Anti-CD3 antibodies and uses thereof

Abstract

Aspects of the application provide anti-CD3 antibodies and methods of using the same in treating cancer, infection, or autoimmune disorders.

Description

ANTI-CD3 ANTIBODIES AND USES THEREOF RELATED APPLICATIONS

[0001] This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application No. 63 / 664,099, filed on June 25, 2024, the entire contents of which are hereby incorporated by reference in their entirety. REFERENCE TO AN ELECTRONIC SEQUENCE LISTING

[0002] The content of the electronic sequence listing (A136170024WO00-SEQ-EMB.xml; Size: 132,054 bytes; Date of Creation: June 25, 2025) is herein incorporated by reference in its entirety. BACKGROUND

[0003] CD3 is a protein expressed by T cells and is part of the T cell receptor (TCR) complex. T cells are critical mediators of the immune response to infection and cancer, and also drive multiple autoimmune disorders. CD3 is a cell surface protein complex expressed by T lymphocytes and forms an essential part of the T cell receptor (TCR) complex. T cells are central to the adaptive immune system, mediating protective responses against infected or malignant cells. Bispecific T cell engagers (TCEs) are a promising class of engineered antibody-based therapeutics designed to redirect T cell cytotoxicity toward tumor cells. These molecules typically comprise two antigen-binding domains: one targeting CD3 (e.g., CD3ε) on T cells and the other targeting a tumor-associated antigen (TAA) on malignant cells. By simultaneously engaging both targets, TCEs promote formation of an immunological synapse, leading to T cell activation and tumor cell lysis in a manner that is independent of MHC presentation. CD3-targeted bispecific antibodies have demonstrated potent anti-tumor activity in both hematologic and solid tumors, underscoring their potential in cancer immunotherapy.

[0004] Despite the growing clinical relevance of TCEs, their development remains technically challenging. While many candidate TCEs display high selectivity and potency in preclinical experiments, they often suffer from problems in downstream development and clinical efficiency studies, including polyspecific, nonspecific and / or off-target binding; poor expression levels or profiles in eukaryotic host cells, such as mammalian host cells and yeast cells; poor chemical and physical properties, such as poor stability during storage (e.g., Docket No. A1361.70024WO00 14108730.1poor / low “shelf-life” stability), poor (low) solubility, poor (high) viscosity, propensity to aggregate; and poor clinical and biophysical profiles, such as poor pharmacokinetic profiles, poor pharmacodynamic profiles, fast or poor in vivo clearance rates , short circulation half- life, some of which result in termination of their development.

[0005] One frequently used CD3-binding scaffold is SP34, a murine monoclonal antibody that binds human CD3ε with high affinity, demonstrates robust T cell activation, and exhibits cross-reactivity with non-human primate CD3, thereby facilitating preclinical studies in relevant animal models. However, like those described above, TCEs and monoclonal antibodies derived from SP34 often display unfavorable biophysical characteristics and their translation into commercial therapeutics is often hampered by persistent developability challenges.

[0006] While recent efforts have focused on the de novo discovery of CD3-binding domains with improved biophysical properties, such approaches often require significant optimization and lack extensive clinical validation. By contrast, scaffolds like SP34 benefit from well-characterized pharmacology, high potency, and cross-reactivity with non-human primates. Accordingly, there remains a need for CD3-binding antibody domains that preserve the potent T cell activation and non-human primate cross-reactivity of established and validated binders, such as SP34, while exhibiting improved physicochemical and manufacturing properties SUMMARY

[0007] The present disclosure, at least in part, provides engineered humanized SP34 (hSP34) antibodies that specifically recognize and bind CD3 and display improved biophysical and developability properties (e.g., improved binding affinity, and / or reduced polyreactivity) as compared to existing humanized anti-CD3 antibodies or the murine parental antibody. For example, in one aspect, the disclosure features an isolated antibody or antigen-binding fragment thereof that binds to CD3 (e.g., human CD3). In some embodiments, an anti-CD3 antibody can be used to activate T cells, such as to induce their proliferation or differentiation. In some embodiments, an anti-CD3 antibody can be used to deplete T cells, such as to treat a T cell-mediated autoimmune condition or to ameliorate the symptoms of a T cell-mediated autoimmune condition. In other aspects, the present disclosure provides T-cell engaging bispecific antibodies targeting CD3, which comprise a first antigen binding site that specifically binds a cancer antigen or a pathogen-derived antigen, and a second antigen binding site that specifically binds CD3 (e.g., an antigen Docket No. A1361.70024WO00 14108730.1binding sites derived from any of the anti-CD3 antibodies described here). In some embodiments, a bispecific antibody described herein recruits a T cell (e.g., cytotoxic T cell) to a cancer cell or an infected cell. In some embodiments, a bispecific antibody described herein elicits T cell mediated immune response (e.g., cytotoxic T cell mediated immune response) against a cancer cell or an infected cell. In some embodiments, a bispecific antibody described herein induces T cell mediated killing (e.g., cytotoxic T cell mediated immune response) of a cancer cell or an infected cell. In some embodiments, a bispecific antibody described herein is useful for treating cancer or infection.

[0008] In some embodiments, the present disclosure provides means for engaging a T cell to a cancer cell or an infected cell. In some embodiments, the means for engaging a T cell to a cancer cell or an infected cell is a bispecific antibody described herein. In some embodiments, the present disclosure provides means for eliciting cytotoxic T cell immunity against cancer cells or infected cells. In some embodiments, the means for eliciting cytotoxic T cell immunity against cancer cells or infected cells is a bispecific antibody described herein.

[0009] In some embodiments, the present disclosure provides an antibody that specifically binds CD3, wherein the improvement comprises one or more of the HC CDR (e.g., HC CDR1, HC CDR2, or HC CDR3) amino acid sequences from any one of an anti-CD3 antibodies selected from Table 1. In some embodiments, the present disclosure provides an antibody that specifically binds CD3, wherein the improvement comprises the HC CDR1, HC CDR2, and HC CDR3 as provided for any one of the antibodies elected from Table 1. In some embodiments, the present disclosure provides an antibody that specifically binds CD3, wherein the improvement comprises one or more of the LC CDRs (e.g., LC CDR1, LC CDR2, or LC CDR3) amino acid sequences from any one of an anti-CD3 antibody selected from Table 1. In some embodiments, the present disclosure provides an antibody that specifically binds CD3, wherein the improvement comprises the LC CDR1, LC CDR2, and LC CDR3 s provided for any one of an anti-CD3 antibody selected from Table 1. In some embodiments, the present disclosure provides an antibody that specifically binds CD3, wherein the improvement comprises HC CDR1, HC CDR2, and HC CDR3, LC CDR1, LC CDR2, and LC CDR3 as provided for any one of an anti-CD3 antibody selected from Table 1.

[0010] In some embodiments, the present disclosure provides anti-CD3 antibodies having one or more amino acid change (e.g., substitution) in one or more of the framework regions Docket No. A1361.70024WO00 14108730.1as compared to the parental murine anti-CD3 antibody and / or a pre-existing humanized anti- CD3 antibody of the same parental murine antibody. In some embodiments, the present disclosure provides an antibody that specifically binds CD3, wherein the improvement comprises one or more of the framework sequences from any one of an anti-CD3 antibodies selected from Table 6.

[0011] In some embodiments, a bispecific antibody comprises a second antigen binding site that specifically binds to a cancer antigen or a pathogen-derived antigen, wherein the improvement comprises a first antigen binding site that specifically binds to CD3 that comprises any one of the anti-CD3 binding sites derived from an anti-CD3 antibody described herein (e.g., any one of the anti-CD3 binders described in Table 1).

[0012] In some aspects, the present disclosure provides an antibody that specifically binds CD3 comprising: a heavy chain complementarity determining region 1 (HC CDR1), a heavy chain complementarity determining region 2 (HC CDR2), and a heavy chain complementarity region 3 (HC CDR3) of a heavy chain variable region (VH) comprising the amino acid sequence of SEQ ID NO: 18; and a light chain complementarity determining region (LC CDR1), a light chain complementarity determining region 2 (LC CDR2), and a light chain complementarity determining region 3 (LC CDR3) of a light chain variable region (VL) comprising the amino acid sequence of SEQ ID NO: 19.

[0013] In some aspects, the present disclosure provides an antibody that specifically binds CD3 comprising: a heavy chain complementarity determining region (HC CDR1) comprising the amino acid sequence of SEQ ID NO: 1, a heavy chain complementarity determining region 2 (HC CDR2) comprising the amino acid sequence of SEQ ID NO: 17, a heavy chain complementarity determining region 3 (HC CDR3) comprising the amino acid sequence of SEQ ID NO: 13, a light chain complementarity determining region 1 (LC CDR1) comprising the amino acid sequence of SEQ ID NO: 4, a light chain complementarity determining region 2 (LC CDR2) comprising the amino acid sequence of SEQ ID NO: 5, and a light chain complementarity determining region 3 (LC CDR3) comprising the amino acid sequence of SEQ ID NO: 6.

[0014] Accordingly, in some aspects, the disclosure provides an antibody that specifically binds CD3 comprising a heavy chain complementarity determining region 1 (HC CDR1) comprising the amino acid sequence TYAMX1(SEQ ID NO: 20), wherein X1 is N or H; a heavy chain complementarity determining region 2 (HC CDR2) comprising the amino acid sequence RIRSKYNNYATX2YAX3SVKX4 (SEQ ID NO: 21), wherein X2 is Y, E, or A, X3 is Docket No. A1361.70024WO00 14108730.1D or A, and X4is G or D; a heavy chain complementarity determining region 3 (HC CDR3) comprising the amino acid sequence HGNFGNSYVSX5FAY (SEQ ID NO: 22), wherein X5 is W or Y; a light chain complementarity determining region 1 (LC CDR1) comprising the amino acid sequence X6SSTGAVTTSNYAN (SEQ ID NO: 23), wherein X6is R or S; a light chain complementarity determining region 2 (LC CDR2) comprising the amino acid sequence GTNKRAP (SEQ ID NO: 5); and a light chain complementarity determining region 3 (LC CDR3) comprising the amino acid sequence ALWYSNLWV (SEQ ID NO: 6).

[0015] In some aspects, the disclosure provides an antibody that specifically binds CD3 comprising a human immunoglobulin kappa variable 4-1 (IGKV4-1) comprising a light chain complementarity determining region 1 (LC CDR1) comprising the amino acid sequence X6SSTGAVTTSNYAN (SEQ ID NO: 23), wherein X6is R or S; a light chain complementarity determining region 2 (LC CDR2) comprising the amino acid sequence GTNKRAP (SEQ ID NO: 5); and a light chain complementarity determining region 3 (LC CDR3) comprising the amino acid sequence ALWYSNLWV (SEQ ID NO: 6).

[0016] In some aspects, the disclosure provides an antibody that specifically binds CD3 comprising (a) a heavy chain complementarity determining region 1 (HC CDR1), a heavy chain complementarity determining region 2 (HC CDR2), and a heavy chain complementarity determining region 3 (HC CDR3) of a heavy chain variable region (VH) comprising the amino acid sequence of SEQ ID NO: 7; and a light chain complementarity determining region 1 (LC CDR1), a light chain complementarity determining region 2 (LC CDR2), and a light chain complementarity determining region 3 (LC CDR3) of a light chain variable region (VL) comprising the amino acid sequence of SEQ ID ON: 10; (b) a HC CDR1, HC CDR2, and a HC CDR3 of a VH comprising the amino acid sequence of SEQ ID NO: 14; and a LC CDR1, a LC CDR2, and a LC CDR3 of a VL comprising the amino acid sequence of SEQ ID ON: 10; (c) a HC CDR1, HC CDR2, and a HC CDR3 of a VH comprising the amino acid sequence of SEQ ID NO: 16; and a LC CDR1, a LC CDR2, and a LC CDR3 of a VL comprising the amino acid sequence of SEQ ID ON: 10; (d) a HC CDR1, HC CDR2, and a HC CDR3 of a VH comprising the amino acid sequence of SEQ ID NO: 18; and a LC CDR1, a LC CDR2, and a LC CDR3 of a VL comprising the amino acid sequence of SEQ ID ON: 8; (e) a HC CDR1, HC CDR2, and a HC CDR3 of a VH comprising the amino acid sequence of SEQ ID NO: 18; and a LC CDR1, a LC CDR2, and a LC CDR3 of a VL comprising the amino acid sequence of SEQ ID ON: 10; (f) a HC CDR1, HC CDR2, and a HC CDR3 of a VH comprising the amino acid sequence of SEQ ID NO: 24; and a LC Docket No. A1361.70024WO00 14108730.1CDR1, a LC CDR2, and a LC CDR3 of a VL comprising the amino acid sequence of SEQ ID ON: 8; (g) a HC CDR1, HC CDR2, and a HC CDR3 of a VH comprising the amino acid sequence of SEQ ID NO: 24; and a LC CDR1, a LC CDR2, and a LC CDR3 of a VL comprising the amino acid sequence of SEQ ID ON: 10; (h) a HC CDR1, HC CDR2, and a HC CDR3 of a VH comprising the amino acid sequence of SEQ ID NO: 14; and a LC CDR1, a LC CDR2, and a LC CDR3 of a VL comprising the amino acid sequence of SEQ ID ON: 19; (i) a HC CDR1, HC CDR2, and a HC CDR3 of a VH comprising the amino acid sequence of SEQ ID NO: 16; and a LC CDR1, a LC CDR2, and a LC CDR3 of a VL comprising the amino acid sequence of SEQ ID ON: 19; or (j) a HC CDR1, HC CDR2, and a HC CDR3 of a VH comprising the amino acid sequence of SEQ ID NO: 18; and a LC CDR1, a LC CDR2, and a LC CDR3 of a VL comprising the amino acid sequence of SEQ ID ON: 19.

[0017] In some aspects, the disclosure provides an antibody that specifically binds CD3 comprising (a) a HC CDR1 comprising the amino acid sequence of SEQ ID NO: 1, a HC CDR2 comprising the amino acid sequence of SEQ ID NO: 2, a HC CDR3 comprising the amino acid sequence of SEQ ID NO: 3, a LC CDR1 comprising the amino acid sequence of SEQ ID NO: 9, a LC CDR2 comprising the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 comprising the amino acid sequence of SEQ ID NO: 6; (b) a HC CDR1 comprising the amino acid sequence of SEQ ID NO: 11, a HC CDR2 comprising the amino acid sequence of SEQ ID NO: 12, a HC CDR3 comprising the amino acid sequence of SEQ ID NO: 13, a LC CDR1 comprising the amino acid sequence of SEQ ID NO: 9, a LC CDR2 comprising the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 comprising the amino acid sequence of SEQ ID NO: 6; (c) a HC CDR1 comprising the amino acid sequence of SEQ ID NO: 1, a HC CDR2 comprising the amino acid sequence of SEQ ID NO: 15, a HC CDR3 comprising the amino acid sequence of SEQ ID NO: 13, a LC CDR1 comprising the amino acid sequence of SEQ ID NO: 9, a LC CDR2 comprising the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 comprising the amino acid sequence of SEQ ID NO: 6; (d) a HC CDR1 comprising the amino acid sequence of SEQ ID NO: 1, a HC CDR2 comprising the amino acid sequence of SEQ ID NO: 17, a HC CDR3 comprising the amino acid sequence of SEQ ID NO: 13, a LC CDR1 comprising the amino acid sequence of SEQ ID NO: 4, a LC CDR2 comprising the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 comprising the amino acid sequence of SEQ ID NO: 6; (e) a HC CDR1 comprising the amino acid sequence of SEQ ID NO: 1, a HC CDR2 comprising the amino acid sequence of SEQ ID Docket No. A1361.70024WO00 14108730.1NO: 17, a HC CDR3 comprising the amino acid sequence of SEQ ID NO: 13, a LC CDR1 comprising the amino acid sequence of SEQ ID NO: 9, a LC CDR2 comprising the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 comprising the amino acid sequence of SEQ ID NO: 6; (f) a HC CDR1 comprising the amino acid sequence of SEQ ID NO: 1, a HC CDR2 comprising the amino acid sequence of SEQ ID NO: 17, a HC CDR3 comprising the amino acid sequence of SEQ ID NO: 13, a LC CDR1 comprising the amino acid sequence of SEQ ID NO: 4, a LC CDR2 comprising the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 comprising the amino acid sequence of SEQ ID NO: 6; (g) a HC CDR1 comprising the amino acid sequence of SEQ ID NO: 1, a HC CDR2 comprising the amino acid sequence of SEQ ID NO: 17, a HC CDR3 comprising the amino acid sequence of SEQ ID NO: 13, a LC CDR1 comprising the amino acid sequence of SEQ ID NO: 9, a LC CDR2 comprising the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 comprising the amino acid sequence of SEQ ID NO: 6; (h) a HC CDR1 comprising the amino acid sequence of SEQ ID NO: 1, a HC CDR2 comprising the amino acid sequence of SEQ ID NO: 12, a HC CDR3 comprising the amino acid sequence of SEQ ID NO: 13, a LC CDR1 comprising the amino acid sequence of SEQ ID NO: 4, a LC CDR2 comprising the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 comprising the amino acid sequence of SEQ ID NO: 6; (i) a HC CDR1 comprising the amino acid sequence of SEQ ID NO: 1, a HC CDR2 comprising the amino acid sequence of SEQ ID NO: 15, a HC CDR3 comprising the amino acid sequence of SEQ ID NO: 13, a LC CDR1 comprising the amino acid sequence of SEQ ID NO: 4, a LC CDR2 comprising the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 comprising the amino acid sequence of SEQ ID NO: 6; or (j) a HC CDR1 comprising the amino acid sequence of SEQ ID NO: 1, a HC CDR2 comprising the amino acid sequence of SEQ ID NO: 17, a HC CDR3 comprising the amino acid sequence of SEQ ID NO: 13, a LC CDR1 comprising the amino acid sequence of SEQ ID NO: 4, a LC CDR2 comprising the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 comprising the amino acid sequence of SEQ ID NO: 6.

[0018] In some embodiments, the antibody is a humanized antibody.

[0019] In some embodiments, the antibody comprises (a) a VH comprising the amino acid of SEQ ID NO: 7, and / or a VL comprising the amino acid sequence of SEQ ID NO: 10; (b) a VH comprising the amino acid of SEQ ID NO: 14, and / or a VL comprising the amino acid sequence of SEQ ID NO: 10; (c) a VH comprising the amino acid of SEQ ID NO: 16, and / or a VL comprising the amino acid sequence of SEQ ID NO: 10; (d) a VH comprising the Docket No. A1361.70024WO00 14108730.1amino acid of SEQ ID NO: 18, and / or a VL comprising the amino acid sequence of SEQ ID NO: 8; (e) a VH comprising the amino acid of SEQ ID NO: 18, and / or a VL comprising the amino acid sequence of SEQ ID NO: 10; (f) a VH comprising the amino acid of SEQ ID NO: 24, and / or a VL comprising the amino acid sequence of SEQ ID NO: 8; (g) a VH comprising the amino acid of SEQ ID NO: 24, and / or a VL comprising the amino acid sequence of SEQ ID NO: 10; (h) a VH comprising the amino acid of SEQ ID NO: 14, and / or a VL comprising the amino acid sequence of SEQ ID NO: 19; (i) a VH comprising the amino acid of SEQ ID NO: 16, and / or a VL comprising the amino acid sequence of SEQ ID NO: 19; or (j) a VH comprising the amino acid of SEQ ID NO: 18, and / or a VL comprising the amino acid sequence of SEQ ID NO: 19.

[0020] In some embodiments, the antibody is a full-length IgG, a Fab fragment, a F(ab') fragment, a F(ab’)2 fragment, a scFv, or a Fv. In some embodiments, the antibody comprises a heavy chain constant region of the isotype IgG1, IgG2, IgG3, or IgG4.

[0021] In some embodiments, the antibody is a humanized antibody.

[0022] In some embodiments, the disclosure provides an isolated nucleic acid encoding the VH and / or VL of an antibody provided herein. In some embodiments, an antibody encoded by an isolated nucleic acid is a humanized antibody. In some embodiments, the nucleic acid comprises (a) the nucleic acid sequence of SEQ ID NO: 25, and / or the nucleic acid sequence of SEQ ID NO: 26; (b) the nucleic acid sequence of SEQ ID NO: 27, and / or the nucleic acid sequence of SEQ ID NO: 26; (c) the nucleic acid sequence of SEQ ID NO: 29, and / or the nucleic acid sequence of SEQ ID NO: 26; (d) the nucleic acid sequence of SEQ ID NO: 31, and / or the nucleic acid sequence of SEQ ID NO: 32; (e) the nucleic acid sequence of SEQ ID NO: 31, and / or the nucleic acid sequence of SEQ ID NO: 26; (f) the nucleic acid sequence of SEQ ID NO: 35, and / or the nucleic acid sequence of SEQ ID NO: 32; (g) the nucleic acid sequence of SEQ ID NO: 35, and / or the nucleic acid sequence of SEQ ID NO: 26; (h) the nucleic acid sequence of SEQ ID NO: 27, and / or the nucleic acid sequence of SEQ ID NO: 40; (i) the nucleic acid sequence of SEQ ID NO: 29, and / or the nucleic acid sequence of SEQ ID NO: 40; or (j) the nucleic acid sequence of SEQ ID NO: 31, and / or the nucleic acid sequence of SEQ ID NO: 40.

[0023] In some embodiments, the disclosure provides an expression vector comprising an isolated nucleic acid provided herein. In some embodiments, the disclosure provides a host cell comprising an antibody, an isolated nucleic acid, or a vector provided herein. In some embodiments, the antibody is a humanized antibody. Docket No. A1361.70024WO00 14108730.1

[0024] In some embodiments, the disclosure provides a composition comprising an antibody, an isolated nucleic acid, a vector, a host cell, or an engineered cell provided herein. In some embodiments, the composition further comprises a pharmaceutically acceptable carrier.

[0025] In some embodiments, the disclosure provides a bispecific antibody comprising a first antigen binding site and a second antigen binding site, wherein the second antigen binding site comprises an antibody provided herein. In some embodiments, the first antigen site specifically binds to a cancer antigen, a pathogen-derived antigen, or a B cell antigen.

[0026] In some embodiments, the first antigen site specifically binds to a cancer antigen. In some embodiments, the cancer antigen is selected from WT1, PRAME, DLL3, CD70, Claudin18.2, MSLN, MAGE-A1, MAGE-A3, MAGE-A4, MAGE-A8, CD38, and BCMA. In some embodiments, the cancer antigen is WT1. In some embodiments, the cancer antigen is PRAME. In some embodiments, the cancer antigen is DLL3. In some embodiments, the cancer antigen is CD70. In some embodiments, the cancer antigen is Claudin18.2. In some embodiments, the cancer antigen is MSLN. In some embodiments, the cancer antigen is MAGE-A1. In some embodiments, the cancer antigen is MAGE-A3. In some embodiments, the cancer antigen is MAGE-A4. In some embodiments, the cancer antigen is MAGE-A8. In some embodiments, the cancer antigen is CD38. In some embodiments, the cancer antigen is BCMA.

[0027] In some embodiments, the first antigen binding site specifically binds a pathogen- derived antigen. In some embodiments, the pathogen-derived antigen is a viral antigen. In some embodiments, the viral antigen is an HIV antigen, an influenza antigen, an HPV antigen, or a Zika virus antigen. In some embodiments, the pathogen-derived antigen is a bacterial antigen. In some embodiments, the bacterial antigen is a Staphylococcus species antigen or a Pseudomonas species antigen. In some embodiments, the pathogen-derived antigen is a parasitic antigen. In some embodiments, the parasitic antigen is a Plasmodium species antigen, a Trypanosoma species antigen, or a Schistosoma species antigen.

[0028] In some embodiments, the first antigen binding site specifically binds a B cell antigen. In some embodiments, the B cell antigen is CD19, CD22, or CD79.

[0029] In some embodiments, the bispecific antibody comprises a first arm that is configured as a Fab, a Fab’, or a scFv and that comprises the first antigen binding site. In some embodiments, the bispecific antibody comprises a second arm that is configured as a Fab, a Fab’, or a scFv and that comprises the first antigen binding site. In some embodiments, Docket No. A1361.70024WO00 14108730.1the bispecific antibody comprises a first arm that is configured as a Fab and a second arm that is configured as a scFv. In some embodiments, the bispecific antibody comprises a first arm that is configured as a scFv and a second arm that is configured as a Fab. In some embodiments, the ratio between the first antigen binding site and the second antigen binding site is 1:1, 1:2, 1:3, 2:1 or 3:1.

[0030] In some embodiments, the disclosure provides a host cell comprising a bispecific antibody provided herein. In some embodiments, the disclosure provides a composition comprising a bispecific antibody provided herein. In some embodiments, the composition further comprises a pharmaceutically acceptable carrier.

[0031] In some embodiments, the disclosure provides a method of treating cancer, the method comprising administering to a subject in need thereof an effective amount of an antibody, an engineered cell, a composition, or a bispecific antibody provided herein.

[0032] In some embodiments, the disclosure provides a method of treating infection, the method comprising administering to a subject in need thereof an effective amount of an antibody, an engineered cell, a composition, or a bispecific antibody provided herein.

[0033] In some embodiments, the disclosure provides a method of treating an autoimmune disorder, the method comprising administering to a subject in need thereof an effective amount of an antibody, an engineered cell, a composition, or a bispecific antibody provided herein.

[0034] The foregoing and other aspects, implementations, acts, functionalities, features and embodiments of the present teachings can be more fully understood from the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate certain embodiments, and together with the written description, serve to provide non-limiting examples of certain aspects of the compositions and methods disclosed herein.

[0036] FIG. 1A: Mean fluorescence intensity (MFI) of Jurkat cells (CD3⁺) incubated with humanized anti-CD3 / BCMA bispecific antibodies (“Anti-CD3 / BCMA bsAb1”), comparator humanized SP34 / BCMA bsAb, and control (“Isotype control / BCMA bsAb”).

[0037] FIG. 1B: % Cytotoxicity of BCMA+ MM1S target cells after 27 hour incubation with primary human CD8+ T cells and anti-CD3 / BCMA bispecific test articles. % Docket No. A1361.70024WO00 14108730.1Cytotoxicity of BCMA+ MM1S target cells after 27 hour incubation with primary human CD8+ T cells and anti-CD3 / BCMA bispecific test articles.

[0038] FIG. 1C: % Cytotoxicity of BCMA+ MM1S target cells after 27 hour incubation with primary human CD8+ T cells and anti-CD3 / BCMA bispecific test articles.

[0039] FIG. 2A: Incucyte kinetic traces showing % green area over time infrom GFP expressing MM1.S (BCMA⁺) target cells following incubation with CD8+ primary T cells and Anti-CD3 Ab10 / BCMA bispecific antibody at reported concentrations.

[0040] FIG. 2B: Incucyte kinetic traces showing % green area over time from GFP expressing THP1 (BCMAlow) target cells following incubation with CD8+ primary T cells and Anti-CD3 Ab10 / BCMA bispecific antibody at reported concentrations.

[0041] FIG. 3A: Incucyte kinetic traces showing % green area over time from GFP expressing MM1.S (BCMA⁺) target cells following incubation with CD8+ primary T cells and Comparator hSP34 Anti-CD3 / BCMA bispecific antibody at reported concentrations.

[0042] FIG. 3B: Incucyte kinetic traces showing % green area over time from GFP expressing THP1 (BCMAlow) target cells following incubation with CD8+ primary T cells and Comparator hSP34 Anti-CD3 / BCMA bispecific antibody at reported concentrations.

[0043] FIG. 4A: IFN-γ concentration measured by ELISA from co-culture supernatants.

[0044] FIG. 4B: IL-2 concentration measured by ELISA from co-culture supernatants.

[0045] FIG. 4C: TNF-α concentration measured by ELISA from co-culture supernatants.

[0046] FIG. 5A: IFN-γ concentration measured by ELISA from co-culture supernatants.

[0047] FIG. 5B: IL-2 concentration measured by ELISA from co-culture supernatants.

[0048] FIG. 5C: TNF-α concentration measured by ELISA from co-culture supernatants.

[0049] FIG. 6A: Incucyte kinetic traces showing % green area over time from GFP expressing HEK293T (BCMAnegative) target cells following incubation with CD8+ primary T cells and Comparator hSP34 Anti-CD3 / BCMA bispecific antibody at reported concentrations.

[0050] FIG. 6B: Incucyte kinetic traces showing % green area over time from GFP expressing HEK293T (BCMAnegative) target cells following incubation with CD8+ primary T cells and Anti-CD3 Ab10 / BCMA bispecific antibody at reported concentrations.

[0051] FIG. 7A–C: Cytokine Release from CD8+ primary human T cells after 27 hour incubation with BCMAnegativeHEK293T in the presence of increasing concentrations of Anti- CD3 Ab10 / BCMA bispecific antibody

[0052] FIG. 7A: IFN-γ concentration measured by ELISA from co-culture supernatants. Docket No. A1361.70024WO00 14108730.1

[0053] FIG. 7B: IL-2 concentration measured by ELISA from co-culture supernatants.

