Survival in hard-to-treat myeloma extended with Elrexfio treatment

Patients continued without signs of disease progression for nearly 1.5 years

Patricia Inácio, PhD avatar

by Patricia Inácio, PhD |

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Pfizer’s Elrexfio (elranatamab) extends the lives of adults with relapsed or refractory multiple myeloma (RRMM) who received at least two prior lines of therapy and whose cancer has worsened since their last treatment.

Median overall survival was 24.6 months, or more than two years, according to data from the 123 RRMM patients who received Elrexfio as part of the first patient group in the ongoing Phase 2 MagnetisMM-3 trial (NCT04649359). The group included patients who hadn’t received treatment targeting B-cell maturation antigen (BCMA), a protein at the surface of myeloma cells. The patients lived without signs of disease progression for a median of 17.2 months, or nearly 1.5 years.

“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,” Roger Dansey, MD, chief development officer of oncology at Pfizer, said in a company press release. “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.”

The findings were presented at the European Hematology Association (EHA) Hybrid Congress, held June 13-16 in Madrid, in a poster titled “Long-term survival after elranatamab monotherapy inpatients with relapsed or refractory multiple myeloma (RRMM): Magnetismm-3.”

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How does Elrexfio work in myeloma?

Multiple myeloma is marked by the abnormal growth of plasma cells, a type of immune cell that produces antibodies. Despite the many approved myeloma treatments, patients often fail to respond to available medications or relapse after treatment.

“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 Mohamad Mohty, MD, PhD, a researcher of the MagnetisMM-3 trial and a professor of hematology at the Saint-Antoine Hospital and Sorbonne University, Paris.

Elrexfio is a dual-target antibody that targets the BCMA protein and CD3, a cell surface protein on immune T-cells. Its dual mode of action brings T-cells in close proximity to the cancer cells to better elicit their elimination. It’s been conditionally approved in the U.S., Canada, and the European Union for adults with RRMM who’ve received at least three to four prior lines of therapy, including a proteasome inhibitor, an immunomodulatory agent, and an anti-CD38 antibody.

The approvals were based on data from the first group of patients in the ongoing Phase 2 MagnetisMM-3 study, which tested the therapy in RRMM patients who had not responded to at least one proteasome inhibitor, one immunomodulatory drug, and one anti-CD38 antibody. Participants had previously received a median of five prior lines of therapy (range, 2-22).

After two loading doses in the first week, participants received an injection of 76 mg Elrexfio once a week in four-week cycles. Those achieving a partial response or better after receiving six or more cycles could move to dosing every other week.

Results showed 61% of patients responded to treatment over a median follow-up of more than a year, with 35% achieving a complete response or better, meaning no signs of the cancer.

Long-term results of Elrexfio

Here, researchers presented MagnetisMM-3’s longer-term results regarding response rates and survival outcomes.

After more than two years of follow-up, 61% of patients responded to Elrexfio. During this period, more than 37.4% had a complete cancer eradication, and the median duration of response hadn’t been reached, meaning most patients were still responding to the therapy and had no signs of disease progression.

There was an 66.9% probability of maintaining a treatment response at two years of follow-up, with that increasing to 87.9% among those with a complete or better response.

Also, patients lived a median of 24.6 months and for a median 17.2 months without disease worsening or death. This latter outcome, called progression-free survival, hadn’t yet been reached in those with a complete or better response, again meaning most of these patients were still alive and without disease progression.

At two years, 90.6% of patients were estimated to live without signs of disease worsening.

“These impactful overall survival data are particularly encouraging given the very advanced patient population with characteristics associated with poorer outcomes,” Mohty said.

The safety and tolerability profile of Elrexfio was consistent with what’s been reported, without new safety concerns over longer follow-up.

Elrexfio’s full approval depends on the complete results from the  confirmatory Phase 3 MagnetisMM-5 trial (NCT05020236), which is enrolling up to 761 adults with RRMM who’ve been treated with Revlimid (lenalidomide) and a proteasome inhibitor. It’s expected to end in 2027.