Sequential Anti-Angiogenic Therapy After Immunotherapy in Advanced Biliary Tract Cancer

Brief Summary: This study is for patients with advanced biliary tract cancer (cancer of the bile ducts or gallbladder). The purpose is to find out if using anti-blood vessel formation drugs after immunotherapy treatment can help patients live longer without their cancer getting worse. What the study compares: Control group: Patients receive standard chemotherapy as first-line treatment, then chemotherapy plus anlotinib (an anti-blood vessel drug) if their cancer progresses Treatment group: Patients receive chemotherapy plus immunotherapy as first-line treatment, then the same second-line treatment as the control group if their cancer progresses Who can join: Patients aged 18-75 with advanced biliary tract cancer that has been confirmed by tissue testing, who have not received immunotherapy or anti-blood vessel drugs before, and who are in good enough health for treatment. What we want to learn: The main goal is to see if patients who received immunotherapy first have better outcomes when they later receive anti-blood vessel treatment. We will measure how long patients live without their cancer getting worse during second-line treatment. Study design: This is a randomized study, meaning patients are assigned by chance to one of the two treatment groups. About 60 patients will participate across multiple hospitals in China. We will also collect blood and tissue samples to better understand how these treatments work. The study will help doctors determine if this treatment sequence could become a new standard approach for patients with advanced biliary tract cancer.