A Phase III Clinical Study of Cadonilimab Plus SOX as Perioperative Treatment for Patients With Resectable G/GEJ Adenocarcinoma

Inclusion Criteria: 1. Patients with histologically confirmed gastric or gastroesophageal junction adenocarcinoma with resectable disease (clinical stage T3-4aN+M0 or T4bNanyM0 per AJCC 8th edition). 2. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 at enrollment. 3. Has life expectancy of at least 6 months. 4. Availability of tumor sample prior to study entry. 5. Patients must undergo radical surgery. 6. Has adequate organ function. Exclusion Criteria: 1. Patients with unresectable locally advanced disease or distant metastasis. 2. Histopathology or cytology confirmed other pathological types, such as adenosquamous cell carcinoma, squamous cell carcinoma, or GI stromal tumor. 3. Current or prior use of immunosuppressive medication within 14 days before randomization. 4. Has received prior anti-cancer therapy for the current malignancy. 5. Has an active infection requiring systemic therapy. 6. Contra-indication to any of the study drugs. 7. Has a known additional malignancy that is progressing or has required active treatment within the past 5 years. 8. Has an active autoimmune disease that has required systemic treatment in past 2 years. 9. Known active Hepatitis B or Hepatitis C virus infection. 10. Has had an allogenic tissue/solid organ transplant.