The present disclosure provides antibody-drug conjugates (ADCs) comprising acytotoxic or cytostatic agent linked toan anti-EGFR antibody by way of a linker, compositions comprising the ADCs,methods of making the ADCs, and methods of treatinga cancer comprising administering the ADCs to a subject having cancer. Thepresent disclosure provides ADCs that specifically bindEGFR, and in particular human EGFR (hEGFR). The anti-EGFR Ab described hereincomprises a S239C mutation in a heavy chainconstant region, wherein the numbering is in accordance with Kabat. In certainembodiments, the heavy chain constant region of theanti-EGFR antibody either lacks a C-terminal lysine or comprises an amino acidother than lysine at a C-terminus of the heavy chainconstant region.
