Antigen-binding polypeptide complexes containing the extracellular domain of a TNFSF ligand

Abstract

Disclosed are antigen-binding polypeptide complexes (e.g., antibodies and antigen-binding fragments thereof) having certain structural characteristics. Also disclosed are polynucleotides and vectors encoding such polypeptide complexes; cells, pharmaceutical compositions, and kits containing such polypeptide complexes; and methods of using such polypeptide complexes.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 291,305, filed December 17, 2021, which is incorporated by reference in its entirety.

[0002] Reference to Electronically Submitted Sequence Listings The contents of the electronically submitted sequence listing (Name: 4850_008PC02_Seqlisting_ST26; Size: 699,814 bytes; Creation Date: December 13, 2022) are incorporated by reference in their entirety into this specification.

[0003] Field The present disclosure relates to antigen-binding polypeptide complexes (e.g., antibodies and antigen-binding fragments thereof) containing the extracellular domain of a tumor necrosis factor superfamily (TNFSF) ligand. The present disclosure also relates to polynucleotides and vectors encoding such polypeptide complexes, cells, pharmaceutical compositions, and kits containing such polypeptide complexes; and methods of using such polypeptide complexes. [Background technology]

[0004] background T cells are a subtype of white blood cells that play a key role in the immune system and in fighting cancer. Cancer cell antigens are presented by antigen-presenting cells (APCs), which activate T cells to recognize and kill cancer cells. T cell activation requires two signaling events: (i) primary signaling through peptide-bearing major histocompatibility complex (MHC) complexes on APCs and T cell receptor (TCR) complexes on T cells, and (ii) costimulatory signaling by members of the CD28 family or tumor necrosis factor receptor superfamily (TNFRSF). The costimulatory signaling pathways are complementary to each other, as CD28 is the major costimulatory pathway on naive T cells, whereas TNFRSF plays a more important role in antigen-experienced or memory T cells.

[0005] Treating T cells with anti-CD3 and anti-CD28 antibodies generates a costimulatory signal that engages the TCR and can be utilized for antigen-induced T cell activation. CD3 is a conserved member of the TCR complex, so the primary T cell activation signal is often provided by anti-CD3 antibodies. The second signal is then often provided by anti-CD28 antibodies or CD28 ligands (such as B7.1, B7.2, etc.) and anti-TNF receptor (TNFR) members or their ligands. TNFRSF members such as OX40 and 4-1BB have been heavily studied for the development of biotherapeutics for cancer immunomodulation and immunotherapy, using either antagonist or agonist approaches.

[0006] Except for CD27, which is constitutively expressed on naive T cells, other TNFRSFs are expressed only upon T cell activation. In addition, memory T cells and regulatory T cells (Tregs) also constitutively express some family members. These expression patterns suggest that the TNFRSF / TNFSF axis may be important in regulating effector and memory responses. Co-signaling receptors, especially TNFRSF co-stimulatory receptors, play a major role in regulating effector T cell responses. Co-stimulation via CD27, OX40, and DR3 promotes the proliferation and survival of both CD4+ and CD8+ effector T cells, whereas co-stimulation via 4-1BB and GITR preferentially promotes the expansion and survival of CD8+ effector T cells.

[0007] OX40 is activated through binding with its ligand OX40L, and 4-1BB signals through binding with its ligand 4-1BBL. OX40L and 4-1BBL are trimeric molecules and can form homotrimeric complexes with trimeric OX40 or 4-1BB on T cells.

[0008] TNFSF-mediated costimulation has been highlighted as a promising strategy to support antitumor immune responses. However, there is still a need for bispecific and multispecific antibodies that can bind to specific target molecules or combinations of target molecules and activate T cells more effectively in antitumor immune responses. There is also a need for bispecific and multispecific antibodies that can provide high efficacy while at the same time providing a broader therapeutic window and better tolerability. Summary of the Invention

[0009] overview Provided herein is an antigen-binding polypeptide complex comprising a first polypeptide, a second polypeptide, and a third polypeptide, wherein the first polypeptide has a structure represented by VL1-L1-CL; VL1-L1-CH1; VH1-L1-CL; or VH1-L1-CH1; (i) the second polypeptide has a structure represented by VH1-L2-CH1-L3-Fc-L4-TNF1-L5-TNF2-L6-TNF3; 1-L2-CL-L3-Fc-L4-TNF1-L5-TNF2-L6-TNF3;VH1-L7-CH1-L8-Fc;VH1-L7-CL-L8-Fc;VL1-L2-CH1-L3-Fc-L4-TNF1 -L5-TNF2-L6-TNF3;VL1-L2-CL-L3-Fc-L4-TNF1-L5-TNF2-L6-TNF3;VL1-L7-CH1-L8-Fc; or by VL1-L7-CL-L8-Fc. and the third polypeptide has a structure represented by VH1-L19-CH1-L20-Fc-L21-TNF1-L22-TNF2-L23-TNF3; or VH2-L14-VL2-L15-Fc-L16-TNF1-L17-TNF2-L18-TNF3; or (ii) the second polypeptide has a structure represented by VH1-L19-CH1-L20-Fc-L21-TNF1-L22-TNF2-L24-TNF3; 3-TNF3; VH1-L19-CL-L20-Fc-L21-TNF1-L22-TNF2-L23-TNF3; VL1-L19-CH1-L20-Fc-L21-TNF1-L22-TNF2-L23-TNF3; or VL1-L19-CL-L20-Fc-L21-TNF1-L22-TNF2-L23-TNF3, and the third polypeptide is VL2-L24-VH2-L25-Fc;or an antigen-binding polypeptide complex having a structure represented by VH2-L26-VL2-L27-Fc, wherein VL1 is a first immunoglobulin light chain variable region, VL2 is a second immunoglobulin light chain variable region, VH1 is a first immunoglobulin heavy chain variable region, VH2 is a second immunoglobulin heavy chain variable region, Fc is a region comprising immunoglobulin heavy chain constant region 2 (CH2), immunoglobulin heavy chain constant region 3 (CH3), and optionally an immunoglobulin hinge, CH1 is immunoglobulin heavy chain constant region 1, CL is an immunoglobulin light chain constant region, TNF1 is a first extracellular domain of a tumor necrosis factor superfamily (TNFSF) ligand, TNF2 is a second extracellular domain of the TNFSF ligand, and TNF3 is a third extracellular domain of the TNFSF ligand, and L1 to L27 are amino acid linkers. ;

[0010] Provided herein is an antigen-binding polypeptide complex comprising a first polypeptide, a second polypeptide, and a third polypeptide, wherein the first polypeptide has a structure represented by VL1-L1-CL; VL1-L1-CH1; VH1-L1-CL; or VH1-L1-CH1; (i) the second polypeptide is selected from the group consisting of VH1-CH1-L2-Fc-L3-TNF1-L4-TNF2-L5-TNF3; VH1-CL-L2-Fc-L3-TNF1-L4-TNF2-L5-TNF3; VH1-CH1-L6-Fc; VH1-CL-L7-Fc; VL1-CH1-L2-Fc-L3-TNF1-L4-TNF2-L5-TNF3; VL1-CL-L2-Fc-L3-TNF1-L4-TNF2-L5-TNF3; L5-TNF3; VL1-CH1-L6-Fc; or VL1-CL-L7-Fc, and the third polypeptide is VL2-L8-VH2-L9-Fc-L10-TNF1-L11-TNF2-L12-TNF3; or VH2-L13-VL2-L14-Fc-L15-TNF1-L16-TNF2-L17-TNF3. or (ii) the second polypeptide has a structure represented by: VH1-CH1-L18-Fc-L19-TNF1-L20-TNF2-L21-TNF3; VH1-CL-L18-Fc-L19-TNF1-L20-TNF2-L21-TNF3; VL1-CH1-L18-Fc-L19-TNF1-L20-TNF2-L21-TNF3;or VL1-CL-L18-Fc-L19-TNF1-L20-TNF2-L21-TNF3, and the third polypeptide has a structure represented by VL2-L22-VH2-L23-Fc or VH2-L24-VL2-L25-Fc, where VL1 is a first immunoglobulin light chain variable region, VL2 is a second immunoglobulin light chain variable region, VH1 is a first immunoglobulin heavy chain variable region, VH2 is a second immunoglobulin heavy chain variable region, and Fc is an immunoglobulin heavy chain constant region. wherein CH1 is an immunoglobulin heavy chain constant region 1, CL is an immunoglobulin light chain constant region, TNF1 is a first extracellular domain of a tumor necrosis factor superfamily (TNFSF) ligand, TNF2 is a second extracellular domain of the TNFSF ligand, TNF3 is a third extracellular domain of the TNFSF ligand, and L1-L25 are amino acid linkers;

[0011] Provided herein is an antigen-binding polypeptide complex comprising a first polypeptide and a second polypeptide, wherein (i) the first polypeptide is selected from the group consisting of VL1-L1-VH1-L2-Fc; VH1-L3-VL1-L4-Fc; VL1-L5-VH1-L6-CL-L7-CH1-L8-Fc; VL1-L5-VH1-L6-CH1-L7-CL-L8-Fc; VH1-L5-VL1-L6-CL-L7-CH1-L8-Fc; VH1-L5-VL1-L6-CL-L7-CH1-L8-Fc; VH1-L5-VL1-L6-CH1-L7-CL-L8-Fc; VL1-L9-CL-L10- VH1-L11-CH1-L12-Fc;VL1-L9-CH1-L10-VH1-L11-CL-L12-Fc;VH1-L9-CL-L10-VL1-L11-CH1-L12-Fc;VH1-L9-CH1-L10-VL1-L11-CL-L12-Fc; VL1-L13-VH1-L14-Fc-L15-TNF1-L16-TNF2-L17-TNF3;VH1-L18-VL1-L19-Fc-L20-TNF1-L21-TNF2-L22-TNF3;VL1-L23-VH1-L24-CL-L25-CH1 -L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-L23-VH1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-L23-VL1-L24-CL-L25 -CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-L23-VL1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-VH1-L14-Fc-L15 -TNF1-L16-TNF2-L17-TNF3;VH1-VL1-L19-Fc-L20-TNF1-L21-TNF2-L22-TNF3;VL1-VH1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29- TNF3;VL1-VH1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-VL1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-VL1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3; F3;VL1-L30-CH1-L31-VH1-L32-CL-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3; -L36-TNF3; L35-TNF2-L36-TNF3 contains the 2-dimensional matrix VL2-L37-VH2-L3 8-Fc-L39-TNF1-L40-TNF2-L41-TNF3;VH2-L42-VL2-L43-Fc-L44-TNF1-L45-TNF2-L46-TNF3; TNF1-L52-TNF2-L53-TNF3;VL2-L54-CL-L55-VH2-L56-CH1-L57-Fc-L58-TNF1-L59-TNF2-L60-TNF3; Fc-L51-TNF1-L52-TNF2-L53-TNF3;VL2-L54-CH1-L55-VH2-L56-CL-L57-Fc-L58-TNF1-L59-TNF2-L60-TNF3; L40-TNF2-L41-TNF3;VH2-VL2-L43-Fc-L44-TNF1-L45-TNF2-L46-TNF3; 3;VL2-CL-L55-VH2-L56-CH1-L57-Fc-L58-TNF1-L59-TNF2-L60-TNF3;or VL2-CH1-L55-VH2-L56-CL-L57-Fc-L58-TNF1-L59-TNF2-L60-TNF3; or (ii) the first polypeptide has a structure represented by VL1-L61-VH1-L62-Fc-L63-TNF1-L64-TNF2-L65-TNF3; VH1-L66-VL1-L67-Fc-L68-TNF1-L69-TNF2-L70-TNF3; VL1-L71-VH1-L72-CL-L73-CH1-L74-Fc-L75-TNF1-L76-TNF2-L77-TNF3; VL VH1-L71-VH1-L72-CH1-L73-CL-L74-Fc-L75-TNF1-L76-TNF2-L77-TNF3; VL1-L78-CL-L79-VH1-L80-CH1-L81-Fc-L82-TNF1-L83-TNF2-L84-TNF3; or VL1-L78-CH1-L79-VH1-L80-CL-L81-Fc-L82-TNF1-L83-TNF2-L84-TNF3, and the second polypeptide is VL2-L85-VH2-L86-Fc; VH2-L87-VL2-L88-Fc; L2-L89-VH2-L90-CL-L91-CH1-L92-Fc; VL2-L89-VH2-L90-CH1-L91-CL-L92-Fc; VL2-L93-CL-L94-VH2-L95-CH1-L96-Fc; or VL2-L93-CH1-L94-VH2-L95-CL-L96-Fc, wherein VL1 is a first immunoglobulin light chain variable region, VL2 is a second immunoglobulin light chain variable region, VH1 is a first immunoglobulin heavy chain variable region, and VH2 is a second immunoglobulin heavy chain variable region. an antigen-binding polypeptide complex, wherein Fc is a region comprising immunoglobulin heavy chain constant region 2 (CH2), immunoglobulin heavy chain constant region 3 (CH3), and optionally an immunoglobulin hinge, CH1 is immunoglobulin heavy chain constant region 1, CL is an immunoglobulin light chain constant region, TNF1 is a first extracellular domain of a TNFSF ligand, TNF2 is a second extracellular domain of a TNFSF ligand, TNF3 is a third extracellular domain of a TNFSF ligand, and L1 to L96 are amino acid linkers;

[0012] Provided herein is an antigen-binding polypeptide complex comprising a first polypeptide and a second polypeptide, wherein (i) the first polypeptide is selected from the group consisting of Fc; VL1-L1-VL2-L2-VH2-L3-VH1-L4-Fc; VH1-L5-VH2-L6-VL2-L7-VL1-L8-Fc; Fc-L9-TNF1-L10-TNF2-L11-TNF3; VL1-L12-VL2- L13-VH2-L14-VH1-L15-Fc-L16-TNF1-L17-TNF2-L18-TNF3; or VH1-L19-VH2-L20-VL2-L21-VL1-L22-Fc-L23-TNF1-L24-TNF2-L25-TNF3, and the second polypeptide has the structure represented by VL3-L26-VL4-L27-VH4-L28-VH3-L29-F or (ii) the first polypeptide has a structure represented by Fc-L40-TNF1-L41-TNF2-L42-TNF3; VL1-L43-VL2-L44-VH3-L33-VH4-L34-VL4-L35-VL3-L36-Fc-L37-TNF1-L38-TNF2-L39-TNF3; or (iii) the first polypeptide has a structure represented by Fc-L40-TNF1-L41-TNF2-L42-TNF3; VL1-L43-VL2-L44-VH3-L33-VH4-L34-VL4-L35-VL3-L36-Fc-L37-TNF1-L38-TNF2-L39-TNF3; H2-L45-VH1-L46-Fc-L47-TNF1-L48-TNF2-L49-TNF3; or VH1-L50-VH2-L51-VL2-L52-VL1-L53-Fc-L54-TNF1-L55-TNF2-L56-TNF3, and the second polypeptide has the structure represented by Fc; VL3-L57-VL4-L58-VH4-L59-VH3-L60-Fc;or has a structure represented by VH3-L61-VH4-L62-VL4-L63-VL3-L64-Fc, where VL1 is a first immunoglobulin light chain variable region, VL2 is a second immunoglobulin light chain variable region, VL3 is a third immunoglobulin light chain variable region, VL4 is a fourth immunoglobulin light chain variable region, VH1 is a first immunoglobulin heavy chain variable region, VH2 is a second immunoglobulin heavy chain variable region, and VH3 is a third immunoglobulin heavy chain variable region. an antigen-binding polypeptide complex, wherein VH4 is a fourth immunoglobulin heavy chain variable region, Fc is a region comprising immunoglobulin heavy chain constant region 2 (CH2), immunoglobulin heavy chain constant region 3 (CH3), and optionally an immunoglobulin hinge, TNF1 is a first extracellular domain of a TNFSF ligand, TNF2 is a second extracellular domain of a TNFSF ligand, TNF3 is a third extracellular domain of a TNFSF ligand, and L1 to L64 are amino acid linkers;

[0013] Provided herein are antibodies or antigen-binding fragments thereof, comprising the antigen-binding polypeptide complexes described herein.

[0014] Provided herein is a pharmaceutical composition comprising an antigen-binding polypeptide complex or an antibody or antigen-binding fragment described herein and a pharma- ceutically acceptable carrier.

[0015] Provided herein is a method for inducing or enhancing an immune response, comprising administering to a subject in need thereof an antigen-binding polypeptide complex or antibody or antigen-binding fragment, or pharmaceutical composition described herein.

[0016] Provided herein is a method for overcoming cancer-mediated immunosuppression, comprising administering to a subject in need thereof an antigen-binding polypeptide complex, an antibody or antigen-binding polypeptide complex, or a pharmaceutical composition described herein. [Brief description of the drawings]

[0017] [Figure 1A] 1A-1F show exemplary antigen-binding polypeptide complexes of the present disclosure. Fv1 and Fv2 represent regions that bind to immune activation receptors or tumor-associated antigens (TAA). In some embodiments, Fv1 and Fv2 bind to human CD3 or CD28. In some embodiments, Fv1 and Fv2 are in the form of single chain variable fragments (scFv). In some embodiments, Fv1 and Fv2 are in the form of Fab or single chain Fab (scFab), optionally including CH1 and CL regions. TNFSF represents a trimer of the extracellular domain of a TNF superfamily member fused to Fc. In some embodiments, TNFSF is in the form of a fusion homotrimer. In some embodiments, TNFSF is a dimer of a fusion homotrimer. [Figure 1B] See legend to Figure 1A. [Figure 1C] See legend to Figure 1A. [Figure 1D] See legend to Figure 1A. [Figure 1E] See legend to Figure 1A. [Figure 1F] See legend to Figure 1A. [Figure 2A] 1 shows ELISA binding results to human CD3 of three exemplary antigen-binding polypeptide complexes containing OX40L trimers (MX169, MX368, and MX369). [Figure 2B] 1 shows ELISA binding results to human CD28 of three exemplary antigen-binding polypeptide complexes containing OX40L trimers (MX169, MX368, and MX369). [Figure 2C] 1 shows ELISA binding results to human OX40 of three exemplary antigen-binding polypeptide complexes containing OX40L trimers (MX169, MX368, and MX369). [Figure 3A]1 shows the fold change in T cell activation tested in a Jurkat cell line expressing luciferase under the control of the NF-κB (NFkb) promoter after overnight stimulation with three exemplary antigen-binding polypeptide complexes (MX169, MX368, and MX369) containing different concentrations of OX40L trimers. Results for a control IgG1 isotype antibody are also shown (IgG1 isotype). [Figure 3B] 1 shows the fold change in T cell activation tested in a Jurkat cell line expressing luciferase under the control of the NFAT promoter after overnight stimulation with three exemplary antigen-binding polypeptide complexes (MX169, MX368, and MX369) containing different concentrations of OX40L trimers. Results for a control IgG1 isotype antibody are also shown (IgG1 isotype). [Figure 4] Figures 4A-4F show the fold change in proliferation of primary human CD4+ T cells (Figures 4A-4C) and CD8+ T cells (Figures 4D-4F) from three different donors treated with one of three exemplary antigen-binding polypeptide complexes (MX169, MX368, and MX369) containing OX40L trimers. Results for a control IgG1 isotype antibody are also shown (IgG1 isotype). Human peripheral blood mononuclear cells (PBMCs) were incubated with the antigen-binding polypeptide complexes for 7 days and stained for flow cytometry. CD4+ and CD8+ T cells were identified and concentrations were determined using Precision Count Beads™. Fold change was calculated by dividing cell concentrations on day 7 and day 0. [Figure 5A] 1 shows ELISA binding results to human CD3 of three exemplary antigen-binding polypeptide complexes (MX306, MX424, and MX425) containing 4-1BBL trimers. [Figure 5B] 1 shows ELISA binding results to human CD28 of three exemplary antigen-binding polypeptide complexes (MX306, MX424, and MX425) containing 4-1BBL trimers. [Figure 5C]1 shows ELISA binding results for three exemplary antigen-binding polypeptide complexes containing 4-1BBL trimers (MX306, MX424, and MX425) to human 4-1BBL. [Figure 6] Figures 6A-6F show the fold change in proliferation of primary human CD4+ T cells (Figures 6A-6C) and CD8+ T cells (Figures 6D-6F) from three different donors treated with three exemplary antigen-binding polypeptide complexes (MX306, MX424, and MX425) containing 4-1BBL trimers. Results for a control IgG1 isotype antibody are also shown (IgG1 isotype). Human PBMCs were incubated with the antigen-binding polypeptide complexes for 7 days and stained for flow cytometry. CD4+ and CD8+ T cells were identified and concentrations were determined using Precision Count Beads™. Fold change was calculated by dividing cell concentrations on day 7 and day 0. [Figure 7A] Figures 7A-7B show T cell proliferation, measured as fold change in CD4 Tcm and Tem, of peripheral blood mononuclear cells (PBMCs) from two donors (Figures 7A and 7B, respectively), induced by MX169 and MX240. Results for a control antibody (hIgG1 isotype) are also shown. [Figure 7B] See legend to Figure 7A. [Figure 8] Figure 1 shows T cell proliferation measured as fold change in CD4 Tcm and Tem in PBMC from three donors induced by MX169, MX368 and MX369. Results for a control antibody (IgG1 isotype) are also shown. [Figure 9] Figure 1 shows T cell proliferation measured as fold change in CD8 Tcm and Tem in PBMC from two donors induced by MX169 and MX240. Results for a control antibody (IgG1 isotype) are also shown. [Figure 10]Figure 1 shows T cell proliferation measured as fold change in CD8 Tcm and Tem in PBMC from three donors induced by MX169, MX368 and MX369. Results for a control antibody (IgG1 isotype) are also shown. [Figure 11] Figure 1 shows T cell proliferation measured as fold change in CD4 Tcm and Tem or CD8 Tcm and Tem of PBMC from two donors induced by MX306 and MX321. Results for a control antibody (IgG1 isotype) are also shown. [Figure 12] Figure 1 shows T cell proliferation measured as fold change in CD4 Tcm and Tem in PBMC from three donors induced by MX306, MX424 and MX425. Results for a control antibody (IgG1 isotype) are also shown. [Figure 13] Figure 1 shows T cell proliferation, measured as fold change in CD8 Tcm and Tem in PBMC from three donors, induced by MX306, MX424 and MX425. Results for a control antibody (IgG1 isotype) are also shown. [Figure 14A] MX169, MX170, MX250, MX368, and MX369 mediate release of IFN-gamma, IL-2, IL-6, and TNF-a from primary human T cells. Results for a control antibody (IgG isotype) are also shown. [Figure 14B] The structures of MX169, MX170, MX250, MX368 and MX369 are shown. [Figure 15] MX169, MX170, MX250, MX368, and MX369 mediate release of IL-4, IL-5, and IL-10 from primary human T cells. Results for a control antibody (IgG isotype) are also shown. [Figure 16] MX169, MX170, MX250, MX368, and MX369 mediate release of IFN-gamma, IL-2, IL-6, and TNF-a from primary human T cells. Results for a control antibody (IgG isotype) are also shown. [Figure 17]MX169, MX170, MX250, MX368, and MX369 mediate release of IL-4, IL-5, and IL-10 from primary human T cells. Results for a control antibody (IgG isotype) are also shown. [Figure 18A] MX306, MX170, MX318, MX424, and MX425 mediate release of IFN-gamma, IL-2, IL-6, and TNF-a from primary human T cells. Results for a control antibody (IgG isotype) are also shown. [Figure 18B] The structures of MX306, MX170, MX318, MX424 and MX425 are shown. [Figure 19] MX306, MX170, MX318, MX424, and MX425 mediate release of IL-4, IL-5, and IL-10 from primary human T cells. Results for a control antibody (IgG isotype) are also shown. [Figure 20] MX306, MX170, MX318, MX424, and MX425 mediate release of IFN-gamma, IL-2, IL-6, and TNF-a from primary human T cells. Results for a control antibody (IgG isotype) are also shown. [Figure 21] MX306, MX170, MX318, MX424, and MX425 mediate release of IL-4, IL-5, and IL-10 from primary human T cells. Results for a control antibody (IgG isotype) are also shown. [Figure 22A] 1 shows the activation of non-human primate (NHP) CD4 and CD8 T cells mediated by MX424, MX485, MX487, MX620, and MX622. Results for a control antibody (IgG1 isotype) are also shown. [Figure 22B] The structures of MX424, MX485, MX487, MX620 and MX622 are shown. [Figure 23] The fold change in CD4 and CD8 cells induced by MX424, MX485, MX487, MX620 and MX622 is shown. Results for a control antibody (IgG1 isotype) are also shown. [Figure 24]MX424, MX485, MX487, MX620 and MX622 mediated release of IFN gamma, IL-6, IL-2 and TNFα. Results for a control antibody (IgG1 isotype) are also shown. [Figure 25A] 1 shows the activation of CD4 and CD8 NHP T cells mediated by MX368 and MX489. Results for a control antibody (IgG1 isotype) are also shown. [Figure 25B] The structures of MX368 and MX489 are shown. [Figure 26] MX368 and MX489 induced proliferation of CD4 and CD8 NHP T cells. Results for a control antibody (IgG1 isotype) are also shown. [Figure 27] MX368 and MX489 mediated release of IFN gamma, IL-6, IL-2 and TNFa from NHP T cells. Results for a control antibody (IgG1 isotype) are also shown. [Figure 28] Shown are T cell numbers and percent T cell activation in NHPs following treatment with MX487 in two donors. [Figure 29] Shown are the percentages of naive, Tcm, Teff and Tem populations in CD4 and CD8 cells from two different NHPs after treatment with MX487. [Diagram 30] T cell counts and percent CD4 and CD8 T cell activation from two NHPs treated with MX620 are shown. Arrows indicate antibody administration. [Diagram 31] Shown are the percentages of naive, Tcm, Teff and Tem populations in CD4 and CD8 T cells from two donors after treatment with MX620. [Diagram 32] Fold change in T cell numbers and activation of CD4 and CD8 T cells from two NHPs following treatment with MX620 are shown. Arrows indicate antibody administration. [Diagram 33] Fold changes in naive, Tcm, Teff and Tem populations in CD8 T cells from two donor NHPs are shown. Arrows indicate antibody treatment. [Diagram 34] Percent lysis of Z138 cells following treatment with increasing concentrations of MX582 and MX583 is shown, as is treatment with a control antibody (hIgG1LALAPA). [Diagram 35] Percent lysis of Z138 cells following treatment with increasing concentrations of MX751, MX777 and MX778 is shown, as is treatment with a control antibody (hIgG1LALAPA). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Detailed Description Given the role of anti-CD3 antibodies, OX40 and 4-1BB in T cell activation and anti-tumor immune responses, combining anti-CD3 antibodies with OX40 or 4-1BB costimulatory signals may broaden activation of various T cell populations and provide sustained stimulation for T cell survival and long-term expansion. Thus, antigen-binding polypeptide complexes (e.g., antibodies or antigen-binding fragments thereof) incorporating one or more trimers of anti-CD3 domains (e.g., complementarity determining regions (CDRs), heavy chain variable regions (VH), light chain variable regions (VL), single chain variable fragments (scFv), Fab, single chain Fab (scFab), heavy chain, or light chain) and the extracellular domain of tumor necrosis factor superfamily (TNFSF) ligands (e.g., OX40L or 4-1BBL) have been developed. In some embodiments, one or more anti-tumor associated antigen (TAA) regions, such as one or more anti-HER2 binding regions (e.g., CDRs, VH, VL, scFv, Fab, scFab, heavy chain or light chain), are further incorporated into the antigen-binding polypeptide complexes of the present disclosure. In some embodiments, one or more anti-immunostimulatory receptor regions, such as one or more anti-CD28 binding regions (e.g., CDRs, VH, VL, scFv, Fab, scFab, heavy chain or light chain), are further incorporated into the antigen-binding complexes of the present disclosure.

