A randomized phase II study of gemcitabine and S-1 combination therapy versus gemcitabine monotherapy for advanced biliary tract cancer.

In order to confirm the impact of adding S-1 to gemcitabine, we conducted a randomized phase II study to compare the combination therapy of gemcitabine plus S-1 to gemcitabine monotherapy in patients with advanced biliary tract cancer. Sixty-two patients with advanced cholangiocarcinoma or gallbladder cancer were randomized to either the combination therapy of gemcitabine and S-1 (gemcitabine 1,000 mg/m(2) on days 1 and 15 and S-1 40 mg/m(2) b.i.d. on days 1-14, repeated every 4 weeks) or gemcitabine monotherapy (gemcitabine 1,000 mg/m(2) on days 1, 8, and 15, repeated every 4 weeks). The primary endpoint of this study was response rate, and the regimen which showed the better response rate was selected as a candidate of phase III study. Tumor response was assessed every two cycles using Response Evaluation Criteria in Solid Tumors criteria version 1.0. The response rates of the combination therapy and the monotherapy were 20.0 and 9.4 %, respectively. The median time-to-progressions and overall survivals of these two treatments were nearly the same (5.6 vs. 4.3 months; 8.9 vs. 9.2 months). Adverse events occurred more frequently in the combination arm. The combination therapy of gemcitabine and S-1 showed the better response rate, but the superiority of this combination therapy was not clear in total. Because the standard of care changed to the combination therapy with gemcitabine and cisplatin during this study, it is difficult to select this combination therapy with a 4-week regimen as a candidate of phase III study.