Patent Publication Number: US-2022233690-A1

Title: Compositions and methods for treating cytokine release syndrome

Description:
RELATED APPLICATION 
     This application claims the benefit of priority to U.S. Provisional Patent Application Ser. No. 63/142,643, filed Jan. 28, 2021, which is hereby incorporated by reference in its entirety. 
    
    
     SEQUENCE LISTING 
     The instant application contains a Sequence Listing which has been submitted electronically in ASCII format and is hereby incorporated by reference in its entirety. Said ASCII copy, created on Apr. 18, 2022, is named RPB-02601_SL.txt and is 691,682 bytes in size. 
     BACKGROUND 
     Cytokine release syndrome (CRS) is a systemic inflammatory response that can be triggered by a variety of factors, including certain drugs. When the symptoms associated with CRS occur less than six hours following the start of a therapeutic infusion they can be referred to as an infusion-related reaction (IRR). 
     T cell-activating cancer immunotherapies, including bi-specific antibody therapies, carry a particularly high risk of CRS (including IRR). In such therapies, CRS can be triggered by a massive release of IFN-γ by activated T cells or by the tumor cells themselves. Secreted IFN-γ induces activation of other immune cells, including macrophages, which in turn produce excessive amounts of other cytokines, such as IL-6, TNF-α, and IL-10. In particular, IL-6 contributes to many of the key symptoms of CRS, including vascular leakage, and activation of the complement and coagulation cascade inducing disseminated intravascular coagulation. IL-6 also likely contributes to cardiomyopathy by promoting myocardial dysfunction (Shimabukaro-Vornhagen et al. (2018)  Journal for Immunotherapy of Cancer  6:1-14). 
     Management of cancer immunotherapy toxicities, including CRS, is a challenging clinical problem. Mitigating CRS and/or IRR is critical for ensuring the safety of certain immunotherapy approaches, including the therapeutic use of bispecific antibodies that target T cells. While low grade CRS can generally be treated symptomatically with anti-histamines, antipyretics and fluids, severe CRS can represent a life-threatening adverse event that requires prompt and aggressive treatment. Certain anti-cytokine treatments, reduced dosing of the administered therapy, and premedication with steroids are currently used to reduce the incidence of severe CRS. For example, tocilizumab, an anti-IL-6 antibody, is used as an initial treatment for severe CRS in some circumstances. However, each these currently available treatments also can reduce the therapeutic efficacy of the immunotherapy for the treatment of the cancer. Thus, there remains a need for alternative strategies to mitigate the potentially life-threatening effects of CRS without at the same time negatively impacting the therapeutic benefits of cancer immunotherapies. 
     SUMMARY 
     Provided herein are methods and compositions for the treatment and/or prevention of cytokine release syndrome (CRS), including the treatment and/or prevention of infusion-related reaction (IRR). As disclosed herein, administration of CD40 antagonists (e.g., CD40 blocking antibodies) can reduce the release of cytokines associated with CRS without affecting the T cell activation and cytotoxicity induced by administration of certain cancer immunotherapies (e.g., CD3 bispecific antibodies, CAR T cells). Thus, in certain aspects, the methods and compositions herein are able to mitigate the potentially life-threatening effects of CRS without negatively impacting the therapeutic efficacy of T cell activating cancer immunotherapies, including bispecific antibodies. 
     In some aspects, provided herein are methods of treating cancer and inhibiting CRS (including IRR) in a subject, comprising conjointly administering to the subject (a) a multi-specific antigen binding molecule comprising a first antigen-binding domain that specifically binds to CD3 and a second antigen-binding domain that specifically binds to a tumor antigen; and (b) a CD40 antagonist. 
     In some embodiments, the multi-specific antigen binding molecule and the CD40 antagonist are administered concurrently or sequentially. In some embodiments, the CD40 antagonist is administered before the multi-specific antigen binding molecule. 
     In some embodiments, the CD40 antagonist is an antibody or antigen-binding fragment thereof. In some embodiments, the CD40 antagonist antibody or antigen-binding fragment thereof is chimeric, humanized, composite, murine, or human. In some embodiments, the CD40 antagonist antibody or antigen-binding fragment thereof is selected from Fv, Fav, F(ab′)2), Fab′, dsFv, scFv, sc(Fv)2, and diabodies fragments. 
     In some aspects, provided herein are methods of treating cancer and inhibiting CRS (including IRR) in a subject, comprising conjointly administering to the subject (a) a multi-specific antigen binding molecule comprising a first antigen-binding domain that specifically binds CD3 and a second antigen-binding domain that specifically binds a tumor antigen; and (b) a CAR-T cell expressing a CD40 antagonist. 
     In some embodiments, the multi-specific antigen binding molecule and the CAR-T cell are administered concurrently or sequentially. In some embodiments, the CAR-T cell is administered before the multi-specific antigen binding molecule. 
     In some embodiments, the CAR-T cell secretes the CD40 antagonist. In some embodiments, the CD40 antagonist is a scFv or Fab. In some embodiments, the CAR-T cell expresses the CD40 antagonist when it is activated. 
     Multi-specific antigen binding molecule may be a bispecific antigen binding molecule or a tri-specific antigen binding molecule. In some embodiments, wherein the tri-specific antigen binding molecule further comprises a third antigen-binding domain that specifically binds an additional T cell antigen or an additional tumor antigen. In some embodiments, third antigen-binding domain specifically binds CD28. In some embodiments, the tumor antigen is selected from CD19, CD123, STEAP2, CD20, SSTR2, CD38, STEAP1, 5T4, ENPP3, PSMA, MUC16, GPRC5D, and BCMA. 
     In some embodiments, the multi-specific antigen binding molecule comprises a multi-specific antibody or antigen-binding fragment thereof. In some embodiments, the multi-specific antibody or antigen-binding fragment thereof is chimeric, humanized, composite, murine, or human. In some embodiments, the multi-specific antigen binding molecule is selected from a bispecific CD3×CD19 antibody, a bispecific CD3×GPRC5D antibody, a bispecific CD3×CD123 antibody, a bispecific CD3×STEAP2 antibody, a bispecific CD3×CD20 antibody, a bispecific CD3×SSTR 2 antibody, a bispecific CD3×CD38 antibody, a bispecific CD3×STEAP1 antibody, a bispecific CD3×5T4 antibody, a bispecific CD3×ENPP3 antibody, a bispecific CD3×MUC16 antibody, a bispecific CD3×BCMA antibody, a bispecific CD3×PSMA antibody, and a trispecific CD3×CD28×CD38 antibody. 
     In some embodiments, the method activates T cells and/or increases T cell cytotoxicity in the subject. In some embodiments, the method induces cancer cell death in the subject. In some embodiments, the method inhibits cytokine release syndrome. In some embodiments, the cytokine release syndrome is inhibited as measured by keeping C-reactive protein (CRP) level below 7 mg/dL, IFN-γ below 75 pg/ml, and/or IL-10 below 60 pg/ml. 
     In some aspects, provided herein are methods of inhibiting CRS (including IRR) caused by a multi-specific antigen binding molecule comprising a first antigen-binding domain that specifically binds CD3 and a second antigen-binding domain that specifically binds a tumor antigen in a subject, comprising administering to the subject a CAR-T cell expressing an CD40 antagonist. 
     In some embodiments, the subject is a human. In some embodiments, the subject is a cancer patient. In some embodiments, the methods described herein further comprises identifying a subject that is susceptible to cytokine release syndrome or in need of reduction in cytokine release prior to administering to the subject a CD40 antagonist or a CAR-T cell expressing a CD40 antagonist. 
     In some aspects, provided herein are pharmaceutical compositions comprising: a multi-specific antigen binding molecule comprising a first antigen-binding domain that specifically binds CD3 and a second antigen-binding domain that specifically binds a tumor antigen; and a CD40 antagonist. In some embodiments, the pharmaceutical compositions described herein further comprise a pharmaceutically acceptable carrier. 
     In some aspects, provided herein are methods of treating cancer and/or inhibiting CRS (including IRR) in a subject, comprising administering to the subject a pharmaceutical composition described herein. In some aspects, provided herein are methods of treating cancer and/or inhibiting CRS (including IRR) in a subject comprising: identifying a subject that is susceptible for cytokine release syndrome or in need of reduction in cytokine release; and administering to the subject a pharmaceutical composition described herein. 
     In some aspects, provided herein are methods of treating cancer and/or inhibiting CRS (including IRR) in a subject comprising: (a) identifying a subject that is susceptible for cytokine release syndrome or in need of reduction in cytokine release; and (b) conjointly administering to the subject (1) a multi-specific antigen binding molecule comprising a first antigen-binding domain that specifically binds to CD3 and a second antigen-binding domain that specifically binds to a tumor antigen; and (2) a CD40 antagonist. 
     In some aspects, provided herein are methods of treating cancer and/or inhibiting CRS (including IRR) in a subject comprising: (a) identifying a subject that is susceptible for cytokine release syndrome or in need of reduction in cytokine release; and (b) conjointly administering to the subject (1) a multi-specific antigen binding molecule comprising a first antigen-binding domain that specifically binds CD3 and a second antigen-binding domain that specifically binds a tumor antigen; and (2) a CAR-T cell expressing a CD40 antagonist. 
     In some embodiments, the subject susceptible for CRS and/or in need of reduction in cytokine release is identified by detecting one or more biomarkers selected from the group consisting of fever, rash, respiratory symptoms, hypoxia, hypotension, cardiovascular dysfunction, neurotoxicity, hepatic dysfunction, renal dysfunction, coagulation, organ toxicity, tumor burden, cytokines, C-reactive protein (CRP), ferritin, lactate dehydrogenase (LDH), aspartate aminotransferase (AST), blood urea nitrogen (BUN), alanine aminotransferase (ALT), creatinine (Cr), fibrinogen, Prothrombin Time (PT), Partial Thromboplastin Time (PTT), eotaxins, and endothelial cell activation. 
     In some embodiments, the cytokines are one or more cytokines selected from the group consisting of sTNFR2, IP10, sIL1R2, sTNFR1, MIG, VEGF, sIL1R1, TNFα, IFNα, GCSF, sRAGE, IL1, IL2, IL4, IL5, IL10, IL12, IL13, IL18, IL1R1, IFNγ, IL6, IL8, sIL2Rα, sgp130, sIL6R, MCP1, MIP1α, MIP1β, FLT-3L, fractalkine, and GM-CSF. In some embodiments, the endothelial cell activation is detected by measuring the serum level of Ang-2 and/or von Willebrand factor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A-1I  show that CD40 blockade inhibited cytokine release mediated by CD123×CD3 without affecting T cell activation in 4 day assay with PBMC enriched with autologous B cells. 
         FIGS. 2A-2E  show that CD40 blockade inhibited cytokine release mediated by a CD3 bispecific in a 4 day assay with AML cell line and PBMC without additional autologous B cells. 
         FIGS. 3A-3G  show that CD40 blockade inhibited selected cytokine release mediated by CD3 bispecific without significantly affecting T cell activation and target killing in 4 day killing assay with prostatic cell line and PBMC. 
         FIGS. 4A and 4B  show that CD40 blockade reduced cytokines in PBMC treated with CD20×CD3 bispecific (REGN1979). 
     
    
    
