Dr Hirbe on Long-Term Efficacy and Safety Outcomes With Mirdametinib in Symptomatic NF1-PN

"The key take-home [message] from the long-term follow up phase is that patients are on this medication longer, then we end up seeing both more patients who actually respond and have at least a 20% shrinkage in their tumor, [as well as] a significantly increased number of patients with deep responses."

Angela C. Hirbe, MD, PhD, an associate professor of medicine in the Division of Oncology at Washington University School of Medicine, shared long-term follow-up results from the phase 2b ReNeu trial (NCT03962543) evaluating mirdametinib (Gomekli) in neurofibromatosis type 1 (NF1)–associated symptomatic plexiform neurofibroma (PN).

Mirdametinib was the first FDA-approved MEK1/2 inhibitor for both adults and children 2 or more years of age with NF1 who have symptomatic PN not amenable to complete resection. This regulatory decision was supported by initial data from ReNeu, which demonstrated a confirmed overall response rate (cORR) of 41% (95% CI, 29%-55%) in adult patients and 52% 95% CI, 38%-65%) in the pediatric cohort.

Results from approximately 9 months after the prior data cutoff were presented at the 2025 SNO Annual Meeting, which showed that this cORR was improved with a longer duration of mirdametinib administration, Hirbe reported. A greater number of patients achieved a response, defined as at least a 20% shrinkage in their tumor, and there was a significantly increased number of patients who had deep responses, defined as those patients who experienced a greater than 50% reduction in the volume of their PNs, she detailed. These deep responses were achieved in both adult and pediatric populations, Hirbe noted. Importantly, the long-term follow-up phase identified no additional safety signals with mirdametinib; the agent continued to be well tolerated with a manageable safety profile, Hirbe noted.

Overall, these findings affirm the lasting responses achieved with mirdametinib in this patient population and indicate that patients who are able to continue on the medication for longer are more likely to experience tumor regression, and benefit in terms of improvement in pain and quality of life, Hirbe concluded.