ERBB2 and neoplasm: The PBD monoamide satisfies the criteria set forth—reduced potency, DNA monoalkylation, active as an ADC (DHES0815A) in the desired dose range for optimal PK and efficacy, efficacy in T-DM1 refractory models and in HER2-low mouse tumor models, and an acceptable safety profile when tested in non-human primate safety studies.