Study rationale, objectives, design, methods, and statistical considerations of an ongoing phase III study comparing S-1 alone versus the S-1/docetaxel combination are reviewed. This study is a prospective, multicenter, multinational, nonblinded, randomized, phase III study of subjects with advanced gastric cancer. Subjects are to be randomly assigned to 3-week cycles of Treatment Arm A (docetaxel and S-1) or 6-week cycles of Treatment Arm B (S-1 only). The primary objective of the study is to compare median overall survival of the test arm (docetaxel and S-1) to the control arm (S-1 only) in subjects with advanced or recurrent gastric cancer. The secondary objectives of the study are to assess the time-to-tumor progression (TTP), defined as time from randomization to date of first documentation of progressive disease (PD), to determine the clinical response (RR), defined as the sum of complete response (CR) and partial response (PR) according to Response Evaluation Criteria in Solid Tumors (RECIST), and to evaluate the safety of the two regimens. A total of 628 subjects (314 in each treatment arm) will be enrolled. Subject enrollment began in September 2005 and lasts approximately 3 years. We have already enrolled 556 patients (88.5%: Japan, 346 cases; Korea, 210 cases) from 103 centers (Japan, 86 centers; Korea, 17 centers) between December 2005 and February 2008. We are expecting full enrollment at the end of August 2008. The JACCRO GC-03 study is now ongoing. After 2 years follow-up from full enrollment, in 2010 we will report the final results of this study.
Trial registration: ClinicalTrials.gov NCT00287768.