[0054] FIG. 7C: TNF-α concentration measured by ELISA from co-culture supernatants.

[0055] FIG. 8A–C: Cytokine Release from CD8+ primary human T cells after 27 hour incubation with BCMAnegativeHEK293T in the presence of increasing concentrations of Comparator hSP34 Anti-CD3 / BCMA bispecific antibody

[0056] FIG. 8A: IFN-γ concentration measured by ELISA from co-culture supernatants.

[0057] FIG. 8B: IL-2 concentration measured by ELISA from co-culture supernatants.

[0058] FIG. 8C: TNF-α concentration measured by ELISA from co-culture supernatants. DETAILED DESCRIPTION

[0059] The present disclosure, at least in part, relates to the development of humanized antibodies that specifically recognize and bind CD3 that has improved properties (e.g., improved binding affinity, and / or reduced polyreactivity as compared to existing humanized anti-CD3 antibodies). In some embodiments, methods and related compositions are provided that are useful for targeting cells (e.g., T cells) that express CD3. Aspects of the disclosure provide anti-CD3 antibodies with high binding affinity and specificity to CD3.

[0060] CD3 (cluster of differentiation 3) is a multimeric complex expressed by T cells (also called T lymphocytes). CD3 is composed of multiple subunits, including CD3γ, CD3δ, CD3ε, and CD3ζ, and is a part of the T cell receptor (TCR) complex. Binding of CD3 via anti-CD3 antibodies can activate T cells, resulting in their proliferation, or deplete T cells by inducing apoptosis. In the case of bispecific antibodies comprising one binding site that targets CD3, binding of CD3 can redirect T cells to localize them to a cell expressing the antigen targeted by the other binding site of the bispecific antibody.

[0061] Also provided is the use of an anti-CD3 antibody and its variants in research, diagnostic / detection, and therapeutic applications. In some embodiments, an anti-CD3 antibody is a bispecific antibody and comprises a first binding site that specifically binds a cancer antigen or a pathogen-derived antigen and a second binding site that specifically binds CD3. In some embodiments, the first binding site specifically binds a cancer antigen. In some embodiments, the first binding site specifically binds a pathogen-derived antigen. By having a binding site specific for CD3 and a binding site specific for a cancer antigen or a pathogen- derived antigen, the bispecific antibody can act as a scaffold, bringing a T cell to a cancer cell or an infected cell to induce an immune response against the cancer cell or infected cell. Docket No. A1361.70024WO00 14108730.1

[0062] The foregoing and other aspects, implementations, acts, functionalities, features and embodiments of the present teachings can be more fully understood from the following description in conjunction with the accompanying drawings. I. Definitions

[0063] AC-SINS: Affinity-Capture Self-Interaction Nanoparticle Spectroscopy (AC-SINS) is a biophysical assay used to evaluate antibody self-interaction. The assay measures changes in plasmon resonance (∆λmax), which correlates with the degree of self-association. Lower ∆λmax values indicate lower self-interaction and improved developability.

[0064] Administering: As used herein, the terms “administering” or “administration” means to provide an antibody or a composition thereof to a subject in a manner that is physiologically and / or pharmacologically useful (e.g., to treat a condition in the subject).

[0065] Affinity Matured Antibody: “Affinity Matured Antibody” is used herein to refer to an antibody with one or more alterations in one or more CDRs, which result in an improvement in the affinity (e.g., KD, kd or ka) of the antibody for a target antigen compared to a parent antibody, which does not possess the alteration(s). Exemplary affinity matured antibodies will have nanomolar or even picomolar affinities for the target antigen. A variety of procedures for producing affinity matured antibodies are known in the art, including the screening of a combinatory antibody library that has been prepared using bio-display. For example, Marks et al., BioTechnology, 10: 779-783 (1992) describes affinity maturation by VH and VL domain shuffling. Random mutagenesis of CDR and / or framework residues is described by Barbas et al., Proc. Nat. Acad. Sci. USA, 91: 3809-3813 (1994); Schier et al., Gene, 169: 147-155 (1995); Yelton et al., J. Immunol., 155: 1994-2004 (1995); Jackson et al., J. Immunol., 154(7): 3310-3319 (1995); and Hawkins et al, J. Mol. Biol., 226: 889-896 (1992). Selective mutation at selective mutagenesis positions and at contact or hypermutation positions with an activity-enhancing amino acid residue is described in U.S. Pat. No. 6,914,128 B1.

[0066] Antibody: As used herein, the term “antibody” refers to a polypeptide that includes at least one immunoglobulin variable domain or at least one site, e.g., paratope, that specifically binds to an antigen. In some embodiments, an antibody comprises a paratope. In some embodiments, a paratope comprises one or more complementarity determining regions (CDRs). In some embodiments, an antibody is a full-length antibody. In some embodiments, an antibody is a chimeric antibody. In some embodiments, an antibody is a humanized Docket No. A1361.70024WO00 14108730.1antibody. However, in some embodiments, an antibody is a Fab fragment, a F(ab’)2 fragment, a Fv fragment or a scFv fragment. In some embodiments, an antibody is a nanobody derived from a camelid antibody or a nanobody derived from shark antibody. In some embodiments, an antibody is a diabody. In some embodiments, an antibody comprises a framework having a human germline sequence. In another embodiment, an antibody comprises a heavy chain constant domain selected from the group consisting of IgG, IgG1, IgG2, IgG2A, IgG2B, IgG2C, IgG3, IgG4, IgA1, IgA2, IgD, IgM, and IgE constant domains. In some embodiments, an antibody comprises a heavy (H) chain variable region (abbreviated herein as VH), and / or a light (L) chain variable region (abbreviated herein as VL). In some embodiments, an antibody comprises a constant domain, e.g., an Fc region. An immunoglobulin constant domain refers to a heavy or light chain constant domain. Human IgG heavy chain and light chain constant domain amino acid sequences and their functional variations are known. With respect to the heavy chain, in some embodiments, the heavy chain of an antibody described herein can be an alpha (α), delta (δ), epsilon (ε), gamma (γ) or mu (µ) heavy chain. In some embodiments, the heavy chain of an antibody described herein can comprise a human alpha (α), delta (δ), epsilon (ε), gamma (γ) or mu (µ) heavy chain. In a particular embodiment, an antibody described herein comprises a human gamma 1 CH1, CH2, and / or CH3 domain. In some embodiments, the amino acid sequence of the VH domain comprises the amino acid sequence of a human gamma (γ) heavy chain constant region, such as any known in the art. Non-limiting examples of human constant region sequences have been described in the art, e.g., see U.S. Pat. No. 5,693,780 and Kabat E A et al., (1991) supra. In some embodiments, the VH domain comprises an amino acid sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 98%, or at least 99% identical to any of the variable chain constant regions provided herein. In some embodiments, an antibody is modified, e.g., modified via glycosylation, phosphorylation, sumoylation, and / or methylation. In some embodiments, an antibody is a glycosylated antibody, which is conjugated to one or more sugar or carbohydrate molecules. In some embodiments, the one or more sugar or carbohydrate molecule are conjugated to the antibody via N-glycosylation, O-glycosylation, C-glycosylation, glypiation (GPI anchor attachment), and / or phosphoglycosylation. In some embodiments, the one or more sugar or carbohydrate molecule are monosaccharides, disaccharides, oligosaccharides, or glycans. In some embodiments, the one or more sugar or carbohydrate molecule is a branched oligosaccharide or a branched glycan. In some embodiments, the one or more sugar or carbohydrate molecule includes a mannose unit, a Docket No. A1361.70024WO00 14108730.1glucose unit, an N-acetylglucosamine unit, or a phospholipid unit. In some embodiments, an antibody is a construct that comprises a polypeptide comprising one or more antigen binding fragments of the disclosure linked to a linker polypeptide or an immunoglobulin constant domain. Linker polypeptides comprise two or more amino acid residues joined by peptide bonds and are used to link one or more antigen binding portions. Examples of linker polypeptides have been reported (see e.g., Holliger, P., et al. (1993) Proc. Natl. Acad. Sci. USA 90:6444-6448; Poljak, R. J., et al. (1994) Structure 2:1121-1123). Still further, an antibody may be part of a larger immunoadhesion molecule, formed by covalent or noncovalent association of the antibody or antibody portion with one or more other proteins or peptides. Examples of such immunoadhesion molecules include use of the streptavidin core region to make a tetrameric scFv molecule (Kipriyanov, S. M., et al. (1995) Human Antibodies and Hybridomas 6:93-101) and use of a cysteine residue, a marker peptide and a C-terminal polyhistidine tag to make bivalent and biotinylated scFv molecules (Kipriyanov, S. M., et al. (1994) Mol. Immunol. 31:1047-1058).

[0067] Approximately: As used herein, the term “approximately” or “about,” as applied to one or more values of interest, refers to a value that is similar to a stated reference value. In certain embodiments, the term “approximately” or “about” refers to a range of values that fall within 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, or less in either direction (greater than or less than) of the stated reference value unless otherwise stated or otherwise evident from the context (except where such number would exceed 100% of a possible value).

[0068] Bispecific Antibody: As used herein, the term “bispecific antibody” refers to a polypeptide or a complex (e.g., two covalently linked polypeptides) that includes two different antigen binding, e.g., paratopes, that have different antigen binding specificities. For example, in one embodiment, a bispecific antibody is a polypeptide that includes two different antigen binding sites in which each antigen binding site binds to a different epitope of the same antigen. In other embodiments, a bispecific antibody is a polypeptide that includes two different antigen binding sites in which each site binds to a different antigen. In some embodiments, a bispecific antibody comprises two different sets of immunoglobulin variable domains, each of which set binds to a different epitope or group of epitopes.

[0069] Typically, each of the two antigen binding sites is present within an “arm” of a bispecific antibody. In some embodiments, an arm of a bispecific antibody is configured as a monospecific antibody, e.g., a full-length IgG or a fragment thereof. In some embodiments, a Docket No. A1361.70024WO00 14108730.1bispecific antibody comprises two arms, one or each of which is configured as an Fv region that confers specificity to distinct antigen residues. In some embodiments, a bispecific antibody comprises two arms of the same configuration, e.g., a Fab, a Fab’, a svFc, or any other suitable format. In some embodiments, a bispecific antibody comprises two arms of two different configurations, e.g., a Fab on one arm and a scFv on the other arm. In some embodiments, a bispecific antibody does not comprise an Fc region. In some embodiments, the two arms of a bispecific antibody are linked directly. In some embodiments, the two arms of a bispecific antibody are linked by a linker. In some embodiments, a bispecific antibody comprises an Fc region, e.g., a dimeric Fc or a monomeric Fc. In some embodiments, a bispecific antibody comprises a monomeric Fc. In some embodiments, a bispecific antibody comprises one arm linked to one end (e.g., the N terminal) of a monomeric Fc and a second arm linked to the other end (e.g., the C terminal) of the monomeric Fc (see, e.g., Shan et al., “In vivo pharmacokinetic enhancement of monomeric Fc and monovalent bispecific designs through structural guidance”, Communications Biology, Vol. 4, Article No. 1048 (2021)). In some embodiments, a bispecific antibody comprises a dimeric Fc region. In some embodiments, a bispecific antibody comprises two arms that are oriented symmetrically around an Fc region (e.g., each Fc monomer of a dimeric Fc region is linked to one arm). In some embodiments, a bispecific antibody comprises two distinct heavy chains and two distinct light chains, with each heavy chain / light chain pair having different antigen binding specificity. In some embodiments, a bispecific antibody comprises two arms that are oriented asymmetrically around an Fc (e.g., the two arms of the bispecific antibody are linked to one of the monomers of a dimeric Fc region). In some embodiments, because bispecific antibodies are capable of binding two different targets, they can be used as scaffolds to recruit or redirect cells to antigenic targets, e.g., to recruit immune cells to cancer cells. In some embodiments, a bispecific antibody contains a first antigen binding and a second antigen binding site that specifically binds CD3 or a portion thereof, e.g., CD3ε, a CD3ε / δ heterodimer, or a CD3ε / γ heterodimer.

[0070] CDR: As used herein, the term “CDR” refers to the complementarity determining region within antibody variable sequences. A typical antibody molecule comprises a heavy chain variable region (VH) and a light chain variable region (VL), which are usually involved in antigen binding. The VH and VL regions can be further subdivided into regions of hypervariability, also known as “complementarity determining regions” (“CDR”), interspersed with regions that are more conserved, which are known as “framework regions” Docket No. A1361.70024WO00 14108730.1(“FR”). Each VH and VL is typically 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 extent of the framework region and CDRs can be precisely identified using methodology known in the art, for example, by the Kabat definition, the IMGT definition, the Chothia definition, the AbM definition, and / or the contact definition, all of which are well known in the art. See, e.g., Kabat, E.A., et al. (1991) Sequences of Proteins of Immunological Interest, Fifth Edition, U.S. Department of Health and Human Services, NIH Publication No. 91-3242; IMGT®, the international ImMunoGeneTics information system® http: / / www.imgt.org, Lefranc, M.-P. et al., Nucleic Acids Res., 27:209-212 (1999); Ruiz, M. et al., Nucleic Acids Res., 28:219-221 (2000); Lefranc, M.-P., Nucleic Acids Res., 29:207- 209 (2001); Lefranc, M.-P., Nucleic Acids Res., 31:307-310 (2003); Lefranc, M.-P. et al., In Silico Biol., 5, 0006 (2004) [[Epub]], 5:45-60 (2005); Lefranc, M.-P. et al., Nucleic Acids Res., 33:D593-597 (2005); Lefranc, M.-P. et al., Nucleic Acids Res., 37:D1006-1012 (2009); Lefranc, M.-P. et al., Nucleic Acids Res., 43:D413-422 (2015); Chothia et al., (1989) Nature 342:877; Chothia, C. et al. (1987) J. Mol. Biol. 196:901-917, Al-lazikani et al (1997) J. Molec. Biol. 273:927-948; and Almagro, J. Mol. Recognit. 17:132-143 (2004). See also hgmp.mrc.ac.uk and bioinf.org.uk / abs. As used herein, a CDR may refer to the CDR defined by any method known in the art. Two antibodies having the same CDR means that the two antibodies have the same amino acid sequence of that CDR as determined by the same method, for example, the IMGT definition.

[0071] In certain embodiments, there are three CDRs in each of the variable regions of a heavy chain and a light chain, which are designated CDR1, CDR2 and CDR3, for each of the variable regions. The term “CDR set” as used herein refers to a group of three CDRs that occur in a single variable region capable of binding the antigen. The exact boundaries of these CDRs have been defined differently according to different systems. The system described by Kabat (Kabat et al., Sequences of Proteins of Immunological Interest (National Institutes of Health, Bethesda, Md. (1987) and (1991)) not only provides an unambiguous residue numbering system applicable to any variable region of an antibody, but also provides precise residue boundaries defining the three CDRs. These CDRs may be referred to as Kabat CDRs. Sub-portions of CDRs may be designated as LC CDR1, LC CDR2 and LC CDR3 or HC CDR1, HC CDR2 and HC CDR3 where the “LC” and the “HC” designate the light chain and the heavy chains regions, respectively. These regions may be referred to as Chothia CDRs, which have boundaries that overlap with Kabat CDRs. Other boundaries defining Docket No. A1361.70024WO00 14108730.1CDRs overlapping with the Kabat CDRs have been described by Padlan (FASEB J. 9:133- 139 (1995)) and MacCallum (J Mol Biol 262(5):732-45 (1996)). Still other CDR boundary definitions may not strictly follow one of the above systems, but will nonetheless overlap with the Kabat CDRs, although they may be shortened or lengthened in light of prediction or experimental findings that particular residues or groups of residues or even entire CDRs do not significantly impact antigen binding. The methods used herein may utilize CDRs defined according to any of these systems, although preferred embodiments use Kabat or Chothia defined CDRs.

[0072] In certain embodiments, the CDRs of an antibody may have different amino acid sequences when different definition systems are used (e.g., the IMGT definition, the Kabat definition, or the Chothia definition). A definition system annotates each amino acid in a given antibody sequence (e.g., VH or VL sequence) with a number, and numbers corresponding to the heavy chain and light chain CDRs are provided in Table 2. The CDRs listed in Table 1 are defined in accordance with the Kabat definition. One skilled in the art is able to derive the CDR sequences using the different numbering systems for the anti- CD3 antibodies provided in Table 1. Table 2. CDR Definitions IMGT1Kabat2Chothia3leic Acids Res., 27:209-212 (1999)2Kabat et al. (1991) Sequences of Proteins of Immunological Interest, Fifth Edition, U.S. Department of Health and Human Services, NIH Publication No.91-32423Chothia et al., J. Mol. Biol.196:901-917 (1987))

[0073] CDR-grafted antibody: The term “CDR-grafted antibody” refers to antibodies which comprise heavy and light chain variable region sequences from one species but in which the sequences of one or more of the CDR regions of VH and / or VL are replaced with CDR sequences of another species, such as antibodies having murine heavy and light chain variable regions in which one or more of the murine CDRs (e.g., CDR3) has been replaced with human CDR sequences.

[0074] Chemotherapeutic agent: As used herein, a “chemotherapeutic agent” refers to a chemical compound useful in the treatment of proliferative disorders, such as cancers. These Docket No. A1361.70024WO00 14108730.1agents can be, e.g., alkylating agents, such as thiotepa and cyclophosphamide (CYTOXAN®); alkylsulfonates such as busulfan, improsulfan and piposulfane; aziridines such as benzodopa, carbocuone, meturedopa and uredopa; ethylene imines and methylamelamines, including altretamine, triethylene methamine, triethylene phosphoramide, triethylene-thiophosphoramide and trimethylolomelamine; acetogenins (especially bulatacin and bulatacinone); delta-9-tetrahydrocannabinol (dronabinol, MARINOL); beta-lapacona; lapacol; Colchicines; betulinic acid; a camptothecin (which includes the synthetic analog topotecan (HYCAMTIN®), CPT-11 (irinotecan, CAMPTOSAR), acetylcamptothecin, scopolectin and 9-aminocamptothecin); Bryostatin; Callistatin; CC-1065 (including its synthetic analogs of adozelesin, carzelesin and bizelesin); podophyllotoxin; podophyllinic acid; teniposide; cryptophycins (particularly cryptophycin 1 and cryptophycin 8); dolastatin; duocarmycin (which include the synthetic analogs, KW-2189 and CB1-TM1); eleutherobin; pancratistatin; a sarcodictiina, -pongistatin; nitrogen mustards such as chlorambucil, chlornaphazine, colofosfamide, estramustine, ifosfamide, mechlorethamine, mechlorethamine oxide hydrochloride, melphalan, novembichin, phenesterin, prednimustine, trofosfamidea, uracil mustard; nitrosureas such as carmustine, chlorozotocin, fotemustine, lomustine, nimustine and ranimnustine; antibiotics, such as enediin antibiotics (e.g., calicheamicin, especially gammall calicheamicin and omegall calicheamicin (see, for example, Agnew, Chem Intl. Ed. Engl., 33: 183-186 (1994)); dynemycin, including dynemycin A; a esperamycin; as well as neocarzinostatin chromophore and chromophores of related chromoprotein antibiotics), aclacinomisins, actinomycin, autramycin, azaserin, bleomycin, cactinomycin, carabicin, carminomycin, carzinophilin, chromomycins, dactinomycin, daunorubicin, detorrubicin, 6-diazo-5-oxo- L-norleucine, doxorubicin (including morpholino- doxorubicin, cyanomorpholino-doxorubicin, 2-pyrrolino-doxorubicin and deoxydoxorubicin), epirubicin, esorubicin, idarubicin, marcellomycin, mitomycins such as mitomycin C, mycophenolic acid, nogalamycin, olivomycins, peplomycin, porfiromycin, puromycin , chelamicin, rodrububicin, streptonigrin, streptozocin, tubercidin, ubenimex, zinostatin, zorubicin; anti-metabolites such as methotrexate and 5-fluorouracil (5-FU); folic acid analogues such as denopterin, methotrexate, pteropterin, trimetrexate; purine analogues such as fludarabine, 6-mercaptopurine, tiamiprin, thioguanine; analogues of pyrimidine such as ancitabine, azacitidine, 6-azauridine, carmofur, cytarabine, dideoxyuridine, doxifluridine, enocythabin, floxuridine; androgens such as calusterone, dromostanolone propionate, epithiostanol, mepitiostane, testolactone; antisuprenal drugs such as aminoglutethimide, Docket No. A1361.70024WO00 14108730.1mitotane, trilostane; folic acid enhancer such as frolinic acid; aceglatone; aldophosphamide glycoside; aminolevulinic acid; eniluracil; amsacrine; bestrabuchil; bisantrene; driamycin; defofamin; demecolcine; diazicuone; elfornitin; eliptinium acetate; an epothilone; etoglucid; gallium nitrate; hydroxyurea; lentinan; lonidainin; maytansinoids such as maytansine and ansamitocins; mitoguazone; mitoxantrone; mopidanmol; nitraerine; pentostatin; fenamet; pirarubicin; losoxantrone; 2-ethylhydrazide; procarbazine; PSK® polysaccharide complex (JHS Natural Products, Eugene, OR); razoxane; rhizoxin; sizofirano; spirogermanium; tenuazonic acid; triazicuone; 2,2 ‘, 2”-trichlorotriethylamine, trichothecenes (especially T-2 toxin, verracurin A, roridin A and anguidine), urethane, vindesine (ELDISINE, FILDESIN), dacarbazine, manomustine, mitobronitol, mitolactol, pipobroman, gacitosin, arabinoside (“Ara-C”), thiotepa, taxoids, for example, paclitaxel (TAXOL, Bristol-Myers Squibb Oncology, Princeton, NJ), Cremophor-free ABRAXANE ™, nanoparticle formulation modified with paclitaxel albumin (American Pharmaceutical Partners, Schaumberg, Illinois), and docetaxel (TAXOTERE®; Rhone-Poulenc Rorer, Antony, France); chloranbuchil; gemcitabine (GEMZAR); 6-thioguanine; mercaptopurine; methotrexate; platinum analogues such as cisplatin and carboplatin; vinblastine (VELBAN®); platinum; etoposide (VP-16); ifosfamide; mitoxantrone; vincristine (ONCOVIN®); oxaliplatin; leucovovina; vinorrelbine (NAVELBINE®); novantrone; edatrexate; Daunomycin; aminopterin; ibandronate; Topoisomerase inhibitor RFS 2000; difluoromethylornithine (DMFO); retinoids such as retinoic acid; capecitabine (XELODA®); pharmaceutically acceptable salts, acids or derivatives of any of the foregoing; as well as combinations of two or more of the foregoing such as CHOP, an abbreviation for a combination therapy of cyclophosphamide, doxorubicin, vincristine and prednisolone; CVP, an abbreviation for a combination therapy of cyclophosphamide, vincristine and prednisolone; and FOLFOX, an abbreviation for an oxaliplatin treatment regimen (ELOXATIN ™) combined with 5-FU and leucovorin.

[0075] Chimeric antibody: The term “chimeric antibody” refers to antibodies which comprise heavy and light chain variable region sequences from one species and constant region sequences from another species, such as antibodies having murine heavy and light chain variable regions linked to human constant regions.

[0076] Compete: The term “compete”, as used herein with regard to an antibody, means that a first antibody binds to an epitope of a protein (e.g., CD3) in a manner sufficiently similar to the binding of a second antibody, such that the result of binding of the first antibody with its epitope is detectably decreased in the presence of the second antibody Docket No. A1361.70024WO00 14108730.1compared to the binding of the first antibody in the absence of the second antibody. The alternative, where the binding of the second antibody to its epitope is also detectably decreased in the presence of the first antibody, can, but need not be the case. That is, a first antibody can inhibit the binding of a second antibody to its epitope without that second antibody inhibiting the binding of the first antibody to its respective epitope. However, where each antibody detectably inhibits the binding of the other antibody with its epitope or ligand, whether to the same, greater, or lesser extent, the antibodies are said to “Cross-compete” with each other for binding of their respective epitope(s). In some embodiments, antibodies that compete or cross-compete bind to the same or overlapping epitopes. Regardless of the mechanism by which such competition or cross-competition occurs (e.g., steric hindrance, conformational change, or binding to a common epitope, or portion thereof), the skilled artisan would appreciate that such competing and / or cross-competing antibodies are encompassed and can be useful for the methods and / or compositions provided herein.

[0077] Complementary: As used herein, the term “complementary” refers to the capacity for precise pairing between two nucleotides or two sets of nucleotides. In particular, complementary is a term that characterizes an extent of hydrogen bond pairing that brings about binding between two nucleotides or two sets of nucleotides. For example, if a base at one position of an oligonucleotide is capable of hydrogen bonding with a base at the corresponding position of a target nucleic acid (e.g., an mRNA), then the bases are considered to be complementary to each other at that position. Base pairings may include both canonical Watson-Crick base pairing and non-Watson-Crick base pairing (e.g., Wobble base pairing and Hoogsteen base pairing). For example, in some embodiments, for complementary base pairings, adenosine-type bases (A) are complementary to thymidine- type bases (T) or uracil-type bases (U), that cytosine-type bases (C) are complementary to guanosine-type bases (G), and that universal bases such as 3-nitropyrrole or 5-nitroindole can hybridize to and are considered complementary to any A, C, U, or T. Inosine (I) has also been considered in the art to be a universal base and is considered complementary to any A, C, U or T.

[0078] Conjugated: As used herein, “conjugated” means two entities are associated, preferably with sufficient affinity that a therapeutic / diagnostic benefit of the association between the two entities is realized. The association between the two entities can be either direct or via a linker, such as a polymer linker. Conjugated can include covalent or noncovalent bonding as well as other forms of association, such as entrapment, e.g., of one Docket No. A1361.70024WO00 14108730.1entity on or within the other, or of either or both entities on or within a third entity, such as a micelle.

[0079] Conservative amino acid substitution: As used herein, a “conservative amino acid substitution” refers to an amino acid substitution that does not alter the relative charge or size characteristics of the protein in which the amino acid substitution is made. Variants can be prepared according to methods for altering polypeptide sequence known to one of ordinary skill in the art such as are found in references which compile such methods, e.g. Molecular Cloning: A Laboratory Manual, J. Sambrook, et al., eds., Fourth Edition, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, New York, 2012, or Current Protocols in Molecular Biology, F.M. Ausubel, et al., eds., John Wiley & Sons, Inc., New York. Conservative substitutions of amino acids include substitutions made amongst amino acids within the following groups: (a) M, I, L, V; (b) F, Y, W; (c) K, R, H; (d) A, G; (e) S, T; (f) Q, N; and (g) E, D.

[0080] Cross-reactive: As used herein and in the context of a targeting agent (e.g., antibody), the term “cross-reactive,” refers to a property of the agent being capable of specifically binding to more than one antigen of a similar type or class (e.g., antigens of multiple homologs, paralogs, or orthologs) with similar affinity or avidity.

[0081] Cytotoxic agent: As used herein, the term “cytotoxic agent” refers to a substance that inhibits or prevents a cellular function and / or causes cell death or destruction. Such agents are well known in the art, and include, e.g., radioactive isotopes (e.g., At211, I131, I125, Y90, Re186, Re188, Sm153, Bi212, P32, Pb212and radioactive isotopes of Lu); chemotherapeutic agents or drugs (e.g., methotrexate, adriamycin, vinca alkaloids (vincristine, vinblastine, etoposide), doxorubicin, melphalan, mitomycin C, chlorambucil, daunorubicin, or other intercalating agents); growth inhibitory agents; enzymes and fragments thereof, such as nucleolytic enzymes; antibiotics; toxins such as small molecule toxins or enzymatically active toxins of bacterial, fungal, plant or animal origin, including fragments and / or variants thereof; and the various anti-tumor or anti-cancer agents described below.

[0082] Developability: As used herein, the term “developability” refers to the extent to which a polypeptide, such as an antibody or antibody fragment, possesses characteristics favorable for its manufacture, formulation, storage, and clinical use. Attributes of developability include, but are not limited to: high expression in eukaryotic cells, solubility, low viscosity, resistance to aggregation, high chemical and thermal stability, long serum half- life, low clearance rate, and minimal nonspecific or polyspecific binding. Developability may Docket No. A1361.70024WO00 14108730.1be assessed using a suite of biophysical and biochemical assays including, but not limited to, PSR (polyspecificity reagent) binding, AC-SINS (affinity-capture self-interaction nanoparticle spectroscopy), HIC (hydrophobic interaction chromatography), SEC (size- exclusion chromatography), DLS (dynamic light scattering), DSF (differential scanning fluorimetry), CIC (cross-interaction chromatography), and others. A developability profile may refer to the composite score or assessment derived from these assays and can be used to compare or rank antibody candidates.

[0083] Effective Amount: As used herein, “an effective amount” refers to the amount of each active agent (e.g., anti-CD3 antibody) required to confer a desired effect (e.g., a therapeutic effect on the subject), either alone or in combination with one or more other active agents. In some embodiments, the therapeutic effect is reduced depleted T cells or activity and / or alleviated disease conditions (e.g., treatment of cancer, infection, or an autoimmune disorder).

