CD19 / CD38 multispecific antibodies for immune checkpoint inhibitor combination therapies

Abstract

Provided and exemplified herein are inhibitors of B-reg cells (regulatory B cells) for use in a combination therapy with an ICI. Useful B-reg inhibitors include antibodies that bind CD19 and CD38, for example, a bispecific antibody that binds CD19 and CD38. Such bispecific antibodies that bind CD19 and CD38 can be characterized by an antibody comprising a CD19-binding domain and a CD38-binding domain.

Description

WSGR Docket Number: 51527-717.601CD19 / CD38 MULTISPECIFIC ANTIBODIES FOR IMMUNE CHECKPOINT INHIBITOR COMBINATION THERAPIESCROSS-REFERENCE

[0001] This application claims the benefit of U.S. Provisional Application Serial No. 63 / 697,954, filed on September 23, 2024, which is incorporated by reference herein in its entirety.SEQUENCE LISTING

[0002] The instant application contains a Sequence Listing which has been submitted electronically and is hereby incorporated by reference in its entirety. Said copy, created on September 21, 2025, is named BG55 51527-717.601. xml and is 22100 bytes in size.BACKGROUND

[0003] Immune checkpoint inhibitor (I Cl ) therapy for the treatment of cancer faces several challenges. Tumors often create dominating suppressive microenvironments that hinder the effectiveness of these therapies, impairing immune cell function and limiting their ability to recognize and kill cancer cells. Additionally, tumor and microenvironment heterogeneity leads to variable responses to checkpoint blockade, and limited tumor infiltration restricts immune cell access to tumor sites. Immunotherapy resistance can also emerge, reducing the long-term efficacy of checkpoint inhibitors.SUMMARY

[0004] Despite advances in immune checkpoint inhibitor (ICI) therapy, the major bottleneck of immune checkpoint blockade therapy can still be definable by a low response rate in most cancers. Accordingly, there is an unmet need for the development of new ICI modalities and therapies in the treatment of cancer.

[0005] Provided herein are combination therapies that improve the ICI therapy efficacy by including the selective targeting and inhibition of immunosuppressive B-regulatory (B-reg) cells. Such combination therapies allow for selective targeting and inhibition of immunosuppressive B-regulatory (B-reg) cells and immune checkpoint inhibition of immunosuppressive T cells and / or immunosuppressive T-cell signaling. Thus, provided herein are methods of treating a cancer comprising: administering to the individual in need thereof (i)WSGR Docket Number: 51527-717.601 a therapeutically effective amount of an inhibitor of B regulatory (B-reg cells) cells (e.g., a bispecific antibody or bispecific antibody fragment that binds CD19 and CD38) and (ii) a therapeutically effective amount of an ICI (e.g., a PD-l / PDL-1 axis inhibitor). The compositions and methods described herein can preserve non B-reg subsets allowing for fewer immunosuppressive side effects compared to pan B cell targeting agents.

[0006] Provided herein, in one embodiment is a method of treating a cancer in an individual in need thereof, the method comprising administering to the individual: a therapeutically effective amount of an inhibitor of B regulatory (B-reg) cells; and a therapeutically effective amount of an immune checkpoint inhibitor (ICI).

[0007] Provided herein, in one embodiment is a method of treating a cancer in an individual in need thereof, the method comprising administering an inhibitor of B regulatory (B-reg) cells to the individual. In certain embodiments, the cancer comprises a tumor characterized by (i) a blood sample taken from the individual having a percentage of B-reg cells greater than 1% of the percent total CD19 positive B cells or (ii) a biological sample taken from the individual having B-reg cells.

[0008] Provided herein, in one embodiment is a method of treating a cancer in an individual in need thereof, the method comprising: determining the percentage of B-reg cells in: (i) a blood sample taken from the individual, or (ii) a tumor sample taken from the individual, and administering to the individual: (i) a therapeutically effective amount of an inhibitor of B regulatory (B-reg) cells if the percentage of B-reg cells in the blood sample is greater than 1.0% of the percent total B cells in the blood sample, or (ii) a therapeutically effective amount of an inhibitor of B regulatory (B-reg) cells if B-reg cells are present in the tumor sample, optionally wherein the B-reg cells are present among total CD45+ cells taken from the tumor sample. In some embodiments, the method comprises administering: (i) the inhibitor of B regulatory (B-reg) cells; and (ii) an immune checkpoint inhibitor (ICI). In some embodiments, the B-reg cells are characterized as CD19+CD38+, optionally wherein the B-reg cells are characterized as CD19+CD38+CD20LOW or CD19+CD38+CD20NEG. In some embodiments, the B-reg cells are characterized as CD19+CD38HIGH, optionally wherein the B- reg cells are characterized as CD19+CD38HIGHCD20LOW or CD19+CD38HIGHCD20NEG. In some embodiments, the ICI is a T-cell ICI. In some embodiments, the inhibitor of B-reg cells comprises a bispecific antibody or bispecific antibody fragment that binds CD19 and CD38. In some embodiments, the bispecific antibody or bispecific antibody fragment that binds CD19WSGR Docket Number: 51527-717.601 and CD38 comprises: an anti-CD38 heavy chain variable domain and an anti-CD38 light chain variable domain; and an anti-CD19 heavy chain variable domain and an anti-CD19 light chain variable domain. In some embodiments, the anti-CD38 heavy chain variable domain comprises: a heavy chain complementarity determining domain 1 (CDRH1) comprising an amino acid sequence set forth in SEQ ID NO: 7, a heavy chain complementarity determining domain 2 (CDRH2) comprising an amino acid sequence set forth in SEQ ID NO: 8, 16. 17, or 18, a heavy chain complementarity determining domain 3 (CDRH3) comprising an amino acid sequence set forth in SEQ ID NO: 9, the anti-CD38 light chain variable domain comprises: a light chain complementarity determining domain 1 (CDRL1) comprising an amino acid sequence set forth in SEQ ID NO: 13 a light chain complementarity determining domain 2 (CDRL2) comprising an amino acid sequence set forth in SEQ ID NO: 14, a light chain complementarity determining domain 3 (CDRL3) comprising an amino acid sequence set forth in SEQ ID NO: 15, or a light chain complementarity determining domain 1 (CDRL1) comprising an amino acid sequence set forth in SEQ ID NO: 23 a light chain complementarity determining domain 2 (CDRL2) comprising an amino acid sequence set forth in SEQ ID NO: 24, a light chain complementarity determining domain 3 (CDRL3) comprising an amino acid sequence set forth in SEQ ID NO: 25, the anti-CD19 heavy chain variable domain comprising: the anti-CD19 light chain variable domain comprises: a light chain complementarity determining domain 1 (CDRL1) comprising an amino acid sequence set forth in SEQ ID NO: 13 a light chain complementarity determining domain 2 (CDRL2) comprising an amino acid sequence set forth in SEQ ID NO: 14, a light chain complementarity determining domain 3 (CDRL3) comprising an amino acid sequence set forth in SEQ ID NO: 15, or a light chain complementarity determining domain 1 (CDRL1) comprising an amino acid sequence set forth in SEQ ID NO: 23 a light chain complementarity determining domain 2 (CDRL2) comprising an amino acid sequence set forth in SEQ ID NO: 24, a light chain complementarity determining domain 3 (CDRL3) comprising an amino acid sequence set forth in SEQ ID NO: 25. In some embodiments, the bispecific antibody or bispecific antibody fragment that binds CD19 and CD38 depletes B-reg cells incubated with cancer patient allogeneic PBMCs. In some embodiments, the B-reg cells are CD19+CD38+CD20- B-reg cells. In some embodiments, the bispecific antibody or bispecific antibody fragment that binds CD19 and CD38 preserves non-target immune cells in healthy donor PMBCs and / or cancer patient PBMCs. In some embodiments, the non-target immune cells comprise CD3+CD38+ immune cells, CD20+CD38+immune cells, CD56+CD38 immune cells, and / or CDllb / c+CD38+immuneWSGR Docket Number: 51527-717.601 cells. In some embodiments, the bispecific antibody or bispecific antibody fragment that binds CD19 and CD38 is a common light chain bispecific antibody. In some embodiments, the common light chain bispecific antibody comprises: an anti-CD38 heavy chain variable domain comprising: a heavy chain complementarity determining domain 1 (CDRH1) comprising an amino acid sequence set forth in SEQ ID NO: 7, a heavy chain complementarity determining domain 2 (CDRH2) comprising an amino acid sequence set forth in SEQ ID NO: 8, 16. 17, or 18, a heavy chain complementarity determining domain 3 (CDRH3) comprising an amino acid sequence set forth in SEQ ID NO: 9, an anti-CD19 heavy chain variable comprising: a heavy chain complementarity determining domain 1 (CDRH1) comprising an amino acid sequence set forth in SEQ ID NQ:10, a heavy chain complementarity determining domain 2 (CDRH2) comprising an amino acid sequence set forth in SEQ ID NO: 11, a heavy chain complementarity determining domain 3 (CDRH3) comprising an amino acid sequence set forth in SEQ ID NO: 12; and a common light chain variable domain comprising: a light chain complementarity determining domain 1 (CDRL1) comprising an amino acid sequence set forth in SEQ ID NO: 13 a light chain complementarity determining domain 2 (CDRL2) comprising an amino acid sequence set forth in SEQ ID NO: 14, a light chain complementarity determining domain 3 (CDRL3) comprising an amino acid sequence set forth in SEQ ID NO: 15, or a light chain complementarity determining domain 1 (CDRL1) comprising an amino acid sequence set forth in SEQ ID NO: 23 a light chain complementarity determining domain 2 (CDRL2) comprising an amino acid sequence set forth in SEQ ID NO: 24, a light chain complementarity determining domain 3 (CDRL3) comprising an amino acid sequence set forth in SEQ ID NO: 25. In some embodiments, the anti-CD38 heavy chain variable domain comprises an amino acid sequence having at least 85%, 90%, 95%, 97%, 98%, 99%, or 100% to SEQ ID NO: 1, the anti-CD19 heavy chain variable domain comprises an amino acid sequence having at least 85%, 90%, 95%, 97%, 98%, 99%, or 100% to SEQ ID NO: 2, and common light chain variable domain comprises an amino acid sequence having at least 85%, 90%, 95%, 97%, 98%, 99%, or 100% to SEQ ID NO: 3. In some embodiments, the common light chain bispecific antibody comprises an anti-CD38 heavy chain amino acid sequence having at least 85%, 90%, 95%, 97%, 98%, 99%, or 100% to SEQ ID NO: 4, an anti-CD19 heavy chain amino acid sequence having at least 85%, 90%, 95%, 97%, 98%, 99%, or 100% to SEQ ID NO: 5, and a common light chain an anti-CD38 heavy chain amino acid sequence having at least 85%, 90%, 95%, 97%, 98%, 99%, or 100% to SEQ ID NO: 6. In some embodiments, the anti-CD38 heavy chain variable domain and the anti-CD19 heavyWSGR Docket Number: 51527-717.601 chain variable domain each comprise a negatively-charged amino acid at heavy chain variable domain position 1 per Kabat numbering; the anti-CD38 heavy chain constant domain and the anti-CD19 heavy chain constant domain each lack a C-terminal lysine residue (K447 per EU numbering); and the common light chain bispecific antibody comprises an experimental isoelectric point (pl) of less than 9. In some embodiments, the common light chain bispecific antibody exhibits a Hydrophobicity (HIC) retention time of less than about 10 minutes. In some embodiments, the terminal lysine residue is K447 per EU numbering. In some embodiments, the anti-CD19 heavy chain variable domain comprises a serine at position 84 and / or a leucine at position 108 according to Kabat numbering. In some embodiments, the common light chain variable region comprises a histidine at position 32 according to Kabat numbering. In some embodiments, the negatively-charged amino acid is glutamic acid. In some embodiments, the pl is between 8.7 and 9. In some embodiments, the ICI is a PD-1 / PD-L1 axis inhibitor. In some embodiments, the PD-1 / PD-L1 axis inhibitor is an antibody. In some embodiments, the antibody is an anti-PD-1 antibody. In some embodiments, the anti-PD-1 antibody is Pembrolizumab, Nivolumab, Dostarlimab, Retifanlimab, Spartalizumab, Camrelizumab, Sintilimab, Cemiplimab, Tislelizumab, penpulimab, zimberelimab, toripalimab, AMP-514 (MEDI0680), Acrixolimab (YBL-006), or a combination thereof. In some embodiments, the antibody is an anti-PD-Ll antibody. In some embodiments, the anti-PD-Ll antibody is Atezolizumab, Avelumab, Durvalumab, Envafolimab (KN035), Cosibelimab (CK-301), or a combination thereof. In some embodiments, the ICI is a CTLA-4 inhibitor. In some embodiments, the CTLA-4 inhibitor is an antibody. In some embodiments, the antibody is Ipilimumab, Tremelimumab, Quavonlimab, Botensilimab, Zalifrelimab, Gotistobart, XTX101, HCAb 4003-2, or a combination thereof. In some embodiments, the ICI is a Lag-3 inhibitor. In some embodiments, the Lag-3 inhibitor is an antibody. In some embodiments, the antibody is Relatlimab, Leramilimab, Favezelimab, Encelimab (TSR-033), Fianlimab, Sym022, INCAGN02385, BI754111, LBL-007, HLX26, or a combination thereof. In some embodiments, the ICI is a TIM-3 inhibitor. In some embodiments, the TIM-3 inhibitor is an antibody. In some embodiments, the antibody is Sabatolimab (MBG453), MsTOOl, MsT065, MsT229, Cobolimab (TSR-022), Sym023, LY3321367, LY3415244, MBG-A425, MsT286, or a combination thereof. In some embodiments, the ICI is a TIGIT inhibitor. In some embodiments, the TIGIT inhibitor is an antibody. In some emobdiments, the antibody is Vibostolimab, Etigilimab, Tiragolumab, Domvanalimab, Ociperlimab, Belrestotug (EOS-448), BMS-986207, ASP8374, COM902,WSGR Docket Number: 51527-717.601Tamgiblimab (IBI939), or a combination thereof. In some embodiments, the cancer comprises a solid tumor or a liquid tumor. In some embodiments, the cancer is characterized by a blood sample taken from the individual and having an increased percentage of B-reg cells relative to a healthy individual blood. In some embodiments, the individual is characterized by (i) a percentage of B regulatory (B-reg) cells in a blood sample being greater than 1.0% of the percent total B cells in the blood sample and / or (ii) B-reg cells being present a tumor sample, optionally wherein the B-reg cells are present among total CD45+ cells taken from the tumor sample. In some embodiments, the cancer comprises lung cancer, colorectal cancer, head and neck carcinoma, or pancreatic cancer. In some embodiments, the cancer is a non-small cell lung cancer, a colorectal adenocarcinoma, a head and neck squamous cell carcinoma, or a pancreatic adenocarcinoma. In some embodiments, treating comprises reducing tumor volume as compared to treatment with the ICI alone and / or reducing the rate of tumor growth as compared to treatment with the ICI alone. In some embodiments, the inhibitor of B regulatory (B-reg) cells is administered concurrently with the immune checkpoint inhibitor (ICI). In some embodiments, the inhibitor of B regulatory (B-reg) cells and the immune checkpoint inhibitor (ICI) are administered separately. In some embodiments, the inhibitor of B regulatory (B-reg) cells and the immune checkpoint inhibitor (ICI) are administered separately according to different treatments schedules. In some embodiments, the individual is currently receiving or has previously received an ICI therapy. In some embodiments, the cancer is resistant to ICI therapy. In some embodiments, the cancer is relapsed or refractory to ICI therapy. In some embodiments, the cancer is a progressive cancer.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1A shows tumor volume data over time with anti-CD19 / CD38 bispecific antibody (bsAB), anti-PD-1 antibody (Ab), and combination anti-CD19 / CD38 bsAb + anti-PD-1 Ab. Combination treatment of anti-CD19 / CD38 bsAb and anti-PD-1 Ab resulted in substantially increased inhibition of tumor growth as compared to anti-PD-1 Ab alone.