     DETAILED DESCRIPTION 
     General 
     Provided herein are methods and compositions for the treatment and/or prevention of cytokine release syndrome (CRS), including the treatment and/or prevention of infusion-related reaction (IRR). As disclosed herein, administration of CD40 antagonists (e.g., CD40 blocking antibodies) can reduce the release of cytokines associated with CRS without affecting the T cell activation and cytotoxicity induced by administration of certain cancer immunotherapies (e.g., CD3 bispecific antibodies, CAR T cells). Thus, in certain aspects, the methods and compositions herein are able to mitigate the potentially life-threatening effects of CRS without negatively impacting the therapeutic efficacy of T cell activating cancer immunotherapies, including bispecific antibodies. 
     Accordingly, in certain aspects, provided herein are methods of treating and/or preventing CRS and/or reducing CRS-associated symptoms in a subject who is undergoing an cancer immunotherapy (e.g., with a multi-specific antigen binding molecule comprising a first antigen-binding domain that specifically binds to CD3 and a second antigen-binding domain that specifically binds to a tumor antigen) by administering to the subject a CD40 antagonist (e.g., an antagonistic antibody that binds to CD40) and/or a CAR-T cell expressing a CD40 antagonist. 
     In some aspects, provided herein are pharmaceutical compositions comprising: a multi-specific antigen binding molecule comprising a first antigen-binding domain that specifically binds CD3 and a second antigen-binding domain that specifically binds a tumor antigen; and a CD40 antagonist. In some embodiments, the pharmaceutical compositions described herein further comprise a pharmaceutically acceptable carrier. 
     It is to be understood that this disclosure is not limited to particular methods and experimental conditions described, as such methods and conditions may vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims. 
     All patents, applications and non-patent publications mentioned in this specification are incorporated herein by reference in their entireties. 
     Definitions 
     For convenience, certain terms employed in the specification, examples, and appended claims are collected here. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. As used herein, the term “about,” when used in reference to a particular recited numerical value, means that the value may vary from the recited value by no more than 1%. For example, as used herein, the expression “about 100” includes 99 and 101 and all values in between (e.g., 99.1, 99.2, 99.3, 99.4, etc.). 
     The articles “a” and “an” are used herein to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article. By way of example, “an element” means one element or more than one element. 
     As used herein, the term “administering” or “administration” means providing a pharmaceutical agent or composition to a subject, and includes, but is not limited to, administering by a medical professional and self-administering. Such an agent can contain, for example, a CAR T cell provided herein. 
     As used herein, the term “antibody” may refer to both an intact antibody and an antigen binding fragment thereof. Intact antibodies are glycoproteins that include at least two heavy (H) chains and two light (L) chains inter-connected by disulfide bonds. Each heavy chain includes a heavy chain variable region (abbreviated herein as V H ) and a heavy chain constant region. Each light chain includes a light chain variable region (abbreviated herein as V L ) and a light chain constant region. The V H  and V L  regions can be further subdivided into regions of hypervariability, termed complementarity determining regions (CDR), interspersed with regions that are more conserved, termed framework regions (FR). Each V H  and V L  is composed of three CDRs and four FRs, arranged from amino-terminus to carboxy-terminus in the following order: FR1, CDR1, FR2, CDR2, FR3, CDR3, FR4. The variable regions of the heavy and light chains contain a binding domain that interacts with an antigen. The term “antibody” includes, for example, monoclonal antibodies, polyclonal antibodies, chimeric antibodies, humanized antibodies, human antibodies, multispecific antibodies (e.g., bispecific antibodies, trispecific antibodies), single-chain antibodies and antigen-binding antibody fragments. 
     The terms “antigen binding fragment” and “antigen-binding portion” of an antibody, as used herein, refer to one or more fragments of an antibody that retain the ability to bind to an antigen. Non-limiting examples of antigen-binding fragments include: (i) Fab fragments; (ii) F(ab′)2 fragments; (iii) Fd fragments; (iv) Fv fragments; (v) single-chain Fv (scFv) molecules; (vi) dAb fragments; and (vii) minimal recognition units consisting of the amino acid residues that mimic the hypervariable region of an antibody (e.g., an isolated complementarity determining region (CDR) such as a CDR3 peptide), or a constrained FR3-CDR3-FR4 peptide. Other engineered molecules, such as domain-specific antibodies, single domain antibodies, domain-deleted antibodies, chimeric antibodies, CDR-grafted antibodies, diabodies, triabodies, tetrabodies, minibodies, nanobodies (e.g. monovalent nanobodies, bivalent nanobodies, etc.), small modular immunopharmaceuticals (SMIPs), and shark variable IgNAR domains, are also encompassed within the expression “antigen-binding fragment,” as used herein. 
     “Cancer” broadly refers to an uncontrolled, abnormal growth of a host&#39;s own cells leading to invasion of surrounding tissue and potentially tissue distal to the initial site of abnormal cell growth in the host. Major classes include carcinomas which are cancers of the epithelial tissue (e.g., skin, squamous cells); sarcomas which are cancers of the connective tissue (e.g., bone, cartilage, fat, muscle, blood vessels, etc.); leukemias which are cancers of blood forming tissue (e.g., bone marrow tissue); lymphomas and myelomas which are cancers of immune cells; and central nervous system cancers which include cancers from brain and spinal tissue. “Cancer(s) and” “neoplasm(s)”” are used herein interchangeably. As used herein, “cancer” refers to all types of cancer or neoplasm or malignant tumors including leukemias, carcinomas and sarcomas, whether new or recurring. Specific examples of cancers are: carcinomas, sarcomas, myelomas, leukemias, lymphomas and mixed type tumors. Non-limiting examples of cancers are new or recurring cancers of the brain, melanoma, bladder, breast, cervix, colon, head and neck, kidney, lung, non-small cell lung, mesothelioma, ovary, prostate, sarcoma, stomach, uterus and medulloblastoma. In some embodiments, the cancer comprises a solid tumor. In some embodiments, the cancer comprises a metastasis. 
     The term “chimeric antigen receptor” (CAR) refers to molecules that combine a binding domain against a component present on the target cell, for example an antibody-based specificity for a desired antigen (e.g., a tumor antigen) with a T cell receptor-activating intracellular domain to generate a chimeric protein that exhibits a specific anti-target cellular immune activity. Generally, CARs consist of an extracellular single chain antigen-binding domain (scFv) fused to the intracellular signaling domain of the T cell antigen receptor complex zeta chain, and have the ability, when expressed in T cells, to redirect antigen recognition based on the monoclonal antibody&#39;s specificity. 
     As used herein, the phrase “conjoint administration” or “administered conjointly” refers to any form of administration of two or more different therapeutic agents such that the second agent is administered while the previously administered therapeutic agent is still effective in the body (e.g., the two agents are simultaneously effective in the subject, which may include synergistic effects of the two agents). For example, the different therapeutic agents can be administered either in the same formulation or in separate formulations, either concomitantly or sequentially. In certain embodiments, the different therapeutic agents can be administered within about one hour, about 12 hours, about 24 hours, about 36 hours, about 48 hours, about 72 hours, or about a week of one another. Thus, a subject who receives such treatment can benefit from a combined effect of different therapeutic agents. 
     A “costimulatory domain” or “costimulatory molecule” refers to the cognate binding partner on a T-cell that specifically binds with a costimulatory ligand, thereby mediating a costimulatory response by the cell, such as, but not limited to proliferation. The costimulatory domain may be a human costimulatory domain. Exemplary costimulatory molecules include, CD28, 4-1BB, CD27, CD8, 4-1BB (CD137), OX40, CD30, CD40, PD-1, ICOS, lymphocyte function-associated antigen-1 (LFA-1), CD2, CD7, LIGHT, NKG2C, and B7-H3. 
     A “costimulatory ligand” refers to a molecule on an antigen presenting cell that specifically binds a cognate costimulatory molecule on a T-cell, thereby providing a signal which mediates a T cell response, including, but not limited to, proliferation activation, differentiation and the like. A costimulatory ligand can include but is not limited to CD7, B7-1 (CD80), B7-2 (CD86), PD-L1, PD-L2, 4-1BBL, OX40L, inducible costimulatory ligand (ICOS-L), intercellular adhesion molecule (ICAM), CD30L, CD40, CD70, CD83, HLA-G, MICA, M1CB, HVEM, lymphotoxin beta receptor, 3/TR6, ILT3, ILT4, an agonist or antibody that binds Toll ligand receptor and a ligand that specifically binds with B7-H3. 
     A “costimulatory signal” refers to a signal, which in combination with a primary signal, leads to T cell proliferation and/or upregulation or downregulation of key molecules. 
     The term “epitope” refers to an antigenic determinant that interacts with a specific antigen binding site in the variable region of an antibody molecule known as a paratope. A single antigen may have more than one epitope. Thus, different antibodies may bind to different areas on an antigen and may have different biological effects. Epitopes may be either conformational or linear. A conformational epitope is produced by spatially juxtaposed amino acids from different segments of the linear polypeptide chain. A linear epitope is one produced by adjacent amino acid residues in a polypeptide chain. In certain circumstance, an epitope may include moieties of saccharides, phosphoryl groups, or sulfonyl groups on the antigen. 
     As used herein, the phrase “pharmaceutically acceptable” refers to those agents, compounds, materials, compositions, and/or dosage forms which are, within the scope of sound medical judgment, suitable for use in contact with the tissues of human beings and animals without excessive toxicity, irritation, allergic response, or other problem or complication, commensurate with a reasonable benefit/risk ratio. 
     As used herein, the phrase “pharmaceutically-acceptable carrier” means a pharmaceutically-acceptable material, composition or vehicle, such as a liquid or solid filler, diluent, excipient, or solvent encapsulating material, involved in carrying or transporting an agent from one organ, or portion of the body, to another organ, or portion of the body. Each carrier must be “acceptable” in the sense of being compatible with the other ingredients of the formulation and not injurious to the patient. Some examples of materials which can serve as pharmaceutically-acceptable carriers include: (1) sugars, such as lactose, glucose and sucrose; (2) starches, such as corn starch and potato starch; (3) cellulose, and its derivatives, such as sodium carboxymethyl cellulose, ethyl cellulose and cellulose acetate; (4) powdered tragacanth; (5) malt; (6) gelatin; (7) talc; (8) excipients, such as cocoa butter and suppository waxes; (9) oils, such as peanut oil, cottonseed oil, safflower oil, sesame oil, olive oil, corn oil and soybean oil; (10) glycols, such as propylene glycol; (11) polyols, such as glycerin, sorbitol, mannitol and polyethylene glycol; (12) esters, such as ethyl oleate and ethyl laurate; (13) agar; (14) buffering agents, such as magnesium hydroxide and aluminum hydroxide; (15) alginic acid; (16) pyrogen-free water; (17) isotonic saline; (18) Ringer&#39;s solution; (19) ethyl alcohol; (20) pH buffered solutions; (21) polyesters, polycarbonates and/or polyanhydrides; and (22) other non-toxic compatible substances employed in pharmaceutical formulations. 
     The terms “polynucleotide”, and “nucleic acid” are used interchangeably. They refer to a natural or synthetic molecule, or some combination thereof, comprising a single nucleotide or two or more nucleotides linked by a phosphate group at the 3′ position of one nucleotide to the 5′ end of another nucleotide. The polymeric form of nucleotides is not limited by length and can comprise either deoxyribonucleotides or ribonucleotides, or analogs thereof. Polynucleotides may have any three-dimensional structure, and may perform any function. The following are non-limiting examples of polynucleotides: coding or non-coding regions of a gene or gene fragment, loci (locus) defined from linkage analysis, exons, introns, messenger RNA (mRNA), transfer RNA, ribosomal RNA, ribozymes, cDNA, recombinant polynucleotides, branched polynucleotides, plasmids, vectors, isolated DNA of any sequence, isolated RNA of any sequence, nucleic acid probes, and primers. A polynucleotide may comprise modified nucleotides, such as methylated nucleotides and nucleotide analogs. If present, modifications to the nucleotide structure may be imparted before or after assembly of the polymer. A polynucleotide may be further modified, such as by conjugation with a labeling component. In all nucleic acid sequences provided herein, U nucleotides are interchangeable with T nucleotides. The polynucleotide is not necessarily associated with the cell in which the nucleic acid is found in nature, and/or operably linked to a polynucleotide to which it is linked in nature. 
     As used herein, a therapeutic that “prevents” a condition refers to a compound that, when administered to a statistical sample prior to the onset of the disorder or condition, reduces the occurrence of the disorder or condition in the treated sample relative to an untreated control sample, or delays the onset or reduces the severity of one or more symptoms of the disorder or condition relative to the untreated control sample. 
     The term “substantial identity” or “substantially identical,” when referring to a nucleic acid or fragment thereof, indicates that, when optimally aligned with appropriate nucleotide insertions or deletions with another nucleic acid (or its complementary strand), there is nucleotide sequence identity in at least about 95%, and more preferably at least about 96%, 97%, 98% or 99% of the nucleotide bases, as measured by any well-known algorithm of sequence identity, such as FASTA, BLAST or Gap, as discussed below. A nucleic acid molecule having substantial identity to a reference nucleic acid molecule may, in certain instances, encode a polypeptide having the same or substantially similar amino acid sequence as the polypeptide encoded by the reference nucleic acid molecule. 
     As applied to polypeptides, the term “substantial similarity” or “substantially similar” means that two peptide sequences, when optimally aligned, such as by the programs GAP or BESTFIT using default gap weights, share at least 95% sequence identity, even more preferably at least 98% or 99% sequence identity. Preferably, residue positions which are not identical differ by conservative amino acid substitutions. A “conservative amino acid substitution” is one in which an amino acid residue is substituted by another amino acid residue having a side chain (R group) with similar chemical properties (e.g., charge or hydrophobicity). In general, a conservative amino acid substitution will not substantially change the functional properties of a protein. In cases where two or more amino acid sequences differ from each other by conservative substitutions, the percent sequence identity or degree of similarity may be adjusted upwards to correct for the conservative nature of the substitution. Means for making this adjustment are well-known to those of skill in the art. See, e.g., Pearson (1994) Methods Mol. Biol. 24: 307-331, herein incorporated by reference. Examples of groups of amino acids that have side chains with similar chemical properties include (1) aliphatic side chains: glycine, alanine, valine, leucine and isoleucine; (2) aliphatic-hydroxyl side chains: serine and threonine; (3) amide-containing side chains: asparagine and glutamine; (4) aromatic side chains: phenylalanine, tyrosine, and tryptophan; (5) basic side chains: lysine, arginine, and histidine; (6) acidic side chains: aspartate and glutamate, and (7) sulfur-containing side chains are cysteine and methionine. Preferred conservative amino acids substitution groups are: valine-leucine-isoleucine, phenylalanine-tyrosine, lysine-arginine, alanine-valine, glutamate-aspartate, and asparagine-glutamine. Alternatively, a conservative replacement is any change having a positive value in the PAM250 log-likelihood matrix disclosed in Gonnet et al. (1992) Science 256: 1443-1445, herein incorporated by reference. A “moderately conservative” replacement is any change having a nonnegative value in the PAM250 log-likelihood matrix. 
     The term “specifically binds” or “specific binding”, as used herein, when referring to a polypeptide refers to a binding reaction which is determinative of the presence of the protein or polypeptide or receptor in a heterogeneous population of proteins and other biologics. Thus, under designated conditions (e.g. immunoassay conditions in the case of an antibody), a specified ligand or antibody “specifically binds” to its particular “target” (e.g. an antibody specifically binds to an endothelial antigen) when it does not bind in a significant amount to other proteins present in the sample or to other proteins to which the ligand or antibody may come in contact in an organism. Generally, a first molecule that “specifically binds” a second molecule has an affinity constant (Ka) greater than about 10 5  M −1  (e.g., 10 6  M −1 , 10 7  M −1 , 10 8  M −1 , 10 9  M −1 , 10 10  M −1 , 10 11  M −1 , and 10 12  M −1  or more) with that second molecule. For example, in the case of the ability of a PIG-specific CAR to bind to a peptide presented on an MHC (e.g., class I MHC or class II MHC); typically, a CAR specifically binds to its peptide/MHC with an affinity of at least a KD of about 10-4 M or less, and binds to the predetermined antigen/binding partner with an affinity (as expressed by KD) that is at least 10 fold less, at least 100 fold less or at least 1000 fold less than its affinity for binding to a non-specific and unrelated peptide/MHC complex (e.g., one comprising a BSA peptide or a casein peptide). 
     As used herein, the term “subject” means a human or non-human animal selected for treatment or therapy. 
     As used herein, the term “treatment” refers to clinical intervention designed to alter the natural course of the individual being treated during the course of clinical pathology. Desirable effects of treatment include decreasing the rate of progression, ameliorating or palliating the pathological state, and remission or improved prognosis of a particular disease, disorder, or condition. An individual is successfully “treated,” for example, if one or more symptoms associated with a particular disease, disorder, or condition are mitigated or eliminated. 
     Cytokine Release Syndrome (CRS) 
     General 
     In certain aspects, provided herein are methods and compositions for treating and/or preventing cytokine release syndrome (CRS). The symptoms associated with CRS can include infusion-related reaction (IRR) if they occur less than six hours following the start of a therapeutic infusion. Thus, in certain embodiments, the methods and compositions provided herein can be useful in treating and/or preventing CRS and/or CRS symptoms, including, but not limited to, IRR. 
     CRS is a potentially life-threatening cytokine-associated toxicity that can occur as a result of cancer immunotherapy, e.g., cancer antibody therapies (e.g., bispecific antibodies) and/or T cell immunotherapies (e.g., CAR T cells). CRS results from high-level immune activation when large numbers of lymphocytes and/or myeloid cells release inflammatory cytokines upon activation. The severity of CRS and the timing of onset of symptoms can vary depending on the magnitude of immune cell activation, the type of therapy administered, and/or the extent of tumor burden in a subject. In the case of T-cell therapy for cancer, symptom onset is typically days to weeks after administration of the T-cell therapy, e.g., when there is peak in vivo T-cell expansion. See, e.g., Lee et al. (2014)  Blood.  124:188-195. 
     Symptoms of CRS can include neurologic toxicity, disseminated intravascular coagulation, cardiac dysfunction, adult respiratory distress syndrome, renal failure, and/or hepatic failure. For example, symptoms of CRS can include fever with or without rigors, fatigue, malaise, myalgias, vomiting, headache, nausea, anorexia, arthalgias, diarrhea, rash, hypoxemia, tachypnea, hypotension, widened pulse pressure, potentially diminished cardiac output (late), increased cardiac output (early), azotemia, hypofibrinogenemia with or without bleeding, elevated D-dimer, hyperbilirubinemia, transaminitis, confusion, delirium, mental status changes, hallucinations, tremor, seizures, altered gait, word finding difficulty, frank aphasia, or dymetria. 
     CRS Grading 
     In certain aspects, the methods and compositions provided herein can be used to treat and/or prevent CRS of any degree of severity. In certain embodiments, the methods and compositions provided herein are used in the treatment and/or prevention of severe CRS. 
     The management of CRS may follow a grade- and risk-adapted strategy for monitoring and therapy. Several CRS grading systems have been developed and disclosed in, e.g., Porter et al. (2018) J. Hematol Oncol. 11:35, Lee et al. (2014) Blood 124:188-195, Neelapu et al. (2018) Nat. Rev. Clin. Oncol. 15:47-62, Neelapu et al. (2018) Nat. Rev. Clin. Oncol. 15:218, Teachey et al. (2016) Cancer Discov. 6:664-679, and U.S. Patent Application Publication No. 2019/0336504, each of which is incorporated by reference herein in its entirety. Any of these CRS grading system may be used to evaluate, diagnose, stratify, or identify subjects for the methods provided herein. 
     In some embodiments, CRS can be graded in severity from 1-5 as follows. Grades 1-3 are less than severe CRS. Grades 4-5 are severe CRS. For Grade 1 CRS, only symptomatic treatment is needed (e.g., nausea, fever, fatigue, myalgias, malaise, headache) and symptoms are not life threatening. For Grade 2 CRS, the symptoms require moderate intervention and generally respond to moderate intervention. Subjects having Grade 2 CRS develop hypotension that is responsive to either fluids or one low-dose vasopressor; or they develop grade 2 organ toxicity or mild respiratory symptoms that are responsive to low flow oxygen (&lt;40% oxygen). In Grade 3 CRS subjects, hypotension generally cannot be reversed by fluid therapy or one low-dose vasopressor. These subjects generally require more than low flow oxygen and have grade 3 organ toxicity (e.g., renal or cardiac dysfunction or coagulopathy) and/or grade 4 transaminitis. Grade 3 CRS subjects require more aggressive intervention, e.g., oxygen of 40% or higher, high dose vasopressor(s), and/or multiple vasopressors. Grade 4 CRS subjects suffer from immediately life-threatening symptoms, including grade 4 organ toxicity or a need for mechanical ventilation. Grade 4 CRS subjects generally do not have transaminitis. In Grade 5 CRS subjects, the toxicity causes death. For example, criteria for grading CRS is disclosed in U.S. Patent Application Publication No. 2019/0336504, which is incorporated by reference herein in its entirety. 
     In certain embodiments, the methods and/compositions provided herein treat and/or prevent grade 5 CRS. In certain embodiments, the methods and/compositions provided herein treat and/or prevent grade 4 CRS. In certain embodiments, the methods and/compositions provided herein treat and/or prevent grade 3 CRS. In certain embodiments, the methods and/compositions provided herein treat and/or prevent grade 2 CRS. In certain embodiments, the methods and/compositions provided herein treat and/or prevent grade 1 CRS. 
     Identifying a Subject at Risk for CRS 
     In certain embodiments, the methods provided herein include the treatment of a subject susceptible for CRS and/or in need of reduction in cytokine release. In some embodiments, the methods provided herein comprise identifying a subject susceptible for CRS and/or or in need of reduction in cytokine release. 
     In some embodiments, one or more biomarkers are used to evaluate (e.g., diagnose or identify) a subject susceptible for CRS or in need of reduction in cytokine release. In some embodiments, the one or more biomarkers are selected from fever, rash, respiratory symptoms, hypoxia, hypotension, cardiovascular dysfunction, neurotoxicity, hepatic dysfunction, renal dysfunction, coagulation, organ toxicity, tumor burden, cytokines, eotaxins, C-reaction protein (CRP), ferratin, creatinine, and endothelial cell activation, etc. 
     In certain embodiments, the exemplary cytokines include, but are not limited to, e.g., sTNFR2, IP10, sIL1R2, sTNFR1, MIG, VEGF, sIL1R1, TNFα, IFNα, GCSF, sRAGE, IL2, IL4, IL5, IL10, IL12, IL13, IL18, IL1R1, IFNγ, IL6, IL8, sIL2Rα, sgp130, sIL6R, MCP1, MIP1α, MIP1β, FLT-3L, fractalkine, and GM-CSF. In some embodiments, one or more (e.g., two or more, or three or more) of the cytokines, sTNFR2, IP10, sIL1R2, sTNFR1, MIG, VEGF, sIL1R1, TNFα, IFNα, GCSF, sRAGE, IL1, IL2, IL4, IL5, IL10, IL12, IL13, IL18, IL1R1, IFNγ, IL6, IL8, sIL2Rα, sgp130, sIL6R, MCP1, MIP1α, MIP1β, FLT-3L, fractalkine, and GM-CSF, are used to evaluate (e.g., diagnose or identify) a subject susceptible for CRS or in need of reduction in cytokine release. 
     Exemplary biomarkers used to evaluate (e.g., predict) CRS severity can also include disease burden assessments, e.g., the extent of disease (e.g., cancer) in a subject. For example, a disease burden assessment can be made by determining the level of disease (e.g., cancer) in a biological sample from a subject. For example, a high disease burden is indicated by the presence of at least 25% (e.g., 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 70%, 80%, 90% or higher) cancer cells in a biological sample obtained from a subject (e.g., determined by morphology on an aspirate or biopsy, a flow assay on an aspirate or biopsy, and/or by MRD). In some embodiments, a high disease burden is indicated by the presence of at least 50% cancer cells in a biological sample obtained from a subject. For example, a low disease burden is indicated by the presence of less than 25% (e.g., 24%, 23%, 22%, 21%, 20%, 15%, 10%, 5% or less) cancer cells in a biological sample obtained from a subject (e.g., determined by morphology on an aspirate or biopsy, a flow assay on an aspirate or biopsy, and/or by MRD). In some embodiments, a low disease burden is indicated by the presence of less than 0.1%, 1%, 5%, 10%, 15%, 20%, or 25% cancer cells in a biological sample obtained from a subject. 
     In some embodiments, one or more cytokines in combination with a disease burden assessment is used to evaluate (e.g., diagnose or identify) a subject susceptible for CRS or in need of reduction in cytokine release. 
     Another exemplary biomarker used to evaluate (e.g., diagnose or identify) a subject susceptible for CRS or in need of reduction in cytokine release includes C-reactive protein (CRP) level or activity. In embodiments, a subject at low risk of severe CRS is identified as having a CRP level of less than 7 mg/dL (e.g., 7, 6.8, 6, 5, 4, 3, 2, 1 mg/dL or less). In some embodiments, a subject at high risk of severe CRS is identified as having a greater level of CRP in a sample (e.g., a blood sample) compared to a subject at low risk of severe CRS or compared to a control level or activity. In some embodiments, the greater level or activity is at least 2-fold greater (e.g., at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 40, 50, 100, 500, 1000-fold or more greater) compared to a subject at low risk of severe CRS or compared to a control level or activity. 
     In some embodiments, one or more biomarkers described herein are used to predict CRS risk or severity in a subject early on after administration with the CD40 antagonist and/or CD3 multispecific antibody described herein. In some embodiments, one or more biomarkers described herein are used to predict CRS risk or severity in a subject within 2 weeks, e.g., within 1 week or less after administration with the CD40 antagonist and/or CD3 multispecific antibody described herein. In embodiments, the biomarkers described herein are used to predict CRS risk or severity in a subject within 10 days (e.g., 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 day or less after administration with the CD40 antagonist and/or CD3 multispecific antibody described herein. In embodiments, the biomarkers described herein are used to predict CRS risk or severity in a subject within 1-10 days (e.g., within 1-10, 1-9, 1-8, 1-7, 1-6, 1-5, 1-4, 1-3, 1-2, or 1 day after administration with the CD40 antagonist and/or CD3 multispecific antibody described herein. In embodiments, the biomarkers described herein are used to predict CRS risk or severity in a subject before the subject experiences one or more symptoms of grade 2, 3, 4, or 5 CRS (e.g., before the subject experiences one or more symptoms of grade 3, 4, or 5 CRS, or grade 4 or 5 CRS). 
     In some embodiments, elevated or reduced levels of one or more of the cytokines described herein, e.g., sTNFR2, IP10, sIL1R2, sTNFR1, VEGF, sIL1R1, TNFα, IFNα, GCSF, sRAGE, IL1, IL2, IL4, IL5, IL10, IL12, IL13, IL18, IL1R1, IFNγ, IL6, IL8, sIL2Rα, sgp130, sIL6R, MCP1, MIP1α, MIPβ, FLT-3L, fractalkine, and GM-CSF, relative to a control level, indicate that the subject is susceptible for CRS or in need of reduction in cytokine release, or at risk of developing severe CRS. The control level may be a reference level, a baseline level, a level from a healthy subject, a level from a subject having disorder or condition (e.g., cancer) other than CRS, a level from a subject prior to administration of the CD3 mulitspecific antibody and/or CD40 antagonist described herein, or a subject with a specific grade of CRS. 
     In some embodiments, an elevation of one or more of the cytokines described herein (e.g., one or more of IFNγ, IL6, IL10, sgp130, IL18, TNFα, IL8, IP10, MCP1, MIG, MIP1β, and sIL6R) by at least 2-fold (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 50, 100, 500, 1000-fold or more) relative to a control level (e.g., a baseline level), indicate that the subject is susceptible for CRS or in need of reduction in cytokine release, or at risk of developing severe CRS. 
     In some embodiments, a reduction of one or more of the cytokines described herein (e.g., one or more of IL1R1, MIP1α, and IL13) by at least 10% (e.g., at least 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, or 99%) relative to a reference level, indicate that the subject is susceptible for CRS or in need of reduction in cytokine release, or at risk of developing severe CRS. In some embodiments, the reference level is a value that does not depend on the baseline level of the cytokine in the subject. In some embodiments, the reference level is baseline cytokine value or baseline cytokine values by disease burden. 
