A Study of AK104 in the First-line Treatment of Locally Advanced Unresectable or Metastatic G/GEJ Adenocarcinoma

AK104 (administered on Day 1 of each cycle, Q3W)+Oxaliplatin (130 mg/m2 intravenous infusion for 2-6 hours on Day 1, Q3W,up to 6 cycles)+ Capecitabine(1000 mg/m2, p.o., Bid, Q3W,up to 6 cycles) . Afterward, AK104 will be used for maintenance treatment (administered on Day 1 of each cycle, Q3W)

Placebo (administered on Day 1 of each cycle, Q3W)+Oxaliplatin (130 mg/m2 intravenous infusion for 2-6 hours on Day 1, Q3W,up to 6 cycles)+ Capecitabine(1000 mg/m2, p.o., Bid, Q3W,up to 6 cycles) . Afterward,Placebo will be used for maintenance treatment (administered on Day 1 of each cycle, Q3W)