[0010] FIG. IB shows survival curve data of CT26 mice treated with an anti-CD19 / CD38 bsAb, anti-PD-1 Ab, and combination anti-CD19 / CD38 bsAB + anti-PD-1 Ab. The combination treatment of anti-CD19 / CD38 bsAb and anti-PD-1 Ab resulted in substantially improved survival of CT26 mice as compared to PD-1 Ab monotherapy.WSGR Docket Number: 51527-717.601

[0011] FIG. 1C shows tumor volume data for individual replicates of mice at day 20 upon treatment with anti-CD19 / CD38 bsAb, anti-PD-1 Ab, and combination anti-CD19 / CD38 bsAb + anti-PD-1 Ab. Combination treatment of anti-CD19 / CD38 bsAb + anti-PD-1 Ab resulted in a substantial decrease in tumor volume as compared to either PD-1 Ab monotherapy.

[0012] FIG. 1D-F shows comparison of survival curves with treatment with anti-CD19 / CD38 bsAb + anti-PD-1 Ab. Combo treatment with anti-CD19 / CD38 bsAb + anti-PD-1 Ab combo resulted in greater survival in mice.

[0013] FIG. 2A-B shows data for absolute cell counts of CD3+ / CD38+, CD20+ / CD38+, CD56+ / CD38+, CDllb / c+ / CD38+ immune cells in healthy and cancer patient PBMC donors. The data shows that treatment of PBMCs with anti-CD19 / CD38 bsAb preserved non-target immune cells (e.g., CD19+CD38+ B-reg cells) in healthy donor and cancer patient PBMCs.

[0014] FIG. 3A-C shows data for absolute cell counts of B-reg cells treated with anti- CD19 / CD38 bsAb. The results show that CD19 / CD38 bsAb depletes B-reg cells incubated with cancer patient allogeneic PBMCs.

[0015] FIG. 4 shows the percentage increase in CD4+ T-cells above activated T-cells, split across populations having >1.5% B-reg cells and B-reg cells <1% B-reg cells. Cancers having increased / elevated in B-reg cells (e.g., relative to a healthy donor and / or >1.5% B-reg cells present in a blood sample) responded strongly to the treatment with anti-CD19 / CD38 bsAb.

[0016] FIG. 5 shows a graph of the percentage of B-reg cells in total CD45+ immune cell population across 4 cancer types. The relative prevalence of B-reg cells was measured in n=56 tumor samples. NSCLC and other solid tumor types show CD19+CD38+ B-reg cells constitute more than 1% of the total CD45+ immune cell population.

[0017] FIG. 6 shows data for B-cell percentages in CD45+ immune cell populations within NSCLC tumors. The results show a majority of NSCLC tumor samples showed elevated levels of B-reg cells in NSCLC.DETAILED DESCRIPTION

[0018] Provided and exemplified herein are inhibitors of B-reg cells (regulatory B cells) for use in a combination therapy with an ICI . Useful B-reg inhibitors include antibodies that bind CD19 and CD38, for example, a bispecific antibody that binds CD19 and CD38. Such bispecific antibodies that bind CD19 and CD38 can be characterized by an antibody comprising a CD19- binding domain and a CD38-binding domain. For example, the CD19-binding domain canWSGR Docket Number: 51527-717.601 comprise a first heavy chain variable (VH) domain and light chain variable (VL) domain that binds CD19 and a second heavy chain variable (VH) domain and light chain variable (VL) domain that binds CD38.

[0019] Antibody is used in the broadest sense and generally refers to and / or includes monoclonal antibodies, multi-valent antibodies, multi-specific, antigen-binding fragments of antibodies that bind a CD19 protein or CD38 protein. Antigen-binding fragments of antibodies (antigen-binding antibody fragments) generally refer to and / or include antibody-derived proteins that comprise a functional set of CDRs (e.g., a CDR-H1-3 and CDR-L1-3) that bind a CD19 protein or CD38 protein and have a molecule weight less than a full-length IgG antibody (e.g., a molecular weight less than ~150,00 Daltons). In certain embodiments, an antigenbinding antibody fragment (e.g., a CD19- or CD38-binding fragment) includes: fragment antigen binding (Fab) fragments, F(ab')2 fragments, Fab' fragments, Fv fragments, IgG (rlgG) fragments, and single chain antibody fragments, including single chain variable fragments (sFv or scFv). Antibodies and antigen-binding fragments of antibodies generally encompass genetically engineered, and / or otherwise modified forms of immunoglobulins, such as intrabodies, peptibodies, chimeric antibodies, fully human antibodies, humanized antibodies, and heteroconjugate antibodies, multi-specific antibodies, multi-valent antibodies, diabodies, triabodies, and tetrabodies, tandem di-scFv, tandem tri-scFv. A full-length antibody, intact antibody, and / or whole antibody are interchangeable, and generally include and / or refer to an antibody having a structure substantially similar to a native antibody structure having heavy chains that contain an Fc region and / or include antibodies of any class or sub-class, including IgG and sub-classes thereof (e.g., IgGl and lgG4), IgM, IgE, IgA, and IgD.

[0020] The term "variable region" or "variable domain" refers to the domain of an antibody heavy or light chain that is involved in binding the antibody to antigen. The variable domains of the heavy chain and light chain (VH and VL, respectively) of a native antibody generally have similar structures, with each domain comprising four conserved framework regions (FRs) and three CDRs (See e.g., Kindt et al. Kuby Immunology, 6th ed., W.H. Freeman and Co., page 91(2007)). A single VH or VL domain may be sufficient to confer antigen-binding specificity. Furthermore, antibodies that bind a particular antigen may be isolated using a VH or VL domain from an antibody that binds the antigen to screen a library of complementary VL or VH domains, respectively (See e.g., Portolano et al., J. Immunol. 150:880-887 (1993); Clarkson et al., Nature 352:624-628 (1991)).WSGR Docket Number: 51527-717.601

[0021] The terms "complementarity determining region," and "CDR," which are synonymous with "hypervariable region" or "HVR," are known in the art to refer to non-contiguous sequences of amino acids within antibody variable regions, which confer antigen specificity and / or binding affinity. In general, there are three CDRs in each heavy chain variable region (CDR-H1, CDR-H2, CDR-H3) and three CDRs in each light chain variable region (CDR-L1, CDR-L2, CDR-L3). "Framework regions" and "FR" are known in the art to refer to the non-CDR portions of the variable regions of the heavy and light chains. In general, there are four FRs in each full-length heavy chain variable region (FR-H1, FR-H2, FR-H3, and FR-H4), and four FRs in each full-length light chain variable region (FR-L1, FR-L2, FR-L3, and FR-L4). The precise amino acid sequence boundaries of a given CDR or FR can be readily determined using any of a number of well-known schemes, including those described by Kabat et al. (1991), "Sequences of Proteins of Immunological Interest," 5th Ed. Public Health Service, National Institutes of Health, Bethesda, MD ("Kabat" numbering scheme), Al-Lazikani et al., (1997) JMB 273,927-948 ("Chothia" numbering scheme); MacCallum et al., J. Mol. Biol. 262:732-745 (1996), "Antibody-antigen interactions: Contact analysis and binding site topography," J. Mol. Biol. 262, 732-745." ("Contact" numbering scheme); Lefranc MP et al., "IMGT unique numbering for immunoglobulin and T cell receptor variable domains and Ig superfamily V-like domains," Dev Comp Immunol, 2003 Jan;27(l):55-77 ("IMGT" numbering scheme); Honegger A and Pluckthun A, "Yet another numbering scheme for immunoglobulin variable domains: an automatic modeling and analysis tool," J Mol Biol, 2001 Jun 8;309(3):657-70, ("Aho" numbering scheme); and Whitelegg NR and Rees AR, "WAM: an improved algorithm for modelling antibodies on the WEB," Protein Eng. 2000 Dec;13(12):819-24 ("AbM" numbering scheme. In certain embodiments, the CDRs of the antibodies described herein can be defined by a method selected from Kabat, Chothia, IMGT, Aho, AbM, or combinations thereof.

[0022] Complementarity determining regions (CDRs) generally include amino acids within antibody variable regions that confer antigen specificity and / or binding affinity (e.g., to CD19 or CD38). In general, there are three CDRs in each heavy chain variable region (CDR-H1, CDR-H2, CDR-H3) and three CDRs in each light chain variable region (CDR-L1, CDR-L2, CDR-L3).Framework regions (FRs) generally refer to and / or include non-CDR regions of the heavy and light chain variable regions. In general, there are four FRs in each full-length heavy chain variable region (FR-H1, FR-H2, FR-H3, and FR-H4), and four FRs in each full-length light chain variable region (FR-L1, FR-L2, FR-L3, and FR-L4).WSGR Docket Number: 51527-717.601

[0023] Variable regions (also referred to as variable domains) generally refer to and / or include the domain of an antibody heavy or light chain that is involved in binding the antibody to antigen (e.g., a single variable domain comprises a CDR 1, CDR 2, and CDR 3). The variable domains of the heavy chain and light chain (VH and VL, respectively) of a native antibody generally have similar structures, with each domain comprising four conserved framework regions (FRs) and three CDRs. In certain instances, a single VH or VL domain can be sufficient to confer antigen-binding specificity.

[0024] Fc region generally encompasses and / or refers to a C-terminal region of an immunoglobulin heavy chain that contains at least a portion of the constant region. Generally, the Fc domain includes an immunoglobulin CH2 and CH3 domain (e.g., an IgG CH2 and CH3 domain). The term includes native sequence Fc regions and variant Fc regions. In one embodiment, a human IgG heavy chain Fc region extends from Cys226, or from Pro230, to the carboxyl-terminus of the heavy chain, per EU numbering. However, the C-terminal lysine (Lys447) of the Fc region may or may not be present. Unless otherwise specified herein, numbering of amino acid residues in the Fc region or constant region is according to the EU numbering system, also called the EU index, as described in Kabat et a l., Sequences of Proteins of Immunological Interest, 5th Ed. Public Health Service, National Institutes of Health, Bethesda, MD, 1991. In certain embodiments, the Fc region include IgG and sub-classes thereof (e.g., IgGl and lgG4), IgM, IgE, IgA, and / or IgD heavy chain constant regions and / or heavy chain constant regions derived from IgG and sub-classes thereof (e.g., IgGl and lgG4), IgM, IgE, IgA, and IgD.

[0025] Binding of antibodies to CD19 or CD38 can be determined by bio-layer interferometry, surface plasmon resonance, isothermal titration calorimetry, and / or ELISA. Affinity generally refers to and / or includes the strength of the sum total of noncovalent interactions between a single binding site of a molecule (e.g., an antibody) and its binding partner (e.g., an antigen such as CD19 or CD38). Unless indicated otherwise, binding affinity generally refers to intrinsic binding affinity which reflects a 1: 1 interaction between members of a binding pair (e.g., antibody and antigen). The affinity of an antibody for an antigen (e.g., CD19 or CD38) can generally be represented by the dissociation constant (KD). Affinity can be measured and determined by bio-layer interferometry, surface plasmon resonance, isothermal titration calorimetry, and / or ELISA.WSGR Docket Number: 51527-717.601

[0026] Exemplary CD38-binding CDRs include the CDRH1-3 of SEQ ID NOs: 7-9 and CDRL1-3 of SEQ ID NOs: 10-12. CD38-binding VHs include SEQ ID NO: 1 and CD19-binding VLs include SEQ ID NO: 3. In certain embodiments, a CD38-binding VH comprises a sequence having at least 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO:1, and the CD38-binding VL comprises a sequence having at least 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 3. In other embodiments, the CD38-binding CDRs and variable domains are selected from Daratumumaband Isatuximab.

[0027] Exemplary CD19-binding CDRs include the CDRH1-3 of SEQ ID NOs: 10-12 and CDRL1-3 of SEQ ID NOs: 13-15 or 23-25. CD19-binding VHs include SEQ ID NO: 2 and CD19- binding VLs include SEQ ID NO: 3 or 22. In certain embodiments, a CD19-binding VH comprises a sequence having at least 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO:2, and the CD19-binding VL comprises a sequence having at least 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 3 or 22. In other embodiments, the CD19-binding CDRs and variable domains are selected from Inebilizumab, Loncastuximab, SGN-CD19A, Tafasitamab, Taplitumomab, Blinatumomab, Coltuximab, and Denintuzumab.

[0028] As described herein, inhibitors of B-reg cells include bispecific antibodies that bind to CD19 and CD38. Bispecific antibodies can be conceived and designed to alter functionality or binding properties of the composite binding molecules or bispecific antibodies (see e.g., "Bispecific antibodies: a mechanistic review of the pipeline." Nat Rev Drug Discovery. 2019 Aug;18(8):585-608) (see e.g., "The making of bispecific antibodies" MAbs. 2017 Feb-Mar; 9(2): 182-212). For example, the bispecific antibodies that bind CD19 and CD38 can be selected from any of the following non-limiting formats: a common light chain bispecific IgG, a Fab- Fc:scFv-Fc bispecific IgG, a Fab-Fc-Fab:Fc bispecific IgG, a Fab-Fc-scFv:Fab-Fc-scFv bispecific IgG, a Fab-Fc-scFv:Fc bispecific IgG, a Fab-Fc-Fab:Fab-Fc bispecific IgG, an scFv-Fab-Fc:scFv-Fab-Fc bispecific IgG, a Fab-Fab-Fc:Fab-Fab-Fc bispecific IgG, a Fab-Fc-Fab:Fab-Fc-Fab bispecific IgG, and a Fab-Fc-scFv:Fab-Fc bispecific IgG, wherein each bispecific antibody comprises at least one CD19-binding domain (e.g., Fab or scFv) and at least one CD38-binding domain (e.g., Fab or scFv). In certain embodiments, the CD38-binding domain is Daratumumab or CD38-binding fragment thereof (e.g., having the Daratumumab VH / VL or CDRs), Isatuximab or CD38-binding fragment thereof (e.g., having the Isatuximab VH / VL or CDRs), MQR202 or CD38-binding fragment thereof (e.g., having the MQR202 VH / VL or CDRs), or TAK-079or CD38-binding fragment thereof (e.g., having the TAK-079VH / VL or CDRs). In certain embodiments, the CD19-WSGR Docket Number: 51527-717.601 binding domain is Blinatumomab or CD19-binding fragment thereof (e.g., having the Blinatumomab VH / VL or CDRs), or Tafasitamab or CD19-binding fragment thereof (e.g., having the Tafasitamab VH / VL or CDRs), or Inebilizumab or CD19-binding fragment thereof (e.g., having the Inebilizumab VH / VL or CDRs), or FMC63 or CD19-binding fragment thereof (e.g., having the FMC63 VH / VL or CDRs). In certain embodiments, the CD38-binding domain comprises the CDRH1-3 of SEQ ID NOs: 7-9 and CDRL1-3 of SEQ ID NOs: 10-12. In certain embodiments, the CD38-binding domain comprises a VH comprising a sequence having at least 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO:1, and a VL comprising a sequence having at least 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 3. In certain embodiments, the CD19-binding domain comprises the CDRH1-3 of SEQ ID NOs: 10-12 and CDRL1-3 of SEQ ID NOs: 13-15 or 23-25. In certain embodiments, the CD19-binding domain comprises a VH comprising a sequence having at least 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO:2, and a VL comprising a sequence having at least 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to SEQ ID NO: 3 or 22.

[0029] In some embodiments, the bispecific antibody is a common light chain antibody. In certain embodiments, the common light chain antibody comprises: an anti-CD38 heavy chain variable domain comprising: a heavy chain complementarity determining domain 1 (CDRH1) comprising an amino acid sequence set forth in SEQ ID NO: 7, a heavy chain complementarity determining domain 2 (CDRH2) comprising an amino acid sequence set forth in SEQ ID NO: 8, 16, 17, or 18, a heavy chain complementarity determining domain 3 (CDRH3) comprising an amino acid sequence set forth in SEQ ID NO: 9, an anti-CD19 heavy chain variable comprising: a heavy chain complementarity determining domain 1 (CDRH1) comprising an amino acid sequence set forth in SEQ ID NQ:10, a heavy chain complementarity determining domain 2 (CDRH2) comprising an amino acid sequence set forth in SEQ ID NO: 11, a heavy chain complementarity determining domain 3 (CDRH3) comprising an amino acid sequence set forth in SEQ ID NO: 12; and a common light chain variable domain comprising: a light chain complementarity determining domain 1 (CDRL1) comprising an amino acid sequence set forth in SEQ ID NO: 13 a light chain complementarity determining domainWSGR Docket Number: 51527-717.6012 (CDRL2) comprising an amino acid sequence set forth in SEQ ID NO: 14, a light chain complementarity determining domain 3 (CDRL3) comprising an amino acid sequence set forth in SEQ ID NO: 15, or a light chain complementarity determining domain 1 (CDRL1) comprising an amino acid sequence set forth in SEQ ID NO: 23 a light chain complementarity determining domain 2 (CDRL2) comprising an amino acid sequence set forth in SEQ ID NO: 24, a light chain complementarity determining domain 3 (CDRL3) comprising an amino acid sequence set forth in SEQ ID NO: 25.

