This is a Prospective, Single-center, Single-arm, phase II clinical trial to explore the efficacy and safety of sintilimab (PD1 inhibitor) combined with XELOX chemotherapy, evaluate the pathological complete response rate of short-course radiotherapy combined with sintilimab and XELOX chemotherapy in neoadjuvant therapy for locally advanced gastric adenocarcinoma.
All individuals recruited signed a written informed consent;
Aged between 18 and 75 years;
Histologically confirmed gastric adenocarcinoma, and Stage III (cT3-4aN1-3 M0, American Joint Committee on Cancer (AJCC) TNM staging system 8th edition) gastric cawas confirmed by enhanced CT/MRI scan (endoscopic ultrasonography (EUS) and laparoscopic exploration if necessary), and the lesion was resectable;
No previous systemic therapy, including including surgery, radiotherapy, chemotherapy and immunotherapy, etc；
Other malignancy disease history within five years, with the exception of basal cell carcinoma or squamous carcinoma of skin, and carcinoma in situ that have undergone radical resection;
Endoscopic signs of active bleeding in the lesion;
Is participating in an interventional clinical study or has received another study drug or used a study device within 4 weeks before the first study drug administration;
Prior treatment with an anti-PD-1, anti-PD-L1 or anti-PD-L2 agent or with an agent directed to another stimulatory or coinhibitory T-cell receptor (e.g. CTLA-4, OX40, CD137) drugs;