A phase I study of S-1 administration and a 24-h infusion of cisplatin plus paclitaxel in patients with advanced gastric cancer

Abstract

4074 Background: S-1 may have a major role in the treatment of gastric cancer as single agent or as a component of combination chemotherapy in Japan. We previously reported a multicentric phase II study of S-1 combined with a 24-h infusion of cisplatin in patients with advanced gastric cancer. This combination was active, safe and had the possibility of being combined with other anticancer drug. Combination chemotherapy with S-1 and cisplatin plus paclitaxel for advanced gastric cancer might yield a stronger antitumor effect. The objective of this study was to determine the dose-limiting toxicity (DLT), the maximum tolerated dose (MTD), the recommended dose (RD), and the preliminary antitumor activity of S-1 and cisplatin plus paclitaxel for advanced gastric cancer. Methods: Paclitaxel was administered on day 1. A fixed dose of S-1 (70 mg/m2/day) was orally administered for 14 consecutive days from day 1, and a 24-h infusion of a fixed dose of cisplatin (60 mg/m2) was administered on day 14 of every 28-day cycle. Four dose escalation levels of paclitaxcel were studied (120, 140, 160, and 180 mg/m2). The DLT was defined as any of the following: grade 3 neutropenia lasting more than 5 days, grade 4 hematological toxicity, grade 3 non-hematological toxicity, or treatment delay of greater than 2 weeks as a result of toxicity. Results: Twenty patients were enrolled. Hematological and non- hematological toxicity of over grade 2 was not observed at dose level 1 and 2. Three patients started at dose level 3. One developed grade 3 neutropenia for 5 days following by grade 2 neutropenia lasted more than 10 days. Five more patients were added at this level. The treatment was delayed over 2 weeks in 1 out of 8 patients. Three patients started at dose level 4. One developed grade 3 neutropenia and needed longer than 14 days to recover. Three patients added this level. In total, at dose level 4 the treatment was delayed over 2 weeks in 3 out of 6 patients as a result of neutropenia. We considered level 4 is the MTD and the RD of paclitaxcel was 160 mg/m2 (dose level 3). The overall response rate was 75%. Conclusions: Triple combination chemotherapy consisting of S-1, cisplatin, and paclitaxel showed a tolerable dose of adverse reactions and favorable antitumor activity for gastric cancer. No significant financial relationships to disclose.