This study is a phase II clinical study to explore the efficacy and safety of BL-B01D1 + PD-1 combination therapy in patients with locally advanced or metastatic urothelial carcinoma.

Inclusion Criteria:

1. All subjects voluntarily participated in the study and signed informed consent;
2. Male or female aged ≥18 years and ≤75 years;
3. Expected survival time ≥3 months;
4. ECOG 0-1;
5. Unresectable locally advanced or metastatic urothelial carcinoma confirmed by histopathology and/or cytology;
6. Participants should not have received previous systemic therapy for locally advanced or metastatic urothelial cancer;
7. A biopsy sample of archived tumor tissue or metastatic urothelial carcinoma must be available within 3 years for PD-L1 and other testing;
8. At least one measurable lesion meeting the RECIST v1.1 definition was required;
9. The level of organ function must meet the requirements on the premise that blood transfusion and the use of any cell growth factors and/or platelet-raising drugs are not allowed within 14 days before the first dose;
10. Previous treatment-related toxicity returned to ≤ grade 1 defined by NCI-CTCAE v5.0;
11. For premenopausal women with childbearing potential, a pregnancy test must be performed within 7 days before the initiation of treatment, the 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. Prior ADC recipients with TOPI inhibitors as toxin;
2. Palliative radiotherapy within 2 weeks before the first dose;
3. Prior immunotherapy with grade ≥3 irAE or grade ≥2 immune-related myocarditis;
4. Use of an immunomodulatory drug within 14 days before the first dose of study drug;
5. The history of severe cardiovascular and cerebrovascular diseases in the past six months was screened;
6. QT prolongation, complete left bundle branch block, III degree atrioventricular block, frequent and uncontrollable arrhythmia;
7. Active autoimmune and inflammatory diseases;
8. Receiving &gt before the first dose; Long-term systemic corticosteroid therapy with prednisone 10mg/d;
9. Other malignant tumors that progressed or required treatment within 5 years before the first dose;
10. Presence of: a) poorly controlled diabetes mellitus before starting study treatment; b) severe complications associated with diabetes mellitus; c) a glycated hemoglobin level of 8% or more; d) hypertension poorly controlled by two antihypertensive drugs; e) history of hypertensive crisis or hypertensive encephalopathy;
11. History of ILD, current ILD, or suspected ILD;
12. Complicated with pulmonary diseases leading to clinically severe respiratory impairment;
13. Screening for unstable thrombotic events requiring therapeutic intervention within the preceding 6 months; Infusion-related thrombosis was excluded;
14. Patients with active central nervous system metastases;
15. Patients with massive or symptomatic effusions or poorly controlled effusions;
16. Patients with a history of allergy to recombinant humanized antibody or human-mouse chimeric antibody or allergic to any excipients of the test drug;
17. Prior organ transplantation or allogeneic hematopoietic stem cell transplantation (Allo-HSCT);
18. HIV antibody positive, active tuberculosis, active hepatitis B virus infection, or active hepatitis C virus infection;
19. Serious infection within 4 weeks before the first dose of study drug; Signs of pulmonary infection or active pulmonary inflammation within 4 weeks;
20. Participated in another clinical trial within 4 weeks before the first dose;
21. Patients with superior vena cava syndrome should not be rehydrated;
22. Have a history of psychotropic substance abuse with an inability to quit or a history of severe neurological or psychiatric illness;
23. Imaging examination showed that the tumor had invaded or wrapped the large thoracic vessels;
24. Severe unhealed wound, ulcer, or fracture within 4 weeks before signing the informed consent;
25. Subjects with clinically significant bleeding or obvious bleeding tendency within 4 weeks before signing the informed consent;
26. Subjects who are scheduled to receive live vaccine or receive live vaccine within 28 days before the first dose;
27. Other circumstances considered by the investigator to be inappropriate for participation in the trial.