Safety and Efficacy of Gemcitabine, Toripalimab and Dose- Modified Lenvatinib in Elderly Patients With Advanced Biliary Tract Cancer Intolerant to Conventional Chemotherapy

The goal of this clinical trial is to learn if the regimen of gemcitabine, toripalimab and dose-modified lenvatinib works to treat advanced biliary tract cancer in elderly patients with intolerance to conventional chemotherapy. It will also learn about the safety of the regimen. The main questions it aims to answer are: * Does this regimen control the tumors in participants with advanced biliary tract cancer? * What medical problems do participants have when taking this regimen? Participants will: Take lenvatinib capsules every day, gemcitabine on days 1 and 8, and toripalimab on day 1 every 3 weeks; Visit the clinic regularly for follow-ups, imaging scans, and lab tests.

Inclusion Criteria: 1. Age ≥ 65 years at the time of informed consent, male or female; 2. ECOG performance status (PS) score of 0 or 1; 3. Expected survival ≥ 12 weeks; 4. Histologically or cytologically confirmed locally advanced or recurrent/metastatic advanced biliary tract malignancy (BTC), including intrahepatic cholangiocarcinoma (iCCA), extrahepatic cholangiocarcinoma (eCCA), and gallbladder carcinoma (GBC) by a complete pathology report from a qualified/accredited institution; 5. Participants are not candidates for surgical resection, ablation, or similar local therapies; 6. Cancer and Aging Research Group (CARG) chemotherapy risk score \< 10; 7. No prior systemic anti-tumor therapy for the study disease; 8. Participants must provide sufficient tumor samples (within 6 months) from the primary or metastatic lesionbefore the first study dose for exploratory biomarker testing; 9. At least one measurable lesion according to RECIST v1.1; 10. Have adequate laboratory parameters and organ functions during the screening period. Exclusion Criteria: 1. Prior anti-tumor therapy before the first study dose; 2. Participation in another clinical study within 4 weeks before the first study dose; 3. Ampullary carcinoma or other pathological types of malignancy besides the study disease, other malignancies, CNS metastases, transplant history, prior antitumor local therapy, recent participation in other clinical studies or major surgery, or unresolved toxicity from prior therapy. 4. Participants with severe comorbidities, immunodeficiency, autoimmune disease, uncontrolled infection, bleeding or thrombotic risks, or other risk factors that may affect the study results or lead to forced termination of the study early as judged by investigators.