A Study of BCMA-directed CAR-T Cells Treatment in Subjects With r/r Multiple Myeloma

Inclusion Criteria: 1. Age 18-75 years old, male or female; 2. The patient volunteered to participate in the study, and he or his legal guardian signed the Informed Consent; 3. Patients with a clear diagnosis of relapsed or refractory multiple myeloma 4. The patient have one or more measurable multiple myeloma lesion, must include one of the following conditions: * Serum M protein≥1.0 g/dL(10g/L) * Urine M protein≥200 mg/24h * Serum free light chain(sFLC): κ/λ FLC ratio is abnormal and affected FLC ≥10mg / dL 5. Bone marrow sample is confirmed as BCMA-positive by flow cytometry or pathological examination; 6. At least 2 weeks from monoclonal antibody therapy prior to CAR T cell therapy. 7. ECOG scores 0 - 1; 8. Good cardiac and pulmonary organ function; 9. Expected survival time \> 12 weeks;. 10. Female subjects of childbearing age must have a negative urine / blood pregnancy test within 7 days before cell therapy and not be in lactation; female or male subjects of childbearing age need to take effective contraception throughout the study. Exclusion Criteria: 1. Have a history of allergy to cellular products; 2. Laboratory testing occurs when: including but not limited to, serum total bilirubin ≥1.5mg / dl; serum ALT or AST is 2.5 times higher than the upper limit of normal value; serum creatinine ≥2.0mg / dl; hemoglobin \<80g / L; absolute neutrophil count \<1000 / mm3 or dependent on GCSF or Other growth factors can maintain the centriole count ≥1000 / mm²; platelet count \<50000 / mm³ or the above level can be maintained due to platelet transfusion; 3. Presence of clinically significant cardiovascular disease, such as uncontrolled or symptomatic arrhythmias, congestive heart failure, or any heart function Grade 3 (moderate) or Grade 4 (severe) heart disease (according to the New York Heart Association Function Classification method: NYHA); patients with a history of myocardial infarction, cardiac angioplasty or stent implantation, unstable angina pectoris or other clinically significant heart disease within 12 months before enrollment; 4. A history of craniocerebral trauma, consciousness disorder, epilepsy, severe cerebral ischemia or hemorrhagic disease; 5. Need to use any anticoagulant (except aspirin); 6. Patients requiring urgent treatment due to tumor progression or spinal cord compression; 7. Patients with CNS metastasis or symptoms of CNS involvement; 8. After allogeneic hematopoietic stem cell transplantation; 9. Plasma cell leukemia; 10. Patients with autoimmune diseases, immunodeficiency, or other immunosuppressive agents; 11. Uncontrolled active infection; 12. Have used any CAR T cell products or other genetically modified T cell therapy before; 13. Hepatitis B or hepatitis C virus infection (including carriers), syphilis, as well as acquired, congenital immune deficiency diseases, including but not limited to HIV infected persons; 14. Have a history of alcoholism, drug addiction and mental illness; 15. Participated in any other clinical trial within 1 months; 16. The investigators believe that there are other circumstances that are not suitable for the trial.