⁃ Subjects must satisfy all the following criteria to be enrolled in the study:

⁃ 1\. With Subjects' consent and signed informed consent, Subjects are willing and able to follow the planned visit, study treatment, laboratory examination and other test procedures; 2. Patients with relapsed / refractory multiple myeloma according to clinical diagnosis:

• The expression of BCMA and / or CD19 in myeloma cells was positive confimed by flow cytometry or immunohistochemistry;

• Patients with relapsed / refractory multiple myeloma who have received at least 1 line treatment (including proteasome inhibitors (PI), immunomodulatory drugs (IMID), CD38 mAb) or are resistant to proteasome inhibitors and / or immunomodulatory agents and / or CD38 mAb in the past.

⁃ 3\. Age 18-70 years old, both male and female; 4. Subjects with physical fitness status of 0-2 in the Eastern Cooperative Oncology Group (ECOG) score; 5. The estimated survival time from the date of signing informed consent is more than 3 months; 6. Hgb ≥ 60g/L (transfusible); 7. Liver and kidney function and cardiopulmonary function meet the following requirements:

• Creatinine ≤ 2 × ULN;

• Left ventricular ejection fraction ≥ 50%;

• Blood oxygen saturation \>90%;

• Total bilirubin ≤ 1.5 × ULN; ALT and AST ≤ 2.5 × ULN; 8. Subjects with pregnancy plans must agree to take contraception before enrollment in the study and after six months of study duration; The investigator should be informed immediately if the subject is pregnant or suspected of pregnancy.

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