Discovery of Potent and Selective Antibody–Drug Conjugates with Eg5 Inhibitors through Linker and Payload Optimization

Abstract

Targeted antimitotic agents are a promising class of anticancer therapies. Herein, we describe the development of a potent and selective antimitotic Eg5 inhibitor based antibody-drug conjugate (ADC). Preliminary studies were performed using proprietary Eg5 inhibitors which were conjugated onto a HER2-targeting antibody using maleimido caproyl valine-citrulline para-amino benzocarbamate, or MC-VC-PABC cleavable linker. However, the resulting ADCs lacked antigen-specificity in vivo, probably from premature release of the payload. Second-generation ADCs were then developed, using noncleavable linkers, and the resulting conjugates (<b>ADC-4</b> and <b>ADC-10</b>) led to in vivo efficacy in an HER-2 expressing (SK-OV-3ip) mouse xenograft model while <b>ADC-11</b> led to in vivo efficacy in an anti-c-KIT (NCI-H526) mouse xenograft model in a target-dependent manner.