RC48 Combined With Adebrelimab, Apatinib and S-1 as Neoadjuvant Therapy in Locally Advanced Gastric Cancer

Inclusion Criteria: * 1\. Participants voluntarily join this study, are able to complete the signing of the informed consent form, and have good compliance; * 2\. Age between 18 to 75 years old (at the time of signing the informed consent form), with no gender restrictions; * 3\. Gastrointestinal cancer or gastroesophageal junction adenocarcinoma confirmed by histology and/or cytology, diagnosed as locally advanced according to the 8th edition of the AJCC standards, with a cTNM diagnosis of T3-4aN+M0 and T4aNanyM0 based on ultrasound endoscopy or enhanced CT/MRI scan (and diagnostic laparoscopy if necessary), and agree to receive curative surgical treatment, with the investigator assessing the potential for tumor resectability; * 4\. Have not previously received systemic treatment for the current disease, including anti-tumor chemotherapy/immunotherapy, etc.; * 5\. HER2 overexpression confirmed by IHC results from endoscopic biopsy tissue (defined as: IHC 2+, 3+); * 6\. ECOG score of 0-1; * 7\. Estimated life expectancy of ≥6 months; * 8\. Good major organ function: Exclusion Criteria: * 1\. Concurrent malignant disease other than gastric cancer (excluding early-stage tumors that have been radically treated); * 2\. Tumor lesions with a tendency to bleed (such as active ulcerative tumor lesions with positive fecal occult blood test, history of hematemesis or melena within 2 months before signing the informed consent form, or assessed by the investigator as being at risk of …