Abstract 971: Synergistic effect of c-Met inhibitor volitinib in combination with EGFR inhibitor Gefitnib on EGFR-TKI resistant NSCLC model HCC827C4R harboring acquired Met gene amplification.
Authors: Zhou Feng , Ren Yongxin , Cui Yumin , Chen Hanyang , Jiao Longxian , Dai Guangxiu , Fan Shiming , Sun Junen , Yu Yongjuan , Sai Yang , Gu Yi , Qing Weiguo , Su Weiguo 
Published: August 2014

Abstract
It is well recognized that non-small cell lung carcinoma (NSCLC) patients with activating EGFR mutations will develop drug resistance after receiving EGFR-tyrosine kinase inhibitors (EGFR-TKI). About 20% of those patients with TKI resistance were identified to harbor Met gene amplification. The aim of this study includes two aspects: a) generating an acquired c-Met amplified EGFR-TKI resistant tumor line in preclinical setting, and b) exploring combination effect of c-met inhibitor volitinib and EGFR inhibitor gefitinib on the new tumor line. Volitinib is a novel, highly potent and selective c-Met inhibitor, currently being evaluated in the phase I clinical trial.
HCC827(exon 19 del E746-A750), a human NSCLC cell line, was treated with increasing concentrations of EGFR inhibitor for about 6 months and gradually produced the resistance to EGFR-TKIs, such as gefitinib and erlotinib. One of the subclones, HCC827C4R was isolated and was confirmed to carry Met gene amplification in comparison to parent cell line HCC827. It was not sensitive to volitinib treatment in cell survival assay due to dual activation of EGFR and c-Met pathways. The results from signal pathway study demonstrated that in HCC827C4R cells, volitinib or gefitinib alone only inhibited the phosphorylation of c-Met or EGFR, respectively, but had no effect on the activation of downstream molecules such as Akt and ERK which drive tumor cell proliferation and other cell functions. In contrast, combination of volitinib and gefitinib significantly inhibited phosphorylation of EGFR, c-Met, Akt and ERK in HCC827C4R, and consequently led to a synergistic effect on inhibiting tumor cell growth in vitro. These results were further confirmed in HCC827C4R xenograft model in vivo at clinically relevant doses. Combination of volitinib and gefitinib induced significant tumor regression and displayed synergistic effect compared to treatment by either gefitinib or volitinib alone. Consistent with in vitro results, combination group strongly inhibited the downstream Akt and ERK phosphorylation. In addition, combination treatment was well tolerant and no significant drug-drug exposure interaction was observed. These data indicated that both c-Met and EGFR could contribute to activating downstream signaling pathway and control HCC827C4R cell growth. Blocking either pathway may not be strong enough to stop tumor growth.
In conclusion, a cell line with activating EGFR mutation and c-Met gene amplification was generated with resistance to gefitinib and insensitivity to volitinib. The combination treatment with volitinib and an EGFR inhibitor gefitinib was highly effective in vitro and in vivo, suggesting that such combination could provide a safe and effective treatment in clinics for this particular patient population.
Citation Format: Feng Zhou, Yongxin Ren, Yumin Cui, Hanyang Chen, Longxian Jiao, Guangxiu Dai, Shiming Fan, Junen Sun, Yongjuan Yu, Yang Sai, Yi Gu, Weiguo Qing, Weiguo Su. Synergistic effect of c-Met inhibitor volitinib in combination with EGFR inhibitor Gefitnib on EGFR-TKI resistant NSCLC model HCC827C4R harboring acquired Met gene amplification. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 971. doi:10.1158/1538-7445.AM2013-971