Abstract 3144: Prediction of ALK mutations associated with acquired resistance to lorlatinib

Abstract

Abstract Anaplastic lymphoma kinase (ALK) rearrangements are important therapeutic targets in non-small cell lung cancer. They are currently treated with the first-generation ALK inhibitor crizotnib followed by more potent, second-generation ALK inhibitors, such as ceritinib, alectinib, or brigatinib. We reported different spectrums of ALK resistance mutations in the biopsies from patients progressing on these drugs. G1202R mutation was found more frequently after treatment with second generation ALK inhibitors. In addition to these drugs, the third-generation ALK inhibitor lorlatinib is currently being evaluated in phase 2 clinical trial. Ba/F3 models indicated that all single ALK mutants are sensitive to lorlatinib and some compound ALK mutations are resistant to lorlatinib. In this study, we performed accelerated mutagenesis screen on Ba/F3 models to predict the resistance mutations which potentially emerge in the patients treated with lorlatinib. Briefly, Ba/F3 cells expressing wild type EML4-ALK or mutant EML4-ALK containing C1156Y, F1174C, L1196M, G1202R, or G1269A were exposed to N-ethyl-N-nitrosourea (ENU). After a 24-hour incubation in normal media, the cells were seeded in 96-well plates and incubated in lorlatinib for 4 weeks. ALK kinase domain was sequenced in clones growing in lorlatinib to identify possible new mutations. As a result, Ba/F3 cells harboring wild type EML4-ALK did not show any mutation on ALK kinase domain. Crizotinib was used as a control to validate the efficiency of mutagenesis. We identified eight different mutations in clones growing in crizotinib, and those were reflecting the spectrum of mutations in the crizotinib-treated patients. Ba/F3 cells with mutant EML4-ALK showed additional compound mutations after incubation with lorlatinib. Those mutations included L1196M + L1198F and G1202R + L1198F which showed high resistance to lorlatinib in Ba/F3 models. Ba/F3 cells with different mutant EML4-ALK showed a distinct spectrum and different frequency of additional mutations. In conclusion, this study predicted that no single mutation would emerge to confer resistance to lorlatinib. Thus, compound mutations and ALK-independent mechanisms become essential mechanisms for lorlatinib resistance. Citation Format: Satoshi Yoda, Leila Dardaei, Manrose Singh, Jeffrey A. Engelman, Alice T. Shaw, Aaron N. Hata. Prediction of ALK mutations associated with acquired resistance to lorlatinib [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 3144. doi:10.1158/1538-7445.AM2017-3144