A Single-arm, Multicenter, Exploratory Study of Adebrelimab Combined With Apatinib and Systemic Chemotherapy for Initially Unresectable Biliary Tract Cancer

1. Patients who received immune checkpoint inhibitors before enrollment, or those who directly received another stimulatory or co-inhibitory T-cell receptor (such as CTLA-4, CD137); 2. Patients who used any other investigational drug within 4 weeks before enrollment; 3. Patients with any active autoimmune disease or history of autoimmune disease (such as interstitial pneumonia, uveitis, enteritis, hepatitis, pituitary inflammation, vasculitis, myocarditis, nephritis, hyperthyroidism, hypothyroidism after hormone replacement therapy); children with asthma who have completely recovered after adulthood and do not require any intervention can be included, but patients requiring bronchodilator drug intervention cannot be included; 4. Congenital or acquired immune deficiencies, such as infection with human immunodeficiency virus (HIV), active hepatitis B (HBV DNA > 500 IU/ml), hepatitis C (positive hepatitis C antibody, HCV-RNA above the detection limit of the analytical method), or co-infection of hepatitis B and hepatitis C; 5. Serious infections occurred within 4 weeks before the first administration (such as intravenous infusion of antibiotics, antifungal or antiviral drugs), or unexplained fever > 38.5°C during screening or before the first administration; 6. History of allogeneic organ transplantation or allogeneic hematopoietic stem cell transplantation; 7. Having an uncontrolled mental disorder; 8. Concurrently having severe and/or uncontrollable diseases that may affect the participation in the study, such as unstable angina pectoris, myocardial infarction within 6 months, unstable symptomatic arrhythmia, symptomatic congestive heart failure, poorly controlled diabetes, excessive activity, uncontrollable infection after insufficient biliary drainage (such as tumor blocking the bile duct); 9. Other cancers that occurred in the past (within the past 5 years) or simultaneously, excluding non-melanoma skin cancer and carcinoma in situ; 10. History of allergy or hypersensitivity to any study drug or any monoclonal antibody; 11. Unable or unwilling to sign the informed consent form.