Abstract 199: Evaluation of multiple EGFR tyrosine kinase inhibitors against clinically relevant EGFR mutants using in vitro modeling

Abstract

Abstract Purpose: We are able to use multiple EGFR-TKIs to treat patients with lung cancer harboring EGFR mutations. However, there is no clear guideline regarding which EGFR-TKIs should be used for which mutations. The purpose of this study is to establish an in vitro model to determine the “therapeutic window” of EGFR-TKIs against various types of EGFR mutations, including several EGFR exon 20 insertion mutations. Experimental design: We evaluated drug sensitivity and downstream signaling of human lung cancer cell lines harboring EGFR mutations (PC9, H3255, PC9-ER, BID007 and H1975) and Ba/F3 cells exogenously expressing mutated or wild type EGFR for the 1st (erlotinib), 2nd (afatinib), and 3rd (osimertinib and rociletinib) generation EGFR-TKIs using MTS assay, apoptosis assay and western blotting, simultaneously. An in vitro model of mutation specificity was created by calculating the ratio of IC50 values between mutated and wild type EGFRs. Results: The model of mutation specificity identified wide therapeutic windows of afatinib for exon 19 deletions and L858R and those of osimertinib and rociletinib for T790M positive mutations in human cell lines and Ba/F3 cells. In human cell lines and Ba/F3 cells harboring exon 19 deletions or L858R, afatinib showed the lowest IC50 and most potently inhibited the phosphorylation of EGFR, AKT, and ERK. Afatinib and 3rd generation EGFR-TKIs (osimertinib and rociletinib), effectively inhibited the cell growth and the phosphorylation of downstream signaling of EGFR in T790M positive cells. For EGFR exon 20 insertion mutations, osimertinib was potent and presented the most wide therapeutic window. Conclusion: This model will provide a preclinical rationale for proper selection of EGFR-TKIs against clinically-relevant EGFR mutations including EGFR exon 20 insertions. Citation Format: Hanako Hasegawa. Evaluation of multiple EGFR tyrosine kinase inhibitors against clinically relevant EGFR mutants using in vitro modeling. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 199.