A Study of BL-M11D1 in Patients With Relapsed/Refractory Myelodysplastic Syndromes

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; 4. Expected survival time ≥3 months; 5. Relapsed/refractory CD33+ MDS; 6. Morphological assessment showing blasts in bone marrow ≥5% and \<20%; 7. Eastern Cooperative Oncology Group (ECOG) performance status ≤2; 8. Toxicities from prior anti-tumor therapy must have recovered to ≤ Grade 1 as defined by NCI-CTCAE v6.0; 9. Meet the required organ function levels; 10. For premenopausal women of childbearing potential, a pregnancy test (serum/urine) must be negative within 7 days before starting treatment, and they must not be breastfeeding; all enrolled trial participants (regardless of gender) must practice adequate barrier contraception throughout the entire treatment period and for 6 months after treatment completion. Exclusion Criteria: 1. Use of chemotherapy, biotherapy, immunotherapy, etc., within 4 weeks or 5 half-lives prior to the first dose; 2. Presence of uncorrected folate deficiency or vitamin B12 deficiency, etc.; 3. History of severe cardiovascular or cerebrovascular disease; 4. Thromboembolic events requiring therapeutic intervention within 6 months prior to screening; 5. Active autoimmune diseases and inflammatory diseases; 6. History of extensive bowel resection or presence of Crohn's disease, ulcerative colitis, chronic diarrhea, or intestinal obstruction; 7. Diagnosis of another malignancy within 5 years prior to the first dose; 8. Poorly controlled hypertension; 9. Poorly controlled hyperglycemia or diabetes mellitus; 10. Pulmonary diseases classified as Grade ≥3 according to CTCAE v6.0, etc.; 11. Trial participants with central nervous system involvement; 12. Trial participants with extramedullary involvement; 13. Trial participants with a history of allergy to recombinant humanized antibodies or chimeric human-mouse antibodies, or hypersensitivity to any excipient component of BL-M11D1; 14. Prior organ transplantation or hematopoietic stem cell transplantation; 15. Positive for human immunodeficiency virus antibody, active tuberculosis, active hepatitis B virus infection, or active hepatitis C virus infection; 16. Active fungal, bacterial, or viral infections; 17. History of severe neurological or psychiatric disorders; 18. Trial participants with clinically significant bleeding or obvious bleeding tendency within 4 weeks prior to signing informed consent; 19. Presence of clinically symptomatic pleural, peritoneal, or pericardial effusion requiring repeated drainage; 20. Participation in another clinical trial within 4 weeks or 5 half-lives prior to the first dose; 21. Pregnant or breastfeeding women; 22. Other conditions deemed by the investigator to make the participant unsuitable for participation in this clinical trial.