     In some embodiments, an elevation of one or more of cytokines described herein (e.g., IFNγ, IL6, IL10, sgp130, IL18, TNFα, IL8, IP10, MCP1, MIG, MIP1β, and sIL6R), e.g., by at least 2-fold (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 50, 100, 500, 1000-fold or more) relative to a control level, e.g., when measured within 1-10 days (e.g., within 1-10, 1-9, 1-8, 1-7, 1-6, 1-5, 1-4, 1-3, 1-2, or 1 day) after administration with a CD3 multispecific antibody described herein, indicate that the subject is susceptible for CRS or in need of reduction in cytokine release, or at risk of developing severe CRS. 
     In some embodiments, a CRP level of less than 7 mg/dL (e.g., 7, 6.8, 6, 5, 4, 3, 2, 1 mg/dL or less), e.g., when measured within 1-10 days (e.g., within 1-10, 1-9, 1-8, 1-7, 1-6, 1-5, 1-4, 1-3, 1-2, or 1 day after administration with a CD3 multispecific antibody described herein, indicate that the subject is at low risk of developing severe CRS. 
     In embodiments, a CRP level of 6 mg/dL or greater (e.g., 6, 6.8, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40 mg/dL or greater), e.g., when measured within 1-10 days (e.g., within 1-10, 1-9, 1-8, 1-7, 1-6, 1-5, 1-4, 1-3, 1-2, or 1 day after administration with a CD3 multispecific antibody described herein, indicate that the subject is at high risk of developing severe CRS. 
     In certain aspects, the disclosure provides a method of monitoring CRS (e.g., monitoring a patient having CRS0, CRS1, CSR2, or CRS3) or monitoring for the development of severe CRS, comprising evaluating one or more CRS biomarkers herein. The method can involve measuring the one or more biomarkers at a plurality of timepoints, e.g., at 2, 3, 4, 5, 6, 7, 8, 9, 10, or more timepoints. In certain aspects, the disclosure provides a method of managing CRS, comprising evaluating a subject at risk for developing CRS (e.g., severe CRS), and optionally administering a treatment for CRS, e.g., a treatment described herein. 
     Identifying a Subject Having CRS 
     In certain embodiments, the methods provided herein include the treatment of a subject who has CRS. In some embodiments, in some embodiments, the methods provided herein include a step of determining whether a subject has CRS (e.g., severe CRS). The method includes acquiring a CRS risk status, e.g., in response to an cancer immunotherapy, e.g., a CD3 multispecific antibody, for the subject, wherein said CRS risk status includes a measure of one or more of the level or activity of one or more (e.g., 3, 4, 5, 10, 15, 20, or more) cytokines chosen from sTNFR2, IP10, sIL1R2, sTNFR1, MIG, VEGF, sIL1R1, TNFα, IFNα, GCSF, sRAGE, IL1, IL2, IL4, IL5, IL10, IL12, IL13, IL18, IL1R1, IFNγ, IL6, IL8, sIL2Rα, sgp130, sIL6R, MCP1, MIP1α, MIP1 (3, FLT-3L, fractalkine, and GM-CSF, or laboratory tests (e.g., analytes) chosen from C-reactive protein (CRP), ferritin, lactate dehydrogenase (LDH), aspartate aminotransferase (AST), blood urea nitrogen (BUN), alanine aminotransferase (ALT), creatinine (Cr), fibrinogen, Prothrombin Time (PT), Partial Thromboplastin Time (PTT), or a combination thereof, in a sample (e.g., a blood sample). 
     In some embodiments, a ferritin level of at least about 23,500, 25,000, 30,000, 40,000, 50,000, 70,000, 80,000, 90,000, 100,000, 150,000, 200,000, or 250,000 ng/ml, and optionally up to about 299,000 or 412,000 ng/ml, is indicative of CRS (e.g., severe CRS). In some embodiments, a ferritin level of less than about 23,500, 20,000, 18,000, 16,000, 14,000, 12,000, 10,000, 9,000, 8,000, 7,000, 6,000 5,000, 4,000, 3,000, 2,000, or 1,000 ng/ml and optionally greater than about 280 ng/ml, is indicative that the subject does not have CRS (e.g., severe CRS). 
     In some embodiments, a LDH level of at least about 1,700, 2,000, 3,000, 4,000, 5,000, 6,000, 7,000, 8,000, 9,000, 10,000, 15,000, or 20,000 U/L, and optionally up to about 24,000 U/L, is indicative of CRS (e.g., severe CRS). In some embodiments, a LDH level of less than about 1,700, 1,500, 1,400, 1,300, 1,200, 1,100, 1,000, 900, 800, 700, 600, 500, 400, 300, or 200 U/L, and optionally greater than about 159 U/L, is indicative that the subject does not have CRS (e.g., severe CRS). 
     In some embodiments, a CRP level of at least about 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, or 35 mg/dl, and optionally up to about 38 mg/dl, is indicative of CRS (severe CRS). In some embodiments, a CRP level of less than about 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 mg/dl, and optionally greater than about 0.7 mg/dl, is indicative that the subject does not have CRS (e.g., severe CRS). 
     In some embodiments, an ALT level of at least about 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 980, 900, 950, or 1000 U/L, and optionally up to 1300 U/L, is indicative of CRS (e.g., severe CRS). In some embodiments, an ALT level of less than about 100, 90, 80, 70, 60, 50, 40, or 30 U/L, and optionally greater than about 25 U/L, is indicative that the subject does not have CRS (e.g., severe CRS). 
     In some embodiments, an AST level of at least about 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 980, 900, 950, 1000 U/L, and optionally up to about 1500 U/L, is indicative of CRS (e.g., severe CRS). In some embodiments, an AST level of less than about 150, 140, 130, 120, 100, 90, 80, 70, 60, 50, 40, or 30 U/L, and optionally greater than about 15 U/L, is indicative that the subject does not have CRS (e.g., severe CRS). 
     In some embodiments, a BUN level of at least about 18, 19, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, or 190 mg/dl, and optionally up to about 210 mg/dl, is indicative of CRS (e.g., severe CRS). In some embodiments, a BUN level of less than about 18, 17, 16, 15, 14, 13, 12, 11, or 10 mg/dl, and optionally greater than about 5 mg/dl, is indicative that the subject does not have CRS (e.g., severe CRS). 
     In some embodiments, a fibrinogen level of less than about 150, 140, 130, 120, 110, 100, 90, 80, 70, 60, 50, 40, or 30 mg/dl, and optionally greater than about 20 mg/dl, is indicative of CRS (e.g., severe CRS). In some embodiments, a fibrinogen level of at least about 150, 160, 170, 180, 190, 200, or 210 mg/dl, and optionally up to about 230 mg/dl, is indicative that the subject does not have CRS (e.g., severe CRS). 
     In some embodiments, a PT level of at least about 17, 18, 19, 20, 21, or 22 sec, and optionally up to about 24 sec, is indicative of CRS (e.g., severe CRS). In some embodiments, a PT level of less than about 17, 16, 15, or 14 sec, and optionally greater than about 12 sec, is indicative that the subject does not have CRS (e.g., severe CRS). 
     In some embodiments, a PTT level of at least about 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 60, 65, 70, 75, 80, or 85 sec, and optionally up to about 95 sec, indicative of CRS (e.g., severe CRS). In some embodiments, a PTT level of less than about 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32, 31, 30, 29, 28, or 27 sec, and optionally greater than about 25 sec, is indicative that the subject does not have CRS (e.g., severe CRS). 
     In some embodiments, a patient with severe CRS has an IFN-γ&gt;75 pg/ml and IL-10&gt;60 pg/ml. In some embodiments, a patient with severe CRS has an IFN-γ of greater than or equal to 40, 50, 60, 70, or 75 pg/ml, an IL-10 level of greater than or equal to 30, 40, 50, or 60 pg/ml, or any combination thereof. 
     Additional biomarkers for evaluating a subject for having CRS or at risk of CRS are disclosed in U.S. Patent Application Publication Nos. 2019/0336504 and 2018/0252727, each of which is incorporated by reference herein in its entirety. 
     Therapeutic Antibodies 
     General 
     In certain aspects, the methods and compositions provided herein relate to the use of therapeutic antibodies (e.g., antagonistic anti-CD40 antibodies and/or bispecific CD3-binding antibodies). 
     As set forth above, as used herein, the term “antibody” encompasses both full antibody molecules and antigen-binding fragments of full antibody molecules. Non-limiting examples of antigen-binding fragments include: (i) Fab fragments; (ii) F(ab′)2 fragments; (iii) Fd fragments; (iv) Fv fragments; (v) single-chain Fv (scFv) molecules; (vi) dAb fragments; and (vii) minimal recognition units consisting of the amino acid residues that mimic the hypervariable region of an antibody (e.g., an isolated complementarity determining region (CDR) such as a CDR3 peptide), or a constrained FR3-CDR3-FR4 peptide. Other engineered molecules, such as domain-specific antibodies, single domain antibodies, domain-deleted antibodies, chimeric antibodies, CDR-grafted antibodies, diabodies, triabodies, tetrabodies, minibodies, nanobodies (e.g. monovalent nanobodies, bivalent nanobodies, etc.), small modular immunopharmaceuticals (SMIPs), and shark variable IgNAR domains, are also encompassed within the expression “antigen-binding fragment,” as used herein. 
     An antigen-binding fragment of an antibody will typically comprise at least one variable domain. The variable domain may be of any size or amino acid composition and will generally comprise at least one CDR which is adjacent to or in frame with one or more framework sequences. In antigen-binding fragments having a V H  domain associated with a V L  domain, the V H  and V L  domains may be situated relative to one another in any suitable arrangement. For example, the variable region may be dimeric and contain V H -V H , V H -V L  or V L -V L  dimers. Alternatively, the antigen-binding fragment of an antibody may contain a monomeric V H  or V L  domain. 
     In certain embodiments, an antigen-binding fragment of an antibody may contain at least one variable domain covalently linked to at least one constant domain. Non-limiting, exemplary configurations of variable and constant domains that may be found within an antigen-binding fragment of an antibody of the present invention include: (i) V H -C H 1; (ii) V H -C H 2; (iii) V H -C H 3; (iv) V H -C H 1-C H 2; (v) V H -C H 1-C H 2-C H 3; (vi) V H -C H 2-C H 3; (vii) V H -CL; (viii) V L -C H 1; (ix) V L -C H 2; (x) V L -C H 3; (xi) V L -C H 1-CH 2 ; (xii) V L -C H 1-C H 2-C H 3; (xiii) V L -C H 2-C H 3; and (xiv) V L -CL. In any configuration of variable and constant domains, including any of the exemplary configurations listed above, the variable and constant domains may be either directly linked to one another or may be linked by a full or partial hinge or linker region. A hinge region may consist of at least 2 (e.g., 5, 10, 15, 20, 40, 60 or more) amino acids which result in a flexible or semi-flexible linkage between adjacent variable and/or constant domains in a single polypeptide molecule. Moreover, an antigen-binding fragment of an antibody of the present invention may comprise a homo-dimer or hetero-dimer (or other multimer) of any of the variable and constant domain configurations listed above in non-covalent association with one another and/or with one or more monomeric V H  or V L  domain (e.g., by disulfide bond(s)). 
     As with full antibody molecules, antigen-binding fragments may be monospecific or multispecific (e.g., bispecific). A multispecific antigen-binding fragment of an antibody will typically comprise at least two different variable domains, wherein each variable domain is capable of specifically binding to a separate antigen or to a different epitope on the same antigen. Any multispecific antibody format, including the exemplary bispecific antibody formats disclosed herein, may be adapted for use in the context of an antigen-binding fragment of an antibody of the present invention using routine techniques available in the art. In certain embodiments provided herein, at least one variable domain of a multispecific antibody is capable of specifically binding to CD3. 
     In some embodiments, the antibodies provided herein may function through complement-dependent cytotoxicity (CDC) or antibody-dependent cell-mediated cytotoxicity (ADCC). “Complement-dependent cytotoxicity” (CDC) refers to lysis of antigen-expressing cells by an antibody of the invention in the presence of complement. “Antibody-dependent cell-mediated cytotoxicity” (ADCC) refers to a cell-mediated reaction in which nonspecific cytotoxic cells that express Fc receptors (FcRs) (e.g., Natural Killer (NK) cells, neutrophils, and macrophages) recognize bound antibody on a target cell and thereby lead to lysis of the target cell. CDC and ADCC can be measured using assays that are well known and available in the art. (See, e.g., U.S. Pat. Nos. 5,500,362 and 5,821,337, and Clynes et al. (1998) Proc. Natl. Acad. Sci. (USA) 95:652-656). The constant region of an antibody is important in the ability of an antibody to fix complement and mediate cell-dependent cytotoxicity. Thus, the isotype of an antibody may be selected on the basis of whether it is desirable for the antibody to mediate cytotoxicity. 
     In certain embodiments provided herein, the anti-CD40 antagonist antibodies or CD3 multispecific (e.g., bispecific or trispecific) antibodies provided herein are human antibodies. The term “human antibody,” as used herein, is intended to include antibodies having variable and constant regions derived from human germline immunoglobulin sequences. The human antibodies of the invention may include amino acid residues not encoded by human germline immunoglobulin sequences (e.g., mutations introduced by random or site-specific mutagenesis in vitro or by somatic mutation in vivo), for example in the CDRs and in particular CDR3. However, the term “human antibody”, as used herein, is not intended to include antibodies in which CDR sequences derived from the germline of another mammalian species, such as a mouse, have been grafted onto human framework sequences. 
     The antibodies provided herein, in some embodiments, may be recombinant human antibodies. The term “recombinant human antibody,” as used herein, is intended to include all human antibodies that are prepared, expressed, created or isolated by recombinant means, such as antibodies expressed using a recombinant expression vector transfected into a host cell (described further below), antibodies isolated from a recombinant, combinatorial human antibody library (described further below), antibodies isolated from an animal (e.g., a mouse) that is transgenic for human immunoglobulin genes (see e.g., Taylor et al. (1992) Nucl. Acids Res. 20:6287-6295) or antibodies prepared, expressed, created or isolated by any other means that involves splicing of human immunoglobulin gene sequences to other DNA sequences. Such recombinant human antibodies have variable and constant regions derived from human germline immunoglobulin sequences. In certain embodiments, however, such recombinant human antibodies are subjected to in vitro mutagenesis (or, when an animal transgenic for human Ig sequences is used, in vivo somatic mutagenesis) and thus the amino acid sequences of the V H  and V L  regions of the recombinant antibodies are sequences that, while derived from and related to human germline V H  and V L  sequences, may not naturally exist within the human antibody germline repertoire in vivo. 
     Human antibodies can exist in two forms that are associated with hinge heterogeneity. In one form, an immunoglobulin molecule comprises a stable four chain construct of approximately 150-160 kDa in which the dimers are held together by an interchain heavy chain disulfide bond. In a second form, the dimers are not linked via inter-chain disulfide bonds and a molecule of about 75-80 kDa is formed composed of a covalently coupled light and heavy chain (half-antibody). These forms have been extremely difficult to separate, even after affinity purification. 
     The frequency of appearance of the second form in various intact IgG isotypes is due to, but not limited to, structural differences associated with the hinge region isotype of the antibody. A single amino acid substitution in the hinge region of the human IgG4 hinge can significantly reduce the appearance of the second form (Angal et al. (1993)  Molecular Immunology  30:105) to levels typically observed using a human IgG1 hinge. The instant invention encompasses antibodies having one or more mutations in the hinge, C H 2 or C H 3 region which may be desirable, for example, in production, to improve the yield of the desired antibody form. 
     The antibodies of the invention may be isolated antibodies. An “isolated antibody,” as used herein, means an antibody that has been identified and separated and/or recovered from at least one component of its natural environment. For example, an antibody that has been separated or removed from at least one component of an organism, or from a tissue or cell in which the antibody naturally exists or is naturally produced, is an “isolated antibody” for purposes of the present invention. An isolated antibody also includes an antibody in situ within a recombinant cell. Isolated antibodies are antibodies that have been subjected to at least one purification or isolation step. According to certain embodiments, an isolated antibody may be substantially free of other cellular material and/or chemicals. 
     In certain embodiments, the methods and compositions provided herein include one-arm antibodies that bind CD40. As used herein, a “one-arm antibody” means an antigen-binding molecule comprising a single antibody heavy chain and a single antibody light chain. 
     Sequence Variants 
     In some embodiments, the anti-CD40 antagonist antibodies and/or CD3 multispecific (e.g., bispecific or trispecific) antibodies disclosed herein may comprise one or more amino acid substitutions, insertions and/or deletions in the framework and/or CDR regions of the heavy and light chain variable domains as compared to the corresponding germline sequences from which the antibodies were derived. Such mutations can be readily ascertained by comparing the amino acid sequences disclosed herein to germline sequences available from, for example, public antibody sequence databases. The present invention includes antibodies, and antigen-binding fragments thereof, which are derived from any of the amino acid sequences disclosed herein, wherein one or more amino acids within one or more framework and/or CDR regions are mutated to the corresponding residue(s) of the germline sequence from which the antibody was derived, or to the corresponding residue(s) of another human germline sequence, or to a conservative amino acid substitution of the corresponding germline residue(s) (such sequence changes are referred to herein collectively as “germline mutations”). A person of ordinary skill in the art, starting with the heavy and light chain variable region sequences disclosed herein, can easily produce numerous antibodies and antigen-binding fragments which comprise one or more individual germline mutations or combinations thereof. In certain embodiments, all of the framework and/or CDR residues within the V H  and/or V L  domains are mutated back to the residues found in the original germline sequence from which the antibody was derived. In other embodiments, only certain residues are mutated back to the original germline sequence, e.g., only the mutated residues found within the first 8 amino acids of FR1 or within the last 8 amino acids of FR4, or only the mutated residues found within CDR1, CDR2 or CDR3. In other embodiments, one or more of the framework and/or CDR residue(s) are mutated to the corresponding residue(s) of a different germline sequence (i.e., a germline sequence that is different from the germline sequence from which the antibody was originally derived). Furthermore, the antibodies of the present invention may contain any combination of two or more germline mutations within the framework and/or CDR regions, e.g., wherein certain individual residues are mutated to the corresponding residue of a particular germline sequence while certain other residues that differ from the original germline sequence are maintained or are mutated to the corresponding residue of a different germline sequence. Once obtained, antibodies and antigen-binding fragments that contain one or more germline mutations can be easily tested for one or more desired property such as, improved binding specificity, increased binding (e.g., as measured by cell binding titration or FACS binding) or binding affinity (e.g., K D ), improved or enhanced antagonistic or agonistic biological properties (as the case may be), reduced immunogenicity, etc. Antibodies and antigen-binding fragments obtained in this general manner are encompassed within the present invention. 
     In some embodiments, the anti-CD40 antagonist antibodies or CD3 multispecific (e.g., bispecific or trispecific) antibodies provided herein comprise variants of any of the HCVR, LCVR, and/or CDR amino acid sequences disclosed herein having one or more conservative substitutions. For example, in certain embodiments the anti-CD40 antagonist antibodies or CD3 multispecific (e.g., bispecific or trispecific) antibodies provided herein have HCVR, LCVR, and/or CDR amino acid sequences with, e.g., 10 or fewer, 8 or fewer, 6 or fewer, 4 or fewer, etc. conservative amino acid substitutions relative to any of the HCVR, LCVR, and/or CDR amino acid sequences disclosed herein. 
     Fc Variants 
     According to certain embodiments provided herein, antibodies and multispecific antigen-binding molecules are provided comprising an Fc domain comprising one or more mutations which enhance or diminish antibody binding to the FcRn receptor, e.g., at acidic pH as compared to neutral pH. For example, the present invention includes antibodies comprising a mutation in the C H 2 or a C H 3 region of the Fc domain, wherein the mutation(s) increases the affinity of the Fc domain to FcRn in an acidic environment (e.g., in an endosome where pH ranges from about 5.5 to about 6.0). Such mutations may result in an increase in serum half-life of the antibody when administered to an animal. Non-limiting examples of such Fc modifications include, e.g., a modification at position 250 (e.g., E or Q); 250 and 428 (e.g., L or F); 252 (e.g., L/Y/F/W or T), 254 (e.g., S or T), and 256 (e.g., S/R/Q/E/D or T); or a modification at position 428 and/or 433 (e.g., H/L/R/S/P/Q or K) and/or 434 (e.g., H/F or Y); or a modification at position 250 and/or 428; or a modification at position 307 or 308 (e.g., 308F, V308F), and 434. In one embodiment, the modification comprises a 428L (e.g., M428L) and 434S (e.g., N434S) modification; a 428L, 259I (e.g., V259I), and 308F (e.g., V308F) modification; a 433K (e.g., H433K) and a 434 (e.g., 434Y) modification; a 252, 254, and 256 (e.g., 252Y, 254T, and 256E) modification; a 250Q and 428L modification (e.g., T250Q and M428L); and a 307 and/or 308 modification (e.g., 308F or 308P). 
     For example, the present invention includes CD3 multispecific antigen-binding molecules (e.g., anti-CD3/anti-MUC16 bispecific, anti-BCMA×anti-CD3, or anti-CD3/anti-CD20 bispecific antibodies), comprising an Fc domain comprising one or more pairs or groups of mutations selected from the group consisting of: 250Q and 248L (e.g., T250Q and M248L); 252Y, 254T and 256E (e.g., M252Y, S254T and T256E); 428L and 434S (e.g., M428L and N434S); and 433K and 434F (e.g., H433K and N434F). All possible combinations of the foregoing Fc domain mutations, and other mutations within the antibody variable domains disclosed herein, are contemplated within the scope of the present invention. 
     Bioequivalents 
     Provided herein antigen-binding molecules having amino acid sequences that vary from those of the exemplary molecules disclosed herein but that retain the ability to bind the same antigen or antigens. Such variant molecules may comprise one or more additions, deletions, or substitutions of amino acids when compared to parent sequence, but exhibit biological activity that is essentially equivalent to that of the described bispecific antigen-binding molecules. 
     The present invention includes antigen-binding molecules that are bioequivalent to any of the exemplary antigen-binding molecules set forth herein. Two antigen-binding proteins, or antibodies, are considered bioequivalent if, for example, they are pharmaceutical equivalents or pharmaceutical alternatives whose rate and extent of absorption do not show a significant difference when administered at the same molar dose under similar experimental conditions, either single does or multiple dose. Some antigen-binding proteins will be considered equivalents or pharmaceutical alternatives if they are equivalent in the extent of their absorption but not in their rate of absorption and yet may be considered bioequivalent because such differences in the rate of absorption are intentional and are reflected in the labeling, are not essential to the attainment of effective body drug concentrations on, e.g., chronic use, and are considered medically insignificant for the particular drug product studied. 
     In one embodiment, two antigen-binding proteins are bioequivalent if there are no clinically meaningful differences in their safety, purity, and potency. 
     In one embodiment, two antigen-binding proteins are bioequivalent if a patient can be switched one or more times between the reference product and the biological product without an expected increase in the risk of adverse effects, including a clinically significant change in immunogenicity, or diminished effectiveness, as compared to continued therapy without such switching. 
     In one embodiment, two antigen-binding proteins are bioequivalent if they both act by a common mechanism or mechanisms of action for the condition or conditions of use, to the extent that such mechanisms are known. 
     Bioequivalence may be demonstrated by in vivo and in vitro methods. Bioequivalence measures include, e.g., (a) an in vivo test in humans or other mammals, in which the concentration of the antibody or its metabolites is measured in blood, plasma, serum, or other biological fluid as a function of time; (b) an in vitro test that has been correlated with and is reasonably predictive of human in vivo bioavailability data; (c) an in vivo test in humans or other mammals in which the appropriate acute pharmacological effect of the antibody (or its target) is measured as a function of time; and (d) in a well-controlled clinical trial that establishes safety, efficacy, or bioavailability or bioequivalence of an antigen-binding protein. 
     Bioequivalent variants of the exemplary bispecific antigen-binding molecules set forth herein may be constructed by, for example, making various substitutions of residues or sequences or deleting terminal or internal residues or sequences not needed for biological activity. For example, cysteine residues not essential for biological activity can be deleted or replaced with other amino acids to prevent formation of unnecessary or incorrect intramolecular disulfide bridges upon renaturation. In other contexts, bioequivalent antigen-binding proteins may include variants of the exemplary bispecific antigen-binding molecules set forth herein comprising amino acid changes which modify the glycosylation characteristics of the molecules, e.g., mutations which eliminate or remove glycosylation. 
     Antibody Binding 
     As used herein, the term “binding” in the context of the binding of an antibody, immunoglobulin, antibody-binding fragment, or Fc-containing protein to either, e.g., a predetermined antigen, such as a cell surface protein or fragment thereof, typically refers to an interaction or association between a minimum of two entities or molecular structures, such as an antibody-antigen interaction. 
     For instance, binding affinity typically corresponds to a K D  value of about 10 −7  M or less, such as about 10 −8  M or less, such as about 10 −9  M or less when determined by, for instance, surface plasmon resonance (SPR) technology in a BIAcore 3000 instrument using the antigen as the ligand and the antibody, Ig, antibody-binding fragment, or Fc-containing protein as the analyte (or antiligand). Cell-based binding strategies, such as fluorescent-activated cell sorting (FACS) binding assays, are also routinely used, and FACS data correlates well with other methods such as radioligand competition binding and SPR (Benedict, C A,  J Immunol Methods.  1997, 201(2):223-31; Geuijen, C A, et al.  J Immunol Methods.  2005, 302(1-2):68-77). 
     Accordingly, the antibody or antigen-binding protein provided herein binds to the predetermined antigen or cell surface molecule (receptor) having an affinity corresponding to a K D  value that is at least ten-fold lower than its affinity for binding to a non-specific antigen (e.g., BSA, casein). According to the present invention, the affinity of an antibody corresponding to a K D  value that is equal to or less than ten-fold lower than a non-specific antigen may be considered non-detectable binding, however such an antibody may be paired with a second antigen binding arm for the production of a bispecific antibody of the invention. 
     The term “K D ” (M) refers to the dissociation equilibrium constant of a particular antibody-antigen interaction, or the dissociation equilibrium constant of an antibody or antibody-binding fragment binding to an antigen. There is an inverse relationship between K D  and binding affinity, therefore the smaller the K D  value, the higher, i.e. stronger, the affinity. Thus, the terms “higher affinity” or “stronger affinity” relate to a higher ability to form an interaction and therefore a smaller K D  value, and conversely the terms “lower affinity” or “weaker affinity” relate to a lower ability to form an interaction and therefore a larger K D  value. In some circumstances, a higher binding affinity (or K D ) of a particular molecule (e.g. antibody) to its interactive partner molecule (e.g. antigen X) compared to the binding affinity of the molecule (e.g. antibody) to another interactive partner molecule (e.g. antigen Y) may be expressed as a binding ratio determined by dividing the larger K D  value (lower, or weaker, affinity) by the smaller K D  (higher, or stronger, affinity), for example expressed as 5-fold or 10-fold greater binding affinity, as the case may be. 
     The term “k d ” (sec-1 or 1/s) refers to the dissociation rate constant of a particular antibody-antigen interaction, or the dissociation rate constant of an antibody or antibody-binding fragment. Said value is also referred to as the k off  value. 
     The term “k a ” (M-1×sec-1 or 1/M) refers to the association rate constant of a particular antibody-antigen interaction, or the association rate constant of an antibody or antibody-binding fragment. 
     The term “K A ” (M-1 or 1/M) refers to the association equilibrium constant of a particular antibody-antigen interaction, or the association equilibrium constant of an antibody or antibody-binding fragment. The association equilibrium constant is obtained by dividing the k a  by the k d . 
     The term “EC50” or “EC 50 ” refers to the half maximal effective concentration, which includes the concentration of an antibody which induces a response halfway between the baseline and maximum after a specified exposure time. The EC 50  essentially represents the concentration of an antibody where 50% of its maximal effect is observed. In certain embodiments, the EC 50  value equals the concentration of an antibody of the invention that gives half-maximal binding to cells expressing CD3 or tumor-associated antigen (e.g., CD123, STEAP2, CD20, PSMA, SSTR2, CD38, STEAP1, 5T4, ENPP3, MUC16, or BCMA), as determined by e.g. a FACS binding assay. Thus, reduced or weaker binding is observed with an increased EC 50 , or half maximal effective concentration value. 
     In one embodiment, decreased binding of CD3 multispecific antibodies can be defined as an increased EC 50  antibody concentration which enables binding to the half-maximal amount of target cells. 
     In another embodiment, the EC 50  value represents the concentration of a CD3 multispecific antibody of the invention that elicits half-maximal depletion of target cells by T cell cytotoxic activity. Thus, increased cytotoxic activity (e.g. T cell-mediated tumor cell killing) is observed with a decreased EC 50 , or half maximal effective concentration value. 
     pH-Dependent Binding 
