Anti-CD3 antibodies and uses thereof

Abstract

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Description

CROSS-REFERENCE TO RELATED APPLICATIONS 5         This application is a divisional application of Australian Patent Application No. 2019274656, filed on 21 May 2019, and is related to International Patent Application No. PCT / IB2019 / 054188, filed on 21 May 2019, and claims priority to Provisional Patent Application No. 62 / 676081, filed on 24 May 2018, the disclosure of each of which is incorporated herein by reference in their entirety. 10 SEQUENCE LISTING Preceding applications contained a Sequence Listing which was originally submitted electronically in ASCII format and is hereby incorporated by reference in its entirety. Said 15 ASCII copy, created on 3 May 2019 is named JBI5135USNP_Sequence_listing.txt and is 588 KB in size. The present application contains a sequence listing which has been submitted electronically as an XML document in the ST.26 format and is hereby incorporated by reference in its entirety. Said XML copy, created on 16 June 2026, is named 206389-0062-01AU_SequenceListing, and is 623KB in size. 20 TECHNICAL FIELD The disclosure provided herein relates to anti-cluster of differentiation 3 (CD3)-antibodies, and antigen-binding fragments thereof, capable of specifically binding to human and 25 non-human CD3, and in particular to anti-CD3 antibodies and antigen-binding fragments that are cross-reactive with CD3 of a non-human mammal (e.g., a cynomolgus monkey); prostate specific membrane antigen (PSMA)-antibodies, and antigen-binding fragments thereof, capable of specifically binding to human and non-human PSMA; IL1RAP antibodies, and antigenbinding fragments thereof, capable of specifically binding to human and non-human IL1RAP; 30 CD33 antibodies, and antigen-binding fragments thereof, capable of specifically binding to human and non-human CD33; and bispecific antibodies that are capable of specifically binding 2026204725   18 Jun 2026 CD3; PSMA; IL1RAP; CD33; CD3 and PSMA; CD3 and IL1RAP; or CD3 and CD33. The disclosure also pertains to uses of such antibodies and antigen-binding fragments in the treatment of cancer, autoimmune and / or inflammatory diseases and other conditions. 5 BACKGROUND Bispecific antibodies and antibody fragments have been explored as a means to recruit cytolytic T cells to kill tumor cells. However, the clinical use of many T cell-recruiting bispecific antibodies has been limited by challenges including unfavorable pharmacokinetics, potential 10 immunogenicity, and manufacturing issues. There thus exists a considerable need for bispecific antibodies that recruit cytolytic T cells to kill tumor cells that exhibit reduced toxicity and favorable manufacturing profiles. The human CD3 T cell antigen receptor protein complex is composed of six distinct chains: a CD3y chain (SwissProt P09693), a CD38 chain (SwissProt P04234), two CD3s chains 15 [TEXT CONTINUES ON PAGE 2] 2026204725   18 Jun 2026 (SwissProt P07766), and one CD3Z chain homodimer (SwissProt P20963) (s y: s 8:ZZ), which is associated with the T cell receptor a and p chain. This complex plays an important role in coupling antigen recognition to several intracellular signal-transduction pathways. The CD3 complex mediates signal transduction, resulting in T cell activation and proliferation. CD3 is 5 required for immune response. SUMMARY Provided herein are isolated recombinant anti-CD3 antibodies, or antigen-binding fragments thereof, comprising: a heavy chain comprising a heavy chain complementarity determining region (HCDR) 1 comprising SEQ ID NO: 662; a HCDR2 comprising SEQ ID NO: 10 663; and a HCDR3 comprising SEQ ID NO: 664 and a light chain comprising a light chain complementarity determining region (LCDR) 1 comprising SEQ ID NO: 671, a LCDR2 comprising SEQ ID NO: 673, and a LCDR3 comprising SEQ ID NO: 690; a heavy chain variable region comprising SEQ ID NO: 652 and a light chain variable region comprising SEQ ID NO: 661; a heavy chain comprising SEQ ID NO: 640 and a light chain comprising SEQ ID 15 NO: 676; or comprising: a heavy chain comprising a HCDR1 comprising SEQ ID NO: 662; a HCDR2 comprising SEQ ID NO: 663; and a HCDR3 comprising SEQ ID NO: 664 and a light chain comprising a LCDR1 comprising SEQ ID NO: 773, a LCDR2 comprising SEQ ID NO: 673, and a LCDR3 comprising SEQ ID NO: 690; a heavy chain variable region comprising SEQ ID NO: 657 and a light chain variable region comprising SEQ ID NO: 678; or a heavy chain 20 comprising SEQ ID NO: 675 and a light chain comprising SEQ ID NO: 678. Also provided are isolated recombinant anti-CD3 antibodies or antigen-binding fragments thereof, that specifically bind Macaca fascicularis or human CD3d, or CD3e, or CD3e and CD3d with a binding affinity of about 300 nM or less. In some embodiments, the isolated recombinant anti-CD3 antibodies or antigen-binding 25 fragments thereof have one, two, three, or four, of the following properties: • bind human and Macaca fascicularis CD3+ T lymphocytes with a calculated EC50 of 20 nM or less and bind Macaca fascicularis CD3-expressing HEK cells with a calculated EC50 of 40 nM or less, wherein the difference in calculated EC50 between binding CD3+ T lymphocytes and binding Macaca fascicularis CD3- 2026204725   18 Jun 2026 expressing HEK cells is less than 5-fold, and wherein the calculated EC50 is measured in a whole cell binding assay at 0 °C using flow cytometry; • bind recombinant CD3d from human (SEQ ID NO:691), or bind recombinant CD3e from human (SEQ ID NO:636), or recombinant CD3d from Macaca fascicularis 5 (SEQ ID NO:692), with an equilibrium dissociation constant (KD) of 12 nM or less, wherein the KD is measured using Proteon surface plasmon resonance assay ProteOn XPR36 system at +25°C; • bind residues 1-6 of CD3e as determined by X-ray crystallography; or • activate T cells or induces CD69 expression to a similar degree as cOKT3 or SP34-10                2 as determined by fluorescence-activated cell sorting assay. In some embodiments, the antibodies or antigen-binding fragments thereof described herein comprise the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID NOs:662, 663, 664, 671, 673, and 690, respectively; a VH and a VL of SEQ ID NOs:652 and 661, respectively; or a HC and a LC of SEQ ID NOs:640 and 676, respectively. 15 In some embodiments, the antibodes or antigen-binding fragments thereof described herein comprise the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID NOs:662, 663, 664, 773, 673, and 690, respectively; a VH and a VL of SEQ ID NOs:657 and 678, respectively or a HC and a LC of SEQ ID NOs:675 and 677, respectively. Further described herein are bispecific antibodies comprising a first domain that 20 specifically binds CD3 and a second domain that specifically binds a second antigen, wherein the first domain comprises an antibody or antigen-binding fragment thereof described herein. The bispecific antibodies described herein can comprise a first domain that comprises the HCDR1, HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID NOs:662, 663, 664, 671, 673, and 670, respectively; and a second domain that comprises the the HCDR1, 25 HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID NOs:697, 683, 698, 699, 792, and 686, respectively; The bispecific antibodies described herein can comprise a first domain that comprises the VH and VL of SEQ ID NOs:652 and 661, respectively; and a second domain that comprises the VH and VL of SEQ ID NOs:681 and 682, respectively. 2026204725   18 Jun 2026 The bispecific antibodies described herein can comprise a first domain that comprises the HC and LC of SEQ ID NOs:640 and 676, respectively; and a second domain that comprises the HC and LC of SEQ ID NOs:679 and 680, respectively. The bispecific antibodies described herein can comprise a first domain that comprises the 5 HCDR1, HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID NOs:662, 663, 664, 671, 673, and 670, respectively; and a second domain that comprises the the HCDR1, HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID NOs:704, 705, 706, 707, 708, and 709, respectively. The bispecific antibodies described herein can comprise a first domain that comprises the 10 VH and VL of SEQ ID NOs:652 and 661, respectively; and a second domain that comprises the VH and VL of SEQ ID NOs:702 and 703, respectively. The bispecific antibodies described herein can comprise a first domain that comprises the HC and LC of SEQ ID NOs:640 and 676, respectively; and a second domain that comprises the HC and LC of SEQ ID NOs:700 and 701, respectively. 15 The disclosure further provides isolated bispecific CD3*PSMA antibodies comprising a first domain that binds to cells expressing recombinant Macaca fascicularis or human CD3d or CD3e with an affinity of 300 nM or less, wherein the binding to cells is measured by flow cytometry, and a second domain that specifically bind PSMA. In some embodiments, the bispecific CD3*PSMA antibody comprises a first domain 20 that: • binds human and Macaca fascicularis CD3+ T lymphocytes with a calculated EC50 of 20 nM or less and binds Macaca fascicularis CD3-expressing HEK cells with a calculated EC50 of 40 nM or less, wherein the difference in calculated EC50 between binding CD3+ T lymphocytes and binding Macaca fascicularis CD3-25 expressing HEK cells is less than 5-fold, and wherein the calculated EC50 is measured in a whole cell binding assay at 0 °C using flow cytometry; • binds recombinant CD3d from human (SEQ ID NO:691), or binds recombinant CD3e from human (SEQ ID NO:636), or binds recombinant CD3d from Macaca fascicularis (SEQ ID NO:692), or binds recombinant CD3e from Macaca 30 fascicularis (SEQ ID NO:693) with an equilibrium dissociation constant (KD) of 2026204725   18 Jun 2026 12 nM or less, wherein the KD is measured using Proteon surface plasmon resonance assay ProteOn XPR36 system at +25°C; • displays no methionine or tryptophan oxidation, or displays no asparagine deamidation, or displays no asparagine isomerization as detected by peptide 5 mapping analysis; • binds residues 1-6 of CD3e as determined by X-ray crystallography; or • activates T cells or induces CD69 expression to a similar degree as cOKT3 or SP34-2 as determined by fluorescence-activated cell sorting assay. Also described are pharmaceutical compositions comprising the antibodies described 10 herein and a pharmaceutically acceptable carrier. The disclosure further provides methods of producing the antibodies described herein, comprising culturing a host cell comprising a vector comprising a polynuceotide encoding the antibodies or antigen-binding fragments thereof described herein in conditions that the antibody is expressed, and recovering the antibody produced by the host cell. The methods of producing 15 the bispecific CD3*PSMA antibody can comprise combining a monospecific bivalent CD3 antibody having two identical HC1 and two identical LC1 and a monospecific bivalent PSMA antibody having two identical HC2 and two identical LC2 in a mixture of about 1:1 molar ratio; introducing a reducing agent into the mixture; incubating the mixture about ninety minutes to about six hours; removing the reducing agent; and purifying the bispecific CD3*PSMA antibody 20 that comprises the HC1, the LC1, the HC2 and the LC2. Further described are methods of treating a cancer in a subject, comprising administering a therapeutically effective amount of the isolated antibodies described to the subject in need thereof for a time sufficient to treat the cancer. The disclosure also provides kits comprising the antibodies described herein. The kits 25 can further comprise reagents for detecting the antibodies and instructions of use. BRIEF DESCRIPTIONS OF THE DRAWINGS The summary, as well as the following detailed description, is further understood when read in conjunction with the appended drawings. For the purpose of illustrating the disclosed antibodies and methods, there are shown in the drawings exemplary embodiments of the 2026204725   18 Jun 2026 antibodies and methods; however, antibodies and methods are not limited to the specific embodiments disclosed. In the drawings: Figs. 1A and 1B show anti-CD3 antibodies produced in OmniRat. VH (Fig. 1A) and VL (Fig. 1B) sequences of active anti-CD3 mAbs produced in OmniRat were aligned with human 5 germline sequences from IMGT. CDR regions are underlined. Sequence divergence is shown in bold. Fig. 1A discloses SEQ ID NOS 651, 651, 653, 656, 655, 20, 654 and 717 and Fig. 1B discloses SEQ ID NOS 658, 688, 660, 659, 659, 659, 659 and 718, all respectively, in order of appearance. Fig. 2 shows a cell-based binding assay to assess the binding capacity of individual rat 10 hybridoma supernatants to human purified CD3+ T lymphocytes. Fig. 3 shows a cell-based binding assay to assess the binding capacity of individual rat hybridoma supernatants to cynomolgus purified CD3+ T lymphocytes. Fig. 4 shows competition assay results of hybridoma supernatants assessed for their ability to compete with commercial anti-human CD3 antibody SP34-2, which has a known 15 epitope and is cross-reactive with cynomolgus CD3. Fig. 5 shows representative binding curves of anti-CD3 antibodies on primary human T cells. Fig. 6 shows representative competition binding curves of anti-CD3 antibodies with AlexaFluor 488 conjugated SP34-2 on primary human T cells. 20        Fig. 7 shows binding of light chain (LC) engineered BLW-2E6 mAbs to primary human T cells. Fig. 8 shows binding of heavy chain (HC) engineered BLW-2E6 to primary human T cells. Fig. 9 shows AlexaFluor™ (AF) 488 CD3 Saturation in Human T Cells by FACS 25 analysis. Acquired mean fluorescence intensity values were plotted as a function of the antibody molecule concentration. Kd values were derived for each donor, and the mean value obtained. The Saturation Binding Constant (KdT) for human T-Cells was derived to be 5.6 ± 1.0 nM (n=4) and was used herein to determine Kd binding affinities. One human donor was excluded as it failed the viability criteria of being at least 60% during analysis. “LS” identifiers in figure 30 legend refer to individual human T cell donors. 2026204725   18 Jun 2026 Fig. 10 shows inhibition curves for the bivalent anti CD3 antibodies, CD3B376 and CD3B450, for competing for binding against the AlexaFluor488 SP-34 anti CD3 antibody. IC50 values were derived to be 29 and 60 nM respectively. Fig. 11 shows sensorgrams of BLW-2E6 variants binding to hCD3s(1-27)-Tn25. 5 Figs. 12A-12E shows thermal stability of anti-CD3 antibodies CD3B376 (Fig. 12A), CD3B450 (Fig. 12B), CD3B389 (Fig. 12C), CD3B467 by DSC (Fig. 12D), and overlay of the thermograms for all the candidates (Fig. 12E). Figs. 13A-13B show comparisons of the thermal stability of anti-CD3 antibodies overlay of thermograms for CD3B376 and CD3B389 (Fig. 13A); overlay of thermograms for CD3B450 10 and CD3B467 (Fig. 13B). Fig. 14 shows LNCAP cell binding of a subset of affinity-matured PSMA*CD3 bispecific antibodies. Fig. 15 shows LNCAP cell binding of a subset of affinity-matured PSMA*CD3 bispecific antibodies. 15 Fig. 16 shows PSMA-negative PC3 cell binding results of affinity-matured PSMA*CD3 bispecific antibodies. Fig. 17 shows results of PSMA*CD3 Affinity Matured Bispecific Abs in a Functional Cell Killing Assay. Fig. 18 shows antibody-antigen interactions in the CD3B334:CD3 complex. CD3 20 residues are in ellipses, CD3B334 residues are in boxes. Fig. 19 shows a primary human and cynomolgus monkey T cell based assay used to determine the capacity of the hybridoma hits to activate T cells as measured by CD69 activation. Fig. 20 shows anti-tumor efficacy of PS3B79 in LnCAP AR.TB human prostate xenografts in T cell humanized NSG mice. Subcutaneous LnCAP AR.TB tumors were measured 25 twice weekly and the results presented as the mean tumor volume, expressed in mm3 ± SEM (*, p<0.0001). Fig. 21 shows anti-tumor efficacy of PS3B90 in LnCAP AR.TB human prostate xenografts in T cell humanized NSG mice. Subcutaneous LnCAP AR.TB tumors were measured twice weekly and the results presented as the mean tumor volume, expressed in mm3 ± SEM (*, 30 p<0.001). 2026204725   18 Jun 2026 Figs. 22A-22D show titration curves for Anti-PSMA phage panning hits binding to human LNCaP cells. Fig. 22A shows titration curves for hits G9-PSM M18, M25, M50, M52, M56, M57, and M59; Fig. 22B shows M52 and M110; Fig. 22C shows M85, M87, and M81; and Fig. 22D shows M52 and M84. In Fig. 22D, Mammalian-expressed supernatants were 5 normalized for Fab expression via octet, and titrated against either human LNCAP, PSMG5 (Cyno-PSMA HEK), or PSMG9 (chimp-PSMA HEK) cells using flowcytometry. Geometric mean fluorescence intensity (GeoMFI) was ploted vs. Fab concertation using GraphPad Prizm. Figs. 23A-23D show titration curves for Anti-PSMA phage panning hits binding to Chimpanzee-PSMA expressing HEK cells shows. (Mammalian Fab Supernatant Titration Curves 10 for Anti-PSMA Phage Panning Hits vs Chimp-PSMA HEK). Fig. 23A shows titration curves for hits G9-PSM M18, M25, M50, M52, M56, M57, and M59; Fig. 23B shows M52 and M110; Fig. 23C shows M81, M52, M85, and M87; and Fig. 23D shows M52 and M84. In Fig. 23D, Mammalian-expressed supernatants were normalized for Fab expression via octet, and titrated against either human LNCAP, PSMG5 (Cyno-PSMA HEK), or PSMG9 (chimp-PSMA HEK) 15 cells using flowcytometry. Geometric mean fluorescence intensity (GeoMFI) was ploted vs. Fab concertation using GraphPad Prizm. Figs. 24A-24D show titration curves for Anti-PSMA phage panning hits binding to Cynomolgus monkey PSMA-expressing HEK cells. (Mammalian Fab Supernatant Titration Curves for Anti-PSMA Phage Panning Hits vs Cyno PSMA HEK). Fig. 24A shows titration 20 curves for hits G9-PSM M18, M25, M50, M52, M56, M57, and M59; Fig. 24B shows M52 and M110; Fig. 24C shows M81, M52, M85, and M87; and Fig. 24D shows M52 and M84. In Fig. 24D, Mammalian-expressed supernatants were normalized for Fab expression via octet, and titrated against either human LNCAP, PSMG5 (Cyno-PSMA HEK), or PSMG9 (chimp-PSMA HEK) cells using flow cytometry. Geometric mean fluorescence intensity (GeoMFI) was ploted 25 vs. Fab concertation using GraphPad Prizm. Fig. 25 shows the overall structure of PSMM84 Fab bound to human PSMA ECD homodimer. Fig. 26 shows a close view of PSMA main interactions with the PSMB83 Light Chain. Fig. 27 shows a close view of PSMA main interactions with the PSMB83 Heavy Chain. 2026204725   18 Jun 2026 Fig. 28 shows the comparison of epitope residues of PSMB83 within the sequences of human (SEQ ID NO: 719), mouse (SEQ ID NO: 720) and cynomolgus monkey (cyno) (SEQ ID NO: 721) PSMA. Epitope residues are shaded and sequence divergence is shown by underline. Fig. 29 shows the paratope residues of PSMB83. CDRs are underlined and paratope 5 residues are shaded. Fig. 30 discloses SEQ ID NOS 722-727, respectively, in order of appearance. Fig. 30 shows an interaction map with direct contacts made between PSMA and PSMM84. Van der Waals interactions are shown as dashed lines and H-bonds are solid lines with arrows pointing to the backbone atoms. 10 Fig. 31 shows expression levels of anti-PSMA Fab clones derived from PSMM84 as compared to expression of parent PSMB83. Raw luminescence numbers were plotted against the log concentration Fig. 32 shows binding to human PSMA of anti-PSMA Fab clones derived from PSMB83 as compared to binding of parent PSMM84. Raw luminescence numbers were plotted against 15 the log concentration. Fig. 33 shows binding to cyno PSMA of anti-PSMA Fab clones derived from PSMB83 as compared to binding of parent PSMB83. Raw luminescence numbers were plotted against the log concentration. Fig. 34 shows IC3B19 and IC3B34 Ex Vivo Mediated T cell Cytotoxicity of LAMA-84 20 cells in Whole Blood after 48 hours. The concentration of IC3B19 and IC3B34 is provided in the table in the lower part of the figure. Fig. 35 shows IC3B19 and IC3B34 Ex Vivo Mediated T-cell Activation in Whole Blood after 48 hours. The concentration of IC3B19 and IC3B34 is provided in the table in the lower part of the figure. 25 Figs. 36-55 show IC3B19 and IC3B34 mediated engagement of T cells and IL1RAP+ target cell line LAMA-84 (endogenous and exogenously added tumor cells). Supernatants were evaluated for 10 pro-inflammatory cytokines from whole blood (n=15 donors) cytotoxicity and T-cell activation assays with exogenous LAMA-84 IL1RAP+ tumor cell line added. For these figures, statistically significant differences are shown in bold text. 30 Figs. 36A-36B show T cell IL-1beta release mediated by IC3B19 and IC3B34 (Fig. 37A) and corresponding 4PL regression parameter estimates (Fig. 37B) after 24 hours. 2026204725   18 Jun 2026 Figs. 37A-37B show T cell IL-1beta release mediated by IC3B19 and IC3B34 (Fig. 38A) and corresponding 4PL regression parameter estimates (Fig. 38B) after 48 hours. Figs. 38A-38B show T cell IL-2 release mediated by IC3B19 and IC3B34 (Fig. 39A) and corresponding 4PL regression parameter estimates (Fig. 39B) after 24 hours. 5 Figs. 39A-39B show T cell IL-2 release mediated by IC3B19 and IC3B34 (Fig. 40A) and corresponding 4PL regression parameter estimates (Fig. 40B) after 48 hours. Figs. 40A-40B show T cell IL-4 release mediated by IC3B19 and IC3B34 (Fig. 41A) and corresponding 4PL regression parameter estimates (Fig. 41B) after 24 hours. Fig. 41 shows T cell IL-4 release mediated by IC3B19 and IC3B34 after 48 hours. 10 Figs. 42A-42B show T cell IL-6 release mediated by IC3B19 and IC3B34 (Fig. 43A) and corresponding 4PL regression parameter estimates (Fig. 43B) after 24 hours. Fig. 43 shows T cell IL-6 release mediated by IC3B19 and IC3B34 after 48 hours. Fig. 44 shows T cell IL-8 release mediated by IC3B19 and IC3B34 after 24 hours. Fig. 45 shows T cell IL-8 release mediated by IC3B19 and IC3B34 after 48 hours. 15 Figs. 46A-46B show T cell IL-10 release mediated by IC3B19 and IC3B34 (Fig. 47A) and corresponding 4PL regression parameter estimates (Fig. 47B) after 24 hours. Figs. 47A-47B show T cell IL-10 release mediated by IC3B19 and IC3B34 (Fig. 48A) and corresponding 4PL regression parameter estimates (Fig. 48B) after 48 hours. Fig. 48 shows T cell IL-12p70 release mediated by IC3B19 and IC3B34 after 24 hours. 20 Fig. 49 shows T cell IL-12p70 release mediated by IC3B19 and IC3B34 after 48 hours. Fig. 50 shows T cell IL-13 release mediated by IC3B19 and IC3B34 after 24 hours. Figs. 51A-51B show T cell IL-13 release mediated by IC3B19 and IC3B34 (Fig. 52A) and corresponding 4PL regression parameter estimates (Fig. 52B) after 48 hours. Figs. 52A-52B show T cell IFN-gamma release mediated by IC3B19 and IC3B34 (Fig. 25 53A) and corresponding 4PL regression parameter estimates (Fig. 53B) after 24 hours. Figs. 53A-53B show T cell IFN-gamma release mediated by IC3B19 and IC3B34 (Fig. 54A) and corresponding 4PL regression parameter estimates (Fig. 54B) after 48 hours. Figs. 54A-54B show T cell TNF-alpha release mediated by IC3B19 and IC3B34 (Fig. 55A) and corresponding 4PL regression parameter estimates (Fig. 55B) after 24 hours. 30 Figs. 55A-55B show T cell TNF-alpha release mediated by IC3B19 and IC3B34 (Fig. 56A) and corresponding 4PL regression parameter estimates (Fig. 56BB) after 48 hours. 2026204725   18 Jun 2026 Fig. 56 shows IC3B19 and IC3B34, but not the bispecific antibodies with null arms (IAPB57*B23B49 or B23B39*CD3B219), induced target specific cytotoxicity in NCI-H1975 cells. In this assay, the cytotoxicity EC50s vary three-fold between IC3B19 and IC3B34, with values of 0.018 and 0.057 nM, respectively. 5 Fig. 57 shows Anti-Tumor Efficacy of IAPB57*CD3B376 in H1975 Human NSCLC Xenografts in T cell Humanized NSG Mice. Subcutaneous H1975 tumors were measured twice weekly and the results presented as the average tumor volume, expressed in mm3 ± SEM, *p<0.0001. Fig. 58 shows a comparison of isoelectric points for various anti-PSMA constructs. 10 Fig. 59 plots change in wavelength compared to CNTO5825 control molecule. Control CNTO607 shows characteristically strong self-interaction. Error bars represent standard deviations from triplicate measurements. Fig. 60 shows a comparison of retention times on IgG and control columns in an anti-PSMA cross-interaction assay. 15 Figs. 61A-61B show ex vivo assessment of CD33xCD3 bispecific antibodies using anti-CD3 arm CD3B219 and CD3B376 cytotoxicity of blasts and T cell activation in fresh AML patient whole blood. FIG. 2A shows the percent of total cell cytotoxicity of AML cells using CD33 bispecific antibodies or the CD3xnull controls. FIG. 2B shows T cell activation induced by CD33 bispecific antibodies or the CD3xnull controls. No Fc blocker was added. 20 Figs. 62A-62C show CD33xCD3 T-cell mediated cytotoxicity assays. CD33xCD3 bispecific antibodies using anti-CD3 arm CD3B219 and anti-CD3B376 were incubated with human pan T cells and AML cell lines that are either wildtype (KG1, FIG. 3A), heterozygous (SH2, FIG. 3B) or homozygous (OCIAML3, FIG. 3C) for the CD33 SNP rs12459419 mutation. After 48 hr at 37°C, 5% CO2, total tumor cell cytotoxicity was measured by flow cytometry. 25 Figs. 63A-63B show ex vivo assessment of C33B904 antibodies paired with either CD3B219 or CD3B376 on the cytotoxicity of MOLM-13 cells exogenously added to normal healthy human whole blood (N=6 donors): Percent of cytotoxicity of MOLM-13 cells (FIG. 4A) and CD33+ CD14+ monocytes (FIG. 4B) using CD33xCD3 bispecifics and respective nullxCD3 controls at 48 hrs. 30 Figs. 64A-64B show ex vivo assessment of CD33xCD3 bispecific antibodies using anti-CD3 arm CD3B219 and CD3B376 on the cytotoxicity of monocytes and T cell activation in 2026204725   18 Jun 2026 fresh whole blood from six normal cynomologous monkey donors. FIG. 5A shows the percent of total cell cytotoxicity of CD33+CD14+ cyno monocytes using CD33 bispecific antibodies or their CD3xnull controls. FIG. 5B shows T cell activation induced by CD33 bispecific antibodies or their CD3xnull controls. No Fc blocker was added. 5 Fig. 65 shows anti-tumor efficacy of C3CB189 in MOLM-13 human AML xenografts in T cell humanized NSG mice. Disseminated MOLM-13 tumors were imaged for bioluminescence (BLI) twice weekly and the results presented as average radiance (p / s / cm2 / sr) ± SEM (n=8-10 / group). *p< 0.0001 for treatment vs. control, calculated by two-way ANOVA with Bonferroni test. 10 Fig. 66 shows survival of animals treated with C3CB189 in MOLM-13 Human AML xenografts in T cell humanized NSG mice. Survival of MOLM-13 bearing mice is graphically represented using a Kaplan-Meier curve and evaluated by Log-rank (Mantel-Cox) test. *p< 0.0001 for treatment vs. control groups. Fig. 67 shows anti-tumor efficacy of C3CB88 in MOLM-13 human AML xenografts in T 15 cell humanized NSG mice. Disseminated MOLM-13 tumors were imaged for bioluminescence (BLI) twice weekly and the results presented as average radiance (p / s / cm2 / sr) ± SEM (n=8-10 / group). *p< 0.0001 for treatment vs. control, calculated by two-way ANOVA with Bonferroni test. Fig. 68 shows survival of animals treated with C3CB88 in MOLM-13 human AML 20 xenografts in T cell humanized NSG mice. Survival of MOLM-13 bearing mice is graphically represented using a Kaplan-Meier curve and evaluated by Log-rank (Mantel-Cox) test. *p< 0.05 for treatment vs. control groups. Figure 69 shows the alignment of select anti-TMEFF2 antibody heavy chain variable regions (VH). The VH regions are identified by their SEQ ID NO: at the beginning of each row. 25 Figure 70 shows the alignment of select anti-TMEFF2 antibody light chain variable regions (VL). The VH regions are identified by their SEQ ID NO: at the beginning of each row. Figure 71 shows the reduction in mean tumor volume of each mouse treated with 0.5 mg / kg TMCB132 in an ex vivo LnCaP prostate cancer model in male NGS mice. Figure 72 shows efficacy of TMEB762xCD3B376 in established LNCaP Xenografts in T 30 Cell Humanized NSG Mice. 2026204725   18 Jun 2026 Figure 73 shows T-cell activation in LnCaP prostatec cancer cells in response to administration of TMCB132. Figure 74 shows T cell-mediated cytotoxicity of TMCB132. Figure 75 shows the antitumor efficacity of TMCB132 in T-cell humanized mice. 5 DETAILED DESCRIPTION OF THE INVENTION All publications, including but not limited to patents and patent applications, cited in this specification are herein incorporated by reference as though fully set forth. It is to be understood that the terminology used herein is for the purpose of describing 10 particular embodiments only and is not intended to be limiting. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although any methods and materials similar or equivalent to those described herein may be used in the practice for testing of the present invention, exemplary materials and methods are 15 described herein. In describing and claiming the present invention, the following terminology will be used. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the content clearly dictates otherwise. Thus, for example, reference to “a cell” includes a combination of two or more cells, and the like. 20 “Specific binding” or “specifically binds” or “binds” refers to an antibody binding to an antigen or an epitope within the antigen with greater affinity than for other antigens. Typically, the antibody binds to the antigen or the epitope within the antigen with an equilibrium dissociation constant (Kd) of about 5x10-8 M or less, for example about 1x10-9 M or less, about 1x10-10 M or less, about 1x10-11 M or less, or about 1x10-12 M or less, typically with the Kd that 25 is at least one hundred-fold less than its Kd for binding to a non-specific antigen (e.g., BSA, casein). The dissociation constant may be measured using standard procedures. Antibodies that specifically bind to the antigen or the epitope within the antigen may, however, have crossreactivity to other related antigens, for example to the same antigen from other species (homologs), such as human or monkey, for example Macaca fascicularis (cynomolgus, cyno) or 30 Pan troglodytes (chimpanzee, chimp). While a monospecific antibody specifically binds one 2026204725   18 Jun 2026 antigen or one epitope, a bispecific antibody specifically binds two distinct antigens or two distinct epitopes. “Antibodies” is meant in a broad sense and includes immunoglobulin molecules including monoclonal antibodies including murine, human, humanized and chimeric monoclonal 5 antibodies, antigen binding fragments, bispecific or multispecific antibodies, dimeric, tetrameric or multimeric antibodies, single chain antibodies, domain antibodies and any other modified configuration of the immunoglobulin molecule that comprises an antigen binding site of the required specificity. “Full length antibody molecules” are comprised of two heavy chains (HC) and two light chains (LC) inter-connected by disulfide bonds as well as multimers thereof (e.g. 10 IgM). Each heavy chain is comprised of a heavy chain variable region (VH) and a heavy chain constant region (comprised of domains CH1, hinge, CH2 and CH3). Each light chain is comprised of a light chain variable region (VL) and a light chain constant region (CL). The VH and the VL regions may be further subdivided into regions of hypervariability, termed complementarity determining regions (CDR), interspersed with framework regions (FR). Each 15 VH and VL is composed of three CDRs and four FR segments, arranged from amino-to-carboxy-terminus in the following order: FR1, CDR1, FR2, CDR2, FR3, CDR3 and FR4. “Complementarity determining regions (CDR)” are antibody regions that bind an antigen. CDRs may be defined using various delineations such as Kabat (Wu et al. (1970) J Exp Med 132: 211-50) (Kabat et al., Sequences of Proteins of Immunological Interest, 5th Ed. Public 20 Health Service, National Institutes of Health, Bethesda, Md., 1991), Chothia (Chothia et al. (1987) J Mol Biol 196: 901-17), IMGT (Lefranc et al. (2003) Dev Comp Immunol 27: 55-77) and AbM (Martin and Thornton (1996) J Bmol Biol 263: 800-15). The correspondence between the various delineations and variable region numbering are described (see e.g. Lefranc et al. (2003) Dev Comp Immunol 27: 55-77; Honegger and Pluckthun, (2001) J Mol Biol 309:657-70; 25 International ImMunoGeneTics (IMGT) database; Web resources, http: / / www_imgt_org). Available programs such as abYsis by UCL Business PLC may be used to delineate CDRs. The term “CDR”, “HCDR1”, “HCDR2”, “HCDR3”, “LCDR1”, “LCDR2” and “LCDR3” as used herein includes CDRs defined by any of the methods described supra, Kabat, Chothia, IMGT or AbM, unless otherwise explicitly stated in the specification. 30 Immunoglobulins may be assigned to five major classes, IgA, IgD, IgE, IgG and IgM, depending on the heavy chain constant domain amino acid sequence. IgA and IgG are further 2026204725   18 Jun 2026 sub-classified as the isotypes IgA1, IgA2, IgG1, IgG2, IgG3 and IgG4. Antibody light chains of any vertebrate species may be assigned to one of two clearly distinct types, namely kappa (k) and lambda (X), based on the amino acid sequences of their constant domains. “Antigen binding fragment” refers to a portion of an immunoglobulin molecule that binds 5 an antigen. Antigen binding fragments may be synthetic, enzymatically obtainable or genetically engineered polypeptides and include the VH, the VL, the VH and the VL, Fab, F(ab')2, Fd and Fv fragments, domain antibodies (dAb) consisting of one VH domain or one VL domain, shark variable IgNAR domains, camelized VH domains, minimal recognition units consisting of the amino acid residues that mimic the CDRs of an antibody, such as FR3-CDR3-FR4 portions, the 10 HCDR1, the HCDR2 and / or the HCDR3 and the LCDR1, the LCDR2 and / or the LCDR3. VH and VL domains may be linked together via a synthetic linker to form various types of single chain antibody designs where the VH / VL domains may pair intramolecularly, or intermolecularly in those cases when the VH and VL domains are expressed by separate single chain antibody constructs, to form a monovalent antigen binding site, such as single chain Fv 15 (scFv) or diabody; described for example in Int. Patent Publ. Nos. WO1998 / 44001, WO1988 / 01649, WO1994 / 13804 and WO1992 / 01047. “Monoclonal antibody” refers to an antibody obtained from a substantially homogenous population of antibody molecules, i.e., the individual antibodies comprising the population are identical except for possible well-known alterations such as removal of C-terminal lysine from 20 the antibody heavy chain or post-translational modifications such as amino acid isomerization or deamidation, methionine oxidation or asparagine or glutamine deamidation. Monoclonal antibodies typically bind one antigenic epitope. A bispecific monoclonal antibody binds two distinct antigenic epitopes. Monoclonal antibodies may have heterogeneous glycosylation within the antibody population. Monoclonal antibody may be monospecific or multispecific such as 25 bispecific, monovalent, bivalent or multivalent. “Isolated antibody” refers to an antibody or antibody fragment that is substantially free of other antibodies having different antigenic specificities (e.g., an isolated antibody specifically binding an antigen is substantially free of antibodies that specifically bind antigens other than the antigen). In the case of bispecific CD3 antibodies, the bispecific antibody specifically binds both 30 CD3 a second antigen. “Isolated antibody” encompasses antibodies that are isolated to a higher 2026204725   18 Jun 2026 purity, such as antibodies that are 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% pure. “Humanized antibody” refers to an antibody in which at least one CDR is derived from non-human species and at least one framework is derived from human immunoglobulin 5 sequences. Humanized antibody may include substitutions in the frameworks so that the frameworks may not be exact copies of expressed human immunoglobulin or human immunoglobulin germline gene sequences. “Human antibody” refers to an antibody that is optimized to have minimal immune response when administered to a human subject. Variable regions of human antibody are 10 derived from human immunoglobulin sequences. If human antibody contains a constant region or a portion of the constant region, the constant region is also derived from human immunoglobulin sequences. Human antibody comprises heavy and light chain variable regions that are “derived from” sequences of human origin if the variable regions of the human antibody are obtained from a system that uses human germline immunoglobulin or rearranged 15 immunoglobulin genes. Such exemplary systems are human immunoglobulin gene libraries displayed on phage, and transgenic non-human animals such as mice or rats carrying human immunoglobulin loci. “Human antibody” typically contains amino acid differences when compared to the immunoglobulins expressed in humans due to differences between the systems used to obtain the human antibody and human immunoglobulin loci, introduction of somatic 20 mutations or intentional introduction of substitutions into the frameworks or CDRs, or both. Typically, “human antibody” is at least about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical in amino acid sequence to an amino acid sequence encoded by human germline immunoglobulin or rearranged immunoglobulin genes. In some cases, “human antibody” may contain consensus framework 25 sequences derived from human framework sequence analyses, for example as described in Knappik et al., (2000) J Mol Biol 296:57-86, or synthetic HCDR3 incorporated into human immunoglobulin gene libraries displayed on phage, for example as described in Shi et al., (2010) J Mol Biol 397:385-96, and in Int. Patent Publ. No. WO2009 / 085462. "Percent (%) amino acid sequence identity" with respect to a reference polypeptide 30 sequence is defined as the percentage of amino acid residues in a candidate sequence that are identical with the amino acid residues in the reference polypeptide sequence, after aligning the 2026204725   18 Jun 2026 sequences and introducing gaps, if necessary, to achieve the maximum percent sequence identity, and not considering any conservative substitutions as part of the sequence identity. Alignment for purposes of determining percent amino acid sequence identity can be achieved in various ways that are within the skill in the art, for instance, using publicly available computer software 5 such as BLAST, BLAST-2, ALIGN or Megalign (DNASTAR) software. Those skilled in the art can determine appropriate parameters for aligning sequences, including any algorithms needed to achieve maximal alignment over the full length of the sequences being compared. For purposes herein, however, % amino acid sequence identify values are generated using the sequence comparison computer program ALIGN-2. The ALIGN-2 sequence comparison computer 10 program was authored by Genentech. Inc., and the source code has been filed with user documentation in the U.S. Copyright Office, Washington D.C., 20559, where it is registered under U.S. Copyright Registration No. TXU510087. The ALIGN-2 program is publicly available from Genentech. Inc., South San Francisco, Calif., or may be compiled from the source code. The ALIGN-2 program should be compiled for use on a UNIX operating system, including 15 digital UNIX V4.0D. All sequence comparison parameters are set by the ALIGN-2 program and do not vary. Where ALIGN-2 is employed for amino acid sequence comparisons, the % amino acid sequence identity of a given amino acid sequence A to, with, or against a given amino acid sequence B (which can altematively be phrased as a given amino acid sequence A that has or comprises a certain % amino acid sequence identity to, with, or against a given amino acid 20 sequence B) is calculated as follows: 100 times the fraction X / Y, where X is the number of amino acid residues scored as identical matches by the sequence alignment program ALIGN-2 in that program's alignment of A and B, and where Y is the total number of amino acid residues in B. It will be appreciated that where the length of 25 amino acid sequence A is not equal to the length of amino acid sequence B, the % amino acid sequence identity of A to B will not equal the % amino acid sequence identity of B to A. Unless specifically stated otherwise, all % amino acid sequence identity values used herein are obtained as described in the immediately preceding paragraph using the ALIGN-2 computer program. Antibodies in which antigen binding sites are derived from a non-human species are not 30 included in the definition of “human antibody”. 2026204725   18 Jun 2026 “Recombinant” refers to DNA, antibodies and other proteins that are prepared, expressed, created or isolated by recombinant means when segments from different sources are joined to produce recombinant DNA, antibodies or proteins. “Epitope” refers to a portion of an antigen to which an antibody specifically binds. 5 Epitopes typically consist of chemically active (such as polar, non-polar or hydrophobic) surface groupings of moieties such as amino acids or polysaccharide side chains and may have specific three-dimensional structural characteristics, as well as specific charge characteristics. An epitope may be composed of contiguous and / or discontiguous amino acids that form a conformational spatial unit. For a discontiguous epitope, amino acids from differing portions of 10 the linear sequence of the antigen come in close proximity in 3-dimensional space through the folding of the protein molecule. Antibody “epitope” depends on the methodology used to identify the epitope. “Paratope” refers to a portion of an antibody to which an antigen specifically binds. A paratope may be linear in nature or may be discontinuous, formed by a spatial relationship 15 between non-contiguous amino acids of an antibody rather than a linear series of amino acids. A “light chain paratope” and a “heavy chain paratope” or “light chain paratope amino acid residues” and “heavy chain paratope amino acid residues” refer to antibody light chain and heavy chain residues in contact with an antigen, respectively, or in general, “antibody paratope residues” refer to those antibody amino acids that are in contact with antigen. 