Sequencing BCMA-Directed Therapies in Relapsed/Refractory Multiple Myeloma: A Real-World Comparison of CAR T-Cell Therapy and Bispecific Antibodies

Background: Several B-cell maturation antigen (BCMA)-directed therapy (BDT) modalities have been approved by the US Food and Drug Administration (FDA) for relapsed-refractory multiple myeloma (RRMM). Ideal sequencing of these therapies remains unknown. Methods: We report one of the largest multicenter retrospective patient cohorts in this real-world analysis of patients receiving a BDT in both BDT-naïve and exposed settings at major academic centers. Results: In the BDT-naïve setting, which included 276 patients, 169 (61%) received chimeric antigen receptor T-cell therapy (CAR-T), whereas 107 (39%) received bispecific antibodies (BsAbs). Median progression-free survival (PFS) in the BDT-naïve setting was significantly longer with CAR-T than with BsAbs (16.1 vs. 13.5 months, p = 0.007) with a higher overall response rate (ORR) (87 vs. 68%). Multivariable Cox regression analysis revealed that receiving CAR-T (hazard ratio [HR] = 0.41), cytokine release syndrome (CRS) of any grade (HR = 0.50), achieving a best response of ≥very good partial response (VGPR) (HR = 0.12), and high-risk cytogenetic abnormalities (HRCA) (HR = 2.29) were all significant prognostic indicators of PFS. Similarly, HRCA (HR = 2.32), CRS (HR = 0.36), and a best response of ≥VGPR (HR = 0.16) were all independent prognostic factors of overall survival (OS). Of the 80 patients who received prior BDT, 22 received CAR-T (28%) and 58 (72%) received BsAbs. The median PFS was 6.3 months in the CAR-T group, with 64% ORR, vs. 4.4 months in the BsAb group, with 53% ORR (PFS HR, 0.93). Only the best response, ≥VGPR (HR = 0.20), achieved significance in the multivariable model. Conclusions: CAR-T led to more durable responses in the BDT-naïve setting than BsAbs. Responses to either modality were weaker in the BDT-exposed setting. These results highlight the importance of sequencing BDT in RRMM.