Pfizer Initiates Pivotal Phase 2 MagnetisMM-3 Trial of BCMA-CD3 Bispecific Antibody Elranatamab

NEW YORK–(BUSINESS WIRE)– Pfizer Inc. (NYSE:PFE) today announced that the first participant has been dosed in the registration-enabling Phase 2 MagnetisMM-3 study (NCT04649359) of elranatamab (PF-06863135), an investigational B-cell maturation antigen (BCMA) CD3-targeted bispecific antibody, in patients with relapsed/refractory multiple myeloma. The study evaluates the efficacy and safety of elranatamab, administered subcutaneously, in patients with disease that is refractory to at least one agent in each of three major classes of medications approved for multiple myeloma. The study’s estimated primary completion date is June 2022.

Elranatamab has also been granted Fast Track Designation by the U.S. Food and Drug Administration (FDA). Fast Track is a process designed to facilitate the development, and expedite the review, of new drugs and vaccines that are intended to treat or prevent serious conditions that have the potential to address an unmet medical need.1

“The initiation of MagnetisMM-3, our pivotal trial, is an important step in our robust and accelerated development program for elranatamab,” said Chris Boshoff, M.D., Ph.D., Chief Development Officer, Oncology, Pfizer Global Product Development. “Bispecific antibodies hold promise as the next potential breakthrough in the treatment of multiple myeloma. We are highly encouraged by early data with subcutaneous elranatamab, which was discovered and developed at Pfizer and designed to enhance safety and convenience.”

At the Virtual American Society of Hematology (ASH) Annual Meeting and Exposition in December 2020, Pfizer presented encouraging data from an ongoing Phase 1 trial of elranatamab (MagnetisMM-1) demonstrating manageable safety and high response rates in patients with relapsed/refractory multiple myeloma including three patients whose disease relapsed on or progressed after prior BCMA-targeted therapies. At the highest dose level, which informed the dose selected for the Phase 2 study, 83% of patients achieved a clinical response. Safety was manageable across all subcutaneous dose levels with no dose-limiting toxicities observed.

Bispecific antibodies are a novel type of cancer immunotherapy that bind to and engage two different targets at once. One arm binds directly to specific antigens on cancer cells and the other activates and brings a person’s own T-cells from the immune system closer to kill the cancer cells.

Elranatamab is a bispecific antibody designed to bind to BCMA which is highly expressed on the surface of multiple myeloma cells, and the CD3 receptor found on the surface of cancer-fighting T-cells, bridging them together to activate an immune response. Binding affinity to BCMA and CD3 has been optimized, to potentially elicit more potent T-cell-mediated anti-myeloma activity. Subcutaneous administration of elranatamab is intended to allow higher doses than intravenous administration without increasing adverse events. In addition to MagnetisMM-3, other trials of elranatamab in multiple myeloma are planned both as monotherapy and in combination with standard or novel therapies.

“Second and later relapses are unfortunately all too common in multiple myeloma and can be devastating to patients as remissions tend to be shorter and the disease may be more aggressive,2” said Alexander M. Lesokhin, M.D., lead investigator and hematologic oncologist at Memorial Sloan Kettering Cancer Center. “Targeting BCMA is a promising area of innovation in multiple myeloma.”

“Living with multiple myeloma can often be a roller coaster, of both hope and disappointment. It can be so up and down and nerve wracking as it’s often the case that a new treatment gets started, only to end in another relapse,” said Susie Novis Durie, Founder & President of the International Myeloma Foundation. “Continued research to develop new treatments with novel mechanisms of action is essential to improve outcomes for these patients.”

About the MagnetisMM-3 Phase 2 Trial

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