Tesirine (SG3249) is an antibody-drug conjugate (ADC) pyrrolobenzodiazepine (PBD) dimer payload. Tesirine combines potent antitumor activity with desirable physicochemical properties such as favorable hydrophobicity and improved conjugation characteristics. SG3199 (HY-101161) is the released warhead component of the ADC payload Tesirine. SG3199 retains picomolar activity in a panel of cancer cell lines. PBD dimers are highly efficient DNA minor groove cross-linking agents with potent cytotoxicity.