Gastric cancer is one of the most common malignancies in China with incidence and mortality both ranking the 2nd among malignancies in China. Unfortunately, over 70% of gastric cancer patients in China were diagnosed in advanced stage, and more than 80% of adenocarcinoma of esophagogastric junction(AEG) were advanced stage. Locally advanced AEG (cT3-4aN+M0) could be cured by multi-disciplinary therapies including surgery, chemotherapy and radiotherapy. As proved, Neoadjuvant chemotherapy can downstage T and N stage, increase the resectability of tumor, and finally improve the long-term survival in AEG patients. However, the therapeutic effects remain unsatisfactory. PD-1 antibody has demonstrated its efficacy in metastatic AEG and has been proved to be effective in neoadjuvant setting in lung cancer and melanoma. Combination of perioperative PD-1 antibody and chemotherapy for locally advanced could be a novel therapy to increase response rate and resectability and reduce recurrence rate. Sinitilimab in this study is an anti-PD-1 monoclonal antibody for injection which has been approved for lymphoma. This study is a multi-center, open-label, randomized phase II clinical trial to evaluate tolerability, safety and efficacy of sinitilimab in combination with perioperative chemotherapy（SOX: oxaliplatin plus S-1） in locally advanced AEG.
For locally advanced adenocarcinoma of esophagogastric junction(AEG) (cT3-4aN+M0), neoadjuvant chemotherapy was improved to downstage T and N stage, increase the resectability of tumor, and finally improve the long-term survival. Combination of perioperative PD-1 antibody and chemotherapy for locally advanced AEG could be a novel therapy to increase response rate and resectability and reduce recurrence rate. Sintilimab in this study is an anti-PD-1 monoclonal antibody for injection which has been approved for several malignant tumors. This study is a multi-center, open-label, randomized phase II clinical trial to evaluate tolerability, safety and efficacy of sintilimab in combination with perioperative chemotherapy in locally advanced AEG.