20 “Bispecific” refers to an antibody that specifically binds two distinct antigens or two distinct epitopes within the same antigen. The bispecific antibody may have cross-reactivity to other related antigens, for example to the same antigen from other species (homologs), such as human or monkey, for example Macaca fascicularis (cynomolgus, cyno) or Pan troglodytes, or may bind an epitope that is shared between two or more distinct antigens. 25 “Multispecific” refers to an antibody that specifically binds two or more distinct antigens or two or more distinct epitopes within the same antigen. The multispecific antibody may have cross-reactivity to other related antigens, for example to the same antigen from other species (homologs), such as human or monkey, for example Macaca fascicularis (cynomolgus, cyno) or Pan troglodytes, or may bind an epitope that is shared between two or more distinct antigens. 2026204725   18 Jun 2026 “Variant” refers to a polypeptide or a polynucleotide that differs from a reference polypeptide or a reference polynucleotide by one or more modifications, for example one or more substitutions, insertions or deletions. “Vector” refers to a polynucleotide capable of being duplicated within a biological 5 system or that can be moved between such systems. Vector polynucleotides typically contain elements, such as origins of replication, promoter, polyadenylation signal and selection markers, that function to facilitate the duplication or maintenance of these polynucleotides in a biological system, such as a cell, virus, animal, plant, and reconstituted biological systems utilizing biological components capable of duplicating a vector. The vector polynucleotide may be DNA 10 or RNA molecules or a hybrid of these, single stranded or double stranded. “Expression vector” refers to a vector that can be utilized in a biological system or in a reconstituted biological system to direct the translation of a polypeptide encoded by a polynucleotide sequence present in the expression vector. “Polynucleotide” refers to a molecule comprising a chain of nucleotides covalently linked 15 by a sugar-phosphate backbone or other equivalent covalent chemistry. Double and singlestranded DNA and RNA are typical examples of polynucleotides. “Polynucleotide” may refer to a synthetic molecule comprising a chain of nucleotides covalently linked by a sugar-phosphate backbone or other equivalent covalent chemistry. cDNA is an exemplary synthetic polynucleotide. 20 “Polypeptide” or “protein” refers to a molecule that comprises at least two amino acid residues linked by a peptide bond to form a polypeptide. Small polypeptides of less than 50 amino acids may be referred to as “peptides”. “Flow cytometry” is a technology that is used to analyze the physical and chemical characteristics of particles in a fluid as it passes through at least one laser. Cell components are 25 fluorescently labelled and then excited by the laser to emit light at varying wavelengths (Adan, et al, Critical Reviews in Biotechnology (2016) 1549-7801). “Anti-idiotypic (anti-Id) antibody” is an antibody that recognizes the antigenic determinants (e.g. the paratope or CDRs) of the antibody. It is generally known in the art the process of producing or preparing an anti-idiotypic antibody. (Lathey, J. et al Immunology 1986 30 57(1):29-35). The anti-Id antibody may be antigen-blocking or non-blocking. The antigenblocking anti-Id antibody may be used to detect the free antibody in a sample, e.g. CD3. The 2026204725   18 Jun 2026 non-blocking anti-Id antibody may be used to detect the total antibody (free, partially bound to antigen, or fully bound to antigen) in a sample. An anti-Id antibody may be prepared by immunizing an animal with the antibody to which an anti-Id antibody is being prepared. In some embodiments described herein, the anti-idiotypic antibody is used for detecting the level of the 5 therapeutic antibodies in a sample. An anti-Id antibody may also be used as an immunogen to induce an immune response in yet another animal, producing a so-called anti-anti-Id antibody. An anti-anti-Id antibody may be epitopically identical to the original mAb, which induced the anti-Id antibody. Thus, by using antibodies to the idiotypic determinants of a mAb, it is possible to identify other clones 10 expressing antibodies of identical specificity. Anti-Id antibodies may be varied (thereby producing anti-Id antibody variants) and / or derivatized by any suitable technique, such as those described elsewhere herein with respect to the anti-CD3 antibodies. PSMA refers to Prostate Specific Membrane Antigen. The amino acid sequence of Pan troglodytes (also referred to as chimpanzee or chimp) PSMA is shown in SEQ ID NO: 49. The 15 extracellular domain spans residues 44 - 750, the transmembrane domain spans residues 20 - 43 and the cytoplasmic domain spans residues 1 - 19 of SEQ ID NO: 49. The amino acid sequence of the Macaca fascicularis (also referred to as cynomolgus monkey, macaque or cyno) PSMA is shown in SEQ ID NO: 50. The extracellular domain spans residues 44 - 750, the transmembrane domain spans residues 20 - 43 and the cytoplasmic domain spans residues 1 - 19 of SEQ ID NO: 20 50. The amino acid sequence of the human PSMA is shown in SEQ ID NO:51. The extracellular domain spans residues 44 - 750, the transmembrane domain spans residues 20 - 43 and the cytoplasmic domain spans residues 1 - 19 of SEQ ID NO:51. Throughout the specification, “CD3-specific” or “specifically binds CD3” or “anti-CD3 antibody” refers to antibodies that bind specifically to the CD3-epsilon polypeptide (SEQ ID 25 NO:635), including antibodies that bind specifically to the CD3-epsilon extracellular domain (ECD) (SEQ ID NO:636). CD3-epsilon, together with CD3-gamma, -delta and -zeta, and the T-cell receptor alpha / beta and gamma / delta heterodimers, forms the T-cell receptor-CD3 complex. This complex plays an important role in coupling antigen recognition to several intracellular signal-transduction pathways. The CD3 complex mediates signal transduction, resulting in T cell 30 activation and proliferation. CD3 is required for the immune response. 2026204725   18 Jun 2026 SEQ ID NO:635 (Human CD3 epsilon) MQSGTHWRVLGLCLLSVGVWGQDGNEEMGGITQTPYKVSISGTTVILTCPQYPG SEILWQHNDKNIGGDEDDKNIGSDEDHLSLKEFSELEQSGYYVCYPRGSKPEDA NFYLYLRARVCENCMEMDVMSVATIVIVDICITGGLLLLVYYWSKNRKAKAKPV 5 TRGAGAGGRQRGQNKERPPPVPNPDYEPIRKGQRDLYSGLNQRRI SEQ ID NO:636 (Human CD3 epsilon extracellular domain) DGNEEMGGITQTPYKVSISGTTVILTCPQYPGSEILWQHNDKNIGGDEDDKNIG SDEDHLSLKEFSELEQSGYYVCYPRGSKPEDANFYLYLRARVCENCMEMD 10 As used herein, the terms “interleukin-1 receptor accessory protein”, “IL1RAP” and “IL1-RAP” specifically include the human IL1RAP protein, for example as described in GenBank Accession No. AAB84059, NCBI Reference Sequence: NP_002173.1 and UniProtKB / Swiss-Prot Accession No. Q9NPH3-1 (see also Huang et al., 1997, Proc. Natl. Acad. 15 Sci. USA. 94 (24), 12829-12832). IL1RAP is also known in the scientific literature as IL1 R3, C3orf13, FLJ37788, IL-1 RAcP and EG3556. “CD33” refers to cluster of differentiation 33 protein. CD33 is a 67 kilodalton (kD) single pass transmembrane glycoprotein and is a member of the sialic acid-binding immunoglobulin-like lectins (Siglecs) family. CD33 is primarily considered to be a myeloid 20 differentiation antigen, with low expression in myeloid progenitors, neutrophils and macrophages and high expression in circulating monocytes and dendritic cells. Human CD33 extracellular domain (Uniprot P20138) (SEQ ID NO:636) and cynomolgus CD33 (XP_005590138.1) are examples of proteins for use in generating CD33-specific antibodies according to the present disclosure. 25        “TMEFF2” refers to human transmembrane protein with EGF like and two follistatin like domains 2, also called tomoregulin 2. The amino acid sequence of the full length human TMEFF2 is shown in SEQ ID NO: 77. The extracellular domain of TMEFF2 is shown in SEQ ID NO: 575 and spans residues 40-374 of the full length TMEFF2. TMEFF2 extracellular domain harbors three distinct subdomains, the Kazal-like 1 (residues 85-137), the Kazal-like 2 30 (residues 176-229) and the EGF domain (residues 261-301). The TMEFF2 EGF domain is shown in SEQ ID NO: 577. The TMEFF2 “membrane proximal region” refers to the TMEFF2 2026204725   18 Jun 2026 reqion of SEQ ID NO: 629, which encompasses the EGF domain and the N- C-terminal linker regions (e.g. residues 230-320 of full length human TMEFF2 of SEQ ID NO: 77). All references to proteins, polypeptides and protein fragments herein are intended to refer to the human version of the respective protein, polypeptide or protein fragment unless explicitly 5 specified as being from a non-human species. Thus, “TMEFF2” means human TMEFF2 unless specified as being from a non-human species, e.g., “mouse TMEFF2” or “monkey TMEFF2” etc. SEQ ID NO: 77 (full length human TMEFF2) MVLWESPRQCSSWTLCEGFCWLLLLPVMLLIVARPVKLAAFPTSLSDCQTPTGW NCSGYDDRENDLFLCDTNTCKFDGECLRIGDTVTCVCQFKCNNDYVPVCGSNGESYQN 10 ECYLRQAACKQQSEILVVSEGSCATDAGSGSGDGVHEGSGETSQKETSTCDICQFGAEC DEDAEDVWCVCNIDCSQTNFNPLCASDGKSYDNACQIKEASCQKQEKIEVMSLGRCQD NTTTTTKSEDGHYARTDYAENANKLEESAREHHIPCPEHYNGFCMHGKCEHSINMQEPS CRCDAGYTGQHCEKKDYSVLYVVPGPVRFQYVLIAAVIGTIQIAVICVVVLCITRKCPRS NRIHRQKQNTGHYSSDNTTRASTRLI 15 SEQ ID NO: 575 (extracellular domain of human TMEFF2) FPTSLSDCQTPTGWNCSGYDDRENDLFLCDTNTCKFDGECLRIGDTVTCVCQFK CNNDYVPVCGSNGESYQNECYLRQAACKQQSEILVVSEGSCATDAGSGSGDGVHEGSG ETSQKETSTCDICQFGAECDEDAEDVWCVCNIDCSQTNFNPLCASDGKSYDNACQIKEA SCQKQEKIEVMSLGRCQDNTTTTTKSEDGHYARTDYAENANKLEESAREHHIPCPEHYN 20 GFCMHGKCEHSINMQEPSCRCDAGYTGQHCEKKDYSVLYVVPGPVRFQYVLIAAVIGTI QIAVICVVVLCITRKCPRSNRIHRQKQNTGHYSSDNTTRASTRLI TMEFF2 EGF domain SEQ ID NO: 577 HHIPCPEHYNGFCMHGKCEHSINMQEPSCRCDAGYTGQHCE TMEFF2 membrane proximal region SEQ ID NO: 629 25 NTTTTTKSEDGHYARTDYAENANKLEESAREHHIPCPEHYNGFCMHGKCEHSIN MQEPSCRCDAGYTGQHCEKKDYSVLYVVPGPVRFQYV “TMEFF2 positive cancer” refers to a cancer tissue or a cancer cell that displays measurable level of TMEFF2 protein. Level of TMEFF2 protein may be measured using well known assays using, for example ELISA, immunofluorescence, flow cytometry or 30 radioimmunoassay on live or lysed cells.“Overexpress”, “overexpressed” and “overexpressing” interchangeably refers to a sample such as a cancer cell, malignant cell or cancer tissue that has 2026204725   18 Jun 2026 measurably higher levels of tumor antigen when compared to a reference sample. The overexpression may be caused by gene amplification or by increased transcription or translation. Expression and overexpression of protein in the sample may be measured using well-known assays using, for example ELISA, immunofluorescence, flow cytometry or radioimmunoassay 5 on live or lysed cells. Expression and overexpression of a polynucleotide in the sample may be measured, for example, using fluorescent in situ hybridization, Southern blotting, or PCR techniques. A protein or a polynucleotide is overexpressed when the level of the protein or the polynucleotide in the sample is at least 1.5-fold higher when compared to the reference sample. Selection of the reference sample is well known. 10 “Sample” refers to a collection of similar fluids, cells, or tissues isolated from a subject, as well as fluids, cells, or tissues present within a subject. Exemplary samples are biological fluids such as blood, serum and serosal fluids, plasma, lymph, urine, saliva, cystic fluid, tear drops, feces, sputum, mucosal secretions of the secretory tissues and organs, vaginal secretions, ascites fluids such as those associated with non-solid tumors, fluids of the pleural, pericardial, 15 peritoneal, abdominal and other body cavities, fluids collected by bronchial lavage, liquid solutions contacted with a subject or biological source, for example, cell and organ culture medium including cell or organ conditioned medium, lavage fluids and the like, tissue biopsies, fine needle aspirations or surgically resected tumor tissue. A “cancer cell” or a “tumor cell” as used herein refers to a cancerous, pre-cancerous or 20 transformed cell, either in vivo, ex vivo, or in tissue culture, that has spontaneous or induced phenotypic changes. These changes do not necessarily involve the uptake of new genetic material. Although transformation may arise from infection with a transforming virus and incorporation of new genomic nucleic acid or uptake of exogenous nucleic acid, it can also arise spontaneously or following exposure to a carcinogen, thereby mutating an endogenous gene. 25 Transformation / cancer is exemplified by morphological changes, immortalization of cells, aberrant growth control, foci formation, proliferation, malignancy, modulation of tumor specific marker levels, invasiveness, tumor growth in suitable animal hosts such as nude mice, and the like, in vitro, in vivo, and ex vivo (Freshney, Culture of Animal Cells: A Manual of Basic Technique (3rd ed. 1994)). 30 Unless otherwise stated, any numerical values, such as a concentration or a concentration range described herein, are to be understood as being modified in all instances by the term 2026204725   18 Jun 2026 “about.” Thus, a numerical value typically includes ± 10% of the recited value. For example, a concentration of 1 mg / mL includes 0.9 mg / mL to 1.1 mg / mL. Likewise, a concentration range of 1% to 10% (w / v) includes 0.9% (w / v) to 11% (w / v). As used herein, the use of a numerical range expressly includes all possible subranges, all individual numerical values within that range, 5 including integers within such ranges and fractions of the values unless the context clearly indicates otherwise. “Effector antigens” are antigens from cells of the immune system that can stimulate or trigger cytotoxicity, phagocytosis, antigen presentation, and / or cytokine release. Such effector antigens are from, for example but not limited to, T cells and natural killer (NK) cells. Examples 10 of suitable specificities for effector antigens include but are not limited to CD3 or CD3 subunits such as CD3s for T cells and CD16 for NK cells. Such cell surface molecules of effector cells are suitable for mediating cell killing. Effector cells are cells of the immune system that can stimulate or trigger cytotoxicity, phagocytosis, antigen presentation, and / or cytokine release. Such effector cells are, for example but not limited to, T-cells, natural killer (NK) cells, 15 granulocytes, monocytes, macrophages, dendritic cells, and antigen-presenting cells. Examples of suitable specificities for effector cells include but are not limited to CD2, CD3 and CD3 subunits such as CD3e, CD5, CD28 and other components of the T-cell receptor (TCR) for T cells; CD16, CD16A, CD25, CD38, CD44, CD56, CD69, CD94, CD335 (NKp46), CD336, (NKp44), CD337 (NKp30), NKp80, NKG2C and NKG2D, DNAM, NCRs for NK cells; CD18, 20 CD64 and CD89 for granulocytes; CD18, CD32, CD64, CD89 and mannose receptor for monocytes and macrophages; CD64 and mannose receptor for dendritic cells; as well as CD35. In certain embodiments of the inventions, those specificities, i.e. cell surface molecules, of effector cells are suitable for mediating cell killing upon binding of a bispecific or multispecific molecules to such cell surface molecule and, thereby, inducing cytolysis or apoptosis. 25 “Bispecific CD3 antibody” refers to a molecule comprising at least one binding domain specifically binding CD3 and at least one binding domain specifically binding a second antigen, such as a bispecific antibody comprising a first domain that specifically binds CD3 and a second domain that specifically binds a second antigen. The domains specifically binding CD3 and a second antigen are typically Vh / Vl pairs. The bispecific CD3 antibody may be monovalent in 30 terms of its binding to either CD3 or the second antigen. In some embodiments, the second, or target, antigen is a cell surface antigen that is expressed on a target cell other than an immune 2026204725   18 Jun 2026 effector cell. In some embodiments, the second antigen a tumor associated antigen (TAA). Exemplary TAAs are PSMA, CD33, IL1RAP, and TMEFF2. “Bispecific PSMA^CD3 antibody”, “PSMA / CD3 antibody”, “bispecific anti-PSMA*CD3 antibody” or “anti-PSMA / CD3 antibody” and the like refer to a molecule 5 comprising at least one binding domain specifically binding PSMA and at least one binding domain specifically binding CD3. The domains specifically binding PSMA and CD3 are typically Vh / Vl pairs. The bispecific anti-PSMA*CD3 antibody may be monovalent in terms of its binding to either PSMA or CD3. “Bispecific CD33*CD3 antibody”, “CD33 / CD3 antibody”, “bispecific anti-CD33*CD3 10 antibody” or “anti-CD33 / CD3 antibody” and the like refer to a molecule comprising at least one binding domain specifically binding CD33 and at least one binding domain specifically binding CD3. The domains specifically binding CD33 and CD3 are typically Vh / Vl pairs. The bispecific anti-CD33*CD3 antibody may be monovalent in terms of its binding to either CD33 or CD3. 15 “Bispecific IL1RAPxCD3 antibody”, “IL1RAP / CD3 antibody”, “bispecific anti-IL1RAP^CD3 antibody” or “anti- IL1RAP / CD3 antibody” and the like refer to a molecule comprising at least one binding domain specifically binding IL1RAP and at least one binding domain specifically binding CD3. The domains specifically binding IL1RAP and CD3 are typically Vh / Vl pairs. The bispecific anti- IL1RAPxCD3 antibody may be monovalent in terms 20 of its binding to either IL1RAP or CD3. “Bispecific anti-TMEFF2 / anti-CD3 antibody”, TMEFF2 / CD3 antibody, TMEFF2xCD3 antibody and the like refer to an antibody that binds TMEFF2 and CD3. “Valent” refers to the presence of a specified number of binding sites specific for an antigen in a molecule. As such, the terms “monovalent”, “bivalent”, “tetravalent”, and 25 “hexavalent” refer to the presence of one, two, four and six binding sites, respectively, specific for an antigen in a molecule. “Multivalent” refers to the presence of two or more binding sites specific for an antigen in a molecule. “An antigen specific CD4+ or CD8+ T cell” refers to a CD4+ or CD8+ T cell activated by a specific antigen, or immunostimulatory epitope thereof. 30 “Subject” includes any human or nonhuman animal. “Nonhuman animal” includes all vertebrates, e.g., mammals and non-mammals, such as nonhuman primates, sheep, dogs, cats, 2026204725   18 Jun 2026 horses, cows chickens, amphibians, reptiles, etc. Except when noted, the terms “patient” or “subject” are used interchangeably. The numbering of amino acid residues in the antibody constant region throughout the specification is according to the EU index as described in Kabat et al., Sequences of Proteins of 5 Immunological Interest, 5th Ed. Public Health Service, National Institutes of Health, Bethesda, MD. (1991), unless otherwise explicitly stated. Table 1. Conventional one- and three-letter amino acid codes used herein Amino acid Three-letter code One-letter code Alanine Ala A Arginine Arg R Asparagine Asn N Aspartate Asp D Cysteine Cys C Glutamate Gln E Glutamine Glu Q Glycine Gly G Histidine His H Isoleucine Ile I Lysine Lys K Methionine Met M Phenylalanine Phe F Proline Pro P Serine Ser S Threonine Thr T Tryptophan Trp W Tyrosine Tyr Y Valine Val V Compositions of Matter The present invention provides anti-CD3 antibodies and antigen-binding fragments 10 thereof, antibodies and antigen-binding fragments thereof that specifically bind PSMA, 2026204725   18 Jun 2026 antibodies and antigen-binding fragments thereof that specifically bind CD33, antibodies and antigen-binding fragments thereof that specifically bind IL1RAP, multispecific antibodies comprising a first domain that specifically binds CD3 and a second domain that specifically binds a second antigen, and multispecific antibodies that specifically bind CD3 and one or more 5 of PSMA, CD33, IL1RAP, and TMEFF2. The present invention provides polypeptides and polynucleotides encoding the antibodies of the invention or complementary nucleic acids thereof, vectors, host cells, and methods of making and using them. General Aspects of the Antibodies Described Herein The anti-CD3 antibodies or antigen-binding fragments described herein include variants 10 having single or multiple amino acid substitutions, deletions, or additions that retain the biological properties (e.g., binding affinity or immune effector activity) of the described anti-CD3 antibodies or antigen-binding fragments. In the context of the present invention the following notations are, unless otherwise indicated, used to describe a mutation; i) substitution of an amino acid in a given position is written as e.g. K409R which means a substitution of a 15 Lysine in position 409 with an Arginine; and ii) for specific variants the specific three or one letter codes are used, including the codes Xaa and X to indicate any amino acid residue. Thus, the substitution of Arginine for Lysine in position 409 is designated as: K409R, or the substitution of any amino acid residue for Lysine in position 409 is designated as K409X. In case of deletion of Lysine in position 409 it is indicated by K409*. The skilled person may produce 20 variants having single or multiple amino acid substitutions, deletions, or additions. These variants may include: (a) variants in which one or more amino acid residues are substituted with conservative or nonconservative amino acids, (b) variants in which one or more amino acids are added to or deleted from the polypeptide, (c) variants in which one or more amino acids include a substituent group, and (d) variants in which the polypeptide is fused with 25 another peptide or polypeptide such as a fusion partner, a protein tag or other chemical moiety, that may confer useful properties to the polypeptide, such as, for example, an epitope for an antibody, a polyhistidine sequence, a biotin moiety and the like. Antibodies or antigen-binding fragments described herein may include variants in which amino acid residues from one species are substituted for the corresponding residue in another species, either at the conserved or 30 nonconserved positions. In other embodiments, amino acid residues at nonconserved positions 2026204725   18 Jun 2026 are substituted with conservative or nonconservative residues. The techniques for obtaining these variants, including genetic (deletions, mutations, etc.), chemical, and enzymatic techniques, are known to persons having ordinary skill in the art. The antibodies or antigen-binding fragments described herein may may be an IgM, an 5 IgD, an IgG, an IgA or an IgE isotype. In some embodiments, the antibody isotype is an IgG1, an IgG2, an IgG3, or an IgG4 isotype. In some embodiments, the antibody is an IgG1 isotype. In some embodiments, the antibody is an IgG2 isotype. In some embodiments, the antibody is an IgG3 isotype. In some embodiments, the antibody is an IgG4 isotype. The specificity of the antibody or antigen-binding fragment thereof is in part determined by the amino acid sequence 10 and arrangement, of the CDRs. Therefore, the CDRs of one isotype may be transferred to another isotype without altering antigen specificity. Accordingly, such antibody isotypes are within the scope of the described antibodies or antigen-binding fragments. The IgG class is divided in four isotypes: IgG1, IgG2, IgG3 and IgG4 in humans. They share more than 95% homology in the amino acid sequences in the CH1, CH2 and CH3 regions 15 but show major differences in the amino acid composition and structure of the hinge region. The Fc region mediates effector functions, such as antibody-dependent cellular cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP) and complement-dependent cytotoxicity (CDC). In ADCC, the Fc region binds to Fc receptors (FcyRs) on the surface of immune effector cells such as natural killer cells and macrophages, leading to the lysis of the targeted cells. In CDC, 20 the antibodies mediate targeted cell killing by triggering the complement cascade at the cell surface. In ADCP, the antibody mediates elimination of antibody-coated target cells by internalization by phagocytic cells, such as macrophages or dendritic cells. The antibodies described herein include antibodies with the described features of the variable domains in combination with any of the IgG isotypes, including modified versions in which the Fc region has been 25 modified to modulate the various effector functions. For many applications of therapeutic antibodies, Fc-mediated effector functions are not desired as they may potentially pose a safety risk due to cell depletion. Modifying effector functions can be achieved by engineering the Fc regions to reduce their binding to FcyRs or the complement factors. The binding of IgG to the activating (FcyRI, FcYRIIa, FcYRIIIa and 30 FcyRIIIb) and inhibitory (FcyRIIb) FcyRs or the first component of complement (C1q) depends on residues located in the hinge region and the CH2 domain. Mutations may be introduced in 2026204725   18 Jun 2026 IgG1, IgG2 and IgG4 to reduce or silence Fc-mediated effector functions. The antibodies described herein may include these modifications. In some embodiments, the anti-CD3, the anti-PSMA, the anti-CD33, and / or the anti-IL1RAP antibodies comprise an engineered Fc region having one or more of the following 5 properties: (a) reduced effector function when compared to the parental Fc; (b) reduced affinity to FcyRI, FcYRIIa, FcYRIIb, FcYRIIIb and / or FcYRIIIa; (c) reduced affinity to FcyRI; (d) reduced affinity to FcYRIIa; (e) reduced affinity to FcYRIIIb; or (f) reduced affinity to FcYRIIIa. In some embodiments, the anti-CD3, the anti-PSMA, the anti-CD33, and / or the anti-IL1RAP antibodies are, e.g., IgG1, IgG2, IgG3, or IgG4 isotypes. In some embodiments 10 wherein the antibody has an IgG4 isotype, the antibody contains S228P, F234A, and L235A substitutions in its Fc region when compared to the wild-type IgG4. In some embodiments wherein the antibody has an IgG1 isotype, the antibody contains L234A, and L235A substitutions in its Fc region. The antibodies described herein may include these modifications. In some embodiments, the anti-CD3, the anti-PSMA, the anti-CD33, and / or the anti- 15 IL1RAP antibodies are an IgG4 isotype, optionally comprising a heavy chain substitution S228P. In some embodiments, the anti-CD3, the anti-PSMA, the anti-CD33, and / or the anti-IL1RAP antibodies are an IgG1 isotype, optionally comprising heavy chain substitutions L234A, G237A, P238S, H268A, A330S and P331S when compared to the wild type IgG1. In some embodiments, the anti-CD3, the anti-PSMA, the anti-CD33, and / or the anti- 20 IL1RAP antibodies are an IgG2 isotype, optionally comprising heavy chain substitutions L234A, G237A, P238S, H268A, V309L, A330S and P331S when compared to the wild type IgG2. Wild-type IgG4 ASTKGPSVFPLAPCSRSTSESTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPA VLQSSGLYSLSSVVTVPSSSLGTKTYTCNVDHKPSNTKVDKRVESKYGPPCPSCPAPEFL 25 GGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWYVDGVEVHNAKTKPREE QFNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQPREPQVYTLPP SQEEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSRLTV DKSRWQEGNVFSCSVMHEALHNHYTQKSLSLSLGK (SEQ ID NO: 602) 30 Wild-type IgG1 ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSS 2026204725   18 Jun 2026 GLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGG PSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQY NSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSR DELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDK 5 SRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK (SEQ ID NO: 601) Wild-type IgG2 ASTKGPSVFPLAPCSRSTSESTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSS GLYSLSSVVTVPSSNFGTQTYTCNVDHKPSNTKVDKTVERKCCVECPPCPAPPVAGPSV 10 FLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVQFNWYVDGVEVHNAKTKPREEQFNST FRVVSVLTVVHQDWLNGKEYKCKVSNKGLPAPIEKTISKTKGQPREPQVYTLPPSREEM TKNQVSLTCLVKGFYPSDISVEWESNGQPENNYKTTPPMLDSDGSFFLYSKLTVDKSRW QQGNVFSCSVMHEALHNHYTQKSLSLSPGK (SEQ ID NO: 711) 15 In certain embodiments, labelled anti-CD3, anti-PSMA, anti-CD33, and / or anti-IL1RAP antibodies are provided. Exemplary labels or moieties that are detected directly (e.g., fluorescent, chromophoric, electron-dense, chemiluminescent, and radioactive labels) and labels and moieties (e.g., enzymes or ligands) that are detected indirectly (e.g., through enzymatic reaction or molecular interaction). Exemplary labels include radiolabels (e.g., 32P, 14C, 111I, 125I, 20 3H, 131I), fluorescent labels (such as DyLight® 649), epitope tags, biotin, chromophore labels, ECL labels, or enzymes. More specifically, the described labels include ruthenium, 111In-DOTA, 111In- diethylenetriaminepentaacetic acid (DTPA), horseradish peroxidase, alkaline phosphatase and beta-galactosidase, poly-histidine (HIS tag), acridine dyes, cyanine dyes, fluorone dyes, oxazin dyes, phenanthridine dyes, rhodamine dyes, Alexafluor® dyes, and the like. 25 In addition to the described anti-CD3, anti-PSMA, anti-CD33, and / or anti-IL1RAP antibodies and antigen-binding fragments, also provided are polynucleotide sequences capable of encoding the described antibodies and antigen-binding fragments. Vectors comprising the described polynucleotides are also provided, as are cells expressing the anti-CD3, anti-PSMA, anti-CD33, and / or anti-IL1RAP antibodies or antigen-binding fragments provided herein. Also 30 described are cells capable of expressing the disclosed vectors. These cells may be mammalian cells (such as 293F cells, CHO cells), insect cells (such as Sf7 cells), yeast cells, plant cells, or 2026204725   18 Jun 2026 bacteria cells (such as E. coli). The described antibodies may also be produced by hybridoma cells. Generation of Monospecific Antibodies In some embodiments, the anti-CD3, the anti-PSMA, the anti-CD33, the anti-TMEFF2, 5 and / or the anti-IL1RAP antibodies of the invention are human. In some embodiments, , the anti-CD3, the anti-PSMA, the anti-CD33, the anti-TMEFF2, and / or the anti-IL1RAP antibodies of the invention are humanized. Monospecific antibodies of the invention described herein (e.g. the anti-CD3, the anti-PSMA, the anti-CD33, the anti-TMEFF2, and / or the anti-IL1RAP antibodies ) may be generated 10 using various technologies. For example, the hybridoma method of Kohler and Milstein, Nature 256:495, 1975 may be used to generate monoclonal antibodies. In the hybridoma method, a mouse or other host animal, such as a hamster, rat or chicken, is immunized with human, chimpanzee, or macaque PSMA, CD33, IL1RAP, TMEFF2, or CD3 or fragments of PSMA, CD33, IL1RAP, TMEFF2, or CD3, such as the extracellular domain of PSMA, CD33, IL1RAP, 15 TMEFF2, or CD3, followed by fusion of spleen cells from immunized animals with myeloma cells using standard methods to form hybridoma cells (Goding, Monoclonal Antibodies: Principles and Practice, pp.59-103 (Academic Press, 1986)). Colonies arising from single immortalized hybridoma cells are screened for production of antibodies with desired properties, such as specificity of binding, cross-reactivity or lack thereof, and affinity for the antigen. 20 Various host animals may be used to produce the anti-CD3, the anti-PSMA, the anti-CD33, TMEFF2, and / or the anti-IL1RAP antibodies of the invention described herein. For example, Balb / c mice may be used to generate mouse anti-human PSMA antibodies. The antibodies made in Balb / c mice and other non-human animals may be humanized using various technologies to generate more human-like sequences. 25 Exemplary humanization techniques including selection of human acceptor frameworks are known and include CDR grafting (U.S. Patent No. 5,225,539), SDR grafting (U.S. Patent No. 6,818,749), Resurfacing (Padlan, (1991) Mol Immunol 28:489-499), Specificity Determining Residues Resurfacing (U.S. Patent Publ. No. 2010 / 0261620), human framework adaptation (U.S. Patent No. 8,748,356) or superhumanization (U.S. Patent No. 7,709, 226). In these methods, 30 CDRs of parental antibodies are transferred onto human frameworks that may be selected based 2026204725   18 Jun 2026 on their overall homology to the parental frameworks, based on similarity in CDR length, or canonical structure identity, or a combination thereof. Humanized antibodies may be further optimized to improve their selectivity or affinity to a desired antigen by incorporating altered framework support residues to preserve binding 5 affinity (backmutations) by techniques such as those described in Int. Patent Publ. Nos. WO1090 / 007861 and WO1992 / 22653, or by introducing variation at any of the CDRs for example to improve affinity of the antibody. Transgenic animals, such as mice or rat carrying human immunoglobulin (Ig) loci in their genome may be used to generate human antibodies against a target protein, and are described in 10 for example U.S. Patent No. 6,150,584, Int. Patent Publ. No. WO99 / 45962, Int. Patent Publ. Nos. WO2002 / 066630, WO2002 / 43478, WO2002 / 043478 and WO1990 / 04036, Lonberg et al (1994) Nature 368:856-9; Green et al (1994) Nature Genet. 7:13-21; Green & Jakobovits (1998) Exp. Med. 188:483-95; Lonberg and Huszar (1995) Int Rev Immunol 13:65-93; Bruggemann et al., (1991) Eur J Immunol 21:1323- 1326; Fishwild et al., (1996) Nat Biotechnol 14:845-851; 15 Mendez et al., (1997) Nat Genet 15:146-156; Green (1999) J Immunol Methods 231:11-23; Yang et al., (1999) Cancer Res 59:1236-1243; Bruggemann and Taussig (1997) Curr Opin Biotechnol 8:455-458. The endogenous immunoglobulin loci in such animal may be disrupted or deleted, and at least one complete or partial human immunoglobulin locus may be inserted into the genome of the animal using homologous or non-homologous recombination, using 20 transchromosomes, or using minigenes. Companies such as Regeneron (http: / / _www_regeneron_com), Harbour Antibodies (http: / / _www_harbourantibodies_com), Open Monoclonal Technology, Inc. (OMT) (http: / / _www_omtinc_net), KyMab (http: / / _www_kymab_com), Trianni (http: / / _www.trianni_com) and Ablexis (http: / / _www_ablexis_com) may be engaged to provide human antibodies directed against a 25 selected antigen using technologies as described above. Human antibodies may be selected from a phage display library, where the phage is engineered to express human immunoglobulins or portions thereof such as Fabs, single chain antibodies (scFv), or unpaired or paired antibody variable regions (Knappik et al., (2000) J Mol Biol 296:57-86; Krebs et al., (2001) J Immunol Meth 254:67-84; Vaughan et al., (1996) Nature 30 Biotechnology 14:309-314; Sheets et al., (1998) PITAS (USA) 95:6157-6162; Hoogenboom and Winter (1991) J Mol Biol 227:381; Marks et al., (1991) J Mol Biol 222:581). The antibodies of 2026204725   18 Jun 2026 the invention may be isolated for example from phage display library expressing antibody heavy and light chain variable regions as fusion proteins with bacteriophage pIX coat protein as described in Shi et al., (2010) J Mol Biol 397:385-96, and Int. Patent Publ. No. WO09 / 085462). The libraries may be screened for phage binding to human and / or cyno PSMA, CD33, IL1RAP, 5 TMEFF2, or CD3 and the obtained positive clones may be further characterized, the Fabs isolated from the clone lysates, and expressed as full length IgGs. Such phage display methods for isolating human antibodies are described in for example: U.S. Patent Nos. 5,223,409, 5,403,484, 5,571,698, 5,427,908, 5, 580,717, 5,969,108, 6,172,197, 5,885,793; 6,521,404; 6,544,731; 6,555,313; 6,582,915 and 6,593,081. 10 Preparation of immunogenic antigens and monoclonal antibody production may be performed using any suitable technique, such as recombinant protein production. The immunogenic antigens may be administered to an animal in the form of purified protein, or protein mixtures including whole cells or cell or tissue extracts, or the antigen may be formed de novo in the animal’s body from nucleic acids encoding said antigen or a portion thereof. 15 Generation and use of bispecific and multispecific CD3 antibodies The invention provides bispecific and multispecific antibodies comprising a first domain that specifically binds CD3 and a second domain that specifically binds a second antigen. The second antigen may be a tumor associated antigen (TAA) or an antigen on pathogenic cells. Exemplary anti-CD3 antibodies that may be used to engineer bispecific and multispecific 20 antibodies comprising a first domain that specifically binds CD3 and a second domain that specifically binds a second antigen include CD3 antibodies comprising the Vh / Vl sequences and heavy / light chain CDRs shown in Table 7A and 7B, respecitvely, and the engineered variants thereof described in Table 10 and Table 11, and accompanying text. For example, the CDRs and / or the VH / VL domains of the CD3 antibodies CD3B312, CD3B313, CD3B314, CD3B315, 25 CD3B316, CD3B317, CD3B337, CD3B373, CD3B376, CD3B389, CD3B450, and CD3B467 described herein may be used to generate bispecific and multispecific antibodies comprising a first domain that specifically binds CD3 and a second domain that specifically binds a second antigen. 2026204725   18 Jun 2026 The herein described anti-CD3 antibody CDRs and / or the VH / VL domains may be incorporated into bispecific antibodies comprising a first domain that specifically binds CD3 and a second domain that specifically binds a second antigen. The herein described anti-CD3 antibody CDRs and / or the VH / VL domains may be 5 incorporated into bispecific antibodies comprising PSMA binding VH / VL domains described herein and in Table 23. The herein described anti-CD3 antibodies and / or the VH / VL domains may be incorporated into bispecific antibodies comprising IL1RAP binding VH / VL domains described herein and in Table 30. The herein described anti-CD3 antibody CDRs and / or the VH / VL domains may be incorporated into bispecific antibodies comprising CD33 binding 10 VH / VL domains described herein and in Table 38. For example, the VH / VL domains of the PSMA antibodies PSMB119, PSMB120, PSMB121, PSMB122, PSMB123, PSMB87, PSMB126, PSMB127, PSMB128, PSMB129, PSMB130, PSMB120, PSMB121, PSMB122, PSMB123, PSMB127, PSMB128, PSMB130, PSMB344, PSMB345, PSMB346, PSMB347, PSMB349, PSMB358, PSMB359, PSMB360, PSMB361, PSMB362, PSMB363, and PSMB365 15 described herein may be used to generate bispecific PSMA*CD3 antibodies. Exemplary TAAs are PSMA, CD33, TMEFF2, and IL1RAP. The exemplary multispecific PSMA*CD3, CD33*CD3, TMEFF2,xCD3, and IL1RAP*CD3 antibodies provided herein have a first domain that specifically bind CD3 and a second domain that specifically binds PSMA, CD33, TMEFF2, or IL1RAP. Exemplary anti-PSMA antibodies that 20 may be used to engineer bispecific PSMA*CD3 molecules are those described herein, which may comprise heavy and light chain sequences including but not limited to the heavy and light chain sequences listed in Table 23. Exemplary anti-IL1RAP antibodies that may be used to engineer bispecific IL1RAP*CD3 molecules are those described herein, which may comprise heavy and light chain variable region sequences including but not limited to the heavy and light 25 chain variable region sequences provided in Table 35. Exemplary anti-CD33 antibodies that may be used to engineer bispecific CD33*CD3 molecules are those described herein, which may comprise heavy and light chain variable region sequences including but not limited to the heavy and light chain variable region sequences provided in Table 43. Exemplary anti-TMEFF2 antibodies that may be used to engineer bispecific TMEFF2*CD3 molecules are those described 30 herein, which may comprise heavy and light chain variable region sequences including but not limited to the heavy and light chain variable region sequences provided in Tables 59, 66-68. 2026204725   18 Jun 2026 The generated bispecific antibodies may be tested for their binding to CD3 and / or the second antigen and / or for their desired functional characteristics, such as T-cell mediated killing of cells that express the second antigen. The bispecific antibodies provided herein include antibodies having a full-length 5 antibody structure. “Fab-arm” or “half molecule” refers to one heavy chain-light chain pair that specifically binds an antigen. Full length bispecific antibodies as described herein may be generated for example using Fab arm exchange (or half molecule exchange) between two monospecific bivalent antibodies by 10 introducing substitutions at the heavy chain CH3 interface in each half molecule to favor heterodimer formation of two antibody half molecules having distinct specificity either in vitro in cell-free environment or using co-expression. The Fab arm exchange reaction is the result of a disulfide-bond isomerization reaction and dissociation-association of CH3 domains. The heavy chain disulfide bonds in the hinge regions of the parental monospecific antibodies are reduced. 15 The resulting free cysteines of one of the parental monospecific antibodies form an inter heavychain disulfide bond with cysteine residues of a second parental monospecific antibody molecule and simultaneously CH3 domains of the parental antibodies release and reform by dissociationassociation. The CH3 domains of the Fab arms may be engineered to favor heterodimerization over homodimerization. The resulting product is a bispecific antibody having two Fab arms or 20 half molecules, which each bind a distinct epitope, i.e. an epitope on CD3 and an epitope on the second antigen. “Homodimerization” refers to an interaction of two heavy chains having identical CH3 amino acid sequences. “Homodimer” refers to an antibody having two heavy chains with identical CH3 amino acid sequences. 