Efficacy and follow-up of humanized anti-BCMA CAR-T cell therapy in relapsed/refractory multiple myeloma patients with extramedullary-extraosseous, extramedullary-bone related, and without extramedullary disease.

The prognosis of patients with multiple myeloma (MM) with extramedullary disease (EMD) remains poor. A high overall response rate (ORR) has been reported following anti-B-cell maturation antigen (BCMA) chimeric antigen receptor (CAR)-T cell therapy in relapsed/refractory (R/R) patients with MM; however, data on patients with EMD remain limited. Herein, we compared and analyzed the efficacy and long-term follow-up of anti-BCMA CAR-T cell therapy in R/R MM patients with extramedullary-extraosseous (EM-E), extramedullary-bone related (EM-B), and without extramedullary disease. No difference in the ORR was observed between the three groups. The long-term efficacy of anti-BCMA CAR-T cell therapy in the EM-E group was worse than that in patients without EMD and with EM-B. In the EM-E group, disease progression was the reappearance of extramedullary lesions without an increase in the MM cell percentage or M protein level. Although no difference in the proportion of CAR-T cells was detected among the three groups, the EM-E group might exhibit a relatively high grade of cytokine release syndrome following anti-BCMA CAR-T therapy. Interleukin-6 levels in the without EMD group were lower than those in the EM-E and EM-B groups. However, given the small number of cases in the three groups, statistical analysis was not performed.(ChiCTR1800017051 and ChiCTR2000033925).