A Study of BL-B16D1 in Patients With Unresectable Locally Advanced or Metastatic Breast Cancer and Other Solid Tumors

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 (stage Ia); ≥18 years old (stage Ib); 4. Expected survival time ≥3 months; 5. Patients with histologically and/or cytologically confirmed unresectable locally advanced or metastatic breast cancer and other solid tumors who failed or could not receive standard treatment; 6. Consent to provide archival tumor tissue samples or fresh tissue samples from primary or metastatic lesions within 3 years; 7. Must have at least one extracranial measurable lesion that meets the RECIST v1.1 definition; 8. ECOG 0 or 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. The organ function level must meet the requirements if the patient has not received blood transfusion or hematopoietic stimulation factor therapy within 14 days before the first dose; 12. Coagulation function: international normalized ratio ≤1.5, and activated partial thromboplastin time ≤1.5ULN; 13. Urinary protein ≤2+ or ≤1000mg/24h; 14. For premenopausal women with childbearing potential, a pregnancy test must be performed within 7 days before starting treatment, serum pregnancy must be negative, and the patient must not be lactating; All enrolled patients (male or female) should use adequate contraception throughout the treatment cycle and for 6 months after completion of treatment. Exclusion Criteria: 1. Chemotherapy, biological therapy and other anti-tumor therapies have been used within 4 weeks or 5 half-lives before the first dose; Mitomycin and nitrosoureas were administered within 6 weeks before the first dose; Oral drugs such as fluorouracil; 2. History of severe heart disease; 3. Prolonged QT interval, complete left bundle branch block, III degree atrioventricular block; 4. Active autoimmune and inflammatory diseases; 5. Patients with other malignant tumors or a history of other malignant tumors; 6. Unstable thrombotic events requiring therapeutic intervention within 6 months before screening; Infusion-related thrombosis was excluded; 7. Hypertension poorly controlled by two antihypertensive drugs (systolic blood pressure \> 150 mmHg or diastolic blood pressure \> 100 mmHg); 8. Patients with poor glycemic control; 9. Patients with grade ≥1 radiation pneumonitis according to the RTOG/EORTC definition; Previous history of ILD or current ILD, or suspicion of such disease during screening; 10. Complicated with pulmonary diseases leading to clinically severe respiratory function impairment; 11. Patients with primary central nervous system (CNS) tumors or CNS metastases that had failed local treatment; 12. Patients with a history of allergy to recombinant humanized antibody or human-mouse chimeric antibody or to any of BL-B16D1's excipients; 13. Received previous organ transplantation or allogeneic hematopoietic stem cell transplantation (Allo-HSCT); 14. In previous (new) adjuvant anthracyclines, the cumulative dose of anthracyclines for doxorubicin \> 550 mg/m2, epirubicin \> 900 mg/m2 or the equivalent dose of other similar drugs; 15. Human immunodeficiency virus antibody positive, active tuberculosis, active hepatitis B virus infection or active hepatitis C virus infection; 16. Serious infection occurred within 4 weeks before the first dose; Signs of pulmonary infection or active pulmonary inflammation within 2 weeks before the first dose; 17. Patients with massive or symptomatic effusions, or poorly controlled effusions; 18. Had participated in another clinical trial within 4 weeks before the first dose (calculated from the time of the last dose); 19. Had the following eye diseases: a. active infection or corneal ulcer; b. monocular vision; c. a history of corneal transplantation; d. Contact lens dependence; e. Uncontrolled glaucoma; f. Uncontrolled or progressive retinopathy, wet macular degeneration, etc.; 20. Other circumstances that the investigator deemed inappropriate for participation in the trial.