[0030] In certain embodiments, the anti-CD38 heavy chain variable domain comprises the CDRH2 having the amino acid sequence set forth in SEQ ID NO: 8. In certain embodiments, the anti-CD38 heavy chain variable domain comprises the CDRH2 having the amino acid sequence set forth in SEQ ID NO: 16. In certain embodiments, the anti-CD38 heavy chain variable domain comprises the CDRH2 having the amino acid sequence set forth in SEQ ID NO: 17. In certain embodiments, the anti-CD38 heavy chain variable domain comprises the CDRH2 having the amino acid sequence set forth in SEQ ID NO: 18.

[0031] In certain embodiments, the anti-CD38 heavy chain variable domain comprises an amino acid sequence having at least 85%, 90%, 95%, 97%, 98%, 99%, or 100% to SEQ ID NO: 1, the anti-CD19 heavy chain variable domain comprises an amino acid sequence having at least 85%, 90%, 95%, 97%, 98%, 99%, or 100% to SEQ ID NO: 2, and the common light chain variable domain comprises an amino acid sequence having at least 85%, 90%, 95%, 97%, 98%, 99%, or 100% to SEQ ID NO: 3. In certain embodiments, the common light chain bispecific antibody comprises an anti-CD38 heavy chain amino acid sequence having at least 85%, 90%, 95%, 97%, 98%, 99%, or 100% to SEQ ID NO: 4, an anti-CD19 heavy chain amino acid sequence having at least 85%, 90%, 95%, 97%, 98%, 99%, or 100% to SEQ ID NO: 5, and a common light chain an anti-CD38 heavy chain amino acid sequence having at least 85%, 90%, 95%, 97%, 98%, 99%, or 100% to SEQ ID NO: 6.

[0032] In certain embodiments, the common light chain bispecific antibody further comprises a Hydrophobicity (HIC) retention time of less than about 10 minutes. In certain embodiments, the anti-CD19 heavy chain variable region comprises a serine at position 84 and / or a leucine at position 108 according to Kabat numbering. In certain embodiments, the common light chain variable region comprises a histidine at position 32 according to Kabat numbering. In certain embodiments, the pl is less than 9. In certain embodiments, the pl isWSGR Docket Number: 51527-717.601 between 8 and 9. In certain embodiments, the pl is between 8.5 and 9.0. In certain embodiments, the pl is between 8.7 and 9.0. In certain embodiments, the pl is between 8.8 and 9.0. In certain embodiments, the pl is 8.9.Immune Checkpoint Inhibitors

[0033] As provided and exemplified herein, Immune checkpoint inhibitors (ICIs) can be combined (concurrently or separately) with the inhibitor of B regulatory (B-reg) cells to treat a tumor. Exemplary ICIs include PD-1 / PD-L1 axis inhibitors, CLTA-4 inhibitors, LAG-3 inhibitors, TIM-3 inhibitors, TIGT inhibitors. These generally target the immune checkpoint proteins: PD-1, PD-L1, CTLA-4, TIM-3, LAG-3, or TIGIT. Such ICIs are generally advantageous as a result of their ability to target T cell immune checkpoint proteins. Accordingly, in some embodiments, the ICI is an inhibitor of a T-cell immune checkpoint protein.

[0034] In some embodiments, the ICI is a PD-1 inhibitor. In certain embodiments, the PD-1 inhibitor is an anti-PD-1 antibody. Exemplary anti-PD-1 antibodies include Pembrolizumab, Nivolumab, Dostarlimab, Retifanlimab, Spartalizumab, Camrelizumab, Sintilimab, Cemi plimab, Tislelizumab, Penpulimab, Zimberelimab, Toripalimab, AMP-514 (MEDI0680), and Acrixolimab (YBL-006). In certain embodiments, the anti-PD-1 antibody is Pembrolizumab, Nivolumab, Dostarlimab, Retifanlimab, Spartalizumab, Camrelizumab, Sintilimab, Cemi plimab, Tislelizumab, Penpulimab, Zimberelimab, Toripalimab, AMP-514 (MEDI0680), or Acrixolimab (YBL-006).

[0035] In some embodiments, the ICI is a PD-L1 inhibitor. In certain embodiments, the PD- L1 inhibitor is an anti-PD-Ll antibody. Exemplary anti-PD-Ll antibodies include Atezolizumab, Avelumab, Durvalumab, Envafolimab (KN035), and Cosibelimab (CK-301). Exemplary nonantibody inhibitors include AUNP12, CA-170, and BMS-986189. In certain embodiments, the anti-PD-Ll antibody is Atezolizumab, Avelumab, Durvalumab, Envafolimab (KN035), or Cosibelimab (CK-301).

[0036] In some embodiments, the ICI is a CTLA-4 inhibitor. In certain embodiments, the CTLA-4 inhibitor is an anti-CTLA-4 antibody. Exemplary antiCTLA-4 antibodies include Ipilimumab, Tremelimumab, Quavonlimab, Botensilimab, Zalifrelimab, Gotistobart, HCAb 4003- 2 and XTX101. In certain embodiments, the anti-CTLA-4 antibody is Ipilimumab, Tremelimumab, Quavonlimab, Botensilimab, Zalifrelimab, Gotistobart, HCAb 4003-2 or XTX101.

[0037] In some embodiments, the ICI is a LAG-3 inhibitor. In certain embodiments, the LAG-3 inhibitor is an anti- LAG-3 antibody. Exemplary anti-LAG-3 antibodies include Relatlimab,WSGR Docket Number: 51527-717.601Leramilimab, Favezelimab, Encelimab (TSR-033), Fianlimab, SymO22, INCAGN02385, BI754111, LBL-007, and HLX26. In certain embodiments, the anti-LAG-3 antibody is Relatlimab, Leramilimab, Favezelimab, Encelimab (TSR-033), Fianlimab, Sym022, INCAGN02385, BI754111, LBL-007, or HLX26.

[0038] In some embodiments, the ICI is a TIM-3 inhibitor. In certain embodiments, the TIM- 3 inhibitor is an anti- TIM-3 antibody. Exemplary anti-TIM-3 antibodies include Sabatolimab (MBG453), MsTOOl, MsT065, MsT229, Cobolimab (TSR-022), Sym023, LY3321367, LY3415244, MBG-A425, and MsT286. In certain embodiments, the anti-TIM-3 antibody is Sabatolimab (MBG453), MsTOOl, MsT065, MsT229, Cobolimab (TSR-022), Sym023, LY3321367, LY3415244, MBG-A425, or MsT286.

[0039] In some embodiments, the ICI is a TIG IT inhibitor. In certain embodiments, the TIGIT inhibitor is an anti- TIGIT antibody. Exemplary a nti-TI GIT antibodies include Vibostolimab, Etigilimab, Tiragolumab, Domvanalimab, Ociperlimab, Belrestotug (EOS-448), BMS-986207, ASP8374, COM902, and Tamgiblimab (IBI939). In certain embodiments, the anti-TIGIT antibody is Vibostolimab, Etigilimab, Tiragolumab, Domvanalimab, Ociperlimab, Belrestotug (EOS-448), BMS-986207, ASP8374, COM902, or Tamgiblimab (IBI939).Pharmaceutical compositions

[0040] In some embodiments, provided herein are pharmaceutical compositions and / or formulations comprising the bispecific antibody that binds CD19 and CD38. Pharmaceutical compositions include and / or refers a preparation that is in such form as to permit biological activity of the antibody or antibody fragment, and that contains no additional components which are unacceptably toxic to a subject to which the formulation would be administered. In certain embodiments, the pharmaceutical composition comprises a pharmaceutically acceptable carrier (e.g., an ingredient in a pharmaceutical formulation, other than an active ingredient, which is nontoxic to an individual). A pharmaceutically acceptable carrier includes, but is not limited to, a buffer, excipient, stabilizer, or preservative. The formulation of pharmaceutically active ingredients (e.g., an antibody or antibody fragment) with pharmaceutically acceptable carriers is known in the art, e.g.: Remington: The Science and Practice of Pharmacy (e.g. 21st edition (2005), and any later editions); Wang SS, Yan YS, Ho K. US FDA-approved therapeutic antibodies with high-concentration formulation: summaries and perspectives. Antib Ther. 2021 Nov 18;4(4):262-272. doi: 10.1093 / abt / tbab027. PMID:WSGR Docket Number: 51527-717.60134909579; and / or AA Elkordy. Formulation of Monoclonal Antibody Therapies. 2023. (978-0-12- 823365-8). Non-limiting examples of additional ingredients include; buffers, diluents, solvents, tonicity regulating agents, preservatives, stabilizers, and chelating agents. One or more pharmaceutically acceptable carrier may be used in formulating the pharmaceutical compositions of the invention.

[0041] In certain embodiments, the pharmaceutical composition is a liquid formulation such as a liquid formulation. In certain embodiments, the liquid formulation is an aqueous formulation, i.e., a formulation comprising water. An aqueous formulation typically comprises at least 50% w / w water, or at least 60%, 70%, 75%, 80%, 85%, 90%, or at least 95% w / w of water.Methods

[0042] The inhibitors of B-reg cells provided herein are useful in methods for treating cancer. Provided and exemplified herein are a methods treating a cancer in an individual in need thereof, the method comprising: administering to the individual: (i) a therapeutically effective amount of an inhibitor of B regulatory (B-reg) cells; and (ii) a therapeutically effective amount of an immune checkpoint inhibitor (ICI).

[0043] The inhibitors of B-reg cells can reduce the amount of B-reg cells in the circulation or in a tumor or tumor microenvironment of an individual. In certain embodiments, the methods described herein does nor substantially reduce non B-reg ell populations. In certain embodiments, there is no substantial reduction in non B-reg cells compared to a pan B cell inhtibor (e.g., tafasitamab). In certain embodiments, non B-reg cells comprise B cells positive or highly positive for CD20 and CD19.

[0044] Further provided and exemplified herein are methods of treating a cancer in an individual in need thereof, wherein the cancer comprises a tumor characterized by (i) a blood sample taken from the individual having a percentage of B-reg cells greater than 1.0 of the percent total B cells (e.g., CD19+ cells) or (ii) a tumor sample taken from the individual having a B-reg cells, optionally wherein the tumor sample taken from the individual comprises B-reg cells in a sample of CD45+ cells from the tumor sample, the method comprising: administering an inhibitor of B regulatory (B-reg) cells to the individual. Also provided herein are methods method of treating a cancer in an individual, the method comprising: (a) determining the percentage of B-reg cells in: (i) a blood sample taken from the individual, or (ii) a tumorWSGR Docket Number: 51527-717.601 sample taken from the individual; and (b) administering to the individual: (i) a therapeutically effective amount of an inhibitor of B regulatory (B-reg) cells if the percentage of B-reg cells is in the blood sample is greater than 1.0% of the percent total B cells, or (ii) a therapeutically effective amount of an inhibitor of B regulatory (B-reg) cells if B-reg cells are present in the tumor sample. In certain embodiments, the methods comprise administering: (i) a therapeutically effective amount of the inhibitor of B regulatory (B-reg) cells; and (ii) a therapeutically effective amount of an immune checkpoint inhibitor (ICI).

[0045] In certain instances, relating to B cells within a blood sample, the percentage of B- reg cells is greater than 1.1%, 1.2%, 1.3%, 1.4%, or 1.5% of the percent total B cells. In certain embodiments, the percentage of B-reg cells is greater than 1.3% of the percent total B cells. In certain embodiments, the percentage of B-reg cells is greater than 1.2% of the percent total B cells. In certain embodiments, the percentage of B-reg cells is greater than 1.3% of the percent total B cells. In certain embodiments, the percentage of B-reg cells is greater than 1.4% of the percent total B cells. In certain embodiments, the percentage of B-reg cells is greater than 1.5% of the percent total B cells.

[0046] In certain instances, relating to B cells within a tumor sample, the presence of B-reg cells indicates the presence of immunosuppressive B cells. In certain embodiments, the B-reg cells are present within the tumor sample. In certain embodiments, the percentage of B-reg cells is greater than 0.1% of the percent total CD45+ cells in the tumor sample. In certain embodiments, the percentage of B-reg cells is greater than 0.5% of the percent total CD45+ cells in the tumor sample. In certain embodiments, the percentage of B-reg cells is greater than 1% of the percent total CD45+ cells in the tumor sample In certain embodiments, the percentage of B-reg cells is greater than 2% of the percent total CD45+ cells in the tumor sample.

[0047] In some embodiments, the B-reg cells are characterized as CD19+CD38+. In certain embodiments, the CD19+CD38+ B-reg cells are CD20-. In certain embodiments, the CD19+CD38+ B-reg cells are CD19+CD38HIGH. In certain embodiments, the B-reg cells are further characterized as CD19+CD38+CD20LOWor CD19+CD38+CD20NEGor CD19+CD38HIGHCD20LOWor CD19+CD38HIGHCD20NEG. A CD38 high phenotype can be suitably determined by the skilled artisan. In certain embodiments, a CD38 high phenotype is determined by an assay on the cell surface expression of CD38 (e.g., flow cytometry, plate assays read by fluorescence plate readers, or microscopy). However, other methods can inWSGR Docket Number: 51527-717.601 certain instances, to the extent that such methods correlate with high surface level expression CD38, be used to determine a CD38 high phenotype (e.g., analyzing levels of mRNA or intracellular or total CD38 protein in a biological sample).

[0048] A CD38 high phenotype can be indicated by a percentage of CD38 positive B Cells in the peripheral blood. In certain embodiments, assay results indicate a CD38 high phenotype if greater than about 1 %, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, or 4.0% of CD19+ CD20- cells in the peripheral blood are CD38 positive. Such positivity can be determined by flow cytometry or microscopy by comparison to a control (e.g., isotype matched control antibody of fluorescent bead controls). In certain embodiments, the CD38 high phenotype is indicated in a patient with a solid tumor. A CD38 high phenotype can also be indicated by a percentage of CD38 positive B Cells in a biopsy sample of a tumor. In certain embodiments, assay results indicate a CD38 high phenotype if greater than about 10 %, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50% of CD19+ CD20- cells in the peripheral blood are CD38 positive. Such positivity can be determined by flow cytometry or microscopy by comparison to a control (e.g., isotype matched control antibody of fluorescent bead controls). In certain embodiments, the CD38 high phenotype is indicated in a patient with a solid tumor. A CD38 high phenotype can be indicated by making a determination of absolute numbers of CD38 molecules on the surface of a B cell. In certain embodiments, assay results indicate a CD38 high phenotype if greater than about 30,000, 35,000, 40,000, 45,000, 50,000, 55,000, 60,000, 65,000, on average are present on B cells with that are positive for CD19.

[0049] A CD20 negative phenotype can be identified by lack of detectable expression of CD20 (when compared to isotype control) by a standard assay such as flow cytometry. A CD20 low phenotype can be identified by low levels of expression of CD20 (e.g., less than a mature non-immunosuppressive or regulatory B CD19 positive, CD20 positive B cell). In certain embodiments, the CD20low B cell expresses 2-fold, 3-fold, or 4-fold less cell surface CD20 than a non-regulatory or immunosuppressive B cell.

[0050] Suitable inhibitor of B-reg cells included bispecific antibodies that bind CD-19 and CD-38. In some embodiments, the inhibitor of B-reg cells comprises a bispecific antibody or bispecific antibody fragment that binds CD19 and CD38. In certain embodiments, the bispecific antibody or bispecific antibody fragment that binds CD19 and CD38 comprises: an anti-CD38 heavy chain variable domain and an anti-CD38 light chain variable domain; and an anti-CD19 heavy chain variable domain and an anti-CD19 light chain variable domain. In certainWSGR Docket Number: 51527-717.601 embodiments, the bispecific antibody is a common light chain bispecific IgG, a Fab-Fc:scFv-Fc bispecific IgG, a Fab-Fc-Fab:Fc bispecific IgG, a Fab-Fc-scFv:Fab-Fc-scFv bispecific IgG, a Fab-Fc- scFv:Fc bispecific IgG, a Fab-Fc-Fab:Fab-Fc bispecific IgG, an scFv-Fab-Fc:scFv-Fab-Fc bispecific IgG, a Fab-Fab-Fc:Fab-Fab-Fc bispecific IgG, a Fab-Fc-Fab:Fab-Fc-Fab bispecific IgG, or a Fab-Fc- scFv:Fab-Fc bispecific IgG, wherein each bispecific antibody comprises at least one CD19- binding domain (e.g., Fab or scFv) and at least one CD38-binding domain (e.g., Fab or scFv), as described herein.

