Pfizer: ELREXFIO™ Achieves Median Survival of More Than Two Years in Relapsed Multiple Myeloma Study

 Pfizer Inc. (NYSE: PFE) today announced detailed overall survival (OS) results from the Phase 2 MagnetisMM-3 study of ELREXFIO™ (elranatamab-bcmm) in patients with heavily pretreated relapsed or refractory multiple myeloma (RRMM). The study demonstrated a median OS of 24.6 (95% CI, 13.4, NE) months in cohort A (n=123) of the pivotal single arm trial.

These data from MagnetisMM-3 will be presented during a poster session (#932) at the European Hematology Association (EHA) Hybrid Congress in Madrid, Spain, from June 13-16. Additional presentations at EHA 2024 will highlight ELREXFIO data across the comprehensive MagnetisMM clinical trial program.

“These compelling overall survival data support the clinical benefit ELREXFIO has already demonstrated and its potential to be a transformative treatment option for people with multiple myeloma,” said Roger Dansey, M.D., Chief Development Officer, Oncology, Pfizer. “The latest results from MagnetisMM-3 reinforce the very promising efficacy observed with ELREXFIO in a relapsed or refractory setting, with deep and durable responses and although definitive conclusions cannot be drawn across studies, the longest reported median progression-free survival among B-cell maturation antigen bispecific antibodies.”

After more than two years of follow-up in the MagnetisMM-3 trial, the overall response rate (ORR) for patients on ELREXFIO was 61.0% (37.4% ≥complete response rate (CRR)), with responses deepening over time, and the median duration of response (DOR) was not reached. At two years, the estimated DOR rate was 66.9% (95% CI: 54.4, 76.7) for all responders, and 87.9% (95% CI: 73.1, 94.8) for patients with CR or better response. Median progression-free survival (PFS) was 17.2 months (95% CI: 9.8 months-NE). For patients with CR or better response, the median PFS was not reached, and at two years, the estimated PFS rate was 90.6% (95% CI: 76.9, 96.4).

“People with relapsed or refractory multiple myeloma often have limited therapeutic options as their disease progresses due to treatment resistance, resulting in increasingly shorter remission and duration of response,” said MagnetisMM-3 clinical trial investigator Mohamad Mohty, M.D., Ph.D., Professor of Hematology and Head of the Hematology and Cellular Therapy Department at the Saint-Antoine Hospital and Sorbonne University, Paris, France. “These impactful overall survival data are particularly encouraging given the very advanced patient population with characteristics associated with poorer outcomes.”

The safety and tolerability of ELREXFIO in MagnetisMM-3 were consistent with what have been previously observed. Five patients (4.1%) experienced secondary primary malignancies (SPMs), all cases being squamous cell carcinoma of the skin, consistent with SPMs often observed in patients with multiple myeloma (MM), while no hematological SPMs were reported. Due to the risk of cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS), patients should be monitored for signs and symptoms for 48 hours after administration of each of the two step-up doses within the ELREXFIO dosing schedule and instructed to remain in proximity of a healthcare facility. In the EU, precautionary hospitalization is not required. Patients are not required to stay near a healthcare facility for the 76 mg first treatment dose.

Based on results of the MagnetisMM-3 trial, ELREXFIO received accelerated approval in August 2023 from the U.S. Food and Drug Administration for the treatment of adult patients with RRMM who have received at least four prior lines of therapy, including a proteasome inhibitor, an immunomodulatory agent, and an anti-CD38 antibody. Continued approval for this indication is contingent upon verification of clinical benefit in a confirmatory trial. In December 2023, the European Commission granted conditional marketing authorization for ELREXFIO for the treatment of adult patients with RRMM who have received at least three prior therapies, including a proteasome inhibitor, an immunomodulatory agent and an anti-CD38 antibody, and have demonstrated disease progression on the last therapy. ELREXFIO has also received approval in Switzerland, Brazil and Canada under Project Orbis, a framework for the concurrent submission and review of oncology drugs among international partners to potentially expedite approvals. Two other countries (Australia and Singapore) are participating in Project Orbis. The Medicines and Healthcare products Regulatory Agency (MHRA) granted ELREXFIO authorization for Great Britain for RRMM.

Pfizer’s comprehensive ongoing MagnetisMM clinical development program is investigating the use of elranatamab across the entire spectrum of patients with MM, from RRMM to newly diagnosed MM. Ongoing registrational-intent trials are comparing elranatamab to current standards of care both as monotherapy and in combination with standard or novel therapies. These include MagnetisMM-4 investigating elranatamab treatment with other anti-cancer therapies, MagnetisMM-5 in the double-class exposed setting, MagnetisMM-6 in newly diagnosed patients who are ineligible for stem cell transplant, MagnetisMM-7 in newly diagnosed patients after transplant, and MagnetisMM-32 in patients with prior anti-CD38-directed therapy.