The purpose of this study is to evaluate the efficacy of pembrolizumab (MK-3745) in combination with chemotherapy (Cisplatin combined with 5-Fluorouracil \[FP regimen\] or oxaliplatin combined with capecitabine \[CAPOX regimen\]) versus placebo in combination with chemotherapy (FP or CAPOX regimens) in the treatment of human epidermal growth factor receptor 2 (HER2) negative advanced gastric or GEJ adenocarcinoma in adult participants. The primary hypotheses of this study are that pembrolizumab plus chemotherapy is superior to placebo plus chemotherapy in terms of overall survival (OS). Once a participant has achieved the study objective or the study has ended, the participant will be discontinued from this study and enrolled in an extension study (Keynote 587; NCT03486873) to continue protocol-defined assessments and treatment.
Administered as an IV infusion on Day 1 Q3W
Administered as an IV infusion on Day 1 Q3W
Administered as a continuous IV infusion on Days 1-5 Q3W
Administered as an IV infusion on Day 1 Q3W
Administered orally BID on Days 1 to 14 Q3W
Administered as an IV infusion on Day 1 Q3W
Buenos Aires, Buenos Aires F.D., Argentina
Buenos Aires, Argentina
Buenos Aires, Argentina
La Rioja, Argentina
San Juan, Argentina