Continuation of Serplulimab Plus Chemotherapy After First Progression in Advanced Gastric or Gastro-oesophageal Junction Adenocarcinoma: an Open-label, Randomised Phase II Trial

This study is conducted in patients with advanced metastatic gastric cancer including gastroesophageal junction cancer(patients with HER2 negative and PD-L1 CPS≥5).Patiens will recevie Serplulimab plus chemotherapy ((oxaliplatin+capecitabine) as first-line treatment. After PD，patients will randomly 2：1 assigned to treatment：one group will receive Serpluimab with Paclitaxel,Apatinib；another group will receive Paclitaxel with or without Ramucirumab.All of eligible patients will receive study drug treatment until loss of clinical benefit, unacceptable toxicity, death, withdrawal of informed consent