A Multicenter, Randomized, Controlled Study of S-1 Combined With Oxaliplatin by Arterial Infusion Plus PD-1 Antibody Versus Conventional SOX Chemotherapy Plus PD-1 Antibody for Locally Advanced Gastric Cancer
SOX regimen, consisting of oral S-1 and intravenous oxaliplatin, is the preferred regimen for perioperative chemotherapy for gastric cancer. The goal of this clinical trial is to compare the efficacy and safety between S-1 combined with oxaliplatin by arterial infusion, as neoadjuvant chemotherapy, and conventional SOX regimen, in locally advanced gastric cancer. The main question it aims to answer is: whether arterially infused oxaliplatin plus S-1 has the potential to be a better neoadjuvant option for patients with locally advanced gastric cancer. Participants will be randomised, and receive: * 3 cycles of conventional SOX chemotherapy plus PD-1 antibody or arterial infused oxaliplatin plus S-1 and PD-1 antibody, as neoadjuvant chemotherapy; * Adequate gastric resection along with D2 lymph node dissection; * 3 cycles adjuvant chemotherapy using SOX regimen plus PD-1 antibody. * Administration of S-1 regularly till 1 year after surgery. Researchers will compare Major pathological response rate (MPR) ，pathologic complete response rate（pCR）,the 2-year overall survival (OS) rates, 2-year disease free survival (DFS), R0 resection rates, and adverse events, to see if the modified perioperative chemotherapy improve the prognosis of patients with locally advanced gastric cancer.
• Eastern Cooperative Oncology Group(ECOG) score 0-1
• Ambulatory males or females, aged 18-75 years
• Histologically or cytologically confirmed adenocarcinoma of the stomach or gastroesophageal junction (Siewert type II or III)
• Locally advanced gastric carcinoma (cT3N2-3M0, cT4aN1-3M0, cT4bNanyM0, American Joint Committee on Cancer (AJCC) TNM staging system 8th edition)
• Life expectancy more than 3 months
• Give written informed consent, with the understanding that the patient has the right to withdraw from the study at any time, without prejudice.
• Normal hepatic, renal, and bone marrow function (ALT/AST\<2.5 fold of upper limit value;Tbil\<1.5mg/dl, Cr\<1.5 fold of upper limit value; White Blood Cell count≥3 × 10\^9/L, ANC ≥ 1.5 × 10\^9/L,PLT≥ 80 × 10\^9/L,Hb ≥ 90 g/L).