• Diagnosed with multiple myeloma (MM) by reference to the diagnostic criteria of the Chinese Guidelines for the Diagnosis and Treatment of Multiple Myeloma (Revised 2022);

• Those who have received at least one line of prior systemic antimyeloma therapy (which must include lenalidomide and proteasome inhibitors; see Appendix 4 for counts of myeloma treatment lines) and meet the definition of relapse or refractory; Definition of relapse: disease progression that occurs at least 60 days from the last treatment after the efficacy of a prior treatment regimen was evaluated at MR or better (except for those who relapsed more than 1 year after treatment); Definition of refractory: progression during prior therapy or progression within 60 days of the last treatment; or failure to achieve MR or better after at least 2 prior courses of therapy; or treatment intolerance.

• Age 18-75 years, male or female, if of childbearing potential subjects should be on effective contraception and must agree to comply with all contraceptive requirements:

⁃ 1\) Females of childbearing potential must agree to and comply with the contraceptive measures specified in the protocol: beginning 4 weeks prior to treatment with this product, two reliable methods of contraception are required concurrently for the duration of the treatment, during the dose suspension, and for 4 weeks after termination of the treatment (one highly effective method of contraception-tubal ligation, intrauterine device, hormonal (contraceptive pills, injections, patches, vaginal rings, or implants), or partner's vasectomy, and another effective contraceptive method - male rubber or synthetic condom, diaphragm or cervical cap). Effective contraception is needed even with a history of infertility unless due to hysterectomy; 2) Men of childbearing potential must use a rubber or synthetic condom at all times during sexual contact with women of childbearing potential beginning 4 weeks prior to treatment with this product, during the treatment period, during the dose suspension period, and for 4 weeks after termination of treatment, even if they have had a successful vasectomy; 4. Subjects with multiple myeloma who have measurable M protein, i.e., at least one of the following 3 measurements:

• Serum M protein ≥ 0.5 g/dL (5 g/L);

• Urine M protein ≥ 200 mg/24h;

• Serum free light chain assay: in the case of an abnormal serum free light chain ratio (less than 0.26 or greater than 1.65), an affected free light chain level ≥10mg/dL (100mg/L); 5. Hematologic fulfillment of the following conditions:

⁃ 1\) ANC ≥ 1.0 x 109/L (without granulocyte colony-stimulating factor within 7 days), with no specific requirement for neutrophil count when ≥ 50% of the bone marrow is plasma cells; 2) PLT ≥75 × 109/L (no platelet transfusion or use of thrombopoietin within 7 days), and platelets ≥50 × 109/L were eligible for enrollment when ≥50% of plasma cells were present in the bone marrow; 3) Hemoglobin ≥ 80 g/L (no red blood cell suspension infusion or use of erythropoietin within 7 days); 6. Liver and kidney function tests fulfill the following conditions:

• TBIL ≤ 1.5 x ULN;

• ALT and AST are ≤ 2.5 x ULN;

• Glomerular filtration rate (GFR) ≥ 30mL/min/1.73m2 (Cockcroft-Gault formula) without the effects of dialysis therapy; 7. Ability to receive and have access to antithrombotic medications such as low molecular heparin sodium, heparin, warfarin or aspirin; 8. An ECOG (Appendix 2) score of 0-2 and an expected survival of ≥12 weeks; 9. Subjects voluntarily enrolled in the study and signed an informed consent form.