CD19 antibodies and methods of using same

Abstract

The invention relates generally to CD19 antibodies and antigen-binding fragments thereof, to chimeric receptors comprising the same, and to cells configured to express such proteins. The invention also relates to methods of using such antibodies, chimeric receptors, and cells in the treatment of various diseases, including cancer and autoimmune diseases.

Description

CD19 ANTIBODIES AND METHODS OF USING SAMECROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to U.S. Provisional Application No. 63 / 654,521, filed May 31, 2025, the entire disclosure of which is hereby incorporated by reference in its entirety for all purposes.SEQUENCE LISTING

[0002] This application contains a Sequence Listing which has been submitted electronically in XML format and is hereby incorporated by reference in its entirety. The XML copy, created on May 29, 2025, is named CBB-205WO_SL.xml and is 182,607 bytes in size.FIELD OF THE DISCLOSURE

[0003] The disclosure relates generally to CD 19 antibodies and antigen-binding fragments thereof, to chimeric receptors comprising the same, and to cells configured to express such proteins. The disclosure also relates to methods of using such antibodies, chimeric receptors, and cells in the treatment of various diseases, including autoimmune diseases.BACKGROUND

[0004] CD 19 is a transmembrane glycoprotein expressed on the surface of B lymphocytes from the earliest recognizable B-lineage cells during development to B-cell blasts. It primarily acts as a B cell co-receptor in conjunction with CD21 and CD81. CD 19 is expressed on auto-reactive B cells in autoimmune diseases, such as multiple sclerosis and rheumatoid arthritis. CD 19 is also expressed in many cancers, such as chronic lymphocytic leukemia, non-Hodgkin’s lymphoma, follicular lymphoma, acute lymphoblastic leukemia, multiple myeloma, and B-cell malignancies.

[0005] Over the course of the last decade, chimeric antigen receptor (CAR) T cell therapy has become an established treatment for a variety of cancers. The method has seen particular success in haematological malignancies such as acute lymphoblastic leukemia (ALL) and diffuse large B-cell lymphoma (DLBCL). In general, CAR T cell therapy for the treatment of cancer involves isolating T cells from human blood, genetically engineering the cells to express a CAR against a desired target antigen, and subsequently administering the engineered CAR T cells to the patient, thereby allowing the CAR T cells to target and destroycancerous cells expressing this antigen. More recently, CAR T cell therapy has also been investigated as treatment for autoimmune diseases, including refractory systemic lupus erythematosus (SLE), a B-cell-mediated autoimmune disease. Researchers reported that administration of a CAR T cell therapy induced clinical remission in 5 out of 5 patients with moderate to severe, refractory SLE (Mackensen et al. (2022) NAT. MED. 28: 2124-2132).

[0006] CD19-directed CAR T cell therapies have led to lasting remissions of B cell leukemias and lymphomas (Abramson (2020) TRANSFUS. MED. REV. 37: 29-33; Locke et al. (2019) LANCET ONCOL. 20: 31-42; Maude et al. (2015) N. ENGL. J. MED. 371: 1507-1517; Schuster (2019) LANCET ONCOL. 20: 2-3). CD19-CAR T cell therapies were the first CAR T therapies to receive EDA approval, and four CAR T products are now commercially available to patients, including tisagenlecleucel (Kymriah®), axicabtagene ciloleucel (Y escarta®), lisocabtagene maraleucel (Breyanzi®), and Brexucabtagene autoleucel (Tecartus®). All four of these approved CAR-T cell therapy products contain the same scFv binding domain, FMC63, which is derived from a murine CD19-specific monoclonal antibody. However, the use of a murine-derived CD 19 binder may lead to the development of a host immune response against immunogenic epitopes in the extracellular binding domain of the CAR, which may impact persistence of the CAR T cells and the efficacy of the therapy.Accordingly, in spite of the advancements made to date, there remains a need for additional anti-CD19 therapeutics.SUMMARY OF THE DISCLOSURE

[0007] The present disclosure is based, in part, upon the discovery of new, fully human anti-CD19 antibodies and their manufacture and use in the treatment of various diseases and disorders, including autoimmune diseases and cancer. Accordingly, in one aspect, the present disclosure provides an antibody or antigen-binding fragment thereof that binds to CD 19 comprising three heavy chain complementarity determining regions (CDRs) (CDRm, CDRH2, and CDRm) and three light chain complementarity determining regions (CDRs) (CDRLI, CDRL2, and CDRij). wherein: (i) the CDRm, CDRm, and CDRm are present in a heavy chain variable domain (VH) comprising the amino acid sequence set forth in SEQ ID NO: 7, and the CDRLI, CDRL2, and CDRLS are present in a light chain variable domain (VL) comprising the amino acid sequence set forth in SEQ ID NO: 8; (ii) the CDRm, CDRm, and CDRm are present in a heavy chain variable domain (VH) comprising the amino acid sequence set forth in SEQ ID NO: 1, and the CDRLI, CDRL2, and CDRLS are present in a light chain variable domain (VL) comprising the amino acid sequence set forth in SEQ ID NO: 2;(iii) the CDRHI, CDRH2, and CDRHS are present in a heavy chain variable domain (VH) comprising the amino acid sequence set forth in SEQ ID NO: 4, and the CDRLI, CDRL2, and CDRLS are present in a light chain variable domain (VL) comprising the amino acid sequence set forth in SEQ ID NO: 5; (iv) the CDRHI, CDRH2, and CDRH3 are present in a heavy chain variable domain (VH) comprising the amino acid sequence set forth in SEQ ID NO: 10, and the CDRLI, CDRL2, and CDRL3 are present in a light chain variable domain (VL) comprising the amino acid sequence set forth in SEQ ID NO: 11; (v) the CDRHI, CDRH2, and CDRH3 are present in a heavy chain variable domain (VH) comprising the amino acid sequence set forth in SEQ ID NO: 13, and the CDRLI, CDRL2, and CDRL3 are present in a light chain variable domain (VL) comprising the amino acid sequence set forth in SEQ ID NO: 14; (vi) the CDRHI, CDRH2, and CDRH3 are present in a heavy chain variable domain (VH) comprising the amino acid sequence set forth in SEQ ID NO: 16, and the CDRLI, CDRL2, and CDRL3 are present in a light chain variable domain (VL) comprising the amino acid sequence set forth in SEQ ID NO: 17; (vii) the CDRHI, CDRH2, and CDRH3 are present in a heavy chain variable domain (VH) comprising the amino acid sequence set forth in SEQ ID NO: 19, and the CDRLI, CDRL2, and CDRL3 are present in a light chain variable domain (VL) comprising the amino acid sequence set forth in SEQ ID NO: 20; (viii) the CDRHI, CDRH2, and CDRH3 are present in a heavy chain variable domain (VH) comprising the amino acid sequence set forth in SEQ ID NO: 22, and the CDRLI, CDRL2, and CDRL3 are present in a light chain variable domain (VL) comprising the amino acid sequence set forth in SEQ ID NO: 23; (ix) the CDRHI, CDRH2, and CDRH3 are present in a heavy chain variable domain (VH) comprising the amino acid sequence set forth in SEQ ID NO: 25, and the CDRLI, CDRL2, and CDRL3 are present in a light chain variable domain (VL) comprising the amino acid sequence set forth in SEQ ID NO: 26; or (x) the CDRHI, CDRH2, and CDRH3 are present in a heavy chain variable domain (VH) comprising the amino acid sequence set forth in SEQ ID NO: 28, and the CDRLI, CDRL2, and CDRL3 are present in a light chain variable domain (VL) comprising the amino acid sequence set forth in SEQ ID NO: 29. In certain embodiments, the CDRHI, CDRH2, CDRH3, CDRLI, CDRL2, and CDRL3 are defined according to Kabat, Chothia, IMGT, AbM, Contact, or Honneger (AHo).

[0008] In another aspect, the present disclosure provides an antibody or antigen-binding fragment thereof that binds to CD 19, comprising a heavy chain variable domain (VH) comprising complementarity determining regions CDRHI, CDRH2, and CDRH3 and a light chain variable domain (VL) comprising complementarity determining regions CDRLI, CDRL2,and CDRLS, wherein: (i) the CDRHI comprises the amino acid sequence of SEQ ID NO: 43, 86, or 108; the CDRH2 comprises the amino acid sequence of SEQ ID NO: 44, 87, or 109; the CDRHS comprises the amino acid sequence of SEQ ID NO: 45 or 110; the CDRLI comprises the amino acid sequence of SEQ ID NO: 46 or 111; the CDRL2 comprises the amino acid sequence of SEQ ID NO: 47 or DAS; and the CDRLS comprises the amino acid sequence of SEQ ID NO: 48; (ii) the CDRHI comprises the amino acid sequence of SEQ ID NO: 31, 82, or 98; the CDRH2 comprises the amino acid sequence of SEQ ID NO: 32, 83, or 99; the CDRH3 comprises the amino acid sequence of SEQ ID NO: 33 or 100; the CDRLI comprises the amino acid sequence of SEQ ID NO: 34 or 101; the CDRL2 comprises the amino acid sequence of SEQ ID NO: 35 or AAS; and the CDRLS comprises the amino acid sequence of SEQ ID NO: 36; (iii) the CDRHI comprises the amino acid sequence of SEQ ID NO: 37, 84, or 103; the CDRH2 comprises the amino acid sequence of SEQ ID NO: 38, 85, or 104; the CDRH3 comprises the amino acid sequence of SEQ ID NO: 39 or 105; the CDRLI comprises the amino acid sequence of SEQ ID NO: 40 or 106; the CDRL2 comprises the amino acid sequence of SEQ ID NO: 41 or DAS; and the CDRLS comprises the amino acid sequence of SEQ ID NO: 42; (iv) the CDRHI comprises the amino acid sequence of SEQ ID NO: 31, 82, or 98; the CDRH2 comprises the amino acid sequence of SEQ ID NO: 49, 88, or 112; the CDRH3 comprises the amino acid sequence of SEQ ID NO: 50 or 113; the CDRLI comprises the amino acid sequence of SEQ ID NO: 51 or 114; the CDRL2 comprises the amino acid sequence of SEQ ID NO: 52 or LGS; and the CDRLS comprises the amino acid sequence of SEQ ID NO: 53; (v) the CDRHI comprises the amino acid sequence of SEQ ID NO: 31, 82, or 98; the CDRH2 comprises the amino acid sequence of SEQ ID NO: 54, 89, or 116; the CDRH3 comprises the amino acid sequence of SEQ ID NO: 55 or 117; the CDRLI comprises the amino acid sequence of SEQ ID NO: 56 or 118; the CDRL2 comprises the amino acid sequence of SEQ ID NO: 57 or GIS; and the CDRLS comprises the amino acid sequence of SEQ ID NO: 58; (vi) the CDRHI comprises the amino acid sequence of SEQ ID NO: 31, 82, or 98; the CDRH2 comprises the amino acid sequence of SEQ ID NO: 32, 90, or 99; the CDRH3 comprises the amino acid sequence of SEQ ID NO: 78 or 120; the CDRLI comprises the amino acid sequence of SEQ ID NO: 79 or 121; the CDRL2 comprises the amino acid sequence of SEQ ID NO: 80 or GAS; and the CDRLS comprises the amino acid sequence of SEQ ID NO: 81; (vii) the CDRHI comprises the amino acid sequence of SEQ ID NO: 43, 91, or 123; the CDRH2 comprises the amino acid sequence of SEQ ID NO: 59, 92, or 124; the CDRH3 comprises the amino acid sequence of SEQ ID NO: 60 or 125; the CDRLI comprises the amino acid sequence of SEQ ID NO: 61 or 126; the CDRL2 comprises the amino acidsequence of SEQ ID NO: 62 or LGS; and the CDRLS comprises the amino acid sequence of SEQ ID NO: 63; (viii) the CDRHI comprises the amino acid sequence of SEQ ID NO: 64, 93, or 127; the CDRH2 comprises the amino acid sequence of SEQ ID NO: 32, 90, or 99; the CDRHS comprises the amino acid sequence of SEQ ID NO: 65 or 128; the CDRLI comprises the amino acid sequence of SEQ ID NO: 34 or 101; the CDRL2 comprises the amino acid sequence of SEQ ID NO: 47 or DAS; and the CDRLS comprises the amino acid sequence of SEQ ID NO: 66; (ix) the CDRHI comprises the amino acid sequence of SEQ ID NO: 67, 94, or 129; the CDRH2 comprises the amino acid sequence of SEQ ID NO: 68, 95, or 130; the CDRH3 comprises the amino acid sequence of SEQ ID NO: 69 or 131; the CDRLI comprises the amino acid sequence of SEQ ID NO: 70 or 132; the CDRL2 comprises the amino acid sequence of SEQ ID NO: 71 or DAS; and the CDRLS comprises the amino acid sequence of SEQ ID NO: 72; or (x) the CDRHI comprises the amino acid sequence of SEQ ID NO: 73, 96, or 133; the CDRH2 comprises the amino acid sequence of SEQ ID NO: 32, 97, or 134; the CDRH3 comprises the amino acid sequence of SEQ ID NO: 74 or 135; the CDRLI comprises the amino acid sequence of SEQ ID NO: 75 or 136; the CDRL2 comprises the amino acid sequence of SEQ ID NO: 76 or AAS; and the CDRLS comprises the amino acid sequence of SEQ ID NO: 77.

[0009] In certain embodiments, the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 43, 44, and 45, respectively, and the CDRLI, CDRL2, and CDRLS comprise the amino acid sequences of SEQ ID NOs: 46, 47, and 48, respectively.

[0010] In certain embodiments, the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 31, 32, and 33, respectively, and the CDRLI, CDRL2, and CDRLS comprise the amino acid sequences of SEQ ID NOs: 34, 35, and 36, respectively.

[0011] In certain embodiments, the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 37, 38, and 39, respectively, and the CDRLI, CDRL2, and CDRLS comprise the amino acid sequences of SEQ ID NOs: 40, 41, and 42, respectively.

[0012] In certain embodiments, the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 31, 49, and 50, respectively, and the CDRLI, CDRL2, and CDRLS comprise the amino acid sequences of SEQ ID NOs: 51, 52, and 53, respectively.

[0013] In certain embodiments, the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 31, 54, and 55, respectively, and the CDRLI, CDRL2, and CDRLS comprise the amino acid sequences of SEQ ID NOs: 56, 57, and 58, respectively.

[0014] In certain embodiments, the CDRHI, CDRH2, and CDRHS comprise the amino acid sequences of SEQ ID NOs: 31, 32, and 78, respectively, and the CDRLI, CDRL2, and CDRLS comprise the amino acid sequences of SEQ ID NOs: 79, 80, and 81, respectively.

[0015] In certain embodiments, the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 43, 59 and 60, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NOs: 61, 62, and 63, respectively.

[0016] In certain embodiments, the CDRHI, CDRH2, and CDRIB comprise the amino acid sequences of SEQ ID NOs: 64, 32, and 65, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NOs: 34, 47, and 66, respectively.

[0017] In certain embodiments, the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 67, 68, and 69, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NOs: 70, 71, and 72, respectively.

[0018] In certain embodiments, the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 73, 32, and 74, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NOs: 75, 76, and 77, respectively.

[0019] In certain embodiments, the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 86, 87, and 45, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NOs: 46, 47, and 48, respectively.

[0020] In certain embodiments, the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 82, 83, and 33, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NOs: 34, 35, and 36, respectively.

[0021] In certain embodiments, the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 84, 85, and 39, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NOs: 40, 41, and 42, respectively.

[0022] In certain embodiments, the CDRHI, CDRH2, and CDRIB comprise the amino acid sequences of SEQ ID NOs: 82, 88, and 50, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NOs: 51, 52, and 53, respectively.

[0023] In certain embodiments, the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 82, 89, and 55, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NOs: 56, 57, and 58, respectively.

[0024] In certain embodiments, the CDRHI, CDRH2, and CDRHS comprise the amino acid sequences of SEQ ID NOs: 82, 90, and 78, respectively, and the CDRLI, CDRL2, and CDRLS comprise the amino acid sequences of SEQ ID NOs: 79, 80, and 81, respectively.

[0025] In certain embodiments, the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 91, 92, and 60, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NOs: 61, 62, and 63, respectively.

[0026] In certain embodiments, the CDRHI, CDRH2, and CDRIB comprise the amino acid sequences of SEQ ID NOs: 93, 90, and 65, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NOs: 34, 47, and 66, respectively.

[0027] In certain embodiments, the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 94, 95, and 69, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NOs: 70, 71, and 72, respectively.

[0028] In certain embodiments, the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 96, 97, and 74, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NOs: 75, 76, and 77, respectively.

[0029] In certain embodiments, the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 108, 109, and 110, respectively, and the CDRLI, CDRL2, and CDRLS comprise the amino acid sequences of SEQ ID NO: 111, DAS, and SEQ ID NO: 48, respectively.

[0030] In certain embodiments, the CDRHI, CDRH2, and CDRIB comprise the amino acid sequences of SEQ ID NOs: 98, 99, and 100, respectively, and the CDRLI, CDRL2, and CDRLS comprise the amino acid sequences of SEQ ID NO: 101, AAS, and SEQ ID NO: 36, respectively.

[0031] In certain embodiments, the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 103, 104, and 105, respectively, and the CDRLI, CDRL2, and CDRLS comprise the amino acid sequences of SEQ ID NO: 106, DAS, and SEQ ID NO: 42, respectively.

[0032] In certain embodiments, the CDRHI, CDRH2, and CDRIB comprise the amino acid sequences of SEQ ID NOs: 98, 112, and 113, respectively, and the CDRLI, CDRL2, and CDRLS comprise the amino acid sequences of SEQ ID NO: 114, LGS, and SEQ ID NO: 53, respectively.

[0033] In certain embodiments, the CDRHI, CDRH2, and CDRHS comprise the amino acid sequences of SEQ ID NOs: 98, 116, and 117, respectively, and the CDRLI, CDRL2, and CDRLS comprise the amino acid sequences of SEQ ID NO: 118, GIS, and SEQ ID NO: 58, respectively.

[0034] In certain embodiments, the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 98, 99, and 120, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NO: 121, GAS, and SEQ ID NO: 81, respectively.

[0035] In certain embodiments, the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 123, 124, and 125, respectively, and the CDRLI, CDRL2, and CDRLS comprise the amino acid sequences of SEQ ID NO: 126, LGS, and SEQ ID NO: 63, respectively.

[0036] In certain embodiments, the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 127, 99, and 128, respectively, and the CDRLI, CDRL2, and CDRLS comprise the amino acid sequences of SEQ ID NO: 101, DAS, and SEQ ID NO: 66, respectively.

[0037] In certain embodiments, the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 129, 130, and 131, respectively, and the CDRLI, CDRL2, and CDRLS comprise the amino acid sequences of SEQ ID NO: 132, DAS, and SEQ ID NO: 72, respectively.

[0038] In certain embodiments, the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 133, 134, and 135, respectively, and the CDRLI, CDRL2, and CDRLS comprise the amino acid sequences of SEQ ID NO: 136, AAS, and SEQ ID NO: 77, respectively.

[0039] In certain embodiments of any of the foregoing antibodies or antigen-binding fragments thereof, the CDRs can be interposed between human or humanized immunoglobulin framework regions.

[0040] In certain embodiments, the VH and the VL comprise amino acid sequences at least 95% identical to the amino acid sequences of SEQ ID NOs: 7 and 8, respectively. In certain embodiments, the VH and the VL comprise the amino acid sequences of SEQ ID NOs: 7 and 8, respectively.

[0041] In certain embodiments, the VH and the VL comprise amino acid sequences at least 95% identical to the amino acid sequences of SEQ ID NOs: 1 and 2, respectively. In certain embodiments, the VH and the VL comprise the amino acid sequences of SEQ ID NOs: 1 and 2, respectively.

[0042] In certain embodiments, the VH and the VL comprise amino acid sequences at least 95% identical to the amino acid sequences of SEQ ID NOs: 4 and 5, respectively. In certain embodiments, the VH and the VL comprise the amino acid sequences of SEQ ID NOs: 4 and 5, respectively.

[0043] In certain embodiments, the VH and the VL comprise amino acid sequences at least 95% identical to the amino acid sequences of SEQ ID NOs: 10 and 11, respectively. In certain embodiments, the VH and the VL comprise the amino acid sequences of SEQ ID NOs: 10 and 11, respectively.

[0044] In certain embodiments, the VH and the VL comprise amino acid sequences at least 95% identical to the amino acid sequences of SEQ ID NOs: 13 and 14, respectively. In certain embodiments, the VH and the VL comprise the amino acid sequences of SEQ ID NOs: 13 and 14, respectively.

[0045] In certain embodiments, the VH and the VL comprise amino acid sequences at least 95% identical to the amino acid sequences of SEQ ID NOs: 16 and 17, respectively. In certain embodiments, the VH and the VL comprise the amino acid sequences of SEQ ID NOs: 16 and 17, respectively.

[0046] In certain embodiments, the VH and the VL comprise amino acid sequences at least 95% identical to the amino acid sequences of SEQ ID NOs: 19 and 20, respectively. In certain embodiments, the VH and the VL comprise the amino acid sequences of SEQ ID NOs: 19 and 20, respectively.

[0047] In certain embodiments, the VH and the VL comprise amino acid sequences at least 95% identical to the amino acid sequences of SEQ ID NOs: 22 and 23, respectively. In certain embodiments, the VH and the VL comprise the amino acid sequences of SEQ ID NOs: 22 and 23, respectively.

[0048] In certain embodiments, the VH and the VL comprise amino acid sequences at least 95% identical to the amino acid sequences of SEQ ID NOs: 25 and 26, respectively. In certain embodiments, the VH and the VL comprise the amino acid sequences of SEQ ID NOs: 25 and 26, respectively.

[0049] In certain embodiments, the VH and the VL comprise amino acid sequences at least 95% identical to the amino acid sequences of SEQ ID NOs: 28 and 29, respectively. In certain embodiments, the VH and the VL comprise the amino acid sequences of SEQ ID NOs: 28 and 29, respectively.

[0050] In certain embodiments of any of the foregoing antibodies or antigen-binding fragments thereof, the antibody or antigen-binding fragment thereof is humanized or fully human.

[0051] In another aspect, the present disclosure provides an antibody or antigen-binding fragment thereof that competes for binding to CD 19 with an antibody or antigen-binding fragment thereof of any one of the foregoing embodiments. In another aspect, the present disclosure provides an antibody or antigen-binding fragment thereof that binds to the same epitope on CD 19 as an antibody or antigen-binding fragment thereof of any one of the foregoing embodiments.

[0052] In certain embodiments of any of the foregoing, the CD 19 bound by the antibody is human CD 19. In certain embodiments, the antibody or antigen-binding fragment thereof binds to human CD 19 with a KD of 200 nM or stronger, 100 nM or stronger, 75 nM or stronger, 50 nM or stronger, 25 nM or stronger, 20 nM or stronger, or 15 nM or stronger, as measured by, e.g., surface plasmon resonance.

[0053] In certain embodiments of any of the foregoing, the antibody or antigen-binding fragment thereof comprises an scFv. The scFv can comprise, for example, an amino acid sequence at least 95% identical to the amino acid sequence of any one of SEQ ID NOs: 9, 3, 6, 12, 15, 18, 21, 24, 27, or 30. In certain embodiments, the scFv comprises the amino acid sequence of any one of SEQ ID NOs: 9, 3, 6, 12, 15, 18, 21, 24, 27, or 30.

[0054] In another aspect, the present disclosure provides a chimeric antigen receptor (CAR) comprising an extracellular binding domain comprising an antibody or antigen-binding fragment thereof disclosed herein. The CAR can, for example, further comprise (i) a transmembrane domain (for example, a CD 8 alpha chain transmembrane domain, e.g., a CD 8 alpha chain transmembrane domain comprising the amino acid sequence of SEQ ID NO: 137), a costimulatory domain (for example, a 4-1BB intracellular domain, e.g., a 4-1BB intracellular domain comprising the amino acid sequence of SEQ ID NO: 138), and / or an intracellular signaling domain (for example, a CD3 zeta signaling domain, e.g., a CD3 zeta signaling domain comprises the amino acid sequence of SEQ ID NO: 139); or (ii) a killerimmunoglobulin-like receptor (KIR) transmembrane domain and a KIR cytoplasmic domain. In certain embodiments, the CAR further comprises a hinge domain or linker interposed between the extracellular binding domain and the transmembrane domain, for example, a CD8 alpha chain hinge, e.g., a CD8 alpha chain hinge comprising the amino acid sequence of SEQ ID NO: 140. In certain embodiments, the CAR comprises the amino acid sequence of any one of SEQ ID NOs: 141-160.

[0055] In another aspect, the present disclosure provides a nucleic acid comprising a nucleotide sequence encoding the VH of an antibody disclosed herein and / or a nucleotide sequence encoding the VL of an antibody disclosed herein. In another aspect, the present disclosure provides a vector (e.g., a viral vector, such as a lentiviral vector or an adeno- associated viral vector) comprising the nucleic acid.

[0056] In another aspect, the present disclosure provides a nucleic acid comprising a nucleotide sequence encoding a CAR disclosed herein. In another aspect, the present disclosure provides a vector (e.g., a viral vector, such as a lentiviral vector or an adeno- associated viral vector) comprising the nucleic acid.

[0057] In another aspect, the present disclosure provides a genetically modified cell comprising a nucleic acid and / or vector described above. In another aspect, the present disclosure provides a genetically modified cell configured to express a CAR disclosed herein. In certain embodiments, the genetically modified cell is an immune cell, e.g., a T cell or a natural killer cell. In certain embodiments, the immune cell is a T cell selected from a cytotoxic T cell, a helper T cell, a memory T cell, an alpha beta T cell, and a gamma delta T cell.

[0058] In another aspect, the present disclosure provides a pharmaceutical composition comprising a nucleic acid described above, a vector described above, or a genetically modified cell described above, and a pharmaceutically acceptable carrier or excipient.

[0059] In another aspect, the present disclosure provides a method of treating a disease in a subject in need thereof, the method comprising administering to the subject a nucleic acid described above, a vector described above, or a pharmaceutical composition described above.

[0060] In another aspect, the present disclosure provides a method of treating a disease in a subject in need thereof, the method comprising administering to the subject a genetically modified cell disclosed herein, e.g., a genetically modified cell that is autologous to thesubject. In certain embodiments, the method comprises administering the genetically modified cell to the subject at a dose from 1 x 105cells / kg to 1 x 108cells / kg.

[0061] In certain embodiments of any of the foregoing therapeutic methods, the disease is an autoimmune disease, e.g., a B-cell-mediated autoimmune disease. For example, the autoimmune disease can be selected from systemic lupus erythematosus (SLE), pemphigus vulgaris (PV), myasthenia gravis (MG), myositis, systemic sclerosis, multiple sclerosis, membranous nephropathy, and chronic immune demyelinating polyneuropathy. In certain embodiments, the autoimmune disease is selected from the group consisting of lupus nephritis, SLE with anti-dsDNA antibodies, mucosal PV, mucocutaneous PV, MuSK- associated MG, AChR MG, anti-synthetase syndrome, dermatomyositis, juvenile myositis, systemic sclerosis with skin involvement, systemic sclerosis with severe organ involvement, and immune mediated necrotizing myopathy.

[0062] In certain embodiments of the therapeutic methods disclosed herein, the disease to be treated is cancer, e.g., a cancer selected from leukemia, acute leukemia, acute lymphoblastic leukemia (ALL), B-cell ALL, acute myeloid leukemia (AML), chronic myelocytic leukemia (CML), chronic lymphocytic leukemia (CLL), transformed CLL, diffuse large B-cell lymphomas (DLBCL), follicular lymphoma, hairy cell leukemia, a lymphoma, Hodgkin’s disease, a malignant lymphoma, non-Hodgkin’s lymphoma, Burkitt’s lymphoma, multiple myeloma, and Richter’s Syndrome (Richter’s Transformation). In certain embodiments, the cancer is a hematological cancer.

[0063] These and other aspects and features of the present disclosure are described in the following detailed description and claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0064] The disclosure can be more completely understood with reference to the following drawings.

[0065] FIGURE 1 depicts a schematic diagram of an exemplary CAR construct.

[0066] FIGURE 2 is a bar graph summarizing the percentage of Expi293 cells successfully expressing one of ten CARs, following transient transfection with a lentiviral vector encoding a CAR comprising a fully human CD19-binder of the disclosure. Expi293 cells that were not transduced (“NTD”) or that were transduced with a CAR comprising the CD19-binder FMC63 (“FMC63”) were used as controls.

[0067] FIGURE 3 is a bar graph summarizing the percentage of primary human T cells successfully expressing a CD19-CAR. T cells obtained from two human donors (“Donor 1” and “Donor 2”) were transduced with a lentiviral vector encoding a CD19-CAR comprising one of seven different fully human CD19-binders, and CD19-CAR-expression was assessed by flow cytometry following staining with fluorescently labeled CD 19 antigen. Cells that were not transduced (“NTD”) or that were transduced with a CAR comprising the CD 19- binder FMC63 (“FMC63”) were used as controls.

[0068] FIGURES 4A-4J summarize the cytotoxicity of CD19-CAR T cells against CD 19+ Nalm6 target cells. T cells obtained from two human donors (“Donor 1” and “Donor 2”) were transduced with a lentiviral vector encoding a CD19-CAR and co-cultured with target Nalm6 cells at the indicated effector: target (E:T) ratios at 9 days post-transduction. Cytolysis of GFP-expressing Nalm6 cells was monitored for 120 hours. Nalm6 cytolysis for CARs comprising the fully human CD19-binders A06, E04, E06, E10, F03, F10, and H06 is summarized in FIGURES 4C, 4D, 4E, 4F, 4G, 4H, and 41, respectively. Nalm6 cells cocultured with non-transduced T cells (FIGURE 4A) or with T cells transduced with a CAR comprising the CD19-binder FMC63 (FIGURE 4B) were used as controls. Data represent mean counts of GFP+ cells in triplicate, and the E:T ratio was calculated based on the number of CAR+ T-cells. FIGURE 4J and FIGURE 4K are bar graphs depicting the area under the curve (AUC) for the data shown in FIGURES 4A-4I for T cells obtained from Donor 1 and Donor 2, respectively.

[0069] FIGURE 5 summarizes the results of an off-target binding screen for four fully human anti-CD19 antibodies. Antibodies comprising a fully human CD 19 binder and a human Fc region were incubated with clones expressing one of 6,000 distinct human membrane proteins, and target binding was measured using flow cytometry to detect a fluorescently labeled secondary antibody. FCGR1A represents High-affinity Immunoglobulin Gamma Fc Receptor 1; ATL2 represents Atlastin-2; LRTM2 represents Leucine-rich Repeat and Transmembrane Domain-containing Protein 2.