     In some embodiments, the present invention includes antibodies and multispecific antigen-binding molecules with pH-dependent binding characteristics. For example, a CD3 multispecific antibody of the present invention may exhibit reduced binding to CD3 at acidic pH as compared to neutral pH. Alternatively, CD3 multispecific antibodies of the invention may exhibit enhanced binding to CD3 at acidic pH as compared to neutral pH. The expression “acidic pH” includes pH values less than about 6.2, e.g., about 6.0, 5.95, 5.9, 5.85, 5.8, 5.75, 5.7, 5.65, 5.6, 5.55, 5.5, 5.45, 5.4, 5.35, 5.3, 5.25, 5.2, 5.15, 5.1, 5.05, 5.0, or less. As used herein, the expression “neutral pH” means a pH of about 7.0 to about 7.4. The expression “neutral pH” includes pH values of about 7.0, 7.05, 7.1, 7.15, 7.2, 7.25, 7.3, 7.35, and 7.4. 
     In certain instances, “reduced binding . . . at acidic pH as compared to neutral pH” is expressed in terms of a ratio of the K D  value of the antibody binding to its antigen at acidic pH to the K D  value of the antibody binding to its antigen at neutral pH (or vice versa). For example, a CD3 multispecific antibody or antigen-binding fragment thereof may be regarded as exhibiting “reduced binding to CD3 at acidic pH as compared to neutral pH” for purposes of the present invention if the CD3 multispecific antibody or antigen-binding fragment thereof exhibits an acidic/neutral K D  ratio of about 3.0 or greater. In certain exemplary embodiments, the acidic/neutral K D  ratio for an antibody or antigen-binding fragment of the present invention can be about 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10.0, 10.5, 11.0, 11.5, 12.0, 12.5, 13.0, 13.5, 14.0, 14.5, 15.0, 20.0. 25.0, 30.0, 40.0, 50.0, 60.0, 70.0, 100.0 or greater. 
     Antibodies with pH-dependent binding characteristics may be obtained, e.g., by screening a population of antibodies for reduced (or enhanced) binding to a particular antigen at acidic pH as compared to neutral pH. Additionally, modifications of the antigen-binding domain at the amino acid level may yield antibodies with pH-dependent characteristics. For example, by substituting one or more amino acids of an antigen-binding domain (e.g., within a CDR) with a histidine residue, an antibody with reduced antigen-binding at acidic pH relative to neutral pH may be obtained. 
     Preparation of Antigen-Binding Domains and Construction of Multispecific Molecules 
     Antigen-binding domains specific for particular antigens can be prepared by any antibody generating technology known in the art. Once obtained, two different antigen-binding domains, specific for two different antigens (e.g., CD3 and a human tumor antigen (e.g., MUC16, BCMA, CD20, etc.)), can be appropriately arranged relative to one another to produce a bispecific antigen-binding molecule of the present invention using routine methods. In certain embodiments, one or more of the individual components (e.g., heavy and light chains) of the multispecific antigen-binding molecules of the invention are derived from chimeric, humanized or fully human antibodies. Methods for making such antibodies are well known in the art. For example, one or more of the heavy and/or light chains of the bispecific antigen-binding molecules of the present invention can be prepared using VELOCIMMUNE™ technology. Using VELOCIMMUNE™ technology (or any other human antibody generating technology), high affinity chimeric antibodies to a particular antigen (e.g., CD3 or human tumor antigen (e.g., MUC16, BCMA, CD20, etc.)) are initially isolated having a human variable region and a mouse constant region. The antibodies are characterized and selected for desirable characteristics, including affinity, selectivity, epitope, etc. The mouse constant regions are replaced with a desired human constant region to generate fully human heavy and/or light chains that can be incorporated into the bispecific antigen-binding molecules of the present invention. 
     Genetically engineered animals may be used to make human bispecific antigen-binding molecules. For example, a genetically modified mouse can be used which is incapable of rearranging and expressing an endogenous mouse immunoglobulin light chain variable sequence, wherein the mouse expresses only one or two human light chain variable domains encoded by human immunoglobulin sequences operably linked to the mouse kappa constant gene at the endogenous mouse kappa locus. Such genetically modified mice can be used to produce fully human bispecific antigen-binding molecules comprising two different heavy chains that associate with an identical light chain that comprises a variable domain derived from one of two different human light chain variable region gene segments. (See, e.g., US 2011/0195454). Fully human refers to an antibody, or antigen-binding fragment or immunoglobulin domain thereof, comprising an amino acid sequence encoded by a DNA derived from a human sequence over the entire length of each polypeptide of the antibody or antigen-binding fragment or immunoglobulin domain thereof. In some instances, the fully human sequence is derived from a protein endogenous to a human. In other instances, the fully human protein or protein sequence comprises a chimeric sequence wherein each component sequence is derived from human sequence. While not being bound by any one theory, chimeric proteins or chimeric sequences are generally designed to minimize the creation of immunogenic epitopes in the junctions of component sequences, e.g. compared to any wild-type human immunoglobulin regions or domains. 
     CD40 Antagonists 
     In certain aspects, provided herein are methods of treating cancer and/or inhibiting cytokine release by administering to a subject (e.g., a subject in need thereof) a CD40 antagonist. 
     The term “CD40 antagonist” refers to any agent that inhibits or blocks a CD40-mediated effect. It may be a small molecule, an antibody, an antisense oligonucleotide, a siRNA, a shRNA, a sgRNA, a peptide, etc. In some embodiments, the CD40 antagonist is an antibody (e.g., an antigen binding antibody fragment) that binds to CD40. The “antagonistic” effect of the anti-CD40 antibody means the effect of inhibiting the binding of CD40 expressed in the surface of cells such as B cells, tumor cells, or dendritic cells with its ligands or the effect of neutralizing one or more of influences of CD40 ligands on CD40-expressing cells. An “antagonistic antibody” means an antibody that has such effects. One example of the influences on CD40-expressing cells includes the suppression of B cell growth or the suppression of antibody production. 
     In some embodiments, the CD40 antagonist antibody (e.g., an antigen binding antibody fragment) targets the CD40 receptor and interfere with CD40 signaling, particularly CD40 signaling pathways that are mediated by interaction of CD40 with the CD40 ligand (CD40L). The term “CD40 antigen,” “CD40 cell surface antigen,” “CD40 receptor,” or “CD40” refers to a transmembrane glycoprotein that belongs to the tumor necrosis factor (TNF) receptor family (see, for example, U.S. Pat. Nos. 5,674,492 and 4,708,871; Stamenkovic et al. (1989) EMBO 8:1403; Clark (1990) Tissue Antigens 36:33; Barclay et al. (1997) The Leucocyte Antigen Facts Book (2d ed.; Academic Press, San Diego)). At least six isoforms of human CD40, encoded by alternatively spliced transcript variants of this gene, have been identified (NM_001250.6 and NP_001241.1; NM_001302753.2 and NP_001289682.1; NM_001322421.2 and NP_001309350.1; NM_001322422.2 and NP_001309351.1; NM_001362758.2 and NP_001349687.1; and NM_152854.4 and NP_690593.1). For purposes of the present invention, the term “CD40 antigen,” “CD40 cell surface antigen,” “CD40 receptor,” or “CD40” encompasses all isoforms of CD40. 
     The CD40 antigen can be displayed on the surface of a variety of cell types, as described elsewhere herein. The term “displayed on the surface” and “expressed on the surface” refers to instances in which all or a portion of the CD40 antigen is exposed to the exterior of the cell. The displayed or expressed CD40 antigen may be fully or partially glycosylated. 
     By “antagonist activity” is intended that the substance functions as an antagonist. An antagonist of CD40 prevents or reduces induction of any of the responses induced by binding of the CD40 receptor to an agonist ligand, particularly CD40L. The antagonist may reduce induction of any one or more of the responses to agonist binding by 5%, 10%, 15%, 20%, 25%, 30%, 35%, preferably 40%, 45%, 50%, 55%, 60%, more preferably 70%, 80%, 85%, and most preferably 90%, 95%, 99%, or 100%. Methods for measuring CD40 ligand binding specificity and antagonist activity of an anti-CD40 therapeutic agent, for example, an anti-CD40 antibody, are known in the art and include, but are not limited to, standard competitive binding assays, assays for monitoring immunoglobulin secretion by B cells, B cell proliferation assays, Banchereau-Like-B cell proliferation assays, T cell helper assays for antibody production, co-stimulation of B cell proliferation assays, and assays for up-regulation of B cell activation markers. See, for example, such assays disclosed in WO 00/75348 and U.S. Pat. No. 6,087,329, herein incorporated by reference. Also see, provisional applications entitled “Antagonist Anti-CD40 Monoclonal Antibodies and Methods for Their Use,” filed Nov. 4, 2003, Nov. 26, 2003, and Apr. 27, 2004, and assigned U.S. Patent Application Nos. 60/517,337, 60/525,579, and 60/565,710, respectively, and International Patent Application No. PCT/US2004/037152, also entitled “Antagonist Anti-CD40 Monoclonal Antibodies and Methods for Their Use,” filed Nov. 4, 2004, and published as WO 2005/044854); the contents of each of which are herein incorporated by reference in their entirety. 
     Any of the assays known in the art can be used to determine whether an anti-CD40 antibody acts as an antagonist of one or more B cell responses. In some embodiments, the anti-CD40 antibody acts as an antagonist of at least one B cell response selected from the group consisting of B cell proliferation, B cell differentiation, antibody production, intercellular adhesion, B cell memory generation, isotype switching, up-regulation of cell-surface expression of MHC Class II and CD80/86, and secretion of pro-inflammatory cytokines such as IL-8, IL-12, and TNF. Of particular interest are antagonist anti-CD40 antibodies that free of significant agonist activity with respect to B cell proliferation when bound to the human CD40 antigen on the surface of a human B cell. 
     The term “CD40 ligand” includes any peptide, polypeptide, or protein that can bind to and activate one or more CD40 signaling pathways. Thus, “CD40 ligands” include, but are not limited to, full-length CD40 ligand proteins and variants and fragments thereof that retain sufficient activity to carry out the function of binding to and stimulating CD40 signaling on CD40-expressing cells. Modifications to a native CD40 ligand, for example, human CD40 ligand (CD40L; also known as CD154), include, but are not limited to, substitutions, deletions, truncations, extensions, fusion proteins, fragments, peptidomimetics, and the like. In some embodiments of the invention, an assay for assessing biological activity of an antagonist anti-CD40 antibody includes the use of soluble CD40L, for example, soluble recombinant human CD40L (Alexis Corporation, Bingham, Nottinghamshire, UK) to stimulate CD40 signaling on CD40-expressing cells. 
     “CD40L-mediated CD40 signaling” refers to any of the biological activities that result from interaction of the cell-surface receptor CD40 with a CD40 ligand. Examples of CD40 signaling are signals that lead to proliferation and survival of CD40-expressing cells, and stimulation of one or more CD40-signaling pathways within CD40-expressing cells. A CD40 “signaling pathway” or “signal transduction pathway” is intended to mean at least one biochemical reaction, or a group of biochemical reactions, that results from interaction of the CD40 receptor with a CD40 ligand, for example, CD40L, and which generates a signal that, when transmitted through the signal pathway, leads to activation of one or more downstream molecules in the signaling cascade. Signal transduction pathways involve a number of signal transduction molecules that lead to transmission of a signal from the cell-surface CD40 receptor across the plasma membrane of a cell, and through one or more in a series of signal transduction molecules, through the cytoplasm of the cell, and in some instances, into the cell&#39;s nucleus. CD40 signal transduction pathways include, for example, the AKT signaling pathway, which leads to activation of AKT, and ultimately activation of NF-κB via the NF-κB signaling pathway; and mitogen-activated protein kinase (MAPK) signaling pathways, including the MEK/ERK signaling pathway and the MEK/p38 signaling pathway, which lead to activation of ERK and p38, respectively. The balance between activation and blocking of these signaling pathways favors either cell survival or apoptosis. 
     In some embodiments, the CD40 antagonist antibody is a monoclonal antibody. In certain embodiments, the CD40 antagonist antibody or antigen-binding fragment thereof is chimeric, humanized, composite, murine, or human. In some embodiments, the CD40 antagonist antibody or antigen-binding fragment thereof is selected from Fv, Fav, F(ab′)2), Fab′, dsFv, scFv, sc(Fv)2, and diabodies fragments. 
     CD40 antagonist antibodies provided herein include but are not limited to, e.g., iscalimab (also known as CFZ533) disclosed in Kahaly et al. (2019)  J. Endocr. Sco.  3:doi.org/10.1210/js.2019-0R19-6, Fisher et al. (2017)  Arthritis Rheumatol.  69:1784, Farkash et al. (2019)  Am. J. Transplant.  19:632, and International Patent Application Publication No. WO 2012/075111A1; ravagalimab (also known as ABBV-323) disclosed in International Patent Application Publication No. WO 2016/196314A1; BI 655064 disclosed in Visvannathan et al. (2016)  Arthritis Rheumatol.  68:1588); bleselumab (also known as ASKP1240 or 341G2) disclosed in Anil et al. (2018)  Biopharm. Drug Dispos.  39:245-255, Harland et al. (2017)  Am. J. Transplant.  17:159-171, and U.S. Pat. No. 8,716,451B2; ch5D12 disclosed in Kasran et al. (2005)  Aliment. Pharmacol. Ther.  22:111-122; lucatumumab (also known as HCD122 or CHIR-12.12) disclosed in Bensinger et al. (2012)  British J. Haematology  159:58-66, Byrd et al. (2012)  Leuk. Lymphoma  53:10.3109/10428194.2012.681655, and International Patent Application No. PCT/US2004/037152; CHIR-5.9 disclosed in International Patent Application No. PCT/US2004/037152; 201A3 disclosed in Perper et al. (2019)  J. Immunol.  203:58-75; KPL-404 disclosed in clinical trial NCT04497662 sponsored by Kiniksa Pharmaceuticals, Ltd.; PG102 disclosed in Bankert et al. (2015)  J. Immunol.  194:4319-4327 and International Patent Application Publication No. WO 2001/024823A1; and BIIB063 disclosed in Musselli et al. (2017) 2017 ACR/ARHP Annual Meeting Abstract, the contents of each of which are herein incorporated by reference in their entirety. 
     Additional CD40 antagonist antibodies useful in certain embodiments of the methods and compositions provided herein are disclosed in, for example, International Patent Application Publication Nos. WO 02/11763A1, WO 02/28481A9, WO 03/045978A3, WO 03/029296A1, WO 03/028809A1, WO 2005/044854, WO 2006/073443A3, WO 2007/124299A8, WO 2011/123489A3, WO 2016/196,314A1, WO 2017/040566A1, WO 2017/060242A1, WO 2018/217976A1, WO2019/156565A1, WO 2020/144605A1, WO 2020/106620A1, and WO 2020/006347A1, U.S. Patent Application Publication Nos. US 2020/0291123A1, US 2017/0158771A1, and US 2008/0057070A1, or U.S. Pat. No. 9,125,893B2, U.S. Pat. No. 8,669,352B2, and U.S. Pat. No. 9,598,494B2, the contents of each of which are herein incorporated by reference in their entirety. 
     The anti-CD40 antagonist antibodies disclosed herein may comprise one or more amino acid substitutions, insertions and/or deletions in the framework and/or CDR regions of the heavy and light chain variable domains as compared to the corresponding germline sequences from which the antibodies were derived. Such mutations can be readily ascertained by comparing the amino acid sequences disclosed herein to germline sequences available from, for example, public antibody sequence databases. The present invention includes antibodies, and antigen-binding fragments thereof, which are derived from any of the amino acid sequences disclosed herein, wherein one or more amino acids within one or more framework and/or CDR regions are mutated to the corresponding residue(s) of the germline sequence from which the antibody was derived, or to the corresponding residue(s) of another human germline sequence, or to a conservative amino acid substitution of the corresponding germline residue(s) (such sequence changes are referred to herein collectively as “germline mutations”). A person of ordinary skill in the art, starting with the heavy and light chain variable region sequences disclosed herein, can easily produce numerous antibodies and antigen-binding fragments which comprise one or more individual germline mutations or combinations thereof. In certain embodiments, all of the framework and/or CDR residues within the V H  and/or V L  domains are mutated back to the residues found in the original germline sequence from which the antibody was derived. In other embodiments, only certain residues are mutated back to the original germline sequence, e.g., only the mutated residues found within the first 8 amino acids of FR1 or within the last 8 amino acids of FR4, or only the mutated residues found within CDR1, CDR2 or CDR3. In other embodiments, one or more of the framework and/or CDR residue(s) are mutated to the corresponding residue(s) of a different germline sequence (i.e., a germline sequence that is different from the germline sequence from which the antibody was originally derived). Furthermore, the antibodies of the present invention may contain any combination of two or more germline mutations within the framework and/or CDR regions, e.g., wherein certain individual residues are mutated to the corresponding residue of a particular germline sequence while certain other residues that differ from the original germline sequence are maintained or are mutated to the corresponding residue of a different germline sequence. Once obtained, antibodies and antigen-binding fragments that contain one or more germline mutations can be easily tested for one or more desired property such as, improved binding specificity, increased binding (e.g., as measured by cell binding titration or FACS binding) or binding affinity (e.g., K D ), improved or enhanced antagonistic or agonistic biological properties (as the case may be), reduced immunogenicity, etc. Antibodies and antigen-binding fragments obtained in this general manner are encompassed within the present invention. 
     Provided herein are also anti-CD40 antagonist antibodies comprising variants of any of the HCVR, LCVR, and/or CDR amino acid sequences disclosed herein having one or more conservative substitutions. For example, the present invention includes anti-CD40 antagonist antibodies or CD3 multispecific (e.g., bispecific or trispecific) antibodies having HCVR, LCVR, and/or CDR amino acid sequences with, e.g., 10 or fewer, 8 or fewer, 6 or fewer, 4 or fewer, etc. conservative amino acid substitutions relative to any of the HCVR, LCVR, and/or CDR amino acid sequences disclosed herein. 
     CAR-T Cell Expressing CD40 Antagonist 
     In certain aspects, the methods and compositions provided herein relate to immune effector cells (e.g., CAR-T cell) that are engineered to express a CD40 Antagonist (e.g., a CD40 antagonist provided herein). In some embodiments, the CAR-T cell secretes the CD40 antagonist. In certain embodiments, the CD40 antagonist is a scFv or Fab. In some embodiments, the CAR-T cell expresses the CD40 antagonist when it is activated. Methods for generating CAR-T cell that secrete an antibody or an antigen binding fragment thereof are disclosed in, e.g., Choi et al. (2019) Nature Biotechnology 37:1049-1058, which is incorporate by reference herein in its entirety. 
     CAR-T cells are T cells that engineered to express a chimeric antigen receptor (CAR) polypeptide. CARs are receptors comprising a targeting moiety that is associated with one or more signaling domains and/or costimulatory domains in a single fusion molecule. In certain embodiments, the binding moiety of a CAR comprises an antigen-binding domain of a single-chain antibody (scFv), comprising the light and heavy chain variable fragments of a monoclonal antibody joined by a flexible linker. In certain embodiments, the binding moiety further comprises transmembrane and hinge domains of a monoclonal antibody. In certain embodiments, the binding domain and/or extracellular domain of a CAR provided herein provides the CAR with the ability to bind to the target antigen of interest (e.g., a tumor antigen). 
     A “signal transducing domain” or “signaling domain” of a CAR, as used herein, is responsible for intracellular signaling following the binding of an extracellular ligand binding domain to the target resulting in the activation of the immune cell and immune response. In other words, the signal transducing domain is responsible for the activation of at least one of the normal effector functions of the immune cell in which the CAR is expressed. For example, the effector function of a T cell can be a cytolytic activity or helper activity including the secretion of cytokines. Thus, the term “signal transducing domain” refers to the portion of a protein which transduces the effector function signal and directs the cell to perform a specialized function. Examples of signal transducing domains for use in a CAR can be the cytoplasmic sequences of the T cell receptor and co-receptors that act in concert to initiate signal transduction following antigen receptor engagement, as well as any derivate or variant of these sequences and any synthetic sequence that has the same functional capability. In some cases, signaling domains comprise two distinct classes of cytoplasmic signaling sequences, those that initiate antigen-dependent primary activation, and those that act in an antigen-independent manner to provide a secondary or co-stimulatory signal. Primary cytoplasmic signaling sequences can comprise signaling motifs which are known as immunoreceptor tyrosine-based activation motifs of ITAMs. ITAMs are well defined signaling motifs found in the intracytoplasmic tail of a variety of receptors that serve as binding sites for syk/zap70 class tyrosine kinases. Exemplary ITAMs include those derived from TCRζ, FcRγ, FcRβ, FcRε, CD3γ, CD3δ, CD3ε, CD5, CD22, CD79a, CD79b and CD66d. 
     In some embodiments, the cells are obtained from the subject to be treated (i.e., are autologous). However, in certain embodiments, immune effector cell lines or donor effector cells (allogeneic) are used. 
     Immune effector cells can be obtained from a number of sources, including peripheral blood mononuclear cells, bone marrow, lymph node tissue, cord blood, thymus tissue, tissue from a site of infection, ascites, pleural effusion, spleen tissue, and tumors. Immune effector cells can be obtained from blood collected from a subject using any number of techniques known to the skilled artisan, such as Ficoll™ separation. For example, cells from the circulating blood of an individual may be obtained by apheresis. In some embodiments, immune effector cells are isolated from peripheral blood lymphocytes by lysing the red blood cells and depleting the monocytes, for example, by centrifugation through a PERCOLL™ gradient or by counterflow centrifugal elutriation. A specific subpopulation of immune effector cells can be further isolated by positive or negative selection techniques. For example, immune effector cells can be isolated using a combination of antibodies directed to surface markers unique to the positively selected cells, e.g., by incubation with antibody-conjugated beads for a time period sufficient for positive selection of the desired immune effector cells. Alternatively, enrichment of immune effector cells population can be accomplished by negative selection using a combination of antibodies directed to surface markers unique to the negatively selected cells. 
     The present disclosure provides methods for making the immune effector cells which express the CARs and CD40 antagonists described herein. In one embodiment, the method comprises transfecting or transducing immune effector cells isolated from a subject, such as a subject having a PIG and/or low density cancer antigen expressing tumor cell, such that the immune effector cells express one or more CAR and CD40 antagonist as described herein. In certain embodiments, the immune effector cells are isolated from an individual and genetically modified without further manipulation in vitro. Such cells can then be directly re-administered into the individual. In further embodiments, the immune effector cells are first activated and stimulated to proliferate in vitro prior to being genetically modified to express a CAR and a CD40 antagonist. In this regard, the immune effector cells may be cultured before or after being genetically modified (i.e., transduced or transfected to express a CAR or a CD40 antagonist as described herein). 
     Prior to in vitro manipulation or genetic modification of the immune effector cells described herein, the source of cells may be obtained from a subject. In particular, the immune effector cells for use with the CARs and CD40 antagonists as described herein comprise T cells. T cells can be obtained from a number of sources, including peripheral blood mononuclear cells, bone marrow, lymph nodes tissue, cord blood, thymus issue, tissue from a site of infection, ascites, pleural effusion, spleen tissue, and tumors. In certain embodiments, T cell can be obtained from a unit of blood collected from the subject using any number of techniques known to the skilled person, such as FICOLL separation. In one embodiment, cells from the circulating blood of an individual are obtained by apheresis. The apheresis product typically contains lymphocytes, including T cells, monocytes, granulocyte, B cells, other nucleated white blood cells, red blood cells, and platelets. In one embodiment, the cells collected by apheresis may be washed to remove the plasma fraction and to place the cells in an appropriate buffer or media for subsequent processing. In one embodiment, the cells are washed with PBS. In an alternative embodiment, the washed solution lacks calcium, and may lack magnesium or may lack many, if not all, divalent cations. As would be appreciated by those of ordinary skill in the art, a washing step may be accomplished by methods known to those in the art, such as by using a semiautomated flowthrough centrifuge. After washing, the cells may be resuspended in a variety of biocompatible buffers or other saline solution with or without buffer. In certain embodiments, the undesirable components of the apheresis sample may be removed in the cell directly resuspended culture media. 
     In certain embodiments, T cells are isolated from peripheral blood mononuclear cells (PBMCs) by lysing the red blood cells and depleting the monocytes, for example, by centrifugation through a Ficoll-Paque™ gradient. A specific subpopulation of T cells, such as CD28+, CD4+, CD8+, CD45RA+, and CD45RO+ T cells, can be further isolated by positive or negative selection techniques. For example, enrichment of a T cell population by negative selection can be accomplished with a combination of antibodies directed to surface markers unique to the negatively selected cells. One method for use herein is cell sorting and/or selection via negative magnetic immunoadherence or flow cytometry that uses a cocktail of monoclonal antibodies directed to cell surface markers present on the cells negatively selected. For example, to enrich for CD4+ cells by negative selection, a monoclonal antibody cocktail typically includes antibodies to CD14, CD20, CD1 b, CD16, HLA-DR, and CD8. Flow cytometry and cell sorting may also be used to isolate cell populations of interest. 
     PBMCs may be used directly for genetic modification with the CARs and CD40 antagonists using methods as described herein. In certain embodiments, after isolation of PBMC, T lymphocytes are further isolated and in certain embodiments, both cytotoxic and helper T lymphocytes can be sorted into naive, memory, and effector T cell subpopulations either before or after genetic modification and/or expansion. CD8+ cells can be obtained by using standard methods. In some embodiments, CD8+ cells are further sorted into naive, central memory, and effector cells by identifying cell surface antigens that are associated with each of those types of CD8+ cells. In embodiments, memory T cells are present in both CD62L+ and CD62L-subsets of CD8+ peripheral blood lymphocytes. PBMC are sorted into CD62L-CD8+ and CD62L+CD8+ fractions after staining with anti-CD8 and anti-CD62L antibodies. In some embodiments, the expression of phenotypic markers of central memory TCM include CD45RO, CD62L, CCR7, CD28, CD3, and CD127 and are negative for granzyme B. In some embodiments, central memory T cells are CD45RO+, CD62L+, CD8+ T cells. In some embodiments, effector T cells are negative for CD62L, CCR7, CD28, and CD127, and positive for granzyme B and perforin. In some embodiments, naive CD8+T lymphocytes are characterized by the expression of phenotypic markers of naive T cells including CD62L, CCR7, CD28, CD3, CD 127, and CD45RA. 
     In certain embodiments, CD4+ T cells are further sorted into subpopulations. For example, CD4+T helper cells can be sorted into naive, central memory, and effector cells by identifying cell populations that have cell surface antigens. CD4+ lymphocytes can be obtained by standard methods. In some embodiments, naive CD4+T lymphocytes are CD45RO−, CD45RA+, CD62L+CD4+ T cell. In some embodiments, central memory CD4+ cells are CD62L positive and CD45RO positive. In some embodiments, effector CD4+ cells are CD62L and CD45RO negative. 
     The immune effector cells, such as T cells, can be genetically modified following isolation using known methods, or the immune effector cells can be activated and expanded (or differentiated in the case of progenitors) in vitro prior to being genetically modified. In another embodiment, the immune effector cells, such as T cells, are genetically modified with the chimeric antigen receptors described herein (e.g., transduced with a viral vector comprising a nucleic acid encoding a CAR or a CD40 antagonist) and then are activated and expanded in vitro. Methods for activating and expanding T cells are known in the art and are described, for example, in U.S. Pat. Nos. 6,905,874; 6,867,041; 6,797,514; WO2012079000. Generally, such methods include contacting PBMC or isolated T cells with a stimulatory agent and costimulatory agent, such as anti-CD3 and anti-CD28 antibodies, generally attached to a bead or other surface, in a culture medium with appropriate cytokines, such as IL-2 (e.g., recombinant human IL-2). Anti-CD3 and anti-CD28 antibodies attached to the same bead serve as a “surrogate” antigen presenting cell (APC). In other embodiments, the T cells may be activated and stimulated to proliferate with feeder cells and appropriate antibodies and cytokines using methods such as those described in U.S. Pat. Nos. 6,040,177; 5,827,642; and WO2012129514. 
     In some embodiments, the immune effector cells comprise any leukocyte involved in defending the body against infectious disease and foreign materials. For example, the immune effector cells can comprise lymphocytes, monocytes, macrophages, dendritic cells, mast cells, neutrophils, basophils, eosinophils, or any combinations thereof. For example, the immune effector cells can comprise T lymphocytes, preferably cytotoxic T lymphocytes (CTLs). 
