Abstract
Abstract Dramatic clinical responses to a first generation anaplastic lymphoma kinase (ALK)-tyrosine kinase inhibitor (TKI) crizotinib have been observed in patients with advanced non-small cell lung cancer (NSCLC) haboring ALK fusion gene. Alectinib (CH5424802) (Chugai Pharmaceutical Co., Ltd.) is a second generation ALK-TKI could partially overcome acquired resistance to crizotinib in vitro (Cancer Cell 19, 2011: 679-90), and showed promising result in phase I/II clinical trials with high response rate (93.5 %) and less toxicity than crizotinib. However, even this promising ALK-TKI, the problem of acquired resistance is inevitable. To elucidate resistant mechanisms, we established an alectinib-resistant cell line H2228/CHR from H2228 that have echinoderm microtubule associated protein like 4 (EML4)-ALK fusion gene, by continuous exposure to this agent. ALK fusion gene disappeared in H2228/CHR, which was confirmed Western blotting, IHC, qRT-PCR and FISH. H2228/CHR cells presented higher phosphorylated levels of epidermal growth factor receptor (EGFR) than the parental H2228 cells and became more sensitive to EGFR-TKI erlotinib. Next, we established alectinib-resistant ABC-11/CHR cells from ABC-11, a cell line established from pleural effusion of EML4-ALK positive ALK-TKI naïve patient. In ABC-11/CHR cells, phosphorylated levels of ALK was markedly decreased and phosphorylated levels of MET was increased.In addition, autocrine of HGF was increased in ABC-11/CHR cells. ABC-11/CHR showed sensitivity to ALK/MET tyrosine kinase inhibitor, crizotinib in vitro and in vivo model. In conclusion, inactivation of ALK signaling induced acquired resistance to alectinib in NSCLC harboring ALK fusion gene. Signaling switch from ALK to EGFR or MET was observed in the alectinib-resistant cells. We revealed to overcome such acquired resistance using erlotinib or crizotinib. Citation Format: Hideko Isozaki, Eiki Ichihara, Masayuki Yasugi, Ochi Nobuaki, Katsuyuki Hotta, Nagio Takigawa, Toshiaki Sendo, Mitsune Tanimoto, Katsuyuki Kiura. ALK inactivation induced acquired resistance to alectinib in lung cancer harboring EML4-ALK fusion gene. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3721. doi:10.1158/1538-7445.AM2014-3721
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