[0070] FIGURES 6A-6B are graphs showing the ability of CD19-CAR T cells to proliferate in response to stimulation with CD19-expressing target cells. Primary T cells were transduced with a lentiviral vector encoding a CD19-CAR comprising the fully human CD19-binder A06, E04, or E06. The CD19-CAR T cells were co-cultured with target Nalm6 cells at a 1: 1 effectortarget (E:T) ratio, and the numbers of CD3+ cells (FIGURE 6A) and CAR+ T cells (FIGURE 6B) were monitored for 31 days. Each condition was run intriplicate. Non-transfected T cells (“NTD”) and T cells expressing a CAR comprising the CD19-binder FMC63 were used as controls.

[0071] FIGURE 7A-7E are graphs showing the cytotoxicity of primary CD4+ and CD8+ T cells expressing a CAR comprising the fully human CD19-binder E04 against CD 19+ Nalm6 target cells. Primary human T cells were transduced with a lentiviral vector encoding the CD19-CAR. Total CAR-T cells (FIGURE 7B), CD4+ CAR-T cells (FIGURE 7C), or CD8+ CAR-T cells (FIGURE 7D) were co-cultured with target Nalm6 cells at the indicated effectortarget (E:T) ratios, and cytolysis of GFP -expressing Nalm6 cells was monitored for 120 hours. Nalm6 cells co-cultured with non-transduced T cells (FIGURE 7A) and cultures of target cells not incubated with T cells (“Targets only”) were used as controls. Data represent mean counts of GFP+ cells in triplicate, and the E:T ratio was calculated based on the percentage of CAR+ T-cells. FIGURE 7E is a bar graph depicting the area under the curve (AUC) for the data shown in FIGURES 7A-7D.

[0072] FIGURES 8A-8B are bar graphs showing expression of IFNy and TNFa from CD3+, CD4+, and CD8+ CD19-CAR T cells. Primary T cells were transduced with a lentiviral vector encoding a CD19-CAR comprising the fully human E06 CD19-binder, stimulated with PMA and ionomycin, and stained for CD3, CD4, CD8, CAR, IFNy, and TNFa. The percentage of cells secreting each cytokine (FIGURE 8A) and the mean fluorescent intensity for each cytokine (FIGURE 8B) were measured.

[0073] FIGURES 9A-9D are graphs showing the in vivo efficacy of CD19-CAR T cells of the disclosure. Primary T cells were transduced with a lentiviral vector encoding a CD 19- CAR comprising a fully human CD19-binder (E04 or E06, as indicated). Immunodeficient NSG mice were injected with CD19+ Nalm6 target cells at Day -5 and, at Day 0, mice were injected with a dose of IxlO6CAR-T cells / mouse (“low”), 3xl06CAR-T cells per mouse (“mid”), or IxlO7CAR-T cells / mouse (“high”). The proliferation of Nalm6 target cells in the mice was monitored for 28 days by bioluminescent imaging (BLI, FIGURE 9B and FIGURE 9D), and mouse body weights were monitored throughout the study (FIGURE 9A and FIGURE 9C). Results for each condition are shown overlaid (FIGURES 9A-9B) and are plotted individually (FIGURES 9C-9D). Data represent means + / - SEM.DETAILED DESCRIPTION

[0074] The present disclosure is based, in part, upon the discovery of new, fully human anti-CD19 antibodies and their manufacture and use in the treatment of various diseases and disorders, including autoimmune diseases and cancer. I. Definitions

[0075] To facilitate an understanding of the present disclosure, a number of terms and phrases are defined below.

[0076] The terms “a” and “an” as used herein mean “one or more” and include the plural unless the context is inappropriate. By way of example, “an element” means one element or more than one element.

[0077] Where the use of the term “about” is before a quantitative value, the present disclosure also includes the specific quantitative value itself, unless specifically stated otherwise. As used herein, the term “about” refers to a ±10% variation from the nominal value unless otherwise indicated or inferred.

[0078] The term “and / or” is used in this disclosure to mean either “and” or “or” unless indicated otherwise. The expression “and / or” in connection with three or more recited objects should be understood to have the same meaning unless otherwise understood from the context.

[0079] As used herein, unless otherwise indicated, the term “antibody” is understood to mean an intact antibody (e.g., an intact monoclonal antibody) or antigen-binding fragment of an antibody (e.g., an antigen-binding fragment of a monoclonal antibody), including an intact antibody or antigen-binding fragment that has been modified, engineered, or chemically conjugated. Examples of antigen-binding fragments include Fab, Fab’, (Fab’)2, Fv, single chain antibodies (e.g., scFv), minibodies, diabodies, triabodies, and dual affinity retargeting antibodies (DARTs). Examples of antibodies that have been modified or engineered include chimeric antibodies, humanized antibodies, and multispecific antibodies (e.g., bispecific antibodies). An example of a chemically conjugated antibody is an antibody conjugated to a toxin moiety.

[0080] Certain animals have different forms of antibodies. For example, camelids have antibodies comprising VHH fragments and cartilaginous fishes have antibodies called “new antigen receptor immunoglobulins” or “IgNARs” comprising VNAR fragments, where suchfragments, which are single, monomeric antibody variable domains that are able to bind selectively to a specific antigen independently of another variable domain, are called “single domain antibody,” “sdAb,” or “nanobody.” An antibody or antigen-binding fragment of an antibody can comprise either a pair of VH and VL or an sdAb. An antibody or antigenbinding fragment of an antibody disclosed herein can be recombinant, chimeric, deimmunized, humanized, and / or affinity matured (see, e.g., U.S. Pat. No. 4,816,567; Morrison et al. (1984) PROC. NATL. ACAD. SCI. U.S.A., 81: 6851-55; Morrison et al. (1985) PROC. NATL. ACAD. SCI. U.S.A., 81:6851; Takeda et al. (1985) NATURE, 314: 452).

[0081] It should be understood that the expression “at least one of’ includes individually each of the recited objects after the expression and the various combinations of two or more of the recited objects unless otherwise understood from the context and use. The expression “and / or” in connection with two, three, or more recited objects should be understood to have the same meaning unless otherwise understood from the context.

[0082] The term “CD 19” as used herein includes variants, isoforms, and species homologs of CD 19, and the term “human CD 19” as used herein includes variants, isoforms, and species homologs of human CD 19. Antibodies of this disclosure may, in certain cases, cross-react with CD 19 from species other than human. In certain embodiments, the antibodies may be completely specific for one or more human CD 19 proteins and may not exhibit species or other types of non-human cross-reactivity. The complete amino acid sequence of an exemplary human CD 19 has Swiss-Prot accession number Pl 5391 (CD19_HUMAN; SEQ ID NO: 165). CD19 (Cluster of Differentiation 19) is also known as CD 19 molecule, B-lymphocyte antigen CD 19, B-Eymphocyte Surface Antigen B4, T-Cell Surface Antigen Leu-12, and CVID3. Human CD19 is designated GenelD: 930 by Entrez Gene, and HGNC ID: 1633 by HGNC. CD19 can be encoded by the gene designated by the same name (CD19). The term “human CD19” encompasses all known or as yet undiscovered alleles and polymorphic forms of human CD 19. The terms “human CD 19” and “CD 19” are used interchangeably herein, unless otherwise understood from the context and use.

[0083] The terms “chimeric antigen receptor” or “CAR,” as used herein, refer to a recombinant receptor that is expressed by a cell, e.g., an immune cell or any other effector cell type, e.g., an effector cell type capable of cell-mediated cytotoxicity, such as a T cell. The CAR includes an extracellular binding domain that specifically binds a protein on the surface of a target cell, e.g., a cell surface protein (e.g., B-cell surface protein) such as CD 19. The binding domain can comprise, for example, an antigen-binding fragment of an antibody,e.g., an anti-CD19 antibody of the disclosure, e.g., a CD19-binding scFv. The CAR may also optionally include (i) a transmembrane domain, a signaling domain, and / or an intracellular costimulatory domain; or (ii) a killer immunoglobulin-like receptor (KIR) transmembrane domain and a KIR cytoplasmic domain.

[0084] The term “cross-compete,” as used herein in the context of a subject antibody and a reference antibody, indicates that the subject antibody competes for binding to an antigen (e.g., CD 19) with the reference antibody and vice versa. A subject antibody cross-competes with a reference antibody if competition is observed whether the reference antibody is used as the first antibody and the subject antibody is used as the second antibody, or the subject antibody is used as the first antibody and the reference antibody is used as the second antibody in this assay. A skilled artisan can select the concentrations of the antibodies used in the competition assays based on the affinities of the antibodies for the antigen and the valency of the antibodies. In an exemplary assay, a first anti-CD19 antibody is immobilized on a solid surface, CD 19 antigen is bound to the first antibody, and binding of a second antiCD 19 antibody is assessed. If the second antibody does not generate a significant binding signal, the second antibody competes with the first antibody for binding CD 19. Exemplary assays are described in Cox et al., “Immunoassay Methods,” in ASSAY GUIDANCE MANUAL [INTERNET], Updated December 24, 2014 (www.ncbi.nlm.nih.gov / books / NBK92434 / ; accessed September 29, 2015); Silman et al. (2001) CYTOMETRY, 44: 30-37; and Finco et al. (2011) J. PHARM. BIOMED. ANAL., 54: 351-358. A CD19 antibody or an antigen-binding fragment of such an antibody (e.g., an scFv derived therefrom), can also be assessed in this assay.

[0085] As used herein, the term “effective amount” refers to the amount of a compound or agent (e.g., a compound or agent of the present disclosure) sufficient to effect beneficial or desired results. For example, “effective amount” can refer to the amount of an active agent (e.g., a CAR T cell) sufficient to effect beneficial or desired results. For example, an effective amount of an agent may be an amount sufficient to achieve one or more of the following: (1) treat an autoimmune disease, e.g., SLE, pemphigus vulgaris, myasthenia gravis, or myositis; (2) reduce or eliminate circulating B cells in a subject; (3) decrease autoantibody levels in a subject; (4) reduce or eliminate endogenous lymphocytes in a subject; (5) reduce proteinuria in a subject; (6) increase the amount or activity of one or more complement factors in a subject; or (7) treat a cancer. An effective amount can be administered in one or more administrations, applications or dosages and is not intended to belimited to a particular formulation or administration route. Any of the therapeutic compositions disclosed herein may be administered to a subject in need thereof in an effective amount.

[0086] As used herein, percent “identity” between a polypeptide sequence and a reference sequence is defined as the percentage of amino acid residues in the polypeptide sequence that are identical to the amino acid residues in the reference sequence, after aligning the sequences and introducing gaps, if necessary, to achieve the maximum percent sequence identity. Similarly, percent “identity” between a nucleic acid sequence and a reference sequence is defined as the percentage of nucleotides in the nucleic acid sequence that are identical to the nucleotides in the reference sequence, after aligning the sequences and introducing gaps, if necessary, to achieve the maximum percent sequence identity.Alignment for purposes of determining percent sequence identity (e.g., nucleic acid sequence identity or amino acid sequence identity) can be achieved in various ways that are within the skill in the art, for instance, using publicly available computer software such as BLAST, BLAST-2, ALIGN, MEGALIGN (DNASTAR), CLUSTALW, CLUSTAL OMEGA, or MUSCLE software. Those skilled in the art can determine appropriate parameters for aligning sequences, including any algorithms needed to achieve maximal alignment over the full length of the sequences being compared.

[0087] The use of the term “include,” “includes,” “including,” “have,” “has,” “having,” “contain,” “contains,” or “containing,” including grammatical equivalents thereof, should be understood generally as open-ended and non-limiting, for example, not excluding additional unrecited elements or steps, unless otherwise specifically stated or understood from the context.

[0088] As used herein, the term “isolated” when used in conjunction with a particular article (e.g. , polypeptide, nucleic acid, or cell) is understood to mean: (1) that the article has been separated or purified from other components (e.g. , other proteins, peptides, nucleic acids, cells, or cellular materials) and / or chemicals (e.g. , reagents used in manufacture); (2) that the article may be separated or purified from the environment in which it may exist in nature, for example, a tissue or fluid sample; or (3) that the article does not occur in nature. For example, a molecule that is removed from a cell that produces it, is “isolated”. A chemically synthesized molecule is “isolated.” As used herein, the term “isolated” can also refer to a molecule that is substantially free of other molecules of the same species. For example, a protein may be “isolated” from other proteins having different amino acidsequences. The purity or homogeneity of a desired article can be assayed using techniques well known in the art, including gel electrophoresis, high performance liquid chromatography, or mass spectrometry. Any of the polynucleotides, polypeptides, vectors, compounds, antibodies, or cells described herein may be isolated.

[0089] As used herein, the term “pharmaceutically acceptable” refers to those compounds, materials, compositions, and / or dosage forms which are, within the scope of sound medical judgment, suitable for use in contact with the tissues of human beings and animals without excessive toxicity, irritation, allergic response, or other problem or complication, commensurate with a reasonable benefit / risk ratio.

[0090] The term “pharmaceutically acceptable carrier” as used herein refers to buffers, carriers, and excipients suitable for use in contact with the tissues of human beings and animals without excessive toxicity, irritation, allergic response, or other problem or complication, commensurate with a reasonable benefit / risk ratio. Pharmaceutically acceptable carriers include any of the standard pharmaceutical carriers, such as a phosphate buffered saline solution, water, emulsions (e.g., such as an oil / water or water / oil emulsions), and various types of wetting agents. The compositions also can include stabilizers and preservatives. For examples of carriers, stabilizers, and adjuvants, see e.g., Adeboye Adejare, Remington: The Science and Practice of Pharmacy (23d ed. 2020).

[0091] The term “purified”, as used herein, means that an entity or substance is separated from one or more other entities or substances with which it was previously found before being purified. An entity or substance may be partially purified, substantially purified, or pure. A substance or entity such as a nucleic acid or polypeptide is considered pure when it is removed from substantially all other compounds or entities other than a solvent and any ions contained in the solvent, z.e., it constitutes at least about 90%, more preferably at least about 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or greater than 99% of the dry weight of the composition. A partially or substantially purified compound or entity such as a nucleic acid or polypeptide may be removed from at least 50%, at least 60%, at least 70%, or at least 80% by weight of the material with which it is naturally found, e.g., cellular material such as cellular proteins and / or nucleic acids. In certain embodiments, the purified nucleic acid or polypeptide constitutes at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, 99% or even more, by dry weight, of the total nucleic acid or polypeptide, respectively, in a composition. Methods for assessing purity are known in the art and include chromatographic methods, immunological methods, electrophoretic methods, etc. Any of thepolynucleotides, polypeptides, or cells described herein may be purified.

[0092] As used herein, the terms “subject” and “patient” refer to an organism to be treated by any of the methods and compositions described herein. Such organisms preferably include, but are not limited to, mammals (e.g., murines, simians, equines, bovines, porcines, canines, felines, and the like), and more preferably include humans.

[0093] As used herein, “treat”, “treating”, and “treatment” refer to the treatment of a disease, disorder, or symptom or manifestation of such in a subject, e.g. , in a human. This includes: (a) preventing a disease or disorder, (b) inhibiting the disease, disorder, etc., i.e., slowing or arresting its progress or development; and (c) relieving the disease, disorder, etc. , i.e., causing regression of the disease state. As used herein, “prevent”, “preventing” and “prevention” refer to causing a disease, disorder, or symptom or manifestation of such not to occur for at least a period of time in at least some subjects.II. CD19 Antibodies

[0094] Among other things, the disclosure provides antibodies and antigen-binding fragments thereof that bind CD19. CD19 is a transmembrane glycoprotein expressed on the surface of B lymphocytes from the earliest recognizable B-lineage cells during development to B-cell blasts. It is a Type I transmembrane protein, comprising two extracellular Ig-like C2 domains, a single transmembrane domain, and a conserved intracellular cytoplasmic domain. CD 19 primarily acts as a B cell co-receptor in conjunction with CD21 and CD81. CD 19 is expressed on auto-reactive B cells in autoimmune diseases, such as multiple sclerosis and rheumatoid arthritis. CD 19 is also expressed in many cancers, such as chronic lymphocytic leukemia, non-Hodgkin’s lymphoma, follicular lymphoma, acute lymphoblastic leukemia, multiple myeloma, and B-cell malignancies. The widespread expression of CD 19 on B cells has led to its adoption as a target for immunotherapies, including monoclonal antibody therapies and adoptive cell therapies.

[0095] In general, an antibody is a multimeric glycoprotein comprising at least two heavy (H) chains and two light (L) chains inter-connected by disulfide bonds. Each heavy chain is comprised of a heavy chain variable region (abbreviated herein as VH) and a heavy chain constant region. The heavy chain constant region comprises three domains, CHi, CH2 and CH3. Each light chain is comprised of a light chain variable region (abbreviated herein as VL) and a light chain constant region. The light chain constant region comprises one domain, CL. Each variable region contains three hypervariable regions known as complementaritydetermining regions (CDRs) flanked by four relatively conserved regions known as framework regions (FRs). The boundaries of the FRs and CDRs can be defined using any appropriate convention known in the art. The three CDRs, referred to as CDRi, CDR2, and CDR3, contribute to the antibody binding specificity.

[0096] As described herein, antibodies of the disclosure may comprise: (a) an immunoglobulin heavy chain variable region (VH) comprising the structure CDRHI -CDRH2- CDRHS and (b) an immunoglobulin light chain variable region (VL) comprising the structure CDRLI-CDRL2-CDRL3, wherein the VH and the VL together define an antigen binding site. In certain embodiments, the VH and VL each comprises one or more framework (FR) regions (e.g., 1, 2, 3, or 4 framework regions). The amino acid sequences of FR1, FR2, FR3, and FR4 all together constitute the “non-CDR region” or “non-extended CDR region” of a VH or VL as referred to herein. In certain embodiments, the VH comprises the structure FRHI- CDRHI-FRH2-CDRH2-FRH3-CDRH3-FRH4 and / or the VL comprises the structure FRLI-CDRLI- FRL2-CDRL2-FRL3-CDRL3-FRL4.

[0097] In certain embodiments, the CD 19 antibody or antigen-binding fragment thereof comprises a VH that comprises an amino acid sequence at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VH of an antibody disclosed in TABLE 1, 2, or 3, and a VL that comprises an amino acid sequence at least 80% (e.g., at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%) identical to the VL of the same antibody disclosed in TABLE 1, 2, or 3. In certain embodiments, the antibody or antigenbinding fragment thereof that binds CD19 comprises CDRHI, CDRH2, CDRH3 sequences present in the VH sequence of any one of SEQ ID NOs: 1, 4, 7, 10, 13, 16, 19, 22, 25, or 28, and CDRLI, CDRL2, and CDRL3 sequences present in the VL sequence of any one of SEQ ID NOs: 2, 5, 8, 11, 14, 17, 20, 23, 26, or 29, which can be identified using CDR determination algorithms known in the art, for example, the algorithms disclosed herein. In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD 19 comprises CDRHI, CDRH2, CDRH3, CDRLI, CDRL2, and CDRL3 sequences determined under Chothia (see, e.g., Chothia C & Lesk A M, (1987), J. MOL. BIOL. 196: 901-917), e.g., as indicated in TABLE 1, where the CDR sequences in each of the VH and VL sequences are underlined and then denoted individually. In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD 19 comprises CDRHI, CDRH2, CDRH3, CDRLI, CDRL2, and CDRL3sequences determined under Kabat (see Kabat et al.. (1991) Sequences of Proteins of Immunological Interest, NIH Publication No. 91-3242, Bethesda), e.g, as indicated in TABLE 2, where the CDR sequences in each of the VH and VL sequences are underlined and then denoted individually. In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD 19 comprises CDRm, CDRH2, CDRHS, CDRLI, CDRL2, and CDRL3 sequences determined under IMGT (see Lefranc, (1999) THE IMMUNOLOGIST, 7, 132-136), e.g., as indicated in TABLE 3, where the CDR sequences in each of the VH and VL sequences are underlined and then denoted individually. In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD 19 comprises CDRm, CDRm, CDRH3, CDRLI, CDRL2, and CDRL3 sequences determined under MacCallum (“Contact” numbering scheme; see, MacCallum R M et al., (1996) J. MOL. BIOL. 262: 732-745);Enhanced Chothia or AbM (see Abhinandan and Martin (2008) MOL. IMMUNOL., 45(14): 3832-9); the “AHo” numbering scheme (see Honegger and Pltickthun (2001) J. Mol. Biol., 309: 657-70), or any other CDR determination method known in the art, of the VH and VL sequences of an antibody disclosed in TABLE 1, 2, or 3. Identification of CDR and framework sequences is within the level of ordinary skill in the art, and it is understood that the boundaries between CDR and framework sequences may depend upon the definition or convention that is used (e.g., IMGT, Kabat, Chothia, etc.).

[0098] The Kabat-defined CDRs are based on sequence variability (Kabat et al., supra). The Chothia-defined CDRs instead are based on the location of the structural loops (Chothia & Lesk, supra). The AbM definition of the CDRs is a compromise between the Kabat and the Chothia numbering schemes and is used by Oxford Molecular’s AbM antibody modelling software (Martin et al. (1989) PROC. NATL. ACAD. SCI. USA, 86: 9268-72; Martin et al.(1991) METHODS ENZYMOL., 203: 121-153; Pedersen et al. (1992) IMMUNOMETHODS, 1: 126- 136; Rees et al. (1996) In STERNBERG M. J. E. (ED.), PROTEIN STRUCTURE PREDICTION.Oxford University Press, Oxford, 141-172). The contact-defined CDRs are based on an analysis of the available complex structures available in the Protein Databank (MacCallum et al. (1996) J. MOL. BIOL., 262: 732-745). The IMGT® (the international ImMunoGeneTics information system® (http: / / www.imgt.org)) -defined CDRs are based on the IMGT numbering for all immunoglobulin and T cell receptor V-REGIONs of all species (IMGT®, the international ImMunoGeneTics information system®; Lefranc et al. (1991) NUCLEIC ACIDS RES., 27(1): 209-12; Ruiz et al. (2000) NUCLEIC ACIDS RES., 28(1): 219-21; Lefranc (2001) NUCLEIC ACIDS RES., 29(1): 207-9; Lefranc (2003) NUCLEIC ACIDS RES., 31(1): 307-10; Lefranc et al. (2005) DEV. COMP. IMMUNOL., 29(3): 185-203; Kaas et al. (2007) BRIEFINGS IN FUNCTIONAL GENOMICS & PROTEOMICS, 6(4): 253-64). Alternatively, the CDRs can be defined according to Honegger’s numbering scheme that is based on structural alignment of an antibody’s three dimensional features (AHo; Honegger et al. (2001) J. MOL. BIOL., 309: 657-70). A comparison of the various numbering systems is described in Dondelinger et al. (2018) FRONT. IMMUNOL., 9: 2278.

[0099] In certain embodiments, the CD 19 antibody or antigen-binding fragment thereof comprises the CDRHI, CDRH2, CDRHS, CDRLI, CDRL2, and CDRL3 sequences of an antibody disclosed in TABLE 1, where the CDR sequences in each of the VH and VL sequences are underlined and identified according to the Chothia numbering scheme. In certain embodiments, the CD 19 antibody or antigen-binding fragment thereof comprises the VH and VL sequences of an antibody disclosed in TABLE 1.TABLE 1. Exemplary CD19 Antibodies (Chothia)

[0100] In certain embodiments, the CD 19 antibody or antigen-binding fragment thereof comprises the CDRHI, CDRH2, CDRHS, CDRLI, CDRL2, and CDRL3 sequences of an antibody disclosed in TABLE 2, where the CDR sequences in each of the VH and VL sequences are underlined and identified according to the Kabat numbering scheme. In certain embodiments, the CD 19 antibody or antigen-binding fragment thereof comprises the VH and VL sequences of an antibody disclosed in TABLE 2.TABLE 2. Exemplary CD19 Antibodies (Kabat)

[0101] In certain embodiments, the CD 19 antibody or antigen-binding fragment thereof comprises the CDRHI, CDRH2, CDRHS, CDRLI, CDRL2, and CDRL3 sequences of an antibody disclosed in TABLE 3, where the CDR sequences in each of the VH and VL sequences are underlined and identified according to the IMGT numbering scheme. In certain embodiments, the CD 19 antibody or antigen-binding fragment thereof comprises the VH and VL sequences of an antibody disclosed in TABLE 3.TABLE 3. Exemplary CD19 Antibodies (IMGT)

[0102] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD 19 comprises heavy chain CDRs CDRHI, CDRH2, and CDRHS that are present in a heavy chain variable domain (VH) comprising the amino acid sequence set forth in SEQ ID NO: 1, and / or the comprises light chain CDRs CDRLI, CDRL2, and CDRL3 that are present in a light chain variable domain (VL) comprising the amino acid sequence set forth in SEQ ID NO: 2. In certain embodiments, the CDRs are Chothia CDRs. In certain embodiments the CDRs are Kabat CDRs. In certain embodiments, the CDRs are IMGT CDRs.

[0103] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD 19 comprises heavy chain CDRs CDRHI, CDRH2, and CDRH3 that are present in a heavy chain variable domain (VH) comprising the amino acid sequence set forth in SEQ ID NO: 4, and / or the comprises light chain CDRs CDRLI, CDRL2, and CDRL3 that are present in a light chain variable domain (VL) comprising the amino acid sequence set forth in SEQ ID NO: 5. In certain embodiments, the CDRs are Chothia CDRs. In certain embodiments the CDRs are Kabat CDRs. In certain embodiments, the CDRs are IMGT CDRs.

[0104] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD 19 comprises heavy chain CDRs CDRHI, CDRH2, and CDRH3 that are present in a heavy chain variable domain (VH) comprising the amino acid sequence set forth in SEQ ID NO: 7, and / or the comprises light chain CDRs CDRLI, CDRL2, and CDRL3 that are present in a light chain variable domain (VL) comprising the amino acid sequence set forth in SEQ ID NO: 8.In certain embodiments, the CDRs are Chothia CD Rs. In certain embodiments the CDRs are Kabat CDRs. In certain embodiments, the CDRs are IMGT CDRs.

[0105] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD 19 comprises heavy chain CDRs CDRHI, CDRH2, and CDRHS that are present in a heavy chain variable domain (VH) comprising the amino acid sequence set forth in SEQ ID NO: 10, and / or the comprises light chain CDRs CDRLI, CDRL2, and CDRL3 that are present in a light chain variable domain (VL) comprising the amino acid sequence set forth in SEQ ID NO: 11. In certain embodiments, the CDRs are Chothia CDRs. In certain embodiments the CDRs are Kabat CDRs. In certain embodiments, the CDRs are IMGT CDRs.

[0106] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD 19 comprises heavy chain CDRs CDRHI, CDRH2, and CDRH3 that are present in a heavy chain variable domain (VH) comprising the amino acid sequence set forth in SEQ ID NO: 13, and / or the comprises light chain CDRs CDRLI, CDRL2, and CDRL3 that are present in a light chain variable domain (VL) comprising the amino acid sequence set forth in SEQ ID NO: 14. In certain embodiments, the CDRs are Chothia CDRs. In certain embodiments the CDRs are Kabat CDRs. In certain embodiments, the CDRs are IMGT CDRs.

[0107] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD 19 comprises heavy chain CDRs CDRHI, CDRH2, and CDRH3 that are present in a heavy chain variable domain (VH) comprising the amino acid sequence set forth in SEQ ID NO: 16, and / or the comprises light chain CDRs CDRLI, CDRL2, and CDRL3 that are present in a light chain variable domain (VL) comprising the amino acid sequence set forth in SEQ ID NO: 17. In certain embodiments, the CDRs are Chothia CDRs. In certain embodiments the CDRs are Kabat CDRs. In certain embodiments, the CDRs are IMGT CDRs.

[0108] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD 19 comprises heavy chain CDRs CDRHI, CDRH2, and CDRH3 that are present in a heavy chain variable domain (VH) comprising the amino acid sequence set forth in SEQ ID NO: 19, and / or the comprises light chain CDRs CDRLI, CDRL2, and CDRL3 that are present in a light chain variable domain (VL) comprising the amino acid sequence set forth in SEQ ID NO: 20. In certain embodiments, the CDRs are Chothia CDRs. In certain embodiments the CDRs are Kabat CDRs. In certain embodiments, the CDRs are IMGT CDRs.

[0109] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD 19 comprises heavy chain CDRs CDRHI, CDRH2, and CDRH3 that are present in a heavychain variable domain (VH) comprising the amino acid sequence set forth in SEQ ID NO: 22, and / or the comprises light chain CDRs CDRLI, CDRL2, and CDRLS that are present in a light chain variable domain (VL) comprising the amino acid sequence set forth in SEQ ID NO: 23. In certain embodiments, the CDRs are Chothia CDRs. In certain embodiments the CDRs are Kabat CDRs. In certain embodiments, the CDRs are IMGT CDRs.

[0110] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD 19 comprises heavy chain CDRs CDRHI, CDRH2, and CDRHS that are present in a heavy chain variable domain (VH) comprising the amino acid sequence set forth in SEQ ID NO: 25, and / or the comprises light chain CDRs CDRLI, CDRL2, and CDRL3 that are present in a light chain variable domain (VL) comprising the amino acid sequence set forth in SEQ ID NO: 26. In certain embodiments, the CDRs are Chothia CDRs. In certain embodiments the CDRs are Kabat CDRs. In certain embodiments, the CDRs are IMGT CDRs.

[0111] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD 19 comprises heavy chain CDRs CDRHI, CDRH2, and CDRH3 that are present in a heavy chain variable domain (VH) comprising the amino acid sequence set forth in SEQ ID NO: 28, and / or the comprises light chain CDRs CDRLI, CDRL2, and CDRL3 that are present in a light chain variable domain (VL) comprising the amino acid sequence set forth in SEQ ID NO: 29. In certain embodiments, the CDRs are Chothia CDRs. In certain embodiments the CDRs are Kabat CDRs. In certain embodiments, the CDRs are IMGT CDRs.

[0112] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRH3 sequences, wherein the CDRHI comprises the amino acid sequence of SEQ ID NO: 31, 82, or 98; the CDRH2 comprises the amino acid sequence of SEQ ID NO: 32, 83, or 99; and the CDRH3 comprises the amino acid sequence of SEQ ID NO: 33 or 100; and / or the antibody or antigen-binding fragment thereof that binds CD 19 comprises a VL comprising CDRLI, CDRL2, and CDRL3 sequences, wherein the CDRLI comprises the amino acid sequence of SEQ ID NO: 34 or 101; the CDRL2 comprises the amino acid sequence of SEQ ID NO: 35 or AAS; and the CDRLS comprises the amino acid sequence of SEQ ID NO: 36.

