Phase II trial of irinotecan/gemcitabine as second-line therapy for relapsed and refractory small-cell lung cancer: Cancer and Leukemia Group B Study 39902

Background: This phase II study evaluated the efficacy and safety of the irinotecan/gemcitabine combination in patients with relapsed/refractory small-cell lung cancer (SCLC). Patients and methods: Patients with measurable tumor who had received one previous chemotherapy or chemotherapy/radiation regimen were eligible. Gemcitabine 1000 mg/m(2) was administered i.v. over 30 min followed immediately by irinotecan 100 mg/m(2) i.v. over 90 min, both on days 1 and 8 every 21 days. Patients were stratified based on response to initial treatment [i.e. primary sensitive disease with progression >= 3 months (group A), or refractory disease (group B)]. Results: Seventy-three patients were enrolled but one never received treatment and one ineligible patient did not have SCLC. Median patient ages of the remaining patients were 61 and 63 years in groups A (n = 35) and B (n = 36), respectively, with performance status of 0 or 1 in 85% of 71 patients. Primary grade 3/4 toxic effects in groups A versus B were neutropenia (36% versus 43%), thrombocytopenia (36% versus 26%), nausea (12% versus 11%), vomiting (0 versus 11%), diarrhea (12% versus 9%), and pulmonary (12% versus 12%). Two patients had fatal events including pneumonitis (n = 1) and acute respiratory distress syndrome (n = 1). Responses occurred in 11 group A [two complete responses and nine partial responses (PRs)] and four group B (all PRs) patients, for response rates of 31% [95% confidence interval (CI) 17%, 49%) and 11% (95% CI 3%, 26%), respectively. Median survival and progression-free survival times were 7.1 (95% CI 6, 10.5) versus 3.5 (95% CI 3.1, 5.7) months, and 3.1 (95% CI 1.6, 5.3) versus 1.6 (95% CI 1.4, 2.8) months for group A versus B. Conclusion: The irinotecan/gemcitabine combination is active and well tolerated as second-line therapy in SCLC patients. Additional studies are warranted as second-line therapy in patients who progressed 90 days or more after first-line therapy. However, the observed efficacy results in refractory SCLC patients indicate that this regimen should not be further explored in this population.