Phase II study of a combination of irinotecan and S-1 in patients with advanced gastric cancer (OGSG0002).

Background/aims: To investigate the efficacy and safety of the combination therapy of irinotecan (CPT-11) plus S-1 in patients with advanced gastric cancer at the dose recommended by a previous phase I study.

Methods: A total of 23 patients received 80 mg/m(2) of CPT-11 on days 1 and 15, and S-1 at a dose level set on the basis of the body surface area (BSA): 40 (BSA <1.25 m(2)), 50 (BSA > or =1.25 to <1.5 m(2)) or 60 mg (BSA > or =1.5 m(2)) b.i.d. was given from days 1-21.

Results: The overall response rate was 47.8% (11 of 23, 95% confidence interval, CI: 27.4-68.2%). The median time to progression (TTP) was 210 days (95% CI: 145-322 days) and the median survival time was 394 days (95% CI: 241-484 days). The incidence of grade 3 or 4 hematological and non-hematological toxicity was 17.4 and 8.7%. The most common hematological toxicity was anemia and the most common non-hematological toxicity was diarrhea.

Conclusion: The combination therapy of CPT-11 and S-1 provided prolonged TTP with low toxicity, and the results warrant a further phase III study to define the efficacy in improvement of survival in patients with advanced gastric cancer.