Efficacy and Safety of Neoadjuvant Sintilimab Plus FLOT Versus Sintilimab Plus SOX Phase II Clinical Trial for Patients With Locally Advanced Gastric Cancer

Inclusion Criteria:

* 1\. Age \>=18 years and \<100 years.
* 2\. Diagnosed with locally advanced gastric cancer.
* 3\. Eastern Cooperative Oncology Group ECOG PS score 0-1.
* 4\. adoption of preoperative chemotherapy treatment and PD-1 antibody therapy.
* 5\. deficient mismatch repair identified by pathological detection.

Exclusion Criteria:

* 1\. Locally advanced unable to resect or metastatic tumors.
* 2\. Patients with recurrence of residual gastric cancer
* 3\. Patients refusing surgical resection after preoperative chemotherapy therapy.
* 4\. Have received any anti-tumor therapy such as chemotherapy, radiotherapy, immunotherapy, etc., or have been more than 180 days since the last treatment.
* 5\. Patients with confirmed allergy to the study drug and/or its excipients.
* 6\. Severe malnutrition and active autoimmune diseases.
* 7\. Pregnant or lactating women.
* 8\. Patients with medical systemic diseases and psychiatric diseases that are not amenable to chemotherapy.
* 9\. Patients with acute infections requiring antibiotic treatment.
* 10\. Patients with acute infections requiring antibiotic treatment.
* 11\. Patients who are concomitantly receiving other immunotherapy, corticosteroids, and other anticancer therapies during the trial.
* 12\. Positive test result for hepatitis B or hepatitis C virus.
* 13\. Untreated central nervous system metastatic peripheral neuropathy (\>grade 1).
* 14\. History of malignancy within the past 5 years (with the exception of curative, localized cancer).
* 15\. Patients who are not expected to achieve R0 resection.
* 16\. Weight loss greater than or equal to 20% within 4 weeks before the first dose.
* 17\. Patients with multiple factors affecting oral medication.
* 18\. Vaccination within 4 weeks prior to the first dose of study drug.
* 19\. Patients who have received immune checkpoint inhibitors and develop serious adverse reactions after treatment and need to be permanently disabled.
* 20\. The investigator believes that the subject has other serious systemic diseases or other reasons and is not suitable for this clinical study.