25 “Heterodimerization” refers to an interaction of two heavy chains having non-identical CH3 amino acid sequences. “Heterodimer” refers to an antibody having two heavy chains with non-identical CH3 amino acid sequences. In some embodiments, the bispecific antibodies include designs such as the Triomab / Quadroma (Trion Pharma / Fresenius Biotech), Knob-in-Hole (Genentech), CrossMAbs 30 (Roche) and the electrostatically-matched (Chugai, Amgen, NovoNordisk, Oncomed), the LUZ- 2026204725   18 Jun 2026 Y (Genentech), the Strand Exchange Engineered Domain body (SEEDbody)(EMD Serono), the Biclonic (Merus) and the DuoBody® Technology (Genmab A / S). The Triomab quadroma technology may be used to generate full-length bispecific antibodies, incorporating the VH and VL of the anti-CD3 antibodies of the invention. Triomab 5 technology promotes Fab arm exchange between two parental chimeric antibodies, one parental mAb having IgG2a and the second parental mAb having rat IgG2b constant regions, yielding chimeric bispecific antibodies. The “knob-in-hole” strategy (see, e.g., Intl. Publ. No. WO 2006 / 028936) may be used to generate full-length bispecific antibodies. Briefly, selected amino acids forming the interface of 10 the CH3 domains in human IgG can be mutated at positions affecting CH3 domain interactions to promote heterodimer formation. An amino acid with a small side chain (hole) is introduced into a heavy chain of an antibody specifically binding a first antigen and an amino acid with a large side chain (knob) is introduced into a heavy chain of an antibody specifically binding a second antigen. After co-expression of the two antibodies, a heterodimer is formed as a result of 15 the preferential interaction of the heavy chain with a “hole” with the heavy chain with a “knob”. Exemplary CH3 substitution pairs forming a knob and a hole are (expressed as modified position in the first CH3 domain of the first heavy chain / modified position in the second CH3 domain of the second heavy chain): T366Y / F405A, T366W / F405W, F405W / Y407A, T394W / Y407T, T394S / Y407A, T366W / T394S, F405W / T394S and T366W / T366S_L368A_Y407V. 20 The CrossMAb technology may be used to generate full-length bispecific antibodies. CrossMAbs, in addition to utilizing the “knob-in-hole” strategy to promoter Fab arm exchange, have in one of the half arms the CH1 and the CL domains exchanged to ensure correct light chain pairing of the resulting bispecific antibody (see e.g. U.S. Patent No. 8,242,247). Other cross-over strategies may be used to generate full length bispecific antibodies by 25 exchanging variable or constant, or both domains between the heavy chain and the light chain or within the heavy chain in the bispecific antibodies, either in one or both arms. These exchanges include for example VH-CH1 with VL-CL, VH with VL, CH3 with CL and CH3 with CH1 as described in Int. Patent Publ. Nos. WO2009 / 080254, WO2009 / 080251, WO2009 / 018386 and WO2009 / 080252. 30 Other strategies such as promoting heavy chain heterodimerization using electrostatic interactions by substituting positively charged residues at one CH3 surface and negatively 2026204725   18 Jun 2026 charged residues at a second CH3 surface may be used, as described in US Patent Publ. No. US2010 / 0015133; US Patent Publ. No. US2009 / 0182127; US Patent Publ. No. US2010 / 028637 or US Patent Publ. No. US2011 / 0123532. In other strategies, heterodimerization may be promoted by following substitutions (expressed as modified position in the first CH3 domain of 5 the first heavy chain / modified position in the second CH3 domain of the second heavy chain): L351Y_F405A_Y407V / T394W, T366I_K392M_T394W / F405A_Y407V, T366L_K392M_T394W / F405A_Y407V, L351Y_Y407A / T366A_K409F, L351Y_Y407A / T366V_K409F, Y407A / T366A_K409F, or T350V_L351Y_F405A_Y407V / T350V_T366L_K392L_T394W as described in U.S. Patent 10 Publ. No. US2012 / 0149876 or U.S. Patent Publ. No. US2013 / 0195849. LUZ-Y technology may be utilized to generate bispecific antibodies. In this technology, a leucine zipper is added into the C terminus of the CH3 domains to drive the heterodimer assembly from parental mAbs that is removed post-purification as described in Wranik et al., (2012) J Biol Chem 287(52): 42221-9. 15 SEEDbody technology may be utilized to generate bispecific antibodies. SEEDbodies have, in their constant domains, select IgG residues substituted with IgA residues to promote heterodimerization as described in U.S. Patent No. US20070287170. The bispecific antibodies described herein may be generated in vitro in a cell-free environment by introducing asymmetrical mutations in the CH3 regions of two monospecific 20 homodimeric antibodies and forming the bispecific heterodimeric antibody from two parent monospecific homodimeric antibodies in reducing conditions to allow disulfide bond isomerization according to methods described in Int. Patent Publ. No. WO2011 / 131746). In the methods, the first monospecific bivalent antibody (i.e., the antibody that specifically binds the second antigen; e.g., anti-PSMA, anti-CD33, anti-TMEFF2 or anti-IL1RAP antibody) and the 25 second monospecific bivalent antibody (i.e., anti-CD3 antibody) are engineered to have certain substitutions at the CH3 domain that promoter heterodimer stability; the antibodies are incubated together under reducing conditions sufficient to allow the cysteines in the hinge region to undergo disulfide bond isomerization; thereby generating the bispecific antibody by Fab arm exchange. The incubation conditions are restored to non-reducing. Exemplary reducing agents 30 that may be used are 2- mercaptoethylamine (2-MEA), dithiothreitol (DTT), dithioerythritol (DTE), glutathione, tris(2-carboxyethyl)phosphine (TCEP), L-cysteine and beta- 2026204725   18 Jun 2026 mercaptoethanol. For example, incubation for at least 90 min at a temperature of at least 20°C in the presence of at least 25 mM 2-MEA or in the presence of at least 0.5 mM dithiothreitol at a pH of from 5-8, for example at pH of 7.0 or at pH of 7.4 may be used. In some embodiments described herein, the bispecific antibody comprising a first domain 5 that specifically binds CD3 and a second domain that specifically binds a second antigen comprises at least one substitution in an antibody CH3 constant domain. In some embodiments described herein, the at least one substitution in the antibody CH3 constant domain is K409R, F405L or F405L and R409K substitution, wherein residue numbering is according to the EU Index. 10 Antibody domains and numbering are well known. “Asymmetrical” refers to nonidentical substitutions in the two CH3 domains in two separate heavy chains in an antibody. An IgG1 CH3 region typically consists of residues 341-446 on IgG1 (residue numbering according to the EU index). In some embodiments described herein, the bispecific antibody is an IgG1 isotype and 15 comprises a F405L substitution in an antibody first heavy chain (HC1) and a K409R substitution in an antibody second heavy chain (HC2) when compared to the wild-type IgG1. In some embodiments described herein, the bispecific antibody is an IgG1 isotype and comprises a K409R substitution in an antibody first heavy chain (HC1) and a F405L substitution in an antibody second heavy chain (HC2) when compared to the wild-type IgG1. 20 In some embodiments described herein, the bispecific antibody is an IgG4 isotype and comprises a S228P substitution in the HC1 and S228P, F405L and R409K substitutions in the HC2 when compared to the wild-type IgG4. In some embodiments described herein, the bispecific antibody is an IgG4 isotype and comprises S228P, F405L and R409K substitutions in the HC1 and a S228P substitution in the 25 HC2 when compared to the wild-type IgG4. In some embodiments described herein, the bispecific antibody is an IgG4 isotype and comprises S228P, F234A and L235A substitutions in the HC1 and S228P, F234A, L235A, F405L and R409K substitutions in the HC2 when compared to the wild-type IgG4. In some embodiments described herein, the bispecific antibody is an IgG4 isotype and 30 comprises S228P, F234A, L235A, F405L and R409K substitutions in the HC1 and a S228P, F234A and L235A substitutions in the HC2 when compared to the wild-type IgG4. 2026204725   18 Jun 2026 In some embodiments described herein, the bispecific antibody of the invention comprises at least one, two, three, four, five, six, seven or eight asymmetrical substitutions in the HC1 and the HC2 at residue positions 350, 366, 368, 370, 399, 405, 407 or 409, when residue numbering is according to the EU index. 5 In some embodiments described herein, the bispecific antibody of the invention comprises at least one, two, three or four asymmetrical substitutions in the HC1 and the HC2 at residue positions 350, 370, 405 or 409, when residue numbering is according to the EU index. In some embodiments described herein, the bispecific antibody of the invention comprises at least one asymmetrical substitution in the HC1 and the HC2 at residue positions 10 405 or 409, when residue numbering is according to the EU index. Substitutions are typically made at the DNA level to a molecule such as the constant domain of the antibody using standard methods. The antibodies of the invention may be engineered into various well-known antibody forms. 15 In some embodiments, the bispecific antibody of the present invention is a cross-body. In some embodiments, the bispecific antibodies of the invention include recombinant IgG-like dual targeting molecules, wherein the two sides of the molecule each contain the Fab fragment or part of the Fab fragment of at least two different antibodies; IgG fusion molecules, wherein full length IgG antibodies are fused to an extra Fab fragment or parts of Fab fragment; 20 Fc fusion molecules, wherein single chain Fv molecules or stabilized diabodies are fused to heavy-chain constant-domains, Fc-regions or parts thereof; Fab fusion molecules, wherein different Fab-fragments are fused together; ScFv- and diabody-based and heavy chain antibodies (e.g., domain antibodies, nanobodies) wherein different single chain Fv molecules or different diabodies or different heavy-chain antibodies (e.g. domain antibodies, nanobodies) are fused to 25 each other or to another protein or carrier molecule. In some embodiments, recombinant IgG-like dual targeting molecules include Dual Targeting (DT)-Ig (GSK / Domantis), Two-in-one Antibody (Genentech) and mAb2 (F-Star). In some embodiments, IgG fusion molecules include Dual Variable Domain (DVD)-Ig (Abbott), Ts2Ab (MedImmune / AZ) and BsAb (Zymogenetics), HERCULES (Biogen Idec) and 30 TvAb (Roche). 2026204725   18 Jun 2026 In some embodiments, Fc fusion molecules include to ScFv / Fc Fusions (Academic Institution), SCORPION (Emergent BioSolutions / Trubion, Zymogenetics / BMS) and Dual Affinity Retargeting Technology (Fc-DART) (MacroGenics). In some embodiments, Fab fusion bispecific antibodies include F(ab)2 5 (Medarex / AMGEN), Dual-Action or Bis-Fab (Genentech), Dock-and-Lock (DNL) (ImmunoMedics), Bivalent Bispecific (Biotecnol) and Fab-Fv (UCB-Celltech). ScFv-, diabody-based and domain antibodies include Bispecific T Cell Engager (BITE) (Micromet), Tandem Diabody (Tandab) (Affimed), Dual Affinity Retargeting Technology (DART) (MacroGenics), Single-chain Diabody (Academic), TCR-like Antibodies (AIT, ReceptorLogics), Human Serum 10 Albumin ScFv Fusion (Merrimack) and COMBODY (Epigen Biotech), dual targeting nanobodies (Ablynx), dual targeting heavy chain only domain antibodies. Various formats of bispecific antibodies have been described, for example in Chames and Baty (2009) Curr Opin Drug Disc Dev 12: 276 and in Nunez-Prado et al., (2015) Drug Discovery Today 20(5):588-594. Table 2 summarizes exemplary monoclonal antibodies described herein that can be used 15 to generate the bispecific antibodies of the invention. Table 2. Exemplary monoclonal antibodies that can be used to generate the bispecific antibodies of the invention First Domain Second Domain anti-CD3 anti-PSMA anti-CD33 anti-ILlRAP CD3B312 PSMB87 C33B760 IAPB3 CD3B313 PSMB119 C33B777 IAPB9 CD3B314 PSMB120 C33B778 IAPB17 CD3B315 PSMB121 C33B782 IAPB23 CD3B316 PSMB122 C33B792 IAPB25 CD3B317 PSMB123 C33B799 IAPB29 CD3B337 PSMB124 C33B806 IAPB38 CD3B373 PSMB126 C33B830 IAPB47 CD3B376 PSMB127 C33B836 IAPB55 CD3B389 PSMB129 C33B903 IAPB57 CD3B450 CD3B467 PSMB130 C33B904 IAPB61 PSMB344 2026204725   18 Jun 2026 PSMB345 C33B905 IAPB62 PSMB346 C33B907 IAPB63 PSMB347 C33B908 IAPB64 PSMB349 PSMB358 PSMB359 PSMB360 PSMB361 PSMB362 PSMB363 PSMB365 IAPB65 Exemplary anti-TMEFF2 antibodies that may be used to engineer bispecific TMEFF2*CD3 molecules are those described herein, which may comprise heavy and light chain variable region sequences including but not limited to the heavy and light chain variable region sequences provided in Tables 59, 66-68. 5 In some embodiments, the anti-CD3 antibody is a multispecific antibody, for example a bispecific antibody comprising a first domain that specifically binds CD3 and a second domain that specifically binds a second antigen. In some embodiments, the second, or target, antigen is a cell surface antigen that is expressed on a target cell other than an immune effector cell. In some embodiments, the second antigen is a TAA. Exemplary TAAs are PSMA, CD33, TMEFF2, and 10 IL1RAP. The invention provides a bispecific antibody comprising a first domain that specifically binds CD3 and a second domain that specifically binds a second antigen. In some embodiments, the first domain comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID NOs:662, 663, 664, 671, 673, and 690, 15 respectively. In some embodiments, the first domain comprises the VH and VL of SEQ ID NOs: 652 and 661, respectively. In some embodiments, the first domain comprises the HC and LC of SEQ ID NOs: 640 and 676, respectively. In some embodiments, the first domain comprises the VH and VL of SEQ ID NOs: 657 and 678, respectively. In some embodiments, the first domain comprises the HC and LC of SEQ ID NOs: 675 and 677, respectively. 2026204725   18 Jun 2026 In some embodiments, the first domain comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID NOs:662, 663, 664, 773, 673, and 690, respectively. In some embodiments, the first domain comprises the VH and VL of SEQ ID NOs:657 and 678, respectively. In some embodiments, the first domain comprises the HC and 5 LC of SEQ ID NOs:675 and 677, respectively. The invention also provides the bispecific antibody comprising a first domain that specifically binds CD3 and a second domain that specifically binds a second antigen of the invention for use in therapy. The invention also provides the bispecific antibody comprising a first domain that 10 specifically binds CD3 and a second domain that specifically binds a second antigen of the invention for use in treating a cell proliferative disporder. The invention also provides the bispecific antibody comprising a first domain that specifically binds CD3 and a second domain that specifically binds a second antigen of the invention for use in treating cancer. 15 The invention also provides the bispecific antibody comprising a first domain that specifically binds CD3 and a second domain that specifically binds a second antigen of the invention for use in treating an autoimmune disease. The invention also provides the bispecific antibody comprising a first domain that specifically binds CD3 and a second domain that specifically binds a second antigen of the 20 invention for use in the mantufacture of a medicament for treating cancer. The invention also provides the bispecific antibody comprising a first domain that specifically binds CD3 and a second domain that specifically binds a second antigen of the invention for use in the mantufacture of a medicament for treating an autoimmune disorder. A further aspect of the invention is a method of treating a cell proliferative disorder or an 25 autoimmune disorder in a subject in need thereof, the method comprising administering to the subject a therapeutically effective amount of the anti-CD3 antibody of the invention. In some embodiments, the anti-CD3 antibody or the bispecific antibody comprising a first domain that specifically binds CD3 and a second domain that specifically binds a second antigen of the invention is administered to the subject in a dosage of about 0.01 mg / kg to about 10 mg / kg. In 2026204725   18 Jun 2026 some embodiments, the anti-CD3 antibody or the bispecific antibody comprising a first domain that specifically binds CD3 and a second domain that specifically binds a second antigen of the invention is administered to the subject in a dosage of about 0.1 mg / kg to about 10 mg / kg. In some embodiments, the anti-CD3 antibody or the bispecific antibody comprising a first domain 5 that specifically binds CD3 and a second domain that specifically binds a second antigen of the invention is administered to the subject in a dosage of about 1 mg / kg. In some embodiments, the anti-CD3 antibodyor the bispecific antibody comprising a first domain that specifically binds CD3 and a second domain that specifically binds a second antigen of the invention is administered subcutaneously, intravenously, intramuscularly, topically, orally, transdermally, 10 intraperitoneally, intraorbitally, by implantation, by inhalation, intrathecally, intraventricularly, or intranasally. In some embodiments, the anti-CD3 antibody or the bispecific antibody comprising a first domain that specifically binds CD3 and a second domain that specifically binds a second antigen of the invention is administered subcutaneously. In some embodiments, the anti-CD3 antibody or the bispecific antibody comprising a first domain that specifically binds 15 CD3 and a second domain that specifically binds a second antigen of the invention is administered intravenously. In any of the preceding uses or methods, the cell proliferative disorder is cancer. In some embodiments, the cancer is selected from the group consisting of esophageal cancer, stomach cancer, small intestine cancer, large intestine cancer, colorectal cancer, breast cancer, non-small 20 cell lung cancer, non-Hodgkin's lymphoma (NHL), B cell lymphoma, B cell leukemia, multiple myeloma, renal cancer, prostate cancer, liver cancer, head and neck cancer, melanoma, ovarian cancer, mesothelioma, glioblastoma, germinal-center B-cell-like (GCB) DLBCL, activated B-cell-like (ABC) DLBCL, follicular lymphoma (FL), mantle cell lymphoma (MCL), acute myeloid leukemia (AML), chronic lymphoid leukemia (CLL), marginal zone lymphoma (MZL), 25 small lymphocytic leukemia (SLL), lymphoplasmacytic lymphoma (LL), Waldenstrom macroglobulinemia (WM), central nervous system lymphoma (CNSL), Burkitt's lymphoma (BL), B-cell prolymphocytic leukemia, Splenic marginal zone lymphoma, Hairy cell leukemia, Splenic lymphoma / leukemia, unclassifiable, Splenic diffuse red pulp small B-cell lymphoma, Hairy cell leukemia variant, Waldenstrom macroglobulinemia, Heavy chain diseases, Plasma cell 30 myeloma, Solitary plasmacytoma of bone, Extraosseous plasmacytoma, Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma), Nodal marginal 2026204725   18 Jun 2026 zone lymphoma, Pediatric nodal marginal zone lymphoma, Pediatric follicular lymphoma, Primary cutaneous follicle centre lymphoma, T-cell / histiocyte rich large B-cell lymphoma, Primary DLBCL of the CNS, Primary cutaneous DLBCL, leg type, EBV-positive DLBCL of the elderly, DLBCL associated with chronic inflammation, Lymphomatoid granulomatosis, Primary 5 mediastinal (thymic) large B-cell lymphoma. Intravascular large B-cell lymphoma, ALK-positive large B-cell lymphoma, Plasmablastic lymphoma, Large B-cell lymphoma arising in HHV8-associated multicentric Castleman disease, Primary effusion lymphoma: B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and Burkitt lymphoma, and B-cell lymphoma, unclassifiable, with features intermediate between 10 diffuse large B-cell lymphoma, classical Hodgkin lymphoma and light chain amyloidosis. In some embodiments, the cancer is esophageal cancer. In some embodiments, the cancer is an adenocarcinoma, for example, a metastatic adenocarcinoma (e.g., a colorectal adenocarcinoma, a gastric adenocarcinoma, or a pancreatic adenocarcinoma). In any of the preceding uses or methods, the autoimmune disorder can be selected from 15 the group consisting of rheumatoid arthritis, juvenile rheumatoid arthritis, systemic lupus erythematosus (SLE), Wegener's disease, inflammatory bowel disease, idiopathic thrombocytopenic purpura (ITP), thrombotic thrombocytopenic purpura (TTP), autoimmune thrombocytopenia, multiple sclerosis, psoriasis, IgA nephropathy, IgM polyneuropathies, myasthenia gravis, vasculitis, diabetes mellitus, Reynaud's syndrome, Sjorgen's syndrome, 20 glomerulonephritis, Neuromyelitis Optica (NMO), and IgG neuropathy. In another aspect, the invention features a kit comprising: (a) a composition comprising any one of the preceding anti-CD3 antibodies or the bispecific antibodies comprising a first domain that specifically binds CD3 and a second domain that specifically binds a second antigen of the invention and (b) a package insert comprising instructions for administering the 25 composition to a subject to treat or delay progression of a cell proliferative disorder. The term "package insert" is used to refer to instructions customarily included in commercial packages of therapeutic products, that contain information about the indications, usage, dosage, administration, combination therapy, contraindications and / or warnings concerning the use of such therapeutic products. 30 In any of the preceding uses or methods, the subject can be a human. 2026204725   18 Jun 2026 Polynucleotides, Vectors, and Host Cells Also disclosed are isolated polynucleotides that encode the anti-CD3 antibodies of the invention or the bispecific antibodies comprising a first domain that specifically binds CD3 and a second domain that specifically binds a second antigen of the invention. The isolated 5 polynucleotides capable of encoding the variable domains provided herein may be included on the same, or different, vectors to produce antibodies or antigen-binding fragments of the invention. In some embodiments, the polynucleotides of the invention include a polynucleotide encoding a leader sequence. Any leader sequence known in the art may be employed. The 10 polynucleotide encoding the leader sequence may include, a restriction endonuclease cleavage site or a translation initiation site. Also provided are vectors comprising the polynucleotides of the invention. The vectors can be expression vectors. The expression vector may contain one or more additional sequences such as but not limited to regulatory sequences (e.g., promoter, enhancer), a selection marker, 15 and a polyadenylation signal. Vectors for transforming a wide variety of host cells are well known and include, but are not limited to, plasmids, phagemids, cosmids, baculoviruses, bacmids, bacterial artificial chromosomes (BACs), yeast artificial chromosomes (YACs), as well as other bacterial, yeast and viral vectors. Recombinant expression vectors within the scope of the description include synthetic, or 20 cDNA-derived nucleic acid fragments that encode at least one recombinant protein which may be operably linked to suitable regulatory elements. Such regulatory elements may include a transcriptional promoter, sequences encoding suitable mRNA ribosomal binding sites, and sequences that control the termination of transcription and translation. Expression vectors, especially mammalian expression vectors, may also include one or more nontranscribed elements 25 such as an origin of replication, a suitable promoter and enhancer linked to the gene to be expressed, other 5' or 3' flanking nontranscribed sequences, 5' or 3' nontranslated sequences (such as necessary ribosome binding sites), a polyadenylation site, splice donor and acceptor sites, or transcriptional termination sequences. An origin of replication that confers the ability to replicate in a host may also be incorporated. 2026204725   18 Jun 2026 The transcriptional and translational control sequences in expression vectors to be used in transforming vertebrate cells may be provided by viral sources. Exemplary vectors may be constructed as described by Okayama and Berg, 3 Mol. Cell. Biol. 280 (1983). In some embodiments, the antibody- or antigen-binding fragment-coding sequence is 5 placed under control of a powerful constitutive promoter, such as the promoters for the following genes: hypoxanthine phosphoribosyl transferase (HPRT), adenosine deaminase, pyruvate kinase, beta-actin, human myosin, human hemoglobin, human muscle creatine, and others. In addition, many viral promoters function constitutively in eukaryotic cells and are suitable for use with the described embodiments. Such viral promoters include without limitation, Cytomegalovirus 10 (CMV) immediate early promoter, the early and late promoters of SV40, the Mouse Mammary Tumor Virus (MMTV) promoter, the long terminal repeats (LTRs) of Maloney leukemia virus, Human Immunodeficiency Virus (HIV), Epstein Barr Virus (EBV), Rous Sarcoma Virus (RSV), and other retroviruses, and the thymidine kinase promoter of Herpes Simplex Virus. In one embodiment, the PSMA-specific antibody or antigen-binding fragment thereof coding sequence 15 is placed under control of an inducible promoter such as the metallothionein promoter, tetracycline-inducible promoter, doxycycline-inducible promoter, promoters that contain one or more interferon-stimulated response elements (ISRE) such as protein kinase R 2',5'-oligoadenylate synthetases, Mx genes, ADAR1, and the like. Vectors described herein may contain one or more Internal Ribosome Entry Site(s) 20 (IRES). Inclusion of an IRES sequence into fusion vectors may be beneficial for enhancing expression of some proteins. In some embodiments the vector system will include one or more polyadenylation sites (e.g., SV40), which may be upstream or downstream of any of the aforementioned nucleic acid sequences. Vector components may be contiguously linked, or arranged in a manner that provides optimal spacing for expressing the gene products (i.e., by the 25 introduction of “spacer” nucleotides between the ORFs), or positioned in another way. Regulatory elements, such as the IRES motif, may also be arranged to provide optimal spacing for expression. The vectors may comprise selection markers, which are well known in the art. Selection markers include positive and negative selection markers, for example, antibiotic resistance genes 30 (e.g., neomycin resistance gene, a hygromycin resistance gene, a kanamycin resistance gene, a tetracycline resistance gene, a penicillin resistance gene), glutamate synthase genes, HSV-TK, 2026204725   18 Jun 2026 HSV-TK derivatives for ganciclovir selection, or bacterial purine nucleoside phosphorylase gene for 6-methylpurine selection (Gadi et al., 7 Gene Ther. 1738-1743 (2000)). A nucleic acid sequence encoding a selection marker or the cloning site may be upstream or downstream of a nucleic acid sequence encoding a polypeptide of interest or cloning site. 5 The vectors described herein may be used to transform various cells with the genes encoding the described antibodies or antigen-binding fragments. For example, the vectors may be used to generate anti-CD3, anti-PSMA, anti-CD33, anti-TMEFF2, or anti-IL1RAP antibodies or antigen-binding fragment-producing cells. Thus, the invention also provides a host cell comprising the vectors of the invention. 10 Numerous techniques are known in the art for the introduction of foreign genes into cells and may be used to construct the recombinant cells for purposes of carrying out the described methods, in accordance with the various embodiments described and exemplified herein. The technique used should provide for the stable transfer of the heterologous gene sequence to the host cell, such that the heterologous gene sequence is heritable and expressible by the cell 15 progeny, and so that the necessary development and physiological functions of the recipient cells are not disrupted. Techniques which may be used include but are not limited to chromosome transfer (e.g., cell fusion, chromosome mediated gene transfer, micro cell mediated gene transfer), physical methods (e.g., transfection, spheroplast fusion, microinjection, electroporation, liposome carrier), viral vector transfer (e.g., recombinant DNA viruses, 20 recombinant RNA viruses) and the like (described in Cline, 29 Pharmac. Ther. 69-92 (1985)). Calcium phosphate precipitation and polyethylene glycol (PEG)-induced fusion of bacterial protoplasts with mammalian cells may also be used to transform cells. Cells suitable for use in the expression of the antibodies or antigen-binding fragments described herein are preferably eukaryotic cells, more preferably cells of plant, rodent, or human 25 origin, for example but not limited to NSO, CHO, CHOK1, perC.6, Tk-ts13, BHK, HEK293 cells, COS-7, T98G, CV-1 / EBNA, L cells, C127, 3T3, HeLa, NS1, Sp2 / 0 myeloma cells, and BHK cell lines, among others. In addition, expression of antibodies may be accomplished using hybridoma cells. Methods for producing hybridomas are well established in the art. Cells transformed with expression vectors of the invention may be selected or screened 30 for recombinant expression of the antibodies or antigen-binding fragments of the invention. Recombinant-positive cells are expanded and screened for subclones exhibiting a desired 2026204725   18 Jun 2026 phenotype, such as high level expression, enhanced growth properties, or the ability to yield proteins with desired biochemical characteristics, for example, due to protein modification or altered post-translational modifications. These phenotypes may be due to inherent properties of a given subclone or to mutation. Mutations may be effected through the use of chemicals, UV- 5 wavelength light, radiation, viruses, insertional mutagens, inhibition of DNA mismatch repair, or a combination of such methods. Pharmaceutical Compositions / Administration The invention also provides for pharmaceutical compositions comprising the antibodies of the invention and a pharmaceutically acceptable carrier. For therapeutic use, the antibodies of 10 the invention may be prepared as pharmaceutical compositions containing an effective amount of the antibody as an active ingredient in a pharmaceutically acceptable carrier. "Carrier" refers to a diluent, adjuvant, excipient, or vehicle with which the antibody of the invention is administered. Such vehicles may be liquids, such as water and oils, including those of petroleum, animal, vegetable or synthetic origin, such as peanut oil, soybean oil, mineral oil, 15 sesame oil and the like. For example, 0.4% saline and 0.3% glycine may be used. These solutions are sterile and generally free of particulate matter. They may be sterilized by conventional, well-known sterilization techniques (e.g., filtration). The compositions may contain pharmaceutically acceptable auxiliary substances as required to approximate physiological conditions such as pH adjusting and buffering agents, stabilizing, thickening, 20 lubricating and coloring agents, etc. The concentration of the antibodies of the invention in such pharmaceutical formulation may vary, from less than about 0.5%, usually to at least about 1% to as much as 15 or 20% by weight and may be selected primarily based on required dose, fluid volumes, viscosities, etc., according to the particular mode of administration selected. Suitable vehicles and formulations, inclusive of other human proteins, e.g., human serum albumin, are 25 described, for example, in e.g. Remington: The Science and Practice of Pharmacy, 21st Edition, Troy, D.B. ed., Lipincott Williams and Wilkins, Philadelphia, PA 2006, Part 5, Pharmaceutical Manufacturing pp 691-1092, See especially pp. 958-989. The mode of administration for therapeutic use of the antibodies of the invention may be any suitable route that delivers the antibody to the host, such as parenteral administration, e.g., 30 intradermal, intramuscular, intraperitoneal, intravenous or subcutaneous, pulmonary, 2026204725   18 Jun 2026 transmucosal (oral, intranasal, intravaginal, rectal), using a formulation in a tablet, capsule, solution, powder, gel, particle; and contained in a syringe, an implanted device, osmotic pump, cartridge, micropump; or other means appreciated by the skilled artisan, as well known in the art. Site specific administration may be achieved by for example intratumoral, intrarticular, 5 intrabronchial, intraabdominal, intracapsular, intracartilaginous, intracavitary, intracelial, intracerebellar, intracerebroventricular, intracolic, intracervical, intragastric, intrahepatic, intracardial, intraosteal, intrapelvic, intrapericardiac, intraperitoneal, intrapleural, intraprostatic, intrapulmonary, intrarectal, intrarenal, intraretinal, intraspinal, intrasynovial, intrathoracic, intrauterine, intravascular, intravesical, intralesional, vaginal, rectal, buccal, sublingual, 10 intranasal, or transdermal delivery. The antibodies of the invention may be administered to a subject by any suitable route, for example parentally by intravenous (i.v.) infusion or bolus injection, intramuscularly or subcutaneously or intraperitoneally. i.v. infusion may be given over for example 15, 30, 60, 90, 120, 180, or 240 minutes, or from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12 hours. 15 The dose given to a subject is sufficient to alleviate or at least partially arrest the disease being treated (“therapeutically effective amount”) and may be sometimes 0.005 mg to about 100 mg / kg, e.g. about 0.05 mg to about 30 mg / kg or about 5 mg to about 25 mg / kg, or about 4 mg / kg, about 8 mg / kg, about 16 mg / kg or about 24 mg / kg , or for example about 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 mg / kg, but may even higher, for example about 15, 16, 17, 18, 19, 20, 21, 22, 23, 20 24, 25, 30, 40, 50, 60, 70, 80, 90 or 100 mg / kg. A fixed unit dose may also be given, for example, 50, 100, 200, 500 or 1000 mg, or the dose may be based on the patient's surface area, e.g., 500, 400, 300, 250, 200, or 100 mg / m2. Usually between 1 and 8 doses, (e.g., 1, 2, 3, 4, 5, 6, 7 or 8) may be administered to treat the patient, but 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 or more doses may be given. 25 The administration of the antibodies of the invention may be repeated after one day, two days, three days, four days, five days, six days, one week, two weeks, three weeks, one month, five weeks, six weeks, seven weeks, two months, three months, four months, five months, six months or longer. Repeated courses of treatment are also possible, as is chronic administration. The repeated administration may be at the same dose or at a different dose. For example, the 30 antibodies of the invention described herein may be administered at 8 mg / kg or at 16 mg / kg at weekly interval for 8 weeks, followed by administration at 8 mg / kg or at 16 mg / kg every two 2026204725   18 Jun 2026 weeks for an additional 16 weeks, followed by administration at 8 mg / kg or at 16 mg / kg every four weeks by intravenous infusion. For example, the antibodies in the methods described herein, may be provided as a daily dosage in an amount of about 0.1-100 mg / kg, such as 0.5, 0.9, 1.0, 1.1, 1.5, 2, 3, 4, 5, 6, 7, 8, 9, 5 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 40, 45, 50, 60, 70, 80, 90 or 100 mg / kg, per day, on at least one of day 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, or 40, or alternatively, at least one of week 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 after initiation of treatment, or any combination thereof, using single or divided doses of 10 every 24, 12, 8, 6, 4, or 2 hours, or any combination thereof. The antibodies in the methods described herein may also be administered prophylactically in order to reduce the risk of developing cancer, delay the onset of the occurrence of an event in cancer progression, and / or reduce the risk of recurrence when a cancer is in remission. 15 The antibodies provided herein may be lyophilized for storage and reconstituted in a suitable carrier prior to use. This technique has been shown to be effective with conventional protein preparations and well-known lyophilization and reconstitution techniques can be employed. Methods of Detecting CD3, PSMA, CD33, IL1RAP, TMEFF2 or target 20                   antigen and CD3 Provided herein are methods of detecting CD3, PSMA, CD33, TMEFF2, or IL1RAP in a sample, comprising obtaining the sample, contacting the sample with the anti-CD3, the anti-PSMA, the anti-CD33, anti- TMEFF2, or the anti-IL1RAP antibody of the invention and detecting the antibody bound to CD3, PSMA, CD33, TMEFF2, or IL1RAP in the sample. 25 Further provided are methods of detecting CD3 and the second antigen (for example PSMA, CD33, TMEFF2 or IL1RAP) in a sample, comprising obtaining the sample, contacting the sample with the bispecific antibody comprising a first domain that specifically binds CD3 and a second domain that specifically binds a second antigen, , and detecting the antibody bound to CD3 and the second antigen in the sample. 2026204725   18 Jun 2026 In some embodiments described herein, the sample may be derived from urine, blood, serum, plasma, saliva, ascites, circulating cells, circulating tumor cells, cells that are not tissue associated (i.e., free cells), tissues (e.g., surgically resected tumor tissue, biopsies, including fine needle aspiration), histological preparations, and the like. 5 The antibodies of the invention may be detected using known methods. Exemplary methods include direct labeling of the antibodies using fluorescent or chemiluminescent labels, or radiolabels, or attaching to the antibodies of the invention a moiety which is readily detectable, such as biotin, enzymes or epitope tags. Exemplary labels and moieties are ruthenium, 111In-DOTA, 111In- diethylenetriaminepentaacetic acid (DTPA), horseradish 10 peroxidase, alkaline phosphatase and beta-galactosidase, poly-histidine (HIS tag), acridine dyes, cyanine dyes, fluorone dyes, oxazin dyes, phenanthridine dyes, rhodamine dyes and Alexafluor® dyes. The antibodies provided herein may be used in a variety of assays to detect CD3, PSMA, CD33, IL1RAP, TMEFF2 or CD3 and the second antigenin the sample. Exemplary assays are 15 western blot analysis, radioimmunoassay, surface plasmon resonance, immunoprecipitation, equilibrium dialysis, immunodiffusion, electrochemiluminescence (ECL) immunoassay, immunohistochemistry, fluorescence-activated cell sorting (FACS) or ELISA assay. Antibody Kits The invention also provides a kit comprising one or more of the anti-CD3, the anti-20 PSMA, the anti-CD33, anti-TMEFF2 or the anti-IL1RAP antibodies or the bispecific antibodies comprising a first domain that specifically binds CD3 and a second domain that specifically binds a second antigen of the invention or antigen-binding fragments thereof. The described kits may be used to carry out the methods of using the anti-CD3, the anti-PSMA, the anti-CD33, anti-TMEFF2 or the anti-IL1RAP antibodies or the bispecific antibodies comprising a first domain 25 that specifically binds CD3 and a second domain that specifically binds a second antigen of the invention or other methods known to those skilled in the art. In some embodiments the described kits may include the antibodies or antigen-binding fragments described herein and reagents for use in detecting the presence of CD3 or the second antigen such as PSMA, CD33, IL1RAP, TMEFF2 in a biological sampleAccordingly, the described kits may include one or 30 more of the antibodies, or an antigen-binding fragment(s) thereof, described herein and a vessel 2026204725   18 Jun 2026 for containing the antibody or fragment when not in use, instructions for use of the antibody or fragment, the antibody or fragment affixed to a solid support, and / or detectably labeled forms of the antibody or fragment, as described herein. The invention also provides a kit comprising the herein described antibody that 5 specifically binds PSMA. The invention also provides a kit comprising the herein described antibody specifically binding CD33. The invention also provides a kit comprising the herein described antibody specifically binding IL1RAP. The invention also provides a kit comprising the herein described antibody specifically binding TMEFF2. The kit may be used for therapeutic uses and as diagnostic kits. 10 The kit may be used to detect the presence of CD3, PSMA, CD33, IL1RAP, TMEFF2 and / or the second antigen in a biological sample. In some embodiments, the kit comprises the antibody of the invention described herein and reagents for detecting the antibody. The kit can include one or more other elements including: instructions for use; other reagents, e.g., a label, a therapeutic agent, or an agent useful 15 for chelating, or otherwise coupling, an antibody to a label or therapeutic agent, or a radioprotective composition; devices or other materials for preparing the antibody for administration; pharmaceutically acceptable carriers; and devices or other materials for administration to a subject. In some embodiments, the kit comprises the antibody of the invention in a container and 20 instructions for use of the kit. In some embodiments, the antibody in the kit is labeled. CD3-Specific Antibodies Described herein are isolated anti-CD3 antibodies. The anti-CD3 antibodies of the inventionbind human CD3 and optionally cynomolgus CD3. In some embodiments, the anti-25 CD3 antibodies of the invention and fragments thereof bind to human and cynomolgus CD3 with affinities within 5-fold of each other. In other words, the difference in antibody binding is less than a multiple of 5. In this case, the anti-CD3 antibody of the invention can be used for both preclinical evaluation of safety, activity and / or pharmacokinetic profile of CD3 in primates and as a drug in humans. Put in other words, the same CD3-specific molecule can be used in 30 preclinical animal studies as well as in clinical studies in humans. This human / cyno cross- 2026204725   18 Jun 2026 reactivity leads to highly comparable results and a much-increased predictive power of the animal studies compared to species-specific surrogate molecules. In some embodiments, the anti-CD3 antibodies and fragments thereof of the invention bind an epitope formed by the CD3e / d subunits. The CD3-specific antibodies may be human, humanized, or chimeric. Also 5 exemplified herein are human antibodies generated in OmniRat (Open Monoclonal Technologies (“OMT”), Palo Alto, California, USA, omniab.com). In some embodiments described herein, the anti-CD3 antibody or fragment thereof has one, two, three, four or five of the following properties: a) binds human and Macaca fascicularis CD3+ T lymphocytes with a calculated EC50 of 10        20 nM or less and binds Macaca fascicularis CD3-expressing HEK cells with a calculated EC50 of 40 nM or less, wherein the difference in calculated EC50 between binding CD3+ T lymphocytes and binding Macaca fascicularis CD3-expressing HEK cells is less than 5-fold, and wherein the calculated EC50 is measured in a whole cell binding assay at 0 °C using flow cytometry; 15 b) binds recombinant CD3d from human (SEQ ID NO:691), or binds recombinant CD3e from human (SEQ ID NO:636), or binds recombinant CD3e from Macaca fascicularis (SEQ ID NO:693) with an equilibrium dissociation constant (Kd) of 12 nM or less, wherein the Kd is measured using Proteon surface plasmon resonance assay ProteOn XPR36 system at +25°C; 20 c) displays no methionine or tryptophan oxidation, or displays no asparagine deamidation, or displays no asparagine isomerization as detected by peptide mapping analysis; d) binds residues 1-6 of CD3e as determined by X-ray crystallography; or e) activates T cells or induces CD69 expression to a similar degree as cOKT3 or SP34-2 as determined by fluorescence-activated cell sorting assay. 