[0113] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRH3 sequences, wherein the CDRHI comprises the amino acid sequence of SEQ ID NO: 37, 84, or 103; the CDRH2 comprises the amino acid sequence of SEQ ID NO: 38, 85, or 104; and the CDRH3 comprisesthe amino acid sequence of SEQ ID NO: 39 or 105; and / or the antibody or antigen-binding fragment thereof that binds CD 19 comprises a VL comprising CDRLI, CDRL2, and CDRLS sequences, wherein the CDRLI comprises the amino acid sequence of SEQ ID NO: 40 or 106; the CDRL2 comprises the amino acid sequence of SEQ ID NO: 41 or DAS; and the CDRLS comprises the amino acid sequence of SEQ ID NO: 42.

[0114] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRH3 sequences, wherein the CDRHI comprises the amino acid sequence of SEQ ID NO: 43, 86, or 108; the CDRH2 comprises the amino acid sequence of SEQ ID NO: 44, 87, or 109; and the CDRH3 comprises the amino acid sequence of SEQ ID NO: 45 or 110; and / or the antibody or antigen-binding fragment thereof that binds CD 19 comprises a VL comprising CDRLI, CDRL2, and CDRLS sequences, wherein the CDRLI comprises the amino acid sequence of SEQ ID NO: 46 or 111; the CDRL2 comprises the amino acid sequence of SEQ ID NO: 47 or DAS; and the CDRLS comprises the amino acid sequence of SEQ ID NO: 48.

[0115] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRH3 sequences, wherein the CDRHI comprises the amino acid sequence of SEQ ID NO: 31, 82, or 98; the CDRH2 comprises the amino acid sequence of SEQ ID NO: 49, 88, or 112; and the CDRH3 comprises the amino acid sequence of SEQ ID NO: 50 or 113; and / or the antibody or antigen-binding fragment thereof that binds CD 19 comprises a VL comprising CDRLI, CDRL2, and CDRLS sequences, wherein the CDRLI comprises the amino acid sequence of SEQ ID NO: 51 or 114; the CDRL2 comprises the amino acid sequence of SEQ ID NO: 52 or LGS; and the CDRLS comprises the amino acid sequence of SEQ ID NO: 53.

[0116] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRH3 sequences, wherein the CDRHI comprises the amino acid sequence of SEQ ID NO: 31, 82, or 98; the CDRH2 comprises the amino acid sequence of SEQ ID NO: 54, 89, or 116; and the CDRH3 comprises the amino acid sequence of SEQ ID NO: 55 or 117; and / or the antibody or antigen-binding fragment thereof that binds CD 19 comprises a VL comprising CDRLI, CDRL2, and CDRLS sequences, wherein the CDRLI comprises the amino acid sequence of SEQ ID NO: 56 or 118; the CDRL2 comprises the amino acid sequence of SEQ ID NO: 57 or GIS; and the CDRLS comprises the amino acid sequence of SEQ ID NO: 58.

[0117] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRHS sequences, wherein the CDRHI comprises the amino acid sequence of SEQ ID NO: 31, 82, or 98; the CDRH2 comprises the amino acid sequence of SEQ ID NO: 32, 90, or 99; and the CDRm comprises the amino acid sequence of SEQ ID NO: 78 or 120; and / or the antibody or antigen-binding fragment thereof that binds CD 19 comprises a VL comprising CDRLI, CDRL2, and CDRL3 sequences, wherein the CDRLI comprises the amino acid sequence of SEQ ID NO: 79 or 121; the CDRL2 comprises the amino acid sequence of SEQ ID NO: 80 or GAS; and the CDRL3 comprises the amino acid sequence of SEQ ID NO: 81.

[0118] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRm sequences, wherein the CDRHI comprises the amino acid sequence of SEQ ID NO: 43, 91, or 123; the CDRH2 comprises the amino acid sequence of SEQ ID NO: 59, 92, or 124; and the CDRm comprises the amino acid sequence of SEQ ID NO: 60 or 125; and / or the antibody or antigen-binding fragment thereof that binds CD 19 comprises a VL comprising CDRLI, CDRL2, and CDRL3 sequences, wherein the CDRLI comprises the amino acid sequence of SEQ ID NO: 61 or 126; the CDRL2 comprises the amino acid sequence of SEQ ID NO: 62 or LGS; and the CDRL3 comprises the amino acid sequence of SEQ ID NO: 63.

[0119] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRm, and CDRm sequences, wherein the CDRHI comprises the amino acid sequence of SEQ ID NO: 64, 93, or 127; the CDRm comprises the amino acid sequence of SEQ ID NO: 32, 90, or 99; and the CDRm comprises the amino acid sequence of SEQ ID NO: 65 or 128; and / or the antibody or antigen-binding fragment thereof that binds CD 19 comprises a VL comprising CDRLI, CDRL2, and CDRL3 sequences, wherein the CDRLI comprises the amino acid sequence of SEQ ID NO: 34 or 101; the CDRL2 comprises the amino acid sequence of SEQ ID NO: 47 or DAS; and the CDRL3 comprises the amino acid sequence of SEQ ID NO: 66.

[0120] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRm, and CDRm sequences, wherein the CDRHI comprises the amino acid sequence of SEQ ID NO: 67, 94, or 129; the CDRm comprises the amino acid sequence of SEQ ID NO: 68, 95, or 130; and the CDRm comprises the amino acid sequence of SEQ ID NO: 69 or 131; and / or the antibody or antigen-binding fragment thereof that binds CD 19 comprises a VL comprising CDRLI, CDRL2, and CDRL3sequences, wherein the CDRLI comprises the amino acid sequence of SEQ ID NO: 70 or 132; the CDRL2 comprises the amino acid sequence of SEQ ID NO: 71 or DAS; and the CDRLS comprises the amino acid sequence of SEQ ID NO: 72.

[0121] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRm sequences, wherein the CDRHI comprises the amino acid sequence of SEQ ID NO: 73, 96, or 133; the CDRH2 comprises the amino acid sequence of SEQ ID NO: 32, 97, or 134; and the CDRH3 comprises the amino acid sequence of SEQ ID NO: 74 or 135; and / or the antibody or antigen-binding fragment thereof that binds CD 19 comprises a VL comprising CDRLI, CDRL2, and CDRL3 sequences, wherein the CDRLI comprises the amino acid sequence of SEQ ID NO: 75 or 136; the CDRL2 comprises the amino acid sequence of SEQ ID NO: 76 or AAS; and the CDRLS comprises the amino acid sequence of SEQ ID NO: 77.

[0122] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRH3 sequences identified by the Chothia numbering scheme and set forth in SEQ ID NOs: 31, 32, and 33, respectively, wherein CDRHI, CDRH2, and CDRH3 sequences are interposed between immunoglobulin FR sequences; and / or a VL comprising CDRLI, CDRL2, and CDRLS sequences identified by the Chothia numbering scheme and set forth in SEQ ID NOs: 34, 35, and 36, respectively, wherein CDRLI, CDRL2, and CDRLS sequences are interposed between immunoglobulin FR sequences. In certain embodiments, the CDRHI, CDRH2, and CDRH3 sequences and / or the CDRLI, CDRL2, and CDRLS sequences are interposed between human or humanized immunoglobulin FR sequences.

[0123] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRH3 sequences identified by the Chothia numbering scheme and set forth in SEQ ID NOs: 37, 38, and 39, respectively, wherein CDRHI, CDRm, and CDRH3 sequences are interposed between immunoglobulin FR sequences; and / or a VL comprising CDRLI, CDRL2, and CDRLS sequences identified by the Chothia numbering scheme and set forth in SEQ ID NOs: 40, 41, and 42, respectively, wherein CDRLI, CDRL2, and CDRLS sequences are interposed between immunoglobulin FR sequences. In certain embodiments, the CDRHI, CDRH2, and CDRm sequences and / or the CDRLI, CDRL2, and CDRLS sequences are interposed between human or humanized immunoglobulin FR sequences.

[0124] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRHS sequences identified by the Chothia numbering scheme and set forth in SEQ ID NOs: 43, 44, and 45, respectively, wherein CDRHI, CDRm, and CDRHS sequences are interposed between immunoglobulin FR sequences; and / or a VL comprising CDRLI, CDRL2, and CDRL3 sequences identified by the Chothia numbering scheme and set forth in SEQ ID NOs: 46, 47, and 48, respectively, wherein CDRLI, CDRL2, and CDRL3 sequences are interposed between immunoglobulin FR sequences. In certain embodiments, the CDRHI, CDRH2, and CDRm sequences and / or the CDRLI, CDRL2, and CDRL3 sequences are interposed between human or humanized immunoglobulin FR sequences.

[0125] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRm sequences identified by the Chothia numbering scheme and set forth in SEQ ID NOs: 31, 49, and 50, respectively, wherein CDRHI, CDRm, and CDRm sequences are interposed between immunoglobulin FR sequences; and / or a VL comprising CDRLI, CDRL2, and CDRL3 sequences identified by the Chothia numbering scheme and set forth in SEQ ID NOs: 51, 52, and 53, respectively, wherein CDRLI, CDRL2, and CDRL3 sequences are interposed between immunoglobulin FR sequences. In certain embodiments, the CDRHI, CDRm, and CDRm sequences and / or the CDRLI, CDRL2, and CDRL3 sequences are interposed between human or humanized immunoglobulin FR sequences.

[0126] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRm, and CDRm sequences identified by the Chothia numbering scheme and set forth in SEQ ID NOs: 31, 54, and 55, respectively, wherein CDRHI, CDRm, and CDRm sequences are interposed between immunoglobulin FR sequences; and / or a VL comprising CDRLI, CDRL2, and CDRL3 sequences identified by the Chothia numbering scheme and set forth in SEQ ID NOs: 56, 57, and 58, respectively, wherein CDRLI, CDRL2, and CDRL3 sequences are interposed between immunoglobulin FR sequences. In certain embodiments, the CDRHI, CDRm, and CDRm sequences and / or the CDRLI, CDRL2, and CDRL3 sequences are interposed between human or humanized immunoglobulin FR sequences.

[0127] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRm, and CDRm sequences identified by the Chothia numbering scheme and set forth in SEQ ID NOs: 31, 32, and 78, respectively,wherein CDRHI, CDRm, and CDRH3 sequences are interposed between immunoglobulin FR sequences; and / or a VL comprising CDRLI, CDRL2, and CDRLS sequences identified by the Chothia numbering scheme and set forth in SEQ ID NOs: 79, 80, and 81, respectively, wherein CDRLI, CDRL2, and CDRL3 sequences are interposed between immunoglobulin FR sequences. In certain embodiments, the CDRHI, CDRH2, and CDRH3 sequences and / or the CDRLI, CDRL2, and CDRL3 sequences are interposed between human or humanized immunoglobulin FR sequences.

[0128] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRH3 sequences identified by the Chothia numbering scheme and set forth in SEQ ID NOs: 43, 59, and 60, respectively, wherein CDRHI, CDRH2, and CDRH3 sequences are interposed between immunoglobulin FR sequences; and / or a VL comprising CDRLI, CDRL2, and CDRL3 sequences identified by the Chothia numbering scheme and set forth in SEQ ID NOs: 61, 62, and 63, respectively, wherein CDRLI, CDRL2, and CDRL3 sequences are interposed between immunoglobulin FR sequences. In certain embodiments, the CDRHI, CDRH2, and CDRH3 sequences and / or the CDRLI, CDRL2, and CDRL3 sequences are interposed between human or humanized immunoglobulin FR sequences.

[0129] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRH3 sequences identified by the Chothia numbering scheme and set forth in SEQ ID NOs: 64, 32, and 65, respectively, wherein CDRHI, CDRm, and CDRH3 sequences are interposed between immunoglobulin FR sequences; and / or a VL comprising CDRLI, CDRL2, and CDRL3 sequences identified by the Chothia numbering scheme and set forth in SEQ ID NOs: 34, 47, and 66, respectively, wherein CDRLI, CDRL2, and CDRL3 sequences are interposed between immunoglobulin FR sequences. In certain embodiments, the CDRHI, CDRH2, and CDRm sequences and / or the CDRLI, CDRL2, and CDRL3 sequences are interposed between human or humanized immunoglobulin FR sequences.

[0130] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRm sequences identified by the Chothia numbering scheme and set forth in SEQ ID NOs: 67, 68, and 69, respectively, wherein CDRHI, CDRm, and CDRm sequences are interposed between immunoglobulin FR sequences; and / or a VL comprising CDRLI, CDRL2, and CDRL3 sequences identified by the Chothia numbering scheme and set forth in SEQ ID NOs: 70, 71, and 72, respectively,wherein CDRLI, CDRL2, and CDRLS sequences are interposed between immunoglobulin FR sequences. In certain embodiments, the CDRHI, CDRH2, and CDRHS sequences and / or the CDRLI, CDRL2, and CDRL3 sequences are interposed between human or humanized immunoglobulin FR sequences.

[0131] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRH3 sequences identified by the Chothia numbering scheme and set forth in SEQ ID NOs: 73, 32, and 74, respectively, wherein CDRHI, CDRH2, and CDRH3 sequences are interposed between immunoglobulin FR sequences; and / or a VL comprising CDRLI, CDRL2, and CDRL3 sequences identified by the Chothia numbering scheme and set forth in SEQ ID NOs: 75, 76, and 77, respectively, wherein CDRLI, CDRL2, and CDRL3 sequences are interposed between immunoglobulin FR sequences. In certain embodiments, the CDRHI, CDRH2, and CDRH3 sequences and / or the CDRLI, CDRL2, and CDRL3 sequences are interposed between human or humanized immunoglobulin FR sequences.

[0132] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRH3 sequences identified by the Kabat numbering scheme and set forth in SEQ ID NOs: 82, 83, and 33, respectively, wherein CDRHI, CDRH2, and CDRH3 sequences are interposed between immunoglobulin FR sequences; and / or a VL comprising CDRLI, CDRL2, and CDRL3 sequences identified by the Kabat numbering scheme and set forth in SEQ ID NOs: 34, 35, and 36, respectively, wherein CDRLI, CDRL2, and CDRL3 sequences are interposed between immunoglobulin FR sequences. In certain embodiments, the CDRHI, CDRH2, and CDRH3 sequences and / or the CDRLI, CDRL2, and CDRL3 sequences are interposed between human or humanized immunoglobulin FR sequences.

[0133] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRH3 sequences identified by the Kabat numbering scheme and set forth in SEQ ID NOs: 84, 85, and 39, respectively, wherein CDRHI, CDRH2, and CDRH3 sequences are interposed between immunoglobulin FR sequences; and / or a VL comprising CDRLI, CDRL2, and CDRL3 sequences identified by the Kabat numbering scheme and set forth in SEQ ID NOs: 40, 41, and 42, respectively, wherein CDRLI, CDRL2, and CDRL3 sequences are interposed between immunoglobulin FR sequences. In certain embodiments, the CDRHI, CDRH2, and CDRH3 sequences and / or theCDRLI, CDRL2, and CDRLS sequences are interposed between human or humanized immunoglobulin FR sequences.

[0134] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRm, CDRH2, and CDRH3 sequences identified by the Kabat numbering scheme and set forth in SEQ ID NOs: 86, 87, and 45, respectively, wherein CDRm, CDRH2, and CDRm sequences are interposed between immunoglobulin FR sequences; and / or a VL comprising CDRLI, CDRL2, and CDRL3 sequences identified by the Kabat numbering scheme and set forth in SEQ ID NOs: 46, 47, and 48, respectively, wherein CDRLI, CDRL2, and CDRL3 sequences are interposed between immunoglobulin FR sequences. In certain embodiments, the CDRm, CDRm, and CDRm sequences and / or the CDRLI, CDRL2, and CDRL3 sequences are interposed between human or humanized immunoglobulin FR sequences.

[0135] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRm, CDRm, and CDRm sequences identified by the Kabat numbering scheme and set forth in SEQ ID NOs: 82, 88, and 50, respectively, wherein CDRm, CDRm, and CDRm sequences are interposed between immunoglobulin FR sequences; and / or a VL comprising CDRLI, CDRL2, and CDRL3 sequences identified by the Kabat numbering scheme and set forth in SEQ ID NOs: 51, 52, and 53, respectively, wherein CDRLI, CDRL2, and CDRL3 sequences are interposed between immunoglobulin FR sequences. In certain embodiments, the CDRm, CDRm, and CDRm sequences and / or the CDRLI, CDRL2, and CDRL3 sequences are interposed between human or humanized immunoglobulin FR sequences.

[0136] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRm, CDRm, and CDRm sequences identified by the Kabat numbering scheme and set forth in SEQ ID NOs: 82, 89, and 55, respectively, wherein CDRm, CDRm, and CDRm sequences are interposed between immunoglobulin FR sequences; and / or a VL comprising CDRLI, CDRL2, and CDRL3 sequences identified by the Kabat numbering scheme and set forth in SEQ ID NOs: 56, 57, and 58, respectively, wherein CDRLI, CDRL2, and CDRL3 sequences are interposed between immunoglobulin FR sequences. In certain embodiments, the CDRm, CDRm, and CDRm sequences and / or the CDRLI, CDRL2, and CDRL3 sequences are interposed between human or humanized immunoglobulin FR sequences.

[0137] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRHS sequences identified by the Kabat numbering scheme and set forth in SEQ ID NOs: 82, 90, and 78, respectively, wherein CDRHI, CDRH2, and CDRHS sequences are interposed between immunoglobulin FR sequences; and / or a VL comprising CDRLI, CDRL2, and CDRL3 sequences identified by the Kabat numbering scheme and set forth in SEQ ID NOs: 79, 80, and 81, respectively, wherein CDRLI, CDRL2, and CDRL3 sequences are interposed between immunoglobulin FR sequences. In certain embodiments, the CDRHI, CDRH2, and CDRHS sequences and / or the CDRLI, CDRL2, and CDRL3 sequences are interposed between human or humanized immunoglobulin FR sequences.

[0138] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRHS sequences identified by the Kabat numbering scheme and set forth in SEQ ID NOs: 91, 92, and 60, respectively, wherein CDRHI, CDRH2, and CDRHS sequences are interposed between immunoglobulin FR sequences; and / or a VL comprising CDRLI, CDRL2, and CDRL3 sequences identified by the Kabat numbering scheme and set forth in SEQ ID NOs: 61, 62, and 63, respectively, wherein CDRLI, CDRL2, and CDRL3 sequences are interposed between immunoglobulin FR sequences. In certain embodiments, the CDRHI, CDRH2, and CDRHS sequences and / or the CDRLI, CDRL2, and CDRL3 sequences are interposed between human or humanized immunoglobulin FR sequences.

[0139] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRHS sequences identified by the Kabat numbering scheme and set forth in SEQ ID NOs: 93, 90, and 65, respectively, wherein CDRHI, CDRH2, and CDRHS sequences are interposed between immunoglobulin FR sequences; and / or a VL comprising CDRLI, CDRL2, and CDRL3 sequences identified by the Kabat numbering scheme and set forth in SEQ ID NOs: 34, 47, and 66, respectively, wherein CDRLI, CDRL2, and CDRL3 sequences are interposed between immunoglobulin FR sequences. In certain embodiments, the CDRHI, CDRH2, and CDRHS sequences and / or the CDRLI, CDRL2, and CDRL3 sequences are interposed between human or humanized immunoglobulin FR sequences.

[0140] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRHS sequences identified by the Kabat numbering scheme and set forth in SEQ ID NOs: 94, 95, and 69, respectively, whereinCDRHI, CDRH2, and CDRHS sequences are interposed between immunoglobulin FR sequences; and / or a VL comprising CDRLI, CDRL2, and CDRLS sequences identified by the Kabat numbering scheme and set forth in SEQ ID NOs: 70, 71, and 72, respectively, wherein CDRLI, CDRL2, and CDRL3 sequences are interposed between immunoglobulin FR sequences. In certain embodiments, the CDRHI, CDRH2, and CDRH3 sequences and / or the CDRLI, CDRL2, and CDRL3 sequences are interposed between human or humanized immunoglobulin FR sequences.

[0141] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRH3 sequences identified by the Kabat numbering scheme and set forth in SEQ ID NOs: 96, 97, and 74, respectively, wherein CDRHI, CDRH2, and CDRH3 sequences are interposed between immunoglobulin FR sequences; and / or a VL comprising CDRLI, CDRL2, and CDRL3 sequences identified by the Kabat numbering scheme and set forth in SEQ ID NOs: 75, 76, and 77, respectively, wherein CDRLI, CDRL2, and CDRL3 sequences are interposed between immunoglobulin FR sequences. In certain embodiments, the CDRHI, CDRH2, and CDRH3 sequences and / or the CDRLI, CDRL2, and CDRL3 sequences are interposed between human or humanized immunoglobulin FR sequences.

[0142] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRH3 sequences identified by the IMGT numbering scheme and set forth in SEQ ID NOs: 98, 99, and 100, respectively, wherein CDRHI, CDRm, and CDRH3 sequences are interposed between immunoglobulin FR sequences; and / or a VL comprising CDRLI, CDRL2, and CDRL3 sequences identified by the IMGT numbering scheme and set forth in SEQ ID NO: 101, AAS, and SEQ ID NO: 36, respectively, wherein CDRLI, CDRL2, and CDRL3 sequences are interposed between immunoglobulin FR sequences. In certain embodiments, the CDRHI, CDRH2, and CD RIB sequences and / or the CDRLI, CDRL2, and CDRL3 sequences are interposed between human or humanized immunoglobulin FR sequences.

[0143] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRm sequences identified by the IMGT numbering scheme and set forth in SEQ ID NOs: 103, 104, and 105, respectively, wherein CDRHI, CDRm, and CDRm sequences are interposed between immunoglobulin FR sequences; and / or a VL comprising CDRLI, CDRL2, and CDRL3 sequences identified by the IMGT numbering scheme and set forth in SEQ ID NO: 106, DAS, and SEQ ID NO: 42,respectively, wherein CDRLI, CDRL2, and CDRLS sequences are interposed between immunoglobulin FR sequences. In certain embodiments, the CDRHI, CDRH2, and CDRH3 sequences and / or the CDRLI, CDRL2, and CDRLS sequences are interposed between human or humanized immunoglobulin FR sequences.

[0144] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRH3 sequences identified by the IMGT numbering scheme and set forth in SEQ ID NOs: 108, 109, and 110, respectively, wherein CDRHI, CDRH2, and CDRH3 sequences are interposed between immunoglobulin FR sequences; and / or a VL comprising CDRLI, CDRL2, and CDRLS sequences identified by the IMGT numbering scheme and set forth in SEQ ID NO: 111, DAS, and SEQ ID NO: 48, respectively, wherein CDRLI, CDRL2, and CDRLS sequences are interposed between immunoglobulin FR sequences. In certain embodiments, the CDRHI, CDRH2, and CD RIB sequences and / or the CDRLI, CDRL2, and CDRLS sequences are interposed between human or humanized immunoglobulin FR sequences.

[0145] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRH3 sequences identified by the IMGT numbering scheme and set forth in SEQ ID NOs: 98, 112, and 113, respectively, wherein CDRHI, CDRm, and CDRH3 sequences are interposed between immunoglobulin FR sequences; and / or a VL comprising CDRLI, CDRL2, and CDRLS sequences identified by the IMGT numbering scheme and set forth in SEQ ID NO: 114, LGS, and SEQ ID NO: 53, respectively, wherein CDRLI, CDRL2, and CDRLS sequences are interposed between immunoglobulin FR sequences. In certain embodiments, the CDRHI, CDRH2, and CD RIB sequences and / or the CDRLI, CDRL2, and CDRLS sequences are interposed between human or humanized immunoglobulin FR sequences.

[0146] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRm sequences identified by the IMGT numbering scheme and set forth in SEQ ID NOs: 98, 116, and 117, respectively, wherein CDRHI, CDRm, and CDRm sequences are interposed between immunoglobulin FR sequences; and / or a VL comprising CDRLI, CDRL2, and CDRLS sequences identified by the IMGT numbering scheme and set forth in SEQ ID NO: 118, GIS, and SEQ ID NO: 58, respectively, wherein CDRLI, CDRL2, and CDRLS sequences are interposed between immunoglobulin FR sequences. In certain embodiments, the CDRHI, CDRm, and CDRmsequences and / or the CDRLI, CDRL2, and CDRLS sequences are interposed between human or humanized immunoglobulin FR sequences.

[0147] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRH3 sequences identified by the IMGT numbering scheme and set forth in SEQ ID NOs: 98, 99, and 120, respectively, wherein CDRHI, CDRm, and CDRH3 sequences are interposed between immunoglobulin FR sequences; and / or a VL comprising CDRLI, CDRL2, and CDRL3 sequences identified by the IMGT numbering scheme and set forth in SEQ ID NO: 121, GAS, and SEQ ID NO: 81, respectively, wherein CDRLI, CDRL2, and CDRL3 sequences are interposed between immunoglobulin FR sequences. In certain embodiments, the CDRHI, CDRH2, and CD RIB sequences and / or the CDRLI, CDRL2, and CDRL3 sequences are interposed between human or humanized immunoglobulin FR sequences.

[0148] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRm sequences identified by the IMGT numbering scheme and set forth in SEQ ID NOs: 123, 124, and 125, respectively, wherein CDRHI, CDRm, and CDRm sequences are interposed between immunoglobulin FR sequences; and / or a VL comprising CDRLI, CDRL2, and CDRL3 sequences identified by the IMGT numbering scheme and set forth in SEQ ID NO: 126, LGS, and SEQ ID NO: 63, respectively, wherein CDRLI, CDRL2, and CDRL3 sequences are interposed between immunoglobulin FR sequences. In certain embodiments, the CDRHI, CDRm, and CDRm sequences and / or the CDRLI, CDRL2, and CDRL3 sequences are interposed between human or humanized immunoglobulin FR sequences.

[0149] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRm, and CDRm sequences identified by the IMGT numbering scheme and set forth in SEQ ID NOs: 127, 99, and 128, respectively, wherein CDRHI, CDRm, and CDRm sequences are interposed between immunoglobulin FR sequences; and / or a VL comprising CDRLI, CDRL2, and CDRL3 sequences identified by the IMGT numbering scheme and set forth in SEQ ID NO: 101, DAS, and SEQ ID NO: 66, respectively, wherein CDRLI, CDRL2, and CDRL3 sequences are interposed between immunoglobulin FR sequences. In certain embodiments, the CDRHI, CDRm, and CDRm sequences and / or the CDRLI, CDRL2, and CDRL3 sequences are interposed between human or humanized immunoglobulin FR sequences.

[0150] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRHS sequences identified by the IMGT numbering scheme and set forth in SEQ ID NOs: 129, 130, and 131, respectively, wherein CDRHI, CDRm, and CDRHS sequences are interposed between immunoglobulin FR sequences; and / or a VL comprising CDRLI, CDRL2, and CDRL3 sequences identified by the IMGT numbering scheme and set forth in SEQ ID NO: 132, DAS, and SEQ ID NO: 72, respectively, wherein CDRLI, CDRL2, and CDRL3 sequences are interposed between immunoglobulin FR sequences. In certain embodiments, the CDRHI, CDRH2, and CD RIB sequences and / or the CDRLI, CDRL2, and CDRL3 sequences are interposed between human or humanized immunoglobulin FR sequences.

[0151] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising CDRHI, CDRH2, and CDRm sequences identified by the IMGT numbering scheme and set forth in SEQ ID NOs: 133, 134, and 135, respectively, wherein CDRHI, CDRm, and CDRm sequences are interposed between immunoglobulin FR sequences; and / or a VL comprising CDRLI, CDRL2, and CDRL3 sequences identified by the IMGT numbering scheme and set forth in SEQ ID NO: 136, AAS, and SEQ ID NO: 77, respectively, wherein CDRLI, CDRL2, and CDRL3 sequences are interposed between immunoglobulin FR sequences. In certain embodiments, the CDRHI, CDRm, and CDRm sequences and / or the CDRLI, CDRL2, and CDRL3 sequences are interposed between human or humanized immunoglobulin FR sequences.

[0152] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising the amino acid sequence of SEQ ID NO: 1, 4, 7, 10, 13, 16, 19, 22, 25, or 28. In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD 19 comprises a VL comprising the amino acid sequence of SEQ ID NO: 2, 5, 8, 11, 14, 17, 20, 23, 26, or 29.

[0153] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising the amino acid sequence of SEQ ID NO: 1, and / or a VL comprising the amino acid sequence of SEQ ID NO: 2.

[0154] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising the amino acid sequence of SEQ ID NO: 4, and / or a VL comprising the amino acid sequence of SEQ ID NO: 5.

[0155] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising the amino acid sequence of SEQ ID NO: 7, and / or a VL comprising the amino acid sequence of SEQ ID NO: 8.

[0156] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising the amino acid sequence of SEQ ID NO: 10, and / or a VL comprising the amino acid sequence of SEQ ID NO: 11.

[0157] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising the amino acid sequence of SEQ ID NO: 13, and / or a VL comprising the amino acid sequence of SEQ ID NO: 14.

[0158] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising the amino acid sequence of SEQ ID NO: 16, and / or a VL comprising the amino acid sequence of SEQ ID NO: 17.

[0159] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising the amino acid sequence of SEQ ID NO: 19, and / or a VL comprising the amino acid sequence of SEQ ID NO: 20.

[0160] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising the amino acid sequence of SEQ ID NO: 22, and / or a VL comprising the amino acid sequence of SEQ ID NO: 23.

[0161] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising the amino acid sequence of SEQ ID NO: 25, and / or a VL comprising the amino acid sequence of SEQ ID NO: 26.

[0162] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising the amino acid sequence of SEQ ID NO: 28, and / or a VL comprising the amino acid sequence of SEQ ID NO: 29.

[0163] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising an amino acid sequence that is at least 80% (e.g., at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 89.5%, at least 90%, at least 90.5%, at least 91%, at least 92%, at least 93%, at least 94%, at least 94.5%, at least 95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to an amino acid sequence selected from any one of SEQ ID NOs: 1, 4, 7, 10, 13, 16, 19, 22, 25, or 28. Alternatively or in addition, the antibody or antigen-binding fragment thereof that bindsCD 19 can comprise a VL comprising an amino acid sequence that is at least 80% (e.g., at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 89.5%, at least 90%, at least 90.5%, at least 91%, at least 92%, at least 93%, at least 94%, at least 94.5%, at least 95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to an amino acid sequence selected from any one of SEQ ID NOs: 2, 5, 8, 11, 14, 17, 20, 23, 26, or 29.

