Efficacy and Safety of Lenvatinib (E7080/MK-7902) Plus Pembrolizumab (MK-3475) Plus Chemotherapy in Participants With Advanced/Metastatic Gastroesophageal Adenocarcinoma (MK-7902-015/E7080-G000-321/LEAP-015)

Exclusion Criteria

• •Has had previous therapy for locally advanced unresectable or metastatic gastric/gastroesophageal junction (GEJ) esophageal adenocarcinoma
• •Has had major surgery within 28 days prior to first dose of study interventions
• •Has had radiotherapy within 14 days of randomization
• •Has a known additional malignancy that is progressing or has required active treatment within the past 5 years
• •Has known central nervous system (CNS) metastases and/or carcinomatous meningitis
• •Has severe hypersensitivity (≥Grade 3) to treatment with an monoclonal antibody (mAb) or known sensitivity or intolerance to any component of lenvatinib, pembrolizumab, study chemotherapy agents and/or to any excipients, murine proteins, or platinum containing products
• •Has had an allogeneic tissue/solid organ transplant
• •Has perforation risks or significant gastrointestinal (GI) bleeding
• •Has GI obstruction, poor oral intake (CAPOX participants), or difficulty in taking oral medication (CAPOX participants)
• •Has received prior therapy with an anti-programmed cell death 1 (PD-1), anti-PD-L1, or anti-PD-L2 agent or with an agent directed to another stimulatory or coinhibitory T-cell receptor
• •Has received prior therapy with anti- vascular endothelial growth factor (VEGF) tyrosine kinase inhibitor or anti-VEGF mAb
• •Has received a live or live-attenuated vaccine within 30 days before the first dose of study drug
• •Has an active autoimmune disease that has required systemic treatment in past 2 years (i.e., with use of disease modifying agents, corticosteroids or immunosuppressive drugs)
• •Has radiographic evidence of encasement or invasion of a major blood vessel, or of intratumoral cavitation
• •Has inadequate cardiac function
• •Has a history of (noninfectious) pneumonitis/interstitial lung disease that required steroids or has current pneumonitis/interstitial lung disease
• •Has poorly controlled diarrhea
• •Has accumulation of pleural, ascitic, or pericardial fluid requiring drainage or diuretic drugs within 2 weeks prior to enrollment
• •Has peripheral neuropathy ≥Grade 2
• •Has a known history of human immunodeficiency virus (HIV) or HIV 1/2 antibodies
• •Has a known history of hepatitis B (defined as HBsAg reactive) or known active hepatitis C virus (defined as HCV ribonucleic acid (RNA) \[qualitative\] is detected) infection
• •Has weight loss of \>20% within the last 3 months