Background: Encouraging results are seen from several early phase clinical trials on the cellular immunotherapy based on chimeric antigen receptor (CAR)-engineered T (CAR-T) targeting B cell maturation antigen (BCMA) for the treatment of relapsed/refractory (RR) multiple myeloma (MM). We developed an anti-BCMA CAR-T cell product manufactured via gamma-retrovirus-mediated transduction of activated T cells to express a second-generation CAR with the 4-1BB costimulatory domain along with a truncated epidermal growth factor receptor (tEGFR) as a safety switch. The preclinical study confirmed its high reactivity against MM cells. Methods: A phase 1 clinical trial (NCT03093168) has been launched to evaluate the safety and feasibility of this BCMA CAR-T cell product for treating RRMM. The enrolled RRMM patients had received at least 3 prior treatment regimens, including a proteasome inhibitor and an immunomodulatory agent, or are double-refractory, and have over 20% BCMA expression on plasma cells. Patients were subjected to a lymphodepleting regimen with Cy once (300 mg/m², d-3) and Flu daily for 3 days (25 mg/m², d-5 to d-3) prior to the CAR-T infusion (d0) at a dose of 9×10⁶ CAR⁺ cells/kg. The efficacy was assessed by the International Uniform Response Criteria for Multiple Myeloma, and the toxicity iss graded by CTCAE 4.02. Results: As of December 31, 2017, 10 patients had been infused with this intended dose of the autologous BCMA CAR-T cells, and 7 patients had reached at least 1 month of follow-up. As of this data cut-off, no greater than Grade 1 neurotoxicities or cytokine release syndrome (CRS) had been observed. The overall response rate (ORR) for the 7 evaluable patients was 86%, including 2 sCRs and 2 MRD-negative responses (2 VGPR). The CAR-T cell expansion and persistence were consistently observed throughout these patients. Conclusions: Our result demonstrates the promising efficacy with the infused dose, including 2 sCRs and ongoing clinical responses for more than 12 months, with only mild and manageable CRS to date. These initial data provide strong evidence to support the further development of this anti-myeloma cellular immunotherapy. Clinical trial information: NCT03093168