Abstract 4333: Self-stabilizing ADCs: antibody-drug conjugates prepared with maleimido drug-linkers that catalyze their own thiosuccinimide ring hydrolysis.

Abstract

Abstract Many antibody-drug conjugates (ADCs) currently in clinical trials employ maleimide-containing drug-linkers which are conjugated to antibody cysteine residues to form thiosuccinimide linkages. It is now known that these thiosuccinimide linkages can undergo two competing reactions while in plasma: elimination of the maleimide resulting in undesirable loss of drug from the ADC, and hydrolysis of the thiosuccinimide ring resulting in a succinic acid derivative which cannot undergo elimination. Thus, thiosuccinimide ring hydrolysis is a reaction which stabilizes the chemical linkage of the drug to the antibody. We have engineered a new class of drug-linkers which incorporate a basic amino group adjacent to the maleimide, providing intramolecular base catalysis of the ring hydrolysis. This basic group induces the thiosuccinimide to undergo rapid self-catalyzed hydrolysis at neutral pH and room temperature, with complete hydrolysis achieved in less than 2 hours. Once hydrolyzed, the drug-linker is no longer subject to maleimide elimination reactions, preventing loss of drug from the antibody by this mechanism and forming a highly stable ADC. To compare these new drug-linkers to traditional maleimido drug-linkers, a number of in vitro and in vivo studies have been conducted. Results of these studies will be presented to demonstrate a robust improvement in drug-linker stability compared to traditional drug-linker formats. Citation Format: Robert P. Lyon, Jocelyn R. Setter, Tim D. Bovee, Svetlana O. Doronina, Martha E. Anderson, Chris L. Leiske, Peter D. Senter. Self-stabilizing ADCs: antibody-drug conjugates prepared with maleimido drug-linkers that catalyze their own thiosuccinimide ring hydrolysis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4333. doi:10.1158/1538-7445.AM2013-4333