A Study of BL-B01D1+PD-1/PD-L1 Monoclonal Antibody in Patients With Advanced Biliary Tract Cancer

Inclusion Criteria: 1. Sign the informed consent form voluntarily and follow the protocol requirements; 2. Gender is not limited; 3. Age ≥18 years old and ≤75 years old; 4. Expected survival time ≥3 months; 5. Patients with advanced biliary tract cancer confirmed by histology or cytology; 6. Patients must provide a documented tumor tissue specimen of the primary or metastatic tumor within 3 years for PD-L1 testing and other testing; 7. At least one measurable lesion meeting the RECIST v1.1 definition was required; 8. ECOG score 0-1; 9. The toxicity of previous antineoplastic therapy has returned to ≤ grade 1 as defined by NCI-CTCAE v5.0; 10. No severe cardiac dysfunction, left ventricular ejection fraction ≥50%; 11. Organ function level must meet the requirements; 12. Coagulation function: international normalized ratio (INR) ≤1.5×ULN, and activated partial thromboplastin time (APTT) ≤1.5×ULN; 13. Urinary protein ≤2+ or ≤1000mg/24h; 14. For premenopausal women of childbearing potential, a pregnancy test must be performed within 7 days before starting treatment, a serum or urine pregnancy test must be negative, and the patient must not be lactating; All enrolled patients should take adequate barrier contraception during the entire treatment cycle and for 6 months after the end of treatment. Exclusion Criteria: 1. Patients with active central nervous system metastases; 2. Who had participated in any other clinical trial within 4 weeks before the trial dose; 3. Received anti-tumor therapy such as chemotherapy, radiotherapy and biological therapy within 4 weeks before the first use of study drug; 4. Had undergone major surgery (investigator-defined) within 4 weeks before the first dose; 5. Had received immunotherapy and developed grade ≥3 irAE or grade ≥2 immune-related myocarditis; 6. Use of immunomodulatory drugs within 14 days before the first dose of study drug; 7. Systemic corticosteroids or immunosuppressive agents were required within 2 weeks before the study administration; 8. Pulmonary disease grade ≥3 according to NCI-CTCAE v5.0; A history of ILD/pulmonary inflammation requiring steroid treatment; 9. Severe systemic infection occurred within 4 weeks before screening; 10. Patients at risk for active autoimmune disease or with a history of autoimmune disease; 11. Other malignant tumors within 5 years before the first dose; 12. Human immunodeficiency virus antibody positive, active tuberculosis, active hepatitis B virus infection or hepatitis C virus infection; 13. Poorly controlled hypertension by two antihypertensive drugs with different mechanisms; 14. Diabetic patients with poor glycemic control; 15. Had a history of severe cardiovascular and cerebrovascular diseases; 16. Previous history of autologous or allogeneic stem cell, bone marrow or organ transplantation; 17. Subjects with clinically significant bleeding or significant bleeding tendency within the preceding 4 weeks were screened; 18. Patients with massive or symptomatic effusions or poorly controlled effusions; 19. Imaging examination showed that the tumor had invaded or wrapped around the chest, neck, pharynx and other large arteries or invaded the pericardium and heart; 20. Unstable thrombotic events requiring therapeutic intervention within 6 months before screening; 21. Prior treatment with an ADC drug with a topoisomerase I inhibitor as a toxin; 22. Patients with a history of allergy to recombinant humanized antibodies or to any of the excipients of the trial drug; 23. The cumulative dose of anthracyclines \> 360 mg/m2 in previous (new) adjuvant therapy; 24. Pregnant or lactating women; 25. Who have a history of psychotropic drug abuse and cannot quit or have mental disorders; 26. The investigator did not consider it appropriate to apply other criteria for participation in the trial.