[0051] The bispecific antibodies described herein are advantageous in that they deplete B- reg cells incubated with cancer patient allogeneic PBMCs. In some embodiments, the bispecific antibody or bispecific antibody fragment that binds CD19 and CD38 depletes B-reg cells (e.g., the B-reg cells are CD19+CD38+CD20_B-reg cells) incubated with cancer patient allogeneic PBMCs. In certain embodiments, the bispecific antibody or bispecific antibody fragment that binds CD19 and CD38 preserves non-target immune cells in healthy donor PMBCs and / or cancer patient PBMCs. Examples of non-target immune cells include CD3+CD38+ immune cells, CD20+CD38+immune cells, CD56+CD38 immune cells, and / or CDllb / c+CD38+immune cells.

[0052] Suitable ICI inhibitors include PD-1 / PD-L1 axis inhibitors, CTLA5 inhibitors, Lag-3 inhibitors, Tim-3 inhibitors, and TIG IT inhibitors. In some embodiments, the ICI is a PD-1 / PD-L1 axis inhibitor is an antibody. In certain embodiments, the antibody is an anti-PD-1 Antibody. Anti-PD-1 antibodies include Pembrolizumab, Nivolumab, Dostarlimab, Retifanlimab, Spartalizumab, Camrelizumab, Sintilimab, Cemiplimab, Tislelizumab, Penpulimab, Zimberelimab, Toripalimab, AMP-514 (MEDI0680), Acrixolimab (YBL-006), or a combination thereof. In some embodiments, the antibody is an anti-PD-Ll antibody. Anti-PD-Ll antibodies include Atezolizumab, Avelumab, Durvalumab, Envafolimab (KN035), Cosibelimab (CK-301), or a combination thereof. In some embodiments, the ICI is a CTLA-4 inhibitor. In certain embodiments, the CTLA-4 inhibitor is an antibody. Anti-CLTA-4 antibodies include Ipilimumab, Tremelimumab, Quavonlimab, Botensilimab, Zalifrelimab, Gotistobart, XTX101, HCAb 4003-2, or a combination thereof. In some embodiments, the ICI is a Lag-3 inhibitor. Anti-Lag-3 antibodies include Relatlimab, Leramilimab, Favezelimab, Encelimab (TSR-033), Fianlimab, Sym022, INCAGN02385, BI754111, LBL-007, HLX26, or a combination thereof. In some embodiments, the ICI is a TIM-3 inhibitor. Anti-TIM-3 antibodies include Sabatolimab (MBG453), MsTOOl, MsT065, MsT229, Cobolimab (TSR-022), Sym023, LY3321367, LY3415244, MBG-A425, MsT286, or a combination thereof. In some embodiments, the ICI is a TIG ITWSGR Docket Number: 51527-717.601 inhibitor. Anti-TIGIT antibodies include Vibostolimab, Etigilimab, Tiragolumab, Domvanalimab, Ociperlimab, Belrestotug (EOS-448), BMS-986207, ASP8374, COM902, Tamgiblimab (IBI939), or a combination thereof.

[0053] The methods described and exemplified herein are useful in treating a cancer or a tumor associated with an increased number of B-reg cells. For example, the methods described herein are useful in treating cancers characterized by a blood sample taken from the individual and having a percentage of B-reg cells greater than 1.5%. In certain embodiments, the percentage of B-reg cells greater than 1.4%. In certain embodiments, the percentage of B-reg cells greater than 1.3%. In certain embodiments, the percentage of B-reg cells greater than 1.2%. In certain embodiments, the percentage of B-reg cells greater than 1.1%. In certain embodiments, the percentage of B-reg cells greater than 1.0%. The methods described and exemplified herein are also useful in treating a cancer comprising a solid tumor or a liquid tumor (blood tumor). In some embodiments, the cancer comprises lung cancer, colorectal cancer, head and neck carcinoma, or pancreatic cancer. In certain embodiments, the cancer is non-small cell lung cancer, colorectal adenocarcinoma, head and neck squamous cell carcinoma, or pancreatic adenocarcinoma.

[0054] In some embodiments, the cancer is resistant to ICI therapy. In some embodiments, the cancer is relapsed or refractory to ICI therapy. In some embodiments, the cancer is a progressive cancer. As used herein, "resistant" includes both primary resistance and acquired resistance. Primary resistance is defined as cancer that never responds to ICI therapy, characterized by either progressive disease at the first radiologic evaluation or no evidence of clinical benefit within approximately six months of treatment initiation. Acquired resistance, also referred to as relapse after response, occurs when the cancer initially responds or stabilizes but subsequently progresses while still on treatment, typically after at least six months of clinical benefit. Refractory cancer is defined as cancers that are unresponsive despite continued treatment or that progress rapidly after cessation of therapy.

[0055] In some embodiments, an individual treated by the methods described herein has received one or more anti-neoplastic treatments including a previous ICI therapy, such as a previous anti-PD-1, anti-PD-Ll, or anti CTLA-4 treatment.

[0056] In some embodiments, the inhibitor of B regulatory (B-reg) cells is administered concurrently with the immune checkpoint inhibitor (ICI). In some embodiments, the inhibitor of B regulatory (B-reg) cells and the immune checkpoint inhibitor (ICI) are administeredWSGR Docket Number: 51527-717.601 separately. In some embodiment, the inhibitor of B regulatory (B-reg) cells and the immune checkpoint inhibitor (I Cl ) are administered separately according to different treatments schedules. In some embodiments, the wherein the individual is currently receiving or has previously received an ICI therapy.

[0057] Treating, as describe herein, includes reducing tumor volume as compared to treatment with the ICI alone and / or reducing the rate of tumor growth as compared to treatment with the ICI alone.

[0058] The antibodies can be administered to a subject in need thereof by any route suitable for the administration of antibody-containing pharmaceutical compositions, such as, for example, subcutaneous, intraperitoneal, intravenous, intramuscular, intratumoral, or intracerebral, etc. In certain embodiments, the antibodies are administered intravenously. In certain embodiments, the antibodies are administered subcutaneously. In certain embodiments, the antibodies are administered intratumoral.

[0059] The methods described herein can treat individuals afflicted with a cancer or a tumor. In certain embodiments, the cancer or tumor is a solid cancer or tumor. In certain embodiments, the cancer or tumor is a blood cancer or tumor. In certain embodiments, the cancer or tumor comprises breast, heart, lung, small intestine, colon, spleen, kidney, bladder, head, neck, ovarian, prostate, brain, pancreatic, skin, bone, bone marrow, blood, thymus, uterine, testicular, and liver tumors. In certain embodiments, tumors which can be treated with the antibodies of the invention comprise adenoma, adenocarcinoma, angiosarcoma, astrocytoma, epithelial carcinoma, germinoma, glioblastoma, glioma, hemangioendothelioma, hemangiosarcoma, hematoma, hepatoblastoma, leukemia, lymphoma, medulloblastoma, melanoma, neuroblastoma, osteosarcoma, retinoblastoma, rhabdomyosarcoma, sarcoma and / or teratoma. In certain embodiments, the tumor / cancer is selected from the group of acral lentiginous melanoma, actinic keratosis, adenocarcinoma, adenoid cystic carcinoma, adenomas, adenosarcoma, adenosquamous carcinoma, astrocytic tumors, Bartholin gland carcinoma, basal cell carcinoma, bronchial gland carcinoma, capillary carcinoid, carcinoma, carcinosarcoma, cholangiocarcinoma, chondrosarcoma, cystadenoma, endodermal sinus tumor, endometrial hyperplasia, endometrial stromal sarcoma, endometrioid adenocarcinoma, ependymal sarcoma, Swing's sarcoma, focal nodular hyperplasia, gastronoma, germ line tumors, glioblastoma, glucagonoma, hemangioblastoma, hemangioendothelioma, hemangioma, hepatic adenoma, hepatic adenomatosis, hepatocellular carcinoma, insulinite,WSGR Docket Number: 51527-717.601 intraepithelial neoplasia, intraepithelial squamous cell neoplasia, invasive squamous cell carcinoma, large cell carcinoma, liposarcoma, lung carcinoma, lymphoblastic leukemia, lymphocytic leukemia, leiomyosarcoma, melanoma, malignant melanoma, malignant mesothelial tumor, nerve sheath tumor, medulloblastoma, medulloepithelioma, mesothelioma, mucoepidermoid carcinoma, myeloid leukemia, neuroblastoma, neuroepithelial adenocarcinoma, nodular melanoma, osteosarcoma, ovarian carcinoma, papillary serous adenocarcinoma, pituitary tumors, plasmacytoma, pseudosarcoma, prostate carcinoma, pulmonary blastoma, renal cell carcinoma, retinoblastoma, rhabdomyosarcoma, sarcoma, serous carcinoma, squamous cell carcinoma, small cell carcinoma, soft tissue carcinoma, somatostatin secreting tumor, squamous carcinoma, squamous cell carcinoma, undifferentiated carcinoma, uveal melanoma, verrucous carcinoma, vagina / vulva carcinoma, VIPpoma, and Wilm's tumor. In certain embodiments, the tumor / cancer to be treated with one or more antibodies of the invention comprise brain cancer, head and neck cancer, colorectal carcinoma, acute myeloid leukemia, pre-B-cell acute lymphoblastic leukemia, bladder cancer, astrocytoma, preferably grade II, III or IV astrocytoma, glioblastoma, glioblastoma multiforme, small cell cancer, and non-small cell cancer, preferably non-small cell lung cancer, lung adenocarcinoma, metastatic melanoma, androgen-independent metastatic prostate cancer, androgen-dependent metastatic prostate cancer, prostate adenocarcinoma, and breast cancer, preferably breast ductal cancer, and / or breast carcinoma. In certain embodiments, the cancer treated with the antibodies of this disclosure comprises glioblastoma. In certain embodiments, the cancer treated with one or more antibodies of this disclosure comprises pancreatic cancer. In certain embodiments, the cancer treated with one or more antibodies of this disclosure comprises ovarian cancer. In certain embodiments, the cancer treated with one or more antibodies of this disclosure comprises lung cancer. In certain embodiments, the cancer treated with one or more antibodies of this disclosure comprises prostate cancer. In certain embodiments, the cancer treated with one or more antibodies of this disclosure comprises colon cancer. In certain embodiments, the cancer treated comprises glioblastoma, pancreatic cancer, ovarian cancer, colon cancer, prostate cancer, or lung cancer. In a certain embodiment, the cancer is refractory to other treatment. In a certain embodiment, the cancer treated is relapsed.

[0060] In certain embodiments the inhibitor of B regulatory (B-reg) cells of the current disclosure are included in a pharmaceutical composition comprising one or moreWSGR Docket Number: 51527-717.601 pharmaceutically acceptable excipients, carriers, and diluents. Pharmaceutically acceptable excipients, carriers and diluents can be included to increase shelf-life, stability, or the administrability of the antibody. Such compounds include salts, pH buffers, detergents, anticoagulants, and preservatives. In certain embodiments, the antibodies of the current disclosure are administered suspended in a sterile solution. In certain embodiments, the solution comprises about 0.9% NaCI. In certain embodiments, the solution comprises about 5.0% dextrose. In certain embodiments, the solution further comprises one or more of: buffers, for example, acetate, citrate, histidine, succinate, phosphate, bicarbonate and hydroxymethylaminomethane (Tris); surfactants, for example, polysorbate 80 (Tween 80), polysorbate 20 (Tween 20), and poloxamer 188; polyol / disaccharide / polysaccharides, for example, glucose, dextrose, mannose, mannitol, sorbitol, sucrose, trehalose, and dextran 40; amino acids, for example, glycine or arginine; antioxidants, for example, ascorbic acid, methionine; or chelating agents, for example, EDTA or EGTA.

[0061] In certain embodiments, the inhibitor of B regulatory (B-reg) cells of the current disclosure can be shipped / stored lyophilized and reconstituted before administration. In certain embodiments, lyophilized antibody formulations comprise a bulking agent such as, mannitol, sorbitol, sucrose, trehalose, dextran 40, or combinations thereof. The lyophilized formulation can be contained in a vial comprised of glass or other suitable non-reactive material. The inhibitor of B regulatory (B-reg) cells when formulated, whether reconstituted or not, can be buffered at a certain pH, generally less than 7.0. In certain embodiments, the pH can be between 4.5 and 7.0, 4.5 and 6.5, 4.5 and 6.0, 4.5 and 5.5, 4.5 and 5.0, or 5.0 and 6.0.

[0062] Also described herein are kits comprising one or more of the inhibitor of B regulatory (B-reg) cells described herein in a suitable container and one or more additional components selected from: instructions for use; a diluent, an excipient, a carrier, and a device for administration.Exemplary Embodiments

[0063] Embodiment 1: A method of treating a cancer in an individual in need thereof, the method comprising: administering to the individual: (i) a therapeutically effective amount of an inhibitor of B regulatory (B-reg) cells; and (ii) a therapeutically effective amount of an immune checkpoint inhibitor (ICI).WSGR Docket Number: 51527-717.601

[0064] Embodiment 2: A method of treating a cancer in an individual in need thereof, wherein the cancer comprises a tumor characterized by (i) a blood sample taken from the individual having a percentage of B-reg cells greater than 1% of the percent total CD19 positive B cells or (ii) a biological sample taken from the individual having B-reg cells, the method comprising: administering an inhibitor of B regulatory (B-reg) cells to the individual.

[0065] Embodiment 3: A method of treating a cancer in an individual in need thereof, the method comprising: (a) determining the percentage of B-reg cells in: (i) a blood sample taken from the individual, or (ii) a tumor sample taken from the individual, and (b) administering to the individual: (i) a therapeutically effective amount of an inhibitor of B regulatory (B-reg) cells if the percentage of B-reg cells in the blood sample is greater than 1.0% of the percent total B cells in the blood sample, or (ii) a therapeutically effective amount of an inhibitor of B regulatory (B-reg) cells if B-reg cells are present in the tumor sample, optionally wherein the B-reg cells are present among total CD45+ cells taken from the tumor sample.

[0066] Embodiment 4: The method of embodiment 2 or embodiment 3, wherein the method comprises administering: (i) the inhibitor of B regulatory (B-reg) cells; and (ii) an immune checkpoint inhibitor (ICI).

[0067] Embodiment 5: The method of any one of the preceding embodiments, wherein the B-reg cells are characterized as CD19+CD38+, optionally wherein the B-reg cells are characterized as CD19+CD38+CD20LOWor CD19+CD38+CD20NEG.

[0068] Embodiment 6: The method of any one of the preceding embodiments, wherein the B-reg cells are characterized as CD19+CD38HIGH, optionally wherein the B-reg cells are characterized as CD19+CD38HIGHCD20LOWor CD19+CD38HIGHCD20NEG.

[0069] Embodiment 7: The method of any one of the preceding embodiments, wherein the ICI is a T-cell ICI.

[0070] Embodiment 8: The method of any one of the preceding embodiments, wherein the inhibitor of B-reg cells comprises a bispecific antibody or bispecific antibody fragment that binds CD19 and CD38.