25 The anti-CD3 antibodies and fragments thereof of the invention have an in vitro binding affinity (Kd) to human T cells expressing human CD3 that is from about 5 nM to about 1000 nM, preferably from about 5 nM to about 50 nM, from about 50 nM to about 100 nM, from about 100 nM to about 200 nM, from about 200 nM to about 300 nM, from about 300 nM to about 400 nM, from about 400 nM to about 500 nM, from about 500 nM to about 600 nM, from about 600 nM 30 to about 700 nM, from about 700 nM to about 800 nM, from about 800 nM to about 900 nM, and 2026204725   18 Jun 2026 from about 900 nM to about 1000 nM, more preferably from about 5 nM to about 300 nM, as determined by flow cytometry. In some aspects, the anti-CD3 antibodies and fragments thereof of the invention are bivalent antibodies having an in vitro binding affinity (Kd) to human T cells expressing human 5 CD3 that is from about 5 nM to about 1000 nM preferably from about 5 nM to about 50 nM, from about 50 nM to about 100 nM, from about 100 nM to about 200 nM, from about 200 nM to about 300 nM, from about 300 nM to about 400 nM, from about 400 nM to about 500 nM, from about 500 nM to about 600 nM, from about 600 nM to about 700 nM, from about 700 nM to about 800 nM, from about 800 nM to about 900 nM, and from about 900 nM to about1000 nM, 10 more preferably from about 5 nM to about 300 nM, most preferably about 100 nM, as determined by flow cytometry. Insome aspects, the anti-CD3 antibodies and fragments thereof of the invention are monovalent constructs having an in vitro binding affinity (Kd) to human T cells expressing human CD3 that is from about 5 nM to about 1000 nM preferably from about 5 nM to about 50 15 nM, from about 50 nM to about 100 nM, from about 100 nM to about 200 nM, from about 200 nM to about 300 nM, from about 300 nM to about 400 nM, from about 400 nM to about 500 nM, from about 500 nM to about 600 nM, from about 600 nM to about 700 nM, from about 700 nM to about 800 nM, from about 800 nM to about 900 nM, and from about 900 nM to about1000 nM, more preferably from about 100 nM to about 250 nM, most preferably about 250 nM, as 20 determined by flow cytometry. In one aspect, the anti-CD3 antibodies and fragments thereof described herein compete with commercial CD3 antibody SP34-2 (BD Biosciences 551916) for binding of CD3, as determined by a competition binding assay using an AlexaFluor 488-conjugated SP34-2 antibody on primary human T cells measured using flow cytometry. 25 In one aspect, the anti-CD3 antibodies and fragments thereof exhibit no post-translational modification, including no oxidation, no deamidation, and no aspartate isomerization, as determined by peptide mapping. In one aspect, the anti-CD3 antibodies and fragments thereof are effective in activating T cells and inducing CD69 expression to a similar degree as SP34-2 in human and cynomolgus 30 monkey T cells and cOKT3 in human T cells, as determined by a T cell based assay using flow cytometry. 2026204725   18 Jun 2026 In one aspect, the anti-CD3 antibodies and fragments thereof described herein have a total enthalpy of unfolding of about 400 kcal / mol or more, about 410 kcal / mol or more, about 420 kcal / mol or more, about 430 kcal / mol or more, about 440 kcal / mol or more, about 45 kcal / mol or more, about 460 kcal / mol or more, about 470 kcal / mol or more, about 480 kcal / mol 5 or more, about 490 kcal / mol or more, about 500 kcal / mol or more, about 510 kcal / mol or more, about 520 kcal / mol or more, about 530 kcal / mol or more, about 540 kcal / mol or more, or about 550 kcal / mol or more. In certain aspects, the anti-CD3 antibodies and fragments thereof of the invention have a total enthalpy of unfolding of about 418 kcal / mol, 545 kcal / mol, about 402 kcal / mol, or about 406 kcal / mol, and the anti-CD3 antibodies are CD3B376 (IgG4 PAA), 10 CD3B450 (IgG4 PAA), CD3B389 (IgG1sigma), and CD3B467 (IgG1sigma) molecules, respectively. Exemplary such antibodies include CD3B311, CD3B312, CD3B313, CD3B314, CD3B315, CD3B316, CD3B317, CD3B334, CD3B376 CD3B389, CD3B450 and CD3B467, and CD3B376 and CD3B450 engineered into a monovalent format 15 The anti-CD3 antibodies or antigen-binding fragments of the invention can occur in a variety of forms, but will include one or more of the antibody variable domain segments or CDRs shown in Table 7A and engineered variants thereof, for example, those shown or described in Table 9 and Table 10, and the accompanying descriptions thereof. The invention also provides an anti-CD3 antibody, or an antigen-binding fragment 20 thereof, comprising a heavy chain comprising a HCDR1, a HCDR2, and a HCDR3 of any one of the antibodies described in Table 7B. The invention also provides an anti-CD3 antibody or an antigen-binding fragment thereof, comprising a heavy chain comprising a HCDR1, a HCDR2, and a HCDR3 of any one of the antibodies described in Table 7B and a light chain comprising a LCDR1, a LCDR2, and a LCDR3 of any one of the antibodies described in Table 7B. In some 25 embodiments, the anti-CD3 antibody or an antigen-binding fragment thereof of the inventioncompetes for binding to CD3 with an antibody or antigen-binding fragment thereof comprising a heavy chain comprising a HCDR1, a HCDR2, and a HCDR3 of any one of the antibodies described in Table 7B and a light chain comprising a LCDR1, a LCDR2, and a LCDR3 of any one of the antibodies described in Table 7B. 30 In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises the HCDR1, the HCDR2 and the HCDR3 contained within a heavy 2026204725   18 Jun 2026 chain variable region (VH) of SEQ ID NOs:651, 652, 653, 654, 655, 687, or 656, wherein the HCDR1, the HCDR2 and the HCDR3 are defined by Chothia, Kabat, or IMGT. In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises the LCDR1, the LCDR2 and the LCDR3 contained within a light chain 5 variable region (VL) of SEQ ID NOs: 658, 659, 694, 660, 688, or 661, wherein the LCDR1, the LCDR2 and the LCDR3 are defined by Chothia, Kabat, or IMGT. In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises the HCDR1 of SEQ ID NOs: 662, 665, or 666; 10 the HCDR2 of SEQ ID NOs: 663, 689, or 695; and the HCDR3 of SEQ ID NOs: 664. In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises the LCDR1 of SEQ ID NOs: 773, 710, 674 or 671; 15 the LCDR2 of SEQ ID NOs: 669 or 673; and the LCDR3 of SEQ ID NOs: 670. In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises the HCDR1 of SEQ ID NOs: 662, 665, or 666; 20 the HCDR2 of SEQ ID NOs: 663, 689, or 695; the HCDR3 of SEQ ID NOs: 664; the LCDR1 of SEQ ID NOs: 773, 710, 674 or 671; the LCDR2 of SEQ ID NOs: 669 or 673; and the LCDR3 of SEQ ID NOs: 670. 25 In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises the HCDR1, the HCDR2 and the HCDR3 of SEQ ID NOs: 662, 663, and 664, respectively; SEQ ID NOs: 662, 695, and 664, respectively; SEQ ID NOs: 665, 663, and 664, respectively; 30 SEQ ID NOs: 665, 695, and 664, respectively; SEQ ID NOs: 662, 689, and 664, respectively; 2026204725   18 Jun 2026 SEQ ID NOs: 666, 663, and 664, respectively; SEQ ID NOs: 666, 695, and 664, respectively SEQ ID NOs: 665, 689, and 664, respectively; or SEQ ID NOs: 666, 689, 664, respectively. 5 In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises the LCDR1, the LCDR2 and the LCDR3 of SEQ ID NOs: 773, 669, and 670, respectively; SEQ ID NOs: 773, 673, and 670, respectively; SEQ ID NOs: 710, 673, and 670, respectively; 10 SEQ ID NOs: 674, 673, and 670, respectively; SEQ ID NOs: 671, 673, and 690, respectively; SEQ ID NOs: 773, 673, and 690, respectively; SEQ ID NOs: 671, 669, and 670, respectively; or SEQ ID NOs: 776, 673, and 670, respectively. 15 In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of SEQ ID NOs: 662, 663, 664, 773, 669, and 670, respectively. In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of SEQ 20 ID NOs: 662, 663, 664, 773, 673, and 670, respectively. In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of SEQ ID NOs: 662, 663, 664, 671, 669, and 670, respectively. In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of 25 the invention comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of SEQ ID NOs: 662, 663, 664, 671, 673, and 690, respectively. In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of SEQ ID NOs: 662, 695, 664, 773, 669, and 670, respectively. 2026204725   18 Jun 2026 In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of SEQ ID NOs: 662, 695, 664, 773, 673, and 670, respectively. In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of 5 the invention comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of SEQ ID NOs: 662, 695, 664, 671, 669, and 670, respectively. In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of SEQ ID NOs: 662, 695, 664, 671, 673, and 670, respectively. 10 In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of SEQ ID NOs: 665, 663, 664, 773, 669, and 670, respectively. In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of SEQ 15 ID NOs: 665, 663, 664, 773, 673, and 670, respectively. In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of SEQ ID NOs: 665, 663, 664, 671, 669, and 670, respectively. In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of 20 the invention comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of SEQ ID NOs: 665, 663, 664, 671, 673, and 670, respectively. In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of SEQ ID NOs: 665, 695, 664, 773, 669, and 670, respectively. 25 In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of SEQ ID NOs: 665, 695, 664, 773, 673, and 670, respectively. In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of SEQ 30 ID NOs: 665, 695, 664, 776, 669, and 670, respectively. 2026204725   18 Jun 2026 In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of SEQ ID NOs: 665, 695, 664, 776, 673, and 670, respectively. In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of 5 the invention comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of SEQ ID NOs: 666, 663, 664, 773, 669, and 670, respectively. In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of SEQ ID NOs: 666, 663, 664, 773, 673, and 670, respectively. 10 In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of SEQ ID NOs: 666, 663, 664, 776, 669, and 670, respectively. In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of SEQ 15 ID NOs: 666, 663, 664, 671, 673, and 670, respectively. In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of SEQ ID NOs: 666, 695, 664, 773, 669, and 670, respectively. In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of 20 the invention comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of SEQ ID NOs: 666, 695, 664, 773, 673, and 670, respectively. In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of SEQ ID NOs: 666, 695, 664, 671, 669, and 670, respectively. 25 In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of SEQ ID NOs: 666, 695, 664, 671, 673, and 670, respectively. In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of SEQ 30 ID NOs: 662, 689, 664, 671, 673, and 670, respectively. 2026204725   18 Jun 2026 In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of SEQ ID NOs: 662, 663, 664, 710, 673, and 670, respectively. In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of 5 the invention comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of SEQ ID NOs: 662, 663, 664, 671, 673, and 690, respectively. In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 of SEQ ID NOs: 662, 663, 664, 773, 673, and 690, respectively. 10 In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises a heavy chain (HC) sequence of SEQ ID NO: 709, 640, 641, 642, 643, 675, or 644 and / or a light chain (LC) sequence of SEQ ID NO: 645, 716, 649, 676, 677, or 650. In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises a HC having a polypeptide sequence at least 85%, preferably 90%, more 15 preferably 95% or more, such as 95%, 96%, 97%, 98%, or 99% identical to SEQ ID NO:709, 640, 641, 642, 643, 675, or 644, and a LC having a polypeptide sequence at least 85%, preferably 90%, more preferably 95% or more, such as 95%, 96%, 97%, 98%, or 99% identical to SEQ ID NO:645, 716, 649, 676, 677, or 650. In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises a HC having a polypeptide 20 sequence at least 85%, preferably 90%, more preferably 95% or more, such as 95%, 96%, 97%, 98%, or 99% identical to SEQ ID NO: 709, 640, 641, 642, 643, 675, or 644, and a LC having a polypeptide sequence at least 85%, preferably 90%, more preferably 95% or more, such as 95%, 96%, 97%, 98%, or 99% identical to SEQ ID NO:645, 716, 649, 676, 677 or 650, wherein the variation in sequence does not occur in a CDR region. 25 In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises a heavy chain variable region (VH) sequence of SEQ ID NO:651, 652, 657, 653, 654, 655, 687, or 656 and / or a light chain variable region (VL) sequence of SEQ ID NO:658, 659, 694, 660, 688, 678, or 661. In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises a VH having a polypeptide 30 sequence at least 85%, preferably 90%, more preferably 95% or more, such as 95%, 96%, 97%, 98%, or 99% identical to SEQ ID NO: 651, 652, 657, 653, 654, 655, 687, or 656, and a VL 2026204725   18 Jun 2026 having a polypeptide sequence at least 85%, preferably 90%, more preferably 95% or more, such as 95%, 96%, 97%, 98%, or 99% identical to SEQ ID NOS 658, 659, 694, 660, 688, 678, or 661. In some embodiments, the anti-CD3 antibody of an antigen-binding fragment thereof of the invention comprises a VH having a polypeptide sequence at least 85%, preferably 90%, more 5 preferably 95% or more, such as 95%, 96%, 97%, 98%, or 99% identical to SEQ ID NO: 651, 652, 657, 653, 654, 655, 687, or 656, and a VL having a polypeptide sequence at least 85%, preferably 90%, more preferably 95% or more, such as 95%, 96%, 97%, 98%, or 99% identical to SEQ ID NO:658, 659, 694, 660, 688, 678, or 661, wherein the variation in sequence does not occur in a CDR region. 10 PSMA-Specific Antibodies The antibodies and fragments thereof that bind to PSMA bind to the chimpanzee target antigen. In one embodiment, the antibodies and fragments thereof bind to the human and macaque PSMA target antigens with affinities within 5-fold of each other. In other words, the difference in antibody binding is less than a multiple of 5. In this case, the identical antibody 15 molecule can be used both for preclinical evaluation of safety, activity and / or pharmacokinetic profile of PSMA in primates and as a drug in humans. Put in other words, the same PSMA-specific molecule can be used in preclinical animal studies as well as in clinical studies in humans. This leads to highly comparable results and a much-increased predictive power of the animal studies compared to species-specific surrogate molecules. Since the PSMA domain is 20 cross-species specific, i.e. reactive with the human and macaque antigens, the antibody or fragments thereof of the invention can be used both for preclinical evaluation of safety, activity and / or pharmacokinetic profile of these binding domains in primates and—in the identical form—as drug in humans. The present invention also provides for multispecific antibodies that specifically bind to 25 PSMA. According to the invention, a bispecific, i.e. bifunctional, antibody can be used to engage two different therapeutic targets or perform two distinct functions. Such antibodies can be used for example to recruit an immune effector cell, e.g. T- or NK-cell, towards a particular target cell. Various antibody-fragment based molecules are known and under investigation, for example for cancer therapy. 2026204725   18 Jun 2026 The present invention also provides for a PSMA*“effector antigen” bispecific antibody. In one embodiment, the effector antigen of the PSMA*“effector antigen” bispecific antibody is CD3. It has been found in the present invention that it is possible to generate a PSMA*CD3 bispecific antibody wherein the identical molecule can be used in preclinical animal testing, as 5 well as clinical studies and even in therapy in human. This is due to the identification of the PSMA*CD3 bispecific antibody, which, in addition to binding to human PSMA and human CD3, respectively, also binds to the homologs of antigens of chimpanzee and macaques. The PSMA*CD3 bispecific antibody of the invention can be used as a therapeutic agent against various diseases, including, but not limited, to cancer. In view of the above, the need to construct 10 a surrogate target PSMA*CD3 bispecific antibody for testing in a phylogenetically distant (from humans) species disappears. As a result, the identical molecule can be used in animal preclinical testing as is intended to be administered to humans in clinical testing as well as following market approval and therapeutic drug administration. In some embodiments described herein, the isolated antibody or antibody fragment 15 thereof specifically binding PSMA has one, two, three, four or five of the following properties: 20 25 30 a. binds Pan troglodytes PSMA extracellular domain (ECD) with an equilibrium dissociation constant (Kd) of 25 nM or less, wherein the Kd is measured using ProteOn XPR36 system at +25°C, b. binds LNCaP cells with a calculated EC50 of 20 nM or less and binds Macaca fascicularis PSMA-expressing HEK cells with a calculated EC50 of 40 nM or less, wherein the difference in calculated EC50 between binding LNCaP cells and binding Macaca fascicularis PSMA-expressing HEK cells is less than 5-fold, and wherein the calculated EC50 is measured in a whole cell binding assay at 0 °C using flow cytometry, c. binds recombinant PSMA ECD from human (SEQ ID NO:55), Pan troglodytes (SEQ ID NO:52) and Macaca fascicularis (SEQ ID NO:53) with an equilibrium dissociation constant (Kd) of 12 nM or less, wherein the Kd is measured using Proteon surface plasmon resonance assay ProteOn XPR36 system at +25°C; d. displays T-cell mediated killing of LNCaP cells, C42 cells, human PSMA-expressing HEK cells or Macaca fascicularis PSMA-expressing HEK cells when 2026204725   18 Jun 2026 paired in a bispecific antibody with anti-CD3 antibody, wherein the T-cell mediated killing is measured by Chromium-51 or by caspase 3 / 7 activation assay, or e. recognizes a conformational epitope wherein the epitope is comprised of residues I138, F235, P237, G238, D244, Y299, Y300, Q303, K304, E307, and K324-P326 5 of human PSMA (SEQ ID NO:51) Exemplary such antibodies or fragments thereof are PSMA antibodies PSMB119, PSMB120, PSMB121, PSMB122, PSMB123, PSMB87, PSMB126, PSMB127, PSMB128, PSMB129, PSMB130, PSMB120, PSMB121, PSMB122, PSMB123, PSMB127, PSMB128, PSMB130, PSMB344, PSMB345, PSMB346, PSMB347, PSMB349, PSMB358, PSMB359, 10 PSMB360, PSMB361, PSMB362, PSMB363, and PSMB365 described herein. In some embodiments of the invention described herein, the antibody specifically binding PSMA of the invention comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2 and the LCDR3 of SEQ ID NOs:56, 57, 58, 59, 60, and 61, respectively. In some embodiments of the invention described herein, the antibody specifically binding 15 PSMA of the invention comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2 and the LCDR3 of SEQ ID NOs:62, 63, 64, 65, 60, and 66, respectively. In some embodiments of the invention described herein, the antibody specifically binding PSMA of the invention comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2 and the LCDR3 of SEQ ID NOs:67, 68, 69, 70, 71, and 72, respectively. 20 In some embodiments of the invention described herein, the antibody specifically binding PSMA of the invention comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2 and the LCDR3 of SEQ ID NOs:73, 74, 75, 76, 60, and 61, respectively. In some embodiments of the invention described herein, the antibody specifically binding PSMA of the invention comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the 25 LCDR2 and the LCDR3 of SEQ ID NOs:78, 79, 80, 81, 82, and 83, respectively. In some embodiments of the invention described herein, the antibody specifically binding PSMA of the invention comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2 and the LCDR3 of SEQ ID NOs:84, 85, 86, 87, 60, and 88, respectively. In some embodiments of the invention described herein, the antibody specifically binding 30 PSMA of the invention comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2 and the LCDR3 of SEQ ID NOs:89, 90, 91, 92, 93, and 94, respectively. 2026204725   18 Jun 2026 In some embodiments of the invention described herein, the antibody specifically binding PSMA of the invention comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2 and the LCDR3 of SEQ ID NOs:95, 96, 97, 65, 60, and 66, respectively. In some embodiments of the invention described herein, the antibody specifically binding 5 PSMA of the invention comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2 and the LCDR3 of SEQ ID NOs:84, 98, 99, 100, 82, and 101, respectively. In some embodiments of the invention described herein, the antibody specifically binding PSMA of the invention comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2 and the LCDR3 of SEQ ID NOs:89, 90, 102, 103, 104, and 105, respectively. 10 In some embodiments of the invention described herein, the antibody specifically binding PSMA of the invention comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2 and the LCDR3 of SEQ ID NOs:89, 90, 106, 103, 104, and 105, respectively. In some embodiments of the invention described herein, the antibody specifically binding PSMA of the invention comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the 15 LCDR2 and the LCDR3 of SEQ ID NOs: 107, 108, 109, 76, 60, and 88, respectively. In some embodiments of the invention described herein, the antibody specifically binding PSMA of the invention comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2 and the LCDR3 of SEQ ID NOs: 78, 1, 80, 81, 82, and 83, respectively. In some embodiments of the invention described herein, the antibody specifically binding 20 PSMA of the invention comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2 and the LCDR3 of SEQ ID NOs: 78, 1, 80, 81, 82, and 83, respectively. In some embodiments of the invention described herein, the antibody specifically binding PSMA of the invention comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2 and the LCDR3 of SEQ ID NOs: 78, 1, 80, 4, 82, and 686, respectively. 25 In some embodiments of the invention described herein, the antibody specifically binding PSMA of the invention comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2 and the LCDR3 of SEQ ID NOs: 78, 1, 80, 81, 792, and 686, respectively. In some embodiments of the invention described herein, the antibody specifically binding PSMA of the invention comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the 30 LCDR2 and the LCDR3 of SEQ ID NOs: 78, 2, 80, 81, 82, and 83, respectively. 2026204725   18 Jun 2026 In some embodiments of the invention described herein, the antibody specifically binding PSMA of the invention comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2 and the LCDR3 of SEQ ID NOs: 78, 3, 80, 81, 82, and 5, respectively. In some embodiments of the invention described herein, the antibody specifically binding 5 PSMA of the invention comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2 and the LCDR3 of SEQ ID NOs: 78, 3, 80, 81, 82, and 83, respectively. In some embodiments of the invention described herein, the antibody specifically binding PSMA of the invention comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2 and the LCDR3 of SEQ ID NOs: 78, 3, 80, 4, 82, and 686, respectively. 10 In some embodiments of the invention described herein, the antibody specifically binding PSMA of the invention comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2 and the LCDR3 of SEQ ID NOs: 78, 3, 80, 81, 792, and 686, respectively. In some embodiments of the invention described herein, the antibody specifically binding PSMA of the invention comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the 15 LCDR2 and the LCDR3 of SEQ ID NOs: 78, 2, 81, 81, 82, and 5, respectively. In some embodiments of the invention described herein, the antibody specifically binding PSMA of the invention comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2 and the LCDR3 of SEQ ID NOs: 78, 2, 80, 4, 792, and 686, respectively. In some embodiments of the invention described herein, the antibody specifically binding 20 PSMA of the invention comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2 and the LCDR3 of SEQ ID NOs: 78, 2, 80, 4, 792, and 686, respectively. In some embodiments of the invention described herein, the antibody specifically binding PSMA of the invention comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2 and the LCDR3 of SEQ ID NOs: 78, 683, 80, 81, 792, and 686, respectively. 25 In some embodiments of the invention described herein, the antibody specifically binding PSMA of the invention comprises a heavy chain variable region (VH) of SEQ ID NOs: 6, 7, 8, 110, 112, 114, 116, 118, 120, 121, 123, 125, 126, 128, 130, or 681.In some embodiments of the invention described herein, the antibody specifically binding PSMA of the invention comprises a 30 light chain variable region (VL) of SEQ ID NOs: 9, 111, 113, 115, 117, 119, 122, 124, 127, 129, 131, or 682. 2026204725   18 Jun 2026 In some embodiments of the invention described herein, the antibody specifically binding PSMA of the invention comprises a heavy chain sequence of SEQ ID NOs: 12, 13, 132, 134, 136, 138, 140, 141, 143, 145, 146, 148, 150, 151, or 679. In some embodiments of the invention described herein, the antibody specifically binding 5 PSMA of the invention comprises a light chain sequence of SEQ ID NOs: 14, 15, 75, 133, 135, 137, 139, 142, 144, 147, 149 or 680. CD33-Specific Antibodies The CD33-specific antibodies of the invention possess one or more desirable functional properties, including but not limited to high-affinity binding to CD33 and / or CD3, high 10 specificity to CD33 and / or CD3, and the ability to treat or prevent cancer when administered alone or in combination with other anti-cancer therapies. In certain embodiments, the isolated monoclonal antibodies or antigen-binding fragments thereof bind the C2 domain of CD33. In certain embodiments, the isolated monoclonal antibodies or antigen-binding fragments thereof bind the V domain of CD33. The full length 15 human CD33 is provided by Uniprot P20138 (SEQ ID NO:244). As used herein, an antibody that “specifically binds to CD33” refers to an antibody that binds to a CD33, preferably a human CD33, preferably the C2 domain of CD33, with a KD of 1x10-7 M or less, preferably 1x10-8 M or less, more preferably 5x10-9 M or less, 1x10-9 M or less, 5x10-10 M or less, or 1x10-10 M or less. 20 The antibodies or antigen-binding fragments described herein can occur in a variety of forms, but will include one or more of the antibody CDRs shown in Table 39 and 40. Described herein are recombinant antibodies and antigen-binding fragments that specifically bind to CD33. In some embodiments, the CD33-specific antibodies or antigenbinding fragments are human IgG, or derivatives thereof. While the CD33-specific antibodies or 25 antigen-binding fragments exemplified herein are human, the antibodies or antigen-binding fragments exemplified may be chimerized. In some embodiments are provided an CD33-specific antibody, or an antigen-binding fragment thereof, comprising a heavy chain comprising a CDR1, a CDR2, and a CDR3 of any one of the antibodies described in Table 39. In some embodiments are provided an CD33-30 specific antibody, or an antigen-binding fragment thereof, comprising a heavy chain comprising 2026204725   18 Jun 2026 a CDR1, a CDR2, and a CDR3 of any one of the antibodies described in Table 39 and a light chain comprising a CDR1, a CDR2, and a CDR3 of any one of the antibodies described in Table 40. In some embodiments are provided a CD33-specific antibody, or antigen-binding 5 fragment thereof, comprising a heavy chain variable region shown in Table 38. In some embodiments are provided a CD33-specific antibody, or antigen-binding fragment thereof, comprising a light chain variable region shown in Table 38. The heavy chain variable domain and light chain variable domain of antibodies discussed in this section and shown in Table 38 are suitable for inclusion in bispecific constructs. For 10 example, in some embodiments of the CD33 bispecific antibodies, the effector arm is a CD3 arm. In some embodiments of the CD33xCD3 bispecific antibody, the CD3 arm comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID NOs:662, 663, 664, 671, 673, and 670, respectively. In some embodiments of the CD33xCD3 bispecific antibody, the CD3 arm comprises the VH and VL of SEQ ID NOs: 652 and 661, 15 respectively. In some embodiments of the CD33xCD3 bispecific antibody, the CD3 arm comprises the HC and LC of SEQ ID NOs: 640 and 676, respectively. In some embodiments of the CD33xCD3 bispecific antibody, the CD3 arm comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID NOs:662, 663, 664, 773, 673, and 670, respectively . In some embodiments of the CD33xCD3 20 bispecific antibody, the CD3 arm comprises the VH and VL of SEQ ID NOs:657 and 678, respectively. In some embodiments of the CD33xCD3 bispecific antibody, the CD3 arm comprises comprises the HC and LC of SEQ ID NOs:675 and 677, respectively. In certain embodiments, the anti-CD33 antibody or antigen-binding fragment thereof comprises a heavy chain variable region having a polypeptide sequence at least 95% identical to 25 SEQ ID NO:267, 260, 275, 270, 262, 258, 257, 281, 292, 291, 261, 269, 280, 259, 263, 264, 265, 266, 272, 277, 279, 284, or 285, or a light chain variable region having a polypeptide sequence at least 95% identical to SEQ ID NO:287, 314, 309, 301, 298, 297, 290, 332, 331, 302, 310, 320, 300, 304, 305, 306, 307, 317, 319, 324, or 325; and the anti-CD3 antibody or antigen-binding fragment thereof comprises a heavy chain variable region having a polypeptide sequence at least 30 95% identical to SEQ ID NO:257 or 258, or a light chain variable region having a polypeptide sequence at least 95% identical to SEQ ID NO:298 or 299. 2026204725   18 Jun 2026 IL1RAP-Specific Antibodies As used herein, the terms “interleukin-1 receptor accessory protein”, “IL1RAP” and “IL1-RAP” specifically include the human IL1RAP protein (SEQ ID NO:576), for example as described in GenBank Accession No. AAB84059, NCBI Reference Sequence: NP_002173.1 and 5 UniProtKB / Swiss-Prot Accession No. Q9NPH3-1 (see also Huang et al., 1997, Proc. Natl. Acad. Sci. USA. 94 (24), 12829-12832). IL1RAP is also known in the scientific literature as IL1 R3, C3orf13, FLJ37788, IL-1 RAcP and EG3556. The antibodies or antigen-binding fragments described herein can occur in a variety of forms, but will include one or more of the antibody CDRs shown in Table 29. 10 Described herein are recombinant antibodies and antigen-binding fragments that specifically bind to IL1RAP. In some embodiments, the IL1RAP-specific antibodies or antigenbinding fragments are human IgG, or derivatives thereof. While the IL1RAP-specific antibodies or antigen-binding fragments exemplified herein are human, the antibodies or antigen-binding fragments exemplified may be chimerized. 15 In some embodiments are provided an IL1RAP-specific antibody, or an antigen-binding fragment thereof, comprising a heavy chain comprising a CDR1, a CDR2, and a CDR3 of any one of the antibodies described in Table 29. In some embodiments are provided an IL1RAP-specific antibody, or an antigen-binding fragment thereof, comprising a heavy chain comprising a CDR1, a CDR2, and a CDR3 of any one of the antibodies described in Table 29 and a light 20 chain comprising a CDR1, a CDR2, and a CDR3 of any one of the antibodies described in Table 29. In some embodiments are provided a IL1RAP-specific antibody, or antigen-binding fragment thereof, comprising a heavy chain variable region of any one of the antibodies shown in Table 30. In some embodiments are provided a IL1RAP-specific antibody, or antigen-binding 25 fragment thereof, comprising a light chain variable region of any one of the antibodies shown in Table 30. In some embodiments are provided a IL1RAP-specific antibody, or antigen-binding fragment thereof, comprising a heavy chain variable region and a light chain variable region of any one of the antibodies shown in Table 30. The heavy chain variable domain and light chain variable domain of antibodies discussed 30 in this section and shown in Table 30 are suitable for inclusion in bispecific constructs in which the targeting arm is an anti-IL1RAP arm. For example, in some embodiments of the IL1RAP 2026204725   18 Jun 2026 bispecific antibodies, the effector arm is a CD3 arm. In some embodiments of the IL1RAPxCD3 bispecific antibody, the CD3 arm comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID NOs:662, 663, 664, 671, 673, and 670, respectively. In some embodiments of the IL1RAPxCD3 bispecific antibody, the CD3 arm comprises the VH 5 and VL of SEQ ID NOs: 652 and 661, respectively. In some embodiments of the IL1RAPxCD3 bispecific antibody, the CD3 arm comprises the HC and LC of SEQ ID NOs: 640 and 676, respectively. In some embodiments of the IL1RAPxCD3 bispecific antibody, the CD3 arm comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID 10 NOs:662, 663, 664, 773, 673, and 670, respectively. In some embodiments of the IL1RAPxCD3 bispecific antibody, the CD3 arm comprises the VH and VL of SEQ ID NOs:657 and 678, respectively. In some embodiments of the IL1RAPxCD3 bispecific antibody, the CD3 arm comprises comprises the HC and LC of SEQ ID NOs:675 and 677, respectively. TMEFF2-Specific Antibodies 15 The invention provides an isolated anti-TMEFF2 antibody or an antigen binding fragment thereof that binds to a membrane proximal region of SEQ ID NO: 629 of TMEFF2. The anti-TMEFF2 antibodies of the invention binding the membrane proximal region of TMEFF2 are not internalized by cells. While wishing not to be bound by any particular theory, it can be expected that non-internalizing anti-TMEFF2 antibodies have improved oncogenic effect 20 mediated by antibody effector functions resulting from lack of internalization and degradation of TMEFF2 when compared to internalizing anti-TMEFF2 antibodies. “Binds to a membrane proximal region” means that 90% of antibody epitope residues identified using hydrogen / deuterium exchange (H / D exchange) reside within the membrane proximal region of TMEFF2. The epitope residues are those which are protected by the test 25 antibody by at least 5% difference in deuteration levels through H / D exchange. Exemplary such antibodies are TMEB675, TMEB570, TMEB674, TMEB565, TMEB762 and TMEB757 as described herein. In some embodiments, the isolated anti-TMEFF2 antibody or the antigen binding fragment thereof binds within residues HGKCEHSINMQEPSC (SEQ ID NO: 592) or 30 DAGYTGQHCEKKDYSVL (SEQ ID NO: 600) to the membrane proximal region of TMEFF2. 2026204725   18 Jun 2026 An exemplary anti-TMEFF2 antibody binding within residues HGKCEHSINMQEPSC (SEQ ID NO: 592) is TMEB570. An exemplary anti-TMEFF2 antibody binding within residues DAGYTGQHCEKKDYSVL (SEQ ID NO: 600) is TMEB675. TNEB675 variants TMEB762 and TMEB757 are also expected to bind the membrane proximal region of TMEFF2 within 5 residues DAGYTGQHCEKKDYSVL (SEQ ID NO: 600). In an H / D exchange assay, recombinantly expressed TMEFF2 ECD is incubated in the presence or absence of the antibody in deuterated water for predetermined times resulting in deuterium incorporation at exchangeable hydrogen atoms which are unprotected by the antibody, followed by protease digestion of the protein and analyses of the peptide fragments using LC- 10 MS. H / D exchange assay can be performed using known protocols. An exemplary protocol is described in Example 5. The invention also provides an isolated anti-TMEFF2 antibody or an antigen binding fragment thereof, wherein the antibody or the antigen binding fragment thereof competes for binding to the membrane proximal region of TMEFF2 with a reference antibody comprising a 15 heavy chain variable region (VH) of SEQ ID NO: 25 and a light chain variable region (VL) of SEQ ID NO: 28, the VH of SEQ ID NO: 589 and the VL of SEQ ID NO: 29, the VH of SEQ ID NO: 27 and the VL of SEQ ID NO: 30, the VH of SEQ ID NO: 589 and the VL of SEQ ID NO: 31, the VH of SEQ ID NO: 604 and the VL of SEQ ID NO: 607, or the VH of SEQ ID NO: 612 and the VL of SEQ ID NO: 613. 20        Competition for binding of a test antibody to the membrane proximal region of TMEFF2 with the reference antibody may be assayed in vitro using well known methods. For example, binding of MSD Sulfo-Tag™ NHS-ester-labeled test antibody to the membrane proximal region of TMEFF2 in the presence of an unlabeled reference antibody may be assessed by ELISA, or Bioacore analyses or flow cytometry may be used to demonstrate competition. The test antibody 25 competes for binding to TMEFF2 with the reference antibody when the test antibody inhibits binding of the reference antibody to the membrane proximal region of TMEFF2 by 85% or more, for example 90% or more, or 95% or more. The invention also provides an isolated anti-TMEFF2 antibody or an antigen binding fragment thereof comprising a heavy chain complementarity determining region 1 (HCDR1), a 30 HCDR2, a HCDR3, a light chain complementarity determining region 1 (LCDR1), a LCDR2 and a LCDR3 of 2026204725   18 Jun 2026 SEQ ID NOs: 582, 584, 587, 18, 588 and 22, respectively; SEQ ID NOs: 583, 585, 16, 19, 21, and 23, respectively; SEQ ID NOs: 582, 586, 17, 18, 588 and 24, respectively; SEQ ID NOs: 583, 585, 16, 18, 588 and 22, respectively; or 5 SEQ ID NOs: 582, 584, 587, 18, 588 and 603, respectively. In some embodiments, the isolated anti-TMEFF2 antibody or the antigen binding fragment thereof of the invention binds to the membrane proximal region of TMEFF2 with an equilibrium dissociation constant (Kd) of about 0.4 x 10-9 M or less, wherein the Kd is measured using surface plasmon resonance in acetate buffer at pH 4.5-5.0 at room temperature. 10 In some embodiments, the isolated anti-TMEFF2 antibody or the antigen binding fragment thereof binds to the membrane proximal region of TMEFF2 with the Kd of between about 0.1 x 10-10 M and about 0.4 x 10-9 M. The affinity of an antibody to the membrane proximal region of TMEFF2 may be determined experimentally using any suitable method. An exemplary method utilizes ProteOn 15 XPR36, Biacore 3000 or KinExA instrumentation, ELISA or competitive binding assays known to those skilled in the art. The measured affinity of an antibody to TMEFF2 may vary if measured under different conditions (e.g., osmolarity, pH). Thus, measurements of affinity and other binding parameters (e.g., KD, Kon, and Koff) are typically made with standardized conditions and a standardized buffer, such as the buffer described herein. Skilled in the art will 20 appreciate that the internal error for affinity measurements for example using Biacore 3000 or ProteOn (measured as standard deviation, SD) can typically be within 5-33% for measurements within the typical limits of detection. Therefore, the term “about” when referring to a Kd value reflects the typical standard deviation in the assay. For example, the typical SD for a Kd of 1x10-9 M is up to +0.33x10-9 M. 25 The invention also provides an isolated anti-TMEFF2 antibody or an antigen binding fragment thereof that binds to the membrane proximal region of TMEFF2, comprising a heavy chain variable region (VH) framework derived from VH3_3-23 (SEQ ID NO: 53) or VH1_1-69 (SEQ ID NO: 54). The invention also provides an isolated anti-TMEFF2 antibody or an antigen binding 30 fragment thereof that binds to the membrane proximal region of TMEFF2, comprising a light 2026204725   18 Jun 2026 chain variable region (VL) framework derived from VKI_L11 (SEQ ID NO: 55) or VKIIII_A27 (SEQ ID NO: 591). The invention also provides an isolated anti-TMEFF2 antibody or an antigen binding fragment thereof that binds to the membrane proximal region of TMEFF2, comprising a VH 5 framework and a VL framework derived from VH3_3-23 of SEQ ID NO: 53 and VKI_L11 of SEQ ID NO: 55, respectively. The invention also provides an isolated anti-TMEFF2 antibody or an antigen binding fragment thereof that binds to the membrane proximal region of TMEFF2, comprising a VH framework and a VL framework derived from VH1_1-69 of SEQ ID NO: 54 and VKIII_A27 of 10 SEQ ID NO: 591, respectively. The invention also provides an isolated anti-TMEFF2 antibody or an antigen binding fragment thereof that binds to the membrane proximal region of TMEFF2, comprising a VH framework and a VL framework derived from VH1_1-69 of SEQ ID NO: 54 and VKI_L11 of SEQ ID NO: 55, respectively. 