     T helper cells (T H  cells) assist other white blood cells in immunologic processes, including maturation of B cells into plasma cells and memory B cells, and activation of cytotoxic T cells and macrophages. These cells are also known as CD4+ T cells because they express the CD4 glycoprotein on their surface. Helper T cells become activated when they are presented with peptide antigens by MHC class II molecules, which are expressed on the surface of antigen-presenting cells (APCs). Once activated, they divide rapidly and secrete small proteins called cytokines that regulate or assist in the active immune response. These cells can differentiate into one of several subtypes, including T H 1, T H 2, T H 3, T H 17, T H 9, or T FH , which secrete different cytokines to facilitate a different type of immune response. 
     Cytotoxic T cells (Tc cells, or CTLs) destroy virally infected cells and tumor cells, and are also implicated in transplant rejection. These cells are also known as CD8 +  T cells since they express the CD8 glycoprotein at their surface. These cells recognize their targets by binding to antigen associated with MHC class I molecules, which are present on the surface of all nucleated cells. Through IL-10, adenosine and other molecules secreted by regulatory T cells, the CD8 +  cells can be inactivated to an anergic state, which prevents autoimmune diseases. 
     Memory T cells are a subset of antigen-specific T cells that persist long-term after an infection has resolved. They quickly expand to large numbers of effector T cells upon re-exposure to their cognate antigen, thus providing the immune system with “memory” against past infections. Memory cells may be either CD4 +  or CD8 + . Memory T cells typically express the cell surface protein CD45RO. 
     Regulatory T cells (T reg  cells), formerly known as suppressor T cells, are crucial for the maintenance of immunological tolerance. Their major role is to shut down T cell-mediated immunity toward the end of an immune reaction and to suppress auto-reactive T cells that escaped the process of negative selection in the thymus. Two major classes of CD4 +  T reg  cells have been described—naturally occurring T reg  cells and adaptive T reg  cells. 
     Natural killer T (NKT) cells (not to be confused with natural killer (NK) cells) bridge the adaptive immune system with the innate immune system. Unlike conventional T cells that recognize peptide antigens presented by major histocompatibility complex (MHC) molecules, NKT cells recognize glycolipid antigen presented by a molecule called CD1d. 
     In some embodiments, the T cells comprise a mixture of CD4 +  cells. In other embodiments, the T cells are enriched for one or more subsets based on cell surface expression. For example, in some cases, the T comprise are cytotoxic CD8 +  T lymphocytes. 
     Natural-killer (NK) cells are CD56 + CD3 −  large granular lymphocytes that can kill virally infected and transformed cells, and constitute a critical cellular subset of the innate immune system (Godfrey J, et al. Leuk Lymphoma 2012 53:1666-1676). Unlike cytotoxic CD8 +  T lymphocytes, NK cells launch cytotoxicity against tumor cells without the requirement for prior sensitization, and can eradicate MHC-I-negative cells (Narni-Mancinelli E, et al. Int Immunol 2011 23:427-431). NK cells are safer effector cells, as they may avoid the potentially lethal complications of cytokine storms (Morgan R A, et al. Mol Ther 2010 18:843-851), tumor lysis syndrome (Porter D L, et al. N Engl J Med 2011 365:725-733), and on-target, off-tumor effects. 
     CD3 Multispecific Antigen-Binding Molecules 
     In certain embodiments, the methods and compositions provided herein relate to CD3 antigen-binding molecules (i.e., antigen binding molecules that comprise at least one antigen binding domain that binds to CD3). In certain embodiments, the CD3 multispecific antigen-binding molecules provided herein further comprise an antigen binding domain that binds to a cancer antigen (i.e., an antigen expressed on a cancer cell). In certain embodiments, the CD3 multispecific antigen-binding molecules provided herein further comprise an antigen binding domain that binds to a costimulatory receptor (e.g., CD28). 
     As used herein, the expression “multispecific antigen-binding molecule” refers to a protein, polypeptide or molecular complex comprising at least a first antigen-binding domain and a second antigen-binding domain. In some embodiments, each antigen-binding domain within the multispecific antigen-binding molecule may comprises at least one CDR that alone, or in combination with one or more additional CDRs and/or FRs, specifically binds to a particular antigen. In the context of the present invention, the first antigen-binding domain specifically binds a first antigen (e.g., CD3), and the second antigen-binding domain specifically binds a second, distinct antigen (e.g., a tumor antigen). 
     In some embodiments, the CD3 multispecific antigen-binding molecule is an CD3 multispecific antibody. The CD3 multispecific antibodies of provided herein may be, for example, bi-specific, or tri-specific. Multispecific antibodies may be specific for different epitopes of one target polypeptide or may contain antigen-binding domains specific for more than one target polypeptide. See, e.g., Tutt et al., 1991, J. Immunol. 147:60-69; Kufer et al., 2004, Trends Biotechnol. 22:238-244. The CD3 bispecific antibodies provided herein can be linked to or co-expressed with another functional molecule, e.g., another peptide or protein. For example, an antibody or fragment thereof can be functionally linked (e.g., by chemical coupling, genetic fusion, noncovalent association or otherwise) to one or more other molecular entities, such as another antibody or antibody fragment to produce a bi-specific or a multispecific antibody with a second or additional binding specificity. 
     The term “CD3,” as used herein, refers to an antigen which is expressed on T cells as part of the multimolecular T cell receptor (TCR) and which consists of a homodimer or heterodimer formed from the association of two of four receptor chains: CD3-epsilon, CD3-delta, CD3-zeta, and CD3-gamma. Human CD3-epsilon comprises the amino acid sequence as set forth in SEQ ID NO:116 of U.S. Patent Application Publication No. US 2020/0024356A1 (SEQ ID NO: 1133), the content of which is incorporated by reference herein in its entirety; human CD3-delta comprises the amino acid sequence as set forth in SEQ ID NO:117 of U.S. Patent Application Publication No. US 2020/0024356A1 (SEQ ID NO: 1134), the content of which is incorporated by reference herein in its entirety; human CD3-zeta comprises the amino acid sequence as set forth in SEQ ID NO: 118 of U.S. Patent Application Publication No. US 2020/0024356A1 (SEQ ID NO: 1135), the content of which is incorporated by reference herein in its entirety; and CD3-gamma comprises the amino acid sequence as set forth in SEQ ID NO 119 of U.S. Patent Application Publication No. US 2020/0024356A1 (SEQ ID NO: 1136), the content of which is incorporated by reference herein in its entirety. All references to proteins, polypeptides and protein fragments herein are intended to refer to the human version of the respective protein, polypeptide or protein fragment unless explicitly specified as being from a non-human species. Thus, the expression “CD3” means human CD3 unless specified as being from a non-human species, e.g., “mouse CD3,” “monkey CD3,” etc. 
     As used herein, “an antibody that binds CD3” or an “anti-CD3 antibody” includes antibodies and antigen-binding fragments thereof that specifically recognize a single CD3 subunit (e.g., epsilon, delta, gamma or zeta), as well as antibodies and antigen-binding fragments thereof that specifically recognize a dimeric complex of two CD3 subunits (e.g., gamma/epsilon, delta/epsilon, and zeta/zeta CD3 dimers). The antibodies and antigen-binding fragments of the present invention may bind soluble CD3 and/or cell surface expressed CD3. Soluble CD3 includes natural CD3 proteins as well as recombinant CD3 protein variants such as, e.g., monomeric and dimeric CD3 constructs, that lack a transmembrane domain or are otherwise unassociated with a cell membrane. 
     As used herein, the expression “cell surface-expressed CD3” means one or more CD3 protein(s) that is/are expressed on the surface of a cell in vitro or in vivo, such that at least a portion of a CD3 protein is exposed to the extracellular side of the cell membrane and is accessible to an antigen-binding portion of an antibody. Cell surface-expressed CD3 includes CD3 proteins contained within the context of a functional T cell receptor in the membrane of a cell. Cell surface-expressed CD3 includes CD3 protein expressed as part of a homodimer or heterodimer on the surface of a cell (e.g., gamma/epsilon, delta/epsilon, and zeta/zeta CD3 dimers). Cell surface-expressed CD3 also includes a CD3 chain (e.g., CD3-epsilon, CD3-delta or CD3-gamma) that is expressed by itself, without other CD3 chain types, on the surface of a cell. A cell surface-expressed CD3 can comprise or consist of a CD3 protein expressed on the surface of a cell which normally expresses CD3 protein. Alternatively, cell surface-expressed CD3 can comprise or consist of CD3 protein expressed on the surface of a cell that normally does not express human CD3 on its surface but has been artificially engineered to express CD3 on its surface. 
     In some embodiments, the present invention includes bispecific antibodies wherein one arm of an immunoglobulin binds CD3, and the other arm of the immunoglobulin is specific for a cancer antigen (also referred to herein as a tumor antigen, or “TAA”). In some embodiments, the present invention includes trispecific antibodies wherein a first arm of an immunoglobulin binds CD3, a second arm of the immunoglobulin is specific for a tumor antigen, and a third arm of the immunoglobulin binds an additional T cell antigen (e.g., CD28) or an additional tumor antigen. 
     In some embodiments, the CD3-binding arm may comprise any of the HCVR/LCVR or CDR amino acid sequences as disclosed in WO 2014/047231 or WO 2017/053856. In certain embodiments, the CD3-binding arm binds to human CD3 and induces human T cell activation. In certain embodiments, the CD3-binding arm binds weakly to human CD3 and induces human T cell activation. In other embodiments, the CD3-binding arm binds weakly to human CD3 and induces tumor-associated antigen-expressing cell killing in the context of a bispecific or multispecific antibody. In other embodiments, the CD3-binding arm binds or associated weakly with human and cynomolgus (monkey) CD3, yet the binding interaction is not detectable by in vitro assays known in the art. 
     In certain embodiments, the multispecific antibodies or antigen-binding fragments for use in the present invention comprise an antigen-binding arm that binds to CD28, ICOS, HVEM, CD27, 4-1BB, OX40, DR3, GITR, CD30, SLAM, CD2, 2B4, CD226, TIM1, or TIM2 to induce T cell activation. 
     In certain embodiments, the CD3 multispecific antigen-binding molecule comprises an antigen-binding domain specific for a cancer antigen. In certain embodiments, the cancer antigen is selected from AIM-2, ALDH1A1, alpha-actinin-4, alpha-fetoprotein (“AFP”), ARTC1, B-RAF, BAGE-1, BCLX (L), BCMA, BCR-ABL fusion protein b3a2, beta-catenin, BING-4, CA-125, CALCA, carcinoembryonic antigen (“CEA”), CASP-5, CASP-8, CD20, CD274, CD45, Cdc27, CDK12, CDK4, CDKN2A, CEA, CLPP, COA-1, CPSF, CSNK1A1, CTAG1, CTAG2, cyclin D1, Cyclin-A1, dek-can fusion protein, DKK1, EFTUD2, Elongation factor 2, ENAH (hMena), Ep-CAM, EpCAM, EphA3, epithelial tumor antigen (“ETA”), ETV6-AML1 fusion protein, EZH2, FGF5, FLT3-ITD, FN1, G250/MN/CAIX, GAGE-1,2,8, GAGE-3,4,5,6,7, GAS7, glypican-3, GnTV, gp100/Pme117, GPNMB, HAUS3, Hepsin, HER-2/neu, HERV-K-MEL, HLA-A11, HLA-A2, HLA-DOB, hsp70-2, IDOL IGF2B3, IL13Ralpha2, Intestinal carboxyl esterase, K-ras, Kallikrein 4, KIF20A, KK-LC-1, KKLC1, KM-HN-1, KMHN1 also known as CCDC110, LAGE-1, LDLR-fucosyltransferaseAS fusion protein, Lengsin, M-CSF, MAGE-A1, MAGE-A10, MAGE-A12, MAGE-A2, MAGE-A3, MAGE-A4, MAGE-A6, MAGE-A9, MAGE-C1, MAGE-C2, malic enzyme, mammaglobin-A, MART2, MATN, MC1R, MCSP, mdm-2, ME1, Melan-A/MART-1, Meloe, Midkine, MMP-2, MMP-7, MUC1, MUC5AC, MUC16, mucin, MUM-1, MUM-2, MUM-3, Myosin, Myosin class I, N-raw, NA88-A, neo-PAP, NFYC, NY-BR-1, NY-ESO-1/LAGE-2, OA1, OGT, OS-9, P polypeptide, p53, PAP, PAX5, PBF, pml-RARalpha fusion protein, polymorphic epithelial mucin (“PEM”), PPP1R3B, PRAME, PRDX5, PSA, PSMA, PTPRK, RAB38/NY-MEL-1, RAGE-1, RBAF600, RGS5, RhoC, RNF43, RU2AS, SAGE, secernin 1, SIRT2, SNRPD1, SOX10, Sp17, SPA17, SSX-2, SSX-4, STEAP1, STEAP2, survivin, SYT-SSX1 or -SSX2 fusion protein, TAG-1, TAG-2, Telomerase, TGF-betaRII, TPBG, TRAG-3, Triosephosphate isomerase, TRP-1/gp75, TRP-2, TRP2-INT2, tyrosinase, tyrosinase (“TYR”), VEGF, WT1 and XAGE-1b/GAGED2a. 
     In some embodiments, the cancer antigen is include ADAM 17, BCMA, CA-IX, CD19, CD20, CD22, CD30, CD33, CD38, CD52, CD56, CD70, CD74, CD79b, CD123, CD138, CDH3, CEA, EphA2, EpCAM, ERBB2, ENPP3, EGFR, EGFR-vIII, FLT3, FOLR1, GD-2, glypican-3, gpA33, GPNMB, GPRC5D, HER2, HER3, LMP1, LMP2A, MUC16, Mesothelin, PSMA, PSCA, RON, ROR1, ROR2, STEAP1, STEAP2, SSTR2, SSTR5, 5T4, and Trop-2. In some embodiments, the tumore antigen may be CD19, CD123, STEAP2, CD20, SSTR2, CD38, STEAP1, 5T4, ENPP3, PSMA, MUC16, GPRC5D, or BCMA. 
     In some embodiments, the tumore antigen may be CD19, CD123, STEAP2, CD20, SSTR2, CD38, STEAP1, 5T4, ENPP3, PSMA, MUC16, GPRC5D, or BCMA. 
     In some embodiments, the cancer antigen is CD20, MUC16, BCMA, PSMA, or STEAP2. 
     CD20 is a non-glycosylated phosphoprotein expressed on the cell membranes of mature B cells. CD20 is considered a B cell tumor-associated antigen because it is expressed by more than 95% of B-cell non-Hodgkin lymphomas (NHLs) and other B-cell malignancies, but it is absent on precursor B-cells, dendritic cells and plasma cells. The human CD20 protein has the amino acid sequence shown in SEQ ID NO: 5 of U.S. Patent Application Publication No. US 2020/0129617 (SEQ ID NO: 1137), the content of which is incorporated by reference herein in its entirety. 
     MUC16 refers to mucin 16. MUC16 is a single transmembrane domain highly glycosylated integral membrane glycoprotein that is highly expressed in ovarian cancer. The amino acid sequence of human MUC16 is set forth in SEQ ID NO:1899 of U.S. Patent Application Publication No. US 2018/0118848A1 (SEQ ID NO: 1138), the content of which is incorporated by reference herein in its entirety. 
     BCMA refers to B-cell maturation antigen. BCMA (also known as TNFRSF17 and CD269) is a cell surface protein expressed on malignant plasma cells, and plays a central role in regulating B cell maturation and differentiation into immunoglobulin-producing plasma cells. The amino acid sequence of human BCMA is shown in SEQ ID NO: 115 of U.S. Patent Application Publication No. US 2020/0024356 (SEQ ID NO: 1139), the content of which is incorporated by reference herein in its entirety. It can also be found in GenBank accession number NP_001183.2. 
     PSMA refers to prostate-specific membrane antigen, also known as folate hydrolase 1 (FOLH1). PSMA is an integral, non-shed membrane glycoprotein that is highly expressed in prostate epithelial cells and is a cell-surface marker for prostate cancer. The amino acid sequence of human PSMA is set forth in SEQ ID NO: 7 of U.S. Patent Application Publication No. US 2020/0129617 (SEQ ID NO: 1140), the content of which is incorporated by reference herein in its entirety. 
     STEAP2 refers to six-transmembrane epithelial antigen of prostate 2. STEAP2 is an integral, six-transmembrane-spanning protein that is highly expressed in prostate epithelial cells and is a cell-surface marker for prostate cancer. STEAP2 is a 490-amino acid protein encoded by STEAP2 gene located at the chromosomal region 7q21 in humans. The amino acid sequence of human STEAP2 is set forth in SEQ ID NO: 9 of U.S. Patent Application Publication No. US 2020/0129617 (SEQ ID NO: 1141), the content of which is incorporated by reference herein in its entirety. 
     In some embodiments, the CD3 multispecific antibody may be a bispecific CD3×CD19 antibody, a bispecific CD3×GPRC5D antibody, a bispecific CD3×CD123 antibody, a bispecific CD3×STEAP2 antibody, a bispecific CD3×CD20 antibody, a bispecific CD3×SSTR 2 antibody, a bispecific CD3×CD38 antibody, a bispecific CD3×STEAP1 antibody, a bispecific CD3×5T4 antibody, a bispecific CD3×ENPP3 antibody, a bispecific CD3×MUC16 antibody, a bispecific CD3×BCMA antibody, a bispecific CD3×PSMA antibody, or a trispecific CD3×CD28×CD38 antibody. 
     In some embodiments, the present invention includes antibodies having the HCVR, LCVR and/or CDR amino acid sequences of the antibodies set forth herein, the anti-CD3 antibodies disclosed in WO 2014/047231 or WO 2017/053856, the bispecific anti-CD20×anti-CD3 antibodies disclosed in WO 2014/047231, the bispecific anti-PSMA×anti-CD3 antibodies disclosed in WO 2017/023761, the bispecific anti-MUC16×anti-CD3 antibodies disclosed in WO 2018/067331, the bispecific anti-STEAP2×anti-CD3 antibodies disclosed in WO 2018/058001, or the bispecific anti-BCMA×anti-CD3 antibodies disclosed in WO 2020/018820, each of which is incorporated herein by reference. 
     In certain embodiments, the mulitispecific antigen-binding molecule is a mulitispecific antibody or antigen-binding fragment thereof. Each antigen-binding domain of a mulitispecific antibody comprises a heavy chain variable domain (HCVR) and a light chain variable domain (LCVR). In the context of a bispecific antigen-binding molecule comprising a first and a second antigen-binding domain (e.g., a bispecific antibody), the CDRs of the first antigen-binding domain may be designated with the prefix “A1” and the CDRs of the second antigen-binding domain may be designated with the prefix “A2”. Thus, the CDRs of the first antigen-binding domain may be referred to herein as A1-HCDR1, A1-HCDR2, and A1-HCDR3; and the CDRs of the second antigen-binding domain may be referred to herein as A2-HCDR1, A2-HCDR2, and A2-HCDR3. In the context of a trispecific antigen-binding molecule comprising a first, a second, and a third antigen-binding domain (e.g., a trispecific antibody), the CDRs of the first antigen-binding domain may be designated with the prefix “A1”, the CDRs of the second antigen-binding domain may be designated with the prefix “A2”, and the CDRs of the third antigen-binding domain may be designated with the prefix “A3”. Thus, the CDRs of the first antigen-binding domain may be referred to herein as A1-HCDR1, A1-HCDR2, and A1-HCDR3; the CDRs of the second antigen-binding domain may be referred to herein as A2-HCDR1, A2-HCDR2, and A2-HCDR3; and the CDRs of the third antigen-binding domain may be referred to herein as A3-HCDR1, A3-HCDR2, and A3-HCDR3. 
     The bispecific antigen-binding molecules discussed above or herein may be bispecific antibodies. In some cases, the bispecific antibody comprises a human IgG heavy chain constant region. In some cases, the human IgG heavy chain constant region is isotype IgG1. In some cases, the human IgG heavy chain constant region is isotype IgG4. In various embodiments, the bispecific antibody comprises a chimeric hinge that reduces Fcγ receptor binding relative to a wild-type hinge of the same isotype. 
     The first antigen-binding domain and the second antigen-binding domain may be directly or indirectly connected to one another to form a bispecific antigen-binding molecule of the present invention. Alternatively, the first antigen-binding domain and the second antigen-binding domain may each be connected to a separate multimerizing domain. The association of one multimerizing domain with another multimerizing domain facilitates the association between the two antigen-binding domains, thereby forming a bispecific antigen-binding molecule. As used herein, a “multimerizing domain” is any macromolecule, protein, polypeptide, peptide, or amino acid that has the ability to associate with a second multimerizing domain of the same or similar structure or constitution. For example, a multimerizing domain may be a polypeptide comprising an immunoglobulin C H 3 domain. A non-limiting example of a multimerizing component is an Fc portion of an immunoglobulin (comprising a C H 2-C H 3 domain), e.g., an Fc domain of an IgG selected from the isotypes IgG1, IgG2, IgG3, and IgG4, as well as any allotype within each isotype group. 
     Bispecific antigen-binding molecules of the present invention will typically comprise two multimerizing domains, e.g., two Fc domains that are each individually part of a separate antibody heavy chain. The first and second multimerizing domains may be of the same IgG isotype such as, e.g., IgG1/IgG1, IgG2/IgG2, IgG4/IgG4. Alternatively, the first and second multimerizing domains may be of different IgG isotypes such as, e.g., IgG 1/IgG2, IgG1/IgG4, IgG2/IgG4, etc. 
     In certain embodiments, the multimerizing domain is an Fc fragment or an amino acid sequence of from 1 to about 200 amino acids in length containing at least one cysteine residue. In other embodiments, the multimerizing domain is a cysteine residue, or a short cysteine-containing peptide. Other multimerizing domains include peptides or polypeptides comprising or consisting of a leucine zipper, a helix-loop motif, or a coiled-coil motif. 
     Any bispecific antibody format or technology may be used to make the bispecific antigen-binding molecules of the present invention. For example, an antibody or fragment thereof having a first antigen binding specificity can be functionally linked (e.g., by chemical coupling, genetic fusion, noncovalent association or otherwise) to one or more other molecular entities, such as another antibody or antibody fragment having a second antigen-binding specificity to produce a bispecific antigen-binding molecule. Specific exemplary bispecific formats that can be used in the context of the present invention include, without limitation, e.g., scFv-based or diabody bispecific formats, IgG-scFv fusions, dual variable domain (DVD)-Ig, Quadroma, knobs-into-holes, common light chain (e.g., common light chain with knobs-into-holes, etc.), CrossMab, CrossFab, (SEED)body, leucine zipper, Duobody, IgG1/IgG2, dual acting Fab (DAF)-IgG, and Mab 2  bispecific formats (see, e.g., Klein et al. 2012, mAbs 4:6, 1-11, and references cited therein, for a review of the foregoing formats). 
     In the context of bispecific antigen-binding molecules provided herein, the multimerizing domains, e.g., Fc domains, may comprise one or more amino acid changes (e.g., insertions, deletions or substitutions) as compared to the wild-type, naturally occurring version of the Fc domain. For example, the invention includes bispecific antigen-binding molecules comprising one or more modifications in the Fc domain that results in a modified Fc domain having a modified binding interaction (e.g., enhanced or diminished) between Fc and FcRn. In one embodiment, the bispecific antigen-binding molecule comprises a modification in a C H 2 or a C H 3 region, wherein the modification increases the affinity of the Fc domain to FcRn in an acidic environment (e.g., in an endosome where pH ranges from about 5.5 to about 6.0). Non-limiting examples of such Fc modifications include, e.g., a modification at position 250 (e.g., E or Q); 250 and 428 (e.g., L or F); 252 (e.g., L/Y/F/W or T), 254 (e.g., S or T), and 256 (e.g., S/R/Q/E/D or T); or a modification at position 428 and/or 433 (e.g., L/R/S/P/Q or K) and/or 434 (e.g., H/F or Y); or a modification at position 250 and/or 428; or a modification at position 307 or 308 (e.g., 308F, V308F), and 434. In one embodiment, the modification comprises a 428L (e.g., M428L) and 434S (e.g., N434S) modification; a 428L, 259I (e.g., V259I), and 308F (e.g., V308F) modification; a 433K (e.g., H433K) and a 434 (e.g., 434Y) modification; a 252, 254, and 256 (e.g., 252Y, 254T, and 256E) modification; a 250Q and 428L modification (e.g., T250Q and M428L); and a 307 and/or 308 modification (e.g., 308F or 308P). 
     Tin certain embodiments, provided herein are bispecific antigen-binding molecules comprising a first C H 3 domain and a second Ig C H 3 domain, wherein the first and second Ig C H 3 domains differ from one another by at least one amino acid, and wherein at least one amino acid difference reduces binding of the bispecific antibody to Protein A as compared to a bi-specific antibody lacking the amino acid difference. In one embodiment, the first Ig C H 3 domain binds Protein A and the second Ig C H 3 domain contains a mutation that reduces or abolishes Protein A binding such as an H95R modification (by IMGT exon numbering; H435R by EU numbering). The second C H 3 may further comprise a Y96F modification (by IMGT; Y436F by EU). See, for example, U.S. Pat. No. 8,586,713. Further modifications that may be found within the second C H 3 include: D16E, L18M, N44S, K52N, V57M, and V82I (by IMGT; D356E, L358M, N384S, K392N, V397M, and V422I by EU) in the case of IgG1 antibodies; N44S, K52N, and V82I (IMGT; N384S, K392N, and V422I by EU) in the case of IgG2 antibodies; and Q15R, N44S, K52N, V57M, R69K, E79Q, and V82I (by IMGT; Q355R, N384S, K392N, V397M, R409K, E419Q, and V422I by EU) in the case of IgG4 antibodies. 
     In certain embodiments, the Fc domain may be chimeric, combining Fc sequences derived from more than one immunoglobulin isotype. For example, a chimeric Fc domain can comprise part or all of a C H 2 sequence derived from a human IgG1, human IgG2 or human IgG4 C H 2 region, and part or all of a C H 3 sequence derived from a human IgG1, human IgG2 or human IgG4. A chimeric Fc domain can also contain a chimeric hinge region. For example, a chimeric hinge may comprise an “upper hinge” sequence, derived from a human IgG1, a human IgG2 or a human IgG4 hinge region, combined with a “lower hinge” sequence, derived from a human IgG1, a human IgG2 or a human IgG4 hinge region. A particular example of a chimeric Fc domain that can be included in any of the antigen-binding molecules set forth herein comprises, from N- to C-terminus: [IgG4 C H 1]-[IgG4 upper hinge]-[IgG2 lower hinge]-[IgG4 CH2]-[IgG4 CH3]. Another example of a chimeric Fc domain that can be included in any of the antigen-binding molecules set forth herein comprises, from N- to C-terminus: [IgG1 C H 1]-[IgG1 upper hinge]-[IgG2 lower hinge]-[IgG4 CH2]-[IgG1 CH3]. These and other examples of chimeric Fc domains that can be included in any of the antigen-binding molecules of the present invention are described in US Publication 2014/0243504, published Aug. 28, 2014, which is herein incorporated in its entirety. Chimeric Fc domains having these general structural arrangements, and variants thereof, can have altered Fc receptor binding, which in turn affects Fc effector function. 
     The CD3 multispecific (e.g., bispecific or trispecific) antibodies disclosed herein may comprise one or more amino acid substitutions, insertions and/or deletions in the framework and/or CDR regions of the heavy and light chain variable domains as compared to the corresponding germline sequences from which the antibodies were derived. Such mutations can be readily ascertained by comparing the amino acid sequences disclosed herein to germline sequences available from, for example, public antibody sequence databases. The present invention includes antibodies, and antigen-binding fragments thereof, which are derived from any of the amino acid sequences disclosed herein, wherein one or more amino acids within one or more framework and/or CDR regions are mutated to the corresponding residue(s) of the germline sequence from which the antibody was derived, or to the corresponding residue(s) of another human germline sequence, or to a conservative amino acid substitution of the corresponding germline residue(s) (such sequence changes are referred to herein collectively as “germline mutations”). A person of ordinary skill in the art, starting with the heavy and light chain variable region sequences disclosed herein, can easily produce numerous antibodies and antigen-binding fragments which comprise one or more individual germline mutations or combinations thereof. In certain embodiments, all of the framework and/or CDR residues within the V H  and/or V L  domains are mutated back to the residues found in the original germline sequence from which the antibody was derived. In other embodiments, only certain residues are mutated back to the original germline sequence, e.g., only the mutated residues found within the first 8 amino acids of FR1 or within the last 8 amino acids of FR4, or only the mutated residues found within CDR1, CDR2 or CDR3. In other embodiments, one or more of the framework and/or CDR residue(s) are mutated to the corresponding residue(s) of a different germline sequence (i.e., a germline sequence that is different from the germline sequence from which the antibody was originally derived). Furthermore, the antibodies of the present invention may contain any combination of two or more germline mutations within the framework and/or CDR regions, e.g., wherein certain individual residues are mutated to the corresponding residue of a particular germline sequence while certain other residues that differ from the original germline sequence are maintained or are mutated to the corresponding residue of a different germline sequence. Once obtained, antibodies and antigen-binding fragments that contain one or more germline mutations can be easily tested for one or more desired property such as, improved binding specificity, increased binding (e.g., as measured by cell binding titration or FACS binding) or binding affinity (e.g., K D ), improved or enhanced antagonistic or agonistic biological properties (as the case may be), reduced immunogenicity, etc. Antibodies and antigen-binding fragments obtained in this general manner are encompassed within the present invention. 
     Provided herein are also CD3 multispecific (e.g., bispecific or trispecific) antibodies comprising variants of any of the HCVR, LCVR, and/or CDR amino acid sequences disclosed herein having one or more conservative substitutions. For example, the present invention includes anti-CD40 antagonist antibodies or CD3 multispecific (e.g., bispecific or trispecific) antibodies having HCVR, LCVR, and/or CDR amino acid sequences with, e.g., 10 or fewer, 8 or fewer, 6 or fewer, 4 or fewer, etc. conservative amino acid substitutions relative to any of the HCVR, LCVR, and/or CDR amino acid sequences disclosed herein. 
     Exemplary CD3×MUC16 Antibodies 
     In some embodiments, the methods and compositions provided herein include bispecific antibodies wherein one arm of an immunoglobulin binds human CD3, and the other arm of the immunoglobulin is specific for human MUC16. The term “MUC16,” as used herein, refers to the human MUC16 protein unless specified as being from a non-human species (e.g., “mouse MUC16,” “monkey MUC16,” etc.). The human MUC16 protein has the amino acid sequence shown in SEQ ID NO: 1899 of U.S. Patent Application Publication No. US 2018/0118848A1 (SEQ ID NO: 1138), the content of which is incorporated by reference herein in its entirety. Such molecules may be referred to herein as, e.g., “anti-CD3/anti-MUC16,” or “anti-CD3×MUC16” or “CD3×MUC16” bispecific molecules, or other similar terminology (e.g., anti-MUC16/anti-CD3). Such bispecific antigen-binding molecules are constructed with a first antigen-binding arm that binds MUC16 and a second antigen-binding arm that binds CD3. The MUC16-binding arm can comprise any of the HCVR/LCVR or CDR amino acid sequences as set forth in Table 1 herein. The CD3-binding arm can comprise any of the HCVR/LCVR or CDR amino acid sequences as set forth in Tables 2-6 herein. Sequences in Tables 1-6 were disclosed in U.S. Patent Application Publication No. US 2018/0118848A1, the the content of which is incorporated by reference herein in its entirety. 
     Table 1 sets forth the amino acid sequence identifiers of the heavy and light chain variable regions and CDRs of selected anti-MUC16 antibodies of the invention. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Amino Acid Sequence Identifiers 
               
