Short Course Radiotherapy With Sequential Disitamab Vedotin Combined With S-1 and Sintilimab as Whole Course Neoadjuvant Therapy for HER2 Expressed Locally Progressive Gastric Cancer

Who cannot join

• -1. Diagnosed as malignant diseases other than gastric cancer within 5 years prior to initial administration (excluding curative basal cell carcinoma, squamous cell carcinoma of the skin, and/or curative resection of carcinoma in situ) 2. The tumor lesion has a tendency for bleeding (such as the presence of active ulcer tumor lesions with positive fecal occult blood test, history of vomiting blood or black stools within 2 months before signing the informed consent form, and a risk of gastrointestinal bleeding determined by the researcher), or having received blood transfusion treatment 4 weeks before the study medication; 3. Unable to take medication orally; 4. Currently participating in intervention clinical research treatment, or having received other research drugs or used research instruments within 4 weeks before the first administration; 5. Previously received the following therapies: anti-HER2, anti-PD-1, anti-PD-L1 drugs, anti-PD-L2 drugs, or drugs targeting another stimulus or synergistic inhibition of T cell receptors (including but not limited to CTLA-4, OX-40, CD137, etc.); 6. Have received systematic systemic treatment with traditional Chinese patent medicines and simple preparations with anti-tumor indications or drugs with immunomodulatory effect (including thymosin, interferon, interleukin, except for local use to control pleural effusion) within 2 weeks before the first administration; 7. Active autoimmune diseases that require systemic treatment (such as the use of disease relieving drugs, glucocorticoids, or immunosuppressants) have occurred within 2 years prior to the first administration. Alternative therapies (such as thyroid hormone, insulin, or physiological glucocorticoids used for adrenal or pituitary insufficiency) are not considered systemic treatments; 8. The study is currently undergoing systemic glucocorticoid therapy (excluding local glucocorticoids through nasal spray, inhalation, or other routes) or any other form of immunosuppressive therapy within 7 days prior to the first administration; Note: Physiological doses of glucocorticoids (≤ 10 mg/day of prednisone or equivalent) are allowed to be used; 9. Known allogeneic organ transplantation (excluding corneal transplantation) or allogeneic hematopoietic stem cell transplantation; 10. Known individuals who are allergic to the drugs used in this study; 11. Peripheral neuropathy ≥ grade 2; 12. Known history of human immunodeficiency virus (HIV) infection (i.e. HIV 1/2 antibody positive); 13. Active hepatitis B or hepatitis C subjects (HBsAg positive with HBV DNA titers higher than the upper limit of normal; HCVAb positive with HCV RNA titers higher than the upper limit of normal); 14. Have received a live vaccine within 30 days before the first administration (1st cycle, 1st day); Note: It is allowed to receive inactivated viral vaccines for seasonal influenza within 30 days before the first administration; However, it is not allowed to receive attenuated live influenza vaccines administered intranasally.
• 15. Pregnant or lactating women; 16. Existence of any serious or uncontrollable systemic diseases 17. Medical history or evidence of illness that may interfere with the trial results, hinder the full participation of subjects in the study, abnormal treatment or laboratory test values, or other situations that the researcher deems unsuitable for enrollment. The researcher believes that there are other potential risks that are not suitable for participation in this study.