[0164] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising an amino acid sequence that is at least 80% (e.g., at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 89.5%, at least 90%, at least 90.5%, at least 91%, at least 92%, at least 93%, at least 94%, at least 94.5%, at least 95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 1; and / or comprises a VL comprising an amino acid sequence that is at least 80% (e.g., at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 89.5%, at least 90%, at least 90.5%, at least 91%, at least 92%, at least 93%, at least 94%, at least 94.5%, at least 95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 2.

[0165] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising an amino acid sequence that is at least 80% (e.g., at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 89.5%, at least 90%, at least 90.5%, at least 91%, at least 92%, at least 93%, at least 94%, at least 94.5%, at least 95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 4; and / or comprises a VL comprising an amino acid sequence that is at least 80% (e.g., at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 89.5%, at least 90%, at least 90.5%, at least 91%, at least 92%, at least 93%, at least 94%, at least 94.5%, at least 95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 5.

[0166] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising an amino acid sequence that is at least 80% (e.g., at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 89.5%, at least 90%, at least 90.5%, at least 91%, at least 92%, at least 93%, at least 94%, at least 94.5%, at least95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 7; and / or comprises a VL comprising an amino acid sequence that is at least 80% (e.g., at least 85%, at least 86%, at least 87%, at least 88%, atleast 89%, at least 89.5%, at least 90%, at least 90.5%, at least 91%, at least 92%, at least93%, at least 94%, at least 94.5%, at least 95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 8.

[0167] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising an amino acid sequence that is at least 80% (e.g., at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 89.5%, at least 90%, at least 90.5%, at least 91%, at least 92%, at least 93%, at least 94%, at least 94.5%, at least 95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 10; and / or comprises a VL comprising an amino acid sequence that is at least 80% (e.g., at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 89.5%, at least 90%, at least 90.5%, at least 91%, at least 92%, at least 93%, at least 94%, at least 94.5%, at least 95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 11.

[0168] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising an amino acid sequence that is at least 80% (e.g., at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 89.5%, at least 90%, at least 90.5%, at least 91%, at least 92%, at least 93%, at least 94%, at least 94.5%, at least 95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 13; and / or comprises a VL comprising an amino acid sequence that is at least 80% (e.g., at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 89.5%, at least 90%, at least 90.5%, at least 91%, at least 92%, at least 93%, at least 94%, at least 94.5%, at least 95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 14.

[0169] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising an amino acid sequence that is at least 80% (e.g., at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 89.5%, at least 90%, at least 90.5%, at least 91%, at least 92%, at least 93%, at least 94%, at least 94.5%, at least 95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 16; and / or comprises a VL comprising an amino acid sequence that is at least 80% (e.g., at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 89.5%, at least 90%, at least 90.5%, at least 91%, at least 92%, at least 93%, at least 94%, at least 94.5%, at least 95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 17.

[0170] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising an amino acid sequence that is at least 80% (e.g., at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 89.5%, at least 90%, at least 90.5%, at least 91%, at least 92%, at least 93%, at least 94%, at least 94.5%, at least 95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 19; and / or comprises a VL comprising an amino acid sequence that is at least 80% (e.g., at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 89.5%, at least 90%, at least 90.5%, at least 91%, at least 92%, at least 93%, at least 94%, at least 94.5%, at least 95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 20.

[0171] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising an amino acid sequence that is at least 80% (e.g., at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 89.5%, at least 90%, at least 90.5%, at least 91%, at least 92%, at least 93%, at least 94%, at least 94.5%, at least 95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 22; and / or comprises a VL comprising an amino acid sequence that is at least 80% (e.g., at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 89.5%, at least 90%, at least 90.5%, at least 91%, at least 92%, at least 93%, at least 94%, at least 94.5%, at least 95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 23.

[0172] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD19 comprises a VH comprising an amino acid sequence that is at least 80% (e.g., at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 89.5%, at least 90%, at least 90.5%, at least 91%, at least 92%, at least 93%, at least 94%, at least 94.5%, at least 95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 25; and / or comprises a VL comprising an amino acid sequence that is at least 80% (e.g., at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 89.5%, at least 90%, at least 90.5%, at least 91%, at least 92%, at least 93%, at least 94%, at least 94.5%, at least 95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 26.

[0173] In certain embodiments, the antibody or antigen-binding fragment thereof that bindsCD19 comprises a VH comprising an amino acid sequence that is at least 80% (e.g., at least85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 89.5%, at least 90%, atleast 90.5%, at least 91%, at least 92%, at least 93%, at least 94%, at least 94.5%, at least 95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 28; and / or comprises a VL comprising an amino acid sequence that is at least 80% (e.g., at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 89.5%, at least 90%, at least 90.5%, at least 91%, at least 92%, at least 93%, at least 94%, at least 94.5%, at least 95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 29.

[0174] In each of the foregoing embodiments, it is contemplated herein that VH sequences and / or VL sequences that together bind CD 19 may each independently contain amino acid alterations (e.g., at least 1, 2, 3, 4, 5, or 10 amino acid substitutions, deletions, or additions) in the framework regions of the VH and / or the VL. In certain embodiments, a VH sequence and / or a VL sequence that together bind CD 19 may each independently contain 1-2, 1-3, 1-4, 1-5, 2-3, 2-4, 2-5, 3-4, 3-5, or 4-5 amino acid alterations (e.g., substitutions, deletions, or additions) in the framework regions of the VH and / or the VL. In certain embodiments, the framework regions of the VH are humanized or fully human framework regions. In certain embodiments, the framework regions of the VL are humanized or fully human framework regions.

[0175] In certain embodiments, the antibody or antigen-binding fragment thereof that bindsCD 19 comprises an scFv. In certain embodiments, the scFv comprises the amino acid sequence of SEQ ID NO: 3. In certain embodiments, the scFv comprises the amino acid sequence of SEQ ID NO: 6. In certain embodiments, the scFv comprises the amino acid sequence of SEQ ID NO: 9. In certain embodiments, the scFv comprises the amino acid sequence of SEQ ID NO: 12. In certain embodiments, the scFv comprises the amino acid sequence of SEQ ID NO: 15. In certain embodiments, the scFv comprises the amino acid sequence of SEQ ID NO: 18. In certain embodiments, the scFv comprises the amino acid sequence of SEQ ID NO: 21. In certain embodiments, the scFv comprises the amino acid sequence of SEQ ID NO: 24. In certain embodiments, the scFv comprises the amino acid sequence of SEQ ID NO: 27. In certain embodiments, the scFv comprises the amino acid sequence of SEQ ID NO: 30.

[0176] In certain embodiments, the antibody or antigen-binding fragment thereof that bindsCD 19 comprises an scFv, wherein the scFv comprises an amino acid sequence that is at least80% (e.g., at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 89.5%, at least 90%, at least 90.5%, at least 91%, at least 92%, at least 93%, at least 94%, at least94.5%, at least 95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 3.

[0177] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD 19 comprises an scFv, wherein the scFv comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 89.5%, at least 90%, at least 90.5%, at least 91%, at least 92%, at least 93%, at least 94%, at least 94.5%, at least 95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 6.

[0178] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD 19 comprises an scFv, wherein the scFv comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 89.5%, at least 90%, at least 90.5%, at least 91%, at least 92%, at least 93%, at least 94%, at least 94.5%, at least 95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 9.

[0179] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD 19 comprises an scFv, wherein the scFv comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 89.5%, at least 90%, at least 90.5%, at least 91%, at least 92%, at least 93%, at least 94%, at least 94.5%, at least 95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 12.

[0180] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD 19 comprises an scFv, wherein the scFv comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 89.5%, at least 90%, at least 90.5%, at least 91%, at least 92%, at least 93%, at least 94%, at least 94.5%, at least 95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 15.

[0181] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD 19 comprises an scFv, wherein the scFv comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 89.5%, at least 90%, at least 90.5%, at least 91%, at least 92%, at least 93%, at least 94%, at least94.5%, at least 95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 18.

[0182] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD 19 comprises an scFv, wherein the scFv comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 89.5%, at least 90%, at least 90.5%, at least 91%, at least 92%, at least 93%, at least 94%, at least 94.5%, at least 95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 21.

[0183] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD 19 comprises an scFv, wherein the scFv comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 89.5%, at least 90%, at least 90.5%, at least 91%, at least 92%, at least 93%, at least 94%, at least 94.5%, at least 95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 24.

[0184] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD 19 comprises an scFv, wherein the scFv comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 89.5%, at least 90%, at least 90.5%, at least 91%, at least 92%, at least 93%, at least 94%, at least 94.5%, at least 95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 27.

[0185] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD 19 comprises an scFv, wherein the scFv comprises an amino acid sequence that is at least 80% (e.g., at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 89.5%, at least 90%, at least 90.5%, at least 91%, at least 92%, at least 93%, at least 94%, at least 94.5%, at least 95%, at least 95.5%, at least 96%, at least 97%, at least 98%, or at least 99%) identical to the amino acid sequence of SEQ ID NO: 30.

[0186] In certain embodiments, the CD 19 antibody or antigen-binding fragment thereof is humanized or fully human. In certain embodiments, the CD 19 antibody or antigen-binding fragment thereof is fully human. In certain embodiments, the VH and the VL of the CD 19 antibody or antigen-binding fragment thereof are fully human.

[0187] In certain embodiments, the antibody or antigen-binding fragment thereof binds CD19 with a KD of 500 nM, 250 nM, 200 nM, 150 nM, 125 nM, 100 nM, 90 nM, 80 nM, 70 nM, 60 nM, 50 nM, 40 nM, 30 nM, 25 nM, 20 nM, 15 nM, 10 nM, 5 nM, 1 nM, or 0.1 nM or stronger, as measured using standard binding assays, for example, surface plasmon resonanceor bio-layer interferometry. In certain embodiments, the antibody or antigen-binding fragment thereof binds CD 19 with a KD of from 500 nM to 0.1 nM, e.g.. from 500 nM to 1 nM, from 500 nM to 5 nM, from 500 nM to 10 nM, from 500 nM to 15 nM, from 500 nM to 20 nM, from 500 nM to 25 nM, from 500 nM to 30 nM, from 500 nM to 40 nM, from 500 nM to 50 nM, from 500 nM to 60 nM, from 500 nM to 70 nM, from 500 nM to 80 nM, from 500 nM to 90 nM, from 500 nM to 100 nM, from 500 nM to 125 nM, from 500 nM to 150 nM, from 500 nM to 200 nM, from 500 nM to 250 nM, from 250 nM to 0.1 nM, from 250 nM to 1 nM, from 250 nM to 5 nM, from 250 nM to 10 nM, from 250 nM to 15 nM, from 250 nM to 20 nM, from 250 nM to 25 nM, from 250 nM to 30 nM, from 250 nM to 40 nM, from 250 nM to 50 nM, from 250 nM to 60 nM, from 250 nM to 70 nM, from 250 nM to 80 nM, from 250 nM to 90 nM, from 250 nM to 100 nM, from 250 nM to 125 nM, from 250 nM to 150 nM, from 250 nM to 200 nM, from 200 nM to 0.1 nM, from 200 nM to 1 nM, from 200 nM to 5 nM, from 200 nM to 10 nM, from 200 nM to 15 nM, from 200 nM to 20 nM, from 200 nM to 25 nM, from 200 nM to 30 nM, from 200 nM to 40 nM, from 200 nM to 50 nM, from 200 nM to 60 nM, from 200 nM to 70 nM, from 200 nM to 80 nM, from 200 nM to 90 nM, from 200 nM to 100 nM, from 200 nM to 125 nM, from 200 nM to 150 nM, from 150 nM to 0.1 nM, from 150 nM to 1 nM, from 150 nM to 5 nM, from 150 nM to 10 nM, from 150 nM to 15 nM, from 150 nM to 20 nM, from 150 nM to 25 nM, from 150 nM to 30 nM, from 150 nM to 40 nM, from 150 nM to 50 nM, from 150 nM to 60 nM, from 150 nM to 70 nM, from 150 nM to 80 nM, from 150 nM to 90 nM, from 150 nM to 100 nM, from 150 nM to 125 nM, from 125 nM to 0.1 nM, from 125 nM to 1 nM, from 125 nM to 5 nM, from 125 nM to 10 nM, from 125 nM to 15 nM, from 125 nM to 20 nM, from 125 nM to 25 nM, from 125 nM to 30 nM, from 125 nM to 40 nM, from 125 nM to 50 nM, from 125 nM to 60 nM, from 125 nM to 70 nM, from 125 nM to 80 nM, from 125 nM to 90 nM, from 125 nM to 100 nM, from 100 nM to 0.1 nM, from 100 nM to 1 nM, from 100 nM to 5 nM, from 100 nM to 10 nM, from 100 nM to 15 nM, from 100 nM to 20 nM, from 100 nM to 25 nM, from 100 nM to 30 nM, from 100 nM to 40 nM, from 100 nM to 50 nM, from 100 nM to 60 nM, from 100 nM to 70 nM, from 100 nM to 80 nM, from 100 nM to 90 nM, from 90 nM to 0.1 nM, from 90 nM to 1 nM, from 90 nM to 5 nM, from 90 nM to 10 nM, from 90 nM to 15 nM, from 90 nM to 20 nM, from 90 nM to 25 nM, from 90 nM to 30 nM, from 90 nM to 40 nM, from 90 nM to 50 nM, from 90 nM to 60 nM, from 90 nM to 70 nM, from 90 nM to 80 nM, from 80 nM to 0.1 nM, from 80 nM to 1 nM, from 80 nM to 5 nM, from 80 nM to 10 nM, from 80 nM to 15 nM, from 80 nM to 20 nM, from 80 nM to 25 nM, from 80 nM to 30 nM, from 80 nM to 40 nM, from 80 nM to 50 nM, from 80 nM to 60 nM, from 80 nM to 70 nM,from 70 nM to 0.1 nM, from 70 nM to 1 nM, from 70 nM to 5 nM, from 70 nM to 10 nM, from 70 nM to 15 nM, from 70 nM to 20 nM, from 70 nM to 25 nM, from 70 nM to 30 nM, from 70 nM to 40 nM, from 70 nM to 50 nM, from 70 nM to 60 nM, from 60 nM to 0.1 nM, from 60 nM to 1 nM, from 60 nM to 5 nM, from 60 nM to 10 nM, from 60 nM to 15 nM, from 60 nM to 20 nM, from 60 nM to 25 nM, from 60 nM to 30 nM, from 60 nM to 40 nM, from 60 nM to 50 nM, from 50 nM to 0.1 nM, from 50 nM to 1 nM, from 50 nM to 5 nM, from 50 nM to 10 nM, from 50 nM to 15 nM, from 50 nM to 20 nM, from 50 nM to 25 nM, from 50 nM to 30 nM, from 50 nM to 40 nM, from 40 nM to 0.1 nM, from 40 nM to 1 nM, from 40 nM to 5 nM, from 40 nM to 10 nM, from 40 nM to 15 nM, from 40 nM to 20 nM, from 40 nM to 25 nM, from 40 nM to 30 nM, from 30 nM to 0.1 nM, from 30 nM to 1 nM, from 30 nM to 5 nM, from 30 nM to 10 nM, from 30 nM to 15 nM, from 30 nM to 20 nM, from 30 nM to 25 nM, from 25 nM to 0.1 nM, from 25 nM to 1 nM, from 25 nM to 5 nM, from 25 nM to 10 nM, from 25 nM to 15 nM, from 25 nM to 20 nM, from 20 nM to 0.1 nM, from 20 nM to 1 nM, from 20 nM to 5 nM, from 20 nM to 10 nM, from 20 nM to 15 nM, from 15 nM to 0.1 nM, from 15 nM to 1 nM, from 15 nM to 5 nM, from 15 nM to 10 nM, from 10 nM to 0.1 nM, from 10 nM to 1 nM, from 10 nM to 5 nM, from 5 nM to 0. 1 nM, from 5 nM to 1 nM, or from 1 nM to 0. 1 nM, as measured using standard binding assays, for example, surface plasmon resonance or bio-layer interferometry.

[0188] In certain embodiments, the antibody or antigen-binding fragment thereof that binds CD 19 cross-competes with an antibody or antigen-binding fragment thereof disclosed in TABLE 1, 2, or 3. Competition assays for determining whether an antibody or antigenbinding fragment thereof binds to the same epitope as, or competes for binding with a disclosed antibody are known in the art. Exemplary competition assays include immunoassays (e.g, ELISA assays, RIA assays), surface plasmon resonance, (e.g., BIAcore analysis), bio-layer interferometry, and flow cytometry.

[0189] The antibodies and antigen-binding fragments thereof disclosed herein may be further optimized (e.g., affinity-matured) to improve biochemical characteristics including affinity and / or specificity, improve biophysical properties including aggregation, stability, precipitation and / or non-specific interactions, and / or to reduce immunogenicity. Affinitymaturation procedures are within ordinary skill in the art. For example, diversity can be introduced into an immunoglobulin heavy chain and / or an immunoglobulin light chain by DNA shuffling, chain shuffling, CDR shuffling, random mutagenesis and / or site-specific mutagenesis. Generally, an optimized antibody or antigen-binding fragment thereof has atleast the same, or substantially the same, affinity for the antigen as the non-optimized (or parental) antibody from which it was derived. Preferably, an optimized antibody has a higher affinity for the antigen when compared to the parental antibody.

[0190] In certain embodiments, a CD 19 antibody of the disclosure is an isolated antibody, e.g., an isolated monoclonal antibody. For example, antibodies or antigen-binding fragments thereof may be removed from, for example, a cell, tissue, body fluid, or animal body, for example, by various purification techniques.

[0191] In certain embodiments, a CD 19 antibody or antigen-binding fragment thereof disclosed herein comprises an antibody Fc domain, e.g., a human antibody Fc domain. For example, the antibody molecule may have a heavy chain constant region selected from, e.g., the heavy chain constant regions of IgGl, IgG2, IgG3, IgG4, IgM, IgAl, IgA2, IgD, and IgE; particularly, selected from, e.g., the (e.g., human) heavy chain constant regions of IgGl, IgG2, IgG3, and IgG4. In another embodiment, the antibody molecule has a light chain constant region chosen from, e.g., the (e.g., human) light chain constant regions of kappa or lambda. The constant region can be altered, e.g. , mutated, to modify the properties of the antibody (e.g., to increase or decrease one or more of: Fc receptor binding, antibody glycosylation, the number of cysteine residues, effector cell function, and / or complement function). In certain embodiments, the antibody has effector function and can fix complement. In other embodiments the antibody does not recruit effector cells or fix complement. In certain embodiments, the antibody has reduced or no ability to bind an Fc receptor. For example, the antibody may be an isotype or subtype, fragment, or other mutant, which does not support binding to an Fc receptor, e.g., it has a mutagenized or deleted Fc receptor binding region.

[0192] In certain embodiments, an amino acid substitution in the first Fc polypeptide replaces the original amino acid with a larger amino acid, selected from arginine (R), phenylalanine (F), tyrosine (Y) or tryptophan (W), and at least one amino acid substitution in the second Fc polypeptide replaces the original amino acid(s) with a smaller amino acid(s), chosen from alanine (A), serine (S), threonine (T), or valine (V), such that the larger amino acid substitution (a protuberance) fits into the surface of the smaller amino acid substitutions (a cavity). For example, one polypeptide can incorporate a T366W substitution, and the other can incorporate three substitutions including T366S, L368A, and Y407V, or T366S, L368A, and Y407T (residue numbers according to EU numbering, Kabat, E.A., et al. (1991) supra). This set of substitutions are referred to as “knobs-in-holes,” wherein the polypeptide chaincomprising a T366W substitution has a “knob” and the polypeptide chain comprising T366S, L368A, and Y407V or T366S, L368A, and Y407T substitutions has a “hole.”

[0193] Alternatively, amino acid substitutions could be selected from the following sets of substitutions shown in TABLE 4 below. Additional exemplary Fc domain substitutions that promote heterodimerization are disclosed in U.S. Patent No. 11,084,863.TABLE 4. Fc Heterodimerization Mutations

[0194] It is understood that where an antibody or antigen-binding fragment thereof disclosed herein is described to contain a first set of mutations in a given first Fc polypeptide chain and a second set of mutations in the second Fc polypeptide chain, the reverse construct, in which the first Fc polypeptide chain contains the second set of mutations and the second Fc polypeptide chain contains the first set of mutations, is also contemplated.III. Chimeric Antigen Receptors

[0195] The disclosure also provides, among other things, chimeric antigen receptors(CARs) that comprise a CD 19 antibody or antigen-binding fragment thereof as disclosed herein. In certain embodiments, a CAR of the disclosure comprises (1) an extracellular binding domain comprising a CD 19 antibody of the disclosure or an antigen-bindingfragment thereof, (2) a transmembrane domain, (3) an intracellular signaling domain and, optionally, (4) a costimulatory domain. In certain embodiments, the intracellular signaling domain is, or is derived from, a stimulatory molecule, such as a T cell activating domain providing a primary activation signal. Upon specific binding to the targeted antigen, the receptor generally delivers an immunostimulatory signal, such as an ITAM-transduced signal, into the cell, thereby activating the cell and promoting a targeted immune response. In certain embodiments, the CAR further comprises one or more costimulatory signaling domains comprising functional signaling domains derived from one or more costimulatory molecules. In certain embodiments, a CAR of the disclosure comprises a KIR transmembrane domain and a KIR cytoplasmic domain. a. CAR Extracellular Domain

[0196] The extracellular domain of the CAR comprises a binding domain that binds the B- cell surface protein CD19. The extracellular binding domain can comprise, for example, an antibody or antigen-binding fragment thereof disclosed herein that binds (e.g., specifically binds) CD 19, e.g., as disclosed hereinabove in Section II. In certain embodiments, the CD 19 antibody or antigen-binding fragment thereof is a Fab fragment or an scFv. In certain embodiments, the CD 19 antibody or antigen-binding fragment thereof is an scFv, e.g., an scFv disclosed in Section II hereinabove.

[0197] The functional ability of a CAR to specifically bind to its target antigen (e.g., CD 19) can be assessed in a Jurkat reporter cell line, wherein activation of the CAR is dependent on binding to plate-bound or cell-bound target protein (in response to which the activated cells fluoresce green due to an NFAT-GFP reporter construct contained therein). Such methods are useful and reliable qualitative measures for functional binding ability. b. CAR Transmembrane Domain

[0198] The extracellular binding domain can be fused to the transmembrane domain of the CAR. In certain embodiments, the transmembrane domain of the CAR is derived from a naturally occurring transmembrane protein. In certain embodiments, the transmembrane domain is capable of signaling to the intracellular domain(s) whenever the CAR has bound to a target. In certain embodiments, the transmembrane domain comprises the transmembrane region(s) of one or more proteins selected from the group consisting of TCR a chain, TCR [3 chain, TCR chain, CD28, CD3a, CD45, CD4, CD5, CD8a, CD9, CD16, CD22, EGFR, CD37, CD64, CD80, CD86, CD134, CD137, CD154, KIRDS2, 0X40, CD2, CD27, LFA-1(CDl la, CD18), ICOS (CD278), 4-1BB (CD137), GITR, CD40, BAFFR, HVEM (LIGHTR), SLAMF7, NKp80 (KLRF1), NKp44, NKp30, NKp46, CD160, CD19, IL2RJ3, IL2Ry, IL7Ra, ITGA1, VLA1, CD49a, ITGA4, IA4, CD49D, ITGA6, VLA-6, CD49f, ITGAD, CDI Id, ITGAE, CD103, ITGAL, CDl la, LFA-1, ITGAM, CDl lb, ITGAX, CDI Ic, ITGB1, CD29, ITGB2, CD18, LFA-1, ITGB7, TNFR2, DNAM1 (CD226), SLAMF4 (CD244, 2B4), CD84, CD96 (Tactile), CEACAM1, CRTAM, Ly9 (CD229), CD160 (BY55), PSGL1, CD100 (SEMA4D), SLAMF6 (NTB-A, Lyl08), SLAM (SLAMF1, CD150, IPO-3), BLAME (SLAMF8), SELPLG (CD 162), LTBR, PAG / Cbp, NKG2D, and NKG2C. In certain embodiments, the transmembrane comprises the transmembrane region(s) of one or more proteins selected from the group consisting of CD8a, CD28, CD3^, and CD4. In certain embodiments, the transmembrane comprises the transmembrane region(s) of one or more proteins selected from the group consisting of CD8a and CD28. In certain embodiments, the transmembrane domain comprises a CD8a transmembrane domain. In certain embodiments, the transmembrane domain is one that naturally is associated with one of the domains (e.g., primary signaling domain or co-stimulatory signaling domain) in the CAR. In certain embodiments, the transmembrane domain can be selected or modified by amino acid substitution to avoid multimerization with a transmembrane domain of the same or a different surface membrane protein, thereby to minimize interactions with other members of a receptor complex (e.g., the CAR complex). In other embodiments, the transmembrane domain is capable of homodimerization with another CAR on the immune cell (e.g., T cell) surface. In certain embodiments, the amino acid sequence of the transmembrane domain may be modified or substituted so as to minimize interactions with the binding domains of the native binding partner present in the same immune cell.

[0199] In certain embodiments, the transmembrane domain comprises a CD 8a transmembrane domain. In certain embodiments, the transmembrane domain comprises an amino acid sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO: 137. In certain embodiments, the transmembrane domain comprises the amino acid sequence of SEQ ID NO: 137.

[0200] In certain embodiments, the transmembrane domain comprises a conservative substitution relative to a transmembrane domain disclosed herein, e.g., relative to atransmembrane domain comprising the amino acid sequence of SEQ ID NO: 137. In certain embodiments, the transmembrane domain comprises less than 2, less than 3, less than 4, less than 5, less than 6, less than 7, less than 8, less than 9, less than 10, less than 11, less than 12, less than 13, less than 14, or less than 15 conservative substitutions relative to, e.g., the amino acid sequence of SEQ ID NO: 137. In certain embodiments, the transmembrane domain comprises 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 or more conservative substitutions relative to the amino acid sequence of SEQ ID NO: 137.

[0201] In certain embodiments, the transmembrane domain comprises a CD28 transmembrane domain. In certain embodiments, the transmembrane domain comprises an amino acid sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO: 161. In certain embodiments, the transmembrane domain comprises the amino acid sequence of SEQ ID NO: 161.

[0202] In certain embodiments, the transmembrane domain comprises a conservative substitution relative to a transmembrane domain disclosed herein, e.g., relative to a transmembrane domain comprising the amino acid sequence of SEQ ID NO: 161. In certain embodiments, the transmembrane domain comprises less than 2, less than 3, less than 4, less than 5, less than 6, less than 7, less than 8, less than 9, less than 10, less than 11, less than 12, less than 13, less than 14, or less than 15 conservative substitutions relative to, e.g., the amino acid sequence of SEQ ID NO: 161. In certain embodiments, the transmembrane domain comprises 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 or more conservative substitutions relative to the amino acid sequence of SEQ ID NO: 161.

[0203] In certain embodiments, the CAR comprises a transmembrane domain and / or a cytoplasmic (intracellular) domain from a killer immunoglobulin-like receptor (KIR) family protein. The KIR gene family has at least 15 gene loci (KIR2DL1, KIR2DL2 / L3, KIR2DL4, KIR2DL5A, KIR2DL5B, KIR2DS1, KIR2DS2, KIR2DS3, KIR2DS4, KIR2DS5 KIR3DL1 / S1 KIR3DL2 KIR3DL3) and two pseudogenes (KIR2DP1 and KIR3DP1) encoded within a 100-200 Kb region of the Leukocyte Receptor Complex (LRC) located on chromosome 19 ( 19ql 3.4) . The LRC constitutes a large, 1 Mb, and dense cluster of rapidly evolving immune genes which contains genes encoding other cell surface molecules with distinctive Ig-like extra-cellular domains. In addition, the extended LRC contains genesencoding the transmembrane adaptor molecules DAP 10 and DAP 12. Thus, in certain embodiments, a cell comprising the CAR of the disclosure comprising a KIR transmembrane domain and / or cytoplasmic domain may also comprise a polynucleotide encoding DAP 10 or DAP12. In certain embodiments, the KIR is KIRS2 or KIR2DS2. c. CAR Intracellular Domains

[0204] The intracellular domain of the CAR comprises an intracellular signaling domain (z.e., a functional signaling domain derived from a stimulatory molecule) and, optionally, one or more costimulatory signaling domains (i. e. , functional signaling domains derived from at least one costimulatory molecule). These intracellular signaling and costimulatory domains are responsible, at least in part, for an immune cell response, including, but not limited to, proliferation, differentiation, and activation of a specialized function of the immune cell (e.g., cytotoxic activity or secretion of cytokines of a T cell) in which the CAR is expressed. The intracellular signaling domain is thus meant to include any truncated portion of the intracellular signaling domain sufficient to transduce the effector function signal.

[0205] Intracellular signaling domains that act in a stimulatory manner may contain signaling motifs which are known as immunoreceptor tyrosine-based activation motifs (ITAMs). Examples of ITAM-containing cytoplasmic signaling sequences that are of particular use in the CARs of the present application include those derived from CD3^, common FcRy (FCER1G), FcyRIIa, FcRp (FcaRlb), CD3y, CD35, CD3a, CD79a, CD79b, DAP 10, and DAP 12. In certain embodiments, the intracellular signaling domain of a CAR described herein comprises a functional, cytoplasmic signaling domain derived from CD3^, FcRy, FcR|3, CD3y, CD35, CD3a, CD5, CD22, CD79a, CD79b, CD66d, 4-1BB, common FcRy (FCER1G), FcyRIIa, FcRp (FcaRlb), DAP10, and / or DAP12. In certain embodiments, the intracellular signaling domain comprises a CD3^ signaling domain or an FcRy signaling domain.

[0206] In certain embodiments, a CAR of the disclosure comprises a CD3^ signaling domain by itself or in combination with any other desired cytoplasmic domain(s) useful in the context of the CAR. For example, the CAR can comprise a CD3^ chain portion (z.e., a CD3^ intracellular signaling domain) and an intracellular domain of a costimulatory molecule, for example, a 4-1BB intracellular domain or a CD28 intracellular domain. In certain embodiments, the CD3^ intracellular signaling domain is a human T-cell surface glycoprotein CD3^ chain isoform 3 (human CD247) intracellular domain. The human CD3^ intracellulardomain provides stimulatory intracellular signaling upon binding of the extracellular antigen to its ligand without HLA restriction.

[0207] In certain embodiments, a CAR of the disclosure comprises a CD3^ signaling domain. In certain embodiments, the intracellular signaling domain comprises an amino acid sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO: 139. In certain embodiments, the intracellular signaling domain comprises the amino acid sequence of SEQ ID NO: 139.

