Immune Checkpoint Inhibitor PD-1 Antibody Combined With Chemotherapy in the Perioperative Treatment of Locally Advanced Resectable Gastric or Gastroesophageal Junction Adenocarcinoma

Inclusion criteria

• At least 18 years of age, 75 years of age or less, no gender limitation;
• Patients with untreated locally advanced resectable adenocarcinoma of the stomach or gastroesophageal junction, with clear pathological diagnosis;
• According to RECIST 1.1, the efficacy evaluation standard for solid tumors, there were definite measurable and evaluable lesions, with spiral CT lesions ≥1cm；
• Physical condition score KPS score 80-100 points ；
• Able to receive systemic chemotherapy;
• No obvious active bleeding;
• No history of other malignancies, except cured carcinoma in situ of the cervix, basal carcinoma of the skin or squamous cell carcinoma;
• Women of childbearing age had negative pregnancy test and had voluntarily taken effective and reliable contraceptive measures during the clinical trial；
• Sign the informed consent form voluntarily；

Exclusion criteria

• There are distant metastasis or local invasion of adjacent organs；
• Tumor recurrence;
• Suffered from or had previously suffered from autoimmune diseases;
• Past organ transplantation or HIV patients;
• Allergic to 5-fluorouracil, calcium leucoin, oxaliplatin, or irinotecan, or contraindications to 5-fluorouracil, calcium leucoin, oxaliplatin, or irinotecan exist;
• Malignant secondary disease dating back to 5 years (exceptions: carcinoma in situ of the cervix, adequately treated basal cell carcinoma of the skin)；
• Severe non-surgical complications or acute infections；
• Peripheral polyneuropathy>NCI Grad I；
• Impaired blood system, liver and kidney function. The evaluation criteria are as follows:

Blood routine: white blood cells (WBC) <3.0×109/L, neutrophils (ANC) <1.5×109/L, platelets (PLT) <100×109/L, hemoglobin (Hb) <90g/L.

Liver and kidney function: total bilirubin (TBIL)>1.5 times the upper limit of the normal value; urea nitrogen (BUN)>1.5 times the upper limit of the normal value；Creatinine (Cr)>1.5 times the upper limit of the normal value；Alanine aminotransferase and aspartate aminotransferase (ALT and AST)> 3 times the upper limit of the normal value (without liver metastasis)；Alanine aminotransferase and aspartate aminotransferase (ALT and AST)> 5 times the upper limit of the normal value (for liver metastases)；

• Subjects with symptomatic brain metastases;
• Subjects with obvious clinical manifestations of arrhythmia, myocardial ischemia, severe atrioventricular block, cardiac insufficiency, and severe valvular disease;
• Subjects with severe bone marrow failure;
• Psychotic subjects who are difficult to control；
• Pregnant or lactating subjects;
• Subjects whom the investigator considers inappropriate to participate in this trial；
• Include in another clinical trial；