Adebrelimab Combined With Gemcitabine, Cisplatin, and Simvastatin for Advanced Biliary Tract Cancer

Inclusion Criteria: * Age ≥ 18 years. * Histologically confirmed unresectable, locally advanced, or metastatic biliary tract adenocarcinoma (including intrahepatic cholangiocarcinoma, extrahepatic cholangiocarcinoma, and gallbladder cancer). * No prior systemic therapy for advanced disease if initially diagnosed as unresectable or metastatic. Disease recurrence occurring more than 6 months after radical surgery or adjuvant therapy is allowed. * ECOG Performance Status of 0 or 1. * At least one radiologically measurable lesion as defined by RECIST 1.1 criteria (tumor lesion with longest diameter ≥10 mm on CT scan, or lymph node with short axis ≥15 mm). * No severe dysfunction of major organs (heart, lungs, brain, etc.). Exclusion Criteria: * Diagnosis of ampullary carcinoma. * Presence of active or previously documented autoimmune or inflammatory disorders. * Known hypersensitivity to any component of the study drugs (adebrelimab, gemcitabine, cisplatin, simvastatin). * Severe liver dysfunction: laboratory tests within 14 days prior to enrollment showing total bilirubin \> 1.5 times the upper limit of normal (ULN), AND/OR alanine aminotransferase (ALT) or aspartate aminotransferase (AST) \> 3 times ULN. * Participation in another investigational drug or device clinical trial within 4 weeks prior to enrollment. * Inability to comply with the study protocol for treatment or scheduled follow-up assessments. * Any other condition deemed by the investigator as unsuitable for participation in the study.