Anti-CD33 antibodies and uses thereof

Abstract

The present application relates to particular anti-CD33 antibodies, nucleic acids encoding the antibodies, vectors and host cells comprising the nucleic acids, and methods of making and using the antibodies, as well as immunoconjugates comprising the anti-CD33 antibodies.

Description

ANTLCD33 ANTIBODIES AND USES THEREOFCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of US Provisional Application No. 63 / 553,282, filed February 14, 2024, which is incorporated by reference herein in its entirety for any purpose.SEQUENCE LISTING

[0002] The application contains a Sequence Listing, which has been submitted electronically in .XML format and is hereby incorporated by reference in its entirety. Said .XML copy, created on February 11, 2025, is named “01277-0041-00PCT.xml” and is 116,874 bytes in size. The sequence listing contained in this .XML file is part of the specification and is hereby incorporated by reference herein in its entirety.FIELD

[0003] The present application relates to anti-CD33 antibodies, nucleic acids encoding the antibodies, vectors and host cells comprising the nucleic acids, and methods of making and using the antibodies.BACKGROUND

[0004] There exists a need for safe and effective agents and methods for treating, preventing and managing cancer, including for cancers that are refractory to standard treatments, while reducing or avoiding the toxicities and / or side effects associated with some existing therapies.SUMMARY

[0005] The present disclosure relates to anti-CD33 antibodies, nucleic acids encoding the antibodies, vectors and host cells comprising the nucleic acids, and methods of both making and using the antibodies. For example, embodiments of the disclosure include the following:

[0006] Embodiment 1. An isolated antibody or antigen-binding portion thereof that specifically binds to CD33, wherein the antibody or antigen-binding portion thereof comprises a heavy chain complementarity determining region 1 (HCDR1) comprising an amino acid sequence selected from SEQ ID NOs: 36-42 and 72-75; a heavy chain complementarity determining region 2 (HCDR2) comprising an amino acid sequence selected from SEQ ID NOs: 43-53 and 76-80; a heavy chain complementarity determining region 3 (HCDR3) comprising the amino acid sequence of SEQ ID NO: 54 or 55; a light chain complementarity determining region1 (LCDR1) comprising an amino acid sequence selected from SEQ ID NOs: 56-61; a light chain complementarity determining region 2 (LCDR2) comprising an amino acid sequence selected from SEQ ID NOs: 62-69; and a light chain complementarity determining region 3 (LCDR3) comprising the amino acid sequence of SEQ ID NO: 70 or 71.

[0007] Embodiment 2. The isolated antibody or antigen-binding portion thereof of embodiment 1, wherein the antibody or antigen-binding portion thereof comprises: a) HCDR1 comprising the amino acid sequence of SEQ ID NO: 37, HCDR2 comprising the amino acid sequence of SEQ ID NO: 44, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 65, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; b) HCDR1 comprising the amino acid sequence of SEQ ID NO: 38, HCDR2 comprising the amino acid sequence of SEQ ID NO: 43, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 65, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; c) HCDR1 comprising the amino acid sequence of SEQ ID NO: 36, HCDR2 comprising the amino acid sequence of SEQ ID NO: 51, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 63, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; d) HCDR1 comprising the amino acid sequence of SEQ ID NO: 38, HCDR2 comprising the amino acid sequence of SEQ ID NO: 51, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 63, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; e) HCDR1 comprising the amino acid sequence of SEQ ID NO: 40, HCDR2 comprising the amino acid sequence of SEQ ID NO: 53, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 65, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; f) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 51, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acidsequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 63, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; g) HCDR1 comprising the amino acid sequence of SEQ ID NO: 40, HCDR2 comprising the amino acid sequence of SEQ ID NO: 53, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 66, LCDR3 comprising the amino acid sequence of SEQ ID NO: 70; h) HCDR1 comprising the amino acid sequence of SEQ ID NO: 38, HCDR2 comprising the amino acid sequence of SEQ ID NO: 43, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 61, LCDR2 comprising the amino acid sequence of SEQ ID NO: 67, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; i) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 52, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 62, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; j) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 51, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 64, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; k) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 51, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 56, LCDR2 comprising the amino acid sequence of SEQ ID NO: 69, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; l) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 46, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; m) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 47, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acidsequence of SEQ ID NO: 56, LCDR2 comprising the amino acid sequence of SEQ ID NO: 63, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; n) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 51, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 57, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; o) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 45, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; p) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 49, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; q) HCDR1 comprising the amino acid sequence of SEQ ID NO: 38, HCDR2 comprising the amino acid sequence of SEQ ID NO: 43, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; r) HCDR1 comprising the amino acid sequence of SEQ ID NO: 41, HCDR2 comprising the amino acid sequence of SEQ ID NO: 43, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; s) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 45, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; t) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 47, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acidsequence of SEQ ID NO: 59, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; u) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 48, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; v) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 50, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; w) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 51, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; x) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 51, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; y) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 47, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; or z) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 46, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0008] Embodiment 3. The isolated antibody or antigen-binding portion thereof of embodiment 1, wherein the antibody or antigen-binding portion thereof comprises:a) HCDR1 comprising the amino acid sequence of SEQ ID NO: 74, HCDR2 comprising the amino acid sequence of SEQ ID NO: 78, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 65, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; b) HCDR1 comprising the amino acid sequence of SEQ ID NO: 72, HCDR2 comprising the amino acid sequence of SEQ ID NO: 76, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 65, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; c) HCDR1 comprising the amino acid sequence of SEQ ID NO: 73, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 63, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; d) HCDR1 comprising the amino acid sequence of SEQ ID NO: 74, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 63, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; e) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 80, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 65, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; f) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 63, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; g) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 80, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 66, LCDR3 comprising the amino acid sequence of SEQ ID NO: 70;h) HCDR1 comprising the amino acid sequence of SEQ ID NO: 72, HCDR2 comprising the amino acid sequence of SEQ ID NO: 76, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 61, LCDR2 comprising the amino acid sequence of SEQ ID NO: 67, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; i) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 79, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 62, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; j) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 64, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; k) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 56, LCDR2 comprising the amino acid sequence of SEQ ID NO: 69, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; l) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; m) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 56, LCDR2 comprising the amino acid sequence of SEQ ID NO: 63, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; n) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 57, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71;o) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; p) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; q) HCDR1 comprising the amino acid sequence of SEQ ID NO: 72, HCDR2 comprising the amino acid sequence of SEQ ID NO: 76, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; r) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 76, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; s) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; t) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 59, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; u) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71;v) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; w) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; x) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; y) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; or z) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0009] Embodiment 4. The isolated antibody or antigen-binding portion thereof of any one of embodiments 1-3, wherein the antibody or antigen-binding portion thereof comprises a heavy chain variable region (VH) comprising an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence selected from SEQ ID NOs: 1-20, and a light chain variable region (VL) comprising an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence selected from SEQ ID NOs: 21-35; optionally wherein the glutamic acid (E) at the N-terminus of SEQ ID NOs: 1-20 may be replaced with a pyroglutamic acid (pE).

[0010] Embodiment 5. The isolated antibody or antigen-binding portion thereof of any one of embodiments 1-3, wherein the antibody or antigen-binding portion thereof comprises a heavychain variable region (VH) comprising an amino acid sequence selected from SEQ ID NOs: 1- 20, and a light chain variable region (VL) comprising an amino acid sequence selected from SEQ ID NOs: 21-35; optionally wherein the glutamic acid (E) at the N-terminus of SEQ ID NOs: 1-20 may be replaced with a pyroglutamic acid (pE).

[0011] Embodiment 6. The isolated antibody or antigen-binding portion thereof of any one of embodiments 1-3, wherein the antibody or antigen-binding portion thereof comprises a heavy chain variable region (VH) and a light chain variable region (VL), wherein the antibody or antigen-binding portion thereof comprises: a) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 5 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 35; b) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 4 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 27; c) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 19 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 26; d) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 20 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 26; e) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 6 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 27; f) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 15 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 26; g) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 6 anda VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 28; h) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 4 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 34; i) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 17 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 30; j) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 14 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 31; k) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 14 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 24; l) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 9 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 32; m) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 10 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 23; n) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 14 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 25; o) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 1 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 32;p) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 2 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 32; q) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 3 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 32; r) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 7 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 32; s) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 8 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 21; t) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 11 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 29; u) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 12 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 32; v) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 13 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 32; w) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 14 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 22; x) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 16 anda VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 32; y) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 18 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 33; z) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 9 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 32; optionally wherein the glutamic acid (E) at the N-terminus of SEQ ID NOs: 1-20 may be replaced with a pyroglutamic acid (pE).

[0012] Embodiment 7. The isolated antibody or antigen-binding portion thereof of any one of embodiments 1-3, wherein the antibody or antigen-binding portion thereof comprises a heavy chain variable region (VH) and a light chain variable region (VL), wherein the antibody or antigen-binding portion thereof comprises: a) a VH comprising the amino acid sequence of SEQ ID NO: 5 and a VL comprising the amino acid sequence of SEQ ID NO: 35; b) a VH comprising the amino acid sequence of SEQ ID NO: 4 and a VL comprising the amino acid sequence of SEQ ID NO: 27; c) a VH comprising the amino acid sequence of SEQ ID NO: 19 and a VL comprising the amino acid sequence of SEQ ID NO: 26; d) a VH comprising the amino acid sequence of SEQ ID NO: 20 and a VL comprising the amino acid sequence of SEQ ID NO: 26; e) a VH comprising the amino acid sequence of SEQ ID NO: 6 and a VL comprising the amino acid sequence of SEQ ID NO: 27; f) a VH comprising the amino acid sequence of SEQ ID NO: 15 and a VL comprising the amino acid sequence of SEQ ID NO: 26; g) a VH comprising the amino acid sequence of SEQ ID NO: 6 and a VL comprising the amino acid sequence of SEQ ID NO: 28; h) a VH comprising the amino acid sequence of SEQ ID NO: 4 and a VL comprising the amino acid sequence of SEQ ID NO: 34; i) a VH comprising the amino acid sequence of SEQ ID NO: 17 and a VL comprising the amino acid sequence of SEQ ID NO: 30;j) a VH comprising the amino acid sequence of SEQ ID NO: 14 and a VL comprising the amino acid sequence of SEQ ID NO: 31; k) a VH comprising the amino acid sequence of SEQ ID NO: 14 and a VL comprising the amino acid sequence of SEQ ID NO: 24; l) a VH comprising the amino acid sequence of SEQ ID NO: 9 and a VL comprising the amino acid sequence of SEQ ID NO: 32; m) a VH comprising the amino acid sequence of SEQ ID NO: 10 and a VL comprising the amino acid sequence of SEQ ID NO: 23; n) a VH comprising the amino acid sequence of SEQ ID NO: 14 and a VL comprising the amino acid sequence of SEQ ID NO: 25; o) a VH comprising the amino acid sequence of SEQ ID NO: 1 and a VL comprising the amino acid sequence of SEQ ID NO: 32; p) a VH comprising the amino acid sequence of SEQ ID NO: 2 and a VL comprising the amino acid sequence of SEQ ID NO: 32; q) a VH comprising the amino acid sequence of SEQ ID NO: 3 and a VL comprising the amino acid sequence of SEQ ID NO: 32; r) a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 32; s) a VH comprising the amino acid sequence of SEQ ID NO: 8 and a VL comprising the amino acid sequence of SEQ ID NO: 21; t) a VH comprising the amino acid sequence of SEQ ID NO: 11 and a VL comprising the amino acid sequence of SEQ ID NO: 29; u) a VH comprising the amino acid sequence of SEQ ID NO: 12 and a VL comprising the amino acid sequence of SEQ ID NO: 32; v) a VH comprising the amino acid sequence of SEQ ID NO: 13 and a VL comprising the amino acid sequence of SEQ ID NO: 32; w) a VH comprising the amino acid sequence of SEQ ID NO: 14 and a VL comprising the amino acid sequence of SEQ ID NO: 22; x) a VH comprising the amino acid sequence of SEQ ID NO: 16 and a VL comprising the amino acid sequence of SEQ ID NO: 32; y) a VH comprising the amino acid sequence of SEQ ID NO: 18 and a VL comprising the amino acid sequence of SEQ ID NO: 33; or z) a VH comprising the amino acid sequence of SEQ ID NO: 9 and a VL comprising the amino acid sequence of SEQ ID NO: 32;optionally wherein the glutamic acid (E) at the N-terminus of SEQ ID NOs: 1-20 may be replaced with a pyroglutamic acid (pE).

[0013] Embodiment 8. The isolated antibody or antigen-binding portion thereof of any one of embodiments 1-7, wherein the antibody or antigen-binding portion thereof is a monoclonal antibody.

[0014] Embodiment 9. The isolated antibody or antigen-binding portion thereof of any one of embodiments 1-8, wherein the antibody or antigen-binding portion thereof is a human antibody, chimeric antibody, or a humanized antibody.

[0015] Embodiment 10. The isolated antibody or antigen-binding portion thereof of any one of embodiments 1-9, wherein the antibody or antigen-binding portion thereof is an IgG antibody.

[0016] Embodiment 11. The isolated antibody or antigen-binding portion thereof of embodiment 10, wherein the antibody is an IgG antibody lacking a C-terminal lysine in the heavy chain constant region.

[0017] Embodiment 12. The isolated antibody or antigen-binding portion thereof of embodiment 10 or embodiment 11, wherein the antibody is an IgGl antibody, an IgG2 antibody, an IgG3 antibody, or an IgG4 antibody.

[0018] Embodiment 13. The isolated antibody or antigen-binding portion thereof of any one of embodiments 1-12, wherein the antibody is a full-length antibody.

[0019] Embodiment 14. The isolated antibody or antigen-binding portion thereof of any one of embodiments 1-12, wherein the antibody or antigen-binding portion thereof is an antibody fragment selected from an Fv, single-chain Fv (scFv), Fab, Fab’, or (Fab’)2.

[0020] Embodiment 15. The isolated antibody or antigen-binding portion thereof of any one of embodiments 1-14, wherein the antibody or antigen-binding portion thereof binds human CD33.

[0021] Embodiment 16. The isolated antibody or antigen-binding portion thereof of embodiment 15, wherein human CD33 comprises the amino acid sequence of SEQ ID NO: 97 or SEQ ID NO: 99.

[0022] Embodiment 17. The isolated antibody or antigen-binding portion thereof of any one of embodiments 1-16, wherein the antibody or antigen-binding portion thereof binds the monomeric form of human CD33 and / or the dimeric form of human CD33.

[0023] Embodiment 18. The isolated antibody or antigen-binding portion thereof of any one of embodiments 1-17, wherein the antibody or antigen-binding portion thereof binds cynomolgus monkey CD33.

[0024] Embodiment 19. The antibody or antigen-binding portion thereof of embodiment 18, wherein cynomolgus monkey CD33 comprises the amino acid sequence of SEQ ID NO: 98.

[0025] Embodiment 20. The isolated antibody or antigen-binding portion thereof of embodiment 18 or embodiment 19, wherein the antibody or antigen-binding portion thereof binds the monomeric form of cynomolgus monkey CD33 and / or the dimeric form of cynomolgus monkey CD33.

[0026] Embodiment 21. The isolated antibody or antigen-binding portion thereof of any one of embodiments 1-20, wherein the antibody or antigen-binding portion thereof binds to human CD33 with an affinity (KD) of less than about 1.5 nM.

[0027] Embodiment 22. The isolated antibody or antigen-binding portion thereof of any one of embodiments 1-21, wherein the antibody or antigen-binding portion thereof binds to cynomolgus monkey CD33 with an affinity (KD) of less than about 10 nM.

[0028] Embodiment 23. The isolated antibody or antigen-binding portion thereof of embodiment 21 or embodiment 22, wherein affinity is determined using biolayer interferometry.

[0029] Embodiment 24. The isolated antibody or antigen-binding portion thereof of any one of embodiments 1-23, wherein the antibody or antigen-binding portion thereof does not bind to human Siglec 6 or human Siglec 8.

[0030] Embodiment 25. The isolated antibody or antigen-binding portion thereof of any one of embodiments 1-24, wherein the antibody or antigen-binding portion thereof internalizes after binding to CD33+ cells.

[0031] Embodiment 26. The isolated antibody or antigen-binding portion thereof of any one of embodiments 1-25, wherein the antibody or antigen-binding portion thereof is a bispecific antibody.

[0032] Embodiment 27. The isolated antibody of antigen-binding portion thereof of embodiment 26, wherein the bispecific antibody binds CD33 and a second antigen.

[0033] Embodiment 28. The isolated antibody or antigen-binding portion thereof of embodiment 27, wherein the second antigen is expressed on the surface of T cells or NK cells.

[0034] Embodiment 29. The isolated antibody or antigen-binding portion thereof of embodiment 27 or embodiment 28, wherein the second antigen is selected from CD3, CD 16, CD16A, NKG2C, and NKG2D.

[0035] Embodiment 30. An antibody-drug conjugate comprising the antibody or antigenbinding portion thereof of any one of embodiments 1-29 and a cytotoxic agent.

[0036] Embodiment 31. A pharmaceutical composition comprising the isolated antibody or antigen-binding portion thereof of any one of embodiments 1-29 or the antibody-drug conjugate of embodiment 30 and a pharmaceutically acceptable carrier.

[0037] Embodiment 32. An isolated nucleic acid encoding the antibody or antigen-binding portion thereof of any one of embodiments 1-29.

[0038] Embodiment 33. A vector comprising the nucleic acid of embodiment 32.

[0039] Embodiment 34. A host cell comprising the nucleic acid of embodiment 32 or the vector of embodiment 33.

[0040] Embodiment 35. A host cell that expresses the antibody or antigen-binding portion thereof of any one of embodiments 1-29.

[0041] Embodiment 36. A method for making an anti-CD33 antibody or antigen-binding portion thereof, comprising culturing the host cell of embodiment 34 or 35 under conditions suitable for expression of the antibody or antigen-binding portion thereof.

[0042] Embodiment 37. The method of embodiment 36, further comprising recovering the antibody or antigen-binding portion thereof produced by the host cell.

[0043] Embodiment 38. A method of treating cancer in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of the isolated antibody or antigen-binding portion thereof of any one of embodiments 1-29, the pharmaceutical composition of embodiment 31, or the antibody-drug conjugate of embodiment 30.

[0044] Embodiment 39. The method of embodiment 38, wherein the cancer is leukemia.

[0045] Embodiment 40. The method of embodiment 39, wherein the leukemia is chronic lymphocytic leukemia, chronic myelocytic leukemia, acute lymphoblastic leukemia, or acute myeloid leukemia.

[0046] Embodiment 41. The method of any one of embodiments 38-40, wherein the subject is a human.