[0084] Framework: As used herein, the term “framework” or “framework sequence” refers to the remaining sequences of a variable region minus the CDRs. Because the exact definition of a CDR sequence can be determined by different systems, the meaning of a framework sequence is subject to correspondingly different interpretations. The six CDRs (LC CDR1, LC CDR2, and LC CDR3 of light chain and HC CDR1, HC CDR2, and HC CDR3 of heavy chain) also divide the framework regions on the light chain and the heavy chain into four sub-regions (FR1, FR2, FR3 and FR4) on each chain, in which CDR1 is positioned between FR1 and FR2, CDR2 between FR2 and FR3, and CDR3 between FR3 and FR4. Without specifying the particular sub-regions as FR1, FR2, FR3 or FR4, a framework region, as referred to by others, represents the combined FRs within the variable region of a single, naturally occurring immunoglobulin chain. As used herein, a FR represents one of the four sub-regions, and FRs represents two or more of the four sub-regions constituting a framework region. Human heavy chain and light chain acceptor sequences are known in the art. In one embodiment, the acceptor sequences known in the art may be used in the antibodies disclosed herein.

[0085] HIC Retention Time: As used herein, the term “Hydrophobic Interaction Chromatography (HIC)” refers to a technique used to assess hydrophobicity of antibodies. Retention time on a HIC column is used as a proxy for hydrophobicity. Lower retention times are generally indicative of more favorable developability profiles. Docket No. A1361.70024WO00 14108730.1

[0086] Human antibody: 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 disclosure 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.

[0087] Humanized antibody: The term “humanized antibody” refers to antibodies which comprise heavy and light chain variable region sequences from a non-human species (e.g., a mouse) but in which at least a portion of the VH and / or VL sequence has been altered to be more “human-like”, i.e., more similar to human germline variable sequences. One type of humanized antibody is a CDR-grafted antibody, in which non-human CDR sequences are introduced into human VH and VL sequences to replace the corresponding human germline CDR sequences. In one embodiment, humanized anti-CD3 antibodies and antigen binding portions are provided. Such antibodies may be generated by obtaining murine anti-CD3 monoclonal antibodies using traditional hybridoma technology followed by humanization using in vitro genetic engineering, such those disclosed in Kasaian et al. PCT publication No. WO 2005 / 123126 A2. In some embodiments, humanization involves switching light chain isotypes. In some embodiments, during humanization, a lambda light chain is changed to a kappa light chain. In some embodiments, during humanization, a kappa light chain is changed to a lambda light chain. In some embodiments, humanization may be guided by machine learning using a deep learning model trained on Hu-mAb (Oxford Protein Informatics Group), or BioPhi (Prihoda et al. A platform for antibody design, humanization, and humanness evaluation based on natural antibody repertoires and deep learning. 2022. mAbs, 14:1.). In some embodiments, humanization may also be guided by heuristic rules used in the art (Honegger, A. Engineering antibodies for stability and efficient folding. 2008. Therapeutic Antibodies, 47-68). In some embodiments, humanization may also be guided by matching the non-human CDRs against a large database of known human CDRs using machine learning or heuristic rules, thereby identifying suitable human VH and VL acceptor frameworks. Any of the suitable humanization methods can be used alone or in combination. Docket No. A1361.70024WO00 14108730.1

[0088] Humanized antibodies are human immunoglobulins (recipient antibody) in which residues from a complementary determining region (CDR) of the recipient are replaced by residues from a CDR of a non-human species (donor antibody) such as mouse, rat, or rabbit having the desired specificity, affinity, and capacity. In some embodiments, Fv framework region (FR) residues of the human immunoglobulin are replaced by corresponding non- human residues. Furthermore, the humanized antibody may comprise residues that are found neither in the recipient antibody nor in the imported CDR or framework sequences, but are included to further refine and optimize antibody performance. In general, the humanized antibody will comprise substantially all of at least one, and typically two, variable domains, in which all or substantially all of the CDR regions correspond to those of a non-human immunoglobulin and all or substantially all of the FR regions are those of a human immunoglobulin consensus sequence. The humanized antibody optimally also will comprise at least a portion of an immunoglobulin constant region or domain (Fc), typically that of a human immunoglobulin. Antibodies may have Fc regions modified as described in WO 99 / 58572. Other forms of humanized antibodies have one or more CDRs (one, two, three, four, five, six) which are altered with respect to the original antibody, which are also termed one or more CDRs derived from one or more CDRs from the original antibody. Humanized antibodies may also involve affinity maturation.

[0089] In some embodiments, humanization is achieved by grafting the CDRs (e.g., as shown in Table 1) into the human variable domains (e.g., IGHV3-23, IGHV3-72, IGHV3-73, IGKV3-20, IGKV1-16, IGLV1-40, IGLV1-44, IGLV1-47, and IGKV4-1 human variable domains). In some embodiments, the anti-CD3 antibody of the present disclosure is a humanized variant comprising one or more amino acid substitutions (e.g., in the VH framework region) as compared with any one of the VHs listed in Table 1, and / or one or more amino acid substitutions (e.g., in the VL framework region) as compared with any one of the VLs listed in Table 1.

[0090] Framework regions provide the structural support for antibodies. Alterations in the framework sequences of an antibody can affect the structural stability, antibody conformation, solubility, effector functions (e.g., antibody-dependent cellular cytotoxicity), and immunogenicity of an antibody. Humanization of a framework region or regions can increase stability, reduce immunogenicity, and increase specificity and affinity of an antibody for a human antigen compared to antibodies that have not been humanized. Docket No. A1361.70024WO00 14108730.1

[0091] Methods of antibody humanization can also affect the properties of the humanized antibody. Humanizing antibodies can include altering the framework regions of an antibody (e.g., to replace them with human framework sequences), grafting CDRs into a human variable domain (as described above), optimizing the residues in the framework and CDR regions to improve binding to human antigen and / or reduce immunogenicity, or a combination of any of the aforementioned. Machine learning algorithms and heuristic rules known in the art may be used to humanize an antibody.

[0092] Isolated antibody: An “isolated antibody”, as used herein, is intended to refer to an antibody that is substantially free of other antibodies having different antigenic specificities (e.g., an isolated antibody that specifically binds CD3 is substantially free of antibodies that specifically bind antigens other than CD3. An isolated antibody that specifically binds CD3 may, however, have cross-reactivity to other antigens. Moreover, an isolated antibody may be substantially free of other cellular material and / or chemicals.

[0093] Kabat numbering: The terms “Kabat numbering”, “Kabat definitions” and “Kabat labeling” are used interchangeably herein. These terms, which are recognized in the art, refer to a system of numbering amino acid residues which are more variable (i.e. hypervariable) than other amino acid residues in the heavy and light chain variable regions of an antibody, or an antigen binding portion thereof (Kabat et al. (1971) Ann. NY Acad, Sci. 190:382-391 and, Kabat, E. A., et al. (1991) Sequences of Proteins of Immunological Interest, Fifth Edition, U.S. Department of Health and Human Services, NIH Publication No. 91-3242). For the heavy chain variable region, the hypervariable region ranges from amino acid positions 31 to 35 for CDR1, amino acid positions 50 to 65 for CDR2, and amino acid positions 95 to 102 for CDR3. For the light chain variable region, the hypervariable region ranges from amino acid positions 24 to 34 for CDR1, amino acid positions 50 to 56 for CDR2, and amino acid positions 89 to 97 for CDR3.

[0094] Multispecific Antibody: As used herein, the term “multispecific antibody” refers to a polypeptide or a complex (e.g., two or more covalently linked polypeptides) that includes at least two different immunoglobulin variable domains or at least two different sites, e.g., paratopes, that specifically bind to one or more antigens. For example, in one embodiment, a multispecific antibody is a polypeptide that includes at least two different sites in which each site binds to a different epitope of the same antigen. In other embodiments, a multispecific antibody is a polypeptide that includes at least two different sites in which each site binds to a different antigen. In some embodiments, a multispecific antibody is a trispecific antibody Docket No. A1361.70024WO00 14108730.1comprises three different sites in which each site binds to a different antigen. In some embodiments, a trispecific antibody comprises a site comprising an anti-CD3 antibody provided herein, a site that specifically binds a tumor antigen, and a site that specifically binds a T cell co-stimulatory antigen (e.g., that specifically binds CD28 or CD137 (4-1BB)) or a cytokine (e.g., that specifically binds interleukin (IL)-2, IL12, IL15, or IL-21).

[0095] Polyspecificity: As used herein, the term “polyspecificity” refers to the unintended binding of an antibody to multiple non-target antigens, often as a result of hydrophobic or electrostatic interactions. High polyspecificity is generally undesirable in therapeutic antibodies due to increased risk of off-target effects, altered pharmacokinetics, and increased immunogenicity. Polyspecificity can be assessed using PSR assays, CIC, SIC, and other binding or chromatography-based techniques.

[0096] PSR Score: As used herein, a “PSR score (Polyspecificity Reagent score)” is a quantitative measure of an antibody's propensity for nonspecific binding. It is typically derived from flow cytometry assays using labeled polyreactive reagents. Scores may generally be interpreted as follows: • ≤ PSR < 0.1: Clean • ≤ PSR < 0.33: Low • 0.33 ≤ PSR < 0.66: Medium • 0.66 ≤ PSR ≤ 1.0: High

[0097] A lower PSR score is generally associated with improved developability. A PSR experiment to produce a PSR score may be run with control antibodies have low, medium and high polyreactivity to establish cutoffs for nonspecific binding for a given experiment.

[0098] Recombinant antibody: The term “recombinant antibody”, as used herein, is intended to include all 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 in more details in this disclosure), including, for example, antibodies isolated from a recombinant, combinatorial human antibody library (Hoogenboom H. R., (1997) TIB Tech. 15:62-70; Azzazy H., and Highsmith W. E., (2002) Clin. Biochem. 35:425-445; Gavilondo J. V., and Larrick J. W. (2002) BioTechniques 29:128- 145; Hoogenboom H., and Chames P. (2000) Immunology Today 21:371-378), antibodies isolated from an animal (e.g., a mouse) that is transgenic for human immunoglobulin genes (see e.g., Taylor, L. D., et al. (1992) Nucl. Acids Res. 20:6287-6295; Kellermann S-A., and Green L. L. (2002) Current Opinion in Biotechnology 13:593-597; Little M. et al (2000) Docket No. A1361.70024WO00 14108730.1Immunology Today 21:364-370) or antibodies prepared, expressed, created or isolated by any other means that involves splicing of human immunoglobulin gene sequences to other DNA sequences. In some embodiments, recombinant human antibodies are provided herein. In certain embodiments, 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 VH and VL regions of the recombinant antibodies are sequences that, while derived from and related to human germline VH and VL sequences, may not naturally exist within the human antibody germline repertoire in vivo. One embodiment of the disclosure provides fully human antibodies capable of binding human CD3 which can be generated using techniques well known in the art, such as, but not limited to, using human Ig phage libraries such as those disclosed in Jermutus et al., PCT publication No. WO 2005 / 007699 A2.

