Selective ALK inhibitor alectinib with potent antitumor activity in models of crizotinib resistance

• Alectinib was effective against EML4-ALK tumors remaining after treatment with crizotinib.
• Alectinib inhibited the growth of some EML4-ALK mutant-driven tumors, including the G1269A model.
• Alectinib might provide therapeutic opportunities for crizotinib-treated patients.

The clinical efficacy of the ALK inhibitor crizotinib has been demonstrated in ALK fusion-positive NSCLC; however, resistance to crizotinib certainly occurs through ALK secondary mutations in clinical use. Here we examined the efficacy of a selective ALK inhibitor alectinib/CH5424802 in models of crizotinib resistance. Alectinib led to tumor size reduction in EML4-ALK-positive xenograft tumors that failed to regress fully during the treatment with crizotinib. In addition, alectinib inhibited the growth of some EML4-ALK mutant-driven tumors, including the G1269A model. These results demonstrated that alectinib might provide therapeutic opportunities for crizotinib-treated patients with ALK secondary mutations.