[0019] Thus, the present invention is directed to antigen-binding polypeptide complexes (e.g., antibodies or antigen-binding fragments thereof) with improved characteristics. In some embodiments, the present invention allows the creation of multispecific and multifunctional antigen-binding polypeptide complexes through the expression of complementary self-assembling heavy and light chains expressed in one polypeptide per arm, optionally with specific amino acid linkers. This multifunctionality allows the antigen-binding polypeptide complexes of the present invention to bind specific combinations of target molecules to provide selectivity or broadness / neutralization, bring together two or more cell types, bring targets together to deliver activation signals, modify disease microenvironments, and enhance binding avidity to improve efficacy.

[0020] Throughout the specification and claims, various terms relating to aspects of the present disclosure are used. Such terms are intended to have their ordinary meaning in the art unless otherwise specified. Other terms that are specifically defined are to be interpreted in a manner consistent with the definition provided herein.

[0021] I. Definition As used herein, the term "antigen-binding polypeptide complex" refers to a group of two, three, or four associated polypeptides, where at least one polypeptide has the ability to specifically bind to one or more antigens. Antigen-binding polypeptide complexes include, but are not limited to, antibodies or antigen-binding fragments thereof.

[0022] The term "antibody" includes, but is not limited to, a glycoprotein immunoglobulin that specifically binds an antigen and comprises at least two heavy (H) chains and two light (L) chains interconnected by disulfide bonds. Each H chain comprises a heavy chain variable region (abbreviated herein as VH) and a heavy chain constant region. The heavy chain constant region comprises three constant domains: CH1, CH2, and CH3. Each L chain comprises a light chain variable region (abbreviated herein as VL) and a light chain constant region. The light chain constant region comprises one constant domain, CL. The VH and VL regions can be further divided into regions of hypervariability called complementarity determining regions (CDRs) and more conserved regions called framework regions (FRs) that lie between them. Each VH and VL comprises three CDRs and four FRs, arranged from amino-terminus to carboxy-terminus in the following order: FR1, CDR1, FR2, CDR2, FR3, CDR3, FR4. The variable regions of the heavy and light chains contain binding domains that interact with antigens. The constant regions of the antibody can mediate the binding of the immunoglobulin to host tissues or factors, including various cells of the immune system (e.g., effector cells) and the first component (C1q) of the classical complement system. The heavy chain may or may not have a C-terminal lysine. Unless otherwise indicated herein, the amino acids of the variable regions are numbered using the Kabat numbering system and the amino acids of the constant regions are numbered using the EU system.

[0023] The term "monoclonal antibody" as used herein refers to an antibody produced by a single clone of B cells and that binds to the same epitope. In contrast, the term "polyclonal antibody" refers to a population of antibodies produced by different B cells and that bind to different epitopes of the same antigen. The term "antibody" includes, by way of example, monoclonal and polyclonal antibodies, chimeric and humanized antibodies, human or non-human antibodies, fully synthetic antibodies, and single chain antibodies. Non-human antibodies can be humanized by recombinant methods to reduce immunogenicity in humans.

[0024] The antibody may be an altered antibody (e.g., mutated, deleted, substituted, conjugated to a non-antibody moiety). For example, the antibody may contain one or more variant amino acids (compared to naturally occurring antibodies) that change the properties (e.g., functional properties) of the antibody. Several such modifications are known in the art, for example, affecting half-life, effector functions, and / or immune responses to the antibody in patients. The term antibody also includes artificial polypeptide constructs that contain an antigen-binding site derived from at least one antibody.

[0025] An "antigen-binding fragment" refers to one or more fragments or portions of an antibody that retain the ability to specifically bind to the antigen bound by the intact antibody. It has been shown that the antigen-binding function of an antibody can be performed by fragments or portions of a full-length antibody. An antigen-binding fragment can contain antigen-determining regions of an intact antibody (e.g., complementarity-determining regions (CDRs)). Examples of antigen-binding fragments of an antibody include Fab, Fab', F(ab') and / or F(ab') fragments. 2 Antigen-binding fragments of antibodies include, but are not limited to, Fv fragments, linear antibodies, and single chain antibodies. Antigen-binding fragments of antibodies may be obtained from any animal species, including rodents (e.g., mice, rats, or hamsters) and humans, or may be artificially produced.

[0026] Furthermore, although the two domains of the Fv fragment, VL and VH, are encoded by separate genes, they can be joined using recombinant techniques by a synthetic linker that allows for the creation of a single protein chain, with the VL and VH regions pairing to form a monovalent molecule (known as a single-chain Fv (scFv); see, e.g., Bird et al. (1988) Science 242:423-426; and Huston et al. (1988) Proc. Natl. Acad. Sci. USA 85:5879-5883). Such single-chain antibodies are also intended to be encompassed within the term "antigen-binding fragment" of an antibody.

[0027] Antigen-binding fragments are obtained using conventional techniques known to those of skill in the art, and the fragments are screened for utility in the same manner as intact antibodies. Antigen-binding fragments can be produced by recombinant DNA techniques or by enzymatic or chemical cleavage of intact immunoglobulins.

[0028] As used herein, the term "variable region" typically refers to a portion of an antibody, generally a light or heavy chain portion, typically about the amino-terminal 110-120 amino acids, or 110-125 amino acids in the mature heavy chain and about 90-115 amino acids in the mature light chain, that differs significantly in sequence between antibodies and is used in the binding and specificity of a particular antibody to a particular antigen. The sequence variability is concentrated in regions called complementarity determining regions (CDRs), while the more conserved regions of the variable domain are called framework regions (FRs). Without wishing to be bound by any particular mechanism or theory, it is believed that the CDRs of the light and heavy chains are primarily responsible for antibody-antigen interaction and specificity. In some embodiments, the variable region is a mammalian variable region, e.g., a human, mouse, or rabbit variable region. In some embodiments, the variable region comprises rodent or mouse CDRs and human FRs. In some embodiments, the variable region is a primate (e.g., non-human primate) variable region. In some embodiments, the variable region comprises rodent or murine CDRs and primate (eg, non-human primate) FRs.

[0029] The term "complementarity determining region" or "CDR" as used herein refers to each of the regions of an antibody variable domain that are hypervariable in sequence and / or form structurally defined loops (hypervariable loops) and / or contain antigen contact residues. An antibody may contain six CDRs, e.g., three in VH and three in VL.

[0030] The terms "VL", "VL region", and "VL domain" are used interchangeably herein to refer to a light chain variable region of an antigen-binding polypeptide complex, an antibody, or an antigen-binding fragment thereof. In some embodiments, a VL region is referred to herein as VL1, which denotes a first light chain variable region, VL2, which denotes a second light chain variable region, VL3, which denotes a third light chain variable region, etc. A recited VL region (e.g., VL1) may have the same or different antigen-binding characteristics and / or the same or different sequence as another recited VL region (e.g., VL2).

[0031] The terms "VH," "VH region," and "VH domain" are used interchangeably herein to refer to a heavy chain variable region of an antigen-binding polypeptide complex, an antibody, or an antigen-binding fragment thereof. In some embodiments, a VH region is referred to herein as VH1, which denotes a first heavy chain variable region, VH2, which denotes a second heavy chain variable region, VH3, which denotes a third heavy chain variable region, etc. A recited VH region (e.g., VH1) may have the same or different antigen-binding characteristics and / or the same or different sequence as another recited VH region (e.g., VH2).

[0032] As used herein, "Kabat numbering" and similar terms are art-recognized and refer to a system for numbering amino acid residues in the heavy and light chain variable regions of an antibody or an antigen-binding fragment thereof. In some embodiments, CDRs can be determined according to the Kabat numbering system (see, for example, Kabat EA & Wu TT (1971) Ann NY Acad Sci 190:382-391 and Kabat EA et al., (1991) Sequences of Proteins of Immunological Interest, Fifth Edition, USDepartment of Health and Human Services, NIH Publication No. 91-3242). Using the Kabat numbering system, the CDRs in an antibody heavy chain molecule are typically located at amino acid positions 31-35 (which may optionally include one or two additional amino acids after 35, referred to as 35A and 35B in the Kabat numbering scheme) (CDR1), amino acid positions 50-65 (CDR2), and amino acid positions 95-102 (CDR3). Using the Kabat numbering system, the CDRs in an antibody light chain molecule are typically located at amino acid positions 24-34 (CDR1), amino acid positions 50-56 (CDR2), and amino acid positions 89-97 (CDR3).

[0033] As used herein, the term "constant region" or "constant domain" is used interchangeably to refer to a portion of an antigen-binding polypeptide complex, an antibody or an antigen-binding fragment thereof, e.g., the carboxyl-terminal portion of the light and / or heavy chain that is not directly involved in binding the antibody to an antigen, but can exhibit various effector functions, such as interaction with the Fc region. Constant regions generally have a more conserved amino acid sequence compared to the variable region. In some embodiments, an antigen-binding polypeptide complex, an antibody or an antigen-binding fragment thereof comprises a constant region or a portion thereof that is sufficient for antibody-dependent cell-mediated cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP), and complement-dependent cytotoxicity (CDC).

[0034] As used herein, the terms "fragment crystallization region", "Fc region", or "Fc domain" are used interchangeably herein to refer to the tail region of an antibody that interacts with cell surface receptors called Fc receptors and several proteins of the complement system. The Fc region typically includes the CH2 and CH3 regions, and optionally includes the immunoglobulin hinge.

[0035] As used herein, the terms "immunoglobulin hinge", "hinge", "hinge domain" or "hinge region" are used interchangeably to refer to the stretch of heavy chain between the Fab and Fc portions of an antigen-binding polypeptide complex, an antibody or an antigen-binding fragment thereof. The hinge provides structure, positioning and flexibility, and aids in the normal function of the antibody (e.g., cross-linking two antigens or binding two antigenic determinants on the same antigen molecule). Immunoglobulin hinges are divided into upper, middle and lower hinge regions, which can be divided based on structural and / or genetic components. Immunoglobulin hinges of the present invention can contain one, two or all three of these regions. Structurally, the upper hinge region runs from the C-terminus of CH1 to the first hinge disulfide bond. The middle hinge region runs from the first cysteine ​​to the last cysteine ​​of the hinge. The lower hinge region extends from the last cysteine ​​to the glycine of CH2. The cysteines present in the hinge form interchain disulfide bonds, linking the immunoglobulin monomers.

[0036] As used herein, the term "Fab" refers to the region of an antibody that binds to an antigen. A Fab typically consists of one constant domain and one variable domain from each of the heavy and light chains.

[0037] As used herein, the term "heavy chain" refers to an antigen-binding polypeptide complex, a portion of an antibody or antigen-binding fragment thereof, typically composed of a heavy chain variable region (VH), heavy chain constant region 1 (CH1), heavy chain constant region 2 (CH2), and heavy chain constant region 3 (CH3). A typical antibody is composed of two heavy chains and two light chains. When used in reference to an antibody, heavy chain can refer to any distinct type, e.g., alpha (α), delta (δ), epsilon (ε), gamma (γ), and mu (μ), based on the amino acid sequence of the constant region, which gives rise to the IgA, IgD, IgE, IgG, and IgM classes of antibodies, respectively, including subclasses of IgG, e.g., IgG1, IgG2, IgG3, and IgG4. Heavy chain amino acid sequences are known in the art. In some embodiments, the heavy chain is a human heavy chain.

[0038] As used herein, the term "light chain" refers to a portion of an antigen-binding polypeptide complex, an antibody or an antigen-binding fragment thereof, typically composed of a light chain variable region (VL) and a light chain constant region (CL). A typical antibody is composed of two light chains and two heavy chains. When used in reference to an antibody, the light chain can refer to any distinct type, e.g., kappa (κ) or lambda (λ), based on the amino acid sequence of the constant region. Light chain amino acid sequences are known in the art. In some embodiments, the light chain is a human light chain.

[0039] The term "chimeric" antibody or antigen-binding fragment thereof refers to an antibody or antigen-binding fragment thereof whose amino acid sequence is derived from more than one species. Typically, the variable regions of both the light and heavy chains correspond to the variable regions of an antibody or antigen-binding fragment thereof from one species of mammal (e.g., mouse, rat, rabbit, etc.) having the desired specificity, affinity and capacity, and the constant regions are homologous to the sequences of the antibody or antigen-binding fragment thereof from that species so as not to elicit an immune response in another species (usually human).

[0040] The term "humanized" antibody or antigen-binding fragment thereof refers to a form of a non-human (e.g., mouse) antibody or antigen-binding fragment that is a specific immunoglobulin chain, a chimeric immunoglobulin, or a fragment thereof, and contains minimal non-human (e.g., mouse) sequence. Typically, a humanized antibody or antigen-binding fragment thereof is a human immunoglobulin in which residues from a complementarity determining region (CDR) are replaced by residues from a CDR of a non-human species (e.g., mouse, rat, rabbit, hamster) having the desired specificity, affinity, and capacity (Jones et al., Nature 321:522-525 (1986); Riechmann et al., Nature 332:323-327 (1988); Verhoeyen et al., Science 239:1534-1536 (1988)). In some embodiments, Fv framework region (FR) residues of a human immunoglobulin are replaced by the corresponding residues in an antibody or fragment from a non-human species having the desired specificity, affinity, and capacity. The humanized antibody or antigen-binding fragment thereof can be further modified by additional substitution of any residues within the Fv framework regions and / or within the replaced non-human residues to improve and optimize the specificity, affinity, and / or capacity of the antibody or antigen-binding fragment thereof. Generally, a humanized antibody or antigen-binding fragment thereof comprises substantially all of at least one, typically two or three, variable domains that contain all or substantially all of the CDR regions corresponding to a non-human immunoglobulin, and all or substantially all of the FR regions are of human immunoglobulin consensus sequences. The humanized antibody or antigen-binding fragment thereof can also comprise at least a portion of a constant region, typically a human immunoglobulin constant region. Examples of methods used to make humanized antibodies are known and are described, for example, in U.S. Pat. No. 5,225,539; Roguska et al., Proc. Natl. Acad. Sci., USA, 91(3):969-973 (1994), and Roguska et al., Protein Eng. 9(10):895-904 (1996).

[0041] The term "human" antibody or antigen-binding fragment thereof, as used herein, means an antibody or antigen-binding fragment thereof having an amino acid sequence derived from the human immunoglobulin locus, and such an antibody or antigen-binding fragment thereof is produced using recombinant techniques known in the art. This definition of human antibody or antigen-binding fragment thereof includes intact or full-length antibodies and fragments thereof.

[0042] An "isolated" polypeptide complex, antibody, antigen-binding fragment thereof, polynucleotide, vector, or cell is a polypeptide complex, antibody, antigen-binding fragment thereof, polynucleotide, vector, or cell in a form that does not exist in nature. Isolated polypeptide complexes, antibodies, antigen-binding fragments thereof, polynucleotides, vectors, or cells include those that have been purified to the extent that they are not in the form in which they exist in nature. In some embodiments, an isolated polypeptide complex, antibody, antigen-binding fragment thereof, polynucleotide, vector, or cell is substantially pure. As used herein, "substantially pure" refers to a material that is at least 50% pure (i.e., free of contaminants), at least 90% pure, at least 95% pure, at least 98% pure, or at least 99% pure.

[0043] The terms "polypeptide," "peptide," and "protein" are used interchangeably herein to refer to polymers of amino acids of any length. The polymers may be linear or branched, may contain modified amino acids, or may be interrupted by non-amino acids. These terms also encompass amino acid polymers that have been modified, naturally or by intervention, for example, by disulfide bond formation, glycosylation, lipidation, acetylation, phosphorylation, or any other manipulation or modification, such as conjugation with a labeling component. Also included within the definition are polypeptides that contain, for example, one or more analogs of an amino acid (including, for example, unnatural amino acids, etc.), as well as other modifications known in the art. Because the polypeptides of the present invention are based on antibodies, it is understood that in some embodiments the polypeptides can occur as single chains or associated chains.

[0044] The use of the alternative (e.g., "or") should be understood to mean either one of the alternatives, both, or any combination thereof. As used herein, the indefinite article "a" or "an" should be understood to refer to "one or more" of any components that are cited or listed.

[0045] As used herein, the term "and / or" is to be construed as specifically disclosing each of the two specified features or components with or without the other feature or component. Thus, as used herein in phrases such as "A and / or B," the term "and / or" is intended to include "A and B," "A or B," "A" (single), and "B" (single). Similarly, the term "and / or" as used in phrases such as "A, B, and / or C" is intended to encompass each of the following aspects: A, B, and C; A, B, or C; A or C; A or B; B or C; A and C; A and B; B and C; A (single); B (single); and C (single).

[0046] Whenever an embodiment is described herein with words such as "comprising," "having," and the like, it is understood that other similar embodiments described with the terms "consisting of" and / or "consisting essentially of" are also provided.

[0047] As used herein, the term "about" refers to a value or composition that is within an acceptable error range for a particular value or composition as determined by one of ordinary skill in the art, depending in part on how the value or composition is measured or determined, i.e., the limitations of the measurement system. For example, "about" can mean within 1 or more than 1 standard deviation, as is customary in the art. Alternatively, "about" can mean a range of up to 10% or 20% (i.e., ±10% or ±20%). For example, about 3 mg can include any number between 2.7 mg and 3.3 mg (for 10%) or between 2.4 mg and 3.6 mg (for 20%). Furthermore, specifically with respect to biological systems or processes, the term can mean a value up to an order of magnitude or up to 5 times. When a particular value or composition is provided in this application and claims, unless otherwise indicated, the meaning of "about" should be assumed to be within an acceptable error range for that particular value or composition.

[0048] As described herein, any numerical range, concentration range, percentage range, ratio range, or integer range, unless otherwise specified, is understood to include any integer value within the recited range, and, where appropriate, fractions thereof (such as tenths and hundredths of integers).

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this disclosure pertains. For example, the Concise Dictionary of Biomedicine and Molecular Biology, Juo, Pei-Show, 2nd ed., 2002, CRC Press; The Dictionary of Cell and Molecular Biology, 5th ed., 2013, Academic Press; and the Oxford Dictionary Of Biochemistry And Molecular Biology, 2006, Oxford University Press provide those skilled in the art with a general dictionary for many of the terms used in this disclosure.

[0050] Units, prefixes, and symbols are shown in the form accepted by the International System of Units (SI). Numerical ranges are intended to be inclusive of the numbers defining the range. The headings provided herein are not intended to limit the various aspects of the disclosure and may be understood by reference to the specification in its entirety. Thus, the terms defined herein are more fully defined by reference to the specification in its entirety.

[0051] Various aspects are described in further detail in the following paragraphs.

[0052] II. Antigen-binding Polypeptide Complexes In some embodiments, the present invention is directed to antigen-binding polypeptide complexes having specific structural features as further described herein. In some embodiments, the antigen-binding polypeptide complexes of the present invention (e.g., antibodies or antigen-binding fragments thereof) comprise an anti-CD3 region (e.g., CDR, VH, VL, scFv, Fab, scFab, heavy chain or light chain) and one or more trimers of the extracellular domain of a tumor necrosis factor superfamily (TNFSF) ligand. In some embodiments, the antigen-binding polypeptide complexes of the present invention further comprise one or more anti-tumor associated antigen (TAA) regions, e.g., one or more anti-HER2 binding regions (e.g., CDR, VH, VL, scFv, Fab, scFab, heavy chain or light chain). In some embodiments, the antigen-binding polypeptide complexes of the present invention further comprise one or more anti-immunostimulatory receptor regions, e.g., one or more anti-CD28 binding regions (e.g., CDR, VH, VL, scFv, Fab, scFab, heavy chain or light chain). In some embodiments, one or more constant regions (eg, CH1 and / or CL) can also be incorporated into the polypeptide of the antigen-binding polypeptide complex.

[0053] A. Extracellular domain of TNFSF ligand and linker As used herein, "extracellular domain of tumor necrosis factor superfamily ligand" or "extracellular domain of TNFSF ligand" refers to a peptide that includes a portion of a ligand of the tumor necrosis superfamily that forms a trimer (also referred to as the TNF homology domain or ectodomain). Thus, the extracellular domain of the TNFSF ligand can also include the full-length TNFSF ligand sequence. In some embodiments, the structures of the antigen-binding polypeptide complexes described herein can refer to the extracellular domain of the TNFSF ligand by the terms TNF1, TNF2, and / or TNF3, which represent the first, second, and / or third extracellular domain of the TNFSF ligand, respectively.

[0054] Examples of the extracellular domain of a TNFSF ligand include, but are not limited to, OX40L (OX40 ligand, TNFSF4), 4-1BBL (4-1BB ligand, TNFSF9), TNF, TNF-related apoptosis-inducing ligand (TRAIL), CD40L (TNFSF5), CD27L (TNFSF7), CD30L (TNFSF8), FasL (TNFSF6), EDAM, LTA (TNFSF1), LTB (TNFSF3), CD153 (TNFSF8), RANKL (TNFSF11), TWEAK (TNFSF12), APRIL (TNFSF13), BAFF (TNFSF13B), LIGHT (TNFSF14), VEGI (TNFSF15), and GITRL (TNFSF18). In some embodiments, the extracellular domain of a TNFSF ligand is OX40L or 4-1BBL. In some embodiments, the extracellular domain of the TNFSF ligand is OX40L. In some embodiments, OX40L comprises the amino acid sequence of SEQ ID NO:1, or a sequence having 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% identity to SEQ ID NO:1. For example, OX40L can comprise the amino acid sequence of SEQ ID NO:1. In some embodiments, the extracellular domain of the TNFSF ligand is 4-1BBL. In some embodiments, 4-1BBL comprises the amino acid sequence of SEQ ID NO:2, or a sequence having 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% identity to SEQ ID NO:2. For example, 4-1BBL can comprise the amino acid sequence of SEQ ID NO:2.

