An antibody drug conjugate of the formula Ab-(L- m) n or a pharmaceutically acceptable salt thereof; wherein Ab is an antibody or antigen binding fragment thereof that comprises (i) a heavy chain variable region that comprises (a) a HCDR1 (CDR-Complementarity Determining Region) of SEQ ID NO: 76, (b) a HCDR2 of SEQ ID NO: 77, (c) a HCDR3 of SEQ ID NO: 78; and a light chain variable region that comprises: (d) a LCDR1 of SEQ ID NO: 85, (e) a LCDR2 of SEQ ID NO: 86, and (f) a LCDR3 of SEQ ID NO: 87; (ii) a heavy chain variable region that comprises (a) a HCDR1 of SEQ ID NO: 22, (b) a HCDR2 of SEQ ID NO: 23, (c) a HCDR3 of SEQ ID NO: 24; and a light chain variable region that comprises: (d) a LCDR1 of SEQ ID NO: 31, (e) a LCDR2 of SEQ ID NO: 32, and (f) a LCDR3 of SEQ ID NO: 33; (iii) a heavy chain variable region that comprises (a) a HCDR1 of SEQ ID NO: 130, (b) a HCDR2 of SEQ ID NO: 131, (c) a HCDR3 of SEQ ID NO: 132; and a light chain variable region that comprises: (d) a LCDR1 of SEQ ID NO: 139, (e) a LCDR2 of SEQ ID NO: 140, and (f) a LCDR3 of SEQ ID NO: 141; (iv) a heavy chain variable region that comprises: (a) a HCDR1 of SEQ ID NO: 58, (b) a HCDR2 of SEQ ID NO: 59, (c) a HCDR3 of SEQ ID NO: 60; and a light chain variable region that comprises: (d) a LCDR1 of SEQ ID NO: 67, (e) a LCDR2 of SEQ ID NO: 68, and (f) a LCDR3 of SEQ ID NO: 69; (v) a heavy chain variable region that comprises: (a) a HCDR1 of SEQ ID NO: 40, (b) a HCDR2 of SEQ ID NO: 41, (c) a HCDR3 of SEQ ID NO: 42; and a light chain variable region that comprises: (d) a LCDR1 of SEQ ID NO: 49, (e) a LCDR2 of SEQ ID NO: 50, and (f) a LCDR3 of SEQ ID NO: 51; (vi) a heavy chain variable region that comprises: (a) a HCDR1 of SEQ ID NO: 94, (b) a HCDR2 of SEQ ID NO: 95, (c) a HCDR3 of SEQ ID NO: 96; and a light chain variable region that comprises: (d) a LCDR1 of SEQ ID NO: 103, (d) a LCDR2 of SEQ ID NO: 104, and (f) a LCDR3 of SEQ ID NO: 105; (vii) a heavy chain variable region that comprises: (a) a HCDR1 of SEQ ID NO: 112, (b) a HCDR2 of SEQ ID NO: 113, (c) a HCDR3 of SEQ ID NO: 114; and a light chain variable region that comprises: (d) a LCDR1 of SEQ ID NO: 121, (e) a LCDR2 of SEQ ID NO: 122, and (f) a LCDR3 of SEQ ID NO: 123; or (viii) a heavy chain variable region that comprises: (a) a HCDR1 of SEQ ID NO: 3, (b) a HCDR2 of SEQ ID NO: 4, (c) a HCDR3 of SEQ ID NO: 5; and a light chain variable region that comprises: (d) a LCDR1 of SEQ ID NO: 12, (e) a LCDR2 of SEQ ID NO: 13, and (f) a LCDR3 of SEQ ID NO: 14; L is a linker; D is a maytansinoid; m is an integer from 1 to 8; and n is an integer from 1 to 10. (ii) a heavy chain variable region that comprises (a) a HCDR1 of SEQ ID NO: 22, (b) a HCDR2 of SEQ ID NO: 23, (c) a HCDR3 of SEQ ID NO: 24; and a light chain variable region that comprises: (d) a LCDR1 of SEQ ID NO: 31, (e) a LCDR2 of SEQ ID NO: 32, and (f) a LCDR3 of SEQ ID NO: 33; (iii) a heavy chain variable region that comprises (a) a HCDR1 of SEQ ID NO: 130, (b) a HCDR2 of SEQ ID NO: 131, (c) a HCDR3 of SEQ ID NO: 132; and a light chain variable region that comprises: (d) a LCDR1 of SEQ ID NO: 139, (e) a LCDR2 of SEQ ID NO: 140, and (f) a LCDR3 of SEQ ID NO: 141; (iv) a heavy chain variable region that comprises: (a) a HCDR1 of SEQ ID NO: 58, (b) a HCDR2 of SEQ ID NO: 59, (c) a HCDR3 of SEQ ID NO: 60; and a light chain variable region that comprises: (d) a LCDR1 of SEQ ID NO: 67, (e) a LCDR2 of SEQ ID NO: 68, and (f) a LCDR3 of SEQ ID NO: 69; (v) a heavy chain variable region that comprises: (a) a HCDR1 of SEQ ID NO: 40, (b) a HCDR2 of SEQ ID NO: 41, (c) a HCDR3 of SEQ ID NO: 42; and a light chain variable region that comprises: (d) a LCDR1 of SEQ ID NO: 49, (e) a LCDR2 of SEQ ID NO: 50, and (f) a LCDR3 of SEQ ID NO: 51; (vi) a heavy chain variable region that comprises: (a) a HCDR1 of SEQ ID NO: 94, (b) a HCDR2 of SEQ ID NO: 95, (c) a HCDR3 of SEQ ID NO: 96; and a light chain variable region that comprises: (d) a LCDR1 of SEQ ID NO: 103, (d) a LCDR2 of SEQ ID NO: 104, and (f) a LCDR3 of SEQ ID NO: 105; (vii) a heavy chain variable region that comprises: (a) a HCDR1 of SEQ ID NO: 112, (b) a HCDR2 of SEQ ID NO: 113, (c) a HCDR3 of SEQ ID NO: 114; and a light chain variable region that comprises: (d) a LCDR1 of SEQ ID NO: 121, (e) a LCDR2 of SEQ ID NO: 122, and (f) a LCDR3 of SEQ ID NO: 123; or (viii) a heavy chain variable region that comprises: (a) a HCDR1 of SEQ ID NO: 3, (b) a HCDR2 of SEQ ID NO: 4, (c) a HCDR3 of SEQ ID NO: 5; and a light chain variable region that comprises: (d) a LCDR1 of SEQ ID NO: 12, (e) a LCDR2 of SEQ ID NO: 13, and (f) a LCDR3 of SEQ ID NO: 14;