Abstract 2589: Investigations of Covalent Binding Efficiency for Third-Generation EGFR Irreversible Inhibitors AZD9291 and CO-1686

Abstract Patients with non-small cell lung cancer with activating EGFR mutations initially respond to first-generation and second-generation EGFR inhibitors. However, clinical efficacy is limited by acquired resistance, frequently driven by the EGFR T790M mutation. In addition, patients oftentimes experience severe side effects including rash and diarrhea due to the inhibition profile against wild-type EGFR. AZD9291 and CO-1686 are the leading third-generation irreversible EGFR inhibitors in clinical development. They selectively inhibit T790M EGFR, while sparing wild-type EGFR. In this study, we investigated the covalent binding efficiency of these two irreversible EGFR inhibitors using biochemical and cellular assays. We discovered that these two inhibitors had dramatic difference in covalent binding efficiencies in WT and mutant EGFR binding at biochemical and cellular levels. In pEGFR cellular assay, AZD9291 displayed much prolonged inhibition of pEGFR than CO-1686. In CO-1686 treated cells, recovery of pEGFR had reached 50% of control levels only after 4 hours. In the meantime, pEGFR in AZD9291 treated cells had no recovery even after 24 hours. These data may suggest different covalent bond formation efficiency and reversibility between different types of irreversible EGFR inhibitors. This may be one of the important factors for consideration when develop third-generation EGFR inhibitors. Citation Format: Zhen Qin, Xuebing Sun, Ye Liu, Yunguang Du, Miao Wang, Nan Hu, Jiye Zhang, Hao Peng, Lai Wang, Min Wei, Lusong Luo. Investigations of covalent binding efficiency for third-generation EGFR irreversible inhibitors AZD9291 and CO-1686. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2589. doi:10.1158/1538-7445.AM2015-2589