[0071] Embodiment 9: The method of embodiment 8, wherein the bispecific antibody or bispecific antibody fragment that binds CD19 and CD38 comprises: an anti-CD38 heavy chain variable domain and an anti-CD38 light chain variable domain; and an anti-CD19 heavy chain variable domain and an anti-CD19 light chain variable domain.WSGR Docket Number: 51527-717.601

[0072] Embodiment 10: The method of embodiment 9, wherein: the anti-CD38 heavy chain variable domain comprises: a heavy chain complementarity determining domain 1 (CDRH1) comprising an amino acid sequence set forth in SEQ ID NO: 7, a heavy chain complementarity determining domain 2 (CDRH2) comprising an amino acid sequence set forth in SEQ ID NO: 8, 16. 17, or 18, a heavy chain complementarity determining domain 3 (CDRH3) comprising an amino acid sequence set forth in SEQ ID NO: 9, the anti-CD38 light chain variable domain comprises: a light chain complementarity determining domain 1 (CDRL1) comprising an amino acid sequence set forth in SEQ ID NO: 13 a light chain complementarity determining domain 2 (CDRL2) comprising an amino acid sequence set forth in SEQ ID NO: 14, a light chain complementarity determining domain 3 (CDRL3) comprising an amino acid sequence set forth in SEQ ID NO: 15, or a light chain complementarity determining domain 1 (CDRL1) comprising an amino acid sequence set forth in SEQ ID NO: 23 a light chain complementarity determining domain 2 (CDRL2) comprising an amino acid sequence set forth in SEQ ID NO: 24, a light chain complementarity determining domain 3 (CDRL3) comprising an amino acid sequence set forth in SEQ ID NO: 25, the anti-CD19 heavy chain variable domain comprising: a heavy chain complementarity determining domain 1 (CDRH1) comprising an amino acid sequence set forth in SEQ ID NQ:10, a heavy chain complementarity determining domain 2 (CDRH2) comprising an amino acid sequence set forth in SEQ ID NO: 11, a heavy chain complementarity determining domain 3 (CDRH3) comprising an amino acid sequence set forth in SEQ ID NO: 12; and the anti-CD19 light chain variable domain comprises: a light chain complementarity determining domain 1 (CDRL1) comprising an amino acid sequence set forth in SEQ ID NO: 13 a light chain complementarity determining domain 2 (CDRL2) comprising an amino acid sequence set forth in SEQ ID NO: 14, a light chain complementarity determining domain 3 (CDRL3) comprising an a mino acid sequence set forth in SEQ ID NO: 15, or a light chain complementarity determining domain 1 (CDRL1) comprising an amino acid sequence set forth in SEQ ID NO: 23 a light chain complementarity determining domain 2 (CDRL2) comprising an amino acid sequence set forth in SEQ ID NO: 24, a light chain complementarity determining domain 3 (CDRL3) comprising an amino acid sequence set forth in SEQ ID NO: 25.

[0073] Embodiment 11: The method of embodiments 8-10, wherein the bispecific antibody or bispecific antibody fragment that binds CD19 and CD38 depletes B-reg cells incubated with cancer patient allogeneic PBMCs.WSGR Docket Number: 51527-717.601

[0074] Embodiment 12: The method of embodiment 11, wherein the B-reg cells are CD19+CD38+CD20- B-reg cells.

[0075] Embodiment 13: The method of any one of embodiments 8-12, wherein the bispecific antibody or bispecific antibody fragment that binds CD19 and CD38 preserves non-target immune cells in healthy donor PMBCs and / or cancer patient PBMCs.

[0076] Embodiment 14: The method of embodiment 13, wherein the non-target immune cells comprise CD3+CD38+ immune cells, CD20+CD38+immune cells, CD56+CD38 immune cells, and / or CDllb / c+CD38+immune cells.

[0077] Embodiment 15: The method of any one of embodiments 8-14, wherein the bispecific antibody or bispecific antibody fragment that binds CD19 and CD38 is a common light chain bispecific antibody.

[0078] Embodiment 16: The method of embodiment 15, wherein the common light chain bispecific antibody comprises: an anti-CD38 heavy chain variable domain comprising: a heavy chain complementarity determining domain 1 (CDRH1) comprising an amino acid sequence set forth in SEQ ID NO: 7, a heavy chain complementarity determining domain 2 (CDRH2) comprising an amino acid sequence set forth in SEQ ID NO: 8, 16. 17, or 18, a heavy chain complementarity determining domain 3 (CDRH3) comprising an amino acid sequence set forth in SEQ ID NO: 9, an anti-CD19 heavy chain variable comprising: a heavy chain complementarity determining domain 1 (CDRH1) comprising an amino acid sequence set forth in SEQ ID NQ:10, a heavy chain complementarity determining domain 2 (CDRH2) comprising an amino acid sequence set forth in SEQ ID NO: 11, a heavy chain complementarity determining domain 3 (CDRH3) comprising an amino acid sequence set forth in SEQ ID NO: 12; and a common light chain variable domain comprising: a light chain complementarity determining domain 1 (CDRL1) comprising an amino acid sequence set forth in SEQ ID NO: 13 a light chain complementarity determining domain 2 (CDRL2) comprising an amino acid sequence set forth in SEQ ID NO: 14, a light chain complementarity determining domain 3 (CDRL3) comprising an amino acid sequence set forth in SEQ ID NO: 15, or a light chain complementarity determining domain 1 (CDRL1) comprising an amino acid sequence set forth in SEQ ID NO: 23 a light chain complementarity determining domain 2 (CDRL2) comprising an amino acid sequence set forth in SEQ ID NO: 24, a light chain complementarity determining domain 3 (CDRL3) comprising an amino acid sequence set forth in SEQ ID NO: 25.WSGR Docket Number: 51527-717.601

[0079] Embodiment 17: The method of embodiment 16, wherein the anti-CD38 heavy chain variable domain comprises an amino acid sequence having at least 85%, 90%, 95%, 97%, 98%, 99%, or 100% to SEQ ID NO: 1, the anti-CD19 heavy chain variable domain comprises an amino acid sequence having at least 85%, 90%, 95%, 97%, 98%, 99%, or 100% to SEQ ID NO: 2, and common light chain variable domain comprises an amino acid sequence having at least 85%, 90%, 95%, 97%, 98%, 99%, or 100% to SEQ ID NO: 3.

[0080] Embodiment 18: The method of embodiment 16, wherein the common light chain bispecific antibody comprises an anti-CD38 heavy chain amino acid sequence having at least 85%, 90%, 95%, 97%, 98%, 99%, or 100% to SEQ ID NO: 4, an anti-CD19 heavy chain amino acid sequence having at least 85%, 90%, 95%, 97%, 98%, 99%, or 100% to SEQ ID NO: 5, and a common light chain an anti-CD38 heavy chain amino acid sequence having at least 85%, 90%, 95%, 97%, 98%, 99%, or 100% to SEQ ID NO: 6.

[0081] Embodiment 19: The method of any one of embodiments 16-18, wherein: the anti- CD38 heavy chain variable domain and the anti-CD19 heavy chain variable domain each comprise a negatively-charged amino acid at heavy chain variable domain position 1 per Kabat numbering; the anti-CD38 heavy chain constant domain and the anti-CD19 heavy chain constant domain each lack a C-terminal lysine residue (K447 per EU numbering); and the common light chain bispecific antibody comprises an experimental isoelectric point (pl) of less than 9.

[0082] Embodiment 20: The method of embodiment 19, wherein the common light chain bispecific antibody exhibits a Hydrophobicity (HIC) retention time of less than about 10 minutes.

[0083] Embodiment 21: The method of any one of embodiments 19-20, wherein the terminal lysine residue is K447 per EU numbering.

[0084] Embodiment 22: The method of any one of embodiments 8-21, wherein the anti- CD19 heavy chain variable domain comprises a serine at position 84 and / or a leucine at position 108 according to Kabat numbering.

[0085] Embodiment 23: The method of any one of embodiments 8-22, wherein the common light chain variable region comprises a histidine at position 32 according to Kabat numbering.

[0086] Embodiment 24: The method of any one of embodiments 19-23, wherein the negatively-charged amino acid is glutamic acid.

[0087] Embodiment 25: The method of any one of embodiments 19-24, wherein the pl is between 8.7 and 9.WSGR Docket Number: 51527-717.601

[0088] Embodiment 26: The method of any one of the preceding embodiments, wherein theICI is a PD-1 / PD-L1 axis inhibitor.

[0089] Embodiment 27: The method of embodiment 26, wherein the PD-1 / PD-L1 axis inhibitor is an antibody.

[0090] Embodiment 28: The method of embodiment 27, wherein the antibody is an anti-PD- 1 antibody.

[0091] Embodiment 29: The method of embodiment 28, wherein the anti-PD-1 antibody is Pembrolizumab, Nivolumab, Dostarlimab, Retifanlimab, Spartalizumab, Camrelizumab, Sintilimab, Cemiplimab, Tislelizumab, penpulimab, zimberelimab, toripalimab, AMP-514 (MEDI0680), Acrixolimab (YBL-006), or a combination thereof.

[0092] Embodiment 30: The method of embodiment 27, wherein the antibody is an anti-PD- L1 antibody.

[0093] Embodiment 31: The method of embodiment 30, wherein the anti-PD-Ll antibody is Atezolizumab, Avelumab, Durvalumab, Envafolimab (KN035), Cosibelimab (CK-301), or a combination thereof.

[0094] Embodiment 32: The method of any one of the preceding embodiments, wherein theICI is a CTLA-4 inhibitor.

[0095] Embodiment 33: The method of embodiment 32, wherein the CTLA-4 inhibitor is an antibody.

[0096] Embodiment 34: The method of embodiment 33, wherein the antibody is Ipilimumab, Tremelimumab, Quavonlimab, Botensilimab, Zalifrelimab, Gotistobart, XTX101, HCAb 4003-2, or a combination thereof.

[0097] Embodiment 35: The method of any one of the preceding embodiments, wherein theICI is a Lag-3 inhibitor.

[0098] Embodiment 36: The method of embodiment 35, wherein the Lag-3 inhibitor is an antibody.

[0099] Embodiment 37: The method of embodiment 36, wherein the antibody is Relatlimab, Leramilimab, Favezelimab, Encelimab (TSR-033), Fianlimab, Sym022, INCAGN02385, BI754111, LBL-007, HLX26, or a combination thereof.

[0100] Embodiment 38: The method of any one of the preceding embodiments, wherein theICI is a TIM-3 inhibitor.WSGR Docket Number: 51527-717.601

[0101] Embodiment 39: The method of embodiment 38, wherein the TIM-3 inhibitor is an antibody.

[0102] Embodiment 40: The method of embodiment 39, wherein the antibody is Sabatolimab (MBG453), MsTOOl, MsT065, MsT229, Cobolimab (TSR-022), Sym023, LY3321367, LY3415244, MBG-A425, MsT286, or a combination thereof.

[0103] Embodiment 41: The method of any one of the preceding embodiments, wherein the ICI is a TIGIT inhibitor.

[0104] Embodiment 42: The method of embodiment 41, wherein the TIGIT inhibitor is an antibody.

[0105] Embodiment 43: The method of embodiment 42, wherein the antibody is Vibostolimab, Etigilimab, Tiragolumab, Domvanalimab, Ociperlimab, Belrestotug (EOS-448), BMS-986207, ASP8374, COM902, Tamgiblimab (IBI939), or a combination thereof.

[0106] Embodiment 44: The method of any one of the preceding embodiments, wherein the cancer comprises a solid tumor or a liquid tumor.

[0107] Embodiment 45: The method of any one of the preceding embodiments, wherein the cancer is characterized by a blood sample taken from the individual and having an increased percentage of B-reg cells relative to a healthy individual blood.

[0108] Embodiment 46: The method of any one of the preceding embodiments, wherein the individual is characterized by (i) a percentage of B regulatory (B-reg) cells in a blood sample being greater than 1.0% of the percent total B cells in the blood sample and / or (ii) B-reg cells being present a tumor sample, optionally wherein the B-reg cells are present among total CD45+ cells taken from the tumor sample.

[0109] Embodiment 47: The method of any one of the preceding embodiments, wherein the cancer comprises lung cancer, colorectal cancer, head and neck carcinoma, or pancreatic cancer.

[0110] Embodiment 48: The method of any one of the preceding embodiments, wherein the cancer is a non-small cell lung cancer, a colorectal adenocarcinoma, a head and neck squamous cell carcinoma, or a pancreatic adenocarcinoma.

[0111] Embodiment 49: The method of any one of the preceding embodiments, wherein treating comprises reducing tumor volume as compared to treatment with the ICI alone and / or reducing the rate of tumor growth as compared to treatment with the ICI alone.WSGR Docket Number: 51527-717.601

[0112] Embodiment 50: The method of any one of embodiments 1-48, wherein the inhibitor of B regulatory (B-reg) cells is administered concurrently with the immune checkpoint inhibitor (ICI).

[0113] Embodiment 51: The method of any one of embodiments 1-48, wherein the inhibitor of B regulatory (B-reg) cells and the immune checkpoint inhibitor (ICI) are administered separately.

[0114] Embodiment 52: The method of any one of embodiments 1-48, wherein the inhibitor of B regulatory (B-reg) cells and the immune checkpoint inhibitor (ICI) are administered separately according to different treatments schedules.

[0115] Embodiment 53: The method of any one of the preceding embodiments, wherein the individual is currently receiving or has previously received an ICI therapy.

[0116] Embodiment 54: The method of any one of the preceding embodiments, wherein the cancer is resistant to ICI therapy.

[0117] Embodiment 55: The method of any one of the preceding embodiments, wherein the cancer is relapsed or refractory to ICI therapy.

[0118] Embodiment 56: The method of any one of the preceding embodiments, wherein the cancer is a progressive cancer.Definitions

[0119] The term "immunosuppression" or "immunodepression" or "negative immune modulation", or "regulatory" in reference to particular cell populations as used herein, refers to processes or cells that are responsible for the reduction or suppression of the immune system function. Immunosuppression generally denotes a state when immune system function is reduced or absent with respect to one or functions such as cellular immunity, antibodybased immunity, or innate immune function. In certain instances, immunosuppression generally denotes a state when immune system function against a tumor or within, surrounding, or adjacent to the tumor microenvironment is reduced or absent. The whole immune response may be depressed, the immune response within a local or specific region may be reduced, or a particular population of immunologically active lymphocytes may be selectively affected. Antigen-specific immunosuppression may be the result of deletion or suppression of a particular population of antigen-specific cells, or the result of enhanced regulation of the immune response by antigen-specific suppressor cells. References toWSGR Docket Number: 51527-717.601 immunosuppressive B cells refer to B cells or B-cell populations that exert negative modulation on the immune response and can be identified by specific surface markers associated with such populations, such as CD38. In certain instances, immunosuppression can be identified by the presence or release of IL-10, IL-35, TGF-beta, or a combination thereof. In certain instances, immunosuppression can be identified by the presence or release by B cells of IL-10, IL-35, TGF- beta, or a combination thereof.

[0120] The term "CD19" or "Cluster of Differentiation 19" (also known as B4, T-cell surface antigen Leu-12, and CVID3) refers to a B-cell lineage surface biomarker or transmembrane protein that in humans is encoded by the gene CD19. CD19 can function as coreceptor for the B-cell antigen receptor complex (BCR) on B-lymphocytes, which decreases the threshold for activation of downstream signaling pathways and for triggering B cell responses to antigens. Structurally, a CD19 amino acid sequence has at least about 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% sequence identity with the amino acid sequence, e.g., of GenBank accession no. NM_001178098.2 -^NP_001171569.1 or NM_001770.6 -> NP_001761.3 over a sequence length of at least 50, 100, 150, 200, 250, 300, 350, 400, 450, 500 amino acids or over the full length of the polypeptide. Structurally, a CD19 nucleic acid sequence has at least about 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% sequence identity with the nucleic acid sequence, e.g., of GenBank accession no. NG_007275.1 or NCBI Gene ID 930, over a sequence length of at least 300, 500, 750, 1000, 1250, 1500 nucleic acids or over the full length of the polynucleotide. The sequence alignments can be performed using any alignment algorithm known in the art, e.g., BLAST, ALIGN, set to default settings.

[0121] The term "CD38" or "Cluster of Differentiation 38" (also known as ADPRC1) refers to a B-cell surface biomarker or transmembrane protein that in humans is encoded by the gene CD38. CD38 can function in B-cell signaling that leads to cellular activation and proliferation. Structurally, a CD38 amino acid sequence has at least about 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% sequence identity with the amino acid sequence, e.g., of GenBank accession no. NM_001775.4 -> NP_001766.2 over a sequence length of at least 50, 100, 150, 200, 250, amino acids or over the full length of the polypeptide. There is a second isoform of CD38 with a premature stop codon that may be expressed at low levels in some cells. Structurally, a CD19 nucleic acid sequence has at least about 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% sequence identity with the nucleic acid sequence, e.g., of GenBank accession no. NC_000004.12 or NCBI Gene ID 952, over a sequence length of at leastWSGR Docket Number: 51527-717.601300, 500, 750 nucleic acids or over the full length of the polynucleotide. The sequence alignments can be performed using any alignment algorithm known in the art, e.g., BLAST, ALIGN, set to default settings.