[0055] In some embodiments, the antigen-binding polypeptide complex of the present disclosure comprises a trimer of three extracellular domains of a TNFSF ligand. In some embodiments, the trimer comprises or consists of the same type of extracellular domain of a TNFSF ligand (e.g., three OX40L or three 4-1BBL (homotrimers)), or the trimer can comprise or consist of a mixture of two or three different extracellular domains of TNFSF ligands (e.g., one OX40L and two 4-1BBL, or two OX40L and one 4-1BBL, in any order). In some embodiments, the antigen-binding polypeptide complex comprises or consists of one trimer (e.g., homotrimer) of the extracellular domain of a TNFSF ligand. For example, an antigen-binding polypeptide complex may comprise a trimer of three OX40L domains, where each OX40L comprises or consists of the amino acid sequence of SEQ ID NO: 1, or a sequence having 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% identity to SEQ ID NO: 1. For example, each OX40L of the trimer may comprise or consist of the sequence of SEQ ID NO: 1. For example, an antigen-binding polypeptide complex may comprise a trimer of three 4-1BBL domains, where each 4-1BBL comprises or consists of the amino acid sequence of SEQ ID NO:2 or a sequence having 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% identity to SEQ ID NO:2. For example, each 4-1BBL of the trimer may comprise or consist of the sequence of SEQ ID NO:2. In some embodiments, an antigen-binding polypeptide complex of the disclosure comprises two trimers of the extracellular domain of a TNFSF ligand (e.g., a dimer of trimers, such as a dimer of homotrimers).For example, the antigen-binding polypeptide complex can comprise a dimer of the OX40L trimers or 4-1BBL trimers described herein.

[0056] In some embodiments, the extracellular domain of the TNFSF ligand comprises or consists of the amino acid sequence of SEQ ID NO: 1 or 2, or a sequence having 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% identity to SEQ ID NO: 1 or 2. For example, the extracellular domain of the TNFSF ligand may comprise or consist of the sequence of SEQ ID NO: 1 or 2. Other sequences of the extracellular domain of TNFSF ligands are known, including, for example, Accession Nos. XP_016857719.1, XP_016857718.1, XP_016857717.1, XP_011508266.2, NP_001284491.1, NP_003317.1, NP_003802.1, P41273.1, 6A3V_X, 6A3V_W, 6A3V_V, 6A3V_U, 6A3V_S, 6A3V_R, 6A3V_Q, 6A3V_P, 6A3V_O, 6A3V_N, 6A3V_M, 6A3V_L, and 6A3V_K.

[0057] In some embodiments, the trimer of the extracellular domain of the TNFSF ligand contains an amino acid linker between one or more extracellular domains of the TNFSF ligand (e.g., having a structure represented by TNF1-L1-TNF2-L2-TNF3, where L1 and L2 are amino acid linkers). In some embodiments, the amino acid linker comprises or consists of the amino acid sequence of any one of SEQ ID NOs: 3-10 and 148-175, or a sequence having 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% identity to any one of SEQ ID NOs: 3-10 and 148-175. For example, the amino acid linker comprises or consists of the amino acid sequence of any one of SEQ ID NOs: 3-10 and 148-175. In some embodiments, the amino acid linker comprises or consists of an amino acid sequence of any one of SEQ ID NOs: 3-10, or a sequence having 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% identity to any one of SEQ ID NOs: 3-10. For example, the amino acid linker may comprise or consist of an amino acid sequence of any one of SEQ ID NOs: 3-10. In some embodiments, the amino acid linker comprises or consists of an amino acid sequence having at least 80% (such as 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%) identity to SEQ ID NO: 3. For example, the amino acid linker may comprise or consist of an amino acid sequence of SEQ ID NO: 3.In some embodiments, the amino acid linker comprises or consists of an amino acid sequence having at least 80% identity to SEQ ID NO: 10 (such as 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%). For example, the amino acid linker may comprise or consist of the amino acid sequence of SEQ ID NO: 10. For example, the amino acid linker may comprise or consist of the amino acid sequence of any one of SEQ ID NOs: 4 to 10. In some embodiments, the extracellular domain of the TNFSF ligand is OX40L (e.g., comprises or consists of an amino acid sequence having 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% identity to SEQ ID NO: 1), and the amino acid linker comprises or consists of an amino acid sequence of SEQ ID NO: 3, or a sequence having 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% identity to SEQ ID NO: 3. For example, the extracellular domain of the trimeric TNFSF ligand can comprise or consist of the amino acid sequence of SEQ ID NO: 1, and the amino acid linker can comprise or consist of the amino acid sequence of SEQ ID NO: 3.In some embodiments, the extracellular domain of the TNFSF ligand is 4-1BBL (e.g., comprises or consists of an amino acid sequence having 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% identity to SEQ ID NO:2), and the amino acid linker comprises or consists of any one of SEQ ID NOs:4-10, or a sequence having 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% identity to any one of SEQ ID NOs:4-10. For example, the extracellular domain of the trimeric TNFSF ligand may comprise or consist of the amino acid sequence of SEQ ID NO: 2, and the amino acid linker may comprise or consist of the amino acid sequence of any one of SEQ ID NOs: 4-10. In some embodiments, the extracellular domain of the TNFSF ligand is 4-1BBL (e.g., comprises or consists of an amino acid sequence having 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% identity to SEQ ID NO: 2), and the amino acid linker comprises or consists of SEQ ID NO: 10, or a sequence having 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% identity to SEQ ID NO: 10. For example, the extracellular domain of the trimeric TNFSF ligand may comprise or consist of the amino acid sequence of SEQ ID NO:2 and the amino acid linker may comprise or consist of the amino acid sequence of SEQ ID NO:10.

[0058] In some embodiments, a trimer of the extracellular domain of a TNFSF ligand comprises or consists of any one of SEQ ID NOs: 11-18, or a sequence having 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% identity to any one of SEQ ID NOs: 11-18. For example, a trimer of the extracellular domain of a TNFSF ligand may comprise or consist of any one of SEQ ID NOs: 11-18. For example, a trimer of the extracellular domain of TNFSF ligand may comprise or consist of the sequence of SEQ ID NO: 11, or a sequence having 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% identity to SEQ ID NO: 11. For example, a trimer of the extracellular domain of TNFSF ligand may comprise or consist of the sequence of SEQ ID NO: 18, or a sequence having 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% identity to SEQ ID NO: 18. In some embodiments, a dimer of trimers of the extracellular domain of TNFSF ligand comprises or consists of two trimers of the extracellular domain of TNFSF ligand, each comprising any one of SEQ ID NOs: 11-18, or a sequence having 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% identity to any one of the amino acid sequences of SEQ ID NOs: 11-18. In some embodiments, the two trimers of the dimer are the same.In some embodiments, one trimer of the dimer is different from the other trimer. For example, a dimer of trimers of the extracellular domain of a TNFSF ligand may comprise or consist of two trimers of the extracellular domain of a TNFSF ligand, each of which comprises any one of the amino acid sequences of SEQ ID NO: 11-18. For example, a dimer of trimers of the extracellular domain of a TNFSF ligand may comprise or consist of two trimers of the extracellular domain of a TNFSF ligand, each of which comprises the sequence of SEQ ID NO: 11 or a sequence having 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% identity to the amino acid sequence of SEQ ID NO: 11. For example, a dimer of trimers of the extracellular domain of TNFSF ligand may comprise or consist of two trimers of the extracellular domain of TNFSF ligand, each comprising a sequence of SEQ ID NO:18 or a sequence having 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% identity to the amino acid sequence of SEQ ID NO:18.

[0059] B.CD3 In some embodiments, an antigen-binding polypeptide complex of the invention (e.g., an antibody or antigen-binding fragment thereof) contains at least one region (e.g., a CDR, VH, VL, scFv, Fab, scFab, heavy chain, or light chain) that specifically binds to CD3.

[0060] In some embodiments, the antigen-binding polypeptide complex comprises a VL and / or a VH that specifically binds CD3. In some embodiments, the VL comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 22, 28, 185, 298, and 306; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 23, 29, 186, 299, and 307; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 24, 30, 187, 300, and 308. and / or the VH comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 19, 25, 182, 294, and 312; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 20, 26, 183, 295, and 313; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 21, 27, 184, 296, and 314. In some embodiments, the VL comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 22; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 23; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 24, and / or the VH comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 19; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 20; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 21.In some embodiments, the VL comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:28; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:29; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:30, and / or the VH comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:25; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:26; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:27. In some embodiments, the VL comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 185; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 186; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 187, and / or the VH comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 182; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 183; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 184. In some embodiments, the VL comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:298; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:299; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:300, and / or the VH comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:294; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:295; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:296.In some embodiments, the VL comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 306; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 307; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 308, and / or the VH comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 302; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 303; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 304. As used herein, "at least 90% identity" includes at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% and 100% identity to the recited reference sequence. In some embodiments, the VL comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 22; a CDR2 comprising the amino acid sequence of SEQ ID NO: 23; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 24, and / or the VH comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 19; a CDR2 comprising the amino acid sequence of SEQ ID NO: 20; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 21. In some embodiments, the VL comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 28; a CDR2 comprising the amino acid sequence of SEQ ID NO: 29; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 30, and / or the VH comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 25; a CDR2 comprising the amino acid sequence of SEQ ID NO: 26; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 27. In some embodiments, the VL comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 185; a CDR2 comprising the amino acid sequence of SEQ ID NO: 186; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 187, and / or the VH comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 182; a CDR2 comprising the amino acid sequence of SEQ ID NO: 183; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 184.In some embodiments, the VL comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 298; a CDR2 comprising the amino acid sequence of SEQ ID NO: 299; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 300, and / or the VH comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 294; a CDR2 comprising the amino acid sequence of SEQ ID NO: 295; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 296. In some embodiments, the VL comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 306; a CDR2 comprising the amino acid sequence of SEQ ID NO: 307; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 308, and / or the VH comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 312; a CDR2 comprising the amino acid sequence of SEQ ID NO: 313; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 314. In some embodiments, the VL comprises an amino acid sequence having 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% identity to SEQ ID NO: 45, and / or the VH comprises an amino acid sequence having 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% identity to SEQ ID NO: 43 or 44. In some embodiments, the VL comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO:45, and / or the VH comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO:43.For example, the VL may comprise the amino acid sequence of SEQ ID NO: 45 and / or the VH may comprise the amino acid sequence of SEQ ID NO: 43. In some embodiments, the VL comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 45 and / or the VH comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 44. For example, the VL may comprise the amino acid sequence of SEQ ID NO: 45 and / or the VH may comprise the amino acid sequence of SEQ ID NO: 44.

[0061] In some embodiments, the VH comprises an amino acid sequence having 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% identity to SEQ ID NO:188. In some embodiments, the VL comprises an amino acid sequence having 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% identity to SEQ ID NO: 297 or 305, and / or the VH comprises an amino acid sequence having 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% identity to SEQ ID NO: 188, 293 or 301. In some embodiments, the VL comprises an amino acid sequence having 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% identity to SEQ ID NO:297, and / or the VH comprises an amino acid sequence having 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% identity to SEQ ID NO:293.In some embodiments, the VL comprises an amino acid sequence having 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% identity to SEQ ID NO:305, and / or the VH comprises an amino acid sequence having 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% identity to SEQ ID NO:301.

[0062] In some embodiments, the antigen-binding polypeptide complex comprises a light chain that specifically binds to CD3. In some embodiments, the light chain comprises an amino acid sequence having 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% identity to SEQ ID NO: 54 or 176. For example, the light chain can comprise an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 54. For example, the light chain may comprise an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 176. For example, the light chain may comprise the amino acid sequence of SEQ ID NO: 54. For example, the light chain may comprise the amino acid sequence of SEQ ID NO: 176. In some embodiments, the light chain comprises an amino acid sequence encoded by a polynucleotide having 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% identity to SEQ ID NO: 55 or 177. For example, the light chain can comprise an amino acid sequence encoded by a polynucleotide having at least 80% identity (such as 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% identity) to SEQ ID NO:55.For example, the light chain may comprise an amino acid sequence encoded by a polynucleotide having at least 80% identity (such as 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% identity) to SEQ ID NO: 177. For example, the light chain may comprise an amino acid sequence encoded by the polynucleotide sequence of SEQ ID NO: 55. For example, the light chain may comprise an amino acid sequence encoded by the polynucleotide sequence of SEQ ID NO: 177.

[0063] In some embodiments, the antigen-binding polypeptide complex comprises a heavy chain that specifically binds to CD3. In some embodiments, the heavy chain comprises an amino acid sequence having 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% identity to SEQ ID NO: 178. In some embodiments, the heavy chain comprises the amino acid sequence of SEQ ID NO: 178.

[0064] In some embodiments, the antigen-binding polypeptide complex comprises a heavy chain that specifically binds CD3 and a light chain that specifically binds CD3. In some embodiments, the heavy chain comprises an amino acid sequence having 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% identity to SEQ ID NO: 178 and the light chain comprises an amino acid sequence having 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% identity to SEQ ID NO: 176. In some embodiments, the heavy chain comprises the amino acid sequence of SEQ ID NO: 178 and the light chain comprises the amino acid sequence of SEQ ID NO: 176.

[0065] In some embodiments, the antigen-binding polypeptide complex comprises a heavy chain that specifically binds to CD3. In some embodiments, the heavy chain comprises an amino acid sequence having 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% identity to SEQ ID NO: 98. In some embodiments, the heavy chain comprises an amino acid sequence having 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% identity to SEQ ID NO: 104. In some embodiments, the heavy chain comprises an amino acid sequence having 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% identity to SEQ ID NO: 120. In some embodiments, the heavy chain comprises the amino acid sequence of SEQ ID NO: 98. In some embodiments, the heavy chain comprises the amino acid sequence of SEQ ID NO: 104. In some embodiments, the heavy chain comprises the amino acid sequence of SEQ ID NO: 120.

[0066] In some embodiments, the antigen-binding polypeptide complex comprises a heavy chain that specifically binds CD3 and a light chain that specifically binds CD3. In some embodiments, the heavy chain comprises an amino acid sequence having 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% identity to SEQ ID NO:98 and the light chain comprises an amino acid sequence having 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% identity to SEQ ID NO:54. In some embodiments, the heavy chain comprises an amino acid sequence having 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% identity to SEQ ID NO: 104 and the light chain comprises an amino acid sequence having 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% identity to SEQ ID NO: 54. In some embodiments, the heavy chain comprises an amino acid sequence having 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% identity to SEQ ID NO: 120, and the light chain comprises an amino acid sequence having 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% identity to SEQ ID NO:54.In some embodiments, the heavy chain comprises the amino acid sequence of SEQ ID NO:98 and the light chain comprises the amino acid sequence of SEQ ID NO:54. In some embodiments, the heavy chain comprises the amino acid sequence of SEQ ID NO:104 and the light chain comprises the amino acid sequence of SEQ ID NO:54. In some embodiments, the heavy chain comprises the amino acid sequence of SEQ ID NO:120 and the light chain comprises the amino acid sequence of SEQ ID NO:54.

[0067] In some embodiments, the antigen-binding polypeptide complex comprises a light chain that specifically binds to CD3. In some embodiments, the light chain comprises an amino acid sequence having 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% identity to SEQ ID NO: 56 (ahCD3_h34L chain). For example, the light chain may comprise the amino acid sequence of SEQ ID NO: 56. In some embodiments, the light chain comprises an amino acid sequence encoded by a polynucleotide having 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% identity to SEQ ID NO: 57 (ahCD3_h34L chain). For example, the light chain may comprise an amino acid sequence encoded by the polynucleotide sequence of SEQ ID NO: 57. In some embodiments, the light chain comprises an amino acid sequence having 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% identity to SEQ ID NO: 54. For example, the light chain may comprise the amino acid sequence of SEQ ID NO:54.

[0068] In some embodiments, the antigen-binding polypeptide complex comprises a heavy chain that specifically binds to CD3. In some embodiments, the heavy chain comprises an amino acid sequence having 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% identity to SEQ ID NO: 98. In some embodiments, the heavy chain comprises an amino acid sequence having 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% identity to SEQ ID NO: 104. In some embodiments, the heavy chain comprises an amino acid sequence having 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% identity to SEQ ID NO: 120. In some embodiments, the heavy chain comprises the amino acid sequence of SEQ ID NO: 98. In some embodiments, the heavy chain comprises the amino acid sequence of SEQ ID NO: 104. In some embodiments, the heavy chain comprises the amino acid sequence of SEQ ID NO: 120.

[0069] In some embodiments, the antigen-binding polypeptide complex comprises a heavy chain that specifically binds CD3 and a light chain that specifically binds CD3. In some embodiments, the heavy chain comprises an amino acid sequence having 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% identity to SEQ ID NO:98 and the light chain comprises an amino acid sequence having 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% identity to SEQ ID NO:54. In some embodiments, the heavy chain comprises an amino acid sequence having 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% identity to SEQ ID NO: 104 and the light chain comprises an amino acid sequence having 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% identity to SEQ ID NO: 54. In some embodiments, the heavy chain comprises an amino acid sequence having 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% identity to SEQ ID NO: 120, and the light chain comprises an amino acid sequence having 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% identity to SEQ ID NO:54.In some embodiments, the heavy chain comprises the amino acid sequence of SEQ ID NO:98 and the light chain comprises the amino acid sequence of SEQ ID NO:54. In some embodiments, the heavy chain comprises the amino acid sequence of SEQ ID NO:104 and the light chain comprises the amino acid sequence of SEQ ID NO:54. In some embodiments, the heavy chain comprises the amino acid sequence of SEQ ID NO:120 and the light chain comprises the amino acid sequence of SEQ ID NO:54.

[0070] In some embodiments, the antigen-binding polypeptide complex comprises a heavy chain that specifically binds to CD3. In some embodiments, the heavy chain comprises an amino acid sequence having 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% identity to SEQ ID NO: 188. For example, the heavy chain can comprise the amino acid sequence of SEQ ID NO: 188.

[0071] Other examples of sequences that specifically bind to CD3 are well known and are described, for example, in U.S. Patent Nos. 11,186,650; 11,155,621; 11,098,120; 11,072,656; 11,007,267; 10,968,276; 10,961,315; 10,906,978; 10,865,251; Nos. 10,759,858; 10,690,678; 10,688,186; 10,669,33; 10,640,572; 10,174,124; 9,850,304; 9,657,102; 8,551,478; 7,994,289; and 7,993,641.

[0072] C. Tumor-associated antigens and immune-activating receptors In some embodiments, the antigen-binding polypeptide complexes (e.g., antibodies or antigen-binding fragments thereof) of the invention contain one or more regions (e.g., CDRs, VH, VL, scFv, Fab, scFab, heavy chain, or light chain) that specifically bind to an immune activating receptor or a tumor-associated antigen (TAA).

[0073] As used herein, a "tumor associated antigen" or TAA is a protein or molecule that is more abundant in cancer cells compared to normal cells. Examples of TAAs include tyrosine protein kinase Met (cMet), trophoblast cell surface antigen 2 (Trop2), CD20, CD19, receptor tyrosine protein kinase erbB-2 (HER2), receptor tyrosine protein kinase erbB-3 (HER3), adenosine A2A receptor (A2AR), proliferation-inducing ligand (APRIL), epidermal growth factor receptor (EGFR), fibroblast growth factor receptor (FGFR), B cell activation (BAFF), BAFF receptor (BAFFR), B cell maturation antigen (BCMA), Bruton's tyrosine kinase (BTK), B and T lymphocyte attenuator (BTLA), B7DC (programmed death ligand 2), B7 homolog 1 (B7H1), B Examples of TAA include, but are not limited to, B7H4, delta-like ligand 3 (DLL3), extracellular nucleoside triphosphate diphosphohydrolase 1 (ENTPD1), Fc fragment of IgE receptor 1a (FCER1A), Fc fragment of IgE receptor 1 (FCER1), arachidonate 5-lipoxygenase activating protein (FLAP), folate hydrolase 1 (FOLH1), mucin 1 (MUC-1), CD133, mucin 16 (MUC-16), lysosomal associated membrane protein 1 (LAMP1), CD38, programmed death ligand 1 (PD-L1), CEA cell adhesion molecule 5 (CEACAM5), prostate six transmembrane epithelial antigen 1 (STEAP1), and epithelial cell adhesion molecule (EpCAM). In some embodiments, the TAA is HER2.

[0074] As used herein, "immunostimulatory receptors" are a heterogeneous group of cell surface molecules that act to amplify or counteract the initial activation signal provided to T cells (e.g., signals from the T cell receptor (TCR) following interaction with antigen / major histocompatibility complex (MHC)), thereby influencing T cell differentiation, activation and / or proliferation. Examples of immune stimulatory receptors are well known and include, but are not limited to, CD3 and CD28.

[0075] In some embodiments, the antigen-binding polypeptide complex comprises a VH and / or a VL that specifically binds to a TAA or an immune stimulatory receptor (e.g., CD28). For example, the antigen-binding polypeptide complex can comprise a VH and / or a VL that specifically binds to CD28. In some embodiments, the VL comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 34 or 40; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 35 or 41; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 36 or 42. and / or the VH comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 31 or 37; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 32 or 38; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 33 or 39. In some embodiments, the VL comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 34; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 35; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 36, and / or the VH comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 31; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 32; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 33.In some embodiments, the VL comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 40; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 41; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 42, and / or the VH comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 37; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 38; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 39. As used herein, "at least 90% identity" includes at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% and 100% identity to the recited reference sequence. In some embodiments, the VL comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 34; a CDR2 comprising the amino acid sequence of SEQ ID NO: 35; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 36, and / or the VH comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 31; a CDR2 comprising the amino acid sequence of SEQ ID NO: 32; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 33. In some embodiments, the VL comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 40; a CDR2 comprising the amino acid sequence of SEQ ID NO: 41; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 42, and / or the VH comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 37; a CDR2 comprising the amino acid sequence of SEQ ID NO: 38; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 39. In some embodiments, the VL comprises an amino acid sequence of SEQ ID NO: 47 or 49, or a sequence having at least 80%, at least 85%, at least 90%, or at least 95% identity to SEQ ID NO: 47 or 49. In some embodiments, the VL comprises a sequence having at least 80% identity (such as 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% identity) to SEQ ID NO:47.In some embodiments, the VL comprises a sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 49. For example, the VL may comprise the amino acid sequence of SEQ ID NO: 47. For example, the VL may comprise the amino acid sequence of SEQ ID NO: 49. In some embodiments, the VH comprises the amino acid sequence of SEQ ID NO: 46 or 48, or a sequence having at least 80%, at least 85%, at least 90%, or at least 95% identity to SEQ ID NO: 46 or 48. In some embodiments, the VH comprises a sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 46. In some embodiments, the VH comprises a sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 48. For example, the VH may comprise the amino acid sequence of SEQ ID NO: 46. For example, the VH may comprise the amino acid sequence of SEQ ID NO: 48. In some embodiments, the antigen-binding polypeptide complex comprises a VL comprising the amino acid sequence of SEQ ID NO:47 (or a sequence having at least 80%, at least 85%, at least 90%, or at least 95% identity to SEQ ID NO:47); and a VH comprising the amino acid sequence of SEQ ID NO:46 (or a sequence having at least 80%, at least 85%, at least 90%, or at least 95% identity to SEQ ID NO:46).In some embodiments, the antigen-binding polypeptide complex comprises a VL comprising the amino acid sequence of SEQ ID NO:49 (or a sequence having at least 80%, at least 85%, at least 90%, or at least 95% identity to SEQ ID NO:49); and a VH comprising the amino acid sequence of SEQ ID NO:48 (or a sequence having at least 80%, at least 85%, at least 90%, or at least 95% identity to SEQ ID NO:48).

[0076] In some embodiments, the antigen-binding polypeptide complex comprises a light chain that specifically binds to a TAA or an immunostimulatory receptor. In some embodiments, the light chain comprises an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 95%, or 100% identity to SEQ ID NO:50 or 52. In some embodiments, the light chain comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO:50. In some embodiments, the light chain comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO:52. For example, the light chain may comprise the amino acid sequence of SEQ ID NO: 50. For example, the light chain may comprise the amino acid sequence of SEQ ID NO: 52. In some embodiments, the light chain comprises an amino acid sequence encoded by a polynucleotide having at least 80%, at least 85%, at least 90%, at least 95%, or 100% identity to SEQ ID NO: 51 or 53. In some embodiments, the light chain comprises an amino acid sequence encoded by a polynucleotide having at least 80% identity (such as 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% identity) to SEQ ID NO: 51.In some embodiments, the light chain comprises an amino acid sequence encoded by a polynucleotide having at least 80% identity (such as 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% identity) to SEQ ID NO: 53. For example, the light chain may comprise an amino acid sequence encoded by the polynucleotide sequence of SEQ ID NO: 51. For example, the light chain may comprise an amino acid sequence encoded by the polynucleotide sequence of SEQ ID NO: 53.