            
           
           
               
               
            
               
                 Antibody 
                 SEQ ID NOs: 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Designation 
                 HCVR 
                 HCDR1 
                 HCDR2 
                 HCDR3 
                 LCVR 
                 LCDR1 
                 LCDR2 
                 LCDR3 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 H1H8755P 
                 1 
                 30 
                 59 
                 88 
                 117 
                 146 
                 175 
                 204 
               
               
                 H1H8767P 
                 2 
                 31 
                 60 
                 89 
                 118 
                 147 
                 176 
                 205 
               
               
                 H1H8770P 
                 3 
                 32 
                 61 
                 90 
                 119 
                 148 
                 177 
                 206 
               
               
                 H1H8783P 
                 4 
                 33 
                 62 
                 91 
                 120 
                 149 
                 178 
                 207 
               
               
                 H1H8790P 
                 5 
                 34 
                 63 
                 92 
                 121 
                 150 
                 179 
                 208 
               
               
                 H1H8794P 
                 6 
                 35 
                 64 
                 93 
                 122 
                 151 
                 180 
                 209 
               
               
                 H1H8794P2 
                 7 
                 36 
                 65 
                 94 
                 123 
                 152 
                 181 
                 210 
               
               
                 H1H8799P 
                 8 
                 37 
                 66 
                 95 
                 124 
                 153 
                 182 
                 211 
               
               
                 H1H8799P2 
                 9 
                 38 
                 67 
                 96 
                 125 
                 154 
                 183 
                 212 
               
               
                 H1H8804P 
                 10 
                 39 
                 68 
                 97 
                 126 
                 155 
                 184 
                 213 
               
               
                 H1H8808P 
                 11 
                 40 
                 69 
                 98 
                 127 
                 156 
                 185 
                 214 
               
               
                 H1H8810P 
                 12 
                 41 
                 70 
                 99 
                 128 
                 157 
                 186 
                 215 
               
               
                 H1H8813P 
                 13 
                 42 
                 71 
                 100 
                 129 
                 158 
                 187 
                 216 
               
               
                 H1M7129N 
                 14 
                 43 
                 72 
                 101 
                 130 
                 159 
                 188 
                 217 
               
               
                 H1M7137N 
                 15 
                 44 
                 73 
                 102 
                 131 
                 160 
                 189 
                 218 
               
               
                 H1M9519N 
                 16 
                 45 
                 74 
                 103 
                 132 
                 161 
                 190 
                 219 
               
               
                 H1M9521N 
                 17 
                 46 
                 75 
                 104 
                 133 
                 162 
                 191 
                 220 
               
               
                 H1M9528N 
                 18 
                 47 
                 76 
                 105 
                 134 
                 163 
                 192 
                 221 
               
               
                 H2M7128N 
                 19 
                 48 
                 77 
                 106 
                 135 
                 164 
                 193 
                 222 
               
               
                 H1M7130N 
                 20 
                 49 
                 78 
                 107 
                 136 
                 165 
                 194 
                 223 
               
               
                 H2M7131N 
                 21 
                 50 
                 79 
                 108 
                 137 
                 166 
                 195 
                 224 
               
               
                 H2M7133N 
                 22 
                 51 
                 80 
                 109 
                 138 
                 167 
                 196 
                 225 
               
               
                 H2M7134N 
                 23 
                 52 
                 81 
                 110 
                 139 
                 168 
                 197 
                 226 
               
               
                 H2M7135N 
                 24 
                 53 
                 82 
                 111 
                 140 
                 169 
                 198 
                 227 
               
               
                 H2M7138N 
                 25 
                 54 
                 83 
                 112 
                 141 
                 170 
                 199 
                 228 
               
               
                 H2M9538N 
                 26 
                 55 
                 84 
                 113 
                 142 
                 171 
                 200 
                 229 
               
               
                 H3M9524N 
                 27 
                 56 
                 85 
                 114 
                 143 
                 172 
                 201 
                 230 
               
               
                 H3M9525N 
                 28 
                 57 
                 86 
                 115 
                 144 
                 173 
                 202 
                 231 
               
               
                 H3M9529N 
                 29 
                 58 
                 87 
                 116 
                 145 
                 174 
                 203 
                 232 
               
               
                   
               
            
           
         
       
     
     Table 2 sets forth the amino acid sequence identifiers of the heavy and light chain variable regions and CDRs of selected anti-CD3 antibodies of the invention. Methods of making the anti-CD3 antibodies disclosed herein can also be found in US publication 2014/0088295. 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Amino Acid Sequence Identifiers 
               
            
           
           
               
               
            
               
                 Antibody 
                 SEQ ID NOs: 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Designation 
                 HCVR 
                 HCDR1 
                   
                 HCDR3 
                 LCVR 
                 LCDR11 
                 LCDR2 
                 LCDR3 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 H1H2712N 
                 233 
                 322 
                 411 
                 500 
                 589 
                 678 
                 767 
                 856 
               
               
                 H1M2692N 
                 234 
                 323 
                 412 
                 501 
                 590 
                 679 
                 768 
                 857 
               
               
                 H1M3542N 
                 235 
                 324 
                 413 
                 502 
                 591 
                 680 
                 769 
                 858 
               
               
                 H1M3544N 
                 236 
                 325 
                 414 
                 503 
                 592 
                 681 
                 770 
                 859 
               
               
                 H1M3549N 
                 237 
                 326 
                 415 
                 504 
                 593 
                 682 
                 771 
                 860 
               
               
                 H1M3613N 
                 238 
                 327 
                 416 
                 505 
                 594 
                 683 
                 772 
                 861 
               
               
                 H2M2689N 
                 239 
                 328 
                 417 
                 506 
                 595 
                 684 
                 773 
                 862 
               
               
                 H2M2690N 
                 240 
                 329 
                 418 
                 507 
                 596 
                 685 
                 774 
                 863 
               
               
                 H2M2691N 
                 241 
                 330 
                 419 
                 508 
                 597 
                 686 
                 775 
                 864 
               
               
                 H2M2704N 
                 242 
                 331 
                 420 
                 509 
                 598 
                 687 
                 776 
                 865 
               
               
                 H2M2705N 
                 243 
                 332 
                 421 
                 510 
                 599 
                 688 
                 777 
                 866 
               
               
                 H2M2706N 
                 244 
                 333 
                 422 
                 511 
                 600 
                 689 
                 778 
                 867 
               
               
                 H2M2707N 
                 245 
                 334 
                 423 
                 512 
                 601 
                 690 
                 779 
                 868 
               
               
                 H2M2708N 
                 246 
                 335 
                 424 
                 513 
                 602 
                 691 
                 780 
                 869 
               
               
                 H2M2709N 
                 247 
                 336 
                 425 
                 514 
                 603 
                 692 
                 781 
                 870 
               
               
                 H2M2710N 
                 248 
                 337 
                 426 
                 515 
                 604 
                 693 
                 782 
                 871 
               
               
                 H2M2711N 
                 249 
                 338 
                 427 
                 516 
                 605 
                 694 
                 783 
                 872 
               
               
                 H2M2774N 
                 250 
                 339 
                 428 
                 517 
                 606 
                 695 
                 784 
                 873 
               
               
                 H2M2775N 
                 251 
                 340 
                 429 
                 518 
                 607 
                 696 
                 785 
                 874 
               
               
                 H2M2776N 
                 252 
                 341 
                 430 
                 519 
                 608 
                 697 
                 786 
                 875 
               
