In various embodiments, “non-responsive/refractory” means that at least some significant portion of the cancer cells are not killed or their cell division arrested. The determination of whether the cancer cells are “non-responsive/refractory” can be made either in vivo or in vitro by any method known in the art for assaying the effectiveness of treatment on cancer cells, using the art-accepted meanings of “refractory” in such a context. In various embodiments, a cancer is “non-responsive/refractory” where the number of cancer cells has not been significantly reduced, or has increased during the treatment. 
     As used herein, the term “potentiate” refers to an improvement in the efficacy of a therapeutic agent at its common or approved dose. 
     As used herein, the terms “prevent,” “preventing” and “prevention” refer to the prevention of the recurrence or spread of a disease in a subject resulting from the administration of a prophylactic or therapeutic agent. 
     As used herein, the terms “prophylactic agent” and “prophylactic agents” refer to any agent(s) that can be used in the prevention of the onset, recurrence or spread of a disorder associated with EphA2 overexpression, particularly cancer. In certain embodiments, the term “prophylactic agent” refers to an EphA2 agonistic antibody or an exposed EphA2 epitope antibody (e.g., 2A4, 2E7, and 12E2). In certain other embodiments, the terms “prophylactic agent” and “prophylactic agents” refer to cancer chemotherapeutics, radiation therapy, hormonal therapy, biological therapy (e.g., immunotherapy), and/or EphA2 antibodies of the invention. In other embodiments, more than one prophylactic agent may be administered in combination. 
     As used herein, a “prophylactically effective amount” refers to that amount of the prophylactic agent sufficient to result in the prevention of the recurrence or spread of cancer. A prophylactically effective amount may refer to the amount of prophylactic agent sufficient to prevent the recurrence or spread of cancer or the occurrence of cancer in a patient, including but not limited to those predisposed to cancer on previously exposed to carcinogens. A prophylactically effective amount may also refer to the amount of the prophylactic agent that provides a prophylactic benefit in the prevention of cancer. Further, a prophylactically effective amount with respect to a prophylactic agent of the invention means that amount of prophylactic agent alone, or in combination with other agents, that provides a prophylactic benefit in the prevention of cancer. Used in connection with an amount of an EphA2 antibody of the invention, the term can encompass an amount that improves overall prophylaxis or enhances the prophylactic efficacy of or synergies with another prophylactic agent. 
     A used herein, a “protocol” includes dosing schedules and dosing regimens. 
     As used herein, the phrase “side effects” encompasses unwanted and adverse effects of a prophylactic or therapeutic agent. Adverse effects are always unwanted, but unwanted effects are not necessarily adverse. An adverse effect from a prophylactic or therapeutic agent might be harmful or uncomfortable or risky. Side effects from chemotherapy include, but are not limited to, gastrointestinal toxicity such as, but not limited to, early and late-forming diarrhea and flatulence, nausea, vomiting, anorexia, leukopenia, anemia, neutropenia, asthenia, abdominal cramping, fever, pain, loss of body weight, dehydration, alopecia, dyspnea, insomnia, dizziness, mucositis, xerostomia, and kidney failure, as well as constipation, nerve and muscle effects, temporary or permanent damage to kidneys and bladder, flu-like symptoms, fluid retention, and temporary or permanent infertility. Side effects from radiation therapy include but are not limited to fatigue, dry mouth, and loss of appetite. Side effects from biological therapies/immunotherapies include but are not limited to rashes or swellings at the site of administration, flu-like symptoms such as fever, chills and fatigue, digestive tract problems and allergic reactions. Side effects from hormonal therapies include but are not limited to nausea, fertility problems, depression, loss of appetite, eye problems, headache, and weight fluctuation. Additional undesired effects typically experienced by patients are numerous and known in the art. Many are described in the  Physicians&#39; Desk Reference  (58 th  ed., 2004). 
     As used herein, the terms “single-chain Fv” or “scFv” refer to antibody fragments comprise the VH and VL domains of antibody, wherein these domains are present in a single polypeptide chain. Generally, the Fv polypeptide further comprises a polypeptide linker between the VH and VL domains which enables the scFv to form the desired structure for antigen binding. For a review of sFv see Plucktbun in  The Pharmacology of Monoclonal Antibodies , vol. 113, Rosenburg and Moore eds. Springer-Verlag, New York, pp. 269-315 (1994). In specific embodiments, scfvs include bispecific scfvs and humanized scFvs. 
     As used herein, the terms “subject” and “patient” are used interchangeably. As used herein, a subject is preferably a mammal such as a non-primate (e.g., cows, pigs, horses, cats, dogs, rats etc.) and a primate (e.g., monkey and human), most preferably a human. 
     As used herein, the terms “treat,” “treating” and “treatment” refer to the eradication, reduction or amelioration of symptoms of a disease or disorder, particularly, the eradication, removal, modification, or control of primary, regional, or metastatic cancer tissue that results from the administration of one or more therapeutic agents. In certain embodiments, such terms refer to the minimizing or delaying file spread of cancer resulting from the administration of one or more therapeutic agents to a subject with such a disease. 
     As used herein, the terms “therapeutic agent” and “therapeutic agents” refer to any agent(s) that can be used in the prevention, treatment, or management of a disorder associated with the overexpression of EphA2, particularly cancer. In certain embodiments, the term “therapeutic agent” refers to an EphA2 agonistic antibody and/an exposed EphA2 epitope antibody, e.g., 2A4, 2E7, and 12E2. In certain other embodiments, the terms “therapeutic agent” and “therapeutic agents” refer to cancer chemotherapeutics, radiation therapy, hormonal therapy, biological therapy/immunotherapy, and/or EphA2 antibody of the invention. In other embodiments, more than one therapeutic agent may be administered in combination. 
     As used herein, a “therapeutically effective amount” refers to that amount of the therapeutic agent sufficient to destroy, modify, control or remove primary, regional or metastatic cancer tissue. A therapeutically effective amount may refer to the amount of therapeutic agent sufficient to delay or minimize the spread of cancer. A therapeutically effective amount may also refer to the amount of the therapeutic agent that provides a therapeutic benefit in the treatment or management of cancer. Further, a therapeutically effective amount with respect to a therapeutic agent of the invention means that amount of therapeutic agent alone, or in combination with other therapies, that provides a therapeutic benefit in the treatment or management of cancer. Used in connection with an amount of an EphA2 antibody of the invention, the term can encompass an amount that improves overall therapy, reduces or avoids unwanted effects, or enhances the therapeutic efficacy of or synergies with another therapeutic agent. 
    
    
     
       4. DESCRIPTION OF THE FIGURES 
         FIG. 1 : Linear map of 4H5 scFv insertion site in MD102 
         FIG. 2 : ELISA titration of scFv supernatants of combinatorial affinity optimized variants (2A4, 2E7, 12E2) on immobilized human EphA2 is summarized in this activity plot, demonstrating the increased activity of the optimize l variants. 
         FIG. 3 : Amino acid sequence alignment of affinity optimized variants 2A4 (Seq ID No: 2), 2E7 (Seq ID No: 18), 12E2 (Seq ID No: 26) with humanized 4H5 scFv (Seq ID No: 10). CDRs represented have the following corresponding Seq ID Nos.: 
       
         
           
             
                 
                 
                 
                 
                 
               
                 
                     
                     
                 
                 
                     
                   Sequence 
                     
                   Seq ID 
                     
                 
                 
                     
                   Identifier 
                   Sequence 
                   No: 
                 
                 
                     
                     
                 
               
              
                 
                     
                 
              
             
             
                 
                 
                 
                 
                 
              
                 
                     
                   2A4CDRH1 
                   SYTMS 
                   3 
                     
                 
                 
                     
                     
                 
                 
                     
                   2A4CDRH2 
                   TISSRGTYTYYPDSVKG 
                   4 
                 
                 
                     
                     
                 
                 
                     
                   2A4CDRH3 
                   EAIFTH 
                   5 
                 
                 
                     
                     
                 
                 
                     
                   2A4CDRL1 
                   KASQDINNYHS 
                   6 
                 
                 
                     
                     
                 
                 
                     
                   2A4CDRL2 
                   RANRLVD 
                   7 
                 
                 
                     
                     
                 
                 
                     
                   2A4CDRL3 
                   LKYNVFPYT 
                   8 
                 
                 
                     
                     
                 
                 
                     
                   4H5CDRH1 
                   SYTMS 
                   11 
                 
                 
                     
                     
                 
                 
                     
                   4H5CDRH2 
                   TISSGGTYTYYPDSVKG 
                   12 
                 
                 
                     
                     
                 
                 
                     
                   4H5CDRH3 
                   EAIFTY 
                   13 
                 
                 
                     
                     
                 
                 
                     
                   4H5CDRL1 
                   KASQDINNYLS 
                   14 
                 
                 
                     
                     
                 
                 
                     
                   4H5CDRL2 
                   RANRLVD 
                   15 
                 
                 
                     
                     
                 
                 
                     
                   4H5CDRL3 
                   LKYDVFPYT 
                   16 
                 
                 
                     
                     
                 
                 
                     
                   2E7CDRH1 
                   SYTMS 
                   19 
                 
                 
                     
                     
                 
                 
                     
                   2E7CDRH2 
                   TISSRGTYTYYPDSVKG 
                   20 
                 
                 
                     
                     
                 
                 
                     
                   2E7CDRH3 
                   EAIFTH 
                   21 
                 
                 
                     
                     
                 
                 
                     
                   2E7CDRL1 
                   KASQDINNYGS 
                   22 
                 
                 
                     
                     
                 
                 
                     
                   2E7CDRL2 
                   RANRLVD 
                   23 
                 
                 
                     
                     
                 
                 
                     
                   2E7CDRL3 
                   LKYNRFPYT 
                   24 
                 
                 
                     
                     
                 
                 
                     
                   12E2CDRH1 
                   SYTMS 
                   27 
                 
                 
                     
                     
                 
                 
                     
                   12E2CDRH2 
                   TISSRGTYTYYPDSVKG 
                   28 
                 
                 
                     
                     
                 
                 
                     
                   12E2CDRH3 
                   EAIFTY 
                   29 
                 
                 
                     
                     
                 
                 
                     
                   12E2CDRL1 
                   KASQDINNYLS 
                   30 
                 
                 
                     
                     
                 
                 
                     
                   12E2CDRL2 
                   RANRLFD 
                   31 
                 
                 
                     
                     
                 
                 
                     
                   12E2CDRL3 
                   LKYDRFPYT 
                   32 
                 
                 
                     
                     
                 
              
             
           
         
       
         FIG. 4A : Nucleic Acid and Amino Acid Sequences of 4H5 (Seq ID Nos.: 9, 10). 
         FIG. 4B : Nucleic Acid and Amino Acid Sequences of 2A4 (Seq ID Nos.: 1, 2). 
         FIG. 4C : Nucleic Acid and Amino Acid Sequences of 2E7 (Seq ID Nos.: 17, 18). 
         FIG. 4D : Nucleic Acid and Amino Acid Sequences of 12E2 Seq ID Nos.: 25, 26). 
         FIG. 5 : Binding affinity measurements of scFv fragments (2A4, 2E7, 12E2) to human EphA2 as compared to EA2 scFv and 4H5 scFv. 2A4, 2E7 and 12E2 demonstrate marked improvements in binding affinities to EphA2 as compared to EA2 and 4H5. 
     
    
    
     5. DETAILED DESCRIPTION OF THE INVENTION 
     The present invention provides antibodies that specifically bind to EphA2. In particular, the invention provides the following antibodies that specifically bind to EphA2: 2A4, 2E7, and 12E2. The present invention also provides for antibodies comprising a variable heavy (“VH”) domain and/or a variable light (“VL”) domain having an amino acid sequence of the VH domain and/or VL domain, respectively, of 2A4 (Seq ID No: 2), 2E7 (Seq ID No: 18), or 12E2 (Seq ID No: 26). Such antibodies may further comprise any constant region known in the art, preferably any human constant region known in the art, including, but not limited to, human light chain kappa (K), human light chain lambda (λ), the constant region of IgG 1 , the constant region of IgG 2 , the constant region of IgG 3  or the constant region of IgG 4 . In addition, the present invention provides for antibodies comprising one or more complementarity determining regions (“CDRs”) of 2A4, 2E7, or 12E2. 
     Decreased EphA2 activity selectively inhibits malignant cancer cell growth and can be achieved with EphA2 agonistic monoclonal antibodies. Although not intending to be bound by any mechanism of action, this inhibition of malignant cell growth is achieved by stimulating (i.e., agonizing) EphA2 signaling thereby causing EphA2 phosphorylation that leads to its degradation. Malignant cell growth is decreased dire to the decreased EphA2 levels and, therefore, ligand-independent EphA2 signaling. 
     Accordingly, the present invention relates to methods and compositions that provide for the treatment, inhibition, and management of cancer, particularly metastatic cancer. A particular aspect of the invention relates to methods and compositions containing compounds that inhibit cancer cell proliferation and invasion, particularly those cancer cells that overexpress EphA2. The present invention further relates to methods and compositions for the treatment, inhibition, or management of metastases of cancers of epithelial cell origin, especially human cancers of the breast, lung, skin, and prostate bladder, kidney and pancreas. Further compositions and methods of the invention include other types of active ingredients in combination with the EphA2 antibodies of the invention. 
     The present invention also relates to methods for the treatment, inhibition, and management of cancer that has become partially or completely refractory to current or standard cancer treatment, such as chemotherapy, radiation therapy, hormonal therapy, and biological therapy. 
     The invention further provides diagnostic methods using the EphA2 antibodies of the invention to evaluate the efficacy of cancer treatment, either EphA2-based or not EphA2-based. The diagnostic methods of the invention can also be used to prognose or predict cancer progression. In particular embodiments, the diagnostic methods of the invention provide methods of imaging and localizing metastases and methods of diagnosis and prognosis using tissues and fluids distal to the primary tumor site (as well as methods using tissues and fluids of the primary tumor). In other embodiments, the diagnostic methods of the invention provide methods of imaging and localizing metastases and methods of diagnosis and prognosis in vivo. 
     5.1 Antibodies 
     As discussed above, the invention encompasses administration of antibodies (preferably monoclonal antibodies) or fragments thereof that specifically bind to and agonize EphA2 signaling (“EphA2 agonistic antibodies”) and/or preferentially bind epitopes on EphA2 that are selectively exposed or increased on cancer cells but not non-cancer cells (“exposed EphA2 epitope antibodies”). In one embodiment, the antibody binds to the extracellular domain of EphA2 and, preferably, also agonizes EphA2, e.g., increases EphA2 phosphorylation. In another embodiment, the antibody binds to the extracellular domain of EphA2 and, preferably, also binds an epitope on EphA2 that is selectively exposed or increased on cancer cells but not non-cancer cells. In a further embodiment, the antibody is 2A4, 2E7, or 12E2. In another embodiment, the antibody binds to an epitope bound by 2A4, 2E7, or 12E2 and/or competes for EphA2 binding with 2A4, 2E7, or 12E2, e.g. as assayed by ELISA. In other embodiments, the antibody of the invention specifically binds to and agonizes EphA2 signaling and/or preferentially binds an epitope-on EphA2 that is selectively exposed or increased on cancer cells but not non-cancer cells and may or may not compete for binding with an EphA2 ligand, e.g., Ephrin A1. 
     The present invention provides antibodies that specifically bind to EpbA2. In particular, the invention provides the following antibodies that specifically bind to EphA2: 2A4 or an antigen-binding fragment thereof, 2E7 or an antigen-binding fragment thereof, or 12E2 or an antigen-binding fragment thereof. In one embodiment, an antibody that specifically binds to EphA2 is 2A4 or an antigen-binding fragment thereof (e.g., one or more CDRs of 2A4). In another embodiment, an antibody that specifically binds to EphA2 is 2E7) or an antigen-binding fragment thereof (e.g., one or more CDRs of 2E7). In another embodiment, an antibody that specifically binds to EphA2 is 12E2 or an antigen-binding fragment thereof (e.g., one or more CDRs of 12E2). 
     
       
         
           
               
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Sequence 
                   
                 Seq ID 
                   
               
               
                   
                 Identifier 
                 Sequence 
                 No: 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 2A4CDRH1 
                 SYTMS 
                 3 
                   
               
               
                   
                   
               
               
                   
                 2A4CDRH2 
                 TISSRGTYTYYPDSVKG 
                 4 
               
               
                   
                   
               
               
                   
                 2A4CDRH3 
                 EAIFTH 
                 5 
               
               
                   
                   
               
               
                   
                 2A4CDRL1 
                 KASQDINNYHS 
                 6 
               
               
                   
                   
               
               
                   
                 2A4CDRL2 
                 RANRLVD 
                 7 
               
               
                   
                   
               
               
                   
                 2A4CDRL3 
                 LKYNVFPYT 
                 8 
               
               
                   
                   
               
               
                   
                 4H5CDRH1 
                 SYTMS 
                 11 
               
               
                   
                   
               
               
                   
                 4H5CDRH2 
                 TISSGGTYTYYPDSVKG 
                 12 
               
               
                   
                   
               
               
                   
                 4H5CDRH3 
                 EAIFTY 
                 13 
               
               
                   
                   
               
               
                   
                 4H5CDRL1 
                 KASQDINNYLS 
                 14 
               
               
                   
                   
               
               
                   
                 4H5CDRL2 
                 RANRLVD 
                 15 
               
               
                   
                   
               
               
                   
                 4H5CDRL3 
                 LKYDVFPYT 
                 16 
               
               
                   
                   
               
               
                   
                 2E7CDRH1 
                 SYTMS 
                 19 
               
               
                   
                   
               
               
                   
                 2E7CDRH2 
                 TISSRGTYTYYPDSVKG 
                 20 
               
               
                   
                   
               
               
                   
                 2E7CDRH3 
                 EAIFTH 
                 21 
               
               
                   
                   
               
               
                   
                 2E7CDRL1 
                 KASQDINNYGS 
                 22 
               
               
                   
                   
               
               
                   
                 2E7CDRL2 
                 RANRLVD 
                 23 
               
               
                   
                   
               
               
                   
                 2E7CDRL3 
                 LKYNRFPYT 
                 24 
               
               
                   
                   
               
               
                   
                 12E2CDRH1 
                 SYTMS 
                 27 
               
               
                   
                   
               
               
                   
                 12E2CDRH2 
                 TISSRGTYTYYPDSVKG 
                 28 
               
               
                   
                   
               
               
                   
                 12E2CDRH3 
                 EAIFTY 
                 29 
               
               
                   
                   
               
               
                   
                 12E2CDRL1 
                 KASQDINNYLS 
                 30 
               
               
                   
                   
               
               
                   
                 12E2CDRL2 
                 RANRLFD 
                 31 
               
               
                   
                   
               
               
                   
                 12E2CDRL3 
                 LKYDRFPYT 
                 32 
               
               
                   
                   
               
            
           
         
       
