Mechanisms of Acquired Crizotinib Resistance in ALK-Rearranged Lung Cancers

Most anaplastic lymphoma kinase (ALK)-positive non-small cell lung cancers (NSCLCs) are highly responsive to treatment with ALK tyrosine kinase inhibitors (TKIs). However, patients with these cancers invariably relapse, typically within 1 year, because of the development of drug resistance. Herein, we report findings from a series of lung cancer patients (n = 18) with acquired resistance to the ALK TKI crizotinib. In about one-fourth of patients, we identified a diverse array of secondary mutations distributed throughout the ALK TK domain, including new resistance mutations located in the solvent-exposed region of the adenosine triphosphate-binding pocket, as well as amplification of the ALK fusion gene.…