15        Antibodies comprising heavy or light chain variable regions “derived from” a particular framework or germline sequence refer to antibodies obtained from a system that uses human germline immunoglobulin genes, such as from transgenic mice, rats or chicken or from phage display libraries as discussed herein. An antibody containing particular framework derived from germline sequence may contain amino acid differences as compared to the sequence it was 20 derived from, due to, for example, naturally-occurring somatic mutations or intentional substitutions. The invention also provides an isolated anti-TMEFF2 antibody or an antigen binding fragment thereof, comprising a HCDR1, a HCDR2, a HCDR3, a LCDR1, a LCDR2 and a LCDR3 of SEQ ID NOs: 582, 584, 587, 18, 588 and 22, respectively. 25 In some embodiments, the isolated anti-TMEFF2 antibody or the antigen-binding fragment thereof comprises a VH of SEQ ID NO: 25 and a VL of SEQ ID NO: 28. In some embodiments, the VH is encoded by a polynucleotide of SEQ ID NO: 39 and the VL is encoded by a polynucleotide of SEQ ID NO: 42. In some embodiments, the isolated anti-TMEFF2 antibody or the antigen binding 30 fragment thereof comprises a HC of SEQ ID NO: 32 and a LC of SEQ ID NO: 35. 2026204725   18 Jun 2026 In some embodiments, the HC is encoded by a polynucleotide of SEQ ID NO: 46 and the VL is encoded by a polynucleotide of SEQ ID NO: 49. The invention also provides an isolated anti-TMEFF2 antibody or an antigen binding fragment thereof comprising a HCDR1, a HCDR2, a HCDR3, a LCDR1, a LCDR2 and a 5 LCDR3 of SEQ ID NOs: 583, 585, 16, 19, 21 and 23, respectively. In some embodiments, the isolated anti-TMEFF2 antibody or the antigen-binding fragment thereof comprises a VH of SEQ ID NO: 589 and a VL of SEQ ID NO: 29. In some embodiments, the VH is encoded by a polynucleotide of SEQ ID NO: 40 and the VL is encoded by a polynucleotide of SEQ ID NO: 43. 10 In some embodiments, the isolated anti-TMEFF2 antibody or the antigen binding fragment thereof comprises a HC of SEQ ID NO: 33 and a LC of SEQ ID NO: 36. In some embodiments, the HC is encoded by a polynucleotide of SEQ ID NO: 47 and the LC is encoded by a polynucleotide of SEQ ID NO: 50. The invention also provides an isolated anti-TMEFF2 antibody or an antigen binding 15 fragment thereof comprising a HCDR1, a HCDR2, a HCDR3, a LCDR1, a LCDR2 and a LCDR3 of SEQ ID NOs: 582, 586, 17, 18, 588 and 24, respectively. In some embodiments, the isolated anti-TMEFF2 antibody or the antigen binding fragment thereof comprises a VH of SEQ ID NO: 27 and a VL of SEQ ID NO: 30. In some embodiments, the VH is encoded by a polynucleotide of SEQ ID NO: 41 and the 20 VL is encoded by a polynucleotide of SEQ ID NO: 44. In some embodiments, the isolated anti-TMEFF2 antibody or the antigen binding fragment thereof comprises a HC of SEQ ID NO: 34 and a LC of SEQ ID NO: 37. In some embodiments, the HC is encoded by a polynucleotide of SEQ ID NO: 48 and the LC is encoded by a polynucleotide of SEQ ID NO: 51. 25 The invention also provides an isolated anti-TMEFF2 antibody or an antigen binding fragment thereof comprising a HCDR1, a HCDR2, a HCDR3, a LCDR1, a LCDR2 and a LCDR3 of SEQ ID NOs: 583, 585, 16, 18, 588 and 22, respectively. In some embodiments, the isolated anti-TMEFF2 antibody or the antigen binding fragment thereof comprises a VH of SEQ ID NO: 589 and a VL of SEQ ID NO: 31. 30 In some embodiments, the VH is encoded by a polynucleotide of SEQ ID NO: 40 and the VL is encoded by a polynucleotide of SEQ ID NO: 45. 2026204725   18 Jun 2026 In some embodiments, the isolated anti-TMEFF2 antibody or the antigen binding fragment thereof comprises a HC of SEQ ID NO: 33 and a LC of SEQ ID NO: 38. In some embodiments, the HC is encoded by a polynucleotide of SEQ ID NO: 47 and the LC is encoded by a polynucleotide of SEQ ID NO: 590. 5 The invention also provides an isolated anti-TMEFF2 antibody or an antigen binding fragment thereof comprising a HCDR1, a HCDR2, a HCDR3, a LCDR1, a LCDR2 and a LCDR3 of SEQ ID NOs: 582, 584, 587, 18, 588 and 603, respectively. In some embodiments, the isolated anti-TMEFF2 antibody or the antigen-binding fragment thereof comprises a VH of SEQ ID NO: 604 and a VL of SEQ ID NO: 607. 10 In some embodiments, the VH is encoded by a polynucleotide of SEQ ID NO: 618 and the VL is encoded by a polynucleotide of SEQ ID NO: 619. In some embodiments, the isolated anti-TMEFF2 antibody or the antigen binding fragment thereof comprises a HC of SEQ ID NO: 614 and a LC of SEQ ID NO: 615. In some embodiments, the HC is encoded by a polynucleotide of SEQ ID NO: 620 and 15 the LC is encoded by a polynucleotide of SEQ ID NO: 621. The invention also provides an isolated anti-TMEFF2 antibody or an antigen binding fragment thereof comprising a HCDR1, a HCDR2, a HCDR3, a LCDR1, a LCDR2 and a LCDR3 of SEQ ID NOs: 582, 584, 587, 18, 588 and 603, respectively. In some embodiments, the isolated anti-TMEFF2 antibody or the antigen binding 20 fragment thereof comprises a VH of SEQ ID NO: 612 and a VL of SEQ ID NO: 613. In some embodiments, the VH is encoded by a polynucleotide of SEQ ID NO: 622 and the VL is encoded by a polynucleotide of SEQ ID NO: 623. In some embodiments, the isolated anti-TMEFF2 antibody or the antigen binding fragment thereof comprises a HC of SEQ ID NO: 616 and a LC of SEQ ID NO: 617. 25 In some embodiments, the HC is encoded by a polynucleotide of SEQ ID NO: 624 and the LC is encoded by a polynucleotide of SEQ ID NO: 625. In some embodiments, the isolated anti-TMEFF2 antibody or the antigen binding fragment thereof is a multispecific antibody. In some embodiments, the isolated anti-TMEFF2 antibody or the antigen binding 30 fragment thereof is a bispecific antibody. 2026204725   18 Jun 2026 In some embodiments, the isolated anti-TMEFF2 bispecific antibody or the antigen binding fragment thereof binds a T cell antigen. In some embodiments, the isolated anti-TMEFF2 bispecific antibody or the antigen binding fragment thereof binds CD3. 5 In some embodiments, the isolated anti-TMEFF2 bispecific antibody or the antigenbinding fragment thereof binds CD3 epsilon. The VH, the VL, the HCDR, the LCDR, the HC and the LC sequences of exemplary anti-TMEFF2 antibodies of the invention are shown in Tables 60-67. Although the embodiments illustrated in the Examples comprise pairs of variable 10 domains, one from a heavy chain and one from a light chain, a skilled artisan will recognize that alternative embodiments may comprise single heavy or light chain variable domains. The single variable domain may be used to screen for variable domains capable of forming a two-domain specific antigen-binding fragment capable of binding to TMEFF2. The screening may be accomplished by phage display screening methods using for example hierarchical dual 15 combinatorial approach disclosed in Int. Patent Publ. No. WO1992 / 01047. In this approach, an individual colony containing either a VH or a VL chain clone is used to infect a complete library of clones encoding the other chain (VL or VH), and the resulting two-chain specific antigenbinding domain is selected in accordance with phage display techniques using known methods and those described herein. Therefore, the individual VH and VL polypeptide chains are useful 20 in identifying additional anti-TMEFF2 antibodies using the methods disclosed in Int. Patent Publ. No. WO1992 / 01047. Bispecific anti-TMEFF2 / anti-CD3 antibodies The invention also provides an isolated bispecific anti-TMEFF2 / anti-CD3 antibody or an antigen binding fragment thereof comprising a first domain that binds TMEFF2 and a second 25 domain that binds CD3, wherein the antibody binds to the membrane proximal region of TMEFF2. While not wishing to be bound by any particular theory, bispecific antibodies binding to the membrane proximal region of TMEFF2 may be more efficient in mediating T-cell mediated killing of tumor cells. The invention also provides an isolated bispecific anti-TMEFF2 / anti-CD3 antibody or an 30 antigen binding fragment thereof comprising a first domain that binds TMEFF2 and a second domain that binds CD3, wherein the antibody competes for binding to the membrane proximal 2026204725   18 Jun 2026 region of TMEFF2 with a reference antibody comprising a heavy chain variable region (VH) of SEQ ID NO: 25 and a light chain variable region (VL) of SEQ ID NO: 28, the VH of SEQ ID NO: 589 and the VL of SEQ ID NO: 29, the VH of SEQ ID NO: 27 and the VL of SEQ ID NO: 30, the VH of SEQ ID NO: 589 and the VL of SEQ ID NO: 31, the VH of SEQ ID NO: 604 and 5 the VL of SEQ ID NO: 607, or the VH of SEQ ID NO: 612 and the VL of SEQ ID NO: 613. In some embodiments, the isolated bispecific anti-TMEFF2 / anti-CD3 antibody or an antigen binding fragment thereof binds the membrane proximal region of TMEFF2 with a dissociation constant (Kd) of about 0.4 x 10-9 M or less, wherein the Kd is measured using surface plasmon resonance in acetate buffer at pH 4.5-5.0 at room temperature. 10 In some embodiments, the isolated bispecific anti-TMEFF2 / anti-CD3 antibody or the antigen binding fragment thereof binds the membrane proximal region TMEFF2 with the Kd of between about 0.1 x 10-10 M and about 0.4 x 10-9 M. The invention also provides an isolated bispecific anti-TMEFF2 / anti-CD3 antibody or an antigen binding fragment thereof, wherein the first domain comprises a HCDR1, a HCDR2, a 15 HCDR3, a LCDR1, a LCDR2 and a LCDR3 of SEQ ID NOs: 582, 584, 587, 18, 588 and 22, respectively; SEQ ID NOs: 583, 585, 16, 19, 21 and 23, respectively; SEQ ID NOs: 582, 586, 17, 18, 588 and 24, respectively; o SEQ ID NOs: 583, 585, 16, 18, 588 and 22, respectively; or 20 SEQ ID NOs: 582, 584, 587, 18, 588 and 603, respectively. The invention also provides an isolated bispecific anti-TMEFF2 / anti-CD3 antibody or an antigen binding fragment thereof, wherein the second domain comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2 and the LCDR3 of SEQ ID NOs: 662, 663, 664, 671, 673, and 690, respectively. 25 The invention also provides an isolated bispecific anti-TMEFF2 / anti-CD3 antibody or an antigen binding fragment thereof, wherein the first domain comprises the VH of SEQ ID NO: 25 and the VL of SEQ ID NO: 28; the VH of SEQ ID NO: 589 and the VL of SEQ ID NO: 29; the VH of SEQ ID NO: 27 and the VL of SEQ ID NO: 30; 30 the VH of SEQ ID NO: 589 and the VL of SEQ ID NO: 31; the VH of SEQ ID NO: 604 and the VL of SEQ ID NO: 607; or 2026204725   18 Jun 2026 the VH of SEQ ID NO: 612 and the VL of SEQ ID NO: 613. The invention also provides an isolated bispecific anti-TMEFF2 / anti-CD3 antibody or an antigen binding fragment thereof, wherein the second domain comprises the VH of SEQ ID NO: 652 and the VL of SEQ ID NO: 661. 5 In some embodiments, the second domain comprises the VH of SEQ ID NO:657 and the VL of SEQ ID NO: 658. The invention also provides an isolated bispecific anti-TMEFF2 / anti-CD3 antibody or an antigen binding fragment thereof comprising a first domain that binds TMEFF2 and a second 10 domain that binds CD3, wherein the first domain comprises a HCDR1, a HCDR2, a HCDR3, a LCDR1, a LCDR2 and a LCDR3 of SEQ ID NOs: 582, 584, 587, 18, 588 and 22, respectively, and the second domain comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2 and the LCDR3 of SEQ ID NOs: 662, 663, 664, 671, 673, and 690, respectively; 15 the first domain comprises a VH of SEQ ID NO: 25 and a VL of SEQ ID NO: 28, and the second domain comprises the VH of SEQ ID NO: 652 and the VL of SEQ ID NO: 661; the first domain comprises a VH of SEQ ID NO: 25 and a VL of SEQ ID NO: 28, and the second domain comprises the VH of SEQ ID NO: 657 and the VL of SEQ ID NO: 678; 20 the bispecific anti-TMEFF2 / anti-CD3 antibody or the antigen binding fragment thereof comprises a HC1 of SEQ ID NO: 32, a LC1 of SEQ ID NO: 35, a HC2 of SEQ ID NO: 640 and a LC2 of SEQ ID NO: 676; and / or the bispecific anti-TMEFF2 / anti-CD3 antibody or the antigen binding fragment thereof comprises a HC1 of SEQ ID NO: 32, a LC1 of SEQ ID NO: 35, a HC2 of SEQ ID NO: 675 and 25 a LC2 of SEQ ID NO: 677. The invention also provides an isolated bispecific anti-TMEFF2 / anti-CD3 antibody or an antigen binding fragment thereof comprising a first domain that binds TMEFF2 and a second domain that binds CD3, wherein the first domain comprises a HCDR1, a HCDR2, a HCDR3, a LCDR1, a LCDR2 and a 30 LCDR3 of SEQ ID NOs: 583, 585, 16, 19, 21, and 23, respectively, and the second domain 2026204725   18 Jun 2026 comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2 and the LCDR3 of SEQ ID NOs: 662, 663, 664, 671, 673, and 690, respectively; the first domain comprises a VH of SEQ ID NO: 589 and a VL of SEQ ID NO: 29, and the second domain comprises the VH of SEQ ID NO: 652 and the VL of SEQ ID NO: 661; 5 the first domain comprises a VH of SEQ ID NO: 589 and a VL of SEQ ID NO: 29, and the second domain comprises the VH of SEQ ID NO: 657 and the VL of SEQ ID NO: 678 and / or the bispecific anti-TMEFF2 / anti-CD3 antibody or the antigen binding fragment thereof comprises a HC1 of SEQ ID NO: 33, a LC1 of SEQ ID NO: 36, a HC2 of SEQ ID NO: 640 and 10 a LC2 of SEQ ID NO: 676; the bispecific anti-TMEFF2 / anti-CD3 antibody or the antigen binding fragment thereof comprises a HC1 of SEQ ID NO: 33, a LC1 of SEQ ID NO: 36, a HC2 of SEQ ID NO: 675 and a LC2 of SEQ ID NO: 677. The invention also provides an isolated bispecific anti-TMEFF2 / anti-CD3 antibody or an 15 antigen binding fragment thereof comprising a first domain that binds TMEFF2 and a second domain that binds CD3, wherein the first domain comprises a HCDR1, a HCDR2, a HCDR3, a LCDR1, a LCDR2 and a LCDR3 of SEQ ID NOs: 582, 586, 17, 18, 588 and 24, respectively, and the second domain comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2 and the LCDR3 of 20 SEQ ID NOs: 662, 663, 664, 671, 673, and 690, respectively; the first domain comprises a VH of SEQ ID NO: 27 and a VL of SEQ ID NO: 30, and the second domain comprises the VH of SEQ ID NO: 652 and the VL of SEQ ID NO: 661; the first domain comprises a VH of SEQ ID NO: 27 and a VL of SEQ ID NO: 30, and the second domain comprises the VH of SEQ ID NO: 657 and the VL of SEQ ID NO: 678, and / or 25 the bispecific anti-TMEFF2 / anti-CD3 antibody or the antigen binding fragment thereof comprises a HC1 of SEQ ID NO: 34, a LC1 of SEQ ID NO: 37, a HC2 of SEQ ID NO: 640 and a LC2 of SEQ ID NO: 676; the bispecific anti-TMEFF2 / anti-CD3 antibody or the antigen binding fragment thereof comprises a HC1 of SEQ ID NO: 34, a LC1 of SEQ ID NO: 37, a HC2 of SEQ ID NO: 675 and 30 a LC2 of SEQ ID NO: 677. 2026204725   18 Jun 2026 The invention also provides an isolated bispecific anti-TMEFF2 / anti-CD3 antibody or an antigen binding fragment thereof comprising a first domain that binds TMEFF2 and a second domain that binds CD3, wherein the first domain comprises a HCDR1, a HCDR2, a HCDR3, a LCDR1, a LCDR2 and a 5 LCDR3 of SEQ ID NOs: 583, 585, 16, 18, 588 and 22, respectively, and the second domain comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2 and the LCDR3 of SEQ ID NOs: 662, 663, 664, 671, 673, and 690, respectively; the first domain comprises a VH of SEQ ID NO: 589 and a VL of SEQ ID NO: 31, and the second domain comprises the VH of SEQ ID NO: 652 and the VL of SEQ ID NO: 661; 10 the first domain comprises a VH of SEQ ID NO: 589 and a VL of SEQ ID NO: 31, and the second domain comprises the VH of SEQ ID NO: 657 and the VL of SEQ ID NO: 678; and / or the bispecific anti-TMEFF2 / anti-CD3 antibody or the antigen binding fragment thereof comprises a HC1 of SEQ ID NO: 33, a LC1 of SEQ ID NO: 38, a HC2 of SEQ ID NO:640 and a 15 LC2 of SEQ ID NO: 676; the bispecific anti-TMEFF2 / anti-CD3 antibody or the antigen binding fragment thereof comprises a HC1 of SEQ ID NO: 33, a LC1 of SEQ ID NO: 38, a HC2 of SEQ ID NO:675 and a LC2 of SEQ ID NO: 677. . 20        The invention also provides an isolated bispecific anti-TMEFF2 / anti-CD3 antibody or an antigen binding fragment thereof comprising a first domain that binds TMEFF2 and a second domain that binds CD3, wherein the first domain comprises a HCDR1, a HCDR2, a HCDR3, a LCDR1, a LCDR2 and a LCDR3 of SEQ ID NOs: 582, 584, 587, 18, 588 and 603, respectively, and the second domain 25 comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2 and the LCDR3 of SEQ ID NOs: 662, 663, 664, 671, 673, and 690, respectively; the first domain comprises a VH of SEQ ID NO: 604 and a VL of SEQ ID NO: 607, and the second domain comprises the VH of SEQ ID NO: 652 and the VL of SEQ ID NO: 661; the first domain comprises a VH of SEQ ID NO: 604 and a VL of SEQ ID NO: 607, and 30 the second domain comprises the VH of SEQ ID NO: 657 and the VL of SEQ ID NO: 678; and / or 2026204725   18 Jun 2026 the bispecific anti-TMEFF2 / anti-CD3 antibody or the antigen binding fragment thereof comprises a HC1 of SEQ ID NO: 614, a LC1 of SEQ ID NO: 615, a HC2 of SEQ ID NO: 640 and a LC2 of SEQ ID NO: 676; the bispecific anti-TMEFF2 / anti-CD3 antibody or the antigen binding fragment thereof 5 comprises a HC1 of SEQ ID NO: 614, a LC1 of SEQ ID NO: 615, a HC2 of SEQ ID NO: 675 and a LC2 of SEQ ID NO: 677. The invention also provides an isolated bispecific anti-TMEFF2 / anti-CD3 antibody or an antigen binding fragment thereof comprising a first domain that binds TMEFF2 and a second domain that binds CD3, wherein 10 the first domain comprises a HCDR1, a HCDR2, a HCDR3, a LCDR1, a LCDR2 and a LCDR3 of SEQ ID NOs: 582, 584, 587, 18, 588 and 603, respectively, and the second domain comprises the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2 and the LCDR3 of SEQ ID NOs: 662, 663, 664, 671, 673, and 690, respectively; the first domain comprises a VH of SEQ ID NO: 612 and a VL of SEQ ID NO: 613, and 15 the second domain comprises the VH of SEQ ID NO: 652 and the VL of SEQ ID NO: 661; the first domain comprises a VH of SEQ ID NO: 612 and a VL of SEQ ID NO: 613, and the second domain comprises the VH of SEQ ID NO: 657 and the VL of SEQ ID NO: 678; and / or the bispecific anti-TMEFF2 / anti-CD3 antibody or an antigen binding fragment thereof 20 comprises a HC1 of SEQ ID NO: 616, a LC1 of SEQ ID NO: 617, a HC2 of SEQ ID NO: 640 and a LC2 of SEQ ID NO: 676; the bispecific anti-TMEFF2 / anti-CD3 antibody or an antigen binding fragment thereof comprises a HC1 of SEQ ID NO: 616, a LC1 of SEQ ID NO: 617, a HC2 of SEQ ID NO: 675 and a LC2 of SEQ ID NO: 677. 25           . EMBODIMENTS: This invention provides the following non-limiting embodiments. 1. An isolated recombinant anti-CD3 antibody, or antigen-binding fragment thereof, 30 comprising: 2026204725   18 Jun 2026 a) a heavy chain comprising a heavy chain complementarity determining region (HCDR) 1 comprising SEQ ID NO: 662; a HCDR2 comprising SEQ ID NO: 663; and a HCDR3 comprising SEQ ID NO: 664 and a light chain comprising a light chain complementarity determining region (LCDR) 1 comprising SEQ ID NO: 671, a LCDR2 comprising SEQ 5 ID NO: 673, and a LCDR3 comprising SEQ ID NO: 690; b) a heavy chain variable region comprising SEQ ID NO: 652 and a light chain variable region comprising SEQ ID NO: 661; c) a heavy chain comprising SEQ ID NO: 640 and a light chain comprising SEQ ID NO: 676; 10 d) a heavy chain comprising a HCDR1 comprising SEQ ID NO: 662; a HCDR2 comprising SEQ ID NO: 663; and a HCDR3 comprising SEQ ID NO: 664 and a light chain comprising a LCDR1 comprising SEQ ID NO: 773, a LCDR2 comprising SEQ ID NO: 673, and a LCDR3 comprising SEQ ID NO: 690; e) a heavy chain variable region comprising SEQ ID NO: 657 and a light chain variable 15 region comprising SEQ ID NO: 678; or f) a heavy chain comprising SEQ ID NO: 675 and a light chain comprising SEQ ID NO: 678. 2. An isolated recombinant anti-CD3 antibody or antigen-binding fragment thereof, wherein the antibody or antigen-binding fragment specifically binds Macaca fascicularis or human 20 CD3d, or CD3e, or CD3e and CD3d with a binding affinity of about 300 nM or less. 3. The isolated recombinant anti-CD3 antibody or antigen-binding fragment thereof of embodiment 2, wherein the binding affinity is about 100 nM or less. 4. The isolated recombinant anti-CD3 antibody or antigen-binding fragment thereof of embodiment 2 or 3, wherein the binding affinity is measured by flow cytometry or by 25 Proteon surface plasmon resonance assay ProteOn XPR36 system at +25°C. 5. The isolated recombinant anti-CD3 antibody or antigen-binding fragment thereof of any one of the previous embodiments, wherein the antibody or antigen-binding fragment has one, two, three, or four of the following properties: a) binds human and Macaca fascicularis CD3+ T lymphocytes with a calculated EC50 of 30        300 nM or less and binds Macaca fascicularis CD3-expressing HEK cells with a calculated EC50 of 300 nM or less, wherein the difference in calculated EC50 between 2026204725   18 Jun 2026 binding CD3+ T lymphocytes and binding Macaca fascicularis CD3-expressing HEK cells is less than 5-fold, and wherein the calculated EC50 is measured in a whole cell binding assay at 0 °C using flow cytometry; b) binds recombinant CD3d from human (SEQ ID NO:691), or binds recombinant CD3e 5 from human (SEQ ID NO:636), or binds recombinant CD3d from Macaca fascicularis (SEQ ID NO:692), or binds recombinant CD3e from Macaca fascicularis (SEQ ID NO:693) with an equilibrium dissociation constant (Kd) of 300 nM or less, wherein the Kd is measured using Proteon surface plasmon resonance assay ProteOn XPR36 system at +25°C; 10 c) binds residues 1-6 of CD3e as determined by X-ray crystallography; or d) activates T cells or induces CD69 expression to a similar degree as cOKT3 or SP34-2 as determined by fluorescence-activated cell sorting assay. 6. The antibody or antigen-binding fragment thereof of any one of the previous embodiments comprising at least one substitution in an antibody constant domain, the at least one 15 substitution comprising: a) heavy chain substitutions K409R, F405L, or F405L and R409K; b) heavy chain substitutions S228P, F234A, and L235A; c) heavy chain substitutions L234A, G237A, P238S, H268A, A330S and P331S, wherein the antibody is an IgG1 isotype; or 20 d) heavy chain substitution S228P, wherein the antibody is an IgG4 isotype; wherein residue numbering is according to the EU Index. 7. The antibody or antigen-binding fragment thereof of any one of the previous embodiments, comprising the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID NOs:662, 663, 664, 671, 673, and 690, respectively. 25 8. The antibody or antigen-binding fragment thereof of any one of the previous embodiments, comprising a heavy chain variable region (VH) and a light chain variable region (VL) of SEQ ID NOs:652 and 661, respectively. 2026204725   18 Jun 2026 9. The antibody or antigen-binding fragment thereof of any one of the previous embodiments, comprising a heavy chain sequence (HC) and a light chain sequence (LC) of SEQ ID NOs:640 and 676, respectively. 10. The antibody or antigen-binding fragment thereof of any one of embodiments 1-5, 5 comprising the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID NOs:662, 663, 664, 773, 673, and 690, respectively. 11. The antibody or antigen-binding fragment thereof of any one of embodiments 1-5, comprising a VH and a VL of SEQ ID NOs:657 and 678, respectively. 12. The antibody or antigen-binding fragment thereof of any one of embodiments 1-5, 10 comprising a HC and a LC of SEQ ID NOs:675 and 677, respectively. 13. An antibody or antigen-binding fragment thereof, comprising the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID NOs: 662, 663, 664, 671, 673, and 690, respectively. 14. An antibody or antigen-binding fragment thereof, comprising a VH and a VL of SEQ ID 15 NOs:652 and 661, respectively. 15. An antibody or antigen-binding fragment thereof, comprising a HC and a LC of SEQ ID NOs:640 and 676, respectively. 16. An antibody or antigen-binding fragment thereof, comprising the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID NOs:662, 663, 664, 773, 673, 20 and 690, respectively. 17. An antibody or antigen-binding fragment thereof, comprising a VH and a VL of SEQ ID NOs:657 and 678, respectively. 18. An antibody or antigen-binding fragment thereof, comprising a HC and a LC of SEQ ID NOs:675 and 677, respectively. 25 19. The antibody or antigen-binding fragment thereof of any one of the previous embodiments, wherein the antibody is human or humanized. 20. The antibody of embodiment 19, wherein the antibody is an IgG4 or IgG1 isotype. 2026204725   18 Jun 2026 21. The antibody of embodiment 20, comprising one, two, three, four, five, six, seven, eight, nine or ten substitutions in the antibody Fc. 22. The antibody of embodiment 18, comprising: a) D43G, L49M, L50I, S62N, Q85E light chain substitutions; 5 b) D43G, V48L, L49M, L50I, S62N, Q85E, H89Y light chain substitutions; c) R10G, R13K, V73I, R70K, T83S, L96V heavy chain substitutions; d) any one of light chain substitutions D43G, V48L, L49M, L50I, S62N, Q85E, or H89Y; or e) any one of heavy chain substitutions R10G, R13K, V73I, R79K, T83S, or L96V, wherein residue numbering for light chain substitutions is according to SEQ ID No: 661, 10 and for heavy chain substitutions is according to SEQ ID No: 652. 23. The antibody of any one of the previous embodiments, wherein the antibody is bispecific or multispecific. 24. A bispecific antibody comprising a first domain that specifically binds CD3 and a second domain that specifically binds a second antigen, wherein the first domain comprises the 15 HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID NOs:662, 663, 664, 671, 673, and 690, respectively. 25. The bispecific antibody of embodiment 24 wherein the first domain and second domain are an IgG4 isotype, and wherein the first or the second domain comprises S228P, F234A, L235A, F405L and R409K heavy chain substitutions and the other domain of the first or the 20 second domain comprises S228P, F234A and L235A heavy chain substitution, wherein residue numbering is according to the EU Index. 26. The bispecific antibody of embodiment 24, wherein the first and / or the second domain comprises at least one substitution in a CH3 constant domain comprising a F405L, or F405L and R409K substitution, wherein residue numbering is according to the EU Index. 25 27. The bispecific antibody of embodiment 24, wherein one of the first or the second domains comprises a F405L heavy chain substitution and the other of the first or second domains comprises a K409R heavy chain substitution, wherein residue numbering is according to the EU Index. 2026204725   18 Jun 2026 28. The bispecific antibody of embodiment 24, wherein the first domain and the second domain are an IgG4 isotype, wherein one of the first or the second domains comprises a S228P heavy chain substitution and the other of the first or the second domains comprises S228P, F405L and R409K heavy chain substitutions, wherein residue numbering is according to the EU 5 Index. 29. The bispecific antibody of claim 24, wherein the first domain comprises the VH and the VL of SEQ ID NOs: 652 and 661, respectively. 30. The bispecific antibody of claim 24, wherein the first domain comprises the HC and the LC of SEQ ID NOs: 640 and 676, respectively. 10 31. The bispecific antibody of claim 24, wherein the first domain comprises the VH and the VL of SEQ ID NOs:657 and 678, respectively. 32. The bispecific antibody of claim 24, wherein the first domain comprises the HC and the LC of SEQ ID NOs:675 and 677, respectively. 33. The bispecific antibody of claim24, wherein the second antigen is a cell surface antigen that 15 is expressed on a target cell other than an immune effector cell. 34. The bispecific antibody of claim 33, wherein the cell surface antigen is a tumor associated antigen. 35. The bispecific antibody of any one of claims 24-34, wherein the second antigen is CD33, IL1RAP, PSMA or TMEFF2. 20 36. The bispecific antibody of embodiment 35, wherein the first domain comprises the HCDR1, HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID NOs:662, 663, 664, 671, 673, and 690, respectively; and wherein the second domain comprises the the HCDR1, HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID NOs:78, 683, 80, 81, 792, and 686, respectively. 25 37. The bispecific antibody of embodiment 33, wherein the first domain comprises the VH and VL of SEQ ID NOs:652 and 661, respectively; and wherein the second domain comprises the VH and VL of SEQ ID NOs:681 and 682, respectively. 2026204725   18 Jun 2026 38. The bispecific antibody of embodiment 33, wherein the first domain comprises the HC and LC of SEQ ID NOs:640 and 676, respectively; and wherein the second domain comprises the HC and LC of SEQ ID NOs:679 and 680, respectively. 39. The bispecific antibody of embodiment 33, wherein the first domain comprises the HCDR1, 5 HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID NOs:662, 663, 664, 671, 673, and 690, respectively; and wherein the second domain comprises the the HCDR1, HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID NOs:78, 3, 80, 81, 792 and 686, respectively . 40. The bispecific antibody of embodiment 33, wherein the first domain comprises the VH and 10 VL of SEQ ID NOs:652 and 661, respectively; and wherein the second domain comprises the VH and VL of SEQ ID NOs 8 and 682, respectively. . 41. The bispecific antibody of embodiment 33, wherein the first domain comprises the HC and LC of SEQ ID NOs:640 and 676, respectively; and wherein the second domain comprises the HC and LC of SEQ ID NOs 13 and 680, respectively. 15 42. The bispecific antibody of embodiment 33, wherein the first domain comprises the HCDR1, HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID NOs:662, 663, 664, 671, 673, and 690, respectively; and wherein the second domain comprises the the HCDR1, HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID NOs:78, 79, 80, 81, 82 and 83, respectively. 20 43. The bispecific antibody of embodiment 33, wherein the first domain comprises the VH and VL of SEQ ID NOs:652 and 661, respectively; and wherein the second domain comprises the VH and VL of SEQ ID NOs:116 and 117, respectively. 44. The bispecific antibody of embodiment 33, wherein the first domain comprises the HC and LC of SEQ ID NOs:640 and 676, respectively; and wherein the second domain comprises the 25 HC and LC of SEQ ID NOs:138 and 139, respectively. 45. The bispecific antibody of embodiment 31, wherein the first domain comprises the HCDR1, HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID NOs: 662, 663, 664, 671, 673, and 670, respectively; and wherein the second domain comprises the the 2026204725   18 Jun 2026 HCDR1, HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID NOs:164, 165, 166, 167, 168, and 169, respectively. 46. The bispecific antibody of embodiment 31, wherein the first domain comprises the VH and VL of SEQ ID NOs:652 and 661, respectively; and wherein the second domain comprises the 5 VH and VL of SEQ ID NOs:215 and 216, respectively. 47. The bispecific antibody of embodiment 31, wherein the first domain comprises the HCDR1, HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID NOs: 662, 663, 664, 671, 673, and 670, respectively; and wherein the second domain comprises the the HCDR1, HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID 10 NOs:349, 390, 341, 471, 513, and 555, respectively. 48. The bispecific antibody of embodiment 31, wherein the first domain comprises the VH and VL of SEQ ID NOs:652 and 661, respectively; and wherein the second domain comprises the VH and VL of SEQ ID NOs:267 and 306, respectively. 49. The bispecific antibody of embodiment 31, wherein the first domain comprises the HCDR1, 15 HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID NOs: 662, 663, 664, 671, 673, and 670, respectively; and wherein the second domain comprises the HCDR1, HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID NOs:363, 404, 445, 485, 527, and 569, respectively. 50. The bispecific antibody of embodiment 31, wherein the first domain comprises the VH and 20 VL of SEQ ID NOs:652 and 661, respectively; and wherein the second domain comprises the VH and VL of SEQ ID NOs:281 and 320, respectively. 51. A pharmaceutical composition comprising the antibody of any one of the previous embodiments and a pharmaceutically acceptable carrier. 52. A polynucleotide encoding the antibody of any one of the embodiments 1-50. 25 53. A vector comprising the polynucleotide of embodiment 52. 54. A host cell comprising the vector of embodiment 53. 2026204725   18 Jun 2026 55. A method of producing the antibody of any one of embodiments 1-50, comprising culturing the host cell of embodiment 52 in conditions that the antibody is expressed, and recovering the antibody produced by the host cell. 56. A method of treating a cancer in a subject, comprising administering a therapeutically 5 effective amount of the isolated antibody of any one of embodiments 1-50 to the subject in need thereof for a time sufficient to treat the cancer. 57. The method of embodiment 56, wherein the cancer is a solid tumor or a hematological malignancy. 58. The method of embodiment 57, wherein the solid tumor is a prostate cancer, a colorectal 10 cancer, a gastric cancer, a clear cell renal carcinoma, a bladder cancer, a lung cancer, a squamous cell carcinoma, a glioma, a breast cancer, a kidney cancer, a neovascular disorder, a clear cell renal carcinoma (CCRCC), a pancreatic cancer, a renal cancer, a urothelial cancer or an adenocarcinoma to the liver. 59. The method of embodiment 58, wherein the prostate cancer is a refractory prostate cancer, a 15 prostatic intraepithelial neoplasia, an androgen independent prostate cancer, or a malignant prostate cancer. 60. The method of embodiment 57, wherein the hematological malignancy is acute myeloid leukemia (AML), myelodysplastic syndrome (MDS), acute lymphocytic leukemia (ALL), diffuse large B-cell lymphoma (DLBCL), chronic myeloid leukemia (CML) or blastic 20 plasmacytoid dendritic cell neoplasm (DPDCN). 61. The method of any one of embodiments 56-60, wherein the antibody is administered in combination with a second therapeutic agent. 62. The antibody of any one of embodiments 1-50 for use in therapy. 63. An anti-idiotypic antibody binding to the antibody of any one of embodiments 1-50. 25 2026204725   18 Jun 2026 EXAMPLES 1 De novo generation and functional characterization of anti-CD3 mAbs 1-1 Immunization of OmniRats® with CD3 antigens to generate CD3 monoclonal antibodies 5 OmniRats® were immunized with proprietary vectors (Aldevron, Fargo, North Dakota, USA) encoding for: human CD3e and human CD3d; cynomolgus CD3e and cynomolgus CD3d. Animals received alternating boosts with human and cynomolgus DNA. From the 6th application on, the animals received optimized vectors with the same insert. Cells from lymph nodes were fused with the Ag8 myeloma cell line. 40 million cells from fusion BLW were put on three 96 10 well plates following IgM depletion. 133 million cells from fusion BLX were put on nine 96-well plates without IgM depletion. Hybridoma supernatants from fusions BLW (with magnetic bead depletion of lymphocytes) and BLX (without magnetic bead depletion of lymphocytes) were analyzed a) by a cell-based ELISA (CELISA) on cells transiently transfected with human and cynomolgus cDNA 15 cloned into screening vectors: pOPT-CD3e-hum-epsilon-TCE.OMT + pOPT-CD3d-hum-delta.OMT, 1:1 (pOPT-CD3e / d-hum-mix) and pcDNA3.1-CD3e-cyn-delta + pcDNA3.1-CD3d-cyn-delta, 1:1 (pcDNA3.1-CD3e / d-cyn-mix). Human and cynomolgus cDNA sequences (and corresponding amino acid sequences) are provided in Table 4. For CELISA negative control, non-transfected mammalian cells were incubated with hybridoma supernatants and detected with 20 the secondary Bethyl antibody. For a CELISA transfection control, mammalian cells, transfected with the constructs described above, were detected with anti-tag antibody. Hybridoma supernatants were further analyzed by flow cytometry (FACS) on CD3 positive and CD3 negative Jurkat cells: Jurkat CD3+ (E6-1) and Jurkat CD3- (J.RT3-T3.5). For FACS negative control, CD3 negative Jurkat cells (J.RT3-T3.5), were incubated with dilution 25 buffer and detected with Southern anti-rat Ig HRP and Bethyl anti-rat IgG1, 2a, 2b, 2c- HRP secondary antibodies. The specificity of the antibodies in the hybridoma supernatants of the hybridomas from fusion BLW and fusion BLX for human and cynomolgus CD3e / d complex presented on transiently transfected cells or, in the case of the human CD3e / d complex on Jurkat CD3+ (E6-1) 2026204725   18 Jun 2026 cells, was demonstrated by CELISA on transiently transfected cells, as well as when tested in FACS on Jurkat cell lines (Table 3). No significant signal was detected for any samples in the experimental samples serving as negative controls. 5 Table 3. Test of the specificity of individual hybridoma supernatants by cell-based ELISA (top) and by flow-cytometry (bottom). CELISA values represent the relative fluorescence units (rfu) of each sample. FACS values represent the geometric means (geomean) of the relative fluorescence intensities of each sample.______________________________________________________ Cell based ELISA (relative fluorescence units) Hybridoma supernatants incubated on cells transfected with : pOPT-CD3e / d-hum-mix pcDNA3.1-CD3e / d-cyn-mix Non-transfected CHO negative control BLW: fusion with lymphocytes from immunization group MR14—379 rat 1&2 (magnetic-bead depletion of IgM+ applied) No Clone Rfu % positive Rfu % positive Rfu % positive 1 BLW-2B4 689 101 230 47 30 2 BLW-2E6 231 34 121 25 20 3 BLW-3B4 867 127 320 66 24 BLX: fusion with lymphocytes from immunization group MR14—379 rat 1&2 (without magnetic-bead depletion of IgM+) No Clone Rfu % positive Rfu % positive Rfu % positive 4 BLX-1F8 689 101 230 47 30 5 BLX-2E9 867 127 320 66 24 6 BLX-3F4 896 131 371 76 17 7 BLX-3G8 759 111 340 70 22 8 BLX-4D9 1042 153 483 99 24 9 BLX-6A2 110 16 38 8 19 Positive control 682 100 488 100 - Negative control 25 4 42 9 - Flow Cytometry (FACS) Hybridoma supernatants incubated on Jurkat cell line Jurkat CD3+ (E6-1) Jurkat CD3- (J.RT3.T3.5) negative control BLW: fusion with lymphocytes from immunization group MR14—379 rat 1&2 (magnetic-bead depletion of IgM+ applied) No Clone geomean % positive geomean % positive 1 BLW-2B4 148034 53 4012 2 BLW-2E6 7503 3 687 3 BLW-3B4 198849 72 2884 BLX: fusion with lymphocytes from immunization group MR14—379 rat 1&2 (without magnetic-bead depletion of IgM+) No Clone geomean % positive geomean % positive 4 BLX-1F8 148034 53 4012 5 BLX-2E9 198849 72 2884 6 BLX-3F4 181963 66 4613 2026204725   18 Jun 2026 7 BLX-3G8 214697 77 3096 8 BLX-4D9 25839 9 1471 9 BLX-6A2 3385 1 1219 Positive control 277338 100 2051 Negative control 869 0 599 Table 4. CD3 sequences used for immunization Human CD3d NP_000723.1 (www.uniprot.org / uniprot / P04234) (SEQ ID NO:691) Human CD3e (NP_000724.1 (www.uniprot.org / uniprot / P07766) (SEQ ID NO:636) Cyno CD3d XP_001097302 (www.uniprot.org / uniprot / Q95LI8) (SEQ ID NO:692) Cyno CD3e CD3e + TCE (www.uniprot.org / uniprot / Q95LI5)   (SEQ ID NO:693) 1-2 Cloning anti-CD3 antibodies Anti-human CD3 antibodies were generated in OmniRats (OMT, Palo Alto, California, USA). Variable region (“V region”) sequences of these clones were extracted from the genomic 5 sequences and analyzed. All sequences obtained were either human IgG heavy chain or lambda light chain and the sequences, especially LC, showed high homology. Aligning the sequences to germline showed some mutations in the framework (Fig. 1). The V-region DNA sequences were synthesized and cloned into mammalian expression vectors, heavy chain sequences into human IgG1 vector and light chain sequences into human lambda vector. Sequences are shown in 10 Tables 6 and 7. Seven mAbs were assigned protein identifiers (Table 5A). CD3B312 was chosen as the most representative clone and the heavy chain sequences were cloned into human IgG1sigma and IgG4 PAA with S228P, F234A, L235A mutations and assigned protein identifiers as shown in Table 5B. These were used to generate bispecific antibodies and to demonstrate T cell redirection functionality through cytotoxicity. 