     
     The present invention provides antibodies that specifically bind EphA2, said antibodies comprising a VH domain having an amino acid sequence of the VH domain of 2A4 (Seq ID No: 2), 2E7 (Seq ID No: 18), or 12E2 (Seq ID No: 26) as disclosed in  FIG. 3 . In one embodiment, an antibody that specifically binds to EphA 2 comprises a VH domain having an amino acid sequence of the VH domain of 2A4 (Seq ID No: 2). In another embodiment, an antibody that specifically binds to EphA2 comprises a VH domain having an amino acid sequence of the VH domain of 2E7 (Seq ID No: 18). In another embodiment, an antibody that specifically binds to EphA2 comprises a VH domain having an amino acid sequence of the VH domain of 12E2 (Seq ID No: 26). 
     The present invention provides antibodies that specifically bind to EphA2, said antibodies comprising a VH CDR having an amino acid sequence of any one of the VH CDRs (Seq ID Nos: 3-6, 11-13, 19-21, and 27-29) listed in  FIG. 3 . In particular, the invention provides antibodies that specifically bind to EphA2, said antibodies comprising (or alternatively, consisting of) one, two, three, four, five or more VH CDRs having an amino acid sequence of any of the VH CDRs (Seq ID Nos: 3-6, 11-13, 19-21, and 27-29) listed in  FIG. 3 . In one embodiment, an antibody that specifically bin is to EphA2 comprises a VH CDR1 having the amino acid sequence of the VH CDR1 from 2A4 (Seq ID No: 3), 2E7 (Seq ID No: 19), or 12E2 (Seq ID No: 27) as disclosed in  FIG. 3 . In another embodiment, an antibody that specifically binds to EphA2 comprises a VH CDR2 having the amino acid sequence of the VH CDR2 from 2A4 (Seq ID No: 4), 2E7 (Seq ID No: 20), or 12E2 (Seq ID No: 28) as disclosed in  FIG. 3 . In another embodiment, an antibody that specifically binds to EpbA2 comprises a VH CDR3 having the amino acid sequence of the VH CDR3 from 2A4 (Seq ID No: 5), 2E7 (Seq ID No: 21), or 12E2 (Seq ID No: 29) as disclosed in  FIG. 3 . In another embodiment, an antibody that specifically binds to EphA2 comprises a VH CDR1 having the amino acid sequence of the VH CDR1 from 2A4 (See ID No: 3), 2E7 (Seq ID No: 19), or 12E2 (Seq ID No: 27) as disclosed in  FIG. 3  and a VH CDR2 having the amino acid sequence of the VH CDR2 from 2A4 (Seq ID No: 4), 2E7 (Seq ID No: 20), or 12E2 (Seq ID No: 28) as disclosed in  FIG. 3 . In another embodiment, an antibody that specifically binds to EphA2 comprises a VH CDR1 having the amino acid sequence of the VH CDR1 from 2A4 (Seq ID No: 3), 2E7 (Seq ID No: 19), or 12E2 (Seq ID No: 27) as disclosed in  FIG. 3  and a VH CDR3 having the amino acid sequence of the VH CDR3 from 2A4 (Seq ID No: 5), 2E7 (Seq ID No: 21), or 12E2 (Seq ID No: 29) as disclosed in  FIG. 3 . In another embodiment, an antibody that specifically binds to EphA2 comprises a VH CDR2 having the amino acid sequence of the VH CDR2 from 2A4 (Seq ID No: 4), 2E7 (Seq ID No: 20), or 12E2 (Seq ID No: 28) as disclosed in  FIG. 3  and a VH CDR3 having the amino acid sequence of the VB CDR3 from 2A4 (Seq ID No: 5), 2E7 (Seq ID No: 21), or 12E2 (Seq ID No: 29) as disclosed in  FIG. 3 . In another embodiment, an antibody that specifically binds to EphA2 comprises a VH CDR1 having the amino acid sequence of the VH CDR1 from 2A4 (Seq ID No: 3), 2E7 (Seq ID No: 19), or 12E2 (Seq ID No: 27) as disclosed in  FIG. 3 , a VH CDR2 having the amino acid sequence of the VH CDR2 from 2A4 (Seq ID No: 4), 2E7 (Seq ID No: 20), or 12E2 (Seq ID No: 28) as disclosed in  FIG. 3 , and a VH CDR3 having the amino acid sequence of the VH CDR3 from 2A4 (Seq ID No: 5), 2E7 (Seq ID No: 21), or 12E2 (Seq ID No: 29) as disclosed in  FIG. 3 . 
     The present invention provides antibodies that specifically bind to EphA2, said antibodies comprising a VL domain having an amino acid sequence of the VL domain from 2A4 (Seq ID No: 2), 2E7 (Seq ID No: 18), or 12E2 (Seq ID No: 26) as disclosed in  FIG. 3 . 
     The present invention also provides antibodies that specifically bind to EphA2, said antibodies comprising a VL CDR having an amino acid sequence of any one of the VL CDRs (Seq ID Nos: 6-8, 14-16, 22-24, and 30-32) listed in  FIG. 3 . In particular, the invention provides antibodies that specifically bind to EphA2, said antibodies comprising (or alternatively, consisting of) one, two, three or more VL CDRs having an amino acid sequence of any of the VL CDRs (Seq ID Nos: 6-8, 14-16, 22-24, and 30-32) listed in  FIG. 3 . In one embodiment, an antibody that specifically binds to EphA2 comprises a VL CDR1 having the amino acid sequence of the VL CDR1 from 2A4 (Seq ID No: 6), 2E7 (Seq ID No: 22), or 12E2 (Seq ID No: 30) as disclosed in  FIG. 3 . In another embodiment, an antibody that specifically binds to EphA2 comprises a VL CDR2 having the amino acid sequence of the VL CDR2 from 2A4 (Seq ID No: 7), 2E7 (Seq ID No: 23), or 12E2 (Seq ID No: 31) as disclosed in  FIG. 3 . In another embodiment, an antibody that specifically binds to EphA2 comprises a VL CDR3 having the amino acid sequence of the VL CDR3 from 2A4 (Seq ID No: 8), 2E7 (Seq ID No: 24), or 12E2 (Seq ID No: 32) as disclosed in  FIG. 3 . In another embodiment, an antibody of that specifically binds to EphA2 comprises a VL CDR1 having the amino acid sequence of the VL CDR1 from 2A4 (Seq ID No: 6), 2E7 (Seq ID No: 22), or 12E2 (Seq ID No: 30) as disclosed in  FIG. 3 , and a VL CDR2 having the amino acid sequence of the VL CDR2 from 2A4 (Seq ID No: 7), 2E7 (Seq ID No: 23), or 12E2 (Seq ID No: 31) as disclosed in  FIG. 3 . In another embodiment, an antibody that specifically binds to EphA2 comprises a VL CDR1 having the amino acid sequence of the VL CDR1 from 2A4 (Seq ID No: 6), 2E7 (Seq ID No: 22), or 12E2 (Seq ID No: 30) as disclosed in  FIG. 3  and a VL CDR3 having the amino acid sequence of the VL CDR3 from 2A4 (Seq ID No: 8), 2E7 (Seq ID No: 24), or 12E2 (Seq ID No: 32) as disclosed in  FIG. 3 . In another embodiment, an antibody that specifically binds to EphA2 comprises a VL CDR2 having the amino acid sequence of the VL CDR2 from 2A4 (Seq ID No: 7), 2E7 (Seq ID No: 23), or 12E2 (Seq ID No: 31) as disclosed in  FIG. 3  and a VL CDR3 having the amino acid sequence of the VL CDR3 from 2A4 (Seq ID No: 8), 2E7 (Seq ID No: 24), or 12E2 (Seq ID No: 32) as disclosed in  FIG. 3 . In another embodiment, an antibody that specifically binds to EphA2 comprises a VL CDR1 having the amino acid sequence of the VL CDR1 from 2A4 (Seq ID No: 6), 2E7 (Seq ID No: 22), or 12E2 (Seq ID No: 30) as disclosed in  FIG. 3 , a VL CDR2 having the amino acid sequence of the VL CDR2 from 2A4 (Seq ID No: 7), 2E7 (Seq ID No: 23), or 12E2 (Seq ID No: 31) as disclosed in  FIG. 3 , and a VL CDR3 having the amino acid sequence of the VL CDR3 from 2A4 (Seq ID No: 8), 2E7 (Seq ID No: 24), or 12E2 (Seq ID No: 32) as disclosed in  FIG. 3 . 
     The present invention provides antibodies that specifically bind to EpbA2, said antibodies comprising one or more VH CDRs and one or more VL CDRs listed in FIG.  3 . In particular, the invention provides an antibody that specifically binds to EphA2, said antibody comprising (or alternatively, consisting of) a VH CDR1 and a VL CDR1; a VH CDR1 and a VL CDR2; a VH CDR1 and a VL CDR3; a VH CDR2 and a VL CDR1; VH CDR2 and VL CDR2; a VH CDR2 and a VL CDR3; a VH CDR3 and a VH CDR1; a VH CDR3 and a VL CDR2; a VH CDR3 and a VL CDR3; a VH CDR1, a VH CDR2 and a VL CDR1; a VH CDR1, a VH CDR2 and a VL CDR2; a VH CDR1, a VH CDR2 and a VL CDR3; a VH CDR2, a VH CDR3 and a VL CDR1, a VH CDR2, a VH CDR3 and a VL CDR2; a VH CDR1, a VH CDR2 and a VL CDR3; a VH CDR1, a VL CDR1 and a VL CDR2; a VH CDR1, a VL CDR1 and a VL CDR3; a VH CDR2, a VL CDR1 and a VL CDR2; a VH CDR2, a VL CDR1 and a VL CDR3; a VH CDR3, a VL CDR1 and a VL CDR2; a VH CDR3, a VL CDR1 and a VL CDR3; a VH CDR1, a VH CDR2, a VH CDR3 and a VL CDR1; a VH CDR1, a VH CDR2, a VH CDR3 and a VL CDR2; a VH CDR1, a VH CDR2, a VH CDR3 and a VL CDR3; a VH CDR1, a VH CDR2, a VL CDR1 and a VL CDR2; a VH CDR1, a VII CDR2, a VL CDR1 and a VL CDR3; a VH CDR1, a VH CDR3, a VL CDR1 and a VL CDR2; a VH CDR1, a VH CDR3, a VL CDR1 and a VL CDR3; a VH CDR2, a VH CDR3, a VL CDR1 and a VL CDR2; a VH CDR2, a VH CDR3, a VL CDR1 and a VL CDR3; a VH CDR2, a VH CDR3, a VL CDR2 and a VL CDR3; a VH CDR1, a VH CDR2, a VH CDR3, a VL CDR1 and a VL CDR2; a VH CDR1, a VH CDR2, a VH CDR3, a VL CDR1 and a VL CDR3; a VH CDR1, a VH CDR2, a VL CDR1, a VL CDR2, and a VL CDR3; a VH CDR1, a VH CDR3, a VL CDR1, a VL CDR2, and a VL CDR3; a VH CDR2, a VH CDR3, a VL CDR1, a VL CDR2, and a VL CDR3; or any combination thereof of the VH CDRs and VL CDRs listed in  FIG. 3 . 
     In one embodiment, an antibody that specifically binds to EphA2 comprises a VH CDR1 having the amino acid sequence of the VH CDR1 from 2A4 (Seq ID No: 3), 2E7 (Seq ID No: 19), or 12E2 (Seq ID No: 27) as disclosed in  FIG. 3  and a VL CDR1 having the amino acid sequence of the VL CDR1 from 2A4 (Seq ID No: 6), 2E7 (Seq ID No: 22), or 12E2 (Seq ID No: 30) as disclosed in  FIG. 3 . In another embodiment, an antibody that specifically binds to EphA2 comprises a VH CDR1 having the amino acid sequence of the VH CDR1 from 2A4 (Seq ID No: 3), 2E7 (Seq ID No: 19), or 12E2 (Seq ID No: 27) as disclosed in  FIG. 3  and a VL CDR2 having the amino acid sequence of the VL CDR2 from 2A4 (Seq ID No: 7), 2E7 (Seq ID No: 23), or 12E2 (Seq ID No: 31) as disclosed in  FIG. 3 . In another embodiment, an antibody that specifically binds to EphA2 comprises a VH CDR1 having the amino acid sequence of the VH CDR1 from 2A4 (Seq ID No: 3), 2E7 (Seq ID No: 19), or 12E2 (Seq ID No: 27) as disclosed in  FIG. 3  and a VL CDR3 having an amino acid sequence of the VL CDR3 from 2A4 (Seq ID No: 8), 2E7 (Seq ID No: 24), or 12E2 (Seq ID No: 32) as disclosed in  FIG. 3 . 
     In one embodiment, an antibody that specifically binds to EphA2 comprises a VH CDR2 having the amino acid sequence of the VH CDR2 from 2A4 (Seq ID No: 4), 2E7 (Seq ID No: 20), or 12E2 (Seq ID No: 28) as disclosed in  FIG. 3  and a VL CDR1 having the amino acid sequence of the VL CDR1 from 2A4 (Seq ID No: 6), 2E7 (Seq ID No: 22), or 12E2 (Seq ID No: 30) as disclosed in  FIG. 3 . In another embodiment, an antibody that specifically binds to EphA2 comprises a VH CDR2 having the amino acid sequence of the VH CDR2 from 2A4 (Seq ID No: 4), 2E7 (Seq ID No: 20), or 12E2 (Seq ID No: 28) as disclosed in  FIG. 3  and a VL CDR2 having the amino acid sequence of the VL CDR2 from 2A4 (Seq ID No: 7), 2E7 (Seq ID No: 23), or 12E2 (Seq ID No: 31) as disclosed in  FIG. 3 . In another embodiment, an antibody that specifically binds to EphA2 comprises a VH CDR2 having the amino acid sequence of the VII CDR2 from 2A4 (Seq ID No: 4), 2E7 (Seq ID No: 20), or 12E2 (Seq ID No: 28) as disclosed in  FIG. 3  and a VL CDR3 having an amino acid sequence of the VL CDR3 from 2A4 (Seq ID No: 8), 2E7 (Seq ID No: 24), or 12E2 (Seq ID No: 32) as disclosed in  FIG. 3 . 
     In one embodiment, an antibody that specifically binds to EphA2 comprises a VH CDR3 having the amino acid sequence of the VH CDR3 from 2A4 (Seq ID No: 5), 2E7 (Seq ID No: 21), or 12E2 (Seq ID No: 29) as disclosed in  FIG. 3  and a VL CDR1 having the amino acid sequence of the VL CDR1 from 2A4 (Seq ID No: 6), 2E7 (Seq ID No: 22), or 12E2 (Seq ID No: 30) as disclosed in  FIG. 3 . In another embodiment, an antibody that specifically binds to EphA2 comprises a VH CDR3 having the amino acid sequence of the VH CDR3 from 2A4 (Seq ID No: 5), 2E7 (Seq ID No: 21), or 12E2 (Seq ID No: 29) as disclosed in  FIG. 3  and a VL CDR2 having the amino acid sequence of the VL CDR2 from 2A4 (Seq ID No: 7), 2E7 (Seq ID No: 23), or 12E2 (Seq ID No: 31) as disclosed in  FIG. 3 . In another embodiment, an antibody that specifically binds to EphA2 comprises a VH CDR3 having the amino acid sequence of the VH CDR3 from 2A4 (Seq ID No: 5), 2E7 (Seq ID No: 21), or 12E2 (Seq ID No: 29) as disclosed in  FIG. 3  and a VL CDR3 having an amino acid sequence of the VL CDR32A4 (Seq ID No: 8), 2E7 (Seq ID No: 24), or 12E2 (Seq ID No: 32) as disclosed in  FIG. 3 . 
     The present invention provides antibodies that specifically bind to EphA2, said antibodies encoded by a nucleic acid sequence comprising the nucleotide sequence of 2A4 (Seq ID No: 1), 2E7 (Seq ID No: 17), or 12E2 (Seq ID No: 25) as disclosed in  FIG. 4  or an antigen-binding fragment thereof. In a specific embodiment, an antibody that specifically binds to EphA2 comprises a VH domain encoded by a nucleic acid sequence having a nucleotide sequence of the VH domain of 2A4 (Seq ID No: 37), 2E7 (Seq ID No: 41), or 12E2 (Seq ID No: 45) as disclosed in  FIG. 4 . In another embodiment, an antibody that specifically binds to EphA2 comprises a VL domain encoded by a nucleic acid sequence having a nucleotide sequence of the VL domain of 2A4 (Seq ID No: 39), 2E7 (Seq ID No: 43), or 12E2 (Seq ID No: 47) as disclosed in  FIG. 4 . In another embodiment, an antibody that specifically binds to EphA2 comprises a VH domain and a VL domain encoded by a nucleic acid sequence having a nucleotide sequence of the VH domain and VL domain of 2A4 (Seq ID Nos: 37,39), 2E7 (Seq ID Nos: 41,43), or 12E2 (Seq ID Nos: 45,47) as disclosed in  FIG. 4 . 
     In another embodiment, an antibody that specifically binds to EphA2 comprises a VH CDR encoded by a nucleic acid sequence having a nucleotide sequence of a VH CDR of 2A4 (Seq ID Nos: 3-5), 2E7 (Seq ID Nos: 19-21), or 12E2 (Seq ID Nos: 27-29) as disclosed in  FIG. 4 . In another embodiment, an antibody that specifically binds to EphA2 comprises a VL CDR encoded by a nucleic acid sequence having a nucleotide sequence of a VL CDR of 2A4 (Seq ID Nos: 6-8), 2E7 (Seq ID Nos: 22-24), or 12E2 (Seq ID Nos: 31-32) as disclosed in Figure, 4. In another embodiment, an antibody that specifically binds to EphA2 comprises a VH CDR and a VL CDR encoded by a nucleic acid sequence having a nucleotide sequence of a VH CDR and a VL CDR of 2A4 (Seq ID Nos: 3-8), 2E7 (Seq ID Nos: 19-24), or 12E2 (Seq ID Nos: 27-32) as disclosed in  FIG. 4 . 
     The present invention provides for a nucleic acid molecule, generally isolated, encoding an antibody of the present invention that specifically binds to EphA2. In particular, the invention provides an isolated nucleic acid molecule encoding an antibody that specifically binds to EphA2, said antibody having the amino acid sequence of 2A4 (Seq ID No:2), 2E7 (Seq ID No: 18), or 12E2 (Seq ID No:26) as disclosed in  FIGS. 3 and 4 , or an antigen-binding fragment thereof. In one embodiment, an isolated nucleic acid molecule encodes an antibody that specifically binds to EphA2, said antibody having the amino acid sequence of 2A4 (Seq ID No:2). In another embodiment, an isolated nucleic acid molecule encodes an antibody that specifically binds to EphA2, said antibody having the amino acid sequence of 2E7 (Seq ID No:18). In a further embodiment, an isolated nucleic acid molecule encodes an antibody that specifically binds to EphA2, said antibody having the amino acid sequence of 12E2 (Seq ID No:26). 
     The invention provides an isolated nucleic acid molecule encoding an antibody that specifically binds to EphA2, said antibody comprising (alternatively, consisting of) a VH domain having an amino acid sequence of a VH domain of 2A4 (Seq ID No: 38), 2E7 (Seq ID No: 42), or 12E2 (Seq ID No: 46) as disclosed in  FIG. 3 . In one embodiment, an isolated nucleic acid molecule encodes an antibody that specifically binds to EphA2, said antibody comprising a VH domain having the amino acid sequence of the VH domain of 2A4 (Seq ID No: 38). In another embodiment, an isolated nucleic acid molecule encodes an antibody that specifically binds to EphA2, said antibody comprising a VH domain having the amino acid sequence of the VH domain of 2E7 (Seq ID No: 42). In a further embodiment, an isolated nucleic acid molecule encodes an antibody that specifically binds to EphA2, said antibody comprising a VH domain having the amino acid sequence of the VH domain of 12E2 (Seq ID No: 46). 
     The invention provides an isolated nucleic acid molecule encoding an antibody that specifically binds to EphA2, said antibody comprising (alternatively, consisting of) a VH CDR having an amino acid sequence of any of the VH CDRs (Seq ID Nos: 3-6, 11-13, 19-21, and 27-29) listed in  FIG. 3 . In particular, the invention provides an isolated nucleic acid molecule encoding an antibody that specifically binds to EphA2, said antibody comprising one, two, three, four, five or more VH CDRs having an amino acid sequence of any of the VH CDRs (Seq ID Nos: 3-5, 11-13, 19-21, and 27-29) listed in  FIG. 3 . In one embodiment, an isolated nucleic acid molecule encodes an antibody that specifically binds to EphA2, said antibody comprising a VH CDR1 (Seq ID Nos: 3, 11, 19, and 27) having the amino acid sequence of a VH CDR1 listed in  FIG. 3 . In another embodiment, an isolated nucleic acid molecule encodes an antibody that specifically binds to EphA2, said antibody comprising a VH CDR2 having the amino acid sequence of a VII CDR2 (Seq ID Nos: 4, 12, 20, and 28) listed in  FIG. 3 . In another embodiment, an isolated nucleic acid molecule encodes an antibody that specifically binds to EphA2, said antibody comprising a VH CDR3 having the amino acid sequence of the VH CDR3 (Seq ID Nos: 5, 13, 21, and 29) listed in  FIG. 3 . 
     The invention provides an isolated nucleic acid molecule encoding an antibody that specifically binds to EphA2, said antibody comprising (alternatively, consisting of) a VL domain having an amino acid sequence of a VL domain of 2A4, 2E7, or 12E2 (Seq ID Nos: 40, 44, and 48) as disclosed in  FIG. 3 . In one embodiment, an isolated nucleic acid molecule encodes an antibody that specifically binds to EphA2, said antibody comprising a VL domain having the amino acid sequence of the VL domain of 2A4 (Seq ID No: 40). In another embodiment, an isolated nucleic acid molecule encodes an antibody that specifically binds to EphA2, said antibody comprising a VL domain having the amino acid sequence of the VL domain of 2E7 (Seq ID No: 44). In a further embodiment, an isolated nucleic acid molecule encodes an antibody that specifically binds to EphA2, said antibody comprising a VL domain having the amino acid sequence of the VL domain of 12E2 (Seq ID No: 48). 
     The invention also provides an isolated nucleic acid molecule encoding an antibody that specifically binds to EphA2, said antibody comprising (alternatively, consisting of) a VL CDR having an amino acid sequence of any of the VL CDRs (Seq ID Nos: 3, 11, 19, and 27) listed in  FIG. 3 . In particular, the invention provides an isolated nucleic acid molecule encoding an antibody that specifically binds to EphA2, said antibody comprising one, two, three or more VL CDRs having an amino acid sequence of any of the VL CDRs (Seq ID Nos: 6-8, 14-16, 22-24, and 30-32) listed in  FIG. 3 . In one embodiment, an isolated nucleic acid molecule encodes an antibody that specifically binds to EphA2, said antibody comprising a VL CDR1 having the amino acid sequence of the VH CDR1 (Seq ID Nos: 6, 14, 22, and 30) listed in  FIG. 3 . In another embodiment, an isolated nucleic acid molecule encodes an antibody that specifically binds to EphA2, said antibody comprising a VL CDR2 having the amino acid sequence of the VL CDR2 (Seq ID Nos: 7, 15, 23, and 31) listed in  FIG. 3 . In another embodiment, an isolated nucleic acid molecule encodes an antibody that specifically binds to EphA2, said antibody comprising a VL CDR3 having the amino acid sequence of the VL CDR3 (Seq ID Nos: 8, 16, 24, and 32) listed in  FIG. 3 . 
     The present invention provides nucleic acid molecules encoding antibodies that specifically bind to EphA2, said antibodies comprising one or more VH CDRs and one or more VL CDRs listed in  FIG. 3 . In particular, the invention provides an isolated nucleic acid molecule encoding an antibody that specifically binds to EphA2, said antibody comprising (or alternatively, consisting of) a VH CDR1 and a VL CDR1; a VH CDR1 and a VL CDR2; a VH CDR1 and a VL CDR3; a VH CDR2 and a VL CDR1; VH CDR2 and VL CDR2; a VH CDR2 and a VL CDR3; a VH CDR3 and a VH CDR1; a VH CDR3 and a VL CDR2; a VH CDR3 and a VL CDR3; a VH CDR1, a VH CDR2 and a VL CDR1; a VH CDR1, a VH CDR2 and a VL CDR2; a VH CDR1, a VH CDR2 and a VL CDR3; a VH CDR2, a VH CDR3 and a VL CDR1, a VH CDR2, a VH CDR3 and a VL CDR2; a VH CDR2, a VH CDR2 and a VL CDR3; a VH CDR1, a VL CDR1 and a VL CDR2; a VH CDR1, a VL CDR1 and a VL CDR3; a VH CDR2, a VL CDR1 and a VL CDR2; a VH CDR2, a VL CDR1 and a VL CDR3; a VH CDR3, a VL CDR1 and a VL CDR2; a VH CDR3, a VL CDR1 and a VL CDR3; a VH CDR1, a VH CDR2, a VH CDR3 and a VL CDR1; a VH CDR1, a VH CDR2, a VH CDR3 and a VL CDR2; a VH CDR1, a VH CDR2, a VH CDR3 and a VL CDR3; a VH CDR1, a VH CDR2, a VL CDR1 and a VL CDR2; a VH CDR1, a VH CDR2, a VL CDR1 and a VL CDR3; a VH CDR1, a VH CDR3, a VL CDR1 and a VL CDR2; a VH CDR1, a VH CDR3, a VL CDR1 and a VL CDR3; a VH CDR2, a VH CDR3, a VL CDR1 and a VL CDR2; a VH CDR2, a VH CDR3, a VL CDR1 and a VL CDR3; a VH CDR2, a VH CDR3, a VL CDR2 and a VL CDR3; a VH CDR1, a VH CDR2, a VH CDR3, a VL CDR1 and a VL CDR2; a VH CDR1, a VH CDR2, a VH CDR3, a VL CDR1 and a VL CDR3; a VH CDR1, a VH CDR2, a VL CDR1, a VL CDR2, and a VL CDR3; a VH CDR1, a VH CDR3, a VL CDR1, a VL CDR2, and a VL CDR3; a VH CDR2, a VH CDR3, a VL CDR1, a VL CDR2, and a VL CDR3; or any combination thereof of the VH CDRs and VL CDRs listed in  FIG. 3 . 
     The present invention provides antibodies that specifically bind to EphA2, said antibodies comprising derivatives of the VH domains, VH CDRs, VL domains, or VL CDRs described herein that specifically bind to EphA2. Standard techniques known to those of skill in the art can be used to introduce mutations (e.g., deletions, additions, and/or substitutions) in the nucleotide sequence encoding an antibody of the invention, including, for example, site-directed mutagenesis and PCR-mediated mutagenesis which results in amino acid substitutions. Preferably, the derivatives include less than 25 amino acid substitutions, less than 20 amino acid substitutions, less than 15 amino acid substitutions, less than 10 amino acid substitutions, less than 5 amino acid substitutions, less than 4 amino acid substitutions, less than 3 amino acid substitutions, or less than 2 amino acid substitutions relative to the original molecule. In a further embodiment, the derivatives have conservative amino acid substitutions are made at one or more predicted non-essential amino acid residues (i.e., amino acid residues which are not critical for the antibody to specifically bind to EphA2). A “conservative amino acid substitution” is one in which the amino acid residue is replaced with an amino acid residue having a side chain with a similar charge. Families of amino acid residues having side chains with similar charges have been defined in the art. These families include amino acids with basic side chains (e.g., lysine, arginine, histidine), acidic side chains (e.g., aspartic acid, glutamic acid), uncharged polar side chains (e.g., glycine, asparagine, glutamine, serine, threonine, tyrosine, cysteine), nonpolar side chains (e.g., alanine, valine, leucine; isoleucine, proline, phenylalanine, methionine, tryptophan), beta-branched side chains (e.g., threonine, valine, isoleucine) and aromatic side chains (e.g., tyrosine, phenylalanine, tryptophan, histidine). Alternatively, mutations can be introduced randomly along all or part of the coding sequence, such as by saturation mutagenesis, and the resultant mutants can be screened for biological activity to identify mutants that retain activity. Following mutagenesis, the encoded antibody can be expressed and the activity of the antibody can be determined. 
     The present invention provides for antibodies that specifically bind to EphA2, said antibodies comprising the amino acid sequence of 2A4 (Seq ID No:2), 2E7 (Seq ID No:18), or 12E2 (Seq ID No:26), with one or more amino acid residue substitutions in the variable light (VL) domain and/or variable heavy (VH) domain. The present invention also provides for antibodies that specifically bind to EphA2, said antibodies comprising the amino acid sequence of 2A4 (Seq ID No:2), 2E7 (Seq ID No:18), or 12E2 (Seq ID No:26), with one or more amino acid residue substitutions in one or more VL CDRs and/or one or more VH CDRs. The present invention also provides for antibodies that specifically bind to EphA2, said antibodies comprising the amino acid sequence of 2A4 (Seq ID No:2), 2E7 (Seq ID No:18), or 12E2 (Seq ID No:26), or a VH and/or VL domain thereof with one or more amino acid residue substitutions in one or more VH frameworks and/or one or more VL frameworks. The antibody generated by introducing substitutions in the VH domain, VH CDRs, VL domain, VL CDRs and/or frameworks of 2A4, 2E7, or 12E2 can be tested in vitro and/or in vivo, for example, for its ability to bind to EphA2, or for its ability to inhibit or reduce EphA2 mediated cell proliferation, or for its ability to agonize or antagonize EphA2, or for its ability to prevent, treat and/or ameliorate cancer, or a symptom thereof. 
     In a specific embodiment, an antibody that specifically binds to EphA2 comprises a nucleotide sequence that hybridizes to the nucleotide sequence encoding 2A4 (Seq ID No:1), 2E7 (Seq ID No:17), or 12E2 (Seq ID No:25), or an antigen-binding fragment thereof under stringent conditions, e.g., hybridization to filter-bound DNA in 6× sodium chloride/sodium citrate (SSC) at about 45° C. followed by one or more washes in 0.2×SSC/0.1% SDS at about 50-65° C., under highly stringent conditions, e.g., hybridization to filter-bound nucleic acid in 6×SSC at about 45° C. followed by one or more washes in 0.1×SSC/0.2% SDS at about 68° C., or under other stringent hybridization conditions which are known to those of skill in the art (see, for example, Ausubel, F. M. et al., eds., 1989, Current Protocols in Molecular Biology, Vol. 1, Green Publishing Associates, Inc. and John Wiley &amp; Sons, Inc., New York at pages 6.3.1-6.3.6 and 2.10.3). 
     In another embodiment, an antibody that specifically binds to EphA2 comprises an amino acid sequence of a VH domain or an amino acid sequence a VL domain encoded by a nucleotide sequence that hybridizes to the nucleotide sequence encoding the VH or VL domains of 2A4 (Seq ID Nos: 37 and 39), 2E7 (Seq ID Nos: 41 and 43), or 12E2 (Seq ID Nos: 45 and 47) under stringent conditions described herein or under other stringent hybridization conditions which are known to those of skill in the art. In another embodiment, an antibody that specifically binds to EphA2 comprises an amino acid sequence of a VH domain and an amino acid sequence of a VL domain encoded by a nucleotide sequence that hybridizes to the nucleotide sequence encoding the VH and VL domains of 2A4 (Seq ID Nos: 37 and 39), 2E7 (Seq ID Nos: 41 and 43), or 12E2 (Seq ID Nos: 45 and 47) under stringent conditions described herein or under other stringent hybridization conditions which are known to those of skill in the art. In another embodiment, an antibody that specifically binds to EphA2 comprises an amino acid sequence of a VH CDR or an amino acid sequence of a VL CDR encoded by a nucleotide sequence that hybridizes to the nucleotide sequence encoding any one of the VH CDRs or VL CDRs (Seq ID Nos: 49-72) listed in  FIG. 3  under stringent conditions described herein or under other stringent hybridization conditions which are known to those of skill in the art. In another embodiment, an antibody that specifically binds to EphA2 comprises an amino acid sequence of a VH CDR (Seq ID Nos: 3-5, 11-13, 19-21, and 27-29), and an amino acid sequence of a VL CDR (Seq ID Nos: 6-8, 14-16, 22-24, and 30-32) encoded by nucleotide sequences that hybridize to the nucleotide sequences encoding any one of the VH CDRs (Seq ID Nos: 49-51, 55-57, 61-63, and 67-69) listed in  FIG. 3  and any one of the VL CDRs (Seq ID Nos: 52-54, 58-60, 64-66, and 70-72) listed in  FIG. 3 , under stringent conditions described herein or under other stringent hybridization conditions which are known to those of skill in the art. 
     In another embodiment, the present invention provides an antibody that specifically binds to EphA2, said antibody comprising a VH domain and/or VL domain encoded by a nucleotide sequence that hybridizes to the nucleotide sequence of the VH domain and/or VL domain of 2A4 (Seq ID Nos: 37 and 39) under stringent conditions. In another embodiment, the present invention provides an antibody that specifically binds to EphA2, said antibody comprising a VH CDR and/or VL CDR encoded by a nucleotide sequence that hybridizes to the nucleotide sequence of the VH CDR (Seq ID Nos: 55-57) and/or VL CDR (Seq ID Nos: 58-60) of 2A4 under stringent conditions. 
     In another embodiment, the present invention provides an antibody that specifically binds to EphA2, said antibody comprising a VH domain and/or VL domain encoded by a nucleotide sequence that hybridizes to the nucleotide sequence of the VH domain and/or VL domain of 2E7 Seq ID Nos: 41 and 43) under stringent conditions. In another embodiment, the present invention provides an antibody that specifically binds to EphA2, said antibody comprising a VH CDR and/or VL CDR encoded by a nucleotide sequence that hybridizes to the nucleotide sequence of the VH CDR (Seq ID Nos: 61-63) and/or VL CDR (Seq ID Nos: 64-66) of 2E7 under stringent conditions. 
     In another embodiment, the present invention provides an antibody that specifically binds to EphA2, said antibody comprising a VH domain and/or VL domain encoded by a nucleotide sequence that hybridizes to the nucleotide sequence of the VH domain and/or VL domain of 12E2 (Seq ID Nos: 45 and 47) under stringent conditions. In another embodiment, the present invention provides an antibody that specifically binds to EphA2, said antibody comprising a VH CDR and/or VL CDR encoded by a nucleotide sequence that hybridizes to the nucleotide sequence of the VH CDR (Seq ID Nos: 67-69) and/or VL CDR (Seq ID Nos: 70-72) of 12E2 under stringent conditions. 
     In a specific embodiment, an antibody that specifically binds to EphA2 comprises an amino acid sequence that is at least 35%, preferably at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99% identical to the amino acid sequence of 2A4 (Seq ID No:2), 2E7 (Seq ID No:18), or 12E2 (Seq ID No:26), or an antigen-binding fragment thereof. In another embodiment, an antibody that specifically binds to EphA2 comprises an amino acid sequence of a VH domain that is at least 35%, preferably at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99% identical to the VH domain of 2A4 (Seq ID No: 38), 2E7 (Seq ID No: 42), or 12E2 (Seq ID No: 46). In another embodiment, an antibody that specifically binds to EphA2 comprises an amino acid sequence of a VL domain that is at least 35%, preferably at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99% identical to the VL domain of 2A4 (Seq ID No: 40), 2E7 (Seq ID No: 44), or 12E2 (Seq ID No: 48). 
