{"groups":[{"description":"Participants received 200 mg pembrolizumab intravenously (IV) every 3 weeks (Q3W) plus trastuzumab (8 mg/kg loading dose, 6 mg/kg maintenance thereafter) IV Q3W in combination with cisplatin plus 5-fluorouracil (FP) or capecitabine/oxaliplatin (CAPOX) chemotherapy. Eligible participants from the Global Cohort Pembrolizumab + Standard of Care who stopped initial course of pembrolizumab due to complete response (CR) or who had stable disease (SD), PR, or CR after completion of 35 cycles of pembrolizumab but progressed after discontinuation, initiated a second course of pembrolizumab at the investigator's discretion. Participants received 200 mg pembrolizumab IV every 3 weeks (Q3W) for up to 17 additional cycles (approximately 1 year additional treatment).","id":"FG000","title":"Global Pembrolizumab + Standard of Care First Course"},{"description":"Participants received matched placebo to pembrolizumab IV Q3W plus trastuzumab (8mg/kg loading dose, 6mg/kg maintenance thereafter) IV Q3W in combination with FP or CAPOX chemotherapy.","id":"FG001","title":"Global Standard of Care"},{"description":"Participants received 200 mg pembrolizumab IV every 3 weeks (Q3W) plus trastuzumab (8 mg/kg loading dose, 6 mg/kg maintenance thereafter) IV Q3W in combination with SOX chemotherapy.","id":"FG002","title":"Japan Pembrolizumab + Trastuzumab + S-1 Plus Oxaliplatin"},{"description":"Participants received matched placebo to pembrolizumab IV Q3W plus trastuzumab (8mg/kg loading dose, 6mg/kg maintenance thereafter) IV Q3W in combination with SOX chemotherapy.","id":"FG003","title":"Japan Trastuzumab + S-1 Plus Oxaliplatin"}],"periods":[{"dropWithdraws":[{"reasons":[{"groupId":"FG000","numSubjects":"266"},{"groupId":"FG001","numSubjects":"286"},{"groupId":"FG002","numSubjects":"14"},{"groupId":"FG003","numSubjects":"17"}],"type":"Death"},{"reasons":[{"groupId":"FG000","numSubjects":"0"},{"groupId":"FG001","numSubjects":"1"},{"groupId":"FG002","numSubjects":"0"},{"groupId":"FG003","numSubjects":"0"}],"type":"Lost to Follow-up"},{"reasons":[{"groupId":"FG000","numSubjects":"1"},{"groupId":"FG001","numSubjects":"3"},{"groupId":"FG002","numSubjects":"0"},{"groupId":"FG003","numSubjects":"0"}],"type":"Withdrawal by Subject"},{"reasons":[{"groupId":"FG000","numSubjects":"83"},{"groupId":"FG001","numSubjects":"58"},{"groupId":"FG002","numSubjects":"6"},{"groupId":"FG003","numSubjects":"3"}],"type":"Participants Ongoing"}],"milestones":[{"achievements":[{"groupId":"FG000","numSubjects":"350"},{"groupId":"FG001","numSubjects":"348"},{"groupId":"FG002","numSubjects":"20"},{"groupId":"FG003","numSubjects":"20"}],"type":"STARTED"},{"achievements":[{"groupId":"FG000","numSubjects":"350"},{"groupId":"FG001","numSubjects":"346"},{"groupId":"FG002","numSubjects":"20"},{"groupId":"FG003","numSubjects":"20"}],"type":"Treated"},{"achievements":[{"groupId":"FG000","numSubjects":"11"},{"groupId":"FG001","numSubjects":"0"},{"groupId":"FG002","numSubjects":"0"},{"groupId":"FG003","numSubjects":"0"}],"type":"Received Second Course of Pembrolizumab"},{"achievements":[{"groupId":"FG000","numSubjects":"0"},{"groupId":"FG001","numSubjects":"0"},{"groupId":"FG002","numSubjects":"0"},{"groupId":"FG003","numSubjects":"0"}],"type":"COMPLETED"},{"achievements":[{"groupId":"FG000","numSubjects":"350"},{"groupId":"FG001","numSubjects":"348"},{"groupId":"FG002","numSubjects":"20"},{"groupId":"FG003","numSubjects":"20"}],"type":"NOT COMPLETED"}],"title":"Overall Study"}],"preAssignmentDetails":"Per protocol, response or progression for participants in the Japan-specific SOX (S-1 plus oxaliplatin) Cohort and for participants in the second course of pembrolizumab were not counted towards efficacy analysis, and adverse events for participants during the second course of pembrolizumab were not counted towards safety analysis."}