[0208] In certain embodiments, the intracellular signaling domain comprises a conservative substitution relative to an intracellular signaling domain disclosed herein, e.g., relative to an intracellular signaling domain comprising the amino acid sequence of SEQ ID NO: 139. In certain embodiments, the intracellular signaling domain comprises less than 2, less than 3, less than 4, less than 5, less than 6, less than 7, less than 8, less than 9, less than 10, less than 11, less than 12, less than 13, less than 14, or less than 15 conservative substitutions relative to, e.g., the amino acid sequence of SEQ ID NO: 139. In certain embodiments, the intracellular signaling domain comprises 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 or more conservative substitutions relative to the amino acid sequence of SEQ ID NO: 139.

[0209] In certain embodiments, a CAR of the disclosure comprises a costimulatory domain. A costimulatory domain comprises a functional signaling domain derived from a costimulatory molecule, a cell surface molecule other than an antigen receptor or its ligands that is required for an efficient response of lymphocytes to an antigen. Examples of costimulatory molecules include CD27, CD28, 4-1BB (CD137), 0X40, CD30, CD40, PD-1, ICOS, lymphocyte function-associated antigen-1 (LFA-1, CDl la / CD18), CD2, CD7, CD258 (LIGHT), NKG2C, B7-H3, CD83 ligands, CD5, ICAM-1, GITR, BAFFR, HVEM (LIGHTR), SLAMF7, NKp80 (KLRF1), NKp44, NKp30, NKp46, CD160, CD19, CD4, CD8a, CD8[3, IL2RJ3, IL2Ry, IL7Ra, ITGA4, VLA1, CD49a, ITGA4, IA4, CD49D, ITGA6, VLA-6, CD49f, ITGAD, CDl ld, ITGAE, CD103, ITGAL, CDl la, LFA-1, ITGAM, CDl lb, ITGAX, CD11c, ITGB1, CD29, ITGB2, CD18, LFA-1, ITGB7, NKG2D, NKG2C, TNFR2, TRANCE / RANKL, DNAM1 (CD226), SLAMF4 (CD244, 2B4), CD84, CD96 (Tactile), CEACAM1, CRTAM, Ly9 (CD229), PSGL1, CD 100 (SEMA4D), CD69, SLAMF6 (NTB- A, Lyl08), SLAM (SLAMF1, CD 150, IPO-3), BLAME (SLAMF8), SELPLG (CD 162), LTBR, LAT, GADS, SLP-76, and PAG / Cbp. In certain embodiments, a costimulatorydomain of the CAR comprises a functional signaling domain of a costimulatory molecule described herein, e.g., 0X40, CD27, CD28, CD30, CD40, PD-1, CD2, CD7, CD258, NKG2C, B7-H3, a CD83 ligand, ICAM-1, LFA-1 (CD1 la / CD18), ICOS and 4-1BB(CD 137), or any combination thereof. In certain embodiments, a costimulatory domain of the CAR comprises a functional signaling domain of a costimulatory molecule selected from 4- 1BB (CD137), CD28, ICOS, CD27, CD40, and 0X40. In certain embodiments, the CAR comprises a costimulatory domain comprising a 4-1BB intracellular domain and / or a CD28 intracellular domain.

[0210] In certain embodiments, a CAR of the disclosure comprises a costimulatory domain comprising a 4-1BB intracellular domain. In certain embodiments, the costimulatory domain comprises an amino acid sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO: 138. In certain embodiments, the costimulatory domain comprises the amino acid sequence of SEQ ID NO: 138.

[0211] In certain embodiments, the costimulatory domain comprises a conservative substitution relative to a costimulatory domain disclosed herein, e.g., relative to costimulatory domain comprising the amino acid sequence of SEQ ID NO: 138. In certain embodiments, the costimulatory domain comprises less than 2, less than 3, less than 4, less than 5, less than 6, less than 7, less than 8, less than 9, less than 10, less than 11, less than 12, less than 13, less than 14, or less than 15 conservative substitutions relative to, e.g., the amino acid sequence of SEQ ID NO: 138. In certain embodiments, the intracellular signaling domain comprises 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 or more conservative substitutions relative to the amino acid sequence of SEQ ID NO: 138.

[0212] In certain embodiments, a CAR of the disclosure comprises a costimulatory domain comprising a CD28 intracellular domain. In certain embodiments, the costimulatory domain comprises an amino acid sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO: 162. In certain embodiments, the costimulatory domain comprises the amino acid sequence of SEQ ID NO: 162.

[0213] In certain embodiments, the costimulatory domain comprises a conservative substitution relative to a costimulatory domain disclosed herein, e.g., relative to costimulatory domain comprising the amino acid sequence of SEQ ID NO: 162. In certain embodiments, the costimulatory domain comprises less than 2, less than 3, less than 4, less than 5, less than 6, less than 7, less than 8, less than 9, less than 10, less than 11, less than 12, less than 13, less than 14, or less than 15 conservative substitutions relative to, e.g., the amino acid sequence of SEQ ID NO: 162. In certain embodiments, the intracellular signaling domain comprises 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 or more conservative substitutions relative to the amino acid sequence of SEQ ID NO: 162.

[0214] The intracellular signaling and costimulatory domains within the cytoplasmic portion of the CAR may be linked to each other in a random or specified order. In certain embodiments, a costimulatory signaling domain is deployed N-terminal to the primary signaling domain. Optionally, the intracellular domains are linked by a short oligo- or polypeptide linker, for example, between 2 and 10 amino acids in length. In certain embodiments, the intracellular domains are linked by, e.g. , a GS doublet or by a (G4S)nlinker. In certain embodiments, the intracellular signaling domain (e.g. CD3^ signaling domain) is the C-terminal domain of the CAR. d. Other CAR Domains

[0215] The extracellular antigen-binding domain of the CAR can be connected to the transmembrane domain by a hinge domain or linker. In certain embodiments, the hinge domain or linker is interposed between the antigen binding site and the transmembrane domain. A variety of hinges or linkers can be employed, including, but not limited to, the human Ig (immunoglobulin) hinge (e.g., an IgG4 hinge, an IgD hinge), a Gly-Ser linker, a (G-iS)-i linker, a KIR2DS2 hinge, and a CD8a hinge.

[0216] In certain embodiments, the hinge domain is a CD8a hinge. In certain embodiments, the hinge domain comprises an amino acid sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO: 140. In certain embodiments, the hinge domain comprises the amino acid sequence of SEQ ID NO: 140.

[0217] In certain embodiments, the hinge domain comprises a conservative substitution relative to a hinge domain disclosed herein, e.g., relative to a hinge domain comprising the amino acid sequence of SEQ ID NO: 140. In certain embodiments, the hinge domain comprises less than 2, less than 3, less than 4, less than 5, less than 6, less than 7, less than 8, less than 9, less than 10, less than 11, less than 12, less than 13, less than 14, or less than 15 conservative substitutions relative to, e.g., the amino acid sequence of SEQ ID NO: 140. In certain embodiments, the hinge domain comprises 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 or more conservative substitutions relative to the amino acid sequence of SEQ ID NO: 140.

[0218] In certain embodiments, the CAR comprises a CD8a transmembrane domain and a CD 8 a hinge.

[0219] In certain embodiments, the CAR comprises a signal peptide. In certain embodiments, the nucleic acid encoding the CAR comprises a nucleic acid sequence encoding a signal peptide. In certain embodiments, the signal peptide is derived from a native polypeptide. In other embodiments, the signal peptide comprises a heterologous or non-native signal peptide. In certain embodiments, the signal peptide is a CD8a signal peptide or an IgG signal peptide.

[0220] In certain embodiments, the CAR comprises a CD8a signal peptide. In certain embodiments, the signal peptide comprises an amino acid sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO: 163. In certain embodiments, the signal peptide comprises the amino acid sequence of SEQ ID NO: 163. In certain embodiments, the CAR comprises an IgG signal peptide. In certain embodiments, the signal peptide comprises an amino acid sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of SEQ ID NO: 164. In certain embodiments, the signal peptide comprises the amino acid sequence of SEQ ID NO: 164.

[0221] In certain embodiments, the signal peptide comprises a conservative substitution relative to a signal peptide disclosed herein, e.g., relative to a signal peptide comprising theamino acid sequence of SEQ ID NO: 163 or SEQ ID NO: 164. In certain embodiments, the signal peptide comprises less than 2, less than 3, less than 4, less than 5, less than 6, less than 7, less than 8, less than 9, or less than 10 conservative substitutions relative to, e.g., the signal peptide of SEQ ID NO: 163 or SEQ ID NO: 164. In certain embodiments, the signal peptide comprises 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 or more conservative substitutions relative to the amino acid sequence of SEQ ID NO: 163 or SEQ ID NO: 164. e. Exemplary CAR Constructs

[0222] In certain embodiments, a CAR of the disclosure comprises, in the N- to C-terminal direction: (1) an extracellular domain comprising a CD19 antibody or antigen-binding fragment thereof, for example, an anti-CD 19 scFv, e.g. , an scFv comprising the amino acid sequence of any one of SEQ ID NOs: 3, 6, 9, 12, 15, 18, 21, 24, 27, or 30; (2) an optional hinge domain or linker, for example, a CD8a hinge, e.g., a hinge comprising the amino acid sequence of SEQ ID NO: 140; (3) a transmembrane domain, for example, a CD8a transmembrane domain, e.g., a transmembrane domain comprising the amino acid sequence of SEQ ID NO: 137; (4) an optional costimulatory domain, for example, an intracellular domain of 4- IBB, e.g., a costimulatory domain comprising the amino acid sequence of SEQ ID NO: 138; and (e) an intracellular signaling domain, for example, a CD3^ signaling domain, e.g., a signaling domain comprising the amino acid sequence of SEQ ID NO: 139. In certain embodiments, the CAR further comprises an N-terminal signal peptide, for example, a CD8 signal peptide, e.g., a signal peptide comprising the amino acid sequence of SEQ ID NO: 163. A schematic of an exemplary anti-CD 19 CAR construct of the disclosure is depicted in FIGURE 1.

[0223] In certain embodiments, a CAR of the disclosure comprises an amino acid sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of any one of SEQ ID NOs: 141-160. In certain embodiments, the CAR comprises the amino acid sequence of any one of SEQ ID NOs: 141-160.

[0224] In certain embodiments, a CAR of the disclosure comprises a conservative substitution relative to a CAR disclosed herein, e.g., relative to a CAR comprising the amino acid sequence of any one of SEQ ID NOs: 141-160. In certain embodiments, the CAR comprises less than 2, less than 3, less than 4, less than 5, less than 6, less than 7, less than 8,less than 9, less than 10, less than 11, less than 12, less than 13, less than 14, less than 15, less than 20, less than 25, or less than 30 conservative substitutions relative to, e.g., the CAR of any one of SEQ ID NOs: 141-160. In certain embodiments, the CAR comprises 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 20, 25, or 30 or more conservative substitutions relative to the amino acid sequence of any one of SEQ ID NOs: 141-160.

[0225] In certain embodiments, a CAR of the disclosure comprises an amino acid sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of any one of SEQ ID NOs: 141-143. In certain embodiments, the CAR comprises the amino acid sequence of any one of SEQ ID NOs: 141-143.

[0226] In certain embodiments, a CAR of the disclosure comprises a conservative substitution relative to a CAR disclosed herein, e.g., relative to a CAR comprising the amino acid sequence of any one of SEQ ID NOs: 141-143. In certain embodiments, the CAR comprises less than 2, less than 3, less than 4, less than 5, less than 6, less than 7, less than 8, less than 9, less than 10, less than 11, less than 12, less than 13, less than 14, less than 15, less than 20, less than 25, or less than 30 conservative substitutions relative to, e.g., the CAR of any one of SEQ ID NOs: 141-143. In certain embodiments, the CAR comprises 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 20, 25, or 30 or more conservative substitutions relative to the amino acid sequence of SEQ any one of SEQ ID NOs: 141-143.

[0227] In certain embodiments, a CAR of the disclosure comprises an amino acid sequence at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of any one of SEQ ID NOs: 151-153. In certain embodiments, the CAR comprises the amino acid sequence of any one of SEQ ID NOs: 151-153.

[0228] In certain embodiments, a CAR of the disclosure comprises a conservative substitution relative to a CAR disclosed herein, e.g., relative to a CAR comprising the amino acid sequence of any one of SEQ ID NOs: 151-153. In certain embodiments, the CAR comprises less than 2, less than 3, less than 4, less than 5, less than 6, less than 7, less than 8, less than 9, less than 10, less than 11, less than 12, less than 13, less than 14, less than 15, less than 20, less than 25, or less than 30 conservative substitutions relative to, e.g., the CAR ofany one of SEQ ID NOs: 151-153. In certain embodiments, the CAR comprises 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 20, 25, or 30 or more conservative substitutions relative to the amino acid sequence of SEQ any one of SEQ ID NOs: 151-153. f. Vectors Comprising CAR-encoding Polynucleotides

[0229] In certain embodiments, engineered T cells produced using the methods of the disclosure may express a CAR encoded by a polynucleotide which, optionally, may be present in a vector. In certain embodiments, the polynucleotide encodes a CAR comprising an extracellular domain, a transmembrane domain, an intracellular signaling domain and, optionally, a costimulatory domain. The extracellular domain comprises a binding domain which can comprise, e.g., an anti-CD19 scFv. In certain embodiments, the polynucleotide encodes a CAR comprising an anti-CD19 scFv, a CD8a transmembrane domain, a 4-1BB costimulatory domain, and a CD3^ signaling domain.

[0230] In certain embodiments, the vector comprises a plasmid vector, viral vector, retroviral vector, lentiviral vector, adenoviral vector, AAV, retrotransposon (e.g., piggyback, sleeping beauty), site directed insertion vector (e.g., CRISPR, Zinc finger nucleases, TALEN), or suicide expression vector, or other known vector in the art.

[0231] In certain embodiments, the vector is a viral vector, e.g., a lentiviral vector, e.g., a 3rd generation lentiviral vector, e.g., a 3rdgeneration self-inactivating lentiviral vector.

[0232] Expression of the CAR can be verified by sequencing. Expression of the full length CAR protein may be verified using immunoblot, immunohistochemistry, flow cytometry, or other technology well known and available in the art.

[0233] The present disclosure also provides a vector in which DNA encoding the CAR of the present disclosure is inserted. Vectors, including those derived from retroviruses such as lentivirus, are suitable tools to achieve long-term gene transfer since they allow long-term, stable integration of a transgene and its propagation in daughter cells. Lentiviral vectors have the added advantage over vectors derived from onco-retroviruses, such as murine leukemia viruses, in that they can transduce non-proliferating cells, such as hepatocytes. They also have the added advantage of resulting in low immunogenicity in the subject into which they are introduced.

[0234] In summary, the expression of natural or synthetic polynucleotides encoding CARs is typically achieved by operably linking a nucleic acid encoding the CAR polypeptide or portions thereof to a promoter, and incorporating the construct into an expression vector. Thevector is one generally capable of replication in a mammalian cell, and / or also capable of integration into the cellular genome of the mammal. Typical vectors contain transcription and translation terminators, initiation sequences, and promoters useful for regulation of the expression of the desired nucleic acid sequence.

[0235] The nucleic acid can be cloned into any number of different types of vectors. For example, the nucleic acid can be cloned into a vector including, but not limited to, a plasmid, a phagemid, a phage derivative, an animal virus, and a cosmid. Vectors of particular interest include expression vectors, replication vectors, probe generation vectors, and sequencing vectors.

[0236] The expression vector may be provided to a cell in the form of a viral vector. Viral vector technology is well known in the art and is described, for example, in Sambrook et al. , 2012, MOLECULAR CLONING: A LABORATORY MANUAL, volumes 1-4, Cold Spring Harbor Press, NY), and in other virology and molecular biology manuals. Viruses, which are useful as vectors include, but are not limited to, retroviruses, adenoviruses, adeno- associated viruses, herpes viruses, and lentiviruses. In general, a suitable vector contains an origin of replication functional in at least one organism, a promoter sequence, convenient restriction endonuclease sites, and one or more selectable markers, (e g., WO 2001 / 96584; WO 2001 / 29058; and U.S. Patent No. 6,326,193).

[0237] Additional promoter elements, e.g., enhancers, regulate the frequency of transcriptional initiation. Typically, these are located in the region 30-110 bp upstream of the start site, although a number of promoters have recently been shown to contain functional elements downstream of the start site as well. The spacing between promoter elements frequently is flexible, so that promoter function is preserved when elements are inverted or moved relative to one another. Depending on the promoter, it appears that individual elements can function either cooperatively or independently to activate transcription.

[0238] An example of a promoter that may be used is the immediate early cytomegalovirus (CMV) promoter sequence. This promoter sequence is a strong constitutive promoter sequence capable of driving high levels of expression of any polynucleotide sequence operatively linked thereto. Other constitutive promoter sequences may also be used, including, but not limited to the simian virus 40 (SV40) early promoter, mouse mammary tumor virus (MMTV), human immunodeficiency virus (HIV) long terminal repeat (LTR) promoter, MoMuLV promoter, an avian leukemia virus promoter, an Epstein-Barr virusimmediate early promoter, a Rous sarcoma virus promoter, the elongation factor- la promoter (EF-la), as well as human gene promoters such as, but not limited to, the actin promoter, the myosin promoter, or the hemoglobin promoter, as appropriate.

[0239] Further, the disclosure is not limited to the use of constitutive promoters. Inducible promoters are also contemplated for use in the methods and compositions of the disclosure. The use of an inducible promoter provides a molecular switch capable of turning on expression of the polynucleotide sequence, which it is operatively linked when such expression is desired, or turning off the expression when expression is not desired. Examples of inducible promoters include, but are not limited to a metallothionine promoter, a glucocorticoid promoter, a progesterone promoter, and a tetracycline promoter. In certain embodiments, an inducible promoter is activated in response to an extracellular ligand. For example, in certain embodiments, the inducible promoter is activated (and the expression of the CAR is regulated) by an extracellular ligand binding to a synthetic receptor. For example, in certain embodiments, a synthetic receptor, e.g., a synthetic Notch receptor (z.e., “synNotch”) may be employed as a binding-triggered transcriptional switch that, when bound to its ligand, activates a promoter to which a nucleic acid sequence encoding the CAR is operably linked. Accordingly, as a non-limiting example, such systems may require the presence of a ligand (e.g., to which the synNotch binds) for the immune cell to be responsive to the target cell (e.g., to which the CAR binds). The requirement of particular combinations to generate certain signaling outputs in molecular circuits results in a logic gate. See, for example, Roybal et al., 2016 CELL 164(4):770-9.

[0240] Examples of other systems for expressing or regulating expression of a chimeric receptor include those described in Wu et al. (2015) Science 350: aab4077; Fedorov et al. (2014) Cancer Journal 20: 160-165; Kloss et al. (2013) Nature Biotechnology 31: 71-75; Sakemura et al. (2016) Cancer Immunol. Res. 4:658-668; Hill et al. (2018) NAT. CHEM. BIOL. 14: 112-117; Di Stasi et al. (2011) N. ENGL. J. MED. 365: 1673-1683; Budde et a / . (2013) PLoS ONE 8: e82742; Wei et al. (2012) NATURE 488: 384-388; Ma et al. (2016) PROC. NATL. ACAD. SCI. USA 113: E450-458; Rodgers et al. (2016) PROC. NATL. ACAD. SCI. USA 113: E459-468; Kudo et al. (2014) CANCER RES. 74: 93-103, and Chen et al. (2010) PROC. NATL. ACAD. SCI. USA 107: 8531-8536.

[0241] In order to assess the expression of a CAR polypeptide or portions thereof, the expression vector to be introduced into a cell can also contain either a selectable marker gene or a reporter gene or both to facilitate identification and selection of expressing cells from thepopulation of cells sought to be transfected or infected through viral vectors. The selectable marker may be carried on a separate piece of DNA or RNA and used in a co-transfection procedure. Both selectable markers and reporter genes may be flanked with appropriate regulatory sequences to enable expression in the host cells. Useful selectable markers include, for example, antibiotic-resistance genes, such as neo and the like.

[0242] Reporter genes are used for identifying potentially transfected cells and for evaluating the functionality of regulatory sequences. In general, a reporter gene is a gene that is not present in or expressed by the recipient organism or tissue and that encodes a polypeptide whose expression is manifested by some easily detectable property, e.g., enzymatic activity. Expression of the reporter gene is assessed at a suitable time after the DNA or RNA has been introduced into the recipient cells. Suitable reporter genes may include genes encoding luciferase, beta-galactosidase, chloramphenicol acetyl transferase, secreted alkaline phosphatase, or the green fluorescent protein gene (e.g., Ui-Tei et al., 2000 FEBS LETTERS 479: 79-82). Suitable expression systems are well known and may be prepared using known techniques or obtained commercially. In general, the construct with the minimal 5 ’ flanking region showing the highest level of expression of reporter gene is identified as the promoter. Such promoter regions may be linked to a reporter gene and used to evaluate agents for the ability to modulate promoter-driven transcription.

[0243] Methods of introducing and expressing genes into a cell are known in the art. In the context of an expression vector, the vector can be readily introduced into a host cell, e.g., mammalian, bacterial, yeast, or insect cell by any method in the art. For example, the expression vector can be transferred into a host cell by physical, chemical, or biological means.

[0244] Physical methods for introducing a polynucleotide into a host cell include calcium phosphate precipitation, lipofection, particle bombardment, microinjection, electroporation, and the like. Methods for producing cells comprising vectors and / or exogenous nucleic acids are well-known in the art. See, for example, Sambrook et al. , 2012, MOLECULAR CLONING: A LABORATORY MANUAL, volumes 1-4, Cold Spring Harbor Press, NY).

[0245] Biological methods for introducing a polynucleotide of interest into a host cell include the use of DNA and RNA vectors. RNA vectors include vectors having an RNA promoter and / other relevant domains for production of an RNA transcript. Viral vectors, and especially retroviral vectors, have become the most widely used method for inserting genesinto mammalian, e.g., human cells. Other viral vectors may be derived from lentivirus, poxviruses, herpes simplex virus, adenoviruses and adeno-associated viruses, and the like. See, for example, U.S. Pat. Nos. 5,350,674 and 5,585,362.

[0246] Chemical means for introducing a polynucleotide into a host cell include colloidal dispersion systems, such as macromolecule complexes, nanocapsules, microspheres, beads, and lipid-based systems including oil-in-water emulsions, micelles, mixed micelles, and liposomes. An exemplary colloidal system for use as a delivery vehicle in vitro and in vivo is a liposome (e.g. , an artificial membrane vesicle). Other methods of targeted delivery of nucleic acids are known, such as delivery of polynucleotides with targeted nanoparticles or another suitable sub-micron sized delivery system.

[0247] In the case where a non-viral delivery system is utilized, an exemplary delivery vehicle is a liposome or lipid nanoparticle (LNP). The use of lipid formulations is contemplated for the introduction of the nucleic acids into a host cell (in vitro, ex vivo or in vivo). In another aspect, the nucleic acid may be associated with a lipid. The nucleic acid associated with a lipid may be encapsulated in the aqueous interior of a liposome, interspersed within the lipid bilayer of a liposome, attached to a liposome via a linking molecule that is associated with both the liposome and the oligonucleotide, entrapped in a liposome, complexed with a liposome, dispersed in a solution containing a lipid, mixed with a lipid, combined with a lipid, contained as a suspension in a lipid, contained or complexed with a micelle, or otherwise associated with a lipid. Lipid, lipid / DNA, lipid / RNA, or lipid / expression vector associated compositions are not limited to any particular structure in solution. For example, they may be present in a bilayer structure, as micelles, or with a “collapsed” structure. They may also simply be interspersed in a solution, possibly forming aggregates that are not uniform in size or shape. Lipids are fatty substances, which may be naturally occurring or synthetic lipids. For example, lipids include the fatty droplets that naturally occur in the cytoplasm as well as the class of compounds which contain long-chain aliphatic hydrocarbons and their derivatives, such as fatty acids, alcohols, amines, amino alcohols, and aldehydes. Examples of lipids, liposomes, lipid nanoparticles, and related formulations are described, for example, in U.S. Patent Nos. 8,058,069, 8,492,359, 8,822,668, 9,006,417, 9,139,554, 9,364,435, 9,404,127, 9,415,109, 9,504,651, 9,518,272, 9,567,296, 9,580,711, 9,636,414, 9,694,077, 9,758,795, 9,814,777, 9,868,692, 9,878,042, 9,943,846, 9,950,065, 10,041,091, 10,106,490, 10,166,298, 10,221,127, 10,227,302, 10,233,148, 10,266,485, 10,442,756, 10,485,884, 10,561,732, 10,576,146, 10,577,403,10,653,780, 10,703,789, 10,980,895, 11,045,418, 11,141,378, 11,173,120, 11,191,849, 11,285,222, 11,357,856, 11,446,383, 11,453,639, 11,478,552, 11,559,587, U.S. Patent Application Publication Nos. 2011 / 0117125, 2012 / 0264810, 2018 / 0000953, 2018 / 0085474, 2018 / 0185516, 2019 / 0022247, 2019 / 0032087, 2019 / 0274968, 2019 / 0336608, 2020 / 0046830, 2020 / 0109113, 2020 / 0155671, 2020 / 0163878, 2020 / 0164038, 2020 / 0172472, 2020 / 0297634, 2020 / 0297870, 2020 / 0306191, 2021 / 0145982, 2021 / 0207140, 2021 / 0220274, 2021 / 0346306, 2022 / 0000778, 2022 / 0001029, 2022 / 0118112, and 2022 / 0160899; and International Patent Application Publication Nos. 2008 / 042973, 2021 / 231929, and 2021 / 237084.

[0248] Lipids suitable for use can be obtained from commercial sources. For example, dimyristyl phosphatidylcholine (“DMPC”) can be obtained from Sigma, St. Louis, MO; dicetyl phosphate (“DCP”) can be obtained from K & K Laboratories (Plainview, NY); cholesterol (“Choi”) can be obtained from Calbiochem-Behring; dimyristyl phosphatidylglycerol (“DMPG”) and other lipids may be obtained from Avanti Polar Lipids, Inc. (Birmingham, AL.). Stock solutions of lipids in chloroform or chloroform / methanol can be stored at about -20 °C. Chloroform is used as the only solvent since it is more readily evaporated than methanol. “Liposome” is a generic term encompassing a variety of single and multilamellar lipid vehicles formed by the generation of enclosed lipid bilayers or aggregates. Liposomes can be characterized as having vesicular structures with a phospholipid bilayer membrane and an inner aqueous medium. Multilamellar liposomes have multiple lipid layers separated by aqueous medium. They form spontaneously when phospholipids are suspended in an excess of aqueous solution. The lipid components undergo self-rearrangement before the formation of closed structures and entrap water and dissolved solutes between the lipid bilayers (Ghosh et al. (1991) GLYCOBIOLOGY 5: 505-10). However, compositions that have different structures in solution than the normal vesicular structure are also encompassed. For example, the lipids may assume a micellar structure or merely exist as nonuniform aggregates of lipid molecules. Also contemplated are lipofectamine-nucleic acid complexes.

[0249] In certain embodiments wherein a non-viral delivery method is utilized, an exemplary delivery vehicle is a bioabsorbable silicon nanoparticle. Silicon nanoparticles can be made of either pure silicon, or a hydrolysable silicon-containing material, and can be made porous by standard techniques such as contacting the particles with a hydrofluoric acid (HF) / ethanol mixture and applying a current. The silicon nanoparticles may be loaded with a polynucleotide, e.g. , RNA, to be delivered into a host cell (e.g. , in vitro, ex vivo, or in vivo).Silicon nanoparticles may be surface-treated with a lipid (e.g., phosphatidylcholine (PC), phosphatidylethanolamine (PE), stearylamine (SA), and / or lecithin, which can aid in controlling the rate of release of the payload polynucleotide. A lipid-surface-treated silicon nanoparticle may be further treated with an amino acid (e.g., arginine, histidine, and / or glycine), which can promote stability of the payload nucleic acid, e.g., RNA. Examples of silicon nanoparticles are described, for example, in U.S. Patent No. 9,132,083, in U.S. Patent Application Publication Nos. 2022 / 0183989 and 2022 / 0184038, and in International Patent Application Publication No. 2020 / 193999.

[0250] Any domains and / or fragments of the CAR, vector, and the promoter may be synthesized gene fragments amplified by PCR or any other means known in the art.IV. Cell Therapeutic Compositions

[0251] The disclosure also provides, among other things, immune cells engineered to express a CAR comprising a CD 19 antibody or antigen-binding fragment thereof as disclosed herein. The engineered immune cell (e.g., T cells) may be administered to a subject as a cell therapeutic in order to treat a disease or disorder. The engineered immune cell can be, for example, a T cell, a B cell, an NK cell, a tumor-infiltrating lymphocyte, and / or a dendritic cell. In certain embodiments, the engineered immune cell is an NK cell. In certain embodiments, the engineered immune cell is a T cell, e.g., a CD8+ T cell or a CD4+ T cell.

[0252] In certain embodiments, an engineered immune cell of the disclosure is present in an immune cell composition. In certain embodiments, the immune cell composition comprises, for example, T cells, B cells, NK cells, tumor-infiltrating lymphocytes, and / or dendritic cells. In certain embodiments, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or at least 99% of the cells in the immune cell composition are CD8+ T cells, e.g., CD8+ T cells engineered to express a CAR. In certain embodiments, the immune cell composition further comprises CD4+ T cells, optionally wherein at least 20%, at least 30%, at least 40%, or at least 50% of the cells in the immune cell composition are CD4+ T cells, e.g., CD4+ T cells engineered to express a CAR.

[0253] In certain embodiments, the immune cell therapy (e.g. , T cell therapy) is autologous to the subject, z.e., immune cells obtained from a patient, after in vitro culture, are administered to the same patient. In certain embodiments, the immune cell therapy (e.g., T cell therapy) is allogeneic to the subject, optionally wherein the immune cells are geneticallyengineered to abrogate expression via component inactivation of class I MHC (e.g., [32M), class II (e.g., RFXANK), or TCR (e.g. TRAC, or CD3).

[0254] T cells (e.g., CD8+T cells) can have antigen specificity via a receptor expressed on the cell surface. T cells can naturally express T cell receptors (TCRs), such as a[3TCRs or ySTCRs, and can be “trained” to express TCRs that target a given antigen or epitope. T cells can also be engineered to express a recombinant TCR or a CAR. A CD19-CAR for use in the therapeutic methods disclosed herein can optionally target additional antigens or epitopes thereof beyond CD 19 that are present on an immune cell surface. In certain embodiments, the T cells are engineered to inactivate their endogenous TCRs, for example, by knocking out the TRAC or TRBC gene, to reduce ligand-independent tonic T cell signaling and enhances T cell potency.