     In another embodiment, an antibody that specifically binds to EphA2 comprises an amino acid sequence of one or more VL CDRs that are at least 35%, preferably at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99% identical to any of the VL CDRs (Seq ID Nos: 6-8, 14-16, 22-24, and 30-32) listed in  FIG. 3 . In another embodiment, an antibody that specifically binds to EphA2 comprises an amino acid sequence of one or more VL CDRs that are at least 35%, preferably at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99% identical to any of one of the VL CDRs (Seq ID Nos: 6-8, 14-16, 22-24, and 30-32) listed in  FIG. 3 . 
     In another embodiment, the invention provides an antibody that specifically binds to EphA2, said antibody encoded by a nucleotide sequence that is at least 65%, preferably at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99% identical to the nucleotide sequence encoding 2A4 (Seq ID No.1). In another embodiment, the invention provides an antibody that specifically binds to EphA2, said antibody comprising a VH domain and/or VL domain encoded by a nucleotide sequence that is at least 65%, preferably at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99% identical to the nucleotide sequence of the VH domain and/or VL domain of 2A4 (Seq ID Nos: 37 and 39). In another embodiment, the invention provides an antibody that specifically binds to EphA2, said antibody comprising a VH CDR and/or a VL CDR encoded by a nucleotide sequence that is at last 65%, preferably at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99% identical to the nucleotide sequence of the VH CDR (Seq ID Nos: 56-58) and/or VL CDR (Seq ID Nos: 58-60) of 2A4. 
     In another embodiment, the invention provides an antibody that specifically binds to EphA2, said antibody encoded by a nucleotide sequence that is at least 65%, preferably at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99% identical to the nucleotide sequence encoding 2E7 (Seq ID No: 17). In another embodiment, the invention provides an antibody that specifically binds to EphA2, said antibody comprising a VH domain and/or VL domain encoded by a nucleotide sequence that is at least 65%, preferably at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99% identical to the nucleotide sequence of the VH domain and/or VL domain of 2E7 (Seq ID Nos: 41 and 43). In another embodiment, the invention provides an antibody that specifically binds to EphA2, said antibody comprising a VH CDR and/or a VL CDR encoded by a nucleotide sequence that is at last 65%, preferably at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99% identical to the nucleotide sequence of the VH CDR (Seq ID Nos: 61-63) and/or VL CDR (Seq ID Nos: 64-66) of 2E7. 
     In another embodiment, the invention provides an antibody that specifically binds to EphA2, said antibody encoded by a nucleotide sequence that is at least 65%, preferably at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99% identical to the nucleotide sequence encoding 12E2 (Seq ID No: 25). In another embodiment, the invention provides an antibody that specifically binds to EphA2, said antibody comprising a VH domain and/or VL domain encoded by a nucleotide sequence that is at least 65%, preferably at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99% identical to the nucleotide sequence of the VH domain and/or VL domain of 12E2 (Seq ID Nos: 45 and 47). In another embodiment, the invention provides an antibody that specifically binds to EphA2, said antibody comprising a VH CDR and/or a VL CDR encoded by a nucleotide sequence that is at last 65%, preferably at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99% identical to the nucleotide sequence of the VH CDR (Seq ID Nos: 67-69) and/or VL CDR (Seq ID Nos: 70-72) of 12E2. 
     The present invention encompasses antibodies that compete with an antibody described herein for binding to EphA2. In particular, the present invention encompasses antibodies that compete with 2A4, 2E7, or 12E2 or an antigen-binding fragment thereof for binding to EphA2. In a specific embodiment, the invention encompasses an antibody that reduces the binding of 2A4, 2E7, or 12E2 to EphA2 by at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95% or more, 25% to 50%, 45 to 75%, or 75 to 99% relative to a control such as PBS in the competition assay described herein or competition assays well known in the art. In another embodiment, the invention encompasses an antibody that reduces binding of 2A4, 2E7, or 12E2 to EphA2 by at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95% or more, or 25% to 50%, 45 to 75%, or 75 to 99% relative to a control such as PBS in an ELISA competition assay. 
     In one embodiment, the invention encompasses an antibody that reduces the binding of 2A4 to EphA2 by at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95% or more, or 25% to 50%, 45 to 75%, or 75 to 99% relative to a control such as PBS in an ELISA competition assay. In another embodiment, the invention encompasses an antibody that reduces the binding of 2E7 to EphA2 by at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95% or more, or 25% to 50%, 45 to 75%, or 75 to 99% relative to a control such as PBS in an ELISA competition assay. In another embodiment, the invention encompasses an antibody that reduces the binding of 12E2 to EphA2 by at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95% or more, or 25% to 50%, 45 to 75%, or 75 to 99% relative to a control such as PBS in an ELISA competition assay. 
     In another embodiment, the invention encompasses an antibody that reduces the binding of an antibody comprising (alternatively, consisting of) an antigen-binding fragment (e.g., a VH domain, a VH CDR, a VL domain or a VL CDR) of 2A4, 2E7, or 12E2 to EphA2 by at least 25%, preferably at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95% or more, or 25% to 50%, 45 to 75%, or 75 to 99% relative to a control such as PBS in a competition assay described herein or well-known to one of skill in the art. In another embodiment, the invention encompasses an antibody that reduces the binding of an antibody comprising (alternatively, consisting of) an antigen-binding fragment (e.g., a VH domain, VL domain, a VH CDR, or a VL CDR) of 2A4, 2E7, or 12E2 to EphA2 by at least 25%, preferably at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95% or more, or 25% to 50%, 45 to 75%, or 75 to 99% relative to a control such as PBS in an ELISA competition assay. 
     In one embodiment, the invention encompasses an antibody that reduces the binding of an antibody comprising (alternatively, consisting of) an antigen-binding fragment of 2A4 to EphA2 by at least 25%, preferably at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95% or more, or 25% to 50%, 45 to 75%, or 75 to 99% relative to a control such as PBS in an ELISA competition assay. In one embodiment, the invention encompasses an antibody that reduces the binding of an antibody comprising (alternatively, consisting of) an antigen-binding fragment of 2E7 to EphA2 by at least 25%, preferably at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95% or more, or 25% to 50%, 45 to 75%, or 75 to 99% relative to a control such as PBS in an ELISA competition assay. In one embodiment, the invention encompasses an antibody that reduces the binding of an antibody comprising (alternatively, consisting of) an antigen-binding fragment of 12E2 to EphA2 by at least 25%, preferably at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95% or more, or 25% to 50%, 45 to 75%, or 75 to 99% relative to a control such as PBS in an ELISA competition assay. 
     The present invention encompasses polypeptides or proteins comprising (alternatively, consisting of) VH domains that compete with the VH domain of 2A4, 2E7, or 12E2 for binding to EphA2. The present invention also encompasses polypeptides or proteins comprising (alternatively, consisting of) VL domains that compete with a VL domain of 2A4, 2E7, or 12E2 for binding to EphA2. 
     The present invention encompasses polypeptides or proteins comprising (alternatively, consisting of) VH CDRs that compete with a VH CDR (Seq ID Nos: 3-5, 11-13, 19-21 and 27-29) listed in  FIG. 3 , for binding to EphA2. The present invention also encompasses polypeptides or proteins comprising (alternatively, consisting of) VL CDRs that compete with a VL CDR (Seq ID Nos: 6-8, 14-16, 22-24, and 30-32) listed in  FIG. 3  for binding to EphA2. 
     The antibodies that specifically bind to EphA2 include derivatives that are modified, i.e., by the covalent attachment of any type of molecule to the antibody such that covalent attachment. For example, but not by way of limitation, the antibody derivatives include antibodies that have been modified, e.g., by glycosylation, acetylation, pegylation, phosphorylation, amindation, derivatization by known protecting/blocking groups, proteolytic cleavage, linkage to a cellular ligand or other protein, etc. Any of numerous chemical modifications may be carried out by known techniques, including, but not limited to, specific chemical cleavage, acetylation, formylation, metabolic synthesis of tunicamycin, etc. Additionally, the derivative may contain one or more non-classical amino acids. 
     The present invention also provides antibodies that specifically bind to EphA2, said antibodies comprising a framework region known to those of skill in the art (e.g., a human or non-human framework). The framework regions may be naturally occurring or consensus framework regions. Preferably, the fragment region of an antibody of the invention is human (see, e.g., Chothia et al., 1998, J. Mol. Biol. 278:457-479 for a listing of human framework regions, which is incorporated herein by reference in its entirety). 
     The present invention encompasses antibodies that specifically bind to EphA2, said antibodies comprising the amino acid sequence of 2A4, 2E7, or 12E2 with mutations (e.g., one or more amino acid substitutions) in the framework regions. In certain embodiments, antibodies that specifically bind to EphA2 comprise the amino acid sequence of 2A4, 2E7, or 12E2 with one or more amino acid residue substitutions in the framework regions of the VH and/or VL domains. Preferably, the amino acid substitutions in the framework region improve binding of the antibody to EphA2. 
     The present invention also encompasses antibodies that specifically bind to EphA2, said antibodies comprising the amino acid sequence of 2A4, 2E7, or 12E2 (Seq ID Nos: 2, 18, and 26) with mutations (e.g., one or more amino acid residue substitutions) in the variable and framework regions. Preferably, the amino acid substitutions in the variable and framework regions improve binding of the antibody to EphA2. 
     The present invention also provides antibodies of the invention that comprise constant regions known to those of skill in the art. Preferably, the constant regions of an antibody of the invention or fragment thereof are human. 
     The present invention provides for antibodies that have a high binding affinity for EphA2. In a specific embodiment, an antibody that specifically binds to EphA2 has an association rate constant or k on  rate (antibody (Ab)+antigen (Ag)  k on → Ab-Ag) of at least 10 5  M −1 s −1 , at least 1.5×10 5  M −1 s −1 , at least 2×10 5  M −1 s −1 , at least 2.5×10 5  M −1 s −1 , at least 5×10 5  M −1 s −1 , at least 10×6 M −1 s −1 , at least 5×10 6  M −1 s −1 , at least 10 7  M −1 s −1 , at least 5×10 7  M −1 s −1 , or at least 10 8  M −1 s −1 , or 10 5  M −1 s −1 , 1.5×10 5  M −1 s −1 -1×10 7 M −1 s −1 , 2×10 5 -1×10 6 M −1 s −1 , or 4.5×10 5 . In another embodiment, an antibody that specifically binds to EphA2 has a k on  of at least 2×10 5  M −1 s −1 , at least 2.5×10 5  M −1 s −1 , at least 5×10 5  M −1 s −1 , at least 10 6  M −1 s −1 , at least 5×10 6  M −1 s −1 , at least 10 7  M −1 s −1 , at least 5×10 7  M −1 s −1 , or at least 10 8  M −1 s −1  as determined by a BIAcore assay. In another embodiment, an antibody that specifically binds to EphA2 has a k on  of at most 10 8  M −1 s −1 , at most 10 9  M n−1 s −1 , at most 10 10  M −1 s −1 , at most 10 11  M −1 s −1 , or at most 10 12  M −1 s −1  as determined by a BIAcore assay. In accordance with these embodiments, such antibodies may comprise a VH domain and/or a VL domain of 2A4, 2E7, or 12E2. 
     In another embodiment, an antibody that specifically binds to EphA2 has a k off  rate (antibody (Ab)+antigen (Ag)  k off ⇄ Ab-Ag) of less than 10 −3  s −1 , less than 5×10 −3  s −1 , less than 10 4  s −1 , less than 2×10 4  s −1 , less than 5×10 −4  s −1 , less than 10 −5  s −1 , less than 5×10 −5  s −1 , less than 10 −6  s −1 , less than 5×10 −6  s −1 , less than 10 −7  s −1 , less than 5×10 −7  s −1 , less than 10 −8  s −1 , less than 5×10 −8  s −1 , less than 10 −9  s −1 , less than 5×10 −9  s −1 , or less than 10 −10  s −1 , or 10 −3 -10 −10  s −1 , 10 −4 -10 −8  s −1 , or 10 −5 -10 −8  s −1 . In one embodiment, an antibody that specifically binds to EphA2 has a k off  of 10 −5  s −1 , less than 5×10 −5  s −1 , less than 10 −6  s −1 , less than 5×10 −6  s −1 , less than 10 −7  s −1 , less than 5×10 −7  s −1 , less than 10 −8  s −1 , less than 5×10 −8  s −1 , less than 10 −9  s −1 , less than 5×10 −9  s −1  or less than 10 −11  s −1  as determined by a BIAcore assay. In another embodiment, an antibody that specifically binds to EphA2 has a k off  of greater than 10 −13  s −1 , greater than 10 −12 s −1 , greater than 10 −11  s −1 , greater than 10 −10  s −1 , greater than 10 −9  s −1 , or greater than 10 −8  s −1 . In accordance with these embodiments, such antibodies may comprise a VH domain and/or a VL domain of 2A4, 2E7, or 12E2. 
     In another embodiment, an antibody that specifically binds to EphA2 has an affinity constant or K a  (k on /k off ) of at least 10 2  M −1 , at least 5×10 2  M −1 , at least 10 3  M −1 , at least 5×10 3  M −1 , at least 10 4  M −1 , at least 5×10 4  M −1 , at least 10 5  M −1 , at least 5×10 5  M −1 , at least 10 6  M −1 , at least 5×10 6  M −1 , at least 10 7  M −1 , at least 5×10 7  M −1 , at least 10 8  M −1 , at least 5×10 8  M −1 , at least 10 9  M −1 , at least 5×10 9  M −1 , at least 10 10  M, at least 5×10 10  M −1 , at least 10 11  M −1 , at least 5×10 11  M −1 , at least 10 12  M −1 , at least 5×10 12  M −1 , at least 10 13  M −1 , at least 5×10 13  M −1 , at least 10 14  M −1 , at least 5×10 14  M −1 , at least 10 15  M −1 , or at least 5×10 15 M −1 , or 10 2 -5×10 5  M −1 , 10 4 -1×10 10  M −1 , or 10 5 -1×10 8  M −1 . In another embodiment, an antibody that immunospecifically binds to EphA2 has a K a  of at most 10 11  M −1 , at most 5×10 11  M −1 , at most 10 12  M −1 , at most 5×10 12  M −1 , at most 10 13  M −1 , at most 5×10 13  M −1 , at most 10 14  M −1 , or at most 5×10 14  M −1 . 
     In another embodiment, an antibody that specifically binds to EphA2 has a dissociation constant or K d  (k off /k on ) of less than 10 −5  M, less than 5×10 −5  M, less than 10 −6  M, less than 5×10 −6  M, less than 10 −7  M, less than 5×10 −7  M, less than 10 −8  M, less than 5×10 −8  M, less than 10 −9  M, less than 5×10 −9  M, less than 10 −10  M, less than 5×10 −10  M, less than 10 −11  M, less than 5×10 −11  M, less than 10 −12  M, less than 5×10 −12  M, less than 10 −13  M, less than 5×10 −13  M, less than 10 −14  M, less than 5×10 −14  M, less than 10 −15  M, or less than 5×10 −15  M or 10 −2  M-5×10 −5  M, 10 −6 -10 −15  M, or 10 −8 -10 −14  M. In another embodiment, an antibody that specifically binds to EphA2 has a K d  of less than 10 −9  M, less than 5×10 −9  M, less than 10 −10  M, less than 5×10 −10  M, less than 1×10 −11  M, less than 5×10 −11  M, less than 1×10 −12  M, less than 5×10 −12  M, less than 10 −13  M, less than 5×10 −13  M or less than 1×10 −14  M, or 10 −9  M-10 −14  M as determined by a BIAcore assay. In another embodiment, an antibody that specifically binds to EphA2 has a K d  of greater than 10 −9  M, greater than 5×10 −9  M, greater than 10 −10  M, greater than 5×10 −10  M, greater than 10 −11  M, greater than 5×10 −11  M, greater than 10 −12  M, greater than 5×10 −12  M, greater than 6×10 −12  M, greater than 10 −13  M, greater than 5×10 −13  M, greater than 10 −14  M, greater than 5×10 14 M or greater than 10 −9  M-10 −14  M. In accordance with these embodiments, such antibodies may comprise a VH domain and/or a VL domain of 2A4, 2E7, or 12E2. 
     The present invention provides peptides, polypeptides and/or proteins comprising one or more variable or hypervariable regions of the antibodies described herein. Preferably, peptides, polypeptides or proteins comprising one or more variable or hypervariable regions of antibodies of the invention further comprise a heterologous amino acid sequence. In certain embodiments, such a heterologous amino acid sequence comprises at least 5 contiguous amino acid residues, at least 10 contiguous amino acid residues, at least 15 contiguous amino acid residues, at least 20 contiguous amino acid residues, at least 25 contiguous amino acid residues, at least 30 contiguous amino acid residues, at least 40 contiguous amino acid residues, at least 50 contiguous amino acid residues, at least 75 contiguous amino acid residues, at least 100 contiguous amino acid residues or more contiguous amino acid residues. Such peptides, polypeptides and/or proteins may be referred to as fusion proteins. 
     In a specific embodiment, peptides, polypeptides or proteins comprising one or more variable or hypervariable regions of the antibodies of the invention are 10 amino acid residues, 15 amino acid residues, 20 amino acid residues, 25 amino acid residues, 30 amino acid residues, 35 amino acid residues, 40 amino acid residues, 45 amino acid residues, 50 amino acid residues, 75 amino acid residues, 100 amino acid residues, 125 amino acid residues, 150 amino acid residues or more amino acid residues in length. In certain embodiments, peptides, polypeptides, or proteins comprising one or more variable or hypervariable regions of an antibody of the invention specifically bind to EphA2. In other embodiments, peptides, polypeptides, or proteins comprising one or more variable or hypervariable regions of an antibody of the invention do not specifically bind to EphA2. 
     In a specific embodiment, the present invention provides peptides, to polypeptides and/or proteins comprising a VH domain and/or VL domain of one of the antibodies described herein (see  FIGS. 3 and 4 ). In another embodiment, the present invention provides peptides, polypeptides and/or proteins comprising one or more CDRs having the amino acid sequence of any of the CDRs listed in  FIG. 3 . In accordance with these embodiments, the peptides, polypeptides or proteins may further comprise a heterologous amino acid sequence. 
     Peptides, polypeptides or proteins comprising one or more variable or hypervariable regions have utility, e.g., in the production of anti-idiotypic antibodies which in turn may be used to prevent, treat, and/or ameliorate one or more symptoms associated with a disease or disorder (e.g., cancer). The anti-idiotypic antibodies produced can also be utilized in immunoassays, such as, e.g., ELISAs, for the detection of antibodies which comprise a variable or hypervariable region contained in the peptide, polypeptide or protein used in the production of the anti-idiotypic antibodies. 
     Antibodies used in the methods of the invention include, but are not limited to, monoclonal antibodies, synthetic antibodies, multispecific antibodies (including bi-specific antibodies), human antibodies, humanized antibodies, chimeric antibodies, single-chain Fvs (scFv) (including bi-specific scFvs), single chain antibodies, Fab fragments, F(ab′) fragments, disulfide-linked Fvs (sdFv), and epitope-binding fragments of any of the above. In particular, antibodies used in the methods of the present invention include immunoglobulin molecules and immunologically active portions of immunoglobulin molecules, i.e., molecules that contain an antigen binding site that specifically binds to EphA2 and is an agonist of EphA2 and/or preferentially binds an EphA2 epitope exposed on cancer cells but not non-cancer cells. The immunoglobulin molecules of the invention can be of any type (e.g., IgG, IgE, IgM, IgD, IgA and IgY), class (e.g., IgG 1 , IgG 2 , IgG 3 , IgG 4 , IgA, and IgA 2 ) or subclass of immunoglobulin molecule. 
     In a specific embodiment, antibodies for use in the methods of the invention are bispecific T cell engagers (BiTEs). Bispecific T cell engagers (BiTE) are bispecific antibodies that can redirect T cells for antigen-specific elimination of targets. A BiTE molecule has an antigen-binding domain that binds to a T cell antigen (e.g. CD3) at one end of the molecule and an antigen-binding domain that will bind to an antigen on the target cell. A BiTE molecule was recently described in WO 99/54440, which is herein incorporated by reference in its entirety. This publication describes a novel single-chain multifunctional polypeptide that comprises binding sites for the CD19 and CD3 antigens (CD19×CD3). This molecule was derived from two antibodies, one that binds to CD19 on the B cell and an antibody that binds to CD3 on the T cells. The variable regions of these different antibodies are linked by a polypeptide sequence, thus creating a single molecule. Also described, is the linking of the heavy chain (VH) and light chain (VL) variable domains with a flexible linker to create a single chain, bispecific antibody. BiTE molecules that target EphA2 are described in U.S. Patent Application No. 60/753,368, filed Dec. 21, 2005, entitled EphA2 BiTE Molecules And Uses Thereof, attorney docket number 10271-175-888, which is herein incorporated by reference in its entirety. 
     In an embodiment of this invention, an antibody or ligand that specifically binds a polypeptide of interest (e.g., an Eph receptor and/or an Ephrin) will comprise a portion of the BiTE molecule. For example, the VH and/or VL (e.g. a scFV) of an antibody that binds a polypeptide of interest (e.g., an Eph receptor and/or an Ephrin) can be fused to an anti-CD3 binding portion such as that of the molecule described above, thus creating a BiTE molecule that targets the polypeptide of interest (e.g., an Eph receptor and/or an Ephrin). In addition to the heavy and/or light chain variable domains of antibody against a polypeptide of interest (e.g., an Eph receptor and/or an Ephrin), other molecules that bind the polypeptide of interest (e.g., an Eph receptor and/or an Ephrin) can comprise the BiTE molecule, for example receptors (e.g., an Eph receptor and/or an Ephrin). In another embodiment, the BiTE molecule can comprise a molecule that binds to other T cell antigens (other than CD3). For example, ligands and/or antibodies that specifically bind to T-cell antigens like CD2, CD4, CD8, CD11a, TCR, and CD28 are contemplated to be part of this invention. This list is not meant to be exhaustive but only to illustrate that other molecules that can specifically bind to a T cell antigen can be used as part of a BiTE molecule. These molecules can include the VH and/or VL portions of the antibody or natural ligands (for example LFA3 whose natural ligand is CD3). 
     The antibodies used in the methods of the invention may be from any animal origin including birds and mammals (e.g., human, murine, donkey, sheep, rabbit, goat, guinea pig, camel, horse, or chicken). Preferably, the antibodies are human or humanized monoclonal antibodies. As used herein, “human” antibodies include antibodies having the amino acid sequence of a human immunoglobulin and include antibodies isolated from human immunoglobulin libraries or from mice or other animal that express antibodies from human genes. 
     The antibodies used in the methods of the present invention may be monospecific, bispecific, trispecific or of greater multispecificity. Multispecific antibodies may specifically bind to different epitopes of an EphA2 polypeptide or may specifically bind to both an EphA2 polypeptide as well a heterologous epitope, such as a heterologous polypeptide or solid support material. See, e.g., International Publication Nos. WO 93/17715, WO 92/08802, WO 91/00360, and WO 92/05793; Tutt, et al., 1991 , J. Immunol.  147:60-69; U.S. Pat. Nos. 4,474,893, 4,714,681, 4,925,648, 5,573,920, and 5,601,819; and Kostelny et al., 1992 , J. Immunol.  148:1547-1553. 
     In a specific embodiment, an antibody used in the methods of the present invention is 2A4, 2E7 or 12E2, or an antigen-binding fragment thereof (e.g., one or more complementarity determining regions (CDRs) of the afore-mentioned antibodies of the invention, e.g., see Table 1). In another embodiment, an agonistic antibody used in the methods of the present invention binds to the same epitope as any of 2A4, 2E7 or 12E2, or competes with any of 2A4, 2E7 or 12E2 for binding to EphA2, e.g., in an ELISA assay. 
     The present invention also provides antibodies of the invention or fragments thereof that comprise a framework region known to those of skill in the art. In a specific embodiment, an antibody of the invention or a fragment thereof comprises a human framework region. Preferably, the antibody of the invention or fragment thereof is human or humanized. In a specific embodiment, the antibody of the invention or fragment thereof comprises one or more CDRs from any of 2A4, 2E7 or 12E2 (or any other EphA2 agonistic antibody or EphA2 antibody that preferentially binds an EphA2 epitope exposed on cancer cells but not non-cancer cells), binds EphA2, and, preferably, agonizes EphA2 and/or preferentially binds an EphA2 epitope exposed on cancer cells but not non-cancer cells. 
     The present invention encompasses single domain antibodies, including camelized single domain antibodies (see e.g., Muyldermans et al., 2001 , Trends Biochem. Sci.  26:230; Nuttall et al., 2000 , Cur. Pharm. Biotech.  1:253; Reichmann and Muyldermans, 1999 , J. Immunol. Meth.  234 :25; International Publication Nos. WO 94/04678 and WO 94/25591; U.S. Pat. No. 6,005,079; which are incorporated herein by reference in their entireties). In one embodiment, the present invention provides single domain antibodies comprising two VH domains having the amino acid sequence of any of the VH domains of 2A4, 2E7 or 12E2 (Seq ID Nos: 38, 42, and 46) (or any other EphA2 agonistic antibody or EphA2 antibody that preferentially binds an EphA2 epitope exposed on cancer cells but not non-cancer cells) with modifications such that single domain antibodies are formed. In another embodiment, the present invention also provides single domain antibodies comprising two VH domains comprising one or more of the VH CDRs of 2A4, 2E7 or 12E2 (Seq ID Nos: 3-5, 19-21, and 27-29) (or any other EphA2 agonistic antibody or EphA2 antibody that preferentially binds an EphA2 epitope exposed on cancer cells but not non-cancer cells). 
     The methods of the present invention also encompass the use of antibodies or fragments thereof that have half-lives (e.g., serum half-lives) in a mammal, preferably a human, of greater than 15 days, preferably greater than 20 days, greater than 25 days, greater than 30 days, greater than 35 days, greater than 40 days, greater than 45 days, greater than 2 months, greater than 3 months, greater than 4 months, or greater than 5 months. The increased half-lives of the antibodies of the present invention or fragments thereof in a mammal, preferably a human, result in a higher serum titer of said antibodies or antibody fragments in the mammal, and thus, reduce the frequency of the administration of said antibodies or antibody fragments and/or reduces the concentration of said antibodies or antibody fragments to be administered. Antibodies or fragments thereof having increased in vivo half-lives can be generated by techniques known to those of skill in the art. For example, antibodies or fragments thereof with increased in vivo half-lives can be generated by modifying (e.g., substituting, deleting or adding) amino acid residues identified as involved in the interaction between the Fc domain and the FcRn receptor (see, e.g., International Publication Nos. WO 97/34631 and WO 02/060919, and U.S. Patent Application Publication 2003/0190311, each of which is incorporated herein by reference in its entirety). Antibodies or fragments thereof with increased in vivo half-lives can be generated by attaching to said antibodies or antibody fragments polymer molecules such as high molecular weight polyethyleneglycol (PEG). PEG can be attached to said antibodies or antibody fragments with or without a multifunctional linker either through site-specific conjugation of the PEG to the N- or C-terminus of said antibodies or antibody fragments or via epsilon-amino groups present on lysine residues. Linear or branched polymer derivatization that results in minimal loss of biological activity will be used. The degree of conjugation will be closely monitored by SDS-PAGE and mass spectrometry to ensure proper conjugation of PEG molecules to the antibodies. Unreacted PEG can be separated from antibody-PEG conjugates by, e.g., size exclusion or ion-exchange chromatography. 
     The present invention also encompasses antibodies that are Fc variants with enhanced antibody dependent cell-mediated cytotoxicity activity. Nonlimiting examples of such Fc variant antibodies are disclosed in U.S. patent application Ser. Nos. 11/203,253 (filed Aug. 15, 2005) and 11/203,251 (filed Aug. 15, 2005), and U.S. Provisional Patent Applications 60/674,674 (filed Apr. 26, 2005) and 60/713,711 (filed Sep. 6, 2005), each of which is incorporated by reference herein in its entirety. 
     The present invention also encompasses the use of antibodies or antibody fragments comprising the amino acid sequence of one or both variable domains of 2A4, 2E7 or 12E2 (Seq ID Nos: 38, 40, 42, 44, 46, and 48) with mutations (e.g., one or more amino acid substitutions) in the framework or variable regions. Preferably, mutations in these antibodies maintain or enhance the avidity and/or affinity of the antibodies for the particular antigen(s) to which they specifically bind. Standard techniques known to those skilled in the art (e.g., immunoassays) can be used to assay the affinity of an antibody for a particular antigen. 
     Standard techniques known to those skilled in the art can be used to introduce mutations in the nucleotide sequence encoding an antibody, or fragment thereof, including, e.g., site-directed mutagenesis and PCR-mediated mutagenesis, which results in amino acid substitutions. Preferably, the derivatives include less than 15 amino acid substitutions, less than 10 amino acid substitutions, less than 5 amino acid substitutions, less than 4 amino acid substitutions, less than 3 amino acid substitutions, or less than 2 amino acid substitutions relative to the original antibody or fragment thereof. In a further embodiment, the derivatives have conservative amino acid substitutions made at one or more predicted non-essential amino acid residues. 
