Pfizer: Pfizer Presents First Data from Planned Interim Analysis of Pivotal Phase 2 MagnetisMM-3 Trial of BCMA-CD3 Bispecific Antibody Elranatamab Under Investigation for Relapsed/Refractory Multiple Myeloma

Pfizer Inc. (NYSE: PFE) today announced new data from a planned interim analysis of the Phase 2 MagnetisMM-3 registration-enabling trial of elranatamab in people with relapsed/refractory multiple myeloma (RRMM) whose disease is refractory to at least one agent in each of three major classes of medications approved for the disease. These data are being presented today during an oral abstract session at the 2022 American Society of Clinical Oncology Annual Meeting (ASCO) (Abstract # 8006).

Elranatamab is an investigational B-cell maturation antigen (BCMA) CD3-targeted bispecific antibody in development for the treatment of multiple myeloma (MM). MagnetisMM-3 is an open-label, multicenter, single arm, Phase 2 study evaluating the safety and efficacy of elranatamab monotherapy in patients with RRMM. The participants included in this study represent a particularly difficult-to-treat MM patient population: 95.7% of participants in the current interim analysis population had triple-class refractory disease and 39.4% had penta-drug refractory disease.1

In this interim analysis, safety and efficacy was analyzed in 94 patients who had received at least one dose of elranatamab (Cohort A – BCMA-naïve) as of the data cutoff on March 23, 2022. Patients received subcutaneous (SC) elranatamab 76 mg weekly (QW) with a 2-step-up priming dose regimen administered during the first week. With a median follow up of 3.71 months, initial efficacy results showed that the objective response rate for elranatamab was 60.6%. As of the data cut-off, 89.5% of objective responders were ongoing without confirmed progression or death.

“Bispecific antibodies hold promise as the next breakthrough in the treatment of multiple myeloma. These data represent an important step forward as we look to bring elranatamab as a potential innovative new treatment to people living with relapsed or refractory multiple myeloma, where there is high need,” said Chris Boshoff, M.D., Ph.D., Chief Development Officer, Oncology, Pfizer Global Product Development. “We are encouraged by these early efficacy and safety results, which suggest elranatamab may have a manageable safety profile coupled with early promising clinical responses. We look forward to the final analysis from MagnetisMM-3, which is expected later this year.”

The results also suggested 76 mg of elranatamab QW may have a manageable safety profile in patients with triple-class refractory MM. The most common treatment emergent adverse events (TEAEs) were hematologic AEs- anemia (43.6%), neutropenia (38.3%), thrombocytopenia (28.7%) and lymphopenia (25.5%); and cytokine release syndrome (CRS) (60.6%). The 2-step-up priming regimen is intended to help mitigate the rate and severity of CRS, and the CRS profile appears to be predictable with the majority of events confined to the first two doses (88.4%) or first three doses (98.6%). Of the 90 patients who received the 2-step-up priming regimen, all CRS were Grade 1 (40.0%) or 2 (18.9%). Additionally, immune effector cell-associated neurotoxicity syndrome (ICANS) occurred in 2.2% of patients, all Grade 2 or less.

These results being presented at ASCO are the first data to be disclosed from the MagnetisMM-3 study. The trial is still ongoing to the primary endpoint analysis with results expected later this year, which, if positive, would form the basis of potential regulatory filings. These data also support continued development of elranatamab in the robust MagnetisMM program, with other trials planned or ongoing both as monotherapy and in combination with standard or novel therapies.

Comments are closed.