[Irinotecan plus oral S-1 in patients with advanced colorectal cancer--biweekly IRIS regimen]

We planned to conduct a phase II clinical study of combination therapy with CPT-11 and S-1. The antitumor effect was the primary endpoint, while the safety, progression-free survival time, and median survival time were the secondary endpoints. The subjects were untreated patients with inoperable advanced colorectal cancer aged 20-75 years. Based on the results of our previous phase I/II study in patients with gastric cancer, the dosage was established in consideration of safety for outpatient therapy. CPT-11 was administered at a dose of 100 mg/m2 (on days 1 and 15) as an intravenous infusion over 90 minutes, and oral S-1 (40 mg/m2) was administered after breakfast and dinner and then withdrawn for 2 weeks. No other serious adverse reactions occurred (either hematological or non-hematological), and all patients could receive therapy safely on an outpatient basis. Interim analysis suggested excellent results, with a response rate of 50%. Combination therapy with CPT-11 and S-1 achieved a high response rate and could be given safely. These findings suggest that the therapy has potential as first-line treatment for inoperable advanced recurrent colorectal cancer.