This study focused on the longitudinal tumor burden profile (tumor macro features, histopathological types and imaging features, etc.), liver function, health status, tumor biomarkers, and serological indicators of patients with unresectable biliary malignancies before chemotherapy combined with immunotherapy to build a dynamic prediction model. Based on this model, risk stratification of BTC patients was realized to explore which specific populations could safely initiate combination therapy. By constructing a risk stratification model, it can help clinicians to screen the best treatment population and provide a basis for safe treatment of high-risk patients.

Inclusion Criteria:

• 1. Confirmed by histopathological diagnosis and/or clinical diagnosis (typical imaging features, clinical manifestations, laboratory examination, etc.) as biliary malignancy (Chinese Society of Clinical Oncology (CSCO) Guidelines for Diagnosis and Treatment of Biliary malignancy (2024)); 2. Based on unresectable malignant tumor in the diagnosis of biliary and in patients undergoing chemotherapy with immunosuppressant therapy system; 3. The liver function class for Child - Pugh, A or B; 4. More than 18 years of age, gender not limited; 5. Expected survival time for 3 months or more; 6. ECOG PS score 2 or less; 7. Meet the following laboratory test parameters:

  1. Hematological system function: Absolute neutrophil count ≥ 1.0×10⁹/L; platelet count ≥ 50×10⁹/L; hemoglobin ≥ 90 g/L; international normalized ratio less than 1.7 or prothrombin time prolongation not exceeding 4 seconds.
  2. Liver function: Alanine aminotransferase/aspartate aminotransferase not exceeding 5 times the upper limit of normal; total bilirubin ≤ 210 μmol/L [≤ 2.38 mg/dL]; albumin ≥ 28 g/L.
  3. Renal function: Serum creatinine not exceeding 1.5 times the upper limit of normal.

Exclusion Criteria:

• Malignant tumors other than BTC;
• Moderate to severe ascites (ascites reaching a Child-Pugh score of 3);
• Any local treatment (including transcatheter interventional therapy, ablation therapy, internal/external radiotherapy, etc.) or surgical resection or traditional Chinese medicine within 4 weeks before the combination of systemic chemotherapy and immunotherapy;
• Incomplete data, such as incomplete laboratory test data, missing or poor-quality imaging data, or lack of prognostic information;
• Severe liver dysfunction, such as decompensated cirrhosis and other liver diseases that significantly affect bilirubin levels;
• Severe comorbidities, such as refractory hypertension (blood pressure still higher than 150/100 mm Hg after optimal drug treatment), persistent arrhythmia (CTCAE grade 2 or above), any degree of atrial fibrillation, prolonged QTc interval (more than 450 milliseconds in men and more than 470 milliseconds in women), renal insufficiency, etc.;
• Human immunodeficiency virus (HIV) infection or acquired immune deficiency syndrome;
• Pregnant or lactating women;
• Acute or chronic mental disorders (including mental disorders that affect the subject's enrollment, treatment intervention, and follow-up).

The target population of this project is patients diagnosed with unresectable biliary malignancies and treated with systemic chemotherapy combined with immunosuppressive agents.