Abstract 3342: Discovery of potent and selective next-generation EGFR inhibitors with activity against single, double, and triple mutant EGFR variants including T790M and C797S
Authors: Huang Wei-Sheng , Nadworny Sara , Narasimhan Narayana , Eyermann Charles J. , Dalgarno David C. , Rivera Victor M. , Shakespeare William C. 
Published: June 2022

Introduction: EGFR activating mutations are observed in 10-50% of NSCLC patients and the common mutations (L858R [L] and exon 19 deletions [D]) are initially sensitive to first-, second-, and third-generation EGFR inhibitors (eg erlotinib [1G], afatinib [2G], and osimertinib [3G], respectively). However, on-target resistance is observed in a substantial percentage of patients, with T790M (T) and C797S (C) observed most frequently (post-1G/2G and post-3G, respectively). We set out to identify a next-generation inhibitor with 1) potent activity against all 8 major single (L and D), double (LT, DT, LC, DC), and triple (LTC, DTC) mutant variants, 2) selectivity over wild type (WT) EGFR, and 3) ability to penetrate the central nervous system (CNS).

Experimental Procedures: Drug activity was determined by assessing effects in kinase assays and on tumor and BaF3 cell lines expressing WT or mutant forms of EGFR. For efficacy studies, mice were dosed orally once daily at doses that did not exceed the maximum tolerated dose.

Results: Here we report the identification of a series of compounds with potent and selective in vitro and in vivo activity against all major classes of EGFR activating and resistance mutations and with selectivity over WT EGFR. A representative member from this series (Cmpd A) potently inhibits the kinase activity of EGFR L, LT, and LTC variants with IC50s ≤0.2 nM, compared to IC50s for osimertinib of 0.4, 0.2, and 360 nM respectively. In engineered BaF3 cells, Cmpd A inhibited viability of all 8 EGFR single, double, and triple mutant variants with IC50s &lt;7 nM, while erlotinib was inactive against LT, DT, LTC, and DTC, and osimertinib was inactive against LC, DC, LTC, and DTC. Cmpd A inhibited the activity of all 8 variants with 7- to 46-fold selectivity over WT EGFR, which compared favorably to the 7- to 10-fold selectivity erlotinib exhibited for L and D. In vivo, Cmpd A (30 mg/kg QD) induced tumor regression, or inhibited tumor growth by at least 90%, in models containing EGFR single (L), double (LT), and triple (LTC and DTC) mutant variants. Studies to examine the CNS penetration of compounds are underway.

Conclusions: We have identified a series of next-generation EGFR inhibitors with potent in vitro and in vivo activity against single, double, and triple mutant EGFR variants including T790M and C797S.

Citation Format: Wei-Sheng Huang, Sara Nadworny, Narayana Narasimhan, Charles J. Eyermann, David C. Dalgarno, Victor M. Rivera, William C. Shakespeare. Discovery of potent and selective next-generation EGFR inhibitors with activity against single, double, and triple mutant EGFR variants including T790M and C797S [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3342.