Pfizer's ELREXFIO beats standard regimens in Phase 3 myeloma trial
The 523-patient study met its progression-free survival endpoint, but Pfizer withheld the comparative effect size and a filing date.
Adrian Kessler
ELREXFIO beat standard regimens on progression-free survival as Pfizer Inc. NYSEPFE reported a positive Phase 3 trial in previously treated multiple myeloma on Tuesday. An estimated 68 per cent of ELREXFIO patients were alive without disease progression at 18 months.
The Oct. 27 release said MagnetisMM-32 enrolled 523 adults previously treated with anti-CD38 therapy and lenalidomide. Pfizer plans global regulatory submissions but gave no filing deadline or date for presenting detailed results.
Pfizer is a large New York pharmaceutical company selling medicines and vaccines worldwide, with an oncology business spanning marketed treatments and experimental drugs.
Pfizer shares NYSEPFE closed at US$29.79 in New York at 4:02 p.m. EDT on Oct. 26, before the announcement. That closing price does not measure the market's response to Tuesday's results.
The randomized, open-label trial compared ELREXFIO alone with a physician's choice of three regimens. Those were elotuzumab, pomalidomide and dexamethasone; pomalidomide, bortezomib and dexamethasone; or carfilzomib and dexamethasone.
Blinded independent reviewers assessed the primary endpoint, progression-free survival, which measures time before disease progression or death. Pfizer called the reduction in risk statistically significant but did not disclose the hazard ratio, confidence interval, exact p value or control-arm progression-free survival.
Median progression-free survival had not been reached with ELREXFIO, while overall-survival results remained immature. Without the comparative figures, the release does not establish the size of the benefit over the control regimens.
Severe Infections Were More Frequent
Grade 3 or higher infections occurred in 27.5 per cent of ELREXFIO patients versus 18.1 per cent of controls. Fatal infections occurred in 0.8 per cent versus 1.6 per cent, respectively, and Pfizer reported no new safety signals.
Pfizer said infection prevention was instituted from the study's beginning. Patients received initial step-up doses before weekly injections, with dosing subsequently moving to every two weeks and then monthly.
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ELREXFIO links the BCMA protein on myeloma cells to CD3 on immune-system T cells, helping direct those cells against the cancer. Its existing U.S. accelerated approval covers patients who have received at least four prior treatment lines.
The FDA's Aug. 14, 2023 approval notice described evidence from a single-arm study measuring response rate and response duration. MagnetisMM-32 instead enrolled patients after at least one prior treatment line; Tuesday's release did not describe an FDA agreement on its design.
"The MagnetisMM-32 results are particularly compelling given the rigorous and clinically relevant benchmark of three established standard-of-care regimens," University of Miami myeloma division chief C. Ola Landgren said in Pfizer's release.
Competition Has Already Moved Into Earlier Treatment
Johnson & Johnson NYSEJNJ announced on March 5 that the FDA approved TECVAYLI plus DARZALEX FASPRO after at least one prior treatment line, including a proteasome inhibitor and an immunomodulatory agent. Its combination trial reported a hazard ratio of 0.17 for progression or death against its control regimens.
That result comes from a different trial and cannot establish relative efficacy against ELREXFIO. Pfizer is pursuing earlier use with a single medicine in patients already exposed to anti-CD38 therapy and lenalidomide.
The iShares Biotechnology ETF NASDAQIBB closed at US$208.69 at 4:00 p.m. EDT on Oct. 26, providing a sector benchmark before Pfizer's announcement.
Pfizer's Aug. 4 financial release reported US$5.3 billion invested in internal research and development during the first half of 2026. The myeloma result adds another development milestone ahead of its next quarterly update.
Read more: Pfizer details 25-strain infant vaccine data as pivotal trials advance
Pfizer's next quarterly results are scheduled for Nov. 3, when investors will get updated financial performance. A dated ELREXFIO submission plan remains undisclosed in Tuesday's release.
