Clinical Efficacy of Adebrelimab With or Without Apatinib Mesilate and SOX Neoadjuvant Therapy in Locally Advanced Gastric Cancer

Inclusion criteria

\*\*Inclusion Criteria\*\* 1. Age 18-75 years (inclusive). 2. Histologically or cytologically confirmed unresectable, locally advanced or metastatic HER2-negative adenocarcinoma of the stomach or gastro-oesophageal junction (GEJ). 3\. No prior systemic chemotherapy, radiotherapy, targeted therapy, or immunotherapy for advanced disease. Subjects who have received prior (neo)adjuvant chemotherapy and/or radiotherapy are eligible provided the last dose was completed ≥ 6 months before randomisation. 4\. At least one measurable lesion per RECIST 1.1 (see Appendix 2). 5. Eastern Cooperative Oncology Group performance status (ECOG PS) 0-1 (see Appendix 4). 6\. Estimated life expectancy \> 3 months. 7. Adequate major organ function defined as: 1. Haematology (obtained ≤ 14 days without transfusion): 1. Hb ≥ 80 g/L 2. WBC ≥ 3 × 10⁹/L 3. ANC ≥ 1.5 × 10⁹/L 4. PLT ≥ 100 × 10⁹/L 2. Biochemistry: 1. Total bilirubin \< 1.5 × upper limit of normal (ULN) 2. ALT and AST \< 2.5 × ULN; ALP ≤ 1.5 × ULN 3. Serum creatinine ≤ 1 × ULN and calculated creatinine clearance ≥ 60 mL/min (Cockcroft-Gault formula) 8. Women of child-bearing potential must have a negative serum pregnancy test within 7 days prior to enrolment and must use highly effective contraception from screening until 8 weeks after the last dose of study drug. Men must be surgically sterile or agree to use effective contraception during the same period. 9\. No participation in any other interventional clinical trial during the pre-treatment or on-treatment phases of this study. 10\. Voluntary written informed consent obtained; willing and able to comply with study procedures and follow-up.