A multicenter phase II study of biweekly paclitaxel and S-1 combination chemotherapy for unresectable or recurrent gastric cancer

Purpose: This Phase II study assessed the activity and safety of biweekly paclitaxel and oral S-1 as treatment for unresectable and recurrent gastric cancer. The maximum tolerated dose for this regimen had been established previously in a Phase I study performed in Japanese patients. Patients and methods: Chemotherapy was performed using two anticancer agents, S-1 and paclitaxel. Oral S-1 (80 mg/m²) was administered twice a day after meals for two consecutive weeks from Day 1 to 14, followed by a 2 week recovery period; paclitaxel (120 mg/m²) was administered intravenously, biweekly, on Days 1 and 15. The patient received cycles of this regimen every 4 weeks (q 28-day cycles). The primary end point was the response rate according to the Response Evaluation Criteria in Solid Tumors. Results: A total of 39 patients (median age, 65 years) were enrolled; 13 other patients were screened, but found to be ineligible. All patients had unresectable and recurrent gastric cancer. The most common treatment-related Grade 3/4 adverse events were neutropenia (37.5%), appetite loss, diarrhea, decreased sodium (each 5%), and anemia, increased alanine aminotransferase, general fatigue, and dizziness (each 2.5%). Almost all the patients experienced alopecia. Intent-to-treat analysis showed a response rate of 43.6%. With a median follow-up of 14 months (range 8-21 months), median survival was 256 days and the median time to progression was 4 months. Conclusion: A combination regimen of biweekly paclitaxel and oral S-1 was well tolerated and showed promising activity against unresectable and recurrent gastric cancer.