[0047] Embodiment 42. Use of the isolated antibody or antigen-binding portion thereof of any one of embodiments 1-29, the pharmaceutical composition of embodiment 31, or the antibodydrug conjugate of embodiment 30 for the preparation of a medicament for treating cancer in a subject in need thereof.

[0048] Embodiment 43. The isolated antibody or antigen-binding portion thereof of any one of embodiments 1-29, the pharmaceutical composition of embodiment 31, or the antibody-drug conjugate of embodiment 30 for use in treating cancer in a subject in need thereof.

[0049] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the claims. All references cited herein are incorporated in their entirety by reference.BRIEF DESCRIPTION OF THE DRAWINGS

[0050] FIGs. 1A-1B show and alignment of the heavy chain variable region sequences (FIG.1A) (from top to bottom: SEQ ID NOS: 5, 7, 3, 4, 4, 6, 6, 19, 20, 2, 8, 1, 18, 11, 12, 10, 9, 9, 13,15, 16, 17, 14, 14, 14, 14, respectively) and light chain variable region sequences (FIG. IB)(from top to bottom: SEQ ID NOS: 34, 21, 25, 22, 33, 32, 32, 32, 32, 32, 32, 32, 32, 32, 29, 31, 30, 24, 28, 35, 27, 27, 26, 26, 26, 23, respectively) of certain antibodies described herein. CDR regions as defined by Kabat are underlined.

[0051] FIG. 2 shows the affinity of certain anti-CD33 antibodies described herein for HEK293 cells expressing human CD33 (first column), human CD33 lacking the V domain (second column), cynomolgus monkey CD33 (third column), or human Siglec6 (fourth column).

[0052] FIG. 3 shows the affinity of certain anti-CD33 antibodies described herein for Molml3 cells, a CD33+ AML cancer cell line (first column), MV411 cells, another CD33+ AML cancer cell line (middle column), and CD33-negative Pfeiffer cells (third column).

[0053] FIG. 4 shows internalization of certain antibodies described herein, isotype control, or vadastuximab (VADA) at various concentrations and 0, 60, and 240 minutes on MV-411 cells, a CD33+ AML cancer cell line. Top row shows a plot of internalization versus concentration at three different time point. Bottom row shows a plot of internalization versus time at three different concentrations.DETAILED DESCRIPTION OF CERTAIN EMBODIMENTSI. Definitions

[0054] Unless otherwise defined, scientific and technical terms used in connection with the present invention shall have the meanings that are commonly understood by those of ordinary skill in the art. Further, unless otherwise required by context, singular terms shall include pluralities and plural terms shall include the singular.

[0055] In this application, the use of “or” means “and / or” unless stated otherwise. In the context of a multiple dependent claim, the use of “or” refers back to more than one preceding independent or dependent claim in the alternative only. Also, terms such as “element” or “component” encompass both elements and components comprising one unit and elements and components that comprise more than one subunit unless specifically stated otherwise.

[0056] Exemplary techniques used in connection with recombinant DNA, oligonucleotide synthesis, tissue culture and transformation (e.g., electroporation, lipofection), enzymatic reactions, and purification techniques are described, e.g., in Sambrook et al. Molecular Cloning: A Laboratory Manual (2nd ed., Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y. (1989)), among other places.

[0057] As used herein, the term “about” refers to a numeric value, including, for example, whole numbers, fractions, and percentages, whether or not explicitly indicated. The term “about” generally refers to a range of numerical values (e.g., + / -5-10% of the recited range) that one of ordinary skill in the art would consider equivalent to the recited value (e.g., having thesame function or result). When terms such as “at least” and “about” precede a list of numerical values or ranges, the terms modify all of the values or ranges provided in the list. In some instances, the term about may include numerical values that are rounded to the nearest significant figure.

[0058] The term “polypeptide” refers to a polymer of amino acid residues, and is not limited to a minimum length. A “protein” may comprise one or more polypeptides. Such polymers of amino acid residues may contain natural or non-natural amino acid residues, and include, but are not limited to, peptides, oligopeptides, dimers, trimers, and multimers of amino acid residues. Both full-length proteins and fragments thereof are encompassed by the definition. The terms also include post-expression modifications of the polypeptide, for example, glycosylation, sialylation, acetylation, phosphorylation, and the like. Furthermore, for purposes of the present invention, a “polypeptide” or “protein” refers to a polypeptide or protein, respectively, which includes modifications, such as deletions, additions, and substitutions (generally conservative in nature), to the native sequence, as long as the protein maintains the desired activity. These modifications may be deliberate, as through site-directed mutagenesis, or may be accidental, such as through mutations of hosts that produce the proteins or errors due to PCR amplification. A protein may comprise two or more polypeptides.

[0059] “CD33” or “sialic acid binding immunoglobulin-like lectin 3 (Siglec-3),” or “SIGLEC- 3,” or “SIGLEC3,” as used herein, refers to human CD33 (huCD33; UniProt ID: P20138-1), unless expressly noted otherwise (i.e., murine CD33, cynomolgus CD33, or the like). Exemplary human CD33 amino acid sequences are shown in SEQ ID NO: 97 and SEQ ID NO: 99.

[0060] The term “antibody” herein refers to a molecule comprising at least complementaritydetermining region (CDR) 1, CDR2, and CDR3 of a heavy chain and at least CDR1, CDR2, and CDR3 of a light chain, wherein the molecule is capable of binding to antigen. The term is used in the broadest sense and encompasses various antibody structures, including but not limited to monoclonal antibodies, polyclonal antibodies, multispecific antibodies (e.g., bispecific antibodies, diabodies, etc.), full length antibodies, single-chain antibodies, antibody conjugates, and antibody fragments, so long as they exhibit the desired CD33-specific binding activity.

[0061] An “isolated” antibody is one that has been separated from a component of its natural environment. In some aspects, an antibody is purified to greater than 95% or 99% purity as determined by, for example, electrophoretic (e.g., SDS-PAGE, isoelectric focusing (IEF), capillary electrophoresis) or chromatographic (e.g., ion exchange or reverse phase HPLC) methods. For a review of methods for assessment of antibody purity, see, e.g., Flatman et al., J. Chromatogr. B 848:79-87 (2007).

[0062] An “antigen” refers to the target of an antibody, i.e., the molecule to which the antibody specifically binds. The term “epitope” denotes the site on an antigen, either proteinaceous or non-proteinaceous, to which an antibody binds. Epitopes on a protein can be formed both from contiguous amino acid stretches (linear epitope) or comprise non-contiguous amino acids (conformational epitope), e.g., coming in spatial proximity due to the folding of the antigen, i.e., by the tertiary folding of a proteinaceous antigen. Linear epitopes are typically still bound by an antibody after exposure of the proteinaceous antigen to denaturing agents, whereas conformational epitopes are typically destroyed upon treatment with denaturing agents.

[0063] An “anti-CD33 antibody” or a “CD33 -antibody” or an “antibody that specifically binds to CD33” or an “antibody that binds to CD33” and similar phrases refer to an antibody that specifically binds to CD33 as defined herein.

[0064] The term “heavy chain” refers to a polypeptide comprising at least a heavy chain variable region, with or without a leader sequence. In some embodiments, a heavy chain comprises at least a portion of a heavy chain constant region. The term “full-length heavy chain” refers to a polypeptide comprising a heavy chain variable region and a heavy chain constant region, with or without a leader sequence.

[0065] The term “light chain” refers to a polypeptide comprising at least a light chain variable region, with or without a leader sequence. In some embodiments, a light chain comprises at least a portion of a light chain constant region. The term “full-length light chain” refers to a polypeptide comprising a light chain variable region and a light chain constant region, with or without a leader sequence.

[0066] The term “complementarity determining regions” (“CDRs”) as used herein refers to each of the regions of an antibody variable region which are hypervariable in sequence and which determine antigen binding specificity. Generally, antibodies comprise six CDRs: three in the VH (CDR-H1 or heavy chain CDR1, CDR-H2, CDR-H3), and three in the VL (CDR-L1, CDR-L2, CDR-L3). Unless otherwise indicated, the CDRs are determined according to the sequence table herein.

[0067] “Framework” or “FR” refers to the residues of the variable region residues that are not part of the complementary determining regions (CDRs). The FR of a variable region generally consists of four FRs: FR1, FR2, FR3, and FR4. Accordingly, the CDR and FR sequences generally appear in the following sequence in VH (or VL): FR1-CDR-H1(CDR-L1)-FR2- CDR- H2(CDR-L2)-FR3- CDR-H3(CDR-L3)-FR4.

[0068] The term “variable region” or “variable domain” refers to the domain of an antibody heavy or light chain that is involved in binding the antibody to antigen. The variable domains of the heavy chain and light chain (VH and VL, respectively) of a native antibody generally havesimilar structures, with each domain comprising four conserved framework regions (FRs) and three complementary determining regions (CDRs). See, e.g., Kindt et al. Kuby Immunology, 6thed., W.H. Freeman and Co., page 91 (2007). A variable domain may comprise heavy chain (HC) CDR1-FR2-CDR2-FR3-CDR3 with or without all or a portion of FR1 and / or FR4; and light chain (LC) CDR1-FR2-CDR2-FR3-CDR3 with or without all or a portion of FR1 and / or FR4. That is, a variable domain may lack a portion of FR1 and / or FR4 so long as it retains antigenbinding activity. A single VH or VL domain may be sufficient to confer antigen-binding specificity. Furthermore, antibodies that bind a particular antigen may be isolated using a VH or VL domain from an antibody that binds the antigen to screen a library of complementary VL or VH domains, respectively. See, e.g., Portolano et al., J. Immunol. 150 :880-887 (1993) ;Clarkson et al., Nature 352 :624-628 (1991).

[0069] The light chain and heavy chain “constant regions” of an antibody refer to additional sequence portions outside of the FRs and CDRs and variable regions. Certain antibody fragments may lack all or some of the constant regions. From N- to C-terminus, each heavy chain has a variable domain (VH), also called a variable heavy domain or a heavy chain variable region, followed by three constant heavy domains (CHI, CH2, and CH3). Similarly, from N- to C-terminus, each light chain has a variable domain (VL), also called a variable light domain or a light chain variable region, followed by a constant light (CL) domain.

[0070] The term “Fc region” herein is used to define a C-terminal region of an immunoglobulin heavy chain that contains at least a portion of the constant region. The term includes native sequence Fc regions and variant Fc regions. In one aspect, a human IgG heavy chain Fc region extends from Cys226, or from Pro230, to the carboxyl-terminus of the heavy chain at Gly446 and Lys447 (EU numbering). Antibodies produced by host cells may undergo post-translational cleavage of one or more, particularly one or two, amino acids from the C-terminus of the heavy chain. Therefore, an antibody produced by a host cell by expression of a specific nucleic acid molecule encoding a full-length heavy chain may include the full-length heavy chain, or it may include a cleaved variant of the full-length heavy chain. This may be the case where the final two C-terminal amino acids of the heavy chain are glycine and lysine, respectively. Therefore, the C-terminal lysine, or the C-terminal glycine and lysine, of the Fc region may or may not be present. Thus, a “full-length heavy chain constant region” or a “full length antibody” for example, which is a human IgGl antibody, includes an IgGl with both a C-terminal glycine and lysine, without the C-terminal lysine, or without both the C-terminal glycine and lysine. Unless otherwise specified herein, numbering of amino acid residues in the Fc region or constant region is according to the EU numbering system, also called the EU index, as described in Kabat et al.,Sequences of Proteins of Immunological Interest, 5thEd. Public Health Service, National Institutes of Health, Bethesda, MD, 1991.

[0071] “Effector functions” refer to those biological activities attributable to the Fc region of an antibody, which vary with the antibody isotype. Examples of antibody effector functions include: Clq binding and complement dependent cytotoxicity (CDC); Fc receptor binding; antibody-dependent cell-mediated cytotoxicity (ADCC); phagocytosis; down regulation of cell surface receptors (e.g., B cell receptor); and B cell activation.

[0072] The “class” of an antibody refers to the type of constant domain or constant region possessed by its heavy chain. There are five major classes of antibodies: IgA, IgD, IgE, IgG, and IgM, and several of these may be further divided into subclasses (isotypes), e.g., IgGl, IgG2, IgG3, IgG4, IgAl, and IgA2. The heavy chain constant domains that correspond to the different classes of immunoglobulins are called a, 8, £, y, and [i, respectively. The light chain of an antibody may be assigned to one of two types, called kappa (K) and lambda (X), based on the amino acid sequence of its constant domain.

[0073] An “antibody fragment” or “antigen-binding fragment” or “antigen-binding portion” refers to a fragment or portion of an antibody other than an intact antibody that binds the antigen (i.e., CD33) to which the intact antibody binds. Examples of antibody fragments include but are not limited to Fv, Fab, Fab’, Fab’-SH, F(ab’)2; diabodies; linear antibodies; single-chain antibody molecules (e.g., scFv, and scFab); single domain antibodies (dAbs); and multispecific antibodies formed from antibody fragments. For a review of certain antibody fragments, see Holliger and Hudson, Nature Biotechnology 23 : 1126-1136 (2005).

[0074] The terms “full length antibody”, “intact antibody”, and “whole antibody” are used herein interchangeably to refer to an antibody having a structure substantially similar to a native antibody structure or, in the case of an IgG antibody, having heavy chains that contain an Fc region as defined herein above.

[0075] The term “chimeric” antibody refers to an antibody in which a portion of the heavy and / or light chain is derived from a particular source or species, while the remainder of the heavy and / or light chain is derived from a different source or species.

[0076] A “humanized” antibody refers to a chimeric antibody comprising amino acid residues from non-human CDRs and amino acid residues from human FRs. In certain aspects, a humanized antibody will comprise substantially all of at least one, and typically two, variable domains, in which all or substantially all of the CDRs correspond to those of a non-human antibody, and all or substantially all of the FRs correspond to those of a human antibody. A humanized antibody optionally may comprise at least a portion of an antibody constant regionderived from a human antibody. A “humanized form” of an antibody, e.g., a non-human antibody, refers to an antibody that has undergone humanization.

[0077] A “human antibody” as used herein refers to antibodies produced from human immunoglobulin sequences, such as antibodies produced in non-human animals that comprise human immunoglobulin genes (such as XenoMouse® and Veloclmmune® mice), and antibodies selected using in vitro methods, such as phage display, wherein the antibody repertoire is based on a human immunoglobulin sequences.

[0078] The term “monoclonal antibody” as used herein refers to an antibody obtained from a population of substantially homogeneous antibodies, i.e., the individual antibodies comprising the population are identical and / or bind the same epitope, except for possible variant antibodies, e.g., containing naturally occurring mutations or arising during production of a monoclonal antibody preparation, such variants generally being present in minor amounts. In contrast to polyclonal antibody preparations, which typically include different antibodies directed against different determinants (epitopes), each monoclonal antibody of a monoclonal antibody preparation is directed against a single determinant on an antigen. Thus, the modifier “monoclonal” indicates the character of the antibody as being obtained from a substantially homogeneous population of antibodies and is not to be construed as requiring production of the antibody by any particular method.

[0079] A “multispecific” antibody is one that binds specifically to more than one target antigen, while a “bispecific” antibody is one that binds specifically to two antigens. An “antibody conjugate” is an antibody conjugated to one or more heterologous molecule(s), including but not limited to a therapeutic agent or a label.

[0080] Antibodies may be modified as part of the production process in certain host cells or through metabolism in vivo. An antibody or antibody region amino acid sequence herein is intended to encompass not only the specific amino acid sequence, but also that sequence as post- translationally modified, for instance, including side chain modifications and cleavages. Such a post-translational modification can occur, for instance, as a result of production of the antibody in a host cell and / or as a result of post-translational modification in vivo in an animal (e.g., a human).

[0081] In some embodiments, an antibody disclosed herein comprises a post-translational modification (e.g., one or more post-translational modifications). Post-translational modifications can include, e.g., ubiquitination, phosphorylation, acetylation, hydroxylation, methylation, glycyosylation, AMPylation, prenylation, deamidation, elimylation, citrullination, and carbamoylation. In some embodiments, the antibody is not post-translationally modified.

[0082] As noted above, antibodies can undergo post-translational cleavage of one or more, particularly one or two, amino acids from the C-terminus of the heavy chain, often a Gly-Lys. This cleavage can occur, for instance, as a result of the process of production of the antibody in a host cell. An antibody produced by expression of a specific nucleic acid molecule encoding a full-length heavy chain can include the full-length heavy chain, or it can include a cleaved variant of the full-length heavy chain, such as a heavy chain lacking a C-terminal Lys or a C- terminal Gly-Lys.

[0083] Other types of post-translational modifications can occur during production of antibodies, or otherwise in vivo, such as the modification of an amino acid side chain. For instance, an N-terminal Glu or Gin residue on an antibody chain can be post-translationally modified to an N-terminal pyroglutamate (also known as pyrrolidine carboxylate; abbreviated pE).

[0084] “Percent (%) amino acid sequence identity” and “homology” with respect to a peptide, polypeptide or antibody sequence are defined as the percentage of amino acid residues in a candidate sequence that are identical with the amino acid residues in the specific peptide or polypeptide sequence, after aligning the sequences and introducing gaps, if necessary, to achieve the maximum percent sequence identity. Alignment for purposes of determining percent amino acid sequence identity can be achieved in various ways that are within the skill in the art, for instance, using publicly available computer software such as BLAST, BLAST-2, ALIGN or MEGALIGNTM (DNASTAR) software. Those skilled in the art can determine appropriate parameters for measuring alignment, including any algorithms needed to achieve maximal alignment over the full length of the sequences being compared.

[0085] The term “signal sequence” or “leader sequence” refers to a sequence of amino acid residues located at the N terminus of a polypeptide that facilitates secretion of a polypeptide from a mammalian cell. A leader sequence may be cleaved upon export of the polypeptide from the mammalian cell, forming a mature protein. Leader sequences may be natural or synthetic, and they may be heterologous or homologous to the protein to which they are attached. Nonlimiting exemplary leader sequences also include leader sequences from heterologous proteins. In some embodiments, an antibody lacks a leader sequence. In some embodiments, an antibody comprises at least one leader sequence, which may be selected from native antibody leader sequences and heterologous leader sequences.