[0099] Selective: As used herein, the term “selective” or “selectively” refers to the ability of a molecule to produce an effect (e.g., inhibit, antagonize, agonize, etc.) in relation to its target molecule compared to a reference molecule. For example, a molecule that selectively inhibits its target molecule means that this molecule is capable of inhibiting its target molecule to a degree that is distinguishable from a reference molecule in an inhibition assay or other inhibitory context. For example, with respect to an inhibitor, the term, “selectively inhibits”, refers to the ability of the inhibitor to inhibit its target molecule with a degree that is distinguishable from a reference molecule that is not substantially inhibited in an inhibition assay, e.g., to an extent that permit selective inhibition of the target molecule, as described herein. Once the reaction is terminated, the signal produced by inhibiting the target molecule can be measured. The half maximal inhibitor concentration for the target molecule and the reference molecule can be calculated. In some embodiments, a molecule described herein selectively binds to a target molecule. In some embodiments, a molecule described herein selectively binds CD3. In some embodiments, a molecule described herein directs a CD3- expressign cell (e.g., a T cell) to target a cancer cell or an infected cell. In some embodiments, a molecule described herein binds to CD3 to induce apoptosis of a CD3- expressing cell (e.g., a T cell). In some embodiments, a molecule described herein binds to CD3 to induce activation and proliferation of a CD3-expressing cell (e.g., a T cell). Docket No. A1361.70024WO00 14108730.1[000100] Specifically binds: As used herein, the term “specifically binds” refers to the ability of a molecule to bind to a binding partner with a degree of affinity or avidity that enables the molecule to be used to distinguish the binding partner from an appropriate control in a binding assay or other binding context. With respect to an antibody, the term, “specifically binds”, refers to the ability of the antibody to bind to a specific antigen with a degree of affinity or avidity, compared with an appropriate reference antigen or antigens, which enables the antibody to be used to distinguish the specific antigen from others, as described herein. In some embodiments, an antibody specifically binds to a target if the antibody has a KD for binding the target of at least about 10-4M, 10-5M, 10-6M, 10-7M, 10-8M, 10-9M, 10-10M, 10-11M, 10-12M, 10-13M, or less. In some embodiments, an antibody specifically binds CD3. [000101] SP34: As used herein, “SP34” refers to a murine monoclonal antibody that binds to the epsilon (CD3ε) subunit of the CD3 complex. It is widely used in immunological studies as a benchmark anti-CD3 antibody. The murine SP34 variable region sequences are provided below: • SP34 VH (EVQLVESGGGLVQPKGSLKLSCAASGFTFNTYAMNWVRQAPGKGLEWVAR IRSKYNNYATYYADSVKDRFTISRDDSQSILYLQMNNLKTEDTAMYYCVRHG NFGNSYVSWFAYWGQGTLVTVSA): [SEQ ID NO: 122] • SP34 VL (QAVVTQESALTTSPGETVTLTCRSSTGAVTTSNYANWVQEKPDHLFTGLIGG TNKRAPGVPARFSGSLIGDKAALTITGAQTEDEAIYFCALWYSNLWVFGGGT KLTVL): [SEQ ID NO: 123] SP34 is known for its high affinity to human CD3Œµ and its ability to activate T cells. It also demonstrates cross-reactivity to CD3 from non-human primates, including cynomolgus monkeys. [000102] Subject: As used herein, the term “subject” refers to a mammal. In some embodiments, a subject is a human. In some embodiments, a subject is a patient, e.g., a human patient that has or is suspected of having a disease. In some embodiments, the subject Docket No. A1361.70024WO00 14108730.1is a human patient who has or is suspected of having cancer and / or one or more conditions arising as a result of a cancer. [000103] Treatment: As used herein, the term “treating” or “treatment” refers to the application or administration of a composition including one or more active agents (e.g., anti- CD3 antibodies) to a subject, who has a target disease or disorder (e.g., cancer, infection, or an autoimmune disorder), a symptom of the disease / disorder, or a predisposition toward the disease / disorder, with the purpose to cure, heal, alleviate, relieve, alter, remedy, ameliorate, improve, or affect the disorder, the symptom of the disease, or the predisposition toward the disease or disorder. Alleviating a target disease / disorder includes delaying or preventing the development or progression of the disease, or reducing disease severity. II. Developability of Anti-CD3 antibodies [000104] The present disclosure, at least in part, provides engineered humanized SP34 (hSP34) antibodies that specifically recognize and bind CD3 and display improved developability properties (e.g., improved binding affinity, and / or reduced polyreactivity) as compared to existing humanized anti-CD3 antibodies or the murine parental antibody. Improved properties may be improved binding affinity, reduced polyreactivity, expression in eukaryotic cells, solubility, low viscosity, resistance aggregation, high chemical and thermal stability, long serum half-life, low clearance rate, minimal non-specific or polyspecific binding, or some combination thereof. [000105] In some embodiments, an improved developability property of an antibody provided herein is improved binding affinity relative to an existing anti-CD3 antibody or a murine parental antibody. Improved binding affinity may be binding affinity that is increased by 50% to 1,000%, 100% to 950%, 150% to 900%, 200% to 850%, 250% to 800%, 300% to 750%, 350% to 700%, 400% to 650%, 450% to 600%, or 500% to 550% relative to an existing anti-CD3 antibody or a murine parental antibody. In some embodiments, improved binding affinity is increased by 50%, 75%, 100%, 125%, 150%, 175%, 200%, 225%, 250%, 275%, 300%, 325%, 350%, 375%, 400%, 425%, 450%, 475%, 500%, 525%, 550%, 575%, 600%, 625%, 650%, 675%, 700%, 725%, 750%, 775%, 800%, 825%, 850%, 875%, 900%, 925%, 950%, 975%, or 1,000% or more relative to an existing anti-CD3 antibody or a murine parental antibody. [000106] In some embodiments, an improved developability property of an antibody provided herein is reduced polyreactivity relative to an existing anti-CD3 antibody or a Docket No. A1361.70024WO00 14108730.1murine parental antibody. Polyreactivity, as used herein, refers to cross-reactivity to off- target antigens (e.g., antigens other than CD3). Reduced polyreactivity is an improved developability property of an antibody because an antibody that has reduced cross-reactivity to off-target antigens is more likely to bind to its target antigen more consistently, requiring lower and / or less consistent antibody administration. In some embodiments, an antibody provided herein has polyreactivity that is reduced by 10% to 100%, 20% to 90%, 30% to 80%, 40% to 70%, or 50% to 60% relative to an existing anti-CD3 antibody or a murine parental antibody. In some embodiments, an antibody provided herein has polyreactivity that is reduced by 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100% or more relative to an existing anti-CD3 antibody or a murine parental antibody. [000107] In some embodiments, an improved developability property of an antibody provided herein is expression in eukaryotic cells. Expression in eukaryotic cells is a developability advantage (e.g., an improved property) relative to an antibody that is not expressed in eukaryotic cells because: antibodies expressed in eukaryotic cells are subject to increased expression regulation (e.g., transcriptional, post-transcription, translational, post- translational), antibodies expressed in eukaryotic cells have increased complexity compared to prokaryotic cells (e.g., post-translational modifications), have higher levels of antibody production, or some combination thereof. It is to be understood that each of these properties are relative to expression in prokaryotic cells. Non-limiting examples of eukaryotic cells that may express an antibody provided herein are: mammalian cells, yeast cells, plant cells, fungal cells, and protozoan cells. In some embodiments, an improved biophysical and / or developability property of an antibody provided herein is expression in mammalian cells. [000108] In some embodiments, an improved developability property of an antibody provided herein is increased solubility relative to an existing anti-CD3 antibody or murine parental antibody. Solubility means that an antibody retains its proper, folded antibody conformation in solution (e.g., buffer, serum, etc). Increased solubility may be increased by 10% to 100%, 20% to 90%, 30% to 80%, 40% to 70%, or 50% to 60% relative to an existing anti-CD3 antibody or a murine parental antibody. In some embodiments, an antibody provided herein has solubility that is increased by 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100% or more relative to an existing anti-CD3 antibody or a murine parental antibody. Docket No. A1361.70024WO00 14108730.1[000109] In some embodiments, an improved developability property of an antibody provided herein is low viscosity relative to an existing anti-CD3 antibody or murine parental antibody. Low viscosity means that the thickness (also known as resistance to flow) of a solution comprising an antibody provided herein is lower for an antibody provided herein relative to an existing anti-CD3 antibody or murine parental antibody. Lower viscosity provides increased administration routes and may improve drug delivery. Lower viscosity may be decreased by 10% to 100%, 20% to 90%, 30% to 80%, 40% to 70%, or 50% to 60% relative to an existing anti-CD3 antibody or a murine parental antibody. In some embodiments, an antibody provided herein has solubility that is decreased by 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100% or more relative to an existing anti-CD3 antibody or a murine parental antibody. [000110] In some embodiments, an improved developability property of an antibody provided herein is increased resistance to aggregation relative to an existing anti-CD3 antibody or a murine parental antibody. Resistance to aggregation means that an antibody provided herein retains its proper, folded antibody conformation as opposed to mis-folded, higher order aggregates comprising an antibody provided herein. In some embodiments, an antibody provided herein has resistance to aggregation that is increased by 10% to 100%, 20% to 90%, 30% to 80%, 40% to 70%, or 50% to 60% relative to an existing anti-CD3 antibody or a murine parental antibody. In some embodiments, an antibody provided herein has resistance to aggregation that is increased by 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100% or more relative to an existing anti-CD3 antibody or a murine parental antibody. [000111] In some embodiments, an improved developability property of an antibody provided herein is high chemical and thermal stability relative to an existing anti-CD3 antibody or a murine parental antibody. High chemical stability may be improved tolerance to an acidic environment or acidic stress, such as a pH of about 6 or below, about 5 or below, about 4 or below, about 3 or below, or about 2 or below. High thermal stability by a melting temperature of about 55ºC, about 56ºC,about 57ºC, about 58ºC, about 59ºC, about 60ºC, about 61ºC, about 62ºC, about 63ºC, 64ºC, or about 65ºC, or higher. [000112] In some embodiments, an improved developability property of an antibody provided herein is long serum half-life relative to an existing anti-CD3 antibody or a murine parental antibody. Long serum half-life is increased concentration of an anti-CD3 in the serum of a subject administered the antibody. Long serum half-life is a half-life of 7 days, 8 Docket No. A1361.70024WO00 14108730.1days, 9 days, 10 days, 11 days, 12 days, 13 days, 14 days, 15 days, 16 days, 17 days, 18 days, 19 days, 20 days, 21 days, 22 days, 23 days, 24 days, 25 days, 26 days, 27 days, 28 days, 29 days, or 29 days or more. [000113] In some embodiments, an improved developability property of an antibody provided herein is low clearance rate relative to an existing anti-CD3 antibody or a murine parental antibody. Low clearance rate is reduced clearance of an antibody (e.g., relative to an existing anti-CD3 antibody) from a subject. Clearance may clearance by liver, clearance by kidney, or any other antibody clearance route known in the art. [000114] Developability may be assessed using a suite of biophysical and biochemical assays including, but not limited to, PSR (polyspecificity reagent) binding, AC-SINS (affinity- capture self-interaction nanoparticle spectroscopy), HIC (hydrophobic interaction chromatography), SEC (size-exclusion chromatography), DLS (dynamic light scattering), DSF (differential scanning fluorimetry), CIC (cross-interaction chromatography), enzyme linked immunosorbent assay (ELISA), measuring antibody concentration in body fluid (e.g., blood, plasma, serum, urine, etc). III. Antibodies and Related Compositions (a) Anti-CD3 Antibodies [000115] In some embodiments, a humanized anti-CD3 antibody provided herein has enhanced affinity for human CD3 relative to anti-CD3 antibodies known in the art. In some embodiments, a humanized anti-CD3 antibody provided herein has increased specificity for human CD3 relative to anti-CD3 antibodies in the art. In some embodiments, a humanized anti-CD3 antibody provided herein has reduced polyreactivity (e.g., cross-reactivity to off- target antigens) relative to anti-CD3 antibodies known in the art. In some embodiments, a humanized anti-CD3 antibody provided herein has increased stability relative to anti-CD3 antibodies known in the art. In some embodiments, a humanized anti-CD3 antibody provided herein has reduced immunogenicity relative to anti-CD3 antibodies known in the art. In some embodiments, a humanized anti-CD3 antibody provided herein has a reduced aggregation propensity or self-association propensity (e.g., as measured by affinity-capture self- interaction nanoparticle spectroscopy, AC-SINS). [000116] In some aspects, the disclosure provides a humanized anti-CD3 antibody. Anti-CD3 antibodies provided herein are humanized murine antibodies that demonstrate improved properties compared to non-humanized antibodies. For example, in some embodiments, a Docket No. A1361.70024WO00 14108730.1humanized anti-CD3 antibody provided herein exhibits enhanced affinity and / or specificity for human CD3 compared to an anti-CD3 antibody that has not been humanized or humanized anti-CD3 antibodies known in the art. In some embodiments, a humanized anti- CD3 antibody provided herein exhibits decreased polyreactivity (e.g., cross-reactivity with off-target antigens) compared to an anti-CD3 antibody that has not been humanized or humanized anti-CD3 antibodies known in the art. [000117] In some embodiments, the anti-CD3 antibody is an antibody specific for CD3 (e.g., CD3ε). Anti-CD3 antibodies can be useful for targeting T cells to induce their activation and / or proliferation, or to deplete them. Anti-CD3 antibodies can induce T cell activation and expansion via cross-linking and clustering of CD3 on the surface of T cells, mimicking signaling via the T cell receptor (TCR). Such activation and expansion can be helpful to generate a more robust T cell response, for example by increasing the population of de novo effector T cells responding to infection or cancer or by reactivating memory T cells to enhance the immune response against rechallenge by a pathogen or cancer. Conversely, depletion of T cells with anti-CD3 antibodies may be helpful where aberrant T cell responses drive pathology, such as in graft-versus-host disease (GVHD), organ transplantation, autoimmune disorders, or allergy. Additionally, depletion of endogenous T cells with anti- CD3 antibodies can improve the outcome of adoptive cell transfer, such as in the context of CAR-T cell therapy to treat cancer, by creating empty niches in lymphoid organs that can be engrafted by adoptively-transferred cells. [000118] The present disclosure, at least in part, provides engineered humanized SP34 (hSP34) antibodies that specifically recognizes and binds CD3. SP34 is a murine monoclonal antibody that binds human CD3ε with high affinity, demonstrates robust T cell activation, and exhibits cross-reactivity with non-human primate CD3, thereby facilitating preclinical studies in relevant animal models. SP34 is known for its high affinity to human CD3ε and its ability to activate T cells. It also demonstrates cross-reactivity to CD3 from non-human primates, including cynomolgus monkeys. In some embodiments, a comparator (e.g., control) anti-CD3 antibody provided herein is a SP34 antibody. [000119] In some embodiments, an antibody provided herein is a humanized SP34 antibody that specifically recognizes and binds CD3. In some embodiments, an antibody provided herein comprises a SP34 sequence that is humanized to reduce immunogenicity compared with a non-humanized sequence. Docket No. A1361.70024WO00 14108730.1[000120] Provided herein, in some aspects, are humanized antibodies that bind to human CD3 with high specificity and affinity. In some embodiments, the anti-CD3 antibody described herein specifically binds to any extracellular epitope of a CD3 or an epitope that becomes exposed to an antibody. In some embodiments, anti-CD3 antibodies provided herein bind to human CD3. In some embodiments, the anti-CD3 antibody described herein binds to an amino acid segment of a human CD3. CD3 is a multimeric protein expressed by T cells. CD3 is part of the T cell receptor (TCR) complex. Binding to CD3 can thus, in some instances, activate T cells. In some other instances, binding to CD3 can deplete T cells by inducing their apoptosis. In some instances, binding to CD3 is useful for redirecting T cells or detecting T cells. [000121] In some embodiments, the anti-CD3 antibody described herein specifically binds to human CD3. Human CD3 is made up of four subunits: CD3γ, CD3δ, CD3ε, and CD3ζ. An exemplary amino acid sequence of human CD3γ is set forth in NCBI Accession Number NP_000064.1 (SEQ ID NO: 119). [000122] Human CD3γ amino acid sequence (SEQ ID NO: 119): MEQGKGLAVLILAIILLQGTLAQSIKGNHLVKVYDYQEDGSVLLTCDAEAKNITWFKDGKMIGFLTED KKKWNLGSNAKDPRGMYQCKGSQNKSKPLQVYYRMCQNCIELNAATISGFLFAEIVSIFVLAVGVYFI AGQDGVRQSRASDKQTLLPNDQLYQPLKDREDDQYSHLQGNQLRRN [000123] An exemplary amino acid sequence of human CD3δ is set forth in NCBI Accession Number ACA05962.1 (SEQ ID NO: 42). [000124] Human CD3δ amino acid sequence (SEQ ID NO: 42): MEHSTFLSGLVLATLLSQVSPFKIPIEELEDRVFVNCNTSITWVEGTVGTLLSDITRLDLGKRILDPR GIYRCNGTDIYKDKESTVQVHYRMCQSCVELDPATVAGIIVTDVIATLLLALGVFCFAGHETGRLSGA ADTQALLRNDQVYQPLRDRDDAQYSHLGGNWARNK [000125] An exemplary amino acid sequence of human CD3ε is set forth in NCBI Accession Number NP_000724.1 (SEQ ID NO: 120). [000126] Human CD3ε amino acid sequence (SEQ ID NO: 120): MQSGTHWRVLGLCLLSVGVWGQDGNEEMGGITQTPYKVSISGTTVILTCPQYPGSEILWQHNDKNIGG DEDDKNIGSDEDHLSLKEFSELEQSGYYVCYPRGSKPEDANFYLYLRARVCENCMEMDVMSVATIVIV DICITGGLLLLVYYWSKNRKAKAKPVTRGAGAGGRQRGQNKERPPPVPNPDYEPIRKGQRDLYSGLNQ RRI [000127] Exemplary amino acid sequences of human CD3ζ are set forth in NCBI Accession Numbers NP_932170.1, NP_000725.1, NP_001365444.1, and NP_001365445.1. An exemplary amino acid sequence of human CD3ζ is set forth in SEQ ID NO: 121. Docket No. A1361.70024WO00 14108730.1[000128] Human CD3ζ amino acid sequence (SEQ ID NO: 121): MKWKALFTAAILQAQLPITEAQSFGLLDPKLCYLLDGILFIYGVILTALFLRVKFSRSADAPAYQQGQ NQLYNELNLGRREEYDVLDKRRGRDPEMGGKPQRRKNPQEGLYNELQKDKMAEAYSEIGMKGERRRGK GHDGLYQGLSTATKDTYDALHMQALPPR [000129] In some embodiments, an anti-CD3 antibody is an antibody specific for CD3. Provided herein, in some aspects, are antibodies that bind to human CD3 with high specificity and affinity. In some embodiments, the anti-CD3 antibody described herein specifically binds to any extracellular epitope of a CD3 or an epitope that becomes exposed to an antibody. [000130] In some embodiments, the anti-CD3 antibody described herein may bind to a fragment of a human CD3. The fragment of CD3 may be between about 5 and about 425 amino acids, between about 10 and about 400 amino acids, between about 50 and about 350 amino acids, between about 100 and about 300 amino acids, between about 150 and about 250 amino acids, between about 200 and about 300 amino acids, or between about 75 and about 150 amino acids in length. The fragment may comprise a contiguous number of amino acids from CD3. In some embodiments, the anti-CD3 antibody described herein binds a fragment of CD3 comprising the amino acid sequence of QDGNE (SEQ ID NO: 45). [000131] In some embodiments, an anti-CD3 antibody described herein are affinity matured clones. In some embodiments, an anti-CD3 antibody specifically binds a CD3 (e.g., a human CD3) with binding affinity (e.g., as indicated by KD) of at least about 10-4M, 10-5M, 10-6M, 10-7M, 10-8M, 10-9M, 10-10M, 10-11M, 10-12M, 10-13M, or less. For example, an anti-CD3 antibody of the present disclosure can bind to a CD3 protein (e.g., human CD3) with an affinity between 5 pM and 500 nM, between 50 pM and 100 nM, between 500 pM and 50 nM, between 1 nM and 50 nM, between 2 nM and 20 nM, between 1 nM and 10 nM, between 1 nM and 3 nM, or between 2 nM and 5 nM. In some embodiments, an anti-CD3 antibody specifically binds a CD3 (e.g., a human CD3ε) with a binding affinity in the range of 10 nM to 1000 nM, 10 nM to 900 nM, 10 nM to 800 nM, 10 nM to 700 nM, 10 nM to 600 nM, 10 nM to 500 nM, 10 nM to 400 nM, 10 nM to 300 nM, 10 nM to 200 nM, 10 nM to 100 nM, 10 nM to 90 nM, 10 nM to 80 nM, 10 nM to 70 nM, 10 nM to 60 nM, 10 nM to 50 nM, 10 nM to 40 nM, 10 nM to 30 nM, 10 nM to 20 nM, 10 nM to 15 nM, 20 nM to 1000 nM, 20 nM to 900 nM, 20 nM to 800 nM, 20 nM to 700 nM, 20 nM to 600 nM, 20 nM to 500 nM, 20 nM to 400 nM, 20 nM to 300 nM, 20 nM to 200 nM, 20 nM to 150 nM, 20 nM to 120 nM, 20 nM to 100 nM, 20 nM to 90 nM, 20 nM to 80 nM, 20 nM to 70 nM, 20 nM to 60 nM, 20 nM to 50 nM, 20 nM to 40 nM, 20 nM to 30 nM, 50 nM to 1000 nM, 50 nM to 900 nM, 50 nM to Docket No. A1361.70024WO00 14108730.1800 nM, 50 nM to 700 nM, 50 nM to 600 nM, 50 nM to 500 nM, 50 nM to 400 nM, 50 nM to 300 nM, 50 nM to 250 nM, 50 nM to 200 nM, 50 nM to 150 nM, 50 nM to 120 nM, 50 nM to 100 nM, 50 nM to 80 nM, 50 nM to 75 nM, 50 nM to 60 nM, 75 nM to 1000 nM, 75 nM to 900 nM, 75 nM to 800 nM, 75 nM to 700 nM, 75 nM to 600 nM, 75 nM to 500 nM, 75 nM to 400 nM, 75 nM to 300 nM, 75 nM to 250 nM, 75 nM to 200 nM, 75 nM to 150 nM, 75 nM to 120 nM, 75 nM to 100 nM, 75 nM to 80 nM, 100 nM to 1000 nM, 100 nM to 900 nM, 100 nM to 800 nM, 100 nM to 700 nM, 100 nM to 600 nM, 100 nM to 500 nM, 100 nM to 400 nM, 100 nM to 300 nM, 100 nM to 250 nM, 100 nM to 200 nM, 100 nM to 150 nM, 100 nM to 120 nM, 200 nM to 1000 nM, 200 nM to 900 nM, 200 nM to 800 nM, 200 nM to 700 nM, 200 nM to 600 nM, 200 nM to 500 nM, 200 nM to 400 nM, 200 nM to 300 nM, 200 nM to 250 nM, 300 nM to 1000 nM, 300 nM to 900 nM, 300 nM to 800 nM, 300 nM to 700 nM, 300 nM to 600 nM, 300 nM to 500 nM, 300 nM to 400 nM, 400 nM to 1000 nM, 400 nM to 900 nM, 400 nM to 800 nM, 400 nM to 750 nM, 400 nM to 700 nM, 400 nM to 650 nM, 400 nM to 600 nM, 400 nM to 550 nM, 400 nM to 500 nM, 500 nM to 1000 nM, 500 nM to 900 nM, 500 nM to 800 nM, 500 nM to 750 nM, 500 nM to 700 nM, 500 nM to 650 nM, 500 nM to 600 nM, 500 nM to 550 nM,750 nM to 1000 nM, 750 nM to 900 nM, or 750 nM to 800 nM. [000132] The disclosure also includes antibodies that compete with any of the antibodies described herein for binding to a CD3 protein (e.g., human CD3) and that have an affinity of 100 nM or lower (e.g., 80 nM or lower, 50 nM or lower, 20 nM or lower, 10 nM or lower, 5 nM or lower, 500 pM or lower, 50 pM or lower, or 5 pM or lower). In some embodiments, an anti-CD3 antibody specifically binds a CD3 (e.g., a human CD3) with a binding affinity between 4 x 10-11and 3 x 10-11. [000133] In some embodiments, an anti-CD3 antibody specifically binds a CD3 (e.g., a human CD3) with a binding affinity (e.g., as indicated by EC50 in cell binding measured by a bivalent CD3 antibody) of between 0.1 and 2.5 nM. In some embodiments, an anti-CD3 antibody specifically binds a CD3 (e.g., a human CD3) with a binding affinity (e.g., as indicated by EC50 in cell binding) of between 0.25 and 2.0 nM. In some embodiments, an anti-CD3 antibody specifically binds a CD3 (e.g., a human CD3) with a binding affinity (e.g., as indicated by EC50 in cell binding) of between 0.5 and 1.5 nM. In some embodiments, an anti-CD3 antibody specifically binds a CD3 (e.g., a human CD3) with a binding affinity (e.g., as indicated by EC50 in cell binding) of between 0.75 and 1.0 nM. In some embodiments, an anti-CD3 antibody specifically binds a CD3 (e.g., a human CD3) with a binding affinity (e.g., Docket No. A1361.70024WO00 14108730.1as indicated by EC50 in cell binding) of between 0.75 and 0.9 nM. In some embodiments, it is understood that if the EC50 values was measured using monovalent anti-CD3 antibody, the EC50 value should be lower than the EC50 value measured using bivalent anti-CD3 antibody comprising the same antibody binding domain. [000134] The affinity and binding kinetics of the anti-CD3 antibody can be tested using any suitable method including but not limited to biosensor technology (e.g., OCTET or BIACORE). In some embodiments, an anti-CD3 antibody described herein binds to CD3 with a KD of sub-nanomolar range, single-digit nanomolar range, double-digit nanomolar range, or triple-digit nanomolar range. [000135] Binding affinity (or binding specificity) can be determined by a variety of methods including equilibrium dialysis, equilibrium binding, gel filtration, ELISA, surface plasmon resonance (SPR), florescent activated cell sorting (FACS) or spectroscopy (e.g., using a fluorescence assay). Exemplary conditions for evaluating binding affinity are in HBS-P buffer (10 mM HEPES pH7.4, 150 mM NaCl, 0.005% (v / v) surfactant P20) and PBS buffer (10mM PO4-3, 137mM NaCl, and 2.7mM KCl). These techniques can be used to measure the concentration of bound proteins as a function of target protein concentration. The concentration of bound protein ([[Bound]]) is generally related to the concentration of free target protein ([[Free]]) by the following equation: [[Bound]] = [[Free]] / (Kd+[[Free]]) [000136] It is not always necessary to make an exact determination of KA, though, since sometimes it is sufficient to obtain a quantitative measurement of affinity, e.g., determined using a method such as ELISA or FACS analysis, is proportional to KA, and thus can be used for comparisons, such as determining whether a higher affinity is, e.g., 2-fold higher, to obtain a qualitative measurement of affinity, or to obtain an inference of affinity, e.g., by activity in a functional assay, e.g., an in vitro or in vivo assay. [000137] In some embodiments, an anti-CD3 antibody herein exhibits reduced polyreactivity compared to anti-CD3 antibodies known in the art. Reduced polyreactivity in antibodies refers to a decreased ability to bind to multiple different antigens (e.g., reduced cross- reactivity with an off-target antigen or antigens). Reducing polyreactivity of an antibody minimizes risk of off-target binding or immunogenicity. Polyreactivity can be measured using a baculovirus particle (BVP) enzyme-linked immunosorbent assay (ELISA), a multi- antigen binding ELISA. Lower normalized BVP scores indicate decreased polyreactivity. In some embodiments, an anti-CD3 antibody provided herein has a normalized BVP score of Docket No. A1361.70024WO00 14108730.1between 0.01 and 0.2. In some embodiments, an anti-CD3 antibody provided herein has a normalized BVP score of between 0.05 and 0.15. In some embodiments, an anti-CD3 antibody provided herein has a normalized BVP score of between 0.07 and 0.12. [000138] In some embodiments, an anti-CD3 antibody provided herein exhibits reduced aggregation or self-association propensity. Self-association propensity can be measured using an affinity-capture self-interaction nanoparticle spectroscopy (AC-SINS) assay. Lower normalized AC-SINS values indicate decreased aggregation or self-association propensity. In some embodiments, an anti-CD3 antibody provided herein has a normalized AC-SINS value of between 0.01 and 0.2, 0.01 and 0.195, 0.01 and 0.19, 0.01 and 0.185, 0.01 and 0.18, 0.01 and 0.175, 0.01 and 0.17, 0.01 and 0.165, 0.01 and 0.16, 0.01 and 0.155, 0.01 and 0.15, 0.01 and 0.145, 0.01 and 0.14, 0.01 and 0.135, 0.01 and 0.13, 0.01 and 0.125, 0.01 and 0.12, 0.01 and 0.115, 0.01 and 0.11, 0.01 and 0.105, 0.01 and 0.10, 0.01 and 0.095, 0.01 and 0.09, 0.01 and 0.085, 0.01 and 0.08, 0.01 and 0.075, 0.01 and 0.07, 0.01 and 0.065, 0.01 and 0.06, 0.01 and 0.055, 0.01 and 0.05, 0.01 and 0.045, 0.01 and 0.040, 0.01 and 0.035, 0.01 and 0.03, 0.01 and 0.025, 0.01 and 0.020, 0.01 and 0.15, 0.02 and 0.2, 0.02 and 0.195, 0.02 and 0.19, 0.02 and 0.185, 0.02 and 0.18, 0.02 and 0.175, 0.02 and 0.17, 0.02 and 0.165, 0.02 and 0.16, 0.02 and 0.155, 0.02 and 0.15, 0.02 and 0.145, 0.02 and 0.14, 0.02 and 0.135, 0.02 and 0.13, 0.02 and 0.125, 0.02 and 0.12, 0.02 and 0.115, 0.02 and 0.11, 0.02 and 0.105, 0.02 and 0.10, 0.02 and 0.095, 0.02 and 0.09, 0.02 and 0.085, 0.02 and 0.08, 0.02 and 0.075, 0.02 and 0.07, 0.02 and 0.065, 0.02 and 0.06, 0.02 and 0.055, 0.02 and 0.05, 0.02 and 0.045, 0.02 and 0.040, 0.02 and 0.035, 0.02 and 0.03, 0.02 and 0.025, 0.05 and 0.2, 0.05 and 0.195, 0.05 and 0.19, 0.05 and 0.185, 0.05 and 0.18, 0.05 and 0.175, 0.05 and 0.17, 0.05 and 0.165, 0.05 and 0.16, 0.05 and 0.155, 0.05 and 0.15, 0.05 and 0.145, 0.05 and 0.14, 0.05 and 0.135, 0.05 and 0.13, 0.05 and 0.125, 0.05 and 0.12, 0.05 and 0.115, 0.05 and 0.11, 0.05 and 0.105, 0.05 and 0.10, 0.05 and 0.095, 0.05 and 0.09, 0.05 and 0.085, 0.05 and 0.08, 0.05 and 0.075, 0.05 and 0.07, 0.05 and 0.065, 0.05 and 0.06, 0.05 and 0.055, 0.07 and 0.2, 0.07 and 0.195, 0.07 and 0.19, 0.07 and 0.185, 0.07 and 0.18, 0.07 and 0.175, 0.07 and 0.17, 0.07 and 0.165, 0.07 and 0.16, 0.07 and 0.155, 0.07 and 0.15, 0.07 and 0.145, 0.07 and 0.14, 0.07 and 0.135, 0.07 and 0.13, 0.07 and 0.125, 0.07 and 0.12, 0.07 and 0.115, 0.07 and 0.11, 0.07 and 0.105, 0.07 and 0.10, 0.07 and 0.095, 0.07 and 0.09, 0.07 and 0.085, 0.07 and 0.08, 0.07 and 0.075, 0.10 and 0.2, 0.10 and 0.195, 0.10 and 0.19, 0.10 and 0.185, 0.10 and 0.18, 0.10 and 0.175, 0.10 and 0.17, 0.10 and 0.165, 0.10 and 0.16, 0.10 and 0.155, 0.10 and 0.15, 0.10 and 0.145, 0.10 and 0.14, 0.10 and 0.135, 0.10 and 0.13, 0.10 and 0.125, 0.10 and 0.12, 0.10 and 0.115, 0.10 and 0.11, 0.10 Docket No. A1361.70024WO00 14108730.1and 0.105, 0.12 and 0.2, 0.12 and 0.195, 0.12 and 0.19, 0.12 and 0.185, 0.12 and 0.18, 0.12 and 0.175, 0.12 and 0.17, 0.12 and 0.165, 0.12 and 0.16, 0.12 and 0.155, 0.12 and 0.15, 0.12 and 0.145, 0.12 and 0.14, 0.12 and 0.135, 0.12 and 0.13, 0.12 and 0.125, 0.15 and 0.2, 0.15 and 0.195, 0.15 and 0.19, 0.15 and 0.185, 0.15 and 0.18, 0.15 and 0.175, 0.15 and 0.17, 0.15 and 0.165, 0.15 and 0.16, 0.15 and 0.155, 0.16 and 0.2, 0.16 and 0.195, 0.16 and 0.19, 0.16 and 0.185, 0.16 and 0.18, 0.16 and 0.175, 0.16 and 0.17, 0.16 and 0.165, 0.17 and 0.2, 0.17 and 0.195, 0.17 and 0.19, 0.17 and 0.185, 0.17 and 0.18, 0.17 and 0.175, 0.18 and 0.2, 0.18 and 0.195, 0.18 and 0.19, 0.18 and 0.185, 0.19 and 0.2, 0.19 and 0.195, or 0.195 and 0.2. [000139] In some embodiments, the antibody is a full-length IgG, a Fab fragment, a F(ab’) fragment, a scFv, or a Fv. In some embodiments, the antibody comprises a heavy chain constant region of the isotype IgG1, IgG2, IgG3, or IgG4. [000140] The heavy chain variable domain (VH) and light chain variable domain (VL), CDR sequences, and heavy chain and light chain constant region sequences of non-limiting examples of anti-CD3 antibodies are provided in Table 1. Exemplary amino acid substitutions of an anti-CD3 antibody described herein are set forth in Table 5. Table 1. Examples of anti-CD3 binders (CDRs according to the Kabat definition) Anti-CD3 Binder Sequences SEQ ID NODocket No. A1361.70024WO00 14108730.1LC CDR1SSSTGAVTTSNYAN9Docket No. A1361.70024WO00 14108730.1VLQAVVTQPPSVSGAPGQRVTISCSSSTGAVTTSNYANWVQE 10Table 5. Exemplary anti-CD3 binder amino acid substitutions Anti-CD3 binder Sequences SEQ ID NODocket No. A1361.70024WO00 14108730.1LC CDR3 6Table 6. Examples of anti-CD3 binder framework sequences and exemplary amino acid substitutions Anti-CD3 Binder Sequences SEQ ID NODocket No. A1361.70024WO00 14108730.1VH FW3RFTISRDDSQSTLYLQMNSLKTEDTAVYYCVR86Docket No. A1361.70024WO00 14108730.1X is G, V, or L[000141] In some embodiments, an anti-CD3 antibody of the present disclosure comprises one or more of the HC CDRs (e.g., HC CDR1, HC CDR2, or HC CDR3) amino acid sequences from any one of an anti-CD3 antibody selected from Table 1. In some embodiments, an anti-CD3 antibody of the present disclosure comprise the HC CDR1, HC CDR2, and HC CDR3 as provided for any one of the antibodies elected from Table 1. In some embodiments, the present disclosure provides an antibody that specifically binds CD3 complex, wherein the improvement comprises the HC CDR1, HC CDR2, and HC CDR3 as provided for any one of the antibodies elected from Table 1. In some embodiments, the present disclosure provides an antibody that specifically binds CD3 complex, wherein the improvement comprises one or more of the LC CDRs (e.g., LC CDR1, LC CDR2, or LC CDR3) amino acid sequences from any one of an anti-CD3 antibody selected from Table 1. In some embodiments, the present disclosure provides an antibody that specifically binds CD3 complex, wherein the improvement comprises the LC CDR1, LC CDR2, and LC CDR3 s provided for any one of an anti-CD3 antibody selected from Table 1. In some Docket No. A1361.70024WO00 14108730.1embodiments, the present disclosure provides an antibody that specifically binds CD3 complex, wherein the improvement comprises HC CDR1, HC CDR2, and HC CDR3, LC CDR1, LC CDR2, and LC CDR3 as provided for any one of an anti-CD3 antibody selected from Table 1. [000142] In some embodiments, an anti-CD3 antibody of the present disclosure comprises one or more of the LC CDRs (e.g., LC CDR1, LC CDR2, or LC CDR3) amino acid sequences from any one of an anti-CD3 antibody selected from Table 1. In some embodiments, an anti-CD3 antibody of the present disclosure comprise the LC CDR1, LC CDR2, and LC CDR3s provided for any one of the anti-CD3 antibodies selected from Table 1. In some embodiments, the present disclosure provides an antibody that specifically binds a CD3 complex, wherein the improvement comprises the HC CDR1, HC CDR2, HC CDR3, LC CDR1, LC CDR2, and LC CDR3 as provided for any one of an anti-CD3 antibody selected from Table 1. [000143] In some embodiments, an anti-CD3 antibody of the present disclosure comprises the HC CDR1, HC CDR2, HC CDR3, LC CDR1, LC CDR2, and LC CDR3 as provided for any one of an anti-CD3 antibody selected from Table 1. In some embodiments, antibody heavy and light chain CDR3 domains may play a particularly important role in the binding specificity / affinity of an antibody for an antigen. Accordingly, an anti-CD3 antibody of the disclosure may include at least the heavy and / or light chain CDR3s of any one of an anti-CD3 antibody selected from Table 1. [000144] In some embodiments, according to the Kabat definition system, an anti-CD3 antibody of the present disclosure comprises a HC CDR1 having the amino acid sequence of TYAMX1 (SEQ ID NO: 20), wherein X1 is N or H. In some embodiments, according to the Kabat definition system, an anti-CD3 antibody of the present disclosure comprises a HC CDR2 having an amino acid sequence of RIRSKYNNYATX2YAX3SVKX4 (SEQ ID NO: 21), wherein X2 is Y, E, or A; X3 is D or A; and X4 is G or D. In some embodiments, according to the Kabat definition system, an anti-CD3 antibody of the present disclosure comprises a HC CDR3 of having the amino acid sequence of HGNFGNSYVSX5FAY (SEQ ID NO: 22), wherein X5 is W or Y. [000145] Alternatively or in addition, according to the Kabat definition system, an anti-CD3 antibody of the present disclosure comprises a LC CDR1 having the amino acid sequence of X6SSTGAVTTSNYAN (SEQ ID NO: 23), wherein X6 is R or S. In some embodiments, according to the Kabat definition system, an anti-CD3 antibody of the present disclosure Docket No. A1361.70024WO00 14108730.1comprises a LC CDR2 having the amino acid sequence of SEQ ID NO: 5. In some embodiments, according to the Kabat definition system, an anti-CD3 antibody of the present disclosure comprises a LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000146] In some embodiments, an anti-CD3 antibody of the present disclosure comprises the HC CDR1, HC CDR2, HC CDR3, LC CDR1, LC CDR2, and / or LC CDR3 of the antibody anti-CD3 Ab1. [000147] In some embodiments, an anti-CD3 antibody of the present disclosure comprises the HC CDR1, HC CDR2, HC CDR3, LC CDR1, LC CDR2, and / or LC CDR3 of the antibody anti-CD3 Ab2. [000148] In some embodiments, an anti-CD3 antibody of the present disclosure comprises the HC CDR1, HC CDR2, HC CDR3, LC CDR1, LC CDR2, and / or LC CDR3 of the antibody anti-CD3 Ab3. [000149] In some embodiments, an anti-CD3 antibody of the present disclosure comprises the HC CDR1, HC CDR2, HC CDR3, LC CDR1, LC CDR2, and / or LC CDR3 of the antibody anti-CD3 Ab4. [000150] In some embodiments, an anti-CD3 antibody of the present disclosure comprises the HC CDR1, HC CDR2, HC CDR3, LC CDR1, LC CDR2, and / or LC CDR3 of the antibody anti-CD3 Ab5. [000151] In some embodiments, an anti-CD3 antibody of the present disclosure comprises the HC CDR1, HC CDR2, HC CDR3, LC CDR1, LC CDR2, and / or LC CDR3 of the antibody anti-CD3 Ab6. [000152] In some embodiments, an anti-CD3 antibody of the present disclosure comprises the HC CDR1, HC CDR2, HC CDR3, LC CDR1, LC CDR2, and / or LC CDR3 of the antibody anti-CD3 Ab7. [000153] In some embodiments, an anti-CD3 antibody of the present disclosure comprises the HC CDR1, HC CDR2, HC CDR3, LC CDR1, LC CDR2, and / or LC CDR3 of the antibody anti-CD3 Ab8. [000154] In some embodiments, an anti-CD3 antibody of the present disclosure comprises the HC CDR1, HC CDR2, HC CDR3, LC CDR1, LC CDR2, and / or LC CDR3 of the antibody anti-CD3 Ab9. [000155] In some embodiments, an anti-CD3 antibody of the present disclosure comprises the HC CDR1, HC CDR2, HC CDR3, LC CDR1, LC CDR2, and / or LC CDR3 of the antibody anti-CD3 Ab10. Docket No. A1361.70024WO00 14108730.1[000156] In some embodiments, the isolated anti-CD3 antibody comprises a heavy chain variable region that comprises a heavy chain CDR1 (HC CDR1), a heavy chain CDR2 (HC CDR2), and a heavy chain CDR3 (HC CDR3). [000157] Also within the scope of the present disclosure are functional variants of any of the exemplary anti-CD3 antibodies as disclosed herein. A functional variant may contain one or more amino acid residue variations in the VH and / or VL, or in one or more of the HC CDRs and / or one or more of the LC CDRs as relative to the reference antibody, while retaining substantially similar binding and biological activities (e.g., substantially similar binding affinity, binding specificity, inhibitory activity, anti-inflammatory activity, or a combination thereof) as the reference antibody. [000158] In some embodiments, an anti-CD3 antibody of the disclosure have one or more CDRs (e.g., HC CDR or LC CDR) sequences substantially similar to any of the HC CDR1, HC CDR2, HC CDR3, LC CDR1, LC CDR2, and / or LC CDR3 sequences from one of an anti-CD3 antibody selected from Table 1. In some embodiments, the position of one or more CDRs along the VH (e.g., HC CDR1, HC CDR2, or HC CDR3) and / or VL (e.g., LC CDR1, LC CDR2, or LC CDR3) region of an antibody described herein can vary by one, two, three, four, five, or six amino acid positions so long as immunospecific binding to CD3 (e.g., human CD3) is maintained (e.g., substantially maintained, for example, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95% of the binding of the original antibody from which it is derived). For example, in some embodiments, the position defining a CDR of any antibody described herein can vary by shifting the N-terminal and / or C- terminal boundary of the CDR by one, two, three, four, five, or six amino acids, relative to the CDR position of any one of the antibodies described herein, so long as immunospecific binding to CD3 (e.g., human CD3) is maintained (e.g., substantially maintained, for example, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95% of the binding of the original antibody from which it is derived). In another embodiment, the length of one or more CDRs along the VH (e.g., HC CDR1, HC CDR2, or HC CDR3) and / or VL (e.g., LC CDR1, LC CDR2, or LC CDR3) region of an antibody described herein can vary (e.g., be shorter or longer) by one, two, three, four, five, or more amino acids, so long as immunospecific binding to CD3 (e.g., human CD3) is maintained (e.g., substantially maintained, for example, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95% of the binding of the original antibody from which it is derived). Docket No. A1361.70024WO00 14108730.1[000159] Accordingly, in some embodiments, a HC CDR1, HC CDR2, HC CDR3, LC CDR1, LC CDR2, and / or LC CDR3 described herein may be one, two, three, four, five or more amino acids shorter than one or more of the CDRs described herein (e.g., CDRS from an anti-CD3 antibody selected from Table 1) so long as immunospecific binding to CD3 (e.g., human CD3) is maintained (e.g., substantially maintained, for example, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95% relative to the binding of the original antibody from which it is derived). In some embodiments, a HC CDR1, HC CDR2, HC CDR3, LC CDR1, LC CDR2, and / or LC CDR3 described herein may be one, two, three, four, five or more amino acids longer than one or more of the CDRs described herein (e.g., CDRS from an anti-CD3 antibody selected from Table 1) so long as immunospecific binding to CD3 (e.g., human CD3) is maintained (e.g., substantially maintained, for example, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95% relative to the binding of the original antibody from which it is derived). In some embodiments, the amino portion of a HC CDR1, HC CDR2, HC CDR3, LC CDR1, LC CDR2, and / or LC CDR3 described herein can be extended by one, two, three, four, five or more amino acids compared to one or more of the CDRs described herein (e.g., CDRS from an anti-CD3 antibody selected from Table 1) so long as immunospecific binding to CD3 (e.g., human CD3) is maintained (e.g., substantially maintained, for example, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95% relative to the binding of the original antibody from which it is derived). In some embodiments, the carboxy portion of a HC CDR1, HC CDR2, HC CDR3, LC CDR1, LC CDR2, and / or LC CDR3 described herein can be extended by one, two, three, four, five or more amino acids compared to one or more of the CDRs described herein (e.g., CDRS from an anti-CD3 antibody selected from Table 1) so long as immunospecific binding to CD3 (e.g., human CD3) is maintained (e.g., substantially maintained, for example, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95% relative to the binding of the original antibody from which it is derived). In some embodiments, the amino portion of a HC CDR1, HC CDR2, HC CDR3, LC CDR1, LC CDR2, and / or LC CDR3 described herein can be shortened by one, two, three, four, five or more amino acids compared to one or more of the CDRs described herein (e.g., CDRS from any of the anti- CD3 antibodies selected from Table 1) so long as immunospecific binding to CD3 (e.g., human CD3) is maintained (e.g., substantially maintained, for example, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95% relative to the binding of the original antibody from which it is derived). In some embodiments, the carboxy Docket No. A1361.70024WO00 14108730.1portion of a HC CDR1, HC CDR2, HC CDR3, LC CDR1, LC CDR2, and / or LC CDR3 described herein can be shortened by one, two, three, four, five or more amino acids compared to one or more of the CDRs described herein (e.g., CDRS from an anti-CD3 antibody selected from Table 1) so long as immunospecific binding to CD3 (e.g., human CD3) is maintained (e.g., substantially maintained, for example, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95% relative to the binding of the original antibody from which it is derived). Any method can be used to ascertain whether immunospecific binding to CD3 (e.g., human CD3) is maintained, for example, using binding assays and conditions described in the art. [000160] In some examples, an anti-CD3 antibody of the disclosure has one or more CDR (e.g., HC CDR or LC CDR) sequences substantially similar to any one of an anti-CD3 antibody selected from Table 1. For example, the antibodies may include one or more CDR sequence(s) from an anti-CD3 antibody selected from Table 1 containing up to 5, 4, 3, 2, or 1 amino acid residue variations as compared to the corresponding CDR region in any one of the CDRs provided herein (e.g., CDRs from an anti-CD3 antibody selected from Table 1) so long as immunospecific binding to CD3 (e.g., human CD3) is maintained (e.g., substantially maintained, for example, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95% relative to the binding of the original antibody from which it is derived). In some embodiments, any of the amino acid variations in any of the CDRs provided herein may be conservative variations. Conservative variations can be introduced into the CDRs at positions where the residues are not likely to be involved in interacting with a CD3 protein (e.g., a human CD3 protein), for example, as determined based on a crystal structure. Some aspects of the disclosure provide anti-CD3 antibodies that comprise one or more of the heavy chain variable (VH) and / or light chain variable (VL) domains provided herein. In some embodiments, any of the VH domains provided herein include one or more of the HC CDR sequences (e.g., HC CDR1, HC CDR2, and HC CDR3) provided herein, for example, any of the CDR-H sequences provided in any one of the anti-CD3 selected from Table 1. In some embodiments, any of the VL domains provided herein include one or more of the CDR-L sequences (e.g., LC CDR1, LC CDR2, and LC CDR3) provided herein, for example, any of the LC CDR sequences provided in any one of an anti-CD3 antibody selected from Table 1. [000161] In some embodiments, an anti-CD3 antibody of the disclosure includes any antibody that includes a heavy chain variable domain and / or a light chain variable domain of any one of an anti-CD3 antibody selected from Table 1, and variants thereof. In some Docket No. A1361.70024WO00 14108730.1embodiments, anti-CD3 antibodies of the disclosure include any antibody that includes the heavy chain variable and light chain variable pairs of any anti-CD3 antibodies selected from Table 1. [000162] Aspects of the disclosure provide anti-CD3 antibodies having a heavy chain variable (VH) and / or a light chain variable (VL) domain amino acid sequence homologous to any of those described herein. In some embodiments, the anti-CD3 antibody comprises a heavy chain variable sequence or a light chain variable sequence that is at least 75% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the heavy chain variable sequence and / or any light chain variable sequence of any one of an anti-CD3 antibody selected from Table 1. In some embodiments, the homologous heavy chain variable and / or a light chain variable amino acid sequences do not vary within any of the CDR sequences provided herein. For example, in some embodiments, the degree of sequence variation (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) may occur within a heavy chain variable and / or a light chain variable sequence excluding any of the CDR sequences provided herein. In some embodiments, an anti-CD3 antibody provided herein comprise a heavy chain variable sequence and a light chain variable sequence that comprises a framework sequence that is at least 75%, (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) to the framework sequence of any anti-CD3 antibodies selected from Table 1. [000163] In some embodiments, an anti-CD3 antibody of the present disclosure comprises one or more of the framework (FW) amino acid sequences of a heavy chain variable region (VH) (e.g., VH FW1, VH FW2, VH FW3, or VH FW4) from any one of the framework regions selected from Table 6. In some embodiments, an anti-CD3 antibody of the present disclosure comprises one or more FW amino acid sequences of a light chain variable region (VL) (e.g., VL FW1, VL FW2, VL FW3, or VL FW4) from any one of the framework regions selected from Table 6. [000164] In some embodiments, the present disclosure provides an antibody that specifically binds CD3, wherein the improvement comprises one or more of the VH FWs (e.g., VH FW1, VH FW2, VH FW3, or VH FW4) amino acid sequences from any one of framework regions selected from Table 6. In some embodiments, the present disclosure provides an antibody that Docket No. A1361.70024WO00 14108730.1specifically binds CD3, wherein the improvement comprises the VH FW1, VH FW2, VH FW3, or VH FW4 as provided for any one of the antibodies elected from Table 6. Alternatively or in addition, in some embodiments, the present disclosure provides an antibody that specifically binds CD3, wherein the improvement comprises one or more of the VL FWs (e.g., VL FW1, VL FW2, VL FW3, or VL FW4) amino acid sequences from any one of the framework regions selected from Table 6. In some embodiments, the present disclosure provides an antibody that specifically binds CD3, wherein the improvement comprises the VL FW1, VL FW2, VL FW3, or VL FW4 provided for any one of an anti-CD3 antibodies selected from Table 6. In some embodiments, the present disclosure provides an antibody that specifically binds CD3, wherein the improvement comprises VH FW1, VH FW2, VH FW3, VH FW4, and VL FW1, VL FW2, VL FW3, and VL FW4 as provided for any one of an anti-CD3 antibodies selected from Table 6. [000165] In some embodiments, an anti-CD3 antibody of the present disclosure comprises the VH FW1, VH FW2, VH FW3, VH FW4, VL FW1, VL FW2, VL FW3, and VL FW4 as provided for any one of an anti-CD3 antibody selected from Table 6. Alternative or in addition, in some embodiments, an anti-CD3 antibody of the present disclosure comprises one or more of the VL FWs (e.g., VL FW1, VL FW2, VL FW3, or VL FW4) amino acid sequences from any one of an anti-CD3 antibodies selected from Table 6. In some embodiments, an anti-CD3 antibody of the present disclosure comprises the VL FW1, VL FW2, VL FW3, and VL FW4s provided for any one of the anti-CD3 antibodies selected from Table 6. In some embodiments, the present disclosure provides an antibody that specifically binds CD3, wherein the improvement comprises the VH FW1, VH FW2, VH FW3, VH FW4, VL FW1, VL FW2, VL FW3, and VL FW4 as provided for any one of an anti-CD3 antibodies selected from Table 6. In some embodiments, antibody heavy and light chain framework regions may play a particularly important role in the binding of an antibody to an antigen. Accordingly, an anti-CD3 antibody of the disclosure may include at least the heavy and / or light chain framework regions of any one of an anti-CD3 antibody selected from Table 6. [000166] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH FW1 having the amino acid sequence of EVQLVESGGGLVQPGGSLX7LSCAASGFTFX8(SEQ ID NO: 112), wherein X7is R or K and X8 is S or N. In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH FW2 having an amino acid sequence of WVRQAX9GKGLEWVX10 (SEQ Docket No. A1361.70024WO00 14108730.1ID NO: 113), wherein X9is S or P and X10is G or S. In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH FW3 having an amino acid sequence of RFTISRDDSX11X12X13X14YLQMNX15LX16X17EDTAVYYCVR (SEQ ID NO: 114), wherein X11is Q or K; X12is N or S; X13is S, I, or I; X14is L or A; X15is N or S; X16is K or R; and X17 is A, V or T. In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH FW4 having an amino acid sequence of WGQGTLVTVSS (SEQ ID NO: 44). [000167] Alternatively or in addition, in some embodiments, an anti-CD3 antibody of the present disclosure comprises a VL FW1 having the amino acid sequence of X18X19X20X21TQX22PX23X24X25X26X27X28X29X30X31X32X33X34X35X36C (SEQ ID NO: 115), where X18is D or Q; X19is A or I; X20is V or Q; X21is M or V; X22is P or S; X23is S or D; X24 is V or S; X25 is S or L; X26 is G, S, or A; X27 is V or A; X28 is S or P; X29 is G, V, or L; X30 is G or Q; X31 is D, R, or E; X32 is V or R; X33 is A, T, or V; X34 is I or T; X35 is I or S; and X36is T, N or absent. In some embodiments, an anti-CD3 antibody provided herein comprises a VL FW2 having the amino acid sequence of WVQX37X38PGX39X40PKX41LIG (SEQ ID NO: 116), wherein X37 is E or Q; X38 is K or L; X39 is Q, T, or K; X40 is A or P; and X41is G or A. In some embodiments, an anti-CD3 antibody provided herein comprises a VL FW3 having the amino acid sequence of GVPX42RFSGSLX43GDX44AX45LX46IX47X48LQX49EDX50AX51YX52C (SEQ ID NO: 117), wherein X42is S or D; X43is I or S; X44is K, S, or D; X45is T or S; X46is A or T; X47is S or T; X48is G or S; X49is P, S, or A; X50is F, E, or V; X51is T, D, or V; and X52is F or Y. In some embodiments, an anti-CD3 antibody provided herein comprises a VL FW4 having the amino acid sequence of FGX54GTKX55X56X57X58 (SEQ ID NO: 118), wherein X54 is G or Q; X55is V or L; X56is E or T; X57is I or N; and X58is L or K. [000168] In some embodiments, an anti-CD3 antibody of the present disclosure comprises the VH FW1, VH FW2, VH FW3, VH FW4, VL FW1, VL FW2, VL FW3, and / or VL FW4of the antibody anti-CD3 Ab1. In some embodiments, an anti-CD3 antibody of the present disclosure comprises the VH FW1, VH FW2, VH FW3, VH FW4, VL FW1, VL FW2, VL FW3, and / or VL FW4 comprising the amino acid sequence as set forth in SEQ ID NOs: 41, 57, 43, 44, 52, 53, 54,and 48, respectively. [000169] In some embodiments, an anti-CD3 antibody of the present disclosure comprises the VH FW1, VH FW2, VH FW3, VH FW4, VL FW1, VL FW2, VL FW3, and / or VL FW4 of the antibody anti-CD3 Ab2. In some embodiments, an anti-CD3 antibody of the present Docket No. A1361.70024WO00 14108730.1disclosure comprises the VH FW1, VH FW2, VH FW3, VH FW4, VL FW1, VL FW2, VL FW3, and / or VL FW4 comprising the amino acid sequence set forth in SEQ ID NOs: 49, 50, 51, 44, 52, 53, 54, and 55, respectively. [000170] In some embodiments, an anti-CD3 antibody of the present disclosure comprises the VH FW1, VH FW2, VH FW3, VH FW4, VL FW1, VL FW2, VL FW3, and / or VL FW4 of the antibody anti-CD3 Ab3. In some embodiments, an anti-CD3 antibody of the present disclosure comprises the VH FW1, VH FW2, VH FW3, VH FW4, VL FW1, VL FW2, VL FW3, and / or VL FW4 comprising the amino acid sequence set forth in SEQ ID NOs: 56, 57, 58, 44, 59, 60, 61, and 62, respectively. [000171] In some embodiments, an anti-CD3 antibody of the present disclosure comprises the VH FW1, VH FW2, VH FW3, VH FW4, VL FW1, VL FW2, VL FW3, and / or VL FW4 of the antibody anti-CD3 Ab4. In some embodiments, an anti-CD3 antibody of the present disclosure comprises the VH FW1, VH FW2, VH FW3, VH FW4, VL FW1, VL FW2, VL FW3, and / or VL FW4 comprising the amino acid sequence set forth in SEQ ID NOs: 63, 64, 65, 44, 66, 67, 68, and 69, respectively. [000172] In some embodiments, an anti-CD3 antibody of the present disclosure comprises the VH FW1, VH FW2, VH FW3, VH FW4, VL FW1, VL FW2, VL FW3, and / or VL FW4 of the antibody anti-CD3 Ab5. In some embodiments, an anti-CD3 antibody of the present disclosure comprises the VH FW1, VH FW2, VH FW3, VH FW4, VL FW1, VL FW2, VL FW3, and / or VL FW4 comprising the amino acid sequence set forth in SEQ ID NOs: 70, 71, 72, 44, 73, 74, 75, and 76, respectively. [000173] In some embodiments, an anti-CD3 antibody of the present disclosure comprises the VH FW1, VH FW2, VH FW3, VH FW4, VL FW1, VL FW2, VL FW3, and / or VL FW4 of the antibody anti-CD3 Ab6. In some embodiments, an anti-CD3 antibody of the present disclosure comprises the VH FW1, VH FW2, VH FW3, VH FW4, VL FW1, VL FW2, VL FW3, and / or VL FW4 comprising the amino acid sequence set forth in SEQ ID NOs: 77, 78, 79, 44, 80, 81, 82, and 83, respectively. [000174] In some embodiments, an anti-CD3 antibody of the present disclosure comprises the VH FW1, VH FW2, VH FW3, VH FW4, VL FW1, VL FW2, VL FW3, and / or VL FW4 of the antibody anti-CD3 Ab7. In some embodiments, an anti-CD3 antibody of the present disclosure comprises the VH FW1, VH FW2, VH FW3, VH FW4, VL FW1, VL FW2, VL FW3, and / or VL FW4 comprising the amino acid sequence set forth in SEQ ID NOs: 84, 85, 86, 44, 87, 88, 89, and 90, respectively. Docket No. A1361.70024WO00 14108730.1[000175] In some embodiments, an anti-CD3 antibody of the present disclosure comprises the VH FW1, VH FW2, VH FW3, VH FW4, VL FW1, VL FW2, VL FW3, and / or VL FW4 of the antibody anti-CD3 Ab8. In some embodiments, an anti-CD3 antibody of the present disclosure comprises the VH FW1, VH FW2, VH FW3, VH FW4, VL FW1, VL FW2, VL FW3, and / or VL FW4 comprising the amino acid sequence set forth in SEQ ID NOs: 91, 92, 93, 44, 94, 95, 96, and 97, respectively. [000176] In some embodiments, an anti-CD3 antibody of the present disclosure comprises the VH FW1, VH FW2, VH FW3, VH FW4, VL FW1, VL FW2, VL FW3, and / or VL FW4 of the antibody anti-CD3 Ab9. In some embodiments, an anti-CD3 antibody of the present disclosure comprises the VH FW1, VH FW2, VH FW3, VH FW4, VL FW1, VL FW2, VL FW3, and / or VL FW4 comprising the amino acid sequence set forth in SEQ ID NOs: 98, 99, 100, 44, 101, 102, 103, and 104, respectively. [000177] In some embodiments, an anti-CD3 antibody of the present disclosure comprises the VH FW1, VH FW2, VH FW3, VH FW4, VL FW1, VL FW2, VL FW3, and / or VL FW4 of the antibody anti-CD3 Ab10. In some embodiments, an anti-CD3 antibody of the present disclosure comprises the VH FW1, VH FW2, VH FW3, VH FW4, VL FW1, VL FW2, VL FW3, and / or VL FW4 comprising the amino acid sequence set forth in SEQ ID NOs: 105, 106, 107, 44, 108, 109, 110, and 111, respectively. [000178] In some embodiments, an anti-CD3 antibody of the present disclosure is a humanized antibody (e.g., a humanized variant containing one or more CDRs of Table 1). In some embodiments, the anti-CD3 antibody of the present disclosure comprises a HC CDR1, a HC CDR2, a HC CDR3, a LC CDR1, a LC CDR2, and a LC CDR3 that are the same as the HC CDR1, HC CDR2, HC CDR3, LC CDR1, LC CDR2, and LC CDR3 shown in Table 1, and comprises a humanized heavy chain variable region and / or a humanized light chain variable region. [000179] In some embodiments, an anti-CD3 antibody of the present disclosure is a humanized antibody comprising a VH containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VH of an anti-CD3 antibody listed in Table 1. Alternatively or in addition, the anti-CD3 antibody of the present disclosure is a humanized antibody comprising a VL containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VL of any one of an anti-CD3 antibody listed in Table 1. Docket No. A1361.70024WO00 14108730.1[000180] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, HC CDR2 and HC CDR3 of a heavy chain variable domain having the amino acid sequence of SEQ ID NO: 7. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, LC CDR2 and LC CDR3 of a light chain variable domain having the amino acid sequence of SEQ ID NO: 10. [000181] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, HC CDR2 and HC CDR3 of a heavy chain variable domain having the amino acid sequence of SEQ ID NO: 7. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, LC CDR2 and LC CDR3 of a light chain variable domain having the amino acid sequence of SEQ ID NO: 10. [000182] In some embodiments, according to the Kabat definition, an anti-CD3 antibody of the present disclosure comprises a HC CDR3 having the amino acid sequence of SEQ ID NO: 3. In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1 having the amino acid sequence of SEQ ID NO: 1, a HC CDR2 having the amino acid sequence of SEQ ID NO: 2, a HC CDR3 having the amino acid sequence of SEQ ID NO: 3, a LC CDR1 having the amino acid sequence of SEQ ID NO: 9, a LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000183] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, a HC CDR2, and a HC CDR3, which collectively contains no more than 5 amino acid variations (e.g., no more than 5, 4, 3, 2, or 1 amino acid variation) as compared with the HC CDR1 having the amino acid sequence of SEQ ID NO: 1, HC CDR2 having the amino acid sequence of SEQ ID NO: 2, and HC CDR3 having the amino acid sequence of SEQ ID NO: 3. “Collectively,” as used anywhere in the present disclosure, means that the total number of amino acid variations in all of the three heavy chain CDRs is within the defined range. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, a LC CDR2, and a LC CDR3, which collectively contains no more than 5 amino acid variations (e.g., no more than 5, 4, 3, 2 or 1 amino acid variation) as compared with the LC CDR1 having the amino acid sequence of SEQ ID NO: 9, LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000184] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, a HC CDR2, and a HC CDR3 that collectively are at least 80% (e.g., at least 80%, Docket No. A1361.70024WO00 14108730.1at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the HC CDR1 having the amino acid sequence of SEQ ID NO: 1, HC CDR2 having the amino acid sequence of SEQ ID NO: 2, and HC CDR3 having the amino acid sequence of SEQ ID NO: 3. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, a LC CDR2, and a LC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the to the LC CDR1 having the amino acid sequence of SEQ ID NO: 9, LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000185] In some embodiments, an anti-CD3 antibody of the present disclosure comprises: a HC CDR1 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR1 having the amino acid sequence of SEQ ID NO: 1; a HC CDR2 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR2 having the amino acid sequence of SEQ ID NO: 2; and / or a HC CDR3 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR3 having the amino acid sequence of SEQ ID NO: 3. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises: a LC CDR1 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR1 having the amino acid sequence of SEQ ID NO: 9; a LC CDR2 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR2 having the amino acid sequence of SEQ ID NO: 5; and / or a LC CDR3 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000186] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH comprising the amino acid sequence of SEQ ID NO: 7. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a VL comprising the amino acid sequence of SEQ ID NO: 10. [000187] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the Docket No. A1361.70024WO00 14108730.1VH as set forth in SEQ ID NO: 7. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a VL containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VL as set forth in SEQ ID NO: 10. In some embodiments, the number of amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) may occur within a VH of SEQ ID NO: 7 and / or a VL of SEQ ID NO: 10 excluding any of the CDR sequences therein. In some embodiments, an anti-CD3 antibodies provided herein comprise a heavy chain variable sequence that comprises a framework sequence that that contains no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation to the framework sequence of a VH of SEQ ID NO: 7, and / or a light chain variable sequence that comprises a framework sequence that that contains no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation to the framework sequence of a VL of SEQ ID NO: 10. [000188] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VH as set forth in SEQ ID NO: 7. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a VL comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VL as set forth in SEQ ID NO: 10. In some embodiments, the degree of sequence variation (e e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) may occur within a VH of SEQ ID NO: 7, and / or a VL of SEQ ID NO: 10 excluding any of the CDR sequences therein. In some embodiments, an anti-CD3 antibody provided herein comprise a heavy chain variable sequence that is at least 75%, (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the framework sequence of a VH of SEQ ID NO: 7, and / or a light chain variable sequence that comprises a framework sequence that is at least 75%, (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least Docket No. A1361.70024WO00 14108730.193%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the framework sequence of a VL of SEQ ID NO: 10. [000189] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, HC CDR2 and HC CDR3 of a heavy chain variable domain having the amino acid sequence of SEQ ID NO: 14. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, LC CDR2 and LC CDR3 of a light chain variable domain having the amino acid sequence of SEQ ID NO: 10. [000190] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, HC CDR2 and HC CDR3 of a heavy chain variable domain having the amino acid sequence of SEQ ID NO: 14. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, LC CDR2 and LC CDR3 of a light chain variable domain having the amino acid sequence of SEQ ID NO: 10. [000191] In some embodiments, according to the Kabat definition, an anti-CD3 antibody of the present disclosure comprises a HC CDR3 having the amino acid sequence of SEQ ID NO: 13. In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1 having the amino acid sequence of SEQ ID NO: 11, a HC CDR2 having the amino acid sequence of SEQ ID NO: 12, a HC CDR3 having the amino acid sequence of SEQ ID NO: 13, a LC CDR1 having the amino acid sequence of SEQ ID NO: 9, a LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000192] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, a HC CDR2, and a HC CDR3, which collectively contains no more than 5 amino acid variations (e.g., no more than 5, 4, 3, 2, or 1 amino acid variation) as compared with the HC CDR1 having the amino acid sequence of SEQ ID NO: 11, HC CDR2 having the amino acid sequence of SEQ ID NO: 12, and HC CDR3 having the amino acid sequence of SEQ ID NO: 13. “Collectively,” as used anywhere in the present disclosure, means that the total number of amino acid variations in all of the three heavy chain CDRs is within the defined range. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, a LC CDR2, and a LC CDR3, which collectively contains no more than 5 amino acid variations (e.g., no more than 5, 4, 3, 2 or 1 amino acid variation) as compared with the LC CDR1 having the amino acid sequence of SEQ ID NO: 9, LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6. Docket No. A1361.70024WO00 14108730.1[000193] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, a HC CDR2, and a HC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the HC CDR1 having the amino acid sequence of SEQ ID NO: 11, HC CDR2 having the amino acid sequence of SEQ ID NO: 12, and HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, a LC CDR2, and a LC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the to the LC CDR1 having the amino acid sequence of SEQ ID NO: 9, LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000194] In some embodiments, an anti-CD3 antibody of the present disclosure comprises: a HC CDR1 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR1 having the amino acid sequence of SEQ ID NO: 11; a HC CDR2 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR2 having the amino acid sequence of SEQ ID NO: 12; and / or a HC CDR3 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises: a LC CDR1 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR1 having the amino acid sequence of SEQ ID NO: 9; a LC CDR2 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR2 having the amino acid sequence of SEQ ID NO: 5; and / or a LC CDR3 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000195] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH comprising the amino acid sequence of SEQ ID NO: 14. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a VL comprising the amino acid sequence of SEQ ID NO: 10. Docket No. A1361.70024WO00 14108730.1[000196] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VH as set forth in SEQ ID NO: 14. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a VL containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VL as set forth in SEQ ID NO: 10. In some embodiments, the number of amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) may occur within a VH of SEQ ID NO: 14 and / or a VL of SEQ ID NO: 10 excluding any of the CDR sequences therein. In some embodiments, an anti-CD3 antibodies provided herein comprise a heavy chain variable sequence that comprises a framework sequence that that contains no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation to the framework sequence of a VH of SEQ ID NO: 14, and / or a light chain variable sequence that comprises a framework sequence that that contains no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation to the framework sequence of a VL of SEQ ID NO: 10. [000197] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VH as set forth in SEQ ID NO: 14. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a VL comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VL as set forth in SEQ ID NO: 10. In some embodiments, the degree of sequence variation (e e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) may occur within a VH of SEQ ID NO: 14, and / or a VL of SEQ ID NO: 10 excluding any of the CDR sequences therein. In some embodiments, an anti-CD3 antibody provided herein comprise a heavy chain variable sequence that is at least 75%, (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the framework sequence of a VH of SEQ ID Docket No. A1361.70024WO00 14108730.1NO: 14, and / or a light chain variable sequence that comprises a framework sequence that is at least 75%, (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the framework sequence of a VL of SEQ ID NO: 10. [000198] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, HC CDR2 and HC CDR3 of a heavy chain variable domain having the amino acid sequence of SEQ ID NO: 16. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, LC CDR2 and LC CDR3 of a light chain variable domain having the amino acid sequence of SEQ ID NO: 10. [000199] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, HC CDR2 and HC CDR3 of a heavy chain variable domain having the amino acid sequence of SEQ ID NO: 16. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, LC CDR2 and LC CDR3 of a light chain variable domain having the amino acid sequence of SEQ ID NO: 10. [000200] In some embodiments, according to the Kabat definition, an anti-CD3 antibody of the present disclosure comprises a HC CDR3 having the amino acid sequence of SEQ ID NO: 13. In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1 having the amino acid sequence of SEQ ID NO: 1, a HC CDR2 having the amino acid sequence of SEQ ID NO: 15, a HC CDR3 having the amino acid sequence of SEQ ID NO: 13, a LC CDR1 having the amino acid sequence of SEQ ID NO: 9, a LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000201] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, a HC CDR2, and a HC CDR3, which collectively contains no more than 5 amino acid variations (e.g., no more than 5, 4, 3, 2, or 1 amino acid variation) as compared with the HC CDR1 having the amino acid sequence of SEQ ID NO: 1, HC CDR2 having the amino acid sequence of SEQ ID NO: 15, and HC CDR3 having the amino acid sequence of SEQ ID NO: 13. “Collectively,” as used anywhere in the present disclosure, means that the total number of amino acid variations in all of the three heavy chain CDRs is within the defined range. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, a LC CDR2, and a LC CDR3, which collectively contains no more than 5 amino acid variations (e.g., no more than 5, 4, 3, 2 or 1 amino acid variation) as compared with the LC CDR1 having the amino acid sequence of SEQ ID NO: 9, LC CDR2 Docket No. A1361.70024WO00 14108730.1having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000202] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, a HC CDR2, and a HC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the HC CDR1 having the amino acid sequence of SEQ ID NO: 1, HC CDR2 having the amino acid sequence of SEQ ID NO: 15, and HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, a LC CDR2, and a LC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the to the LC CDR1 having the amino acid sequence of SEQ ID NO: 9, LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000203] In some embodiments, an anti-CD3 antibody of the present disclosure comprises: a HC CDR1 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR1 having the amino acid sequence of SEQ ID NO: 1; a HC CDR2 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR2 having the amino acid sequence of SEQ ID NO: 15; and / or a HC CDR3 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises: a LC CDR1 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR1 having the amino acid sequence of SEQ ID NO: 9; a LC CDR2 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR2 having the amino acid sequence of SEQ ID NO: 5; and / or a LC CDR3 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000204] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH comprising the amino acid sequence of SEQ ID NO: 16. Alternatively or in addition, the Docket No. A1361.70024WO00 14108730.1anti-CD3 antibody of the present disclosure comprises a VL comprising the amino acid sequence of SEQ ID NO: 10. [000205] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VH as set forth in SEQ ID NO: 16. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a VL containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VL as set forth in SEQ ID NO: 10. In some embodiments, the number of amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) may occur within a VH of SEQ ID NO: 16 and / or a VL of SEQ ID NO: 10 excluding any of the CDR sequences therein. In some embodiments, an anti-CD3 antibodies provided herein comprise a heavy chain variable sequence that comprises a framework sequence that that contains no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation to the framework sequence of a VH of SEQ ID NO: 16, and / or a light chain variable sequence that comprises a framework sequence that that contains no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation to the framework sequence of a VL of SEQ ID NO: 10. [000206] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VH as set forth in SEQ ID NO: 16. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a VL comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VL as set forth in SEQ ID NO: 10. In some embodiments, the degree of sequence variation (e e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) may occur within a VH of SEQ ID NO: 16, and / or a VL of SEQ ID NO: 10 excluding any of the CDR sequences therein. In some embodiments, an anti-CD3 antibody provided herein comprise a heavy chain variable sequence that is at least 75%, (e.g., at least 80%, at least 85%, at least 90%, at Docket No. A1361.70024WO00 14108730.1least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the framework sequence of a VH of SEQ ID NO: 16, and / or a light chain variable sequence that comprises a framework sequence that is at least 75%, (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the framework sequence of a VL of SEQ ID NO: 10. [000207] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, HC CDR2 and HC CDR3 of a heavy chain variable domain having the amino acid sequence of SEQ ID NO: 18. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, LC CDR2 and LC CDR3 of a light chain variable domain having the amino acid sequence of SEQ ID NO: 8. [000208] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, HC CDR2 and HC CDR3 of a heavy chain variable domain having the amino acid sequence of SEQ ID NO: 18. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, LC CDR2 and LC CDR3 of a light chain variable domain having the amino acid sequence of SEQ ID NO: 8. [000209] In some embodiments, according to the Kabat definition, an anti-CD3 antibody of the present disclosure comprises a HC CDR3 having the amino acid sequence of SEQ ID NO: 13. In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1 having the amino acid sequence of SEQ ID NO: 1, a HC CDR2 having the amino acid sequence of SEQ ID NO: 17, a HC CDR3 having the amino acid sequence of SEQ ID NO: 13, a LC CDR1 having the amino acid sequence of SEQ ID NO: 4, a LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000210] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, a HC CDR2, and a HC CDR3, which collectively contains no more than 5 amino acid variations (e.g., no more than 5, 4, 3, 2, or 1 amino acid variation) as compared with the HC CDR1 having the amino acid sequence of SEQ ID NO: 1, HC CDR2 having the amino acid sequence of SEQ ID NO: 17, and HC CDR3 having the amino acid sequence of SEQ ID NO: 13. “Collectively,” as used anywhere in the present disclosure, means that the total number of amino acid variations in all of the three heavy chain CDRs is within the defined range. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, a LC CDR2, and a LC CDR3, which collectively contains no more Docket No. A1361.70024WO00 14108730.1than 5 amino acid variations (e.g., no more than 5, 4, 3, 2 or 1 amino acid variation) as compared with the LC CDR1 having the amino acid sequence of SEQ ID NO: 4, LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000211] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, a HC CDR2, and a HC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the HC CDR1 having the amino acid sequence of SEQ ID NO: 1, HC CDR2 having the amino acid sequence of SEQ ID NO: 17, and HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, a LC CDR2, and a LC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the to the LC CDR1 having the amino acid sequence of SEQ ID NO: 4, LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000212] In some embodiments, an anti-CD3 antibody of the present disclosure comprises: a HC CDR1 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR1 having the amino acid sequence of SEQ ID NO: 1; a HC CDR2 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR2 having the amino acid sequence of SEQ ID NO: 17; and / or a HC CDR3 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises: a LC CDR1 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR1 having the amino acid sequence of SEQ ID NO: 4; a LC CDR2 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR2 having the amino acid sequence of SEQ ID NO: 5; and / or a LC CDR3 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR3 having the amino acid sequence of SEQ ID NO: 6. Docket No. A1361.70024WO00 14108730.1[000213] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH comprising the amino acid sequence of SEQ ID NO: 18. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a VL comprising the amino acid sequence of SEQ ID NO: 8. [000214] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VH as set forth in SEQ ID NO: 18. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a VL containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VL as set forth in SEQ ID NO: 8. In some embodiments, the number of amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) may occur within a VH of SEQ ID NO: 18 and / or a VL of SEQ ID NO: 8 excluding any of the CDR sequences therein. In some embodiments, an anti-CD3 antibodies provided herein comprise a heavy chain variable sequence that comprises a framework sequence that that contains no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation to the framework sequence of a VH of SEQ ID NO: 18, and / or a light chain variable sequence that comprises a framework sequence that that contains no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation to the framework sequence of a VL of SEQ ID NO: 8. [000215] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VH as set forth in SEQ ID NO: 18. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a VL comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VL as set forth in SEQ ID NO: 8. In some embodiments, the degree of sequence variation (e e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) may occur within a VH of SEQ ID NO: 18, and / or a VL of SEQ ID NO: 8 excluding any of the CDR sequences Docket No. A1361.70024WO00 14108730.1therein. In some embodiments, an anti-CD3 antibody provided herein comprise a heavy chain variable sequence that is at least 75%, (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the framework sequence of a VH of SEQ ID NO: 18, and / or a light chain variable sequence that comprises a framework sequence that is at least 75%, (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the framework sequence of a VL of SEQ ID NO: 8. [000216] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, HC CDR2 and HC CDR3 of a heavy chain variable domain having the amino acid sequence of SEQ ID NO: 18. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, LC CDR2 and LC CDR3 of a light chain variable domain having the amino acid sequence of SEQ ID NO: 10. [000217] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, HC CDR2 and HC CDR3 of a heavy chain variable domain having the amino acid sequence of SEQ ID NO: 18. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, LC CDR2 and LC CDR3 of a light chain variable domain having the amino acid sequence of SEQ ID NO: 10. [000218] In some embodiments, according to the Kabat definition, an anti-CD3 antibody of the present disclosure comprises a HC CDR3 having the amino acid sequence of SEQ ID NO: 13. In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1 having the amino acid sequence of SEQ ID NO: 1, a HC CDR2 having the amino acid sequence of SEQ ID NO: 17, a HC CDR3 having the amino acid sequence of SEQ ID NO: 13, a LC CDR1 having the amino acid sequence of SEQ ID NO: 9, a LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000219] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, a HC CDR2, and a HC CDR3, which collectively contains no more than 5 amino acid variations (e.g., no more than 5, 4, 3, 2, or 1 amino acid variation) as compared with the HC CDR1 having the amino acid sequence of SEQ ID NO: 1, HC CDR2 having the amino acid sequence of SEQ ID NO: 17, and HC CDR3 having the amino acid sequence of SEQ ID NO: 13. “Collectively,” as used anywhere in the present disclosure, means that the total number of amino acid variations in all of the three heavy chain CDRs is within the defined Docket No. A1361.70024WO00 14108730.1range. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, a LC CDR2, and a LC CDR3, which collectively contains no more than 5 amino acid variations (e.g., no more than 5, 4, 3, 2 or 1 amino acid variation) as compared with the LC CDR1 having the amino acid sequence of SEQ ID NO: 9, LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000220] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, a HC CDR2, and a HC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the HC CDR1 having the amino acid sequence of SEQ ID NO: 1, HC CDR2 having the amino acid sequence of SEQ ID NO: 17, and HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, a LC CDR2, and a LC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the to the LC CDR1 having the amino acid sequence of SEQ ID NO: 9, LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000221] In some embodiments, an anti-CD3 antibody of the present disclosure comprises: a HC CDR1 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR1 having the amino acid sequence of SEQ ID NO: 1; a HC CDR2 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR2 having the amino acid sequence of SEQ ID NO: 17; and / or a HC CDR3 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises: a LC CDR1 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR1 having the amino acid sequence of SEQ ID NO: 9; a LC CDR2 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR2 having the amino acid sequence of SEQ ID NO: 5; and / or a LC CDR3 having no more than 3 Docket No. A1361.70024WO00 14108730.1amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000222] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH comprising the amino acid sequence of SEQ ID NO: 18. