Abstract 957: The ALK inhibitor LDK378 overcomes crizotinib resistance in non-small cell lung cancer

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Non-small cell lung cancers (NSCLC) harboring anaplastic lymphoma kinase (ALK) gene rearrangements are sensitive to the ALK tyrosine kinase inhibitor (TKI) crizotinib. However, these cancers invariably relapse due to the development of resistance, and approximately 1/3 of such cancers develop resistance mutations within the ALK tyrosine kinase domain. Here we report the preclinical evaluation of the next-generation ALK TKI, LDK378 in the setting of crizotinib resistance. Using EML4-ALK mutant Ba/F3 cellular models, in vivo models of acquired resistance to crizotinib, and novel cell lines established from biopsies of crizotinib-resistant NSCLC patients, we have examined the efficacy of LDK378 in crizotinib-naive and -resistant ALK-positive cancers. These studies reveal that LDK378 is more potent than crizotinib and effectively overcomes resistance in vitro and in vivo. In particular, LDK378 inhibits ALK harboring crizotinib resistance mutations, including L1196M, G1269A, I1171T and S1206Y. Cell lines derived from crizotinib-resistant biopsies were sensitive to LDK378, including one that did not harbor an ALK resistance mutation and was also sensitive to crizotinib, suggesting that some crizotinib-resistant cancers with wildtype ALK are still sensitive to complete ALK inhibition. We observed that LDK378 did not effectively overcome two crizotinib-resistant ALK mutations, G1202R and F1174C ALK, and mutations in one of these residues was identified in 5 out of 11 biopsies from patients with acquired resistance to LDK378. Altogether our results demonstrate that LDK378 can overcome many mechanisms of crizotinib resistance, consistent with emerging clinical data showing marked efficacy of LDK378 in patients with crizotinib-resistant disease. Citation Format: Luc Friboulet, Nanxin Li, Ryohei Katayama, Christian C. Lee, Justin F. Gainor, Adam S. Crystal, Pierre-Yves Michellys, Mark M. Awad, Noriko Yanagitani, Sungjoon Kim, AnneMarie Pferdekamper, Jie Li, Shailaja Kasibhatla, Frank Sun, Xiuying Sun, Su Hua, Peter McNamara, Sidra Mahmood, Elizabeth L. Lockerman, Naoya Fujita, Makoto Nishio, Jennifer L. Harris, Alice T. Shaw, Jeffrey A. Engelman. The ALK inhibitor LDK378 overcomes crizotinib resistance in non-small cell lung cancer. [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 957. doi:10.1158/1538-7445.AM2014-957