Abstract 5135: Targeting EGFR cysteine 775 in EGFR mutant lung cancer

Abstract Covalent targeting of EGFR cysteine 797 by osimertinib is one of the most successful breakthroughs in targeted therapy, fundamentally transforming the treatment landscape for non-small cell lung cancer (NSCLC) patients. However, resistance driven by mutation of C797 remains a major clinical challenge. Developing novel covalent strategies beyond C797 targeting presents a compelling opportunity for next-generation EGFR inhibitors. We first demonstrated that cysteine 775, located deep within the ATP-binding pocket, is accessible by a rationally designed covalent molecule ZNL-3, which exhibited strong efficacy in osimertinib-resistant mouse models. To further enhance resilience to resistance-causing mutations, we developed a dual-warhead, bident compound—YNW-1—which covalently targets both cysteine 775 and 797 simultaneously. YNW-1 is the first molecule to exhibit balanced reactive efficiency on both cysteines, rendering single-site mutations ineffective to confer resistance. The discovery of ZNL-3 and YNW-1 represents significant advancements in EGFR-targeted drug development, and further optimization toward clinical translation is a worthwhile strategy. Citation Format: Jie Jiang, Zhengnian Li, Yaning Wang, Stephen J. Collins, Felix H. Gottlieb, Prafulla C. Gokhale, Michael J. Eck, Pasi A. Jänne, Jianwei Che, Nathanael S. Gray, Tinghu Zhang. Targeting EGFR cysteine 775 in EGFR mutant lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 5135.