Study protocol of a phase II clinical trial (KSCC1501A) examining oxaliplatin + S-1 for treatment of HER2-negative advanced/recurrent gastric cancer previously untreated with chemotherapy

Background: Oxaliplatin + S-1 is a recognized treatment regimen in Japan, but there are no Japanese clinical data on an oxaliplatin dose of 130mg/m². The current research involves a single-arm, prospective, phase II clinical trial to examine the efficacy and safety of oxaliplatin + S-1 with an oxaliplatin dose of 130mg/m² to treat HER2-negative advanced/recurrent gastric cancer previously untreated with chemotherapy in Japan. Methods/design: The primary endpoint of this trial will be the response rate, and the secondary endpoints will be the safety profile of oxaliplatin + S-1, progression-free survival, the response rate in subjects under the age of 75, overall survival, time to treatment failure, duration of treatment, time to failure of strategy, and dose intensity. The threshold response rate is 45% and the expected response rate is 60%. Assuming that a one-tailed score test will be performed with an α of 0.05, 68 patients are needed to ensure a statistical power of 80%. Planned enrollment is 70 subjects and the total duration of this trial is expected to be 3years. Discussion: Since replacing cisplatin with oxaliplatin should provide the same level of therapeutic efficacy while limiting adverse events and simplifying treatment, oxaliplatin + S-1 may be increasingly used to treat gastric cancer in Japan. Verifying the efficacy and safety of oxaliplatin + S-1 with an oxaliplatin dose of 130mg is an important task that the current trial has set out to achieve. Trial registration: The protocol was registered at the website of the University Hospital Medical Information Network (UMIN), Japan (protocol ID UMIN000017550) on May 29, 2015. The details are available at the following web address: http://www.umin.ac.jp/ctr/.