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a VL comprising the amino acid sequence of SEQ ID NO: 10. [000223] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VH as set forth in SEQ ID NO: 18. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a VL containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VL as set forth in SEQ ID NO: 10. In some embodiments, the number of amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) may occur within a VH of SEQ ID NO: 18 and / or a VL of SEQ ID NO: 10 excluding any of the CDR sequences therein. In some embodiments, an anti-CD3 antibodies provided herein comprise a heavy chain variable sequence that comprises a framework sequence that that contains no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation to the framework sequence of a VH of SEQ ID NO: 18, and / or a light chain variable sequence that comprises a framework sequence that that contains no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation to the framework sequence of a VL of SEQ ID NO: 10. [000224] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VH as set forth in SEQ ID NO: 18. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a VL comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VL as set forth in SEQ ID NO: 10. In some embodiments, the degree of sequence variation (e e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least Docket No. A1361.70024WO00 14108730.195%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) may occur within a VH of SEQ ID NO: 18, and / or a VL of SEQ ID NO: 10 excluding any of the CDR sequences therein. In some embodiments, an anti-CD3 antibody provided herein comprise a heavy chain variable sequence that is at least 75%, (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the framework sequence of a VH of SEQ ID NO: 18, and / or a light chain variable sequence that comprises a framework sequence that is at least 75%, (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the framework sequence of a VL of SEQ ID NO: 10. [000225] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, HC CDR2 and HC CDR3 of a heavy chain variable domain having the amino acid sequence of SEQ ID NO: 24. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, LC CDR2 and LC CDR3 of a light chain variable domain having the amino acid sequence of SEQ ID NO: 8. [000226] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, HC CDR2 and HC CDR3 of a heavy chain variable domain having the amino acid sequence of SEQ ID NO: 24. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, LC CDR2 and LC CDR3 of a light chain variable domain having the amino acid sequence of SEQ ID NO: 8. [000227] In some embodiments, according to the Kabat definition, an anti-CD3 antibody of the present disclosure comprises a HC CDR3 having the amino acid sequence of SEQ ID NO: 13. In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1 having the amino acid sequence of SEQ ID NO: 1, a HC CDR2 having the amino acid sequence of SEQ ID NO: 17, a HC CDR3 having the amino acid sequence of SEQ ID NO: 13, a LC CDR1 having the amino acid sequence of SEQ ID NO: 4, a LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000228] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, a HC CDR2, and a HC CDR3, which collectively contains no more than 5 amino acid variations (e.g., no more than 5, 4, 3, 2, or 1 amino acid variation) as compared with the HC CDR1 having the amino acid sequence of SEQ ID NO: 1, HC CDR2 having the amino acid sequence of SEQ ID NO: 17, and HC CDR3 having the amino acid sequence of SEQ ID Docket No. A1361.70024WO00 14108730.1NO: 13. “Collectively,” as used anywhere in the present disclosure, means that the total number of amino acid variations in all of the three heavy chain CDRs is within the defined range. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, a LC CDR2, and a LC CDR3, which collectively contains no more than 5 amino acid variations (e.g., no more than 5, 4, 3, 2 or 1 amino acid variation) as compared with the LC CDR1 having the amino acid sequence of SEQ ID NO: 4, LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000229] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, a HC CDR2, and a HC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the HC CDR1 having the amino acid sequence of SEQ ID NO: 1, HC CDR2 having the amino acid sequence of SEQ ID NO: 17, and HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, a LC CDR2, and a LC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the to the LC CDR1 having the amino acid sequence of SEQ ID NO: 4, LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000230] In some embodiments, an anti-CD3 antibody of the present disclosure comprises: a HC CDR1 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR1 having the amino acid sequence of SEQ ID NO: 1; a HC CDR2 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR2 having the amino acid sequence of SEQ ID NO: 17; and / or a HC CDR3 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises: a LC CDR1 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR1 having the amino acid sequence of SEQ ID NO: 4; a LC CDR2 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR2 Docket No. A1361.70024WO00 14108730.1having the amino acid sequence of SEQ ID NO: 5; and / or a LC CDR3 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000231] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH comprising the amino acid sequence of SEQ ID NO: 24. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a VL comprising the amino acid sequence of SEQ ID NO: 8. [000232] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VH as set forth in SEQ ID NO: 24. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a VL containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VL as set forth in SEQ ID NO: 8. In some embodiments, the number of amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) may occur within a VH of SEQ ID NO: 24 and / or a VL of SEQ ID NO: 8 excluding any of the CDR sequences therein. In some embodiments, an anti-CD3 antibodies provided herein comprise a heavy chain variable sequence that comprises a framework sequence that that contains no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation to the framework sequence of a VH of SEQ ID NO: 24, and / or a light chain variable sequence that comprises a framework sequence that that contains no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation to the framework sequence of a VL of SEQ ID NO: 8. [000233] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VH as set forth in SEQ ID NO: 24. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a VL comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VL as set forth in SEQ ID NO: 8. In some embodiments, the degree of sequence variation (e e.g., at least Docket No. A1361.70024WO00 14108730.180%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) may occur within a VH of SEQ ID NO: 24, and / or a VL of SEQ ID NO: 8 excluding any of the CDR sequences therein. In some embodiments, an anti-CD3 antibody provided herein comprise a heavy chain variable sequence that is at least 75%, (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the framework sequence of a VH of SEQ ID NO: 24, and / or a light chain variable sequence that comprises a framework sequence that is at least 75%, (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the framework sequence of a VL of SEQ ID NO: 8. [000234] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, HC CDR2 and HC CDR3 of a heavy chain variable domain having the amino acid sequence of SEQ ID NO: 24. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, LC CDR2 and LC CDR3 of a light chain variable domain having the amino acid sequence of SEQ ID NO: 10. [000235] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, HC CDR2 and HC CDR3 of a heavy chain variable domain having the amino acid sequence of SEQ ID NO: 24. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, LC CDR2 and LC CDR3 of a light chain variable domain having the amino acid sequence of SEQ ID NO: 10. [000236] In some embodiments, according to the Kabat definition, an anti-CD3 antibody of the present disclosure comprises a HC CDR3 having the amino acid sequence of SEQ ID NO: 13. In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1 having the amino acid sequence of SEQ ID NO: 1, a HC CDR2 having the amino acid sequence of SEQ ID NO: 17, a HC CDR3 having the amino acid sequence of SEQ ID NO: 13, a LC CDR1 having the amino acid sequence of SEQ ID NO: 9, a LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000237] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, a HC CDR2, and a HC CDR3, which collectively contains no more than 5 amino acid variations (e.g., no more than 5, 4, 3, 2, or 1 amino acid variation) as compared with the HC CDR1 having the amino acid sequence of SEQ ID NO: 1, HC CDR2 having the amino Docket No. A1361.70024WO00 14108730.1acid sequence of SEQ ID NO: 17, and HC CDR3 having the amino acid sequence of SEQ ID NO: 13. “Collectively,” as used anywhere in the present disclosure, means that the total number of amino acid variations in all of the three heavy chain CDRs is within the defined range. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, a LC CDR2, and a LC CDR3, which collectively contains no more than 5 amino acid variations (e.g., no more than 5, 4, 3, 2 or 1 amino acid variation) as compared with the LC CDR1 having the amino acid sequence of SEQ ID NO: 9, LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000238] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, a HC CDR2, and a HC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the HC CDR1 having the amino acid sequence of SEQ ID NO: 1, HC CDR2 having the amino acid sequence of SEQ ID NO: 17, and HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, a LC CDR2, and a LC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the to the LC CDR1 having the amino acid sequence of SEQ ID NO: 9, LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000239] In some embodiments, an anti-CD3 antibody of the present disclosure comprises: a HC CDR1 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR1 having the amino acid sequence of SEQ ID NO: 1; a HC CDR2 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR2 having the amino acid sequence of SEQ ID NO: 17; and / or a HC CDR3 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises: a LC CDR1 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR1 having the amino acid sequence of SEQ ID NO: 9; a LC CDR2 having no more than 3 amino acid Docket No. A1361.70024WO00 14108730.1variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR2 having the amino acid sequence of SEQ ID NO: 5; and / or a LC CDR3 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000240] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH comprising the amino acid sequence of SEQ ID NO: 24. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a VL comprising the amino acid sequence of SEQ ID NO: 10. [000241] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VH as set forth in SEQ ID NO: 24. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a VL containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VL as set forth in SEQ ID NO: 10. In some embodiments, the number of amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) may occur within a VH of SEQ ID NO: 24 and / or a VL of SEQ ID NO: 10 excluding any of the CDR sequences therein. In some embodiments, an anti-CD3 antibodies provided herein comprise a heavy chain variable sequence that comprises a framework sequence that that contains no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation to the framework sequence of a VH of SEQ ID NO: 24, and / or a light chain variable sequence that comprises a framework sequence that that contains no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation to the framework sequence of a VL of SEQ ID NO: 10. [000242] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VH as set forth in SEQ ID NO: 24. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a VL comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VL as set forth Docket No. A1361.70024WO00 14108730.1in SEQ ID NO: 10. In some embodiments, the degree of sequence variation (e e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) may occur within a VH of SEQ ID NO: 24, and / or a VL of SEQ ID NO: 10 excluding any of the CDR sequences therein. In some embodiments, an anti-CD3 antibody provided herein comprise a heavy chain variable sequence that is at least 75%, (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the framework sequence of a VH of SEQ ID NO: 24, and / or a light chain variable sequence that comprises a framework sequence that is at least 75%, (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the framework sequence of a VL of SEQ ID NO: 10. [000243] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, HC CDR2 and HC CDR3 of a heavy chain variable domain having the amino acid sequence of SEQ ID NO: 14. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, LC CDR2 and LC CDR3 of a light chain variable domain having the amino acid sequence of SEQ ID NO: 19. [000244] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, HC CDR2 and HC CDR3 of a heavy chain variable domain having the amino acid sequence of SEQ ID NO: 14. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, LC CDR2 and LC CDR3 of a light chain variable domain having the amino acid sequence of SEQ ID NO: 19. [000245] In some embodiments, according to the Kabat definition, an anti-CD3 antibody of the present disclosure comprises a HC CDR3 having the amino acid sequence of SEQ ID NO: 13. In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1 having the amino acid sequence of SEQ ID NO: 11, a HC CDR2 having the amino acid sequence of SEQ ID NO: 12, a HC CDR3 having the amino acid sequence of SEQ ID NO: 13, a LC CDR1 having the amino acid sequence of SEQ ID NO: 4, a LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000246] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, a HC CDR2, and a HC CDR3, which collectively contains no more than 5 amino acid variations (e.g., no more than 5, 4, 3, 2, or 1 amino acid variation) as compared with the Docket No. A1361.70024WO00 14108730.1HC CDR1 having the amino acid sequence of SEQ ID NO: 11, HC CDR2 having the amino acid sequence of SEQ ID NO: 12, and HC CDR3 having the amino acid sequence of SEQ ID NO: 13. “Collectively,” as used anywhere in the present disclosure, means that the total number of amino acid variations in all of the three heavy chain CDRs is within the defined range. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, a LC CDR2, and a LC CDR3, which collectively contains no more than 5 amino acid variations (e.g., no more than 5, 4, 3, 2 or 1 amino acid variation) as compared with the LC CDR1 having the amino acid sequence of SEQ ID NO: 4, LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000247] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, a HC CDR2, and a HC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the HC CDR1 having the amino acid sequence of SEQ ID NO: 11, HC CDR2 having the amino acid sequence of SEQ ID NO: 12, and HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, a LC CDR2, and a LC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the to the LC CDR1 having the amino acid sequence of SEQ ID NO: 4, LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000248] In some embodiments, an anti-CD3 antibody of the present disclosure comprises: a HC CDR1 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR1 having the amino acid sequence of SEQ ID NO: 11; a HC CDR2 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR2 having the amino acid sequence of SEQ ID NO: 12; and / or a HC CDR3 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises: a LC CDR1 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR1 having the Docket No. A1361.70024WO00 14108730.1amino acid sequence of SEQ ID NO: 4; a LC CDR2 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR2 having the amino acid sequence of SEQ ID NO: 5; and / or a LC CDR3 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000249] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH comprising the amino acid sequence of SEQ ID NO: 14. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a VL comprising the amino acid sequence of SEQ ID NO: 19. [000250] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VH as set forth in SEQ ID NO: 14. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a VL containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VL as set forth in SEQ ID NO: 19. In some embodiments, the number of amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) may occur within a VH of SEQ ID NO: 14 and / or a VL of SEQ ID NO: 19 excluding any of the CDR sequences therein. In some embodiments, an anti-CD3 antibodies provided herein comprise a heavy chain variable sequence that comprises a framework sequence that that contains no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation to the framework sequence of a VH of SEQ ID NO: 14, and / or a light chain variable sequence that comprises a framework sequence that that contains no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation to the framework sequence of a VL of SEQ ID NO: 19. [000251] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VH as set forth in SEQ ID NO: 14. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a VL comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at Docket No. A1361.70024WO00 14108730.1least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VL as set forth in SEQ ID NO: 19. In some embodiments, the degree of sequence variation (e e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) may occur within a VH of SEQ ID NO: 14, and / or a VL of SEQ ID NO: 19 excluding any of the CDR sequences therein. In some embodiments, an anti-CD3 antibody provided herein comprise a heavy chain variable sequence that is at least 75%, (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the framework sequence of a VH of SEQ ID NO: 14, and / or a light chain variable sequence that comprises a framework sequence that is at least 75%, (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the framework sequence of a VL of SEQ ID NO: 19. [000252] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, HC CDR2 and HC CDR3 of a heavy chain variable domain having the amino acid sequence of SEQ ID NO: 16. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, LC CDR2 and LC CDR3 of a light chain variable domain having the amino acid sequence of SEQ ID NO: 19. [000253] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, HC CDR2 and HC CDR3 of a heavy chain variable domain having the amino acid sequence of SEQ ID NO: 16. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, LC CDR2 and LC CDR3 of a light chain variable domain having the amino acid sequence of SEQ ID NO: 19. [000254] In some embodiments, according to the Kabat definition, an anti-CD3 antibody of the present disclosure comprises a HC CDR3 having the amino acid sequence of SEQ ID NO: 13. In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1 having the amino acid sequence of SEQ ID NO: 1, a HC CDR2 having the amino acid sequence of SEQ ID NO: 15, a HC CDR3 having the amino acid sequence of SEQ ID NO: 13, a LC CDR1 having the amino acid sequence of SEQ ID NO: 4, a LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000255] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, a HC CDR2, and a HC CDR3, which collectively contains no more than 5 amino Docket No. A1361.70024WO00 14108730.1acid variations (e.g., no more than 5, 4, 3, 2, or 1 amino acid variation) as compared with the HC CDR1 having the amino acid sequence of SEQ ID NO: 1, HC CDR2 having the amino acid sequence of SEQ ID NO: 15, and HC CDR3 having the amino acid sequence of SEQ ID NO: 13. “Collectively,” as used anywhere in the present disclosure, means that the total number of amino acid variations in all of the three heavy chain CDRs is within the defined range. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, a LC CDR2, and a LC CDR3, which collectively contains no more than 5 amino acid variations (e.g., no more than 5, 4, 3, 2 or 1 amino acid variation) as compared with the LC CDR1 having the amino acid sequence of SEQ ID NO: 4, LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000256] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, a HC CDR2, and a HC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the HC CDR1 having the amino acid sequence of SEQ ID NO: 1, HC CDR2 having the amino acid sequence of SEQ ID NO: 15, and HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, a LC CDR2, and a LC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the to the LC CDR1 having the amino acid sequence of SEQ ID NO: 4, LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000257] In some embodiments, an anti-CD3 antibody of the present disclosure comprises: a HC CDR1 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR1 having the amino acid sequence of SEQ ID NO: 1; a HC CDR2 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR2 having the amino acid sequence of SEQ ID NO: 15; and / or a HC CDR3 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises: a LC CDR1 having no more than 3 amino acid variations (e.g., Docket No. A1361.70024WO00 14108730.1no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR1 having the amino acid sequence of SEQ ID NO: 4; a LC CDR2 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR2 having the amino acid sequence of SEQ ID NO: 5; and / or a LC CDR3 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000258] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH comprising the amino acid sequence of SEQ ID NO: 16. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a VL comprising the amino acid sequence of SEQ ID NO: 19. [000259] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VH as set forth in SEQ ID NO: 16. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a VL containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VL as set forth in SEQ ID NO: 19. In some embodiments, the number of amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) may occur within a VH of SEQ ID NO: 16 and / or a VL of SEQ ID NO: 19 excluding any of the CDR sequences therein. In some embodiments, an anti-CD3 antibodies provided herein comprise a heavy chain variable sequence that comprises a framework sequence that that contains no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation to the framework sequence of a VH of SEQ ID NO: 16, and / or a light chain variable sequence that comprises a framework sequence that that contains no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation to the framework sequence of a VL of SEQ ID NO: 19. [000260] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VH as set forth in SEQ ID NO: 16. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a VL comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at Docket No. A1361.70024WO00 14108730.1least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VL as set forth in SEQ ID NO: 19. In some embodiments, the degree of sequence variation (e e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) may occur within a VH of SEQ ID NO: 16, and / or a VL of SEQ ID NO: 19 excluding any of the CDR sequences therein. In some embodiments, an anti-CD3 antibody provided herein comprise a heavy chain variable sequence that is at least 75%, (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the framework sequence of a VH of SEQ ID NO: 16, and / or a light chain variable sequence that comprises a framework sequence that is at least 75%, (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the framework sequence of a VL of SEQ ID NO: 19. [000261] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, HC CDR2 and HC CDR3 of a heavy chain variable domain having the amino acid sequence of SEQ ID NO: 18. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, LC CDR2 and LC CDR3 of a light chain variable domain having the amino acid sequence of SEQ ID NO: 19. [000262] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, HC CDR2 and HC CDR3 of a heavy chain variable domain having the amino acid sequence of SEQ ID NO: 18. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, LC CDR2 and LC CDR3 of a light chain variable domain having the amino acid sequence of SEQ ID NO: 19. [000263] In some embodiments, according to the Kabat definition, an anti-CD3 antibody of the present disclosure comprises a HC CDR3 having the amino acid sequence of SEQ ID NO: 13. In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1 having the amino acid sequence of SEQ ID NO: 1, a HC CDR2 having the amino acid sequence of SEQ ID NO: 17, a HC CDR3 having the amino acid sequence of SEQ ID NO: 13, a LC CDR1 having the amino acid sequence of SEQ ID NO: 4, a LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 having the amino acid sequence of SEQ ID NO: 6. Docket No. A1361.70024WO00 14108730.1[000264] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, a HC CDR2, and a HC CDR3, which collectively contains no more than 5 amino acid variations (e.g., no more than 5, 4, 3, 2, or 1 amino acid variation) as compared with the HC CDR1 having the amino acid sequence of SEQ ID NO: 1, HC CDR2 having the amino acid sequence of SEQ ID NO: 17, and HC CDR3 having the amino acid sequence of SEQ ID NO: 13. “Collectively,” as used anywhere in the present disclosure, means that the total number of amino acid variations in all of the three heavy chain CDRs is within the defined range. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, a LC CDR2, and a LC CDR3, which collectively contains no more than 5 amino acid variations (e.g., no more than 5, 4, 3, 2 or 1 amino acid variation) as compared with the LC CDR1 having the amino acid sequence of SEQ ID NO: 4, LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000265] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a HC CDR1, a HC CDR2, and a HC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the HC CDR1 having the amino acid sequence of SEQ ID NO: 1, HC CDR2 having the amino acid sequence of SEQ ID NO: 17, and HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a LC CDR1, a LC CDR2, and a LC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the to the LC CDR1 having the amino acid sequence of SEQ ID NO: 4, LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000266] In some embodiments, an anti-CD3 antibody of the present disclosure comprises: a HC CDR1 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR1 having the amino acid sequence of SEQ ID NO: 1; a HC CDR2 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR2 having the amino acid sequence of SEQ ID NO: 17; and / or a HC CDR3 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR3 having the amino Docket No. A1361.70024WO00 14108730.1acid sequence of SEQ ID NO: 13. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises: a LC CDR1 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR1 having the amino acid sequence of SEQ ID NO: 4; a LC CDR2 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR2 having the amino acid sequence of SEQ ID NO: 5; and / or a LC CDR3 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000267] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH comprising the amino acid sequence of SEQ ID NO: 18. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a VL comprising the amino acid sequence of SEQ ID NO: 19. [000268] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VH as set forth in SEQ ID NO: 18. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a VL containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VL as set forth in SEQ ID NO: 19. In some embodiments, the number of amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) may occur within a VH of SEQ ID NO: 18 and / or a VL of SEQ ID NO: 19 excluding any of the CDR sequences therein. In some embodiments, an anti-CD3 antibodies provided herein comprise a heavy chain variable sequence that comprises a framework sequence that that contains no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation to the framework sequence of a VH of SEQ ID NO: 18, and / or a light chain variable sequence that comprises a framework sequence that that contains no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation to the framework sequence of a VL of SEQ ID NO: 19. [000269] In some embodiments, an anti-CD3 antibody of the present disclosure comprises a VH comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VH as set forth in SEQ ID Docket No. A1361.70024WO00 14108730.1NO: 18. Alternatively or in addition, the anti-CD3 antibody of the present disclosure comprises a VL comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VL as set forth in SEQ ID NO: 19. In some embodiments, the degree of sequence variation (e e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) may occur within a VH of SEQ ID NO: 18, and / or a VL of SEQ ID NO: 19 excluding any of the CDR sequences therein. In some embodiments, an anti-CD3 antibody provided herein comprise a heavy chain variable sequence that is at least 75%, (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the framework sequence of a VH of SEQ ID NO: 18, and / or a light chain variable sequence that comprises a framework sequence that is at least 75%, (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the framework sequence of a VL of SEQ ID NO: 19. [000270] An anti-CD3 antibody described herein can be in any antibody form, including, but not limited to, intact (i.e., full-length) antibodies, antigen-binding fragments thereof (such as Fab, F(ab'), F(ab')2, Fv), single chain antibodies, bi-specific antibodies, or nanobodies. In some embodiments, the anti-CD3 antibody described herein is a scFv. In some embodiments, the anti-CD3 antibody described herein is a scFv-Fab (e.g., scFv fused to a portion of a constant region). Provided herein, in some embodiments, is a bispecific antibody. In some embodiments, the first antigen binding site of the bispecific antibody specifically binds CD3. In some embodiments, the second antigen binding site specifically binds a T cell antigen. In some antibodies, the T cell antigen is a CD3 complex or a portion thereof. [000271] In some embodiments, conservative mutations can be introduced into antibody sequences (e.g., CDRs or framework sequences) at positions where the residues are not likely to be involved in interacting with a target antigen (e.g., CD3), for example, as determined based on a crystal structure. In some embodiments, one, two or more mutations (e.g., amino acid substitutions) are introduced into the Fc region of an anti-CD3 antibody described herein (e.g., in a CH2 domain (residues 231-340 of human IgG1) and / or CH3 domain (residues 341- 447 of human IgG1) and / or the hinge region, with numbering according to the Kabat numbering system (e.g., the EU index in Kabat)) to alter one or more functional properties of Docket No. A1361.70024WO00 14108730.1the antibody, such as serum half-life, complement fixation, Fc receptor binding and / or antigen-dependent cellular cytotoxicity. [000272] In some embodiments, one, two or more mutations (e.g., amino acid substitutions) are introduced into the hinge region of the Fc region (CH1 domain) such that the number of cysteine residues in the hinge region are altered (e.g., increased or decreased) as described in, e.g., U.S. Pat. No. 5,677,425. The number of cysteine residues in the hinge region of the CH1 domain can be altered to, e.g., facilitate assembly of the light and heavy chains, or to alter (e.g., increase or decrease) the stability of the antibody or to facilitate linker conjugation. [000273] In some embodiments, one, two or more mutations (e.g., amino acid substitutions) are introduced into the Fc region of an antibody described herein (e.g., in a CH2 domain (residues 231-340 of human IgG1) and / or CH3 domain (residues 341-447 of human IgG1) and / or the hinge region, with numbering according to the Kabat numbering system (e.g., the EU index in Kabat)) to increase or decrease the affinity of the antibody for an Fc receptor (e.g., an activated Fc receptor) on the surface of an effector cell. Mutations in the Fc region of an antibody that decrease or increase the affinity of an antibody for an Fc receptor and techniques for introducing such mutations into the Fc receptor or fragment thereof are known to one of skill in the art. Examples of mutations in the Fc receptor of an antibody that can be made to alter the affinity of the antibody for an Fc receptor are described in, e.g., Smith P et al., (2012) PNAS 109: 6181-6186, U.S. Pat. No. 6,737,056, and International Publication Nos. WO 02 / 060919; WO 98 / 23289; and WO 97 / 34631, which are incorporated herein by reference. [000274] In some embodiments, one, two or more amino acid mutations (i.e., substitutions, insertions or deletions) are introduced into an IgG constant domain, or FcRn-binding fragment thereof (preferably an Fc or hinge-Fc domain fragment) to alter (e.g., decrease or increase) half-life of the antibody in vivo. See, e.g., International Publication Nos. WO 02 / 060919; WO 98 / 23289; and WO 97 / 34631; and U.S. Pat. Nos. 5,869,046, 6,121,022, 6,277,375 and 6,165,745 for examples of mutations that will alter (e.g., decrease or increase) the half-life of an antibody in vivo. [000275] In some embodiments, one, two or more amino acid mutations (i.e., substitutions, insertions, or deletions) are introduced into an IgG constant domain, or FcRn-binding fragment thereof (preferably an Fc or hinge-Fc domain fragment) to decrease the half-life of the anti-CD3 antibody in vivo. Docket No. A1361.70024WO00 14108730.1[000276] In some embodiments, one, two or more amino acid mutations (i.e., substitutions, insertions or deletions) are introduced into an IgG constant domain, or FcRn-binding fragment thereof (preferably an Fc or hinge-Fc domain fragment) to increase the half-life of the antibody in vivo. In some embodiments, the antibodies can have one or more amino acid mutations (e.g., substitutions) in the second constant (CH2) domain (residues 231-340 of human IgG1) and / or the third constant (CH3) domain (residues 341-447 of human IgG1), with numbering according to the EU index in Kabat (Kabat E A et al., (1991) supra). In some embodiments, the constant region of the IgG1 of an antibody described herein comprises a methionine (M) to tyrosine (Y) substitution in position 252, a serine (S) to threonine (T) substitution in position 254, and a threonine (T) to glutamic acid (E) substitution in position 256, numbered according to the EU index as in Kabat. See U.S. Pat. No. 7,658,921, which is incorporated herein by reference. This type of mutant IgG, referred to as "YTE mutant" has been shown to display fourfold increased half-life as compared to wild-type versions of the same antibody (see Dall'Acqua W F et al., (2006) J Biol Chem 281: 23514-24). In some embodiments, an antibody comprises an IgG constant domain comprising one, two, three or more amino acid substitutions of amino acid residues at positions 251-257, 285-290, 308- 314, 385-389, and 428-436, numbered according to the EU index as in Kabat. [000277] In some embodiments, one, two or more amino acid substitutions are introduced into an IgG constant domain Fc region to alter the effector function(s) of the anti-CD3 antibody. The effector ligand to which affinity is altered can be, for example, an Fc receptor or the C1 component of complement. This approach is described in further detail in U.S. Pat. Nos. 5,624,821 and 5,648,260 (e.g., a L234A and L235A mutation). In some embodiments, the deletion or inactivation (through point mutations or other means) of a constant region domain can reduce Fc receptor binding of the circulating antibody thereby increasing tumor localization. See, e.g., U.S. Pat. Nos. 5,585,097 and 8,591,886 for a description of mutations that delete or inactivate the constant domain and thereby increase tumor localization. In some embodiments, one or more amino acid substitutions may be introduced into the Fc region of an antibody described herein to remove potential glycosylation sites on Fc region, which may reduce Fc receptor binding (see, e.g., Shields R L et al., (2001) J Biol Chem 276: 6591-604). [000278] In some embodiments, one or more amino in the constant region of an anti-CD3 antibody described herein can be replaced with a different amino acid residue such that the antibody has altered Clq binding and / or reduced or abolished complement dependent cytotoxicity (CDC). This approach is described in further detail in U.S. Pat. No. 6,194,551 Docket No. A1361.70024WO00 14108730.1(Idusogie et al). In some embodiments, one or more amino acid residues in the N-terminal region of the CH2 domain of an antibody described herein are altered to thereby alter the ability of the antibody to fix complement. This approach is described further in International Publication No. WO 94 / 29351. In some embodiments, the Fc region of an antibody described herein is modified to increase the ability of the antibody to mediate antibody dependent cellular cytotoxicity (ADCC) and / or to increase the affinity of the antibody for an Fcγ receptor. This approach is described further in International Publication No. WO 00 / 42072. [000279] In some embodiments, the heavy and / or light chain variable domain(s) sequence(s) of the antibodies provided herein can be used to generate, for example, CDR-grafted, chimeric, humanized, or composite human antibodies or antigen-binding fragments, as described elsewhere herein. As understood by one of ordinary skill in the art, any variant, CDR-grafted, chimeric, humanized, or composite antibodies derived from any of the antibodies provided herein may be useful in the compositions and methods described herein and will maintain the ability to specifically bind CD3, such that the variant, CDR-grafted, chimeric, humanized, or composite antibody has at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95% or more binding to CD3 relative to the original antibody from which it is derived. [000280] In some embodiments, the antibodies provided herein comprise mutations that confer desirable properties to the antibodies. For example, to avoid potential complications due to Fab-arm exchange, which is known to occur with native IgG4 mAbs, the antibodies provided herein may comprise a stabilizing ‘Adair’ mutation (Angal S., et al., “A single amino acid substitution abolishes the heterogeneity of chimeric mouse / human (IgG4) antibody,” Mol Immunol 30, 105-108; 1993), where serine 228 (EU numbering; residue 241 Kabat numbering) is converted to proline resulting in an IgG1-like hinge sequence. Accordingly, any of the antibodies may include a stabilizing ‘Adair’ mutation. [000281] In some embodiments, an antibody is modified, e.g., modified via glycosylation, phosphorylation, sumoylation, and / or methylation. In some embodiments, an antibody is a glycosylated antibody, which is conjugated to one or more sugar or carbohydrate molecules. In some embodiments, the one or more sugar or carbohydrate molecule are conjugated to the antibody via N-glycosylation, O-glycosylation, C-glycosylation, glypiation (GPI anchor attachment), and / or phosphoglycosylation. In some embodiments, the one or more sugar or carbohydrate molecules are monosaccharides, disaccharides, oligosaccharides, or glycans. In some embodiments, the one or more sugar or carbohydrate molecule is a branched Docket No. A1361.70024WO00 14108730.1oligosaccharide or a branched glycan. In some embodiments, the one or more sugar or carbohydrate molecule includes a mannose unit, a glucose unit, an N-acetylglucosamine unit, an N-acetylgalactosamine unit, a galactose unit, a fucose unit, or a phospholipid unit. In some embodiments, there are about 1-10, about 1-5, about 5-10, about 1-4, about 1-3, or about 2 sugar molecules. In some embodiments, a glycosylated antibody is fully or partially glycosylated. In some embodiments, an antibody is glycosylated by chemical reactions or by enzymatic means. In some embodiments, an antibody is glycosylated in vitro or inside a cell, which may optionally be deficient in an enzyme in the N- or O- glycosylation pathway, e.g., a glycosyltransferase. In some embodiments, an antibody is functionalized with sugar or carbohydrate molecules as described in International Patent Application Publication WO2014065661, published on May 1, 2014, entitled, “Modified antibody, antibody- conjugate and process for the preparation thereof”. [000282] In some embodiments, any one of an anti-CD3 antibody described herein may comprise a signal peptide in the heavy and / or light chain sequence (e.g., a N-terminal signal peptide). In some embodiments, the anti-CD3 antibody described herein comprises any one of the VH and VL sequences, any one of the IgG heavy chain and light chain sequences, or any one of the F(ab’) heavy chain and light chain sequences described herein, and further comprises a signal peptide (e.g., a N-terminal