Gefurulimab Meets Primary and Secondary Endpoints in Phase III PREVAIL Trial for Generalised Myasthenia Gravis

Positive topline results from the global PREVAIL Phase III trial showed that gefurulimab achieved both its primary and secondary endpoints in adults with anti-acetylcholine receptor (AChR) antibody-positive generalised myasthenia gravis (gMG). The investigational therapy demonstrated a statistically significant and clinically meaningful improvement in Myasthenia Gravis Activities of Daily Living (MG-ADL) total scores at week 26 compared with placebo.

All key secondary endpoints were also met, including change from baseline in Quantitative Myasthenia Gravis (QMG) total score at both week four and week 26.

These results were presented at the Myasthenia Gravis Foundation of America (MGFA) Scientific Session during the AANEM Annual Meeting in San Francisco, California.

Early and Sustained Clinical Improvements

Patients treated with gefurulimab experienced a mean treatment difference of -1.6 in MG-ADL total score versus placebo at week 26 (95% CI: -2.4, -0.8; p<0.0001). Clinically meaningful benefits appeared as early as week one and continued throughout the 26-week treatment period.

Similarly, QMG total scores showed improvements by week four (treatment difference: -1.8; 95% CI: -2.5, -1.1; p<0.0001), sustained through week 26 (treatment difference: -2.1; 95% CI: -3.1, -1.1; p<0.0001).

“Results from PREVAIL demonstrating early and lasting benefits in MG-ADL and QMG scores support the potential for gefurulimab to offer an efficacious and convenient self-administered treatment option,” said Dr. Kelly Gwathmey, Principal Investigator and Vice Chair of the MGFA Medical & Scientific Advisory Council.

Safety and Tolerability

Gefurulimab was well-tolerated, with a safety profile consistent with previous C5 inhibitors such as eculizumab and ravulizumab. The incidence of treatment-emergent adverse events (TEAEs) was comparable between treatment and placebo groups. Most adverse events were mild to moderate (Grade 1–2).

• Most common TEAEs (gefurulimab): injection site reactions (9.9%), headache (9.9%), back pain (7.6%)
• Most common TEAEs (placebo): headache (12.4%), diarrhoea (8.5%), upper respiratory infection (7.8%)

No new safety signals were observed.

“Findings from PREVAIL highlight how early and sustained complement inhibition with gefurulimab may translate into meaningful, functional improvement for people living with gMG,” said Dr. Gianluca Pirozzi, Senior Vice President, Development, Regulatory and Safety, Alexion, AstraZeneca Rare Disease.

About the PREVAIL Trial

PREVAIL (ALXN1720-MG-301) is a global, randomised, double-blind, placebo-controlled Phase III study assessing the safety and efficacy of gefurulimab in adults with generalised myasthenia gravis.

• Sample size: 260 patients
• Regions: 20 countries across North America, Europe, Asia, and the Pacific
• Treatment duration: 26 weeks
• Design: 1:1 randomisation to gefurulimab or placebo; once-weekly subcutaneous dosing following an initial loading dose

Participants who completed the trial are continuing in an open-label extension to further assess long-term safety and efficacy.

About Gefurulimab

Gefurulimab is an investigational complement C5 inhibitor designed for subcutaneous self-administration. The dual-binding nanobody targets the C5 protein to prevent overactivation of the complement system while binding to serum albumin to extend half-life, enabling once-weekly dosing.

The therapy has received Orphan Drug Designation in the U.S. for myasthenia gravis.

About Alexion, AstraZeneca Rare Disease

Alexion, the rare disease division of AstraZeneca, focuses on discovering and developing life-changing medicines for patients affected by rare and devastating conditions.

AstraZeneca is a global, science-led biopharmaceutical company with core focus areas in oncology, rare diseases, cardiovascular, renal, metabolism, respiratory, and immunology.

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