• histologically documented adenocarcinoma of Gastric or Gastroesophageal Junction. 2. clinically diagnosed stage T3-4aN+M0 according to ultrasound endoscopy or enhanced CT/MRI scan. 3. Male or female. Age ≥ 18 years and ≤75 years. 4. surgeons participating in this study consider the lesion a resectable one. 5. ECOG 0\

⁃ 1 6. Physical condition and adequate organ function to ensure the success of abdominal surgery. 7. Adequate hematological function: Neutrophil count ≥ 1.5 × 109/L, Platelets ≥ 100 × 109/L and Hemoglobin ≥90g/L. 8. Adequate liver function: Total bilirubin ≤ 1.5 × upper limit of normal (ULN); AST (SGOT) and ALT (SGPT) \< 2.5 × ULN . ALP ≤ 2.5 × upper limit of normal (ULN); ALB ≥30g/L. 9. Adequate renal function: Serum creatinine ≤ 1.5 x ULN, and creatinine clearance ≥ 60 ml/min. 10. Adequate coagulation function: INR/PT≤ 1.5 x ULN, aPTT≤ 1.5 x ULN. 11. No serious concomitant disease that will threaten the survival of patients to less than 5 years. 12. Written (signed) informed consent. 13. Good compliance with the study procedures, including lab and auxiliary examination and treatment. 14. Female patients should not be pregnant or breast feeding. 15. PD-L1 assessment