From the 1960s when monomeric pyrrolobenzodiazepines (PBDs) such as anthramycin were isolated and characterized, to the dramatic increase of potency induced by dimerization in the 2000s, PBD dimers have evolved as one of the leading classes of antibody drug conjugate (ADC) payloads. Currently, 17 ADCs are in clinical trials involving PBD-dimers — second only to auristatins (23 ADCs), and more than those with maytansines (16 ADCs). Four different PBD-dimer ADC payloads are in clinical trials: Talirine (SGD-1910) from Seattle Genetics;…