Irinotecan, carboplatin, and imatinib in untreated extensive-stage small-cell lung cancer: a phase II trial of the Minnie Pearl Cancer Research Network.

Introduction: The tyrosine kinase KIT has variable expression in small-cell lung cancer (SCLC) and may be a prognostic factor. Imatinib targets KIT expression, providing rationale for studying its role in combination with chemotherapy in SCLC in a multicenter phase II trial.

Methods: Patients with untreated extensive-stage SCLC received carboplatin area under the concentration-time curve of 4 on day 1; irinotecan 60 mg/m2 on days 1, 8, and 15; and imatinib 600 mg/day. Treatment cycles were 28 days. Patients remained on imatinib until progressive disease or significant toxicity.

Results: Between September 2002 and May 2004, 68 patients were enrolled in this multicenter trial. Median age was 60 years (range, 37-81). The objective response rate was 66% (95% confidence interval: 54%-76%). Median progression-free survival was 5.4 months (95% CI: 4.3-6.0 months). Median overall survival was 8.4 months (95% CI: 6.3-10.5 months). Thirty-five percent of patients were alive at 1 year. Grade 3/4 hematologic toxicity included neutropenia (43%), anemia (16%), and thrombocytopenia (9%). Grade 3 nonhematologic toxicity included diarrhea (19%), fatigue (24%), and nausea (26%). Forty-eight of 56 patients (86%) with available tumor specimens had KIT expression detected. KIT expression did not appear to correlate with progression-free survival or overall survival in a retrospective analysis.

Conclusions: Irinotecan, carboplatin, and imatinib is a safe and generally well-tolerated regimen in patients with SCLC. However, the addition of imatinib did not improve results from those expected with chemotherapy alone.