Cantuzumab mertansine (HUC242-DM1, SB-408075) is an anti-MUC1 sialylated carbohydrate, tumour-associated (CA242, cancer antigen 242), humanized monoclonal antibody conjugated to maytansinoid DM1 ([N2’-deacetyl-N2’-(3-mercapto-1-oxopropyl)-maytansine]) via a reductible SPP linker [N-succinimidyl 4-(2-pyridyldithio)pentanoate].