LAUSR

EGFR is one of receptor tyrosine kinases (RTKs) and, upon ligand binding, turns on the downstream signals that include oncogenic RAS/MEK/ERK, PI3K/AKT/mTOR, and JAK/STAT pathways. EGFR gene mutations, such as Exon 19 deletion (Del19) and L858R mutations, induce abnormal activation of the EGFR protein even in the absence of the ligand leading to various cancers. EGFR mutations are found in non-small cell lung cancer (NSCLC) patients with 10-15% frequency (approximately 50% in Asian patients). Starting from Del19 and L8585R mutations, additional mutations in the EGFR gene occur during the treatment with 1st/2nd/3rd generation EGFR inhibitors, resulting in Del19/T790M, L858R/T790M, Del19/T790M/C797S, L858R/T790M/C797S, Del19/C797S, and L858R/C797S mutations. While double mutations that include the T790M mutation have been efficaciously treated with Osimertinib, there are currently no approved therapies that can effectively target the C797S-containing mutants. Here we present preclinical data showing a small-molecule inhibitor that effectively disables EGFR mutants, including Del19/T790M/C797S, L858R/T790M/C797S, Del19/C797S, and L858R/C797S mutants. High potency and selectivity were confirmed by in vitro kinase assays and cellular assays. Outstanding anti-cancer activity was observed in mouse xenograft models with various EGFR mutations and, importantly, it was inactive in the EGFR wild-type model. With confirmed brain penetrance through in vivo studies, our potent EGFR inhibitor may provide a great therapeutic potential for patients with EGFR mutation-driven NSCLC. Citation Format: Yeejin Jeon, Kiram Lee, Anna Jang, Miyeon Kim, Kyeong Jin Yoon, Yeri Lee, Dongsu Kim, Donggeon Kim, Dohyun Park, Sang Kyun Lim, Sung Pil Choi. Discovery of a small-molecule EGFR inhibitor that can potently target various EGFR mutants, including C797S mutant, in vitro and in vivo. [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 4016.