Envafolimab With Chemotherapy and Simvastatin in Advanced Biliary Tract Cancer

"Envafolimab (generic name):~Dose: 300 mg, intravenous (IV) infusion. Schedule: Day 1 of each 21-day cycle (induction phase); every 28 days (maintenance phase).~Role: PD-L1 inhibitor immunotherapy.~Gemcitabine (generic name):~Dose: 1,000 mg/m², IV infusion. Schedule: Days 1 and 8 of each 21-day cycle (induction phase only).~Cisplatin (generic name):~Dose: 25 mg/m², IV infusion. Schedule: Days 1 and 8 of each 21-day cycle (induction phase only).~Simvastatin (generic name):~Dose: 40 mg, oral tablet. Schedule: Daily (continuously through induction and maintenance phases). Investigational Role: Potential immunomodulator and chemosensitizer in biliary tract cancer.~Treatment Phases:~Induction Phase (Cycles 1-8, 21-day cycles): All four drugs administered. Maintenance Phase (Post-Cycle 8): Envafolimab + Simvastatin only (28-day cycles)."