[0122] The term "CD20" or "Cluster of Differentiation 20" (also known as B-lymphocyte surface antigen Bl) refers to a B-cell lineage surface biomarker or transmembrane protein that in humans is encoded by the gene CD20. Structurally, a CD20 amino acid sequence has at least about 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% sequence identity with the amino acid sequence, e.g., of Uniprot entry P11836 over a sequence length of at least 50, 100, 150, 200, 250, amino acids or over the full length of the polypeptide.

[0123] A "target" as referred to herein refers to the portion of a molecule that participates with a binding moiety of a molecule, peptide, polypeptide, antibody, or antibody fragment. A target can comprise an amino acid sequence and / or a carbohydrate, lipid or other chemical entity. An "antigen" is a target comprising a portion that is able to be bound by an adaptive immune molecule such as an antibody or antibody fragment, B-cell receptor, or T-cell receptor.

[0124] "ADCC" or "antibody dependent cell-mediated cytotoxicity" as used herein, refers to the cell-mediated reaction wherein nonspecific cytotoxic cells that express FcyRs recognize bound antibody on a target cell and subsequently cause lysis of the target cell. ADCC can be correlated with binding to FcyRllla wherein increased binding to FcyRllla leads to an increase in ADCC activity. "ADCP" or antibody dependent cell-mediated phagocytosis, as used herein, can refer to the cell-mediated reaction wherein nonspecific cytotoxic cells that express FcyRs recognize bound antibody on a target cell and subsequently cause phagocytosis of the target cell.

[0125] Multispecific and bispecific antibodies can be produced in small or large quantities using standard methods. Such methods comprise incubating a cell or cell-line comprising a nucleic acid encoding the antibody in a cell culture medium under conditions sufficient to allow for expression and secretion of the antibody, and further harvesting the antibody from the cell culture medium. The harvesting can further comprise one or more purification steps to remove live cells, cellular debris, non-antibody proteins or polypeptides, undesired salts, buffers, and medium components. In certain embodiments, the additional purification step(s) include centrifugation, ultracentrifugation, protein A, protein G, protein A / G, or protein L purification, and / or ion exchange chromatography.WSGR Docket Number: 51527-717.601

[0126] A bispecific antibody generally refers to and includes antibody formats that possesses the ability to specifically bind to at least two structurally distinct targets. The specific binding can be the result of two distinct binding moieties that are structurally distinct at the molecular level, including but not limited to distinct non-identical amino acid sequences; or a single binding moiety that is able to specifically bind to two structurally distinct targets with high affinity (e.g., with a KD less than about lxlOA-6). An antibody, or antibody fragment referred to as "multispecific" refers to a molecule that possesses the ability to specifically bind to at least two or more structurally distinct targets. A "bispecific antibody" including grammatical equivalents refers to a bispecific molecule that preserves at least one fragment of an antibody able to specifically bind a target, for example, a variable region, heavy or light chain, or one or more complementarity determining regions from an antibody molecule. A "multispecific antibody" including grammatical equivalents refers to a multispecific molecule that preserves at least one fragment of an antibody able to specifically bind with a target, for example, a variable region, heavy or light chain, or complementarity determining region from an antibody molecule. Many methods can be deployed to facilitate proper bispecific formation.

[0127] Knob-in-Hole as described in US 5,731,116; US 7,476,724 and Ridgway, J. et al. (1996) Prot. Engineering 9(7): 617-621, broadly involves: (1) mutating the CH3 domain of one or both antibodies to promote heterodimerization; and (2) combining the mutated antibodies under conditions that promote heterodimerization. "Knobs" or "protuberances" are typically created by replacing a small amino acid in a parental antibody with a larger amino acid (e.g., T366Y or T366W); "Holes" or "cavities" are created by replacing a larger residue in a parental antibody with a smaller amino acid (e.g., Y407T, T366S, L368A and / or Y407V).

[0128] For multispecific antibodies including an Fc domain, introduction of specific mutations into the constant region of the heavy chains to promote the correct heterodimerization of the Fc portion can be utilized. Several such techniques are reviewed in Klein et al. (mAbs (2012) 4:6, 1-11), the contents of which are incorporated herein by reference in their entirety. These techniques include the "knobs-into-holes" (Ki H ) approach which involves the introduction of a bulky residue into one of the CH3 domains of one of the antibody heavy chains. This bulky residue fits into a complementary "hole" in the other CH3 domain of the paired heavy chain so as to promote correct pairing of heavy chains (see e.g., US7642228).

[0129] Exemplary KiH mutations include S354C, T366W in the "knob" heavy chain and Y349C, T366S, L368A, Y407V in the "hole" heavy chain.WSGR Docket Number: 51527-717.601

[0130] Other Fc mutations are provided by Igawa and Tsunoda who identified 3 negatively charged residues in the CH3 domain of one chain that pair with three positively charged residues in the CH3 domain of the other chain. These specific charged residue pairs are : E356- K439, E357-K370, D399-K409 and vice versa. By introducing at least two of the following three mutations in chain A: E356K, E357K and D399K, as well as K370E, K409D, K439E in chain B, alone or in combination with newly identified disulfide bridges, they were able to favor very efficient heterodimerization while suppressing homodimerization at the same time (Martens T et al. A novel one-armed antic- Met antibody inhibits glioblastoma growth in vivo. Clin Cancer Res 2006; 12:6144-52; PMID:17062691). Previous studies defined 41 variant pairs based on combining structural calculations and sequence information that were subsequently screened for maximal heterodimerization, defining the combination of S364H, F405A (HA) on chain A and Y349T, T394F on chain B (TF) (Moore GL et al. A novel bispecific antibody format enables simultaneous bivalent and monovalent co-engagement of distinct target antigens. MAbs 2011; 3:546-57; PMID: 22123055).

[0131] Asymmetric bispecific antibodies generally comprise a heavy chain / light chain (HC / LC) pair from an antibody specific for target A and an HC / LC pair from an antibody specific for target B, creating a hetero-bifunctional antibody. Hetero-bifunctional antibodies such as these face the problem of unproductive formation of the molecule when it is being produced. HC / LC-A: HC / LC-B is desired, but is usually thermodynamically or statistically unfavorable from all the possible combinations possible. Multiple schemes have been introduced to circumvent this problem. In some instances, the HC / LC pair from an antibody with specificity for A and the HC / LC pair from an antibody with specificity for B further comprise mutations to the FC region to increase the probability of formation of an antibody with HC / LC-A: HC / LC-B. This can be achieved by engineering structural features such as "knobs" into the FC region for HC-A, and "holes" into HC-B, or vice versa, that promote formation of heterodimers between HC-A and HC-B. Another scheme to promote HC-A: HC-B heterodimers is to engineer amino acid residues in the FC portion of HC-A and HC-B to comprise charge pairs that favor electrostatic interactions between HC-B and HC-A. Another scheme to address the problem of chain association is to replace the variable regions of one of the HC / LC pairs with a single-chain binding molecule (e.g., VHH or an scFv). Such that one-half of the molecule comprises a classical HC / LC pair and the other comprises a HC constant region fused or otherwise connected to the single-chain binding molecule. Further modifications can be made to promoteWSGR Docket Number: 51527-717.601 proper HC / LC paring and include engineering mutations to the HC and LC for either A or B to favor formation of the proper HC / LC pair; CrossMab technology, which entails swapping the corresponding constant regions of the HC / LC pair. Symmetric bispecific antibodies circumvent the chain association problem by not relying on formation of a hetero-bifunctional molecule. Such examples include: the dual-variable domain molecule, which comprises stacked variable regions of differing specificity; the IgG-scFv molecule, which comprises an scFv of a differing specificity fused to the c-terminus of heavy chain of a classical antibody molecule; the (scFV)4- FC, which comprises two scFvs connected by an Fc region of an Ig (the Fes dimerize creating a bispecific, tetravalent molecule); the DART-Fc and the two-in-one, amongst others.

[0132] The terms "polypeptide" and "protein" are used interchangeably and refers to a polymer of amino acid residues, and are not limited to a minimum length. Polypeptides, including the provided antibodies and antibody chains and other peptides, e.g., linkers and binding peptides, can include amino acid residues including natural and / or non-natural amino acid residues. The terms also include post-expression modifications of the polypeptide, for example, glycosylation, sia lylation, acetylation, phosphorylation, and the like. In some aspects, the polypeptides can contain modifications with respect to a native or natural sequence, as long as the protein maintains the desired activity. These modifications can be deliberate, as through site-directed mutagenesis, or can be accidental, such as through mutations of hosts which produce the proteins or errors due to PCR amplification.

[0133] Linkers can be used to join heavy and light chain variable domains, antibodies or antigen binding fragments of antibodies to form multispecific antibodies. A "linker" herein is also referred to as "linker sequence" "spacer" "tethering sequence" or grammatical equivalents thereof. A "linker" as referred herein connects two distinct molecules that by themselves possess target binding, catalytic activity, or are naturally expressed and assembled as separate polypeptides. For example, two distinct binding moieties or a heavy-chain / light- chain pair. A number of strategies may be used to covalently link molecules together. These include but are not limited to polypeptide linkages between N- and C-termini of proteins or protein domains, linkage via disulfide bonds, and linkage via chemical cross-linking reagents. In one aspect of this embodiment, the linker is a peptide bond, generated by recombinant techniques or peptide synthesis. The linker peptide may predominantly include the following amino acid residues: Gly, Ser, Ala, or Thr. The linker peptide should have a length that is adequate to link two molecules in such a way that they assume the correct conformationWSGR Docket Number: 51527-717.601 relative to one another so that they retain the desired activity. In one embodiment, the linker is from about 1 to 50 amino acids in length or about 1 to 30 amino acids in length. In one embodiment, linkers of 1 to 20 amino acids in length may be used. Useful linkers include glycine-serine polymers, including for example (GS)n, (GSGGS)n, (GGGGS)n, and (GGGS)n, where n is an integer of at least one, glycine-alanine polymers, alanine-serine polymers, and other flexible linkers. Exemplary, linkers for linking antibody fragments or single chain variable fragments can include AAEPKSS, AAEPKSSDKTHTCPPCP (SEQ ID NO: 19), GGGG (SEQ ID NO: 20), or GGGGDKTHTCPPCP (SEQ ID NO: 21). Alternatively, a variety of non-proteinaceous polymers, including but not limited to polyethylene glycol (PEG), polypropylene glycol, polyoxyalkylenes, or copolymers of polyethylene glycol and polypropylene glycol, may find use as linkers.

[0134] "Fragment-based" bispecific antibodies or bispecific antibodies comprising a "single chain variable fragment" or "scFv" of this disclosure can refer to a single chain antibody, or fragment thereof, that comprises two binding moieties and a linker connecting the two binding moieties. The linker may be a polypeptide linker or other linker of suitable flexibility so as not to inhibit binding of either targeting moiety. Fragment based bispecific antibody formats include tandem VHH antibodies, tandem scFvs, scFv-Fabs, F(ab)2, dual-affinity retargeting antibodies (DARTs). Such fragment-based antibodies can be further manipulated to comprise additional binding moieties with specificity for a given target e.g., A2:BI, AI:B2 or A2:B2, or with fragments of an Fc region to improve pharmacokinetics or promote ADCC, ADCP, or CDC.

[0135] A "binding moiety" refers to a portion of a molecule, peptide, polypeptide, antibody, or antibody fragment that mediates specific binding to a recited target or antigen or epitope. By way of example, the binding moiety of an antibody may comprise a heavy- chain / light-chain variable region pair or one or more complementarity determining regions (CDRs).

[0136] A "target" as referred to herein refers to the portion of a molecule that participates with a binding moiety of a molecule, peptide, polypeptide, antibody, or antibody fragment. A target can comprise an amino acid sequence and / or a carbohydrate, lipid or other chemical entity. An "antigen" is a target comprising a portion that is able to be bound by an adaptive immune molecule such as an antibody or antibody fragment, B-cell receptor, or T-cell receptor.

[0137] In some embodiments, the bispecific antibodies provided herein have a dissociation constant (KD) of about 10 pM, 1 pM, 100 nM, 50 nM, 40 nM, 30 nM, 20 nM, 10 nM, 5 nM, 2 nM, 1 nM, 0.5 nM, 0.1 nM, 0.05 nM, 0.01 nM, or 0.001 nM or less (e.g., 10“8M or less, e.g.,WSGR Docket Number: 51527-717.601 from 10“8M to 10“13M, e.g., from 10“9M to 10“13M) for the antibody target. The antibody target can be a CD19 target, a CD38 target, or a target comprising both CD19 and CD38. KDcan be measured by any suitable assay. In certain embodiments, KD can be measured using surface plasmon resonance assays (e.g., using a BIACORE®-2000 or a BIACORE®-3000 or Octet).

[0138] A "humanized" antibody is an antibody in which all or substantially all CDR amino acid residues are derived from non-human CDRs and all or substantially all FR amino acid residues are derived from human FRs. A humanized antibody optionally can include at least a portion of an antibody constant region derived from a human antibody. A "humanized form" of a non-human antibody refers to a variant of the non-human antibody that has undergone humanization, typically to reduce immunogenicity to humans, while retaining the specificity and affinity of the parental non-human antibody. In some embodiments, some FR residues in a humanized antibody are substituted with corresponding residues from a non-human antibody (e.g., the antibody from which the CDR residues are derived), e.g., to restore or improve antibody specificity or affinity.

[0139] Among the provided antibodies are human antibodies. A "human antibody" is an antibody with an amino acid sequence corresponding to that of an antibody produced by a human or a human cell, or non-human source that utilizes human antibody repertoires or other human antibody-encoding sequences, including human antibody libraries. The term excludes humanized forms of non-human antibodies comprising non-human antigen-binding regions, such as those in which all or substantially all CDRs are non-human. Human antibodies may be prepared by administering an immunogen to a transgenic animal that has been modified to produce intact human antibodies or intact antibodies with human variable regions in response to antigenic challenge. Such animals typically contain all or a portion of the human immunoglobulin loci, which replace the endogenous immunoglobulin loci, or which are present extrachromosomally or integrated randomly into the animal's chromosomes. In such transgenic animals, the endogenous immunoglobulin loci have generally been inactivated. Human antibodies also may be derived from human antibody libraries, including phage display and cell-free libraries, containing antibody-encoding sequences derived from a human repertoire.

[0140] "ADCC" or "antibody dependent cell-mediated cytotoxicity" as used herein, refers to the cell-mediated reaction wherein nonspecific cytotoxic cells that express FcyRs recognize bound antibody on a target cell and subsequently cause lysis of the target cell. ADCC can beWSGR Docket Number: 51527-717.601 correlated with binding to FcyRllla wherein increased binding to FcyRllla leads to an increase in ADCC activity. "ADCP" or antibody dependent cell-mediated phagocytosis, as used herein, can refer to the cell-mediated reaction wherein nonspecific cytotoxic cells that express FcyRs recognize bound antibody on a target cell and subsequently cause phagocytosis of the target cell.

[0141] The terms "polypeptide" and "protein" are used interchangeably and refers to a polymer of amino acid residues, and are not limited to a minimum length. Polypeptides, including the provided antibodies and antibody chains and other peptides, e.g., linkers and binding peptides, can include amino acid residues including natural and / or non-natural amino acid residues. The terms also include post-expression modifications of the polypeptide, for example, glycosylation, sia lylation, acetylation, phosphorylation, and the like. In some aspects, the polypeptides can contain modifications with respect to a native or natural sequence, as long as the protein maintains the desired activity. These modifications can be deliberate, as through site-directed mutagenesis, or can be accidental, such as through mutations of hosts which produce the proteins or errors due to PCR amplification.

[0142] As described herein, the term "percent (%) sequence identity," and terms related thereto, in the context of amino acid sequences or nucleic acid sequences, is the percentage of amino acid residues or nucleic acid residues in a candidate sequence that are identical with the amino acid residues or nucleic acid residues, respectively, in a selected sequence, after aligning the 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 or percent nucleic acid identity can be achieved in various ways that are within the skill in the art, for instance, using publicly available computer software such as Clustal Omega, BLAST, BLAST-2, ALIGN, ALIGN-2 or Megalign (DNASTAR) software, with BLAST being the alignment algorithm of preference. Those skilled in the art can determine appropriate parameters for measuring alignment, including any algorithms needed to achieve maximal alignment over the full-length of the sequences being compared, although for simplicity it maybe preferred to use default parameters.