     5.1.1 Antibody Conjugates 
     The antibodies used in the methods of the invention include derivatives that are modified, e.g., by the covalent attachment of any type of molecule to the antibody. For example, but not by way of limitation, the antibody derivatives include antibodies that have been modified, e.g., by glycosylation, acetylation, pegylation, phosphorylation, amidation, derivatization by known protecting/blocking groups, proteolytic cleavage, linkage to a cellular ligand or other protein, etc. Any of numerous chemical modifications may be carried out by known techniques, including, but not limited to, specific chemical cleavage, acetylation, formylation, metabolic synthesis of tunicamycin, etc. Additionally, the derivative may contain one or more non-classical amino acids. 
     The present invention encompasses the use of antibodies or fragments thereof recombinantly fused or chemically conjugated (including both covalent and non-covalent conjugations) to a heterologous polypeptide (or portion thereof, preferably to a polypeptide of at least 10, at least 20, at least 30, at least 40, at least 50, at least 60, at least 70, at least 80, at least 90 or at least 100 amino acids) to generate fusion proteins. The fusion does not necessarily need to be direct, but may occur through linker sequences. For example, antibodies may be used to target heterologous polypeptides to particular cell types, either in vitro or in vivo, by fusing or conjugating the antibodies to antibodies specific for particular cell surface receptors. Antibodies fused or conjugated to heterologous polypeptides may also be used in in vitro immunoassays and purification methods using methods known in the art. See e.g., International Publication WO 93/21232; EP 439,095; Naramura et al., 1994 , Immunol. Lett.  39:91-99; U.S. Pat. No. 5,474,981; Gillies et al., 1992 , PNAS  89:1428-1432; and Fell et al., 1991 , J. Immunol.  146:2446-2452, which are incorporated by reference in their entireties. In some embodiments, the disorder to be detected, treated, managed, or monitored is malignant cancer that overexpresses EphA2. In other embodiments, the disorder to be detected, treated, managed, or monitored is a pre-cancerous condition associated with cells that overexpress EphA2. In a specific embodiments, the pre-cancerous condition is high-grade prostatic intraepithelial neoplasia (PIN), fibroadenoma of the breast, fibrocystic disease, or compound nevi. 
     The present invention further includes compositions comprising heterologous polypeptides fused or conjugated to antibody fragments. For example, the heterologous polypeptides may be fused or conjugated to a Fab fragment, Fd fragment, Fv fragment, F(ab) 2  fragment, or portion thereof. Methods for fusing or conjugating polypeptides to antibody portions are known in the art. See, e.g., U.S. Pat. Nos. 5,336,603, 5,622,929, 5,359,046, 5,349,053, 5,447,851, and 5,112,946; EP 307,434; EP 367,166; International Publication Nos. WO 96/04388 and WO 91/06570; Ashkenazi et al., 1991 , PNAS  88: 10535-10539; Zheng et al., 1995 , J. Immunol.  154:5590-5600; and Vil et al., 1992 , PNAS  89:11337-11341 (said references incorporated by reference in their entireties). 
     Additional fusion proteins, e.g., of any of 2A4, 2E7, or 12E2 antibodies (or any other EphA2 agonistic antibody or EphA2 antibody that preferentially binds an EphA2 epitope exposed on cancer cells but not non-cancer cells), may be generated through the techniques of gene-shuffling, motif-shuffling, exon-shuffling, and/or codon-shuffling. (collectively referred to as “DNA shuffling”). DNA shuffling may be employed to alter the activities of antibodies of the invention or fragments thereof (e.g., antibodies or fragments thereof with higher affinities and lower dissociation rates). See, generally, U.S. Pat. Nos. 5,605,793; 5,811,238; 5,830,721; 5,834,252; and 5,837,458, and Patten et al., 1997 , Curr. Opinion Biotechnol.  8:724-33; Harayama, 1998 , Trends Biotechnol.  16:76; Hansson, et al., 1999 , J. Mol. Biol.  287:265; and Lorenzo and Blasco, 1998 , BioTechniques  24:308 (each of these patents and publications are hereby incorporated by reference in its entirety). Antibodies or fragments thereof, or the encoded antibodies or fragments thereof, may be altered by being subjected to random mutagenesis by error-prone PCR, random nucleotide insertion or other methods prior to recombination. One or more portions of a polynucleotide encoding an antibody or antibody fragment, which portions specifically bind to EphA2 may be recombined with one or more components, motifs, sections, parts, domains, fragments, etc. of one or more heterologous molecules. 
     Moreover, the antibodies or fragments thereof can be fused to marker sequences, such as a peptide to facilitate purification. In further embodiments, the marker amino acid sequence is a hexa-histidine peptide, such as the tag provided in a pQE vector (QIAGEN, Inc., 9259 Eton Avenue, Chatsworth, Calif., 91311), among others, many of which are commercially available. As described in Gentz et al., 1989 , PNAS  86:821, for instance, hexa-histidine provides for convenient purification of the fusion protein. Other peptide tags useful for purification include, but are not limited to, the hemagglutinin “HA” tag, which corresponds to an epitope derived from the influenza hemagglutinin protein (Wilson et al., 1984 , Cell  37:767) and the “flag” tag. 
     In other embodiments, antibodies of the present invention or fragments or variants thereof are conjugated to a diagnostic or detectable agent. Such antibodies can be useful for monitoring or prognosing the development or progression of a cancer as part of a clinical testing procedure, such as determining the efficacy of a particular therapy. Additionally, such antibodies can be useful for monitoring or prognosing the development or progression of a pre-cancerous condition associated with cells that overexpress EphA2 (e.g., high-grade prostatic intraepithelial neoplasia (PIN), fibroadenoma of the breast, fibrocystic disease, or compound nevi). In one embodiment, an exposed EphA2 epitope antibody is conjugated to a diagnostic or detectable agent. 
     Such diagnosis and detection can accomplished by coupling the antibody to detectable substances including, but not limited to various enzymes, such as but not limited to horseradish peroxidase, alkaline phosphatase, beta-galactosidase, or acetylcholinesterase; prosthetic groups, such as but not limited to streptavidin/biotin and avidin/biotin; fluorescent materials, such as but not limited to, umbelliferone, fluorescein, fluorescein isothiocynate, rhodamine, dichlorotriazinylamine fluorescein, dansyl chloride or phycoerythrin; luminescent materials, such as but not limited to, luminol; bioluminescent materials, such as but not limited to, luciferase, luciferin, and aequorin; radioactive materials, such as but not limited to, bismuth ( 213 Bi), carbon ( 14 C), chromium ( 51 Cr), cobalt ( 57 Co), fluorine ( 18 F), gadolinium ( 153 Gd,  159 Gd), gallium ( 68 Ga,  67 Ga), germanium ( 68 Ge), holmium ( 166 Ho), indium ( 115 In,  113 In,  112 In,  111 In), iodine ( 131 I,  125 I,  123 I,  121 I), lanthanium ( 140 La), lutetium ( 177 Lu), manganese ( 54 Mn), molybdenum ( 99 Mo), palladium ( 103 Pd), phosphorous ( 32 P), praseodymium ( 142 Pr), promethium ( 149 Pm), rhenium ( 186 Re,  188 Re), rhodium ( 105 Rh), ruthemium ( 97 Ru), samarium ( 153 Sm), scandium ( 47 Sc), selenium ( 75 Se), strontium ( 85 Sr), sulfur ( 35 S), technetium ( 99 Tc), thallium ( 201 Ti), tin ( 113 Sn,  117 Sn), tritium ( 3 H), xenon ( 133 Xe), ytterbium ( 169 I,  175 Yb), yttrium ( 90 Y), zinc ( 65 Zn); positron emitting metals using various positron emission tomographies, and nonradioactive paramagnetic metal ions. 
     The present invention further encompasses uses of antibodies or fragments thereof conjugated to a therapeutic agent. Nonlimiting examples of these conjugates are disclosed in U.S. Provisional Application 60/714,362, filed Sep. 7, 2005, U.S. Provisional Application 60/735,966, filed Nov. 14, 2005, 2005, U.S. Patent Application Publication No. US2005/0180972 A1, and U.S. Patent Application Publication No. US2005/0123536 A1, each of which is hereby incorporated by reference in its entirety herein. 
     An antibody or fragment thereof may be conjugated to a therapeutic moiety such as a cytotoxin, e.g., a cytostatic or cytocidal agent, a therapeutic agent or a radioactive metal ion, e.g., alpha-emitters. A cytotoxin or cytotoxic agent includes any agent that is detrimental to cells. Examples include auristatin molecules (e.g., auristatin E, auristatin F, auristatin PHE, MMAE, MMAF, bryostatin 1, and solastatin 10; see Woyke et al., Antimicrob. Agents Chemother. 46:3802-8 (2002), Woyke et al., Antimicrob. Agents Chemother. 45:3580-4 (2001), Mohammad et al., Anticancer Drugs 12:735-40 (2001), Wall et al, Biochem. Biophys. Res. Commun. 266:76-80 (1999), Mohammad et al., Int. J. Oncol. 15:367-72 (1999), all of which are incorporated herein by reference), paclitaxel, cytochalasin B, gramicidin D, ethidium bromide, emetine, mitomycin, etoposide, tenoposide, vincristine, vinblastine, colchicin, doxorubicin, daunorubicin, dihydroxy anthracin dione, mitoxantrone, mithramycin, actinomycin D, 1-dehydrotestosterone, glucocorticoids, procaine, tetracaine, lidocaine, propranolol, puromycin, epirubicin, and cyclophosphamide and analogs or homologs thereof. Therapeutic agents include, but are not limited to, antimetabolites (e.g., methotrexate, 6-mercaptopurine, 6-thioguanine, cytarabine, 5-fluorouracil decarbazine), alkylating agents (e.g., mechlorethamine, thioepa chlorambucil, melphalan, carmustine (BCNU) and lomustine (CCNU), cyclothosphamide, busulfan, dibromomannitol, streptozotocin, mitomycin C, and cisdichlorodiamine platinum (II) (DDP) cisplatin), anthracyclines (e.g., daunorubicin (formerly daunomycin) and doxorubicin), antibiotics (e.g., dactinomycin (formerly actinomycin), bleomycin, mithramycin, and anthramycin (AMC)), and anti-mitotic agents (e.g., vincristine and vinblastine). 
     Further, an antibody or fragment thereof may be conjugated to a therapeutic agent or drug moiety that modifies a given biological response. Therapeutic agents or drug moieties are not to be construed as limited to classical chemical therapeutic agents. For example, the drug moiety may be a protein or polypeptide possessing a desired biological activity. Such proteins may include, for example, a toxin such as abrin, ricin A, pseudomonas exotoxin, cholera toxin, or diphtheria toxin; a protein such as tumor necrosis factor, α-interferon, β-interferon, nerve growth factor, platelet derived growth factor, tissue plasminogen activator, an apoptotic agent, e.g., TNF-α, TNF-β, AIM I (see, International Publication No. WO 97/33899), AIM II (see, International Publication No. WO 97/34911), Fas Ligand (Takahashi et al., 1994 , J. Immunol.,  6:1567), and VEGI (see, International Publication No. WO 99/23105), a thrombotic agent or an anti-angiogenic agent, e.g., angiostatin or endostatin; or, a biological response modifier such as, for example, a lymphokine (e.g., interleukin-1 (“IL-1”), interleukin-2 (“IL-2”), interleukin-6 (“IL-6”), granulocyte macrophage colony stimulating factor (“GM-CSF”), and granulocyte colony stimulating factor (“G-CSF”)), or a growth factor (e.g., growth hormone (“GH”)). 
     Moreover, an antibody can be conjugated to therapeutic moieties such as a radioactive materials or macrocyclic chelators useful for conjugating radiometal ions (see above for examples of radioactive materials). In certain embodiments, the macrocyclic chelator is 1,4,7,10-tetraazacyclododecane-N,N′,N″,N″-tetraacetic acid (DOTA) which can be attached to the antibody via a linker molecule. Such linker molecules are commonly known in the art and described in Denardo et al., 1998 , Clin Cancer Res.  4:2483-90; Peterson et al., 1999 , Bioconjug. Chem.  10:553; and Zimmerman et al., 1999 , Nucl. Med. Biol.  26:943-50 each incorporated by reference in their entireties. 
     In a specific embodiment, the conjugated antibody is an EphA2 antibody that preferably binds an EphA2 epitope exposed on cancer cells but not on non-cancer cells (i.e., exposed EphA2 epitope antibody). 
     Techniques for conjugating therapeutic moieties to antibodies are well known. Moieties can be conjugated to antibodies by any method known in the art, including, but not limited to aldehyde/Schiff linkage, sulphydryl linkage, acid-labile linkage, cis-aconityl linkage, hydrazone linkage, enzymatically degradable linkage (see generally Garnett, 2002 , Adv. Drug Deliv. Rev.  53:171-216). Additional techniques for conjugating therapeutic moieties to antibodies are well known, see, e.g., Arnon et al., “Monoclonal Antibodies For Immunotargeting Of Drugs In Cancer Therapy,” in Monoclonal Antibodies And Cancer Therapy, Reisfeld et al., (eds.), pp. 243-56 (Alan R. Liss, Inc. 1985); Hellstrom et al., “Antibodies For Drug Delivery,” in Controlled Drug Delivery (2nd Ed.), Robinson et al. (eds.), pp. 623-53 (Marcel Dekker, Inc. 1987); Thorpe, “Antibody Carriers Of Cytotoxic Agents In Cancer Therapy: A Review,” in Monoclonal Antibodies &#39;84: Biological And Clinical Applications, Pinchera et al. (eds.), pp. 475-506 (1985); “Analysis, Results, And Future Prospective Of The Therapeutic Use Of Radiolabeled Antibody In Cancer Therapy,” in Monoclonal Antibodies For Cancer Detection And Therapy, Baldwin et al. (eds.), pp. 303-16 (Academic Press 1985), and Thorpe et al., 1982 , Immunol. Rev.  62:119-58. Methods for fusing or conjugating antibodies to polypeptide moieties are known in the art. See, e.g., U.S. Pat. Nos. 5,336,603, 5,622,929, 5,359,046, 5,349,053, 5,447,851, and 5,112,946; EP 307,434; EP 367,166; International Publication Nos. WO 96/04388 and WO 91/06570; Ashkenazi et al., 1991 , PNAS  88: 10535-10539; Zheng et al., 1995 , J. Immunol.  154:5590-5600; and Vil et al., 1992 , PNAS  89:11337-11341. The fusion of an antibody to a moiety does not necessarily need to be direct, but may occur through linker sequences. Such linker molecules are commonly known in the art and described in Denardo et al., 1998 , Clin Cancer Res.  4:2483-90; Peterson et al., 1999 , Bioconjug. Chem.  10:553; Zimmerman et al., 1999 , Nucl. Med. Biol.  26:943-50; Garnett, 2002 , Adv. Drug Deliv. Rev.  53:171-216, each of which is incorporated herein by reference in its entirety. 
     Alternatively, an antibody can be conjugated to a second antibody to form an antibody heteroconjugate as described by Segal in U.S. Pat. No. 4,676,980, which is incorporated herein by reference in its entirety. 
     Antibodies may also be attached to solid supports, which are particularly useful for immunoassays or purification of the target antigen. Such solid supports include, but are not limited to, glass, cellulose, polyacrylamide, nylon, polystyrene, polyvinyl chloride or polypropylene. 
     5.1.2 Methods of Producing Antibodies 
     The antibodies or fragments thereof can be produced by any method known in the art for the synthesis of antibodies, in particular, by chemical synthesis or preferably, by recombinant expression techniques. 
     Monoclonal antibodies can be prepared using a wide variety of techniques known in the art including the use of hybridoma, recombinant, and phage display technologies, or a combination thereof. For example, monoclonal antibodies can be produced using hybridoma techniques including those known in the art and taught, for example, in Harlow et al.,  Antibodies: A Laboratory Manual , (Cold Spring Harbor Laboratory Press, 2nd ed. 1988); Hammerling, et al., in:  Monoclonal Antibodies and T - Cell Hybridomas  563-681 (Elsevier, N.Y., 1981) (said references incorporated by reference in their entireties). The term “monoclonal antibody” as used herein is not limited to antibodies produced through hybridoma technology. The term “monoclonal antibody” refers to an antibody that is derived from a single clone, including any eukaryotic, prokaryotic, or phage clone, and not the method by which it is produced. 
     Methods for producing and screening for specific antibodies using hybridoma technology are routine and well known in the art. Briefly, mice can be immunized with EphA2 (either the full length protein or a domain thereof, e.g., the extracellular or the ligand binding domain) and once an immune response is detected, e.g., antibodies specific for EphA2 are detected in the mouse serum, the mouse spleen is harvested and splenocytes isolated. The splenocytes are then fused by well known techniques to any suitable myeloma cells, for example cells from cell line SP20 available from the ATCC. Hybridomas are selected and cloned by limited dilution. Hybridoma clones are then assayed by methods known in the art for cells that secrete antibodies capable of binding a polypeptide of the invention. Ascites fluid, which generally contains high levels of antibodies, can be generated by immunizing mice with positive hybridoma clones. 
     Accordingly, monoclonal antibodies can be generated by culturing a hybridoma cell secreting an antibody of the invention wherein, preferably, the hybridoma is generated by fusing splenocytes isolated from a mouse immunized with EphA2 or fragment thereof with myeloma cells and then screening the hybridomas resulting from the fusion for hybridoma clones that secrete an antibody able to bind EphA2. 
     Antibody fragments which recognize specific EphA2 epitopes may be generated by any technique known to those of skill in the art. For example, Fab and F(ab′)2 fragments of the invention may be produced by proteolytic cleavage of immunoglobulin molecules, using enzymes such as papain (to produce Fab fragments) or pepsin (to produce F(ab′)2 fragments). F(ab′)2 fragments contain the variable region, the light chain constant region and the CH1 domain of the heavy chain. Further, the antibodies of the present invention can also be generated using various phage display methods known in the art. 
     In phage display methods, functional antibody domains are displayed on the surface of phage particles which carry the polynucleotide sequences encoding them. In particular, DNA sequences encoding VH and VL domains are amplified from animal cDNA libraries (e.g., human or murine cDNA libraries of lymphoid tissues). The DNA encoding the VH and VL domains are recombined together with an scFv linker by PCR and cloned into a phagemid vector (e.g., p CANTAB 6 or pComb 3 MSS). The vector is electroporated in  E. coli  and the  E. coli  is infected with helper phage. Phage used in these methods are typically filamentous phage including fd and M13 and the VH and VL domains are usually recombinantly fused to either the phage gene III or gene VIII. Phage expressing an antigen binding domain that binds to the EphA2 epitope of interest can be selected or identified with antigen, e.g., using labeled antigen or antigen bound or captured to a solid surface or bead. Examples of phage display methods that can be used to make the antibodies of the present invention include those disclosed in Brinkman et al., 1995 , J. Immunol. Methods  182:41-50; Ames et al., 1995 , J. Immunol. Methods  184:177; Kettleborough et al., 1994 , Eur. J. Immunol.  24:952-958; Persic et al., 1997 , Gene  187:9; Burton et al., 1994 , Advances in Immunology  57:191-280; International Application No. PCT/GB91/01134; International Publication Nos. WO 90/02809, WO 91/10737, WO 92/01047, WO 92/18619, WO 93/11236, WO 95/15982, WO 95/20401, and WO97/13844; and U.S. Pat. Nos. 5,698,426, 5,223,409, 5,403,484, 5,580,717, 5,427,908, 5,750,753, 5,821,047, 5,571,698, 5,427,908, 5,516,637, 5,780,225, 5,658,727, 5,733,743 and 5,969,108; each of which is incorporated herein by reference in its entirety. 
     Phage may be screened for EphA2 binding, particularly to the extracellular domain of EphA2. Agonizing EpbA2 activity (e.g., increasing EphA2 phosphorylation, reducing EphA2 levels) may also be screened. 
     As described in the above references, after phage selection, the antibody coding regions from the phage can be isolated and used to generate whole antibodies, including human antibodies, or any other desired antigen binding fragment, and expressed in any desired host, including mammalian cells, insect cells, plant cells, yeast, and bacteria, e.g., as described below. Techniques to recombinantly produce Fab, Fab′ and F(ab′)2 fragments can also be employed using methods known in the art such as those disclosed in International Publication No. WO 92/22324; Mullinax et al., 1992 , BioTechniques  12:864; Sawai et al., 1995 , AJRI  34:26; and Better et al., 1988 , Science  240:1041 (said references incorporated by reference in their entireties). 
     To generate whole antibodies, PCR primers including VH or VL nucleotide sequences, a restriction site, and a flanking sequence to protect the restriction site can be used to amplify the VH or VL sequences in scFv clones. Utilizing cloning techniques known to those of skill in the art, the PCR amplified VH domains can be cloned into vectors expressing a VH constant region, e.g., the human gamma 4 constant region, and the PCR amplified VL domains can be cloned into vectors expressing a VL constant region, e.g., human kappa or lambda constant regions. Preferably, the vectors for expressing the VH or VL domains comprise an EF-1α promoter, a secretion signal, a cloning site for the variable domain, constant domains, and a selection marker such as neomycin. The VH and VL domains may also be cloned into one vector expressing the necessary constant regions. The heavy chain conversion vectors and light chain conversion vectors are then co-transfected into cell lines to generate stable or transient cell lines that express full-length antibodies, e.g., IgG, using techniques known to those of skill in the art. 
     For some uses, including in vivo use of antibodies in humans and in vitro detection assays, it may be preferable to use human or chimeric antibodies. Completely human antibodies are particularly desirable for therapeutic treatment of human subjects. Human antibodies can be made by a variety of methods known in the art including phage display methods described above using antibody libraries derived from human immunoglobulin sequences. See also U.S. Pat. Nos. 4,444,887 and 4,716,111; and International Publication Nos. WO 98/46645, WO 98/50433, WO 98/24893, WO 98/16654, WO 96/34096, WO 96/33735, and WO 91/10741; each of which is incorporated herein by reference in its entirety. 
     Human antibodies can also be produced using transgenic mice which are incapable of expressing functional endogenous immunoglobulins, but which can express human immunoglobulin genes. For example, the human heavy and light chain immunoglobulin gene complexes may be introduced randomly or by homologous recombination into mouse embryonic stem cells. Alternatively, the human variable region, constant region, and diversity region may be introduced into mouse embryonic stem cells in addition to the human heavy and light chain genes. The mouse heavy and light chain immunoglobulin genes may be rendered non-functional separately or simultaneously with the introduction of human immunoglobulin loci by homologous recombination. In particular, homozygous deletion of the J H  region prevents endogenous antibody production. The modified embryonic stem cells are expanded and microinjected into blastocysts to produce chimeric mice. The chimeric mice are then bred to produce homozygous offspring which express human antibodies. The transgenic mice are immunized in the normal fashion with a selected antigen, e.g., all or a portion of a polypeptide of the invention. Monoclonal antibodies directed against the antigen can be obtained from the immunized, transgenic mice using conventional hybridoma technology. The human immunoglobulin transgenes harbored by the transgenic mice rearrange during B cell differentiation, and subsequently undergo class switching and somatic mutation. Thus, using such a technique, it is possible to produce therapeutically useful IgG, IgA, IgM and IgE antibodies. For an overview of this technology for producing human antibodies, see Lonberg and Huszar (1995 , Int. Rev. Immunol.  13:65-93). For a detailed discussion of this technology for producing human antibodies and human monoclonal antibodies and protocols for producing such antibodies, see, e.g., International Publication Nos. WO 98/24893, WO 96/34096, and WO 96/33735; and U.S. Pat. Nos. 5,413,923, 5,625,126, 5,633,425, 5,569,825, 5,661,016, 5,545,806, 5,814,318, and 5,939,598, which are incorporated by reference herein in their entirety. In addition, companies such as Abgenix, Inc. (Fremont, Calif.) and Medarex (Princeton, N.J.) can be engaged to provide human antibodies directed against a selected antigen using technology similar to that described above. 
     A chimeric antibody is a molecule in which different portions of the antibody are derived from different immunoglobulin molecules such as antibodies having a variable region derived from a non-human antibody and a human immunoglobulin constant region. Methods for producing chimeric antibodies are known in the art. See, e.g., Morrison, 1985 , Science  229:1202; Oi et al., 1986 , BioTechniques  4:214; Gillies et al., 1989 , J. Immunol. Methods  125:191-202; and U.S. Pat. Nos. 6,311,415, 5,807,715, 4,816,567, and 4,816,397, which are incorporated herein by reference in their entirety. Chimeric antibodies comprising one or more CDRs from a non-human species and framework regions from a human immunoglobulin molecule can be produced using a variety of techniques known in the art including, for example, CDR-grafting (EP 239,400; International Publication No. WO 91/09967; and U.S. Pat. Nos. 5,225,539, 5,530,101, and 5,585,089), veneering or resurfacing (EP 592,106; EP 519,596; Padlan, 1991 , Molecular Immunology  28(4/5):489-498; Studnicka et al., 1994 , Protein Engineering  7:805; and Roguska et al., 1994 , PNAS  91:969), and chain shuffling (U.S. Pat. No. 5,565,332). 
     In one embodiment, a chimeric antibody of the invention specifically binds EphA2 and comprises one, two, or three VL CDRs having an amino acid sequence of any of the V L  CDRs of 2A4, 2E7, or 12E2 (Seq ID Nos: 6-8, 22-24, and 30-32) within human framework regions. In a specific embodiment, a chimeric antibody of the invention specifically binds EphA2 and comprises a VL CDR having the amino acid sequence of a VL CDR from 2A4, 2E7, or 12E2 (Seq ID Nos: 6-8, 22-24, and 30-32) as disclosed in  FIG. 3 . In another embodiment, a chimeric antibody of the invention specifically binds EphA2 and comprises one, two, or three VH CDRs having an amino acid sequence of any of the VH CDRs of 2A4, 2E7, or 12E2 (Seq ID Nos: 3-5, 19-21 and 27-29) within human framework regions. In a specific embodiment, a chimeric antibody of the invention specifically binds EphA2 and comprises a VH CDR having the amino acid sequence of a VH CDR from 2A4, 2E7, or 12E2 (Seq ID Nos: 3-5, 19-21 and 27-29) as disclosed in  FIG. 3 . In a further embodiment, a chimeric antibody of the invention specifically binds EphA2 and comprises one, two, or three VL CDRs having an amino acid sequence of any of the VL CDRs of 2A4, 2E7, or 12E2 (Seq ID Nos: 6-8, 22-24, and 30-32) and further comprises one, two, or three VH CDRs having an amino acid sequence of any of the VH CDRs of 2A4, 2E7, or 12E2 (Seq ID Nos: 3-5, 19-21 and 27-29) within human framework regions. In a specific embodiment, a chimeric antibody of the invention specifically binds EphA2 and comprises a VL CDR having an amino acid sequence of a VL CDR from 2A4, 2E7, or 12E2 (Seq ID Nos: 6-8, 22-24, and 30-32) as disclosed in  FIG. 3  and further comprises a VH CDR having an amino acid sequence of a VH CDR from 2A4, 2E7, or 12E2 (Seq ID Nos: 3-5, 19-21 and 27-29) as disclosed in  FIG. 3 . In a further embodiment, a chimeric antibody of the invention specifically binds EphA2 and comprises three VL CDRs having an amino acid sequence of any of the VL CDRs of 2A4, 2E7, or 12E2 (Seq ID Nos: 6-8, 22-24, and 30-32) and three VH CDRs having an amino acid sequence of any of the VH CDRs of 2A4, 2E7, or 12E2 (Seq ID Nos: 3-5, 19-21 and 27-29) within human framework regions. In yet a further embodiment, a chimeric antibody of the invention specifically binds EphA2 and comprises VL CDRs having an amino acid sequence selected from the group consisting of a VL CDR from 2A4, 2E7, or 12E2 (Seq ID Nos: 6-8, 22-24, and 30-32) as disclosed in  FIG. 3 , and further comprises VH CDRs having an amino acid sequence selected from the group consisting of a VH CDR from 2A4, 2E7, or 12E2 (Seq ID Nos: 3-5, 19-21 and 27-29) as disclosed in  FIG. 3 . 
     Often, framework residues in the framework regions will be substituted with the corresponding residue from the CDR donor antibody to alter, preferably improve, antigen binding. These framework substitutions are identified by methods well known in the art, e.g., by modeling of the interactions of the CDR and framework residues to identify framework residues important for antigen binding and sequence comparison to identify unusual framework residues at particular positions. (See, e.g., U.S. Pat. No. 5,585,089; and Riechmann et al., 1988 , Nature  332:323, which are incorporated herein by reference in their entireties.) 