[0086] The term “nucleic acid molecule” or “polynucleotide” includes any compound and / or substance that comprises a polymer of nucleotides. Each nucleotide is composed of a base, specifically a purine- or pyrimidine base (i.e. cytosine I, guanine (G), adenine (A), thymine (T) or uracil (U)), a sugar (i.e. deoxyribose or ribose), and a phosphate group. Often, the nucleicacid molecule is described by the sequence of bases, whereby said bases represent the primary structure (linear structure) of a nucleic acid molecule. The sequence of bases is typically represented from 5’ to 3’. Herein, the term nucleic acid molecule encompasses deoxyribonucleic acid (DNA) including e.g., complementary DNA (cDNA) and genomic DNA, ribonucleic acid (RNA), in particular messenger RNA (mRNA), synthetic forms of DNA or RNA, and mixed polymers comprising two or more of these molecules. The nucleic acid molecule may be linear or circular. In addition, the term nucleic acid molecule includes both sense and antisense strands, as well as single stranded and double stranded forms. Moreover, the herein described nucleic acid molecule can contain naturally occurring or non-naturally occurring nucleotides. Examples of non-naturally occurring nucleotides include modified nucleotide bases with derivatized sugars or phosphate backbone linkages or chemically modified residues. Nucleic acid molecules also encompass DNA and RNA molecules which are suitable as a vector for direct expression of an antibody of the invention in vitro and / or in vivo, e.g., in a host or patient. Such DNA (e.g., cDNA) or RNA (e.g., mRNA, circular RNA) vectors, can be unmodified or modified.

[0087] An “isolated” nucleic acid refers to a nucleic acid molecule that has been separated from a component of its natural environment. An isolated nucleic acid includes a nucleic acid molecule contained in cells that ordinarily contain the nucleic acid molecule, but the nucleic acid molecule is present extrachromosomally or at a chromosomal location that is different from its natural chromosomal location.

[0088] “Isolated nucleic acid encoding an anti-CD33 antibody” refers to one or more nucleic acid molecules encoding anti-CD33 antibody heavy and light chains (or fragments thereof), including such nucleic acid molecule(s) in a single vector or separate vectors, and such nucleic acid molecule(s) present at one or more locations in a host cell.

[0089] The term “vector”, as used herein, refers to a nucleic acid molecule capable of propagating another nucleic acid to which it is linked. The term includes the vector as a selfreplicating nucleic acid structure as well as the vector incorporated into the genome of a host cell into which it has been introduced. Certain vectors are capable of directing the expression of nucleic acids to which they are operatively linked. Such vectors are referred to herein as “expression vectors”.

[0090] The terms “host cell”, “host cell line”, and “host cell culture” are used interchangeably and refer to cells into which exogenous nucleic acid has been introduced, including the progeny of such cells.

[0091] In this disclosure, “binds” or “binding” or “specific binding” and similar terms, when referring to a protein and its ligand or an antibody and its antigen target for example, or some other binding pair, means that the binding affinity between the members of the binding pair issufficiently strong that the interaction cannot be due to random molecular associations (i.e. “nonspecific binding”). Such binding typically requires a dissociation constant (KD) of IpM or less, and may often involve a KD of 100 nM or less.

[0092] “Affinity” refers to the strength of the sum total of noncovalent interactions between a single binding site of a molecule (e.g., an antibody) and its binding partner (e.g., an antigen). Unless indicated otherwise, as used herein, “binding affinity” refers to intrinsic binding affinity which reflects a 1 : 1 interaction between members of a binding pair (e.g., antibody and antigen). Affinity can generally be represented by the dissociation constant (KD). Affinity of an antibody for an antigen can be measured by common methods known in the art, such as biolayer interferometry or surface plasmon resonance (SPR), for instance. Unless otherwise indicated, KD values provided herein were determined using biolayer interferometry.

[0093] The terms “reduce” or “inhibit” more generally refer to a decrease or cessation of any event (such as protein ligand binding) or to a decrease or cessation of any phenotypic characteristic or to the decrease or cessation in the incidence, degree, or likelihood of that characteristic. To “reduce” or “inhibit” is to decrease, reduce or arrest an activity, function, and / or amount as compared to a reference. It is not necessary that the inhibition or reduction be complete. For example, in certain embodiments, by “reduce” or “inhibit” is meant the ability to cause an overall decrease of 20% or greater. In another embodiment, by “reduce” or “inhibit” is meant the ability to cause an overall decrease of 50% or greater. In yet another embodiment, by “reduce” or “inhibit” is meant the ability to cause an overall decrease of 75%, 85%, 90%, 95%, or greater.

[0094] “ Treatment” or “treating” as used herein, covers any administration or application of a therapeutic for disease in a human, and includes inhibiting the disease or progression of the disease or one or more disease symptoms, inhibiting or slowing the disease or its progression or one or more of its symptoms, arresting its development, partially or fully relieving the disease or one or more of its symptoms, or preventing a recurrence of one or more symptoms of the disease.

[0095] The terms “subject” and “patient” are used interchangeably herein to refer to a human unless expressly indicated otherwise (i.e., a murine subject or the like).

[0096] The term “cancer” is used herein to refer to a group of cells that exhibit abnormally high levels of proliferation and growth. A cancer may be benign (also referred to as a benign tumor), pre-malignant, or malignant. Cancer cells may be solid cancer cells or leukemic cancer cells.

[0097] Examples of cancers applicable to methods of treatment herein include but are not limited to, carcinoma, lymphoma, blastoma, sarcoma, and leukemia. More particular nonlimiting examples of such cancers include squamous cell cancer, small-cell lung cancer,pituitary cancer, esophageal cancer, astrocytoma, soft tissue sarcoma, non-small cell lung cancer (including squamous cell non-small cell lung cancer), adenocarcinoma of the lung, squamous carcinoma of the lung, cancer of the peritoneum, hepatocellular cancer, gastrointestinal cancer, pancreatic cancer, glioblastoma, cervical cancer, ovarian cancer, liver cancer, bladder cancer, hepatoma, breast cancer, colon cancer, colorectal cancer, endometrial or uterine carcinoma, salivary gland carcinoma, kidney cancer, renal cell carcinoma, liver cancer, prostate cancer, vulval cancer, thyroid cancer, hepatic carcinoma, brain cancer, endometrial cancer, testis cancer, cholangiocarcinoma, gallbladder carcinoma, gastric cancer, melanoma, and various types of head and neck cancer (including squamous cell carcinoma of the head and neck).

[0098] As used herein, the term “tumor,” refers to all neoplastic cell growth and proliferation, whether malignant or benign, and all pre-cancerous and cancerous cells and tissues.“Neoplastic,” as used herein, refers to any form of dysregulated or unregulated cell growth, whether malignant or benign, resulting in abnormal tissue growth. Thus, “neoplastic cells” include malignant and benign cells having dysregulated or unregulated cell growth.

[0099] As used herein, “hematologic malignancy” refers to cancer of the body's blood-forming and immune system — the bone marrow and lymphatic tissue. Such cancers include leukemias, lymphomas (Non-Hodgkin's Lymphoma), Hodgkin's disease (also called Hodgkin's Lymphoma) and myeloma.

[0100] The term “leukemia” refers to malignant neoplasms of the blood-forming tissues. The leukemia includes, but is not limited to, chronic lymphocytic leukemia, chronic myelocytic leukemia, acute lymphoblastic leukemia, acute myeloid leukemia, and acute myeloblastic leukemia. The leukemia can be relapsed, refractory or resistant to conventional therapy.

[0101] As used herein, “promyelocytic leukemia” or “acute promyelocytic leukemia” refers to a malignancy of the bone marrow in which there is a deficiency of mature blood cells in the myeloid line of cells and an excess of immature cells called promyelocytes. It is usually marked by an exchange of regions of chromosomes 15 and 17.

[0102] As used herein, “acute lymphocytic leukemia (ALL)”, also known as “acute lymphoblastic leukemia” refers to a malignant disease caused by the abnormal growth and development of early nongranular white blood cells, or lymphocytes.

[0103] As used herein, “T-cell leukemia” refers to a disease in which certain cells of the lymphoid system called T lymphocytes or T cells are malignant. T cells are white blood cells that normally can attack virus-infected cells, foreign cells, and cancer cells and produce substances that regulate the immune response.

[0104] The term “relapsed” refers to a situation where patients who have had a remission of leukemia after therapy have a return of leukemia cells in the marrow and a decrease in normal blood cells.

[0105] The term “refractory or resistant” refers to a circumstance where patients, even after intensive treatment, have residual leukemia cells in their marrow.

[0106] “Anti-cancer agents” refers to anti-metabolites (e.g., 5-fluoro-uracil, methotrexate, fludarabine), antimicrotubule agents (e.g., vinca alkaloids such as vincristine, vinblastine; taxanes such as paclitaxel, docetaxel), alkylating agents (e.g., cyclophosphamide, melphalan, carmustine, nitrosoureas such as bischloroethylnitrosurea and hydroxyurea), platinum agents (e.g. cisplatin, carboplatin, oxaliplatin, JM-216 or satraplatin, CI-973), anthracy clines (e.g., doxorubicin, daunorubicin), antitumor antibiotics (e.g., mitomycin, idarubicin, adriamycin, daunomycin), topoisomerase inhibitors (e.g., etoposide, camptothecins), anti-angiogenesis agents (e.g. Sutent® and Bevacizumab) or any other cytotoxic agents, (estramustine phosphate, prednimustine), hormones or hormone agonists, antagonists, partial agonists or partial antagonists, kinase inhibitors, and radiation treatment.

[0107] The term “effective amount” or “therapeutically effective amount” refers to an amount of a drug effective for treatment of a disease or disorder in a subject, such as to partially or fully relieve one or more symptoms. In some embodiments, an effective amount refers to an amount effective, at dosages and for periods of time necessary, to achieve the desired therapeutic or prophylactic result.

[0108] A “biological sample” as used herein refers to a sample taken from a subject or from an animal. Examples of biological samples include tissue samples and liquid biological samples, such as whole blood, serum, plasma, blood supernatant, or synovial fluid. A biological sample may be taken directly from a subject or may be first chemically or physically modified in some fashion prior to use, for example, in order to assist in analysis of the sample.

[0109] A “pharmaceutically acceptable carrier” refers to a non-toxic solid, semisolid, or liquid filler, diluent, encapsulating material, formulation auxiliary, or carrier conventional in the art for use with a therapeutic agent that together comprise a “pharmaceutical composition” for administration to a subject. A pharmaceutically acceptable carrier is non-toxic to recipients at the dosages and concentrations employed and is compatible with other ingredients of the formulation. The pharmaceutically acceptable carrier is appropriate for the formulation employed. For example, if the therapeutic agent is to be administered orally, the carrier may be a gel capsule. If the therapeutic agent is to be administered subcutaneously, the carrier ideally is not irritable to the skin and does not cause injection site reaction.II. Exemplary Anti-CD33 Antibodies

[0110] Novel antibodies directed against CD33, such as human CD33, are provided. Anti-CD33 antibodies include, but are not limited to, humanized antibodies, chimeric antibodies, mouse antibodies, human antibodies, and antibodies comprising the heavy chain and / or light chain CDRs discussed herein. In some embodiments, an isolated antibody that binds to CD33 is provided. In some embodiments, a monoclonal antibody that binds to CD33 is provided. In some embodiments, the antibody binds to human CD33. In some embodiments, the antibody binds to human CD33 comprising the amino acid sequence of SEQ ID NO: 97, and / or binds to human CD33 comprising the amino acid sequence of SEQ ID NO: 99.[OHl] In some embodiments, an anti-CD33 antibody comprises a heavy chain variable region and a light chain variable region. In some embodiments, an anti-CD33 antibody comprises at least one heavy chain comprising a heavy chain variable region and at least a portion of a heavy chain constant region, and at least one light chain comprising a light chain variable region and at least a portion of a light chain constant region. In some embodiments, an anti-CD33 antibody comprises two heavy chains, wherein each heavy chain comprises a heavy chain variable region and at least a portion of a heavy chain constant region, and two light chains, wherein each light chain comprises a light chain variable region and at least a portion of a light chain constant region. As used herein, a single-chain Fv (scFv), or any other antibody that comprises, for example, a single polypeptide chain comprising all six CDRs (three heavy chain CDRs and three light chain CDRs) is considered to have a heavy chain and a light chain. In some embodiments, the heavy chain is the region of the anti-CD33 antibody that comprises the three heavy chain CDRs. In some embodiments, the light chain is the region of the anti-CD33 antibody that comprises the three light chain CDRs.

[0112] In some embodiments, an anti-CD33 antibody comprises at least one, two, three, four, five, or six CDRs selected from a heavy chain complementarity determining region 1 (HCDR1) comprising an amino acid sequence selected from SEQ ID NOs: 36-42 and 72-75; a heavy chain complementarity determining region 2 (HCDR2) comprising an amino acid sequence selected from SEQ ID NOs: 43-53 and 76-80; a heavy chain complementarity determining region 3 (HCDR3) comprising the amino acid sequence of SEQ ID NO: 54 or 55; a light chain complementarity determining region 1 (LCDR1) comprising an amino acid sequence selected from SEQ ID NOs: 56-61; a light chain complementarity determining region 2 (LCDR2) comprising an amino acid sequence selected from SEQ ID NOs: 62-69; and a light chain complementarity determining region 3 (LCDR3) comprising the amino acid sequence of SEQ ID NO: 70 or 71.

[0113] In some embodiments, the anti-CD33 antibody comprises six CDRs including a heavy chain complementarity determining region 1 (HCDR1) comprising an amino acid sequence selected from SEQ ID NOs: 36-42 and 72-75; a heavy chain complementarity determining region 2 (HCDR2) comprising an amino acid sequence selected from SEQ ID NOs: 43-53 and 76-80; a heavy chain complementarity determining region 3 (HCDR3) comprising the amino acid sequence of SEQ ID NO: 54 or 55; a light chain complementarity determining region 1 (LCDR1) comprising an amino acid sequence selected from SEQ ID NOs: 56-61; a light chain complementarity determining region 2 (LCDR2) comprising an amino acid sequence selected from SEQ ID NOs: 62-69; and a light chain complementarity determining region 3 (LCDR3) comprising the amino acid sequence of SEQ ID NO: 70 or 71.

[0114] In some embodiments, an anti-CD33 antibody comprises at least one, two, three, four, five, or six CDRs selected from HCDR1 comprising the amino acid sequence of SEQ ID NO: 37 or 74, HCDR2 comprising the amino acid sequence of SEQ ID NO: 44 or 78, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 65, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0115] In some embodiments, the anti-CD33 antibody comprises six CDRs including HCDR1 comprising the amino acid sequence of SEQ ID NO: 37 or 74, HCDR2 comprising the amino acid sequence of SEQ ID NO: 44 or 78, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 65, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0116] In some embodiments, an anti-CD33 antibody comprises at least one, two, three, four, five, or six CDRs selected from HCDR1 comprising the amino acid sequence of SEQ ID NO: 38 or 72, HCDR2 comprising the amino acid sequence of SEQ ID NO: 43 or 76, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 65, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0117] In some embodiments, the anti-CD33 antibody comprises six CDRs including HCDR1 comprising the amino acid sequence of SEQ ID NO: 38 or 72, HCDR2 comprising the amino acid sequence of SEQ ID NO: 43 or 76, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 65, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0118] In some embodiments, an anti-CD33 antibody comprises at least one, two, three, four, five, or six CDRs selected from HCDR1 comprising the amino acid sequence of SEQ ID NO: 36 or 73, HCDR2 comprising the amino acid sequence of SEQ ID NO: 51 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 63, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0119] In some embodiments, the anti-CD33 antibody comprises six CDRs including HCDR1 comprising the amino acid sequence of SEQ ID NO: 36 or 73, HCDR2 comprising the amino acid sequence of SEQ ID NO: 51 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 63, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0120] In some embodiments, an anti-CD33 antibody comprises at least one, two, three, four, five, or six CDRs selected from HCDR1 comprising the amino acid sequence of SEQ ID NO: 38 or 74, HCDR2 comprising the amino acid sequence of SEQ ID NO: 51 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 63, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0121] In some embodiments, the anti-CD33 antibody comprises six CDRs including HCDR1 comprising the amino acid sequence of SEQ ID NO: 38 or 74, HCDR2 comprising the amino acid sequence of SEQ ID NO: 51 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 63, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0122] In some embodiments, an anti-CD33 antibody comprises at least one, two, three, four, five, or six CDRs selected from HCDR1 comprising the amino acid sequence of SEQ ID NO: 40 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 53 or 80, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 65, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0123] In some embodiments, the anti-CD33 antibody comprises six CDRs including HCDR1 comprising the amino acid sequence of SEQ ID NO: 40 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 53 or 80, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprisingthe amino acid sequence of SEQ ID NO: 65, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0124] In some embodiments, an anti-CD33 antibody comprises at least one, two, three, four, five, or six CDRs selected from HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 51 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 63, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0125] In some embodiments, the anti-CD33 antibody comprises six CDRs including HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 51 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 63, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0126] In some embodiments, an anti-CD33 antibody comprises at least one, two, three, four, five, or six CDRs selected from HCDR1 comprising the amino acid sequence of SEQ ID NO: 40 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 53 or 80, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 66, LCDR3 comprising the amino acid sequence of SEQ ID NO: 70.

[0127] In some embodiments, the anti-CD33 antibody comprises six CDRs including HCDR1 comprising the amino acid sequence of SEQ ID NO: 40 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 53 or 80, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 66, LCDR3 comprising the amino acid sequence of SEQ ID NO: 70.

