Exploratory Clinical Study of Penpulimab Combined With SOX in the Perioperative Treatment of Gastric Cancer

Inclusion Criteria:

* signed and dated informed consent;
* At least 18 years of age;
* ECOG PS: 0-1;
* Patients with gastric cancer diagnosed as T3-4NXMX by imaging;
* Patients with gastric adenocarcinoma diagnosed by cytology;
* Patients with gastric cancer assessed by the surgeon as suitable for neoadjuvant therapy or conversion therapy followed by radical resection;
* Laboratory tests should meet the following requirements (28 days before enrollment in baseline period) :
* Women should agree that they must use contraception during and for 6 months after the study; Had a negative serum pregnancy test within 7 days prior to study enrollment and had to be non-lactating; Men should agree that they must use contraception during the study and for 6 months after the end of the study period.

Exclusion Criteria:

* Co-existing with other malignant tumors (except cured basal cell carcinoma of the skin);
* Gastric cancer patients with T1-2N0M0;
* Previous treatment including anti-PD-1 /PD-L1/CTLA-4 antibody therapy or other immunotherapy directed against PD-1/PD-L1/CTLA-4;
* Weight loss greater than or equal to 20% within 4 weeks before the first dose;
* Severe hypersensitivity after administration of other monoclonal antibodies;
* The presence or history of any active autoimmune disease
* Immunosuppressive therapy, systemic or absorbable local hormone therapy (dose \> 10mg/ day prednisone or other effective hormone) is required to achieve immunosuppression and continues to be used within 2 weeks of the first administration;
* Patients with multiple factors affecting oral medication
* Uncontrolled pleural effusion, pericardial effusion, or ascites that require repeated drainage;
* Had received a prophylactic or attenuated vaccine within 4 weeks before the first dose;