     A humanized antibody is an antibody or its variant or fragment thereof which is capable of binding to a predetermined antigen and which comprises a framework region having substantially the amino acid sequence of a human immunoglobulin and a CDR having substantially the amino acid sequence of a non-human immunoglobulin. A humanized antibody comprises substantially all of at least one, and typically two, variable domains in which all or substantially all of the CDR regions correspond to those of a non-human immunoglobulin (i.e., donor antibody) and all or substantially all of the framework regions are those of a human immunoglobulin consensus sequence. Preferably, a humanized antibody also comprises at least a portion of an immunoglobulin constant region (Fc), typically that of a human immunoglobulin. Ordinarily, the antibody will contain both the light chain as well as at least the variable domain of a heavy chain. The antibody also may include the CH1, hinge, CH2, CH3, and CH4 regions of the heavy chain. The humanized antibody can be selected from any class of immunoglobulins, including IgM, IgG, IgD, IgA and IgE, and any isotype, including IgG1, IgG2, IgG 3  and IgG 4 . Usually the constant domain is a complement fixing constant domain where it is desired that the humanized antibody exhibit cytotoxic activity, and the class is typically IgG 1 . Where such cytotoxic activity is not desirable, the constant domain may be of the IgG 2  class. The humanized antibody may comprise sequences from more than one class or isotype, and selecting particular constant domains to optimize desired effector functions is within the ordinary skill in the art. The framework and CDR regions of a humanized antibody need not correspond precisely to the parental sequences, e.g., the donor CDR or the consensus framework may be mutagenized by substitution, insertion or deletion of at least one residue so that the CDR or framework residue at that site does not correspond to either the consensus or the import antibody. Such mutations, however, will not be extensive. Usually, at least 75% of the humanized antibody residues will correspond to those of the parental framework region (FR) and CDR sequences, more often 90%, and most preferably greater than 95%. Humanized antibodies can be produced using variety of techniques known in the art, including but not limited to, CDR-grafting (European Patent No. EP 239,400; International Publication No. WO 91/09967; and U.S. Pat. Nos. 5,225,539, 5,530,101, and 5,585,089), veneering or resurfacing (European Patent Nos. EP 592,106 and EP 519,596; Padlan, 1991 , Molecular Immunology  28(4/5):489-498; Studnicka et al., 1994 , Protein Engineering  7(6):805-814; and Roguska et al., 1994 , PNAS  91:969-973), chain shuffling (U.S. Pat. No. 5,565,332), and techniques disclosed in, e.g., U.S. Pat. Nos. 6,407,213, 5,766,886, 5,585,089, International Publication No. WO 9317105, Tan et al., 2002 , J. Immunol.  169:1119-25, Caldas et al., 2000 , Protein Eng.  13:353-60, Morea et al., 2000 , Methods  20:267-79, Baca et al., 1997 , J. Biol. Chem.  272:10678-84, Roguska et al., 1996 , Protein Eng.  9:895-904, Couto et al., 1995 , Cancer Res.  55 (23 Supp):5973s-5977s, Couto et al., 1995 , Cancer Res.  55:1717-22, Sandhu, 1994 , Gene  150:409-10, Pedersen et al., 1994 , J. Mol. Biol.  235:959-73, Jones et al., 1986 , Nature  321:522-525, Riechmann et al., 1988 , Nature  332:323, and Presta, 1992 , Curr. Op. Struct. Biol.  2:593-596. Often, framework residues in the framework regions will be substituted with the corresponding residue from the CDR donor antibody to alter, preferably improve, antigen binding. These framework substitutions are identified by methods well known in the art, e.g., by modeling of the interactions of the CDR and framework residues to identify framework residues important for antigen binding and sequence comparison to identify unusual framework residues at particular positions. (See, e.g., Queen et al., U.S. Pat. No. 5,585,089; and Riechmann et al., 1988, Nature 332:323, which are incorporated herein by reference in their entireties.) 
     Further, the antibodies of the invention can, in turn, be utilized to generate anti-idiotype antibodies using techniques well known to those skilled in the art. (See, e.g., Greenspan &amp; Bona, 1989 , FASEB J.  7:437-444; and Nissinoff, 1991 , J. Immunol.  147:2429-2438). The invention provides methods employing the use of polynucleotides comprising a nucleotide sequence encoding an antibody of the invention or a fragment thereof. 
     5.1.3 Polynucleotides Encoding an Antibody 
     The methods of the invention also encompass polynucleotides that hybridize under high stringency, intermediate or lower stringency hybridization conditions, e.g., as defined supra, to polynucleotides that encode an antibody of the invention. In a specific embodiment, the invention provides an isolated nucleic acid comprising a nucleotide sequence encoding a heavy chain variable domain or a light chain variable domain of an antibody of the invention (e.g., 2A4, 2E7, or 12E2) (Seq ID Nos: 1, 17 and 25). In another specific embodiment, the invention provides an isolated nucleic acid comprising a nucleotide sequence encoding a heavy chain variable domain or a light chain variable domain of an antibody of the invention (e.g., 2A4, 2E7, or 12E2) (Seq ID Nos: 1, 17 and 25) that has been humanized or chimerized. 
     The polynucleotides may be obtained, and the nucleotide sequence of the polynucleotides determined, by any method known in the art. Since the amino acid sequences of the antibodies are known, nucleotide sequences encoding these antibodies can be determined using methods well known in the art, i.e., nucleotide codons known to encode particular amino acids are assembled in such a way to generate a nucleic acid that encodes the antibody or fragment thereof of the invention. Such a polynucleotide encoding the antibody may be assembled from chemically synthesized oligonucleotides (e.g., as described in Kutmeier et al., 1994 , BioTechniques  17:242), which, briefly, involves the synthesis of overlapping oligonucleotides containing portions of the sequence encoding the antibody, annealing and ligating of those oligonucleotides, and then amplification of the ligated oligonucleotides by PCR. 
     Alternatively, a polynucleotide encoding an antibody may be generated from nucleic acid from a suitable source. If a clone containing a nucleic acid encoding a particular antibody is not available, but the sequence of the antibody molecule is known, (see e.g.,  FIGS. 3 and 4 ), a nucleic acid encoding the immunoglobulin may be chemically synthesized or obtained from a suitable source (e.g., an antibody cDNA library, or a cDNA library generated from, or nucleic acid, preferably poly A+ RNA, isolated from, any tissue or cells expressing the antibody, such as hybridoma cells selected to express an antibody of the invention, e.g., clone deposited in the ATCC as PTA-4380) by PCR amplification using synthetic primers hybridizable to the 3′ and 5′ ends of the sequence or by cloning using an oligonucleotide probe specific for the particular gene sequence to identify, e.g., a cDNA clone from a cDNA library that encodes the antibody. Amplified nucleic acids generated by PCR may then be cloned into replicable cloning vectors using any method well known in the art. 
     Once the nucleotide sequence of the antibody is determined, the nucleotide sequence of the antibody may be manipulated using methods well known in the art for the manipulation of nucleotide sequences, e.g., recombinant DNA techniques, site directed mutagenesis, PCR, etc. (see, for example, the techniques described in Sambrook et al., 1990, Molecular Cloning, A Laboratory Manual, 2d Ed., Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y. and Ausubel et al., eds., 1998, Current Protocols in Molecular Biology, John Wiley &amp; Sons, NY, which are both incorporated by reference herein in their entireties), to generate antibodies having a different amino acid sequence, for example to create amino acid substitutions, deletions, and/or insertions. 
     In a specific embodiment, one or more of the CDRs is inserted within framework regions using routine recombinant DNA techniques. The framework regions may be naturally occurring or consensus framework regions, and preferably human framework regions (see, e.g., Chothia et al., 1998 , J. Mol. Biol.  278: 457-479 for a listing of human framework regions). Preferably, the polynucleotide generated by the combination of the framework regions and CDRs encodes an antibody that specifically binds to EphA2. Preferably, as discussed supra, one or more amino acid substitutions may be made within the framework regions, and, preferably, the amino acid substitutions improve binding of the antibody to its antigen. Additionally, such methods may be used to make amino acid substitutions or deletions of one or more variable region cysteine residues participating in an intrachain disulfide bond to generate antibody molecules lacking one or more intrachain disulfide bonds. Other alterations to the polynucleotide are encompassed by the present invention and within the skill of the art. 
     5.1.4 Recombinant Expression of an Antibody 
     Recombinant expression of an antibody of the invention, derivative, analog or fragment thereof, (e.g., a heavy or light chain of an antibody of the invention or a portion thereof or a single chain antibody of the invention), requires construction of an expression vector containing a polynucleotide that encodes the antibody. Once a polynucleotide encoding an antibody molecule or a heavy or light chain of an antibody, or portion thereof (preferably, but not necessarily, containing the heavy or light chain variable domain), of the invention has been obtained, the vector for the production of the antibody molecule may be produced by recombinant DNA technology using techniques well known in the art. Thus, methods for preparing a protein by expressing a polynucleotide containing an antibody encoding nucleotide sequence are described herein. Methods which are well known to those skilled in the art can be used to construct expression vectors containing antibody coding sequences and appropriate transcriptional and translational control signals. These methods include, for example, in vitro recombinant DNA techniques, synthetic techniques, and in vivo genetic recombination. The invention, thus, provides replicable vectors comprising a nucleotide sequence encoding an antibody molecule of the invention, a heavy or light chain of an antibody, a heavy or light chain variable domain of an antibody or a portion thereof, or a heavy or light chain CDR, operably linked to a promoter. Such vectors may include the nucleotide sequence encoding the constant region of the antibody molecule (see, e.g., International Publication Nos. WO 86/05807 and WO 89/01036; and U.S. Pat. No. 5,122,464) and the variable domain of the antibody may be cloned into such a vector for expression of the entire heavy, the entire light chain, or both the entire heavy and light chains. 
     The expression vector is transferred to a host cell by conventional techniques and the transfected cells are then cultured by conventional techniques to produce an antibody of the invention. Thus, the invention includes host cells containing a polynucleotide encoding an antibody of the invention or fragments thereof, or a heavy or light chain thereof, or portion thereof, or a single chain antibody of the invention, operably linked to a heterologous promoter. In further embodiments for the expression of double-chained antibodies, vectors encoding both the heavy and light chains may be co-expressed in the host cell for expression of the entire immunoglobulin molecule, as detailed below. 
     A variety of host-expression vector systems may be utilized to express the antibody molecules of the invention (see, e.g., U.S. Pat. No. 5,807,715). Such host-expression systems represent vehicles by which the coding sequences of interest may be produced and subsequently purified, but also represent cells which may, when transformed or transfected with the appropriate nucleotide coding sequences, express an antibody molecule of the invention in situ. These include but are not limited to microorganisms such as bacteria (e.g.,  E. coli  and  B. subtilis ) transformed with recombinant bacteriophage DNA, plasmid DNA or cosmid DNA expression vectors containing antibody coding sequences; yeast (e.g.,  Saccharomyces Pichia ) transformed with recombinant yeast expression vectors containing antibody coding sequences; insect cell systems infected with recombinant virus expression vectors (e.g., baculovirus) containing antibody coding sequences; plant cell systems infected with recombinant virus expression vectors (e.g., cauliflower mosaic virus, CaMV; tobacco mosaic virus, TMV) or transformed with recombinant plasmid expression vectors (e.g., Ti plasmid) containing antibody coding sequences; or mammalian cell systems (e.g., COS, CHO, BHK, 293, NS0, and 3T3 cells) harboring recombinant expression constructs containing promoters derived from the genome of mammalian cells (e.g., metallothionein promoter) or from mammalian viruses (e.g., the adenovirus late promoter; the vaccinia virus 7.5K promoter). Preferably, bacterial cells such as  Escherichia coli  and more preferably, eukaryotic cells, especially for the expression of whole recombinant antibody molecule, are used for the expression of a recombinant antibody molecule. For example, mammalian cells such as Chinese hamster ovary cells (CHO), in conjunction with a vector such as the major intermediate early gene promoter element from human cytomegalovirus is an effective expression system for antibodies (Foecking et al., 1986 , Gene  45:101; and Cockett et al., 1990 , BioTechnology  8:2). In a specific embodiment, the expression of nucleotide sequences encoding antibodies or fragments thereof which specifically bind to and agonize is regulated by a constitutive promoter, inducible promoter or tissue specific promoter. 
     In bacterial systems, a number of expression vectors may be advantageously selected depending upon the use intended for the antibody molecule being expressed. For example, when a large quantity of such a protein is to be produced, for the generation of pharmaceutical compositions of an antibody molecule, vectors which direct the expression of high levels of fission protein products that are readily purified may be desirable. Such vectors include, but are not limited to, the  E. coli  expression vector pUR278 (Ruther et al., 1983 , EMBO  12:1791), in which the antibody coding sequence may be ligated individually into the vector in frame with the lac Z coding region so that a fusion protein is produced; pIN vectors (Inouye &amp; Inouye, 1985, Nucleic Acids Res. 13:3101-3109; Van Heeke &amp; Schuster, 1989, J. Biol. Chem. 24:5503-5509); and the like. pGEX vectors may also be used to express foreign polypeptides as fusion proteins with glutathione 5-transferase (GST). In general, such fusion proteins are soluble and can easily be purified from lysed cells by adsorption and binding to matrix glutathione-agarose beads followed by elution in the presence of free glutathione. The pGEX vectors are designed to include thrombin or factor Xa protease cleavage sites so that the cloned target gene product can be released from the GST moiety. 
     In an insect system,  Autographa californica  nuclear polyhedrosis virus (AcNPV) is used as a vector to express foreign genes. The virus grows in  Spodoptera frugiperda  cells. The antibody coding sequence may be cloned individually into non-essential regions (for example the polyhedrin gene) of the virus and placed under control of an AcNPV promoter (for example the polyhedrin promoter). 
     In mammalian host cells, a number of viral-based expression systems may be utilized. In cases where an adenovirus is used as an expression vector, the antibody coding sequence of interest may be ligated to an adenovirus transcription/translation control complex, e.g., the late promoter and tripartite leader sequence. This chimeric gene may then be inserted in the adenovirus genome by in vitro or in vivo recombination. Insertion in a non-essential region of the viral genome (e.g., region E1 or E3) will result in a recombinant virus that is viable and capable of expressing the antibody molecule in infected hosts (e.g., see Logan &amp; Shenk, 1984 , PNAS  8 1:355-359). Specific initiation signals may also be required for efficient translation of inserted antibody coding sequences. These signals include the ATG initiation codon and adjacent sequences. Furthermore, the initiation codon must be in phase with the reading frame of the desired coding sequence to ensure translation of the entire insert. These exogenous translational control signals and initiation codons can be of a variety of origins, both natural and synthetic. The efficiency of expression may be enhanced by the inclusion of appropriate transcription enhancer elements, transcription terminators, etc. (see, e.g., Bittner et al., 1987 , Methods in Enzymol.  153:516-544). 
     In addition, a host cell strain may be chosen which modulates the expression of the inserted sequences, or modifies and processes the gene product in the specific fashion desired. Such modifications (e.g., glycosylation) and processing (e.g., cleavage) of protein products may be important for the function of the protein. Different host cells have characteristic and specific mechanisms for the post-translational processing and modification of proteins and gene products. Appropriate cell lines or host systems can be chosen to ensure the correct modification and processing of the foreign protein expressed. To this end, eukaryotic host cells which possess the cellular machinery for proper processing of the primary transcript, glycosylation, and phosphorylation of the gene product may be used. Such mammalian host cells include but are not limited to CHO, VERO, BHK, HeLa, COS, MDCK, 293, 3T3, WI 38, BT483, Hs578T, HTB2, BT2O, NS1, and T47D, NS0 (a murine myeloma cell line that does not endogenously produce any immunoglobulin chains), CRL7O3O and HsS78Bst cells. 
     For long-term, high-yield production of recombinant proteins, stable expression is preferred. For example, cell lines which stably express the antibody molecule may be engineered. Rather than using expression vectors which contain viral origins of replication, host cells can be transformed with DNA controlled by appropriate expression control elements (e.g., promoter, enhancer, sequences, transcription terminators, polyadenylation sites, etc.), and a selectable marker. Following the introduction of the foreign DNA, engineered cells may be allowed to grow for 1-2 days in an enriched media, and then are switched to a selective media. The selectable marker in the recombinant plasmid confers resistance to the selection and allows cells to stably integrate the plasmid into their chromosomes and grow to form foci which in turn can be cloned and expanded into cell lines. This method may advantageously be used to engineer cell lines which express the antibody molecule. Such engineered cell lines may be particularly useful in screening and evaluation of compositions that interact directly or indirectly with the antibody molecule. 
     A number of selection systems may be used, including but not limited to, the herpes simplex virus thymidine kinase (Wigler et al., 1977 , Cell  11:223), glutamine synthase, hypoxanthine guanine phosphoribosyltransferase (Szybalska &amp; Szybalski, 1992, Proc. Natl. Acad. Sci. USA 48:202), and adenine phosphoribosyltransferase (Lowy et al., 1980 , Cell  22:8-17) genes can be employed in tk-, gs-, hgprt- or aprt-cells, respectively. Also, antimetabolite resistance can be used as the basis of selection for the following genes: dhfr, which confers resistance to methotrexate (Wigler et al., 1980 , PNAS  77:357; O&#39;Hare et al., 1981 , PNAS  78:1527); gpt, which confers resistance to mycophenolic acid (Mulligan &amp; Berg, 1981 , PNAS  78:2072); neo, which confers resistance to the aminoglycoside G-418 (Wu and Wu, 1991 , Biotherapy  3:87; Tolstoshev, 1993 , Ann. Rev. Pharmacol. Toxicol.  32:573; Mulligan, 1993 , Science  260:926; and Morgan and Anderson, 1993 , Ann. Rev. Biochem.  62: 191; May, 1993 , TIB TECH  11:155-); and hygro, which confers resistance to hygromycin (Santerre et al., 1984 , Gene  30:147). Methods commonly known in the art of recombinant DNA technology may be routinely applied to select the desired recombinant clone, and such methods are described, for example, in Ausubel et al. (eds.), Current Protocols in Molecular Biology, John Wiley &amp; Sons, NY (1993); Kriegler, Gene Transfer and Expression, A Laboratory Manual, Stockton Press, NY (1990); and in Chapters 12 and 13, Dracopoli et al. (eds), Current Protocols in Human Genetics, John Wiley &amp; Sons, NY (1994); Colberre-Garapin et al., 1981 , J. Mol. Biol.  150:1, which are incorporated by reference herein in their entireties. 
     The expression levels of an antibody molecule can be increased by vector amplification (for a review, see Bebbington and Hentschel, The use of vectors based on gene amplification for the expression of cloned genes in mammalian cells in DNA cloning, Vol. 3. (Academic Press, New York, 1987)). When a marker in the vector system expressing antibody is amplifiable, increase in the level of inhibitor present in culture of host cell will increase the number of copies of the marker gene. Since the amplified region is associated with the antibody gene, production of the antibody will also increase (Crouse et al., 1983 , Mol. Cell. Biol.  3:257). 
     The host cell may be co-transfected with two expression vectors of the invention, the first vector encoding a heavy chain derived polypeptide and the second vector encoding a light chain derived polypeptide. The two vectors may contain identical selectable markers which enable equal expression of heavy and light chain polypeptides. Alternatively, a single vector may be used which encodes, and is capable of expressing, both heavy and light chain polypeptides. In such situations, the light chain should be placed before the heavy chain to avoid an excess of toxic free heavy chain (Proudfoot, 1986 , Nature  322:52; and Kohler, 1980 , PNAS  77:2197). The coding sequences for the heavy and light chains may comprise cDNA or genomic DNA. 
     Once an antibody molecule of the invention has been produced by recombinant expression, it may be purified by any method known in the art for purification of an immunoglobulin molecule, for example, by chromatography (e.g., ion exchange, affinity, particularly by affinity for the specific antigen after Protein A, and sizing column chromatography), centrifugation, differential solubility, or by any other standard technique for the purification of proteins. Further, the antibodies of the present invention or fragments thereof may be fused to heterologous polypeptide sequences described herein or otherwise known in the art to facilitate purification. 
     5.2 Prophylactic/Therapeutic Methods 
     The present invention encompasses methods for treating, preventing, or managing a disorder associated with overexpression of EphA2, preferably cancer, in a subject comprising administering one or more EphA2 agonistic antibodies and/or exposed EphA2 epitope antibodies, preferably one or more monoclonal (or antibodies from some other source of a single antibody species) EphA2 agonistic antibodies and/or exposed EphA2 epitope antibodies. In a specific embodiment, the disorder to be treated, prevented, or managed is malignant cancer. In another specific embodiment, the disorder to be treated, prevented, or managed is a pre-cancerous condition associated with cells that overexpress EphA2. In more specific embodiments, the pre-cancerous condition is high-grade prostatic intraepithelial neoplasia (PIN), fibroadenoma of the breast, fibrocystic disease, or compound nevi. 
     In one embodiment, the antibodies of the invention can be administered in combination with one or more other therapeutic agents useful in the treatment, prevention or management of cancer. In certain embodiments, one or more EphA2 antibodies of the invention are administered to a mammal, preferably a human, concurrently with one or more other therapeutic agents useful for the treatment of cancer. The term “concurrently” is not limited to the administration of prophylactic or therapeutic agents at exactly the same time, but rather it is meant that the EphA2 antibodies of the invention and the other agent are administered to a subject in a sequence and within a time interval such that the antibodies of the invention can act together with the other agent to provide an increased benefit than if they were administered otherwise. For example, each prophylactic or therapeutic agent may be administered at the same time or sequentially in any order at different points in time; however, if not administered at the same time, they should be administered sufficiently close in time so as to provide the desired therapeutic or prophylactic effect. Each therapeutic agent can be administered separately, in any appropriate form and by any suitable route. In other embodiments, the EphA2 antibodies of the invention are administered before, concurrently or after surgery. Preferably the surgery completely removes localized tumors or reduces the size of large tumors. Surgery can also be done as a preventive measure or to relieve pain. 
     In one embodiment, the one or more EphA2 antibodies of the invention consist of 2A4, 2E7, or 12E2. In other embodiments, variants of 2A4, 2E7, or 12E2, e.g., with one or more amino acid substitutions, particularly in the variable domain, are provided that have increased activity, binding ability, etc., as compared to 2A4, 2E7, or 12E2. 
     In various embodiments, the prophylactic or therapeutic agents are administered less than 1 hour apart, at about 1 hour apart, at about 1 hour to about 2 hours apart, at about 2 hours to about 3 hours apart, at about 3 hours to about 4 hours apart, at about 4 hours to about 5 hours apart, at about 5 hours to about 6 hours apart, at about 6 hours to about 7 hours apart, at about 7 hours to about 8 hours apart, at about 8 hours to about 9 hours apart, at about 9 hours to about 10 hours apart, at about 10 hours to about 11 hours apart, at about 11 hours to about 12 hours apart, no more than 24 hours apart or no more than 48 hours apart. In further embodiments, two or more components are administered within the same patient visit. 
     The dosage amounts and frequencies of administration provided herein are encompassed by the ten-s therapeutically effective and prophylactically effective. The dosage and frequency further will typically vary according to factors specific for each patient depending on the specific therapeutic or prophylactic agents administered, the severity and type of cancer, the route of administration, as well as age, body weight, response, and the past medical history of the patient. Suitable regimens can be selected by one skilled in the art by considering such factors and by following, for example, dosages reported in the literature and recommended in the  Physicians&#39; Desk Reference  (58 th  ed., 2004). 
     5.2.1 Patient Population 
     The invention provides methods for treating, preventing, and managing cancer by administrating to a subject a therapeutically or prophylactically effective amount of one or more EphA2 antibodies of the invention. In another embodiment, the EphA2 antibodies of the invention can be administered in combination with one or more other therapeutic agents. The subject is preferably a mammal such as non-primate (e.g., cows, pigs, horses, cats, dogs, rats, etc.) and a primate (e.g., monkey, such as a cynomolgous monkey and a human). In a further embodiment, the subject is a human. 
     Specific examples of cancers that can be treated by the methods encompassed by the invention include, but are not limited to, cancers that over express EphA2. In a further embodiment, the cancer is of an epithelial origin. Examples of such cancers are cancer of the lung, colon, prostate, breast, and skin. Additional cancers are listed by example and not by limitation in the following section 52.1.1. In particular embodiments, methods of the invention can be used to treat and/or prevent metastasis from primary tumors. 
     The methods and compositions of the invention comprise the administration of one or more EphA2 antibodies of the invention to subjects/patients suffering from or expected to suffer from cancer, e.g., have a genetic predisposition for a particular type of cancer, have been exposed to a carcinogen, or are in remission from a particular cancer. As used herein, “cancer” refers to primary or metastatic cancers. Such patients may or may not have been previously treated for cancer. The methods and compositions of the invention may be used as a first line or second line cancer treatment. Included in the invention is also the treatment of patients undergoing other cancer therapies and the methods and compositions of the invention can be used before any adverse effects or intolerance of these other cancer therapies occurs. The invention also encompasses methods for administering one or more EphA2 antibodies of the invention to treat or ameliorate symptoms in refractory patients. In a certain embodiment, that a cancer is refractory to a therapy means that at least some significant portion of the cancer cells are not killed or their cell division arrested. The determination of whether the cancer cells are refractory can be made either in vivo or in vitro by any method known in the art for assaying the effectiveness of treatment on cancer cells, using the art-accepted meanings of “refractory” in such a context. In various embodiments, a cancer is refractory where the number of cancer cells has not been significantly reduced, or has increased. The invention also encompasses methods for administering one or more EphA2 agonistic antibodies to prevent the onset or recurrence of cancer in patients predisposed to having cancer. In one embodiment, the monoclonal antibody is 2A4, 2E7, or 12E2. 
     In particular embodiments, the EphA2 antibodies of the invention, or other therapeutics that reduce EphA2 expression, are administered to reverse resistance or reduced sensitivity of cancer cells to certain hormonal, radiation and chemotherapeutic agents thereby resensitizing the cancer cells to one or more of these agents, which can then be administered (or continue to be administered) to treat or manage cancer, including to prevent metastasis. 
     In alternate embodiments, the invention provides methods for treating patients&#39; cancer by administering one or more EphA2 antibodies of the invention in combination with any other treatment or to patients who have proven refractory to other treatments but are no longer on these treatments. In one embodiment, the EphA2 antibody is 2A4, 2E7, or 12E2. In certain embodiments, the patients being treated by the methods of the invention are patients already being treated with chemotherapy, radiation therapy, hormonal therapy, or biological therapy/immunotherapy. Among these patients are refractory patients and those with cancer despite treatment with existing cancer therapies. In other embodiments, the patients have been treated and have no disease activity and one or more agonistic antibodies of the invention are administered to prevent the recurrence of cancer. 
     In certain embodiments, the existing treatment is chemotherapy. In particular embodiments, the existing treatment includes administration of chemotherapies including but not limited to, methotrexate, taxol, mercaptopurine, thioguanine, hydroxyurea, cytarabine, cyclophosphamide, ifosfamide, nitrosoureas, cisplatin, carboplatin, mitomycin, dacarbazine, procarbizine, etoposides, campathecins, bleomycin, doxorubicin, idarubicin, daunorubicin, dactinomycin, plicamycin, mitoxantrone, asparaginase, vinblastine, vincristine, vinorelbine, paclitaxel, docetaxel, etc. Among these patients are patients treated with radiation therapy, hormonal therapy and/or biological therapy/immunotherapy. Also among these patients are those who have undergone surgery for the treatment of cancer. 
