Adverse events

On Day 1 of each 21-day cycle, participants received an intravenous (IV) infusion of pembrolizumab 200 mg for up to 35 cycles (up to approximately 2 years) PLUS Investigator choice of chemotherapy for up to 6 cycles (paclitaxel 175 mg/m\^2 PLUS cisplatin 50 mg/m\^2 WITH or WITHOUT bevacizumab 15 mg/kg per local label OR paclitaxel 175 mg/m\^2 PLUS carboplatin Area Under the Curve (AUC) 5 for up to 6 cycles, WITH or WITHOUT bevacizumab 15 mg/kg per local label). All treatments were administered until disease progression or toxicity. Eligible participants who stopped the initial course of pembrolizumab with Stable Disease (SD) or better but progressed after discontinuation may have been able to initiate a second course of pembrolizumab for up to 17 cycles (up to approximately 1 additional year) at the investigator's discretion.

On Day 1 of each 21-day cycle, participants received an IV infusion of placebo (Normal Saline or Dextrose solution) for up to 35 cycles (up to approximately 2 years) PLUS Investigator choice of chemotherapy for up to 6 cycles (paclitaxel 175 mg/m\^2 PLUS cisplatin 50 mg/m\^2 WITH or WITHOUT bevacizumab 15 mg/kg per local label OR paclitaxel 175 mg/m\^2 PLUS carboplatin AUC 5 for up to 6 cycles, WITH or WITHOUT bevacizumab 15 mg/kg per local label). All treatments were administered until disease progression or toxicity.

Eligible participants received up to 17 additional administrations (up to approximately 1 year) of pembrolizumab 200 mg IV on Day 1 of each 21-day cycle.