Phase 3 Gefurulimab Trial Results Presented at AANEM 2026
Phase 3 trial findings shared on September 29 at the 2026 annual meeting of the American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM) and covered by Medscape revealed that weekly subcutaneous administrations of the dual-binding nanobody gefurulimab correlated with a decreased reliance on rescue treatments, a numerical decrease in clinical worsening, and a lower rate of hospital admissions among adults suffering from anti-acetylcholine receptor antibody-positive generalized myasthenia gravis.
Generalized myasthenia gravis is a rare autoimmune neuromuscular disorder. Approximately 85% of patients with the condition are positive for anti-acetylcholine receptor antibodies, which bind to receptors at the neuromuscular junction, disrupting nerve-to-muscle signaling and triggering an immune response. Study investigator Nicholas S. Streicher, MD, assistant professor of neurology at Georgetown University in Washington, DC, explained to Medscape that gefurulimab is a nanobody that inhibits complement component 5 (C5), a key driver of disease.
PREVAIL Trial Design and Primary Endpoint Outcomes
The multicenter, double-blind PREVAIL trial enrolled 260 adult participants with Myasthenia Gravis Foundation of America class II-IV disease. Patients had a mean baseline Myasthenia Gravis Activities of Daily Living (MG-ADL) score of 9 and were randomly assigned to receive either weekly subcutaneous self-injections of gefurulimab or a placebo for 26 weeks. Nearly all participants, specifically 94.6%, completed the 26-week treatment.
As documented previously in JAMA Neurology, the study achieved its primary endpoint by demonstrating a change from baseline in total MG-ADL scores at week 26, showcasing a least-squares mean decrease of 4.2 points for the gefurulimab cohort compared to 2.6 points for the placebo cohort. Overall, gefurulimab was well tolerated, displaying a safety profile matching what has been seen in prior studies of C5 inhibitors for gMG, with no novel safety signals surfacing.
Reduced Hospitalizations and Lower Rescue Therapy Needs
Exploratory outcomes from the trial tracked clinical deterioration, rescue therapy utilization, and hospital-based interventions. Clinical deterioration occurred in nine patients (6.9%) in the gefurulimab group vs 18 (14.0%) in the placebo group. The drug was better — 14% vs 7% — but there wasn’t a statistically significant difference,
noted Streicher.
Rescue medication was needed by seven participants (5.3%) belonging to the gefurulimab arm, whereas 16 participants (12.4%) in the placebo arm required it.
Additionally, gMG-related hospital admissions by the 26-week mark were documented in three individuals (2.3%) of the gefurulimab cohort, contrasting with 12 individuals (9.3%) of the placebo cohort.
The reduced need for rescue therapy and fewer hospitalizations shows exactly how well this drug is working,
Streicher said. The idea is that you could potentially start reducing steroids, which have their own negative health effects as time goes on.
Regulatory Review and Future Treatment Administration
The drug is currently under review by the FDA. Gefurulimab might present several benefits relative to current treatments, such as the ease of subcutaneous self-administration rather than requiring intravenous infusions. Streicher noted that unlike conventional antibodies, which may be cleared from the body during treatments with agents such as IVIG, gefurulimab is designed to remain effective, potentially allowing it to be used in combination with other therapies.
Frequently Asked Questions About Gefurulimab and the PREVAIL Trial
What is gefurulimab and how does it work in myasthenia gravis?
Gefurulimab is a dual-binding nanobody that inhibits the activation of C5, a key driver of disease in anti-AChR antibody-positive gMG.
Who participated in the PREVAIL phase 3 trial?
The study population comprised 260 adults diagnosed with anti-AChR antibody-positive gMG whose illness fell under Myasthenia Gravis Foundation of America class II-IV, alongside a Myasthenia Gravis Activities of Daily Living (MG-ADL) score of 5 or higher. Participants had a mean age of 52.8 years, and 60.4% were female.
What were the main efficacy findings presented at AANEM 2026?
Beyond the primary endpoint reduction in MG-ADL scores, investigators reported that rescue therapy was required in 5.3% of patients in the gefurulimab group vs 12.4% in the placebo group, and gMG-related hospitalization at 26 weeks occurred in 2.3% of patients in the gefurulimab group vs 9.3% in the placebo group.