By Dr. Anish Shah
On August 14, 2023, the U.S. Food and Drug Administration granted accelerated approval to Elranatamab-bcmm (Elrexfio) for adults with relapsed or refractory multiple myeloma who have received at least four prior lines of therapy, including a proteasome inhibitor, an immunomodulatory agent, and an anti-CD38 monoclonal antibody. Elrabatamab is a bispecific antibody that targets B-cell maturation antigen (BCMA) and CD3 on T-cells and activates and redirects the T-cell mediated immune response against MM.
Study ID number: NCT04649359
Approval was based on the MagnetisMM-3 trial, an open-label, single-arm, multi-center study that included 97 patients with relapsed/refractory multiple myeloma who were refractory to key drugs and had measurable disease by International Myeloma Working Group (IMWG) criteria. They also needed an ECOG performance status of 0 to 2, acceptable bone marrow, renal, and hepatic function and LV ejection fraction of 40% or higher. Elranatamab-bcmm was given as a step-up dose (12 mg on day 1, 32 mg on day 4, and 76 mg weekly from day eight until the 24th week) until disease progression or unacceptable toxicity was observed. The median treatment duration was not specifically mentioned, but median follow-up was 11.1 months.
Efficacy was established on the primary efficacy outcome measures of objective response rate (ORR) and duration of response (DOR). Results showed an ORR of 57.7% (95% CI, 47.3%-67.7%) in the 97 patients who were naïve to the therapy. The ORR included a complete response rate of 25.8%, an excellent partial response rate of 25.8%, and a partial response rate of 6.2%. The median DOR was not reached but was observed to be strong at 6 and 9 months – 90.4% (95% CI, 78.4%-95.9%) and 82.3% (95% CI, 67.1%-90.9%), respectively, with a median follow up of 11.1 months (95% CI, 10.6-12.0). Elranatamab-bcmm showcases a significant response rate among patients with refractory multiple myeloma. Controlled application can be a game-changer for those with limited treatment options.
Severe side effects include life-threatening cytokine release syndrome (CRS) and neurologic toxicity. Common adverse reactions range from CRS, fatigue, digestive issues, and respiratory infections to musculoskeletal pain.
FDA’s accelerated approval for Elranatamab-bcmm (Elrexfio) brings forth a new treatment avenue for refractory multiple myeloma patients. The recommended dosage starts with a step-up dose transitioning to a weekly regimen. Continuous monitoring and adherence to dosing guidelines can maximize its therapeutic potential while minimizing associated risks.
