Efficacy and Safety of Perioperative Chemotherapy Plus PD-1 Antibody in Gastric Cancer

Inclusion Criteria:

1. Written (signed) informed consent.
2. Age ≥ 18 years and ≤70 years.
3. ECOG Performance status 0-1.
4. Has previously untreated localized gastric or gastroesophageal junction adenocarcinoma as defined by T3 or greater primary lesion or the presence of any positive nodes - N+ (clinical nodes) without evidence of metastatic disease.
5. Patients who plan surgery after neoadjuvant chemotherapy based on clinical staging criteria.
6. Consent to send tumor tissue from biopsy or resection for PD-L1 detection and PD-L1 CPS≥1;
7. Expected survival ≥6 months;
8. Females of child bearing age must have a negative pregnancy test
9. 1）Platelet (PLT) ≥100×109/L; 2) Neutrophil count (ANC)≥1.5×l09/L; 3) Hemoglobin (Hb) level ≥9.0 g/dl; 4）WBC≥3.5×l09/L; 5) International normalized ratio (INR) ≤1.5; 5) Prothrombin time (PT) ,International Normalized Ratio（INR）and activated partial thromboplastin time (APTT) ≤1.5×ULN; 6）Total bilirubin (TBIL) level ≤1.5×ULN（patients with gilbert syndrome≤3×ULN）; 7) Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) level ≤2.5×ULN ; 10) Serum creatinine (Cr) level ≤1.5×ULN and creatinine clearance ≥60 ml/min;

Exclusion Criteria:

1. Patients with pathologically confirmed gastric squamous cell carcinoma, adenosquamous carcinoma, small cell carcinoma, and undifferentiated gastric cancer.
2. patients who have HER2 positive confiemed with IHC3+ or IHC2+ and FISH positive.
3. Patients with a history of t Anticancer or Experimental Therapy(Including chemotherapy, radiotherapy, hormone therapy and molecular targeted therapy)
4. The patient's cardia or pylorus is nearly obstructed, affecting eating and gastric emptying
5. Immunotherapy with previous anti-PD-1, anti-PD-L1, anti-PD-L2, anti-CD137 or anti-CTLA-4 antibodies or any other antibody or drug that targets T-cell co-stimulation or immune checkpoint pathways
6. Patients have experienced or currently has other malignancies within 5 years.Except for the cured cervical carcinoma in situ,Non-melanoma skin cancer, Other tumors or cancers that have been treated radically and have shown no signs of disease for at least 5 years.
7. Peripheral neuropathy ≥ level 2（according to CTCAE 5.0）
8. Patient currently has CNS or cancerous meningitis.
9. Patients are allergic to study medication and its ingredients
10. Patients have hereditary bleeding or coagulopathy at risk of bleeding
11. Patient underwent major surgery within 4 weeks
12. Patients have taken Chinese herbal medicine or proprietary Chinese medicine for cancer treatment within two weeks
13. Patients have not recovered from complications of previous surgery.According to the CTCAE 5.0, it has not been reduced below level 1(In addition to hair loss and fatigue)
14. Patients require immunosuppressive drugs within 2 weeks or less or during the study.Exclude the following:

    A) Use of intranasal, inhaled or topical steroid(For example, intra - articular injection) B) physiological dose of steroid ( Prednisone less than 10mg per day or use equivalent dose) C) Short-term(no more than 7 day) use of steroids to prevent or treat non-autoimmune allergic diseases
15. Patients have an active or history of autoimmune disease that may recur
16. Patients have a history of interstitial lung disease or non-infectious pneumonia
17. Patients have a history of active tuberculosis
18. Patients have a history of HIV infection or other acquired, congenital immunodeficiency disease , organ transplant or stem cell transplant
19. Hepatitis B or C virus virological tests meet any of the following:

    A) HBsAg positive ,HBV-DNA≥150 copies/mL or ≥2000IU/mL B) HCV antibody positive and HCV-RNA is above the detection limit of the analysis method
20. Within 2 weeks or 2 weeks before randomization,Patients have an active or uncontrollable infection that requires systemic treatment
21. Patient vaccinated with live virus within 4 weeks
22. Patients have uncontrollable pleural effusion, pericardial effusion, or ascites requiring repeated drainage or treatment.
23. Patients have gastrointestinal perforation or fistula within 6 months and significant clinically significant gastrointestinal bleeding before 3 months of randomization
24. Patient have intestinal obstruction, inflammatory bowel disease, extensive bowel resection, Crohn's disease, ulcerative colitis or chronic diarrhea
25. Patients have serious internal medicine diseases
26. Women who are pregnant, breast-feeding or planning to become pregnant during treatment or within 6 months after treatment ends.
27. Patients are unwilling to receive effective contraception during treatment and within 6 months after treatment ends
28. The investigator believes that the subject is not suitable for the study