Randomised phase II trial of irinotecan plus S-1 in patients with gemcitabine-refractory pancreatic cancer

Background: We aimed to compare the efficacy and safety of irinotecan/S-1 (IRIS) therapy with S-1 monotherapy in patients with gemcitabine-refractory pancreatic cancer. Methods: Patients were treated with oral S-1 (80–120 mg for 14 days every 4 weeks) plus intravenous irinotecan (100 mg m −2 on days 1 and 15 every 4 weeks; IRIS group) or oral S-1 group (80–120 mg daily for 28 days every 6 weeks). The primary endpoint was progression-free survival (PFS). Results: Of 137 patients enrolled, 127 were eligible for efficacy. The median PFS in the IRIS group and S-1 monotherapy group were 3.5 and 1.9 months, respectively (hazard ratio (HR)=0.77; 95% confidence interval (CI), 0.53–1.11; P =0.18), while the median overall survival (OS) were 6.8 and 5.8 months, respectively (HR=0.75; 95% CI, 0.51–1.09; P =0.13). Response rate was significantly higher in the IRIS group than in the S-1 monotherapy group (18.3% vs 6.0%, P =0.03). Grade 3 or higher neutropenia and anorexia occurred more frequently in the IRIS group. Conclusions: There was a trend for better PFS and OS in the IRIS group that could be a treatment arm in the clinical trials for gemcitabine-refractory pancreatic cancer.