In phase Ia study, the safety and tolerability of BL-B01D1 in patients with locally advanced or metastatic gastrointestinal tumor and other solid tumor will be investigated to determine the dose-limiting toxicity (DLT), maximum tolerated dose (MTD) of BL-B01D1.

In phase Ib study, the safety and tolerability of BL-B01D1 at the phase Ia recommended dose will be further investigated, and recommended phase II dose (RP2D) for phase II clinical studies will be determined.

In addition, the preliminary efficacy, pharmacokinetic characteristics, and immunogenicity of BL-B01D1 in patients with locally advanced or metastatic gastrointestinal tumor and other solid tumor will be evaluated.

Inclusion Criteria:

1. Participants must sign the informed consent form voluntarily and follow the plan requirements.
2. No gender limit.
3. Age: ≥18 years old and ≤75 years old (phase Ia); ≥18 years old (phase Ib).
4. Expected survival time ≥ 3 months.
5. Patients with locally advanced or metastatic triple-negative breast cancer or other solid tumors who have been diagnosed histopathologically and/or cytologically as failing standard therapy, or who are not eligible for standard therapy at this stage, and who are inoperable.
6. Agree to provide archived tumor tissue samples or fresh tissue samples from the primary tumor or metastatic tumor within 3 years (TROP2 protein expression in tumor pathological tissue to explore the correlation between TROP2 protein expression and BL-M02D1 validity index); If subjects are unable to provide tumor tissue samples, they will be admitted after evaluation by the investigator if other admission criteria are met.
7. Participants must have at least one assessable lesion as defined by RECIST V1.1.
8. Has an Eastern Cooperative Oncology Group performance status (ECOG PS) 0-1
9. The toxicity of previous antitumor therapy was restored to ≤1 as defined by NCI-CTCAE v5.0 (except for asymptomatic laboratory abnormalities considered by the investigators, such as elevated ALP, hyperuricemia, and elevated blood glucose; Toxicities with no safety risk, such as hair loss, grade 2 peripheral neurotoxicity, were excluded).
10. Has adequate organ function before registration, defined as: a) Bone marrow function: Absolute neutrophil count (ANC) ≥1.5×109/L, Platelet count ≥90×109/L, Hemoglobin ≥90 g/L; B) Hepatic function: Total bilirubin (TBIL≤1.5 ULN), AST and ALT ≤2.5 ULN for participants without liver metastasis, AST and ALT ≤5.0 ULN for liver metastases; c) Renal function: Creatinine (Cr) ≤1.5 ULN, or creatinine clearance (Ccr) ≥50 mL/min (according to the Cockcroft and Gault formula).
11. Coagulation function: International normalized ratio (INR)≤1.5, and activated partial thromboplastin time (APTT)≤1.5ULN.
12. Urinary protein ≤2+ or ≤1000mg/24h.
13. For premenopausal women with childbearing potential, a pregnancy test must be taken within 7 days prior to the start of treatment. Serum or urine pregnancy must be negative and must be non-lactating. Adequate barrier contraceptive measures should be taken during the treatment and 6 months after the end of treatment for all participants (regardless of male or female).

Exclusion Criteria:

Patients screened for any of the following conditions will not be included in this study:

1. Chemotherapy, biological therapy, immunotherapy, radical radiotherapy, major surgery, targeted therapy (including small molecule inhibitor of tyrosine kinase), and other anti-tumor therapy within 4 weeks or 5 half-lives (whichever is shorter) prior to the first administration; mitomycin and nitrosoureas treatment within 6 weeks prior to the first administration; oral fluorouracil-like drugs such as S-1, capecitabine, or palliative radiotherapy within 2weeks prior to the first administration.
2. Prior treatment with ADC drugs targeting TROP2 or ADC drugs using camptothecin derivatives (topoisomerase I inhibitors) as toxins.
3. Participants with history of severe heart disease, such as: symptomatic congestive heart failure (CHF) ≥ grade 2 (CTCAE 5.0), New York Heart Association (NYHA) ≥ grade 2 heart failure, history of transmural myocardial infarction, unstable angina pectoris etc.
4. Participants with prolonged QT interval (male QTc> 450 msec or female QTc> 470 msec), complete left bundle branch block, III grade atrioventricular block.
5. Active autoimmune diseases and inflammatory diseases, such as: systemic lupus erythematosus, psoriasis requiring systemic treatment, rheumatoid arthritis, inflammatory bowel disease and Hashimoto's thyroiditis, etc., except for type I diabetes, hypothyroidism that can be controlled only by alternative treatment, and skin diseases that do not require systemic treatment (such as vitiligo, psoriasis).
6. The presence of a second primary tumor within 5 years prior to initial administration, except for radical basal cell carcinoma of the skin, squamous cell carcinoma of the skin, and/or radical resected carcinoma in situ.
7. Screening for unstable thrombotic events such as deep vein thrombosis, arterial thrombosis and pulmonary embolism requiring therapeutic intervention within the first 6 months; Infusion device-related thrombosis is excluded;
8. Unstable thrombotic events such as deep vein thrombosis, arterial thrombosis and pulmonary embolism requiring therapeutic intervention within 6 months prior to screening; Thrombus formation associated with infusion set is excluded.
9. Symptoms of active central nervous system metastasis. However, patients with stable brain parenchymal metastases can be enrolled. Stable was defined as: a. The seizure-free state lasted for > 12 weeks with or without the use of antiepileptic drugs; b. Glucocorticoid use is not required; c. Consecutive MRI scans (at least 8 weeks between scans) showed stable imaging status.
10. Patients with a history of allergy to recombinant humanized antibody or mouse chimeric antibody or to any excipients of BL-B01D1.
11. Previous recipients of organ transplantation or allogeneic hematopoietic stem cell transplantation (Allo-HSCT).
12. In previous adjuvant therapy with anthracyclines, the cumulative dose of anthracyclines was > 360 mg/m2.
13. Positive human immunodeficiency virus antibody (HIVAb), active tuberculosis, active hepatitis B virus infection (HBV-DNA copy number > 103IU/ml) or active hepatitis C virus infection (HCV antibody positive and HCV-RNA > lower limit of detection).
14. Active infections requiring systemic treatment, such as severe pneumonia, bacteremia, septicemia, etc.
15. Participated in another clinical trial (calculated from the time of the last dose) within 4 weeks prior to the first dose.
16. The other conditions of participation in this clinical trial were not considered appropriate by the investigators.