Dose Optimization of Elranatamab to Mitigate the Risk of Cytokine Release Syndrome in Patients with Multiple Myeloma

BACKGROUND: Elranatamab is a BCMA-CD3 bispecific antibody approved for the treatment of relapsed or refractory multiple myeloma. Cytokine release syndrome is one of the most common adverse events associated with bispecific antibodies. OBJECTIVE: We aimed to determine the optimal elranatamab dosing regimen for mitigating cytokine release syndrome. PATIENTS AND METHODS: Safety, pharmacokinetics, and exposure-response were analyzed across four clinical studies (MagnetisMM-1, MagnetisMM-2, MagnetisMM-3, and MagnetisMM-9). Different priming regimens evaluated across these studies included a one-step-up dose priming regimen of 44 mg with or without premedication, a two-step-up dose priming regimen of 12 mg on day 1 and 32 mg on day 4 with premedication, and a two-step-up dose priming regimen of 4 mg on day 1 and 20 mg on day 4 with premedication. RESULTS: The maximum elranatamab serum concentration on day 1 was positively associated with any-grade and grade ≥ 2 cytokine release syndrome. A slower time to maximum serum concentration and a lower dose-normalized maximum serum concentration were observed with subcutaneous versus intravenous administration, supporting subcutaneous dosing to help mitigate cytokine release syndrome. CONCLUSIONS: Based on the incidence, severity, and predictable profile of cytokine release syndrome, the 12/32-mg priming-dose regimen with premedication was determined to be the optimal regimen before the first full dose of 76 mg on day 8. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov identifiers: NCT03269136, NCT04798586, NCT04649359, and NCT05014412.