Multicenter phase 1 trial of elranatamab for relapsed or refractory multiple myeloma

Multiple myeloma is a plasma cell malignancy expressing BCMA. Elranatamab is a bispecific antibody directed to BCMA on multiple myeloma cells and to CD3 on T cells. The multicenter phase 1 MagnetisMM-1 trial in Canada and the United States evaluated elranatamab for relapsed or refractory multiple myeloma (RRMM). Among 88 patients, who had received a median of five prior regimens, 90.9% were triple-class refractory, 29.1% had high cytogenetic risk, and 23.6% received prior BCMA-directed therapy. No dose-limiting toxicities were observed during dose escalation. Among 55 patients receiving elranatamab at efficacious doses, with a median follow-up of 12.0 months, the ORR was 63.6% with 38.2% of patients achieving complete response or better. Among responders, the median duration of response was 17.1 months. All 13 patients evaluable for minimal residual disease achieved negativity. The median progression-free and overall survival were 11.8 months and 21.2 months, respectively. The authors conclude that elranatamab achieved durable responses, manageable safety, and promising survival among RRMM patients.