15 Table 5A. Peptide ID and protein ID of clones clone ID HC peptide ID LC peptide ID protein ID BLW-2B4 CD3H218 CD3L123 CD3B311 BLW-2E6 CD3H219 CD3L124 CD3B312 BLW-3B4 CD3H218 CD3L125 CD3B313 BLX-1F8 CD3H220 CD3L126 CD3B314 BLX-2E9 CD3H221 CD3L124 CD3B315 2026204725   18 Jun 2026 BLX-3F4 CD3H222 CD3L124 CD3B316 BLX-3G8 CD3H223 CD3L124 CD3B317 Table 5B. CD3B312 was chosen as the most representative clone and the heavy chain sequences were cloned into human IgG1sigma and IgG4 PAA with mutations and assigned protein identifiers. IgG1 IgG1sigma IgG4PAA CD3B312 CD3B337 CD3B373 Table 6. Heavy chain and light chain sequences of 7 monoclonal CD3 antibodies Protein AA ID Heavy Chain Amino Acid Sequence SEQ ID NO. Light Chain Amino Acid Sequence SEQ ID NO. CD3B311 (BLW-2B4) HC Peptide ID: CD3H218 QVQLQQSGPGLVKPSQTLSLTCAIS GDSVFNNNAAWTWIRQSPSRGLEW LGRTYYRSKWLYDYAVSVKSRITV NPDTSRNQFTLQLKSVTPEDTALYY CSRGYSSSFDYWGQGTLVTVSSAST KGPSVFPLAPSSKSTSGGTAALGCL VKDYFPEPVTVSWNSGALTSGVHTF PAVLQSSGLYSLSSVVTVPSSSLGTQ TYICNVNHKPSNTKVDKKVEPKSCD KTHTCPPCPAPELLGGPSVFLFPPKP KDTLMISRTPEVTCVVVDVSHEDPE VKFNWYVDGVEVHNAKTKPREEQ YNSTYRVVSVLTVLHQDWLNGKEY KCKVSNKALPAPIEKTISKAKGQPRE PQVYTLPPSREEMTKNQVSLTCLVK GFYPSDIAVEWESNGQPENNYKTTP PVLDSDGSFFLYSKLTVDKSRWQQG NVFSCSVMHEALHNHYTQKSLSLSP GK (637) LC Peptide ID: CD3L123 QSALTQPASVSGSPGQSITIS CTGTSSNIGTYKFVSWYQQH PDKAPKVLLYEVSKRPSGVS SRFSGSKSGNTASLTISGLQA EDQADYHCCSYAGSGTLLF GGGTKLTVLGQPKAAPSVTL FPPSSEELQANKATLVCLISD FYPGAVTVAWKADSSPVKA GVETTTPSKQSNNKYAASSY LSLTPEQWKSHRSYSCQVTH EGSTVEKTVAPTECS (645) CD3B312 HC Peptide ID: CD3H219 LC Peptide ID: CD3L124 2026204725   18 Jun 2026 (BLW-2E6) QVRLQQSGPGLVKPSQTLSLTCAISG DSVFNNNAAWSWIRQSPSRGLEWL GRTYYRSKWLYDYAVTVKSRITVN PDTSRNQFTLQLTSVTPEDTALYYC ARGYSSSFDYWGQGTLVTVSSASTK GPSVFPLAPSSKSTSGGTAALGCLV KDYFPEPVTVSWNSGALTSGVHTFP AVLQSSGLYSLSSVVTVPSSSLGTQT YICNVNHKPSNTKVDKKVEPKSCD KTHTCPPCPAPELLGGPSVFLFPPKP KDTLMISRTPEVTCVVVDVSHEDPE VKFNWYVDGVEVHNAKTKPREEQ YNSTYRVVSVLTVLHQDWLNGKEY KCKVSNKALPAPIEKTISKAKGQPRE PQVYTLPPSREEMTKNQVSLTCLVK GFYPSDIAVEWESNGQPENNYKTTP PVLDSDGSFFLYSKLTVDKSRWQQG NVFSCSVMHEALHNHYTQKSLSLSP GK (640) QSALTQPASVSGSPGQSITIS CTGTSSNIGTYKFVSWYQQH PDKAPKVLLYEVSKRPSGVS SRFSGSKSGNTASLTISGLQA EDQADYHCCSYAGSGTLLF GGGTKLTVLGQPKAAPSVTL FPPSSEELQANKATLVCLISD FYPGAVTVAWKADSSPVKA GVETTTPSKQSNNKYAASSY LSLTPEQWKSHRSYSCQVTH EGSTVEKTVAPTECS (646) CD3B313 (BLW-3B4) HC Peptide ID: CD3H218 QVQLQQSGPGLVKPSQTLSLTCAIS GDSVFNNNGAWSWIRQSPSRGLEW LGRTYYRSKWLYDYAVSVKSRITV NPDTSRNQFTLQLNSVTPEDTALYY CARGYSSSFDYWGQGTLVTVSSAST KGPSVFPLAPSSKSTSGGTAALGCL VKDYFPEPVTVSWNSGALTSGVHTF PAVLQSSGLYSLSSVVTVPSSSLGTQ TYICNVNHKPSNTKVDKKVEPKSCD KTHTCPPCPAPELLGGPSVFLFPPKP KDTLMISRTPEVTCVVVDVSHEDPE VKFNWYVDGVEVHNAKTKPREEQ YNSTYRVVSVLTVLHQDWLNGKEY KCKVSNKALPAPIEKTISKAKGQPRE PQVYTLPPSREEMTKNQVSLTCLVK GFYPSDIAVEWESNGQPENNYKTTP PVLDSDGSFFLYSKLTVDKSRWQQG NVFSCSVMHEALHNHYTQKSLSLSP GK (638) LC Peptide ID: CD3L125 QSALTQPASVSGSPGQSITIS CTGTSSNIGTYKFVSWYQQH PDKAPKVLLYEVSKRPSGVS SRFSGSKSGNTASLTISGLQA EDQADYHCCSYAGSGTLLF GGGTKLTVLGQPKAAPSVTL FPPSSEELQANKATLVCLISD FYPGAVTVAWKADSSPVKA GVETTTPSKQSNNKYAASSY LSLTPEQWKSHRSYSCQVTH EGSTVEKTVAPTECS (649) CD3B314 HC Peptide ID: CD3H220 LC Peptide ID: CD3L126 2026204725   18 Jun 2026 (BLX-1F8) QVQLQQSGPGLVKPSQTLSLTCAIS GDSVFNNNAAWSWIRQSPSRGLEW LGRTYYRSKWLYDYAVSVKSRITV NPDTSRNQFTLQLKSVTPEDTALYY CSRGYSSSFDYWGQGTLVTVSSAST KGPSVFPLAPSSKSTSGGTAALGCL VKDYFPEPVTVSWNSGALTSGVHTF PAVLQSSGLYSLSSVVTVPSSSLGTQ TYICNVNHKPSNTKVDKKVEPKSCD KTHTCPPCPAPELLGGPSVFLFPPKP KDTLMISRTPEVTCVVVDVSHEDPE VKFNWYVDGVEVHNAKTKPREEQ YNSTYRVVSVLTVLHQDWLNGKEY KCKVSNKALPAPIEKTISKAKGQPRE PQVYTLPPSREEMTKNQVSLTCLVK GFYPSDIAVEWESNGQPENNYKTTP PVLDSDGSFFLYSKLTVDKSRWQQG NVFSCSVMHEALHNHYTQKSLSLSP GK (641) QSALTQPASVSGSPGQSITIS CTGTSSDIGTYKFVSWYQQH PDKAPKVLLYEVSKRPSGVS SRFSGSKSDNTASLTISGLQA EDQADYHCCSYAGSGTLLF GGGTKLTVLGQPKAAPSVTL FPPSSEELQANKATLVCLISD FYPGAVTVAWKADSSPVKA GVETTTPSKQSNNKYAASSY LSLTPEQWKSHRSYSCQVTH EGSTVEKTVAPTECS (650) CD3B315 (BLX-2E9) HC Peptide ID: CD3H221 QVQLQQSGPGLVKPSQTLSLTCAIS GDSVFNNNAAWSWIRQSPSRGLEW LGRTYYRSKWLYDYAVSVKSRITV NPDTSRNQFTLQLNSVTPEDTALYY CVRGYSSSFDYWGQGTLVTVSSAST KGPSVFPLAPSSKSTSGGTAALGCL VKDYFPEPVTVSWNSGALTSGVHTF PAVLQSSGLYSLSSVVTVPSSSLGTQ TYICNVNHKPSNTKVDKKVEPKSCD KTHTCPPCPAPELLGGPSVFLFPPKP KDTLMISRTPEVTCVVVDVSHEDPE VKFNWYVDGVEVHNAKTKPREEQ YNSTYRVVSVLTVLHQDWLNGKEY KCKVSNKALPAPIEKTISKAKGQPRE PQVYTLPPSREEMTKNQVSLTCLVK GFYPSDIAVEWESNGQPENNYKTTP PVLDSDGSFFLYSKLTVDKSRWQQG NVFSCSVMHEALHNHYTQKSLSLSP GK (642) LC Peptide ID: CD3L124 QSALTQPASVSGSPGQSITIS CTGTSRDIGTYKFVSWYQQH PDKAPKVLLYEVSKRPSGVS SRFSGSKSGNTASLTISGLQA EDQADYHCCSYAGSGTLLF GGGTKLTVLGQPKAAPSVTL FPPSSEELQANKATLVCLISD FYPGAVTVAWKADSSPVKA GVETTTPSKQSNNKYAASSY LSLTPEQWKSHRSYSCQVTH EGSTVEKTVAPTECS (647) CD3B316 HC Peptide ID: CD3H222 LC Peptide ID: CD3L124 2026204725   18 Jun 2026 (BLX-3F4) QVQLQQSGPRLVRPSQTLSLTCAISG DSVFNNNAAWSWIRQSPSRGLEWL GRTYYRSKWLYDYAVSVKSRITVN PDTSRNQFTLQLNSVTPEDTALYYC ARGYSSSFDYWGQGTLVTVSSASTK GPSVFPLAPSSKSTSGGTAALGCLV KDYFPEPVTVSWNSGALTSGVHTFP AVLQSSGLYSLSSVVTVPSSSLGTQT YICNVNHKPSNTKVDKKVEPKSCD KTHTCPPCPAPELLGGPSVFLFPPKP (643) QSALTQPASVSGSPGQSITIS CTGTSSNIGTYKFVSWYQQH PDKAPKVLLYEVSKRPSGVS SRFSGSKSGNTASLTISGLQA EDQADYHCCSYAGSGTLLF GGGTKLTVLGQPKAAPSVTL (646) CD3B317 (BLX-3G8) KDTLMISRTPEVTCVVVDVSHEDPE VKFNWYVDGVEVHNAKTKPREEQ YNSTYRVVSVLTVLHQDWLNGKEY KCKVSNKALPAPIEKTISKAKGQPRE PQVYTLPPSREEMTKNQVSLTCLVK GFYPSDIAVEWESNGQPENNYKTTP PVLDSDGSFFLYSKLTVDKSRWQQG NVFSCSVMHEALHNHYTQKSLSLSP GK HC Peptide ID: CD3H223 QVQLQQSGPGLVKPSQTLSLTCAIS GDSVFNNNAAWSWIRQSPSRGLEW LGRTYYRSKWLYDYAVSVKSRITV NPDTSRNQFTLQLNSVTPEDTALYY CVRGYSSSFDYWGQGTLVTVSSAST KGPSVFPLAPSSKSTSGGTAALGCL VKDYFPEPVTVSWNSGALTSGVHTF PAVLQSSGLYSLSSVVTVPSSSLGTQ TYICNVNHKPSNTKVDKKVEPKSCD KTHTCPPCPAPELLGGPSVFLFPPKP (644) FPPSSEELQANKATLVCLISD FYPGAVTVAWKADSSPVKA GVETTTPSKQSNNKYAASSY LSLTPEQWKSHRSYSCQVTH EGSTVEKTVAPTECS LC Peptide ID: CD3L124 QSALTQPASVSGSPGQSITIS CTGTSRDIGTYKFVSWYQQH PDKAPKVLLYEVNKRPSGVS SRFSGSKSGNTASLTISGLQA EDQADYHCCSYAGSGTLLF GGGTKLTVLGQPKAAPSVTL (648) KDTLMISRTPEVTCVVVDVSHEDPE VKFNWYVDGVEVHNAKTKPREEQ YNSTYRVVSVLTVLHQDWLNGKEY KCKVSNKALPAPIEKTISKAKGQPRE PQVYTLPPSREEMTKNQVSLTCLVK GFYPSDIAVEWESNGQPENNYKTTP PVLDSDGSFFLYSKLTVDKSRWQQG NVFSCSVMHEALHNHYTQKSLSLSP GK FPPSSEELQANKATLVCLISD FYPGAVTVAWKADSSPVKA GVETTTPSKQSNNKYAASSY LSLTPEQWKSHRSYSCQVTH EGSTVEKTVAPTECS Table 7A. VH and VL sequences with HC and LC isotype of 7 monoclonal CD3 antibodies from the first panel of 9 described above (see Table 3). All HC isotypes were huIgG1_G1m(17). All LC isotypes were huLambda 2. Fab ID Peptide ID VH (SEQ ID NO:) Peptide ID VL (SEQ ID NO:) CD3B311 CD3H218 qvqlqqsgpglvkpsqtlslt caisgdsvfnnnaawswirqs psrglewlgrtyyrskwlydy avsvksritvnpdtsrnqftl CD3L123 qsaltqpasvsgspgqsitisct gtsrdigtykfvswyqqhpdkap kvllyevnkrpsgvssrfsgsks 2026204725   18 Jun 2026 qlnsvtpedtalyycvrgyss sfdywgqgtlvtvss (651) gntasltisglqaedqadyhccs yagsgtllfgggtkltvl (658) CD3B312 CD3H219 qvqlqqsgprlvrpsqtlslt caisgdsvfnnnaawswirqs psrglewlgrtyyrskwlydy avsvksritvnpdtsrnqftl qlnsvtpedtalyycargyss sfdywgqgtlvtvss (652) CD3L124 qsaltqpasvsgspgqsitisct gtssnigtykfvswyqqhpdkap kvllyevskrpsgvssrfsgsks gntasltisglqaedqadyhccs yagsgtllfgggtkltvl (659) CD3B313 CD3H218 qvqlqqsgpglvkpsqtlslt caisgdsvfnnnaawswirqs psrglewlgrtyyrskwlydy avsvksritvnpdtsrnqftl qlnsvtpedtalyycvrgyss sfdywgqgtlvtvss (687) CD3L124 qsaltqpasvsgspgqsitisct gtsrdigtykfvswyqqhpdkap kvllyevskrpsgvssrfsgsks gntasltisglqaedqadyhccs yagsgtllfgggtkltvl (688) CD3B314 CD3H220 qvqlqqsgpglvkpsqtlslt caisgdsvfnnnaawswirqs psrglewlgrtyyrskwlydy avsvksritvnpdtsrnqftl qlksvtpedtalyycsrgyss sfdywgqgtlvtvss (653) CD3L126 qsaltqpasvsgspgqsitisct gtssdigtykfvswyqqhpdkap kvllyevskrpsgvssrfsgsks dntasltisglqaedqadyhccs yagsgtllfgggtkltvl (660) CD3B315 CD3H221 qvqlqqsgpglvkpsqtlslt caisgdsvfnnngawswirqs psrglewlgrtyyrskwlydy avsvksritvnpdtsrnqftl qlnsvtpedtalyycargyss sfdywgqgtlvtvss (654) CD3L124 qsaltqpasvsgspgqsitisct gtssnigtykfvswyqqhpdkap kvllyevskrpsgvssrfsgsks gntasltisglqaedqadyhccs yagsgtllfgggtkltvl (659) CD3B316 CD3H222 qvrlqqsgpglvkpsqtlslt caisgdsvfnnnaawswirqs psrglewlgrtyyrskwlydy avtvksritvnpdtsrnqftl qltsvtpedtalyycargyss sfdywgqgtlvtvss (655) CD3L124 qsaltqpasvsgspgqsitisct gtssnigtykfvswyqqhpdkap kvllyevskrpsgvssrfsgsks gntasltisglqaedqadyhccs yagsgtllfgggtkltvl (659) CD3B317 CD3H223 qvqlqqsgpglvkpsqtlslt caisgdsvfnnnaawtwirqs psrglewlgrtyyrskwlydy avsvksritvnpdtsrnqftl qlksvtpedtalyycsrgyss sfdywgqgtlvtvss (656) CD3L124 qsaltqpasvsgspgqsitisct gtssnigtykfvswyqqhpdkap kvllyevskrpsgvssrfsgsks gntasltisglqaedqadyhccs yagsgtllfgggtkltvl (659) 2026204725   18 Jun 2026 Table 7B. CDR sequences with HC and LC isotype of 7 monoclonal CD3 antibodies from the first panel of 9 described above (see Table 3). Sequences are defined according to Kabat. All HC isotypes were huIgGl G1m(17). All LC isotypes were huLambda 2. CDRs (SEQ ID NO: ) FAB ID Peptide ID CDR1 CDR2 CDR3 CD3B311 HC CD3H218 NNNAAWS (662) RTYYRSKWLYDYAVSVKS (663) GYSSSFDY (664) LC CD3L123 TGTSRDIGTYKFVS (667) EVNKRPS (669) CSYAGSGTLL (670) CD3B312 HC CD3H219 NNNAAWS (662) RTYYRSKWLYDYAVSVKS (663) GYSSSFDY (664) LC CD3L124 TGTSSNIGTYKFVS (671) EVSKRPS (673) CSYAGSGTLL (670) CD3B313 HC CD3H218 NNNAAWS (662) RTYYRSKWLYDYAVSVKS (663) GYSSSFDY (664) LC CD3L124 TGTSRDIGTYKFVS (672) EVSKRPS (673) CSYAGSGTLL (670) CD3B314 HC CD3H220 NNNAAWS (662) RTYYRSKWLYDYAVSVKS (663) GYSSSFDY (664) LC CD3L126 TGTSSDIGTYKFVS (674) EVSKRPS (673) CSYAGSGTLL (670) CD3B315 HC CD3H221 NNNGAWS (665) RTYYRSKWLYDYAVSVKS (663) GYSSSFDY (664) LC CD3L124 TGTSSNIGTYKFVS (671) EVSKRPS (673) CSYAGSGTLL (670) CD3B316 HC CD3H222 NNNAAWS (662) RTYYRSKWLYDYAVTVKS (689) GYSSSFDY (664) LC CD3L124 TGTSSNIGTYKFVS (671) EVSKRPS (673) CSYAGSGTLL (670) CD3B317 HC CD3H223 NNNAAWT (666) RTYYRSKWLYDYAVSVKS (663) GYSSSFDY (664) LC CD3L124 TGTSSNIGTYKFVS (671) EVSKRPS (673) CSYAGSGTLL (670) 5              1-3 Screening of hybridomas for binding to human and cynomolgus purified T cells A cell-based binding assay was designed to assess the binding capacity of individual rat hybridoma supernatants to human (Fig. 2) and cynomolgus (Fig. 3) purified CD3+ T lymphocytes. The T cells were counted, diluted to 1*10A6 cells / mL and incubated with 0.5 10 ul / mL of Live / Dead Fixable Green Dead Cell Stain (Life Technologies, L-2301). Next the cells were aliquoted into a U-bottom (Falcon 353077) plate at 100ul / well (1x10A5 cells / well). The plates were centrifuged at 300g for 5 minutes to pellet the cells and the supernatant removed. The plate was vortexed briefly to resuspend the cells. The hybridoma supernatants were diluted 2026204725   18 Jun 2026 in FACS staining buffer (BSA, BD Biosciences 554657) to 4.5 pg / mL and then serially diluted 6 times at 1:3 dilutions to the lowest concentration of 0.006 pg / mL. A positive control of mouse anti-human CD3 (SP34-2, BD Biosciences 551916) and negative isotype control (mouse IgG1 BD Biosciences 556648) were also diluted to 4.5 pg / mL. 50pl of each sample was added to the 5 T cells and incubated at 4°C for 1 hour. The cells were washed once with staining buffer and secondary AF647 Goat anti-mouse IgG (Life Technologies, A21235) or AF647 goat anti-rat IgG (Life Technologies, A21247) was added at 10 pg / mL in 50 pl was added according to the appropriate species (anti-rat for hybridoma samples and anti-mouse for the control antibodies). The plates were incubated at 4°C for 45 minutes and washed with staining buffer twice. The cells 10 were resuspended in 25 pl of running buffer (staining buffer + 1 mM EDTA (Life technologies, AM9260G) + 0.1% pluronic F-68 (Life Technologies 24040-032)) and read on the Intellicyt system (Intellicyt Corp.). The results are shown in Figs. 2 and 3. In other experiments, purified human T cells were plated at 1.1*10A5 cells / well in U-bottom plates. The plates were centrifuged at 300g for 5 minutes to pellet the cells and the 15 supernatant removed. The plate was vortexed briefly to resuspend the cells. The hybridoma supernatants were diluted in FACS staining buffer (BSA, BD Biosciences 554657) to 30ug / mL and then serially diluted 11 times at 1:3 dilutions to the lowest concentration of 0.00017ug / mL. 50ul of each sample was added to the T cells and incubated at 4C for 1 hour. The cells were washed once with staining buffer and secondary Dylight 650 goat anti-rat IgG (Bethyl, A110- 20 239D5) was added at 10ug / mL in 50ul was added. The plates were incubated at 4C for 1 hour and washed with staining buffer twice. The cells were resuspended in 30ul of FACS buffer and read on the Hypercyte flow cytometer (Intellicyt Corp.). Representative dose-response curves for the anti-CD3 clones binding to primary human T cells are shown in Fig. 5. Representative competition binding curves with SP34-2 (a commercial anti-human CD3 25 antibody which has a known epitope and is cross-reactive with cynomolgus CD3) are shown in Fig. 6. The initial screening results are summarized in Table 8. Six of the clones showed positive binding and also compete with SP34-2 for binding to primary human T cells. 2026204725   18 Jun 2026 1-4 Competition assay with SP34-2 commercial CD3 antibody The hybridoma supernatants were also assessed for their ability to compete with commercial anti-human CD3 antibody SP34-2 which has a known epitope and is cross-reactive with cynomolgus CD3. First a concentration titration curve of AF488 fluorescently labelled 5 SP34-2 (BD, 557705) was performed to determine a fixed concentration of SP34-2 for the following competition assays. Briefly, human purified T cells were diluted to 1x10A6 cell / mL in PBS. Fc block (Human TruStain Fc Block, Biolegend, 422302) was added at 5pL / 100pL cells and plated at 100pL / well in U-bottom plates. AF488 SP34-2 and the AF488 labelled isotype control (AF488 mouse IgG1, BD, 400129) were serially diluted from 50pg / mL to 0.049pg / mL in 10 a 1:2 dilution scheme. The plates were centrifuged at 300xg for 5 minutes to pellet the cells and the supernatant removed. The plate was gently vortexed briefly to resuspend the cells. 50 pL of each AF488 SP34-2 dilution was added to the cells and incubated at 4C for 1 hour. The plates were washed with staining buffer twice and once with running buffer (staining buffer + 1mM EDTA (Life technologies, AM9260G) + 0.1% pluronic F-68 (Life Technologies 24040-032)). 15 The cells were resuspended in 25pL of running buffer and read on the HTFC Screening System (IntelliCyt Corporation). Based on the dose response curve, a fixed concentration of 2ug / mL SP34-2 was chosen for the competition assay. Seven hybridomas that demonstrated binding to purified T cells were assayed for competition with SP34-2 binding to human T cells (Fig. 4). Control antibodies were included in 20 the competition assay. Unlabeled Mouse Anti-Human CD3, SP34-2 antibody and Mouse AntiHuman CD3, UCHT1 antibody were used as positive controls and rat IgG and Mouse isotype were used as negative controls for AF488 labeled SP34-2. Purified human T cells were diluted to a concentration of 1x10A6 cells / mL in PBS. Fc block at 5pL per 100pL cells (Human TruStain Fc Block, Biolegend, 422302) and Live / Dead Fixable Far Red Dead Cell Stain at 0.5pL per mL 25 cells (Life Technologies L10120) were added to the cells and incubated for 15 minutes at 4°C. Next, 105 cells per well (1x10A5 cells / well) were aliquoted into a 96-well U-bottom plate (Falcon 353077). The plates were centrifuged at 300xg for 5 minutes to pellet the cells and the supernatant removed. The plate was gently vortexed briefly to resuspend the cells. The hybridoma supernatants and the control antibodies were diluted in FACS staining buffer (BSA, 30 BD Biosciences 554657) at 2X the desired final concentration. 35pL of the 2X hybridoma 2026204725   18 Jun 2026 supernatants and the control antibodies were mixed with 35uL of 2X AF488 SP34-2 (4pg / mL) to give the desired 1X concentration of hybridoma supernatants, 1X concentration of control antibodies and 2pg / mL AF488 SP34-2. The hybridoma supernatants and control antibodies were assayed using a 7-point titration with a concentration range. Hybridoma supernatants were 5 assayed from 200^g / mL to 0.08 ^g / mL and control antibodies were assayed from 100^g / mL to 0.04^g / mL. 50uL of the 1X hybridoma supernatants or 1X control antibodies with 2^g / mL AF488 SP34-2 were added to the T cells and incubated at 4°C for 2 hours. The plates were washed with staining buffer twice and once with running buffer (staining buffer + 1mM EDTA (Life technologies, AM9260G) + 0.1% pluronic F-68 (Life Technologies 24040-032)). The cells 10 were resuspended in 25^L of running buffer and read on the HTFC Screening System (IntelliCyt Corporation). Representative competition binding curves with SP34-2 (a commercial anti-human CD3 antibody which has a known epitope and is cross-reactive with cynomolgus CD3) are shown in Fig. 4 and Fig. 6. The initial screening results are summarized in Table 8. Six of the clones showed positive binding and also competed with SP34-2 for binding to primary human T 15 cells. As shown in Fig. 4 the seven antibodies competed with SP34-2 with similar curves. The right shift of the curves relative to the control SP34-2 indicates a weaker binding affinity. The isotype control rat IgG did not compete with SP34-2, as expected. Table 8. Summary of anti-CD3 antibody binding on primary human T cells. Anti-CD3 clones 20 BLX-4E5, BLX-5H7, BLX-8B4, BLX-8B6, BLX-8G8 and BLW-1E3 were positive for binding to human T cells and competed with SP34-2 binding______ Ab clone Binds with human T cells Competes with SP34-2 BLW-2B4 + + BLW-2E6 + + BLW-3B4 + + BLX-1F8 + + BLX-2E9 + + BLX-3F4 + + BLX-3G8 + + BLX-1G10 - - BLX-3H6 - - BLX-4E5 + + BLX-5H7 + + BLX-8B4 + + BLX-8B6 + + 2026204725   18 Jun 2026 BLX-8G8 + + BLW-1E3 + + BLW-1F1 + - BLW-2C4 - - BLW-2C11 - - BLW-2F9 - - BLW-3B5 - - BLW-3H5 - - 1-5 Screening of hybridoma hits for T cell activation as measured by CD69 upregulation A primary human and cynomolgus monkey T cell based assay was used to determine the 5 capacity of the hybridoma hits to activate T cells. This was accomplished by coating antibodies to a plate to mimic the cross-linking effect of TCR activation. Upon activation, T cells are known to upregulate the surface expression of the protein, CD69. The experiment was conducted by coating 50pJ of a iOpg / mi antibody preparation with unknown samples or controls (positive control: in house, Okt-3 BISB264.002, BD Bioscience SP-34-2 #551916; negative control: anti- i0 CD20 in house BISB266.004) to a 96 well plate (Costar #336i). The plates were incubated overnight at 4°C. The next day the plates were washed twice with PBS. Frozen primary T cells (human sourced from Biological Specialities or Hemacare; cynomolgus sourced from Worldwide Primates) were thawed, counted for viability and resuspended at 2*106 cell / ml in RPMI 1640 medium (Gibco #11875 with 10% HI FBS (Gibco #10062). 100gl of the cells was 15 added to the plate and incubated overnight (approximately 16 hours) at 37C, 5% CO2. The following day the plates were spun at 1300rpm for 3 minutes to pellet the cells and the supernatants were discarded. The cells were washed once in PBS and spun as before. 10pJ of a 2.5% solution of Live / Dead Green Fixable Dye (Life Technologies #L23101) in PBS was added to each well and incubated at room temperature and in the dark for 10 minutes. Next 50^ of a 20 1% solution of anti-CD69 AF488 (Biolegend #310916 lot #B125271) in FACS buffer (BD Biosciences #554657) was added and the plates were incubated for 45 minutes at 4°C. The plates were washed twice by pelleting the cells as before and discarding the supernatant and resuspending in 150pl of FACS buffer. After the final wash the cells were resuspended in 150pl of FACS buffer and read on the FACS Canto. As seen in Fig. 20, the positive controls cOkt3 and 2026204725   18 Jun 2026 SP34-2 induced the upregulation of CD69 on human T cells as indicated by the measured mean fluorescence intensity of the anti-CD69 staining. Only SP34-2 induced CD69 expression in the cynomolgus T cells, as it binds to a region of CD3 sequence that is conserved from monkey to man. The OKT3 anti-CD3 clone did not bind cynomolgus CD3 and did not induce CD69 5 upregulation. The negative control in both human and cynomolgus T cells was an anti-CD20 which is not expressed on T cells. Of the hybridoma clones that were tested for T cell activation, several induced CD69 expression to a similar degree as the positive control, namely 2B4, 2E6, 3B4, 1F8, 2E9, 3F4, 3G8, 4E5, 5H7, 8B4, 8G8 and 1F1. Most also bound and activated cynomolgus T cells except for 5H7, 8B4, and 8G8. 10            1-6 Framework engineering of BLW-2E6 Clones showed high homology and carried framework mutations comparing to human immunoglobulin germline sequences (Figs. 1A and 1B). Clone 2E6 was selected to adapt the standard framework sequence. All 6 mutations on HC and 7 mutations on LC were mutated back to human germline sequence, either individually or combined (Table 9). The mutated V-region 15 DNA sequences were synthesized and cloned into the same mammalian expression vectors as their parental constructs. The HC and LC constructs were paired via matrix format to generate proteins carrying individual or combinatorial mutations and protein activity was tested. V48 on LC could not be changed back to germline. All other back mutations were not critical but reduced activity to some degree. 20 Table 9. BLW-2E6 framework variants. Heavy chain back mutation to human germline peptide ID WT CD3H219 R10G CD3H225 R13K CD3H226 V73I CD3H227 R79K CD3H228 T83S CD3H229 L96V CD3H230 R10G / R13K / V73I / R79K / T83 S / L96V CD3H231 Light chain back mutation to human germline peptide ID WT CD3L124 2026204725   18 Jun 2026 D43G CD3L128 V48L CD3L129 L49M CD3L130 L50I CD3L131 S62N CD3L132 Q85E CD3L133 H89Y CD3L134 D43G / L49M / L50I / S62N / Q85E CD3L135 D43G / L49M / L50I / S62N / Q85E / H89Y CD3L137 D43G / V48L / L49M / L50I / S62N / Q85E / H89Y CD3L136 D43G / L49M / L50I / S62N / Q85E / H89Y / C91V CD3L197 Framework mutations were engineered to one hybridoma clone, BLW-2E6, resulting in 80 mutant clones, some of which are indicated in Table 10. The 80 mutant clones were assayed for binding to primary human T cells (Figs. 7 and 8). The T cells were counted, diluted to 5 1*10A6 cells / mL and incubated with 5pL Fc block (Human TruStain Fc Block, Biolegend, 422302) per 100pL cells and 0.5pJ per mL of Live / Dead Fixable Green Dead Cell Stain (Life Technologies, L-2301) per 100pL cells. Next, the cells were aliquoted into a 96-well U-bottom plate (Falcon 353077) at 100pL / well (1x10A5 cells / well). The plates were centrifuged at 300xg for 5 minutes to pellet the cells and the supernatant removed. The plate was gently vortexed 10 briefly to resuspend the cells. The hybridoma supernatants were diluted in FACS staining buffer (BSA, BD Biosciences 554657) to 7.5^g / mL, 1.5ug / mL, 0.3 pg / mL, and 0.06 pg / mL. 50pL of each sample was added to the T cells and incubated at 4°C for 1 hour. The cells were washed once with staining buffer, and 50^L of 5^g / mL secondary AF647 goat anti-Human IgG F(ab')2 (Jackson ImmunoResearch catalog 109-605-097) was added to the cells. The plates were 15 incubated at 4°C for 45 minutes and washed with staining buffer twice and once with running buffer (staining buffer + 1mM EDTA (Life technologies, AM9260G) + 0.1% pluronic F-68 (Life Technologies 24040-032)). The cells were resuspended in 25pL of running buffer and read on the HTFC Screening System (IntelliCyt Corporation). The results demonstrate that a change in the LC at position 48 abolished binding so that mutation was not carried forward. A slight 20 reduction in binding was seen in the HC with all positions returned to germline (CD3H231). 2026204725   18 Jun 2026 1-7 C91 scanning of BLW-2E6 LC Clone 2E6 and its derivatives expressed poorly and protein aggregation was observed. One residue, C91 of light chain, was predicted to have post-translational modification (PTM) risk and was mutated to all other possible amino acids to improve protein stability (Table 10). 5 The mutated V-region DNA sequences were synthesized and cloned into the same human lambda expression vector as their parental construct. The SPR results demonstrated a change to valine or leucine at position 91 did not dramatically alter binding affinity. This change was also incorporated into wild type sequence and the framework adaptation above resulting in antibodies CD3B376 (CD3H219 / CD3L150) and CD3B450 (CD3H231 / CD3L197). CD3B376 and 10 CD3B450 were cloned as IgG4PAA (IgG4 with S228P, F234A, L235A mutations). Sequence information for CD3B376 is provided below: CD3H219 HC amino acid sequence (SEQ ID NO:640): 15 QVQLQQSGPRLVRPSQTLSLTCAISGDSVFNNNAAWSWIRQSPSRGLEWLGRTYYRSKW LYDYAVSVKSRITVNPDTSRNQFTLQLNSVTPEDTALYYCARGYSSSFDYWGQGTLVTV SSASTKGPSVFPLAPCSRSTSESTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVL QSSGLYSLSSVVTVPSSSLGTKTYTCNVDHKPSNTKVDKRVESKYGPPCPPCPAPEAAG GPSVFLFPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWYVDGVEVHNAKTKPREEQ 20 FNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQPREPQVYTLPPS QEEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFLLYSKLTVD KSRWQEGNVFSCSVMHEALHNHYTQKSLSLSLGK CD3H219 HC nucleic acid sequence (SEQ ID NO: 712) 25 caggtgcagctgcagcagtctggccctagactcgtgcggccttcccagaccctg tctctgacctgtgccatctccggcgactccgtgttcaacaacaacgccgcctggtcctg gatccggcagagcccttctagaggcctggaatggctgggccggacctactaccggtcca agtggctgtacgactacgccgtgtccgtgaagtcccggatcaccgtgaaccctgacacc tcccggaaccagttcaccctgcagctgaactccgtgacccctgaggacaccgccctgta 30 ctactgcgccagaggctactcctcctccttcgactattggggccagggcaccctcgtga ccgtgtcctct 2026204725   18 Jun 2026 CD3L150 LC amino acid sequence (SEQ ID NO:676): QSALTQPASVSGSPGQSITISCTGTSSNIGTYKFVSWYQQHPDKAPKVLLYEVSKRPSG VSSRFSGSKSGNTASLTISGLQAEDQADYHCVSYAGSGTLLFGGGTKLTVLGQPKAAPS 5 VTLFPPSSEELQANKATLVCLISDFYPGAVTVAWKADSSPVKAGVETTTPSKQSNNKYA ASSYLSLTPEQWKSHRSYSCQVTHEGSTVEKTVAPTECS CD3L150 LC nucleic acid sequence (SEQ ID NO: 713) cagtctgctctgacccagcctgcctccgtgtctggctctcccggccagtccatc 10 accatcagctgtaccggcacctcctccaacatcggcacctacaagttcgtgtcctggta tcagcagcaccccgacaaggcccccaaagtgctgctgtacgaggtgtccaagcggccct ctggcgtgtcctccagattctccggctccaagtctggcaacaccgcctccctgaccatc agcggactgcaggctgaggaccaggccgactaccactgtgtgtcctacgctggctctgg caccctgctgtttggcggaggcaccaagctgaccgtgctg 15 VH amino acid sequence of CD3H219 (SEQ ID NO:652): qvqlqqsgprlvrpsqtlsltcaisgdsvfnnnaawswirqspsrglewlgrtyyrskw lydyavsvksritvnpdtsrnqftlqlnsvtpedtalyycargysssfdywgqgtlvtv ss 20 VL amino acid sequence of CD3L150 (SEQ ID NO:661): qsaltqpasvsgspgqsitisctgtssnigtykfvswyqqhpdkapkvllyevskrpsg vssrfsgsksgntasltisglqaedqadyhcVsyagsgtllfgggtkltvl 25 HCDR1 of CD3H219 (SEQ ID NO:662): NNNAAWS HCDR2 of CD3H219 (SEQ ID NO:663): RTYYRSKWLYDYAVSVKS HCDR3 of CD3H219 (SEQ ID NO:664): GYSSSFDY 30 LCDR1 of CD3L150 (SEQ ID NO:671): TGTSSNIGTYKFVS 2026204725   18 Jun 2026 LCDR2 of CD3L150 (SEQ ID NO:673): EVSKRPS LCDR3 of CD3L150 (SEQ ID NO:690): VSYAGSGTLL 5 Sequence information for CD3B450 is provided below: CD3H231 HC amino acid sequence (SEQ ID NO:675): QVQLQQSGPGLVKPSQTLSLTCAISGDSVFNNNAAWSWIRQSPSRGLEWLGRTYYRSKW LYDYAVSVKSRITINPDTSKNQFSLQLNSVTPEDTAVYYCARGYSSSFDYWGQGTLVTV 10 SSASTKGPSVFPLAPCSRSTSESTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVL QSSGLYSLSSVVTVPSSSLGTKTYTCNVDHKPSNTKVDKRVESKYGPPCPPCPAPEAAG GPSVFLFPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWYVDGVEVHNAKTKPREEQ FNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQPREPQVYTLPPS QEEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFLLYSKLTVD 15 KSRWQEGNVFSCSVMHEALHNHYTQKSLSLSLGK CD3H231 HC nucleic acid sequence (SEQ ID NO: 714): caggtgcagctgcagcagagcggccccggcctggtcaagcccagccagaccctgagcct gacctgcgccatcagcggcgacagcgtgttcaacaacaacgccgcctggtcctggatcc 20 gccagagccccagccgcggcctggagtggctgggccgcacctactaccgcagcaagtgg ctgtacgactacgccgtgtccgtgaagtcccgcatcaccatcaaccccgacaccagcaa gaaccagttctccctgcagctgaacagcgtgacccccgaggacaccgccgtgtactact gcgcccgcggctacagcagcagcttcgactactggggccagggcaccctggtcaccgtg tccagc 25 CD3L197 LC amino acid sequence (SEQ ID NO:677): QSALTQPASVSGSPGQSITISCTGTSSNIGTYKFVSWYQQHPGKAPKVMIYEVSKRPSG VSNRFSGSKSGNTASLTISGLQAEDEADYYCVSYAGSGTLLFGGGTKLTVLGQPKAAPS VTLFPPSSEELQANKATLVCLISDFYPGAVTVAWKADSSPVKAGVETTTPSKQSNNKYA 30 ASSYLSLTPEQWKSHRSYSCQVTHEGSTVEKTVAPTECS CD3L197 LC nucleic acid sequence (SEQ ID NO: 715): 2026204725   18 Jun 2026 Cagtctgctctgacccagcctgcctccgtgtctggctctcccggccagtccatcaccat cagctgtaccggcacctcctccaacatcggcacctacaagttcgtgtcctggtatcagcagcac cccggcaaggcccccaaagtgatgatctacgaggtgtccaagcggccctccggcgtgtccaaca gattctccggctccaagtccggcaacaccgcctccctgacaatcagcggactgcaggccgagga 5 cgaggccgactactactgtgtgtcctacgccggctctggcaccctgctgtttggcggcggaaca aagctgaccgtgctg VH amino acid sequence of CD3H231 (SEQ ID NO:657): qvqlqqsgpglvkpsqtlsltcaisgdsvfnnnaawswirqspsrglewlgrtyyrskw 10 lydyavsvksritinpdtsknqfslqlnsvtpedtavyycargysssfdywgqgtlvtv ss VL amino acid sequence of CD3L197 (SEQ ID NO:678): QSALTQPASVSGSPGQSITISCTGTSSNIGTYKFVSWYQQHPGKAPKVMIYEVSKRPSGVSNRFSGSKSGNTAS 15 LTISGLQAEDEADYYCVSYAGSGTLLFGGGTKLTVL HCDR1 of CD3H231 (SEQ ID NO:662): NNNAAWS HCDR2 of CD3H231 (SEQ ID NO:663): RTYYRSKWLYDYAVSVKS 20 HCDR3 of CD3H231 (SEQ ID NO:664): GYSSSFDY LCDR1 of CD3L197 (SEQ ID NO:671): TGTSSNIGTYKFVS 25 LCDR2 of CD3L197 (SEQ ID NO:673): EVSKRPS LCDR3 of CD3L197 (SEQ ID NO:690): VSYAGSGTLL Table 10. Engineered variants of BLW-2E6 LC by C91 scanning C91 scanning peptide ID CD3 2E6 LC CD3L124 CD3 2E6 LC, C91S CD3L146 CD3 2E6 LC, C91G CD3L147 CD3 2E6 LC, C91E CD3L148 2026204725   18 Jun 2026 CD3 2E6 LC, C91D CD3L149 CD3 2E6 LC, C91V CD3L150 CD3 2E6 LC, C91A CD3L151 CD3 2E6 LC, C91R CD3L152 CD3 2E6 LC, C91K CD3L153 CD3 2E6 LC, C91N CD3L154 CD3 2E6 LC, C91M CD3L155 CD3 2E6 LC, C91I CD3L156 CD3 2E6 LC, C91T CD3L157 CD3 2E6 LC, C91W CD3L158 CD3 2E6 LC, C91Y CD3L159 CD3 2E6 LC, C91L CD3L160 CD3 2E6 LC, C91F CD3L161 CD3 2E6 LC, C91Q CD3L162 CD3 2E6 LC, C91H CD3L163 CD3 2E6 LC, C91P CD3L164 1-8 Binding of BLW-2E6 CD3 mAbs to hCD3£ construct by ProteOn SPR The binding of BLW-2E6 anti-CD3 mAbs with point mutations on the light and / or heavy chain(s) to a recombinant human CD3£(1-27) peptide with a C-terminal Tencon25 fusion 5 (Janssen production, referred as hCD3£(1-27)-Tn25) was measured by ProteOn SPR (Bio-Rad). Goat anti-human Fc IgG (Jackson Immunoresearch, Cat# 109-005-098) was directly immobilized via amine coupling at 30 pg / mL in acetate buffer, pH 5.0 on all 6 ligand channels in vertical orientation on GLC Sensor Chip (Bio-Rad, catalog no. 176-5011) with a flow rate of 30 pL / min in PBS containing 0.005% Tween-20. The immobilization densities averaged about 10 6000 Response Units (RU) with less than 5% variation among different channels. Five different mAbs were captured on the anti-human Fc IgG surface at 1.5 ug / ml (1000~1250 RU) in vertical ligand orientation, with the 6th ligand channel as no ligand surface control. The hCD3 £(1-27)-Tn25 at 1 pM concentration in 3-fold dilution series of 5 concentrations flew in as analyte to bind to captured mAbs in the horizontal orientation. A 6th buffer sample was also injected to 15 monitor the dissociation of captured mAb and baseline stability. The dissociation phase for all concentrations of hCD3£(1-27)-Tn25 was monitored at a flow rate of 100 pL / min for 30 minutes. The binding surface was regenerated for the next interaction cycle using a 18 second pulse of 0.8% phosphoric acid to remove the antigen and the bound mAb. The raw data were 2026204725   18 Jun 2026 processed by subtracting two sets of reference data from the response data: 1) the inter-spot signals to correct for the non-specific interactions between the Ag and the empty chip surface; 2) the buffer channel signals to correct for baseline drifting due to the dissociation of captured mAb surface over time. The processed data at all concentrations for each mAb were 5 globally fit to a 1:1 simple Langmuir binding model to extract estimates of the kinetic (kon, koff) and affinity (Kd) constants. Results are provided in Fig. 11. Table 11. Summary of the kinetics / affinities of BLW-2E6 variants binding to hCD3s(1-27)-Tn25 (N=1 Protein AA ID Heavy Chain Light Chain ka (1 / Ms) kd (1 / s) KD (nM) HC Mutation(s) LC mutation(s) C3B312 CD3H219 CD3L124 9.08E+04 1.87E-03 20.6 Wild type Wild type CD3B3 76 CD3H219 CD3L150 1.02E+05 2.37E-03 23.3 Wild type C91V N / A CD3H219 CD3L160 9.84E+04 4.05E-03 41.1 Wild type C91L N / A CD3H219 CD3L137 6.13E+04 2.02E-03 32.9 Wild type D43G / L49M / L50I / S62N / Q85E / H89Y CD3B3 34 CD3H231 CD3L137 6.96E+04 5.54E-03 79.6 R10G / R13K / V73I / R79K / T83S / L96V D43G / L49M / L50I / S62N / Q85E / H89Y N / A = not assigned 10 1-9 Binding of anti-CD3 monoclonal antibodies to human T cells In vitro binding affinity of CD3B376 and CD3B450 to human T cells was determined by flow cytometry after crossing with antigen specific target arm. A preliminary study was carried out on human T cells to determine the saturation binding constant of an anti-CD3 tracer molecule 15 (KdT). A fixed concentration of the tracer ([T]) was then used in a competition binding assay with titrated concentrations of the test mAbs. The IC50 (concentration at which 50% inhibition is achieved) value of the test molecule was used to determine the binding affinity (Kd) using the following formula: Kd = IC50 / (1+([T] / KdT)). Five human donors were used to determine the saturation binding constant (KdT) of the tracer, a commercially available AlexaFluor488 SP34-2 20 anti-CD3 (BioScience #557705) (data not shown). 2026204725   18 Jun 2026 Determining Saturation Binding Constant of Tracer (KdT) Methods: Human pan T cells were cryogenically-stored in nitrogen tanks until used. T cells were thawed, washed with PBS, re-suspended in FACS Staining buffer, counted (with viability noted), and re-suspended at 0.5*10A6 cells / mL. Far Red Live / Dead stain (Life 5 Technologies, AKA Invitrogen # L34974) (50 p.L of DMSO into a vial) was added at 1 uL per 1x10A6 cells; and FcR blocker (Miltenyi Biotec #130-059-901) (1 mL of a 1:20 dilution per 0.5x10A6 cells) were added to the cells for 10 minutes each. Cells were plated at 50,000 cells / well and washed. Increasing concentrations of the AlexaFluor488 SP-34 anti-CD3 were added to the T cells for 2 hours at 4 °C. Cells were washed to remove un-bound antibody, fixed 10 for 15 minutes, washed, and re-suspended in FACS Staining buffer containing 1mM EDTA. The iQue Intellicyte Flow Cytometer was used to measure binding. Cells were gated for T cell population, followed by cell singlets, followed by Live Cells (FL4). Geometric mean of staining (FL1) was determined for each well. The acquired mean fluorescence intensity values were plotted as a function of the 15 antibody molecule concentration and analyzed using Prism software in a one-site binding analysis (Total Binding) (Fig. 9). The software calculates the corresponding Kd value that describes the binding of the antibody molecule to a receptor (the CD3 on Human Pan T cells) that follows the law of mass action. The formula is as follows: Y = (Bmax X X) / (Kd + X); where: Bmax is maximal binding; Kd is the concentration of ligand required to reach half- 20 maximal binding. Results: Kd values were derived for each donor, and the mean value obtained. The Saturation Binding Constant (KdT) for human T-Cells was derived to be 5.6 ± 1.0 nM (n=4) and was used in the previously mentioned formula to determine Kd binding affinities. Determining Binding Affinity of anti-CD3 mAbs by Competition Assay 25 Methods: Competition binding studies were performed using bivalent antibodies against CD3: • Anti CD3 bivalents: CD3B376 and CD3B450 (Fig. 10) Human pan T cells were used to determine the binding affinity of the test mAbs. The tracer used was the commercially available AlexaFluor488 SP-34 anti-CD3 (BioScience 30 #557705) and the saturation binding constant for this tracer is described above. 2026204725   18 Jun 2026 T cells were cryogenically-stored in nitrogen tanks until used. T cells were thawed, washed with PBS, re-suspended in FACS Staining buffer, counted with viability noted, and resuspended at 0.5*106 cells / mL. Far Red Live / Dead stain (Life Technologies, AKA Invitrogen # L34974) (50 uL of DMSO into a vial) was added at 1 uL per 1x10A6 cells; and FcR blocker 5 (Miltenyi Biotec #130-059-901) (1 mL of a 1:20 dilution per 0.5x10A6 cells) was added to the cells for 10 minutes each. Cells were plated at 50,000 cells / well and washed. The mAbs (and isotype control), were serially diluted 1:2 from a starting concentration of 1000 or 200 ug / mL (2X), and a fixed concentration of the tracer (5 ug / mL; 2X) was mixed together to give 1X concentrations. Therefore, the final (1X) concentration of the tracer was 2.5 10 ug / mL = 16.6 nM. The mixture was added to the T cells for 2 hours at 4 °C. Cells were then washed to remove un-bound antibody, fixed for 15 minutes, washed, and re-suspended in FACS Staining buffer containing 1mM EDTA. The iQue Intellicyte Flow Cytometer was used to measure binding. Cells were gated for T-cell population, followed by cell singlets, followed by Live Cells (FL4). Geometric mean of 15 staining (FL1) was determined for each well. The acquired mean fluorescence intensity values were plotted as a function of the log antibody molecule concentration (converted to nM) and analyzed using Prism software in a sigmoidal dose-response (variable slope) from which the EC50 / IC50 values (in nM) are derived. The binding affinity (Kd) was derived using the following formula: Kd = IC50 / (1+([T] / KdT)). Where: Kd is the affinity of the competitor 20 (unlabeled molecule); IC50 in nM of the test compound; [T] is concentration of the tracer (16.6 nM); KdT is the Kd of the tracer determined by saturation binding (5.6 nM for human). Production of monoclonal and bispecific antibodies The bispecific CD3 antibodies of the present invention may be generated through controlled Fab-arm exchanged (FAE) as described in Labrijn et al., 2013, PNAS, vol. 110(13): 25 5145-5150; PCT Publ. WO 2011 / 131746; or in Labrijn et al., 2014, Nat Protoc, 9(10):2450-63. Briefly, in this in vitro method, two full-length parental bivalent antibodies are provided, each comprising a mutation in the antibody CH3 region that favors heterodimer formation resulting in bispecific antibodies containing a half-arm from each parental antibody. Mutations that may be used to favor heterodimer formation are F405L in one parental antibody and R409K in the other 2026204725   18 Jun 2026 prental antibody for IgG1 antibodies, or F405L and K409R one parental antibody while retaining wild-type CH3 for IgG4 antibodies. The monospecific antibodies were expressed in HEK cell lines under CMV promoters. The parental antibodies were purified using a protein A column with an elution buffer of 5 100mM NaAc pH3.5 and a neutralization puffer of 2M Tris pH 7.5 and 150 mM NaCl. The mabs were desalted using PD10 (Sephadex G25M) column and dialyzed intoD-PBS, pH 7.2 buffer. Post purification the parental antibodies were mixed under reducing conditions in 75mM cysteamine-HCl and incubated at 31°C for 4h. The recombination reactions were based on molar ratios, where a set amount of target parent (eg, 10mg, or ~71.8 nanomoles) was combined with 10 CD3 antibody (eg, ~67.8 nanomoles), where the target parent antibody was added in a 6% excess of the CD3 antibody. The recombinations were subsequently dialyzed against PBS to remove the reductant. The bispecific antibody reactions were performed with an excess of the target parent antibody (ratio) to minimize the amount of unreacted CD3 parental antibody remaining after recombination. Following the partial reduction of the parental mAbs, the reductant was removed 15 via overnight dialysis into PBS. Results: Fig. 10 shows the inhibition curves for the bivalent and monovalent anti CD3 constructs, CD3B376 and CD3B450, competing for binding against the AlexaFluor488 SP-34 anti CD3 tracer antibody. Increasing concentrations of the test anti CD3 antibodies decreased the binding of the AlexaFluor488 tracer antibody, thus decreasing the mean fluorescence intensity 20 (MFI). IC50 values were generated, and using the aforementioned formula, Kd affinities were calculated and summarized in Table 13. The CD3B376 binding site was tighter than the CD3B450 in both bivalent and monovalent form. Table 13. IC50 and Kd affinity values of the anti CD3 bivalent and monovalent CD3B376 and 25 CD3B450 constructs Construct anti CD3 IC50 (nM) K (nM) Bivalent CD3B376 29 7.3 CD3B450 60 15 Monovalent Construct CD3B376 409 103 CD3B450 1011 254 2026204725   18 Jun 2026 1-10 Conformational stability of anti-CD3 monoclonal antibodies Conformational stability of the anti-CD3 antibodies CD3B376, CD3B389 (IgG1 sigma version of CD3B376; heavy chain is SEQ ID NO: 729; light chain is SEQ ID NO: 676), CD3B450, and CD3B467 (IgG1 sigma version of CD3B450; heavy chain is SEQ ID NO: 728; 5 light chain is SEQ ID NO: 677) was determined by differential scanning calorimetry (DSC). The mid-point of thermal transition, Tm, was determined from the thermal denaturation profiles of each of the Ab candidates. Fig. 12A - Fig. 12E show the thermal denaturation profiles of the anti-CD3 antibodies in PBS. Table 14 includes a summary of the Tm and the enthalpy values (AH) for the thermal unfolding of the anti-CD3 antibodies as determined by DSC. 10 The DSC results indicate that all anti-CD3 antibodies CD3B376, CD3B389, CD3B450, and CD3B467 have folded domains. Based on the onset of unfolding, the relative stability of each antibody was as follows: CD3B389 < CD3B467 < CD3B376 < CD3B450. The anti-CD3 molecules tested by DSC displayed some differences in their thermal stability. The CD3B376 (IgG4 PAA) molecule displayed three partially unresolved transitions at 59.7, 62.4 and 69.2°C 15 with a total enthalpy of unfolding of 417.6 kcal / mol, while the CD3B450 (IgG4 PAA) molecule displayed two unresolved transitions at 62.5 and 66.3°C with a total enthalpy of unfolding of 545.1 kcal / mol. The CD3B389 (IgG1sigma) molecule displayed four transitions at 54.6, 58.2, 73.1 and 77.1°C with a total enthalpy of unfolding of 401.7 kcal / mol, while the CD3B467 (IgG1sigma) molecule displayed four transitions at 56.3, 59.6, 66.5 and 75.6°C with a total 20 enthalpy of unfolding of 406.2 kcal / mol. Table 14. Summary of the thermal transition data for the anti-CD3 antibodies in PBS. Values represent averages of duplicate runs. Sequence information is provided for HC and LC peptides (SEQ ID NOs in parentheses). CD3B376 HC: SEQ ID NO: 640 LC: SEQ ID NO: 676 CD3B450 HC: SEQ ID NO: 675 LC: SEQ ID NO: 677 CD3B389 HC: SEQ ID NO: 729 LC: SEQ ID NO: 676 CD3B467 HC: SEQ ID NO: 728 LC: SEQ ID NO: 677 Average Error Average Error Average Error Average Error Tm1 (°C) 59.7 0.1 62.5 0.9 54.6 0.1 56.3 0.1 AH1 (cal / mol) 151900.0 4200.0 158175.0 64025.0 166150.0 2450.0 98160.0 17840.0 Tm2 (°C) 62.4 0.1 66.3 0.2 58.2 0.1 59.6 0.0 2026204725   18 Jun 2026 AH2 (cal / mol) 202200.0 4300.0 386900.0 71000.0 62050.0 1290.0 72900.0 370.0 Tm3 (°C) 69.2 0.0 NA NA 73.5 0.1 66.5 0.0 AH3 (cal / mol) 63450.0 2080.0 NA NA 101900.0 1600.0 92785.0 6785.0 Tm4 (°C) NA NA NA NA 77.1 0.0 75.6 0.1 AH3 (cal / mol) NA NA NA NA 71560.0 2500.0 142400.0 4800.0 Total AH 601000.0 NA 545075.0 NA 401660.0 NA 406245.0 NA The two IgG1antibodies display lower stability compared to the corresponding IgG4 PAA antibodies (comparing the molecules with the same variable domains) with Tm of the first transition being 5-6°C lower (Fig. 13A and Fig. 13B and Table 14). 