[0077] In some embodiments, the antigen-binding polypeptide complex comprises a VH and / or a VL that specifically binds CD20. In some embodiments, the VL comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 314 or 322; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 315 or 323; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 316 or 324. and / or the VH comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 310 or 318; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 311 or 319; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 312 or 320. In some embodiments, the VL comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:314; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:315; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:316, and / or the VH comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:310; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:311; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:312.In some embodiments, the VL comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:322; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:323; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:324, and / or the VH comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:318; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:319; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:320. In some embodiments, the VL comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:313 or 321, and / or the VH comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:309 or 317. In some embodiments, the VL comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:313, and / or the VH comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:309. In some embodiments, the VL comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 321, and / or the VH comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 317.As used herein, "at least 90% identity" includes at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% and 100% identity to the recited reference sequence.

[0078] In some embodiments, the antigen-binding polypeptide complex comprises a VH and / or a VL that specifically binds cMet. In some embodiments, the VL comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:274; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:275; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:276, and / or the VH comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:270; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:271; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:272. In some embodiments, the VL comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 273, and / or the VH comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 269. As used herein, "at least 90% identity" includes at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% and 100% identity to the recited reference sequence.

[0079] In some embodiments, the antigen-binding polypeptide complex comprises a VH and / or a VL that specifically binds Trop2. In some embodiments, the VL comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:282; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:283; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:284, and / or the VH comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:278; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:279; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:280. In some embodiments, the VL comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 281, and / or the VH comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 277. As used herein, "at least 90% identity" includes at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% and 100% identity to the recited reference sequence.

[0080] In some embodiments, the antigen-binding polypeptide complex comprises a VH and / or a VL that specifically binds CD19. In some embodiments, the VL comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:290; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:291; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:292, and / or the VH comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:286; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:287; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:288. In some embodiments, the VL comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 289, and / or the VH comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 285. As used herein, "at least 90% identity" includes at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% and 100% identity to the recited reference sequence.

[0081] Other examples of sequences that specifically bind to TAAs are well known and include, but are not limited to, GenBank Accession Nos. AAA39272.1, AAA39159.1, ABN79462.1, AVW80143.1, AVW80142.1, AVW80141.1, AAB34430.1, AAB34429.1, CAD45042.1, 4CMH_C, and 4CMH_B. Such sequences have also been used in, for example, Wernly et al., Cells, 9(2):295, 2020; Arakawa et al., Journal of Biochemistry, 120(3):657-662, 1996; Cole et al., Transplantation, 68(4):563-571, 1999; Li et al., International Immunopharmacology, 62:299-308, 2018; Castella et al., Methods & Clinical Development, 12:134-144, 2019; Sun et al., Molecular Immunology, 41(9):929-938, 2004; Iwaszkiewicz-Grzes et al., Cytotherapy, 22(11):629-641, 2020, Rosinski et al., Transplant Direct, 1(2):e7, 2015; Ellis et al., J Immunology, 155(2):925-937, 1995; Stevenson et al., Blood, 77(5):1071-1079, 1991; Chillemi et al., Molecular Medicine, 19:99-108, 2013, and International Publication No. WO2020 / 076853.

[0082] D. Antigen-binding Polypeptide Complex Structure In some embodiments, an antigen-binding polypeptide complex of the invention comprises a first polypeptide, a second polypeptide, and a third polypeptide, wherein the first polypeptide has a structure represented by VL1-L1-CL; VL1-L1-CH1; VH1-L1-CL; or VH1-L1-CH1; and wherein (i) the second polypeptide has a structure represented by VH1-L2-CH1-L3-Fc-L4-TNF1-L5-TNF2-L6. -TNF3;VH1-L2-CL-L3-Fc-L4-TNF1-L5-TNF2-L6-TNF3;VH1-L7-CH1-L8-Fc;VH1-L7-CL-L8-Fc;VL1-L2-CH1-L3-Fc- VL1-L7-CH1-L8-Fc; or VL1-L7-CL-L8 -Fc, and the third polypeptide has a structure represented by VL2-L9-VH2-L10-Fc-L11-TNF1-L12-TNF2-L13-TNF3; or VH2-L14-VL2-L15-Fc-L16-TNF1-L17-TNF2-L18-TNF3; or (ii) the second polypeptide has a structure represented by VH1-L19-CH1-L20-Fc-L21-TNF1-L22-TNF2 -L23-TNF3; VH1-L19-CL-L20-Fc-L21-TNF1-L22-TNF2-L23-TNF3; VL1-L19-CH1-L20-Fc-L21-TNF1-L22-TNF2-L23-TNF3; or VL1-L19-CL-L20-Fc-L21-TNF1-L22-TNF2-L23-TNF3, and the third polypeptide is VL2-L24-VH2-L25-Fc;or a structure represented by VH2-L26-VL2-L27-Fc, where VL1 is a first immunoglobulin light chain variable region, VL2 is a second immunoglobulin light chain variable region, VH1 is a first immunoglobulin heavy chain variable region, VH2 is a second immunoglobulin heavy chain variable region, Fc is a region including immunoglobulin heavy chain constant region 2 (CH2), immunoglobulin heavy chain constant region 3 (CH3), and optionally an immunoglobulin hinge, CH1 is immunoglobulin heavy chain constant region 1, CL is an immunoglobulin light chain constant region, TNF1 is a first extracellular domain of a tumor necrosis factor superfamily (TNFSF) ligand, TNF2 is a second extracellular domain of the TNFSF ligand, and TNF3 is a third extracellular domain of the TNFSF ligand, and L1 to L27 are amino acid linkers. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL; VL1-L1-CH1; VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VH1-L2-CH1-L3-Fc-L4-TNF1-L5-TNF2-L6-TNF3, and the third polypeptide has a structure represented by VL2-L9-VH2-L10-Fc-L11-TNF1-L12-TNF2-L13-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL;VL1-L1-CH1;VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VH1-L2-CH1-L3-Fc-L4-TNF1-L5-TNF2-L6-TNF3, and the third polypeptide has a structure represented by VH2-L14-VL2-L15-Fc-L16-TNF1-L17-TNF2-L18-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL;VL1-L1-CH1;VH1-L1-CL;or VH1-L1-CH1, the first polypeptide has a structure represented by VH1-L2-CL-L3-Fc-L4-TNF1-L5-TNF2-L6-TNF3, and the third polypeptide has a structure represented by VL2-L9-VH2-L10-Fc-L11-TNF1-L12-TNF2-L13-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL; VL1-L1-CH1; VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VH1-L2-CL-L3-Fc-L4-TNF1-L5-TNF2-L6-TNF3, and the third polypeptide has a structure represented by VH2-L14-VL2-L15-Fc-L16-TNF1-L17-TNF2-L18-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL; VL1-L1-CH1; VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VH1-L7-CH1-L8-Fc, and the third polypeptide has a structure represented by VL2-L9-VH2-L10-Fc-L11-TNF1-L12-TNF2-L13-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL; VL1-L1-CH1; VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VH1-L7-CH1-L8-Fc, and the third polypeptide has a structure represented by VH2-L14-VL2-L15-Fc-L16-TNF1-L17-TNF2-L18-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL;VL1-L1-CH1;VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VH1-L7-CL-L8-Fc, and the third polypeptide has a structure represented by VL2-L9-VH2-L10-Fc-L11-TNF1-L12-TNF2-L13-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL;VL1-L1-CH1;VH1-L1-CL; or VH1-L1-CH1, the first polypeptide has a structure represented by VH1-L7-CL-L8-Fc, and the third polypeptide has a structure represented by VH2-L14-VL2-L15-Fc-L16-TNF1-L17-TNF2-L18-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL; VL1-L1-CH1; VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VL1-L2-CH1-L3-Fc-L4-TNF1-L5-TNF2-L6-TNF3, and the third polypeptide has a structure represented by VL2-L9-VH2-L10-Fc-L11-TNF1-L12-TNF2-L13-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL; VL1-L1-CH1; VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VL1-L2-CH1-L3-Fc-L4-TNF1-L5-TNF2-L6-TNF3, and the third polypeptide has a structure represented by VH2-L14-VL2-L15-Fc-L16-TNF1-L17-TNF2-L18-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL;VL1-L1-CH1;VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VL1-L2-CL-L3-Fc-L4-TNF1-L5-TNF2-L6-TNF3, and the third polypeptide has a structure represented by VL2-L9-VH2-L10-Fc-L11-TNF1-L12-TNF2-L13-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL;VL1-L1-CH1;VH1-L1-CL;or VH1-L1-CH1, the first polypeptide has a structure represented by VL1-L2-CL-L3-Fc-L4-TNF1-L5-TNF2-L6-TNF3, and the third polypeptide has a structure represented by VH2-L14-VL2-L15-Fc-L16-TNF1-L17-TNF2-L18-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL; VL1-L1-CH1; VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VL1-L7-CH1-L8-Fc, and the third polypeptide has a structure represented by VL2-L9-VH2-L10-Fc-L11-TNF1-L12-TNF2-L13-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL; VL1-L1-CH1; VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VL1-L7-CH1-L8-Fc, and the third polypeptide has a structure represented by VH2-L14-VL2-L15-Fc-L16-TNF1-L17-TNF2-L18-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL; VL1-L1-CH1; VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VL1-L7-CL-L8-Fc, and the third polypeptide has a structure represented by VL2-L9-VH2-L10-Fc-L11-TNF1-L12-TNF2-L13-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL;VL1-L1-CH1;VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VL1-L7-CL-L8-Fc, and the third polypeptide has a structure represented by VH2-L14-VL2-L15-Fc-L16-TNF1-L17-TNF2-L18-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL;VL1-L1-CH1;VH1-L1-CL;or VH1-L1-CH1, the second polypeptide has a structure represented by VH1-L19-CH1-L20-Fc-L21-TNF1-L22-TNF2-L23-TNF3, and the third polypeptide has a structure represented by VL2-L24-VH2-L25-Fc. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL; VL1-L1-CH1; VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VH1-L19-CH1-L20-Fc-L21-TNF1-L22-TNF2-L23-TNF3, and the third polypeptide has a structure represented by VH2-L26-VL2-L27-Fc. In some embodiments, the first polypeptide is VL1-L1-CL; VL1-L1-CH1; VH1-L1-CL; or VH1-L1-CH1; In some embodiments, the first polypeptide has a structure represented by VL1-L19-CL-L20-Fc-L21-TNF1-L22-TNF2-L23-TNF3, the second polypeptide has a structure represented by VL2-L24-VH2-L25-Fc. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL; VL1-L1-CH1; VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VH1-L19-CL-L20-Fc-L21-TNF1-L22-TNF2-L23-TNF3, and the third polypeptide has a structure represented by VH2-L26-VL2-L27-Fc. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL; VL1-L1-CH1; VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VL1-L19-CH1-L20-Fc-L21-TNF1-L22-TNF2-L23-TNF3, and the third polypeptide has a structure represented by VL2-L24-VH2-L25-Fc. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL; VL1-L1-CH1; VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VL1-L19-CH1-L20-Fc-L21-TNF1-L22-TNF2-L23-TNF3, and the third polypeptide has a structure represented by VH2-L26-VL2-L27-Fc. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL;VL1-L1-CH1;VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VL1-L19-CL-L20-Fc-L21-TNF1-L22-TNF2-L23-TNF3, and the third polypeptide has a structure represented by VL2-L24-VH2-L25-Fc. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL;VL1-L1-CH1;VH1-L1-CL;or VH1-L1-CH1, the first polypeptide has a structure represented by VL1-L19-CL-L20-Fc-L21-TNF1-L22-TNF2-L23-TNF3, and the third polypeptide has a structure represented by VH2-L26-VL2-L27-Fc. In some embodiments, an antigen-binding polypeptide complex of the invention comprises a first polypeptide, a second polypeptide, and a third polypeptide, wherein the first polypeptide has a structure represented by VL1-L1-CL; VL1-L1-CH1; VH1-L1-CL; or VH1-L1-CH1, and wherein (i) the second polypeptide has a structure represented by VH1-CH1-L2-Fc-L3-TNF1-L4-TNF2-L5-TNF3; VH1-CL-L2-Fc-L3-TNF1-L4-TNF2-L5-TNF3; VH1-CH1-L6-Fc; VH1-CL-L7-Fc; VL1-CH1-L2-Fc-L3-TNF1-L4-TNF2-L5-TNF3; VL1-CL-L2-Fc-L3-TNF1-L4 -TNF2-L5-TNF3; VL1-CH1-L6-Fc; or VL1-CL-L7-Fc, and the third polypeptide is VL2-L8-VH2-L9-Fc-L10-TNF1-L11-TNF2-L12-TNF3; or VH2-L13-VL2-L14-Fc-L15-TNF1-L16-TNF2-L17-TN F3, or (ii) the second polypeptide has a structure represented by VH1-CH1-L18-Fc-L19-TNF1-L20-TNF2-L21-TNF3; VH1-CL-L18-Fc-L19-TNF1-L20-TNF2-L21-TNF3; VL1-CH1-L18-Fc-L19-TNF1-L20-TNF2-L21-TNF3;or VL1-CL-L18-Fc-L19-TNF1-L20-TNF2-L21-TNF3, and the third polypeptide has a structure represented by VL2-L22-VH2-L23-Fc or VH2-L24-VL2-L25-Fc, where VL1 is a first immunoglobulin light chain variable region, VL2 is a second immunoglobulin light chain variable region, VH1 is a first immunoglobulin heavy chain variable region, VH2 is a second immunoglobulin heavy chain variable region, and Fc is an immunoglobulin light chain variable region. wherein CH1 is an immunoglobulin heavy chain constant region 1, CL is an immunoglobulin light chain constant region, TNF1 is a first extracellular domain of a tumor necrosis factor superfamily (TNFSF) ligand, TNF2 is a second extracellular domain of the TNFSF ligand, TNF3 is a third extracellular domain of the TNFSF ligand, and L1 to L26 are amino acid linkers. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL; VL1-L1-CH1; VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VH1-CH1-L2-Fc-L3-TNF1-L4-TNF2-L5-TNF3, and the third polypeptide has a structure represented by VL2-L8-VH2-L9-Fc-L10-TNF1-L11-TNF2-L12-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL;VL1-L1-CH1;VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VH1-CH1-L2-Fc-L3-TNF1-L4-TNF2-L5-TNF3, and the third polypeptide has a structure represented by VH2-L13-VL2-L14-Fc-L15-TNF1-L16-TNF2-L17-TNF. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL;VL1-L1-CH1;VH1-L1-CL;or a second polypeptide has a structure represented by VH1-L1-CH1, a second polypeptide has a structure represented by VH1-CL-L2-Fc-L3-TNF1-L4-TNF2-L5-TNF3, and a third polypeptide has a structure represented by VL2-L8-VH2-L9-Fc-L10-TNF1-L11-TNF2-L12-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL; VL1-L1-CH1; VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VH1-CL-L2-Fc-L3-TNF1-L4-TNF2-L5-TNF3, and the third polypeptide has a structure represented by VH2-L13-VL2-L14-Fc-L15-TNF1-L16-TNF2-L17-TNF. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL; VL1-L1-CH1; VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VH1-CH1-L6-Fc, and the third polypeptide has a structure represented by VL2-L8-VH2-L9-Fc-L10-TNF1-L11-TNF2-L12-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL; VL1-L1-CH1; VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VH1-CH1-L6-Fc, and the third polypeptide has a structure represented by VH2-L13-VL2-L14-Fc-L15-TNF1-L16-TNF2-L17-TNF. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL;VL1-L1-CH1;VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VH1-CL-L7-Fc, and the third polypeptide has a structure represented by VL2-L8-VH2-L9-Fc-L10-TNF1-L11-TNF2-L12-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL;VL1-L1-CH1;VH1-L1-CL;or VH1-L1-CH1, the second polypeptide has a structure represented by VH1-CL-L7-Fc, and the third polypeptide has a structure represented by VH2-L13-VL2-L14-Fc-L15-TNF1-L16-TNF2-L17-TNF. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL;VL1-L1-CH1;VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VL1-CH1-L2-Fc-L3-TNF1-L4-TNF2-L5-TNF3, and the third polypeptide has a structure represented by VL2-L8-VH2-L9-Fc-L10-TNF1-L11-TNF2-L12-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL; VL1-L1-CH1; VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VL1-CH1-L2-Fc-L3-TNF1-L4-TNF2-L5-TNF3, and the third polypeptide has a structure represented by VH2-L13-VL2-L14-Fc-L15-TNF1-L16-TNF2-L17-TNF. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL;VL1-L1-CH1;VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VL1-CL-L2-Fc-L3-TNF1-L4-TNF2-L5-TNF3, and the third polypeptide has a structure represented by VL2-L8-VH2-L9-Fc-L10-TNF1-L11-TNF2-L12-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL;VL1-L1-CH1;VH1-L1-CL;or VH1-L1-CH1, the second polypeptide has a structure represented by VL1-CL-L2-Fc-L3-TNF1-L4-TNF2-L5-TNF3, and the third polypeptide has a structure represented by VH2-L13-VL2-L14-Fc-L15-TNF1-L16-TNF2-L17-TNF. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL;VL1-L1-CH1;VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VL1-CH1-L6-Fc, and the third polypeptide has a structure represented by VL2-L8-VH2-L9-Fc-L10-TNF1-L11-TNF2-L12-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL;VL1-L1-CH1;VH1-L1-CL;or VH1-L1-CH1, the second polypeptide has a structure represented by VL1-CH1-L6-Fc, and the third polypeptide has a structure represented by VH2-L13-VL2-L14-Fc-L15-TNF1-L16-TNF2-L17-TNF. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL;VL1-L1-CH1;VH1-L1-CL;or VH1-L1-CH1, and the second polypeptide has a structure represented by VH2-L13-VL2-L14-Fc-L15-TNF1-L16-TNF2-L17-TNF. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL;VL1-L1-CH1;VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VL1-CL-L7-Fc, and the third polypeptide has a structure represented by VH2-L13-VL2-L14-Fc-L15-TNF1-L16-TNF2-L17-TNF. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL; VL1-L1-CH1; VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VH1-CH1-L18-Fc-L19-TNF1-L20-TNF2-L21-TNF3, and the third polypeptide has a structure represented by VL2-L22-VH2-L23-Fc. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL; VL1-L1-CH1; VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VH1-CH1-L18-Fc-L19-TNF1-L20-TNF2-L21-TNF3, and the third polypeptide has a structure represented by VH2-L24-VL2-L25-Fc. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL; VL1-L1-CH1; VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VH1-CL-L18-Fc-L19-TNF1-L20-TNF2-L21-TNF3, and the third polypeptide has a structure represented by VL2-L22-VH2-L23-Fc.In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL; VL1-L1-CH1; VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VH1-CL-L18-Fc-L19-TNF1-L20-TNF2-L21-TNF3, and the third polypeptide has a structure represented by VH2-L24-VL2-L25-Fc. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL; VL1-L1-CH1; VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VL1-CH1-L18-Fc-L19-TNF1-L20-TNF2-L21-TNF3, and the third polypeptide has a structure represented by VL2-L22-VH2-L23-Fc. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL; VL1-L1-CH1; VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VL1-CH1-L18-Fc-L19-TNF1-L20-TNF2-L21-TNF3, and the third polypeptide has a structure represented by VH2-L24-VL2-L25-Fc. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL; VL1-L1-CH1; VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VL1-CL-L18-Fc-L19-TNF1-L20-TNF2-L21-TNF3, and the third polypeptide has a structure represented by VL2-L22-VH2-L23-Fc. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL; VL1-L1-CH1; VH1-L1-CL; or VH1-L1-CH1, the second polypeptide has a structure represented by VL1-CL-L18-Fc-L19-TNF1-L20-TNF2-L21-TNF3, and the third polypeptide has a structure represented by VH2-L24-VL2-L25-Fc.

[0083] In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL, the second polypeptide has a structure represented by VH1-L2-CH1-L3-Fc-L4-TNF1-L5-TNF2-L6-TNF3, and the third polypeptide has a structure represented by VL2-L9-VH2-L10-Fc-L11-TNF1-L12-TNF2-L13-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL, the second polypeptide has a structure represented by VH1-CH1-L2-Fc-L3-TNF1-L4-TNF2-L5-TNF3, and the third polypeptide has a structure represented by VL2-L8-VH2-L9-Fc-L10-TNF1-L11-TNF2-L12-TNF3.

[0084] In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL, the second polypeptide has a structure represented by VH1-L2-CH1-L3-Fc-L4-TNF1-L5-TNF2-L6-TNF3, and the third polypeptide has a structure represented by VH2-L14-VL2-L15-Fc-L16-TNF1-L17-TNF2-L18-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL, the second polypeptide has a structure represented by VH1-L7-CH1-L8-Fc, and the third polypeptide has a structure represented by VL2-L9-VH2-L10-Fc-L11-TNF1-L12-TNF2-L13-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL, the second polypeptide has a structure represented by VH1-L7-CH1-L8-Fc, and the third polypeptide has a structure represented by VH2-L14-VL2-L15-Fc-L16-TNF1-L17-TNF2-L18-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL, the second polypeptide has a structure represented by VH1-L19-CH1-L20-Fc-L21-TNF1-L22-TNF2-L23-TNF3, and the third polypeptide has a structure represented by VL2-L24-VH2-L25-Fc. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL, the second polypeptide has a structure represented by VH1-L19-CH1-L20-Fc-L21-TNF1-L22-TNF2-L23-TNF3, and the third polypeptide has a structure represented by VH2-L26-VL2-L27-Fc. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL, the second polypeptide has a structure represented by VH1-CH1-L2-Fc-L3-TNF1-L4-TNF2-L5-TNF3, and the third polypeptide has a structure represented by VH2-L13-VL2-L14-Fc-L15-TNF1-L16-TNF2-L17-TNF3.In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL, the second polypeptide has a structure represented by VH1-L6-CH1-L7-Fc, and the third polypeptide has a structure represented by VL2-L8-VH2-L9-Fc-L10-TNF1-L11-TNF2-L12-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL, the second polypeptide has a structure represented by VH1-L6-CH1-L7-Fc, and the third polypeptide has a structure represented by VH2-L13-VL2-L14-Fc-L15-TNF1-L16-TNF2-L17-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL, the second polypeptide has a structure represented by VH1-L18-CH1-L19-Fc-L20-TNF1-L21-TNF2-L22-TNF3, and the third polypeptide has a structure represented by VL2-L23-VH2-L24-Fc. In some embodiments, the first polypeptide has a structure represented by VL1-L1-CL, the second polypeptide has a structure represented by VH1-L18-CH1-L19-Fc-L20-TNF1-L21-TNF2-L22-TNF3, and the third polypeptide has a structure represented by VH2-L25-VL2-L26-Fc.

[0085] In some embodiments, the VL1 and VH1 of the antigen-binding polypeptide complex specifically binds CD3.

[0086] In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 22, 28, 185, 298, and 306; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 23, 29, 186, 299, and 307; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 24, 30, 187, 300, and 308. and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 19, 25, 182, 294, and 302; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 20, 26, 183, 295, and 303; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 21, 27, 184, 296, and 304. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:22; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:23; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:24, and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:19; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:20; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:21.In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:28; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:29; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:30, and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:25; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:26; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:27. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 185; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 186; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 187, and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 182; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 183; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 184. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:298; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:299; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:300, and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:294; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:295; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:296.In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 306; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 307; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 308, and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 302; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 303; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 304. As used herein, "at least 90% identity" includes at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% and 100% identity to the recited reference sequence. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO:22; a CDR2 comprising the amino acid sequence of SEQ ID NO:23; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO:24, and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO:19; a CDR2 comprising the amino acid sequence of SEQ ID NO:20; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO:21. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO:28; a CDR2 comprising the amino acid sequence of SEQ ID NO:29; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO:30, and / or the VH1 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO:25; a CDR2 comprising the amino acid sequence of SEQ ID NO:26; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO:27.In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 185; a CDR2 comprising the amino acid sequence of SEQ ID NO: 186; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 187, and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 182; a CDR2 comprising the amino acid sequence of SEQ ID NO: 183; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 184. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 298; a CDR2 comprising the amino acid sequence of SEQ ID NO: 299; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 300, and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 294; a CDR2 comprising the amino acid sequence of SEQ ID NO: 295; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 296. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 306; a CDR2 comprising the amino acid sequence of SEQ ID NO: 307; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 308, and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 302; a CDR2 comprising the amino acid sequence of SEQ ID NO: 303; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 304.

