The study was designed to evaluate the efficacy and safety of HRS-4642 monotherapy or in combination with adebrelimab in the treatment of advanced biliary tract tumor patients.

Inclusion Criteria:

1. 18-75 years old, male or female.
2. Histologically or cytologically confirmed diagnosis of advanced biliary tract cancer.
3. Unresectable or metastatic advanced patients with progression or intolerance for ≥ one line of systemic therapy, including patients who metastasize during or within 6 months after neoadjuvant or adjuvant therapy (adjuvant therapy or neoadjuvant therapy must include gemcitabine-based chemotherapy).
4. Have at least one measurable lesion according to the Response Evaluation Criteria in Solid Tumors (RECIST v1.1).
5. ECOG performance status of 0-1.
6. With a life expectancy of ≥3 months.
7. Have adequate laboratory parameters and organ functions during the screening period.

Exclusion Criteria:

1. Known history of hypersensitivity to any components of HRS-4642 or adebrelimab.
2. Prior anti-tumor chemotherapy within 4 weeks before the study drug administration. Small molecular targeted drugs (including oral targeted drugs for other clinical trials) with a half-life of less than 5 or 7 days from the first medication.
3. Patients with untreated or active central nervous system tumor metastasis.
4. Other factors that may affect the study results or lead to forced termination of the study early as judged by investigators.