Rationale for co-targeting IGF-1R and ALK in ALK fusion positive lung cancer

The ALK tyrosine kinase inhibitor (TKI), crizotinib, shows significant activity in patients whose lung cancers harbor ALK fusions but its efficacy is limited by variable primary responses and acquired resistance. In work arising from the intriguing clinical observation of a patient with ALK fusion+ lung cancer who had an ‘exceptional response’ to an IGF-1R antibody, we define a therapeutic synergism between ALK and IGF-1R inhibitors. Similar to IGF-1R, ALK fusion proteins bind to the adaptor, IRS-1, and IRS-1 knockdown enhances the anti-tumor effects of ALK inhibitors. In models of ALK TKI resistance, the IGF-1R pathway is activated, and combined ALK/IGF-1R inhibition improves therapeutic efficacy. Consistent with this finding, IGF-1R/IRS-1 levels are increased in biopsy samples from patients progressing on crizotinib therapy. Collectively, these data support a role for the IGF-1R/IRS-1 pathway in both ALK TKI-sensitive and TKI-resistant states and provide biological rationale for further clinical development of dual ALK/IGF-1R inhibitors.