[0087] In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO: 45, and / or the VH1 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO: 43 or 44. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 45, and / or the VH1 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 43. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO: 45, and / or the VH1 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO: 43.In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 45, and / or the VH1 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 44. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO: 45, and / or the VH1 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO: 44.

[0088] In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO: 297 or 305, and / or the VH1 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO: 188, 293 or 301. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO:297, and / or the VH1 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO:293.In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO:305, and / or the VH1 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO:301.

[0089] In some embodiments, the VL2 and VH2 of the antigen-binding polypeptide complex specifically bind to a tumor-associated antigen (TAA) or an immunostimulatory receptor. In some embodiments, the immunostimulatory receptor is CD28. In some embodiments, the TAA is tyrosine protein kinase Met (cMet), trophoblast cell surface antigen 2 (Trop2), CD20, CD19, receptor tyrosine protein kinase erbB-2 (HER2), receptor tyrosine protein kinase erbB-3 (HER3), adenosine A2A receptor (A2AR), proliferation-inducing ligand (APRIL), epidermal growth factor receptor (EGFR), fibroblast growth factor receptor (FGFR), B-cell activation (BAFF), BAFF receptor (BAFFR), B-cell maturation antigen (BCMA), Bruton's tyrosine kinase (BTK), B-lymphocyte and T-lymphocyte attenuator (BTLA), B7DC (programmed death ligand 2), B7 homodimer (B7H), B7-related markers (B7-related markers ... Log 1 (B7H1), B7 homolog 4 (B7H4), delta-like ligand 3 (DLL3), extracellular nucleoside triphosphate diphosphohydrolase 1 (ENTPD1), Fc fragment of IgE receptor 1a (FCER1A), Fc fragment of IgE receptor 1 (FCER1), arachidonate 5-lipoxygenase activating protein (FLAP), folate hydrolase 1 (FOLH1), mucin 1 (MUC-1), CD133, mucin 16 (MUC-16), lysosomal associated membrane protein 1 (LAMP1), CD38, programmed death ligand 1 (PD-L1), CEA cell adhesion molecule 5 (CEACAM5), prostate six transmembrane epithelial antigen 1 (STEAP1), and epithelial cell adhesion molecule (EpCAM). In some embodiments, the TAA is HER2.

[0090] In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 34 or 40; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 35 or 41; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 36 or 42. and / or the VH2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 31 or 37; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 32 or 38; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 33 or 39. In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 34; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 35; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 36, and / or the VH2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 31; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 32; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 33.In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 40; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 41; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 42, and / or the VH2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 37; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 38; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 39. As used herein, "at least 90% identity" includes at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% and 100% identity to the recited reference sequence. In some embodiments, the VL2 of the antigen binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 34; a CDR2 comprising the amino acid sequence of SEQ ID NO: 35; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 36, and / or the VH2 of the antigen binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 31; a CDR2 comprising the amino acid sequence of SEQ ID NO: 32; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 33. In some embodiments, the VL2 of the antigen binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 40; a CDR2 comprising the amino acid sequence of SEQ ID NO: 41; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 42, and / or the VH2 of the antigen binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 37; a CDR2 comprising the amino acid sequence of SEQ ID NO: 38; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 39.

[0091] In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO: 47 or 49, and / or the VH2 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO: 46 or 48. In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 47, and / or the VH2 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 46. In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO: 47, and / or the VH2 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO:46.In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 49, and / or the VH2 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 48. In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO: 49, and / or the VH2 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO:48.

[0092] In some embodiments, the VL2 and VH2 of the antigen-binding polypeptide complex specifically binds CD3.

[0093] In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 22, 28, 185, 298, and 306; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 23, 29, 186, 299, and 307; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 24, 30, 187, 300, and 308. and / or the VH2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 19, 25, 182, 294, and 312; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 20, 26, 183, 295, and 313; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 21, 27, 184, 296, and 314. In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:22; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:23; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:24, and / or the VH2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:19; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:20; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:21.In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:28; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:29; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:30, and / or the VH2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:25; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:26; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:27. In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 185; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 186; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 187, and / or the VH2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 182; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 183; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 184. As used herein, "at least 90% identity" includes at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% and 100% identity to the recited reference sequence. In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO:22; a CDR2 comprising the amino acid sequence of SEQ ID NO:23; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO:24, and / or the VH2 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO:19; a CDR2 comprising the amino acid sequence of SEQ ID NO:20; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO:21.In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 28; a CDR2 comprising the amino acid sequence of SEQ ID NO: 29; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 30, and / or the VH2 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 25; a CDR2 comprising the amino acid sequence of SEQ ID NO: 26; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 27. In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 185; a CDR2 comprising the amino acid sequence of SEQ ID NO: 186; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 187, and / or the VH2 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 182; a CDR2 comprising the amino acid sequence of SEQ ID NO: 183; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 184. In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:298; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:299; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:300, and / or the VH2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:294; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:295; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:296.In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:306; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:307; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:308, and / or the VH2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:312; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:313; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:314.

[0094] In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO: 45, and / or the VH2 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO: 43 or 44. In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 45, and / or the VH2 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 43. In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO: 45, and / or the VH2 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO:43.In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 45, and / or the VH2 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 44. In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO: 45, and / or the VH2 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO: 44.

[0095] In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO:297, and / or the VH2 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO:293.

[0096] In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO:305, and / or the VH2 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO:301.

[0097] In some embodiments, the VL1 and VH1 of the antigen-binding polypeptide complex specifically bind to a TAA or an immunostimulatory receptor. In some embodiments, the immunostimulatory receptor is CD28. In some embodiments, the TAA is cMet, Trop2, CD20, CD19, HER2, HER3, A2AR, APRIL, EGFR, FGFR, BAFF, BAFFR, BCMA, BTK, BTLA, B7DC, B7H1, B7H4, DLL3, ENTPD1, ​​FCER1A, FCER1, FLAP, FOLH1, MUC-1, CD133, MUC-16, LAMP1, CD38, PD-L1, CEACAM5, STEAP1, or EpCAM. In some embodiments, the TAA is HER2.

[0098] In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 34 or 40; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 35 or 41; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 36 or 42. and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 31 or 37; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 32 or 38; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 33 or 39. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 34; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 35; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 36, and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 31; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 32; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 33.In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 40; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 41; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 42, and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 37; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 38; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 39. As used herein, "at least 90% identity" includes at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% and 100% identity to the recited reference sequence. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 34; a CDR2 comprising the amino acid sequence of SEQ ID NO: 35; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 36, and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 31; a CDR2 comprising the amino acid sequence of SEQ ID NO: 32; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 33. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 40; a CDR2 comprising the amino acid sequence of SEQ ID NO: 41; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 42, and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 37; a CDR2 comprising the amino acid sequence of SEQ ID NO: 38; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 39.

[0099] In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO: 47 or 49, and / or the VH1 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO: 46 or 48. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO:47, and / or the VH1 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO:46.In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 49, and / or the VH1 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 48. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO: 47, and / or the VH1 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO: 46. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO:49 and / or the VH1 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO:48.

[0100] In some embodiments, the antigen-binding polypeptide complex comprises a VH and / or a VL that specifically binds CD20. In some embodiments, the VL comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 314 or 322; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 315 or 323; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 316 or 324. and / or the VH comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 310 or 318; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 311 or 319; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 312 or 320. In some embodiments, the VL comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:314; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:315; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:316, and / or the VH comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:310; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:311; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:312.In some embodiments, the VL comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:322; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:323; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:324, and / or the VH comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:318; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:319; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:320. In some embodiments, the VL comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:313 or 321, and / or the VH comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:309 or 317. In some embodiments, the VL comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:313, and / or the VH comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:309. In some embodiments, the VL comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 321, and / or the VH comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 317.As used herein, "at least 90% identity" includes at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% and 100% identity to the recited reference sequence.

[0101] In some embodiments, the antigen-binding polypeptide complex comprises a VH and / or a VL that specifically binds cMet. In some embodiments, the VL comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:274; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:275; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:276, and / or the VH comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:270; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:271; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:272. In some embodiments, the VL comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 273, and / or the VH comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 269. As used herein, "at least 90% identity" includes at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% and 100% identity to the recited reference sequence.

[0102] In some embodiments, the antigen-binding polypeptide complex comprises a VH and / or a VL that specifically binds Trop2. In some embodiments, the VL comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:282; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:283; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:284, and / or the VH comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:278; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:279; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:280. In some embodiments, the VL comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 281, and / or the VH comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 277. As used herein, "at least 90% identity" includes at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% and 100% identity to the recited reference sequence.

[0103] In some embodiments, the antigen-binding polypeptide complex comprises a VH and / or a VL that specifically binds CD19. In some embodiments, the VL comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:290; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:291; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:292, and / or the VH comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:286; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:287; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:288. In some embodiments, the VL comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 289, and / or the VH comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 285. As used herein, "at least 90% identity" includes at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% and 100% identity to the recited reference sequence.

