Anti-CD19/BCMA Bispecific CAR-T Cell Therapy for R/R MM

Inclusion Criteria: * Expected survival \> 12 weeks * Diagnosis of Multiple Myeloma by IMWG updated criteria (2014) * Pathology demonstrated that BCMA-poitive malignant plasma cells exited in bone marrow or plamacytoma * Exited measurable lesions and in accordance with one of the following test indicators: serum M protein≥1 g/dl; urine M protein≥200 mg/24h; serum free light chain≥10 mg/dl; diagnosis of plasmacytoma by biopsy * The criteria for relapsed and refractory multiple myeloma: patients previously received at least 3 different prior treatment regimens for multiple myeloma, including protein inhibitors (eg: Bortezomib), and immunomodulator (eg: Revlimid), and have disease progression in the past 60 days * At least 90 days after stem cell transplantation * Clinical performance status of ECOG score 0-2 * Creatinine≤2.0 mg/dl * Bilirubin≤2.0 mg/dl * The ALT/AST value is lower than 2.5-fold of normal value * Accessible to intravenous injection, and no white blood cell collection contraindications * Sexually active patients must be willing to utilize one of the more effective birth control methods for 30 days after the CTL infusion. Male partner should use a condom * 5mg/day dose of Prednisone or other equivalent steroid hormone drugs (eg: Dexamethasone) were not used for two weeks before apheresis and CAR-T infusion * Able to understand and sign the Informed Consent Document. Exclusion Criteria: * Patients with symptoms of central nervous system * Patients with second malignancies in addition to multiple myeloma * Active hepatitis B or C, HIV infections * Any other active diseases could affect the enrollment of this trial * Long term use of immunosuppressive agents after organ transplantation, except currently receiving or recently received glucocorticoid treatment * Patients with organ failure * Women of child-bearing potential who are pregnant or breastfeeding during therapy, or have a planned pregnancy with 2 months after therapy * A history of mental illness and poorly controlled * Women of child-bearing potential who are not willing to practice birth control from the time of enrollment on this study and for 2 months after receiving the preparative regimen. Women of child bearing potential must have a negative serum or urine pregnancy test performed within 48 hours before infusion * Patients who are accounted by researchers to be not appropriate for this test * Subjects suffering disease affects the understanding of informed consent or complying with study protocol