Cadonilimab Plus Regorafenib and Gem-Cis Chemotherapy in Advanced Biliary Tract Cancer

Main Inclusion Criteria: 1. subjects with a histopathological or cytologically diagnosis of BTC 2. The participants must be required to sign an informed consent 3. At least one measurable lesion (RECIST 1.1) 4. No previous systematic treatment for BTC 5. Child-Pugh Score, Class A 6. ECOG performance status 0 or 1 7. Adequate organ function 8. Life expectancy of at least 3 months Exclusion Criteria: 1. Diagnosis of mixed ampullary, hepatocellular and cholangiocarcinoma 2. Known history of serious allergy to any monoclonal antibody 3. Known central nervous system metastases and/or leptomeningeal disease prior to treatment 4. Portal hypertension with esophageal or gastric varices within 6 months prior to initiation of treatment 5. Any bleeding or thrombotic disorder within 6 months prior to initiation of treatment 6. Any active malignancy prior to the start of treatment 7. Active or history of autoimmune disease 8. Other acute or chronic conditions, psychiatric disorders, or laboratory abnormalities that may increase the risk of study participation 9. Pregnant or lactating women