A Study Comparing BL-B01D1 With Chemotherapy of Physician's Choice in Patients With Unresectable Locally Advanced or Metastatic Triple-Negative Breast Cancer

Inclusion Criteria: 1. Voluntarily sign the informed consent and follow the requirements of the protocol; 2. No gender limit; 3. Age ≥18 years old and ≤75 years old; 4. Expected survival time ≥3 months; 5. Patients with unresectable, locally advanced or metastatic triple-negative breast cancer; 6. Consent to provide archival tumor tissue samples or fresh tissue samples of primary or metastatic lesions within 3 years; 7. The subjects had received 1-2 lines of chemotherapy regimens in the locally advanced or metastatic stage, and had been treated with taxanes previously; 8. Acceptability of chemotherapy with eribulin, capecitabine, gemcitabine, or vinorelbine, as assessed by the investigator; 9. Patients with baseline brain metastases should have received treatment for all brain metastases and be stable; 10. Must have at least one measurable lesion that meets the RECIST v1.1 definition; 11. ECOG score 0 or 1; 12. Toxicity of previous antineoplastic therapy has returned to ≤ grade 1 defined by NCI-CTCAE v5.0; 13. No severe cardiac dysfunction, left ventricular ejection fraction ≥50%; 14. No blood transfusion, no use of cell growth factors and/or platelet raising drugs within 14 days before the first use of the study drug, and the organ function level must meet the requirements; 15. Coagulation function: international normalized ratio ≤1.5, and activated partial thromboplastin time ≤1.5×ULN; 16. Urine protein ≤2+ or \< 1000mg/24h; 17. For premenopausal women with childbearing potential, a pregnancy test must be performed within 7 days before the initiation of treatment, serum pregnancy must be negative, and must be non-lactating; All enrolled patients (male or female) were advised to use adequate barrier contraception throughout the treatment cycle and for 6 months after the end of treatment. Exclusion Criteria: 1. Prior receipt of an ADC with a TOPI inhibitor as a toxin; 2. Prior receipt of an ADC or antibody drug targeting EGFR and/or HER3; 3. Chemotherapy, biological therapy, immunotherapy, etc. within 4 weeks or 5 half-lives before the first dose, small molecule targeted therapy within 5 days, palliative radiotherapy and anti-tumor therapy within 2 weeks; 4. Anthracycline equivalent cumulative dose of adriamycin \> 360 mg/m2; 5. History of severe cardiovascular or cerebrovascular disease; 6. Unstable thrombotic events requiring therapeutic intervention within 6 months before screening; 7. QT prolongation, complete left bundle branch block, III degree atrioventricular block, frequent and uncontrollable arrhythmia; 8. Active malignancy diagnosed within 5 years before randomization; 9. Hypertension poorly controlled by two antihypertensive drugs; 10. Patients with poor blood glucose control before the first dose; 11. A history of interstitial lung disease requiring steroid therapy, or current radiation pneumonitis, or a suspicion of such disease; 12. Complicated with pulmonary diseases leading to clinically severe respiratory impairment; 13. Patients with carcinomatous meningitis (meningeal metastasis) or brain stem metastasis or spinal cord compression; 14. Have a history of allergy to recombinant humanized antibodies or any of the ingredients of BL-B01D1; 15. A history of autologous or allogeneic stem cell transplantation; 16. Human immunodeficiency virus antibody positive, active hepatitis B virus infection, or hepatitis C virus infection; 17. Severe infection within 4 weeks before randomization; Evidence of pulmonary infection or active pulmonary inflammation within 2 weeks before randomization; 18. Patients with massive or symptomatic effusions or poorly controlled effusions; 19. Imaging examination showed that the tumor had invaded or enveloped the large blood vessels in the abdomen, chest, neck, and pharynx; 20. Were receiving long-term systemic corticosteroids or equivalent active anti-inflammatory drugs or any form of immunosuppressive therapy before randomization; 21. Received other unmarketed investigational drug or treatment within 4 weeks before the first dose; 22. Patients with superior vena cava syndrome should not be rehydrated; 23. A history of severe neurological or mental illness; 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. History of intestinal obstruction, inflammatory bowel disease, or extensive bowel resection or presence of Crohn's disease, ulcerative colitis, or chronic diarrhea; 27. Patients scheduled for vaccination or receiving live vaccine within 28 days before the first dose; 28. Other circumstances that were assessed by the investigator as inappropriate for participation in the trial.