Neoadjuvant Iparomlimab and Tuvonralimab With Nab-P-SOX in Locally Advanced Gastric or Gastroesophageal Junction Cancer

Inclusion Criteria: * Age 18-75 years * Histologically confirmed gastric or gastroesophageal junction adenocarcinoma, clinical stage cT3-4aN+M0 * Resectable disease, as determined by the surgical investigator * No prior radiotherapy, chemotherapy, or other systemic antitumor therapy * HER-2 negative * ECOG performance status 0-1 * Life expectancy greater than 6 months * Adequate organ function: hemoglobin \>= 90 g/L; absolute neutrophil count \>= 1.5 x 10\^9/L; platelet count \>= 100 x 10\^9/L; serum creatinine \<= 1.5 x ULN; ALT/AST \<= 2.5 x ULN; total bilirubin \<= 1.5 x ULN; amylase/lipase \< 1.5 x ULN; INR/APTT \<= 1.5 x ULN; urine protein \< 2+; LVEF \>= 50% * Women of childbearing potential must be non-pregnant, non-lactating, and agree to use adequate contraception * Provision of written informed consent and anticipated good compliance Exclusion Criteria: * Known allergy or hypersensitivity to the investigational drug(s) or excipients * History of other prior antitumor therapy * Therapeutic full-dose anticoagulation or thrombolysis within 10 days prior to first dose * Requirement for systemic corticosteroids or immunosuppressive therapy within 2 weeks prior to first dose * Active autoimmune disease or autoimmune disease with high risk of relapse * Within 6 months: gastrointestinal perforation, fistula, or obstruction; Crohn's disease or ulcerative colitis; or extensive intestinal resection * Symptomatic and uncontrolled brain or leptomeningeal metastases * History of interstitial lung disease/pneumonitis or pulmonary hypertension * History of organ transplantation * Uncontrolled hypertension (\>150/100 mmHg), diabetes mellitus, or cardiac arrhythmia * Arterial or venous thrombotic/embolic event within 6 months * Within 12 months: myocardial infarction, unstable angina, or NYHA class III/IV heart failure * Drainage of ascites, pleural effusion, or pericardial effusion within 4 weeks prior to enrollment * Non-healing wound, active ulcer, or untreated fracture * Other active malignancy * Active HIV, HBV, or HCV infection * Major surgery within 4 weeks prior to first dose * Any condition that, in the investigator's judgment renders the patient unsuitable for study participation