Abstract 2192: A novel mechanism of EML4-ALK rearrangement in a patient-derived cell line and its tumor growth inhibition by an ALK inhibitor CH5424802.

Purpose: EML4-ALK is a driver oncogene in non-small cell lung cancer (NSCLC) and has been developed into a promising molecular target for antitumor agents. Although EML4-ALK is reported to be formed by inversion of chromosome 2, other mechanisms of gene fusion remain unknown. Here we characterize the EML4-ALK fusion gene of a new cell line derived from a patient of NSCLC. In addition, the efficacy of ALK inhibitors against this new cell line was examined. Experimental Design: An EML4-ALK-positive cell line, termed LC649, was established from pleomorphic carcinoma, a rare subtype of NSCLC. We investigated the chromosomal aberrations using fluorescence in situ hybridization (FISH) and comparative genomic hybridization (CGH). CH5424802, a selective ALK inhibitor, was evaluated in the antitumor activity against LC649 in vitro and in vivo xenograft model. Results: Our initial characterization revealed that LC649 harbors variant 3 of EML4-ALK fusion with 2-fold copy number gain. Interestingly, CGH and metaphase-FISH analysis showed that LC649 contained, in addition to two normal chromosome 2, two aberrant chromosome 2 that were fragmented and scattered. These observations provided the first evidence that EML4-ALK fusion in LC649 cells was formed in chromosome 2 by a distinct mechanism of genomic rearrangement, termed “chromothripsis”. Additionally, CH5424802 inhibited phospho-ALK and suppressed tumor growth of the LC649 cells in vitro and in vivo in a xenograft model. Conclusions: Our results suggested that chromothripsis may be a mechanism of oncogenic rearrangement of EML4-ALK. CH5424802 was effective against EML4-ALK positive tumors with ALK copy number gain mediated by chromothripsis. Citation Format: Tatsushi Kodama, Noriko Motoi, Hironori Ninomiya, Hiroshi Sakamoto, Kunio Kitada, Toshiyuki Tsukaguchi, Yasuko Sato, Nobuya Ishii, Yasuhito Terui, Kiyohiko Hatake, Yuichi Ishikawa. A novel mechanism of EML4-ALK rearrangement in a patient-derived cell line and its tumor growth inhibition by an ALK inhibitor CH5424802. [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 2192. doi:10.1158/1538-7445.AM2013-2192