A Study of BL-M24D1 in Patients With Locally Advanced or Metastatic Gastrointestinal Tumors and Other Solid Tumors

Inclusion Criteria: 1. Voluntarily sign the informed consent form and comply with the protocol requirements; 2. No gender restrictions; 3. Age: ≥18 years and ≤75 years (Phase Ia); ≥18 years (Phase Ib); 4. Expected survival time ≥3 months; 5. Locally advanced or metastatic digestive tract tumors and other solid tumors; 6. Agree to provide archived tumor tissue specimens or fresh tissue samples from primary or metastatic lesions within the past 3 years; 7. Must have at least one measurable lesion meeting the RECIST v1.1 criteria; 8. ECOG performance status score of 0 or 1; 9. Toxicities from prior antitumor treatments have recovered to ≤ Grade 1 as defined by NCI-CTCAE v5.0; 10. No severe cardiac dysfunction, left ventricular ejection fraction ≥50%; 11. Organ function levels must meet the requirements; 12. Coagulation function: International Normalized Ratio (INR) ≤1.5, and activated partial thromboplastin time (APTT) ≤1.5 × ULN; 13. Urine protein ≤2+ or ≤1000mg/24h; 14. For premenopausal women with childbearing potential, a pregnancy test must be conducted within 7 days before starting treatment, serum pregnancy must be negative, and they must not be breastfeeding; all enrolled patients (regardless of gender) should adopt adequate barrier contraception throughout the treatment cycle and for 6 months after treatment ends. Exclusion Criteria: 1. Use of chemotherapy, biological therapy, or immunotherapy within 4 weeks prior to the first dose or within 5 half-lives; 2. History of severe heart disease; 3. QT interval prolongation, complete left bundle branch block, or third-degree atrioventricular block; 4. Active autoimmune or inflammatory diseases; 5. Diagnosis of other malignancies within 5 years prior to the first dose; 6. Hypertension poorly controlled by two antihypertensive medications; 7. Patients with poorly controlled blood glucose; 8. Unstable thrombotic events requiring therapeutic intervention within 6 months prior to the first dose; 9. Lung diseases graded ≥3 according to CTCAE v5.0; 10. Symptoms of active central nervous system metastases; 11. History of allergy to recombinant humanized antibodies or human-mouse chimeric antibodies, or allergy to any excipient component of BL-M24D1; 12. Previous organ transplantation or allogeneic hematopoietic stem cell transplantation (Allo-HSCT); 13. Cumulative dose of anthracyclines \>360 mg/m² in previous (neo)adjuvant anthracycline therapy; 14. Human immunodeficiency virus antibody positivity, active tuberculosis, active hepatitis B virus infection, or active hepatitis C virus infection; 15. History of interstitial lung disease (ILD) requiring steroid treatment, or current ILD; 16. Active infection requiring systemic treatment within 4 weeks prior to the first investigational drug dose; 17. Pleural, abdominal, pelvic, or pericardial effusion requiring drainage and/or accompanied by symptoms within 4 weeks prior to the first investigational drug dose; 18. Subjects with clinically significant bleeding or obvious bleeding tendency within 4 weeks prior to the first investigational drug dose; 19. Participation in another clinical trial within 4 weeks prior to the first dose; 20. Pregnant or lactating women; 21. Other conditions deemed by the investigator as unsuitable for participation in this clinical trial.