An Exploratory Study on the Use of Ivosidenib for the Precise Treatment of Advanced Biliary Tract Malignancies With IDH1 Mutations in the Later Line of Therapy.

Inclusion Criteria * Voluntary Participation: Signed informed consent. * Genetic Mutation: Presence of an IDH1 mutation confirmed by genetic testing. * Disease Status： * Newly diagnosed, untreated advanced/metastatic disease; OR * Recurrence \>6 months after curative-intent surgery (with or without adjuvant therapy). * Measurable Disease: At least one measurable lesion per RECIST 1.1. * Performance Status: ECOG performance status of 0 or 1. * Life Expectancy： ≥3 months. * Organ Function: Adequate hematological, hepatic, and renal function. * Contraception: Use of highly effective contraception for women of childbearing potential and men. Exclusion Criteria * Prior Treatment: Previous treatment with Ivosidenib. * Cancer Type: Ampulla of Vater cancer. * Pregnancy： Pregnant or breastfeeding women. * Allergy: Known hypersensitivity to any component of the study drugs. * Recent Therapy: Local anti-tumor therapy or major surgery within 4 weeks prior to initiation. * Medical Conditions: * Uncontrolled hypertension. * Significant cardiovascular disease. * Active or untreated CNS metastases. * Active autoimmune disease. * Uncontrolled active infection (e.g., HBV, HCV, HIV). * Significant bleeding tendency or history. * Severe non-healing wounds. * History of organ transplantation. * Concurrent Participation: Participation in another interventional clinical trial.