A DNA-Interacting Payload Designed to Eliminate Cross-Linking Improves the Therapeutic Index of Antibody–Drug Conjugates (ADCs)

Abstract

Tumor-selective delivery of cytotoxic agents in the form of antibody-drug conjugates (ADCs) is now a clinically validated approach for cancer treatment. In an attempt to improve the clinical success rate of ADCs, emphasis has been recently placed on the use of DNA-cross-linking pyrrolobenzodiazepine compounds as the payload. Despite promising early clinical results with this class of ADCs, doses achievable have been low due to systemic toxicity. Here, we describe the development of a new class of potent DNA-interacting agents wherein changing the mechanism of action from a cross-linker to a DNA alkylator improves the tolerability of the ADC. ADCs containing the DNA alkylator displayed similar <i>in vitro</i> potency, but improved bystander killing and <i>in vivo</i> efficacy, compared with those of the cross-linker. Thus, the improved <i>in vivo</i> tolerability and antitumor activity achieved in rodent models with ADCs of the novel DNA alkylator could provide an efficacious, yet safer option for cancer treatment. <i>Mol Cancer Ther; 17(3); 650-60. ©2018 AACR</i>.