A Study of BL-B01D1 Plus an Anti-PD-1 Antibody Versus Nab-paclitaxel Plus an Anti-PD-1 Antibody in Patients With Previously Untreated, Locally Advanced, Inoperable or Metastatic Triple-Negative Breast Cancer Whose Tumors Express PD-L1 (PANKU-Breast04)

This trial is a registrational Phase III, randomized, open-label, multicenter study designed to compare the efficacy and safety of BL-B01D1 in combination with a PD-1 monoclonal antibody versus nab-paclitaxel in combination with a PD-1 monoclonal antibody in patients with PD-L1-positive, previously untreated, inoperable locally advanced or recurrent metastatic triple-negative breast cancer.

Inclusion Criteria: 1. Voluntarily sign the informed consent form and agree to comply with the protocol requirements; 2. Female patients aged 18 to 75 years; 3. Expected survival time ≥ 3 months; 4. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1; 5. Pathologically confirmed recurrent or metastatic triple-negative breast cancer; 6. Confirmed PD-L1 expression positivity by central laboratory testing; 7. No prior systemic anti-tumor therapy in the advanced/recurrent or metastatic setting; 8. Agree to provide archived tumor tissue specimens (surgical specimens) or fresh tissue samples from primary or metastatic lesions obtained within 3 years; 9. Must have at least one measurable lesion as defined by RECIST v1.1; 10. Toxicities from prior anti-tumor therapy must have recovered to ≤ Grade 1 as defined by NCI-CTCAE v6.0; 11. No severe cardiac dysfunction, with left ventricular ejection fraction (LVEF) ≥ 50%; 12. Organ function levels must meet the protocol-specified requirements; 13. Urine protein ≤ 1+ or \< 1000 mg/24 h; 14. For premenopausal women of childbearing potential, a pregnancy test (serum) must be performed within 7 days before starting treatment, and pregnancy must be ruled out; patients must not be lactating. All enrolled patients (regardless of sex) must use adequate barrier contraception throughout the entire treatment period and for 7 months after the end of treatment. Exclusion Criteria: 1. Received surgery, radical radiotherapy, or immunotherapy within 4 weeks before the first dose; 2. Prior exposure to ADC drugs with topoisomerase I inhibitor payload; 3. Prior treatment with other T-cell receptor-targeting agents (excluding PD-1/PD-L1); 4. Use of immunomodulators within 14 days before the first study drug dose; 5. History of severe cardiac or cerebrovascular disease; 6. Receiving chronic systemic corticosteroids at \>10 mg/day prednisone before the first dose; 7. Active autoimmune or inflammatory disease; 8. Any thrombotic event within 6 months before randomization; 9. Prolonged QTc, complete left bundle branch block, or similar; 10. Active malignancy diagnosed within 3 years before randomization; 11. Hypertension uncontrolled by two antihypertensives; 12. Poorly controlled diabetes/hyperglycemia; 13. History of steroid-treated ILD/interstitial pneumonitis; 14. Concurrent lung disease causing clinically significant respiratory impairment; 15. Active CNS metastases; 16. Severe infection within 4 weeks before randomization; 17. Massive or symptomatic serosal effusion; 18. Severe non-healing wound, ulcer, or fracture within 4 weeks before consent; 19. Clinically significant bleeding or bleeding tendency within 4 weeks before consent; 20. Inflammatory bowel disease, extensive bowel resection, immune enteritis, bowel obstruction, or chronic diarrhea; 21. Allergy or contraindication to the study drug; 22. History of autologous/allogeneic stem cell transplantation; 23. HIV antibody positive, active HBV, or active HCV; 24. History of severe neurological or psychiatric illness; 25. Received or planning to receive live vaccine within 28 days before randomization; 26. Other conditions rendering the patient unsuitable per investigator's judgment.