Monomethyl auristatin F (MMAF) sodium is a highly potent tubulin inhibitor and an antineoplastic agent used as a warhead in ADCs (antibody-drug conjugates) such as vorsetuzumab mafodotin and SGN-CD19A. MMAF plus its attachment structure to the antibody are referred to as mafodotin in the International Nonproprietary Names for MMAF-antibody-conjugates. Since the N-terminal amino group of MMAF only has one methyl substituent rather than two, as it does in auristatin F itself, it is actually desmethyl-auristatin F.