[0128] In some embodiments, an anti-CD33 antibody comprises at least one, two, three, four, five, or six CDRs selected from HCDR1 comprising the amino acid sequence of SEQ ID NO: 38 or 72, HCDR2 comprising the amino acid sequence of SEQ ID NO: 43 or 76, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 61, LCDR2 comprising the amino acid sequence of SEQ ID NO: 67, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0129] In some embodiments, the anti-CD33 antibody comprises six CDRs including HCDR1 comprising the amino acid sequence of SEQ ID NO: 38 or 72, HCDR2 comprising the amino acid sequence of SEQ ID NO: 43 or 76, HCDR3 comprising the amino acid sequence of SEQ IDNO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 61, LCDR2 comprising the amino acid sequence of SEQ ID NO: 67, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0130] In some embodiments, an anti-CD33 antibody comprises at least one, two, three, four, five, or six CDRs selected from HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 52 or 79, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 62, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0131] In some embodiments, the anti-CD33 antibody comprises six CDRs including HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 52 or 79, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 62, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0132] In some embodiments, an anti-CD33 antibody comprises at least one, two, three, four, five, or six CDRs selected from HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 51 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 64, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0133] In some embodiments, the anti-CD33 antibody comprises six CDRs including HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 51 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 64, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0134] In some embodiments, an anti-CD33 antibody comprises at least one, two, three, four, five, or six CDRs selected from HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 51 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 56, LCDR2 comprising the amino acid sequence of SEQ ID NO: 69, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0135] In some embodiments, the anti-CD33 antibody comprises six CDRs including HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the aminoacid sequence of SEQ ID NO: 51 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 56, LCDR2 comprising the amino acid sequence of SEQ ID NO: 69, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0136] In some embodiments, an anti-CD33 antibody comprises at least one, two, three, four, five, or six CDRs selected from HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 46 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0137] In some embodiments, the anti-CD33 antibody comprises six CDRs including HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 46 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0138] In some embodiments, an anti-CD33 antibody comprises at least one, two, three, four, five, or six CDRs selected from HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 47 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 56, LCDR2 comprising the amino acid sequence of SEQ ID NO: 63, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0139] In some embodiments, the anti-CD33 antibody comprises six CDRs including HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 47 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 56, LCDR2 comprising the amino acid sequence of SEQ ID NO: 63, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0140] In some embodiments, an anti-CD33 antibody comprises at least one, two, three, four, five, or six CDRs selected from HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 51 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 57, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0141] In some embodiments, the anti-CD33 antibody comprises six CDRs including HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 51 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 57, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0142] In some embodiments, an anti-CD33 antibody comprises at least one, two, three, four, five, or six CDRs selected from HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 45 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0143] In some embodiments, the anti-CD33 antibody comprises six CDRs including HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 45 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0144] In some embodiments, an anti-CD33 antibody comprises at least one, two, three, four, five, or six CDRs selected from HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 49 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0145] In some embodiments, the anti-CD33 antibody comprises six CDRs including HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 49 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0146] In some embodiments, an anti-CD33 antibody comprises at least one, two, three, four, five, or six CDRs selected from HCDR1 comprising the amino acid sequence of SEQ ID NO: 38 or 72, HCDR2 comprising the amino acid sequence of SEQ ID NO: 43 or 76, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acidsequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0147] In some embodiments, the anti-CD33 antibody comprises six CDRs including HCDR1 comprising the amino acid sequence of SEQ ID NO: 38 or 72, HCDR2 comprising the amino acid sequence of SEQ ID NO: 43 or 76, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0148] In some embodiments, an anti-CD33 antibody comprises at least one, two, three, four, five, or six CDRs selected from HCDR1 comprising the amino acid sequence of SEQ ID NO: 41 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 43 or 76, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0149] In some embodiments, the anti-CD33 antibody comprises six CDRs including HCDR1 comprising the amino acid sequence of SEQ ID NO: 41 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 43 or 76, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0150] In some embodiments, an anti-CD33 antibody comprises at least one, two, three, four, five, or six CDRs selected from HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 45 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0151] In some embodiments, the anti-CD33 antibody comprises six CDRs including HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 45 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0152] In some embodiments, an anti-CD33 antibody comprises at least one, two, three, four, five, or six CDRs selected from HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 47 or 77, HCDR3comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 59, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0153] In some embodiments, the anti-CD33 antibody comprises six CDRs including HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 47 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 59, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0154] In some embodiments, an anti-CD33 antibody comprises at least one, two, three, four, five, or six CDRs selected from HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 48 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0155] In some embodiments, the anti-CD33 antibody comprises six CDRs including HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 48 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0156] In some embodiments, an anti-CD33 antibody comprises at least one, two, three, four, five, or six CDRs selected from HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 50 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0157] In some embodiments, the anti-CD33 antibody comprises six CDRs including HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 50 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0158] In some embodiments, an anti-CD33 antibody comprises at least one, two, three, four, five, or six CDRs selected from HCDR1 comprising the amino acid sequence of SEQ ID NO: 42or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 51 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0159] In some embodiments, the anti-CD33 antibody comprises six CDRs including HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 51 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0160] In some embodiments, an anti-CD33 antibody comprises at least one, two, three, four, five, or six CDRs selected from HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 51 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0161] In some embodiments, the anti-CD33 antibody comprises six CDRs including HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 51 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0162] In some embodiments, an anti-CD33 antibody comprises at least one, two, three, four, five, or six CDRs selected from HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 47 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0163] In some embodiments, the anti-CD33 antibody comprises six CDRs including HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 47 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0164] In some embodiments, an anti-CD33 antibody comprises at least one, two, three, four, five, or six CDRs selected from HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 46 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

[0165] In some embodiments, the anti-CD33 antibody comprises six CDRs including HCDR1 comprising the amino acid sequence of SEQ ID NO: 42 or 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 46 or 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71

[0166] In some embodiments, any of the six CDRs provided herein can be combined as subparts with any of the other CDRs provided herein, for a total of six CDRs in a construct. Thus, in some embodiments, two CDRs from a first antibody (for example, HCDR1 and HCDR2) can be combined with four CDRs from a second antibody (HCDR3, LCDR1, LCDR2, and LCDR3). In some embodiments, two or fewer residues in one or more of the CDRs can be replaced to obtain a variant thereof. In some embodiments, two or fewer residues can be replaced in 1, 2, 3, 4, 5, or 6 of the CDRs.

[0167] In some embodiments, the anti-CD33 antibody comprises (I) a VH domain comprising at least one, at least two, or all three VH CDR sequences selected from (i) an HCDR1 comprising an amino acid sequence selected from SEQ ID NOs: 36-42 and 72-75; (ii) an HCDR2 comprising an amino acid sequence selected from SEQ ID NOs: 43-53 and 76-80; (iii) an HCDR3 comprising the amino acid sequence of SEQ ID NO: 54 or 55; and (II) a VL domain comprising at least one, at least two, or all three VL CDR sequences selected from (iv) an LCDR1 comprising an amino acid sequence selected from SEQ ID NOs: 56-61; (v) an LCDR2 comprising an amino acid sequence selected from SEQ ID NOs: 62-69; and (vi) an LCDR3 comprising the amino acid sequence of SEQ ID NO: 70 or 71; wherein the VH domain comprises a sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of any one of SEQ ID NOs: 1-20, and the VL domain comprises a sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of any one of SEQ ID NOs: 21-35.

[0168] In some embodiments, an anti-CD33 antibody comprises a heavy chain variable domain (VH) sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or100% sequence identity to the amino acid sequence of any one of SEQ ID NOs: 1-20. In some embodiments, a VH sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity contains substitutions (for example, conservative substitutions), insertions, or deletions relative to the reference sequence, but an anti-CD33 antibody comprising that sequence retains the ability to bind CD33. In some embodiments, a total of 1 to 10 amino acids have been substituted, inserted and / or deleted in any one of SEQ ID NOs: 1-20. In some embodiments, substitutions, insertions, or deletions occur in regions outside the CDRs (that is, in the FRs). Optionally, the anti-CD33 antibody comprises the VH sequence of any one of SEQ ID NOs: 1-20, including post-translational modifications of that sequence.

[0169] In some embodiments, an anti-CD33 antibody is provided, wherein the antibody comprises a light chain variable domain (VL) having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of any one of SEQ ID NOs: 21-35. In some embodiments, a VL sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity contains substitutions (for example, conservative substitutions), insertions, or deletions relative to the reference sequence, but an anti-CD33 antibody comprising that sequence retains the ability to bind to CD33. In some embodiments, a total of 1 to 10 amino acids have been substituted, inserted and / or deleted in any one of SEQ ID NOs: 21-35. In some embodiments, the substitutions, insertions, or deletions occur in regions outside the CDRs (that is, in the FRs). Optionally, the anti-CD33 antibody comprises the VL sequence of any one of SEQ ID NOs: 21-35, including post-translational modifications of that sequence.

[0170] In some embodiments, an anti-CD33 antibody comprises a heavy chain variable domain (VH) sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of any one of SEQ ID NOs: 1-20 and a light chain variable domain (VL) having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of any one of SEQ ID NOs: 21-35. In some embodiments, a VH sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity contains substitutions (for example, conservative substitutions), insertions, or deletions relative to the reference sequence, and a VL sequence having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity contains substitutions (for example, conservative substitutions), insertions, or deletions relative to the reference sequence, but an anti-CD33 antibody comprising that sequence retains the ability to bind to CD33. In some embodiments, a total of 1 to 10 amino acids have been substituted, inserted and / or deleted in any one of SEQ ID NOs: 1-20. In some embodiments, a total of 1 to 10 amino acids have been substituted, inserted and / or deleted in any one of SEQ ID NOs: 21-35. In someembodiments, substitutions, insertions, or deletions occur in regions outside the CDRs (that is, in the FRs). Optionally, the anti-CD33 antibody comprises the VH sequence of any one of SEQ ID NOs: 1-20 and the VL sequence of any one of SEQ ID NOs: 21-35, including post-translational modifications of one or both sequences.

[0171] In some embodiments, an anti-CD33 antibody comprises a VH as in any of the embodiments provided herein, and a VL as in any of the embodiments provided herein. In some embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 5 and a VL comprising the amino acid sequence of SEQ ID NO: 35, including post- translational modifications of those sequences. In some embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 4 and a VL comprising the amino acid sequence of SEQ ID NO: 27, including post-translational modifications of those sequences. In some embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 19 and a VL comprising the amino acid sequence of SEQ ID NO: 26, including post- translational modifications of those sequences. In some embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 20 and a VL comprising the amino acid sequence of SEQ ID NO: 26, including post-translational modifications of those sequences. In some embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 6 and a VL comprising the amino acid sequence of SEQ ID NO: 27, including post-translational modifications of those sequences. In some embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 15 and a VL comprising the amino acid sequence of SEQ ID NO: 26, including post-translational modifications of those sequences. In some embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 6 and a VL comprising the amino acid sequence of SEQ ID NO: 28, including post-translational modifications of those sequences. In some embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 4 and a VL comprising the amino acid sequence of SEQ ID NO: 34, including post-translational modifications of those sequences. In some embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 17 and a VL comprising the amino acid sequence of SEQ ID NO: 30, including post-translational modifications of those sequences. In some embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 14 and a VL comprising the amino acid sequence of SEQ ID NO: 31, including post- translational modifications of those sequences. In some embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 14 and a VL comprising the amino acid sequence of SEQ ID NO: 24, including post-translational modifications of those sequences. In some embodiments, the antibody comprises a VH comprising the amino acid sequence ofSEQ ID NO: 9 and a VL comprising the amino acid sequence of SEQ ID NO: 32, including post-translational modifications of those sequences. In some embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 10 and a VL comprising the amino acid sequence of SEQ ID NO: 23, including post-translational modifications of those sequences. In some embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 14 and a VL comprising the amino acid sequence of SEQ ID NO: 25, including post-translational modifications of those sequences. In some embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 1 and a VL comprising the amino acid sequence of SEQ ID NO: 32, including post-translational modifications of those sequences. In some embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 2 and a VL comprising the amino acid sequence of SEQ ID NO: 32, including post-translational modifications of those sequences. In some embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 3 and a VL comprising the amino acid sequence of SEQ ID NO: 32, including post- translational modifications of those sequences. In some embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 32, including post-translational modifications of those sequences. In some embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 8 and a VL comprising the amino acid sequence of SEQ ID NO: 21, including post- translational modifications of those sequences. In some embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 11 and a VL comprising the amino acid sequence of SEQ ID NO: 29, including post-translational modifications of those sequences. In some embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 12 and a VL comprising the amino acid sequence of SEQ ID NO: 32, including post-translational modifications of those sequences. In some embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 13 and a VL comprising the amino acid sequence of SEQ ID NO: 32, including post-translational modifications of those sequences. In some embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 14 and a VL comprising the amino acid sequence of SEQ ID NO: 22, including post-translational modifications of those sequences. In some embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 16 and a VL comprising the amino acid sequence of SEQ ID NO: 32, including post-translational modifications of those sequences. In some embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 18 and a VL comprising the amino acid sequence of SEQ ID NO: 33, including post-translational modifications of those sequences. Insome embodiments, the antibody comprises a VH comprising the amino acid sequence of SEQ ID NO: 9 and a VL comprising the amino acid sequence of SEQ ID NO: 32, including post- translational modifications of those sequences.

[0172] In various embodiments, an anti-CD33 antibody provided herein may comprise pyroglutamic acid (pyroGlu or pE) in place of glutamic acid (Glu or E) at the N-terminus. In some embodiments, pyroGlu is formed by cyclization of an N-terminal Glu during expression and / or purification of the antibody. Thus, a Glu (E) at the N-terminus of an antibody chain sequence provided herein may be replaced with a pyroGlu, and antibodies comprising pyroGlu in place of Glu at the N-terminus the sequences provided herein are contemplated. Thus, in some embodiments, an anti-CD33 antibody is provided, wherein the antibody comprises a heavy chain variable domain comprising the sequence of any one of SEQ ID NO: 69, 70, 71, 72, or 73, wherein the N-terminal Glu (E) is replaced with a pyroGlu (pE). Similarly, an anti-CD33 antibody is provided, wherein the antibody comprises a heavy chain comprising the sequence of any one of SEQ ID NO: 83, 84, 85, 86, or 87, wherein the N-terminal Glu (E) is replaced with a pyroGlu (pE).

[0173] In various embodiments, the antibody is a monoclonal antibody.

[0174] In various embodiments, an anti-CD33 antibody specifically may comprise any of the following properties, singly or in combination. In some embodiments, the antibody binds to human CD33 with an affinity (KD) of less than about 5 nM, less than about 1 nM, less than about 0.5 nM, less than about 0.1 nM, from about 0.01 nM to about 5 nM, from about 0.01 nM to about 1 nM, from about 0.05 nM to about 1 nM, from about 0.1 nM to about 1 nM, from about 0.1 nM to about 0.5 nM, from about 0.05 nM to about 0.5 nM, from about 0.05 nM to about 0.1 nM, or from about 0.5 nM to about 1 nM. In some embodiments, the antibody binds to cynomolgus monkey CD33 with a KD less than about 5 nM, less than about 1 nM, less than about 0.5 nM, less than about 0.1 nM, from about 0.01 nM to about 5 nM, from about 0.01 nM to about 1 nM, from about 0.05 nM to about 1 nM, from about 0.1 nM to about 1 nM, from about 0.1 nM to about 0.5 nM, from about 0.05 nM to about 0.5 nM, from about 0.05 nM to about 0.1 nM, or from about 0.5 nM to about 1 nM. In some embodiments, the antibody binds to human CD33 with a KD of less than about 1.5 nM. In some embodiments, the antibody binds to cynomolgus monkey CD33 with an affinity (KD) of less than about 10 nM. In some embodiments, affinity is determined using biolayer interferometry.

[0175] In some embodiments, the antibody binds human CD33. In some embodiments, the human CD33 comprises the amino acid sequence of SEQ ID NO: 97. In some embodiments, the human CD33 comprises the amino acid sequence of SEQ ID NO: 99. In some embodiments, the antibody binds the monomeric form of human CD33. In some embodiments, the antibody bindsthe dimeric form of human CD33. In some embodiments, the antibody binds cynomolgus monkey CD33. In some embodiments, the cynomolgus monkey CD33 comprises the amino acid sequence of SEQ ID NO: 98. In some embodiments, the antibody binds the monomeric form of cynomolgus monkey CD33. In some embodiments, the antibody binds the dimeric form of cynomolgus monkey CD33.

[0176] In some embodiments, the antibody does not significantly bind to human Siglec 6. In some embodiments, the antibody does not significantly bind to human Siglec 8.

[0177] In some embodiments, the antibody is capable of mediating internalization of the antibody in CD33+ cells. In some embodiments, the antibody has a Tregi tope-adjusted EpiMatrix Score equal to or less than 0, equal to or less than -25, or equal to or less than -45.III. Exemplary Antibody Variants, Fragments, and Constant Regions

[0178] In many embodiments, an antibody specifically binding to CD33 may further incorporate any of the features, singly or in combination, as described in the sections that follow.A. Antibody Fragments

[0179] In certain embodiments, an antibody provided herein is an antibody fragment. In some embodiments, the anti-CD33 antibody is an antibody fragment selected from an Fv, single-chain Fv (scFv), Fab, Fab’, or (Fab’)2. Antibody fragments include, but are not limited to, Fab, Fab’, Fab’-SH, F(ab’)2, Fv, and scFv fragments, and other fragments described below. For a review of certain antibody fragments, see Hudson et al. Nat. Med. 9: 129-134 (2003). For a review of scFv fragments, see, e.g., Pluckthiin, in The Pharmacology of Monoclonal Antibodies, vol. 113, Rosenburg and Moore eds., (Springer-Verlag, New York), pp. 269-315 (1994); see also WO 93 / 16185; and U.S. Patent Nos. 5,571,894 and 5, ’87, 458. For discussion of Fab and F(a”)2 fragments comprising salvage receptor binding epitope residues and having increased in vivo half-life, see U.S. Patent No. 5,869,046.

[0180] Diabodies are antibody fragments with two antigen-binding sites that may be bivalent or bispecific. See, for example, EP 404,097; WO 1993 / 01161; Hudson et al., Nat. Med. 9: 129-134 (2003); and Hollinger et al., Proc. Natl. Acad. Sci. USA 90: 6444-6448 (1993). Triabodies and tetrabodies are also described in Hudson et al., Nat. Med. 9: 129-134 (2003).

[0181] Single-domain antibodies are antibody fragments comprising all or a portion of the heavy chain variable domain or all or a portion of the light chain variable domain of an antibody. In certain embodiments, a single-domain antibody is a human single-domain antibody (Domantis, Inc., Waltham, MA; see, e.g., U.S. Patent No. 6,248,516).

[0182] Antibody fragments can be made by various techniques, including but not limited to proteolytic digestion of an intact antibody as well as production by recombinant host cells (e.g., E. coli or phage), as described herein.B. Bispecific or Multispecific Antibodies

[0183] In certain embodiments, an antibody provided herein is a multispecific antibody, for example, a bispecific antibody. Multispecific antibodies are monoclonal antibodies that have binding specificities for at least two different sites. In certain embodiments, one of the binding specificities is CD33 and the other is for any other antigen. In certain embodiments, bispecific antibodies may bind to two different epitopes of CD33. Bispecific antibodies may also be used to localize drugs such as cytotoxic agents or to localize detection labels to cells that express CD33. some embodiments, the multispecific antibody (e.g., bispecific antibody) comprises a first variable domain comprising the CDRs or variable regions as described herein. Bispecific antibodies can be prepared as full length antibodies or antibody fragments.

[0184] In some embodiments, an antibody provided herein is a bispecific antibody comprising a first antigen-binding domain that binds CD33 and a second antigen-binding domain that binds a second antigen. In various embodiments, the first antigen-binding domain is an antigen-binding domain that binds CD33 described herein. In some embodiments, the bispecific antibody is an immune cell engager. In some embodiments, the second antigen binding domain binds an antigen on the surface of T cells. In some embodiments, the second antigen binding domain binds an antigen on the surface of NK cells. In some embodiments, the second antigen binding domain of the bispecific antibody binds an antigen selected from CD3, CD16, CD16A, NKG2C, or NKG2D.

