Activity of IPI-504, a novel heat-shock protein 90 inhibitor, in patients with molecularly defined non-small-cell lung cancer.

Purpose: IPI-504 is a novel, water-soluble, potent inhibitor of heat-shock protein 90 (Hsp90). Its potential anticancer activity has been validated in preclinical in vitro and in vivo models. We studied the activity of IPI-504 after epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) therapy in patients with advanced, molecularly defined non-small-cell lung cancer (NSCLC).

Patients And Methods: Patients with advanced NSCLC, prior treatment with EGFR TKIs, and tumor tissue available for molecular genotyping were enrolled in this prospective, nonrandomized, multicenter, phase II study of IPI-504 monotherapy. The primary outcome was objective response rate (ORR). Secondary aims included safety, progression-free survival (PFS), and analysis of activity by molecular subtypes.

Results: Seventy-six patients were enrolled between December 2007 and May 2009 from 10 United States cancer centers. An ORR of 7% (five of 76) was observed in the overall study population, 10% (four of 40) in patients who were EGFR wild-type, and 4% (one of 28) in those with EGFR mutations. Although both EGFR groups were below the target ORR of 20%, among the three patients with an ALK gene rearrangement, two had partial responses and the third had prolonged stable disease (7.2 months, 24% reduction in tumor size). The most common adverse events included grades 1 and 2 fatigue, nausea, and diarrhea. Grade 3 or higher liver function abnormalities were observed in nine patients (11.8%).

Conclusion: IPI-504 has clinical activity in patients with NSCLC, particularly among patients with ALK rearrangements.