[0255] The immune T cells (e.g., T cells) for use in adoptive cell therapy can be engineered to express a CAR of the disclosure by introducing a heterologous polynucleotide encoding the CAR. In certain embodiments, the polynucleotide is a DNA molecule (e.g, a cDNA molecule). In certain embodiments, the polynucleotide further comprises an expression control sequence (e.g., promoter and / or enhancer) operably linked to the CAR coding sequence. In certain embodiments, the immune cells (e.g., T cells) are transduced by a vector, such as a viral vector (e.g. , AAV vector, lentiviral vector, or adenoviral vector) or a non-viral vector (e.g, plasmid), comprising a polynucleotide encoding the CAR. In certain embodiments, the polynucleotide encodes an amino acid sequence comprising a signal peptide at the N-terminus of the CAR. Such a signal peptide can facilitate cell surface localization of the CAR when it is expressed in an effector cell, and is cleaved from the CAR during cellular processing.

[0256] In certain embodiments, the therapeutic methods of the disclosure comprise administering a dose of engineered immune cells (e.g., CAR T cells) to a subject in need thereof. In certain embodiments, the dose of engineered immune cells is from IxlO5cells / kg bodyweight to IxlO8cells / kg bodyweight. For example, in certain embodiments, the dose of engineered immune cells (e.g., T cells) is from IxlO5to IxlO8cells / kg, from IxlO5to IxlO6cells / kg, or from IxlO6to IxlO8cells / kg. In certain embodiments, the dose of engineered immune cells (e.g., T cells) is an effective amount of the engineered immune cells.

[0257] In certain embodiments, the dose of engineered immune cells (e.g., T cells) is at least IxlO5cells / kg. For example, in certain embodiments, the dose of engineered immunecells (e.g., T cells) is at least IxlO5cells / kg, at least IxlO6cells / kg, or at least IxlO8cells / kg. In certain embodiments, the dose of engineered immune cells (e.g., T cells) is IxlO5cells / kg, IxlO6cells / kg, or IxlO8cells / kg.

[0258] In certain embodiments, the total dose of engineered immune cells (e.g, CAR T cells) administered to the subject is from IxlO6to IxlO10cells. For example, in certain embodiments, the total dose of engineered immune cells (e.g., T cells) administered to the subject is from IxlO6to IxlO10cells, from IxlO6to IxlO8cells, or from IxlO8to IxlO10cells. In certain embodiments, the total dose of engineered immune cells (e.g., CAR T cells) administered to the subject is at least IxlO6cells. For example, in certain embodiments, the total dose of engineered immune cells (e.g., T cells) administered to the subject is at least IxlO6cells, at least IxlO8cells, or at least IxlO10cells.

[0259] In certain embodiments, the engineered immune cells (e.g., T cells) are administered to the subject in a single dose. In certain embodiments, the engineered immune cells (e.g., T cells) are administered intravenously.V. Therapeutic Uses

[0260] The disclosure also provides methods of treating diseases and disorders comprising administering an antibody or antigen-binding fragment thereof or an engineered immune cell described herein, or a composition comprising the same, to a subject in need thereof. The disease or disorder to be treated can be, e.g., an autoimmune disease or an unwanted immune response, or a cancer.

[0261] In certain instances, unwanted immune responses are mediated, at least in part, by the activity of immunoglobulins. Immunoglobulins are glycoproteins belonging to the immunoglobulin superfamily which recognize antigens and facilitate the humoral response of the immune system. Immunoglobulins may occur in two physical forms, a soluble form that is secreted from the cell, and a membrane-bound form that is attached to the surface of a B cell and is referred to as the B cell receptor (BCR). Immature B cells, which have not been exposed to an antigen, are known as naive B cells and express only the IgM isotype in a cell surface-bound form. B cells begin to express both IgM and IgD when they reach maturity, indicating that they are ready to respond to antigen. B cell activation follows engagement of the BCR with an antigen, causing the cell to divide and differentiate into an antibodyproducing plasma cell. In this activated form, the B cell starts to produce antibody in a secreted form rather than a membrane -bound form. However, B cells producing antibodiesdirected against self antigens (autoantibodies) can lead to an unwanted immune response against an organism’s own cells and tissues, thereby contributing to an autoimmune disorder.

[0262] Thus, the disclosure provides a method of treating an autoimmune disease in a subject. In certain embodiments, the method comprises administering to the subject a CD 19 antibody or an antigen-binding fragment thereof. In other embodiments, the method comprises administering to the subject engineered immune cells (e.g., T cells) expressing a CAR of the disclosure, which may target and kill B cells. In certain embodiments, the method is used to decrease the number of circulating B cells in a subject. In certain embodiments, B cells in the subject produce autoantibodies having specificity for self antigens, e.g., anti-dsDNA antibodies or anti-MuSK antibodies. In certain embodiments, the method is used to decrease the number of antibodies, e.g., autoantibodies, in a subject. In certain embodiments, the autoimmune disease is a B -cell-mediated autoimmune disease, z.e., an autoimmune disease wherein (1) at least some symptoms or manifestations of the disease are attributable to, and / or exacerbated by, immunoglobulins produced by the subject’s B cells, and / or (2) B cells have some role in initiating or maintaining the disease or a symptom or manifestation thereof.

[0263] Examples of B -cell-mediated autoimmune diseases include, but are not limited to: systemic lupus erythematosus (SLE), lupus nephritis, SLE with anti-dsDNA antibodies, pemphigus vulgaris (PV), mucosal PV, mucocutaneous PV, myasthenia gravis (MG), MuSK- associated MG, AChR MG, myositis, juvenile myositis, membranous nephropathy, antisynthetase syndrome, dermatomyositis, immune mediated necrotizing myopathy, multiple sclerosis, neuromyelitis optica, chronic inflammatory demyelinating polyneuropathy, anti- NMDA Receptor encephalitis, Lambert-Eaton syndrome, pemphigus foliaceus, epidermolysis bullosa acquisita, bullous pemphigoid, Goodpasture’s syndrome, rheumatoid arthritis, systemic sclerosis, systemic sclerosis with skin involvement, systemic sclerosis with severe organ involvement, systemic sclerosis with renal involvement, systemic sclerosis with pulmonary involvement, systemic sclerosis with cardiac involvement, anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis, immune thrombocytopenic purpura, antiphospholipid syndrome, autoimmune hemolytic anemia, type 1 diabetes, Grave’s disease, and Hashimoto’s disease. In certain embodiments, a therapeutic method described herein is used to treat any of the foregoing autoimmune diseases in a subject. In certain embodiments, a therapeutic method described herein is used to treat SLE, lupus nephritis, SLE with anti- dsDNA antibodies, PV, mucosal PV, mucocutaneous PV, MG, MuSK-associated MG, AChRMG, myositis juvenile myositis, systemic sclerosis, systemic sclerosis with skin involvement, systemic sclerosis with severe organ involvement, systemic sclerosis with renal involvement, systemic sclerosis with pulmonary involvement, systemic sclerosis with cardiac involvement, chronic immune demyelinating polyneuropathy, membranous nephropathy, anti-synthetase syndrome, dermatomyositis, or immune mediated necrotizing myopathy in a subject in need thereof. In certain embodiments, a therapeutic method described herein is used to treat SLE, PV, MG, myositis, systemic sclerosis, multiple sclerosis, membranous nephropathy, or chronic immune demyelinating polyneuropathy in a subject in need thereof. In certain embodiments, a therapeutic method described herein is used to treat SLE, lupus nephritis, SLE with anti-dsDNA antibodies, PV, mucosal PV, mucocutaneous PV, MG, MuSK-associated MG, AChR MG, myositis, juvenile myositis, systemic sclerosis with skin involvement, systemic sclerosis with severe organ involvement, systemic sclerosis with renal involvement, systemic sclerosis with pulmonary involvement, systemic sclerosis with cardiac involvement, membranous nephropathy, anti-synthetase syndrome, dermatomyositis, or immune mediated necrotizing myopathy in a subject in need thereof.

[0264] In certain embodiments, treating a subject using a method of the disclosure results in a decrease in autoantibody levels (e.g., anti-dsDNA antibody levels, anti-nuclear antibody levels, or anti-MuSK antibody levels) in the subject. For example, in certain embodiments, autoantibody levels in the subject decrease by at least 1%, at least 2%, at least 3%, at least 4%, at least 5%, at least 6%, at least 8%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5%, at least 99.6%, at least 99.7%, at least 99.8%, or at least 99.9% e.g., as compared to autoantibody levels in the subject prior to administering the treatment. In certain embodiments, treating a subject with a method of the disclosure makes autoantibody levels undetectable in the subject. Autoantibody levels can be measured using any appropriate technique known in the art including, for example, by ELISA.

[0265] In certain embodiments, treating a subject using a method of the disclosure results in a decrease in circulating B cell levels. For example, in certain embodiments, B cell levels in the subject decrease by at least 1%, at least 2%, at least 3%, at least 4%, at least 5%, at least 6%, at least 8%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5%, at least 99.6%, at least99.7%, at least 99.8%, or at least 99.9%, e.g., as compared to levels of circulating B cells in the subject prior to administering the treatment. In certain embodiments, treating a subject with a method of the disclosure makes circulating B cell levels undetectable in the subject. In certain embodiments, the decrease in circulating B cells is transient, whereby B cell levels are restored partially or completely after a period of time.

[0266] In certain embodiments, treating a subject using a method of the disclosure results in a decrease in the amount of circulating CD19+ cells. For example, in certain embodiments, the amount of circulating CD 19+ cells in the subject decreases by at least 1%, at least 2%, at least 3%, at least 4%, at least 5%, at least 6%, at least 8%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5%, at least 99.6%, at least 99.7%, at least 99.8%, or at least 99.9%, e.g., as compared to levels of circulating CD 19+ cells in the subject prior to administering the treatment. In certain embodiments, treating a subject with a method of the disclosure makes the amount of circulating CD 19+ cells undetectable in the subject. In certain embodiments, the decrease in the amount of circulating CD 19+ cells is transient, and levels are restored partially or completely after a period of time.

[0267] The compositions and methods disclosed herein can also be used to treat various forms of cancer in a subject or inhibit cancer growth in a subject. In certain embodiments, the method comprises administering to the subject a CD 19 antibody of the disclosure or an antigen-binding fragment thereof. In other embodiments, the method comprises administering to the subject engineered immune cells (e.g., T cells) expressing a CAR of the disclosure, which may target and kill cancerous cells. In certain embodiments, the methods comprise administering to the subject an effective amount of a composition of engineered immune cells (e.g., T cells) of the disclosure, either alone or in a combination with another therapeutic agent to treat the cancer in the subject. In certain embodiments, the cancer to be treated and / or the cancer cell to be targeted expresses CD 19. In certain embodiments, the cancer to be treated is a B-cell malignancy.

[0268] In certain embodiments, the cancer is selected from a lymphoma (e.g., a B-cell lymphoma, Hodgkin lymphoma, lymphoblastic lymphoma), and a leukemia (e.g., hairy cell leukemia, B-cell chronic lymphocytic leukemia, acute myeloid leukemia (AML), acute lymphoblastic leukemia). In certain embodiments, the cancer is selected from acute lymphoblastic leukemia (ALL) (including non-T-cell ALL), acute myeloid leukemia, B cellprolymphocytic leukemia, B cell acute lymphoid leukemia (“BALL”), blastic plasmacytoid dendritic cell neoplasm, Burkitt's lymphoma, chronic lymphocytic leukemia (CLL), chronic myelogenous leukemia (CML), chronic myeloid leukemia, chronic or acute leukemia, diffuse large B cell lymphoma (DLBCL), follicular lymphoma (FL), hairy cell leukemia, Hodgkin's Disease, malignant lymphoproliferative conditions, MALT lymphoma, mantle cell lymphoma, Marginal zone lymphoma, monoclonal gammapathy of undetermined significance (MGUS), multiple myeloma, myelodysplasia and myelodysplastic syndrome, non-Hodgkin's lymphoma (NHL), plasma cell proliferative disorder (including asymptomatic myeloma (smoldering multiple myeloma or indolent myeloma), plasmablastic lymphoma, plasmacytoid dendritic cell neoplasm, plasmacytomas (including plasma cell dyscrasia; solitary myeloma; solitary plasmacytoma; extramedullary plasmacytoma; and multiple plasmacytoma), POEMS syndrome (also known as Crow-Fukase syndrome; Takatsuki disease; and PEP syndrome), primary mediastinal large B cell lymphoma (PMBC), small cell- or a large cell-follicular lymphoma, splenic marginal zone lymphoma (SMZL), systemic amyloid light chain amyloidosis, T cell acute lymphoid leukemia (“TALL”), T cell lymphoma, transformed follicular lymphoma, or Waldenstrom macroglobulinemia, Mantle cell lymphoma (MCL), Transformed follicular lymphoma (TFL), Primary mediastinal B cell lymphoma (PMBCL), Multiple myeloma, and Hairy cell lymphoma / leukemia. In certain embodiments, the cancer is selected from leukemia, acute leukemia, acute lymphoblastic leukemia (ALL), B-cell ALL, acute myeloid leukemia (AML), chronic myelocytic leukemia (CML), chronic lymphocytic leukemia (CLL), transformed CLL, diffuse large B-cell lymphomas (DLBCL), follicular lymphoma, hairy cell leukemia, a lymphoma, Hodgkin’s disease, a malignant lymphoma, non-Hodgkin’s lymphoma, Burkitt’s lymphoma, multiple myeloma, and Richter’s Syndrome (Richter’s Transformation).

[0269] The methods and compositions described herein can be used alone or in combination with other therapeutic agents and / or modalities. The term administered “in combination,” as used herein, is understood to mean that two (or more) different treatments are delivered to the subject during the course of the subject’s affliction with the disorder, such that the effects of the treatments on the patient overlap at a point in time. In certain embodiments, the delivery of one treatment is still occurring when the delivery of the second begins, so that there is overlap in terms of administration. This is sometimes referred to herein as “simultaneous” or “concurrent delivery.” In other embodiments, the delivery of one treatment ends before the delivery of the other treatment begins. In certain embodiments ofeither case, the treatment is more effective because of combined administration. For example, the second treatment is more effective, e.g., an equivalent effect is seen with less of the second treatment, or the second treatment reduces symptoms to a greater extent, than would be seen if the second treatment were administered in the absence of the first treatment, or the analogous situation is seen with the first treatment. In certain embodiments, delivery is such that the reduction in a symptom, or other parameter related to the disorder is greater than what would be observed with one treatment delivered in the absence of the other. The effect of the two treatments can be partially additive, wholly additive, or greater than additive. The delivery can be such that an effect of the first treatment delivered is still detectable when the second is delivered.

[0270] In certain embodiments, a method or composition described herein (e.g., a method of treating a disease or a cell therapeutic composition for use in such a method) is administered in combination with one or more additional therapies. In certain embodiments, the additional therapy may include an anti-inflammatory, anti-angiogenic, anti-fibrotic, or anti-proliferative compound, e.g., a steroid, a biologic immunomodulator, a monoclonal antibody, an antibody fragment, an aptamer, an siRNA, an antisense molecule, a fusion protein, a bronchodilator, a statin, an anti-inflammatory agent (e.g. methotrexate), or an NSAID. In certain embodiments, the additional therapy may include a combination of therapeutics of different classes. In certain embodiments, the additional therapy may be an antibody therapy (e.g., belimumab) or a corticosteroid.

[0271] In certain embodiments wherein the disease to be treated is cancer, a method or composition described herein can administered in combination with one or more additional therapies such as surgery, radiation therapy, or administration of another therapeutic preparation. In certain embodiments, the additional therapy may include chemotherapy, e.g., a cytotoxic agent. In certain embodiments, the additional therapy may include a targeted therapy, e.g. a tyrosine kinase inhibitor, a proteasome inhibitor, or a protease inhibitor. In certain embodiments, the additional therapy may include an anti-inflammatory, anti- angiogenic, anti-fibrotic, or anti-proliferative compound, a steroid, a biologic immunomodulator, a monoclonal antibody, an antibody fragment, an aptamer, an siRNA, an antisense molecule, a fusion protein, a cytokine, a cytokine receptor, a bronchodialator, a statin, an anti-inflammatory agent (e.g. methotrexate), or an NSAID. In certain embodiments, the additional therapy may include a combination of therapeutics of different classes.

[0272] In certain embodiments, a method or composition described herein is administered in combination with a checkpoint inhibitor. The checkpoint inhibitor may, for example, be selected from a PD-1 antagonist, PD-L1 antagonist, CTLA-4 antagonist, adenosine A2A receptor antagonist, B7-H3 antagonist, B7-H4 antagonist, BTLA antagonist, KIR antagonist, LAG3 antagonist, TIM-3 antagonist, VISTA antagonist or TIGIT antagonist.

[0273] In certain embodiments, the checkpoint inhibitor is a PD-1 or PD-L1 inhibitor. PD- I is a receptor present on the surface of T-cells that serves as an immune system checkpoint that inhibits or otherwise modulates T-cell activity at the appropriate time to prevent an overactive immune response. Cancer cells, however, can take advantage of this checkpoint by expressing ligands, for example, PD-L1, that interact with PD-1 on the surface of T-cells to shut down or modulate T-cell activity. Exemplary PD-1 / PD-L1 based immune checkpoint inhibitors include antibody based therapeutics. Exemplary treatment methods that employ PD-1 / PD-L1 based immune checkpoint inhibition are described in U.S. Patent Nos.8,728,474 and 9,073,994, and EP Patent No. 1537878B1, and, for example, include the use of anti-PD-1 antibodies. Exemplary anti-PD-1 antibodies are described, for example, in U.S. Patent Nos. 8,952,136, 8,779,105, 8,008,449, 8,741,295, 9,205,148, 9,181,342, 9,102,728, 9,102,727, 8,952,136, 8,927,697, 8,900,587, 8,735,553, and 7,488,802. Exemplary anti-PD-1 antibodies include, for example, nivolumab (Opdivo®, Bristol-Myers Squibb Co.), pembrolizumab (Keytruda®, Merck Sharp & Dohme Corp.), PDR001 (Novartis Pharmaceuticals), and pidilizumab (CT-011, Cure Tech). Exemplary anti-PD-Ll antibodies are described, for example, in U.S. Patent Nos. 9,273,135, 7,943,743, 9,175,082, 8,741,295, 8,552,154, and 8,217,149. Exemplary anti-PD-Ll antibodies include, for example, atezolizumab (Tecentriq®, Genentech), duvalumab (AstraZeneca), MEDI4736, avelumab, and BMS 936559 (Bristol Myers Squibb Co.).

[0274] In certain embodiments, a method or composition described herein is administered in combination with a CTLA-4 inhibitor. In the CTLA-4 pathway, the interaction of CTLA-4 on a T-cell with its ligands (e.g., CD80, also known as B7-1, and CD86) on the surface of an antigen presenting cells (rather than cancer cells) leads to T-cell inhibition. Exemplary CTLA-4 based immune checkpoint inhibition methods are described in U.S. Patent Nos. 5,811,097, 5,855,887, 6,051,227. Exemplary anti-CTLA-4 antibodies are described in U.S. Patent Nos. 6,984,720, 6,682,736, 7,311,910; 7,307,064, 7,109,003, 7,132,281, 6,207,156, 7,807,797, 7,824,679, 8,143,379, 8,263,073, 8,318,916, 8,017,114, 8,784,815, and 8,883,984, International (PCT) Publication Nos. WO98 / 42752, WG00 / 37504, and WOOl / 14424, andEuropean Patent No. EP 1212422 Bl. Exemplary CTLA-4 antibodies include ipilimumab or tremelimumab.

[0275] Exemplary cytotoxic agents that can be administered in combination with a method or composition described herein include, for example, antimicrotubule agents, topoisomerase inhibitors, antimetabolites, protein synthesis and degradation inhibitors, mitotic inhibitors, alkylating agents, platinating agents, inhibitors of nucleic acid synthesis, histone deacetylase inhibitors (HD AC inhibitors, e.g.. vorinostat (SAHA, MK0683), entinostat (MS-275), panobinostat (LBH589), trichostatin A (TSA), mocetinostat (MGCD0103), belinostat (PXD101), romidepsin (FK228, depsipeptide)), DNA methyltransferase inhibitors, nitrogen mustards, nitrosoureas, ethylenimines, alkyl sulfonates, triazenes, folate analogs, nucleoside analogs, ribonucleotide reductase inhibitors, vinca alkaloids, taxanes, epothilones, intercalating agents, agents capable of interfering with a signal transduction pathway, agents that promote apoptosis and radiation, or antibody molecule conjugates that bind surface proteins to deliver a toxic agent. In certain embodiment, the cytotoxic agent that can be administered with a method or composition described herein is a platinum-based agent (such as cisplatin), cyclophosphamide, dacarbazine, methotrexate, fluorouracil, gemcitabine, capecitabine, hydroxyurea, topotecan, irinotecan, azacytidine, vorinostat, ixabepilone, bortezomib, taxanes (e.g., paclitaxel or docetaxel), cytochalasin B, gramicidin D, ethidium bromide, emetine, mitomycin, etoposide, tenoposide, vincristine, vinblastine, vinorelbine, colchicin, anthracyclines (e.g., doxorubicin or epirubicin) daunorubicin, dihydroxy anthracin dione, mitoxantrone, mithramycin, actinomycin D, adriamycin, 1 -dehydrotestosterone, glucocorticoids, procaine, tetracaine, lidocaine, propranolol, puromycin, ricin, or maytansinoids.

[0276] In certain embodiments of the cell therapeutic methods of the disclosure, the method comprises, prior to administration of the cell therapeutic composition, administering a preconditioning regimen to the subject in need thereof. The preconditioning regimen can comprise, for example, one or more doses of cyclophosphamide and / or fludarabine. In certain embodiments, the preconditioning regimen comprises one or more doses of oxaliplatin, busulfan, etoposide and / or cytarabine. In certain embodiments, the preconditioning regimen comprises radiation therapy, e.g, total body irradiation.VI. Methods of Preparing Antibodies

[0277] Methods for producing antibodies, e.g., those disclosed herein, are known in the art. For example, DNA molecules encoding light chain variable regions and / or heavy chain variable regions can be synthesized chemically or by recombinant DNA methodologies. For example, the sequences of the antibodies can be cloned from hybridomas by conventional hybridization techniques or polymerase chain reaction (PCR) techniques, using the appropriate synthetic nucleic acid primers. The resulting DNA molecules encoding the variable regions of interest can be ligated to other appropriate nucleotide sequences, including, for example, constant region coding sequences, and expression control sequences, to produce conventional gene expression constructs (i. e. , expression vectors) encoding the desired antibodies. Production of defined gene constructs is within routine skill in the art.

[0278] Nucleic acids encoding desired antibodies can be incorporated (ligated) into expression vectors, which can be introduced into host cells through conventional transfection or transformation techniques. Exemplary host cells are E. coli cells, Chinese hamster ovary (CHO) cells, human embryonic kidney 293 (HEK 293) cells, HeLa cells, baby hamster kidney (BHK) cells, monkey kidney cells (COS), human hepatocellular carcinoma cells (e.g., Hep G2), and myeloma cells that do not otherwise produce IgG protein. Transformed host cells can be grown under conditions that permit the host cells to express the genes that encode the immunoglobulin light and / or heavy chain variable regions.

[0279] Specific expression and purification conditions will vary depending upon the expression system employed. For example, if a gene is to be expressed in E. coli, it is first cloned into an expression vector by positioning the engineered gene downstream from a suitable bacterial promoter, e.g., Trp or Tac, and a prokaryotic signal sequence. The expressed protein may be secreted. The expressed protein may accumulate in refractile or inclusion bodies, which can be harvested after disruption of the cells by French press or sonication. The refractile bodies then are solubilized, and the protein may be refolded and / or cleaved by methods known in the art.

[0280] If the engineered gene is to be expressed in eukaryotic host cells, e.g., CHO cells, it is first inserted into an expression vector containing a suitable eukaryotic promoter, a secretion signal, a poly A sequence, and a stop codon. Optionally, the vector or gene construct may contain enhancers and introns. In certain embodiments, the expression vector optionally contains sequences encoding all or part of a constant region, enabling an entire, ora part of, a heavy or light chain to be expressed. The gene construct can be introduced into eukaryotic host cells using conventional techniques.

[0281] In certain embodiments, the host cells express an antibody comprising VL or VH fragments, VL-VH heterodimers, VH-VL or VL-VH single chain polypeptides, complete heavy or light immunoglobulin chains, or portions thereof, each of which may be attached to a moiety having another function (e.g, cytotoxicity).

[0282] A polypeptide comprising an antibody, e.g., an antibody comprising an immunoglobulin heavy chain variable region and / or light chain variable region, can be produced by growing (culturing) a host cell transfected with an expression vector encoding such a variable region, under conditions that permit expression of the polypeptide. Following expression, the polypeptide can be harvested and purified or isolated using techniques known in the art, e.g., affinity tags such as glutathione-S-transferase (GST) or histidine tags.

[0283] In certain embodiments, an antibody disclosed herein may comprise a single polypeptide chain. In this instance, a host cell can be transfected with a single vector expressing the polypeptide (e.g., containing an expression control sequence operably linked to a nucleotide sequence encoding the polypeptide). Alternatively, an antibody disclosed herein may comprise two or more polypeptides. In this instance, a host cell can be cotransfected with more than one expression vector, for example, one expression vector expressing each polypeptide. A host cell can also be transfected with a single expression vector that expresses the two or more polypeptides. For example, the coding sequences of the two or more polypeptides can be operably linked to different expression control sequences (e.g, promoter, enhancer, and / or internal ribosome entry site (IRES)). The coding sequences of the two or more polypeptides can also be separated by a ribosomal skipping sequence or self-cleaving sequence, such as a 2A peptide.

[0284] In certain embodiments, an antibody can be produced by growing (culturing) a host cell transfected with: (a) an expression vector that encodes a complete or partial immunoglobulin heavy chain, and a separate expression vector that encodes a complete or partial immunoglobulin light chain; or (b) a single expression vector that encodes both chains (e.g., complete or partial heavy and light chains), under conditions that permit expression of both chains. The intact antibody can be harvested and purified or isolated using techniques known in the art, e.g., Protein A, Protein G, affinity tags such as glutathione-S-transferase(GST) or histidine tags. It is within ordinary skill in the art to express the heavy chain and the light chain from a single expression vector or from two separate expression vectors.

[0285] In certain embodiments, in order to express a protein, e.g., an antibody, as a secreted protein, an N-terminal signal sequence is included in the protein construct. Exemplary N- terminal signal sequences include signal sequences from interleukin-2, CD-5, IgG kappa light chain, trypsinogen, serum albumin, and prolactin.

[0286] Methods for reducing or eliminating the antigenicity of antibodies and antibody fragments are known in the art. When the antibodies are to be administered to a human, the antibodies may be “humanized” to reduce or eliminate antigenicity in humans. Preferably, each humanized antibody has the same or substantially the same affinity for the antigen as the non-humanized mouse antibody from which it was derived.

[0287] In one humanization approach, chimeric proteins are created in which mouse immunoglobulin constant regions are replaced with human immunoglobulin constant regions. See, e.g., Morrison et al. , 1984, PROC. NAT. ACAD. SCI. 81:6851-6855, Neuberger et al., 1984, NATURE 312:604-608; U.S. Patent Nos. 6,893,625 (Robinson); 5,500,362 (Robinson); and 4,816,567 (Cabilly).

[0288] In an approach known as CDR grafting, the CDRs of the light and heavy chain variable regions are grafted into frameworks from another species. For example, murine CDRs can be grafted into human FRs. In some embodiments, the CDRs of the light and heavy chain variable regions of an antibody are grafted into human FRs or consensus human FRs. To create consensus human FRs, FRs from several human heavy chain or light chain amino acid sequences are aligned to identify a consensus amino acid sequence. CDR grafting is described in U.S. Patent Nos. 7,022,500 (Queen); 6,982,321 (Winter); 6,180,370 (Queen);6,054,297 (Carter); 5,693,762 (Queen); 5,859,205 (Adair); 5,693,761 (Queen); 5,565,332 (Hoogenboom); 5,585,089 (Queen); 5,530,101 (Queen); Jones et al. (1986) NATURE 321: 522-525; Riechmann et al. (1988) NATURE 332: 323-327; Verhoeyen et al. (1988) SCIENCE 239: 1534-1536; and Winter (1998) FEBS EETT. 430: 92-94.

[0289] In an approach called “SUPERHUMANIZATION™,” human CDR sequences are chosen from human germline genes, based on the structural similarity of the human CDRs to those of the mouse antibody to be humanized. See, e.g., U.S. Patent No. 6,881,557 (Foote); and Tan et al., 2002, J. IMMUNOL. 169: 1119-1125.

[0290] Other methods to reduce immunogenicity include “reshaping,” “hyperchimerization,” and “veneering / resurfacing.” See, e.g., Vaswami et al., 1998, ANNALS OF ALLERGY, ASTHMA, & IMMUNOL. 81: 105; Roguska et a / ., 1996, PROT. ENGINEER 9:895 - 904; and U.S. Patent No. 6,072,035 (Hardman). In the veneering / resurfacing approach, the surface accessible amino acid residues in the murine antibody are replaced by amino acid residues more frequently found at the same positions in a human antibody. This type of antibody resurfacing is described, e.g., in U.S. Patent No. 5,639,641 (Pedersen).

[0291] Another approach for converting a mouse antibody into a form more suitable for medical use in humans is known as ACTIVMAB™ technology (Vaccinex, Inc., Rochester, NY), which involves a vaccinia virus-based vector to express antibodies in mammalian cells. High levels of combinatorial diversity of IgG heavy and light chains can be produced. See, e.g., U.S. Patent Nos. 6,706,477 (Zauderer); 6,800,442 (Zauderer); and 6,872,518 (Zauderer). Another approach for converting a mouse antibody into a form more suitable for use in humans is technology practiced commercially by KaloBios Pharmaceuticals, Inc. (Palo Alto, CA). This technology involves the use of a proprietary human “acceptor” library to produce an “epitope focused” library for antibody selection. Another approach for modifying a mouse antibody into a form more suitable for medical use in humans is HUMAN ENGINEERING™ technology, which is practiced commercially by XOMA (US) LLC. See, e.g., International (PCT) Publication No. WO 93 / 11794 and U.S. Patent Nos. 5,766,886 (Studnicka); 5,770,196 (Studnicka); 5,821,123 (Studnicka); and 5,869,619 (Studnicka).

[0292] Any suitable approach, including any of the above approaches, can be used to reduce or eliminate human immunogenicity of an antibody.