5              1-11 Crystal structure of CD3B334 Fab in complex with CD3e N-terminal peptide Anti-CD3 mAb CD3B334 (CD3H231 / CD3L137) was modified to increase the “humanness” index by replacing a number of framework residues in the antibody by the human germline residues. This procedure yielded antibody CD3B334 with the following mutations: 10 D43G / L49M / L50I / S62N / Q85E / H89Y in VL when compared to the parental VL CD3L124 and R10G / R13K / V73I / R79K / T83S / L96V in VH when compared to the paretal VH CD3H219. The His-tagged Fab fragment of CD3B334 was expressed in HEK 293Expi cells and purified using affinity and size-exclusion chromatography. The N-terminal 9-mer peptide of human CD3e was synthesized at New England Peptide (Lot V1108-19 / 21) and mixed with Fab at molar ratio 10:1 15 (excess of peptide). The complex was crystallized by the vapor-diffusion method from solution containing 4 M Na formate in 0.1 M Tris, pH 8.5. The crystals belong to the orthorhombic space group P212121 with unit cell dimensions of 66.5*69.4*100.4 A and one complex molecule in the asymmetric unit. The structure of the complex was determined at 1.8 A resolution by the molecular replacement method using the crystal structure of the Fab as a search model. 20        CD3B334 bound residues 1-6 of CD3e. The N-terminal Gln of the peptide was in the pyroglutamate form and in a hydrophobic environment, between F107 of HCDR3 and L99 of LCDR3. Two arginine residues, R52 and R56, from HCDR2 were engaged in 2026204725   18 Jun 2026 electrostatic interactions with the acidic residues of CD3. In total, 16 residues formed the CD3B334 paratope. Residues from all CDRs except LCDR2 were in direct contact (within 4 A distance) with the CD3 peptide (see Fig. 18). 5       2 PSMA Antibodies 2-1 Generation of PSMA cell lines Expression vectors presenting full-length chimpanzee PSMA (H2Q3K5_PANTR, SEQ ID NO: 49) or full length Cynomolgous monkey PSMA (EHH56646.1, SEQ ID NO: 50) were generated for use as screening tools to assess the anti-PSMA leads using an in-house expression 10 vector with the CMV promoter using standard molecular biology techniques. Vectors were transiently transfected into HEK293F cells in suspension using standard methods. Transfected 293F suspension cells were plated in growth medium plus serum to become adherent and selected for stable plasmid integration. Single cell populations were selected by serial dilution and the PSMA surface receptor expression was quantified by FACS using the (PSMAL antibody 15 (Center) affinity Purified Rabbit Polycolonal Antibody (Catalog # OAAB02483, Aviva Systems Biology) as the primary antibody with a R-PE anti-rabbit secondary antibody (Catalog # 111116-144, Jackson ImmunoResearch Laboratories, Inc.) and a rabbit polyclonal IgG (Catalog # SC-532, Santa Cruz Biotechnology) as the isotype control). Human PSMA expressing cell lines were generated using lentivirus (Genecopoeia, cat # 20 EX-G0050-Lv105-10) containing full length human PSMA (FOLH1_HUMAN, SEQ ID NO:51) and puromycin for selection of PSMA positive cells. HEK293F cells (ATCC), negative for PSMA, were transduced with Lentiviral particles to overexpress human PSMA. Following transduction, cells positively expressing PSMA and the resistance marker were selected by treating pooled cells, grown in DMEM + 10% HI FBS (Life Technologies) and supplemented 25 with varying concentrations of Puromycin (Life Technologies). In addition to the HEK generated cell lines, several commercial cell lines were used for phage panning and binding and cellular toxicity assays. LNCaP clone FGC cells (ATCC cat#CRL-1740) are a commercially available human prostate cancer cell lines. C4-2B cells were 2026204725   18 Jun 2026 originally developed at MD Anderson and are derived from LNCaP FGC grown in vivo and metastasize to bone marrow (Thalmann, et al 1994, Cancer Research 54, 2577-81). 2-2 Generation of Soluble PSMA ECD Proteins Recombinant chimpanzee PSMA Extra Cellular Domain (ECD) protein (Chimp PSMA 5 ECD, SEQ ID NO:52) was generated for panning and to assess the anti-PSMA leads using an inhouse expression vector with the CMV promoter using standard molecular biology techniques. The chimp PSMA ECD gene fragment (amino acid 44 - 750 of SEQ ID NO:49) with N-terminal signal sequence (SEQ ID NO:594), N-terminal Avitag (SEQ ID NO:595) and 6-His tags (SEQ ID NO:596) was cloned using an in-house expression vector with the CMV promoter using 10 standard molecular biology techniques and transiently expressed in 293Expi cells (Invitrogen). cDNA was prepared using gene synthesis techniques (U.S. Pat. No. 6,670,127; U.S. Pat. No. 6,521,427). Supernatants were harvested and clarified by centrifugation. The proteins were purified using a two-step purification process: 1) IMAC purification with a HisTrap HP column (GE Healthcare) and 2) size exclusion purification (Superdex 200, Ge Healthcare) where the 15 elution buffer is Dulbecco's phosphate-buffered saline, calcium, magnesium (Thermofisher, #14040) containing 0.5mM ZnCl2 to stabilize PSMA dimerization. Fractions containing the protein of interest were pooled and protein concentration was determined by A280. This material was used for binding and affinity measurements and is referred to as PSMG8. Chimp PSMA ECD was also biotinylated for panning. The BirA plasmid that was co- 20 transfected into mammalian cells to biotinylate proteins containing the Avi tag was created inhouse. The BirA coding region (SEQ ID NO:597) was fused to the signal peptide from mouse IgG heavy chain (SEQ ID NO:598), and an ER retention signal (KDEL (SEQ ID NO: 716)) was added to the C-terminus to generate the BirA plasmid (SEQ ID NO:599). The constructed gene was cloned into an expression vector under the control of the CMV promoter. To produce 25 biotinylated PSMA antigen, the PSMA plasmid DNA was added in a 4-fold excess (w / w) to the BirA plasmid into the transfection mix. Biotinylation of the Chimp PSMA ECD protein was performed via the Avi tag by cotransfection of a BirA expression construct and the resulting secreted protein was purified using a two-step purification process: 1) IMAC purification with a HisTrap HP column (GE 30 Healthcare) and 2) size exclusion purification (Superdex 200, Ge Healthcare) where the elution 2026204725   18 Jun 2026 buffer is Dulbecco's phosphate-buffered saline, calcium, magnesium (Thermofisher, #14040) containing 0.5mM ZnCl2 to stabilize PSMA dimerization. The protein was tested for endotoxin prior to use in phage panning studies. Recombinant cynomolgous monkey PSMA extracellular domain (ECD) protein (cyno 5 PSMA ECD, SEQ ID NO:53), corresponding to amino acids 44-750 of SEQ ID NO:50 with N-terminal signal (SEQ ID NO:594), N-terminal Avi- (SEQ ID NO:595) and 6His- (SEQ ID NO:596) tags was cloned and expressed as described previously for the chimp PSMA ECD. Biotinylation of the cyno PSMA ECD protein was performed via the Avi tag by cotransfection of a BirA expression construct and the resulting secreted protein was purified by a two-step 10 purification using IMAC HisTrap HP column (GE Healthcare) and MonoAvidin columns. The protein was tested for endotoxin prior to use in phage panning studies. This material was also used for binding and affinity measurements and is referred to as PSMG1. A second recombinant cyno PSMA ECD protein (Cyno PSMA Fc, SEQ ID NO:54) with an IgG1 Fc (SEQ ID NO:593) was cloned and expressed using an in-house expression vector 15 with the CMV promoter using standard molecular biology techniques. CynoPSMA Fc protein was transiently expressed in 293HEK-expi cells. Transient transfection of PSMG3 in HEK293 Expi cells were harvested 5 days after transfection, clarified by centrifugation (30 min, 6000 rpm) and filtered (0.2 u PES membrane, Corning). The relative amount of IgG was determined with the Octet instrument (ForteBio) using a purified known IgG (same isotype) spiked into 20 spent medium to generate the standard curve. Clarified Cyno PSMA Fc supernatant was loaded onto an equilibrated (dPBS, pH 7.2) HiTrap MabSelect Sure Protein A column (GE Healthcare) at a relative concentration of ~30 mg protein per ml of resin. After loading, the column was washed with dPBS, pH7.2 and protein eluted with 10 column volumes of 0.1 M Na-Acetate, pH 3.5. Peak fractions were pooled, 25 neutralized with 2M Tris, pH 7, and filtered (0.2u). The neutralized protein sample was dialyzed against 3 changes of dPBS containing Ca2+, Mg2+, and 0.5 mM ZnCl2, pH 7.2 overnight at 4oC. The next day, sample was removed from dialysis, filtered (0.2u) and the protein concentration determined by absorbance at 280nm on a BioTek SynergyHTTM spectrophotometer. The quality of the purified proteins was assessed by SDS-PAGE and analytical size exclusion HPLC 30 (Dionex HPLC system). Endotoxin levels were measured using a LAL assay (Pyrotell-T, Associates of Cape Cod). Purified proteins were stored at 4oC. 2026204725   18 Jun 2026 Recombinant human PSMA extracellular domain (ECD) protein (human PSMA ECD, SEQ ID NO:55), corresponding to amino acids 44-750 of SEQ ID NO:51 with N-terminal Avi-and 6His tags (SEQ ID NO: 596) was cloned, expressed and purified as described previously for the chimp and cyno PSMA ECD proteins. 5              2-3   Identification of Anti-chimp and anti-human PSMA Fabs Panning with recombinant protein A first solution panning of the de novo Human Fab-pIX libraries [Shi, L., et al J Mol Biol, 2010. 397(2): p. 385-396. WO 2009 / 085462], consisting of VH1-69, 3-23 and 5-51 heavy chain libraries paired with four human VL germline genes (A27, B3, L6, O12) libraries, was 10 performed using an alternating panning approach with one round of phage capture on Strepavidin beads (Invitrogen Cat# 112.05D, Lot# 62992920) coated with biotinylated Chimp PSMA ECD according to the manufacturer’s protocol, followed by phage capture on ProtG beads(Invitrogen, Cat#10003D) coated with Cyno-PSMA-Fc according to the manufacturer’s protocol followed by phage capture on Sera-mag Double Speed magnetic Neutravidin beads 15 (Thermo, Cat #7815-2104-011150) coated with biotinylated Chimp PSMA ECD according to the manufacturer’s protocol. This panning yielded two hits: PSMM18 and PSMM25. Whole cell panning for anti-PSMA Fabs Additional panning experiments were performed on whole cells using the Round #1 output from the chimpanzee ECD panning experiments described above or fresh de novo phage 20 libraries, as input. Briefly, phage was produced by helper phage infection and concentrated by PEG / NaCl precipitation according to standard protocols known in the art. The phage libraries were pre-cleared on untransfected parental HEK293F cells overnight at 4°C with gentle rocking. Following PEG / NaCl precipitation, the pre-cleared libraries were incubated with chimp PSMA expressing HEK293 cells or LNCAP cells with gentle rocking for 2 hr at 4°C. The removal of 25 unbound phage and the recovery of phage-bound cells was performed by Ficoll gradient, and following several wash steps with, cells carrying bound phage were incubated with 1mL of TG-1 E. coli culture at 37°C for 30 minutes without agitation. The resulting mixture was plated on 2026204725   18 Jun 2026 LB-Carbenicillin-1% Glucose plates and grown over night at 37°C. The process was then repeated for subsequent panning rounds. Conversion of phage Fab-pIX to Fab-His for generating E. coli supernatants 5 The resulting phage Fab-pIX hits were converted to Fab-His using a standard procedure. Plasmid DNA was isolated from phage panned E. coli (Plasmid Plus Maxi Kit, Qiagen cat#12963) and subjected to NheI / SpeI restriction digest. The resulting 5400 and 100bp fragments were separated on a 0.8% agarose gel and the 5400bp fragment was gel purified (MinElute PCR purification kit, Qiagen cat#28006). The purified 5400bp band was self-ligated 10 using T4 ligase and the resulting product (encoding the Fab-his fusion) was transformed back into the TG-1 E. coli strain and clonally isolated. Fab-His supernatants were generated from clones by overnight induction of cultures with 1mM IPTG. Following centrifugation of the overnight culture, clarified supernatants were ready for use in downstream assays. To determine the relative expression levels of different Fab-his supernatants, an anti-kappa (Southern Biotech 15 cat#2061-05) ELISA on serially diluted supernatants was performed. All of the clones tested exhibited similar Fab-his expression (data not shown). Cell binding of Fab-his fusions from E. coli A cell-based binding assay was designed to assess the binding capabilities of individual Fab-his fusions from E.coli supernatants to PSMA-expressing cells. Individual Fab clones were 20 isolated from the round 3 output of all panning experiments following pIX excision. Fab clones were tested for binding to chimp and cyno PSMA expressing HEK cells, as well as to human PSMA on LNCaP cells. Briefly, PSMA expressing cells were aliquoted into a V-bottom plate (CoStar 3357) at a density of 200,000 per well and incubated with (100 pl) supernatants expressing Fab fragments for 1 hour on ice. Cells were washed twice with PBS containing 2% 25 FBS, and stained with a mouse anti-human kappa-RPE antibody (Life Technologies cat# MH10514) for 1 hour on ice. Cells were washed twice with PBS containing 2% FBS and resuspended in 100pL of the same wash buffer. Plates were read on a BD FACS Array flow cytometer. FACS data was analyzed in FlowJo software by live gating the healthy population of cells using forward scatter and side scatter, and then analyzing the cells within this gate for PE 2026204725   18 Jun 2026 staining. Mean fluorescence intensity (MFI) was calculated and exported into Microsoft Excel. Fab clones that exhibited binding > 3 times background for all three species of PSMA (cyno, chimp and human), and exhibited no binding to the HEK293 cell line, were labeled as “preliminary positive”. Fabs were sequenced and moved forward for cloning into mammalian 5 expression vector for rescreening. True positives were selected from the binding of mammalian cell expressed Fab supernatants to PSMA-expressing cell lines. Preparation of Mammalian Fabs For conversion of E.coli Fab to mammalian-expressed Fab, In-Fusion HD cloning (ClonTech cat#638918) was utilized according to the manufacturer’s protocol. Briefly, 10 nucleotide sequences of clones that have passed the primary screen and are to be moved into mammalian Fab format, are loaded into the “InFu Primer Finder v1.2.3” program (software developed in-house), which generates a list of isotype-specific PCR primers used to generate PCR fragments for In-Fusion cloning into the huKappa_muIgGSP and huG1 Fab expression vectors. These vectors are in-house vectors with CMV promotors based off of pcDNA3.1. 15 Following the In-fusion process, E. coli clones were isolated, sequence verified and transfected into HEK293 cells using standard protocols. Mammalian PSMA Fabs for confirming binding to PSMA expressing cell lines were prepared by harvesting 20 ml of supernatants from transfection after 5 days. Rescreening hits from whole cell panning in mammalian sup format 20        Confirmation of mammalian expressed Fab supernatants was performed using the whole cell binding assay described previously. Binding of Fabs to human PSMA (LNCaP), chimpanzee, and cynomolgous monkey cells was tested, as well as counter screening for no binding to the parental HEK cell line. Table 19 shows the hit profile of mammalian Fab supernatant binding to PSMA-expressing cells. Many of the hits from E. coli supernatants did 25 not confirm with mammalian expressed proteins. PSMM48 showed high binding to cyno PSMA-expressing cells and some binding to chimp-PSMA expressing cells, but no binding to LNCaP cells expressing human PSMA. PSMM56 showed a similar profile, but with some binding to LNCaP cells. PSMM69 - 80 bound to LNCaP cells, but not to chimp- or cyno-PSMA expressing cells. Mammalian Fab sups PSMM52, M56 and M57, bound all three cell lines. 2026204725   18 Jun 2026 PSMM50, M51, and M54, show more chimp or cyno binding. M58 showed slight chimp and cyno binding. Table 19. Hit profile of Mammalian Fab protein binding to PSMA-expressing cells measured by Geo-MFI (Mean Fluoresent Instensity) Fab ID (Fab DNA ID) cyno chimp LNCaP Parent HEK PSMB10 (PSMM10) 244 81.6 - 248 PSMB11 (PSMM11) 19 6.6 - 8.14 PSMB12 (PSMM12) 31.6 8.05 - 12.6 PSMB13 (PSMM13) 57.8 18.2 - 50.5 PSMB14 (PSMM14) 32.6 13.1 - 22.2 PSMB15 (PSMM15) 40.4 18.5 - 38 PSMB16 (PSMM16) 175 220 - 6.39 PSMB17 (PSMM17) 34.9 22.4 - 40.1 PSMB18 (PSMM18) 696 439 - 8.71 PSMB19 (PSMM19) 53.7 - 5.15 4.47 PSMB20 (PSMM20) 5.75 - 5.85 41.3 PSMB21 (PSMM21) 94.4 - 20.7 372 PSMB22 (PSMM22) 9.07 - 7.92 54.9 PSMB23 (PSMM23) 16.4 - 6.66 164 PSMB24 (PSMM24) 14.6 9.6 4.09 3.96 PSMB25 (PSMM25) 15.2 11.3 16.9 4.09 PSMB26 (PSMM26) 9.48 - 7.26 114 PSMB27 (PSMM27) 20 - 7.56 136 PSMB28 (PSMM28) 29.7 - 8.88 302 PSMB29 (PSMM29) 6.87 - 5.7 72.8 PSMB30 (PSMM30) 5.16 - 4.58 45 PSMB31 (PSMM31) 5.99 - - 25.5 PSMB32 (PSMM32) 4.81 - - 27.1 PSMB33 (PSMM33) 5.14 - - 40.1 PSMB34 (PSMM34) 17.9 - - 107 PSMB35 (PSMM35) 58.5 - - 231 PSMB36 (PSMM36) 5.05 - - 6.96 PSMB37 (PSMM37) 23.4 - - 178 PSMB38 (PSMM38) 4.05 - - 7.7 PSMB39 (PSMM39) 10.2 - - 166 2026204725   18 Jun 2026 PSMB40 (PSMM40) 66.9 - - 348 PSMB41 (PSMM41) 5.39 - - 12 PSMB42 (PSMM42) 7.35 - - 25.8 PSMB43 (PSMM43) 8.73 - - 7.18 PSMB44 (PSMM44) 12.6 - - 48.9 PSMB45 (PSMM45) 22.4 - - 43.1 PSMB46 (PSMM46) 3.88 - - 5.29 PSMB47 (PSMM48) 101 25.5 3.46 2.85 PSMB48 (PSMM49) 2.72 3.18 2.68 2.72 PSMB49 (PSMM50) 51.6 22 3.22 3.48 PSMB51 (PSMM52) 285 231 41.5 2.68 PSMB52 (PSMM53) 39.2 6.89 2.67 2.56 PSMB53 (PSMM54) 27.6 17.8 4 2.6 PSMB54 (PSMM55) 2.7 2.75 2.65 2.79 PSMB55 (PSMM56) 226 180 17.2 2.58 PSMB56 (PSMM57) 95.6 34.7 24.5 2.52 PSMB57 (PSMM58) 19.8 11 3.26 2.68 PSMB58 (PSMM59) 121 192 25.3 2.67 PSMB59 (PSMM60) 4.96 9.69 6.04 3 PSMB60 (PSMM61) 2.28 3.07 87.3 4.64 PSMB61 (PSMM62) 2.1 3.16 135 2.98 PSMB62 (PSMM63) 7.17 4.43 54.9 9.09 PSMB63 (PSMM64) 2.07 2.95 27 2.82 PSMB64 (PSMM65) 2.39 3.26 70.5 3.05 PSMB65 (PSMM66) 2.3 3.13 32.4 4.25 PSMB66 (PSMM67) 2.14 3 24.6 2.83 PSMB67 (PSMM68) 2.23 2.95 21 2.95 PSMB68 (PSMM69) 5.44 - 134 35.3 PSMB69 (PSMM70) 2.29 3.38 25.5 3.35 PSMB70 (PSMM71) 2.22 3.49 15.5 3.26 PSMB71 (PSMM72) 2.54 4.4 18.5 3.07 PSMB72 (PSMM73) 2.13 3.53 227 3.02 PSMB73 (PSMM74) 2.97 4.13 125 11.1 PSMB74 (PSMM75) 120 - 178 132 PSMB75 (PSMM76) 2.99 3.04 173 7.89 2026204725   18 Jun 2026 PSMB76 (PSMM77) 3.75 3.99 138 3.95 PSMB77 (PSMM78) 4.68 3.96 144 4.71 PSMB78 (PSMM79) 25.2 - 378 24.4 PSMB79 (PSMM80) 38.4 - 512 157 PSMB80 (PSMM81) 19.6 18.6 20.9 6.61 PSMB81 (PSMM82) 2.63 2.06 4.07 2.69 PSMB82 (PSMM83) 2.79 2.23 4.11 2.76 PSMB83 (PSMM84) 2.59 2.28 4.09 2.74 PSMB84 (PSMM85) 750 729 192 3.15 PSMB85 (PSMM86) 2.84 2.59 2.33 3.24 PSMB86 (PSMM87) 224 176 31.7 2.82 PSMB87 (PSMM88) 2.63 2.27 4.23 2.91 PSMB88 (PSMM89) 37.7 29.7 30.3 7.6 PSMB89 (PSMM90) 27.1 27.3 53.2 39.5 PSMB90 (PSMM91) 26.7 24.7 47.1 36.4 PSMB91 (PSMM92) 8.97 6.16 13 6.63 PSMB92 (PSMM93) 20 16.5 57.1 50 PSMB93 (PSMM94) 5.13 9.62 2.5 3.66 PSMB94 (PSMM95) 5.12 2.67 2.22 3.57 PSMB95 (PSMM96) 8.9 8.82 13.4 11.4 PSMB96 (PSMM97) 2.4 3.25 2.53 4.03 PSMB97 (PSMM98) 2.57 4.73 2.52 3.7 PSMB99 (PSMM100) 9.95 2.4 2.39 4.03 PSMB100 (PSMM101) 4.03 2.52 2.33 3.37 PSMB100 (PSMM101) 3.5 2.86 2.48 4.57 PSMB101 (PSMM102) 5.49 3.18 2.23 3.33 PSMB102 (PSMM103) 2.4 2.42 2.16 3.2 PSMB103 (PSMM104) 3.52 3.26 2.58 4.44 PSMB104 (PSMM105) 2.15 2.5 2.34 3.95 PSMB105 (PSMM106) 2.03 2.39 2.18 3.39 PSMB106 (PSMM107) 2 2.4 2.27 3.59 PSMB107 (PSMM108) 2 2.47 2.33 3.49 PSMB108 (PSMM109) 2 2.58 2.28 3.46 PSMB109 (PSMM110) 321 326 34.9 6.11 PSMB110 (PSMM111) 2.3 2.31 2.31 3.4 2026204725   18 Jun 2026 PSMB111 (PSMM112) 2.32 2.31 - 3.21 PSMB112 (PSMM113) 6.28 5.7 2.71 3.28 PSMB113 (PSMM114) 2.82 2.95 2.32 3.29 PSMB114 (PSMM115) 2.78 2.47 4.3 3.14 PSMB115 (PSMM116) 2.66 2.59 2.2 3.14 PSMB46 (PSMM117) 4.54 3.18 2.21 4.79 PSMB67 (PSMM118) 3.95 4.3 3 6.13 PSMB74 (PSMM119) 7.94 13 3.16 12.5 PSMB78 (PSMM120) 5.08 4.79 22.3 6.82 PSMB81 (PSMM121) 3.66 3.83 3.05 5.11 PSMB82 (PSMM122) 15.1 28.4 10.8 24.3 PSMB83 (PSMM123) 37.5 42.1 3.04 4.88 PSMB85 (PSMM124) 34.6 52.9 20.7 46.8 PSMB87 (PSMM125) 4.23 3.74 2.26 4.73 PSMB89 (PSMM126) 51.8 53.1 11.7 6.27 PSMB90 (PSMM127) 42.8 30.2 7.74 5.99 PSMB91 (PSMM128) 3.9 27.6 2.37 4.32 PSMB92 (PSMM129) 45.7 37.3 12.1 7.4 PSMB93 (PSMM130) 5.13 7.85 4.11 7.82 PSMB94 (PSMM131) 3.67 3.23 2.32 4.72 PSMB95 (PSMM132) 4.05 3.64 2.56 5.57 PSMB96 (PSMM133) 3.91 4.54 2.37 4.65 PSMB97 (PSMM134) 3.22 3.16 4.08 4.22 PSMB98 (PSMM135) 15.6 12.7 2.22 4.21 PSMB99 (PSMM136) 4.08 3.26 2.22 5.04 PSMB100 (PSMM137) 5.24 3.82 2.16 4.83 PSMB101 (PSMM138) 3.84 3.14 2.23 4.52 PSMB102 (PSMM139) 4.51 3.82 2.23 4.59 PSMB103 (PSMM140) 6.81 4.27 2.21 5.41 PSMB104 (PSMM141) 7.52 4.35 2.26 4.39 PSMB105 (PSMM142) 5.03 11.2 4.87 7.28 PSMB106 (PSMM143) 3.87 3.8 2.73 4.9 PSMB107 (PSMM144) 3.3 3.35 2.3 4.64 PSMB108 (PSMM145) 6.78 3.83 2.33 4.98 PSMB110 (PSMM146) 4.03 3.23 2.28 5.3 2026204725   18 Jun 2026 PSMB111 (PSMM147) 3.71 3.26 2.36 5.11 PSMB112 (PSMM148) 4.54 3.26 2.26 4.86 PSMB113 (PSMM149) 84.3 104 51.7 94.2 PSMB114 (PSMM150) 3.31 3.26 2.21 5.14 PSMB115 (PSMM151) 3.55 3.43 2.3 4.21 Dose response curves of mammalian expressed Fabs Once mammalian expressed Fab clones were confirmed for positive binding as neat Fab supernatants to PSMA expressing cell lines, the supernatants were normalized for protein concentration by Octet or protein gel, and dose-response curves were completed to confirm 5 PSMA binding using the protocol described previously. Fig. 22 - Fig. 24 show titration curves for hits that demonstrated binding to all three PSMA-expressing cells. Figs. 22A, 22B, 22C and 22D show the titration curves for anti-PSMA panning hits vs. LNCaP cells. Figs. 23A, 23B, 23C, and 23D show the titration curves for anti-PSMA panning hits vs chimp-PSMA HEK cells. Figs. 24A, 24B, 24C, and 24D show the titration curves for anti-PSMA panning hits vs Cyno- 10 PSMA HEK cells. Binding profiles among hits were compared across cell lines expressing different species of PSMA. PSMM52 supernatant was used as a positive control across experiments. Several hits were deprioritized because of N-linked glycosylation sites in CDRs, binding to the PSMA negative parental HEK cell line, or lack of binding to PSMA positive cell lines. Eleven Fab hits remained and 10 hits were cloned into human IgG4-PAA heavy chain 15 constructs and used to generate PSMA*CD3 bispecific antibodies. These hits showed crossspecies binding within 3-fold of each other and were moved into a bispecific antibody format to be tested for T cell redirection killing of PSMA positive targets. The panning antigens for each hit is shown in Table 20. Table 20. Antigen for each of the panning hits Round 1 antigen Round 2-3 antigen Hits Hit identification Chimp PSMA ECD Cyno PSMA ECD 2 PSMM18, PSMM25 Chimp PSMA ECD Chimp PSMA HEK 9 PSMM50, PSMM52, PSMM57, PSMM59, 2026204725   18 Jun 2026 PSMM110, PSMM56, PSMM85, PSMM84 LNCaP Chimp PSMA 2 PSMM87, PSMM81 HEK Preparation of anti-PSMA mAbs A total of 12 clones that demonstrated binding to all three PSMA-expressing cells were ultimately converted to mAb IgG4 having Fc substitutions S228P, F234A, and L235A (PAA) isotype by restriction cloning. Briefly, constructs corresponding to Fab clones that have passed 5 initial screens were digested with HindIII and ApaI. Gel purified fragments were ligated into an expression vector with CMV promotervDR000215, a CMV driven expression vector containing the human IgG4-PAA Fc for full mAb expression. This allowed for rapid generation of bispecific antibodies.The expression vector previously described was used to express the Heavy and Light Chains for each PSMA mab, where both vectors were co-transfected transiently into 10 293Expi or CHO cell lines for expression of the mAb. CDR sequences of cross-species positive PSMA Fabs generated from phage panning are shown below in Table 21. VH and VL sequences of the selected Fabs are shown below in Table 22. Heavy and light chain sequences of mAbs generated from the Fabs are shown in Table 23. Table 21. CDR sequences (defined according to Kabat) of FAbs from phage panning 15 , (corresponding SEQ ID NOs are listed in parentheses)_____________________________ FAB ID CDRs (SEQ ID NO: ) CDR1 CDR2 CDR3 PSMB109 HC NAWIS (62) WINPESGRANYAQKFQG (63) ELYYLVYSTYYYAFDY (64) LC RASQSIDRWLN (65) AASSLQS (60) QQSPRYPLT (66) PSMB86 HC SYDIS (67) GIIPIEGTANYAQKFQG (68) DYPAGYGFDY (69) LC RASQSVSSSYLA (70) GASSRAT (71) QQYGSSPLT (72) PSMB84 HC SDWMS (73) AISGNGGSTEYADSVKG (74) DPYYYYDGDSYYGMDV (75) LC RASQSISSYLN AASSLQS QQSYSTP 2026204725   18 Jun 2026 (76) (60) (61) PSMB83 HC SDAMH (78) EISGSGGYTNYADSVKG (79) DSYDSSLYVGDYFDY (80) LC RASQSVSSYLA (81) DASNRAT (82) QQRSNWPLT (83) PSMB56 HC SYAIS (84) WISPYNGNANYAQKFQG (85) DSDRSYNLDY (86) LC RASQSISGWLN (87) AASSLQS (60) QQSYSTPLT (88) PSMB55 HC SYWIG (89) IIYPGDSDTRYSPSFQG (90) GLPIWYLDY (91) LC RASQSVASDLA (92) FASNRAT (93) QQSITWPFT (94) PSMB51 HC SYAIS (95) WIIPYNGNANYAQKFQG (96) VNSAALVWERLDY (97) LC RASQSIDRWLN (65) AASSLQS (60) QQSPRYPLT (66) PSMB49 HC SYAIS (84) GIIPIFGTANYAQKFQG (98) ASRVWHASYGYLDY (99) LC RASQSVSKWLA (100) DASNRAT (82) QQRFTAPWT (101) PSMB25 HC SYWIG (89) IIYPGDSDTRYSPSFQG (90) GWAYDRGLDY (102) LC KS SQSVLYSSNNKNYLA (103) WASTRES (104) QQYYSTPLT (105) PSMB18 HC SYWIG (89) IIYPGDSDTRYSPSFQG (90) AYHYSKGLDY (106) LC KS SQSVLYSSNNKNYLA (103) WASTRES (104) QQYYSTPLT (105) PSMB80 HC DYAIS (107) RIDPIEGTANYAQKFQG (108) DRYYYDGVYWYSDYFDY (109) LC RASQSISSYLN (76) AASSLQS (60) QQSYSTPLT (88) PSMB58 HC SYWIS (56) IIYPGDSYTRYSPSFQG (57) DYEWELFDSRLDY (58) LC RASQSISSYLN AASSLQS QQSYSTP 2026204725   18 Jun 2026 (59) (60) (61) Table 22. VH and VL sequences of PSMA Fabs FAB ID VH Amino acid sequence SEQ ID NO VL Amino Acid Sequence SEQ ID NO PSMB109 QVQLVQSGAEVKKPGSSVKVSCKASGGTF SSYAISWVRQAPGQGLEWMGWISPYNGNA NYAQKFQGRVTITADESTSTAYMELSSLR SEDTAVYYCARVNSAALVWERLDYWGQGT LVTVSS 110 DIQMTQSPSSLSASVGDRV TITCRASQSIDRWLNWYQQ KPGKAPKLLIYAASSLQSG VPSRFSGSGSGTDFTLTIS SLQPEDFATYYCQQSPRYP LTFGQGTKVEIK 111 PSMB86 QVQLVQSGAEVKKPGSSVKVSCKASGGTF KSYDISWVRQAPGQGLEWMGGIIPIEGTA NYAQKFQGRVTITADESTSTAYMELSSLR SEDTAVYYCARDYPAGYGFDYWGQGTLVT VSS 112 EIVLTQSPGTLSLSPGERA TLSCRASQSVSSSYLAWYQ QKPGQAPRLLIYGASSRAT GIPDRFSGSGSGTDFTLTI SRLEPEDFAVYYCQQYGSS PLTFGQGTKVEIK 113 PSMB84 EVQLLESGGGLVQPGGSLRLSCAASGFTF DSDWMSWVRQAPGKGLEWVSAISGNGGST EYADSVKGRFTISRDNSKNTLYLQMNSLR AEDTAVYYCARDPYYYYDGDSYYGMDVWG QGTLVTVSS 114 DIQMTQSPSSLSASVGDRV TITCRASQSISSYLNWYQQ KPGKAPKLLIYAASSLQSG VPSRFSGSGSGTDFTLTIS SLQPEDFATYYCQQSYSTP LTFGQGTKVEIK 115 PSMB83 EVQLLESGGGLVQPGGSLRLSCAASGFTF KSDAMHWVRQAPGKGLEWVSEISGSGGYT NYADSVKGRFTISRDNSKNTLYLQMNSLR AEDTAVYYCARDSYDSSLYVGDYFDYWGQ GTLVTVSS 116 EIVLTQSPATLSLSPGERA TLSCRASQSVSSYLAWYQQ KPGQAPRLLIYDASNRATG IPARFSGSGSGTDFTLTIS SLEPEDFAVYYCQQRSNWP LTFGQGTKVEIK 117 PSMB80 QVQLVQSGAEVKKPGSSVKVSCKASGGTF DDYAISWVRQAPGQGLEWMGRIDPIEGTA NYAQKFQGRVTITADESTSTAYMELSSLR SEDTAVYYCARDRYYYDGVYWYSDYFDYW GQGTLVTVS 118 DIQMTQSPSSLSASVGDRV TITCRASQSISSYLNWYQQ KPGKAPKLLIYAASSLQSG VPSRFSGSGSGTDFTLTIS SLQPEDFATYYCQQSYSTP LTFGQGTKVEIK 119 2026204725   18 Jun 2026 PSMB58 EVQ LVQ S GAEVKK PGESLKISCKGSGYSF TSYWISWVRQMPGKGLEWMGIIYPGDSYT RYSPSFQGQVTISADKSISTAYLQWSSLK ASDTAMYYCARDYEWELFDSRLDYWGQGT LVTVSS 120 DIQMTQSPSSLSASVGDRV TITCRASQSISSYLNWYQQ KPGKAPKLLIYAASSLQSG VPSRFSGSGSGTDFTLTIS SLQPEDFATYYCQQSYSTP LTFGQGTKVEIK 115 PSMB56 QVQLVQSGAEVKKPGSSVKVSCKASGGTF SSYAISWVRQAPGQGLEWMGWISPYNGNA NYAQKFQGRVTITADESTSTAYMELSSLR SEDTAVYYCARDSDRSYNLDYWGQGTLVT VSS 121 DIQMTQSPSSLSASVGDRV TITCRASQSISGWLNWYQQ KPGKAPKLLIYAASSLQSG VPSRFSGSGSGTDFTLTIS SLQPEDFATYYCQQSYSTP LTFGQGTKVEIK 122 PSMB55 EVQ LVQ S GAEVKK PGESLKISCKGSGYSF TSYWIGWVRQMPGKGLEWMGIIYPGDSDT RYSPSFQGQVTISADKSISTAYLQWSSLK ASDTAMYYCARGLPIWYLDYWGQGTLVTV SSA 123 EIVLTQSPATLSLSPGERA TLSCRASQSVASDLAWYQQ KPGQAPRLLIYFASNRATG IPARFSGSGSGTDFTLTIS SLEPEDFAVYYCQQSITWP FTFGQGTKVEIK 124 PSMB51 QVQLVQSGAEVKKPGSSVKVSCKASGGTF SSYAISWVRQAPGQGLEWMGWIIPYNGNA NYAQKFQGRVTITADESTSTAYMELSSLR SEDTAVYYCARVNSAALVWERLDYWGQGT LVTVSS 125 DIQMTQSPSSLSASVGDRV TITCRASQSIDRWLNWYQQ KPGKAPKLLIYAASSLQSG VPSRFSGSGSGTDFTLTIS SLQPEDFATYYCQQSPRYP LTFGQGTKVEIK 111 PSMB49 QVQLVQSGAEVKKPGSSVKVSCKASGGTF SSYAISWVRQAPGQGLEWMGGIIPIFGTA NYAQKFQGRVTITADESTSTAYMELSSLR SEDTAVYYCARASRVWHASYGYLDYWGQG TLVTVSS 126 EIVLTQSPATLSLSPGERA TLSCRASQSVSKWLAWYQQ KPGQAPRLLIYDASNRATG IPARFSGSGSGTDFTLTIS SLEPEDFAVYYCQQRFTAP WTFGQGTKVEIK 127 PSMB25 EVQ LVQ S GAEVKK PGESLKISCKGSGYSF TSYWIGWVRQMPGKGLEWMGIIYPGDSDT RYSPSFQGQVTISADKSISTAYLQWSSLK ASDTAMYYCARGWAYDRGLDYWGQGTLVT VSS 128 DIVMTQSPDSLAVSLGERA TINCKSSQSVLYSSNNKNY LAWYQQKPGQPPKLLIYWA STRESGVPDRFSGSGSGTD FTLTISSLQAEDVAVYYCQ QYYSTPLTFGQGTKVEIK 129 2026204725   18 Jun 2026 PSMB18 EVQ LVQ S GAEVKK PGESLKISCKGSGYSF TSYWIGWVRQMPGKGLEWMGIIYPGDSDT RYSPSFQGQVTISADKSISTAYLQWSSLK ASDTAMYYCARAYHYSKGLDYWGQGTLVT VSS 130 DIVMTQSPDSLAVSLGERA TINCKSSQSVLYSSNNKNY LAWYQQKPGQPPKLLIYWA STRESGVPDRFSGSGSGTD FTLTISSLQAEDVAVYYCQ QYYSTPLTFGQGTKVEIK 131 Table 23 Heavy and Light chain sequences of PSMA monoclonal antibodies with corresponding SEQ ID NOs mAb ID Heavy Chain Amino acid sequence SEQ ID NO Light Chain Amino Acid Sequence SEQ ID NO PSMB129 (FAB PSMB109) QVQLVQSGAEVKKPGSSVKVSCKAS GGTFSSYAISWVRQAPGQGLEWMGW IS PYNGNANYAQKFQGRVTITADES TS TAYMELSSLRSEDTAVYYCARVN SAALVWERLDYWGQGTLVTVSSAST KGPSVFPLAPCSRSTSESTAALGCL VKDYFPEPVTVSWNSGALTSGVHTF PAVLQSSGLYSLSSVVTVPSSSLGT KTYTCNVDHKPSNTKVDKRVESKYG PPCPPCPAPEAAGGPSVFLFPPKPK DTLMISRTPEVTCVVVDVSQEDPEV QFNWYVDGVEVHNAKTKPREEQFNS TYRVVSVLTVLHQDWLNGKEYKCKV SNKGLPSSIEKTISKAKGQPREPQV YTLPPSQEEMTKNQVSLTCLVKGFY PSDIAVEWESNGQPENNYKTTPPVL DSDGSFFLYSRLTVDKSRWQEGNVF SCSVMHEALHNHYTQKSLSLSLGK 132 DIQMTQSPSSLSASVGDRVTIT CRASQSIDRWLNWYQQKPGKAP KLLIYAASSLQSGVPSRFSGSG SGTDFTLTISSLQPEDFATYYC QQSPRYPLTFGQGTKVEIKRTV AAPSVFIFPPSDEQLKSGTASV VCLLNNFYPREAKVQWKVDNAL QSGNSQESVTEQDSKDSTYSLS STLTLSKADYEKHKVYACEVTH QGLSSPVTKSFNRGEC 133 PSMB130 (FAB PSMB86) QVQLVQSGAEVKKPGSSVKVSCKAS GGTFKSYDISWVRQAPGQGLEWMGG IIPIEGTANYAQKFQGRVTITADES TS TAYMELSSLRSEDTAVYYCARDY PAGYGFDYWGQGTLVTVSSASTKGP SVFPLAPCSRSTSESTAALGCLVKD YFPEPVTVSWNSGALTSGVHTFPAV LQSSGLYSLSSVVTVPSSSLGTKTY TCNVDHKPSNTKVDKRVESKYGPPC PPCPAPEAAGGPSVFLFPPKPKDTL MISRTPEVTCVVVDVSQEDPEVQFN WYVDGVEVHNAKTKPREEQFNSTYR VVSVLTVLHQDWLNGKEYKCKVSNK GLPSSIEKTISKAKGQPREPQVYTL PPSQEEMTKNQVSLTCLVKGFYPSD IAVEWESNGQPENNYKTTPPVLDSD GSFFLYSRLTVDKSRWQEGNVFSCS VMHEALHNHYTQKSLSLSLGK 134 EIVLTQSPGTLSLSPGERATLS CRASQSVSSSYLAWYQQKPGQA PRLLIYGASSRATGIPDRFSGS GSGTDFTLTISRLEPEDFAVYY CQQYGSSPLTFGQGTKVEIKRT VAAPSVFIFPPSDEQLKSGTAS VVCLLNNFYP REAKVQWKVDNA LQSGNSQESVTEQDSKDSTYSL SSTLTLSKADYEKHKVYACEVT HQGLSSPVTKSFNRGEC 135 2026204725   18 Jun 2026 PSMB128 EVQLLESGGGLVQPGGSLRLSCAAS GFTFDSDWMSWVRQAPGKGLEWVSA 136 DIQMTQSPSSLSASVGDRVTIT CRASQSISSYLNWYQQKPGKAP 137 (FAB PSMB84) ISGNGGSTEYADSVKGRFTISRDNS KNTLYLQMNSLRAEDTAVYYCARDP YYYYDGDSYYGMDVWGQGTLVTVSS ASTKGPSVFPLAPCSRSTSESTAAL GCLVKDYFPEPVTVSWNSGALTSGV HTFPAVLQSSGLYSLSSVVTVPSSS LGTKTYTCNVDHKPSNTKVDKRVES KYGPPCPPCPAPEAAGGPSVFLFPP KPKDTLMISRTPEVTCVVVDVSQED PEVQFNWYVDGVEVHNAKTKPREEQ FNSTYRVVSVLTVLHQDWLNGKEYK CKVSNKGLPSSIEKTISKAKGQPRE PQVYTLPPSQEEMTKNQVSLTCLVK GFYPSDIAVEWESNGQPENNYKTTP PVLDSDGSFFLYSRLTVDKSRWQEG NVFSCSVMHEALHNHYTQKSLSLSL GK KLLIYAASSLQSGVPSRFSGSG SGTDFTLTISSLQPEDFATYYC QQSYSTPLTFGQGTKVEIKRTV AAPSVFIFPPSDEQLKSGTASV VCLLNNFYPREAKVQWKVDNAL QSGNSQESVTEQDSKDSTYSLS STLTLSKADYEKHKVYACEVTH QGLSSPVTKSFNRGEC PSMB127 (FAB PSMB83) EVQLLESGGGLVQPGGSLRLSCAAS GFTFKSDAMHWVRQAPGKGLEWVSE ISGSGGYTNYADSVKGRFTISRDNS KNTLYLQMNSLRAEDTAVYYCARDS YDSSLYVGDYFDYWGQGTLVTVSSA STKGPSVFPLAPCSRSTSESTAALG CLVKDYFPEPVTVSWNSGALTSGVH TFPAVLQSSGLYSLSSVVTVPSSSL GTKTYTCNVDHKPSNTKVDKRVESK YGPPCPPCPAPEAAGGPSVFLFPPK PKDTLMISRTPEVTCVVVDVSQEDP EVQFNWYVDGVEVHNAKTKPREEQF NSTYRVVSVLTVLHQDWLNGKEYKC KVSNKGLPSSIEKTISKAKGQPREP QVYTLPPSQEEMTKNQVSLTCLVKG FYPSDIAVEWESNGQPENNYKTTPP VLDSDGSFFLYSRLTVDKSRWQEGN VFSCSVMHEALHNHYTQKSLSLSLG K 138 EIVLTQSPATLSLSPGERATLS CRASQSVSSYLAWYQQKPGQAP RLLIYDASNRATGIPARFSGSG SGTDFTLTISSLEPEDFAVYYC QQRSNWPLTFGQGTKVEIKRTV AAPSVFIFPPSDEQLKSGTASV VCLLNNFYPREAKVQWKVDNAL QSGNSQESVTEQDSKDSTYSLS STLTLSKADYEKHKVYACEVTH QGLSSPVTKSFNRGEC 139 PSMB126 (FAB PSMB80) QVQLVQSGAEVKKPGSSVKVSCKAS GGTFDDYAISWVRQAPGQGLEWMGR IDPIEGTANYAQKFQGRVTITADES TS TAYMELSSLRSEDTAVYYCARDR YYYDGVYWYSDYFDYWGQGTLVTVS SASTKGPSVFPLAPCSRSTSESTAA LGCLVKDYFPEPVTVSWNSGALTSG VHTFPAVLQSSGLYSLSSVVTVPSS SLGTKTYTCNVDHKPSNTKVDKRVE SKYGPPCPPCPAPEAAGGPSVFLFP PKPKDTLMISRTPEVTCVVVDVSQE DPEVQFNWYVDGVEVHNAKTKPREE QFNSTYRVVSVLTVLHQDWLNGKEY KCKVSNKGLPSSIEKTISKAKGQPR EPQVYTLPPSQEEMTKNQVSLTCLV KGFYPSDIAVEWESNGQPENNYKTT PPVLDSDGSFFLYSRLTVDKSRWQE GNVFSCSVMHEALHNHYTQKSLSLS LGK 140 DIQMTQSPSSLSASVGDRVTIT CRASQSISSYLNWYQQKPGKAP KLLIYAASSLQSGVPSRFSGSG SGTDFTLTISSLQPEDFATYYC QQSYSTPLTFGQGTKVEIKRTV AAPSVFIFPPSDEQLKSGTASV VCLLNNFYPREAKVQWKVDNAL QSGNSQESVTEQDSKDSTYSLS STLTLSKADYEKHKVYACEVTH QGLSSPVTKSFNRGEC 137 2026204725   18 Jun 2026 PSMB124 (FAB PSMB56) QVQLVQSGAEVKKPGSSVKVSCKAS GGTFSSYAISWVRQAPGQGLEWMGW IS PYNGNANYAQKFQGRVTITADES TSTAYMELSSLRSEDTAVYYCARDS DRSYNLDYWGQGTLVTVSSASTKGP SVFPLAPCSRSTSESTAALGCLVKD YFPEPVTVSWNSGALTSGVHTFPAV LQSSGLYSLSSVVTVPSSSLGTKTY TCNVDHKPSNTKVDKRVESKYGPPC PPCPAPEAAGGPSVFLFPPKPKDTL MISRTPEVTCVVVDVSQEDPEVQFN WYVDGVEVHNAKTKPREEQFNSTYR VVSVLTVLHQDWLNGKEYKCKVSNK GLPSSIEKTISKAKGQPREPQVYTL PPSQEEMTKNQVSLTCLVKGFYPSD IAVEWESNGQPENNYKTTPPVLDSD GSFFLYSRLTVDKSRWQEGNVFSCS VMHEALHNHYTQKSLSLSLGK 141 DIQMTQSPSSLSASVGDRVTIT CRASQSISGWLNWYQQKPGKAP KLLIYAASSLQSGVPSRFSGSG SGTDFTLTISSLQPEDFATYYC QQSYSTPLTFGQGTKVEIKRTV AAPSVFIFPPSDEQLKSGTASV VCLLNNFYPREAKVQWKVDNAL QSGNSQESVTEQDSKDSTYSLS STLTLSKADYEKHKVYACEVTH QGLSSPVTKSFNRGEC 142 PSMB123 (FAB PSMB55) EVQLVQSGAEVKKPGESLKISCKGS GYSFTSYWIGWVRQMPGKGLEWMGI IYPGDSDTRYSPSFQGQVTISADKS ISTAYLQWSSLKASDTAMYYCARGL PIWYLDYWGQGTLVTVSSASTKGPS VFPLAPCSRSTSESTAALGCLVKDY FPEPVTVSWNSGALTSGVHTFPAVL QSSGLYSLSSVVTVPSSSLGTKTYT CNVDHKPSNTKVDKRVESKYGPPCP PCPAPEAAGGPSVFLFPPKPKDTLM ISRTPEVTCVVVDVSQEDPEVQFNW YVDGVEVHNAKTKPREEQFNSTYRV VSVLTVLHQDWLNGKEYKCKVSNKG LPSSIEKTISKAKGQPREPQVYTLP PSQEEMTKNQVSLTCLVKGFYPSDI AVEWESNGQPENNYKTTPPVLDSDG SFFLYSRLTVDKSRWQEGNVFSCSV MHEALHNHYTQKSLSLSLGK 143 EIVLTQSPATLSLSPGERATLS CRASQSVASDLAWYQQKPGQAP RLLIYFASNRATGIPARFSGSG SGTDFTLTISSLEPEDFAVYYC QQSITWPFTFGQGTKVEIKRTV AAPSVFIFPPSDEQLKSGTASV VCLLNNFYPREAKVQWKVDNAL QSGNSQESVTEQDSKDSTYSLS STLTLSKADYEKHKVYACEVTH QGLSSPVTKSFNRGEC 144 PSMB122 (FAB PSMB51) QVQLVQSGAEVKKPGSSVKVSCKAS GGTFSSYAISWVRQAPGQGLEWMGW IIPYNGNANYAQKFQGRVTITADES TS TAYMELSSLRSEDTAVYYCARVN SAALVWERLDYWGQGTLVTVSSAST KGPSVFPLAPCSRSTSESTAALGCL VKDYFPEPVTVSWNSGALTSGVHTF PAVLQSSGLYSLSSVVTVPSSSLGT KTYTCNVDHKPSNTKVDKRVESKYG PPCPPCPAPEAAGGPSVFLFPPKPK DTLMISRTPEVTCVVVDVSQEDPEV QFNWYVDGVEVHNAKTKPREEQFNS TYRVVSVLTVLHQDWLNGKEYKCKV SNKGLPSSIEKTISKAKGQPREPQV YTLPPSQEEMTKNQVSLTCLVKGFY PSDIAVEWESNGQPENNYKTTPPVL DSDGSFFLYSRLTVDKSRWQEGNVF SCSVMHEALHNHYTQKSLSLSLGK 145 DIQMTQSPSSLSASVGDRVTIT CRASQSIDRWLNWYQQKPGKAP KLLIYAASSLQSGVPSRFSGSG SGTDFTLTISSLQPEDFATYYC QQSPRYPLTFGQGTKVEIKRTV AAPSVFIFPPSDEQLKSGTASV VCLLNNFYPREAKVQWKVDNAL QSGNSQESVTEQDSKDSTYSLS STLTLSKADYEKHKVYACEVTH QGLSSPVTKSFNRGEC 133 PSMB121 (FAB PSMB49) QVQLVQSGAEVKKPGSSVKVSCKAS GGTFSSYAISWVRQAPGQGLEWMGG IIPIFGTANYAQKFQGRVTITADES 146 EIVLTQSPATLSLSPGERATLS CRASQSVSKWLAWYQQKPGQAP RLLIYDASNRATGIPARFSGSG 147 2026204725   18 Jun 2026 TSTAYMELSSLRSEDTAVYYCARAS SGTDFTLTISSLEPEDFAVYYC RVWHASYGYLDYWGQGTLVTVSSAS TKGPSVFPLAPCSRSTSESTAALGC LVKDYFPEPVTVSWNSGALTSGVHT FPAVLQSSGLYSLSSVVTVPSSSLG TKTYTCNVDHKPSNTKVDKRVESKY GPPCPPCPAPEAAGGPSVFLFPPKP KDTLMISRTPEVTCVVVDVSQEDPE VQFNWYVDGVEVHNAKTKPREEQFN STYRVVSVLTVLHQDWLNGKEYKCK VSNKGLPSSIEKTISKAKGQPREPQ VYTLPPSQEEMTKNQVSLTCLVKGF YPSDIAVEWESNGQPENNYKTTPPV LDSDGSFFLYSRLTVDKSRWQEGNV FSCSVMHEALHNHYTQKSLSLSLGK QQRFTAPWTFGQGTKVEIKRTV AAPSVFIFPPSDEQLKSGTASV VCLLNNFYPREAKVQWKVDNAL QSGNSQESVTEQDSKDSTYSLS STLTLSKADYEKHKVYACEVTH QGLSSPVTKSFNRGEC PSMB120 (FAB PSMB25) EVQLVQSGAEVKKPGESLKISCKGS GYSFTSYWIGWVRQMPGKGLEWMGI IYPGDSDTRYSPSFQGQVTISADKS ISTAYLQWSSLKASDTAMYYCARGW AYDRGLDYWGQGTLVTVSSASTKGP SVFPLAPCSRSTSESTAALGCLVKD YFPEPVTVSWNSGALTSGVHTFPAV LQSSGLYSLSSVVTVPSSSLGTKTY TCNVDHKPSNTKVDKRVESKYGPPC PPCPAPEAAGGPSVFLFPPKPKDTL MISRTPEVTCVVVDVSQEDPEVQFN WYVDGVEVHNAKTKPREEQFNSTYR VVSVLTVLHQDWLNGKEYKCKVSNK GLPSSIEKTISKAKGQPREPQVYTL PPSQEEMTKNQVSLTCLVKGFYPSD IAVEWESNGQPENNYKTTPPVLDSD GSFFLYSRLTVDKSRWQEGNVFSCS VMHEALHNHYTQKSLSLSLGK 148 DIVMTQSPDSLAVSLGERATIN CKSSQSVLYSSNNKNYLAWYQQ KPGQPPKLLIYWASTRESGVPD RFSGSGSGTDFTLTISSLQAED VAVYYCQQYYSTPLTFGQGTKV EIKRTVAAPSVFIFPPSDEQLK SGTASVVCLLNNFYPREAKVQW KVDNALQSGNSQESVTEQDSKD STYSLSSTLTLSKADYEKHKVY ACEVTHQGLSSPVTKSFNRGEC 149 PSMB119 (FAB PSMB18) EVQLVQSGAEVKKPGESLKISCKGS GYSFTSYWIGWVRQMPGKGLEWMGI IYPGDSDTRYSPSFQGQVTISADKS ISTAYLQWSSLKASDTAMYYCARAY HYSKGLDYWGQGTLVTVSSASTKGP SVFPLAPCSRSTSESTAALGCLVKD YFPEPVTVSWNSGALTSGVHTFPAV LQSSGLYSLSSVVTVPSSSLGTKTY TCNVDHKPSNTKVDKRVESKYGPPC PPCPAPEAAGGPSVFLFPPKPKDTL MISRTPEVTCVVVDVSQEDPEVQFN WYVDGVEVHNAKTKPREEQFNSTYR VVSVLTVLHQDWLNGKEYKCKVSNK GLPSSIEKTISKAKGQPREPQVYTL PPSQEEMTKNQVSLTCLVKGFYPSD IAVEWESNGQPENNYKTTPPVLDSD GSFFLYSRLTVDKSRWQEGNVFSCS VMHEALHNHYTQKSLSLSLGK 150 DIVMTQSPDSLAVSLGERATIN CKSSQSVLYSSNNKNYLAWYQQ KPGQPPKLLIYWASTRESGVPD RFSGSGSGTDFTLTISSLQAED VAVYYCQQYYSTPLTFGQGTKV EIKRTVAAPSVFIFPPSDEQLK SGTASVVCLLNNFYPREAKVQW KVDNALQSGNSQESVTEQDSKD STYSLSSTLTLSKADYEKHKVY ACEVTHQGLSSPVTKSFNRGEC 149 2026204725   18 Jun 2026 PSMB87 (FAB PSMB58) EVQLVQSGAEVKKPGESLKISCKGS GYSFTSYWISWVRQMPGKGLEWMGI IYPGDSYTRYSPSFQGQVTISADKS ISTAYLQWSSLKASDTAMYYCARDY EWELFDSRLDYWGQGTLVTVSSAST KGPSVFPLAPCSRSTSESTAALGCL VKDYFPEPVTVSWNSGALTSGVHTF PAVLQSSGLYSLSSVVTVPSSSLGT KTYTCNVDHKPSNTKVDKRVESKYG PPCPPCPAPEAAGGPSVFLFPPKPK DTLMISRTPEVTCVVVDVSQEDPEV QFNWYVDGVEVHNAKTKPREEQFNS TYRVVSVLTVLHQDWLNGKEYKCKV SNKGLPSSIEKTISKAKGQPREPQV YTLPPSQEEMTKNQVSLTCLVKGFY PSDIAVEWESNGQPENNYKTTPPVL DSDGSFFLYSRLTVDKSRWQEGNVF SCSVMHEALHNHYTQKSLSLSLGK 151 DIQMTQSPSSLSASVGDRVTIT CRASQSISSYLNWYQQKPGKAP KLLIYAASSLQSGVPSRFSGSG SGTDFTLTISSLQPEDFATYYC QQSYSTPLTFGQGTKVEIKRTV AAPSVFIFPPSDEQLKSGTASV VCLLNNFYPREAKVQWKVDNAL QSGNSQESVTEQDSKDSTYSLS STLTLSKADYEKHKVYACEVTH QGLSSPVTKSFNRGEC 137 A monospecific anti-PSMA antibody PSMB119 was generated comprising the VH and VL regions having the VH of SEQ ID NO: 130and the VL of SEQ ID NO: 131and an IgG4 constant region with S228P, F234A, and L235A substitutions. A monospecific anti-PSMA 5 antibody PSMB120 was generated comprising the VH and VL regions having the VH of SEQ ID NO: 128 and the VL of SEQ ID NO: 129 and an IgG4 constant region with S228P, F234A, and L235A substitutions. A monospecific anti-PSMA antibody PSMB121 was generated comprising the VH and VL regions having the VH of SEQ ID NO: 126 and the VL of SEQ ID NO: 127 and an IgG4 constant region with S228P, F234A, and L235A substitutions. A monospecific anti- 10 PSMA antibody PSMB122 was generated comprising the VH and VL regions having the VH of SEQ ID NO: 125 and the VL of SEQ ID NO: 111 and an IgG4 constant region with S228P, F234A, and L235A substitutions. A monospecific anti-PSMA antibody PSMB123 was generated comprising the VH and VL regions having the VH of SEQ ID NO: 123 and the VL of SEQ ID NO: 124 and an IgG4 constant region with S228P, F234A, and L235A substitutions. A 15 monospecific anti-PSMA antibody PSMB124 was generated comprising the VH and VL regions having the VH of SEQ ID NO: 121 and the VL of SEQ ID NO: 122 and an IgG4 constant region with S228P, F234A, and L235A substitutions. A monospecific anti-PSMA antibody PSMB126 was generated comprising the VH and VL regions having the VH of SEQ ID NO: 118 and the VL of SEQ ID NO: 119 and an IgG4 constant region with S228P, F234A, and L235A 20 substitutions. A monospecific anti-PSMA antibody PSMB127 was generated comprising the VH and VL regions having the VH of SEQ ID NO: 116 and the VL of SEQ ID NO: 117 and an IgG4 2026204725   18 Jun 2026 constant region with S228P, F234A, and L235A substitutions. A monospecific anti-PSMA antibody PSMB128 was generated comprising the VH and VL regions having the VH of SEQ ID NO: 114 and the VL of SEQ ID NO: 115 and an IgG4 constant region with S228P, F234A, and L235A substitutions. A monospecific anti-PSMA antibody PSMB129 was generated comprising 5 the VH and VL regions having the VH of SEQ ID NO: 110 and the VL of SEQ ID NO: 111 and an IgG4 constant region with S228P, F234A, and L235A substitutions. A monospecific anti-PSMA antibody PSMB130 was generated comprising the VH and VL regions having the VH of SEQ ID NO: 112 and the VL of SEQ ID NO: 113 and an IgG4 constant region with S228P, F234A, and L235A substitutions. 10 2-5 Crystal structure of human PSMA ECD bound to anti-PSMA Fab PSMB83 (aka PSMM84) PSMA is a homodimeric protein expressed on the cell surface. PSMA is a type II integral glycoprotein of 750 residues per monomer, comprised of a large ECD domain (705 residues) 15 with peptidase activity, a single pass TM domain, and a short 19 residue intracellular domain. The crystal structure of the extracellular region (ECD) of human PSMA bound to the anti-PSMA Fab arm of bispecific antibody PS3B27 was determined to 3.15 A resolution to better understand the combining site between PSMA and the antibody. The extracellular region of human PSMA (residues 44-750) was expressed in High 20 Five™ insect cells with an N-terminal gp67 signal peptide followed by a cleavable hexahistidine tag (SEQ ID NO: 596). The secreted protein was purified from supernatant by a three-step procedure comprising of an initial Ni2+-NTA affinity capture, TEV-mediated cleavage of the histidine tag followed by an inverse affinity chromatography step, and a final size-exclusion chromatography step. Purified PSMA-ECD was flash-frozen in liquid nitrogen and stored at -80 25 °C in 10 mM HEPES pH 7.4, 150 mM NaCl, 2 mM CaCl2, 0.1 mM ZnCl2 The Fab of PSMB83 (aka PSMM84), which is the parental anti-PSMA Fab arm in bispecific antibody PS3B27, was expressed in HEK293 Expi cells with a hexahistidine tag (SEQ ID NO: 596) and purified using affinity (HisTrap, GE Healthcare) and size-exclusion chromatography (SEC-300, Phenomenex Yarra). The Fab was stored at 4 °C in 50 mM NaCl, 20 30 mM Tris pH 7.4 2026204725   18 Jun 2026 The human PSMA ECD / PSMB83 Fab complex was prepared by a three-step procedure. First, the Fab was buffer exchanged into 20mM MES pH 6.0, 150 mM NaCl. Then, the Fab and PSMA were mixed (1.5 molar excess Fab over PSMA monomer) and incubated overnight at 4 °C while dialyzing into 20 mM MES pH ...

