Real-world outcomes with elranatamab in multiple myeloma: a multicenter analysis from the U.S. Multiple Myeloma Immunotherapy Consortium

Elranatamab, a BCMA-CD3 bispecific antibody, has demonstrated robust activity in relapsed/refractory multiple myeloma (RRMM), but real-world outcomes remain poorly defined. We conducted a multicenter retrospective study of 130 patients treated with commercial elranatamab across nine U.S. academic centers. The cohort was heavily pretreated (91% triple-class refractory, 49% penta-refractory), with 49% previously exposed to BCMA-targeted therapies. Only 22% would have met eligibility for MagnetisMM-3 cohort A. The overall response rate (ORR) was 65%, including ≥CR in 36%. Median progression-free survival (PFS) and overall survival (OS) were 4.3 and 14.6 months, respectively, shorter than MagnetisMM-3. Elevated LDH and low hemoglobin independently predicted poor outcomes and were incorporated into the novel ALPS (Anemia-LDH Prognostic System) score, which stratified patients into distinct risk groups for ORR, OS, PFS, and duration of response. Prior BCMA exposure reduced depth of response, with inferior OS observed in those treated within one year of prior therapy. Infections occurred in 38% of patients. Intravenous immunoglobulin supplementation, modeled as a time-dependent covariate, was associated with improved infection-free survival and PFS. While the incidence of CRS was modestly lower than in MagnetisMM-3, ICANS occurred more frequently in this real-world cohort. These findings highlight the efficacy, limitations, and supportive care needs of elranatamab in a frailer, more heterogeneous real-world RRMM population.