     Alternatively, the invention also encompasses methods for treating patients undergoing or having undergone radiation therapy. Among these are patients being treated or previously treated with chemotherapy, hormonal therapy and/or biological therapy/immunotherapy. Also among these patients are those who have undergone surgery for the treatment of cancer. 
     In other embodiments, the invention encompasses methods for treating patients undergoing or having undergone hormonal therapy and/or biological therapy/immunotherapy. Among these are patients being treated or having been treated with chemotherapy and/or radiation therapy. Also among these patients are those who have undergone surgery for the treatment of cancer. 
     Additionally, the invention also provides methods of treatment of cancer as an alternative to chemotherapy, radiation therapy, hormonal therapy, and/or biological therapy/immunotherapy where the therapy has proven or may prove too toxic, i.e., results in unacceptable or unbearable side effects, for the subject being treated. The subject being treated with the methods of the invention may, optionally, be treated with other cancer treatments such as surgery, chemotherapy, radiation therapy, hormonal therapy or biological therapy, depending on which treatment was found to be unacceptable or unbearable. 
     In other embodiments, the invention provides administration of one or more agonistic monoclonal antibodies of the invention without any other cancer therapies for the treatment of cancer, but who have proved refractory to such treatments. In specific embodiments, patients refractory to other cancer therapies are administered one or more agonistic monoclonal antibodies in the absence of cancer therapies. 
     In other embodiments, patients with a pre-cancerous condition associated with cells that overexpress EphA2 can be administered antibodies of the invention to treat the disorder and decrease the likelihood that it will progress to malignant cancer. In specific embodiments, the pre-cancerous condition is high-grade prostatic intraepithelial neoplasia (PIN), fibroadenoma of the breast, fibrocystic disease, or compound nevi. 
     5.2.1.1 Cancers 
     Cancers and related disorders that can be treated or prevented by methods and compositions of the present invention include but are not limited to cancers of an epithelial cell origin. Examples of such 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&#39;s disease, non-Hodgkin&#39;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; Waldenström&#39;s macroglobulinemia; monoclonal gammopathy of undetermined significance; benign monoclonal gammopathy; heavy chain disease; bone and connective tissue sarcomas such as but not limited to bone sarcoma, osteosarcoma, chondrosarcoma, Ewing&#39;s sarcoma, malignant giant cell tumor, fibrosarcoma of bone, chordoma, periosteal sarcoma, soft-tissue sarcomas, angiosarcoma (hemangiosarcoma), fibrosarcoma, Kaposi&#39;s sarcoma, leiomyosarcoma, liposarcoma, lymphangiosarcoma, neurilemmoma, rhabdomyosarcoma, synovial sarcoma; brain tumors such as but not limited to, glioma, astrocytoma, brain stem glioma, ependymoma, oligodendroglioma, nonglial tumor, acoustic neurinoma, craniopharyngioma, medulloblastoma, meningioma, pineocytoma, pineoblastoma, primary brain lymphoma; breast cancer including but not limited to adenocarcinoma, lobular (small cell) carcinoma, intraductal carcinoma, medullary breast cancer, mucinous breast cancer, tubular breast cancer, papillary breast cancer, Paget&#39;s disease, and inflammatory breast cancer; adrenal cancer such as but not limited to pheochromocytom and adrenocortical carcinoma; thyroid cancer such as but not limited to papillary or follicular thyroid cancer, medullary thyroid cancer and anaplastic thyroid cancer; pancreatic cancer such as but not limited to, insulinoma, gastrinoma, glucagonoma, vipoma, somatostatin-secreting tumor, and carcinoid or islet cell tumor; pituitary cancers such as but limited to Cushing&#39;s disease, prolactin-secreting tumor, acromegaly, and diabetes insipius; eye cancers such as but not limited to ocular melanoma such as iris melanoma, choroidal melanoma, and cilliary body melanoma, and retinoblastoma; vaginal cancers such as squamous cell carcinoma, adenocarcinoma, and melanoma; vulvar cancer such as squamous cell carcinoma, melanoma, adenocarcinoma, basal cell carcinoma, sarcoma, and Paget&#39;s disease; cervical cancers such as but not limited to, squamous cell carcinoma, and adenocarcinoma; uterine cancers such as but not limited to endometrial carcinoma and uterine sarcoma; ovarian cancers such as but not limited to, ovarian epithelial carcinoma, borderline tumor, germ cell tumor, and stromal tumor; esophageal cancers such as but not limited to, squamous cancer, adenocarcinoma, adenoid cystic carcinoma, mucoepidermoid carcinoma, adenosquamous carcinoma, sarcoma, melanoma, plasmacytoma, verrucous carcinoma, and oat cell (small cell), carcinoma; stomach cancers such as but not limited to, adenocarcinoma, fungating (polypoid), ulcerating, superficial spreading, diffusely spreading, malignant lymphoma, liposarcoma, fibrosarcoma, and carcinosarcoma; colon cancers; rectal cancers; liver cancers such as but not limited to hepatocellular carcinoma and hepatoblastoma; gallbladder cancers such as adenocarcinoma; cholangiocarcinomas such as but not limited to pappillary, nodular, and diffuse; lung cancers such as non-small cell lung cancer, squamous cell carcinoma (epidermoid carcinoma), adenocarcinoma, large-cell carcinoma and small-cell lung cancer; testicular cancers such as but not limited to germinal tumor, seminoma, anaplastic, classic (typical), spermatocytic, nonseminoma, embryonal carcinoma, teratoma carcinoma, choriocarcinoma (yolk-sac tumor), prostate cancers such as but not limited to, adenocarcinoma, leiomyosarcoma, and rhabdomyosarcoma; penal cancers; oral cancers such as but not limited to squamous cell carcinoma; basal cancers; salivary gland cancers such as but not limited to adenocarcinoma, mucoepidermoid carcinoma, and adenoidcystic carcinoma; pharynx cancers such as but not limited to squamous cell cancer, and verrucous; skin cancers such as but not limited to, basal cell carcinoma, squamous cell carcinoma and melanoma, superficial spreading melanoma, nodular melanoma, lentigo malignant melanoma, acral lentiginous melanoma; kidney cancers such as but not limited to renal cell carcinoma, adenocarcinoma, hypemephroma, fibrosarcoma, transitional cell cancer (renal pelvis and/or uterer); Wilms&#39; tumor; bladder cancers such as but not limited to transitional cell carcinoma, squamous cell cancer, adenocarcinoma, carcinosarcoma. In addition, 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). 
     Accordingly, the methods and compositions of the invention 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, Burkitt&#39;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, tetratocarcinoma, neuroblastoma and glioma; tumors of the central and peripheral nervous system, including astrocytoma, neuroblastoma, glioma, and schwannomas; tumors of mesenchymal origin, including fibrosarcoma, rhabdomyoscarama, and osteosarcoma; and other tumors, including melanoma, xeroderma pigmentosum, keratoactanthoma, seminoma, thyroid follicular cancer and teratocarcinoma. It is also contemplated that cancers caused by aberrations in apoptosis would also be treated by the methods and compositions of the invention. 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. In specific embodiments, malignancy or dysproliferative changes (such as metaplasias and dysplasias), or hyperproliferative disorders, are treated or prevented in the skin, lung, colon, breast, prostate, bladder, kidney, pancreas, ovary, or uterus. In other specific embodiments, sarcoma, melanoma, or leukemia is treated or prevented. 
     In some embodiments, the cancer is malignant and overexpresses EphA2. In other embodiments, the disorder to be treated is a pre-cancerous condition associated with cells that overexpress EphA2. In a specific embodiments, the pre-cancerous condition is high-grade prostatic intraepithelial neoplasia (PIN), fibroadenoma of the breast, fibrocystic disease, or compound nevi. 
     In specific embodiments, the methods and compositions of the invention are used for the treatment and/or prevention of breast, colon, ovarian, lung, and prostate cancers and melanoma and are provided below by example rather than by limitation. 
     5.2.1.2 Treatment of Breast Cancer 
     In specific embodiments, patients with breast cancer are administered an effective amount of one or more monoclonal antibodies of the invention. In another embodiment, the antibodies of the invention can be administered in combination with an effective amount of one or more other agents useful for breast cancer therapy including but not limited to: doxorubicin, epirubicin, the combination of doxorubicin and cyclophosphamide (AC), the combination of cyclophosphamide, doxorubicin and 5-fluorouracil (CAF), the combination of cyclophosphamide, epirubicin and 5-fluorouracil (CEF), herceptin, tamoxifen, the combination of tamoxifen and cytotoxic chemotherapy, taxanes (such as docetaxel and paclitaxel). In a further embodiment, antibodies of the invention can be administered with taxanes plus standard doxorubicin and cyclophosphamide for adjuvant treatment of node-positive, localized breast cancer. 
     In a specific embodiment, patients with pre-cancerous fibroadenoma of the breast or fibrocystic disease are administered an EphA2 antibody of the invention to treat the disorder and decrease the likelihood that it will progress to malignant breast cancer. 
     5.2.1.3 Treatment of Colon Cancer 
     In specific embodiments, patients with colon cancer are administered an effective amount of one or more monoclonal antibodies of the invention. In another embodiment, the antibodies of the invention can be administered in combination with an effective amount of one or more other agents useful for colon cancer therapy including but not limited to: the combination of 5-FU and leucovorin, the combination of 5-FU and levamisole, irinotecan (CPT-11) or the combination of irinotecan, 5-FU and leucovorin (IFL). 
     5.2.1.4 Treatment of Prostate Cancer 
     In specific embodiments, patients with prostate cancer are administered an effective amount of one or more monoclonal antibodies of the invention. In another embodiment, the antibodies of the invention can be administered in combination with an effective amount of one or more other agents useful for prostate cancer therapy including but not limited to: external-beam radiation therapy, interstitial implantation of radioisotopes (i.e., I 125 , palladium, iridium), leuprolide or other LHRH agonists, non-steroidal antiandrogens (flutamide, nilutamide, bicalutamide), steroidal antiandrogens (cyproterone acetate), the combination of leuprolide and flutamide, estrogens such as DES, chlorotrianisene, ethinyl estradiol, conjugated estrogens U.S.P., DES-diphosphate, radioisotopes, such as strontium-89, the combination of external-beam radiation therapy and strontium-89, second-line hormonal therapies such as aminoglutethimide, hydrocortisone, flutamide withdrawal, progesterone, and ketoconazole, low-dose prednisone, or other chemotherapy regimens reported to produce subjective improvement in symptoms and reduction in PSA level including docetaxel, paclitaxel, estramustine/docetaxel, estramustine/etoposide, estramustine/vinblastine, and estramustine/paclitaxel. 
     In a specific embodiment, patients with pre-cancerous high-grade prostatic intraepithelial neoplasia (PIN) are administered an EphA2 antibody of the invention to treat the disorder and decrease the likelihood that it will progress to malignant prostate cancer. 
     5.2.1.5 Treatment of Melanoma 
     In specific embodiments, patients with melanoma are administered an effective amount of one or more monoclonal antibodies of the invention. In another embodiment, the antibodies of the invention can be administered in combination with an effective amount of one or more other agents useful for melanoma cancer therapy including but not limited to: dacarbazine (DTIC), nitrosoureas such as carmustine (BCNU) and lomustine (CCNU), agents with modest single agent activity including vinca alkaloids, platinum compounds, and taxanes, the Dartmouth regimen (cisplatin, BCNU, and DTIC), interferon alpha (IFN-A), and interleukin-2 (IL-2). In a specific embodiment, an effective amount of one or more agonistic monoclonal antibodies of the invention can be administered in combination with isolated hyperthermic limb perfusion (ILP) with melphalan (L-PAM), with or without tumor necrosis factor-alpha (TNF-alpha) to patients with multiple brain metastases, bone metastases, and spinal cord compression to achieve symptom relief and some shrinkage of the tumor with radiation therapy. 
     In a specific embodiment, patients with pre-cancerous compound nevi are administered an EphA2 antibody of the invention to treat the disorder and decrease the likelihood that it will progress to malignant melanoma. 
     5.2.1.6 Treatment of Ovarian Cancer 
     In specific embodiments, patients with ovarian cancer are administered an effective amount of one or more monoclonal antibodies of the invention. In another embodiment, the antibodies of the invention can be administered in combination with an effective amount of one or more other agents useful for ovarian cancer therapy including but not limited to: intraperitoneal radiation therapy, such as P 32  therapy, total abdominal and pelvic radiation therapy, cisplatin, the combination of paclitaxel (Taxol) or docetaxel (Taxotere) and cisplatin or carboplatin, the combination of cyclophosphamide and cisplatin, the combination of cyclophosphamide and carboplatin, the combination of 5-FU and leucovorin, etoposide, liposomal doxorubicin, gemcitabine or topotecan. It is contemplated that an effective amount of one or more agonistic monoclonal antibodies of the invention is administered in combination with the administration Taxol for patients with platinum-refractory disease. Included is the treatment of patients with refractory ovarian cancer including administration of: ifosfamide in patients with disease that is platinum-refractory, hexamethylmelamine (HMM) as salvage chemotherapy after failure of cisplatin-based combination regimens, and tamoxifen in patients with detectable levels of cytoplasmic estrogen receptor on their tumors. 
     5.2.1.7 Treatment of Lung Cancers 
     In specific embodiments, patients with small lung cell cancer are administered an effective amount of one or more monoclonal antibodies of the invention. In another embodiment, the antibodies of the invention can be administered in combination with an effective amount of one or more other agents useful for lung cancer therapy including but not limited to: thoracic radiation therapy, cisplatin, vincristine, doxorubicin, and etoposide, alone or in combination, the combination of cyclophosphamide, doxorubicin, vincristine/etoposide, and cisplatin (CAV/EP), local palliation with endobronchial laser therapy, endobronchial stents, and/or brachytherapy. 
     In other specific embodiments, patients with non-small lung cell cancer are administered an effective amount of one or more monoclonal antibodies of the invention in combination with an effective amount of one or more other agents useful for lung cancer therapy including but not limited to: palliative radiation therapy, the combination of cisplatin, vinblastine and mitomycin, the combination of cisplatin and vinorelbine, paclitaxel, docetaxel or gemcitabine, the combination of carboplatin and paclitaxel, interstitial radiation therapy for endobronchial lesions or stereotactic radiosurgery. 
     5.2.2 Other Prophylactic/Therapeutic Agents. 
     In some embodiments, therapy by administration of one or more monoclonal antibodies is combined with the administration of one or more therapies such as, but not limited to, chemotherapies, radiation therapies, hormonal therapies, and/or biological therapies/immunotherapies. Prophylactic/therapeutic agents include, but are not limited to, proteinaceous molecules, including, but not limited to, peptides, polypeptides, proteins, including post-translationally modified proteins, antibodies etc.; or small molecules (less than 1000 daltons), inorganic or organic compounds; or nucleic acid molecules including, but not limited to, double-stranded or single-stranded DNA, or double-stranded or single-stranded RNA, as well as triple helix nucleic acid molecules. Prophylactic/therapeutic agents can be derived from any known organism (including, but not limited to, animals, plants, bacteria, fungi, and protista, or viruses) or from a library of synthetic molecules. 
     In a specific embodiment, the methods of the invention encompass administration of an antibody of the invention in combination with the administration of one or more prophylactic/therapeutic agents that are inhibitors of kinases such as, but not limited to, ABL, ACK, AFK, AKT (e.g., AKT-1, AKT-2, and AKT-3), ALK, AMP-PK, ATM, Aurora1, Aurora2, bARK1, bArk2, BLK, BMX, BTK, CAK, CaM kinase, CDC2, CDK, CK, COT, CTD, DNA-PK, EGF-R, ErbB-1, ErbB-2, ErbB-3, ErbB-4, ERK (e.g., ERK1, ERK2, ERK3, ERK4, ERK5, ERK6, ERK7), ERT-PK, FAK, FGR (e.g., FGFIR, FGF2R), FLT (e.g., FLT-1, FLT-2, FLT-3, FLT-4), FRK, FYN, GSK (e.g., GSK1, GSK2, GSK3-alpha, GSK3-beta, GSK4, GSK5), G-protein coupled receptor kinases (GRKs), HCK, HER2, HKII, JAK (e.g., JAK1, JAK2, JAK3, JAK4), JNK (e.g., JNK1, JNK2, JNK3), KDR, KIT, IGF-I receptor, IKK-1, IKK-2, INSR (insulin receptor), IRAK1, IRAK2, IRK, ITK, LCK, LOK, LYN, MAPK, MAPKAPK-1, MAPKAPK-2, MEK, MET, MFPK, MHCK, MLCK, MLK3, NEU, NIK, PDGF receptor alpha, PDGF receptor beta, PHK, PI-3 kinase, PKA, PKB, PKC, PKG, PRK1, PYK2, p38 kinases, p135tyk2, p34cdc2, p42cdc2, p42mapk, p44 mpk, RAF, RET, RIP, RIP-2, RK, RON, RS kinase, SRC, SYK, S6K, TAK1, TEC, TIE1, TIE2, TRKA, TXK, TYK2, UL13, VEGFR1, VEGFR2, YES, YRK, ZAP-70, and all subtypes of these kinases (see e.g., Hardie and Hanks (1995) The Protein Kinase Facts Book, I and II, Academic Press, San Diego, Calif.). In further embodiments, an antibody of the invention id administered in combination with the administration of one or more prophylactic/therapeutic agents that are inhibitors of Eph receptor kinases (e.g., EphA2, EphA4). In yet another embodiment, an antibody of the invention is administered in combination with the administration of one or more prophylactic/therapeutic agents that are inhibitors of EphA2. 
     In another specific embodiment, the methods of the invention encompass administration of an antibody of the invention in combination with the administration of one or more prophylactic/therapeutic agents that are angiogenesis inhibitors such as, but not limited to: Angiostatin (plasminogen fragment); antiangiogenic antithrombin III; Angiozyme; ABT-627; Bay 12-9566; Benefin; Bevacizumab; BMS-275291; cartilage-derived inhibitor (CDI); CA1; CD59 complement fragment; CEP-7055; Col 3; Combretastatin A-4; Endostatin (collagen XVIII fragment); fibronectin fragment; Gro-beta; Halofuiginone; Heparinases; Heparin hexasaccharide fragment; HMV833; Human chorionic gonadotropin (hCG); IM-862; Interferon alpha/beta/gamma; Interferon inducible protein (IP-10); Interleukin-12; Kringle 5 (plasminogen fragment); Marimastat; Metalloproteinase inhibitors. (TIMPs); 2-Methoxyestradiol; MMI 270 (CGS 27023A); MoAb IMC-1C11; Neovastat; NM-3; Panzem; PI-88; Placental ribonuclease inhibitor; Plasminogen activator inhibitor; Platelet factor-4 (PF4); Prinomastat; Prolactin 16 kD fragment; Proliferin-related protein (PRP); PTK 787/ZK 222594; Retinoids; Solimastat; Squalamine; SS 3304; SU 5416; SU6668; SU11248; Tetrahydrocortisol-S; tetrathiomolybdate; thalidomide; Thrombospondin-1 (TSP-1); TNP-470; Transforming growth factor-beta (TGF-β); Vasculostatin; Vasostatin (calreticulin fragment); ZD6126; ZD6474; farnesyl transferase inhibitors (FTI); and bisphosphonates. 
     In another specific embodiment, the methods of the invention encompass administration of an antibody of the invention in combination with the administration of one or more prophylactic/therapeutic agents that are anti-cancer agents such as, but not limited to: 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, cannustine, carubicin hydrochloride, carzelesin, cedefingol, chlorambucil, cirolemycin, cisplatin, cladribine, crisnatol mesylate, cyclophosphamide, cytarabine, dacarbazine, dactinomycin, daunorubicin hydrochloride, decarbazine, decitabine, dexormaplatin, dezaguanine, dezaguanine mesylate, diaziquone, docetaxel, doxorubicin, doxorubicin hydrochloride, droloxifene, droloxifene citrate, dromostanolone propionate, duazomycin, edatrexate, eflornithine hydrochloride, elsamitrucin, enloplatin, enpromate, epipropidine, epirubicin hydrochloride, erbulozole, esorubicin hydrochloride, estramustine, estramustine phosphate sodium, etanidazole, etoposide, etoposide phosphate, etoprine, fadrozole hydrochloride, fazarabine, fenretinide, floxuridine, fludarabine phosphate, fluorouracil, fluorocitabine, fosquidone, fostriecin sodium, gemcitabine, gemcitabine hydrochloride, hydroxyurea, idarubicin hydrochloride, ifosfamide, ilmofosine, interleukin 2 (including recombinant interleukin 2, or rIL2), interferon alpha-2a, interferon alpha-2b, interferon alpha-n1, interferon alpha-n3, interferon beta-I a, interferon gamma-I b, iproplatin, irinotecan hydrochloride, lanreotide acetate, letrozole, leuprolide acetate, liarozole hydrochloride, lometrexol sodium, lomustine, losoxantrone hydrochloride, masoprocol, maytansine, mechlorethamine hydrochloride, megestrol acetate, melengestrol acetate, melphalan, menogaril, mercaptopurine, methotrexate, methotrexate sodium, metoprine, meturedepa, mitindomide, mitocarcin, mitocromin, mitogillin, mitomalcin, mitomycin, mitosper, mitotane, mitoxantrone hydrochloride, mycophenolic acid, nitrosoureas, nocodazole, nogalamycin, ormaplatin, oxisuran, paclitaxel, pegaspargase, peliomycin, pentamustine, peplomycin sulfate, perfosfamide, pipobroman, piposulfan, piroxantrone hydrochloride, plicamycin, plomestane, porfimer sodium, porfiromycin, prednimustine, procarbazine hydrochloride, puromycin, puromycin hydrochloride, pyrazofurin, riboprine, rogletimide, safingol, safingol hydrochloride, semustine, simtrazene, sparfosate sodium, sparsomycin, spirogermanium hydrochloride, spiromustine, spiroplatin, streptonigrin, streptozocin, sulofenur, talisomycin, tecogalan sodium, tegafur, teloxantrone hydrochloride, temoporfin, teniposide, teroxirone, testolactone, thiamiprine, thioguanine, thiotepa, tiazofurin, tirapazamine, toremifene citrate, trestolone acetate, triciribine phosphate, trimetrexate, trimetrexate glucuronate, triptorelin, tubulozole hydrochloride, uracil mustard, uredepa, vapreotide, verteporfin, vinblastine sulfate, vincristine sulfate, vindesine, vindesine sulfate, vinepidine sulfate, vinglycinate sulfate, vinleurosine sulfate, vinorelbine tartrate, vinrosidine sulfate, vinzolidine sulfate, vorozole, zeniplatin, zinostatin, zorubicin hydrochloride. Other anti-cancer drugs include, but are not limited to: 20-epi-1,25 dihydroxyvitamin 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, antiandrogens, antiestrogens, antineoplaston, aphidicolin glycinate, apoptosis gene modulators, apoptosis regulators, apurinic acid, ara-CDP-DL-PTBA, arginine deaminase, asulacrine, atamestane, atrimustine, axinastatin 1, axinastatin 2, axinastatin 3, azasetron, azatoxin, azatyrosine, baccatin III derivatives, balanol, batimastat, BCR/ABL antagonists, benzochlorins, benzoylstaurosporine, beta lactam derivatives, beta-alethine, betaclamycin B, betulinic acid, bFGF inhibitor, bicalutamide, bisantrene, bisaziridinylspermine, bisnafide, bistratene A, bizelesin, breflate, bropirimine, budotitane, buthionine sulfoximine, calcipotriol, calphostin C, camptothecin derivatives, canarypox IL-2, capecitabine, carboxamide-amino-triazole, carboxyamidotriazole, CaRest M3, CARN 700, cartilage derived inhibitor, carzelesin, casein kinase inhibitors (ICOS), castanospermine, cecropin B, cetrorelix, chloroquinoxaline sulfonamide, cicaprost, cis-porphyrin, cladribine, clomifene analogues, clotrimazole, collismycin A, collismycin B, combretastatin A4, combretastatin analogue, conagenin, crambescidin 816, crisnatol, cryptophycin 8, cryptophycin A derivatives, curacin A, cyclopentanthraquinones, cycloplatam, cypemycin, cytarabine ocfosfate, cytolytic factor, cytostatin, dacliximab, decitabine, dehydrodidemnnin B, deslorelin, dexamethasone, dexifosfamide, dexrazoxane, dexveraparnil, diaziquone, didemnin B, didox, diethylnorspermine, dihydro-5-azacytidine, dihydrotaxol, dioxamycin, diphenyl spiromustine, docetaxel, docosanol, dolasetron, doxifluridine, droloxifene, dronabinol, duocarmycin SA, ebselen, ecomustine, edelfosine, edrecolomab, eflornithine, elemene, emitefur, epirubicin, epristeride, estramustine analogue, estrogen agonists, estrogen antagonists, etanidazole, etoposide phosphate, exemestane, fadrozole, fazarabine, fenretinide, filgrastimn, finasteride, flavopiridol, flezelastine, fluasterone, fludarabine, fluorodaunorunicin hydrochloride, forfenimex, formestane, fostriecin, fotemustine, gadolinium texaphyrin, gallium nitrate, galocitabine, ganirelix, gelatinase inhibitors, gemcitabine, glutathione inhibitors, hepsulfam, heregulin, hexamethylene bisacetamide, hypericin, ibandronic acid, idarubicin, idoxifene, idramantone, ilmofosine, ilomastat, imidazoacridones, imiquimod, immunostimulant peptides, insulin-like growth factor-1 receptor inhibitor, interferon agonists, interferons, interleukins, iobenguane, iododoxorubicin, ipomeanol, iroplact, irsogladine, isobengazole, isohomohalicondrin B, itasetron, jasplakinolide, kahalalide F, lamellarin-N triacetate, lanreotide, leinamycin, lenograstim, lentinan sulfate, leptolstatin, letrozole, leukemia inhibiting factor, leukocyte alpha interferon, leuprolide+estrogen+progesterone, leuprorelin, levamisole, liarozole, linear polyamine analogue, lipophilic disaccharide peptide, lipophilic platinum compounds, lissoclinamide 7, lobaplatin, lombricine, lometrexol, lonidamine, losoxantrone, lovastatin, loxoribine, luitotecaln, lutetium texaphyrin, lysofylline, lytic peptides, maitansine, mannostatin A, marimastat, masoprocol, maspin, matrilysin inhibitors, matrix metalloproteinase inhibitors, menogaril, merbarone, meterelin, methioninase, metoclopramide, MIF inhibitor, mifepristone, miltefosine, mirimostim, mismatched double stranded RNA, mitoguazone, mitolactol, mitomycin analogues, mitonafide, mitotoxin fibroblast growth factor-saporin, mitoxantrone, mofarotene, molgramostim, monoclonal antibody, human chorionic gonadotrophin, monophosphoryl lipid A+myobacterium cell wall sk, mopidamol, multiple drug resistance gene inhibitor, multiple tumor suppressor 1-based therapy, mustard anticancer agent, mycaperoxide B, mycobacterial cell wall extract, myriaporone, N-acetyldinaline, N-substituted benzamides, nafarelin, nagrestip, naloxone+pentazocine, napavin, naphterpin, nartograstim, nedaplatin, nemorubicin, neridronic acid, neutral endopeptidase, nilutamide, nisarnycin, nitric oxide modulators, nitroxide antioxidant, nitrullyn, O6-benzylguanine, octreotide, okicenone, oligonucleotides, onapristone, ondansetron, ondansetron, oracin, oral cytokine inducer, ormaplatin, osaterone, oxaliplatin, oxaunomycin, paclitaxel, paclitaxel analogues, paclitaxel derivatives, palauamine, palmitoylrhizoxin, pamidronic acid, panaxytriol, panomifene, parabactin, pazelliptine, pegaspargase, peldesine, pentosan polysulfate sodium, pentostatin, pentrozole, perflubron, perfosfamide, perillyl alcohol, phenazinomycin, phenylacetate, phosphatase inhibitors, picibanil, pilocarpine hydrochloride, pirarubicin, piritrexim, placetin A, placetin B, plasminogen activator inhibitor, platinum complex, platinum compounds, platinum-triamine complex, porfimer sodium, porfiromycin, prednisone, propyl bis-acridone, prostaglandin J2, proteasome inhibitors, protein A-based immune modulator, protein kinase C inhibitor, protein kinase C inhibitors, microalgal, protein tyrosine phosphatase inhibitors, purine nucleoside phosphorylase inhibitors, purpurins, pyrazoloacridine, pyridoxylated hemoglobin polyoxyethylene conjugate, raf antagonists, raltitrexed, ramosetron, ras farnesyl protein transferase inhibitors, ras inhibitors, ras-GAP inhibitor, retelliptine demethylated, rhenium Re 186 etidronate, rhizoxin, ribozymes, RII retinamide, rogletimide, rohitukine, romurtide, roquinimex, rubiginone B1, ruboxyl, safingol, saintopin, SarCNU, sarcophytol A, sargramostim, Sdi 1 mimetics, semustine, senescence derived inhibitor 1, sense oligonucleotides, signal transduction inhibitors, signal transduction modulators, single chain antigen binding protein, sizofiran, sobuzoxane, sodium borocaptate, sodium phenylacetate, solverol, somatomedin binding protein, soneinin, sparfosic acid, spicamycin D, spiromustine, splenopentin, spongistatin 1, squalamine, stem cell inhibitor, stem-cell division inhibitors, stipiamide, stromelysin inhibitors, sulfinosine, superactive vasoactive intestinal peptide antagonist, suradista, suramin, swainsonine, synthetic glycosaminoglycans, tallimustine, tamoxifen methiodide, tauromustine, taxol, tazarotene, tecogalan sodium, tegafur, tellurapyrylium, telomerase inhibitors, temoporfin, temozolomide, teniposide, tetrachlorodecaoxide, tetrazomine, thaliblastine, thalidomide, thiocoraline, thioguanine, thrombopoietin, thrombopoietin mimetic, thymalfasin, thymopoietin receptor agonist, thymotrinan, thyroid stimulating hormone, tin ethyl etiopurpurin, tirapazamine, titanocene bichloride, topsentin, toremifene, totipotent stem cell factor, translation inhibitors, tretinoin, triacetyluridine, triciribine, trimetrexate, triptorelin, tropisetron, turosteride, tyrosine kinase inhibitors, tyrphostins, UBC inhibitors, ubenimex, urogenital sinus-derived growth inhibitory factor, urokinase receptor antagonists, vapreotide, variolin B, vector system, erythrocyte gene therapy, velaresol, veramine, verdins, velteporfin, vinqrelbine, vinxaltine, vitaxin, vorozole, zanoterone, zeniplatin, zilascorb, and zinostatin stimalamer. Preferred additional anti-cancer drugs are 5-fluorouracil and leucovorin. 
     In more particular embodiments, the present invention also comprises the administration of one or more monoclonal antibodies of the invention in combination with the administration of one or more therapies such as, but not limited to anti-cancer agents such as those disclosed in Table 2, preferably for the treatment of breast, ovary, melanoma, prostate, colon and lung cancers as described above. 
     
