Dose-finding study of docetaxel, oxaliplatin, and S-1 for patients with advanced gastric cancer

To determine the maximum tolerated dose (MTD), recommended dose (RD), and activity of combined docetaxel, oxaliplatin, and S-1 (DOS) chemotherapy on metastatic gastric cancer.

Docetaxel and oxaliplatin were administered intravenously on day 1 and S-1 was administered orally on days 1-14 of every 21-day cycle. The doses of docetaxel/oxaliplatin/S-1 in the phase I study were level -1A, 52.5/80/60 mg/m(2); level -1B, 52.5/80/80 mg/m(2); level 1A, 52.5/105/80 mg/m(2); level 1B, 52.5/130/80 mg/m(2); level 2A, 60/105/80 mg/m(2); level 2B, 60/130/80 mg/m(2); level 3A, 67.5/105/80 mg/m(2); level 3B, 67.5/130/80 mg/m(2); level 4A, 75/105/80 mg/m(2); level 4B, 75/130/80 mg/m(2).

Nine patients were enrolled. One of six patients at level 1A and two of three patients at level 1B developed dose-limiting toxicity (febrile neutropenia) during the initial two cycles. Therefore, the doses used at levels 1B and 1A were defined as the MTD and RD, respectively. All patients were evaluated for toxicity and response. Six partial responses were noted, and the overall response rate was 67%.

The RD of the DOS regimen in patients with advanced gastric cancer was docetaxel 52.5 mg/m(2) and oxaliplatin 105 mg/m(2) on day 1 and S-1 80 mg/m(2) on days 1-14 of every 21-day cycle. A phase II study using the RD is currently underway.