[0293] In addition, it is possible to create fully human antibodies in mice. Fully human mAbs lacking any non-human sequences can be prepared from human immunoglobulin transgenic mice by techniques referenced in, e.g., Lonberg et al., NATURE 368:856-859, 1994; Fishwild et al., NAT. BIOTECH. 14:845-851, 1996; and Mendez et al., NAT. GENET. 15: 146- 156, 1997. Fully human monoclonal antibodies can also be prepared and optimized from phage display libraries by techniques referenced in, e.g., Knappik et al., J. MOL. BIOL. 296:57-86, 2000; and Krebs et al., J. IMMUNOL. METH 254:67-84 2001).

[0294] The present disclosure encompasses antibody fragments, or fusion proteins comprising antibody fragments, which may be generated by traditional means, such asenzymatic digestion, or by recombinant techniques. For a review of certain antibody fragments, see Hudson et al. (2003) NAT. MED. 9: 129-134.

[0295] Various techniques have been developed for the production of antibody fragments. Traditionally, these fragments were derived via proteolytic digestion of intact antibodies (see, e.g. , Morimoto et al. ( 1992) JOURNAL OF BIOCHEMICAL AND BIOPHYSICAL METHODS 24: 107- 117; and Brennan et al. (1985) SCIENCE 229:81). However, these fragments can now be produced directly by recombinant host cells. Fab, Fv and scFv antibody fragments can all be expressed in and secreted from E. coll, thus allowing the facile production of large amounts of these fragments. Antibody fragments can be isolated from the antibody phage libraries. Alternatively, Fab’-SH fragments can be directly recovered from E. coll and chemically coupled to form F(ab’)2 fragments (Carter et al. (1992) BIO / TECHNOLOGY 10: 163-167). According to another approach, F(ab’)2 fragments can be isolated directly from recombinant host cell culture. Fab and F(ab’)2 fragments with increased in vivo half-life comprising salvage receptor binding epitope residues are described in U.S. Patent No. 5,869,046. Other techniques for the production of antibody fragments will be apparent to the skilled practitioner. In certain embodiments, an antibody is a single chain Fv fragment (scFv). See U.S. Patent Nos. 5,571,894 and 5,587,458.

[0296] Methods for making bispecific antibodies are known in the art. See Milstein and Cuello (1983) NATURE 305:537, International (PCT) Publication No. WO93 / 08829, and Traunecker et al. (1991) EMBO J., 10:3655. For further details of generating bispecific antibodies see, for example, Suresh et al. (1986) METHODS ENZYMOL. 121:210. Bispecific antibodies include cross-linked or “heteroconjugate” or “heterodimer” antibodies. For example, one of the antibodies in the heterodimer can be coupled to avidin, the other to biotin. Heterodimer antibodies may be made using any convenient cross-linking method. Suitable cross-linking agents are well known in the art, and are disclosed in U.S. Patent No. 4,676,980, along with a number of cross-linking techniques.

[0297] Examples of heterodimeric or asymmetric IgG-like molecules include but are not limited to those obtained with the following technologies or using the following formats: Triomab / Quadroma, Knobs-into-Holes, CrossMabs, electrostatically-matched antibodies, LUZ-Y, Strand Exchange Engineered Domain body, Biclonic and DuoBody.

[0298] Advantages of using antibody fragments (e.g., F(ab), F(ab’)2, or scFv fragments) include the elimination of non-specific binding between Fc portions of antibodies and Fcreceptors on cells (such as macrophages, dendritic cells, neutrophils, NK cells and B cells). In addition, they may be able to penetrate tissues more efficiently due to their smaller size.

[0299] Heterodimeric antibodies, or asymmetric antibodies, allow for greater flexibility and new formats for attaching a variety of drugs to the antibody arms. One of the general formats for creating a heterodimeric antibody is the “knobs-into-holes” format. This format is specific to the heavy chain part of the constant region in antibodies. The “knobs” part is engineered by replacing a small amino acid with a larger one, which fits into a “hole”, which is engineered by replacing a large amino acid with a smaller one. What connects the “knobs” to the “holes” are the disulfide bonds between each chain. The “knobs-into-holes” shape facilitates antibody dependent cell-mediated cytotoxicity. Single chain variable fragments (scFv) are connected to the variable domain of the heavy and light chain via a short linker peptide. The linker is rich in glycine, which gives it more flexibility, and serine / threonine, which gives it specificity. Two different scFv fragments can be connected together, via a hinge region, to the constant domain of the heavy chain or the constant domain of the light chain. This gives the antibody bispecificity, allowing for the binding specificities of two different antigens. The “knobs-into-holes” format enhances heterodimer formation but doesn’t suppress homodimer formation.Several approaches to support heterodimerization have been described, for example in International (PCT) Publication Nos. WO96 / 27011, W098 / 050431, W02007 / 110205, W02007 / 147901, W02009 / 089004, W02010 / 129304, WO2011 / 90754, WO2011 / 143545, WO2012 / 058768, WO2013 / 157954, and WO2013 / 096291, and European Patent Publication No. EP 1870459. Typically, in the approaches known in the art, the CEE domain of the first heavy chain and the CH3 domain of the second heavy chain are both engineered in a complementary manner so that the heavy chain comprising one engineered CH3 domain can no longer homodimerize with another heavy chain of the same structure (e.g., a CH3- engineered first heavy chain can no longer homodimerize with another CHi-cnginccrcd first heavy chain; and a CHs-engineered second heavy chain can no longer homodimerize with another CHs-engineered second heavy chain). Thereby the heavy chain comprising one engineered CH3 domain is forced to heterodimerize with another heavy chain comprising the CH3 domain, which is engineered in a complementary manner. As a result, the CH3 domain of the first heavy chain and the CH3 domain of the second heavy chain are engineered in a complementary manner by amino acid substitutions, such that the first heavy chain and thesecond heavy chain are forced to heterodimerize, whereas the first heavy chain and the second heavy chain can no longer homodimerize (e.g., for steric reasons).VII. Pharmaceutical Compositions

[0300] For therapeutic use, an agent (e.g. , an antibody or antigen-binding fragment thereof) or a cell (e.g, a CD19-CAR immune cell) disclosed herein preferably is present in a pharmaceutical composition, optionally wherein the composition comprises a pharmaceutically acceptable carrier. a. Compositions Comprising an Antibody or Antigen-binding Fragment Thereof

[0301] For therapeutic use, an antibody preferably is combined with a pharmaceutically acceptable carrier. Pharmaceutically acceptable carriers include any of the standard pharmaceutical carriers, such as a phosphate buffered saline solution, water, emulsions (e.g., such as an oil / water or water / oil emulsions), and various types of wetting agents. The compositions also can include stabilizers and preservatives. For examples of carriers, stabilizers and adjuvants, see, e.g., Adeboye Adejare, Remington: The Science and Practice of Pharmacy (23d ed. 2020). Pharmaceutically acceptable carriers include buffers, solvents, dispersion media, coatings, isotonic and absorption delaying agents, and the like, that are compatible with pharmaceutical administration. The use of such media and agents for pharmaceutically active substances is known in the art.

[0302] In certain embodiments, a pharmaceutical composition may contain formulation materials for modifying, maintaining or preserving, for example, the pH, osmolarity, viscosity, clarity, color, isotonicity, odor, sterility, stability, rate of dissolution or release, adsorption or penetration of the composition. In such embodiments, suitable formulation materials include, but are not limited to, amino acids (such as glycine, glutamine, asparagine, arginine or lysine); antimicrobials; antioxidants (such as ascorbic acid, sodium sulfite or sodium hydrogen-sulfite); buffers (such as borate, bicarbonate, Tris-HCl, citrates, phosphates or other organic acids); bulking agents (such as mannitol or glycine); chelating agents (such as ethylenediamine tetraacetic acid (EDTA)); complexing agents (such as caffeine, polyvinylpyrrolidone, beta-cyclodextrin or hydroxypropyl -beta-cyclodextrin); fillers; monosaccharides; disaccharides; and other carbohydrates (such as glucose, mannose or dextrins); proteins (such as serum albumin, gelatin or immunoglobulins); coloring, flavoring and diluting agents; emulsifying agents; hydrophilic polymers (such as polyvinylpyrrolidone); low molecular weight polypeptides; salt-forming counterions (such assodium); preservatives (such as benzalkonium chloride, benzoic acid, salicylic acid, thimerosal, phenethyl alcohol, methylparaben, propylparaben, chlorhexidine, sorbic acid or hydrogen peroxide); solvents (such as glycerin, propylene glycol or polyethylene glycol); sugar alcohols (such as mannitol or sorbitol); suspending agents; surfactants or wetting agents (such as pluronics, PEG, sorbitan esters, polysorbates such as polysorbate 20, polysorbate, triton, tromethamine, lecithin, cholesterol, tyloxapal); stability enhancing agents (such as sucrose or sorbitol); tonicity enhancing agents (such as alkali metal halides, preferably sodium or potassium chloride, mannitol sorbitol); delivery vehicles; diluents; excipients and / or pharmaceutical adjuvants (see, Remington ’s Pharmaceutical Sciences, 18th ed. (Mack Publishing Company, 1990).

[0303] In certain embodiments, a pharmaceutical composition may contain nanoparticles, e.g., polymeric nanoparticles, liposomes, or micelles (see, Anselmo et al. (2016) BIOENG. TRANSL. MED. 1: 10-29).

[0304] In certain embodiments, a pharmaceutical composition may contain a sustained- or controlled-delivery formulation. Techniques for formulating sustained- or controlled- delivery means, such as liposome carriers, bio-erodible microparticles or porous beads and depot injections, are also known to those skilled in the art. Sustained-release preparations may include, e.g., porous polymeric microparticles or semipermeable polymer matrices in the form of shaped articles, e.g., fdms, or microcapsules. Sustained release matrices may include polyesters, hydrogels, polylactides, copolymers of L-glutamic acid and gamma ethyl-L- glutamate, poly (2-hydroxyethyl-inethacrylate), ethylene vinyl acetate, or poly-D(-)-3- hydroxybutyric acid. Sustained release compositions may also include liposomes that can be prepared by any of several methods known in the art.

[0305] Pharmaceutical compositions containing an antibody disclosed herein can be presented in a dosage unit form and can be prepared by any suitable method. A pharmaceutical composition should be formulated to be compatible with its intended route of administration. Examples of routes of administration are intravenous (IV), intradermal, inhalation, transdermal, topical, transmucosal, intrathecal and rectal administration. In certain embodiments, an antibody disclosed herein is administered by IV infusion. In certain embodiments, an antibody disclosed herein is administered by intratumoral injection. Useful formulations can be prepared by methods known in the pharmaceutical art. For example, see Adeboye Adejare, Remington: The Science and Practice of Pharmacy (23d ed. 2020).Formulation components suitable for parenteral administration include a sterile diluent suchas water for injection, saline solution, fixed oils, polyethylene glycols, glycerin, propylene glycol or other synthetic solvents; antibacterial agents such as benzyl alcohol or methyl parabens; antioxidants such as ascorbic acid or sodium bisulfite; chelating agents such as EDTA; buffers such as acetates, citrates or phosphates; and agents for the adjustment of tonicity such as sodium chloride or dextrose.

[0306] For intravenous administration, suitable carriers include physiological saline, bacteriostatic water, Cremophor ELTM (BASF, Parsippany, NJ) or phosphate buffered saline (PBS). The carrier should be stable under the conditions of manufacture and storage, and should be preserved against microorganisms. The carrier can be a solvent or dispersion medium containing, for example, water, ethanol, polyol (for example, glycerol, propylene glycol, and liquid polyethylene glycol), and suitable mixtures thereof.

[0307] In certain embodiments, a pharmaceutical composition may contain a stabilizing agent. In certain embodiments, the stabilizing agent is a cation, such as a divalent cation. In certain embodiments, the cation is calcium or magnesium. The cation can be in the form of a salt, such as calcium chloride (CaCh) or magnesium chloride (MgCh).

[0308] In certain embodiments, the stabilizing agent is present in an amount from about 0.05 mM to about 5 mM. For example, the stabilizing agent may be present in an amount of from about 0.05 mM to about 4 mM, from about 0.05 mM to about 3 mM, from about 0.05 mM to about 2 mM, from about 0.05 mM to about 1 mM, from about 0.05 mM to about 0.5 mM, from about 0.5 mM to about 4 mM, from about 0.5 mM to about 3 mM, from about 0.5 mM to about 2 mM, from about 0.5 mM to about 1 mM, from about 1 mM to about 4 mM, from about 1 mM to about 3 mM, of from about 1 mM to about 2 mM.

[0309] Pharmaceutical formulations preferably are sterile. Sterilization can be accomplished by any suitable method, e.g., fdtration through sterile filtration membranes. Where the composition is lyophilized, filter sterilization can be conducted prior to or following lyophilization and reconstitution.

[0310] The compositions described herein may be administered locally or systemically. Administration will generally be parenteral administration. In a preferred embodiment, the pharmaceutical composition is administered subcutaneously and in an even more preferred embodiment intravenously. Preparations for parenteral administration include sterile aqueous or non-aqueous solutions, suspensions, and emulsions.

[0311] Generally, a therapeutically effective amount of active component, for example, an antibody, is in the range of 0.1 mg / kg to 100 mg / kg, e.g., 1 mg / kg to 100 mg / kg, 1 mg / kg to 10 mg / kg. The amount administered will depend on variables such as the type and extent of disease or indication to be treated, the overall health of the patient, the in vivo potency of the antibody, the pharmaceutical formulation, and the route of administration. The initial dosage can be increased beyond the upper level in order to rapidly achieve the desired blood-level or tissue-level. Alternatively, the initial dosage can be smaller than the optimum, and the daily dosage may be progressively increased during the course of treatment. Human dosage can be optimized, e.g., in a conventional Phase I dose escalation study designed to run from 0.5 mg / kg to 20 mg / kg. Dosing frequency can vary, depending on factors such as route of administration, dosage amount, serum half-life of the antibody, fusion protein, and / or antibody conjugate, and the disease being treated. Exemplary dosing frequencies are once per day, once per week and once every two weeks. A preferred route of administration is parenteral, e.g., intravenous infusion. In certain embodiments, an antibody is lyophilized, and then reconstituted in buffered saline, at the time of administration. b. Compositions Comprising an Engineered Immune Cell

[0312] As described hereinabove, the engineered immune cells of the disclosure are useful in immune cell therapies (e.g., adoptive immune cell therapies, e.g., for the treatment of an autoimmune disease or cancer). Accordingly, the present disclosure provides compositions comprising one or more engineered immune cells as described herein. In certain embodiments, the one or more engineered immune cells are present in a pharmaceutical composition, e.g., wherein the composition comprises a pharmaceutically acceptable carrier.

[0313] In certain embodiments, the immune cell therapy is autologous, i.e., immune cells obtained from a patient, after in vitro / ex vivo culture, are administered to the same patient. In certain embodiments, the immune cell therapy is allogeneic and the immune cells are obtained from a healthy donor, optionally wherein the immune cells (e.g., T cells) are genetically engineered to inactivate or lack expression of a functional T cell receptor (TCR) and / or a human leukocyte antigen (HLA) molecule, e.g., an HLA class I component or an HLA class II component. For example, in certain embodiments, an allogeneic T cell can be engineered to have reduced or no expression of a functional TCR on its surface, or engineered to have reduced or no expression of one or more subunits that comprise a functional TCR (e.g., the TCR a chain or the TCR [3 chain). Alternatively, the T cell can express a functionally impaired TCR, e.g., by expression of mutated or truncated forms ofone or more of the subunits of the TCR. In certain embodiments, an allogeneic T cell can be engineered to have reduced or no expression of a functional HLA molecule on its surface, e.g. , reduced or no expression of an HLA class I molecule or an HLA class II molecule. In certain embodiments, surface expression of an HLA class I molecule is reduced in an allogeneic T cell by targeting or knocking out a sequence encoding beta-2 microglobulin (P2M). In certain embodiments, surface expression of an HLA class II molecule is reduced in an allogeneic T cell by targeting or knocking out a sequence encoding CIITA. Such cells can be created through the use of a gene editing systems as described herein. In embodiments, gene editing systems targeting sequences encoding TCR a chain, TCR P chain, P2M, and / or CIITA are introduced into the cells, such that surface expression of functional TCR, HLA class I molecules, and / or HLA class II molecules is downregulated. In some embodiments, the allogeneic T cell can lack a functional TCR and a functional HLA molecule, e.g., an HLA class I molecule and / or an HLA class II molecule.

[0314] An immune cell therapy can be provided as a cell composition. In certain embodiments, the engineered immune cell in the composition is an NK cell, e.g., a CARNK cell. In certain embodiments, the engineered immune cell in the composition is a T cell, e.g., a CAR T cell. It is understood that other types of cells, such as APCs, may be used for expanding T cells ex vivo. As such, the cell composition may include other cell types in addition to T cells. In certain embodiments, the cell composition has been enriched for T cells. Where the T cells are prepared by stimulation using APCs in an ex vivo cell culture, the T cells can be enriched by methods known in the art. For example, in certain embodiments, the APCs are removed from the cell culture by surface marker-based magnetic bead selection or cell sorting. In certain embodiments, the APCs are outgrown by T cells under conditions (e.g., cytokines) that preferably support T cell proliferation. In certain embodiments, the APCs are removed by their stronger adherence to tissue culture plate than T cells. The enrichment can produce a composition in which at least 70%, at least 80%, at least 90%, at least 95%, or at least 99% of the cells in the composition are T cells. In certain embodiments, the composition is substantially free of myeloid cells. For example, in certain embodiments, the percentage of myeloid cells relative to all cells in the composition is 20% or less, 10% or less, 5% or less, 4% or less, 3% or less, 2% or less, or 1% or less.

[0315] In certain embodiments, an immune cell composition may comprise one or more immunogenicity enhancing adjuvants (also referred to as “adjuvants” herein). Such adjuvants are substances that enhance or potentiate the immune response (e.g., immune responsesmediated by CD8-positive T cells and helper-T (TH) cells to an antigen) in a non-antigen- specific manner, and would thus be considered useful in a pharmaceutical composition disclosed herein. Suitable adjuvants include, but are not limited to, 1018 ISS, aluminum salts, AMPLIVAX®, AS15, BCG, CP-870,893, CpG7909, CyaA, dSLIM, flagellin or TLR5 ligands derived from flagellin, FLT3 ligand, GM-CSF, IC30, IC31, Imiquimod (ALDARA®), resiquimod, IMUFACT®, IMP321, interleukins as IL-2, IL-13, IL-21, interferon-a or -[3, or pegylated derivatives thereof, IS Patch, ISS, ISCOMATRIX, ISCOMs, JUVIMMUNE®, LIPOVAC®, MALP2, MF59, monophosphoryl lipid A, Montanide IMS 1312, Montanide ISA 206, Montanide ISA 50V, Montanide ISA-51, water-in-oil and oil-in- water emulsions, OK-432, OM-174, OM-197-MP-EC, ONTAK®, OspA, poly(lactide coglycolide) [PLG] -based and dextran microparticles, talactoferrin SRL 172, VEGF trap, R848, beta-glucan, Pam3Cys, Aquila's QS21 stimulon, which is derived from saponin, mycobacterial extracts and synthetic bacterial cell wall mimics, and other proprietary adjuvants such as Ribi's Detox, QUIL®, or Superfos. Depending upon the circumstances, adjuvants such as Freund's or GM-CSF may be preferred. Several immunological adjuvants (e.g., MF59) specific for dendritic cells and their preparation have been described previously (Ott et al. (1995) PHARM BIOTECHNOL. 6: 277-96). In certain embodiments, an adjuvant is a naturally occurring adjuvant. In certain embodiments, an adjuvant is a non-naturally occurring adjuvant.

[0316] The immune cell therapy compositions can further comprise one or more carriers and / or excipients. Exemplary carriers and excipients are described herein (see the “Compositions Comprising an Antibody or Antigen-binding Fragment Thereof’ subsection above).

[0317] The therapeutically effective amount of the engineered immune cells to be administered may depend on variables such as the type and extent of disease or indication to be treated, the overall health of the patient, the in vivo potency of the engineered immune cells, the pharmaceutical formulation, and the route of administration. A preferred route of administration is intravenous infusion.

[0318] Throughout the description, where compositions are described as having, including, or comprising specific components, or where processes and methods are described as having, including, or comprising specific steps, it is contemplated that, additionally, there are compositions of the present disclosure that consist essentially of, or consist of, the recited components, and that there are processes and methods according to the present disclosure thatconsist essentially of, or consist of, the recited processing steps. Similarly, throughout the description, where compositions are described as consisting essentially of specific components, or where processes and methods are described as consisting essentially of specific steps, it is contemplated that, additionally, there are compositions of the present disclosure that consist of the recited components, and that there are processes and methods according to the present disclosure that consist of the recited processing steps.

[0319] In the application, where an element or component is said to be included in and / or selected from a list of recited elements or components, it should be understood that the element or component can be any one of the recited elements or components, or the element or component can be selected from a group consisting of two or more of the recited elements or components.

[0320] Further, it should be understood that elements and / or features of a composition or a method described herein can be combined in a variety of ways without departing from the spirit and scope of the present disclosure, whether explicit or implicit herein. For example, where reference is made to a particular compound, that compound can be used in various embodiments of compositions of the present disclosure and / or in methods of the present disclosure, unless otherwise understood from the context. In other words, within this application, embodiments have been described and depicted in a way that enables a clear and concise application to be written and drawn, but it is intended and will be appreciated that embodiments may be variously combined or separated without parting from the present teachings and disclosure. For example, it will be appreciated that all features described and depicted herein can be applicable to all aspects of the disclosure described and depicted herein.

[0321] It should be understood that the expression “at least one of’ includes individually each of the recited objects after the expression and the various combinations of two or more of the recited objects unless otherwise understood from the context and use. The expression “and / or” in connection with three or more recited objects should be understood to have the same meaning unless otherwise understood from the context.

[0322] It should be understood that the order of steps or order for performing certain actions is immaterial so long as the method remains operable. Moreover, two or more steps or actions may be conducted simultaneously.

[0323] The use of any and all examples, or exemplary language herein, for example, “such as” or “including,” is intended merely to illustrate better the present invention and does not pose a limitation on the scope of the invention unless claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the present disclosure.EXAMPLES

[0324] The following Examples are merely illustrative and are not intended to limit the scope or content of the invention in any way.Example 1

[0325] This example describes a phage-display antibody campaign to identify fully human anti-CD19 antibodies.

[0326] A phage-display library of scFvs comprising a fully human antigen-binding site was screened using standard techniques to identify antibody variants with affinity for human CD19, yielding 122 unique clones with clear or equivocal affinity for the target antigen. For the top 96 antibody clones, CD19-binding affinity was measured by surface plasmon resonance using an Octet HTX instrument, and KD, Kon, and KOff values were calculated for each antibody. 90 of the 96 clones were found to be clear binders, including 10 tight binders, 55 medium binders, and 25 weak binders.

[0327] The binding affinity of the 96 clones to cell-surface-expressed CD 19 was also assessed by flow cytometry, and results were quantified as the fold-change in the geometric mean fluorescence intensity (gFMI). Of the 96 antibodies screened, 59 exhibited detectable binding to CD19-expressing CH0-K1 cells. 46 binders exhibited an at least three-fold increase in cell-binding over background, and 13 additional binders exhibited a 2- to 3 -fold increase in CD19-binding over background. 10 CD19 binders were selected for further investigation based on both the SPR and cell-binding assays. The sequences of the VH, VL, and CDRs of each of these 10 binders are summarized in TABLES 1-3. The SPR and flow cytometry results for each of these 10 binders are summarized in TABLE 5. The CD 19- binding affinity of the anti-CD19 scFv FMC63 was measured and quantified using the same assays (TABLE 5)TABLE 5. CD19-binding affinity for 10 antibody clonesExample 2

[0328] This example describes screening CARs comprising fully human CD19-binders for expression and cytotoxicity.Generation of CD19-CAR viral vectors

[0329] The 10 anti-CD19 scFvs identified in Example 1 were cloned into lentiviral expression vectors to generate anti-CD19 CAR constructs. Briefly, a DNA encoding an antiCD 19 scFv was synthesized as a gBlock™ (IDT) and cloned into the pALD plasmid backbone (Aldevron) using either restriction digest or Gibson cloning. The resultant CAR constructs contained a CD8 extracellular hinge, a CD8 transmembrane domain, a 4- IBB costimulatory domain, and a CD3zeta intracellular signaling domain, as shown schematically in FIGURE 1

[0330] VPC cells were transfected with the resulting packaging plasmids and appropriate lentiviral vector production plasmids (VSV-G, Rev-K, and Gag-Pol; Aldevron) using an LV- MAX transfection kit. Lentivirus-containing supernatant was harvested after 48 hours, filtered through a 0.45-micron polyethersulfone (PES) membrane, and concentrated using either ultracentrifugation at 62,976xg for 108 minutes at 4 °C or Tangential Flow Filtration (TFF) for 1 hour at room temperature, and the resulting concentrates were stored at -80 °C.Viral titer assays were used to determine vector titers in both Jurkat T cells and PBMCs via serial dilutions and flow cytometry. Titers were analyzed on FlowJo and Excel, and then used to generate small-scale CAR-Ts for further study.Analyzing CD19-CAR Expression and Functional Titers

[0331] Lentiviral vectors were transiently transfected into HEK293 derivative cells (Expi293 cells) to assess expression of each anti-CD19-CAR. Non-transfected cells and cells transfected with a vector encoding an FMC63-based CAR were used as controls. Cells were stained with CD19-CAR detection reagent (Miltenyi, 130-129-55; biotin-conjugated CD19 antigen) and PE streptavidin (BD Bioscience, 554061), and CAR expression was assessed by flow cytometry. Results were quantified as the percentage of CAR-expressing cells. As shown in FIGURE 2, seven out of the ten CARs comprising a fully human CD 19 binding domain expressed well. Clones D09, F10, and G04 showed less than 15% positive staining against the CD19-CAR detection agent. Lentiviral vectors were also transfected into Jurkat T cells to conduct functional titers and further assess transduction efficiency. Jurkat T cells transfected with an FMC63-based CAR were used as a control. As summarized in TABLE 6, the functional Jurkat-based titer evaluation was consistent with the transient transfection results. Transfection with clones D09, G04, and F10 resulted in significantly lower titers as compared to the other CD19-binders and the FMC63 control.TABLE 6. Jurkat-based titers for anti-CD19-CARsCD19-CAR Expression in Primary Human T Cells

[0332] The 7 CD19-CAR constructs that expressed efficiently in Expi263 and Jurkat T cells were further analyzed for expression in primary human T cells isolated from two different donors. Briefly, on Day 0, T cells were isolated from human PBMCs by selection with anti-CD3 / CD28 beads. The isolated T cells were plated at a concentration of 1E6 cells / mL in a 12-well non-tissue culture plate. At 24-hours post-isolation, cells were transfected with lentiviral vectors encoding CD19-CARs comprising one of the fully human anti-CD19 scFvs identified in Example 1 ( MOI = 5 or 10), and incubated for 48 hours. Cells were counted using a NucleoCounter® NC200® (ChemoMetec) every 2 days and expanded, as necessary. Media was supplemented with IL-2 every 2 days. At Day 9, 3E5 total cells were stained using CD19-CAR detection reagent (Miltenyi, 130-129-55; biotin-conjugated CD19 antigen) and PE streptavidin (BD Bioscience, 554061). Cells were also stained with Pacific Blue™-conjugated anti -human CD4 antibody (Biolegend, 317429) and APC / Cyanine7-conjugated anti-human CD8 antibody to assess CD4 and CD8 expression. CD19-CAR, CD4, and CD8 expression were assessed using flow cytometry, and data were analyzed using FlowJo and Quanteon. As shown in FIGURE 3, CD19-CARs comprising any of the seven fully human CD19-binders exhibited robust expression in primary human T cells obtained from both donors.Cytotoxicity ofT Cells Expressing a CD19-CAR Comprising a Fully Human CD19-binder

[0333] Primary human T cells expressing one of seven CD19-CARs comprising a fully human anti-CD19 scFv were evaluated for cytotoxicity against CD19-expressing target cells. Briefly, primary human T cells were isolated from PBMCs and transfected with lentiviral vectors encoding a CD19-CAR comprising a novel, fully human anti-CD19 scFv, as described above. Non-transfected T cells and T cells transfected with a CD19-CAR construct comprising FMC63 were used as controls. The CD19-CAR T cells were incubated with Nalm6 target cells at four different effector:target ratios (1: 1, 0.5: 1, 0.25: 1, 0.125: 1, or 0.0625: 1 or Target only), with three replicates per condition. The number of effector cells added to the culture was determined based on the percentage of CAR-expressing T cells. A culture of target cells that was not incubated with any T cells was used as a negative control.

[0334] Target-cell death was evaluated over 120 hours with an imaging -based cytotoxicity assay, using an IncuCyte S3 Live-Cell Analysis System. The Nalm6 target cells endogenously expressed CD 19, and were engineered to express GFP and clonally selected forhigh GFP expression. Target cell lysis was monitored by quantifying the number of GFP- expressing target cells. The number of GFP-positive target cells per image was quantified using the embedded IncuCyte Analysis Software, and the area under each curve (AUC) was calculated using GraphPad Prism.

[0335] As summarized in FIGURES 4A-4K, primary T cells expressing CD19-CAR constructs derived from anti-CD19 clones A06, E04, E06 and E10 exhibited more than a 50% increase in cytotoxic activity across all tested E:T ratios, as compared to the non-transduced and target-only control treatments. The cytotoxicity of these four constructs was comparable to that of a CAR construct comprising FMC63. By contrast, cells expressing CARs comprising scFvs derived from clones F03, F10 and H06 were less cytotoxic than cells expressing the analogous FMC63-CAR construct.Example 3

[0336] This example describes screening fully human CD 19 antibodies for off-target binding to human membrane proteins.

[0337] CD19-binders corresponding to clones A06, E04, E06, and E10 were fused to human Fc domains and assessed for off-target binding using a membrane proteome array (MPA), which enables comprehensive profiling of potential off-target binding specificity. The assay utilizes HEK-293T cells in conjunction with flow cytometry to facilitate the identification of potential off-target binding of purified CD 19 binders to approximately 6000 membrane proteins. Briefly, the MPA library comprises approximately 6,000 distinct human membrane protein clones, each overexpressed in live cells from expression plasmids. Each clone was individually transfected in separate wells of a 384-well plate, followed by a 24h incubation. Cells expressing each individual MPA protein clone were arrayed in duplicate in a matrix format for high-throughput screening. Before screening on the MPA, the test ligand concentration for screening was determined on cells expressing positive (membrane-tethered Protein A) and negative (mock-transfected) binding controls, followed by detection by flow cytometry using a fluorescently labeled secondary antibody. Each test ligand was added to the MPA at the predetermined concentration, and binding across the protein library was measured on an Intellicyt iQue using a fluorescently labeled secondary antibody. Each array plate contained both positive (Fc-binding) and negative (empty vector) controls to ensure plate -by-plate reproducibility. Test ligand interactions with any targets identified by MPAscreening were confirmed in a second flow cytometry experiment using serial dilutions of the test antibody, and the target identity was re-verified by sequencing.

