LAUSR

Heterobifunctional degraders, known as proteolysis targeting chimeras (PROTACs), is an emerging modality for drug discovery, and theoretically possess catalytic mode-of-action, yet few studies have either confirmed or exploited this potential advantage of event-driven pharmacology. Degraders of oncogenic EML4-ALK fusions were developed by conjugating ALK inhibitors to cereblon ligands guided by computational models. To study the sub-stoichiometric capacity of the degrader molecules, simultaneous optimization of pharmacology and compound properties using ternary complex modeling and physicochemical considerations yielded multiple catalytic degraders that were more resilient to clinically relevant ATP-binding site mutations than parental kinase inhibitor drugs. Using HiBiT assay to assess the target degradation and NanoBRET for target occupancy, we illustrated the concept of catalytic degradation of EML4-ALK. Our strategy culminated in the design of the orally bioavailable derivative CPD-1224 that avoided hemolysis (a feature of detergent-like PROTACs), degraded the otherwise recalcitrant compounded mutant L1196M/G1202R in vivo, and commensurately slowed tumor growth, while the third generation ALK inhibitor drug lorlatinib had no effect. These results validate our original therapeutic hypothesis by exemplifying opportunities for catalytic degraders to proactively address binding site resistant mutations in cancer. Citation Format: Yang Gao, Baishan Jiang, Hellen Kim, Jianwei Che, Katherine Donovan, John Hatcher, Fidel Huerta, Nicholas Kwiatkowski, Yingpeng Liu, Peter Liuni, Rebecca J. Metivier, Vineeth Murali, Radosław Nowak, Tinghu Zhang, Eric Fischer, Nathanael Gray, Lyn Jones. Catalytic degraders effectively address kinase site mutations in EML-ALK oncogenic fusions [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3426.