Deepu Madduri, MD, Icahn School of Medicine at Mount Sinai, New York, NY, shares updated data from a first-in-human Phase I trial (NCT03761108) of REGN5458 in relapsed/refractory (R/R) multiple myeloma patients. REGN5458 is a B-cell maturation antigen (BCMA) x CD3 bispecific antibody, thus allowing T-cell targeted killing of BCMA-expressing multiple myeloma cells. Trial results indicate an acceptable safety and tolerability profile for REGN5458, with the most common treatment-related adverse event being low-grade cytokine release syndrome (CRS). Efficacy results from the 49 heavily pretreated R/R multiple myeloma patients that took part in the dose escalation study demonstrated early, deep and durable responses, with a total overall response rate (ORR) of 39% and 42% of responders achieving a complete response. Importantly, 37% of responders maintained their response for 8 months or more. This interview took place during the 62nd American Society of Hematology (ASH) Annual Meeting and Exposition, 2020.