SW-163D is a cyclodepsipeptide antibiotic that is isolated from Streptomyces sp. SW-163D also exhibits antitumour activity. PF06888667 is a potent, stable, and efficacious ADC that consists of the bis-intercalator, SW-163D, conjugated via an N-acetyl-lysine-valine-citrulline-p-aminobenzyl alcohol-N,N-dimethylethylenediamine (AcLysValCitPABC-DMAE) linker to an engineered variant of the anti-Her2 mAb, trastuzumab, catalyzed by transglutaminase[1].