[0143] As used herein, the term "individual" is synonymous with patient and / or subject and includes and / or refers to a human and may be a human that has been diagnosed as needing to treat a disease or condition as disclosed herein. However, examples are not limitedWSGR Docket Number: 51527-717.601 to humans and include, chimpanzees, marmosets, cows, horses, sheep, goats, pigs, rabbits, dogs, cats, rats, mice, guinea pigs, and the like. The term individual includes vertebrates. The individual is typically a human and may be a human that has been diagnosed as needing to treat a disease or condition as disclosed herein.

[0144] As used herein, treating or treatment of includes and / or refers to ameliorating the disease or disorder or symptoms thereof (e.g., slowing or arresting or reducing the development of the disease or at least one of the clinical symptoms thereof). In certain embodiments, treating or treatment also includes and / or refers to alleviating or ameliorating at least one physical and / or biological parameters including those which may not be discernible by the patient. In certain embodiments, treating or treatment includes and / or refers to modulating a disease, disorder, or biological process either physically, (e.g., stabilization of a discernible symptom), physiologically, (e.g., stabilization of a physical and / or biological parameter), or both. In certain embodiments, treating or treatment includes and / or refers to preventing or delaying the onset or development or progression of the disease or disorder. In certain embodiments, treating or treatment includes and / or refers to preventing or delaying or inhibiting the deterioration of (i) a healthy physiological state or (ii) a baseline physiological state (e.g., the progression of a disease or disorder).

[0145] A "therapeutically effective amount," "effective dose," "effective amount," or "therapeutically effective dosage" of a drug or therapeutic agent is any amount of the drug that, when used alone or in combination with another therapeutic agent, protects a su bject against the onset of a disease or promotes disease regression evidenced by a decrease in severity of disease symptoms, an increase in frequency and duration of disease symptom-free periods, or a prevention of impairment or disability due to the disease affliction. The ability of a therapeutic agent to promote disease regression can be evaluated using a variety of methods known to the skilled practitioner, such as in human subjects during clinical trials, in animal model systems predictive of efficacy in humans, or by assaying the activity of the agent in in vitro assays.

[0146] As used herein, "pharmaceutically acceptable" with reference to a carrier" "excipient" or "diluent" includes any and all solvents, dispersion media, coatings, antibacterial and antifungal agents, isotonic and absorption delaying agents, and the like that are physiologically compatible. In some aspects, the carrier is suitable for intravenous, intramuscular, subcutaneous, parenteral, spinal or epidermal administration (e.g., by injectionWSGR Docket Number: 51527-717.601 or infusion). Depending on the route of administration, the active compound, i.e., antibody, can be coated in a material to protect the compound from the action of acids and other natural conditions that can inactivate the compound.

[0147] The pharmaceutical compounds described herein can include one or more pharmaceutically acceptable salts. A "pharmaceutically acceptable salt" refers to a salt that retains the desired biological activity of the parent compound and does not impart any undesired toxicological effects (see e.g., Berge, S.M., et al. (1977) J. Pharm. Sci. 66: 1-19). Examples of such salts include acid addition salts and base addition salts. Acid addition salts include those derived from nontoxic inorganic acids, such as hydrochloric, nitric, phosphoric, sulfuric, hydrobromic, hydroiodic, phosphorous and the like, as well as from nontoxic organic acids such as aliphatic mono- and dicarboxylic acids, phenyl- substituted alkanoic acids, hydroxy alkanoic acids, aromatic acids, aliphatic and aromatic sulfonic acids and the like. Base addition salts include those derived from alkaline earth metals, such as sodium, potassium, magnesium, calcium and the like, as well as from nontoxic organic amines, such as N,N'- dibenzylethylenediamine, N-methylglucamine, chloroprocaine, choline, diethanolamine, ethylenediamine, procaine and the like.

[0148] As used herein, in any instance or embodiment described herein, "comprising" may be replaced with "consisting essentially of' and / or "consisting of," unless context clearly connotes otherwise. Similarly, as used herein, in any instance or embodiment described herein, "comprises" may be replaced with "consists essentially of" and / or "consists of," unless context clearly connotes otherwise.

[0149] As used herein, the term "about," in the context of a given value or range, includes and / or refers to a value or range that is within 10% of the given value or range.

[0150] As used herein, the term "and / or" is to be taken as specific disclosure of each of the two specified features or components with or without the other. For example, "A and / or B" is to be taken as specific disclosure of each of (i) A, (ii) B and (iii) A and B, just as if each were set out individually herein.WSGR Docket Number: 51527-717.601EXAMPLESExample 1: Treatment of in vivo tumor model using anti-CD19 / CD38 bispecific and anti-PD-1 antibodiesAim

[0151] The objective of this study was to determine the in vivo anti-tumor activity of MBS 1938-1 (an anti-mouseCD19 and -mouseCD38 bsAb), Anti-PD-1 RMP1-14, and Mouse lgG2a as monotherapy or combination in a syngeneic colorectal cancer model, CT26 in immunocompetent mice.Study design

[0152] Mouse lgG2a (synonym: InVivoMAb mouse lgG2a isotype control; Cl.18.4; 9.72 mg / mL) and Anti-PD-1 (synonym: InVivo Anti-mouse PD-1; RMP1-14; 9.69 mg / mL) were obtained from Bio-X-cell as stock solutions and stored at 2-8°C in the dark. MBS1938-1 (7.200 mL; 2.0 mg / mL) was provided by Biograph 55 as a stock solution and stored at -80°C in the dark.

[0153] The Mouse lgG2a dosing solution of 1.0 mg / mL was freshly formulated by diluting 0.741 mL of Mouse lgG2a stock solution (9.72 mg / mL) to 6.459 mL of IX PBS in an Eppendorf / dosing vial and mixed by using gentle hand agitation to form a clear solution. The dosing solution was stored at 2-8°C until administration.

[0154] The Anti-PD-1 RMP1-14 dosing solution of 1.0 mg / mL was freshly formulated by diluting 1.486 mL of Anti-PD-1 RMP1-14 stock solution (9.69 mg / mL) to 12.914 mL of IX PBS in an Eppendorf / dosing vial and mixed by using gentle hand agitation to form a clear solution. The dosing solution was stored at 2-8°C until administration.

[0155] The MBS1938-1 dosing solution of 1.0 mg / mL was freshly prepared by thawing 1 aliquot of MBS1938-1 stock solution (7.200 mL; 2.0 mg / mL) from -80°C to room temperature. Then, 7.200 mL of IX PBS was added and mixed using gentle hand agitation to form a clear solution. The dosing solution was stored at 2-8°C until administration.

[0156] Pre-study animals (female, Balb / c) were unilaterally (left flank) and subcutaneously implanted with 300,000 CT26 cells (colorectal tumor type) resuspended in 100 pL of PBS. Prestudy tumor volumes are recorded for each experiment beginning four to five days after injection. Tumor growth was monitored thrice a week using digital calipers, and the tumor volume (TV) was calculated using the formula (0.52 x [length x width2]). When the TV reachedWSGR Docket Number: 51527-717.601 approximately 50-150 mm3, animals were matched by tumor size and assigned into control or treatment groups (n = 20 / group). Champions made efforts to randomize 100 tumor-bearing mice for Groups 1-5 at a mean tumor volume falling within the range of 50-120 mm3with a target of ~80 mm3. Dosing was initiated on Day 0. Tumor size and body weight were measured thrice weekly, and the study endpoint was when all the mice in the single-arm treatment group (MBS1938-1) reached 2000 mm3or Day 30 post-randomization. The study was completed on Day 32. The design of the efficacy study is summarized in Table 1.Table 1

[0157] Effects on tumor growth were evaluated by measuring percent tumor growth inhibition (TGI) and the number of complete responder (CR), partial responder (PR), and tumor- free survivors (TFS). Tolerability was assessed by body weight loss, lethality, and clinical signs of adverse treatment-related side effects. Tumor volumes and body weights were measured three times per week.

[0158] Inhibition of tumor growth was determined by calculating the percent TGI (100% x [l-(fi na I MTV - initial MTV of a treated group) / (final MTV - initial MTV of the control group)]). Treatment started on Day 0. Tumor volumes of treatment groups for the duration of the study and at the completion of the study were compared to that of the control group.

[0159] Mean tumor volume growth rate was calculated by the sponsor using the ratebased T / C. The rate-based T / C was determined by calculating 10 (pT- pC) x30 days. It was based on the ratio of the fitted growth rates of treated versus control groups, normalized to a study length of 30 days. Here, pT is the mean of growth rates for the treatment group, and pC is the mean of the growth rates for the control group. The rate-based T / C uses a fixed time (Day 30) and is less dependent on the choice of the final treatment day. A time of 30 days was chosen to be consistent with the studyWSGR Docket Number: 51527-717.601Outcome: anti-tumor efficacy

[0160] In the efficacy study with syngeneic colorectal tumor model CT26, treatment with the combination of Anti-PD-1 RMP1-14 at 10 mg / kg IP / BIWx4 + MBS 1938-1 at 10 mg / kg IP / BIWx4 (Group 5) had a significant anti-tumor activity with 89% TGI compared to the untreated control group (FIG. 1A). Intraperitoneal treatment with Mouse lgG2a at 10 mg / kg BIWx4 (Group 2) had no significant effect on anti-tumor activity with 2% TGI compared to the untreated control group (Group 1). Treatment with Anti-PD-1 RMP1-14 at 10 mg / kg IP / BIWx4 (Group 3) and MBS 1938-1 at 10 mg / kg IP / BIWx4 (Group 4) decreased the tumor volume and had a non-significant anti-tumor activity trend with 43% TGI and 47% TGI compared to the untreated control group.

[0161] The anti-tumor activity of the Anti-PD-1 RMP1-14 10 mg / kg + MBS 1938-1 10 mg / kg combination group (Group 5) was significantly greater than the Mouse lgG2a 10 mg / kg group (Group 2). There were 6 tumor-free survivors (TFSs) in Anti-PD-1 RMP1-14 10 mg / kg group (Group 3), 1 partial responder (PR), 1 complete responder (CR), and 4 TFS in MBS 1938-1 10 mg / kg group (Group 4), 1 PR, and 6 TFS in Anti-PD-1 RMP1-14 10 mg / kg + MBS 1938-1 10 mg / kg combination group (Group 5) and no PRs, CR, or TFSs in any other group.Outcome: survival analysis

[0162] Treatment with the combination of Anti-PD-1 RMP1-14 at 10 mg / kg IP / BIWx4 + MBS 1938-1 at 10 mg / kg IP / BIWx4 (Group 5) resulted in improved survival (FIG. IB). FIG. IB shows survival analysis at the time to the study endpoint of 2000 mm3for the Mouse lgG2a 10 mg / kg group (Group 2), Anti-PD-1 RMP1-14 10 mg / kg group (Group 3), MBS 1938-1 10 mg / kg group (Group 4) as single agents, and the combination of Anti-PD-1 RMP1-14 10 mg / kg + MBS 1938-1 10 mg / kg combination group (Group 5) (as compared to the untreated control (Group 1)). The improved survival resulting from the combination treatment with Anti-PD-1 and anti- CD19 / CD38 bispecific antibody is also shown in FIGs. 1D-1F.Outcome: tumor rate of growth reduction

[0163] MBS1938-1 Alone and in Combination Induces a Dramatic Reduction in MeanTumor Volume (MTV) Growth Rate after Study Day 20 (FIG. 1C). FIG. 1C shows mean tumor volume growth rate for the Mouse lgG2a 10 mg / kg group (Group 2), Anti-PD-1 RMP1-14 10 mg / kg group (Group 3), MBS 1938-1 10 mg / kg group (Group 4) as single agents, and the combination of Anti-PD-1 RMP1-14 10 mg / kg + MBS 1938-1 10 mg / kg combination group (Group 5) (as compared to the untreated control (Group 1)).WSGR Docket Number: 51527-717.601Summary

[0164] Collectively, these results demonstrate an unexpected synergistic effect of the combination treatment using a combination of anti-CD19 / CD38 bsAb and anti-PD-1 Ab as compared to either treatment alone or negative controls.Example 2: Treatment of PBMCs using anti-CD19 / CD38 bispecific antibody

[0165] The effect of anti-CD19 / CD38 bsAb (BG55-001, anti-hCD19 / hCD38 common light chain bispecific comprising SEQ ID NOs: 1-3) on the survival of non-target immune cells in healthy donor and cancer patient PBMCs was measured. Cryopreserved donor PBMCs were thawed and treated with antibody treatments, anti-CD19 / CD38 bsAb, Tafasitamab (anti-CD19), Alemtuzumab (anti-CD52), and hlgGl Isotype negative control. Cells were treated with 150 or 100 pg / mL for healthy donor and cancer donor, respectively. Cells were treated for 24 hours followed by flow cytometry analysis to determine absolute counts of different immune cell populations in triplicate.

[0166] Donor-derived B cells were isolated and differentiated to B-reg cells by coculturing with feeder cells and cytokines. Next, B-reg cells were fluorescently labeled with VF405 and then added to PBMC cultures at a 1:4 ratio (B-reg: PBMC) and treated with antibodies or vehicle for 24 hours in triplicate. Flow cytometry analysis was performed to determine absolute counts of labeled B-reg cells.

[0167] FIG. 2A shows a bar graph of the absolute cell counts of CD3+ / CD38+, CD20+ / CD38+, CD56+ / CD38+, CDllb / c+ / CD38+ immune cells normalized to baseline untreated cells. For all cell types, anti-CD19 / CD38 bsAb resulted in higher absolute cell counts as compared to the hlgGl isotype negative control. The anti-CD19 / CD38 bsAb also showed comparable or greater absolute cell counts compared to Tafasitamab and Alemtuzumab controls. The results show that CD38 negative populations were not affected by anti- CD19 / CD38 bsAb treatment when compared to isotype control.

[0168] FIG. 2B shows a bar graph of the absolute cell counts of CD3+ / CD38+, CD20+ / CD38+, CD56+ / CD38+, CDllb / c+ / CD38+ immune cells normalized to baseline untreated cells. For CD3+ / CD38+, CD20+ / CD38+, and CDllb / c+ / CD38+ cells, anti-CD19 / CD38 bsAb resulted in higher absolute cell counts as compared to the hlgGl isotype negative control. The CD56+ / CD38+ cell population showed a slight decrease in absolute cell counts in the anti- CD19 / CD38 treatment as compared to isotype control. For CD3+ / CD38+, CD20+ / CD38+, andWSGR Docket Number: 51527-717.601CDllb / c+ / CD38+ cells, the anti-CD19 / CD38 bsAb also showed comparable or greater absolute cell counts compared to Tafasitamab and Alemtuzumab controls. The CD56+ / CD38+ cell population showed a slight decrease in absolute cell counts in the anti-CD19 / CD38 treatment as compared to Tafasitamab and Alemtuzumab controls. The results show that CD38 negative populations were not affected by anti-CD19 / CD38 bsAb treatment when compared to isotype control.

[0169] FIGs. 3A-C show a bar graph of the absolute cell count of live VF405+ B-reg cells. The cells were treated with anti-CD19 / CD38 bsAb, hlgGl isotype negative control, or vehicle. The results show depletion of B-reg cells incubated with cancer patient allogenic PBMCs by anti-CD19 / CD38 bsAb treatment as compared to the controls. The results demonstrate the effect of the anti-CD19 / CD38 bsAb in depleting B-reg cells while not affecting other immune cells.Example 3: Treatment of cancer using anti-CD19 / CD38 bispecific antibody

[0170] The effect of anti-CD19 / CD38 bsAb BG55-001, anti-hCD19 / hCD38 common light chain bispecific comprising SEQ ID NOs: 1-3) on CD4+ T-cell proliferation was measured in the blood of patients with the cancer types: NSCLC (non-small cell lung cancer), CRC (colorectal adenocarcinoma), HNSCC (head and neck squamous cell carcinoma), and PAC (pancreatic adenocarcinoma). Blood was taken from cancer patients with a N=20 for each of the 4 cancer types. Cells were treated with either anti-CD19 / CD38 bsAb or isotype negative control in triplicate. CD4+ T-cells were measured after treatment with antibody.