signal peptide). [000283] In some embodiments, any one of the antibodies described herein is a multispecific antibody that specifically binds CD3 and one or more additional target antigens. In some embodiments, the antibody is a bispecific antibody that specifically binds to CD3 and one additional target antigen. In some embodiments, the multispecific antibody or bispecific antibody can be obtained by known technology in the art. In some embodiments, the one or more additional target antigens include are not limited to CD3, CD4, CD8, CD20, CD19, CD21, CD23, CD46, CD80, HLA-DR, CD74, CD22, CD14, CD15, CD16, CD123, CD28, CD137 (4-1BB), interleukin (IL)-2, IL-12, IL-15, IL-21, TCR gamma / delta, NKp46, or KIR. In some embodiments, the one or more additional target antigens comprise a cancer antigen or a pathogen-derived antigen. [000284] In some embodiments, the antibodies described herein are conjugated directly or indirectly to one or more molecular payloads or labels. For example, in some embodiments, antibodies described herein are conjugated to molecular payload, e.g., a molecular payload providing a therapeutic benefit for a subject, e.g., an antibody-drug conjugate (ADC). In some embodiments, a molecular payload may be a small molecule, protein, nucleic acid, Docket No. A1361.70024WO00 14108730.1oligonucleotide, or any molecular entity capable of modulating the activity or function of a gene, protein, and / or nucleic acid, e.g., in a cell. In some embodiments, the molecular payload is a cytotoxic agent or a chemotherapeutic agent. In some embodiments, antibodies described herein are conjugated directly or indirectly to a detectable label, e.g., for diagnostic purposes. [000285] In some embodiments, the present disclosure also provides fusion proteins comprising an anti-CD3 antibody described herein fused directly or indirectly (e.g., via a linker) to one or more polypeptide or protein. (b) T cell engaging bispecific antibodies targeting a CD3 complex [000286] In some aspects, the present disclosure provides a multispecific (e.g., a bispecific) antibody comprising one or more first antigen binding sites targeting one or more different epitopes of a cancer antigen or a pathogen-derived antigen, and one or more second binding sites targeting CD3. In some aspects, the present disclosure provides a multispecific (e.g., a bispecific) antibody comprising one or more first antigen binding sites targeting one or more different epitopes of a cancer antigen or a pathogen-derived antigen and one or more second antigen binding sites targeting CD3. Such multispecific (e.g., bispecific) antibodies can redirect T cells (e.g., cytotoxic T cells) to cancer cells, or infected cells that are displaying pathogen-derived antigens on the cell surface, by binding CD3 on T cells with one binding site and binding one or more cancer or pathogen-derived antigens with another binding site. This dual-binding activity spatially reorients T cells to directly kill the target cells, thereby enhancing the cytolytic immune response. [000287] In some embodiments, the present disclosure provides a bispecific antibody comprising a first antigen binding site targeting a cancer antigen or a pathogen-derived antigen, and a second binding site targeting CD3. In some embodiments, the present disclosure provides a bispecific antibody comprising a first antigen binding site targeting a cancer antigen or a pathogen-derived antigen, and a second antigen binding site that specifically binds CD3. In some embodiments, the present disclosure provides a bispecific antibody comprising a first antigen binding site targeting one or more epitopes of a cancer antigen or a pathogen-derived antigen, and a second antigen binding site that specifically binds CD3. In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising an antigen binding site of any one of the CD3 antibodies described in Table 1. In some embodiments, a bispecific antibody described herein comprises Docket No. A1361.70024WO00 14108730.1a second antigen binding site comprising a HC CDR1, HC CDR2, HC CDR3, LC CDR1, LC CDR2, and / or LC CDR3 of any one of the anti-CD3 antibodies described in Table 1. In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a VH and / or VL of any one of the anti-CD3 antibodies described in Table 1. [000288] In some embodiments, a bispecific antibody described herein is a T cell engaging antibody that targets CD3 and also targets a cancer antigen or a pathogen-derived antigen. In some embodiments, a bispecific antibody described herein comprises a second antigen binding site that specifically binds CD3 and a first antigen binding site that specifically binds a cancer antigen or a pathogen-derived antigen (referred to as a bispecific antibody). In some embodiments, the first antigen binding site specifically binds to a cancer antigen. In some embodiments, the cancer antigen includes but is not limited to CD13, CD14, CD15, CD19, CD20, CD22, CD30, CD33, CD38, CD41, CD61, CD64, CD68, CD70, CD117, CD123, CD138, CD267, CD269, Claudin18.2, DLL3, HER2 / neu, PSA (prostate-specific antigen), PSMA, CEA (carcinoembryonic antigen), NY-ESO-1, glypican-3, EGFR, EGFRvIII, MAGE (melanoma antigens), MAGE-A1, MAGE-A3, MAGE-A4, MAGE-A8, MSLN (mesothelin), BCMA, TACI, alpha-fetoprotein, BAFF, FLT3, CA 9-19, CA 72-4, FAP, MART-1, F77, GD2, CT83, HORMAD1, glycoprotein (gp) 100, HPV16, WT1, or PRAME. In some embodiments, the cancer antigen is WT1. In some embodiments, the cancer antigen is PRAME. In some embodiments, the cancer antigen is DLL3. In some embodiments, the cancer antigen is CD70. In some embodiments, the cancer antigen is Claudin18.2. In some embodiments, the cancer antigen is MSLN. In some embodiments, the cancer antigen is MAGE-A4. In some embodiments, the cancer antigen is MAGE-A8. In some embodiments, the cancer antigen is CD38. In some embodiments, the cancer antigen is BCMA. [000289] In some embodiments, first antigen binding site specifically binds a pathogen- derived antigen. In some embodiments, the pathogen-derived antigen is derived from pathogens that include but are not limited to HIV, HPV, RSV, influenza, Epstein-Barr virus (EBV), cytomegalovirus (CMV), Dengue virus (DNV), Zika virus (ZIKV), SARS-CoV-2, Staphyloccocus species (e.g., S. aureus, S. pneumoniae, and others), Enterococcus spp. (e.g., E. faecium and others), Klebsiella spp. (e.g., K. pneumoniae and others), Acinetobacter spp. (e.g., A. baumannii and others), Pseudomonas spp. (e.g., P. aeruginosa and others, Enterobacter spp. (e.g., E. cloacae, E. aerogenes, and others), Plasmodium spp. (e.g., P. falciparum, P. vivax, and others), Trypanosoma spp. (e.g., T. brucei gambiense, T. brucei Docket No. A1361.70024WO00 14108730.1rhodesiense, and others), Schistosoma spp. (e.g., S. mansoni, S. haematobium, S. japonicum), T. solium, and E. histolytica. [000290] In some embodiments, a need for recruiting a T cell to a cancer cell to kill the cancer cell exists. In some embodiments, the present disclosure provides means for engaging a T cell to a cancer cell. In some embodiments, the means for engaging a T cell to a cancer cell is a bispecific antibody described herein. In some embodiments, the present disclosure provides means for eliciting cytotoxic T cell immunity against cancer cells. In some embodiments, the means for eliciting cytotoxic T cell immunity against cancer cells is a bispecific antibody described herein. [000291] In some embodiments, a need for recruiting a T cell to an infected cell to kill the infected cell exists. In some embodiments, the present disclosure provides means for engaging a T cell to an infected cell. In some embodiments, the means for engaging a T cell to an infected cell is a bispecific antibody described herein. In some embodiments, the present disclosure provides means for eliciting cytotoxic T cell immunity against infected cells. In some embodiments, the means for eliciting cytotoxic T cell immunity against infected cells is a bispecific antibody described herein. [000292] In some embodiments, a bispecific antibody comprises a second antigen binding site that specifically binds to CD3, wherein the improvement comprises a second antigen binding site that specifically binds to a CD3 complex that comprises any one of the anti-CD3 binding site derived from an anti-CD3 antibody described herein (e.g., any one of the anti- CD3 antibody described in Table 1). [000293] In some embodiments, a bispecific antibody provided herein comprises an antigen binding site that binds to B-cell maturation antigen (BCMA) and an antigen binding site that specifically binds to CD3. BCMA is a tumor necrosis factor receptor (TNFR) superfamily member that helps to coordinate B cell proliferation maturation and survival, as well as differentiation into plasma cells. BCMA is expressed almost exclusively on plasmablasts and plasma cells and is weakly detectable on some memory B cells committed to plasma cell differentiation and on plasmacytoid dendritic cells. [000294] In some embodiments, a bispecific antibody provided herein comprises an a bispecific antibody provided herein comprises [000295] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site that specifically binds to CD3. In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1, a Docket No. A1361.70024WO00 14108730.1HC CDR2 and a HC CDR3 of a heavy chain variable domain (VH) having the amino acid sequence of SEQ ID NO: 7. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a LC CDR1, a LC CDR2 and a LC CDR3 of a light chain variable domain (VL) having the amino acid sequence of SEQ ID NO: 10. [000296] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR3 having the amino acid sequence of SEQ ID NO: 3. In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1 having the amino acid sequence of SEQ ID NO: 1, a HC CDR2 having the amino acid sequence of SEQ ID NO: 2, and a HC CDR3 having the amino acid sequence of SEQ ID NO: 3. Alternatively or in addition, in some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a LC CDR1 having the amino acid sequence of SEQ ID NO: 9, a LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 having the amino acid sequence of SEQ ID NO: 6. In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1 having the amino acid sequence of SEQ ID NO: 1, a HC CDR2 having the amino acid sequence of SEQ ID NO: 2, a HC CDR3 having the amino acid sequence of SEQ ID NO: 3, a LC CDR1 having the amino acid sequence of SEQ ID NO: 9, a LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000297] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1, a HC CDR2, and a HC CDR3, which collectively contains no more than 5 amino acid variations (e.g., no more than 5, 4, 3, 2, or 1 amino acid variation) as compared with the HC CDR1 having the amino acid sequence of SEQ ID NO: 1, HC CDR2 having the amino acid sequence of SEQ ID NO: 2, and HC CDR3 having the amino acid sequence of SEQ ID NO: 3. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a LC CDR1, a LC CDR2, and a LC CDR3, which collectively contains no more than 5 amino acid variations (e.g., no more than 5, 4, 3, 2 or 1 amino acid variation) as compared with the LC CDR1 having the amino acid sequence of SEQ ID NO: 9, LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6. Docket No. A1361.70024WO00 14108730.1[000298] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1, a HC CDR2, and a HC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the HC CDR1 having the amino acid sequence of SEQ ID NO: 1, HC CDR2 having the amino acid sequence of SEQ ID NO: 2, and HC CDR3 having the amino acid sequence of SEQ ID NO: 3. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a LC CDR1, a LC CDR2, and a LC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the to the LC CDR1 having the amino acid sequence of SEQ ID NO: 9, LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000299] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR1 having the amino acid sequence of SEQ ID NO: 1; a HC CDR2 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR2 having the amino acid sequence of SEQ ID NO: 2; and / or a HC CDR3 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR3 having the amino acid sequence of SEQ ID NO: 3. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a LC CDR1 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR1 having the amino acid sequence of SEQ ID NO: 9; a LC CDR2 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR2 having the amino acid sequence of SEQ ID NO: 5; and / or a LC CDR3 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000300] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1 at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the HC CDR1 having the amino Docket No. A1361.70024WO00 14108730.1acid sequence of SEQ ID NO: 1; a HC at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the HC CDR2 having the amino acid sequence of SEQ ID NO: 2; and / or a HC CDR3 at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the HC CDR3 having the amino acid sequence of SEQ ID NO: 3. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a LC CDR1 at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the LC CDR1 having the amino acid sequence of SEQ ID NO: 9; a LC CDR2 at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the LC CDR2 having the amino acid sequence of SEQ ID NO: 5; and / or a LC CDR3 at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000301] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a VH comprising the amino acid sequence of SEQ ID NO: 7. Alternatively or in addition a bispecific antibody described herein comprises a second antigen binding site comprising a VL comprising the amino acid sequence of SEQ ID NO: 10. In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a VH comprising the amino acid sequence of SEQ ID NO: 7, and a VL comprising the amino acid sequence of SEQ ID NO: 10. [000302] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a VH containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VH as set forth in SEQ ID NO: 7. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a VL containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VL as set forth in SEQ ID NO: 10. Docket No. A1361.70024WO00 14108730.1[000303] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a VH comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VH as set forth in SEQ ID NO: 7. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a VL comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VL as set forth in SEQ ID NO: 10. [000304] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a comprises a VH containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VH as set forth in SEQ ID NO: 7. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a VL containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VL as set forth in SEQ ID NO: 10. In some embodiments, the number of amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) may occur within a VH of SEQ ID NO: 7 and / or a VL of SEQ ID NO: 10 excluding any of the CDR sequences therein. In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a heavy chain variable sequence that comprises a framework sequence that that contains no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation to the framework sequence of a VH of SEQ ID NO: 7, and / or a light chain variable sequence that comprises a framework sequence that that contains no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation to the framework sequence of a VL of SEQ ID NO: 10. [000305] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a VH comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VH as set forth in SEQ ID NO: 7. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a VL comprising an Docket No. A1361.70024WO00 14108730.1amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VL as set forth in SEQ ID NO: 10. In some embodiments, the degree of sequence variation (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) may occur within a VH of SEQ ID NO: 7, and / or a VL of SEQ ID NO: 10 excluding any of the CDR sequences therein. In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a heavy chain variable sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the framework sequence of a VH of SEQ ID NO: 7, and / or a light chain variable sequence that comprises a framework sequence that at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the framework sequence of a VL of SEQ ID NO: 10. [000306] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site that specifically binds to CD3. In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1, a HC CDR2 and a HC CDR3 of a heavy chain variable domain (VH) having the amino acid sequence of SEQ ID NO: 14. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a LC CDR1, a LC CDR2 and a LC CDR3 of a light chain variable domain (VL) having the amino acid sequence of SEQ ID NO: 10. [000307] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR3 having the amino acid sequence of SEQ ID NO: 13. In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1 having the amino acid sequence of SEQ ID NO: 11, a HC CDR2 having the amino acid sequence of SEQ ID NO: 12, and a HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, in some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a LC CDR1 having the amino acid sequence of SEQ ID NO: 9, a LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 having the amino acid sequence of SEQ ID NO: 6. In some embodiments, a bispecific antibody described herein comprises a second Docket No. A1361.70024WO00 14108730.1antigen binding site comprising a HC CDR1 having the amino acid sequence of SEQ ID NO: 11, a HC CDR2 having the amino acid sequence of SEQ ID NO: 12, a HC CDR3 having the amino acid sequence of SEQ ID NO: 13, a LC CDR1 having the amino acid sequence of SEQ ID NO: 9, a LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000308] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1, a HC CDR2, and a HC CDR3, which collectively contains no more than 5 amino acid variations (e.g., no more than 5, 4, 3, 2, or 1 amino acid variation) as compared with the HC CDR1 having the amino acid sequence of SEQ ID NO: 11, HC CDR2 having the amino acid sequence of SEQ ID NO: 12, and HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a LC CDR1, a LC CDR2, and a LC CDR3, which collectively contains no more than 5 amino acid variations (e.g., no more than 5, 4, 3, 2 or 1 amino acid variation) as compared with the LC CDR1 having the amino acid sequence of SEQ ID NO: 9, LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000309] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1, a HC CDR2, and a HC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the HC CDR1 having the amino acid sequence of SEQ ID NO: 11, HC CDR2 having the amino acid sequence of SEQ ID NO: 12, and HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a LC CDR1, a LC CDR2, and a LC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the to the LC CDR1 having the amino acid sequence of SEQ ID NO: 9, LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000310] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR1 having Docket No. A1361.70024WO00 14108730.1the amino acid sequence of SEQ ID NO: 11; a HC CDR2 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR2 having the amino acid sequence of SEQ ID NO: 12; and / or a HC CDR3 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a LC CDR1 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR1 having the amino acid sequence of SEQ ID NO: 9; a LC CDR2 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR2 having the amino acid sequence of SEQ ID NO: 5; and / or a LC CDR3 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000311] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1 at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the HC CDR1 having the amino acid sequence of SEQ ID NO: 11; a HC at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the HC CDR2 having the amino acid sequence of SEQ ID NO: 12; and / or a HC CDR3 at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a LC CDR1 at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the LC CDR1 having the amino acid sequence of SEQ ID NO: 9; a LC CDR2 at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the LC CDR2 having the amino acid sequence of SEQ ID NO: 5; and / or a LC CDR3 at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least Docket No. A1361.70024WO00 14108730.192%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000312] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a VH comprising the amino acid sequence of SEQ ID NO: 14. Alternatively or in addition a bispecific antibody described herein comprises a second antigen binding site comprising a VL comprising the amino acid sequence of SEQ ID NO: 10. In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a VH comprising the amino acid sequence of SEQ ID NO: 14, and a VL comprising the amino acid sequence of SEQ ID NO: 10. [000313] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a VH containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VH as set forth in SEQ ID NO: 14. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a VL containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VL as set forth in SEQ ID NO: 10. [000314] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a VH comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VH as set forth in SEQ ID NO: 14. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a VL comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VL as set forth in SEQ ID NO: 10. [000315] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a comprises a VH containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VH as set forth in SEQ ID NO: 14. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a VL containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid Docket No. A1361.70024WO00 14108730.1variation) as compared with the VL as set forth in SEQ ID NO: 10. In some embodiments, the number of amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) may occur within a VH of SEQ ID NO: 14 and / or a VL of SEQ ID NO: 10 excluding any of the CDR sequences therein. In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a heavy chain variable sequence that comprises a framework sequence that that contains no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation to the framework sequence of a VH of SEQ ID NO: 14, and / or a light chain variable sequence that comprises a framework sequence that that contains no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation to the framework sequence of a VL of SEQ ID NO: 10. [000316] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a VH comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VH as set forth in SEQ ID NO: 14. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a VL comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VL as set forth in SEQ ID NO: 10. In some embodiments, the degree of sequence variation (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) may occur within a VH of SEQ ID NO: 14, and / or a VL of SEQ ID NO: 10 excluding any of the CDR sequences therein. In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a heavy chain variable sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the framework sequence of a VH of SEQ ID NO: 14, and / or a light chain variable sequence that comprises a framework sequence that at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the framework sequence of a VL of SEQ ID NO: 10. Docket No. A1361.70024WO00 14108730.1[000317] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site that specifically binds to CD3. In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1, a HC CDR2 and a HC CDR3 of a heavy chain variable domain (VH) having the amino acid sequence of SEQ ID NO: 16. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a LC CDR1, a LC CDR2 and a LC CDR3 of a light chain variable domain (VL) having the amino acid sequence of SEQ ID NO: 10. [000318] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR3 having the amino acid sequence of SEQ ID NO: 13. In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1 having the amino acid sequence of SEQ ID NO: 1, a HC CDR2 having the amino acid sequence of SEQ ID NO: 15, and a HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, in some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a LC CDR1 having the amino acid sequence of SEQ ID NO: 9, a LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 having the amino acid sequence of SEQ ID NO: 6. In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1 having the amino acid sequence of SEQ ID NO: 1, a HC CDR2 having the amino acid sequence of SEQ ID NO: 15, a HC CDR3 having the amino acid sequence of SEQ ID NO: 13, a LC CDR1 having the amino acid sequence of SEQ ID NO: 9, a LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000319] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1, a HC CDR2, and a HC CDR3, which collectively contains no more than 5 amino acid variations (e.g., no more than 5, 4, 3, 2, or 1 amino acid variation) as compared with the HC CDR1 having the amino acid sequence of SEQ ID NO: 1, HC CDR2 having the amino acid sequence of SEQ ID NO: 15, and HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a LC CDR1, a LC CDR2, and a LC CDR3, which collectively contains no more than 5 amino acid variations (e.g., no more than 5, 4, 3, 2 or 1 amino acid variation) as compared with the LC CDR1 having the amino acid sequence of SEQ ID NO: 9, LC CDR2 having the amino acid Docket No. A1361.70024WO00 14108730.1sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000320] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1, a HC CDR2, and a HC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the HC CDR1 having the amino acid sequence of SEQ ID NO: 1, HC CDR2 having the amino acid sequence of SEQ ID NO: 15, and HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a LC CDR1, a LC CDR2, and a LC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the to the LC CDR1 having the amino acid sequence of SEQ ID NO: 9, LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000321] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR1 having the amino acid sequence of SEQ ID NO: 1; a HC CDR2 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR2 having the amino acid sequence of SEQ ID NO: 15; and / or a HC CDR3 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a LC CDR1 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR1 having the amino acid sequence of SEQ ID NO: 9; a LC CDR2 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR2 having the amino acid sequence of SEQ ID NO: 5; and / or a LC CDR3 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000322] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1 at least 80% (e.g., at least 80%, at least 85%, at Docket No. A1361.70024WO00 14108730.1least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the HC CDR1 having the amino acid sequence of SEQ ID NO: 1; a HC at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the HC CDR2 having the amino acid sequence of SEQ ID NO: 15; and / or a HC CDR3 at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a LC CDR1 at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the LC CDR1 having the amino acid sequence of SEQ ID NO: 9; a LC CDR2 at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the LC CDR2 having the amino acid sequence of SEQ ID NO: 5; and / or a LC CDR3 at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000323] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a VH comprising the amino acid sequence of SEQ ID NO: 16. Alternatively or in addition a bispecific antibody described herein comprises a second antigen binding site comprising a VL comprising the amino acid sequence of SEQ ID NO: 10. In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a VH comprising the amino acid sequence of SEQ ID NO: 16, and a VL comprising the amino acid sequence of SEQ ID NO: 10. [000324] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a VH containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VH as set forth in SEQ ID NO: 16. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a VL containing no more than 20 amino acid variations (e.g., no more than 20, Docket No. A1361.70024WO00 14108730.119, 18, 17, 16, 15, 14, 13, 12, 11, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VL as set forth in SEQ ID NO: 10. [000325] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a VH comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VH as set forth in SEQ ID NO: 16. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a VL comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VL as set forth in SEQ ID NO: 10. [000326] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a comprises a VH containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VH as set forth in SEQ ID NO: 16. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a VL containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VL as set forth in SEQ ID NO: 10. In some embodiments, the number of amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) may occur within a VH of SEQ ID NO: 16 and / or a VL of SEQ ID NO: 10 excluding any of the CDR sequences therein. In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a heavy chain variable sequence that comprises a framework sequence that that contains no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation to the framework sequence of a VH of SEQ ID NO: 16, and / or a light chain variable sequence that comprises a framework sequence that that contains no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation to the framework sequence of a VL of SEQ ID NO: 10. [000327] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a VH comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical Docket No. A1361.70024WO00 14108730.1to the VH as set forth in SEQ ID NO: 16. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a VL comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VL as set forth in SEQ ID NO: 10. In some embodiments, the degree of sequence variation (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) may occur within a VH of SEQ ID NO: 16, and / or a VL of SEQ ID NO: 10 excluding any of the CDR sequences therein. In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a heavy chain variable sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the framework sequence of a VH of SEQ ID NO: 16, and / or a light chain variable sequence that comprises a framework sequence that at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the framework sequence of a VL of SEQ ID NO: 10. [000328] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site that specifically binds to CD3. In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1, a HC CDR2 and a HC CDR3 of a heavy chain variable domain (VH) having the amino acid sequence of SEQ ID NO: 18. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a LC CDR1, a LC CDR2 and a LC CDR3 of a light chain variable domain (VL) having the amino acid sequence of SEQ ID NO: 8. [000329] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR3 having the amino acid sequence of SEQ ID NO: 13. In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1 having the amino acid sequence of SEQ ID NO: 1, a HC CDR2 having the amino acid sequence of SEQ ID NO: 17, and a HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, in some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a LC CDR1 having the amino acid sequence of SEQ ID NO: 4, a LC CDR2 having the amino acid Docket No. A1361.70024WO00 14108730.1sequence of SEQ ID NO: 5, and a LC CDR3 having the amino acid sequence of SEQ ID NO: 6. In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1 having the amino acid sequence of SEQ ID NO: 1, a HC CDR2 having the amino acid sequence of SEQ ID NO: 17, a HC CDR3 having the amino acid sequence of SEQ ID NO: 13, a LC CDR1 having the amino acid sequence of SEQ ID NO: 4, a LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000330] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1, a HC CDR2, and a HC CDR3, which collectively contains no more than 5 amino acid variations (e.g., no more than 5, 4, 3, 2, or 1 amino acid variation) as compared with the HC CDR1 having the amino acid sequence of SEQ ID NO: 1, HC CDR2 having the amino acid sequence of SEQ ID NO: 17, and HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a LC CDR1, a LC CDR2, and a LC CDR3, which collectively contains no more than 5 amino acid variations (e.g., no more than 5, 4, 3, 2 or 1 amino acid variation) as compared with the LC CDR1 having the amino acid sequence of SEQ ID NO: 4, LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000331] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1, a HC CDR2, and a HC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the HC CDR1 having the amino acid sequence of SEQ ID NO: 1, HC CDR2 having the amino acid sequence of SEQ ID NO: 17, and HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a LC CDR1, a LC CDR2, and a LC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the to the LC CDR1 having the amino acid sequence of SEQ ID NO: 4, LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6. Docket No. A1361.70024WO00 14108730.1[000332] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR1 having the amino acid sequence of SEQ ID NO: 1; a HC CDR2 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR2 having the amino acid sequence of SEQ ID NO: 17; and / or a HC CDR3 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a LC CDR1 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR1 having the amino acid sequence of SEQ ID NO: 4; a LC CDR2 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR2 having the amino acid sequence of SEQ ID NO: 5; and / or a LC CDR3 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000333] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1 at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the HC CDR1 having the amino acid sequence of SEQ ID NO: 1; a HC at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the HC CDR2 having the amino acid sequence of SEQ ID NO: 17; and / or a HC CDR3 at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a LC CDR1 at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the LC CDR1 having the amino acid sequence of SEQ ID NO: 4; a LC CDR2 at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or Docket No. A1361.70024WO00 14108730.1100%) identical to the LC CDR2 having the amino acid sequence of SEQ ID NO: 5; and / or a LC CDR3 at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000334] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a VH comprising the amino acid sequence of SEQ ID NO: 18. Alternatively or in addition a bispecific antibody described herein comprises a second antigen binding site comprising a VL comprising the amino acid sequence of SEQ ID NO: 8. In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a VH comprising the amino acid sequence of SEQ ID NO: 18 and a VL comprising the amino acid sequence of SEQ ID NO: 8. [000335] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a VH containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VH as set forth in SEQ ID NO: 18. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a VL containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VL as set forth in SEQ ID NO: 8. [000336] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a VH comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VH as set forth in SEQ ID NO: 18. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a VL comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VL as set forth in SEQ ID NO: 8. [000337] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a comprises a VH containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VH as set forth in SEQ ID NO: 18. Alternatively or in addition, a bispecific antibody described herein comprises a second Docket No. A1361.70024WO00 14108730.1antigen binding site comprising a VL containing no more than 20 amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) as compared with the VL as set forth in SEQ ID NO: 8. In some embodiments, the number of amino acid variations (e.g., no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation) may occur within a VH of SEQ ID NO: 18 and / or a VL of SEQ ID NO: 8 excluding any of the CDR sequences therein. In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a heavy chain variable sequence that comprises a framework sequence that that contains no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation to the framework sequence of a VH of SEQ ID NO: 18, and / or a light chain variable sequence that comprises a framework sequence that that contains no more than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid variation to the framework sequence of a VL of SEQ ID NO: 8. [000338] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a VH comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VH as set forth in SEQ ID NO: 18. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a VL comprising an amino acid sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VL as set forth in SEQ ID NO: 8. In some embodiments, the degree of sequence variation (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) may occur within a VH of SEQ ID NO: 18, and / or a VL of SEQ ID NO: 8 excluding any of the CDR sequences therein. In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a heavy chain variable sequence that is at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the framework sequence of a VH of SEQ ID NO: 18, and / or a light chain variable sequence that comprises a framework sequence that at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at Docket No. A1361.70024WO00 14108730.1least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the framework sequence of a VL of SEQ ID NO: 8. [000339] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site that specifically binds to CD3. In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1, a HC CDR2 and a HC CDR3 of a heavy chain variable domain (VH) having the amino acid sequence of SEQ ID NO: 18. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a LC CDR1, a LC CDR2 and a LC CDR3 of a light chain variable domain (VL) having the amino acid sequence of SEQ ID NO: 10. [000340] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR3 having the amino acid sequence of SEQ ID NO: 13. In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1 having the amino acid sequence of SEQ ID NO: 1, a HC CDR2 having the amino acid sequence of SEQ ID NO: 17, and a HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, in some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a LC CDR1 having the amino acid sequence of SEQ ID NO: 9, a LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 having the amino acid sequence of SEQ ID NO: 6. In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1 having the amino acid sequence of SEQ ID NO: 1, a HC CDR2 having the amino acid sequence of SEQ ID NO: 17, a HC CDR3 having the amino acid sequence of SEQ ID NO: 13, a LC CDR1 having the amino acid sequence of SEQ ID NO: 9, a LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000341] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1, a HC CDR2, and a HC CDR3, which collectively contains no more than 5 amino acid variations (e.g., no more than 5, 4, 3, 2, or 1 amino acid variation) as compared with the HC CDR1 having the amino acid sequence of SEQ ID NO: 1, HC CDR2 having the amino acid sequence of SEQ ID NO: 17, and HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a LC CDR1, a LC CDR2, and a LC CDR3, which collectively contains no more than 5 amino acid Docket No. A1361.70024WO00 14108730.1variations (e.g., no more than 5, 4, 3, 2 or 1 amino acid variation) as compared with the LC CDR1 having the amino acid sequence of SEQ ID NO: 9, LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000342] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1, a HC CDR2, and a HC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the HC CDR1 having the amino acid sequence of SEQ ID NO: 1, HC CDR2 having the amino acid sequence of SEQ ID NO: 17, and HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a LC CDR1, a LC CDR2, and a LC CDR3 that collectively are at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the to the LC CDR1 having the amino acid sequence of SEQ ID NO: 9, LC CDR2 having the amino acid sequence of SEQ ID NO: 5, and LC CDR3 having the amino acid sequence of SEQ ID NO: 6. [000343] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR1 having the amino acid sequence of SEQ ID NO: 1; a HC CDR2 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR2 having the amino acid sequence of SEQ ID NO: 17; and / or a HC CDR3 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the HC CDR3 having the amino acid sequence of SEQ ID NO: 13. Alternatively or in addition, a bispecific antibody described herein comprises a second antigen binding site comprising a LC CDR1 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR1 having the amino acid sequence of SEQ ID NO: 9; a LC CDR2 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR2 having the amino acid sequence of SEQ ID NO: 5; and / or a LC CDR3 having no more than 3 amino acid variations (e.g., no more than 3, 2, or 1 amino acid variation) as compared with the LC CDR3 having the amino acid sequence of SEQ ID NO: 6. Docket No. A1361.70024WO00 14108730.1[000344] In some embodiments, a bispecific antibody described herein comprises a second antigen binding site comprising a HC CDR1 at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the HC CDR1 having the amino acid sequence of SEQ ID NO: 1; a HC at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the HC CDR2 having the amino acid sequence of SEQ ID NO: 17; and / or a HC CDR3 at least 80% (e.g., at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94...

