In March 2021, the FDA approved idecabtagene vicleucel, a chimeric antigen receptor T-cell therapy targeting the B-cell maturation antigen (BCMA), for adult patients with relapsed/refractory multiple myeloma (RRMM) after ≥4 lines of therapy including an immunomodulatory agent, a proteasome inhibitor, and an anti-CD38 mAb. Approval was based on overall response rate (ORR), complete response (CR) rate, and duration of response (DOR) in 100 adult patients with RRMM treated with idecabtagene vicleucel in a single-arm trial. Patients received a single infusion of idecabtagene vicleucel, preceded by lymphodepleting chemotherapy with cyclophosphamide and fludarabine. Of the 100 patients in the efficacy evaluable population, ORR was 72% [95% confidence interval (CI), 62–81] with stringent CR rate of 28% (95% CI, 19–38). After median follow-up of 10.7 months, median DOR was 11 months (95% CI, 10.3–11.4) in responders (partial response or better) and 19 months [95% CI, 11.4 months, not estimable (NE)] in patients who achieved stringent CR. Serious adverse reactions occurred in 67% of 127 patients evaluated for safety. Grade 3 or higher cytokine release syndrome and neurologic toxicities occurred in 9% and 4%, respectively, leading to a Risk Evaluation and Mitigation Strategy. Hemophagocytic lymphohistiocytosis/macrophage activation syndrome occurred in 4%, with two fatalities. Prolonged cytopenia requiring hematopoietic rescue occurred in 2% (3/127), with two fatalities.