ALK Resistance Mutations and Efficacy of Lorlatinib in Advanced Anaplastic Lymphoma Kinase-Positive Non–Small-Cell Lung Cancer

PURPOSELorlatinib is a potent, brain-penetrant, third-generation anaplastic lymphoma kinase (ALK)/ROS1 tyrosine kinase inhibitor (TKI) with robust clinical activity in advanced ALK-positive non–small-cell lung cancer, including in patients who have failed prior ALK TKIs. Molecular determinants of response to lorlatinib have not been established, but preclinical data suggest that ALK resistance mutations may represent a biomarker of response in previously treated patients.PATIENTS AND METHODSBaseline plasma and tumor tissue samples were collected from 198 patients with ALK-positive non–small-cell lung cancer from the registrational phase II study of lorlatinib. We analyzed plasma DNA for ALK mutations using Guardant360. Tumor tissue DNA was analyzed using an ALK mutation–focused next-generation sequencing assay. Objective response rate, duration of response, and progression-free survival were evaluated according to ALK mutation status.RESULTSApproximately one quarter of patients had ALK mutations detected ...