Objective To evaluate the long-term efficacy and safety of B cell maturation antigen (BCMA)-chimeric antigen receptor-T (CAR-T) cells in the treatment of recurrent/refractory multiple myeloma (R/R MM).

Methods A retrospective analysis was conducted on the clinical data of 20 patients with R/R MM who received BCMA CAR-T-cell therapy at The First Affiliated Hospital of Nanchang University between July 2018 and July 2023. The follow-up period was up to December 31, 2023. Overall survival and progression-free survival (PFS) rates were evaluated using Kaplan–Meier analysis, and adverse effects were recorded.

Results Of all 20 cases with R/R MM, the median number of previous treatment lines was three (range: two to six), total objective response rate (ORR) was 75%, and complete response (CR) rate was 50%. The median follow-up duration was 29 months, with a median PFS of 26 months. Among ten patients with CR, five were still in remission at the last follow-up, with the shortest duration of remission being 6 months and the longest being 48 months. In the subgroup analysis, PFS was significantly worse in patients with extramedullary infiltration, high tumor burden, and 17p deletion high-risk cytogenetic features (P<0.05). Cytokine release syndrome (CRS) was the most common (90%) adverse event, and it was mostly mild, with an incidence rate of grade 3 or higher of 35%. Few long-term adverse effects occurred and no CAR-T cell treatment-related deaths were observed.

Conclusions BCMA CAR-T-cell therapy was effective and safe for patients with R/R MM. Patients with extramedullary diseases and high tumor burden can also benefit from this treatment; however, their persistent response is not satisfactory. It is worth exploring the differences and designing prospective clinical studies to consolidate and maintain the efficacy in these patients.