B cell maturation antigen‐specific chimeric antigen receptor T cells for relapsed or refractory multiple myeloma: A meta‐analysis

Abstract Introduction Chimeric antigen receptor (CAR) T cells targeting B cell maturation antigen (BCMA) have shown impressive results in clinical studies for relapsed/refractory multiple myeloma (RRMM). We performed a systematic literature review to summarize the current body of evidence on the role of anti‐BCMA CAR T cells for RRMM. Objectives and Methods Fifteen studies comprising a total of 285 patients with heavily pretreated RRMM were included using a conventional meta‐analysis. Main efficacy outcomes were response, relapse, and survival. Safety outcomes were cytokine release syndrome (CRS) and neurotoxicity. Results Anti‐BCMA CAR T cells resulted in a pooled overall response of 82% (95% confidence interval [CI], 74%‐88%) and complete response of 36% (24%‐50%). Higher CAR + cell doses were associated with higher response rates. The pooled relapse rate of responders was 45% (27%‐64%), and median progression‐free survival was 10 months. Present extramedullary disease did not show worse outcome. Severe CRS grades 3‐4 and neurotoxicity occurred in 15% (10%‐23%) and 18% (10%‐31%). Conclusion Anti‐BCMA CAR T cells showed high response rates, even in patients with present extramedullary disease, while relapse occurred in half of the patients who achieved a response. Larger studies with longer follow‐up especially evaluating the association of response and survival are needed.