Abstract 1974: Discovery of TRX-211-399, a potent, CNS-penetrant, highly selective inhibitor of EGFR exon 20 insertion mutations

Abstract Lung cancer is the leading cause of cancer-related deaths worldwide, accounting for approximately 2 million new cases and 1.8 million deaths annually. Various types of EGFR-activating mutations are one of the most important oncogenic drivers in non-small cell lung cancer (NSCLC). Among NSCLC patients with EGFR mutations, 5-10% of patients have EGFR exon 20 insertion (ex20ins) mutations that are insensitive to clinically available EGFR tyrosine kinase inhibitors (TKIs). Recently, as mobocertinib (EXKIVITY®) failed to improve progression-free survival in Phase 3 clinical trial, there remains a high unmet medical need to develop new drugs with wider therapeutic window to treat NSCLC harboring EGFR ex20ins mutations. Herein, we report a novel EGFR-TKI, TRX-211-399, specifically designed to target ex20ins mutations. TRX-211-399 potently inhibited the proliferation of not only Ba/F3 cells overexpressing near-loop (A767dupASV, S768dupSVD) and far-loop (H773insNPH, H773dupH) mutations but also patient-derived NSCLC cell line. In particular, TRX-211-399 demonstrated high selectivity against wild-type EGFR. With favorable DMPK profiles, once-daily oral administration of TRX-211-399 showed significant tumor regression in multiple Ba/F3 xenograft models carrying different EGFR exon20ins mutations. Furthermore, in a PC-9-luc cell intracranial xenograft model, TRX-211-399 induced substantial anti-tumor effects and prolonged survival without body weight loss. TRX-211-399 is currently undergoing further preclinical evaluation as a potential candidate for clinical development for patients with EGFR exon20ins mutations. Citation Format: Kwangwoo Chun, Sumin Lim, Joohyun Lee, Seulgi Choi, Seongrak Kim, Youngil Choi, Areum Park, Bohee Kim, Yongseo Park, Eunhyun Choi, Sungwon Lee, Koo Lee. Discovery of TRX-211-399, a potent, CNS-penetrant, highly selective inhibitor of EGFR exon 20 insertion mutations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1974.