Treatment with C5 Inhibitor Associated with Significant, Clinically Meaningful Improvements in Generalized Myasthenia Gravis Disease Severity

Treatment with gefurulimab (Alexion Pharmaceuticals, Boston, MA), an investigational complement C5 inhibitor, was associated with significant and clinically meaningful improvements in disease severity for adults with anti-acetylcholine receptor positive (AChR+) generalized myasthenia gravis (gMG). In the topline results from the phase 3 PREVAIL clinical trial (NCT05556096), the study’s primary and secondary end points were met, with those treated with gefurulimab demonstrating improved Myasthenia Gravis Activities of Daily Living (MG-ADL) scores at 26 weeks compared with those taking placebo.

Gefurulimab is a dual-binding nanobody designed for self-administration once-weekly. It targets complement C5 to prevent terminal complement cascade activation. The medication is designed to provide sustained disease control without the need for in-clinic infusion, potentially improving patient adherence and autonomy.

In the global, phase 3, randomized, double-blind, placebo-controlled PREVAIL clinical trial, 260 adults with AChR+ gMG across 20 countries were randomized 1:1 to receive treatment with gefurulimab or placebo for 26 weeks. The primary end point was change from baseline in MG-ADL total score, with secondary end points evaluating other measures of disease improvement. According to a statement released by Alexion Pharmaceutical’s parent company, AstraZeneca (Cambridge, United Kingdom), results at 26 weeks show that treatment with gefurulimab met the study’s primary end point and all secondary end points. Treatment with gefurulimab was also well-tolerated with a safety profile consistent with other C5-inhibiting drugs for gMG.

“Rapidly fluctuating symptoms and the unpredictable disability associated with gMG can affect nearly every aspect of a patient's life, making early intervention and sustained disease control a critical treatment goal,” said Kelly Gwathmey, MD, Principal Investigator for the PREVAIL trial. “A once-weekly, self-administered C5 treatment option would offer patients greater convenience and independence in managing their condition, empowering them to have more control over their therapy.”

See also: Patient-Reported Outcome Measures in Neuromuscular Disorders by Brianne Kelly, MD, Saba Nawaz, MD, and Kelly G. Gwathmey, MD.