A Study of BL-B01D1 in Patients With Unresectable Locally Advanced or Metastatic Breast Cancer and Other Solid Tumors

Prior treatment

• Received biological therapy, immunotherapy, or other antitumor treatments within 4 weeks or 5 half-lives prior to the first dose (6 weeks for mitomycin and nitrosoureas; oral fluorouracil drugs such as tegafur/gimeracil/oteracil (S-1) or capecitabine, or oral endocrine therapy, or palliative radiotherapy within 2 weeks before the first dose);
• Diagnosis of other malignancies within 2 years prior to the first dose;
• Concurrent pulmonary disease leading to clinically significant respiratory impairment;
• Unstable deep vein thrombosis, arterial thrombosis, pulmonary embolism, or other thrombotic events requiring therapeutic intervention within 6 months before screening (excluding catheter-related thrombosis);
• Previous organ transplantation or allogeneic hematopoietic stem cell transplantation (Allo-HSCT);
• Cumulative anthracycline dose \>360 mg/m² in prior (neo)adjuvant anthracycline therapy;
• Severe infection (CTCAE \> Grade 2) within 4 weeks before the first dose of the study drug; signs of active pulmonary infection within 2 weeks before the first dose;
• Participation in another clinical trial within 4 weeks before the first dose (calculated from the last dose date);

Other illness

• History of severe heart disease;
• Active autoimmune or inflammatory diseases;
• Poorly controlled hypertension (systolic blood pressure \>150 mmHg or diastolic blood pressure \>100 mmHg) despite the use of two antihypertensive medications;
• History of interstitial lung disease (ILD), current ILD, or suspected ILD based on imaging during screening;
• History of hypersensitivity to recombinant humanized antibodies or human-mouse chimeric antibodies, or any excipients of BL-B01D1;
• Positive for human immunodeficiency virus antibody (HIVAb), active tuberculosis, active hepatitis B virus (HBV) infection, or active hepatitis C virus (HCV) infection;
• Any other condition deemed unsuitable for participation in this clinical trial by the investigator.

Lab values

• Prolonged QT interval, complete left bundle branch block, third-degree atrioventricular block, or severe arrhythmia;
• Poorly controlled blood glucose (defined as: a) two fasting blood glucose levels \>10 mmol/L, or b) glycated hemoglobin level exceeding 8%), or concurrent diabetic gangrene;

Other

• Patients with central nervous system (CNS) metastases and/or carcinomatous meningitis (leptomeningeal metastases);
• Patients with significant serous cavity effusion, symptomatic effusion, or poorly controlled effusion;
• Imaging findings indicating tumor invasion or encasement of major thoracic, cervical, or pharyngeal blood vessels, unless the investigator deems it does not affect the patient's eligibility for treatment;

• Voluntarily sign the informed consent form and comply with the protocol requirements;
• No gender restrictions;
• Age: ≥18 years and ≤75 years;
• Expected survival time ≥3 months;
• Histologically and/or cytologically confirmed unresectable locally advanced or metastatic breast cancer and other solid tumors with failed standard treatment, intolerance to standard treatment, no current standard treatment available, or inability to access standard treatment;
• Enrolled subjects should not have received prior systemic therapy for unresectable locally advanced or recurrent/metastatic triple-negative breast cancer;
• Agree to provide archived tumor tissue specimens or fresh tissue samples from primary or metastatic lesions within the past 3 years;
• Must have at least one measurable lesion as defined by RECIST v1.1;
• ECOG performance status score of 0 or 1;
• Toxicity from prior anti-tumor therapy has recovered to ≤ Grade 1 as defined by NCI-CTCAE v5.0;
• No severe cardiac dysfunction, with left ventricular ejection fraction (LVEF) ≥50%;
• Organ function levels must meet the requirements without transfusion or use of any cell growth factors and/or platelet-raising drugs within 14 days before the first dose of the study drug;
• Coagulation function: International Normalized Ratio (INR) ≤1.5, and activated partial thromboplastin time (APTT) ≤1.5 × ULN;
• Urine protein ≤2+ or ≤1000 mg/24h;
• For premenopausal women with childbearing potential, a pregnancy test (serum or urine) must be performed within 7 days before starting treatment, and the result must be negative; they must not be breastfeeding. All enrolled patients (regardless of gender) must use adequate barrier contraception throughout the treatment period and for 6 months after treatment ends.