[0185] Techniques for making multispecific antibodies include, but are not limited to, recombinant co-expression of two immunoglobulin heavy chain-light chain pairs having different specificities (see Milstein and Cuello, Nature 305: 537 (1983)), WO 93 / 08829, and Traunecker et al., EMBO J. 10: 3655 (1991)), and “knob -in-hole” engineering (see, e.g., U.S. Patent No. 5,731,168). Multi-specific antibodies may also be made by engineering electrostatic steering effects for making antibody Fc-heterodimeric molecules (WO 2009 / 089004A1); crosslinking two or more antibodies or fragments (see, e.g., US Patent No. 4,676,980, and Brennan et al., Science, 229: 81 (1985)); using leucine zippers to produce bi-specific antibodies (see, e.g., Kostelny et al., J. Immunol., 18(5): 1547-1553 (1992)); using “diabod” technology for making bispecific antibody fragments (see, e.g., Hollinger et al., Proc. Natl. Acad. Sci. USA, 90:6444- 6448 (1993)); and using single-chain Fv (sFv) dimers (see, e.g. Gruber et al., J. Immunol, 152:5368 (1994)); and preparing trispecific antibodies as described, e.g., in Tutt et al. J.Immunol. 147: 60 (1991).

[0186] Engineered antibodies with three or more functional antigen binding sites, including “Octopus antibodies,” are also included herein (see, e.g. US 2006 / 0025576).C. Human Antibodies

[0187] In certain embodiments, an antibody provided herein is a human antibody. Human antibodies can be made by any suitable method. Nonlimiting exemplary methods include making human antibodies in transgenic mice that comprise human immunoglobulin loci. See, e.g., Jakobovits et al., Proc. Natl. Acad. Sci. USA 90: 2551-55 (1993); Jakobovits et al., Nature 362: 255-8 (1993); Lonberg et al., Nature 368: 856-9 (1994); and U.S. Patent Nos. 5,545,807; 6,713,610; 6,673,986; 6,162,963; 5,545,807; 6,300,129; 6,255,458; 5,877,397; 5,874,299; and 5,545,806.

[0188] Nonlimiting exemplary methods also include selecting human antibodies from phage display libraries. See, e.g., Hoogenboom et al., J. Mol. Biol. 227: 381-8 (1992); Marks et al., J. Mol. Biol. 222: 581-97 (1991); and PCT Publication No. WO 99 / 10494.D. Chimeric and Humanized Antibodies

[0189] In certain embodiments, an antibody provided herein is a chimeric antibody. Certain chimeric antibodies are described, e.g., in U.S. Patent No. 4,816,567; and Morrison et al., Proc. Natl. Acad. Sci. USA, 81 :6851-6855 (1984)). In one example, a chimeric antibody comprises a non-human variable region (e.g., a variable region derived from a mouse, rat, hamster, rabbit, or non-human primate, such as a monkey) and a human constant region. In a further example, a chimeric antibody is a “class switched” antibody in which the class or subclass has been changed from that of the parent antibody. Chimeric antibodies include antigen-binding fragments thereof.

[0190] In certain embodiments, a chimeric antibody is a humanized antibody. In some embodiments, an antibody provided herein is a humanized antibody. Typically, a non-human antibody is humanized to reduce immunogenicity to humans, while retaining the specificity and affinity of the parental non-human antibody. Generally, a humanized antibody comprises one or more variable domains in which HVRs, e.g., CDRs, (or portions thereof) are derived from a non-human antibody, and FRs (or portions thereof) are derived from human antibody sequences. A humanized antibody optionally will also comprise at least a portion of a human constant region. In some embodiments, some FR residues in a humanized antibody are substituted with corresponding residues from a non-human antibody (e.g., the antibody from which the HVR residues are derived), e.g., to restore or improve antibody specificity or affinity.

[0191] Humanized antibodies and methods of making them are reviewed, e.g., in Almagro and Fransson, Front. Biosci. 13: 1619-1633 (2008), and are further described, e.g., in Riechmann et al., Nature 332:323-329 (1988); Queen et al., Proc. Nat ’I Acad. Sci. USA 86: 10029-10033(1989); US Patent Nos. 5, 821,337, 7,527,791, 6,982,321, and 7,087,409; Kashmiri etal., Methods 36:25-34 (2005) (describing specificity determining region (SDR) grafting); Padlan, Mol. Immunol. 28:489-498 (1991) (describing “resurfacing”); Dall’Acqua et al., Methods 36:43- 60 (2005) (describing “FR shuffling”); and Osbourn et al., Methods 36:61-68 (2005) and Klimka et al., Br. J. Cancer, 83:252-260 (2000) (describing the “guided selection” approach to FR shuffling).

[0192] Human framework regions that may be used for humanization include but are not limited to framework regions selected using the “best-fit” method (see, e.g., Sims et al. J. Immunol.151 :2296 (1993)); framework regions derived from the consensus sequence of human antibodies of a particular subgroup of light or heavy chain variable regions (see, e.g., Carte r et al. Pro c. Natl. Acad. Set. USA, 89:4285 (1992); and Presta et al. J. Immunol., 151 :2623 (1993)); human mature (somatically mutated) framework regions or human germline framework regions (see, e.g., Almagro and Fransson, Front. Biosci. 13: 1619-1633 (2008)); and framework regions derived from screening FR libraries (see, e.g., Baca et al., J. Biol. Chem. 272: 10678-10684 (1997) and Rosok et al., J. Biol. Chem. 271 :22611-22618 (1996)).

[0193] In some embodiments, the humanized antibodies may comprise a human IgGl, IgG2, IgG3, or IgG4 heavy chain constant region.E. Glycosylation and Pegylation Variants

[0194] In certain embodiments, the glycosylation of an antibody is modified. For example, an aglycoslated antibody can be made (i.e., the antibody lacks glycosylation). Glycosylation can be altered to, for example, increase the affinity of the antibody for antigen. Such carbohydrate modifications can be accomplished by, for example, altering one or more sites of glycosylation within the antibody sequence. For example, one or more amino acid substitutions can be made that result in elimination of one or more variable region framework glycosylation sites to thereby eliminate glycosylation at that site. Such aglycosylation can increase the affinity of the antibody for antigen. Such an approach is described in further detail in U.S. Patent Nos.5,714,350 and 6,350,861 by Co et al.

[0195] Glycosylation of the constant region on N297 can be prevented by mutating the N297 residue to another residue, e.g., N297A, and / or by mutating an adjacent amino acid, e.g., 298 to thereby reduce glycosylation on N297.

[0196] Additionally or alternatively, an antibody can be made that has an altered type of glycosylation, such as a hypofucosylated antibody having reduced amounts of fucosyl residues or an antibody having increased bisecting GlcNac structures. Such altered glycosylation patterns have been demonstrated to increase the ADCC ability of antibodies. Such carbohydrate modifications can be accomplished by, for example, expressing the antibody in a host cell withaltered glycosylation machinery. Cells with altered glycosylation machinery have been described in the art and can be used as host cells in which to express recombinant antibodies described herein to thereby produce an antibody with altered glycosylation. For example, EP 1,176,195 by Hanai et al. describes a cell line with a functionally disrupted FUT8 gene, which encodes a fucosyl transferase, such that antibodies expressed in such a cell line exhibit hypofucosylation. PCT Publication WO 03 / 035835 by Presta describes a variant CHO cell line, Led 3 cells, with reduced ability to attach fucose to Asn(297)-linked carbohydrates, also resulting in hypofucosylation of antibodies expressed in that host cell (see also Shields, R.L. et al. (2002) J. Biol. Chem. 277:26733-26740). PCT Publication WO 99 / 54342 by Umana et al. describes cell lines engineered to express glycoprotein-modifying glycosyl transferases {e.g., beta(l,4)-N-acetylglucosaminyltransferase III (GnTIII)) such that antibodies expressed in the engineered cell lines exhibit increased bisecting GlcNac structures which results in increased ADCC activity of the antibodies (see also Umana et al. (1999) Nat. Biotech. 17: 176-180).

[0197] Another modification of the antibodies described herein is pegylation. An antibody can be pegylated to, for example, increase the biological (e.g., serum) half-life of the antibody. To pegylate an antibody, the antibody, or fragment thereof, typically is reacted with polyethylene glycol (PEG), such as a reactive ester or aldehyde derivative of PEG, under conditions in which one or more PEG groups become attached to the antibody or antibody fragment. In some embodiments, the pegylation is carried out via an acylation reaction or an alkylation reaction with a reactive PEG molecule (or an analogous reactive water-soluble polymer). As used herein, the term “polyethylene glycol” is intended to encompass any of the forms of PEG that have been used to derivatize other proteins, such as mono (CI-CIO) alkoxy- or aryloxy-polyethylene glycol or polyethylene glycol-maleimide. In certain embodiments, the antibody to be pegylated is an aglycosylated antibody. Methods for pegylating proteins are known in the art and can be applied to the antibodies described herein. See for example, EP 0 154 316 by Nishimura et al. and EP 0 401 384 by Ishikawa et al.F. Constant Regions

[0198] In some embodiments, the antibody is a full-length antibody. In some embodiments, an antibody described herein comprises one or more human constant regions. In some embodiments, the human heavy chain constant region is of an isotype selected from IgA, IgG, and IgD. In some embodiments, the human light chain constant region is of an isotype selected from K and X. In some embodiments, the antibody is an IgG antibody. In some embodiments, the antibody is an IgG antibody lacking a C-terminal lysine in the heavy chain constant region. In some embodiments, an antibody described herein comprises a human IgG constant region, such as an IgGl, IgG2, IgG3, or IgG4. In some embodiments, the antibody is an IgGl antibody, anIgG2 antibody, an IgG3 antibody, or an IgG4 antibody. In some embodiments, an antibody described herein comprises a human IgG4 heavy chain constant region. In some such embodiments, an antibody described herein comprises an S241P mutation in the human IgG4 constant region. In some embodiments, an antibody described herein comprises a human IgG4 constant region and a human K light chain.

[0199] In some embodiments, a human IgG heavy chain Fc region extends from Cys226, or from Pro230, to the carboxyl-terminus of the heavy chain at Gly446 and Lys447 (EU numbering). Antibodies produced by host cells may undergo post-translational cleavage of one or more, particularly one or two, amino acids from the C-terminus of the heavy chain. Therefore, an antibody produced by a host cell by expression of a specific nucleic acid molecule encoding a full-length heavy chain may include the full-length heavy chain and / or a cleaved variant of the full-length heavy chain. In some embodiments, the C-terminal lysine, or the C-terminal glycine and lysine, of the Fc region may or may not be present. Thus, a “full-length heavy chain constant region” or a “full length antibody” for example, which is a human IgGl antibody, includes an IgGl with both a C-terminal glycine and lysine, without the C-terminal lysine, or without both the C-terminal glycine and lysine.

[0200] The choice of heavy chain constant region can determine whether or not an antibody will have effector function in vivo. Such effector function, in some embodiments, includes antibodydependent cell-mediated cytotoxicity (ADCC) and / or complement-dependent cytotoxicity (CDC), and can result in killing of the cell to which the antibody is bound. In some methods of treatment, including methods of treating some cancers, cell killing may be desirable, for example, when the antibody binds to a cell that supports the maintenance or growth of the tumor. Exemplary cells that may support the maintenance or growth of a tumor include, but are not limited to, tumor cells themselves, cells that aid in the recruitment of vasculature to the tumor, and cells that provide ligands, growth factors, or counter-receptors that support or promote tumor growth or tumor survival. In some embodiments, when effector function is desirable, an antibody comprising a human IgGl heavy chain or a human IgG3 heavy chain is selected.

[0201] In certain embodiments, an antibody provided herein is altered to increase or decrease the extent to which the antibody is glycosylated. Addition or deletion of glycosylation sites to an antibody may be conveniently accomplished by altering the amino acid sequence such that one or more glycosylation sites is created or removed.

[0202] Where the antibody comprises an Fc region, the carbohydrate attached thereto may be altered. Native antibodies produced by mammalian cells typically comprise a branched, biantennary oligosaccharide that is generally attached by an N-linkage to Asn297 of the CH2domain of the Fc region. See, e.g., Wright et al. TIBTECH 15:26-32 (1997). The oligosaccharide may include various carbohydrates, e.g., mannose, N-acetyl glucosamine (GlcNAc), galactose, and sialic acid, as well as a fucose attached to a GlcNAc in the “stem” of the biantennary oligosaccharide structure. In some embodiments, modifications of the oligosaccharide in an antibody of the invention may be made in order to create antibodies with certain improved properties. For example, in some embodiments an antibody may be afucosylated, for example, by mutating residues such as Asn297 that are normally glycosylated with fucose-containing glycosylations, or through other means. In some embodiments, antibodies herein may comprise an afucosylated human IgGl constant region.

[0203] Antibodies are further provided with bisected oligosaccharides, e.g., in which a biantennary oligosaccharide attached to the Fc region of the antibody is bisected by GlcNAc. Such antibodies may have reduced fucosylation and / or improved ADCC function. Examples of such antibodies are described, e.g., in WO 2003 / 011878 (Jean-Mairet et al.); US Patent No. 6,602,684 (Umana et al.); and US 2005 / 0123546 (Umana et al.). Antibodies with at least one galactose residue in the oligosaccharide attached to the Fc region are also provided. Such antibodies may have improved CDC function. Such antibodies are described, e.g., in WO 1997 / 30087 (Patel et al.); WO 1998 / 58964 (Raju, S.); and WO 1999 / 22764 (Raju, S.).

[0204] Antibodies are also provided with amino-terminal leader extensions. For example, one or more amino acid residues of the amino-terminal leader sequence are present at the aminoterminus of any one or more heavy or light chains of an antibody. An exemplary amino-terminal leader extension comprises or consists of three amino acid residues, VHS, present on one or both light chains of an antibody.

[0205] The in vivo or serum half-life of human FcRn high affinity binding polypeptides can be assayed, e.g., in transgenic mice, in humans, or in non-human primates to which the polypeptides with a variant Fc region are administered. See also, e.g., Petkova et al. International Immunology 18(12): 1759-1769 (2006).

[0206] In some embodiments of the invention, an afucosylated antibody mediates ADCC in the presence of human effector cells more effectively than a parent antibody that comprises fucose, Generally, ADCC activity may be determined using the in vitro ADCC assay as herein disclosed, but other assays or methods for determining ADCC activity, e.g. in an animal model etc., are contemplated.

[0207] In certain embodiments, the Fc region is altered by replacing at least one amino acid residue with a different amino acid residue to alter the effector function(s) of the antibody. For example, one or more amino acids selected from amino acid residues 234, 235, 236, 237, 297, 318, 320, 322, 330, and / or 331 (EU numbering) can be replaced with a different amino acidresidue such that the antibody has an altered affinity for an effector ligand but retains the antigen-binding ability of the parent antibody. The effector ligand to which affinity is altered can be, for example, an Fc receptor or the Cl component of complement. This approach is described in further detail in U.S. Patent Nos. 5,624,821 and 5,648,260, both by Winter et al.

[0208] In some examples, one or more amino acids selected from amino acid residues 329, 331 and 322 can be replaced with a different amino acid residue such that the antibody has altered Clq binding and / or reduced or abolished complement dependent cytotoxicity (CDC). This approach is described in further detail in U.S. Patent Nos. 6,194,551 by Idusogie et al.

[0209] In some examples, one or more amino acid residues within amino acid positions 231 and 239 are altered to thereby alter the ability of the antibody to fix complement. This approach is described further in PCT Publication WO 94 / 29351 by Bodmer et al. In some examples, the Fc region can be modified to decrease antibody dependent cellular cytotoxicity (ADCC) and / or to decrease the affinity for an Fey receptor by modifying one or more amino acids at the following positions: 234, 235, 236, 238, 239, 240, 241 , 243, 244, 245, 247, 248, 249, 252, 254, 255, 256, 258, 262, 263, 264, 265, 267, 268, 269, 270, 272, 276, 278, 280, 283, 285, 286, 289, 290, 292,293, 294, 295, 296, 298, 299, 301, 303, 305, 307, 309, 312, 313, 315, 320, 322, 324, 325, 326,327, 329, 330, 331, 332, 333, 334, 335, 337, 338, 340, 360, 373, 376, 378, 382, 388, 389, 398,414, 416, 419, 430, 433, 434, 435, 436, 437, 438 or 439 (EU numbering). Exemplary substitutions include 236A, 239D, 239E, 268D, 267E, 268E, 268F, 324T, 332D, and 332E. Exemplary variants include 239D / 332E, 236A / 332E, 236A / 239D / 332E, 268F / 324T, 267E / 268F, 267E / 324T, and 267E / 268F7324T (EU numbering). Other Fc modifications that can be made to Fes are those for reducing or ablating binding to FcyR and / or complement proteins, thereby reducing or ablating Fc-mediated effector functions such as ADCC, ADCP, and CDC.Exemplary modifications include but are not limited substitutions, insertions, and deletions at positions 234, 235, 236, 237, 267, 269, 325, 328, 330, and / or 331 (e.g., 330 and 331), wherein numbering is according to the EU index. Exemplary substitutions include but are not limited to 234A, 235E, 236R, 237A, 267R, 269R, 325L, 328R, 330S, and 33 IS (e.g., 330S, and 33 IS), wherein numbering is according to the EU index. An Fc variant can comprise 236R / 328R. Other modifications for reducing FcyR and complement interactions include substitutions 297 A, 234A, 235A, 237A, 318A, 228P, 236E, 268Q, 309L, 330S, 331 S, 220S, 226S, 229S, 238S, 233P, and 234V, as well as removal of the glycosylation at position 297 by mutational or enzymatic means or by production in organisms such as bacteria that do not glycosylate proteins. These and other modifications are reviewed in Strohl, 2009, Current Opinion in Biotechnology 20:685-691. For example, the human IgG1.3 Fc constant region contains L234A, L235E, and G237A substitutions. The IgGlfa.P238K (or IgGl.P238K) contains a P238K substitution. The IgGl.lfcomprises L234A, L235E, G237A, A330S, and P331S substitutions. (All numbering under the EU index.)

[0210] Fc variants that enhance affinity for an inhibitory receptor FcyRIIb can also be used. Such variants can provide an Fc fusion protein with immunomodulatory activities related to FcyRIIb cells, including for example, B cells and monocytes. In one embodiment, the Fc variants provide selectively enhanced affinity to FcyRIIb relative to one or more activating receptors. Modifications for altering binding to FcyRIIb include one or more modifications at a position selected from the group consisting of 234, 235, 236, 237, 239, 266, 267, 268, 325, 326, 327, 328, 330, 331, and 332, according to the EU index. Exemplary substitutions for enhancing FcyRIIb affinity include but are not limited to 234A, 234D, 234E, 234F, 234W, 235D, 235E, 235F, 235R, 235 Y, 236D, 236N, 237 A, 237D, 237N, 239D, 239E, 266M, 267D, 267E, 268D, 268E, 327D, 327E, 328F, 328W, 328Y, 330S, 33 IS, and 332E. Exemplary substitutions include 235Y, 236D, 239D, 266M, 267E, 268D, 268E, 328F, 328W, and 328Y. Other Fc variants for enhancing binding to FcyRIIb include 235Y / 267E, 236D / 267E, 239D / 268D, 239D / 267E, 267E / 268D, 267E / 268E, and 267E / 328F. (All numbering under the EU index.)