       
         
           
               
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                 Therapeutic Agent 
                 Administration 
                 Dose 
                 Intervals 
               
               
                   
               
             
            
               
                 doxorubicin 
                 Intravenous 
                 60-75 mg/m 2  on Day 1 
                 21 day intervals 
               
               
                 hydrochloride 
               
               
                 (Adriamycin RDF ® 
               
               
                 and Adriamycin 
               
               
                 PFS ®) 
               
               
                 epirubicin 
                 Intravenous 
                 100-120 mg/m 2  on Day 1 of 
                 3-4 week cycles 
               
               
                 hydrochloride 
                   
                 each cycle or divided equally 
               
               
                 (Ellence ™) 
                   
                 and given on Days 1-8 of the 
               
               
                   
                   
                 cycle 
               
               
                 fluorousacil 
                 Intravenous 
                 How supplied: 
               
               
                   
                   
                 5 ml and 10 ml vials 
               
               
                   
                   
                 (containing 250 and 500 mg 
               
               
                   
                   
                 flourouracil respectively) 
               
               
                 docetaxel 
                 Intravenous 
                 60-100 mg/m 2  over 1 hour 
                 Once every 3 weeks 
               
               
                 (Taxotere ®) 
               
               
                 paclitaxel 
                 Intravenous 
                 175 mg/m 2  over 3 hours 
                 Every 3 weeks for 4 courses 
               
               
                 (Taxol ®) 
                   
                   
                 (administered sequentially to 
               
               
                   
                   
                   
                 doxorubicin-containing 
               
               
                   
                   
                   
                 combination chemotherapy) 
               
               
                 tamoxifen citrate 
                 Oral 
                 20-40 mg 
                 Daily 
               
               
                 (Nolvadex ®) 
                 (tablet) 
                 Dosages greater than 20 mg 
               
               
                   
                   
                 should be given in divided 
               
               
                   
                   
                 doses (morning and evening) 
               
               
                 leucovorin calcium 
                 Intravenous or 
                 How supplied: 
                 Dosage is unclear from text. 
               
               
                 for injection 
                 intramuscular 
                 350 mg vial 
                 PDR 3610 
               
               
                   
                 injection 
               
               
                 luprolide acetate 
                 Single 
                 1 mg (0.2 ml or 20 unit mark) 
                 Once a day 
               
               
                 (Lupron ®) 
                 subcutaneous 
               
               
                   
                 injection 
               
               
                 flutamide 
                 Oral 
                 250 mg 
                 3 times a day at 8 hour 
               
               
                 (Eulexin ®) 
                 (capsule) 
                 (capsules contain 125 mg 
                 intervals (total daily dosage 
               
               
                   
                   
                 flutamide each) 
                 750 mg) 
               
               
                 nilutamide 
                 Oral 
                 300 mg or 150 mg 
                 300 mg once a day for 30 
               
               
                 (Nilandron ®) 
                 (tablet) 
                 (tablets contain 50 or 150 mg 
                 days followed by 150 mg 
               
               
                   
                   
                 nilutamide each) 
                 once a day 
               
               
                 bicalutamide 
                 Oral 
                 50 mg 
                 Once a day 
               
               
                 (Casodex ®) 
                 (tablet) 
                 (tablets contain 50 mg 
               
               
                   
                   
                 bicalutamide each) 
               
               
                 progesterone 
                 Injection 
                 USP in sesame oil 50 mg/ml 
               
               
                 ketoconazole 
                 Cream 
                 2% cream applied once or 
               
               
                 (Nizoral ®) 
                   
                 twice daily depending on 
               
               
                   
                   
                 symptoms 
               
               
                 prednisone 
                 Oral 
                 Initial dosage may vary from 
               
               
                   
                 (tablet) 
                 5 mg to 60 mg per day 
               
               
                   
                   
                 depending on the specific 
               
               
                   
                   
                 disease entity being treated. 
               
               
                 estramustine 
                 Oral 
                 14 mg/kg of body weight 
                 Daily given in 3 or 4 divided 
               
               
                 phosphate sodium 
                 (capsule) 
                 (i.e. one 140 mg capsule for 
                 doses 
               
               
                 (Emcyt ®) 
                   
                 each 10 kg or 22 lb of body 
               
               
                   
                   
                 weight) 
               
               
                 etoposide or VP-16 
                 Intravenous 
                 5 ml of 20 mg/ml solution 
               
               
                   
                   
                 (100 mg) 
               
               
                 dacarbazine 
                 Intravenous 
                 2-4.5 mg/kg 
                 Once a day for 10 days. 
               
               
                 (DTIC-Dome ®) 
                   
                   
                 May be repeated at 4 week 
               
               
                   
                   
                   
                 intervals 
               
               
                 polifeprosan 20 with 
                 wafer placed in 
                 8 wafers, each containing 7.7 
               
               
                 carmustine implant 
                 resection cavity 
                 mg of carmustine, for a total 
               
               
                 (BCNU) (nitrosourea) 
                   
                 of 61.6 mg, if size and shape 
               
               
                 (Gliadel ®) 
                   
                 of resection cavity allows 
               
               
                 cisplatin 
                 Injection 
                 [n/a in PDR 861] 
               
               
                   
                   
                 How supplied: 
               
               
                   
                   
                 solution of 1 mg/ml in multi- 
               
               
                   
                   
                 dose vials of 50 mL and 
               
               
                   
                   
                 100 mL 
               
               
                 mitomycin 
                 Injection 
                 supplied in 5 mg and 20 mg 
               
               
                   
                   
                 vials (containing 5 mg and 20 
               
               
                   
                   
                 mg mitomycin) 
               
               
                 gemcitabine HCl 
                 Intravenous 
                 For NSCLC- 2 schedules 
                 4 week schedule- 
               
               
                 (Gemzar ®) 
                   
                 have been investigated and 
                 Days 1, 8 and 15 of each 28- 
               
               
                   
                   
                 the optimum schedule has not 
                 day cycle. Cisplatin 
               
               
                   
                   
                 been determined 
                 intravenously at 100 mg/m 2   
               
               
                   
                   
                 4 week schedule- 
                 on day 1 after the infusion of 
               
               
                   
                   
                 administration intravenously 
                 Gemzar. 
               
               
                   
                   
                 at 1000 mg/m 2  over 30 
                 3 week schedule- 
               
               
                   
                   
                 minutes on 3 week schedule- 
                 Days 1 and 8 of each 21 day 
               
               
                   
                   
                 Gemzar administered 
                 cycle. Cisplatin at dosage of 
               
               
                   
                   
                 intravenously at 1250 mg/m 2   
                 100 mg/m 2  administered 
               
               
                   
                   
                 over 30 minutes 
                 intravenously after 
               
               
                   
                   
                   
                 administration of Gemzar on 
               
               
                   
                   
                   
                 day 1. 
               
               
                 carboplatin 
                 Intravenous 
                 Single agent therapy: 
                 Every 4 weeks 
               
               
                 (Paraplatin ®) 
                   
                 360 mg/m 2  I.V. on day 1 
               
               
                   
                   
                 (infusion lasting 15 minutes 
               
               
                   
                   
                 or longer) 
               
               
                   
                   
                 Other dosage calculations: 
               
               
                   
                   
                 Combination therapy with 
               
               
                   
                   
                 cyclophosphamide, Dose 
               
               
                   
                   
                 adjustment recommendations, 
               
               
                   
                   
                 Formula dosing, etc. 
               
               
                 ifosamide 
                 Intravenous 
                 1.2 g/m 2  daily 
                 5 consecutive days 
               
               
                 (Ifex ®) 
                   
                   
                 Repeat every 3 weeks or 
               
               
                   
                   
                   
                 after recovery from 
               
               
                   
                   
                   
                 hematologic toxicity 
               
               
                 topotecan 
                 Intravenous 
                 1.5 mg/m 2  by intravenous 
                 5 consecutive days, starting 
               
               
                 hydrochloride 
                   
                 infusion over 30 minutes 
                 on day 1 of 21 day course 
               
               
                 (Hycamtin ®) 
                   
                 daily 
               
               
                   
               
            
           
         
       
     