[0171] FIG. 4 shows a bar graph of the percentage increase in CD4+ T-cells above activated T-cells only. The graph is divided into two sections. The left half represents cancers with >1.5% B-reg cells, considered pathologic. The right half shows cancers with <1% B-reg cells, which are within physiologic levels comparable to healthy individuals. Cancers having increased / elevated in B-reg cells (e.g., relative to a healthy donor and / or >1.5% B-reg cells present in a blood sample) responded strongly to the treatment with anti-CD19 / CD38 as indicated in increased CD4 T cells. The %CD4+ T-cell increase above activated T-cells only was significant and greater than isotype negative control. Additionally, the cancers in which are known to have <1% B-reg cells did not respond to the treatment with anti-CD19 / CD38 as expected. This demonstrates efficacy of the anti-CD19 / CD38 treatment in cancers having >1.5% B-reg cells compared to healthy individual.WSGR Docket Number: 51527-717.601

[0172] FIG. 5 shows a graph of the percentage of B-reg cells in total CD45+ population from tumor samples for individual replicates for the 4 cancer types. The relative prevalence of B-reg cells was measured in n=56 tumor samples. The percentage of B-reg cells in total CD45+ immune cell populations was evaluated using quantitative image analysis of multiplex IHC tissue sections. N=735,445 B-reg cells were analyzed. The results show that B-reg cells made up more than 1% of the total CD45+ immune cell population in n=45 of 56 tumor samples analyzed.

[0173] FIG. 6 shows a bar graph of the B-cell percentage in CD45+ immune cell populations of NSCLC tumors. The relative prevalence of B-reg cells and CD20+ B-cells was measured in n=20 NSCLC tumor samples from n=20 patients. The results show a majority of tumor samples showed elevated levels of B-reg cells in NSCLC.

[0174] While preferred embodiments of the present disclosure have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the instant disclosure. It should be understood that various alternatives to the embodiments described herein may be employed in practicing the invention. It is intended that the following claims define the scope of the embodiments disclosed herein, and that methods and structures within the scope of these claims and their equivalents be covered thereby.WSGR Docket Number: 51527-717.601SEQUENCESWSGR Docket Number: 51527-717.601

Claims

WSGR Docket Number: 51527-717.601CLAIMS1. A method of treating a cancer in an individual in need thereof, the method comprising: administering to the individual:(i) a therapeutically effective amount of an inhibitor of B regulatory (B-reg) cells; and(ii) a therapeutically effective amount of an immune checkpoint inhibitor (ICI).

2. A method of treating a cancer in an individual in need thereof, wherein the cancer comprises a tumor characterized by (i) a blood sample taken from the individual having a percentage of B-reg cells greater than 1% of the percent total CD19 positive B cells or (ii) a biological sample taken from the individual having B-reg cells, the method comprising: administering an inhibitor of B regulatory (B-reg) cells to the individual.

3. A method of treating a cancer in an individual in need thereof, the method comprising:(a) determining the percentage of B-reg cells in:(i) a blood sample taken from the individual, or(ii) a tumor sample taken from the individual, and(b) administering to the individual:(i) a therapeutically effective amount of an inhibitor of B regulatory (B-reg) cells if the percentage of B-reg cells in the blood sample is greater than 1.0% of the percent total B cells in the blood sample, or(ii) a therapeutically effective amount of an inhibitor of B regulatory (B-reg) cells if B-reg cells are present in the tumor sample, optionally wherein the B-reg cells are present among total CD45+ cells taken from the tumor sample.

4. The method of claim 2 or claim 3, wherein the method comprises administering:(i) the inhibitor of B regulatory (B-reg) cells; and(ii) an immune checkpoint inhibitor (ICI).

5. The method of claim 1, wherein the B-reg cells are characterized as CD19+CD38+, optionally wherein the B-reg cells are characterized as CD19+CD38+CD20LOWor CD19+CD38+CD20NEG.WSGR Docket Number: 51527-717.6016. The method of claim 1, wherein the B-reg cells are characterized as CD19+CD38HIGH, optionally wherein the B-reg cells are characterized as CD19+CD38HIGHCD20LOWor CD19+CD38HIGHCD20NEG.

7. The method of claim 1, wherein the ICI is a T-cell ICI .

8. The method of claim 1, wherein the inhibitor of B-reg cells comprises a bispecific antibody or bispecific antibody fragment that binds CD19 and CD38.

9. The method of claim 8, wherein the bispecific antibody or bispecific antibody fragment that binds CD19 and CD38 comprises: an anti-CD38 heavy chain variable domain and an anti-CD38 light chain variable domain; and an anti-CD19 heavy chain variable domain and an anti-CD19 light chain variable domain.

10. The method of claim 9, wherein: the anti-CD38 heavy chain variable domain comprises: a heavy chain complementarity determining domain 1 (CDRH1) comprising an amino acid sequence set forth in SEQ ID NO: 7, a heavy chain complementarity determining domain 2 (CDRH2) comprising an amino acid sequence set forth in SEQ ID NO: 8, 16. 17, or 18, a heavy chain complementarity determining domain 3 (CDRH3) comprising an amino acid sequence set forth in SEQ ID NO: 9, the anti-CD38 light chain variable domain comprises: a light chain complementarity determining domain 1 (CDRL1) comprising an amino acid sequence set forth in SEQ ID NO: 13 a light chain complementarity determining domain 2 (CDRL2) comprising an amino acid sequence set forth in SEQ ID NO: 14, a light chain complementarity determining domain 3 (CDRL3) comprising an amino acid sequence set forth in SEQ ID NO: 15, or a light chain complementarity determining domain 1 (CDRL1) comprising an amino acid sequence set forth in SEQ ID NO: 23 a light chain complementarity determining domain 2 (CDRL2) comprising an amino acid sequence set forth in SEQ ID NO: 24, a light chain complementarity determining domain 3 (CDRL3) comprising an amino acid sequence set forth in SEQ ID NO: 25, the anti-CD19 heavy chain variable domain comprising:WSGR Docket Number: 51527-717.601 a heavy chain complementarity determining domain 1 (CDRH1) comprising an amino acid sequence set forth in SEQ ID NO:10, a heavy chain complementarity determining domain 2 (CDRH2) comprising an amino acid sequence set forth in SEQ ID NO: 11, a heavy chain complementarity determining domain 3 (CDRH3) comprising an amino acid sequence set forth in SEQ ID NO: 12; and the anti-CD19 light chain variable domain comprises: a light chain complementarity determining domain 1 (CDRL1) comprising an amino acid sequence set forth in SEQ ID NO: 13 a light chain complementarity determining domain 2 (CDRL2) comprising an amino acid sequence set forth in SEQ ID NO: 14, a light chain complementarity determining domain 3 (CDRL3) comprising an amino acid sequence set forth in SEQ ID NO: 15, or a light chain complementarity determining domain 1 (CDRL1) comprising an amino acid sequence set forth in SEQ ID NO: 23 a light chain complementarity determining domain 2 (CDRL2) comprising an amino acid sequence set forth in SEQ ID NO: 24, a light chain complementarity determining domain 3 (CDRL3) comprising an amino acid sequence set forth in SEQ ID NO: 25.

11. The method of claim 8, wherein the bispecific antibody or bispecific antibody fragment that binds CD19 and CD38 depletes B-reg cells incubated with cancer patient allogeneic PBMCs.

12. The method of claim 11, wherein the B-reg cells are CD19+CD38+CD20_B-reg cells.

13. The method of claim 8, wherein the bispecific antibody or bispecific antibody fragment that binds CD19 and CD38 preserves non-target immune cells in healthy donor PMBCs and / or cancer patient PBMCs.

14. The method of claim 13, wherein the non-target immune cells comprise CD3+CD38+ immune cells, CD20+CD38+immune cells, CD56+CD38 immune cells, and / or CDllb / c+CD38+immune cells.

15. The method of claim 8, wherein the bispecific antibody or bispecific antibody fragment that binds CD19 and CD38 is a common light chain bispecific antibody.

16. The method of claim 15, wherein the common light chain bispecific antibody comprises: an anti-CD38 heavy chain variable domain comprising: a heavy chain complementarity determining domain 1 (CDRH1) comprising an amino acid sequence set forth in SEQ ID NO: 7, a heavy chain complementarityWSGR Docket Number: 51527-717.601 determining domain 2 (CDRH2) comprising an amino acid sequence set forth in SEQ ID NO: 8, 16. 17, or 18, a heavy chain complementarity determining domain 3 (CDRH3) comprising an amino acid sequence set forth in SEQ ID NO: 9, an anti-CD19 heavy chain variable comprising: a heavy chain complementarity determining domain 1 (CDRH1) comprising an amino acid sequence set forth in SEQ ID NQ:10, a heavy chain complementarity determining domain 2 (CDRH2) comprising an amino acid sequence set forth in SEQ ID NO: 11, a heavy chain complementarity determining domain 3 (CDRH3) comprising an amino acid sequence set forth in SEQ ID NO: 12; and a common light chain variable domain comprising: a light chain complementarity determining domain 1 (CDRL1) comprising an amino acid sequence set forth in SEQ ID NO: 13 a light chain complementarity determining domain 2 (CDRL2) comprising an amino acid sequence set forth in SEQ ID NO: 14, a light chain complementarity determining domain 3 (CDRL3) comprising an amino acid sequence set forth in SEQ ID NO: 15, or a light chain complementarity determining domain 1 (CDRL1) comprising an amino acid sequence set forth in SEQ ID NO: 23 a light chain complementarity determining domain 2 (CDRL2) comprising an amino acid sequence set forth in SEQ ID NO: 24, a light chain complementarity determining domain 3 (CDRL3) comprising an amino acid sequence set forth in SEQ ID NO: 25.

17. The method of claim 16, wherein the anti-CD38 heavy chain variable domain comprises an amino acid sequence having at least 85%, 90%, 95%, 97%, 98%, 99%, or 100% to SEQ ID NO: 1, the anti-CD19 heavy chain variable domain comprises an amino acid sequence having at least 85%, 90%, 95%, 97%, 98%, 99%, or 100% to SEQ ID NO: 2, and common light chain variable domain comprises an amino acid sequence having at least 85%, 90%, 95%, 97%, 98%, 99%, or 100% to SEQ ID NO: 3.

18. The method of claim 16, wherein the common light chain bispecific antibody comprises an anti-CD38 heavy chain amino acid sequence having at least 85%, 90%, 95%, 97%, 98%, 99%, or 100% to SEQ ID NO: 4, an anti-CD19 heavy chain amino acid sequence having at least 85%, 90%, 95%, 97%, 98%, 99%, or 100% to SEQ ID NO: 5, and a common light chain an anti-CD38 heavy chain amino acid sequence having at least 85%, 90%, 95%, 97%, 98%, 99%, or 100% to SEQ ID NO: 6.WSGR Docket Number: 51527-717.60119. The method of any one of claim 16, wherein: the anti-CD38 heavy chain variable domain and the anti-CD19 heavy chain variable domain each comprise a negatively-charged amino acid at heavy chain variable domain position 1 per Kabat numbering; the anti-CD38 heavy chain constant domain and the anti-CD19 heavy chain constant domain each lack a C-terminal lysine residue (K447 per EU numbering); and the common light chain bispecific antibody comprises an experimental isoelectric point (pl) of less than 9.

20. The method of claim 19, wherein the common light chain bispecific antibody exhibits a Hydrophobicity (HIC) retention time of less than about 10 minutes.

21. The method of claim 19, wherein the terminal lysine residue is K447 per EU numbering.

22. The method of claim 8, wherein the anti-CD19 heavy chain variable domain comprises a serine at position 84 and / or a leucine at position 108 according to Kabat numbering.

23. The method of claim 8, wherein the common light chain variable region comprises a histidine at position 32 according to Kabat numbering.

24. The method of claim 19, wherein the negatively-charged amino acid is glutamic acid.

25. The method of claim 19, wherein the pl is between 8.7 and 9.

26. The method of claim 1, wherein the ICI is a PD-1 / PD-L1 axis inhibitor.

27. The method of claim 26, wherein the PD-1 / PD-L1 axis inhibitor is an antibody.

28. The method of claim 27, wherein the antibody is an anti-PD-1 antibody.

29. The method of claim 28, wherein the anti-PD-1 antibody is Pembrolizumab, Nivolumab,Dostarlimab, Retifanlimab, Spartalizumab, Camrelizumab, Sintilimab, Cemiplimab, Tislelizumab, penpulimab, zimberelimab, toripalimab, AMP-514 (MEDI0680), Acrixolimab (YBL-006), or a combination thereof.

30. The method of claim 27, wherein the antibody is an anti-PD-Ll antibody.

31. The method of claim 30, wherein the anti-PD-Ll antibody is Atezolizumab, Avelumab, Durvalumab, Envafolimab (KN035), Cosibelimab (CK-301), or a combination thereof.

32. The method of claim 1, wherein the ICI is a CTLA-4 inhibitor.

33. The method of claim 32, wherein the CTLA-4 inhibitor is an antibody.WSGR Docket Number: 51527-717.60134. The method of claim 33, wherein the antibody is Ipilimumab, Tremelimumab, Quavonlimab, Botensilimab, Zalifrelimab, Gotistobart, XTX101, HCAb 4003-2, or a combination thereof.

35. The method of claim 1, wherein the ICI is a Lag-3 inhibitor.

36. The method of claim 35, wherein the Lag-3 inhibitor is an antibody.

37. The method of claim 36, wherein the antibody is Relatlimab, Leramilimab, Favezelimab, Encelimab (TSR-033), Fianlimab, Sym022, INCAGN02385, BI754111, LBL-007, HLX26, or a combination thereof.

38. The method of claim 1, wherein the ICI is a TIM-3 inhibitor.

39. The method of claim 38, wherein the TIM-3 inhibitor is an antibody.

40. The method of claim 39, wherein the antibody is Sabatolimab (MBG453), MsTOOl, MsT065, MsT229, Cobolimab (TSR-022), Sym023, LY3321367, LY3415244, MBG-A425, MsT286, or a combination thereof.

41. The method of claim 1, wherein the ICI is a TIGIT inhibitor.

42. The method of claim 41, wherein the TIGIT inhibitor is an antibody.

43. The method of claim 42, wherein the antibody is Vibostolimab, Etigilimab, Tiragolumab, Domvanalimab, Ociperlimab, Belrestotug (EOS-448), BMS-986207, ASP8374, COM902, Tamgiblimab (IBI939), or a combination thereof.

44. The method of claim 1, wherein the cancer comprises a solid tumor or a liquid tumor.

45. The method of claim 1, wherein the cancer is characterized by a blood sample taken from the individual and having an increased percentage of B-reg cells relative to a healthy individual blood.

46. The method of claim 1, wherein the individual is characterized by (i) a percentage of B regulatory (B-reg) cells in a blood sample being greater than 1.0% of the percent total B cells in the blood sample and / or (ii) B-reg cells being present a tumor sample, optionally wherein the B-reg cells are present among total CD45+ cells taken from the tumor sample.

47. The method of claim 1, wherein the cancer comprises lung cancer, colorectal cancer, head and neck carcinoma, or pancreatic cancer.

48. The method of claim 47, wherein the cancer is a non-small cell lung cancer, a colorectal adenocarcinoma, a head and neck squamous cell carcinoma, or a pancreatic adenocarcinoma.WSGR Docket Number: 51527-717.60149. The method of claim 1, wherein treating comprises reducing tumor volume as compared to treatment with the ICI alone and / or reducing the rate of tumor growth as compared to treatment with the ICI alone.

50. The method of claim 1, wherein the inhibitor of B regulatory (B-reg) cells is administered concurrently with the immune checkpoint inhibitor (ICI).

51. The method of claim 1, wherein the inhibitor of B regulatory (B-reg) cells and the immune checkpoint inhibitor (ICI) are administered separately.

52. The method of claim 1, wherein the inhibitor of B regulatory (B-reg) cells and the immune checkpoint inhibitor (ICI) are administered separately according to different treatments schedules.

53. The method of claim 1, wherein the individual is currently receiving or has previously received an ICI therapy.

54. The method of claim 1, wherein the cancer is resistant to ICI therapy.

55. The method of claim 1, wherein the cancer is relapsed or refractory to ICI therapy.

56. The method of claim 1, wherein the cancer is a progressive cancer.

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