Cadonilimab Combination Regimen as First-line Treatment for HER2-expressing GC/GEJ Patients

Inclusion criteria

• ✓.Sign the informed consent form. 2. ≥18 years and ≤75 years . 3.Histologically confirmed unresectable locally advanced or metastatic gastric or gastroesophageal junction adenocarcinoma (tumor center located within 5 cm proximally or distally from the esophagogastric junction according to the Siewert classification system).
• ✓.Confirmed PD-L1 expression status (accepts PD-L1 expression test results confirmed by the investigator).
• ✓.HER2 expression (accepts HER2 expression test results confirmed by the investigator):
• ✓.No prior systemic anti-tumor therapy. 7.With at least one measurable lesion (RECIST 1.1 criteria) in the subject . 8.Expected survival ≥ 3 months. 9.ECOG 0/1. 10.Adequate organ function is determined by the following criteria:
• ✓. Hematological (no transfusions or growth factor support allowed within 7 days before the first dose):Absolute neutrophil count (ANC) ≥ 1.5 × 10\^9/L (1,500/mm³); Platelet count ≥ 100 × 10\^9/L (100,000/mm³);Hemoglobin ≥ 90 g/L or ≥ 5.6 mmol/L.
• ✓. Liver:Serum albumin ≥ 28 g/L (no albumin infusions allowed within 14 days before the first dose);Total bilirubin (TBil) ≤ 1.5 × ULN; for subjects with liver metastases or evidence/suspicion of Gilbert's disease, TBil ≤ 3 × ULN; Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤ 2.5 × ULN; for subjects with liver metastases, AST and ALT ≤ 5 × ULN.
• ✓. Renal:Serum creatinine ≤ 1.5 × ULN or calculated creatinine clearance (CrCl) ≥ 50 mL/min (calculated using the Cockcroft-Gault formula);Urinalysis: urine protein \< 2+; if urine protein ≥ 2+, then 24-hour urine protein ≤ 1 g.
• ✓. Coagulation:International normalized ratio (INR) ≤ 1.5 × ULNActivated partial thromboplastin time (aPTT) ≤ 1.5 × ULN;Prothrombin time (PT) ≤ 1.5 × ULN.

Exclusion criteria