Subcutaneous Use of BCMA-CD3 Bispecific Monoclonal Antibody in Myeloma
Posted: Tuesday, July 27, 2021
In the ongoing phase I MagnetisMM-1 trial, subcutaneous doses of at least 215 μg/kg of elranatamab achieved an overall response rate of 75% in patients with relapsed or refractory multiple myeloma. The updated results, which were presented by Nizar J. Bahlis, MD, of the University of Calgary, Canada, and colleagues, during the 2021 American Society of Clinical Oncology (ASCO) Annual Meeting (Abstract 8006), suggested this humanized bispecific monoclonal antibody also had a manageable safety profile.
“Elranatamab…targets B-cell maturation antigen (BCMA), a member of the tumor necrosis factor receptor superfamily expressed in multiple myeloma, and CD3 on T cells,” the investigators commented. “The results…support ongoing development of elranatamab for patients with multiple myeloma, both as monotherapy and in combination with standard or novel therapies.”
A total of 30 patients were administered 80, 130, 215, 360, 600, or 1,000 μg/kg of elranatamab weekly via subcutaneous injection. Lymphopenia (80%), cytokine-release syndrome (73%), anemia (57%), injection-site reaction (53%), thrombocytopenia (53%), and neutropenia (40%) were among the most frequently reported all-causality treatment-emergent adverse events. Both cytokine-release syndrome and immune effector cell–associated neurotoxicity syndrome (20%) were limited to grade 2 or lower; the median durations of these toxicities were 2.0 and 1.5 days, respectively. No dose-limiting toxicities were reported.
Exposure increased with dose, and the duration of the time taken to reach the maximum concentration ranged from 3 to 7 days. Cytokine increases were observed with the first dose; the investigators reported increased T-cell proliferation in the peripheral blood. The overall response rate for doses of at least 215 μg/kg was 75%; a total of six partial responses, three very good partial responses, one complete response, and five stringent complete responses were observed. The median duration of the time to response was 22 days; a total of 75% of patients who were previously administered BCMA-directed therapy achieved a response.
Disclosure: For full disclosures of the study authors, visit coi.asco.org.