[0338] The results of the MPA analysis are summarized in FIGURE 5. As expected, all clones exhibited specificity towards CD 19. Clone A06 also bound to FCGR1A, a membrane protein which is known to bind to the human Fc portion of recombinant proteins. Clone A06 otherwise exhibited negligible off-target binding. Clone E06 also exhibited negligible off- target binding. Clone E04 exhibited a low degree of off-target binding to ATL2. Finally, clone E10 exhibited off-target binding to LRTM2, a membrane protein which is highly expressed in plasma cells and which is implicated in heparin-binding processes.Example 4

[0339] This example describes evaluating three CARs comprising a fully human CD 19- binder for proliferation in response to stimulation with CD19-expressing target cells.

[0340] Briefly, primary human T cells were isolated from PBMCs and transfected with lentiviral vectors encoding a CD19-CAR comprising a fully human anti-CD19 scFv, as described in Example 2 above. Non-transfected T cells and T cells transfected with a CD 19- CAR construct comprising FMC63 were used as controls. The CD19-CAR T cells were incubated with Nalm6 target cells at a 1 : 1 effector: target ratio, with three replicates per condition. The numbers of total CD3+ and CAR+ T cells were evaluated over 31 days using a Cellaca MX high-throughput cell counter by counting cell numbers every 3-4 days. T cells were stained with anti-CD3 antibody and with a CD19-CAR detection reagent.

[0341] As summarized in FIGURES 6A-6B, primary T cells expressing CD19-CAR constructs derived from anti-CD19 clones A06, E04, and E06 proliferated in response to target stimulation on day 0, as compared to the non-transduced control T cells. The proliferation of these three constructs was greater and lasted longer than that of a CAR construct comprising FMC63. After 24 days, all three constructs started to decline in numbers and stopped proliferating.Example 5

[0342] This example describes evaluating CD4+ and CD8+ T cells expressing a CAR comprising a fully human CD19-binder for cytotoxicity against CD19-expressing target cells.

[0343] Primary human T cells expressing a CD19-CAR comprising a fully human antiCD 19 scFv (E04) were evaluated for cytotoxicity against CD19-expressing Nalm6 targetcells as described in Example 2. Briefly, primary human T cells were isolated from PBMCs and transfected with lentiviral vectors encoding a CD19-CAR comprising the novel, fully human anti-CD19 scFv E04, as described above. The CD19-CAR T cells were further isolated into CD4+ and CD8+ T cells, and the CD4+ CAR T cells, the CD8+ CAR T cells, and the total fraction of CD19-CAR T cells were incubated with Nalm6 target cells at five different effectortarget ratios (1: 1, 0.5: 1, 0.25: 1, 0.125: 1, or 0.0625: 1), with three replicates per condition. The number of effector cells added to the culture was determined based on the percentage of CAR-expressing T cells. Target cells incubated with non-transduced T cells (NTD) and target cells that were not incubated with any T cells (“Targets only”) were used as negative controls.

[0344] Target-cell death was evaluated over 120 hours with an imaging -based cytotoxicity assay, using an IncuCyte S3 Live-Cell Analysis System. The Nalm6 target cells endogenously expressed CD 19, and were engineered to express GFP and clonally selected for high GFP expression. Target cell lysis was monitored by quantifying the number of GFP- expressing target cells. The number of GFP-positive target cells per image was quantified using the embedded IncuCyte Analysis Software, and the area under each curve (AUC) was calculated using GraphPad Prism.

[0345] As summarized in FIGURES 7A-7E, primary CD4+ or CD8+ T cells expressing a CD19-CAR construct derived from anti-CD19 clone E04 exhibited more than a 50% increase in cytotoxic activity across all tested E:T ratios, as compared to the nontransduced and target-only control treatments. The cytotoxicity of CD4+ and CD8+ CAR T cells were comparable to each other and to total CAR T cells.Example 6

[0346] This example describes evaluating T cells expressing a CAR comprising a fully human CD19-binder for intracellular cytokine secretion after stimulation.

[0347] Primary human T cells were isolated from PBMCs and transfected with a lentiviral vector encoding a CD19-CAR comprising a novel, fully human anti-CD19 scFv (E06), as described in Example 2. The CD19-CAR T cells were sorted based on CAR expression, stimulated with PMA and ionomycin for 4.5 hours, and then stained for CD3, CD4, CD8, CAR, IFNy, and TNFa. As summarized in FIGURES 8A-8B, primary T cells expressing a CD19-CAR construct derived from the anti-CD19 clone E06 produced IFNy and TNFa when stimulated.Example 7

[0348] This example describes evaluating the in vivo efficacy of T cells expressing a CAR comprising a fully human CD19-binder.

[0349] Briefly, primary human T cells were isolated from PBMCs and transfected with lentiviral vectors encoding a CD19-CAR comprising one of two novel, fully human antiCD 19 scFvs (E04 or E06), as described above. Non-transfected T cells and T cells transfected with a CD19-CAR construct comprising FMC63 were used as controls.Immunodeficient NSG mice were injected with CD 19-expressing Nalm6 tumor cells on Day -5, followed by injection on Day 0 with a dose of IxlO6CAR-T cells / mouse (“low”), 3xl06CAR-T cells per mouse (“mid”), or IxlO7CAR-T cells per mouse (“high”). Proliferation of Nalm6 cells was measured by biolumine scent imaging (BLI) using the IVIS Spectrum, with imaging beginning on Day -7 for baseline and continuing up to 3 times per week until termination of the study on Day 28. Body weights and animal health were assessed throughout the course of the study.

[0350] As summarized in FIGURES 9A-9D, primary T cells expressing CD19-CAR constructs derived from anti-CD19 clones E04 and E06 effectively controlled Nalm6 target cell proliferation in mice at all dose levels as compared to the non-transduced control T cells. The in vivo efficacy of these two constructs was comparable to that of a CAR construct comprising FMC63 in high and mid doses.INCORPORATION BY REFERENCE

[0351] The entire disclosure of each of the patent and scientific documents referred to herein is incorporated by reference for all purposes.EQUIVALENTS

[0352] The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The foregoing embodiments are therefore to be considered in all respects illustrative rather than limiting on the invention described herein. Scope of the invention is thus indicated by the appended claims rather than by the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are intended to be embraced therein.SEQUENCE LISTINGIll

Claims

WHAT IS CLAIMED IS:

1. An antibody or antigen-binding fragment thereof that binds to CD 19 comprising three heavy chain complementarity determining regions (CDRs) (CDRHI, CDRH2, and CD RIB) and three light chain complementarity determining regions (CDRs) (CDRLI, CDRL2, and CD RIB). wherein:(i) the CDRHI, CDRH2, and CDRHS are present in a heavy chain variable domain (VH) comprising the amino acid sequence set forth in SEQ ID NO: 7, and the CDRLI, CDRL2, and CDRL3 are present in a light chain variable domain (VL) comprising the amino acid sequence set forth in SEQ ID NO: 8;(ii) the CDRHI, CDRH2, and CDRH3 are present in a heavy chain variable domain (VH) comprising the amino acid sequence set forth in SEQ ID NO: 1, and the CDRLI, CDRL2, and CDRL3 are present in a light chain variable domain (VL) comprising the amino acid sequence set forth in SEQ ID NO: 2;(iii) the CDRHI, CDRH2, and CDRH3 are present in a heavy chain variable domain (VH) comprising the amino acid sequence set forth in SEQ ID NO: 4, and the CDRLI, CDRL2, and CDRL3 are present in a light chain variable domain (VL) comprising the amino acid sequence set forth in SEQ ID NO: 5;(iv) the CDRHI, CDRH2, and CDRH3 are present in a heavy chain variable domain (VH) comprising the amino acid sequence set forth in SEQ ID NO: 10, and the CDRLI, CDRL2, and CDRL3 are present in a light chain variable domain (VL) comprising the amino acid sequence set forth in SEQ ID NO: 11;(v) the CDRHI, CDRH2, and CDRH3 are present in a heavy chain variable domain (VH) comprising the amino acid sequence set forth in SEQ ID NO: 13, and the CDRLI, CDRL2, and CDRL3 are present in a light chain variable domain (VL) comprising the amino acid sequence set forth in SEQ ID NO: 14;(vi) the CDRHI, CDRH2, and CDRH3 are present in a heavy chain variable domain (VH) comprising the amino acid sequence set forth in SEQ ID NO: 16, and the CDRLI, CDRL2, and CDRL3 are present in a light chain variable domain (VL) comprising the amino acid sequence set forth in SEQ ID NO: 17;(vii) the CDRHI, CDRH2, and CDRHS are present in a heavy chain variable domain (VH) comprising the amino acid sequence set forth in SEQ ID NO: 19, and the CDRLI, CDRL2, and CDRL3 are present in a light chain variable domain (VL) comprising the amino acid sequence set forth in SEQ ID NO: 20;(viii) the CDRHI, CDRH2, and CDRH3 are present in a heavy chain variable domain (VH) comprising the amino acid sequence set forth in SEQ ID NO: 22, and the CDRLI, CDRL2, and CDRL3 are present in a light chain variable domain (VL) comprising the amino acid sequence set forth in SEQ ID NO: 23;(ix) the CDRHI, CDRH2, and CDRH3 are present in a heavy chain variable domain (VH) comprising the amino acid sequence set forth in SEQ ID NO: 25, and the CDRLI, CDRL2, and CDRL3 are present in a light chain variable domain (VL) comprising the amino acid sequence set forth in SEQ ID NO: 26; or(x) the CDRHI, CDRH2, and CDRH3 are present in a heavy chain variable domain (VH) comprising the amino acid sequence set forth in SEQ ID NO: 28, and the CDRLI, CDRL2, and CDRL3 are present in a light chain variable domain (VL) comprising the amino acid sequence set forth in SEQ ID NO: 29.

2. The antibody or antigen-binding fragment thereof of claim 1, wherein:(a) the CDRHI, CDRH2, CDRH3, CDRLI, CDRL2, and CDRL3 are defined according to Kabat;(b) the CDRHI, CDRH2, CDRH3, CDRLI, CDRL2, and CDRL3 are defined according to Chothia;(c) the CDRHI, CDRH2, CDRH3, CDRLI, CDRL2, and CDRL3 are defined according to IMGT;(d) the CDRHI, CDRH2, CDRH3, CDRLI, CDRL2, and CDRL3 are defined according to AbM;(e) the CDRHI, CDRH2, CDRH3, CDRLI, CDRL2, and CDRL3 are defined according to Contact;(f) the CDRHI, CDRH2, CDRH3, CDRLI, CDRL2, and CDRL3 are defined according to Honneger (AHo).

3. An antibody or antigen-binding fragment thereof that binds to CD 19, comprising a heavy chain variable domain (VH) comprising complementarity determining regions CDRHI,CDRH2, and CDRH3 and a light chain variable domain (VL) comprising complementarity determining regions CDRLI, CDRL2, and CDRL3, wherein:(i) the CDRHI comprises the amino acid sequence of SEQ ID NO: 43, 86, or 108; the CDRH2 comprises the amino acid sequence of SEQ ID NO: 44, 87, or 109; the CDRm comprises the amino acid sequence of SEQ ID NO: 45 or 110; the CDRLI comprises the amino acid sequence of SEQ ID NO: 46 or 111; the CDRL2 comprises the amino acid sequence of SEQ ID NO: 47 or DAS; and the CDRL3 comprises the amino acid sequence of SEQ ID NO: 48;(ii) the CDRHI comprises the amino acid sequence of SEQ ID NO: 31, 82, or 98; the CDRH2 comprises the amino acid sequence of SEQ ID NO: 32, 83, or 99; the CDRrn comprises the amino acid sequence of SEQ ID NO: 33 or 100; the CDRLI comprises the amino acid sequence of SEQ ID NO: 34 or 101; the CDRL2 comprises the amino acid sequence of SEQ ID NO: 35 or AAS; and the CDRL3 comprises the amino acid sequence of SEQ ID NO: 36;(iii) the CDRHI comprises the amino acid sequence of SEQ ID NO: 37, 84, or 103; the CDRH2 comprises the amino acid sequence of SEQ ID NO: 38, 85, or 104; the CDRm comprises the amino acid sequence of SEQ ID NO: 39 or 105; the CDRLI comprises the amino acid sequence of SEQ ID NO: 40 or 106; the CDRL2 comprises the amino acid sequence of SEQ ID NO: 41 or DAS; and the CDRL3 comprises the amino acid sequence of SEQ ID NO: 42;(iv) the CDRHI comprises the amino acid sequence of SEQ ID NO: 31, 82, or 98; the CDRH2 comprises the amino acid sequence of SEQ ID NO: 49, 88, or 112; the CDRm comprises the amino acid sequence of SEQ ID NO: 50 or 113; the CDRLI comprises the amino acid sequence of SEQ ID NO: 51 or 114; the CDRL2 comprises the amino acid sequence of SEQ ID NO: 52 or LGS; and the CDRL3 comprises the amino acid sequence of SEQ ID NO: 53;(v) the CDRHI comprises the amino acid sequence of SEQ ID NO: 31, 82, or 98; the CDRH2 comprises the amino acid sequence of SEQ ID NO: 54, 89, or 116; the CDRm comprises the amino acid sequence of SEQ ID NO: 55 or 117; the CDRLI comprises the amino acid sequence of SEQ ID NO: 56 or 118; the CDRL2 comprises the aminoacid sequence of SEQ ID NO: 57 or GIS; and the CDRLS comprises the amino acid sequence of SEQ ID NO: 58;(vi) the CDRHI comprises the amino acid sequence of SEQ ID NO: 31, 82, or 98; the CDRH2 comprises the amino acid sequence of SEQ ID NO: 32, 90, or 99; the CDRH3 comprises the amino acid sequence of SEQ ID NO: 78 or 120; the CDRLI comprises the amino acid sequence of SEQ ID NO: 79 or 121; the CDRL2 comprises the amino acid sequence of SEQ ID NO: 80 or GAS; and the CDRLS comprises the amino acid sequence of SEQ ID NO: 81;(vii) the CDRHI comprises the amino acid sequence of SEQ ID NO: 43, 91, or 123; the CDRH2 comprises the amino acid sequence of SEQ ID NO: 59, 92, or 124; the CDRH3 comprises the amino acid sequence of SEQ ID NO: 60 or 125; the CDRLI comprises the amino acid sequence of SEQ ID NO: 61 or 126; the CDRL2 comprises the amino acid sequence of SEQ ID NO: 62 or LGS; and the CDRLS comprises the amino acid sequence of SEQ ID NO: 63;(viii) the CDRHI comprises the amino acid sequence of SEQ ID NO: 64, 93, or 127; the CDRH2 comprises the amino acid sequence of SEQ ID NO: 32, 90, or 99; the CDRH3 comprises the amino acid sequence of SEQ ID NO: 65 or 128; the CDRLI comprises the amino acid sequence of SEQ ID NO: 34 or 101; the CDRL2 comprises the amino acid sequence of SEQ ID NO: 47 or DAS; and the CDRLS comprises the amino acid sequence of SEQ ID NO: 66;(ix) the CDRHI comprises the amino acid sequence of SEQ ID NO: 67, 94, or 129; the CDRH2 comprises the amino acid sequence of SEQ ID NO: 68, 95, or 130; the CDRH3 comprises the amino acid sequence of SEQ ID NO: 69 or 131; the CDRLI comprises the amino acid sequence of SEQ ID NO: 70 or 132; the CDRL2 comprises the amino acid sequence of SEQ ID NO: 71 or DAS; and the CDRLS comprises the amino acid sequence of SEQ ID NO: 72; or(x) the CDRHI comprises the amino acid sequence of SEQ ID NO: 73, 96, or 133; the CDRH2 comprises the amino acid sequence of SEQ ID NO: 32, 97, or 134; the CDRH3 comprises the amino acid sequence of SEQ ID NO: 74 or 135; the CDRLI comprises the amino acid sequence of SEQ ID NO: 75 or 136; the CDRL2 comprises the amino acid sequence of SEQ ID NO: 76 or AAS; and the CDRLS comprises the amino acid sequence of SEQ ID NO: 77.

4. The antibody or antigen-binding fragment thereof of any one of claims 1-3, wherein:(i) the CDRHI, CDRH2, and CDRHS comprise the amino acid sequences of SEQ ID NOs: 43, 44, and 45, respectively, and the CDRLI, CDRL2, and CDRLS comprise the amino acid sequences of SEQ ID NOs: 46, 47, and 48, respectively;(ii) the CDRHI, CDRm, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 31, 32, and 33, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NOs: 34, 35, and 36, respectively;(iii) the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 37, 38, and 39, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NOs: 40, 41, and 42, respectively;(iv) the CDRHI, CDRH2, and CDRm comprise the amino acid sequences of SEQ ID NOs: 31, 49, and 50, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NOs: 51, 52, and 53, respectively;(v) the CDRHI, CDRm, and CDRm comprise the amino acid sequences of SEQ ID NOs: 31, 54, and 55, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NOs: 56, 57, and 58, respectively;(vi) the CDRHI, CDRm, and CDRm comprise the amino acid sequences of SEQ ID NOs: 31, 32, and 78, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NOs: 79, 80, and 81, respectively;(vii) the CDRHI, CDRm, and CDRm comprise the amino acid sequences of SEQ ID NOs: 43, 59 and 60, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NOs: 61, 62, and 63, respectively;(viii) the CDRHI, CDRm, and CDRm comprise the amino acid sequences of SEQ ID NOs: 64, 32, and 65, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NOs: 34, 47, and 66, respectively;(ix) the CDRHI, CDRm, and CDRm comprise the amino acid sequences of SEQ ID NOs: 67, 68, and 69, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NOs: 70, 71, and 72, respectively; or(x) the CDRHI, CDRH2, and CDRHS comprise the amino acid sequences of SEQ ID NOs: 73, 32, and 74, respectively, and the CDRLI, CDRL2, and CDRLS comprise the amino acid sequences of SEQ ID NOs: 75, 76, and 77, respectively.

5. The antibody or antigen-binding fragment thereof of any one of claims 1-3, wherein:(i) the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 86, 87, and 45, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NOs: 46, 47, and 48, respectively;(ii) the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 82, 83, and 33, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NOs: 34, 35, and 36, respectively;(iii) the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 84, 85, and 39, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NOs: 40, 41, and 42, respectively;(iv) the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 82, 88, and 50, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NOs: 51, 52, and 53, respectively;(v) the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 82, 89, and 55, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NOs: 56, 57, and 58, respectively;(vi) the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 82, 90, and 78, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NOs: 79, 80, and 81, respectively;(vii) the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 91, 92, and 60, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NOs: 61, 62, and 63, respectively;(viii) the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 93, 90, and 65, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NOs: 34, 47, and 66, respectively;(ix) the CDRHI, CDRH2, and CDRHS comprise the amino acid sequences of SEQ ID NOs: 94, 95, and 69, respectively, and the CDRLI, CDRL2, and CDRLS comprise the amino acid sequences of SEQ ID NOs: 70, 71, and 72, respectively; or(x) the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 96, 97, and 74, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NOs: 75, 76, and 77, respectively.

6. The antibody or antigen-binding fragment thereof of any one of claims 1-3, wherein:(i) the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 108, 109, and 110, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NO: 111, DAS, and SEQ ID NO: 48, respectively;(ii) the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 98, 99, and 100, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NO: 101, AAS, and SEQ ID NO: 36, respectively;(iii) the CDRHI, CDRH2, and CDRIB comprise the amino acid sequences of SEQ ID NOs: 103, 104, and 105, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NO: 106, DAS, and SEQ ID NO: 42, respectively;(iv) the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 98, 112, and 113, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NO: 114, LGS, and SEQ ID NO: 53, respectively;(v) the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 98, 116, and 117, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NO: 118, GIS, and SEQ ID NO: 58, respectively;(vi) the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 98, 99, and 120, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NO: 121, GAS, and SEQ ID NO: 81, respectively;(vii) the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 123, 124, and 125, respectively, and the CDRLI, CDRL2, and CDRL3 comprisethe amino acid sequences of SEQ ID NO: 126, LGS, and SEQ ID NO: 63, respectively;(viii) the CDRHI, CDRH2, and CDRHS comprise the amino acid sequences of SEQ ID NOs: 127, 99, and 128, respectively, and the CDRLI, CDRL2, and CDRLS comprise the amino acid sequences of SEQ ID NO: 101, DAS, and SEQ ID NO: 66, respectively;(ix) the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 129, 130, and 131, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NO: 132, DAS, and SEQ ID NO: 72, respectively; or(x) the CDRHI, CDRH2, and CDRH3 comprise the amino acid sequences of SEQ ID NOs: 133, 134, and 135, respectively, and the CDRLI, CDRL2, and CDRL3 comprise the amino acid sequences of SEQ ID NO: 136, AAS, and SEQ ID NO: 77, respectively.

7. The antibody or antigen-binding fragment thereof of any one of claims 1-6, wherein the CDRs are interposed between human or humanized immunoglobulin framework regions.

8. The antibody or antigen-binding fragment thereof of any one of claims 1-7, wherein:(i) the VH and the VL comprise amino acid sequences at least 95% identical to the amino acid sequences of SEQ ID NOs: 7 and 8, respectively;(ii) the VH and the VL comprise amino acid sequences at least 95% identical to the amino acid sequences of SEQ ID NOs: 1 and 2, respectively;(iii) the VH and the VL comprise amino acid sequences at least 95% identical to the amino acid sequences of SEQ ID NOs: 4 and 5, respectively;(iv) the VH and the VL comprise amino acid sequences at least 95% identical to the amino acid sequences of SEQ ID NOs: 10 and 11, respectively;(v) the VH and the VL comprise amino acid sequences at least 95% identical to the amino acid sequences of SEQ ID NOs: 13 and 14, respectively;(vi) the VH and the VL comprise amino acid sequences at least 95% identical to the amino acid sequences of SEQ ID NOs: 16 and 17, respectively;(vii) the VH and the VL comprise amino acid sequences at least 95% identical to the amino acid sequences of SEQ ID NOs: 19 and 20, respectively;(viii) the VH and the VL comprise amino acid sequences at least 95% identical to the amino acid sequences of SEQ ID NOs: 22 and 23, respectively;(ix) the VH and the VL comprise amino acid sequences at least 95% identical to the amino acid sequences of SEQ ID NOs: 25 and 26, respectively; or(x) the VH and the VL comprise amino acid sequences at least 95% identical to the amino acid sequences of SEQ ID NOs: 28 and 29, respectively.

9. The antibody or antigen-binding fragment thereof of any one of claims 1-8, wherein:(i) the VH and the VL comprise the amino acid sequences of SEQ ID NOs: 7 and 8, respectively;(ii) the VH and the VL comprise the amino acid sequences of SEQ ID NOs: 1 and 2, respectively;(iii) the VH and the VL comprise the amino acid sequences of SEQ ID NOs: 4 and 5, respectively;(iv) the VH and the VL comprise the amino acid sequences of SEQ ID NOs: 10 and 11, respectively;(v) the VH and the VL comprise the amino acid sequences of SEQ ID NOs: 13 and 14, respectively;(vi) the VH and the VL comprise the amino acid sequences of SEQ ID NOs: 16 and 17, respectively;(vii) the VH and the VL comprise the amino acid sequences of SEQ ID NOs: 19 and 20, respectively;(viii) the VH and the VL comprise the amino acid sequences of SEQ ID NOs: 22 and 23, respectively;(ix) the VH and the VL comprise the amino acid sequences of SEQ ID NOs: 25 and 26, respectively; or(x) the VH and the VL comprise the amino acid sequences of SEQ ID NOs: 28 and 29, respectively.

10. The antibody or antigen-binding fragment thereof of any one of claims 1-9, wherein the antibody or antigen-binding fragment thereof is humanized or fully human.

11. An antibody or antigen-binding fragment thereof that competes for binding to CD 19 with the antibody or antigen-binding fragment thereof of any one of claims 1-10.

12. An antibody or antigen-binding fragment thereof that binds to the same epitope on CD 19 as the antibody or antigen-binding fragment thereof of any one of claims 1-11.

13. The antibody or antigen-binding fragment thereof of any one of claims 1-12, wherein the CD19 is human CD19.

14. The antibody or antigen-binding fragment thereof of any one of claims 1-13, wherein the antibody or antigen-binding fragment thereof binds to human CD 19 with a KD of 200 nM or stronger, 100 nM or stronger, 75 nM or stronger, 50 nM or stronger, 25 nM or stronger, 20 nM or stronger, or 15 nM or stronger, as measured by surface plasmon resonance.

15. The antibody or antigen-binding fragment thereof of any one of claims 1-14, wherein the antibody or antigen-binding fragment thereof comprises an scFv.

16. The antibody or antigen-binding fragment thereof of claim 15, wherein the scFv comprises an amino acid sequence at least 95% identical to the amino acid sequence of any one of SEQ ID NOs: 9, 3, 6, 12, 15, 18, 21, 24, 27, or 30.

17. The antibody or antigen-binding fragment thereof of claim 15 or 16, wherein the scFv comprises the amino acid sequence of any one of SEQ ID NOs: 9, 3, 6, 12, 15, 18, 21, 24, 27, or 30.

18. A chimeric antigen receptor (CAR) comprising an extracellular binding domain comprising the antibody or antigen-binding fragment thereof of any one of claims 1-17.

19. The CAR of claim 18, wherein the CAR further comprises a transmembrane domain, a costimulatory domain, and / or an intracellular signaling domain.

20. The CAR of claim 19, wherein the transmembrane domain comprises a CD8 alpha chain transmembrane domain.

21. The CAR of claim 20, wherein the CD8 alpha chain transmembrane domain comprises the amino acid sequence of SEQ ID NO: 137.

22. The CAR of any one of claims 19-21, wherein the costimulatory domain comprises a 4-1BB intracellular domain.

23. The CAR of claim 22, wherein the 4- IBB intracellular domain comprises the amino acid sequence of SEQ ID NO: 138.

24. The CAR of any one of claims 19-23, wherein the intracellular signaling domain comprises a CD3 zeta signaling domain.

25. The CAR of claim 24, wherein the CD3 zeta signaling domain comprises the amino acid sequence of SEQ ID NO: 139.

26. The CAR of any one of claims 19-25, wherein the CAR further comprises a hinge domain or linker interposed between the extracellular binding domain and the transmembrane domain.

27. The CAR of claim 26, wherein the hinge domain is a CD8 alpha chain hinge.

28. The CAR of claim 27, wherein the CD8 alpha chain hinge comprises the amino acid sequence of SEQ ID NO: 140.

29. The CAR of any one of claims 18-28, wherein the CAR comprises the amino acid sequence of any one of SEQ ID NOs: 141-160.

30. The CAR of claim 18, wherein the CAR further comprises a killer immunoglobulin- like receptor (KIR) transmembrane domain and a KIR cytoplasmic domain.

31. A nucleic acid comprising a nucleotide sequence encoding the VH of any one of claims 1-17 and / or a nucleotide sequence encoding the VL of any one of claims 1-17.

32. A nucleic acid comprising a nucleotide sequence encoding the CAR of any one of claims 18-30.

33. A vector comprising the nucleic acid of claim 31 or 32.

34. The vector of claim 33, wherein the vector is a viral vector.

35. The vector of claim 34, wherein the viral vector is a lentiviral vector or an adeno- associated viral vector.

36. A genetically modified cell comprising the nucleic acid of claim 31 or 32 or the vector of any one of claims 33-35.

37. A genetically modified cell configured to express the CAR of any one of claims 18- 30.

38. The genetically modified cell of claim 36 or 37, wherein the cell is an immune cell.

39. The genetically modified cell of claim 38, wherein the immune cell is a T cell or a natural killer cell.

40. The genetically modified cell of claim 38 or 39, wherein the immune cell is a T cell.

41. The genetically modified cell of claim 40, wherein the T cell is selected from the group consisting of a cytotoxic T cell, a helper T cell, a memory T cell, an alpha beta T cell, and a gamma delta T cell.

42. A pharmaceutical composition comprising the nucleic acid of claim 31 or 32, the vector of any one of claims 33-35, or the genetically modified cell of any one of claims 36- 41, and a pharmaceutically acceptable carrier or excipient.

43. A method of treating a disease in a subject in need thereof, the method comprising administering to the subject the nucleic acid of claim 31 or 32, the vector of any one of claims 33-35, or the pharmaceutical composition of claim 42.

44. A method of treating a disease in a subject in need thereof, the method comprising administering the genetically modified cell of any one of claims 36-41 to the subject.

45. The method of claim 44, wherein the genetically modified cell is autologous to the subject.

46. The method of claim 44 or 45, wherein the method comprises administering the genetically modified cell to the subject at a dose from 1 x 105cells / kg to 1 x 108cells / kg.

47. The method of any one claims 43-46, wherein the disease is an autoimmune disease.

48. The method of claim 47, wherein the autoimmune disease is a B-cell-mediated autoimmune disease.

49. The method of claim 47 or 48, wherein the autoimmune disease is selected from the group consisting of systemic lupus erythematosus (SLE), pemphigus vulgaris (PV), myasthenia gravis (MG), myositis, systemic sclerosis, multiple sclerosis, membranous nephropathy, and chronic immune demyelinating polyneuropathy.

50. The method of any one of claims 47-49, wherein the autoimmune disease is selected from the group consisting of lupus nephritis, SLE with anti-dsDNA antibodies, mucosal PV, mucocutaneous PV, MuSK-associated MG, AChR MG, anti-synthetase syndrome, dermatomyositis, juvenile myositis, systemic sclerosis with skin involvement, systemic sclerosis with severe organ involvement, and immune mediated necrotizing myopathy.

51. The method of any one claims 43-46, wherein the disease is cancer.

52. The method of claim 51, wherein the cancer is selected from leukemia, acute leukemia, acute lymphoblastic leukemia (ALL), B-cell ALL, acute myeloid leukemia (AML), chronic myelocytic leukemia (CML), chronic lymphocytic leukemia (CLL), transformed CLL, diffuse large B-cell lymphomas (DLBCL), follicular lymphoma, hairy cell leukemia, a lymphoma, Hodgkin’s disease, a malignant lymphoma, non-Hodgkin’s lymphoma, Burkitt’s lymphoma, multiple myeloma, or Richter’s Syndrome (Richter’s Transformation).

53. The method of claim 51 or 52, wherein the cancer is a hematological cancer.

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