[0104] In some embodiments, an antigen-binding polypeptide complex of the invention comprises a first polypeptide and a second polypeptide, wherein (i) the first polypeptide is selected from the group consisting of VL1-L1-VH1-L2-Fc; VH1-L3-VL1-L4-Fc; VL1-L5-VH1-L6-CL-L7-CH1-L8-Fc; VL1-L5-VH1-L6-CH1-L7-CL-L8-Fc; VH1-L5-VL1-L6-CL-L7-CH1-L8-Fc; VH1-L5-VL1-L6-CH1-L7-CL-L8-Fc; VH1-L5-VL1-L6-CH1-L7-CL-L8-Fc; VL1-L9-CL- L10-VH1-L11-CH1-L12-Fc;VL1-L9-CH1-L10-VH1-L11-CL-L12-Fc;VH1-L9-CL-L10-VL1-L11-CH1-L12-Fc;VH1-L9-CH1-L10-VL1-L11-CL-L12- FC H1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-L23-VH1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-L23-VL1-L24-CL-L 25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-L23-VL1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-VH1-L14-Fc-L1 5-TNF1-L16-TNF2-L17-TNF3;VH1-VL1-L19-Fc-L20-TNF1-L21-TNF2-L22-TNF3;VL1-VH1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29- TNF3;VL1-VH1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-VL1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-VL1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3; F3;VL1-L30-CH1-L31-VH1-L32-CL-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3; L36-TNF3;which is VH1-L30-CH1-L31-VL1-L32-CL-L33-Fc-L34-TNF1-L 35-TNF2-L36-TNF3 contains the 2 subunits VL2-L37-VH2-L38-F c-L39-TNF1-L40-TNF2-L41-TNF3;VH2-L42-VL2-L43-Fc-L44-TNF1-L45-TNF2-L46-TNF3; 1-L52-TNF2-L53-TNF3;and they are VL2-L54-CL-L55-VH2-L56-CH1-L57-Fc-L58-TNF1-L59-TNF2-L60-TNF3; -Fc-L51-TNF1-L52-TNF2-L53-TNF3;VL2-L54-CH1-L55-VH2-L56-CL-L57-Fc-L58-TNF1-L59-TNF2-L60-TNF3; L40-TNF2-L41-TNF3;VH2-VL2-L43-Fc-L44-TNF1-L45-TNF2-L46-TNF3; 3;VL2-CL-L55-VH2-L56-CH1-L57-Fc-L58-TNF1-L59-TNF2-L60-TNF3;or VL2-CH1-L55-VH2-L56-CL-L57-Fc-L58-TNF1-L59-TNF2-L60-TNF3; or (ii) the first polypeptide has the structure represented by VL1-L61-VH1-L62-Fc-L63-TNF1-L64-TNF2-L65-TNF3; VH1-L66-V L1-L67-Fc-L68-TNF1-L69-TNF2-L70-TNF3;VL1-L71-VH1-L72-CL-L73-CH1-L74-Fc-L75- TNF1-L76-TNF2-L77-TNF3;VL1-L71-VH1-L72-CH1-L73-CL-L74-Fc-L75-TNF1-L76-TNF2- L77-TNF3; VL1-L78-CL-L79-VH1-L80-CH1-L81-Fc-L82-TNF1-L83-TNF2-L84-TNF3; or VL1-L78-CH1-L79-VH1-L80-CL-L81-Fc-L82-TNF1-L83-TNF2-L84-TNF3, The two polypeptides are: VL2-L85-VH2-L86-Fc; VH2-L87-VL2-L88-Fc; VL2-L89-VH2-L90-CL-L91-CH1-L92-Fc; VL2-L89-VH2-L90-CH1-L91-CL-L92-Fc; VL2-L93-CL-L94-VH2-L95-CH1-L96-Fc;or has a structure represented by VL2-L93-CH1-L94-VH2-L95-CL-L96-Fc, where VL1 is a first immunoglobulin light chain variable region, VL2 is a second immunoglobulin light chain variable region, VH1 is a first immunoglobulin heavy chain variable region, VH2 is a second immunoglobulin heavy chain variable region, Fc is a region comprising immunoglobulin heavy chain constant region 2 (CH2), immunoglobulin heavy chain constant region 3 (CH3), and optionally an immunoglobulin hinge, CH1 is immunoglobulin heavy chain constant region 1, CL is an immunoglobulin light chain constant region, TNF1 is a first extracellular domain of a TNFSF ligand, TNF2 is a second extracellular domain of a TNFSF ligand, and TNF3 is a third extracellular domain of a TNFSF ligand, and L1-L96 is an amino acid linker. In some embodiments, the first polypeptide is selected from the group consisting of VL1-L1-VH1-L2-Fc; VH1-L3-VL1-L4-Fc; VL1-L5-VH1-L6-CL-L7-CH1-L8-Fc; VL1-L5-VH1-L6-CH1-L7-CL-L8-Fc; VH1-L5-VL1-L6-CL-L7-CH1-L8-Fc ;VH1-L5-VL1-L6-CH1-L7-CL-L8-Fc;VL1-L9-CL-L10-VH1-L11-CH1-L12-Fc;VL1-L9-CH 1-L10-VH1-L11-CL-L12-Fc;VH1-L9-CL-L10-VL1-L11-CH1-L12-Fc;VH1-L9-CH1-L10-V L1-L11-CL-L12-Fc;VL1-L13-VH1-L14-Fc-L15-TNF1-L16-TNF2-L17-TNF3;VH1-L18-VL 1-L19-Fc-L20-TNF1-L21-TNF2-L22-TNF3;VL1-L23-VH1-L24-CL-L25-CH1-L26-Fc-L27 -TNF1-L28-TNF2-L29-TNF3;VL1-L23-VH1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TN F2-L29-TNF3;VH1-L23-VL1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-L23-VL1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-VH1-L14-Fc-L15-TNF1-L16 -TNF2-L17-TNF3;VH1-VL1-L19-Fc-L20-TNF1-L21-TNF2-L22-TNF3;VL1-VH1-L24-CL-L25-CH1-L26-Fc-L 27-TNF1-L28-TNF2-L29-TNF3;VL1-VH1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-V L1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-VL1-L24-CH1-L25-CL-L26-Fc-L27-TN F1-L28-TNF2-L29-TNF3;VL1-L30-CL-L31-VH1-L32-CH1-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3;VL1-L3 0-CH1-L31-VH1-L32-CL-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3;VH1-L30-CL-L31-VL1-L32-CH1-L33-Fc -L34-TNF1-L35-TNF2-L36-TNF3; or VH1-L30-CH1-L31-VL1-L32-CL-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3, and the second polypeptide has the structure represented by VL2-L37-VH2-L38-Fc-L39-TNF1-L40-TNF2-L41-TNF3. In some embodiments, the first polypeptide is selected from the group consisting of VL1-L1-VH1-L2-Fc; VH1-L3-VL1-L4-Fc; VL1-L5-VH1-L6-CL-L7-CH1-L8-Fc; VL1-L5-VH1-L6-CH1-L7-CL-L8-Fc; VH1-L5-VL1-L6-CL-L7-C H1-L8-Fc;VH1-L5-VL1-L6-CH1-L7-CL-L8-Fc;VL1-L9-CL-L10-VH1-L11-CH1-L12- Fc;VL1-L9-CH1-L10-VH1-L11-CL-L12-Fc;VH1-L9-CL-L10-VL1-L11-CH1-L12-Fc;VH1-L9-CH1-L10-VL1-L11-CL-L12-Fc;VL1-L13-VH1-L14-Fc-L15-TNF1-L16-TNF2-L17-TNF3;VH1-L18-VL1-L19-Fc-L20-TNF1-L21-TNF2-L22-TNF3;VL1-L23-VH1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-L23-VH1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-L23-VL1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-L23-VL1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-VH1-L14-Fc-L15-TNF1-L16-TNF2-L17-TNF3;VH1-VL1-L19-Fc-L20-TNF1-L21-TNF2-L22-TNF3;VL1-VH1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-VH1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-VL1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TN; F3;VH1-VL1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-L30-CL-L31-VH1-L32-CH1-L33-Fc-L34 -TNF1-L35-TNF2-L36-TNF3;VL1-L30-CH1-L31-VH1-L32-CL-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3;VH1-L30-CL-L3 1-VL1-L32-CH1-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3; or VH1-L30-CH1-L31-VL1-L32-CL-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3, and the second polypeptide has the structure represented by VH2-L42-VL2-L43-Fc-L44-TNF1-L45-TNF2-L46-TNF3. In some embodiments, the first polypeptide is selected from the group consisting of VL1-L1-VH1-L2-Fc; VH1-L3-VL1-L4-Fc; VL1-L5-VH1-L6-CL-L7-CH1-L8-Fc; VL1-L5-VH1-L6-CH1-L7-CL-L8-Fc; VH1-L5-VL1-L6-CL-L7-CH1-L8-Fc ;VH1-L5-VL1-L6-CH1-L7-CL-L8-Fc;VL1-L9-CL-L10-VH1-L11-CH1-L12-Fc;VL1-L9-CH 1-L10-VH1-L11-CL-L12-Fc;VH1-L9-CL-L10-VL1-L11-CH1-L12-Fc;VH1-L9-CH1-L10-V L1-L11-CL-L12-Fc;VL1-L13-VH1-L14-Fc-L15-TNF1-L16-TNF2-L17-TNF3;VH1-L18-VL 1-L19-Fc-L20-TNF1-L21-TNF2-L22-TNF3;VL1-L23-VH1-L24-CL-L25-CH1-L26-Fc-L27 -TNF1-L28-TNF2-L29-TNF3;VL1-L23-VH1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TN F2-L29-TNF3;VH1-L23-VL1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-L23-VL1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-VH1-L14-Fc-L15-TNF1-L16- TNF2-L17-TNF3;VH1-VL1-L19-Fc-L20-TNF1-L21-TNF2-L22-TNF3;VL1-VH1-L24-CL-L25-CH1-L26-Fc-L27- TNF1-L28-TNF2-L29-TNF3;VL1-VH1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-VL1-L2 4-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-VL1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28- TNF2-L29-TNF3;VL1-L30-CL-L31-VH1-L32-CH1-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3;VL1-L30-CH1-L31 -VH1-L32-CL-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3;VH1-L30-CL-L31-VL1-L32-CH1-L33-Fc-L34-TNF1-L 35-TNF2-L36-TNF3; or VH1-L30-CH1-L31-VL1-L32-CL-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3, and the second polypeptide has the structure represented by VL2-L47-VH2-L48-CL-L49-CH1-L50-Fc-L51-TNF1-L52-TNF2-L53-TNF3. In some embodiments, the first polypeptide is selected from the group consisting of VL1-L1-VH1-L2-Fc; VH1-L3-VL1-L4-Fc; VL1-L5-VH1-L6-CL-L7-CH1-L8-Fc; VL1-L5-VH1-L6-CH1-L7-CL-L8-Fc; VH1-L5-VL1-L6-CL-L7-C H1-L8-Fc;VH1-L5-VL1-L6-CH1-L7-CL-L8-Fc;VL1-L9-CL-L10-VH1-L11-CH1-L12- Fc;VL1-L9-CH1-L10-VH1-L11-CL-L12-Fc;VH1-L9-CL-L10-VL1-L11-CH1-L12-Fc;VH1-L9-CH1-L10-VL1-L11-CL-L12-Fc;VL1-L13-VH1-L14-Fc-L15-TNF1-L16-TNF2-L17-TNF3;VH1-L18-VL1-L19-Fc-L20-TNF1-L21-TNF2-L22-TNF3;VL1-L23-VH1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-L23-VH1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-L23-VL1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-L23-VL1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-VH1-L14-Fc-L15-TNF1-L16-TNF2-L17-TNF3;VH1-VL1-L19-Fc-L20-TNF1-L21-TNF2-L22-TNF3;VL1-VH1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-VH1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-VL1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-VL1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-L30-CL-L31-VH1-L32-CH1-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3;VL1-L30-CH1-L31-VH1-L32-CL-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3;VH1-L30-CL-L31-VL1-L32-CH1-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3;or VH1-L30-CH1-L31-VL1-L32-CL-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3, and the second polypeptide has the structure represented by VL2-L54-CL-L55-VH2-L56-CH1-L57-Fc-L58-TNF1-L59-TNF2-L60-TNF3. In some embodiments, the first polypeptide is selected from the group consisting of VL1-L1-VH1-L2-Fc; VH1-L3-VL1-L4-Fc; VL1-L5-VH1-L6-CL-L7-CH1-L8-Fc; VL1-L5-VH1-L6-CH1-L7-CL-L8-Fc; VH1-L5-VL1-L6-CL-L7-CH1-L8-Fc; VH1-L5-VL1-L6-CH1-L7-CL-L8-Fc; VH1-L5-VL1-L6-CH1-L7-CL-L8-Fc; VL1-L9-CL-L10-VH1-L 11-CH1-L12-Fc;VL1-L9-CH1-L10-VH1-L11-CL-L12-Fc;VH1-L9-CL-L10-VL1-L11-CH1-L12-Fc;VH1-L9-CH1-L10-VL1 -L11-CL-L12-Fc;VL1-L13-VH1-L14-Fc-L15-TNF1-L16-TNF2-L17-TNF3;VH1-L18-VL1-L19-Fc-L20-TNF1-L21-TNF2-L 22-TNF3;VL1-L23-VH1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-L23-VH1-L24-CH1-L25-CL-L2 6-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-L23-VL1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-L 23-VL1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-VH1-L14-Fc-L15-TNF1-L16-TNF2-L17-TNF3; VH1-VL1-L19-Fc-L20-TNF1-L21-TNF2-L22-TNF3;VL1-VH1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-VH1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-VL1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-VL1-L24-CH1 -L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-L30-CL-L31-VH1-L32-CH1-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3;VL1-L30-CH1-L31-VH1-L32-CL -L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3; VH1-L30-CL-L31-VL1-L32-CH1-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3; or VH1-L30-CH1-L31-VL1-L32-CL-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3, and the second polypeptide has the structure represented by VL2-L47-VH2-L48-CH1-L49-CL-L50-Fc-L51-TNF1-L52-TNF2-L53-TNF3. In some embodiments, the first polypeptide is selected from the group consisting of VL1-L1-VH1-L2-Fc; VH1-L3-VL1-L4-Fc; VL1-L5-VH1-L6-CL-L7-CH1-L8-Fc; VL1-L5-VH1-L6-CH1-L7-CL-L8-Fc; VH1-L5-VL1-L6-CL-L7-CH1-L8-Fc; VH1-L5-VL1-L6-CH1-L7-CL-L8-Fc; VH1-L5-VL1-L6-CH1-L7-CL-L8-Fc; VL1-L9-CL-L10-VH1-L11-CH1-L12-Fc; VL1-L9-CH1-L10-VH1-L1 1-CL-L12-Fc;VH1-L9-CL-L10-VL1-L11-CH1-L12-Fc;VH1-L9-CH1-L10-VL1-L11-CL-L12-Fc;VL1-L13-VH1-L14-Fc-L15-TNF1-L16-TNF2- L17-TNF3;VH1-L18-VL1-L19-Fc-L20-TNF1-L21-TNF2-L22-TNF3;VL1-L23-VH1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-L23-VH1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-L23-VL1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-L23-VL1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-VH1-L14-Fc-L15-TNF1-L16-TNF2-L17-TNF3;VH1-VL1-L19-Fc-L20-TNF1-L21-TNF2-L22-TNF3;VL1-VH1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-VH1-L24-CH1-L25-CL-L26-Fc-L27-; TNF1-L28-TNF2-L29-TNF3;VH1-VL1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-VL1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L 28-TNF2-L29-TNF3;VL1-L30-CL-L31-VH1-L32-CH1-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3;VL1-L30-CH1-L31-VH1-L32-CL-L33-Fc-L34-TNF1- L35-TNF2-L36-TNF3; VH1-L30-CL-L31-VL1-L32-CH1-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3; or VH1-L30-CH1-L31-VL1-L32-CL-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3, and the second polypeptide has the structure represented by VL2-L54-CH1-L55-VH2-L56-CL-L57-Fc-L58-TNF1-L59-TNF2-L60-TNF3. In some embodiments, the first polypeptide is selected from the group consisting of VL1-L1-VH1-L2-Fc; VH1-L3-VL1-L4-Fc; VL1-L5-VH1-L6-CL-L7-CH1-L8-Fc; VL1-L5-VH1-L6-CH1-L7-CL-L8-Fc; VH1-L5-VL1-L6-CL-L7-CH1-L8-Fc; VH1-L5-VL1-L6-CH1-L7-CL-L8-Fc; VH1-L5-VL1-L6-CH1-L7-CL-L8-Fc; VL1-L9-CL-L10-VH1-L11-CH1-L12-Fc; VL1-L9-CH1-L10-VH1-L1 1-CL-L12-Fc;VH1-L9-CL-L10-VL1-L11-CH1-L12-Fc;VH1-L9-CH1-L10-VL1-L11-CL-L12-Fc;VL1-L13-VH1-L14-Fc-L15-TNF1-L16-TNF2- L17-TNF3;VH1-L18-VL1-L19-Fc-L20-TNF1-L21-TNF2-L22-TNF3;VL1-L23-VH1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-L23-VH1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-L23-VL1-L24-CL-L25-CH1-L26-Fc-L27-TNF 1-L28-TNF2-L29-TNF3;VH1-L23-VL1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-VH1-L14-Fc-L15-TNF 1-L16-TNF2-L17-TNF3;VH1-VL1-L19-Fc-L20-TNF1-L21-TNF2-L22-TNF3;VL1-VH1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L2 8-TNF2-L29-TNF3;VL1-VH1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-VL1-L24-CL-L25-CH1-L26-Fc- L27-TNF1-L28-TNF2-L29-TNF3;VH1-VL1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-L30-CL-L31-VH1 -L32-CH1-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3;VL1-L30-CH1-L31-VH1-L32-CL-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3 ;VH1-L30-CL-L31-VL1-L32-CH1-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3; or VH1-L30-CH1-L31-VL1-L32-CL-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3, and the second polypeptide has the structure represented by VL2-VH2-L38-Fc-L39-TNF1-L40-TNF2-L41-TNF3. In some embodiments, the first polypeptide is VL1-L1-VH1-L2-Fc; VH1-L3-VL1-L4-Fc; VL1-L5-VH1-L6-CL-L7-CH1-L8-Fc; VL1-L5-VH1-L6-CH1-L7-CL-L8-Fc; VH1-L5-VL1-L6-CL-L7-CH1-L8-Fc; VH1-L5-VL1-L6-CL-L7-CH1-L8-Fc; VH1-L5-VL1-L6-CH1-L7-CL-L8-Fc;VL1-L9-CL-L10-VH1-L11-CH1-L12-Fc;VL1-L9-CH1-L10-VH1-L11-CL-L12-Fc;VH1-L9-CL-L10-VL1-L11-CH1-L12-Fc;VH1-L9-CH1-L10-VL1-L11-CL-L12-Fc;VL1-L13-VH1-L14-Fc-L15-TNF1-L16-TNF2-L17-TNF3;VH1-L18-VL1-L19-Fc-L20-TNF1-L21-TNF2-L22-TNF3;VL1-L23-VH1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-L23-VH1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-L23-VL1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-L23-VL1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-VH1-L14-Fc-L15-TNF1-L16-TNF2-L17-TNF3;VH1-VL1-L19-Fc-L20-TNF1-L21-TNF2-L22-TNF3;VL1-VH1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-VH1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-VL1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-VL1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-L30-CL-L31-VH1-L32-CH1-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3;VL1-L30-CH1-L31-VH1-L32-CL-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3;VH1-L30-CL-L31-VL1-L32-CH1-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3;or VH1-L30-CH1-L31-VL1-L32-CL-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3, and the second polypeptide has the structure represented by VH2-VL2-L43-Fc-L44-TNF1-L45-TNF2-L46-TNF3. In some embodiments, the first polypeptide is VL1-L1-VH1-L2-Fc; VH1-L3-VL1-L4-Fc; VL1-L5-VH1-L6-CL-L7-CH1-L8-Fc; VL1-L5-VH1-L6-CH1-L7-CL-L8-Fc; VH1-L5-VL1-L6-CL-L7-CH1-L8-Fc; VH1-L5-VL1-L6-CH1-L7-CL-L8-Fc; VH1-L5-VL1-L6-CH1-L7-CL-L8-Fc; VL1-L9-CL-L10-VH1-L11-CH1-L12-Fc; VL1-L9-CH1-L10-VH1-L11-CL-L12-Fc;VH1-L9-CL-L10-VL1-L11-CH1-L12-Fc;VH1-L9-CH1-L10-VL1-L11-CL-L12-Fc;VL1-L1 3-VH1-L14-Fc-L15-TNF1-L16-TNF2-L17-TNF3;VH1-L18-VL1-L19-Fc-L20-TNF1-L21-TNF2-L22-TNF3;VL1-L23-VH1-L24-CL-L VH1 -L23-VL1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-L23-VL1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-T VL1-VH1- L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-VH1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-VL1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-VL1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3; VL1-L30-CL-L31-VH1-L32-CH1-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3;VL1-L30-CH1-L31-VH1-L32-CL-L33-Fc-L34-TNF1-L35-TNF2-L 36-TNF3; VH1-L30-CL-L31-VL1-L32-CH1-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3; or VH1-L30-CH1-L31-VL1-L32-CL-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3, and the second polypeptide has the structure represented by VL2-VH2-L48-CL-L49-CH1-L50-Fc-L51-TNF1-L52-TNF2-L53-TNF3. In some embodiments, the first polypeptide is selected from the group consisting of VL1-L1-VH1-L2-Fc; VH1-L3-VL1-L4-Fc; VL1-L5-VH1-L6-CL-L7-CH1-L8-Fc; VL1-L5-VH1-L6-CH1-L7-CL-L8-Fc; VH1-L5-VL1-L6-CL-L7-CH1-L8-Fc; VH1-L5-VL1-L6-CH1-L7-CL-L8-Fc; VH1-L5-VL1-L6-CH1-L7-CL-L8-Fc; VL1-L9-CL-L10-VH1-L11-CH1-L12-Fc; VL1-L9-CH1-L10-VH1-L11-CL-L12-Fc; VH1-L9-CL-L10-VL1- L11-CH1-L12-Fc;VH1-L9-CH1-L10-VL1-L11-CL-L12-Fc;VL1-L13-VH1-L14-F c-L15-TNF1-L16-TNF2-L17-TNF3;VH1-L18-VL1-L19-Fc-L20-TNF1-L21-TNF2- L22-TNF3;VL1-L23-VH1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-L23-VH1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;<h2 style=";text-align:left;direction:ltr">VH1-L23-VL1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-L23-VL1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-VH1-L14-Fc-L15-TNF1-L16-TNF2-L17-TNF3;VH1-VL1-L19-Fc-L20-TNF1-L21-TNF2-L22-TNF3;VL1-VH1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L2;<h2 style=";text-align:left;direction:ltr"> 8-TNF2-L29-TNF3;VL1-VH1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-VL1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH 1-VL1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-L30-CL-L31-VH1-L32-CH1-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3;VL1-L30-CH1-L31- VH1-L32-CL-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3; VH1-L30-CL-L31-VL1-L32-CH1-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3; or VH1-L30-CH1-L31-VL1-L32-CL-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3, and the second polypeptide has the structure represented by VL2-CL-L55-VH2-L56-CH1-L57-Fc-L58-TNF1-L59-TNF2-L60-TNF3. In some embodiments, the first polypeptide is selected from the group consisting of VL1-L1-VH1-L2-Fc; VH1-L3-VL1-L4-Fc; VL1-L5-VH1-L6-CL-L7-CH1-L8-Fc; VL1-L5-VH1-L6-CH1-L7-CL-L8-Fc; VH1-L5-VL1-L6-CL-L7-CH1-L8-Fc; VH1-L5-VL1-L6-CH1-L7-CL-L8-Fc; VH1-L5-VL1-L6-CH1-L7-CL-L8-Fc; VL1-L9-CL-L10-VH1-L11-CH1-L12-Fc; VL1-L9-CH1-L10-VH1-L1 1-CL-L12-Fc;VH1-L9-CL-L10-VL1-L11-CH1-L12-Fc;VH1-L9-CH1-L10-VL1-L11-CL-L12-Fc;VL1-L13-VH1-L14-Fc-L15-TNF1-L16-TNF2- L17-TNF3;VH1-L18-VL1-L19-Fc-L20-TNF1-L21-TNF2-L22-TNF3;VL1-L23-VH1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-L23-VH1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-L23-VL1-L24-CL-L25-CH1-L26-Fc-L27-TNF1- L28-TNF2-L29-TNF3;VH1-L23-VL1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-VH1-L14-Fc-L15-TNF1-L1 6-TNF2-L17-TNF3;VH1-VL1-L19-Fc-L20-TNF1-L21-TNF2-L22-TNF3;VL1-VH1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF 2-L29-TNF3;VL1-VH1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-VL1-L24-CL-L25-CH1-L26-Fc-L27-TNF 1-L28-TNF2-L29-TNF3;VH1-VL1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VL1-L30-CL-L31-VH1-L32-CH1- VH1-L30-CL -L31-VL1-L32-CH1-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3; or VH1-L30-CH1-L31-VL1-L32-CL-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3, and the second polypeptide has the structure represented by VL2-VH2-L48-CH1-L49-CL-L50-Fc-L51-TNF1-L52-TNF2-L53-TNF3. In some embodiments, the first polypeptide is VL1-L1-VH1-L2-Fc; VH1-L3-VL1-L4-Fc; VL1-L5-VH1-L6-CL-L7-CH1-L8-Fc; VL1-L5-VH1-L6-CH1-L7-CL-L8-Fc; VH1-L5-VL1-L6-CL-L7-CH1-L8-Fc;<h2 style=";text-align:left;direction:ltr">VH1-L5-VL1-L6-CH1-L7-CL-L8-Fc;VL1-L9-CL-L10-VH1-L11-CH1-L12-Fc;VL1-L9-CH1-L10-VH1-L11-CL-L12-Fc;VH1-L9-CL-L10-VL1-L11-CH1-L1 2-Fc;VH1-L9-CH1-L10-VL1-L11-CL-L12-Fc;VL1-L13-VH1-L14-Fc-L15-T NF1-L16-TNF2-L17-TNF3;VH1-L18-VL1-L19-Fc-L20-TNF1-L21-TNF2-L22 -TNF3 ;VL1-L23-VH1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3 NF3 ;VH1-L23-VL1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3 3:VL1-VH1-L14-Fc-L15-TNF1-L16-TNF2-L17-TNF3;VH1-VL1-L19-Fc-L20-TNF1-L21-TNF2-L22-TNF3 -L28-TNF2-L29-TNF3;VL1-VH1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3;VH1-VL1-L24-CL-L25-CH1-L26-Fc-L27-TNF1-L28-TNF2- L29-TNF3 ;VH1-VL1-L24-CH1-L25-CL-L26-Fc-L27-TNF1-L28-TNF2-L29-TNF3 F3;VL1-L30-CH1-L31-VH1-L32-CL-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3;or VH1-L30-CH1-L31-VL1-L32-CL-L33-Fc-L34-TNF1-L35-TNF2-L36-TNF3, and the second polypeptide has a structure represented by VL2-CH1-L55-VH2-L56-CL-L57-Fc-L58-TNF1-L59-TNF2-L60-TNF3. For example, the first polypeptide may have a structure represented by VL1-L13-VH1-L14-Fc-L15-TNF1-L16-TNF2-L17-TNF3, and the second polypeptide may have a structure represented by VL2-L37-VH2-L38-Fc-L39-TNF1-L40-TNF2-L41-TNF3. In some embodiments, the first polypeptide is VL1-L61-VH1-L62-Fc-L63-TNF1-L64-TNF2-L65-TNF3; VH1-L66-VL1-L67-Fc-L68-TNF1-L69-TNF2-L70-TNF3; VL1-L71-VH1-L72-CL-L73-CH1-L74-Fc-L75-TNF1-L76-TNF2-L77-TNF3; VL1-L71-VH1-L72-CH1-L73-CL-L74-Fc -L75-TNF1-L76-TNF2-L77-TNF3; VL1-L78-CL-L79-VH1-L80-CH1-L81-Fc-L82-TNF1-L83-TNF2-L84-TNF3; or VL1-L78-CH1-L79-VH1-L80-CL-L81-Fc-L82-TNF1-L83-TNF2-L84-TNF3, and the second polypeptide has the structure represented by VL2-L85-VH2-L86-Fc. In some embodiments, the first polypeptide is VL1-L61-VH1-L62-Fc-L63-TNF1-L64-TNF2-L65-TNF3; VH1-L66-VL1-L67-Fc-L68-TNF1-L69-TNF2-L70-TNF3; VL1-L71-VH1-L72-CL-L73-CH1-L74-Fc-L75-TNF1-L76-TNF2-L77-TNF3; VL1-L71-VH1-L72-CH1-L73-CL-L74-Fc-L75-TNF1-L76-TNF2-L77-TNF3;VL1-L78-CL-L79-VH1-L80-CH1-L81-Fc-L82-TNF1-L83-TNF2-L84-TNF3; or VL1-L78-CH1-L79-VH1-L80-CL-L81-Fc-L82-TNF1-L83-TNF2-L84-TNF3, and the second polypeptide has the structure represented by VH2-L87-VL2-L88-Fc. In some embodiments, the first polypeptide is VL1-L61-VH1-L62-Fc-L63-TNF1-L64-TNF2-L65-TNF3; VH1-L66-VL1-L67-Fc-L68-TNF1-L69-TNF2-L70-TNF3; VL1-L71-VH1-L72-CL-L73-CH1-L74-Fc-L75-TNF1-L76-TNF2-L77-TNF3; VL1-L71-VH1-L72-CH1-L73-CL-L74-Fc-L75-TNF 1-L76-TNF2-L77-TNF3; VL1-L78-CL-L79-VH1-L80-CH1-L81-Fc-L82-TNF1-L83-TNF2-L84-TNF3; or VL1-L78-CH1-L79-VH1-L80-CL-L81-Fc-L82-TNF1-L83-TNF2-L84-TNF3, and the second polypeptide has the structure represented by VL2-L89-VH2-L90-CL-L91-CH1-L92-Fc. In some embodiments, the first polypeptide is selected from the group consisting of VL1-L61-VH1-L62-Fc-L63-TNF1-L64-TNF2-L65-TNF3; VH1-L66-VL1-L67-Fc-L68-TNF1-L69-TNF2-L70-TNF3; VL1-L71-VH1-L72-CL-L73-CH1-L74-Fc- L75-TNF1-L76-TNF2-L77-TNF3;VL1-L71-VH1-L72-CH1-L73-CL-L74-Fc-L75-TNF1-L76- TNF2-L77-TNF3;VL1-L78-CL-L79-VH1-L80-CH1-L81-Fc-L82-TNF1-L83-TNF2-L84-TNF3;or VL1-L78-CH1-L79-VH1-L80-CL-L81-Fc-L82-TNF1-L83-TNF2-L84-TNF3, and the second polypeptide has a structure represented by VL2-L93-CL-L94-VH2-L95-CH1-L96-Fc. In some embodiments, the first polypeptide has a structure represented by VL1-L61-VH1-L62-Fc-L63-TNF1-L64-TNF2-L65-TNF3; VH1-L66-VL1-L67-Fc-L68-TNF1-L69-TNF2-L70-TNF3; VL1-L71-VH1-L72-CL-L73-CH; 1-L74-Fc-L75-TNF1-L76-TNF2-L77-TNF3;VL1-L71-VH1-L72-CH1-L73-CL-L74-Fc-L75- TNF1-L76-TNF2-L77-TNF3; or VL1-L78-CL-L79-VH1-L80-CH1-L81-Fc-L82-TNF1-L83-T TNFI-L84-TNF3; or VL1-L78-CH1-L79-VH1-L80-CL-L81-Fc-L82-TNF1-L83-TNF2-L84-TNF3, and the second polypeptide has the structure represented by VL2-L89-VH2-L90-CH1-L91-CL-L92-Fc. In some embodiments, the first polypeptide is VL1-L61-VH1-L62-Fc-L63-TNF1-L64-TNF2-L65-TNF3; VH1-L66-VL1-L67-Fc-L68-TNF1-L69-TNF2-L70-TNF3; VL1-L71-VH1-L72-CL-L73-CH1-L74-Fc-L75-TNF1-L76-TNF2-L77-TNF3; VL1-L71-VH1-L72-CH1-L73-CL-L74-Fc-L75-TNF1 -L76-TNF2-L77-TNF3; or VL1-L78-CL-L79-VH1-L80-CH1-L81-Fc-L82-TNF1-L83-TNF2-L84-TNF3; or VL1-L78-CH1-L79-VH1-L80-CL-L81-Fc-L82-TNF1-L83-TNF2-L84-TNF3, and the second polypeptide has the structure represented by VL2-L93-CH1-L94-VH2-L95-CL-L96-Fc.

[0105] In some embodiments, the VL1 and VH1 of the antigen-binding polypeptide complex specifically binds CD3.

[0106] In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 22, 28, 185, 298, and 306; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 23, 29, 186, 299, and 307; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 24, 30, 187, 300, and 308. and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 19, 25, 182, 294, and 302; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 20, 26, 183, 295, and 303; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 21, 27, 184, 296, and 304. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:22; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:23; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:24, and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:19; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:20; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:21.In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:28; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:29; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:30, and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:25; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:26; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:27. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 185; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 186; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 187, and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 182; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 183; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 184. As used herein, "at least 90% identity" includes at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% and 100% identity to the recited reference sequence. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO:22; a CDR2 comprising the amino acid sequence of SEQ ID NO:23; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO:24, and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO:19; a CDR2 comprising the amino acid sequence of SEQ ID NO:20; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO:21.In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 28; a CDR2 comprising the amino acid sequence of SEQ ID NO: 29; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 30, and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 25; a CDR2 comprising the amino acid sequence of SEQ ID NO: 26; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 27. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 185; a CDR2 comprising the amino acid sequence of SEQ ID NO: 186; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 187, and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 182; a CDR2 comprising the amino acid sequence of SEQ ID NO: 183; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 184. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:298; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:299; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:300, and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:294; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:295; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:296.In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:306; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:307; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:308, and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:302; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:303; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:304.

[0107] In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO: 45, and / or the VH1 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO: 43 or 44. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 45, and / or the VH1 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 43. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO: 45, and / or the VH1 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO: 43.In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 45, and / or the VH1 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 44. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO: 45, and / or the VH1 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO: 44.

[0108] In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO:297, and / or the VH1 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO:293.

[0109] In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO:305, and / or the VH1 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO:301.

[0110] In some embodiments, the VL2 and VH2 of the antigen-binding polypeptide complex specifically bind to a TAA or an immunostimulatory receptor. In some embodiments, the immunostimulatory receptor is CD28. In some embodiments, the TAA is cMet, Trop2, CD20, CD19, HER2, HER3, A2AR, APRIL, EGFR, FGFR, BAFF, BAFFR, BCMA, BTK, BTLA, B7DC, B7H1, B7H4, DLL3, ENTPD1, ​​FCER1A, FCER1, FLAP, FOLH1, MUC-1, CD133, MUC-16, LAMP1, CD38, PD-L1, CEACAM5, STEAP1, or EpCAM. In some embodiments, the TAA is HER2.

[0111] In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 34 or 40; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 35 or 41; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 36 or 42. and / or the VH2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 31 or 37; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 32 or 38; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 33 or 39. In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 34; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 35; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 36, and / or the VH2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 31; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 32; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 33.In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 40; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 41; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 42, and / or the VH2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 37; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 38; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 39. As used herein, "at least 90% identity" includes at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% and 100% identity to the recited reference sequence. In some embodiments, the VL2 of the antigen binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 34; a CDR2 comprising the amino acid sequence of SEQ ID NO: 35; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 36, and / or the VH2 of the antigen binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 31; a CDR2 comprising the amino acid sequence of SEQ ID NO: 32; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 33. In some embodiments, the VL2 of the antigen binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 40; a CDR2 comprising the amino acid sequence of SEQ ID NO: 41; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 42, and / or the VH2 of the antigen binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 37; a CDR2 comprising the amino acid sequence of SEQ ID NO: 38; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 39.

[0112] In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO: 47 or 49, and / or the VH2 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO: 46 or 48. In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 47, and / or the VH2 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 46. In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO: 47, and / or the VH2 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO:46.In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 49, and / or the VH2 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 48. In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO: 49, and / or the VH2 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO:48.

[0113] In some embodiments, the VL2 comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 314 or 322; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 315 or 323; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 316 or 324. and / or VH2 comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 310 or 318; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 311 or 319; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 312 or 320. In some embodiments, the VL2 comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:314; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:315; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:316, and / or the VH2 comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:310; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:311; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:312.In some embodiments, the VL2 comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:322; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:323; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:324, and / or the VH2 comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:318; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:319; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:320. In some embodiments, VL2 comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 313 or 321, and / or VH2 comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 309 or 317. In some embodiments, VL2 comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 313, and / or VH2 comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 309. In some embodiments, VL2 comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 321, and / or VH2 comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 317.As used herein, "at least 90% identity" includes at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% and 100% identity to the recited reference sequence.

[0114] In some embodiments, the VL2 comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:274; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:275; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:276, and / or the VH2 comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:270; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:271; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:272. In some embodiments, VL2 comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 273, and / or VH2 comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 269. As used herein, "at least 90% identity" includes at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% and 100% identity to the recited reference sequence.

[0115] In some embodiments, the VL2 comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:282; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:283; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:284, and / or the VH2 comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:278; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:279; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:280. In some embodiments, VL2 comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 281, and / or VH2 comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 277. As used herein, "at least 90% identity" includes at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% and 100% identity to the recited reference sequence.

[0116] In some embodiments, the VL2 comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:290; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:291; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:292, and / or the VH2 comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:286; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:287; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:288. In some embodiments, VL2 comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 289, and / or VH2 comprises an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 285. As used herein, "at least 90% identity" includes at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% and 100% identity to the recited reference sequence.

[0117] In some embodiments, the VL2 and VH2 of the antigen-binding polypeptide complex specifically binds CD3.

[0118] In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 22, 28, 185, 298, and 306; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 23, 29, 186, 299, and 307; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 24, 30, 187, 300, and 308. and / or the VH2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 19, 25, 182, 294, and 302; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 20, 26, 183, 295, and 303; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 21, 27, 184, 296, and 304. In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:22; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:23; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:24, and / or the VH2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:19; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:20; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:21.In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:28; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:29; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:30, and / or the VH2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:25; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:26; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:27. In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 185; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 186; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 187, and / or the VH2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 182; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 183; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 184. As used herein, "at least 90% identity" includes at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% and 100% identity to the recited reference sequence. In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO:22; a CDR2 comprising the amino acid sequence of SEQ ID NO:23; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO:24, and / or the VH2 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO:19; a CDR2 comprising the amino acid sequence of SEQ ID NO:20; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO:21.In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 28; a CDR2 comprising the amino acid sequence of SEQ ID NO: 29; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 30, and / or the VH2 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 25; a CDR2 comprising the amino acid sequence of SEQ ID NO: 26; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 27. In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 185; a CDR2 comprising the amino acid sequence of SEQ ID NO: 186; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 187, and / or the VH2 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 182; a CDR2 comprising the amino acid sequence of SEQ ID NO: 183; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 184. In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:298; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:299; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:300, and / or the VH2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:294; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:295; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:296.In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:306; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:307; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:308, and / or the VH2 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:302; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:303; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:304.

[0119] In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO: 45, and / or the VH2 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO: 43 or 44. In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 45, and / or the VH2 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 43. In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO: 45, and / or the VH2 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO:43.In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 45, and / or the VH2 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 44. In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO: 45, and / or the VH2 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO: 44. In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO:297, and / or the VH2 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO:293.In some embodiments, the VL2 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO:305, and / or the VH2 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO:301.