               
                 H2M2777N 
                 253 
                 342 
                 431 
                 520 
                 609 
                 698 
                 787 
                 876 
               
               
                 H2M2778N 
                 254 
                 343 
                 432 
                 521 
                 610 
                 699 
                 788 
                 877 
               
               
                 H2M2779N 
                 255 
                 344 
                 433 
                 522 
                 611 
                 700 
                 789 
                 878 
               
               
                 H2M2789N 
                 256 
                 345 
                 434 
                 523 
                 612 
                 701 
                 790 
                 879 
               
               
                 H2M2862N 
                 257 
                 346 
                 435 
                 524 
                 613 
                 702 
                 791 
                 880 
               
               
                 H2M2885N 
                 258 
                 347 
                 436 
                 525 
                 614 
                 703 
                 792 
                 881 
               
               
                 H2M2886N 
                 259 
                 348 
                 437 
                 526 
                 615 
                 704 
                 793 
                 882 
               
               
                 H2M3540N 
                 260 
                 349 
                 438 
                 527 
                 616 
                 705 
                 794 
                 883 
               
               
                 H2M3541N 
                 261 
                 350 
                 439 
                 528 
                 617 
                 706 
                 795 
                 884 
               
               
                 H2M3543N 
                 262 
                 351 
                 440 
                 529 
                 618 
                 707 
                 796 
                 885 
               
               
                 H2M3547N 
                 263 
                 352 
                 441 
                 530 
                 619 
                 708 
                 797 
                 886 
               
               
                 H2M3548N 
                 264 
                 353 
                 442 
                 531 
                 620 
                 709 
                 798 
                 887 
               
               
                 H2M3563N 
                 265 
                 354 
                 443 
                 532 
                 621 
                 710 
                 799 
                 888 
               
               
                 H1H5751P 
                 266 
                 355 
                 444 
                 533 
                 622 
                 711 
                 800 
                 889 
               
               
                 H1H5752P 
                 267 
                 356 
                 445 
                 534 
                 623 
                 712 
                 801 
                 890 
               
               
                 H1H5753B 
                 268 
                 357 
                 446 
                 535 
                 624 
                 713 
                 802 
                 891 
               
               
                 H1H5754B 
                 269 
                 358 
                 447 
                 536 
                 625 
                 714 
                 803 
                 892 
               
               
                 H1H5755B 
                 270 
                 359 
                 448 
                 537 
                 626 
                 715 
                 804 
                 893 
               
               
                 H1H5756B 
                 271 
                 360 
                 449 
                 538 
                 627 
                 716 
                 805 
                 894 
               
               
                 H1H5757B 
                 272 
                 361 
                 450 
                 539 
                 628 
                 717 
                 806 
                 895 
               
               
                 H1H5758B 
                 273 
                 362 
                 451 
                 540 
                 629 
                 718 
                 807 
                 896 
               
               
                 H1H5761P 
                 274 
                 363 
                 452 
                 541 
                 630 
                 719 
                 808 
                 897 
               
               
                 H1H5763P 
                 275 
                 364 
                 453 
                 542 
                 631 
                 720 
                 809 
                 898 
               
               
                 H1H5764P 
                 276 
                 365 
                 454 
                 543 
                 632 
                 721 
                 810 
                 899 
               
               
                 H1H5769P 
                 277 
                 366 
                 455 
                 544 
                 633 
                 722 
                 811 
                 900 
               
               
                 H1H5771P 
                 278 
                 367 
                 456 
                 545 
                 634 
                 723 
                 812 
                 901 
               
               
                 H1H5772P 
                 279 
                 368 
                 457 
                 546 
                 635 
                 724 
                 813 
                 902 
               
               
                 H1H5777P 
                 280 
                 369 
                 458 
                 547 
                 636 
                 725 
                 814 
                 903 
               
               
                 H1H5778P 
                 281 
                 370 
                 459 
                 548 
                 637 
                 726 
                 815 
                 904 
               
               
                 H1H5780P 
                 282 
                 371 
                 460 
                 549 
                 638 
                 727 
                 816 
                 905 
               
               
                 H1H5781P 
                 283 
                 372 
                 461 
                 550 
                 639 
                 728 
                 817 
                 906 
               
               
                 H1H5782P 
                 284 
                 373 
                 462 
                 551 
                 640 
                 729 
                 818 
                 907 
               
               
                 H1H5785B 
                 285 
                 374 
                 463 
                 552 
                 641 
                 730 
                 819 
                 908 
               
               
                 H1H5786B 
                 286 
                 375 
                 464 
                 553 
                 642 
                 731 
                 820 
                 909 
               
               
                 H1H5788P 
                 287 
                 376 
                 465 
                 554 
                 643 
                 732 
                 821 
                 910 
               
               
                 H1H5790B 
                 288 
                 377 
                 466 
                 555 
                 644 
                 733 
                 822 
                 911 
               
               
                 H1H5791B 
                 289 
                 378 
                 467 
                 556 
                 645 
                 734 
                 823 
                 912 
               
               
                 H1H5792B 
                 290 
                 379 
                 468 
                 557 
                 646 
                 735 
                 824 
                 913 
               
               
                 H1H5793B 
                 291 
                 380 
                 469 
                 558 
                 647 
                 736 
                 825 
                 914 
               
               
                 H1H5795B 
                 292 
                 381 
                 470 
                 559 
                 648 
                 737 
                 826 
                 915 
               
               
                 H1H5796B 
                 293 
                 382 
                 471 
                 560 
                 649 
                 738 
                 827 
                 916 
               
               
                 H1H5797B 
                 294 
                 383 
                 472 
                 561 
                 650 
                 739 
                 828 
                 917 
               
               
                 H1H5798B 
                 295 
                 384 
                 473 
                 562 
                 651 
                 740 
                 829 
                 918 
               
               
                 H1H5799P 
                 296 
                 385 
                 474 
                 563 
                 652 
                 741 
                 830 
                 919 
               
               
                 H1H5801B 
                 297 
                 386 
                 475 
                 564 
                 653 
                 742 
                 831 
                 920 
               
               
                 H1H7194B 
                 298 
                 387 
                 476 
                 565 
                 654 
                 743 
                 832 
                 921 
               
               
                 H1H7195B 
                 299 
                 388 
                 477 
                 566 
                 655 
                 744 
                 833 
                 922 
               
               
                 H1H7196B 
                 300 
                 389 
                 478 
                 567 
                 656 
                 745 
                 834 
                 923 
               
               
                 H1H7198B 
                 301 
                 390 
                 479 
                 568 
                 657 
                 746 
                 835 
                 924 
               
               
                 H1H7203B 
                 302 
                 391 
                 480 
                 569 
                 658 
                 747 
                 836 
                 925 
               
               
                 H1H7204B 
                 303 
                 392 
                 481 
                 570 
                 659 
                 748 
                 837 
                 926 
               
               
                 H1H7208B 
                 304 
                 393 
                 482 
                 571 
                 660 
                 749 
                 838 
                 927 
               
               
                 H1H7211B 
                 305 
                 394 
                 483 
                 572 
                 661 
                 750 
                 839 
                 928 
               
               
                 H1H7221B 
                 306 
                 395 
                 484 
                 573 
                 662 
                 751 
                 840 
                 929 
               
               
                 H1H7223B 
                 307 
                 396 
                 485 
                 574 
                 663 
                 752 
                 841 
                 930 
               
               
                 H1H7226B 
                 308 
                 397 
                 486 
                 575 
                 664 
                 753 
                 842 
                 931 
               
               
                 H1H7232B 
                 309 
                 398 
                 487 
                 576 
                 665 
                 754 
                 843 
                 932 
               
               
                 H1H7233B 
                 310 
                 399 
                 488 
                 577 
                 666 
                 755 
                 844 
                 933 
               
               
                 H1H7241B 
                 311 
                 400 
                 489 
                 578 
                 667 
                 756 
                 845 
                 934 
               
               
                 H1H7242B 
                 312 
                 401 
                 490 
                 579 
                 668 
                 757 
                 846 
                 935 
               
               
                 H1H7250B 
                 313 
                 402 
                 491 
                 580 
                 669 
                 758 
                 847 
                 936 
               
               
                 H1H7251B 
                 314 
                 403 
                 492 
                 581 
                 670 
                 759 
                 848 
                 937 
               
               
                 H1H7254B 
                 315 
                 404 
                 493 
                 582 
                 671 
                 760 
                 849 
                 938 
               
               
                 H1H7258B 
                 316 
                 405 
                 494 
                 583 
                 672 
                 761 
                 850 
                 939 
               
               
                 H1H7269B 
                 317 
                 406 
                 495 
                 584 
                 673 
                 762 
                 851 
                 940 
               
               
                 H1H7279B 
                 318 
                 407 
                 496 
                 585 
                 674 
                 763 
                 852 
                 941 
               
               
                 H1xH7221G 
                 319 
                 408 
                 497 
                 586 
                 675 
                 764 
                 853 
                 942 
               
               
                 H1xH7221G3 
                 320 
                 409 
                 498 
                 587 
                 676 
                 765 
                 854 
                 943 
               
               
                 H1xH7221G5 
                 321 
                 410 
                 499 
                 588 
                 677 
                 766 
                 855 
                 944 
               
               
                   
               
            
           
         
       
     
     Tables 3 and 4 set out the amino acid sequence identifiers for heavy chain variable regions (Table 3) and light chain variable regions (Table 4), and their corresponding CDRs, of additional anti-CD3 HCVRs and LCVRs useful in anti-MUC16×anti-CD3 bispecific antibodies of the invention. 
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 (Heavy Chain Variable Region Amino Acid Sequences) 
               
            
           
           
               
               
               
            
               
                   
                   
                 SEQ ID NOs 
               
            
           
           
               
               
               
               
               
               
            
               
                   
                 Heavy Chain Identifier 
                 HCVR 
                 HCDR1 
                 HCDR2 
                 HCDR3 
               
               
                   
               
               
                   
                 CD3-VH-AA 
                 945 
                 951 
                 957 
                 963 
               
               
                   
                 CD3-VH-B 
                 946 
                 952 
                 958 
                 964 
               
               
                   
                 CD3-VH-C 
                 947 
                 953 
                 959 
                 965 
               
               
                   
                 CD3-VH-D 
                 948 
                 954 
                 960 
                 966 
               
               
                   
                 CD3-VH-E 
                 949 
                 955 
                 961 
                 967 
               
               
                   
                 CD3-VH-F #   
                 950 
                 956 
                 962 
                 968 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 4 
               
             
            
               
                   
               
               
                 (Light Chain Variable Region Amino Acid Sequences) 
               
            
           
           
               
               
               
            
               
                   
                   
                 SEQ ID NOs 
               
            
           
           
               
               
               
               
               
               
            
               
                   
                 Light Chain Identifier 
                 LCVR 
                 LCDR1 
                 LCDR2 
                 LCDR3 
               
               
                   
               
               
                   
                 CD3-VL-AA 
                 969 
                 975 
                 981 
                 987 
               
               
                   
                 CD3-VL-B 
                 970 
                 976 
                 982 
                 988 
               
               
                   
                 CD3-VL-C 
                 971 
                 977 
                 983 
                 989 
               
               
                   
                 CD3-VL-D 
                 972 
                 978 
                 984 
                 990 
               
               
                   
                 CD3-VL-E 
                 973 
                 979 
                 985 
                 991 
               
               
                   
                 CD3-VL-F #   
                 974 
                 980 
                 986 
                 992 
               
               
                   
               
            
           
         
       
     
     Table 5 sets forth the amino acid sequence identifiers of the heavy chain variable regions and CDRs of engineered anti-CD3 antibodies of the invention. The amino acid sequence identifiers of the light chain variable region and CDRs are also identified below in Table 6. 
     
       
         
           
               
             
               
                 TABLE 5 
               
             
            
               
                   
               
               
                 Heavy Chain Amino Acid Sequence Identifiers 
               
            
           
           
               
               
               
            
               
                   
                 Antibody 
                   
               
               
                   
                 CD3-VH 
                 SEQ ID NOs: 
               
            
           
           
               
               
               
               
               
               
            
               
                   
                 Designation 
                 HCVR 
                 CDR1 
                 CDR2 
                 CDR3 
               
               
                   
                   
               
               
                   
                 CD3-VH-G 
                  993 
                 1013 
                 1033 
                 1053 
               
               
                   
                 CD3-VH-G2 
                  994 
                 1014 
                 1034 
                 1054 
               
               
                   
                 CD3-VH-G3 
                  995 
                 1015 
                 1035 
                 1055 
               
               
                   
                 CD3-VH-G4 
                  996 
                 1016 
                 1036 
                 1056 
               
               
                   
                 CD3-VH-G5 
                  997 
                 1017 
                 1037 
                 1057 
               
               
                   
                 CD3-VH-G8 
                  998 
                 1018 
                 1038 
                 1058 
               
               
                   
                 CD3-VH-G9 
                  999 
                 1019 
                 1039 
                 1059 
               
               
                   
                 CD3-VH-G10 
                 1000 
                 1020 
                 1040 
                 1060 
               
               
                   
                 CD3-VH-G11 
                 1001 
                 1021 
                 1041 
                 1061 
               
               
                   
                 CD3-VH-G12 
                 1002 
                 1022 
                 1042 
                 1062 
               
               
                   
                 CD3-VH-G13 
                 1003 
                 1023 
                 1043 
                 1063 
               
               
                   
                 CD3-VH-G14 
                 1004 
                 1024 
                 1044 
                 1064 
               
               
                   
                 CD3-VH-G15 
                 1005 
                 1025 
                 1045 
                 1065 
               
               
                   
                 CD3-VH-G16 
                 1006 
                 1026 
                 1046 
                 1066 
               
               
                   
                 CD3-VH-G17 
                 1007 
                 1027 
                 1047 
                 1067 
               
               
                   
                 CD3-VH-G18 
                 1008 
                 1028 
                 1048 
                 1068 
               
               
                   
                 CD3-VH-G19 
                 1009 
                 1029 
                 1049 
                 1069 
               
               
                   
                 CD3-VH-G20 
                 1010 
                 1030 
                 1050 
                 1070 
               
               
                   
                 CD3-VH-G21 
                 1011 
                 1031 
                 1051 
                 1071 
               
               
                   
                 CD3-VH-P 
                 1012 
                 1032 
                 1052 
                 1072 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 6 
               
             
            
               
                   
               
               
                 Light Chain Amino Acid Sequence Identifiers 
               
            
           
           
               
               
            
               
                 Antibody 
                 SEQ ID NOs: 
               
            
           
           
               
               
               
               
               
            
               
                 Designation 
                 LCVR 
                 CDR1 
                 CDR2 
                 CDR3 
               
               
                   
               
               
                 VK1-39JK5 
                 1073 
                 1074 
                 1075 
                 1076 
               
               
                   
               
            
           
         
       
     
     In certain exemplary embodiments, the first antigen-binding domain that specifically binds human CD3 comprises heavy chain complementarity determining regions (HCDR1, HCDR2 and HCDR3) from a heavy chain variable region (HCVR) selected from the group consisting of SEQ ID NOs: 993, 997, 999, 1000, and 1010, and light chain complementarity determining regions (LCDR1, LCDR2 and LCDR3) from a light chain variable region (LCVR) comprising an amino acid sequence of SEQ ID NO: 118. 
     In certain exemplary embodiments, the first antigen-binding domain that specifically binds human CD3 comprises three heavy chain complementarity determining regions (A1-HCDR1, A1-HCDR2 and A1-HCDR3) and three light chain complementarity determining regions (A1-LCDR1, A1-LCDR2 and A1-LCDR3), wherein A1-HCDR1 comprises an amino acid sequence selected from the group consisting of SEQ ID NOs:1013, 1017, 1019, 1020, and 1030; A1-HCDR2 comprises an amino acid sequence selected from the group consisting of SEQ ID NOs:1033, 1037, 1039, 1040, and 1050; A1-HCDR3 comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 1053, 1057, 1059, 1060, and 1070; A1-LCDR1 comprises an amino acid sequence of SEQ ID NO: 147; A1-LCDR2 comprises an amino acid sequence of SEQ ID NO: 176; and A1-LCDR3 comprises an amino acid sequence of SEQ ID NO: 205. 
     In certain exemplary embodiments, the first antigen-binding domain that specifically binds human CD3 comprises the heavy and light chain CDRs of a HCVR/LCVR amino acid sequence pair selected from the group consisting of: SEQ ID NOs: 993/118, 997/118, 999/118, 1000/118, and 1010/118. 
     In certain exemplary embodiments, the first antigen-binding domain that specifically binds human CD3 comprises three heavy chain complementarity determining regions (A1-HCDR1, A1-HCDR2 and A1-HCDR3) and three light chain complementarity determining regions (A1-LCDR1, A1-LCDR2 and A1-LCDR3), and the second antigen-binding domain that specifically binds human MUC16 comprises three heavy chain complementarity determining regions (A2-HCDR1, A2-HCDR2 and A2-HCDR3) and three light chain complementarity determining regions (A2-LCDR1, A2-LCDR2 and A2-LCDR3); wherein A1-HCDR1 comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 1013, 1017, 1019, 1020, and 1030; A1-HCDR2 comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 1033, 1037, 1039, 1040, and 1050; A1-HCDR3 comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 1053, 1057, 1059, 1060, and 1070; A1-LCDR1 comprises an amino acid sequence of SEQ ID NO: 147; A1-LCDR2 comprises an amino acid sequence of SEQ ID NO: 176; and A1-LCDR3 comprises an amino acid sequence of SEQ ID NO: 205; and wherein A2-HCDR1 comprises an amino acid sequence of SEQ ID NO: 31; A2-HCDR2 comprises an amino acid sequence of SEQ ID NO: 60; A2-HCDR3 comprises an amino acid sequence of SEQ ID NO: 89; A2-LCDR1 comprises an amino acid sequence of SEQ ID NO: 147; A2-LCDR2 comprises an amino acid sequence of SEQ ID NO: 176; and A2-LCDR3 comprises an amino acid sequence of SEQ ID NO: 205. 
     Additional bispecific anti-MUC16×anti-CD3 antibodies disclosed in, e.g., WO 2018/067331, which is hereby incorporated by reference. 
     Exemplary CD3×BCMA Antibodies 
     In some embodiments, the methods and compositions provided herein include bispecific antibodies wherein one arm of an immunoglobulin binds human CD3, and the other arm of the immunoglobulin is specific for human BCMA. The term “BCMA,” as used herein, refers to the human BCMA protein unless specified as being from a non-human species (e.g., “mouse BCMA,” “monkey BCMA,” etc.). The human BCMA protein has the amino acid sequence shown in SEQ ID NO: 115 of U.S. Patent Application Publication No. US 2020/0024356A1 (SEQ ID NO: 1139), the content of which is incorporated herein by reference in its entirety. Such molecules may be referred to herein as, e.g., “anti-BCMA×anti-CD3” or “anti-CD3/anti-BCMA,” or “anti-CD3×BCMA” or “CD3×BCMA” bispecific molecules, or other similar terminology (e.g., anti-BCMA/anti-CD3). The BCMA-binding arm can comprise any of the HCVR/LCVR or CDR amino acid sequences as set forth in Table 7 herein. The CD3-binding arm can comprise any of the HCVR/LCVR or CDR amino acid sequences as set forth in Table 8 herein, or the anti-CD3 antibodies disclosed in WO 2014/047231 or WO 2017/053856. Sequences in Tables 7 and 8 were disclosed in U.S. Patent Application Publication No. US 2020/0024356A1, the content of which is incorporated herein by reference in its entirety. 
     Table 7 sets forth the amino acid sequence identifiers of the heavy and light chain variable regions and CDRs of selected anti-BCMA antibodies of the invention. 
     
       
         
           
               
             
               
                 TABLE 7 
               
             
            
               
                   
               
               
                 Amino Acid Sequence Identifiers 
               
            
           
           
               
               
            
               
                 Antibody 
                 SEQ ID NOs: 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Designation 
                 HCVR 
                 HCDR1 
                 HCDR2 
                 HCDR3 
                 LCVR 
                 LCDR1 
                 LCDR2 
                 LCDR3 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 mAb16711 
                 1077 
                 1084 
                 1089 
                 1094 
                 1099 
                 1106 
                 1111 
                 1116 
               
               
                 mAb16716 
                 1078 
                 1085 
                 1090 
                 1095 
                 1100 
                 1107 
                 1112 
                 1117 
               
               
                 mAb16732 
                 1079 
                 1086 
                 1091 
                 1096 
                 1101 
                 1108 
                 1113 
                 1118 
               
               
                 mAb16747 
                 1080 
                 1087 
                 1092 
                 1097 
                 1102 
                 1109 
                 1114 
                 1119 
               
               
                 mAb21581 
                 1081 
                 1088 
                 1093 
                 1098 
                 1103 
                 1110 
                 1115 
                 1120 
               
               
                 mAb21587 
                 1082 
                   
                   
                   
                 1104 
                   
                   
                   
               
               
                 mAb21589 
                 1083 
                   
                   
                   
                 1105 
               
               
                   
               
            
           
         
       
     
     Table 8 sets forth the amino acid sequence identifiers of the heavy and light chain variable regions and CDRs of selected anti-CD3 antibodies. Other anti-CD3 antibodies for use in preparing bispecific antibodies in accordance with the present invention can be found in, e.g., WO 2014/047231. 
     
       
         
           
               
             
               
                 TABLE 8 
               
             
            
               
                   
               
               
                 Amino Acid Sequence Identifiers 
               
            
           
           
               
               
            
               
                 Antibody 
                 SEQ ID NOs: 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Designation 
                 HCVR 
                 HCDR1 
                 HCDR2 
                 HCDR3 
                 LCVR 
                 LCDR1 
                 LCDR2 
                 LCDR3 
               
               
                   
               
               
                 mAb7221G 
                 1121 
                 1123 
                 1125 
                 1127 
                 1129 
                 1130 
                 1131 
                 1132 
               
               
                 mAb7221G20 
                 1122 
                 1124 
                 1126 
                 1128 
                 1129 
                 1130 
                 1131 
                 1132 
               
               
                   
               
            
           
         
       
     
