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 breastcancer;

6. Consent to provide archival tumor tissue samples or fresh tissue samples of primaryor metastatic lesions within 3 years;

7. The subjects had received 1-2 lines of chemotherapy regimens in the locally advancedor metastatic stage, and had been treated with taxanes previously;

8. Acceptability of chemotherapy with eribulin, capecitabine, gemcitabine, orvinorelbine, as assessed by the investigator;

9. Patients with baseline brain metastases should have received treatment for all brainmetastases 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 byNCI-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 drugswithin 14 days before the first use of the study drug, and the organ function levelmust meet the requirements;

15. Coagulation function: international normalized ratio ≤1.5, and activated partialthromboplastin time ≤1.5×ULN;

16. Urine protein ≤2+ or < 1000mg/24h;

17. For premenopausal women with childbearing potential, a pregnancy test must beperformed within 7 days before the initiation of treatment, serum pregnancy must benegative, and must be non-lactating; All enrolled patients (male or female) wereadvised 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-livesbefore the first dose, small molecule targeted therapy within 5 days, palliativeradiotherapy 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 beforescreening;

7. QT prolongation, complete left bundle branch block, III degree atrioventricularblock, 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 currentradiation pneumonitis, or a suspicion of such disease;

12. Complicated with pulmonary diseases leading to clinically severe respiratoryimpairment;

13. Patients with carcinomatous meningitis (meningeal metastasis) or brain stemmetastasis or spinal cord compression;

14. Have a history of allergy to recombinant humanized antibodies or any of theingredients 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 pulmonaryinfection 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 bloodvessels in the abdomen, chest, neck, and pharynx;

20. Were receiving long-term systemic corticosteroids or equivalent activeanti-inflammatory drugs or any form of immunosuppressive therapy beforerandomization;

21. Received other unmarketed investigational drug or treatment within 4 weeks beforethe 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 informedconsent;

25. Subjects with clinically significant bleeding or obvious bleeding tendency within 4weeks before signing the informed consent;

26. History of intestinal obstruction, inflammatory bowel disease, or extensive bowelresection or presence of Crohn's disease, ulcerative colitis, or chronic diarrhea;

27. Patients scheduled for vaccination or receiving live vaccine within 28 days beforethe first dose;

28. Other circumstances that were assessed by the investigator as inappropriate forparticipation in the trial.