The Potent ALK Inhibitor Brigatinib (AP26113) Overcomes Mechanisms of Resistance to First- and Second-Generation ALK Inhibitors in Preclinical Models
2016
Purpose: Non–small cell lung cancers (NSCLCs) harboring ALK gene rearrangements (ALK + ) typically become resistant to the first-generation
anaplastic lymphoma kinase(ALK) tyrosine kinase inhibitor (TKI)
crizotinibthrough development of secondary
resistance mutationsin ALK or disease progression in the brain. Mutations that confer resistance to second-generation ALK TKIs
ceritiniband
alectinibhave also been identified. Here, we report the structure and first comprehensive preclinical evaluation of the next-generation ALK TKI
brigatinib. Experimental Design: A kinase screen was performed to evaluate the selectivity profile of
brigatinib. The cellular and in vivo activities of ALK TKIs were compared using engineered and cancer-derived cell lines. The
brigatinib–ALK co-structure was determined. Results:
Brigatinibpotently inhibits ALK and
ROS1, with a high degree of selectivity over more than 250 kinases. Across a panel of ALK + cell lines,
brigatinibinhibited native ALK (IC 50 , 10 nmol/L) with 12-fold greater potency than
crizotinib. Superior efficacy of
brigatinibwas also observed in mice with ALK + tumors implanted subcutaneously or intracranially.
Brigatinibmaintained substantial activity against all 17 secondary ALK mutants tested in cellular assays and exhibited a superior inhibitory profile compared with
crizotinib,
ceritinib, and
alectinibat clinically achievable concentrations.
Brigatinibwas the only TKI to maintain substantial activity against the most recalcitrant ALK
resistance mutation, G1202R. The unique, potent, and pan-ALK mutant activity of
brigatinibcould be rationalized by structural analyses. Conclusions:
Brigatinibis a highly potent and selective
ALK inhibitor. These findings provide the molecular basis for the promising activity being observed in ALK + ,
crizotinib-resistant patients with NSCLC being treated with
brigatinibin clinical trials. Clin Cancer Res; 22(22); 5527–38. ©2016 AACR .
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