[0120] In some embodiments, the VL1 and VH1 of the antigen-binding polypeptide complex specifically bind to a TAA or an immunostimulatory receptor. In some embodiments, the immunostimulatory receptor is CD28. In some embodiments, the TAA is cMet, Trop2, CD20, CD19, HER2, HER3, A2AR, APRIL, EGFR, FGFR, BAFF, BAFFR, BCMA, BTK, BTLA, B7DC, B7H1, B7H4, DLL3, ENTPD1, ​​FCER1A, FCER1, FLAP, FOLH1, MUC-1, CD133, MUC-16, LAMP1, CD38, PD-L1, CEACAM5, STEAP1, or EpCAM. In some embodiments, the TAA is HER2.

[0121] In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 34 or 40; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 35 or 41; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 36 or 42. and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 31 or 37; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 32 or 38; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 33 or 39. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 34; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 35; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 36, and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 31; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 32; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 33.In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 40; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 41; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 42, and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 37; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 38; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 39. As used herein, "at least 90% identity" includes at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% and 100% identity to the recited reference sequence. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 34; a CDR2 comprising the amino acid sequence of SEQ ID NO: 35; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 36, and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 31; a CDR2 comprising the amino acid sequence of SEQ ID NO: 32; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 33. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 40; a CDR2 comprising the amino acid sequence of SEQ ID NO: 41; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 42, and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising the amino acid sequence of SEQ ID NO: 37; a CDR2 comprising the amino acid sequence of SEQ ID NO: 38; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 39.In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:274; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:275; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:276. and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:270; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:271; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:272. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:282; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:283; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:284. and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:278; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:279; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:280.In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:290; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:291; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:292. and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:286; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:287; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:288. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:314; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:315; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:316. and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:310; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:311; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:312.In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:322; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:323; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:324. and / or the VH1 of the antigen-binding polypeptide complex comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:318; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:319; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:320.

[0122] In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO: 47 or 49, and / or the VH1 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO: 46 or 48. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 47, and / or the VH1 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 46. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO: 47, and / or the VH1 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO:46.In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 49, and / or the VH1 of the antigen-binding polypeptide complex comprises an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 48. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO: 49, and / or the VH1 of the antigen-binding polypeptide complex comprises the amino acid sequence of SEQ ID NO:48. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO:273, and / or the VH1 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO:269.In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO:281, and / or the VH1 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO:277. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO:289, and / or the VH1 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO:285.In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO:313, and / or the VH1 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO:309. In some embodiments, the VL1 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO:321, and / or the VH1 of the antigen-binding polypeptide complex comprises an amino acid sequence having 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% identity to SEQ ID NO:317.

[0123] In some embodiments, the VL1 and VH1 of the antigen binding polypeptide specifically bind to CD3 and the VL2 and VH2 specifically bind to a TAA (e.g., HER2) or an immunostimulatory receptor (e.g., CD28). In some embodiments, the VL1 and VH1 of the antigen binding polypeptide specifically bind to CD3 and the VL2 and VH2 specifically bind to HER2. In some embodiments, the VL1 and VH1 of the antigen binding polypeptide specifically bind to CD3 and the VL2 and VH2 specifically bind to CD28. In some embodiments, the VL2 and VH2 of the antigen binding polypeptide specifically bind to CD3 and the VL1 and VH1 specifically bind to a TAA (e.g., HER2) or an immunostimulatory receptor (e.g., CD28). In some embodiments, the VL2 and VH2 of the antigen binding polypeptide specifically bind to CD3 and the VL1 and VH1 specifically bind to HER2. In some embodiments, the VL2 and VH2 of the antigen-binding polypeptide specifically bind to CD3, and the VL1 and VH1 specifically bind to CD28.

[0124] In some embodiments, an antigen-binding polypeptide complex of the invention comprises a first polypeptide and a second polypeptide, wherein (i) the first polypeptide is selected from the group consisting of Fc; VL1-L1-VL2-L2-VH2-L3-VH1-L4-Fc; VH1-L5-VH2-L6-VL2-L7-VL1-L8-Fc; Fc-L9-TNF1-L10-TNF2-L11-TNF3; VL1-L12-VL2-L13-VH2-L14-VH1-L15-Fc-L16-TNF1-L17-TNF2-L18-TNF3; or VH1-L19-VH2-L20-VH1-L21-VH1-L22-VH1-L23-VH1-L24-VH1-L25-VH1-L26-VH1-L27-VH1-L28-VH1-L29-VH1-L30-VH1-L31-VH1-L32-VH1-L33-VH1-L34-VH1-L35-VH1-L36-VH1-L37-VH1-L38-VH1-L39-VH1-L40-VH1-L41-VH1-L42-VH1-L43-VH1-L44-VH1-L45-VH1-L46-VH1-L47-VH1-L48-VH1-L49-VH1-L50-VH1-L51-VH1-L52-VH1-L53-VH1-L54-VH1-L55-VH1-L56-VH1-L57-VH1-L58-VH1- L2-L21-VL1-L22-Fc-L23-TNF1-L24-TNF2-L25-TNF3, and the second polypeptide has a structure represented by VL3-L26-VL4-L27-VH4-L28-VH3-L29-Fc-L30-TNF1-L31-TNF2-L32-TNF3; or VH3-L33-VH4-L34-VL4-L35-VL3-L36-Fc-L37-TNF1-L38-TNF2-L39-TNF3; or (ii) the first polypeptide has a structure represented by Fc-L40-TNF1-L41-TNF2 VH1-L42-TNF3; VL1-L43-VL2-L44-VH2-L45-VH1-L46-Fc-L47-TNF1-L48-TNF2-L49-TNF3; or VH1-L50-VH2-L51-VL2-L52-VL1-L53-Fc-L54-TNF1-L55-TNF2-L56-TNF3, and the second polypeptide has the structure represented by Fc; VL3-L57-VL4-L58-VH4-L59-VH3-L60-Fc; or VH3-L61-VH4-L62-VL4-L63-VL3-L64-Fc. wherein VL1 is a first immunoglobulin light chain variable region, VL2 is a second immunoglobulin light chain variable region, VL3 is a third immunoglobulin light chain variable region, and VL4 is a fourth immunoglobulin light chain variable region, VH1 is a first immunoglobulin heavy chain variable region, VH2 is a second immunoglobulin heavy chain variable region, VH3 is a third immunoglobulin heavy chain variable region, and VH4 is a fourth immunoglobulin heavy chain variable region, and Fc is an immunoglobulin heavy chain constant region 2 (CH2), an immunoglobulin heavy chain constant region 3 (CH3),and optionally an immunoglobulin hinge, TNF1 is a first extracellular domain of a TNFSF ligand, TNF2 is a second extracellular domain of a TNFSF ligand, TNF3 is a third extracellular domain of a TNFSF ligand, and L1-L64 are amino acid linkers. In some embodiments, the first polypeptide has a structure represented by Fc, and the second polypeptide has a structure represented by VL3-L26-VL4-L27-VH4-L28-VH3-L29-Fc-L30-TNF1-L31-TNF2-L32-TNF3. In some embodiments, the first polypeptide has a structure represented by Fc and the second polypeptide has a structure represented by VH3-L33-VH4-L34-VL4-L35-VL3-L36-Fc-L37-TNF1-L38-TNF2-L39-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L1-VL2-L2-VH2-L3-VH1-L4-Fc and the second polypeptide has a structure represented by VL3-L26-VL4-L27-VH4-L28-VH3-L29-Fc-L30-TNF1-L31-TNF2-L32-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L1-VL2-L2-VH2-L3-VH1-L4-Fc and the second polypeptide has a structure represented by VH3-L33-VH4-L34-VL4-L35-VL3-L36-Fc-L37-TNF1-L38-TNF2-L39-TNF3. In some embodiments, the first polypeptide has a structure represented by VH1-L5-VH2-L6-VL2-L7-VL1-L8-Fc and the second polypeptide has a structure represented by VL3-L26-VL4-L27-VH4-L28-VH3-L29-Fc-L30-TNF1-L31-TNF2-L32-TNF3. In some embodiments, the first polypeptide has a structure represented by VH1-L5-VH2-L6-VL2-L7-VL1-L8-Fc, and the second polypeptide has a structure represented byIn some embodiments, the first polypeptide has a structure represented by Fc-L9-TNF1-L10-TNF2-L11-TNF3, and the second polypeptide has a structure represented by VL3-L26-VL4-L27-VH4-L28-VH3-L29-Fc-L30-TNF1-L31-TNF2-L32-TNF3. In some embodiments, the first polypeptide has a structure represented by Fc-L9-TNF1-L10-TNF2-L11-TNF3 and the second polypeptide has a structure represented by VH3-L33-VH4-L34-VL4-L35-VL3-L36-Fc-L37-TNF1-L38-TNF2-L39-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L12-VL2-L13-VH2-L14-VH1-L15-Fc-L16-TNF1-L17-TNF2-L18-TNF3, and the second polypeptide has a structure represented by VL3-L26-VL4-L27-VH4-L28-VH3-L29-Fc-L30-TNF1-L31-TNF2-L32-TNF3. In some embodiments, the first polypeptide has a structure represented by VL1-L12-VL2-L13-VH2-L14-VH1-L15-Fc-L16-TNF1-L17-TNF2-L18-TNF3 and the second polypeptide has a structure represented by VH3-L33-VH4-L34-VL4-L35-VL3-L36-Fc-L37-TNF1-L38-TNF2-L39-TNF3. In some embodiments, the first polypeptide has a structure represented by VH1-L19-VH2-L20-VL2-L21-VL1-L22-Fc-L23-TNF1-L24-TNF2-L25-TNF3, and the second polypeptide has a structure represented by VL3-L26-VL4-L27-VH4-L28-VH3-L29-Fc-L30-TNF1-L31-TNF2-L32-TNF3.In some embodiments, the first polypeptide has a structure represented by Fc-L40-TNF1-L41-TNF2-L42-TNF3 and the second polypeptide has a structure represented by Fc-L40-TNF1-L41-TNF2-L42-TNF3. In some embodiments, the first polypeptide has a structure represented by Fc-L40-TNF1-L41-TNF2-L42-TNF3 and the second polypeptide has a structure represented by VL3-L57-VL4-L58-VH4-L59-VH3-L60-Fc. In some embodiments, the first polypeptide has a structure represented by Fc-L40-TNF1-L41-TNF2-L42-TNF3 and the second polypeptide has a structure represented by VH3-L61-VH4-L62-VL4-L63-VL3-L64-Fc. In some embodiments, the first polypeptide has a structure represented by VL1-L43-VL2-L44-VH2-L45-VH1-L46-Fc-L47-TNF1-L48-TNF2-L49-TNF3, and the second polypeptide has a structure represented by Fc. In some embodiments, the first polypeptide has a structure represented by VL1-L43-VL2-L44-VH2-L45-VH1-L46-Fc-L47-TNF1-L48-TNF2-L49-TNF3, and the second polypeptide has a structure represented by VL3-L57-VL4-L58-VH4-L59-VH3-L60-Fc. In some embodiments, the first polypeptide has a structure represented by VL1-L43-VL2-L44-VH2-L45-VH1-L46-Fc-L47-TNF1-L48-TNF2-L49-TNF3, and the second polypeptide has a structure represented by VH3-L61-VH4-L62-VL4-L63-VL3-L64-Fc.In some embodiments, the first polypeptide has a structure represented by VH1-L50-VH2-L51-VL2-L52-VL1-L53-Fc-L54-TNF1-L55-TNF2-L56-TNF3, and the second polypeptide has a structure represented by Fc. In some embodiments, the first polypeptide has a structure represented by VH1-L50-VH2-L51-VL2-L52-VL1-L53-Fc-L54-TNF1-L55-TNF2-L56-TNF3, and the second polypeptide has a structure represented by VL3-L57-VL4-L58-VH4-L59-VH3-L60-Fc. In some embodiments, the first polypeptide has a structure represented by VH1-L50-VH2-L51-VL2-L52-VL1-L53-Fc-L54-TNF1-L55-TNF2-L56-TNF3, and the second polypeptide has a structure represented by VH3-L61-VH4-L62-VL4-L63-VL3-L64-Fc.

[0125] In some embodiments, the VL1, VH1, VL3, and VH3 of the antigen-binding polypeptide complex specifically bind to CD3.

[0126] In some embodiments, the VL1 and VL3 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 22, 28, 185, 298, and 306; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 23, 29, 186, 299, and 307; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 24, 30, 187, 300, and 308. and / or the VH1 and VH3 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 19, 25, 182, 294, and 302; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 20, 26, 183, 295, and 303; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 21, 27, 184, 296, and 394. In some embodiments, the VL1 and VL3 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:22; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:23; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:24, and / or the VH1 and VH3 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:19; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:20; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:21.In some embodiments, the VL1 and VL3 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:28; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:29; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:30, and / or the VH1 and VH3 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:25; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:26; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:27. In some embodiments, the VL1 and VL3 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 185; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 186; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 187, and / or the VH1 and VH3 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 182; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 183; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 184. As used herein, "at least 90% identity" includes at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% and 100% identity to the recited reference sequence. In some embodiments, the VL1 and VL3 of the antigen-binding polypeptide complex comprise a CDR1 comprising the amino acid sequence of SEQ ID NO:22; a CDR2 comprising the amino acid sequence of SEQ ID NO:23; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO:24, and / or the VH1 and VH3 of the antigen-binding polypeptide complex comprise a CDR1 comprising the amino acid sequence of SEQ ID NO:19; a CDR2 comprising the amino acid sequence of SEQ ID NO:20; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO:21.In some embodiments, the VL1 and VL3 of the antigen binding polypeptide complex comprise a CDR1 comprising the amino acid sequence of SEQ ID NO: 28; a CDR2 comprising the amino acid sequence of SEQ ID NO: 29; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 30, and / or the VH1 and VH3 of the antigen binding polypeptide complex comprise a CDR1 comprising the amino acid sequence of SEQ ID NO: 25; a CDR2 comprising the amino acid sequence of SEQ ID NO: 26; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 27. In some embodiments, the VL1 and VL3 of the antigen binding polypeptide complex comprise a CDR1 comprising the amino acid sequence of SEQ ID NO: 185; a CDR2 comprising the amino acid sequence of SEQ ID NO: 186; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 187, and / or the VH1 and VH3 of the antigen binding polypeptide complex comprise a CDR1 comprising the amino acid sequence of SEQ ID NO: 182; a CDR2 comprising the amino acid sequence of SEQ ID NO: 183; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 184. In some embodiments, the VL1 and VL3 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:298; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:299; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:300, and / or the VH1 and VH3 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:294; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:295; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:296.In some embodiments, the VL1 and VL3 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:306; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:307; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:308, and / or the VH1 and VH3 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:302; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:303; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:304.

[0127] In some embodiments, the VL1 and VL3 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:45, and / or the VH1 and VH3 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:43 or 44. In some embodiments, the VL1 and VL3 of the antigen-binding polypeptide complex comprise an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 45, and / or the VH1 and VH3 of the antigen-binding polypeptide complex comprise an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 43. In some embodiments, the VL1 and VL3 of the antigen-binding polypeptide complex comprise the amino acid sequence of SEQ ID NO: 45, and / or the VH1 and VH3 of the antigen-binding polypeptide complex comprise the amino acid sequence of SEQ ID NO: 43.In some embodiments, the VL1 and VL3 of the antigen-binding polypeptide complex comprise an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 45, and / or the VH1 and VH3 of the antigen-binding polypeptide complex comprise an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 44. In some embodiments, the VL1 and VL3 of the antigen-binding polypeptide complex comprise the amino acid sequence of SEQ ID NO: 45, and / or the VH1 and VH3 of the antigen-binding polypeptide complex comprise the amino acid sequence of SEQ ID NO: 44. In some embodiments, the VL1 and VL3 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:297, and / or the VH1 and VH3 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:293.In some embodiments, the VL1 and VL3 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:305, and / or the VH1 and VH3 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:301.

[0128] In some embodiments, the VL2, VH2, VL4, and VH4 of the antigen-binding polypeptide complex specifically bind to a TAA or an immunostimulatory receptor. In some embodiments, the immunostimulatory receptor is CD28. In some embodiments, the TAA is cMet, Trop2, CD20, CD19, HER2, HER3, A2AR, APRIL, EGFR, FGFR, BAFF, BAFFR, BCMA, BTK, BTLA, B7DC, B7H1, B7H4, DLL3, ENTPD1, ​​FCER1A, FCER1, FLAP, FOLH1, MUC-1, CD133, MUC-16, LAMP1, CD38, PD-L1, CEACAM5, STEAP1, or EpCAM. In some embodiments, the TAA is HER2.

[0129] In some embodiments, the VL2 and VL4 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 34 or 40; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 35 or 41; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 36 or 42. and / or the VH2 and VH4 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 31 or 37; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 32 or 38; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 33 or 39. In some embodiments, the VL2 and VL4 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:34; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:35; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:36, and / or the VH2 and VH4 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:31; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:32; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:33.In some embodiments, the VL2 and VL4 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 40; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 41; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 42, and / or the VH2 and VH4 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 37; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 38; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 39. As used herein, "at least 90% identity" includes at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% and 100% identity to the recited reference sequence. In some embodiments, the VL2 and VL4 of the antigen binding polypeptide complex comprise a CDR1 comprising the amino acid sequence of SEQ ID NO: 34; a CDR2 comprising the amino acid sequence of SEQ ID NO: 35; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 36, and / or the VH2 and VH4 of the antigen binding polypeptide complex comprise a CDR1 comprising the amino acid sequence of SEQ ID NO: 31; a CDR2 comprising the amino acid sequence of SEQ ID NO: 32; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 33. In some embodiments, the VL2 and VL4 of the antigen binding polypeptide complex comprise a CDR1 comprising the amino acid sequence of SEQ ID NO: 40; a CDR2 comprising the amino acid sequence of SEQ ID NO: 41; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 42, and / or the VH2 and VH4 of the antigen binding polypeptide complex comprise a CDR1 comprising the amino acid sequence of SEQ ID NO: 37; a CDR2 comprising the amino acid sequence of SEQ ID NO: 38; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 39.In some embodiments, the VL2 and VL4 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:274; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:275; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:276. and / or the VH2 and VH4 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:270; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:271; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:272. In some embodiments, the VL2 and VL4 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:282; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:283; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:284. and / or the VH2 and VH4 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:278; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:279; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:280.In some embodiments, the VL2 and VL4 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:290; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:291; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:292. and / or the VH2 and VH4 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:286; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:287; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:288. In some embodiments, the VL2 and VL4 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:314; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:315; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:316. and / or the VH2 and VH4 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:310; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:311; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:312.In some embodiments, the VL2 and VL4 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:322; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:323; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:324. and / or the VH2 and VH4 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:318; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:319; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:320.

[0130] In some embodiments, the VL2 and VL4 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO: 47 or 49, and / or the VH2 and VH4 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO: 46 or 48. In some embodiments, the VL2 and VL4 of the antigen-binding polypeptide complex comprise an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 47, and / or the VH2 and VH4 of the antigen-binding polypeptide complex comprise an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 46. In some embodiments, the VL2 and VL4 of the antigen-binding polypeptide complex comprise the amino acid sequence of SEQ ID NO: 47, and / or the VH2 and VH4 of the antigen-binding polypeptide complex comprise the amino acid sequence of SEQ ID NO:46.In some embodiments, the VL2 and VL4 of the antigen-binding polypeptide complex comprise an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 49, and / or the VH2 and VH4 of the antigen-binding polypeptide complex comprise an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 48. In some embodiments, the VL2 and VL4 of the antigen-binding polypeptide complex comprise the amino acid sequence of SEQ ID NO: 49, and / or the VH2 and VH4 of the antigen-binding polypeptide complex comprise the amino acid sequence of SEQ ID NO: 48. In some embodiments, the VL2 and VL4 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:273, and / or the VH2 and VH4 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:269.In some embodiments, the VL2 and VL4 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:281, and / or the VH2 and VH4 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:277. In some embodiments, the VL2 and VL4 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:289, and / or the VH2 and VH4 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:285.In some embodiments, the VL2 and VL4 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:313, and / or the VH2 and VH4 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:309. In some embodiments, the VL2 and VL4 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:321, and / or the VH2 and VH4 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:317.

[0131] In some embodiments, the VL1, VH1, VL4, and VH4 of the antigen-binding polypeptide complex specifically bind to CD3.

[0132] In some embodiments, the VL1 and VL4 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 22, 28, 185, 298, and 306; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 23, 29, 186, 299, and 307; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 24, 30, 187, 300, and 308. and / or the VH1 and VH4 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 19, 25, 182, 294, and 302; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 20, 26, 183, 295, and 303; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 21, 27, 184, 296, and 304. In some embodiments, the VL1 and VL4 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:22; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:23; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:24, and / or the VH1 and VH4 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:19; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:20; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:21.In some embodiments, the VL1 and VL4 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:28; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:29; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:30, and / or the VH1 and VH4 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:25; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:26; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:27. In some embodiments, the VL1 and VL4 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 185; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 186; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 187, and / or the VH1 and VH4 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 182; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 183; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 184. As used herein, "at least 90% identity" includes at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% and 100% identity to the recited reference sequence. In some embodiments, the VL1 and VL4 of the antigen-binding polypeptide complex comprise a CDR1 comprising the amino acid sequence of SEQ ID NO:22; a CDR2 comprising the amino acid sequence of SEQ ID NO:23; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO:24, and / or the VH1 and VH4 of the antigen-binding polypeptide complex comprise a CDR1 comprising the amino acid sequence of SEQ ID NO:19; a CDR2 comprising the amino acid sequence of SEQ ID NO:20; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO:21.In some embodiments, the VL1 and VL4 of the antigen binding polypeptide complex comprise a CDR1 comprising the amino acid sequence of SEQ ID NO: 28; a CDR2 comprising the amino acid sequence of SEQ ID NO: 29; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 30, and / or the VH1 and VH4 of the antigen binding polypeptide complex comprise a CDR1 comprising the amino acid sequence of SEQ ID NO: 25; a CDR2 comprising the amino acid sequence of SEQ ID NO: 26; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 27. In some embodiments, the VL1 and VL4 of the antigen binding polypeptide complex comprise a CDR1 comprising the amino acid sequence of SEQ ID NO: 185; a CDR2 comprising the amino acid sequence of SEQ ID NO: 186; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 187, and / or the VH1 and VH4 of the antigen binding polypeptide complex comprise a CDR1 comprising the amino acid sequence of SEQ ID NO: 182; a CDR2 comprising the amino acid sequence of SEQ ID NO: 183; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 184. In some embodiments, the VL1 and VL4 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 298; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 299; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 300. and / or the VH1 and VH4 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs:294; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs:295; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs:296.In some embodiments, the VL1 and VL4 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 306; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 307; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 308. and / or the VH1 and VH4 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 302; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 303; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 304.

[0133] In some embodiments, the VL1 and VL4 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:45, and / or the VH1 and VH4 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:43 or 44. In some embodiments, the VL1 and VL4 of the antigen-binding polypeptide complex comprise an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 45, and / or the VH1 and VH4 of the antigen-binding polypeptide complex comprise an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 43. In some embodiments, the VL1 and VL4 of the antigen-binding polypeptide complex comprise the amino acid sequence of SEQ ID NO: 45, and / or the VH1 and VH4 of the antigen-binding polypeptide complex comprise the amino acid sequence of SEQ ID NO: 43.In some embodiments, the VL1 and VL4 of the antigen-binding polypeptide complex comprise an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 45, and / or the VH1 and VH4 of the antigen-binding polypeptide complex comprise an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 44. In some embodiments, the VL1 and VL4 of the antigen-binding polypeptide complex comprise the amino acid sequence of SEQ ID NO: 45, and / or the VH1 and VH4 of the antigen-binding polypeptide complex comprise the amino acid sequence of SEQ ID NO: 44. In some embodiments, the VL1 and VL4 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:297, and / or the VH1 and VH4 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:293.In some embodiments, the VL1 and VL4 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:305, and / or the VH1 and VH4 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:301.

[0134] In some embodiments, the VL2, VH2, VL3, and VH3 of the antigen-binding polypeptide complex specifically bind to a TAA or an immunostimulatory receptor. In some embodiments, the immunostimulatory receptor is CD28. In some embodiments, the TAA is cMet, Trop2, CD20, CD19, HER2, HER3, A2AR, APRIL, EGFR, FGFR, BAFF, BAFFR, BCMA, BTK, BTLA, B7DC, B7H1, B7H4, DLL3, ENTPD1, ​​FCER1A, FCER1, FLAP, FOLH1, MUC-1, CD133, MUC-16, LAMP1, CD38, PD-L1, CEACAM5, STEAP1, or EpCAM. In some embodiments, the TAA is HER2.

