The purpose of this clinical trial is to evaluate the safety and effectiveness of a new combination therapy for patients with biliary tract cancer that cannot be removed by surgery. Participants will receive an immunotherapy drug called adebrelimab combined with two chemotherapy drugs (gemcitabine and albumin-bound paclitaxel) as their first-line treatment. This is an open-label, single-arm study, meaning all enrolled patients will receive this same combination treatment. The main goal of the study is to determine the Objective Response Rate (ORR), which measures the proportion of patients whose tumors shrink in response to the treatment. Researchers will also evaluate how long patients live without the disease getting worse (Progression-Free Survival), overall survival, quality of life, and any side effects experienced. The study plans to enroll 30 participants.

Inclusion Criteria:

• Age 18 to 75 years, male or female. Eastern Cooperative Oncology Group (ECOG) performance status score of 0 or 1. No prior local or systemic treatment for biliary tract malignancy. Histologically or cytologically confirmed initially unresectable or inoperable biliary tract cancer; recurrent biliary tract tumor after surgery; or patients who received post-operative adjuvant therapy must have been off treatment for more than 6 months. Adequate organ and hematological function. Life expectancy of ≥ 3 months. Laboratory results within 7 days prior to the first dose meeting the following criteria:Absolute neutrophil count (ANC) ≥ 1.5 × 10^9/L, Platelets ≥ 75 × 10^9/L, Hemoglobin ≥ 90 g/L (without blood transfusion or G-CSF within 2 weeks prior to screening); Serum albumin ≥ 30 g/L, Total bilirubin ≤ 1.5 × ULN, ALT and AST ≤ 3 × ULN, Serum creatinine ≤ 1.5 × ULN or Creatinine clearance > 50 mL/min; INR ≤ 1.2 or PT exceeding the normal control range by ≤ 2 seconds; Urine protein < 2+ (if ≥ 2+, 24-hour urine protein quantification must be < 1.0 g). Women of childbearing potential must agree to abstain from sexual intercourse or use a reliable and effective method of contraception from the time of signing the informed consent form until at least 120 days after the last dose of the study drug. Women of childbearing potential must have a negative serum pregnancy test within 72 hours prior to the first dose and must not be lactating. Male subjects with female partners of childbearing potential must agree to abstain from sexual intercourse or use a reliable and effective method of contraception from the time of signing the informed consent form until at least 120 days after the last dose of the study drug, and must not donate sperm during this period.

Exclusion Criteria:

• Pathological diagnosis of mixed hepatocellular carcinoma or containing other non-cholangiocarcinoma malignant components. Prior systemic therapy. History of or concurrent other malignancies, except for adequately treated non-melanoma skin cancer, carcinoma in situ of the cervix, and papillary thyroid cancer. Active pulmonary tuberculosis infection within 1 year prior to enrollment; or history of active tuberculosis infection over 1 year ago without formal anti-tuberculosis treatment or with tuberculosis still in the active phase. History of autoimmune diseases or immunodeficiency, including but not limited to myasthenia gravis, myositis, autoimmune hepatitis, systemic lupus erythematosus, rheumatoid arthritis, inflammatory bowel disease, antiphospholipid syndrome, Wegener's granulomatosis, Sjögren's syndrome, Guillain-Barré syndrome, or multiple sclerosis. Requiring long-term systemic corticosteroid therapy (dose equivalent to > 10 mg/day prednisone) or any other form of immunosuppressive therapy. Subjects using inhaled or topical corticosteroids are allowed. Severe cardiopulmonary or renal dysfunction. Uncontrolled arterial hypertension (systolic blood pressure ≥ 140 mmHg or diastolic blood pressure ≥ 90 mmHg); history of hypertensive crisis or hypertensive encephalopathy. HBV DNA > 2000 IU/ml, or active HCV infection (HCV antibody positive and HCV-RNA level above the lower limit of detection). Active infection requiring systemic therapy. Human immunodeficiency virus (HIV 1/2 antibody) positive. History of psychotropic drug abuse, alcoholism, or drug addiction. History of allergy to study drugs. Other factors that, in the judgment of the investigator, may affect the safety of the subject or compliance with the trial