First-line Esophageal Carcinoma Study With Pembrolizumab Plus Chemo vs. Chemo (MK-3475-590/KEYNOTE-590)

The purpose of this trial is to evaluate efficacy and safety of pembrolizumab plus standard of care (SOC) chemotherapy with cisplatin and 5-fluorouracil (5-FU) versus placebo plus SOC chemotherapy with cisplatin and 5-FU as first-line treatment in participants with locally advanced or metastatic esophageal carcinoma. The overall primary efficacy hypotheses are as follows: 1. In participants with esophageal squamous cell carcinoma (ESCC), participants whose tumors are programmed cell death-ligand 1 (PD-L1)-positive (defined as combined positive score \[CPS\] ≥10), ESCC participants whose tumors are PD-L1 positive (CPS ≥10), and in all participants, overall survival (OS) is superior with pembrolizumab plus SOC chemotherapy compared with placebo plus SOC chemotherapy. 2. In participants with ESCC, participants whose tumors are PD-L1 positive (CPS ≥10), and in all participants, progression-free survival (PFS) according to Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 as assessed by investigator is superior with pembrolizumab plus SOC chemotherapy compared with placebo plus SOC chemotherapy.