KEYNOTE-062: This phase III trial is using pembrolizumab (an immunotherapy agent) as a first line treatment for people with advanced gastric and gastro-oesophageal adenocarcinomaA Randomized, Active-Controlled, Partially Blinded, Biomarker Select, Phase III Clinical Trial of Pembrolizumab as Monotherapy and in Combination With Cisplatin+5-Fluorouracil Versus Placebo+Cisplatin+5-Fluorouracil as First-Line Treatment in Subjects With Advanced Gastric or Gastroesophageal Junction (GEJ) Adenocarcinoma

Exclusion

• Squamous cell or undifferentiated gastric cancer
• Previous therapy for locally advanced, unresectable or metastatic gastric/GEJ cancer. Participant may have received prior neoadjuvant or adjuvant therapy as long as it was completed at least 6 months prior to randomization
• Major surgery, open biopsy or significant traumatic injury within 28 days prior to randomization, or anticipation of the need for major surgery during the course of study treatment.
• Radiotherapy within 14 days of randomization
• Known additional malignancy that is progressing or requires active treatment with the exception of basal cell carcinoma of the skin, squamous cell carcinoma of the skin that has undergone potentially curative therapy or in situ cervical cancer
• Known active central nervous system (CNS) metastases and/or carcinomatous meningitis
• Active autoimmune disease that has required systemic treatment in past 2 years
• Diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy (in dosing exceeding 10 mg daily of prednisone equivalent) or any other form of immunosuppressive therapy within 7 days prior the first dose of study medication
• History of non-infectious pneumonitis that required steroids or current pneumonitis
• Active infection requiring systemic therapy
• Pregnant, breastfeeding, or expecting to conceive or father children within the projected duration of the trial, starting with the screening visit through 120 days after the last dose of study medication
• Prior therapy with an anti-programmed cell death (PD)-1, anti-PD-L1, or anti-PD-L2 agent
• Known history of human immunodeficiency virus (HIV)
• Known active Hepatitis B or C
• Currently participating in and receiving study therapy or has participated in a study of an investigational agent or has used an investigational device within 4 weeks prior to the first dose of study medication
• Received a live vaccine within 30 days prior to the first dose of study medication