[0211] Other modifications for enhancing FcyR and complement interactions include but are not limited to substitutions 298 A, 333A, 334A, 326A, 2471, 339D, 339Q, 280H, 290S, 298D, 298V, 243L, 292P, 300L, 396L, 3051, and 396L. These and other modifications are reviewed in Strohl, 2009, Current Opinion in Biotechnology 20:685-691. Fc modifications that increase binding to an Fey receptor include amino acid modifications at any one or more of amino acid positions 238, 239, 248, 249, 252, 254, 255, 256, 258, 265, 267, 268, 269, 270, 272, 279, 280, 283, 285, 298, 289, 290, 292, 293, 294, 295, 296, 298, 301, 303, 305, 307, 312, 315, 324, 327, 329, 330, 335, 337, 338, 340, 360, 373, 376, 379, 382, 388, 389, 398, 414, 416, 419, 430, 434, 435, 437, 438 or 439 of the Fc region, wherein the numbering of the residues in the Fc region is that of the EU index as in Patent Publication No. WO 00 / 42072.

[0212] Optionally, the Fc region can comprise a non-naturally occurring amino acid residue at additional and / or alternative positions known to one skilled in the art (see, e.g., U.S. Pat. Nos. 5,624,821; 6,277,375; 6,737,056; 6,194,551; 7,317,091; 8,101,720; PCX Patent Publications WO 00 / 42072; WO 01 / 58957; WO 02 / 06919; WO 04 / 016750; WO 04 / 029207; WO 04 / 035752; WO 04 / 074455; WO 04 / 099249; WO 04 / 063351; WO 05 / 070963; WO 05 / 040217, WO 05 / 092925 and WO 06 / 0201 14).

[0213] The affinities and binding properties of an Fc region for its ligand can be determined by a variety of in vitro assay methods (biochemical or immunological based assays) known in the art including but not limited to, equilibrium methods (e.g., enzyme-linked immunosorbent assay (ELISA), or radioimmunoassay (RIA)), or kinetics (e.g., BIACORE analysis), and othermethods such as indirect binding assays, competitive inhibition assays, fluorescence resonance energy transfer (FRET), gel electrophoresis and chromatography (e.g., gel filtration). These and other methods can utilize a label on one or more of the components being examined and / or employ a variety of detection methods including but not limited to chromogenic, fluorescent, luminescent, or isotopic labels. A detailed description of binding affinities and kinetics can be found in Paul, W. E., ed., Fundamental immunology, 4th Ed., Lippincott-Raven, Philadelphia (1999), which focuses on antibody-immunogen interactions.

[0214] In certain embodiments, the antibody is modified to increase its biological half-life. Various approaches are possible. For example, this can be done by increasing the binding affinity of the Fc region for FcRn, For example, one or more of more of following residues can be mutated: 252, 254, 256, 433, 435, 436, as described in U.S. Pat. No. 6,277,375. Specific exemplary substitutions include one or more of the following: T252L, T254S, and / or T256F. Alternatively, to increase the biological half life, the antibody can be altered within the CHI or CL region to contain a salvage receptor binding epitope taken from two loops of a CH2 domain of an Fc region of an IgG, as described in U.S. Patent Nos. 5,869,046 and 6,121,022 by Presta et al. Other exemplary variants that increase binding to FcRn and / or improve pharmacokinetic properties include substitutions at positions 259, 308, 428, and 434, including for example 2591, 308F, 428L, 428M, 434S, 4341 1. 434F, 434Y, and 434X1. Other variants that increase Fc binding to FcRn include: 250E, 250Q, 428 L, 428F, 250Q / 428L (Hinton et al. 2004, J. Biol. Chem. 279(8): 6213-6216, Hinton et al. 2006 Journal of Immunology 176:346-356), 256A, 272A, 286A, 305A, 307A, 307Q, 31 1A, 312A, 376A, 378Q, 380A, 382A, 434A (Shields et al., Journal of Biological Chemistry, 2001, 276(9):6591-6604), 252F, 252T, 252Y, 252W, 254T, 256S, 256R, 256Q, 256E, 256D, 256T, 309P, 31 1 S, 433R, 433S, 4331, 433P, 433Q, 434H, 434F, 434Y, 252Y / 254T / 256E, 433K / 434F / 436H, 308T / 309P / 311S (Dall’Acqua et al. Journal of Immunology, 2002, 169:5171-5180, Dal’Acqua et al., 2006, Journal of Biological Chemistry 281 :23514-23524). Other modifications for modulating FcRn binding are described in Yeung et al., 2010, J Immunol, 182:7663-7671.

[0215] In certain embodiments, hybrid IgG isotypes with particular biological characteristics can be used. For example, an IgGl / IgG3 hybrid variant can be constructed by substituting IgGl positions in the CH2 and / or CH3 region with the amino acids from IgG3 at positions where the two isotypes differ. Thus a hybrid variant IgG antibody can be constructed that comprises one or more substitutions, e.g., 274Q, 276K, 300F, 339T, 356E, 358M, 384S, 392N, 397M, 4221, 435R, and 436F. In some embodiments described herein, an IgGl / IgG2 hybrid variant can be constructed by substituting IgG2 positions in the CH2 and / or CH3 region with amino acids from IgGl at positions where the two isotypes differ. Thus a hybrid variant IgG antibody can beconstructed that comprises one or more substitutions, e.g., one or more of the following amino acid substitutions: 233E, 234L, 235L, +236G (referring to an insertion of a glycine at position 236), and 327A.

[0216] Moreover, the binding sites on human IgGl for FcyRI, FcyRII, FcyRIII and FcRn have been mapped and variants with improved binding have been described (see Shields, R.L. et al. (2001) J. Biol. Chem. 276:6591-6604). Specific mutations at positions 256, 290, 298, 333, 334 and 339 were shown to improve binding to FcyRIII. Additionally, the following combination mutants were shown to improve FcyRIII binding: T256A / S298A, S298A / E333A, S298A / K224A and S298A / E333A / K334A, which has been shown to exhibit enhanced FcyRIIIa binding and ADCC activity (Shields etal., 2001). Other IgGl variants with strongly enhanced binding to FcyRIIIa have been identified, including variants with S239D / I332E and S239D / I332E / A330L mutations which showed the greatest increase in affinity for FcyRIIIa, a decrease in FcyRIIb binding, and strong cytotoxic activity in cynomolgus monkeys (Lazar et al., 2006). Introduction of the triple mutations into antibodies such as alemtuzumab (CD52-specific), trastuzumab (HER2 / neu-specific), rituximab (CD20-specific), and cetuximab (EGFR- specific) translated into greatly enhanced ADCC activity in vitro, and the S239D / I332E variant showed an enhanced capacity to deplete B cells in monkeys (Lazar et al., 2006). In addition, IgGl mutants containing L235V, F243L, R292P, Y300L and P396L mutations which exhibited enhanced binding to FcyRIIIa and concomitantly enhanced ADCC activity in transgenic mice expressing human FcyRIIIa in models of B cell malignancies and breast cancer have been identified (Stavenhagen et al., 2007; Nordstrom et al., 2011). Other Fc mutants that can be used include: S298A / E333A / L334A, S239D / I332E, S239D / I332E / A330L, L235V / F243L / R292P / Y300L / P396L, and M428L / N434S.

[0217] In certain embodiments, an Fc is chosen that has reduced binding to FcyRs. An exemplary Fc, e.g., IgGl Fc, with reduced FcyR binding comprises the following three amino acid substitutions: L234A, L235E and G237A.

[0218] In certain embodiments, an Fc is chosen that has reduced complement fixation. An exemplary Fc, e.g., IgGl Fc, with reduced complement fixation has the following two amino acid substitutions: A330S and P331S.

[0219] In certain embodiments, an Fc is chosen that has essentially no effector function, i.e., it has reduced binding to FcyRs and reduced complement fixation. An exemplary Fc, e.g., IgGl Fc, that is effectorless comprises the following five mutations: L234A, L235E, G237A, A330S and P331S.

[0220] When using an IgG4 constant domain, it can include the substitution S228P, which mimics the hinge sequence in IgGl and thereby stabilizes IgG4 molecules. Fc modifications described in WO 2017 / 087678 or WO2016081746 may also be used.

[0221] In certain embodiments, the glycosylation of an antibody is modified. For example, an aglycoslated antibody can be made (i.e., the antibody lacks glycosylation). Glycosylation can be altered to, for example, increase the affinity of the antibody for antigen. Such carbohydrate modifications can be accomplished by, for example, altering one or more sites of glycosylation within the antibody sequence. For example, one or more amino acid substitutions can be made that result in elimination of one or more variable region framework glycosylation sites to thereby eliminate glycosylation at that site. Such aglycosylation can increase the affinity of the antibody for antigen. Such an approach is described in further detail in U.S. Patent Nos. 5,714,350 and 6,350,861 by Co et al.

[0222] Glycosylation of the constant region on N297 can be prevented by mutating the N297 residue to another residue, e.g., N297A, and / or by mutating an adjacent amino acid, e.g., 298 to thereby reduce glycosylation on N297.

[0223] Additionally or alternatively, an antibody can be made that has an altered type of glycosylation, such as a hypofucosylated antibody having reduced amounts of fucosyl residues or an antibody having increased bisecting GlcNac structures. Such altered glycosylation patterns have been demonstrated to increase the ADCC ability of antibodies. Such carbohydrate modifications can be accomplished by, for example, expressing the antibody in a host cell with altered glycosylation machinery. Cells with altered glycosylation machinery have been described in the art and can be used as host cells in which to express recombinant antibodies described herein to thereby produce an antibody with altered glycosylation. For example, EP 1,176,195 by Hanai et al. describes a cell line with a functionally disrupted FUT8 gene, which encodes a fucosyl transferase, such that antibodies expressed in such a cell line exhibit hypofucosylation. PCT Publication WO 03 / 035835 by Presta describes a variant CHO cell line, Led 3 cells, with reduced ability to attach fucose to Asn(297)-linked carbohydrates, also resulting in hypofucosylation of antibodies expressed in that host cell (see also Shields, R.L. et al. (2002) J. Biol. Chem. 277:26733-26740). PCT Publication WO 99 / 54342 by Umana et al. describes cell lines engineered to express glycoprotein-modifying glycosyl transferases {e.g., beta(l,4)-N-acetylglucosaminyltransferase III (GnTIII)) such that antibodies expressed in the engineered cell lines exhibit increased bisecting GlcNac structures which results in increased ADCC activity of the antibodies (see also Umana et al. (1999) Nat. Biotech. 17: 176-180).

[0224] Another modification of the antibodies described herein is pegylation. An antibody can be pegylated to, for example, increase the biological (e.g., serum) half-life of the antibody. Topegylate an antibody, the antibody, or fragment thereof, typically is reacted with polyethylene glycol (PEG), such as a reactive ester or aldehyde derivative of PEG, under conditions in which one or more PEG groups become attached to the antibody or antibody fragment. In some embodiments, the pegylation is carried out via an acylation reaction or an alkylation reaction with a reactive PEG molecule (or an analogous reactive water-soluble polymer). As used herein, the term “polyethylene glycol" is intended to encompass any of the forms of PEG that have been used to derivatize other proteins, such as mono (CI-CIO) alkoxy- or aryloxy-polyethylene glycol or polyethylene glycol-maleimide. In certain embodiments, the antibody to be pegylated is an aglycosylated antibody. Methods for pegylating proteins are known in the art and can be applied to the antibodies described herein. See for example, EP 0 154 316 by Nishimura et al. and EP 0 401 384 by Ishikawa et al.IV. Nucleic Acid Molecules Encoding Anti-CD33 Antibodies

[0225] Nucleic acid molecules comprising polynucleotides that encode one or more chains of anti-CD33 antibodies described herein are provided. In some embodiments, a nucleic acid molecule comprises a polynucleotide that encodes a heavy chain or a light chain of an anti- CD33 antibody. In some embodiments, provided is an isolated nucleic acid encoding any one of the anti-CD33 antibodies provided herein. In some embodiments, a nucleic acid molecule comprises both a polynucleotide that encodes a heavy chain and a polynucleotide that encodes a light chain, of an anti-CD33 antibody. In some embodiments, a first nucleic acid molecule comprises a first polynucleotide that encodes a heavy chain and a second nucleic acid molecule comprises a second polynucleotide that encodes a light chain.

[0226] In some such embodiments, the heavy chain and the light chain are expressed from one nucleic acid molecule, or from two separate nucleic acid molecules, as two separate polypeptides. In some embodiments, such as when an antibody is an scFv, a single polynucleotide encodes a single polypeptide comprising both a heavy chain and a light chain linked together.

[0227] In some embodiments, a polynucleotide encoding a heavy chain or light chain of an anti- CD33 antibody comprises a nucleotide sequence that encodes a leader sequence, which, when translated, is located at the N terminus of the heavy chain or light chain. The leader sequence may be the native heavy or light chain leader sequence, or may be another heterologous leader sequence.

[0228] Nucleic acid molecules may be constructed using recombinant DNA techniques conventional in the art. In some embodiments, a nucleic acid molecule is an expression vector that is suitable for expression in a selected host cell.V. Anti-CD33 Antibody Expression and ProductionA. Vectors

[0229] Vectors comprising polynucleotides that encode anti-CD33 heavy chains and / or anti- CD33 light chains are provided. In some embodiments, provided herein is a vector comprising a nucleic acid encoding any one of the anti-CD33 antibodies described herein. Vectors comprising polynucleotides that encode anti-CD33 heavy chains and / or anti-CD33 light chains are also provided. Such vectors include, but are not limited to, DNA vectors, RNA vectors (e.g., mRNA and circular RNA, self-amplifying RNA vectors, etc.), phage vectors, viral vectors (e.g., pox virus vectors, vaccinia virus vectors, adenovirus vectors, modified vaccinia virus Ankara (MV A) vectors, etc.), retroviral vectors, etc. In some embodiments, a vector comprises a first polynucleotide sequence encoding a heavy chain and a second polynucleotide sequence encoding a light chain. In some embodiments, the heavy chain and light chain are expressed from the vector as two separate polypeptides. In some embodiments, the heavy chain and light chain are expressed as part of a single polypeptide, such as, for example, when the antibody is an scFv.

[0230] In some embodiments, a first vector comprises a polynucleotide that encodes a heavy chain and a second vector comprises a polynucleotide that encodes a light chain. In some embodiments, the first vector and second vector are transfected into host cells in similar amounts (such as similar molar amounts or similar mass amounts). In some embodiments, a mole- or mass-ratio of between 5: 1 and 1 :5 of the first vector and the second vector is transfected into host cells. In some embodiments, a mass ratio of between 1 : 1 and 1 :5 for the vector encoding the heavy chain and the vector encoding the light chain is used. In some embodiments, a mass ratio of 1 :2 for the vector encoding the heavy chain and the vector encoding the light chain is used.

[0231] In some embodiments, a vector is selected that is optimized for expression of polypeptides in CHO or CHO-derived cells, or in NSO cells. Exemplary such vectors are described, e.g., in Running Deer et al., BiotechnoL Prog. 20:880-889 (2004).

[0232] In some embodiments, a vector is chosen for in vivo expression anti-CD33 heavy chains and / or anti-CD33 light chains in animals, including humans. In some such embodiments, expression of the polypeptide is under the control of a promoter that functions in a tissuespecific manner. For example, liver-specific promoters are described, e.g., in PCT Publication No. WO 2006 / 076288.B. Host Cells

[0233] In various embodiments, anti-CD33 heavy chains and / or anti-CD33 light chains may be expressed in prokaryotic cells, such as bacterial cells; or in eukaryotic cells, such as fungal cells(such as yeast), plant cells, insect cells, and mammalian cells. Such expression may be carried out, for example, according to procedures known in the art. In some embodiments, provided herein are host cells comprising an isolated nucleic acid encoding any one of the anti-CD33 antibodies described herein. In some embodiments, provided herein are host cells comprising a vector comprising a nucleic acid encoding any one of the anti-CD33 antibodies described herein. In some embodiments, provided herein is a host cell that produces any one of the anti-CD33 antibodies described herein. Exemplary eukaryotic cells that may be used to express polypeptides include, but are not limited to, COS cells, including COS 7 cells; 293 cells, including 293-6E cells; CHO cells, including CHO-S and DG44 cells; PER.C6® cells (Crucell); and NSO cells. In some embodiments, anti-CD33 heavy chains and / or anti-CD33 light chains may be expressed in yeast. See, e.g., U.S. Publication No. US 2006 / 0270045 Al. In some embodiments, a particular eukaryotic host cell is selected based on its ability to make desired post-translational modifications to the anti-CD33 heavy chains and / or anti-CD33 light chains. For example, in some embodiments, CHO cells produce polypeptides that have a higher level of sialylation than the same polypeptide produced in 293 cells.

[0234] Introduction of one or more nucleic acids into a desired host cell may be accomplished by any method, including but not limited to, calcium phosphate transfection, DEAE-dextran mediated transfection, cationic lipid-mediated transfection, electroporation, transduction, infection, etc. Nonlimiting exemplary methods are described, e.g., in Sambrook et al., Molecular Cloning, A Laboratory Manual, 3rded. Cold Spring Harbor Laboratory Press (2001). Nucleic acids may be transiently or stably transfected in the desired host cells, according to any suitable method.

[0235] In some embodiments, one or more polypeptides may be produced in vivo in an animal that has been engineered or transfected with one or more nucleic acid molecules encoding the polypeptides, according to any suitable method.