Claims

1. CLAIMS What is claimed is:

1. An antibody that specifically binds CD3 comprising: a heavy chain complementarity determining region 1 (HC CDR1), a heavy chain complementarity determining region 2 (HC CDR2), and a heavy chain complementarity region 3 (HC CDR3) of a heavy chain variable region (VH) comprising the amino acid sequence of SEQ ID NO: 18; and a light chain complementarity determining region (LC CDR1), a light chain complementarity determining region 2 (LC CDR2), and a light chain complementarity determining region 3 (LC CDR3) of a light chain variable region (VL) comprising the amino acid sequence of SEQ ID NO:

19.

2. An antibody that specifically binds CD3 comprising: a heavy chain complementarity determining region (HC CDR1) comprising the amino acid sequence of SEQ ID NO: 1, a heavy chain complementarity determining region 2 (HC CDR2) comprising the amino acid sequence of SEQ ID NO: 17, a heavy chain complementarity determining region 3 (HC CDR3) comprising the amino acid sequence of SEQ ID NO: 13, a light chain complementarity determining region 1 (LC CDR1) comprising the amino acid sequence of SEQ ID NO: 4, a light chain complementarity determining region 2 (LC CDR2) comprising the amino acid sequence of SEQ ID NO: 5, and a light chain complementarity determining region 3 (LC CDR3) comprising the amino acid sequence of SEQ ID NO:

6.

3. An antibody that specifically binds CD3 comprising: a heavy chain complementarity determining region 1 (HC CDR1) comprising the amino acid sequence TYAMX1 (SEQ ID NO: 20), wherein X1 is N or H; a heavy chain complementarity determining region 2 (HC CDR2) comprising the amino acid sequence RIRSKYNNYATX2YAX3SVKX4 (SEQ ID NO: 21), wherein: X2 is Y, E, or A, X3is D or A, and X4is G or D; a heavy chain complementarity determining region 3 (HC CDR3) comprising the amino acid sequence HGNFGNSYVSX5FAY (SEQ ID NO: 22), wherein X5 is W or Y; Docket No. A1361.70024WO00 14108730.1 a light chain complementarity determining region 1 (LC CDR1) comprising the amino acid sequence X6SSTGAVTTSNYAN (SEQ ID NO: 23), wherein X6 is R or S; a light chain complementarity determining region 2 (LC CDR2) comprising the amino acid sequence GTNKRAP (SEQ ID NO: 5); and a light chain complementarity determining region 3 (LC CDR3) comprising the amino acid sequence ALWYSNLWV (SEQ ID NO: 6).

4. An antibody that specifically binds CD3 comprising a human immunoglobulin kappa variable 4-1 (IGKV4-1) light chain, wherein the IGKV4-1 light chain comprises: a light chain complementarity determining region 1 (LC CDR1) comprising the amino acid sequence X6SSTGAVTTSNYAN (SEQ ID NO: 23), wherein X6is R or S; a light chain complementarity determining region 2 (LC CDR2) comprising the amino acid sequence GTNKRAP (SEQ ID NO: 5); and a light chain complementarity determining region 3 (LC CDR3) comprising the amino acid sequence ALWYSNLWV (SEQ ID NO: 6).

5. An antibody that specifically binds CD3 comprising: (a) a heavy chain complementarity determining region 1 (HC CDR1), a heavy chain complementarity determining region 2 (HC CDR2), and a heavy chain complementarity determining region 3 (HC CDR3) of a heavy chain variable region (VH) comprising the amino acid sequence of SEQ ID NO: 7; and a light chain complementarity determining region 1 (LC CDR1), a light chain complementarity determining region 2 (LC CDR2), and a light chain complementarity determining region 3 (LC CDR3) of a light chain variable region (VL) comprising the amino acid sequence of SEQ ID NO: 10; (b) a HC CDR1, HC CDR2, and a HC CDR3 of a VH comprising the amino acid sequence of SEQ ID NO: 14; and a LC CDR1, a LC CDR2, and a LC CDR3 of a VL comprising the amino acid sequence of SEQ ID NO: 10; (c) a HC CDR1, HC CDR2, and a HC CDR3 of a VH comprising the amino acid sequence of SEQ ID NO: 16; and a LC CDR1, a LC CDR2, and a LC CDR3 of a VL comprising the amino acid sequence of SEQ ID NO: 10; (d) a HC CDR1, HC CDR2, and a HC CDR3 of a VH comprising the amino acid sequence of SEQ ID NO: 18; and a LC CDR1, a LC CDR2, and a LC CDR3 of a VL comprising the amino acid sequence of SEQ ID NO: 8; Docket No. A1361.70024WO00 14108730.1 (e) a HC CDR1, HC CDR2, and a HC CDR3 of a VH comprising the amino acid sequence of SEQ ID NO: 18; and a LC CDR1, a LC CDR2, and a LC CDR3 of a VL comprising the amino acid sequence of SEQ ID NO: 10; (f) a HC CDR1, HC CDR2, and a HC CDR3 of a VH comprising the amino acid sequence of SEQ ID NO: 24; and a LC CDR1, a LC CDR2, and a LC CDR3 of a VL comprising the amino acid sequence of SEQ ID NO: 8; (g) a HC CDR1, HC CDR2, and a HC CDR3 of a VH comprising the amino acid sequence of SEQ ID NO: 24; and a LC CDR1, a LC CDR2, and a LC CDR3 of a VL comprising the amino acid sequence of SEQ ID NO: 10; (h) a HC CDR1, HC CDR2, and a HC CDR3 of a VH comprising the amino acid sequence of SEQ ID NO: 14; and a LC CDR1, a LC CDR2, and a LC CDR3 of a VL comprising the amino acid sequence of SEQ ID NO: 19; or (i) a HC CDR1, HC CDR2, and a HC CDR3 of a VH comprising the amino acid sequence of SEQ ID NO: 16; and a LC CDR1, a LC CDR2, and a LC CDR3 of a VL comprising the amino acid sequence of SEQ ID NO:

19.

6. An antibody that specifically binds CD3 comprising: (a) a HC CDR1 comprising the amino acid sequence of SEQ ID NO: 1, a HC CDR2 comprising the amino acid sequence of SEQ ID NO: 2, a HC CDR3 comprising the amino acid sequence of SEQ ID NO: 3, a LC CDR1 comprising the amino acid sequence of SEQ ID NO: 9, a LC CDR2 comprising the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 comprising the amino acid sequence of SEQ ID NO: 6; or (b) a HC CDR1 comprising the amino acid sequence of SEQ ID NO: 11, a HC CDR2 comprising the amino acid sequence of SEQ ID NO: 12, a HC CDR3 comprising the amino acid sequence of SEQ ID NO: 13, a LC CDR1 comprising the amino acid sequence of SEQ ID NO: 9, a LC CDR2 comprising the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 comprising the amino acid sequence of SEQ ID NO: 6; (c) a HC CDR1 comprising the amino acid sequence of SEQ ID NO: 1, a HC CDR2 comprising the amino acid sequence of SEQ ID NO: 15, a HC CDR3 comprising the amino acid sequence of SEQ ID NO: 13, a LC CDR1 comprising the amino acid sequence of SEQ ID NO: 9, a LC CDR2 comprising the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 comprising the amino acid sequence of SEQ ID NO: 6; Docket No. A1361.70024WO00 14108730.1 (d) a HC CDR1 comprising the amino acid sequence of SEQ ID NO: 1, a HC CDR2 comprising the amino acid sequence of SEQ ID NO: 17, a HC CDR3 comprising the amino acid sequence of SEQ ID NO: 13, a LC CDR1 comprising the amino acid sequence of SEQ ID NO: 4, a LC CDR2 comprising the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 comprising the amino acid sequence of SEQ ID NO: 6; (e) a HC CDR1 comprising the amino acid sequence of SEQ ID NO: 1, a HC CDR2 comprising the amino acid sequence of SEQ ID NO: 17, a HC CDR3 comprising the amino acid sequence of SEQ ID NO: 13, a LC CDR1 comprising the amino acid sequence of SEQ ID NO: 9, a LC CDR2 comprising the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 comprising the amino acid sequence of SEQ ID NO: 6; (f) a HC CDR1 comprising the amino acid sequence of SEQ ID NO: 1, a HC CDR2 comprising the amino acid sequence of SEQ ID NO: 17, a HC CDR3 comprising the amino acid sequence of SEQ ID NO: 13, a LC CDR1 comprising the amino acid sequence of SEQ ID NO: 4, a LC CDR2 comprising the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 comprising the amino acid sequence of SEQ ID NO: 6; (g) a HC CDR1 comprising the amino acid sequence of SEQ ID NO: 1, a HC CDR2 comprising the amino acid sequence of SEQ ID NO: 17, a HC CDR3 comprising the amino acid sequence of SEQ ID NO: 13, a LC CDR1 comprising the amino acid sequence of SEQ ID NO: 9, a LC CDR2 comprising the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 comprising the amino acid sequence of SEQ ID NO: 6; (h) a HC CDR1 comprising the amino acid sequence of SEQ ID NO: 1, a HC CDR2 comprising the amino acid sequence of SEQ ID NO: 12, a HC CDR3 comprising the amino acid sequence of SEQ ID NO: 13, a LC CDR1 comprising the amino acid sequence of SEQ ID NO: 4, a LC CDR2 comprising the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 comprising the amino acid sequence of SEQ ID NO: 6; or (i) a HC CDR1 comprising the amino acid sequence of SEQ ID NO: 1, a HC CDR2 comprising the amino acid sequence of SEQ ID NO: 15, a HC CDR3 comprising the amino acid sequence of SEQ ID NO: 13, a LC CDR1 comprising the amino acid sequence of SEQ ID NO: 4, a LC CDR2 comprising the amino acid sequence of SEQ ID NO: 5, and a LC CDR3 comprising the amino acid sequence of SEQ ID NO:

6.

7. The antibody of claim 5 or 6, wherein the antibody comprises: Docket No. A1361.70024WO00 14108730.1 (a) a VH comprising the amino acid of SEQ ID NO: 7, and / or a VL comprising the amino acid sequence of SEQ ID NO: 10; (b) a VH comprising the amino acid of SEQ ID NO: 14, and / or a VL comprising the amino acid sequence of SEQ ID NO: 10; (c) a VH comprising the amino acid of SEQ ID NO: 16, and / or a VL comprising the amino acid sequence of SEQ ID NO: 10; (d) a VH comprising the amino acid of SEQ ID NO: 18, and / or a VL comprising the amino acid sequence of SEQ ID NO: 8; (e) a VH comprising the amino acid of SEQ ID NO: 18, and / or a VL comprising the amino acid sequence of SEQ ID NO: 10; (f) a VH comprising the amino acid of SEQ ID NO: 24, and / or a VL comprising the amino acid sequence of SEQ ID NO: 8; (g) a VH comprising the amino acid of SEQ ID NO: 24, and / or a VL comprising the amino acid sequence of SEQ ID NO: 10; (h) a VH comprising the amino acid of SEQ ID NO: 14, and / or a VL comprising the amino acid sequence of SEQ ID NO: 19; (i) a VH comprising the amino acid of SEQ ID NO: 16, and / or a VL comprising the amino acid sequence of SEQ ID NO:

19.

8. The antibody of any one of claims 1-7, wherein the antibody is a full-length IgG, a Fab fragment, a F(ab') fragment, a F(ab’)2 fragment, a scFv, or a Fv.

9. The antibody of any one of claims 1-8, wherein the antibody comprises a heavy chain constant region of the isotype IgG1, IgG2, IgG3, or IgG4.

10. An isolated nucleic acid encoding the VH and / or VL of the antibody of any one of claims 1-9 11. The isolated nucleic acid of claim 10, wherein the isolated nucleic acid comprises the nucleic acid sequence of SEQ ID NO: 31, and / or the nucleic acid sequence of SEQ ID NO:

40. Docket No. A1361.70024WO00 14108730.

112. The isolated nucleic acid of claim 10, wherein the isolated nucleic acid comprises: (a) the nucleic acid sequence of SEQ ID NO: 25, and / or the nucleic acid sequence of SEQ ID NO: 26; (b) the nucleic acid sequence of SEQ ID NO: 27, and / or the nucleic acid sequence of SEQ ID NO: 26; (c) the nucleic acid sequence of SEQ ID NO: 29, and / or the nucleic acid sequence of SEQ ID NO: 26; (d) the nucleic acid sequence of SEQ ID NO: 31, and / or the nucleic acid sequence of SEQ ID NO: 32; (e) the nucleic acid sequence of SEQ ID NO: 31, and / or the nucleic acid sequence of SEQ ID NO: 26; (f) the nucleic acid sequence of SEQ ID NO: 35, and / or the nucleic acid sequence of SEQ ID NO: 32; (g) the nucleic acid sequence of SEQ ID NO: 35, and / or the nucleic acid sequence of SEQ ID NO: 26; (h) the nucleic acid sequence of SEQ ID NO: 27, and / or the nucleic acid sequence of SEQ ID NO: 40; or (i) the nucleic acid sequence of SEQ ID NO: 29, and / or the nucleic acid sequence of SEQ ID NO:

40.

13. An expression vector comprising the isolated nucleic acid of any one of claims 10-12.

14. A host cell comprising the antibody of any one of claims 1-9, the isolated nucleic acid of any one of claims 10-12, or the expression vector of claim 13.

15. An engineered cell expressing the antibody of any one of claims 1-9.

16. The engineered cell of claim 15, wherein the engineered cell is a T cell, a NK cell, or a NKT cell.

17. A composition comprising the antibody of any one of claims 1-9, the isolated nucleic acid of claim 10-12, the expression vector of claim 13, the host cell of claim 14, or the engineered cell of claim 15 or 16. Docket No. A1361.70024WO00 14108730.

118. The composition of claim 17, further comprising a pharmaceutically acceptable carrier.

19. A bispecific antibody comprising a first antigen binding site and a second antigen binding site, wherein the second antigen binding site comprises the antibody of any one of claims 1-9.

20. The bispecific antibody of claim 19, wherein the first antigen binding site specifically binds to a cancer antigen, a pathogen-derived antigen, or a B cell antigen.

21. The bispecific antibody of claim 19, wherein the first antigen binding site specifically binds to a cancer antigen.

22. The bispecific antibody of claim 21, wherein the cancer antigen is selected from WT1, PRAME, DLL3, CD70, Claudin18.2, MSLN, MAGE-A1, MAGE-A3, MAGE-A4, MAGE- A8, CD38, and BCMA.

23. The bispecific antibody of claim 22, wherein the cancer antigen is WT1.

24. The bispecific antibody of claim 22, wherein the cancer antigen is PRAME.

25. The bispecific antibody of claim 22, wherein the cancer antigen is DLL3.

26. The bispecific antibody of claim 22, wherein the cancer antigen is CD70.

27. The bispecific antibody of claim 22, wherein the cancer antigen is Claudin18.

2.

28. The bispecific antibody of claim 222wherein the cancer antigen is MSLN.

29. The bispecific antibody of claim 22, wherein the cancer antigen is MAGE-A4 30. The bispecific antibody of claim 22, wherein the cancer antigen is MAGE-A8. Docket No. A1361.70024WO00 14108730.

131. The bispecific antibody of claim 22, wherein the cancer antigen is CD38.

32. The bispecific antibody of claim 22, wherein the cancer antigen is BCMA.

33. The bispecific antibody of claim 19, wherein the first antigen binding site specifically binds a pathogen-derived antigen.

34. The bispecific antibody of claim 33, wherein the pathogen-derived antigen is a viral antigen.

35. The bispecific antibody of claim 34, wherein the viral antigen is an HIV antigen, an influenza antigen, an HPV antigen, or a Zika virus antigen.

36. The bispecific antibody of claim 33, wherein the pathogen-derived antigen is a bacterial antigen.

37. The bispecific antibody of claim 36, wherein the bacterial antigen is a Staphylococcus species antigen or a Pseudomonas species antigen.

38. The bispecific antibody of claim 33, wherein the pathogen-derived antigen is a parasitic antigen.

39. The bispecific antibody of claim 38, wherein the parasitic antigen is a Plasmodium species antigen, a Trypanosoma species antigen, or a Schistosoma species antigen.

40. The bispecific antibody of claim 19, wherein the first antigen binding site specifically binds a B cell antigen.

41. The bispecific antibody of claim 40, wherein the B cell antigen is CD19, CD22, or CD79. Docket No. A1361.70024WO00 14108730.

142. The bispecific antibody of any one of claims 19-41, wherein the bispecific antibody comprises a first arm that is configured as a Fab, a Fab’, or a scFv and that comprises the first antigen binding site.

43. The bispecific antibody of any one of claims 19-41, wherein the bispecific antibody comprises a second arm that is configured as a Fab, a Fab’, or a scFv and that comprises the first antigen binding site.

44. The bispecific antibody of any one of claims 19-41, wherein the bispecific antibody comprises a first arm that is configured as a Fab and a second arm that is configured as a scFv.

45. The bispecific antibody of any one of claims 19-41, wherein the bispecific antibody comprises a first arm that is configured as a scFv and a second arm that is configured as a Fab.

46. The bispecific antibody of any one of claims 19-45, wherein the ratio between the first antigen binding site and the second antigen binding site is 1:1, 1:2, 1:3, 2:1 or 3:

1.

47. A host cell comprising the bispecific antibody of any one of claims 19-46.

48. A composition comprising the bispecific antibody of any one of claims 19-46.

49. The composition of claim 48, further comprising a pharmaceutically acceptable carrier.

50. A method of treating cancer, the method comprising administering to a subject in need thereof an effective amount of the antibody of any one of claims 1-9, the engineered cell of claim 15 or 16, the composition of any one of claims 17, 18, 48, or 49, or the bispecific antibody of any one of claims 19-33 or 42-46.

56. A method of treating infection, the method comprising administering to a subject in need thereof an effective amount of the antibody of any one of claims 1-9, the engineered cell Docket No. A1361.70024WO00 14108730.1of claim 15 or 16, the composition of any one of claims 17, 18, 48, or 49, or the bispecific antibody of any one of claims 19, 20, 33-39, or 43-46.

57. A method of treating an autoimmune disorder, the method comprising administering to a subject in need thereof an effective amount of the antibody of anyone one of claims 1-9, the engineered cell of claim 15 or 16, the composition of any one of claims 17, 18, 48, or 49, or the bispecific antibody of any one of claims 19, 20, or 41-46. Docket No. A1361.70024WO00 14108730.1

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