In Vitro Characterization Of The Effect Of Nazartinib Against Non-Small Cell Lung Cancer Activating Clinically Relevant Egfr Mutants

Purpose: Multiple EGFR-TKIs are available and under development to treat patients with lung cancer harboring EGFR mutations. Nazartinib is one of the 3rd generation EGFR-TKIs targeting EGFR T790M as well as common mutations such as L858R and exon 19 deletions. Today, there is no clear guideline regarding which EGFR-TKIs should be used for which mutations. The purpose of this study is to clarify which EGFR-TKIs including nazartinib are best for each EGFR mutation, especially exon 20 insertion mutations using in vitro modeling. Experimental design: We evaluated drug sensitivity and downstream signaling of human lung cancer cell lines (PC9, H3255, H1975, PC9ER, BID007) and Ba/F3 cells harboring multiple types of EGFR mutations for 1st- (erlotinib), 2nd- (afatinib) and 3rd- (osimertinib and nazartinib) generation EGFR-TKIs by MTS assay and western blotting. 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 a wide therapeutic window of each EGFR-TKIs for exon 19 deletions and L858R. On the other hand, osimertinib and nazartinib have wide therapeutic window 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 dramatically inhibited the phosphorylation of EGFR, AKT, and ERK. Afatinib and 3rd generation EGFR-TKIs, osimertinib and nazartinib, effectively inhibited the phosphorylation of EGFR, AKT, and ERK in T790M positive cells. For EGFR exon 20 insertion mutations, althogh afatinib, osimertinib and nazartinib effectively inhibited the phosphorylation of EGFR, AKT, and ERK in several exon 20 insertion mutations, osimertinib and nazartinib were potent and presented a wide therapeutic window. Conclusion: Nazartinib as well as osimertinib has wide therapeutic windows for exon 19 deletions, L858R, T790M and some exon 20 insertions . Citation Format: Keita Masuzawa, Hiroyuki Yasuda, Toshiyuki Hirano, Shigenari Nukaga, Hanako Hasegawa, Junko Hamamoto, Katsuhiko Naoki, Kenzo Soejima, Tomoko Betsuyaku. In vitro characterization of the effect of nazartinib against non-small cell lung cancer activating clinically relevant EGFR mutants [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2099. doi:10.1158/1538-7445.AM2017-2099