ALK L1196M + ALK G1202R

ALK resistance mutations increase with each successive generation of ALK TKI and may be underestimated by tumor genotyping. Sequential treatment with increasingly potent ALK TKIs may promote acquisition of ALK resistance mutations leading to treatment-refractory compound ALK mutations.

This study shows that mechanisms of resistance to lorlatinib are diverse and complex, requiring new therapeutic strategies to tailor treatment upon disease progression.

EML4-ALK rearranged malignant pleural mesothelioma (MPM) is rare and its responses to anaplastic lymphoma kinase (ALK) inhibitors, including alectinib and lorlatinib, remain unexplored. Moreover, our case also revealed acquired mechanisms of lorlatinib resistance mediated by multiple mutations ALK I1171N, L1196M, and G1202R, contributing an incremental step to our understanding of the complexity of acquired resistance mechanisms in sequential ALK inhibitor therapy. The reviews of this paper are available via the supplemental material section.

" From April 2015 to July 2019, 92 patients enrolled; 81 (88.0%) received ALK TKI as first-line (crizotinib, n = 59; alectinib, n = 22), 10 (10.9%) received TKI as second-line (alectinib, n = 6; crizotinib, n = 2; ceritinib, n = 1; brigatinib, n = 1), and 1 (1.1%) was treated in third-line (lorlatinib). NGS of cell-free plasma DNA is useful not only for the detection of ALK fusions and resistance mutations but also for assessing prognosis and monitoring the dynamic changes of genomic alterations in ALK+ NSCLC treated with ALK TKI. Research Funding: Bio & Medical Technology Development Program of the National Research Foundation (NRF) funded by the Korean government (MSIT) (No.NRF-2017M3A9G5060259)Bio & Medical Technology Development Program of the National Research Foundation (NRF) funded by the Kor"

Brigatinib showed clinically meaningful efficacy in Japanese patients refractory to prior alectinib (first line or post crizotinib), regardless of prior chemotherapy. The safety profile of brigatinib was consistent with prior studies and no new safety findings were identified. Research Funding: Takeda Pharmaceutical Company Ltd