Abstract 5461: H002: A wide spectrum, highly selective fourth-generation EGFR inhibitor overcoming resistance harboring C797S mutation in NSCLC

Abstract BACKGROUND: Resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) is a major challenge in non-small cell lung cancer (NSCLC) treatment. EGFR activating mutations, such as exon 19 deletions (Del19) and L858R substitution, have been reported in 10-50% of patients with NSCLC. Although these patients respond well to early generations of TKIs, acquired resistance by mechanisms such as T790M mutation compromises their efficacy. Recently, the C797S mutation in combination with Del19 or L858R, and with T790M, has emerged as one of the most common mechanisms underlying on-target resistance to a third generation EGFR TKI, osimertinib. We are developing a fourth-generation EGFR inhibitor, H002, with a wide spectrum and high selectivity to address the growing unmet needs in NSCLC patients harboring C797S mutation. METHODS: H002’s selectivity was assessed by KINOMEscan against more than 400 human kinases. A panel of 44 kinases was further evaluated to enable early identification of off-target effect. In vitro and in vivo anti-tumor efficacy was determined in drug-resistant mutant cell lines, CDX and PDX models. Single mutants (Del or L858R), double mutants (Del/T790M or L858R/T790M) and triple mutants (Del/T790M/C797S or L858R/T790M/C797S) as well as wild type EGFR were assessed. Drug metabolism and pharmacokinetic (DMPK) properties were further assessed. H002’s safety profile was evaluated in rats and beagle dogs, and by hERG potassium channel assay. Acute toxicity, and repeated dose GLP toxicity studies were also conducted in IND-enabling studies. RESULTS: High kinase selectivity and very low off-target effects were demonstrated by kinome-wide profiling and safety screening. H002 was highly active against all forementioned single, double or triple EGFR mutants (IC50 < 5 nM), and highly selective against wild type EGFR. H002 also exhibited potent anti-tumor effects in a dose-dependent manner in various CDX and PDX models. Excellent PK properties were observed in rats and beagle dogs with bioavailability over 70%. H002 was shown to cross the blood-brain barrier post i.g. administration in rats. No adverse effects of respiratory, cardiovascular and central nervous system were observed in safety studies. Repeated-dose toxicity studies only showed EGFR-related adverse reactions, such as gastrointestinal and liver toxicity, with high safety margin over 10-folds. CONCLUSION: H002 has been demonstrated as a promising next generation EGFR inhibitor, with high selectivity, a wide spectrum and potent anti-tumor activity against various EGFR activating mutations, favorable DMPK and safety profiles. It will be further developed as a fourth-generation EGFR inhibitor to overcome drug resistance in NSCLC. Citation Format: Wei Huang, Lin Zhu, Xiaoe Yan, Xin Huang, Jia Hao, Shan Li, Xiangyu Li, Zhiming Chen, Yunchuan Jia, Haibo Li, Jianming Zhang, Xianming Deng, Caihong Yun. H002: A wide spectrum, highly selective fourth-generation EGFR inhibitor overcoming resistance harboring C797S mutation in NSCLC [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 5461.