Clinical Research of Adoptive BCMA CAR-NK Cells on Relapse/Refractory MM

Inclusion Criteria: 1. 18 years to 80 years, expected survival \> 3 months 2. Confirmed diagnosis of active MM as defined by IMWG. BCMA expression of the malignant cells must be detected by immunohistochemistry or by flow cytometry 3. BCMA-expressing B cell malignancy must be assured and must be relapsed or refractory disease 4. ECOG performance status of 0 - 1 5. Cardiac function: 1 - 2 levels; Liver: TBIL ≤ 3ULN，AST ≤ 2.5 ULN，ALT ≤ 2.5ULN; kidney: Cr ≤ 1.25ULN 6. No serious allergic constitution 7. No other serous diseases that conflicts with the clinical program 8. No other cancer history 9. Female participants of reproductive potential must have a negative serum pregnancy test 10. Subjects must have signed written, informed consent Exclusion Criteria: 1. Pregnant or lactating women 2. Uncontrolled active infection, HIV infection, syphilis serology reaction positive 3. Active hepatitis B or hepatitis C infection 4. Recent or current use of glucocorticoid or other immunosuppressor 5. Serious mental disorder 6. With severe cardiac, liver, renal insufficiency, diabetes and other diseases 7. Participate in other clinical research in the past three months 8. Previously treatment with any gene therapy products