[0236] In some embodiments, provided herein is a method for making an anti-CD33 antibody described herein, comprising culturing a host cell described herein under conditions suitable for expression of the antibody. In some embodiments, the method further comprises recovering the antibody produced by the host cell.C. Purification of Anti-CD33 Antibodies

[0237] Anti-CD33 antibodies may be purified by any suitable method. Such methods include, but are not limited to, the use of affinity matrices or hydrophobic interaction chromatography or size exclusion chromatography.D. Cell-free Production of Anti-CD33 Antibodies

[0238] In some embodiments, an anti-CD33 antibody is produced in a cell-free system. Nonlimiting exemplary cell-free systems are described, e.g., in Sitaraman et al., Methods Mol. Biol. 498: 229-44 (2009); Spirin, Trends Biotechnol. 22: 538-45 (2004); Endo et al., Biotechnol. Adv. 21 : 695-713 (2003).VI. Exemplary Antibody-Drug Conjugates

[0239] The anti-CD33 antibodies described herein may be included in an antibody-drug conjugate. An antibody-drug conjugate typically comprises three components: Antibody, Payload, and Linker. In some embodiments, the Antibody targets the ADC to a particular cell type and may also elicit a therapeutic response, the Payload elicits a desired therapeutic response, and the Linker attaches the Payload to the Antibody. Often, the Payload is coupled via the Linker to an Antibody that specifically targets a certain tumor antigen (e.g., a protein that is expressed at higher levels on tumor cells compared to normal cells). In some embodiments, an antibody binds its antigen on the surface of a cell, such as a cancer cell, and the ADC is internalized by the cell. In some such embodiments, after the ADC is internalized, the Payload elicits the desired therapeutic response, for example, in the case of a Payload which is an anticancer agent, the Payload inhibits the expansion of, or kills, the cancer cell.

[0240] In some embodiments, the Payload is an anticancer drug. In some embodiments, the Payload is a radioisotope.VII. Exemplary Chimeric Antigen Receptors

[0241] The anti-CD33 antibodies described herein may be included in a chimeric antigen receptor (CAR). A CAR typically comprises an extracellular binding domain, a spacer, a transmembrane domain, and an intracellular signaling domain. The anti-CD33 antibodies or fragments thereof described herein are suitable for use in the extracellular binding domain of a CAR. In some embodiments, a T-cell comprises a CAR, which comprises an anti-CD33 antibody or fragment thereof described herein.VIII. Therapeutic Compositions and MethodsA. Methods of Treating Diseases

[0242] In one embodiment, provided herein is a method of treating and / or preventing cancer, which comprises administering to a patient a compound, antibody, or antibody-drug conjugate provided herein.

[0243] In another embodiment, provided herein is method of managing cancer, which comprises administering to a patient a compound, antibody, or antibody-drug conjugate provided herein.

[0244] Also provided herein are methods of treating patients who have been previously treated for cancer but are non-responsive to standard therapies, as well as those who have not previouslybeen treated. Also encompassed are methods of treating patients regardless of patient's age, although some diseases or disorders are more common in certain age groups. Further encompassed are methods of treating patients who have undergone surgery in an attempt to treat the disease or condition at issue, as well as those who have not. Because patients with cancer have heterogeneous clinical manifestations and varying clinical outcomes, the treatment given to a patient may vary, depending on his / her prognosis. The skilled clinician will be able to readily determine without undue experimentation specific secondary agents, types of surgery, and types of non-drug based standard therapy that can be effectively used to treat an individual patient with cancer.

[0245] As used herein, the term “cancer” includes, but is not limited to, solid tumors and blood borne tumors. The term “cancer” refers to disease of skin tissues, organs, blood, and vessels, including, but not limited to, cancers of the bladder, bone, blood, brain, breast, cervix, chest, colon, endometrium, esophagus, eye, head, kidney, liver, lymph nodes, lung, mouth, neck, ovaries, pancreas, prostate, rectum, stomach, testis, throat, and uterus. Specific cancers include, but are not limited to, advanced malignancy, amyloidosis, neuroblastoma, meningioma, hemangiopericytoma, multiple brain metastases, glioblastoma multiforms, glioblastoma, brain stem glioma, poor prognosis malignant brain tumor, malignant glioma, recurrent malignant glioma, anaplastic astrocytoma, anaplastic oligodendroglioma, neuroendocrine tumor, rectal adenocarcinoma, Dukes C & D colorectal cancer, unresectable colorectal carcinoma, metastatic hepatocellular carcinoma, Kaposi's sarcoma, karotype acute myeloblastic leukemia, Hodgkin's lymphoma, non-Hodgkin's lymphoma, cutaneous T-Cell lymphoma, cutaneous B-Cell lymphoma, diffuse large B-Cell lymphoma, low grade follicular lymphoma, malignant melanoma, malignant mesothelioma, malignant pleural effusion mesothelioma syndrome, peritoneal carcinoma, papillary serous carcinoma, gynecologic sarcoma, soft tissue sarcoma, scleroderma, cutaneous vasculitis, Langerhans cell histiocytosis, leiomyosarcoma, fibrodysplasia ossificans progressive, hormone refractory prostate cancer, resected high-risk soft tissue sarcoma, unresectable hepatocellular carcinoma, Waldenstrom's macroglobulinemia, smoldering myeloma, indolent myeloma, fallopian tube cancer, androgen independent prostate cancer, androgen dependent stage IV non-metastatic prostate cancer, hormone-insensitive prostate cancer, chemotherapy-insensitive prostate cancer, urachal cancer, papillary thyroid carcinoma, follicular thyroid carcinoma, medullary thyroid carcinoma, and leiomyoma.

[0246] In certain embodiments, the cancer is a solid tumor. In certain embodiments, the solid tumor is metastatic. In certain embodiments, the solid tumor is drug-resistant. In certain embodiments, the solid tumor is hepatocellular carcinoma, prostate cancer, ovarian cancer, or glioblastoma.

[0247] In certain embodiments, the cancer is a blood borne tumor. In certain embodiments, the blood borne tumor is metastatic. In certain embodiments, the blood borne tumor is drug resistant. In certain embodiments, the cancer is leukemia.

[0248] In one embodiment, methods provided herein encompass treating, preventing or managing various types of leukemias such as chronic lymphocytic leukemia (CLL), chronic myelocytic leukemia (CML), acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), and acute myeloblastic leukemia (AML) by administering a therapeutically effective amount of a compound, antibody, or antibody-drug conjugate provided herein.

[0249] In some embodiments, the methods provided herein encompass treating, preventing or managing acute leukemia in a subject. In some embodiments, the acute leukemia is acute myeloid leukemia (AML), which includes, but is not limited to, undifferentiated AML (MO), myeloblastic leukemia (Ml), myeloblastic leukemia (M2), promyelocytic leukemia (M3 or M3 variant [M3 V]), myelomonocytic leukemia (M4 or M4 variant with eosinophilia [M4E]), monocytic leukemia (M5), erythroleukemia (M6), and megakaryoblastic leukemia (M7). In one embodiment, the acute myeloid leukemia is undifferentiated AML (MO). In one embodiment, the acute myeloid leukemia is myeloblastic leukemia (Ml). In one embodiment, the acute myeloid leukemia is myeloblastic leukemia (M2). In one embodiment, the acute myeloid leukemia is promyelocytic leukemia (M3 or M3 variant [M3 V]). In one embodiment, the acute myeloid leukemia is myelomonocytic leukemia (M4 or M4 variant with eosinophilia [M4E]). In one embodiment, the acute myeloid leukemia is monocytic leukemia (M5). In one embodiment, the acute myeloid leukemia is erythroleukemia (M6). In one embodiment, the acute myeloid leukemia is megakaryoblastic leukemia (M7). Thus, the methods of treating, preventing or managing acute myeloid leukemia in a subject comprise the step of administering to the subject an amount of a compound, antibody, or antibody-drug conjugate provided herein effective to treat, prevent or manage acute myeloid leukemia alone or in combination. In some embodiments, the methods comprise the step of administering to the subject a compound, antibody, or antibody-drug conjugate provided herein in combination with a second active agent in amounts effective to treat, prevent or manage acute myeloid leukemia.

[0250] In some embodiments, the methods provided herein encompass treating, preventing or managing acute lymphocytic leukemia (ALL) in a subject. In some embodiments, acute lymphocytic leukemia includes leukemia that originates in the blast cells of the bone marrow (B- cells), thymus (T-cells), and lymph nodes. The acute lymphocytic leukemia can be categorized according to the French-American-British (FAB) Morphological Classification Scheme as LI — Mature-appearing lymphoblasts (T-cells or pre-B-cells), L2 — Immature and pleomorphic (variously shaped) lymphoblasts (T-cells or pre-B-cells), and L3 — Lymphoblasts (B-cells;Burkitt’s cells). In one embodiment, the acute lymphocytic leukemia originates in the blast cells of the bone marrow (B-cells). In one embodiment, the acute lymphocytic leukemia originates in the thymus (T-cells). In one embodiment, the acute lymphocytic leukemia originates in the lymph nodes. In one embodiment, the acute lymphocytic leukemia is LI type characterized by mature-appearing lymphoblasts (T-cells or pre-B-cells). In one embodiment, the acute lymphocytic leukemia is L2 type characterized by immature and pleomorphic (variously shaped) lymphoblasts (T-cells or pre-B-cells). In one embodiment, the acute lymphocytic leukemia is L3 type characterized by lymphoblasts (B-cells; Burkitt’s cells). In certain embodiments, the acute lymphocytic leukemia is T-cell leukemia. In one embodiment, the T-cell leukemia is peripheral T-cell leukemia. In another embodiment, the T-cell leukemia is T-cell lymphoblastic leukemia. In another embodiment, the T-cell leukemia is cutaneous T-cell leukemia. In another embodiment, the T-cell leukemia is adult T-cell leukemia. Thus, the methods of treating, preventing or managing acute lymphocytic leukemia in a subject comprise the step of administering to the subject an amount of a compound, antibody, or antibody-drug conjugate provided herein effective to treat, prevent or manage acute lymphocytic leukemia alone or in combination with a second active agent. In some embodiments, the methods comprise the step of administering to the subject a compound, antibody, or antibody-drug conjugate provided herein in combination with a second active agent in amounts effective to treat, prevent or manage acute lymphocytic leukemia.

[0251] In some embodiments, the methods provided herein encompass treating, preventing or managing chronic myelogenous leukemia (CML) in a subject. The methods comprise the step of administering to the subject an amount of a compound, antibody, or antibody-drug conjugate provided herein effective to treat, prevent or manage chronic myelogenous leukemia. In some embodiments, the methods comprise the step of administering to the subject a compound, antibody, or antibody-drug conjugate provided herein in combination with a second active agent in amounts effective to treat, prevent or manage chronic myelogenous leukemia.

[0252] In some embodiments, the methods provided herein encompass treating, preventing or managing chronic lymphocytic leukemia (CLL) in a subject. The methods comprise the step of administering to the subject an amount of a compound, antibody, or antibody-drug conjugate provided herein effective to treat, prevent or manage chronic lymphocytic leukemia. In some embodiments, the methods comprise the step of administering to the subject a compound, antibody, or antibody-drug conjugate provided herein in combination with a second active agent in amounts effective to treat, prevent or manage chronic lymphocytic leukemia.

[0253] In some embodiments, the methods provided herein encompass treating, preventing or managing myelodysplastic syndrome (MDS) in a subject. MDS is characterized by immatureblood cells in the bone marrow that do not mature and may progress to AML. In some embodiments, the subject has very low, low, intermediate, high, or very high risk MDS according to the International Prognostic Scoring System (IPSS-R). The methods comprise the step of administering to the subject an amount of a compound, antibody, or antibody-drug conjugate provided herein effective to treat, prevent or manage MDS. In some embodiments, the methods comprise the step of administering to the subject a compound, antibody, or antibodydrug conjugate provided herein in combination with a second active agent in amounts effective to treat, prevent or manage MDS.

[0254] In certain embodiments, provided herein are methods of treating, preventing, and / or managing disease in patients with impaired renal function. In certain embodiments, provided herein are method of treating, preventing, and / or managing cancer in patients with impaired renal function. In certain embodiments, provided herein are methods of providing appropriate dose adjustments for patients with impaired renal function due to, but not limited to, disease, aging, or other patient factors.

[0255] In certain embodiments, provided herein are methods of treating, preventing, and / or managing lymphoma, including non-Hodgkin's lymphoma. In some embodiments, provided herein are methods for the treatment or management of non-Hodgkin's lymphoma (NHL), including but not limited to, diffuse large B-cell lymphoma (DLBCL), using prognostic factors.

[0256] In certain embodiments, provided herein are methods of treating, preventing, and / or managing multiple myeloma, including relapsed / refractory multiple myeloma in patients with impaired renal function or a symptom thereof, comprising administering a therapeutically effective amount of a compound, antibody, or antibody-drug conjugate provided herein to a patient having relapsed / refractory multiple myeloma with impaired renal function.

[0257] In certain embodiments, the patient to be treated with one of the methods provided herein has not been treated with anticancer therapy prior to the administration of a compound, antibody, or antibody-drug conjugate provided herein. In certain embodiments, the patient to be treated with one of the methods provided herein has been treated with anticancer therapy prior to the administration of a compound, antibody, or antibody-drug conjugate provided herein. In certain embodiments, the patient to be treated with one of the methods provided herein has developed drug resistance to the anticancer therapy.

[0258] The methods provided herein encompass treating a patient regardless of patient's age, although some diseases or disorders are more common in certain age groups.B. Routes of Administration and Carriers

[0259] Provided herein are compositions (e.g., pharmaceutical compositions) comprising a compound, antibody, or antibody-drug conjugate provided herein and one or more pharmaceutically acceptable carriers.

[0260] In various embodiments, a compound, antibody, or antibody-drug conjugate provided herein may be administered in vivo by various routes, including, but not limited to, oral, intraarterial, parenteral (including intravenous and subcutaneous), intranasal, intramuscular, intracardiac, intraventricular, intratracheal, buccal, rectal, intraperitoneal, intradermal, topical, transdermal, and intrathecal, or otherwise by implantation or inhalation. The subject compositions may be formulated into preparations, such as liquid formulations or formulations suitable for injections, inhalations, and the like. Alternatively, in some embodiments, the composition may be provided as a lyophilized powder that may be reconstituted upon addition of an appropriate liquid or carrier, for example, sterile water. The appropriate formulation and route of administration may be selected according to the intended application.

[0261] In various embodiments, compositions comprising a compound, antibody, or antibodydrug conjugate provided herein are provided in formulations with a wide variety of pharmaceutically acceptable carriers (see, e.g., Gennaro, Remington: The Science and Practice of Pharmacy with Facts and Comparisons: Drugfacts Plus, 20th ed. (2003); Ansel et al., Pharmaceutical Dosage Forms and Drug Delivery Systems, 7th ed., Lippencott Williams and Wilkins (2004); Kibbe et al., Handbook of Pharmaceutical Excipients, 3rd ed., Pharmaceutical Press (2000)). Various pharmaceutically acceptable carriers, which include vehicles, adjuvants, and diluents, are available. Moreover, various pharmaceutically acceptable auxiliary substances, such as pH adjusting and buffering agents, tonicity adjusting agents, stabilizers, wetting agents and the like, are also available.IX. EXAMPLESExample 1: Generation of CD33 Antibodies

[0262] Screening and discovery of fully human immunoglobulin G (IgG) antibodies against CD33 was performed by utilizing a yeast display platform. Recombinant human CD33 extracellular domain (ECD), which includes the V and C2 domains, was used as bait in an initial screen to isolate binders from naive human libraries of fully human antibodies expressed by yeast cells. This initial attempt failed to identify antibodies that recognized the CD33 C2 region, as determined using an Octet® biolayer interferometry (BLI) detection system. A modified screening campaign of the yeast display platform was undertaken that integrated truncated human and cynomolgus CD33 ECDs expressing the C2 domain but lacking the V domain(CD33-C2) and were allowed to form either human / human homodimers or human / cynomolgus heterodimers. Following first-round selection with the full-length human CD33 ECD of a >109naive human antibody library and a second-round polyspecificity reagent / Siglec6 / 8 counterselection, remaining antibodies were sub-binned with either full-length human CD33, full-length cyno CD33, human CD33-C2 or human / cyno CD33-C2. 78 unique antibodies were identified and of these, 72 avidly-bound the full-length human CD33 ECD with 58 recognizing the V domain and 14 binding to truncated human CD33-C2. None of the C2 domain binders cross-reacted in avid assay format with the cynomolgus form of the CD33 ECD while 52 / 58 V domain binders exhibited cynomolgus CD33 affinities. These results underscore the relative difficulty identifying CD33 C2 selective antibodies from this library, particularly with respect to cynomolgus CD33 cross-reactivity, a highly desirable feature that enables pre-clinical toxicology and PK / PD studies in monkeys.

[0263] Of the 14 that recognized human CD33-C2, 10 CD33-C2 antibodies were selected as parents for subsequent affinity maturation. 8 of 10 of these parental antibodies failed after affinity maturation to exhibit improved binding to human CD33 natively-expressed by Molml3 AML cells and showed poor affinity for Hek293 cells engineered to express cynomolgus CD33.

[0264] Of the 2 maturation-amenable lineages, the first was subjected to a total of 3 rounds of affinity maturation; however, recognition of human CD33 expressed by Molml3 and MV-411 AML cells remained low and could not be progressed without causing Siglec-6 off-target reactivity, as assessed by Octet® BLI. Since CD33 -related Siglec proteins can be detected in healthy tissue (e.g. Siglec-6 in placenta, colon; Siglec-8 in brain, lung, intestine, liver), it is important to avoid potential toxicities resulting from inadvertent antibody cross-reactivity to these proteins. The second maturation-amenable lineage was advanced through 4 total rounds of maturation, leading to the identification of variations that improved Molml3, MV-411 and cynomolgus CD33 (Hek293 cynomolgus CD33) cell-binding profiles.Example 2: Octet® biolayer interferometry (BLI) Analysis of Affinity Matured Antibodies

[0265] Binding kinetics of antibody CD33-Abl and its progeny antibodies was assessed by Octet® BLI.

[0266] The binding data for the antibodies is shown in Table 1 below.Table 1Example 3: Novel C2 antibodies exhibited selective affinity for CD33+ cells

[0267] CD33-Abl and its progeny antibodies described above were tested for selective affinity for CD33+ cells compared to vadastuximab (VADA) or isotype control.

[0268] HEK293 cells were engineered to express the full-length coding sequence of cynomolgus CD33 or a truncated form of human CD33 lacking the V-domain by transfection. Serially diluted antibodies were added to cells, followed by washing and additional incubation with a secondary anti-human IgG detection antibody. Levels of antibody binding were analyzed by determining the mean fluorescence intensity (MFI) by flow cytometry.

[0269] Results in HEK293 cells engineered to express the full-length coding sequence of cynomolgus CD33 are shown in FIG. 2, third column. Results in HEK293 cells engineered to express a truncated form of human CD33 lacking the V-domain are shown in FIG. 2, second column. CD33-Abl and its progeny antibodies from affinity -maturation cycles 2-4 exhibited affinity for CD33+ HEK293 cells expressing full length cynomolgus CD33 or human C2 domain. CD33-Abl and its progeny antibodies did not exhibit detectable affinity for HEK293 cells transduced with full length Siglec-6. See FIG. 2, fourth column.

