Elranatamab Delivers Durable Responses in Relapsed Myeloma With Reduced Dosing

Data from a US subgroup analysis of the MagnetisMM-3 trial (NCT04649359) indicate that elranatamab brings about deep and lasting responses in people with relapsed or refractory multiple myeloma.

At the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting, the latest results from the US subgroup of the study were provided, along with a discussion of how less frequent elranatamab doses worked and were safe for patients who had received many previous treatments.

The first six cycles involved an initial subcutaneous dose of 76 mg elranatamab once a week, after use of smaller doses to try to prevent cytokine release syndrome (CRS). Patients who had a partial response that lasted for 2 months were permitted to begin every-other-week doses of the drug, which could then be changed to once-monthly doses. The analysis was performed with 47 US patients from Cohort A; none had previous exposure to B-cell maturation antigen–directed treatment.

The patients had gone through an average of five different treatments (range, 2-22) before being enrolled. Almost all patients (93.6%) failed to respond to three or more classes of drugs, and more than half (46.8%) did not respond to five or more drugs. Seventeen percent of the patients were Black or African American. Median follow-up was 33.8 months.

Of all the patients in the US subgroup, 66.0% showed an overall response, and 42.6% experienced a complete or response. The median duration of response was not reached, and at 30 months, the probability of maintaining a response was 65.7%. Patients who received elranatamab had a median progression-free survival of 27.3 months.

All patients reported treatment-related adverse events and 78.7% were grade 3 or 4. Infections were reported in 70.2% of patients; 40.4% of infections were grade 3 or 4, but none were grade 5. More than 50% of the patients were given immunoglobulin replacement. Most patients were given preventive antivirals (80.9%), and some were given antibiotics (14.9%).

Cytokine release syndrome was found in 61.7% of patients, and all cases were grade 1 or 2. The incidence of mild immune effector cell–associated neurotoxicity syndrome (ICANS) was 8.5% in the study group.

It is important to note that 22 patients switched to every-other-week dosing and another eight switched to once-monthly dosing, demonstrating that less frequent dosing works and may offer patients better convenience and quality of life.