What Does MagentisMM-3 Data Tell Us About Elranatamab?

Ajay Nooka, MD, FACP, of the Winship Cancer Institute at Emory University, discusses data from the single-arm phase II MagnetisMM-3 trial of elranatamab (ELREXFIO) in multiple myeloma (MM).

The recent US Food and Drug Administration (FDA) accelerated approval of the bispecific antibody is based upon results from the MagnetisMM-3 trial. The approval is for adults with relapsed or refractory MM who have received at least four prior lines of therapy, including a proteasome inhibitor, an immunomodulatory agent, and an anti-CD38 monoclonal antibody.

This parallels the characteristics of the “heavily refractory patient population” included in the trial, Dr. Nooka said. Patients in the trial had a median of six prior lines of therapy and were refractory to a proteasome inhibitor, an immunomodulatory agent, and an anti-CD38 monoclonal antibody.

“For these patients, the standard of care has not been as clearly defined as we would like,” he said. “So, BCMA became the target of choice in this patient population.”

Patients in the trial received two priming doses of the bispecific antibody prior to receiving the target dose. This was done to “minimize the risk” of cytokine release syndrome (CRS), Dr. Nooka said. The primary endpoint of the trial was the overall response rate (ORR). Dr. Nooka said they found a 61% ORR in the study, with a very good partial response rate of over 58%.

Dr. Nooka also spoke about what the accelerated approval means for patients with multiple myeloma.

“When you see the heavy depths of responses among these patients that are heavily refractory … we have not been used to seeing these responses in the past,” he said. “Even two years ago, we were never able to see these responses. That’s why it makes a huge impact in this patient population.”

Dr. Nooka outlined the adverse events (AEs) seen in the trial, emphasizing that understanding the side effects is “essential.” These side effects include CRS, immune effector cell-associated neurotoxicity syndrome, infection, and cytopenias. He spoke about management strategies for AEs, as well as the frequency and severity of AEs observed in the study.

For example, with CRS, which is a “very predictable toxicity” in this setting, there are plans in place, Dr. Nooka said.

“There is a hospitalization recommended by the REMS program, which is the Risk Evaluation Mitigation System,” he said. “This program recommends patients who receive elranatamab in the priming dose to have a hospital stay of 48 hours after, and one day or 24 hours after the second priming dose, and then the patient can be released. This is a very important aspect of how we manage cytokine release syndrome.”

Dr. Nooka also emphasized the importance of prophylaxis for infections and understanding how to manage predictive toxicities with elranatamab.

Overall, the “new treatment is clearly needed and clearly beneficial for this specific patient population,” Dr. Nooka said.

Elranatamab previously received Breakthrough Therapy Designation from the FDA in November 2022. The FDA granted priority review to the Biologics License Application in February 2023.