[0135] In some embodiments, the VL2 and VL3 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 34 or 40; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 35 or 41; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 36 or 42. and / or the VH2 and VH3 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 31 or 37; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 32 or 38; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 33 or 39. In some embodiments, the VL2 and VL3 of the antigen binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 34; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 35; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 36, and / or the VH2 and VH3 of the antigen binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 31; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 32; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 33.In some embodiments, the VL2 and VL3 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 40; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 41; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 42, and / or the VH2 and VH3 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 37; a CDR2 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 38; and / or a CDR3 comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 39. As used herein, "at least 90% identity" includes at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% and 100% identity to the recited reference sequence. In some embodiments, the VL2 and VL3 of the antigen binding polypeptide complex comprise a CDR1 comprising the amino acid sequence of SEQ ID NO: 34; a CDR2 comprising the amino acid sequence of SEQ ID NO: 35; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 36, and / or the VH2 and VH3 of the antigen binding polypeptide complex comprise a CDR1 comprising the amino acid sequence of SEQ ID NO: 31; a CDR2 comprising the amino acid sequence of SEQ ID NO: 32; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 33. In some embodiments, the VL2 and VL3 of the antigen binding polypeptide complex comprise a CDR1 comprising the amino acid sequence of SEQ ID NO: 40; a CDR2 comprising the amino acid sequence of SEQ ID NO: 41; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 42, and / or the VH2 and VH3 of the antigen binding polypeptide complex comprise a CDR1 comprising the amino acid sequence of SEQ ID NO: 37; a CDR2 comprising the amino acid sequence of SEQ ID NO: 38; and / or a CDR3 comprising the amino acid sequence of SEQ ID NO: 39.In some embodiments, the VL2 and VL3 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:274; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:275; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:276. and / or the VH2 and VH3 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:270; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:271; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:272. In some embodiments, the VL2 and VL3 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:282; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:283; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:284. and / or the VH2 and VH3 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:278; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:279; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:280.In some embodiments, the VL2 and VL3 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:314; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:315; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:316. and / or the VH2 and VH3 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:310; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:311; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:312. In some embodiments, the VL2 and VL3 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:322; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:323; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:324. and / or the VH2 and VH3 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:318; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:319; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO:320.

[0136] In some embodiments, the VL2 and VL3 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO: 47 or 49, and / or the VH2 and VH3 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO: 46 or 48. In some embodiments, the VL2 and VL3 of the antigen-binding polypeptide complex comprise an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 47, and / or the VH2 and VH3 of the antigen-binding polypeptide complex comprise an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 46. In some embodiments, the VL2 and VL3 of the antigen-binding polypeptide complex comprise the amino acid sequence of SEQ ID NO: 47, and / or the VH2 and VH3 of the antigen-binding polypeptide complex comprise the amino acid sequence of SEQ ID NO:46.In some embodiments, the VL2 and VL3 of the antigen-binding polypeptide complex comprise an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 49, and / or the VH2 and VH3 of the antigen-binding polypeptide complex comprise an amino acid sequence having at least 80% identity (such as 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% identity) to SEQ ID NO: 48. In some embodiments, the VL2 and VL3 of the antigen-binding polypeptide complex comprise the amino acid sequence of SEQ ID NO: 49, and / or the VH2 and VH3 of the antigen-binding polypeptide complex comprise the amino acid sequence of SEQ ID NO: 48. In some embodiments, the VL2 and VL3 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:273, and / or the VH2 and VH3 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:269.In some embodiments, the VL2 and VL3 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:281, and / or the VH2 and VH3 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:277. In some embodiments, the VL2 and VL3 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:289, and / or the VH2 and VH3 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:285.In some embodiments, the VL2 and VL3 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:313, and / or the VH2 and VH3 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:309. In some embodiments, the VL2 and VL3 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:321, and / or the VH2 and VH3 of the antigen-binding polypeptide complex comprise an amino acid sequence having 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% identity to SEQ ID NO:317.

[0137] In some embodiments, the VL2, VH2, VL4, and VH4 of the antigen-binding polypeptide complex specifically bind to CD3.

[0138] In some embodiments, the VL2 and VL4 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 22, 28, 185, 298, and 306; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 23, 29, 186, 299, and 307; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 24, 30, 187, 300, and 308. and / or the VH2 and VH4 of the antigen-binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 19, 25, 182, 294, and 302; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 20, 26, 183, 295, and 303; and / or a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 21, 27, 184, 296, and 304. In some embodiments, the VL2 and VL4 of the antigen binding polypeptide complex comprise a CDR1 comprising an amino acid sequence having at least 90% identity to SEQ ID NO:22; a CDR2 comprising an amino acid sequence having at least 90% identity t...

Claims

1. 1. An antigen-binding polypeptide complex comprising a first polypeptide and a second polypeptide, (i) the first polypeptide comprises: and the second polypeptide is or having a structure represented by or (ii) the first polypeptide comprises: and the second polypeptide is and having a structure represented by where: VL1 is a first immunoglobulin light chain variable region; VL2 is a second immunoglobulin light chain variable region, VH1 is a first immunoglobulin heavy chain variable region; VH2 is a second immunoglobulin heavy chain variable region; Fc is a region comprising immunoglobulin heavy chain constant region 2 (CH2), immunoglobulin heavy chain constant region 3 (CH3), and optionally an immunoglobulin hinge; CH1 is immunoglobulin heavy chain constant region 1; CL is an immunoglobulin light chain constant region; TNF1 is the first extracellular domain of the tumor necrosis factor superfamily (TNFSF) ligand; TNF2 is the second extracellular domain of the TNFSF ligand; TNF3 is the third extracellular domain of the TNFSF ligand; L1 to L96 are amino acid linkers; The antigen-binding polypeptide complex. (i) one or more of the linkers L1 to L96 have a length of about 0 amino acids to about 50 amino acids; (ii) one or more of the linkers L1 to L96 are non-immunogenic; (iii) one or more of the linkers L1 to L96 does not contain a consensus T-cell epitope; and / or (iv) one or more of the linkers L1 to L96 comprises an amino acid sequence of any one of SEQ ID NOs: 3 to 10 and 148 to 175, or a sequence having at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, or at least 95% identity to any one of SEQ ID NOs: 3 to 10 and 148 to 175; The antigen-binding polypeptide complex of claim 1.

3. The antigen-binding polypeptide complex of claim 1, wherein VL1 and VH1 specifically bind to CD3 and / or VL2 and VH2 specifically bind to a tumor-associated antigen (TAA) or an immunostimulatory receptor.

4. VL1 comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 22, 28, 185, 298, and 306; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 23, 29, 186, 299, and 307; and a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 24, 30, 187, 300, and 308; and VH1 comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 19, 25, 182, 294, and 302; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 20, 26, 183, 295, and 303; and a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 21, 27, 184, 296, and 304. The antigen-binding polypeptide complex of claim 3.

5. 5. The antigen-binding polypeptide complex of claim 4, wherein VL1 comprises an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 95%, or 100% identity to any one of SEQ ID NOs: 45, 297, and 305, and VH1 comprises an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 95%, or 100% identity to any one of SEQ ID NOs: 43, 44, 188, 293, and 301.

6. The TAA may be selected from the group consisting of tyrosine protein kinase Met (cMet), trophoblast cell surface antigen 2 (Trop2), CD20, CD19, receptor tyrosine protein kinase erbB-2 (HER2), receptor tyrosine protein kinase erbB-3 (HER3), adenosine A2A receptor (A2AR), proliferation-inducing ligand (APRIL), epidermal growth factor receptor (EGFR), fibroblast growth factor receptor (FGFR), B-cell activating factor (BAFF), BAFF receptor (BAFFR), B-cell maturation antigen (BCMA), Bruton's tyrosine kinase (BTK), B-lymphocyte and T-lymphocyte attenuator (BTLA), B7DC (programmed death ligand 2), B7 homolog 1 (B7H1), B7 homolog 2 (B7H2), B7 homolog 3 (B7H3), B7 homolog 4 (B7H4), B7 homolog 5 (B7H5), B7 homolog 6 (B7H6), B7 homolog 7 (B7H7), B7 homolog 8 (B7H8), B7 homolog 9 (B7H9), B7 homolog 10 (B7H9), B7 homolog 11 (B7H9), B7 homolog 12 (B7H9), B7 homolog 13 (B7H9), B7 homolog 14 (B7H9), B7 homolog 15 (B7H9), B7 homolog 16 (B7H9), B7 homolog 17 (B7H9), B7 homolog 18 (B7H9), B7 homolog 19 (B7H9), B7 homolog 20 (B7H9), B7 homolog 21 (B7H9), B7 homolog 22 (B7H9), B7 homolog 23 (B7H9), B7 homolog 24 (B7H9), B7 homolog 25 (B7H9), B7 homolog 26 (B7H9), B7 homolog 27 (B 4. The antigen-binding polypeptide complex of claim 3, wherein the polypeptide is selected from the group consisting of guanylyl nucleotide 4 (B7H4), delta-like ligand 3 (DLL3), extracellular nucleoside triphosphate diphosphohydrolase 1 (ENTPD1), Fc fragment of IgE receptor 1a (FCER1A), Fc fragment of IgE receptor 1 (FCER1), arachidonate 5-lipoxygenase-activating protein (FLAP), folate hydrolase 1 (FOLH1), mucin 1 (MUC-1), CD133, mucin 16 (MUC-16), lysosome-associated membrane protein 1 (LAMP1), CD38, programmed death-ligand 1 (PD-L1), CEA cell adhesion molecule 5 (CEACAM5), prostate six-transmembrane epithelial antigen 1 (STEAP1), and epithelial cell adhesion molecule (EpCAM).

7. 4. The antigen-binding polypeptide complex of claim 3, wherein the TAA is HER2 or the immunostimulatory receptor is CD28. Claim 8: VL2 comprises: a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 34, 40, 274, 282, 290, 314, and 322; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 35, 41, 275, 283, 291, 315, and 323; and a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 36, 42, 276, 284, 292, 316, and 324; and VH2 comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 31, 37, 270, 278, 286, 310, and 318; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 32, 38, 271, 279, 287, 311, and 319; and a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 33, 39, 272, 280, 288, 312, and 320. The antigen-binding polypeptide complex of claim 1.

9. The antigen-binding polypeptide complex of claim 8, wherein VL2 comprises an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 95%, or 100% identity to any one of SEQ ID NOs: 47, 49, 273, 281, 289, 313, and 321, and VH2 comprises an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 95%, or 100% identity to any one of SEQ ID NOs: 46, 48, 269, 277, 285, 309, and 317.

10. TNF1, TNF2, and TNF3 are selected from the group consisting of 4-1BBL (TNFSF9), OX40L (TNFSF4), TNF, TNF-related apoptosis-inducing ligand (TRAIL), CD40L (TNFSF5), CD27L (TNFSF7), CD30L (TNFSF8), FasL (TNFSF6), EDAM, LTA (TNFSF1), and LTB (TNFSF3). , CD153 (TNFSF8), RANKL (TNFSF11), TWEAK (TNFSF12), APRIL (TNFSF13), BAFF (TNFSF13B), LIGHT (TNFSF14), VEGI (TNFSF15), and GITRL (TNFSF18), respectively.

11. 11. The antigen-binding polypeptide complex of claim 10, wherein TNF1, TNF2, and TNF3 are each 4-1BBL.

12. The antigen-binding polypeptide complex of claim 1, which is an antibody or antigen-binding fragment thereof.

13. A pharmaceutical composition comprising an antigen-binding polypeptide complex according to any one of claims 1 to 12 and a pharmaceutically acceptable carrier.

14. The pharmaceutical composition of claim 13 for inducing or enhancing an immune response.

15. A pharmaceutical composition described in claim 13 for overcoming cancer-mediated immunosuppression.

16. 1. An antigen-binding polypeptide complex comprising a first polypeptide, a second polypeptide, and a third polypeptide, (a) the first polypeptide comprises: and having a structure represented by (i) the second polypeptide is and the third polypeptide is or having a structure represented by or (ii) the second polypeptide is and the third polypeptide is and having a structure represented by where: VL1 is a first immunoglobulin light chain variable region; VL2 is a second immunoglobulin light chain variable region, VH1 is a first immunoglobulin heavy chain variable region; VH2 is a second immunoglobulin heavy chain variable region; Fc is a region comprising immunoglobulin heavy chain constant region 2 (CH2), immunoglobulin heavy chain constant region 3 (CH3), and optionally an immunoglobulin hinge; CH1 is immunoglobulin heavy chain constant region 1; CL is an immunoglobulin light chain constant region; TNF1 is the first extracellular domain of the tumor necrosis factor superfamily (TNFSF) ligand; TNF2 is the second extracellular domain of the TNFSF ligand; TNF3 is the third extracellular domain of the TNFSF ligand; L1 to L27 are amino acid linkers, or, (b) the first polypeptide is and having a structure represented by (i) the second polypeptide is and the third polypeptide is or having a structure represented by or (ii) the second polypeptide is and the third polypeptide is and having a structure represented by where: VL1 is a first immunoglobulin light chain variable region; VL2 is a second immunoglobulin light chain variable region, VH1 is a first immunoglobulin heavy chain variable region; VH2 is a second immunoglobulin heavy chain variable region; Fc is a region comprising immunoglobulin heavy chain constant region 2 (CH2), immunoglobulin heavy chain constant region 3 (CH3), and optionally an immunoglobulin hinge; CH1 is immunoglobulin heavy chain constant region 1; CL is an immunoglobulin light chain constant region; TNF1 is the first extracellular domain of the tumor necrosis factor superfamily (TNFSF) ligand; TNF2 is the second extracellular domain of the TNFSF ligand; TNF3 is the third extracellular domain of the TNFSF ligand; L1 to L25 are amino acid linkers; The antigen-binding polypeptide complex.

17. 1. An antigen-binding polypeptide complex comprising a first polypeptide and a second polypeptide, (i) the first polypeptide comprises: and the second polypeptide is or having a structure represented by or (ii) the first polypeptide comprises: and the second polypeptide is and having a structure represented by where: VL1 is a first immunoglobulin light chain variable region; VL2 is a second immunoglobulin light chain variable region, VL3 is a third immunoglobulin light chain variable region, VL4 is a fourth immunoglobulin light chain variable region, VH1 is a first immunoglobulin heavy chain variable region; VH2 is a second immunoglobulin heavy chain variable region; VH3 is a third immunoglobulin heavy chain variable region; VH4 is a fourth immunoglobulin heavy chain variable region; Fc is a region comprising immunoglobulin heavy chain constant region 2 (CH2), immunoglobulin heavy chain constant region 3 (CH3), and optionally an immunoglobulin hinge; TNF1 is the first extracellular domain of the TNFSF ligand; TNF2 is the second extracellular domain of the TNFSF ligand; TNF3 is the third extracellular domain of the TNFSF ligand; L1 to L64 are amino acid linkers; The antigen-binding polypeptide complex.

18. 18. The antigen-binding polypeptide complex of any one of claims 1 to 12, 16, and 17, wherein one or more of linkers L1 to L96 comprises the amino acid sequence of any one of SEQ ID NOs: 3 to 10 and 148 to 175, or a sequence having at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, or at least 95% identity to any one of SEQ ID NOs: 3 to 10 and 148 to 175.

19. 18. The antigen-binding polypeptide complex of claim 16 or 17, wherein VL1 and VH1 specifically bind to CD3.

20. VL1 comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 22, 28, 185, 298, and 306; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 23, 29, 186, 299, and 307; and a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 24, 30, 187, 300, and 308; and VH1 comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 19, 25, 182, 294, and 302; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 20, 26, 183, 295, and 303; and a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 21, 27, 184, 296, and 304.

20. The antigen-binding polypeptide complex of claim 19.

21. 21. The antigen-binding polypeptide complex of claim 20, wherein VL1 comprises an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 95%, or 100% identity to SEQ ID NO: 45, and VH1 comprises an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 95%, or 100% identity to SEQ ID NO: 43 or 44.

22. 18. The antigen-binding polypeptide complex of claim 16 or 17, wherein VL2 and VH2 specifically bind to a tumor-associated antigen (TAA) or an immunostimulatory receptor.

23. The tumor-associated antigen is selected from the group consisting of tyrosine protein kinase Met (cMet), trophoblast cell surface antigen 2 (Trop2), CD20, CD19, receptor tyrosine protein kinase erbB-2 (HER2), receptor tyrosine protein kinase erbB-3 (HER3), adenosine A2A receptor (A2AR), proliferation-inducing ligand (APRIL), epidermal growth factor receptor (EGFR), fibroblast growth factor receptor (FGFR), B-cell activating factor (BAFF), BAFF receptor (BAFFR), B-cell maturation antigen (BCMA), Bruton's tyrosine kinase (BTK), B-lymphocyte and T-lymphocyte attenuator (BTLA), B7DC (programmed death ligand 2), B7 homolog 1 (B7H1), B7 homolog 2 (B7H2), B7H3 (B7H4), B7H5 (B7H6), B7H7 (B7H8), B7H9 (B7H9), B7H1 (B7H1), B7H2 (B7H1), B7H1 (B7H1), B7H2 (B7H1), B7H3 (B7H4), B7H5 (B7H5), B7H6 (B7H6), B7H7 (B7H7), B7H8 (B7H9), B7H9 (B7H1), B7H1 (B7H1), B7H1 (B7H1), B7H1 (B7H1), B7H2 (B7H1), B7H1 (B7H1), B7H1 (B7H1), B7H2 (B7H1), B7H3 (B7H1), B7H4 (B7H1), B7H5 (B7H1), B7H6 (B7H1), B7H6 (B7H1), B7H7 (B7H1), B7H7 (B7H1), B7H8 (B 23. The antigen-binding polypeptide complex of claim 22, which is Log 4 (B7H4), delta-like ligand 3 (DLL3), extracellular nucleoside triphosphate diphosphohydrolase 1 (ENTPD1), Fc fragment of IgE receptor 1a (FCER1A), Fc fragment of IgE receptor 1 (FCER1), arachidonate 5-lipoxygenase-activating protein (FLAP), folate hydrolase 1 (FOLH1), mucin 1 (MUC-1), CD133, mucin 16 (MUC-16), lysosome-associated membrane protein 1 (LAMP1), CD38, programmed death-ligand 1 (PD-L1), CEA cell adhesion molecule 5 (CEACAM5), prostate six-transmembrane epithelial antigen 1 (STEAP1), or epithelial cell adhesion molecule (EpCAM).

24. 23. The antigen-binding polypeptide complex of claim 22, wherein the TAA is HER2 or the immunostimulatory receptor is CD28.

25. VL2 comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 34, 40, 274, 282, 290, 314, or 322; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 35, 41, 275, 283, 291, 315, or 323; and a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 36, 42, 276, 284, 292, 316, or 324; and VH2 comprises a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 31, 37, 270, 278, 286, 310, or 318; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 32, 38, 271, 279, 287, 311, or 319; and a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 33, 39, 272, 280, 288, 312, or 320.

18. An antigen-binding polypeptide complex according to claim 16 or 17.

26. 26. The antigen-binding polypeptide complex of claim 25, wherein VL2 comprises an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 95%, or 100% identity to SEQ ID NO: 47, 49, 273, 281, 289, 313, or 321, and VH2 comprises an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 95%, or 100% identity to SEQ ID NO: 46, 48, 269, 277, 285, 309, or 317.

27. 17. The antigen-binding polypeptide complex of claim 16, wherein VL2 and VH2 specifically bind to CD3.

28. 28. The antigen-binding polypeptide complex of claim 27, wherein VL1 and VH1 specifically bind to a TAA or an immunostimulatory receptor.

29. 29. The antigen-binding polypeptide complex of claim 28, wherein the TAA is HER2 or the immunostimulatory receptor is CD28.

30. 18. The antigen-binding polypeptide complex of claim 17, wherein VL1, VH1, VL3, and VH3 specifically bind to CD3.

31. 31. The antigen-binding polypeptide complex of claim 17 or 30, wherein VL2, VH2, VL4, and VH4 specifically bind to a TAA or an immunostimulatory receptor.

32. 32. The antigen-binding polypeptide complex of claim 31, wherein the TAA is HER2 or the immunostimulatory receptor is CD28.

33. 18. The antigen-binding polypeptide complex of claim 17, wherein VL1, VH1, VL4, and VH4 specifically bind to CD3.

34. 34. The antigen-binding polypeptide complex of claim 17 or 33, wherein VL2, VH2, VL3, and VH3 specifically bind to a TAA or immunostimulatory receptor.

35. 35. The antigen-binding polypeptide complex of claim 34, wherein the TAA is HER2 or the immunostimulatory receptor is CD28.

36. 18. The antigen-binding polypeptide complex of claim 17, wherein VL2, VH2, VL4, and VH4 specifically bind to CD3.

37. 37. The antigen-binding polypeptide complex of claim 17 or 36, wherein VL1, VH1, VL3, and VH3 specifically bind to a TAA or immunostimulatory receptor.

38. 38. The antigen-binding polypeptide complex of claim 37, wherein the TAA is HER2 or the immunostimulatory receptor is CD28.

39. 18. The antigen-binding polypeptide complex of claim 17, wherein VL2, VH2, VL3, and VH3 specifically bind to CD3.

40. 40. The antigen-binding polypeptide complex of claim 17 or 39, wherein VL1, VH1, VL4, and VH4 specifically bind to a TAA or immunostimulatory receptor.

41. 41. The antigen-binding polypeptide complex of claim 40, wherein the TAA is HER2 or the immunostimulatory receptor is CD28.

42. the VL that specifically binds to CD3 comprises: a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 22, 28, 185, 298, and 306; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 23, 29, 186, 299, and 307; and a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 24, 30, 187, 300, and 308; and the VH that specifically binds to CD3 comprises: a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 19, 25, 182, 294, and 302; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 20, 26, 183, 295, and 303; and a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to any one of SEQ ID NOs: 21, 27, 184, 296, and 304.

31. The antigen-binding polypeptide complex of claim 30.

43. 43. The antigen-binding polypeptide complex of claim 42, wherein the VL that specifically binds to CD3 comprises an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 95%, or 100% identity to SEQ ID NO: 45, 297, or 305, and the VH that specifically binds to CD3 comprises an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 95%, or 100% identity to SEQ ID NO: 43, 44, 188, 293, or 301.

44. the VL that specifically binds to a TAA or immunostimulatory receptor comprises: a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 34, 40, 274, 282, 290, 314, or 322; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 35, 41, 275, 283, 291, 315, or 323; and a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 36, 42, 276, 284, 292, 316, or 324; and The VH that specifically binds to a TAA or immunostimulatory receptor comprises: a CDR1 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 31, 37, 270, 278, 286, 310, or 318; a CDR2 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 32, 38, 271, 279, 287, 311, or 319; and a CDR3 comprising an amino acid sequence having at least 90% identity, at least 95% identity, or 100% identity to SEQ ID NO: 33, 39, 272, 280, 288, 312, or 320.

32. The antigen-binding polypeptide complex of claim 31.

45. The antigen-binding polypeptide complex of claim 44, wherein the VL that specifically binds to a TAA or immunostimulatory receptor comprises an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 95%, or 100% identity to SEQ ID NO: 47, 49, 273, 281, 289, 313, or 321, and the VH that specifically binds to a TAA or immunostimulatory receptor comprises an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 95%, or 100% identity to SEQ ID NO: 46, 48, 269, 277, 285, 309, or 317.

46. TNF1, TNF2, and TNF3 are expressed in the OX40L (TNFSF4), 4-1BBL (TNFSF9), TNF, TNF-related apoptosis-inducing ligand (TRAIL), CD40L (TNFSF5), CD27L (TNFSF7), CD30L (TNFSF8), FasL (TNFSF6), EDAM, LTA (TNFSF1), LTB (TNFSF3), and CD 18. The antigen-binding polypeptide complex of claim 16 or 17, wherein each of the polypeptides is selected from the group consisting of: 153 (TNFSF8), RANKL (TNFSF11), TWEAK (TNFSF12), APRIL (TNFSF13), BAFF (TNFSF13B), LIGHT (TNFSF14), VEGI (TNFSF15), and GITRL (TNFSF18).

47. 18. The antigen-binding polypeptide complex of claim 16 or 17, which is an antibody or an antigen-binding fragment thereof.

48. 18. A pharmaceutical composition comprising an antigen-binding polypeptide complex according to claim 16 or 17 and a pharmaceutically acceptable carrier.

49. The pharmaceutical composition of claim 48 for inducing or enhancing an immune response.

50. A pharmaceutical composition described in claim 48 for overcoming cancer-mediated immunosuppression.

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