     In certain exemplary embodiments, the isolated anti-BCMA×anti-CD3 bispecific antigen binding molecule comprises a first antigen-binding domain that comprises: (a) three heavy chain complementarity determining regions (HCDR1, HCDR2 and HCDR3) contained within a heavy chain variable region (HCVR) comprising the amino acid sequence of SEQ ID NO: 1081; and (b) three light chain complementarity determining regions (LCDR1, LCDR2 and LCDR3) contained within a light chain variable region (LCVR) comprising the amino acid sequence of SEQ ID NO: 1129. In some cases, the isolated bispecific antigen binding molecule comprises a HCDR1 comprising the amino acid sequence of SEQ ID NO: 1088, a HCDR2 comprising the amino acid sequence of SEQ ID NO: 1093, and a HCDR3 comprising the amino acid sequence of SEQ ID NO: 1098. In some cases, the isolated bispecific antigen-binding molecule comprises a LCDR1 comprising the amino acid sequence of SEQ ID NO: 1130, a LCDR2 comprising the amino acid sequence of SEQ ID NO: 1131, and a LCDR3 comprising the amino acid sequence of SEQ ID NO: 1132. In some cases, the first antigen-binding domain comprises a HCVR comprising the amino acid sequence of SEQ ID NO: 1081, and a LCVR comprising the amino acid sequence of SEQ ID NO: 1129. 
     In certain exemplary embodiments, the isolated anti-BCMA×anti-CD3 bispecific antigen-binding molecule comprises a second antigen-binding domain that comprises: (a) three heavy chain complementarity determining regions (HCDR1, HCDR2 and HCDR3) contained within a heavy chain variable region (HCVR) comprising the amino acid sequence of SEQ ID NO: 1121 or SEQ ID NO: 1122; and (b) three light chain complementarity determining regions (LCDR1, LCDR2 and LCDR3) contained within a light chain variable region (LCVR) comprising the amino acid sequence of SEQ ID NO: 1129. In some cases, the second antigen-binding domain comprises: (a) a HCDR1 comprising the amino acid sequence of SEQ ID NO: 1123 or SEQ ID NO: 1124; (b) a HCDR2 comprising the amino acid sequence of SEQ ID NO: 1125 or SEQ ID NO: 1126; and (c) a HCDR3 comprising the amino acid sequence of SEQ ID NO: 1127 or SEQ ID NO: 1128. In some cases, the second antigen-binding domain comprises a LCDR1 comprising the amino acid sequence of SEQ ID NO: 1130, a LCDR2 comprising the amino acid sequence of SEQ ID NO: 1131, and a LCDR3 comprising the amino acid sequence of SEQ ID NO: 1132. In some cases, the second antigen-binding domain comprises: (a) HCDR1, HCDR2, HCDR3 domains, respectively, comprising the amino acid sequences of SEQ ID NOs: 1123, 1125, 1127; and LCDR1, LCDR2, LCDR3 domains, respectively, comprising the amino acid sequences of SEQ ID NOs: 1130, 1131, 1132; or (b) HCDR1, HCDR2, HCDR3 domains, respectively, comprising the amino acid sequences of SEQ ID NOs: 1124, 1126, 1128; and LCDR1, LCDR2, LCDR3 domains, respectively, comprising the amino acid sequences of SEQ ID NOs: 1130, 1131, 1132. In some cases, the second antigen-binding domain comprises: (a) a HCVR comprising the amino acid sequence of SEQ ID NO: 1121, and a LCVR comprising the amino acid sequence of SEQ ID NO: 1129; or (b) a HCVR comprising the amino acid sequence of SEQ ID NO: 1122, and a LCVR comprising the amino acid sequence of SEQ ID NO: 1129. 
     In certain exemplary embodiments, the isolated anti-BCMA×anti-CD3 bispecific antigen-binding molecule comprises: (a) a first antigen-binding domain that comprises HCDR1, HCDR2, HCDR3 domains, respectively, comprising the amino acid sequences of SEQ ID NOs: 1088, 1093, 1098, and LCDR1, LCDR2, LCDR3 domains, respectively, comprising the amino acid sequences of SEQ ID NOs: 1130, 1131, 1132; and (b) a second antigen binding domain that comprises HCDR1, HCDR2, HCDR3 domains, respectively, comprising the amino acid sequences of SEQ ID NOs: 1123, 1125, 1127, and LCDR1, LCDR2, LCDR3 domains, respectively, comprising the amino acid sequences of SEQ ID NOs: 1130, 1131, 1132. In some cases, the isolated bispecific antigen-binding molecule comprises: (a) a first antigen binding domain that comprises a HCVR comprising the amino acid sequence of SEQ ID NO: 1081, and a LCVR comprising the amino acid sequence of SEQ ID NO: 1129; and (b) a second antigen binding domain that comprises a HCVR comprising the amino acid sequence of SEQ ID NO: 1121, and a LCVR comprising the amino acid sequence of SEQ ID NO:1129. 
     In certain exemplary embodiments, the isolated anti-BCMA×anti-CD3 bispecific antigen-binding molecule comprises: (a) a first antigen-binding domain that comprises HCDR1, HCDR2, HCDR3 domains, respectively, comprising the amino acid sequences of SEQ ID NOs: 1088, 1093, 1098, and LCDR1, LCDR2, LCDR3 domains, respectively, comprising the amino acid sequences of SEQ ID NOs: 1130, 1131, 1132; and (b) a second antigen binding domain that comprises HCDR1, HCDR2, HCDR3 domains, respectively, comprising the amino acid sequences of SEQ ID NOs: 1124, 1126, 1128, and LCDR1, LCDR2, LCDR3 domains, respectively, comprising the amino acid sequences of SEQ ID NOs: 1130, 1131, 1132. In some cases, the isolated bispecific antigen-binding molecule comprises: (a) a first antigen binding domain that comprises a HCVR comprising the amino acid sequence of SEQ ID NO: 1081, and a LCVR comprising the amino acid sequence of SEQ ID NO: 1129; and (b) a second antigen binding domain that comprises a HCVR comprising the amino acid sequence of SEQ ID NO: 1122, and a LCVR comprising the amino acid sequence of SEQ ID NO: 1129. 
     In certain exemplary embodiments, the isolated anti-BCMA×anti-CD3 bispecific antigen-binding molecule comprises: (a) a first antigen-binding domain that specifically binds human BCMA, and comprises the CDRs of a HCVR comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 1077, 1078, 1079, 1080, 1081, 1082, and 1083, and the CDRs of a LCVR comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 1099, 1100, 1101, 1102, 1103, 1129, 1104, and 1105; and (b) a second antigen-binding domain that specifically binds human CD3. In some cases, the first antigen-binding domain comprises the CDRs from a HCVR/LCVR amino acid sequence pair selected from the group consisting of SEQ ID NOs: 1077/1099, 1078/1100, 1079/1101, 1080/1102, 1081/1103, 1082/1104, 1083/1105, 1077/1129, 1078/1129, 1079/1129, 1080/1129, 1081/1129, 1082/1129, and 1083/1129. In some cases, the first antigen-binding domain comprises HCDR1-HCDR2-HCDR3-LCDR1-LCDR2-LCDR3 domains, respectively, selected from the group consisting of SEQ ID NOs: 1084-1089-1094-1106-1111-1116, 1085-1090-1095-1107-1112-1117, 1086-1091-1096-1108-1113-1118, 1087-1092-1097-1109-1114-1119, 1088-1093-1098-1110-1115-1120, 1084-1089-1094-1130-1131-1132, 1085-1090-1095-1130-1131-1132, 1086-1091-1096-1130-1131-1132, 1087-1092-1097-1130-1131-1132, and 1088-1093-1098-1130-1131-1132. In some cases, the first antigen-binding domain comprises the a HCVR/LCVR amino acid sequence pair selected from the group consisting of SEQ ID NOs: 1077/1099, 1078/1100, 1079/1101, 1080/1102, 1081/1103, 1082/1104, 1083/1105, 1077/1129, 1078/1129, 1079/1129, 1080/1129, 1081/1129, 1082/1129, and 1083/1129. In some cases, the second antigen-binding domain comprises the CDRs of a HCVR/LCVR amino acid sequence pair selected from the group consisting of SEQ ID NOs: 1121/1129 and 1122/1129. 
     In certain exemplary embodiments, the isolated anti-BCMA×anti-CD3 bispecific antigen binding molecule competes for binding to BCMA, or binds to the same epitope on BCMA as a reference antibody, wherein the reference antibody comprises a first antigen-binding domain comprising an HCVR/LCVR pair comprising the amino acid sequences of SEQ ID NOs: 1081/1129 and a second antigen-binding domain comprising an HCVR/LCVR pair comprising the amino acid sequences of either SEQ ID NOs: 1121/1129 or SEQ ID NOs: 1122/1129. 
     In certain exemplary embodiments, the isolated anti-BCMA×anti-CD3 bispecific antigen binding molecule competes for binding to human CD3, or binds to the same epitope on human CD3 as a reference antibody, wherein the reference antibody comprises a first antigen-binding domain comprising an HCVR/LCVR pair comprising the amino acid sequences of SEQ ID NOs: 1081/1129 and a second antigen-binding domain comprising an HCVR/LCVR pair comprising the amino acid sequences of either SEQ ID NOs: 1121/1129 or SEQ ID NOs: 1122/1129. 
     Additional bispecific anti-BCMA×anti-CD3 antibodies are disclosed in, e.g., WO 2020/018820. 
     CD3×CD20 Antibodies 
     In some embodiments, provided herein are bispecific antibodies wherein one arm of an immunoglobulin binds human CD3, and the other arm of the immunoglobulin is specific for human CD20. The term “CD20,” as used herein, refers to the human CD20 protein unless specified as being from a non-human species (e.g., “mouse CD20,” “monkey CD20,” etc.). The human CD20 protein has the amino acid sequence shown in SEQ ID NO:1369 of U.S. Pat. No. 9,657,102B2 (SEQ ID NO: 1142), the content of which is incorporated by reference herein in it entirety. Such molecules may be referred to herein as, e.g., “anti-CD3/anti-CD20,” or “anti-CD3×CD20” or “CD3×CD20” bispecific molecules, or other similar terminology. 
     In certain embodiments, the first antigen-binding domain that specifically binds CD3 comprises a heavy chain variable region (HCVR) having an amino acid sequence selected from the group consisting of SEQ ID NOs: 1147, 1155, 1163, 1171, 1179 and 1187 or a substantially similar sequence thereof having at least 90%, at least 95%, at least 98% or at least 99% sequence identity. All sequences disclosed in this section for antigen-binding domains that specifically bind CD3 or CD20 are from U.S. Pat. No. 9,657,102B2, the content of which is incorporated by reference herein in it entirety. 
     In certain embodiments, the first antigen-binding domain that specifically binds CD3 comprises a light chain variable region (LCVR) having an amino acid sequence selected from the group consisting of SEQ ID NOs: 1151, 1159, 1167, 1175, 1183 and 1191, or a substantially similar sequence thereof having at least 90%, at least 95%, at least 98% or at least 99% sequence identity. 
     In certain embodiments, the first antigen-binding domain that specifically binds CD3 comprises a HCVR and LCVR (HCVR/LCVR) amino acid sequence pair selected from the group consisting of SEQ ID NOs: 1147/1151, 1155/1159, 1163/1167, 1171/1175, 1179/1183, and 1187/1191. 
     In certain embodiments, the first antigen-binding domain that specifically binds CD3 comprises a heavy chain CDR1 (HCDR1) domain having an amino acid sequence selected from the group consisting of SEQ ID NOs: 1148, 1156, 1164, 1172, 1180 and 1188, or a substantially similar sequence thereof having at least 90%, at least 95%, at least 98% or at least 99% sequence identity; a heavy chain CDR2 (HCDR2) domain having an amino acid sequence selected from the group consisting of SEQ ID NOs:1149, 1157, 1165, 1173, 1181 and 1189, or a substantially similar sequence thereof having at least 90%, at least 95%, at least 98% or at least 99% sequence identity; a heavy chain CDR3 (HCDR3) domain having an amino acid sequence selected from the group consisting of SEQ ID NOs:1150, 1158, 1166, 1174, 1182 and 1190, or a substantially similar sequence thereto having at least 90%, at least 95%, at least 98% or at least 99% sequence identity; a light chain CDR1 (LCDR1) domain having an amino acid sequence selected from the group consisting of SEQ ID NOs: 1152, 1160, 1168, 1176, 1184 and 1192, or a substantially similar sequence thereof having at least 90%, at least 95%, at least 98% or at least 99% sequence identity; a light chain CDR2 (LCDR2) domain having an amino acid sequence selected from the group consisting of SEQ ID NOs:1153, 1161, 1169, 1177, 1185 and 1193, or a substantially similar sequence thereof having at least 90%, at least 95%, at least 98% or at least 99% sequence identity, and a light chain CDR3 (LCDR3) domain having an amino acid sequence selected from the group consisting of SEQ ID NOs:1154, 1162, 1170, 1178, 1186 and 1194, or a substantially similar sequence thereof having at least 90%, at least 95%, at least 98% or at least 99% sequence identity. 
     In certain embodiments, the first antigen-binding domain that specifically binds CD3 comprises HCDR1-HCDR2-HCDR3-LCDR1-LCDR2-LCDR3 domains, respectively, having the amino acid sequences selected from the group consisting of: SEQ ID NOs: 1148-1149-1150-1152-1153-1154; 1156-1157-1158-1160-1161-1162; 1164-1165-1166-1168-1169-1170; 1172-1173-1174-1176-1177-1178; 1180-1181-1182-1184-1185-1186; and 1188-1189-1190-1192-1193-1194. 
     In certain embodiments, the second antigen-binding domain that specifically binds CD20 comprises a heavy chain variable region (HCVR) having the amino acid sequence of SEQ ID NO: 1143, or a substantially similar sequence thereof having at least 90%, at least 95%, at least 98% or at least 99% sequence identity. 
     In certain embodiments, the second antigen-binding domain that specifically binds CD20 comprises a light chain variable region (LCVR) having the amino acid sequence selected from the group consisting of SEQ ID NOs: 1151, 1159, 1167, 1175, 1183 and 1191, or a substantially similar sequence thereof having at least 90%, at least 95%, at least 98% or at least 99% sequence identity. 
     In certain embodiments, the second antigen-binding domain that specifically binds CD20 comprises a HCVR and LCVR (HCVR/LCVR) amino acid sequence pair selected from the group consisting of SEQ ID NOs: 1143/1151, 1143/1159, 1143/1167, 1143/1175, 1143/1183 and 1143/1191. 
     In certain embodiments, the second antigen-binding domain that specifically binds CD20 comprises a heavy chain CDR1 (HCDR1) domain having the amino acid sequence of SEQ ID NO:1144, or a substantially similar sequence thereof having at least 90%, at least 95%, at least 98% or at least 99% sequence identity; a heavy chain CDR2 (HCDR2) domain having the amino acid sequence of SEQ ID NO: 1145, or a substantially similar sequence thereof having at least 90%, at least 95%, at least 98% or at least 99% sequence identity; a heavy chain CDR3 (HCDR3) domain having the amino acid sequence of SEQ ID NO:1146, or a substantially similar sequence thereto having at least 90%, at least 95%, at least 98% or at least 99% sequence identity; a light chain CDR1 (LCDR1) domain having an amino acid sequence selected from the group consisting of SEQ ID NOs: 1152, 1160, 1168, 1176, 1184 and 1192, or a substantially similar sequence thereof having at least 90%, at least 95%, at least 98% or at least 99% sequence identity; a light chain CDR2 (LCDR2) domain having an amino acid sequence selected from the group consisting of SEQ ID NOs:1153, 1161, 1169, 1177, 1185 and 1193, or a substantially similar sequence thereof having at least 90%, at least 95%, at least 98% or at least 99% sequence identity; and a light chain CDR3 (LCDR3) domain having an amino acid sequence selected from the group consisting of SEQ ID NOs:1154, 1162, 1170, 1178, 1186 and 1194, or a substantially similar sequence thereof having at least 90%, at least 95%, at least 98% or at least 99% sequence identity. 
     In certain embodiments, the second antigen-binding domain that specifically binds CD20 comprises HCDR1-HCDR2-HCDR3-LCDR1-LCDR2-LCDR3 domains, respectively, having the amino acid sequences selected from the group consisting of: SEQ ID NOs:1144-1145-1146-1152-1153-1154; 1144-1145-1146-1160-1161-1162; 1144-1145-1146-1168-1169-1170; 1144-1145-1146-1176-1177-1178; 1144-1145-1146-1184-1185-1186; and 1144-1145-1146-1192-1193-1194. 
     Additional bispecific anti-CD20/anti-CD3 antibodies are disclosed in e.g., U.S. Pat. No. 9,657,102, which is incorporated by reference herein in its entirety. 
     Other Exemplary CD3 Multispecific Antibodies 
     Additional exemplary CD3 multispecific antibodies that can be used in the compositions and methods of the present invention include but are not limited to, e.g., bispecific CD3×CD123 antibodies disclosed in U.S. Pat. No. 10,787,521B2, U.S. Patent Application Publication Nos. 2018/0222987A1 and US 2019/0241657A1, and International Application Publication Nos. WO 2016/036937A1, WO 2017/210443A1, WO 2019/050521A1, WO 2019/210147A1, WO 2019/232528A1, and WO 2020/092404A1; bispecific CD3×STEAP2 antibodies disclosed in International Application Publication Nos. WO 2018/058001A1; bispecific CD3×CD20 antibodies disclosed in WO 2014/047231A1, WO 2015/143079A1, WO 2016/081490A1, WO 2017/112775A1, WO 2017/210485A1, WO 2018/114748A1, WO 2018/093821A8, WO 2018/223004A1, WO 2018/188612A1, WO 2019/155008A1, WO 2019/228406A1, WO 2020/088608A1, WO 2020/156405A1, and U.S. Patent Application Publication Nos. US 2020/0199231A1, and US 2020/0172627A1; bispecific CD3×SSTR 2 antibodies disclosed in International Application Publication No. WO 2018/005706A1; bispecific CD3×CD38 antibodies disclosed in International Application Nos. WO 2015/149077A1 and WO 2020/018556A1, and U.S. Patent Application Publication Nos. US 2018/0305465A1 and US 2020/0102403A1; bispecific CD3×STEAP1 antibodies disclosed in Olivier Nolan-Stevaux (2020) Abstract at Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; bispecific CD3×5T4 antibodies disclosed in International Application Publication No. WO 2013/041687A1, U.S. Patent Application Publication Nos. US 2017/0342160A1, US 20200277397A1; bispecific CD3×ENPP3 antibodies as descried in International Application Publication No. WO 2020/180726A1; bispecific CD3×MUC16 antibodies disclosed in International Application Publication Nos. WO 2018/067331A9 and WO 2019/246356A1; bispecific CD3×BCMA antibodies disclosed in International Application Publication Nos. WO 2013/072406A1, WO 2014/140248A1, WO 2016/166629A1, WO 2017/031104A1, WO 2017/134134A1, WO 2017/095267A1, WO 2019/220369A3, WO 2019/075359A1, WO 2019/226761A1, WO 2020/025596A1, WO 2020/191346A1, WO 2020018820A1, U.S. Patent Application Publication Nos. US 2013/0273055A1, US 2019/0263920A1; bispecific CD3×CD19 antibodies disclosed in International Application Publication Nos. WO 2012/055961A1, WO 2016/048938A1, WO 2017/087603A1, WO 2017/096368A1, WO 2018/188612A1, WO 2019/237081A1, WO 2020/048525A1, WO 2020/135335A1, U.S. Patent Application Publication Nos. US 2016/0326249A1, US 2020/0283523A1, US 2019/0284279A1, U.S. Pat. No. 9,315,567B2, U.S. Pat. No. 7,575,923B2, U.S. Pat. No. 7,635,472B2; bispecific CD3×GPRC5D antibodies disclosed in International Application Publication Nos. WO 2018/017786A3, WO 2019/220369A3; bispecific CD3×PSMA antibodies disclosed in U.S. Patent Application Publication No. US 2017/0320947A1; trispecific CD3×CD28×CD38 antibodies disclosed in U.S. Patent Application Publication No. US 2020/0140552A1; or other CD3 multispecific antibodies disclosed in International Application Publication Nos. WO 2016/086189A2, WO 2020/088608A1, WO2019191120A1, and WO 2016/105450A3, the contents of each of which is incorporated by reference herein in its entirety. 
     In some embodiments, the aforementioned multispecific (e.g., bispecific or trispecific) antigen-binding molecules that specifically bind CD3 and a tumor antigen may comprise an anti-CD3 antigen-binding molecule which binds to CD3 with a weak binding affinity such as exhibiting a K D  of greater than about 40 nM, as measured by an in vitro affinity binding assay. The aforementioned bispecific antigen-binding molecules may comprise an anti-CD3 antigen-binding molecule which binds to CD3 and exhibits an EC50 of greater than about 100 nM, as measured by a FACS titration assay. The aforementioned bispecific antigen-binding molecules may comprise an anti-CD3 antigen-binding molecule which exhibits no measurable or observable binding to CD3, as measured by an in vitro affinity binding assay or a FACS titration assay, yet retains ability to activate human PBMC cells and/or induce cytotoxic activity on tumor antigen-expressing cell lines. 
     Therapeutic Formulation and Administration 
     In some aspects, provided herein are pharmaceutical compositions comprising a CD40 antagonist (e.g., a CD40 antagonist antibody, or an antigen binding fragment thereof) as described herein. In some aspects, provided herein are pharmaceutical compositions comprising a CD3 multispecific antigen-binding molecule as described herein. In some aspects, provided herein are pharmaceutical compositions in which a CD3 multispecific antigen-binding molecule described herein is co-formulated with a CD40 antagonist (e.g., a CD40 antagonist antibody, or an antigen binding fragment thereof) as described elsewhere herein. 
     The pharmaceutical compositions provided herein can be formulated with suitable carriers, excipients, and other agents that provide improved transfer, delivery, tolerance, and the like. A multitude of appropriate formulations can be found in the formulary known to all pharmaceutical chemists: Remington&#39;s Pharmaceutical Sciences, Mack Publishing Company, Easton, Pa. These formulations include, for example, powders, pastes, ointments, jellies, waxes, oils, lipids, lipid (cationic or anionic) containing vesicles (such as LIPOFECTIN™, Life Technologies, Carlsbad, Calif.), DNA conjugates, anhydrous absorption pastes, oil-in-water and water-in-oil emulsions, emulsions carbowax (polyethylene glycols of various molecular weights), semi-solid gels, and semi-solid mixtures containing carbowax. See also Powell et al. “Compendium of excipients for parenteral formulations” PDA (1998) J Pharm Sci Technol 52:238-311. 
     The dose of antigen-binding molecule administered to a patient may vary depending upon the age and the size of the patient, target disease, conditions, route of administration, and the like. 
     Various delivery systems are known and can be used to administer a pharmaceutical composition provided herein, e.g., encapsulation in liposomes, microparticles, microcapsules, recombinant cells capable of expressing the mutant viruses, receptor mediated endocytosis (see, e.g., Wu et al., 1987, J. Biol. Chem. 262:4429-4432). Methods of introduction include, but are not limited to, intradermal, intramuscular, intraperitoneal, intravenous, subcutaneous, intranasal, epidural, and oral routes. The composition 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 some embodiments, a pharmaceutical composition provided herein can be delivered subcutaneously or intravenously with a standard needle and syringe. In addition, with respect to subcutaneous delivery, a pen delivery device readily has applications in delivering a pharmaceutical composition of the present invention. Such a pen delivery device can be reusable or disposable. A reusable pen delivery device generally utilizes a replaceable cartridge that contains a pharmaceutical composition. Once all of the pharmaceutical composition within the cartridge has been administered and the cartridge is empty, the empty cartridge can readily be discarded and replaced with a new cartridge that contains the pharmaceutical composition. The pen delivery device can then be reused. In a disposable pen delivery device, there is no replaceable cartridge. Rather, the disposable pen delivery device comes prefilled with the pharmaceutical composition held in a reservoir within the device. Once the reservoir is emptied of the pharmaceutical composition, the entire device is discarded. 
     Numerous reusable pen and autoinjector delivery devices have applications in the subcutaneous delivery of a pharmaceutical composition of the present invention. Examples include, but are not limited to AUTOPEN™ (Owen Mumford, Inc., Woodstock, UK), DISETRONIC™ pen (Disetronic Medical Systems, Bergdorf, Switzerland), HUMALOG MIX 75/25™ pen, HUMALOG™ pen, HUMALIN 70/30™ pen (Eli Lilly and Co., Indianapolis, Ind.), NOVOPEN™ I, II and III (Novo Nordisk, Copenhagen, Denmark), NOVOPEN JUNIOR™ (Novo Nordisk, Copenhagen, Denmark), BD™ pen (Becton Dickinson, Franklin Lakes, N.J.), OPTIPEN™, OPTIPEN PRO™, OPTIPEN STARLET™, and OPTICLIK™ (sanofi-aventis, Frankfurt, Germany), to name only a few. Examples of disposable pen delivery devices having applications in subcutaneous delivery of a pharmaceutical composition of the present invention include, but are not limited to the SOLOSTAR™ pen (sanofi-aventis), the FLEXPEN™ (Novo Nordisk), and the KWIKPEN™ (Eli Lilly), the SURECLICK™ Autoinjector (Amgen, Thousand Oaks, Calif.), the PENLET™ (Haselmeier, Stuttgart, Germany), the EPIPEN (Dey, L. P.), and the HUMIRA™ Pen (Abbott Labs, Abbott Park Ill.), to name only a few. 
     In certain situations, the pharmaceutical composition can be delivered in a controlled release system. In one embodiment, a pump may be used (see Langer, supra; Sefton, 1987, CRC Crit. Ref. Biomed. Eng. 14:201). In another embodiment, polymeric materials can be used; see, Medical Applications of Controlled Release, Langer and Wise (eds.), 1974, CRC Pres., Boca Raton, Fla. In yet another embodiment, a controlled release system can be placed in proximity of the composition&#39;s target, thus requiring only a fraction of the systemic dose (see, e.g., Goodson, 1984, in Medical Applications of Controlled Release, supra, vol. 2, pp. 115-138). Other controlled release systems are discussed in the review by Langer, 1990, Science 249:1527-1533. 
     The injectable preparations may include dosage forms for intravenous, subcutaneous, intracutaneous and intramuscular injections, drip infusions, etc. These injectable preparations may be prepared by methods publicly known. For example, the injectable preparations may be prepared, e.g., by dissolving, suspending or emulsifying the antibody or its salt described above in a sterile aqueous medium or an oily medium conventionally used for injections. As the aqueous medium for injections, there are, for example, physiological saline, an isotonic solution containing glucose and other auxiliary agents, etc., which may be used in combination with an appropriate solubilizing agent such as an alcohol (e.g., ethanol), a polyalcohol (e.g., propylene glycol, polyethylene glycol), a nonionic surfactant [e.g., polysorbate 80, HCO-50 (polyoxyethylene (50 mol) adduct of hydrogenated castor oil)], etc. As the oily medium, there are employed, e.g., sesame oil, soybean oil, etc., which may be used in combination with a solubilizing agent such as benzyl benzoate, benzyl alcohol, etc. The injection thus prepared is preferably filled in an appropriate ampoule. 
     Advantageously, the pharmaceutical compositions for oral or parenteral use described above are prepared into dosage forms in a unit dose suited to fit a dose of the active ingredients. Such dosage forms in a unit dose include, for example, tablets, pills, capsules, injections (ampoules), suppositories, etc. 
     In some aspects, provided herein are pharmaceutical compositions comprising a CAR-T cell expressing a CD40 antagonist (e.g., a CD40 antagonist antibody, or an antigen binding fragment thereof) as described herein. 
     In certain embodiments, the CD40 antagonist expressing CAR-T cell populations may be administered either alone, or as a pharmaceutical composition in combination with pharmaceutically or physiologically acceptable carriers, diluents, excipients and/or with other components or cell populations. Such compositions may comprise buffers such as neutral buffered saline, phosphate buffered saline and the like; carbohydrates such as glucose, mannose, sucrose or dextrans, mannitol; proteins; polypeptides or amino acids such as glycine; antioxidants; chelating agents such as EDTA or glutathione; adjuvants (e.g., aluminum hydroxide); and preservatives. Compositions disclosed herein may be formulated for intravenous administration. 
     The administration of the CAR-T cell expressing a CD40 antagonist may be carried out in any convenient manner, including by injection, transfusion, or implantation. The compositions described herein may be administered to a patient subcutaneously, intradermally, intratumorally, intranodally, intramedullary, intramuscularly, by intravenous (i.v.) injection, or intraperitoneally. In some embodiments, the disclosed compositions are administered to a patient by intradermal or subcutaneous injection. In some embodiments, the disclosed compositions are administered by i.v. injection. The compositions may also be injected directly into a tumor, or lymph node. 
     Methods for Treating Cancers and/or Inhibiting Cytokine Release Syndrome 
     In some aspects, the present invention includes methods for treating cancer and inhibiting cytokine release syndrome (CRS) in a subject. In some embodiments, the methods may comprise conjointly (e.g., concurrently or sequentially) administering (1) a CD40 antagonist or a CAR-T cell expressing a CD40 antagonist; and (2) a multispecific (e.g., bispecific or trispecific) antigen binding molecule comprising at least a first antigen-binding domain against CD3 and a second antigen-binding domain against a tumor antigen to a subject in need thereof. In some embodiments, the methods may comprise administering a pharmaceutical composition comprising (1) a CD40 antagonist or a CAR-T cell expressing a CD40 antagonist; and (2) a multispecific (e.g., bispecific or trispecific) antigen binding molecule comprising at least a first antigen-binding domain against CD3 and a second antigen-binding domain against a tumor antigen to a subject in need thereof. The therapeutic composition may comprise any of the CD40 antagonist antibodies and CD3 multispecific antigen-binding molecules as disclosed herein and a pharmaceutically acceptable carrier or diluent. 
     In some aspects, the present invention includes methods for inhibiting cytokine release syndrome (CSR), or reduce cytokine release caused by a multispecific antigen binding molecule comprising a first antigen-binding domain that specifically binds CD3 and a second antigen-binding domain that specifically binds a tumor antigen in a subject. The methods according to this aspect of the invention comprise administering a CD40 antagonist or a CAR-T cell expressing a CD40 antagonist to a subject in need thereof. 
     In some aspects, the methods described above further comprise diagnosing or identifying subjects susceptible for cytokine release syndrome or in need of reduction in cytokine release. 
     As used herein, the terms “treat”, “treating”, or the like, mean to alleviate symptoms, or eliminate the causation of symptoms either on a temporary or permanent basis. For example, “treating cancer” may mean to delay or inhibit tumor growth, to reduce tumor cell load or tumor burden, to promote tumor regression, to cause tumor shrinkage, necrosis and/or disappearance, to prevent tumor recurrence, and/or to increase duration of survival of the subject. 
     As used herein, the expression “a subject in need thereof” means a human or non-human mammal that exhibits one or more symptoms or indications of cancer and/or CRS, and/or who has been diagnosed with cancer and/or CRS, and who needs treatment for the same. In many embodiments, the term “subject” may be interchangeably used with the term “patient”. 
     In some embodiments, cancers that may be treated by methods and compositions provided herein include, but are not limited to, cancer from the cervix, anus, vagina, vulva, penis, tongue base, larynx, tonsil, bladder, blood, bone, bone marrow, brain, breast, colon, esophagus, gastrointestine, gum, head, kidney, liver, lung, nasopharynx, neck, ovary, prostate, skin, non-melanoma skin cancer (NMSC), cutaneous squamous cell carcinoma (SCC), stomach, testis, tongue, or uterus. In addition, the cancer may specifically be of the following histological type, though it is not limited to these: neoplasm, malignant; carcinoma; carcinoma, undifferentiated; giant and spindle cell carcinoma; small cell carcinoma; papillary carcinoma; squamous cell carcinoma; lymphoepithelial carcinoma; basal cell carcinoma; pilomatrix carcinoma; transitional cell carcinoma; papillary transitional cell carcinoma; adenocarcinoma; gastrinoma, malignant; cholangiocarcinoma; hepatocellular carcinoma; combined hepatocellular carcinoma and cholangiocarcinoma; trabecular adenocarcinoma; adenoid cystic carcinoma; adenocarcinoma in adenomatous polyp; adenocarcinoma, familial polyposis coli; solid carcinoma; carcinoid tumor, malignant; branchiolo-alveolar adenocarcinoma; papillary adenocarcinoma; chromophobe carcinoma; acidophil carcinoma; oxyphilic adenocarcinoma; basophil carcinoma; clear cell adenocarcinoma; granular cell carcinoma; follicular adenocarcinoma; papillary and follicular adenocarcinoma; nonencapsulating sclerosing carcinoma; adrenal cortical carcinoma; endometrioid carcinoma; skin appendage carcinoma; apocrine adenocarcinoma; sebaceous adenocarcinoma; ceruminous adenocarcinoma; mucoepidermoid carcinoma; cystadenocarcinoma; papillary cystadenocarcinoma; papillary serous cystadenocarcinoma; mucinous cystadenocarcinoma; mucinous adenocarcinoma; signet ring cell carcinoma; infiltrating duct carcinoma; medullary carcinoma; lobular carcinoma; inflammatory carcinoma; mammary paget&#39;s disease; acinar cell carcinoma; adenosquamous carcinoma; adenocarcinoma w/squamous metaplasia; malignant thymoma; malignant ovarian stromal tumor; malignant thecoma; malignant granulosa cell tumor; and malignant roblastoma; sertoli cell carcinoma; malignant leydig cell tumor; malignant lipid cell tumor; malignant paraganglioma; malignant extra-mammary paraganglioma; pheochromocytoma; glomangiosarcoma; malignant melanoma; amelanotic melanoma; superficial spreading melanoma; malignant melanoma in giant pigmented nevus; epithelioid cell melanoma; malignant blue nevus; sarcoma; fibrosarcoma; malignant fibrous histiocytoma; myxosarcoma; liposarcoma; leiomyosarcoma; rhabdomyosarcoma; embryonal rhabdomyosarcoma; alveolar rhabdomyosarcoma; stromal sarcoma; malignant mixed tumor; mullerian mixed tumor; nephroblastoma; hepatoblastoma; carcinosarcoma; malignant mesenchymoma; malignant brenner tumor; malignant phyllodes tumor; synovial sarcoma; malignant mesothelioma; dysgerminoma; embryonal carcinoma; malignant teratoma; malignant struma ovarii; choriocarcinoma; malignant mesonephroma; hemangiosarcoma; malignant hemangioendothelioma; kaposi&#39;s sarcoma; malignant hemangiopericytoma; lymphangiosarcoma; osteosarcoma; juxtacortical osteosarcoma; chondrosarcoma; malignant chondroblastoma; mesenchymal chondrosarcoma; giant cell tumor of bone; ewing&#39;s sarcoma; malignant odontogenic tumor; ameloblastic odontosarcoma; malignant ameloblastoma; ameloblastic fibrosarcoma; malignant pinealoma; chordoma; malignant glioma; ependymoma; astrocytoma; protoplasmic astrocytoma; fibrillary astrocytoma; astroblastoma; glioblastoma; oligodendroglioma; oligodendroblastoma; primitive neuroectodermal; cerebellar sarcoma; ganglioneuroblastoma; neuroblastoma; retinoblastoma; olfactory neurogenic tumor; malignant meningioma; neurofibrosarcoma; malignant neurilemmoma; malignant granular cell tumor; malignant lymphoma; Hodgkin&#39;s disease; Hodgkin&#39;s lymphoma; paragranuloma; small lymphocytic malignant lymphoma; diffuse large cell malignant lymphoma; follicular malignant lymphoma; mycosis fungoides; other specified non-Hodgkin&#39;s lymphomas; malignant histiocytosis; multiple myeloma; mast cell sarcoma; immunoproliferative small intestinal disease; leukemia; lymphoid leukemia; plasma cell leukemia; erythroleukemia; lymphosarcoma cell leukemia; myeloid leukemia; basophilic leukemia; eosinophilic leukemia; monocytic leukemia; mast cell leukemia; megakaryoblastic leukemia; myeloid sarcoma; and hairy cell leukemia. 
     In some embodiments, cancers that may be treated by methods and compositions provided herein express the tumor antigen targeted by the CD3 multispecific antigen-binding molecules (e.g., a tumor with an expression of the tumor antigen as determined by flow cytometry on ≥20% of the tumor cells). In particular, the compositions and methods of the present invention may be used for the treatment, prevention and/or amelioration of any disease or disorder associated with or mediated by, e.g., CD20, PSMA, MUC16, STEAP2 or BCMA expression or activity or the proliferation of CD20+, PSMA+, MUC16+, STEAP2+, or BCMA+ cells. The mechanism of action by which the therapeutic methods of the invention are achieved include killing of the cells expressing such antigens in the presence of effector cells, for example, by CDC, apoptosis, ADCC, phagocytosis, or by a combination of two or more of these mechanisms. 
     In some embodiments, the CD3 multispecific antigen binding molecule used in the present compositions or methods is a bispecific anti-CD3×anti-PSMA antibody. The compositions or methods are useful for treating a PSMA-expressing cancer including prostate cancer, kidney cancer, bladder cancer, colorectal cancer, and gastric cancer. In some embodiments, the cancer is prostate cancer (e.g., castrate-resistant prostate cancer). 
     In some embodiments, the CD3 multispecific antigen binding molecule used in the present compositions or methods is a bispecific anti-CD3×anti-MUC16 antibody. The compositions or methods are useful for treating a MUC16-expressing cancer including ovarian cancer, breast cancer, pancreatic cancer, non-small-cell lung cancer, intrahepatic cholangiocarcinoma-mass forming type, adenocarcinoma of the uterine cervix, and adenocarcinoma of the gastric tract. In some embodiments, the cancer is ovarian cancer. 
     In some embodiments, the CD3 multispecific antigen binding molecule used in the present compositions or methods is a bispecific anti-CD3×anti-STEAP2 antibody. The compositions or methods are useful for treating a STEAP2-expressing cancer including prostate cancer, bladder cancer, cervical cancer, lung cancer, colon cancer, kidney cancer, breast cancer, pancreatic cancer, stomach cancer, uterine cancer, and ovarian cancer. In some embodiments, the cancer is prostate cancer (e.g., castrate-resistant prostate cancer). 
     In some embodiments, the CD3 multispecific antigen binding molecule used in the present compositions or methods is a bispecific anti-CD3×anti-BCMA antibody. The compositions or methods are useful for treating a BCMA-expressing cancer including multiple myeloma or other B-cell or plasma cell cancers, such as Waldenstrom&#39;s macroglobulinemia, Burkitt lymphoma, and diffuse large B-Cell lymphoma, Non-Hodgkin&#39;s lymphoma, chronic lymphocytic leukemia, follicular lymphoma, mantle cell lymphoma, marginal zone lymphoma, lymphoplasmacytic lymphoma, and Hodgkin&#39;s lymphoma. In some embodiments, the cancer is multiple myeloma. 
     In some embodiments, the CD3 multispecific antigen binding molecule used in the present compositions or methods is a bispecific anti-CD3×anti-CD20 antibody. The compositions or methods are useful for treating a CD20-expressing cancer including non-Hodgkin lymphoma, Hodgkin lymphoma, chronic lymphocytic leukemia, acute lymphoblastic leukemia, small lymphocytic lymphoma, diffuse large B-cell lymphoma, follicular lymphoma, mantle cell lymphoma, marginal zone lymphoma, Waldenstrom macroglobulinemia, primary mediastinal B-cell lymphoma, lymphoblastic lymphoma, or Burkitt lymphoma. In some embodiments, the cancer is follicular lymphoma. In some embodiments, the cancer is diffuse large B-cell lymphoma (DLBCL). 
     In some embodiments, the methods of the present invention are used in a subject (e.g., a cancer patient) with one or more symptoms or indications of cytokine release syndrome described herein, who has been diagnosed with cytokine release syndrome, and/or who are susceptible for cytokine release syndrome or in need of reduction in cytokine release. 
     In certain embodiments, the methods of the present invention are used in a subject that has been treated with certain cancer drugs (e.g., cancer immunotherapy, CAR-T cell therapy, or CD3 multispecific antigen binding molecules such as those described herein). 
     In some embodiments, for any of the methods disclosed herein, the subject treated, or the subject evaluated, is a subject to be treated or who has been treated with a cancer immunotherapy, e.g., a CD3 multispecific antigen binding molecule as described herein. 
     In some embodiments, the subject is at risk (e.g., at high risk) for developing CRS (e.g., severe CRS). In embodiments, the subject is at low risk (e.g., not at risk) for developing CRS (e.g., severe CRS). In some embodiments, the subject has CRS grade 0, CRS grade 1, CRS grade 2, or CRS grade 3. In some embodiments, the risk of a subject for developing CRS (e.g., severe CRS) is determined using an evaluation or prediction methods described herein. 
     In some embodiments, the methods provided herein treat, delay, or inhibit the growth of a tumor, or induce tumor cell death. In certain embodiments, the methods provided herein promote tumor regression. In certain embodiments, the methods provided herein reduce tumor cell load or to reduce tumor burden. In certain embodiments, the methods provided herein prevent tumor recurrence. 
     In some embodiments, the methods provided herein prevent, inhibit, alleviate, or treat CRS, e.g., by alleviating at least one symptom or indication associated with CRS, reducing CRS severity, or reducing cytokine release, etc. In some embodiments, the methods provided herein prevent, inhibit, alleviate, or treat CRS without negatively impacting the therapeutic benefits of the CD3 multispecific antigen binding molecule described herein. 
     In certain embodiments, the methods of the present invention comprise administering to a subject in need thereof a therapeutically effective amount of a CD40 antagonist or a CAR-T cell expressing a CD40 antagonist in combination with a therapeutically effective amount of a CD3 multispecific antigen binding molecule, wherein administration of a CD40 antagonist or a CAR-T cell expressing a CD40 antagonist leads to inhibition of CRS (e.g., inhibit or reduce at least one symptom, indication, or biomarker of CRS disclosed herein). In certain embodiments, CRS is inhibited by at least about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70% or about 80% as compared to a subject administered with a CD3 multispecific antigen binding molecule as monotherapy. 
     In certain embodiments, the administration of a CD40 antagonist or a CAR-T cell expressing a CD40 antagonist reduces cytokine release. In certain embodiments, levels of cytokines (e.g., TNFα, IL4, IL6, IL10, IL2, IFN-γ, IL-17A, IL13, or CD40L) is inhibited by at least about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70% or about 80% as compared to a subject administered with a CD3 multispecific antigen binding molecule as monotherapy. 
     In certain embodiments, the administration of a CD40 antagonist or a CAR-T cell expressing a CD40 antagonist in combination with a CD3 multispecific antigen binding molecule does not significantly reduce anti-tumor effects (e.g., inhibit or delay tumor growth, induce tumor regression, prevents tumor recurrence, and/or increases duration of survival, etc.) as compared to a subject administered with a CD3 multispecific antigen binding molecule as monotherapy. For example, the administration of a CD40 antagonist or a CAR-T cell expressing a CD40 antagonist in combination with a CD3 multispecific antigen binding molecule may reduce anti-tumor effects by less than about 40%, less than about 30%, less than about 20%, less than about 15%, less than about 10%, less than about 5%, less than about 1%, less than about 0.5%, or less than about 0.1%. as compared to a subject administered with a CD3 multispecific antigen binding molecule as monotherapy. In certain embodiments, the administration of a CD40 antagonist or a CAR-T cell expressing a CD40 antagonist does not affect anti-tumor efficacy of the CD3 multispecific antigen binding molecule. 
     In certain embodiments, the administration of a CD40 antagonist or a CAR-T cell expressing a CD40 antagonist in combination with a CD3 multispecific antigen binding molecule does not significantly reduce T cell (e.g., CD8+ T cell) activation, expansion, and/or cytotoxicity as compared to a subject administered with a CD3 multispecific antigen binding molecule as monotherapy. For example, the administration of a CD40 antagonist or a CAR-T cell expressing a CD40 antagonist in combination with a CD3 multispecific antigen binding molecule may reduce T cell (e.g., CD8+ T cell) activation, expansion, and/or cytotoxicity by less than about 40%, about 30%, about 20%, about 15%, about 10%, about 5%, about 1%, about 0.5%, or about 0.1%., as compared to a subject administered with a CD3 multispecific antigen binding molecule as monotherapy. In certain embodiments, the administration of a CD40 antagonist or a CAR-T cell expressing a CD40 antagonist does not affect T cell (e.g., CD8+ T cell) activation, expansion, and/or cytotoxicity induced by the CD3 multispecific antigen binding molecule. 
     In certain embodiments, the disclosed CD40 antagonist, CAR-T cell expressing CD40 antagonist, and/or CD3 multispecific antigen binding molecule are administered to a patient in conjunction with (e.g., before, simultaneously or following) any number of relevant treatment modalities, including but not limited to additional cancer or CRS treatments. 
     Exemplary CRS treatments include, e.g., IL-6 inhibitor or IL-6 receptor (IL-6R) inhibitors (e.g., tocilizumab or siltuximab), anti-TN-γ therapy, anti-sIL2Ra therapy, fever reducing medication such as acetaminophen, sgp130 blockers, vasoactive medications, corticosteroids, immunosuppressive agents, and mechanical ventilation. Exemplary vasoactive medications include but are not limited to angiotensin-11, endothelin-1, alpha adrenergic agonists, rostanoids, phosphodiesterase inhibitors, endothelin antagonists, inotropes (e.g., adrenaline, dobutamine, isoprenaline, ephedrine), vasopressors (e.g., noradrenaline, vasopressin, metaraminol, vasopressin, methylene blue), inodilators (e.g., milrinone, levosimendan), and dopamine. Exemplary vasopressors include but are not limited to norepinephrine, dopamine, phenylephrine, epinephrine, and vasopressin. Exemplary corticosteroids include but are not limited to dexamethasone, hydrocortisone, and methylprednisolone. Exemplary immunosuppressive agents include but are not limited to an inhibitor of TNFα or an inhibitor of IL-1. Assitonal exemplary therapies for CRS are disclosed in International Application WO2014011984, which is hereby incorporated by reference. 
     The additional therapeutically active component(s) may be administered just prior to, concurrent with, or shortly after the administration of an antigen-binding molecule of the present invention; (for purposes of the present disclosure, such administration regimens are considered the administration of an antigen-binding molecule “in combination with” an additional therapeutically active component). 
     Combined administration, as described above, may be simultaneous, separate, or sequential. For simultaneous administration, the agents may be administered as one composition or as separate compositions, as appropriate. 
     Administration Regimens 
     In certain embodiments, provided herein are methods comprising administering to a subject a CD40 antagonist (e.g., a CD40 antagonist antibody) or a CAR-T cell expressing a CD40 antagonist at a dosing frequency of about four times a week, twice a week, once a week, once every two weeks, once every three weeks, once every four weeks, once every five weeks, once every six weeks, once every eight weeks, once every twelve weeks, or less frequently so long as a therapeutic response is achieved. 
     In certain embodiments, provided herein are methods comprising administering to a subject a CD3 multispecific antigen binding molecule at a dosing frequency of about four times a week, twice a week, once a week, once every two weeks, once every three weeks, once every four weeks, once every five weeks, once every six weeks, once every eight weeks, once every twelve weeks, or less frequently so long as a therapeutic response is achieved. 
     In certain embodiments, the methods involve the administration of a CD40 antagonist (e.g., a CD40 antagonist antibody) or a CAR-T cell expressing a CD40 antagonist in combination with a CD3 multispecific antigen binding molecule at a dosing frequency of about four times a week, twice a week, once a week, once every two weeks, once every three weeks, once every four weeks, once every five weeks, once every six weeks, once every eight weeks, once every twelve weeks, or less frequently so long as a therapeutic response is achieved. 
     According to certain embodiments, multiple doses of a CD40 antagonist (e.g., a CD40 antagonist antibody) or a CAR-T cell expressing a CD40 antagonist in combination with a CD3 multispecific antigen binding molecule may be administered to a subject over a defined time course. The methods according to this aspect of the invention may comprise sequentially administering to a subject multiple doses of a CD40 antagonist (e.g., a CD40 antagonist antibody) or a CAR-T cell expressing a CD40 antagonist in combination with a CD3 multispecific antigen binding molecule. As used herein, “sequentially administering” means that each dose of an antigen-binding molecule is administered to the subject at a different point in time, e.g., on different days separated by a predetermined interval (e.g., hours, days, weeks or months). The present invention includes methods which comprise sequentially administering to the patient a single initial dose of a CD40 antagonist (e.g., a CD40 antagonist antibody) or a CAR-T cell expressing a CD40 antagonist, followed by one or more secondary doses of the CD40 antagonist (e.g., a CD40 antagonist antibody) or the CAR-T cell expressing a CD40 antagonist, and optionally followed by one or more tertiary doses of the CD40 antagonist (e.g., a CD40 antagonist antibody) or the CAR-T cell expressing a CD40 antagonist. In certain embodiments, the present invention futher comprises sequentially administering to the patient a single initial dose of with a CD3 multispecific antigen binding molecule, followed by one or more secondary doses of the CD3 multispecific antigen binding molecule, and optionally followed by one or more tertiary doses of the CD3 multispecific antigen binding molecule. 
     The terms “initial dose,” “secondary doses,” and “tertiary doses,” refer to the temporal sequence of administration of the antigen-binding molecule of the invention. Thus, the “initial dose” is the dose which is administered at the beginning of the treatment regimen (also referred to as the “baseline dose”); the “secondary doses” are the doses which are administered after the initial dose; and the “tertiary doses” are the doses which are administered after the secondary doses. The initial, secondary, and tertiary doses may all contain the same amount of the therapeutic agents described herein, but generally may differ from one another in terms of frequency of administration. In certain embodiments, however, the amount of an antigen-binding molecule contained in the initial, secondary and/or tertiary doses varies from one another (e.g., adjusted up or down as appropriate) during the course of treatment. In certain embodiments, two or more (e.g., 2, 3, 4, or 5) doses are administered at the beginning of the treatment regimen as “loading doses” followed by subsequent doses that are administered on a less frequent basis (e.g., “maintenance doses”). 
     In one exemplary embodiment of the present invention, each secondary and/or tertiary dose is administered 1 to 26 (e.g., 1, 1½, 2, 2½, 3, 3½, 4, 4½, 5, 5½, 6, 6½, 7, 7½, 8, 8½, 9, 9½, 10, 10½, 11, 11½, 12, 12½, 13, 13½, 14, 14½, 15, 15½, 16, 16½, 17, 17½, 18, 18½, 19, 19½, 20, 20½, 21, 21½, 22, 22½, 23, 23½, 24, 24½, 25, 25½, 26, 26½, or more) weeks after the immediately preceding dose. The phrase “the immediately preceding dose,” as used herein, means, in a sequence of multiple administrations, the dose of the theraputic agents described herein which is administered to a patient prior to the administration of the very next dose in the sequence with no intervening doses. 
     The methods according to this aspect of the invention may comprise administering to a patient any number of secondary and/or tertiary doses of the theraputic agents described herein. For example, in certain embodiments, only a single secondary dose is administered to the patient. In other embodiments, two or more (e.g., 2, 3, 4, 5, 6, 7, 8, or more) secondary doses are administered to the patient. Likewise, in certain embodiments, only a single tertiary dose is administered to the patient. In other embodiments, two or more (e.g., 2, 3, 4, 5, 6, 7, 8, or more) tertiary doses are administered to the patient. 
     In embodiments involving multiple secondary doses, each secondary dose may be administered at the same frequency as the other secondary doses. For example, each secondary dose may be administered to the patient 1 to 2 weeks after the immediately preceding dose. Similarly, in embodiments involving multiple tertiary doses, each tertiary dose may be administered at the same frequency as the other tertiary doses. For example, each tertiary dose may be administered to the patient 2 to 4 weeks after the immediately preceding dose. Alternatively, the frequency at which the secondary and/or tertiary doses are administered to a patient can vary over the course of the treatment regimen. The frequency of administration may also be adjusted during the course of treatment by a physician depending on the needs of the individual patient following clinical examination. 
     EXEMPLIFICATION 
     Example 1: CD40 Blockade Inhibited Cytokine Release Mediated by CD123×CD3 without Affecting T Cell Activation in 4 Day Assay with PBMC Enriched with Autologous B Cells 
     Experimental Set-Up: 
     The effect of CD40 blockade on cytokine release was assessed in the assay with human PBMC enriched with autologous B cells and AML cell line MOLM13. B cells were isolated from human PBMC using EasySep human B cell isolation kit (StemCells cat #17954), labeled with CFSE, and plated in complete media (RPMI supplemented with 10% FBSm 100 U/mL penicillin, 100 μg/ml streptomycin, 292 μg/ml L-glutamine) with autologous PBMC and MOLM13 cells at the ratio (5:10:1). CD123×CD3(G) or one-arm CD3 control were added to the well in 10-fold titrations starting at 1 μg/ml. Anti-CD40 antibody (IgG1 mutant, REGN3794) was used at constant concentration of 5 μg/ml. Cells were incubated 4 days at 37° C. in complete media. Cytokines and T cell activations were assessed 4 days after the set-up. Cytokines were measured in the supernatants using LegendPlex human B cell panel (Biolegend Catalog #740527). For T cell activation assessment cells were stained with directly conjugated antibodies to CD2, CD25 and live/dead cell stain. T cell activation is reported as the percentage of live CD2+ cells expressing CD25. 
     Results: 
     Blocking CD40 with anti-CD40 antibody inhibited cytokine release mediated by bispecific CD123×CD3 antibody in 4 day in vitro assay with CD123+ tumor cells, human PBMC and enriched B cells without significantly affecting T cell activation ( FIGS. 1A-1I ). 
     Example 2: CD40 Blockade Inhibited Cytokine Release Mediated by CD3 Bispecific without Significantly Affecting T Cell Activation in 4 Day Assay with AML Cell Line and PBMC without Additional Autologous B Cells 
     Experimental Set-Up: 
     The effect of CD40 blockade on cytokine release was assessed in the assay with human PBMC and AML cell line THP-1. Human PBMC were labeled with CFSE and THP-1 cells were labeled with Violet Cell trace. Labeled PBMC and THP-1 cells were plated in complete media at the ratio (10:1). CD123×CD3(G) or one-arm CD3 control were added to the well in 10-fold titrations starting at 1 μg/ml. Anti-CD40 antibody (IgG1 mutant, REGN3794) was used at constant concentration of 5 μg/ml. Cells were incubated 4 days at 37° C. in complete media. Cytokines and T cell activations were assessed 4 days after the set-up. Cytokines were measured in the supernatants using LegendPlex human B cell panel (Biolegend Catalog #740527). For T cell activation assessment cells were stained with directly conjugated antibodies to CD2, CD4, CD8, CD16, CD25 and live/dead cell stain. T cell activation is reported as the percentage of live CD2+CD16-CD8+ cells expressing CD25. 
     Results: 
     Blocking CD40 with anti-CD40 antibody inhibited cytokine release mediated by CD3 bispecific in 4 day in vitro assay with CD123+ tumor cells and human PBMC (no additional B cells) without significantly affecting T cell activation ( FIGS. 2A-2E ). In general, stronger cytokine release and more significant blockade of this release by anti-CD40 antibody were observed in assays including enriched B cells ( FIGS. 1A-1H ) as compared to those without ( FIGS. 2A-2E ). 
     Example 3: CD40 Blockade Inhibited Selected Cytokine Release Mediated by CD3 Bispecific without Significantly Affecting T Cell Activation and Target Killing in 4 Day Killing Assay with Prostate Cell Line and PBMC 
     Experimental Set-Up: 
     The effect of CD40 blockade on cytokine release was assessed in the killing assay with human PBMC and prostate cell line 22Rv1. Human PBMC were labeled with CFSE and 22Rv1 cells were labeled with Violet Cell trace. Labeled PBMC and 22Rv1 cells were plated in complete media at the ratio (20:1). Steap2×CD3(G) or one-arm CD3 control were added to the well in 10-fold titrations starting at 1 μg/ml. Anti-CD40 antibody (IgG1 mutant, REGN3794) was used at constant concentration of 5 μg/ml. Cells were incubated 4 days at 37° C. in complete media. At the end of the culture, cytokine release, surviving target cells, and T cell activation were analyzed by flow cytometry. Cytokines were measured in the supernatants using LegendPlex human B cell panel (Biolegend Catalog #740527). For T cell activation and target cell killing assessment the cells were washed and stained with directly conjugated antibodies to CD2, CD4, CD8, CD16, CD25 and live/dead cell stain. T cell activation is reported as the percentage of live CD2+CD16-CD8+ cells expressing CD25. For the assessment of 22Rv1 survival, cells were gated on live violet-labeled population. The percentage of live population normalized to the untreated sample is reported. 
     Results: 
     Blocking CD40 with anti-CD40 antibody inhibited cytokine release mediated by CD3 bispecific in 4 day in vitro killing assay with STEAP2+ tumor cells and human PBMC without significantly affecting T cell activation and cytotoxicity ( FIGS. 3A-3G ). The extent of anti-CD40 mediated inhibition varied across cytokines ( FIGS. 3C-3G ). 
     Example 4: CD40 Blockade Reduced Cytokines in PBMC Treated with CD20×CD3 Bispecific (REGN1979) 
     Experimental Set-Up: 
     The effect of CD40 blockade on cytokine release was assessed in the killing assay with human PBMC and NHL cell line Ramos. Ramos cells were labeled with CFSE and mixed with human PBMC in complete media at the ratio (1:10). CD20×CD3 (REGN1979) or one-arm CD3 control were added to the well in 10-fold titrations starting at 10 μg/ml. Anti-CD40 antibody (IgG1 mutant, REGN3794) was used at constant concentration of 5 μg/ml. Cells were incubated 4 days at 37° C. in complete media. At the end of the culture, cytokine release, surviving target cells, and T cell activation were analyzed by flow cytometry. Cytokines were measured in the supernatants using LegendPlex human B cell panel (Biolegend Catalog #740527). For T cell activation and target cell killing assessment the cells were washed and stained with directly conjugated antibodies to CD2, CD4, CD8, CD16, CD25 and live/dead cell stain. T cell activation is reported as the percentage of live CD2+CD16-CD8+ cells expressing CD25. For the assessment of Ramos survival, absolute number of live Ramos cells per well was calculated using CountBright beads. 
     Results: 
     Blocking CD40 with anti-CD40 antibody inhibited cytokine release mediated by CD20×CD3 bispecific in 4 day in vitro killing assay with CD20+ tumor cells and human PBMC without negatively affecting cytotoxicity ( FIGS. 4A-4B ). The combination of CD20×CD3 (REGN1979)+anti-CD40 antibody reduced T cell activation (˜35% below CD20×CD3 (REGN1979) alone) in 1 of 2 donors tested ( FIG. 4A ). 
     INCORPORATION BY REFERENCE 
     All publications, patents, patent applications and sequence accession numbers mentioned herein are hereby incorporated by reference in their entirety as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated by reference. In case of conflict, the present application, including any definitions herein, will control. 
     EQUIVALENTS 
     A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims. Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of skill in the art to which the disclosed invention belongs. 
     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.