Claims

2026204725   18 Jun 2026WHAT IS CLAIMED:

1. An isolated recombinant anti-CD3 antibody, or antigen-binding fragment thereof, comprising:5 a) a heavy chain comprising a heavy chain complementarity determining region (HCDR) 1 comprising SEQ ID NO: 662; a HCDR2 comprising SEQ ID NO: 663; and a HCDR3 comprising SEQ ID NO: 664 and a light chain comprising a light chain complementarity determining region (LCDR) 1 comprising SEQ ID NO:671, a LCDR2 comprising SEQ ID NO: 673, and a LCDR3 comprising SEQ ID NO: 690;10 b) a heavy chain variable region comprising SEQ ID NO: 652 and a light chain variable region comprising SEQ ID NO: 661;c) a heavy chain comprising SEQ ID NO: 640 and a light chain comprising SEQ ID NO: 676;d) a heavy chain variable region comprising SEQ ID NO: 657 and a light chain variable15 region comprising SEQ ID NO: 678; ore) a heavy chain comprising SEQ ID NO: 675 and a light chain comprising SEQ ID NO: 677.

2. An isolated recombinant anti-CD3 antibody or antigen-binding fragment thereof, wherein the antibody or antigen-binding fragment specifically binds Macaca fascicularis or human20 CD3d, or CD3e, or CD3e and CD3d with a binding affinity of about 300 nM or less.

3. The isolated recombinant anti-CD3 antibody or antigen-binding fragment thereof of claim 2, wherein the binding affinity is about 100 nM or less.

4. The isolated recombinant anti-CD3 antibody or antigen-binding fragment thereof of claim 2 or 3, wherein the binding affinity is measured by flow cytometry or by Proteon surface25 plasmon resonance assay ProteOn XPR36 system at +25°C.

5. The isolated recombinant anti-CD3 antibody or antigen-binding fragment thereof of any one of the previous claims, wherein the antibody or antigen-binding fragment has one, two, three, or four of the following properties:a) binds human and Macaca fascicularis CD3+ T lymphocytes with a calculated EC50 of30        300 nM or less and binds Macaca fascicularis CD3-expressing HEK cells with acalculated EC50 of 300 nM or less, wherein the difference in calculated EC50 between binding CD3+ T lymphocytes and binding Macaca fascicularis CD3-expressing HEK2026204725   18 Jun 2026cells is less than 5-fold, and wherein the calculated EC50 is measured in a whole cell binding assay at 0 °C using flow cytometry;b) binds recombinant CD3d from human (SEQ ID NO:691), or binds recombinant CD3e from human (SEQ ID NO:636), or binds recombinant CD3d from Macaca fascicularis5 (SEQ ID NO:692), or binds recombinant CD3e from Macaca fascicularis (SEQ ID NO:693) with an equilibrium dissociation constant (Kd) of 300 nM or less, wherein the Kd is measured using Proteon surface plasmon resonance assay ProteOn XPR36 system at +25°C;c) binds residues 1-6 of CD3e as determined by X-ray crystallography; or10 d) activates T cells or induces CD69 expression to a similar degree as cOKT3 or SP34-2 as determined by fluorescence-activated cell sorting assay.

6. The antibody or antigen-binding fragment thereof of any one of the previous claims comprising at least one substitution in an antibody constant domain, the at least one substitution comprising:15 a) heavy chain substitutions K409R, F405L, or F405L and R409K;b) heavy chain substitutions S228P, F234A, and L235A;c) heavy chain substitutions L234A, G237A, P238S, H268A, A330S and P331S, wherein the antibody is an IgG1 isotype; ord) heavy chain substitution S228P, wherein the antibody is an IgG4 isotype;20 wherein residue numbering is according to the EU Index.

7. The antibody or antigen-binding fragment thereof of any one of the previous claims, comprising the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID NOs:662, 663, 664, 671, 673, and 690, respectively.

8. The antibody or antigen-binding fragment thereof of any one of the previous claims,25 comprising a heavy chain variable region (VH) and a light chain variable region (VL) of SEQ ID NOs:652 and 661, respectively.2026204725   18 Jun 20269. The antibody or antigen-binding fragment thereof of any one of the previous claims, comprising a heavy chain sequence (HC) and a light chain sequence (LC) of SEQ ID NOs:640 and 676, respectively.

10. The antibody or antigen-binding fragment thereof of any one of claims 1-5, comprising a VH 5 and a VL of SEQ ID NOs:657 and 678, respectively.

11. The antibody or antigen-binding fragment thereof of any one of claims 1-5, comprising a HC and a LC of SEQ ID NOs:675 and 677, respectively.

12. An antibody or antigen-binding fragment thereof, comprising the HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID NOs: 662, 663, 664, 671, 673, 10 and 690, respectively.

13. An antibody or antigen-binding fragment thereof, comprising a VH and a VL of SEQ ID NOs:652 and 661, respectively.

14. An antibody or antigen-binding fragment thereof, comprising a HC and a LC of SEQ ID NOs:640 and 676, respectively.15 15. An antibody or antigen-binding fragment thereof, comprising a VH and a VL of SEQ ID NOs:657 and 678, respectively.

16. An antibody or antigen-binding fragment thereof, comprising a HC and a LC of SEQ ID NOs:675 and 677, respectively.

17. The antibody or antigen-binding fragment thereof of any one of the previous claims, wherein 20 the antibody is human or humanized.

18. The antibody of claim 17, wherein the antibody is an IgG4 or IgG1 isotype.

19. The antibody of claim 18, comprising one, two, three, four, five, six, seven, eight, nine or ten substitutions in the antibody Fc.

20. An antibody or antigen-binding fragment thereof, comprising a HC of SEQ ID NO:639 and 25 a LC of SEQ ID NOs:646, comprising at least one substitution comprising:a) D43G, L49M, L50I, S62N, Q85E light chain substitutions;b) D43G, V48L, L49M, L50I, S62N, Q85E, H89Y light chain substitutions;2026204725   18 Jun 2026c) R10G, R13K, V73I, R70K, T83S, L96V heavy chain substitutions;d) any one of light chain substitutions D43G, V48L, L49M, L50I, S62N, Q85E, or H89Y; ore) any one of heavy chain substitutions R10G, R13K, V73I, R79K, T83S, or L96V, wherein residue numbering is according to the EU Index.

521. The antibody of any one of the previous claims, wherein the antibody is bispecific or multispecific.

22. A bispecific antibody comprising a first domain that specifically binds CD3 and a second domain that specifically binds a second antigen, wherein the first domain comprises the10 HCDR1, the HCDR2, the HCDR3, the LCDR1, the LCDR2, and the LCDR3 of SEQ ID NOs:662, 663, 664, 671, 673, and 690, respectively.

23. The bispecific antibody of claim 22 wherein the first domain and second domain are an IgG4 isotype, and wherein the first or the second domain comprises S228P, F234A, L235A, F405L and R409K heavy chain substitutions and the other domain of the first or the second domain15 comprises S228P, F234A and L235A heavy chain substitution, wherein residue numbering is according to the EU Index.

24. The bispecific antibody of claim 22, wherein the first and / or the second domain comprises at least one substitution in a CH3 constant domain comprising a F405L, or F405L and R409K substitution, wherein residue numbering is according to the EU Index.20 25. The bispecific antibody of claim 22, wherein one of the first or the second domains comprises a F405L heavy chain substitution and the other of the first or second domains comprises a K409R heavy chain substitution, wherein residue numbering is according to the EU Index.

26. The bispecific antibody of claim 22, wherein the first domain and the second domain are an25 IgG4 isotype, wherein one of the first or the second domains comprises a S228P heavy chain substitution and the other of the first or the second domains comprises S228P, F405L and R409K heavy chain substitutions, wherein residue numbering is according to the EU Index.2026204725   18 Jun 202627. The bispecific antibody of claim 22, wherein the first domain comprises the VH and the VL of SEQ ID NOs: 652 and 661, respectively.

28. The bispecific antibody of claim 22, wherein the first domain comprises the HC and the LC of SEQ ID NOs: 640 and 676, respectively.5 29. The bispecific antibody of claim 22, wherein the first domain comprises the VH and the VL of SEQ ID NOs:657 and 678, respectively.

30. The bispecific antibody of claim 22, wherein the first domain comprises the HC and the LC of SEQ ID NOs:675 and 677, respectively.

31. The bispecific antibody of claim 22, wherein the second antigen is a cell surface antigen that10 is expressed on a target cell other than an immune effector cell.

32. The bispecific antibody of claim 31, wherein the cell surface antigen is a tumor associated antigen.

33. The bispecific antibody of any one of claims 24-34, wherein the second antigen is CD33, IL1RAP, PSMA or TMEFF2.15 34. A pharmaceutical composition comprising the antibody of any one of the previous claims and a pharmaceutically acceptable carrier.

35. A polynucleotide encoding the antibody of any one of the claims 1-34.

36. A vector comprising the polynucleotide of claim 35.

37. A host cell comprising the vector of claim 36.20 38. A method of producing the antibody of any one of claims 1-34, comprising culturing the host cell of claim 37 in conditions that the antibody is expressed, and recovering the antibody produced by the host cell.

39. A method of treating a cancer in a subject, comprising administering a therapeutically effective amount of the isolated antibody of any one of claims 1-34 to the subject in need25 thereof for a time sufficient to treat the cancer.

40. The method of claim 39, wherein the cancer is a solid tumor or a hematological malignancy.2026204725   18 Jun 202641. The method of claim 40, wherein the solid tumor is a prostate cancer, a colorectal cancer, a gastric cancer, a clear cell renal carcinoma, a bladder cancer, a lung cancer, a squamous cell carcinoma, a glioma, a breast cancer, a kidney cancer, a neovascular disorder, a clear cell renal carcinoma (CCRCC), a pancreatic cancer, a renal cancer, a urothelial cancer or an5 adenocarcinoma to the liver.

42. The method of claim 41, wherein the prostate cancer is a refractory prostate cancer, a prostatic intraepithelial neoplasia, an androgen independent prostate cancer, or a malignant prostate cancer.

43. The method of claim 40, wherein the hematological malignancy is acute myeloid leukemia10 (AML), myelodysplastic syndrome (MDS), acute lymphocytic leukemia (ALL), diffuse large B-cell lymphoma (DLBCL), chronic myeloid leukemia (CML) or blastic plasmacytoid dendritic cell neoplasm (DPDCN).

44. The method of any one of claims 38-43, wherein the antibody is administered in combination with a second therapeutic agent.15 45. The antibody of any one of claims 1-34 for use in therapy.

46. An anti-idiotypic antibody binding to the antibody of any one of claims 1-34.

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