[0270] The antibodies were also tested for binding to CD33+ AML cancer cell lines (Molml3 and MV411), and CD33-negative Pfeiffer cells (FIG. 3). CD33-Abl and its affinity matured progeny antibodies exhibited selective affinity for the CD33+ AML cancer cells lines relative to the CD33- cell line.Example 4: Antibody Mediated Internalization in CD33+ cells

[0271] Antibody drug conjugates (ADCs) comprise an antibody and a molecular warhead for targeted cytotoxicity. The ability of the antibody to mediate internalization is an important property for ADC potency. Antibody CD33-Abl progeny deriving from affinity -maturation cycles 2 and 4 were compared with VADA for relative cell internalization kinetics.

[0272] CD33+ MOLM-13 cells, CD33+ MV-411 cells, or CD33-negative Pfeiffer cells were incubated with various concentrations (32 pM-10 nM) of antibody CD33-M or VADA labeled with acid-sensitive fluorescent Fab fragments that become fluorescent in the endosome. Cells were stained with the Fab-labeled antibody on ice and, after washing off unbound antibody, incubated at 37°C for four hours. Cells were then analyzed by flow cytometry, recording the geometric MFI (gMFI) at each concentration of antibody.

[0273] The results (FIG. 4) demonstrated that the progeny of antibody CD33-Abl showed greater internalization in CD33+ cells than VADA, which showed little to no internalization.X. TABLE OF CERTAIN SEQUENCES

[0274] The following table provides a listing of certain sequences referenced herein.

Claims

What is Claimed is:

1. An isolated antibody or antigen-binding portion thereof that specifically binds to CD33, wherein the antibody or antigen-binding portion thereof comprises a heavy chain complementarity determining region 1 (HCDR1) comprising an amino acid sequence selected from SEQ ID NOs: 36-42 and 72-75; a heavy chain complementarity determining region 2 (HCDR2) comprising an amino acid sequence selected from SEQ ID NOs: 43-53 and 76-80; a heavy chain complementarity determining region 3 (HCDR3) comprising the amino acid sequence of SEQ ID NO: 54 or 55; a light chain complementarity determining region 1 (LCDR1) comprising an amino acid sequence selected from SEQ ID NOs: 56-61; a light chain complementarity determining region 2 (LCDR2) comprising an amino acid sequence selected from SEQ ID NOs: 62-69; and a light chain complementarity determining region 3 (LCDR3) comprising the amino acid sequence of SEQ ID NO: 70 or 71.

2. The isolated antibody or antigen-binding portion thereof of claim 1, wherein the antibody or antigen-binding portion thereof comprises: a) HCDR1 comprising the amino acid sequence of SEQ ID NO: 37, HCDR2 comprising the amino acid sequence of SEQ ID NO: 44, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 65, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; b) HCDR1 comprising the amino acid sequence of SEQ ID NO: 38, HCDR2 comprising the amino acid sequence of SEQ ID NO: 43, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 65, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; c) HCDR1 comprising the amino acid sequence of SEQ ID NO: 36, HCDR2 comprising the amino acid sequence of SEQ ID NO: 51, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 63, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; d) HCDR1 comprising the amino acid sequence of SEQ ID NO: 38, HCDR2 comprising the amino acid sequence of SEQ ID NO: 51, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 63, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71;e) HCDR1 comprising the amino acid sequence of SEQ ID NO: 40, HCDR2 comprising the amino acid sequence of SEQ ID NO: 53, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 65, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; f) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 51, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 63, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; g) HCDR1 comprising the amino acid sequence of SEQ ID NO: 40, HCDR2 comprising the amino acid sequence of SEQ ID NO: 53, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 66, LCDR3 comprising the amino acid sequence of SEQ ID NO: 70; h) HCDR1 comprising the amino acid sequence of SEQ ID NO: 38, HCDR2 comprising the amino acid sequence of SEQ ID NO: 43, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 61, LCDR2 comprising the amino acid sequence of SEQ ID NO: 67, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; i) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 52, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 62, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; j) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 51, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 64, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; k) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 51, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 56, LCDR2 comprising the amino acid sequence of SEQ ID NO: 69, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71;l) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 46, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; m) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 47, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 56, LCDR2 comprising the amino acid sequence of SEQ ID NO: 63, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; n) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 51, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 57, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; o) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 45, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; p) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 49, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; q) HCDR1 comprising the amino acid sequence of SEQ ID NO: 38, HCDR2 comprising the amino acid sequence of SEQ ID NO: 43, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; r) HCDR1 comprising the amino acid sequence of SEQ ID NO: 41, HCDR2 comprising the amino acid sequence of SEQ ID NO: 43, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71;s) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 45, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; t) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 47, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 59, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; u) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 48, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; v) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 50, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; w) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 51, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; x) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 51, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; y) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 47, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; orz) HCDR1 comprising the amino acid sequence of SEQ ID NO: 42, HCDR2 comprising the amino acid sequence of SEQ ID NO: 46, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

3. The isolated antibody or antigen-binding portion thereof of claim 1, wherein the antibody or antigen-binding portion thereof comprises: a) HCDR1 comprising the amino acid sequence of SEQ ID NO: 74, HCDR2 comprising the amino acid sequence of SEQ ID NO: 78, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 65, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; b) HCDR1 comprising the amino acid sequence of SEQ ID NO: 72, HCDR2 comprising the amino acid sequence of SEQ ID NO: 76, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 65, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; c) HCDR1 comprising the amino acid sequence of SEQ ID NO: 73, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 63, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; d) HCDR1 comprising the amino acid sequence of SEQ ID NO: 74, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 63, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; e) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 80, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 65, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; f) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ IDNO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 63, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; g) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 80, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 58, LCDR2 comprising the amino acid sequence of SEQ ID NO: 66, LCDR3 comprising the amino acid sequence of SEQ ID NO: 70; h) HCDR1 comprising the amino acid sequence of SEQ ID NO: 72, HCDR2 comprising the amino acid sequence of SEQ ID NO: 76, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 61, LCDR2 comprising the amino acid sequence of SEQ ID NO: 67, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; i) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 79, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 62, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; j) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 64, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; k) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 56, LCDR2 comprising the amino acid sequence of SEQ ID NO: 69, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; l) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; m) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ IDNO: 56, LCDR2 comprising the amino acid sequence of SEQ ID NO: 63, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; n) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 57, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; o) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; p) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; q) HCDR1 comprising the amino acid sequence of SEQ ID NO: 72, HCDR2 comprising the amino acid sequence of SEQ ID NO: 76, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; r) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 76, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; s) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; t) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ IDNO: 59, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; u) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; v) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; w) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; x) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 54, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; y) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71; or z) HCDR1 comprising the amino acid sequence of SEQ ID NO: 75, HCDR2 comprising the amino acid sequence of SEQ ID NO: 77, HCDR3 comprising the amino acid sequence of SEQ ID NO: 55, LCDR1 comprising the amino acid sequence of SEQ ID NO: 60, LCDR2 comprising the amino acid sequence of SEQ ID NO: 68, LCDR3 comprising the amino acid sequence of SEQ ID NO: 71.

4. The isolated antibody or antigen-binding portion thereof of any one of claims 1-3, wherein the antibody or antigen-binding portion thereof comprises a heavy chain variable region (VH) comprising an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%,96%, 97%, 98%, or 99% identical to the amino acid sequence selected from SEQ ID NOs: 1- 20, and a light chain variable region (VL) comprising an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence selected from SEQ ID NOs: 21-35; optionally wherein the glutamic acid (E) at the N-terminus of SEQ ID NOs: 1-20 may be replaced with a pyroglutamic acid (pE).

5. The isolated antibody or antigen-binding portion thereof of any one of claims 1-3, wherein the antibody or antigen-binding portion thereof comprises a heavy chain variable region (VH) comprising an amino acid sequence selected from SEQ ID NOs: 1-20, and a light chain variable region (VL) comprising an amino acid sequence selected from SEQ ID NOs: 21-35; optionally wherein the glutamic acid (E) at the N-terminus of SEQ ID NOs: 1-20 may be replaced with a pyroglutamic acid (pE).

6. The isolated antibody or antigen-binding portion thereof of any one of claims 1-3, wherein the antibody or antigen-binding portion thereof comprises a heavy chain variable region (VH) and a light chain variable region (VL), wherein the antibody or antigen-binding portion thereof comprises: a) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 5 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 35; b) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 4 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 27; c) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 19 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 26; d) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 20 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 26; e) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 6 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 27;f) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 15 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 26; g) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 6 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 28; h) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 4 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 34; i) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 17 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 30; j) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 14 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 31; k) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 14 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 24; l) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 9 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 32; m) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 10 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 23; n) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 14 and aVL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 25; o) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 1 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 32; p) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 2 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 32; q) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 3 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 32; r) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 7 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 32; s) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 8 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 21; t) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 11 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 29; u) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 12 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 32; v) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 13 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 32;w) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 14 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 22; x) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 16 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 32; y) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 18 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 33; z) a VH comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 9 and a VL comprising an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 32; optionally wherein the glutamic acid (E) at the N-terminus of SEQ ID NOs: 1-20 may be replaced with a pyroglutamic acid (pE).

7. The isolated antibody or antigen-binding portion thereof of any one of claims 1-3, wherein the antibody or antigen-binding portion thereof comprises a heavy chain variable region (VH) and a light chain variable region (VL), wherein the antibody or antigen-binding portion thereof comprises: a) a VH comprising the amino acid sequence of SEQ ID NO: 5 and a VL comprising the amino acid sequence of SEQ ID NO: 35; b) a VH comprising the amino acid sequence of SEQ ID NO: 4 and a VL comprising the amino acid sequence of SEQ ID NO: 27; c) a VH comprising the amino acid sequence of SEQ ID NO: 19 and a VL comprising the amino acid sequence of SEQ ID NO: 26; d) a VH comprising the amino acid sequence of SEQ ID NO: 20 and a VL comprising the amino acid sequence of SEQ ID NO: 26; e) a VH comprising the amino acid sequence of SEQ ID NO: 6 and a VL comprising the amino acid sequence of SEQ ID NO: 27; f) a VH comprising the amino acid sequence of SEQ ID NO: 15 and a VL comprising the amino acid sequence of SEQ ID NO: 26;g) a VH comprising the amino acid sequence of SEQ ID NO: 6 and a VL comprising the amino acid sequence of SEQ ID NO: 28; h) a VH comprising the amino acid sequence of SEQ ID NO: 4 and a VL comprising the amino acid sequence of SEQ ID NO: 34; i) a VH comprising the amino acid sequence of SEQ ID NO: 17 and a VL comprising the amino acid sequence of SEQ ID NO: 30; j) a VH comprising the amino acid sequence of SEQ ID NO: 14 and a VL comprising the amino acid sequence of SEQ ID NO: 31; k) a VH comprising the amino acid sequence of SEQ ID NO: 14 and a VL comprising the amino acid sequence of SEQ ID NO: 24; l) a VH comprising the amino acid sequence of SEQ ID NO: 9 and a VL comprising the amino acid sequence of SEQ ID NO: 32; m) a VH comprising the amino acid sequence of SEQ ID NO: 10 and a VL comprising the amino acid sequence of SEQ ID NO: 23; n) a VH comprising the amino acid sequence of SEQ ID NO: 14 and a VL comprising the amino acid sequence of SEQ ID NO: 25; o) a VH comprising the amino acid sequence of SEQ ID NO: 1 and a VL comprising the amino acid sequence of SEQ ID NO: 32; p) a VH comprising the amino acid sequence of SEQ ID NO: 2 and a VL comprising the amino acid sequence of SEQ ID NO: 32; q) a VH comprising the amino acid sequence of SEQ ID NO: 3 and a VL comprising the amino acid sequence of SEQ ID NO: 32; r) a VH comprising the amino acid sequence of SEQ ID NO: 7 and a VL comprising the amino acid sequence of SEQ ID NO: 32; s) a VH comprising the amino acid sequence of SEQ ID NO: 8 and a VL comprising the amino acid sequence of SEQ ID NO: 21; t) a VH comprising the amino acid sequence of SEQ ID NO: 11 and a VL comprising the amino acid sequence of SEQ ID NO: 29; u) a VH comprising the amino acid sequence of SEQ ID NO: 12 and a VL comprising the amino acid sequence of SEQ ID NO: 32; v) a VH comprising the amino acid sequence of SEQ ID NO: 13 and a VL comprising the amino acid sequence of SEQ ID NO: 32; w) a VH comprising the amino acid sequence of SEQ ID NO: 14 and a VL comprising the amino acid sequence of SEQ ID NO: 22;x) a VH comprising the amino acid sequence of SEQ ID NO: 16 and a VL comprising the amino acid sequence of SEQ ID NO: 32; y) a VH comprising the amino acid sequence of SEQ ID NO: 18 and a VL comprising the amino acid sequence of SEQ ID NO: 33; or z) a VH comprising the amino acid sequence of SEQ ID NO: 9 and a VL comprising the amino acid sequence of SEQ ID NO: 32; optionally wherein the glutamic acid (E) at the N-terminus of SEQ ID NOs: 1-20 may be replaced with a pyroglutamic acid (pE).

8. The isolated antibody or antigen-binding portion thereof of any one of claims 1-7, wherein the antibody or antigen-binding portion thereof is a monoclonal antibody.

9. The isolated antibody or antigen-binding portion thereof of any one of claims 1-8, wherein the antibody or antigen-binding portion thereof is a human antibody, chimeric antibody, or a humanized antibody.

10. The isolated antibody or antigen-binding portion thereof of any one of claims 1-9, wherein the antibody or antigen-binding portion thereof is an IgG antibody.

11. The isolated antibody or antigen-binding portion thereof of claim 10, wherein the antibody is an IgG antibody lacking a C-terminal lysine in the heavy chain constant region.

12. The isolated antibody or antigen-binding portion thereof of claim 10 or claim 11, wherein the antibody is an IgGl antibody, an IgG2 antibody, an IgG3 antibody, or an IgG4 antibody.

13. The isolated antibody or antigen-binding portion thereof of any one of claims 1-12, wherein the antibody is a full-length antibody.

14. The isolated antibody or antigen-binding portion thereof of any one of claims 1-12, wherein the antibody or antigen-binding portion thereof is an antibody fragment selected from an Fv, single-chain Fv (scFv), Fab, Fab’, or (Fab’)2.

15. The isolated antibody or antigen-binding portion thereof of any one of claims 1-14, wherein the antibody or antigen-binding portion thereof binds human CD33.

16. The isolated antibody or antigen-binding portion thereof of claim 15, wherein human CD33 comprises the amino acid sequence of SEQ ID NO: 97 or SEQ ID NO: 99.

17. The isolated antibody or antigen-binding portion thereof of any one of claims 1-16, wherein the antibody or antigen-binding portion thereof binds the monomeric form of human CD33 and / or the dimeric form of human CD33.

18. The isolated antibody or antigen-binding portion thereof of any one of claims 1-17, wherein the antibody or antigen-binding portion thereof binds cynomolgus monkey CD33.

19. The antibody or antigen-binding portion thereof of claim 18, wherein cynomolgus monkey CD33 comprises the amino acid sequence of SEQ ID NO: 98.

20. The isolated antibody or antigen-binding portion thereof of claim 18 or claim 19, wherein the antibody or antigen-binding portion thereof binds the monomeric form of cynomolgus monkey CD33 and / or the dimeric form of cynomolgus monkey CD33.

21. The isolated antibody or antigen-binding portion thereof of any one of claims 1-20, wherein the antibody or antigen-binding portion thereof binds to human CD33 with an affinity (KD) of less than 1.5 nM.

22. The isolated antibody or antigen-binding portion thereof of any one of claims 1-21, wherein the antibody or antigen-binding portion thereof binds to cynomolgus monkey CD33 with an affinity (KD) of less than 10 nM.

23. The isolated antibody or antigen-binding portion thereof of claim 21 or claim 22, wherein affinity is determined using biolayer interferometry.

24. The isolated antibody or antigen-binding portion thereof of any one of claims 1-23, wherein the antibody or antigen-binding portion thereof does not bind to human Siglec 6 or human Siglec 8.

25. The isolated antibody or antigen-binding portion thereof of any one of claims 1-24, wherein the antibody or antigen-binding portion thereof internalizes after binding to CD33+ cells.

26. The isolated antibody or antigen-binding portion thereof of any one of claims 1-25, wherein the antibody or antigen-binding portion thereof is a bispecific antibody.

27. The isolated antibody of antigen-binding portion thereof of claim 26, wherein the bispecific antibody binds CD33 and a second antigen.

28. The isolated antibody or antigen-binding portion thereof of claim 27, wherein the second antigen is expressed on the surface of T cells or NK cells.

29. The isolated antibody or antigen-binding portion thereof of claim 27 or claim 28, wherein the second antigen is selected from CD3, CD16, CD16A, NKG2C, and NKG2D.

30. An antibody-drug conjugate comprising the antibody or antigen-binding portion thereof of any one of claims 1-29 and a cytotoxic agent.

31. A pharmaceutical composition comprising the isolated antibody or antigen-binding portion thereof of any one of claims 1-29 or the antibody-drug conjugate of claim 30 and a pharmaceutically acceptable carrier.

32. An isolated nucleic acid encoding the antibody or antigen-binding portion thereof of any one of claims 1-29.

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

34. A host cell comprising the nucleic acid of claim 32 or the vector of claim 33.

35. A host cell that expresses the antibody or antigen-binding portion thereof of any one of claims 1-29.

36. A method for making an anti-CD33 antibody or antigen-binding portion thereof, comprising culturing the host cell of claim 34 or 35 under conditions suitable for expression of the antibody or antigen-binding portion thereof.

37. The method of claim 36, further comprising recovering the antibody or antigen-binding portion thereof produced by the host cell.

38. A method of treating cancer in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of the isolated antibody or antigen-binding portion thereof of any one of claims 1-29, the pharmaceutical composition of claim 31, or the antibody-drug conjugate of claim 30.

39. The method of claim 38, wherein the cancer is leukemia.

40. The method of claim 39, wherein the leukemia is chronic lymphocytic leukemia, chronic myelocytic leukemia, acute lymphoblastic leukemia, or acute myeloid leukemia.

41. The method of any one of claims 38-40, wherein the subject is a human.

42. Use of the isolated antibody or antigen-binding portion thereof of any one of claims 1-29, the pharmaceutical composition of claim 31, or the antibody-drug conjugate of claim 30 for the preparation of a medicament for treating cancer in a subject in need thereof.

43. The isolated antibody or antigen-binding portion thereof of any one of claims 1-29, the pharmaceutical composition of claim 31, or the antibody-drug conjugate of claim 30 for use in treating cancer in a subject in need thereof.

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