ELREXFIO™ Achieves Over Two-Year Median Survival in Relapsed/Refractory Multiple Myeloma

Pfizer Inc. has unveiled detailed overall survival (OS) results from the Phase 2 MagnetisMM-3 study of ELREXFIO™ (elranatamab-bcmm) in patients dealing with heavily pretreated relapsed or refractory multiple myeloma (RRMM). According to the study, patients in cohort A (n=123) of the pivotal single-arm trial exhibited a median OS of 24.6 months. These significant findings will be showcased at the European Hematology Association (EHA) Hybrid Congress in Madrid, Spain, from June 13-16, alongside additional presentations highlighting ELREXFIO data across the MagnetisMM clinical trial program.

Roger Dansey, M.D., Chief Development Officer for Oncology at Pfizer, emphasized the potential transformative impact of ELREXFIO for people with multiple myeloma. He noted that the MagnetisMM-3 results reinforce the promising efficacy of ELREXFIO in relapsed or refractory settings, characterized by deep and durable responses. The study reported a median progression-free survival (PFS) of 17.2 months, a noteworthy duration among B-cell maturation antigen bispecific antibodies.

During more than two years of follow-up in the MagnetisMM-3 trial, the overall response rate (ORR) for patients on ELREXFIO reached 61.0%, with 37.4% achieving a complete response rate (CRR). Responses improved over time, with the median duration of response (DOR) not reached. At the two-year mark, the estimated DOR rate was 66.9% for all responders, and 87.9% for patients with a complete response or better. The median PFS for patients with a complete response or better was also not reached, with an estimated two-year PFS rate of 90.6%.

MagnetisMM-3 investigator Mohamad Mohty, M.D., Ph.D., highlighted the importance of these findings given the limited therapeutic options for people with relapsed or refractory multiple myeloma. He pointed out that the advanced patient population in the study typically faces poorer outcomes.

The safety profile of ELREXFIO in the MagnetisMM-3 trial was consistent with previous observations. A small number of patients (4.1%) experienced secondary primary malignancies (SPMs), all of which were squamous cell carcinoma of the skin. There were no reports of hematological SPMs. Due to the risks of cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS), close monitoring is recommended after administration of the initial doses. In the European Union, precautionary hospitalization is not mandatory.

Based on the MagnetisMM-3 results, ELREXFIO received accelerated approval from the U.S. Food and Drug Administration (FDA) in August 2023 for treating adult patients with RRMM who have undergone at least four prior lines of therapy. This approval is subject to verification of clinical benefit in a confirmatory trial. Furthermore, the European Commission granted conditional marketing authorization for ELREXFIO in December 2023 for the same patient population who have received at least three prior therapies.

ELREXFIO has also been approved in Switzerland, Brazil, and Canada under Project Orbis, a framework designed to expedite oncology drug approvals among international partners. Australia and Singapore are also participating in Project Orbis. In addition, the Medicines and Healthcare products Regulatory Agency (MHRA) in Great Britain has granted authorization for ELREXFIO for RRMM.

Pfizer's ongoing MagnetisMM clinical development program is exploring elranatamab across a broad range of multiple myeloma patients, from relapsed or refractory to newly diagnosed. The program includes several registrational-intent trials investigating elranatamab as monotherapy and in combination with other therapies. These include MagnetisMM-4, MagnetisMM-5, MagnetisMM-6, MagnetisMM-7, and MagnetisMM-32, addressing different patient subsets and treatment stages.

MagnetisMM-3 is an open-label, multicenter, non-randomized Phase 2 study focusing on ELREXFIO monotherapy in multiple myeloma patients refractory to at least one proteasome inhibitor, one immunomodulatory drug, and one anti-cluster of differentiation 38 antibody. The study includes two cohorts based on previous treatment with B-cell maturation antigen-directed therapy. The primary endpoint is the objective response rate, with secondary endpoints including duration of response, progression-free survival, minimal residual disease negativity rate, overall survival, and safety.

Multiple myeloma (MM) is an aggressive and currently incurable blood cancer affecting plasma cells in the bone marrow. Over 50,000 new cases are diagnosed annually in Europe, with more than 187,000 new cases worldwide. About 40% of MM patients do not survive beyond five years after diagnosis, often requiring multiple lines of therapy due to frequent relapses. ELREXFIO represents a promising treatment option aimed at improving disease control and quality of life for these patients.