     The invention also encompasses administration of the EphA2 antibodies of the invention in combination with radiation therapy comprising the use of x-rays, gamma rays and other sources of radiation to destroy the cancer cells. In further embodiments, the radiation treatment is administered as external beam radiation or teletherapy wherein the radiation is directed from a remote source. In other embodiments, the radiation treatment is administered as internal therapy or brachytherapy wherein a radioactive source is placed inside the body close to cancer cells or a tumor mass. 
     Cancer therapies and their dosages, routes of administration and recommended usage are known in the art and have been described in such literature as the  Physicians&#39; Desk Reference  (58 th  ed., 2004). 
     5.3 Identification of Antibodies of the Invention 
     5.3.1 Agonistic Antibodies 
     Antibodies of the invention may preferably agonize (i.e., elicit EphA2 phosphorylation) as well as specifically bind to the EphA2 receptor. When agonized, EphA2 becomes phosphorylated and then subsequently degraded. Any method known in the art to assay either the level of EphA2 phosphorylation, activity, or expression can be used to assay candidate EphA2 antibodies to determine their agonistic activity (see, e.g., Section 6.2.1 infra). 
     Thus, the invention provides methods of assaying and screening for EphA2 antibodies of the invention by incubating antibodies that specifically bind EphA2, particularly that bind the extracellular domain of EphA2, with cells that express EphA2, particularly cancer cells, preferably metastatic cancer cells, that overexpress EphA2 (relative to non-cancer cells of the same cell type) and then assaying for an increase in EphA2 phosphorylation and/or EphA2 degradation, thereby identifying an EphA2 antibody of the invention. 
     5.3.2 Antibodies that Preferentially Bind EphA2 Epitopes Exposed on Cancer Cells 
     Antibodies of the invention may preferably bind to EphA2 epitopes exposed on cancer cells (e.g., cells overexpressing EphA2 and/or cells with substantial EphA2 that is not bound to ligand) but not non-cancer cells or cell where EphA2 is bound to ligand. In this embodiment, antibodies of the invention are antibodies directed to an EphA2 epitope not exposed on non-cancer cells but exposed on cancer cells (see, e.g., Section 6.6 infra). Differences in EphA2 membrane distribution between non-cancer cells and cancer cells expose certain epitopes on cancer cells that are not exposed on non-cancer cells. For example, normally EphA2 is bound to its ligand, EphrinA1, and localizes at areas of cell-cell contacts. However, cancer cells generally display decreased cell-cell contacts as well as overexpress EphA2 in excess of its ligand. Thus, in cancer cells, there is an increased amount of unbound EphA2 that is not localized to cell-cell contacts. As such, in one embodiment, an antibody that preferentially binds unbound, unlocalized EphA2 is an antibody of the invention. 
     Any method known in the art to determine candidate EphA2 antibody binding/localization on a cell can be used to screen candidate antibodies for desirable binding properties. In a one embodiment, immunofluorescence microscopy is used to determine the binding characteristics of an antibody. Standard techniques can be used to compare the binding of an antibody binding to cells grown in vitro. In a specific embodiment, antibody binding to cancer cells is compared to antibody binding to non-cancer cells. An exposed EphA2 epitope antibody binds poorly to non-cancer cells but binds well to cancer cells. In another specific embodiment, antibody binding to non-cancer dissociated cells (e.g., treated with a calcium chelator such as EGTA) is compared to antibody binding to non-cancer cells that have not been dissociated. An exposed EphA2 epitope antibody binds poorly non-cancer cells that have not been dissociated but binds well to dissociated non-cancer cells. 
     In another embodiment, flow cytometry is used to determine the binding characteristics of an antibody. In this embodiment, EphA2 may or may not be crosslinked to its ligand, Ephrin A1. An exposed EphA2 epitope antibody binds poorly crosslinked EphA2 but binds well to uncrosslinked EphA2. 
     In another embodiment, cell-based or immunoassays are used to determine the binding characteristics of an antibody. In this embodiment, antibodies that can compete with an EphA2 ligand (e.g., Ephrin A1) for binding to EphA2 displace Ephrin A1 from EphA2. The EphA2 ligand used in this assay can be soluble protein (e.g., recombinantly expressed) or expressed on a cell so that it is anchored to the cell. 
     5.4 Characterization and Demonstration of Therapeutic or Prophylactic Utility 
     Toxicity and efficacy of the prophylactic and/or therapeutic protocols of the instant invention can be determined by standard pharmaceutical procedures in cell cultures or experimental animals, e.g., for determining the LD 50  (the dose lethal to 50% of the population) and the ED 50  (the dose therapeutically effective in 50% of the population). The dose ratio between toxic and therapeutic effects is the therapeutic index and it can be expressed as the ratio LD 50 /ED 50 . Prophylactic and/or therapeutic agents that exhibit large therapeutic indices are preferred. While prophylactic and/or therapeutic agents that exhibit toxic side effects may be used, care should be taken to design a delivery system that targets such agents to the site of affected tissue in order to minimize potential damage to uninfected cells and, thereby, reduce side effects. 
     The data obtained from the cell culture assays and animal studies can be used in formulating a range of dosage of the prophylactic and/or therapeutic agents for use in humans. The dosage of such agents lies preferably within a range of circulating concentrations that include the ED 50  with little or no toxicity. The dosage may vary within this range depending upon the dosage form employed and the route of administration utilized. For any agent used in the method of the invention, the therapeutically effective dose can be estimated initially from cell culture assays. A dose may be formulated in animal models to achieve a circulating plasma concentration range that includes the IC 50  (i.e., the concentration of the test compound that achieves a half-maximal inhibition of symptoms) as determined in cell culture. Such information can be used to more accurately determine useful doses in humans. Levels in plasma may be measured, for example, by high performance liquid chromatography. 
     The anti-cancer activity of the therapies used in accordance with the present invention also can be determined by using various experimental animal models for the study of cancer such as the SCID mouse model or transgenic mice where a mouse EphA2 is replaced with the human EphA2, nude mice with human xenografts, animal models described in Section 6 infra, or any animal model (including hamsters, rabbits, etc.) known in the art and described in  Relevance of Tumor Models for Anticancer Drug Development  (1999, eds. Fiebig and Burger);  Contributions to Oncology  (1999, Karger);  The Nude Mouse in Oncology Research  (1991, eds. Boven and Winograd); and  Anticancer Drug Development Guide  (1997 ed. Teicher), herein incorporated by reference in their entireties. 
     5.4.1 Demonstration of Therapeutic Utility 
     The protocols and compositions of the invention are preferably tested in vitro, and then in vivo, for the desired therapeutic or prophylactic activity, prior to use in humans. For example, in vitro assays which can be used to determine whether administration of a specific therapeutic protocol is indicated, include in vitro cell culture assays in which a patient tissue sample is grown in culture, and exposed to or otherwise administered a protocol, and the effect of such protocol upon the tissue sample is observed, e.g., increased phosphorylation/degradation of EphA2. A lower level of proliferation or survival of the contacted cells indicates that the therapeutic agent is effective to treat the condition in the patient. Alternatively, instead of culturing cells from a patient, therapeutic agents and methods may be screened using cells of a tumor or malignant cell line. Many assays standard in the art can be used to assess such survival and/or growth; for example, cell proliferation can be assayed by measuring  3 H-thymidine incorporation, by direct cell count, by detecting changes in transcriptional activity of known genes such as proto-oncogenes (e.g., fos, myc) or cell cycle markers; cell viability can be assessed by trypan blue staining, differentiation can be assessed visually based on changes in morphology, increased phosphorylation/degradation of EphA2, etc. 
     Compounds for use in therapy can be tested in suitable animal model systems prior to testing in humans, including but not limited to in rats, mice, chicken, cows, monkeys, rabbits, hamsters, etc., for example, the animal models described above. The compounds can then be used in the appropriate clinical trials. 
     Further, any assays known to those skilled in the art can be used to evaluate the prophylactic and/or therapeutic utility of the combinatorial therapies disclosed herein for treatment or prevention of cancer. 
     5.5 Pharmaceutical Compositions 
     The compositions of the invention include bulk drug compositions useful in the manufacture of pharmaceutical compositions (e.g., impure or non-sterile compositions) and pharmaceutical compositions (i.e., compositions that are suitable for administration to a subject or patient) which can be used in the preparation of unit dosage forms. Such compositions comprise a prophylactically or therapeutically effective amount of a prophylactic and/or therapeutic agent disclosed herein or a combination of those agents and a pharmaceutically acceptable carrier. Preferably, compositions of the invention comprise a prophylactically or therapeutically effective amount of one or more EphA2 antibodies of the invention and a pharmaceutically acceptable carrier. In a further embodiment, the composition of the invention further comprises an additional anti-cancer agent. In a specific embodiment, additional anti-cancer agent include, but are not limited to, chemotherapeutic agents, radiation therapeutic agents, hormonal therapeutic agents, biological therapeutics and immunotherapeutic agents. 
     In a specific embodiment, the term “pharmaceutically acceptable” means approved by a regulatory agency of the Federal or a state government or listed in the U.S. Pharmacopeia or other generally recognized pharmacopeia for use in animals, and more particularly in humans. The term “carrier” refers to a diluent, adjuvant (e.g., Freund&#39;s adjuvant (complete and incomplete) or, more preferably, MF59C.1 adjuvant available from Chiron, Emeryville, Calif.), excipient, or vehicle with which the therapeutic is administered. Such pharmaceutical carriers can be sterile liquids, such as water and oils, including those of petroleum, animal, vegetable or synthetic origin, such as peanut oil, soybean oil, mineral oil, sesame oil and the like. Water is a preferred carrier when the pharmaceutical composition is administered intravenously. Saline solutions and aqueous dextrose and glycerol solutions can also be employed as liquid carriers, particularly for injectable solutions. Suitable pharmaceutical excipients include starch, glucose, lactose, sucrose, gelatin, malt, rice, flour, chalk, silica gel, sodium stearate, glycerol monostearate, talc, sodium chloride, dried skim milk, glycerol, propylene, glycol, water, ethanol and the like. The composition, if desired, can also contain minor amounts of wetting or emulsifying agents, or pH buffering agents. These compositions can take the form of solutions, suspensions, emulsion, tablets, pills, capsules, powders, sustained-release formulations and the like. 
     Generally, the ingredients of compositions of the invention are supplied either separately or mixed together in unit dosage form, for example, as a dry lyophilized powder or water free concentrate in a hermetically sealed container such as an ampoule or sachette indicating the quantity of active agent. Where the composition is to be administered by infusion, it can be dispensed with an infusion bottle containing sterile pharmaceutical grade water or saline. Where the composition is administered by injection, an ampoule of sterile water for injection or saline can be provided so that the ingredients may be mixed prior to administration. 
     The compositions of the invention can be formulated as neutral or salt forms. Pharmaceutically acceptable salts include those formed with anions such as those derived from hydrochloric, phosphoric, acetic, oxalic, tartaric acids, etc., and those formed with cations such as those derived from sodium, potassium, ammonium, calcium, ferric hydroxides, isopropylamine, triethylamine, 2-ethylamino ethanol, histidine, procaine, etc. 
     Various delivery systems are known and can be used to administer an agonistic monoclonal antibody of the invention or the combination of an agonistic monoclonal antibody of the invention and a prophylactic agent or therapeutic agent useful for preventing or treating cancer, e.g., encapsulation in liposomes, microparticles, microcapsules, recombinant cells capable of expressing the antibody or antibody fragment, receptor-mediated endocytosis (see, e.g., Wu and Wu, 1987 , J. Biol. Chem.  262:4429-4432), construction of a nucleic acid as part of a retroviral or other vector, etc. Methods of administering a prophylactic or therapeutic agent of the invention include, but are not limited to, parenteral administration (e.g., intradermal, intramuscular, intraperitoneal, intravenous and subcutaneous), epidural, and mucosal (e.g., intranasal, inhaled, and oral routes). In a specific embodiment, prophylactic or therapeutic agents of the invention are administered intramuscularly, intravenously, or subcutaneously. The prophylactic or therapeutic agents may be administered by any convenient route, for example by infusion or bolus injection, by absorption through epithelial or mucocutaneous linings (e.g., oral mucosa, rectal and intestinal mucosa, etc.) and may be administered together with other biologically active agents. Administration can be systemic or local. 
     In a specific embodiment, it may be desirable to administer the prophylactic or therapeutic agents of the invention locally to the area in need of treatment; this may be achieved by, for example, and not by way of limitation, local infusion, by injection, or by means of an implant, said implant being of a porous, non-porous, or gelatinous material, including membranes, such as sialastic membranes, or fibers. 
     In yet another embodiment, the prophylactic or therapeutic agent can be delivered in a controlled release or sustained release system. In one embodiment, a pump may be used to achieve controlled or sustained release (see Langer, supra; Sefton, 1987 , CRC Crit. Ref. Biomed. Eng.  14:20; Buchwald et al., 1980 , Surgery  88:507; Saudek et al., 1989 , M. Engl. J. Med.  321:574). In another embodiment, polymeric materials can be used to achieve controlled or sustained release of the antibodies of the invention or fragments thereof (see e.g., Medical Applications of Controlled Release, Langer and Wise (eds.), CRC Pres., Boca Raton, Fla. (1974); Controlled Drug Bioavailability, Drug Product Design and Performance, Smolen and Ball (eds.), Wiley, New York (1984); Ranger and Peppas, 1983 , J. Macromol. Sci. Rev. Macromol. Chem.  23:61; see also Levy et al., 1985 , Science  228:190; During et al., 1989 , Ann. Neurol.  25:351; Howard et al., 1989 , J. Neurosurg.  7 1:105); U.S. Pat. Nos. 5,679,377; 5,916,597; 5,912,015; 5,989,463; 5,128,326; International Publication Nos. WO 99/15154 and WO 99/20253. Examples of polymers used in sustained release formulations include, but are not limited to, poly(2-hydroxy ethyl methacrylate), poly(methyl methacrylate), poly(acrylic acid), poly(ethylene-co-vinyl acetate), poly(methacrylic acid), polyglycolides (PLG), polyanhydrides, poly(N-vinyl pyrrolidone), poly(vinyl alcohol), polyacrylamide, poly(ethylene glycol), polylactides (PLA), poly(lactide-co-glycolides) (PLGA), and polyorthoesters. In a further embodiment, the polymer used in a sustained release formulation is inert, free of leachable impurities, stable on storage, sterile, and biodegradable. In yet another embodiment, a controlled or sustained release system can be placed in proximity of the prophylactic or therapeutic target, thus requiring only a fraction of the systemic dose (see, e.g., Goodson, in Medical Applications of Controlled Release, supra, vol. 2, pp. 115-138 (1984)). 
     Controlled release systems are discussed in the review by Langer (1990, Science 249:1527-1533). Any technique known to one of skill in the art can be used to produce sustained release formulations comprising one or more therapeutic agents of the invention. See, e.g., U.S. Pat. No. 4,526,938; International Publication Nos. WO 91/05548 and WO 96/20698; Ning et al., 1996 , Radiotherapy  &amp;  Oncology  39:179-189; Song et al., 1995 , PDA Journal of Pharmaceutical Science  &amp;  Technology  50:372-397; Cleek et al., 1997 , Pro. Int&#39;l. Symp. Control. Rel. Bioact. Mater.  24:853-854; and Lam et al., 1997 , Proc. Int&#39;l. Symp. Control Rel. Bioact. Mater.  24:759-760, each of which is incorporated herein by reference in its entirety. 
     5.5.1 Formulations 
     Pharmaceutical compositions for use in accordance with the present invention may be formulated in conventional manner using one or more physiologically acceptable carriers or excipients. 
     Thus, the EphA2 antibodies of the invention and their physiologically acceptable salts and solvates may be formulated for administration by inhalation or insufflation (either through the mouth or the nose) or oral, parenteral or mucosal (such as buccal, vaginal, rectal, sublingual) administration. In a further embodiment, local or systemic parenteral administration is used. 
     For oral administration, the pharmaceutical compositions may take the form of, for example, tablets or capsules prepared by conventional means with pharmaceutically acceptable excipients such as binding agents (e.g., pregelatinised maize starch, polyvinylpyrrolidone or hydroxypropyl methylcellulose); fillers (e.g., lactose, microcrystalline cellulose or calcium hydrogen phosphate); lubricants (e.g., magnesium stearate, talc or silica); disintegrants (e.g., potato starch or sodium starch glycolate); or wetting agents (e.g., sodium lauryl sulphate). The tablets may be coated by methods well known in the art. Liquid preparations for oral administration may take the form of, for example, solutions, syrups or suspensions, or they may be presented as a dry product for constitution with water or other suitable vehicle before use. Such liquid preparations may be prepared by conventional means with pharmaceutically acceptable additives such as suspending agents (e.g., sorbitol syrup, cellulose derivatives or hydrogenated edible fats); emulsifying agents (e.g., lecithin or acacia); non-aqueous vehicles (e.g., almond oil, oily esters, ethyl alcohol or fractionated vegetable oils); and preservatives (e.g., methyl or propyl-p-hydroxybenzoates or sorbic acid). The preparations may also contain buffer salts, flavoring, coloring and sweetening agents as appropriate. 
     Preparations for oral administration may be suitably formulated to give controlled release of the active compound. 
     For buccal administration the compositions may take the form of tablets or lozenges formulated in conventional manner. 
     For administration by inhalation, the prophylactic or therapeutic agents for use according to the present invention are conveniently delivered in the form of an aerosol spray presentation from pressurized packs or a nebulizer, with the use of a suitable propellant, e.g., dichlorodifluoromethane, trichlorofluoromethane, dichlorotetrafluoroethane, carbon dioxide or other suitable gas. In the case of a pressurized aerosol the dosage unit may be determined by providing a valve to deliver a metered amount. Capsules and cartridges of e.g., gelatin for use in an inhaler or insufflator may be formulated containing a powder mix of the compound and a suitable powder base such as lactose or starch. 
     The prophylactic or therapeutic agents may be formulated for parenteral administration by injection, e.g., by bolus injection or continuous infusion. Formulations for injection may be presented in unit dosage form, e.g., in ampoules or in multi-dose containers, with an added preservative. The compositions may take such forms as suspensions, solutions or emulsions in oily or aqueous vehicles, and may contain formulatory agents such as suspending, stabilizing and/or dispersing agents. Alternatively, the active ingredient may be in powder form for constitution with a suitable vehicle, e.g., sterile pyrogen-free water, before use. 
     The prophylactic or therapeutic agents may also be formulated in rectal compositions such as suppositories or retention enemas, e.g., containing conventional suppository bases such as cocoa butter or other glycerides. 
     In addition to the formulations described previously, the prophylactic or therapeutic agents may also be formulated as a depot preparation. Such long acting formulations may be administered by implantation (for example subcutaneously or intramuscularly) or by intramuscular injection. Thus, for example, the prophylactic or therapeutic agents may be formulated with suitable polymeric or hydrophobic materials (for example as an emulsion in an acceptable oil) or ion exchange resins, or as sparingly soluble derivatives, for example, as a sparingly soluble salt. 
     The invention also provides that a prophylactic or therapeutic agent is packaged in a hermetically sealed container such as an ampoule or sachette indicating the quantity. In one embodiment, the prophylactic or therapeutic agent is supplied as a dry sterilized lyophilized powder or water free concentrate in a hermetically sealed container and can be reconstituted, e.g., with water or saline to the appropriate concentration for administration to a subject. 
     In a further embodiment of the invention, the formulation and administration of various chemotherapeutic, biological/immunotherapeutic and hormonal therapeutic agents are known in the art and often described in the  Physicians&#39; Desk Reference , (58 th  ed., 2004). The typical doses of various cancer therapeutics known in the art are provided in Table 2. 
     In other embodiments of the invention, radiation therapy agents such as radioactive isotopes can be given orally as liquids in capsules or as a drink. Radioactive isotopes can also be formulated for intravenous injections. The skilled oncologist can determine the preferred formulation and route of administration. 
     In certain embodiments the agonistic monoclonal antibodies of the invention, are formulated at 1 mg/ml, 5 mg/ml, 10 mg/ml, 25 mg/ml, and 50 mg/ml for intravenous injections and at 5 mg/ml, 10 mg/ml, and 80 mg/ml for repeated subcutaneous administration and intramuscular injection. In other embodiments the agonistic monoclonal antibodies of the invention are formulated at between about 0.1 mg/ml and about 1 mg/ml, between about 1 mg/ml and about 5 mg/ml, between about 5 mg/ml and about 10 mg/ml, between about 10 mg/ml and about 25 mg/ml, and between about 25 mg/ml and about 50 mg/ml. 
     The compositions may, if desired, be presented in a pack or dispenser device that may contain one or more unit dosage forms containing the active ingredient. The pack may for example comprise metal or plastic foil, such as a blister pack. The pack or dispenser device may be accompanied by instructions for administration. 
     5.5.2 Dosages 
     The amount of the composition of the invention which will be effective in the treatment, prevention or management of cancer can be determined by standard research techniques. For example, the dosage of the composition which will be effective in the treatment, prevention or management of cancer can be determined by administering the composition to an animal model such as, e.g., the animal models disclosed herein or known to those skilled in the art. In addition, in vitro assays may optionally be employed to help identify optimal dosage ranges. 
     Selection of the preferred effective dose can be determined (e.g., via clinical trials) by a skilled artisan based upon the consideration of several factors which will be known to one of ordinary skill in the art. Such factors include the disease to be treated or prevented, the symptoms involved, the patient&#39;s body mass, the patient&#39;s immune status and other factors known by the skilled artisan to reflect the accuracy of administered pharmaceutical compositions. 
     The precise dose to be employed in the formulation will also depend on the route of administration, and the seriousness of the cancer, and should be decided according to the judgment of the practitioner and each patient&#39;s circumstances. Effective doses may be extrapolated from dose-response curves derived from in vitro or animal model test systems. 
     For antibodies, the dosage administered to a patient is typically 0.0001 mg/kg to 100 mg/kg of the patient&#39;s body weight. Preferably, the dosage administered to a patient is between 0.0001 mg/kg and 20 mg/kg, 0.0001 mg/kg and 10 mg/kg, 0.0001 mg/kg and 5 mg/kg, 0.0001 and 2 mg/kg, 0.0001 and 1 mg/kg, 0.0001 mg/kg and 0.75 mg/kg, 0.0001 mg/kg and 0.5 mg/kg, 0.0001 mg/kg to 0.25 mg/kg, 0.0001 to 0.15 mg/kg, 0.0001 to 0.10 mg/kg, 0.001 to 0.5 mg/kg, 0.01 to 0.25 mg/kg, or 0.01 to 0.10 mg/kg of the patient&#39;s body weight. Generally, human and humanized antibodies have a longer half-life within the human body than antibodies from other species due to the immune response to the foreign polypeptides. Thus, lower dosages of human antibodies and less frequent administration is often possible. 
     For other cancer therapeutic agents administered to a patient, the typical doses of various cancer therapeutics known in the art are provided in Table 2. Given the invention, certain embodiments will encompass the administration of lower dosages in combination treatment regimens than dosages recommended for the administration of single agents. 
     The invention provides for any method of administrating lower doses of known prophylactic or therapeutic agents than previously thought to be effective for the prevention, treatment, management or amelioration of cancer. In certain embodiments, lower doses of known anti-cancer therapies are administered in combination with lower doses of agonistic monoclonal antibodies of the invention. 
     5.6 Kits 
     The invention provides a pharmaceutical pack or kit comprising one or more containers filled with an EphA2 antibody of the invention. Additionally, one or more other prophylactic or therapeutic agents useful for the treatment of a cancer can also be included in the pharmaceutical pack or kit. The invention also provides a pharmaceutical pack or kit comprising one or more containers filled with one or more of the ingredients of the pharmaceutical compositions of the invention. Optionally associated with such container(s) can be a notice in the form prescribed by a governmental agency regulating the manufacture, use or sale of pharmaceuticals or biological products, which notice reflects approval by the agency of manufacture, use or sale for human administration. 
     The present invention provides kits that can be used in the above methods. In one embodiment, a kit comprises one or more EphA2 antibodies of the invention. In another embodiment, a kit further comprises one or more other prophylactic or therapeutic agents useful for the treatment of cancer, in one or more containers. In certain embodiments the EphA2 antibody of the invention is 2A4, 2E7, or 12E2. In further embodiments, the other prophylactic or therapeutic agent is a chemotherapeutic. In other embodiments, the prophylactic or therapeutic agent is a biological or hormonal therapeutic. 
     6. EXAMPLES 
     Affinity Optimization of the Humanized Anti-Human EphA2 Monoclonal Antibody 4H5 
     Reagents 
     All chemicals were of analytical grade. Restriction enzymes and DNA-modifying enzymes, and T4 ligase and T7 DNA polymerase were purchased from New England Biolabs, Inc. (Beverly, Mass.). Custom oligonucleotides were synthesized from Invitrogen (Carlsbad, Calif.). Human EphA2-Fc fusion protein (consisting of the human EphA2 ectodomain fused with the Fc portion of a human IgG1) was expressed in human embryonic kidney (HEK) 293 cells and purified by protein G affinity chromatography using standard protocols. Human EphA2-Fc biotinylation was carried out using an EZ-Link Sulfo-NHS-LC-Biotinylation Kit according to the manufacturer&#39;s instructions (Pierce, Rockford, Ill.). 
     1. Humanization of Murine Anti-Human EphA2 Antibody EA2 by Framework Shuffling Technology: 
     The humanization of the parental murine mAb EA2 was accomplished using the framework shuffling technology as described in detail by W. F. Dall&#39;Acqua et al., Methods 36 (2005) 43-60, and in U.S. Patent Application Publications No. 2005/0048617A1 and No. 2006/0228350A1 each of which is hereby incorporated by reference herein in its entirety. Essentially, CDR regions of both EA2 VL and EA2 VH regions were grafted onto libraries of human framework germline sequences in a combinatorial fashion, creating mosaic, humanized variants retaining EphA2 binding. One such humanized clone, 4H5, exhibited approximately a 20 fold increase of affinity when compared with chimeric Fab EA2. This clone was chosen as template for affinity maturation and was subsequently optimized as described below, resulting in the variants 2A4, 2E7 and 12E2. 
     2. Affinity Optimization of 4H5 scfv: 
     2.1 scFv template construction: The variable regions of humanized Mab 4H5 were cloned as an scFv fragment into an M13 expression vector (W. F. Dall&#39;Acqua et al./Methods). The 4H5 variable light region was combined to the 3′ end of the 4H5 variable heavy chain by a [(Gly) 4 Ser]3 linker, and followed by a FLAG tag and a His tag on the C-terminal end ( FIG. 1 ). Constructs were generated using PCR and the following primers to amplify the variable regions in separate reactions: 
     Medi-VH8: TTC TAT GCG OCC CAG CCG GCC CAG GTG CAG CTG TTG SAG TCT G (5′ primer to amplify VH, S=C/G) 
     Medi-JH1: GGA GCC GCC GCC GCC AGA ACC ACC ACC ACC TGA GGA GAC GGT GAC CAG GGT GCC (3′ primer to amplify VH), 
     Medi-VK1: GGC GGC GGC GGC TCC GGT GGT GGT GGT TCT GAC ATC CAG WTG ACC CAG TCT CC (5′ primer for VL, W=A/T) 
     Medi-JK4: TGG AAT TCG GCC CCC GAG GCC ACG TTT GAT CTC CAO CTT GGT CCC (3′ primer for VL), where underlined sequences corresponds to the [(Gly) 4 Ser]3 linker, and bold italic letters denote the Sfi I restriction site. Overlapping PCR was used to construct the scFv fragment which was then restricted by Sfi I and cloned into the vector MD 102. The murine parental EA2 variable regions were cloned in the same manner to serve as an scFv control. The 4H5 scFv construct was then expressed in CJ236 to produce uridine+ssDNA as described in Wu and An [Wu et. al., 2003]. This 4H5 scFv U+ssDNA was used as template for the mutagenic affinity optimization reactions that follow. 
     2.2 Affinity Optimization of scFv by Parsimonious randomization of each CDR region: Each amino acid of all 6 Complementary-Determining Regions (CDRs) was individually, randomly mutated using two separate libraries per amino acid [Wu et. al., 2003]. Encoding either 8 amino acids (NSS) or 12 amino acids (NWS) at every CDR amino acid position, each individual degenerate primer was used in a single hybridization mutagenesis reaction [Wu, 2003, Dall&#39;Acqua et. al., 2005], and then combined for generation of the corresponding CDR libraries. Briefly, each degenerate primer was phosphorylated, then used in a 10:1 ratio with uridinylated 4H5 scFv single-stranded U+DNA template (prepared as described in Wu et. An, 2003) in an annealing reaction where the temperature was lowered from 95° C. to 55° C. over 1 hour. T4 ligase and T7 DNA polymerase was added to the annealed reaction and the reaction was incubated for 1.5 hours at 37° C. Synthesis products for every amino acid of each CDR were pooled, however NSS and NWS libraries were kept segregated and screened independently. Typically, 1 μl of the pooled CDR library synthesized DNA was then electroporated into XL1-Blue for plaque formation on XL1-Blue bacterial lawn or production of scFv fragments as described [Wu, 2003]. 
     3. Screening of the Libraries 
     3.1. Primary Screen 
     3.1.1. Description 
     The primary screen consisted of a single point ELISA (SPE) which was carried out using supernatants containing soluble, secreted scFv protein prepared from 1 ml-bacterial culture grown in 96 deep-well plates and infected with individual recombinant M13 clones essentially as described in Wu, 2003, and Dall&#39;Acqua et. al., 2005. Briefly, this Capture ELISA involves coating individual wells of a 96-well Maxisorp immunoplate with approximately 30 ng of a mouse anti-FLAG antibody (Sigma), blocking with 3% BSA/PBS for 2 h at 37° C. and incubating with samples (soluble, secreted scFv) for 2 h at room temperature. 150-600 ng/well of biotinylated human EphA2-Fc was then added for 2 h at room temperature. This was followed by incubation with neutravidin-horseradish peroxydase (HRP) conjugate (Pierce, Ill.) for 40 min at room temperature. HRP activity was detected with tetra methyl benzidine (TMB) substrate and the reaction quenched with 0.2 M H2SO4. Plates were read at 450 nm n. 
     3.1.2. Result of the Primary Screen 
     Typically, clones exhibiting an OD 450 nm signal approximately two times greater than the parental 4H5 scFv were re-grown at a 15 ml scale, and re-assayed by the same ELISA in duplicate wells to confirm the positive result. Clones which repeated were then sequenced and assayed using an Activity ELISA (see below) to estimate the folds increase of binding to human EphA2. 
     3.2. Secondary Screen 
     3.2.1. Description 
     In order to further characterize the previously identified single-change, affinity optimized variants (see section 3.1), a secondary screen using secreted scFv fragments expressed from 15 ml-bacterial culture [Wu, 2003] was carried out. More precisely, two ELISAs were used: (i) an activity ELISA in which individual wells of a 96-well Maxisorp Immunoplate were coated with ˜0.5 ug of human EphA2-Fc and blocked with 3% BSA/PBS for 2 h at 37° C. 2-fold serially diluted samples were then added and incubated for 1 h at room temperature. Incubation with a goat anti-human kappa horseradish peroxydase (HRP) conjugate then followed. HRP activity was detected with TMB substrate and the reaction quenched with 0.2 M H2SO4. Plates were read at 450 nm; (ii) an anti-scFv quantification ELISA, which was carried out essentially as, described [Wu, 2003). Briefly, individual wells of a 96-well Ni NTA plate (Qiagen) incubated with 2-fold serially diluted samples or standard (50-0.78 ng/ml). Incubation with a mouse anti-FLAG horseradish peroxydase (HRP) conjugate then followed. HRP activity was detected with TMB substrate and the reaction quenched with 0.2 M H2SO4. Plates were read at 450 nm. 
     3.2.2. Results of the Secondary Screen 
     The two-part secondary ELISA screen described in section 3.2.1 allowed us to compare scFv 4H5 and the affinity optimized variants to each other in terms of binding to human EphA2 by normalizing their scFv concentrations. All single-change, affinity optimized variant scFv clones-exhibited better binding to human EphA2 when compared with the parental scFv 4H5 (Data not shown). 
     4. Construction and Characterization of Combinatorial Variants from CDR Affinity Optimized Clones. 
     4.1.1 Description: 
     To engineer combinatorial variants with further improvement in binding, all single amino acid changes which improved binding when compared to parental 4H5 scFv by activity/quantitative ELISA were combined to create a small, focused combinatorial library. Briefly, degenerate primers encoding all identified amino acid changes as well as the parental amino acid at the same position were designed. In an annealing reaction where all primers were included and synthesis followed (see section 2), a combinatorial library was constructed and screened as previously described (see section 3.1.1). 
     4.1.2 Results of Primary Screening on EphA2 
     Typically, clones exhibiting an OD 450 nm signal greater than the parental scFv 4H5 were re-grown at a 15 ml scale, and re-assayed by ELISA (described in section 3.1.1) in duplicate wells to confirm the positive result. Sixteen combinatorial variants were then selected and sequenced identifying 11 unique combinations of CDR amino acid changes thus making each variant different from one another by one to three amino acids at the primary sequence level. 
     4.1.3 Results of Secondary Screening on EphA2 
     The 11 unique combinatorial variants described above were analyzed by a secondary screen as described previously (3.2.1) to estimate the improved binding affinities of the combinatorial variants. All variants had significantly improved affinities for human EphA2 when compared to 4H5 scFv. Data for three affinity optimized combinatorial variants 2A4, 2E7, and 12E2 are shown in  FIG. 2 . 
     Binding Analysis 
     2A4, 2E7 and 12E2 as well as parental EA2 scFv and humanized 4H5 scFv were induced for expression in  E. coli  in a 1 L culture volume. The supernatants containing soluble, secreted scFv fragments were spun to remove cellular debris then passed over an anti-FLAG column (Sigma) to purify and isolate the variant proteins. The purified affinity optimized variants were analyzed by surface plasmon resonance detection using a BIAcore 3000 instrument (Pharmacia Biosensor, Uppsala, Sweden). Humanized, affinity optimized variants of EA2 exhibited 110-150 fold affinity improvement when compared to the parental anti-EphA2 scFv EA2. (see  FIG. 5 ). 
     EQUIVALENTS 
     Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the following claims. All publications, patents and patent applications mentioned in this specification are herein incorporated by reference into the specification to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference.