Alexion, AstraZeneca plc (LON:AZN) Rare Disease’s Klygefa (gefurulimab) has been recommended for approval in the European Union (EU) as an add-on to standard therapy for the treatment of generalised myasthenia gravis (gMG) in adults who are anti-acetylcholine receptor (AChR) antibody-positive. If approved, Klygefa will be the first and only dual-binding nanobody C5 inhibitor for this patient population.
The Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) based its positive opinion on results from the pivotal PREVAIL Phase III trial, which were presented at the Myasthenia Gravis Foundation of America (MGFA) Scientific Session during the American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM) 2025 Annual Meeting and published in JAMA Neurology.1
gMG is a rare autoimmune disorder characterised by reduced muscle function and severe muscle weakness.2 An estimated 82,500 people are diagnosed with gMG in Europe 5 countries (Germany, France, UK, Italy and Spain) with 66,000 being AChR-positive.3
Tobias Ruck, MD, Director Department of Neurology, BG University Hospital Bergmannsheil Bochum, Ruhr-University Bochum and investigator in the trial, said: “For people living with gMG, unpredictable symptoms can quickly become incapacitating or life-threatening. In the PREVAIL Phase III trial, gefurulimab demonstrated the ability to improve measures of disease severity and daily function with the convenience of once weekly subcutaneous self-administration, as early as one week and through the 26-week study period. With this positive CHMP opinion patients may soon have the option of a novel treatment option that could help them spend less time thinking about their care and more time living their lives.”
Marc Dunoyer, Chief Executive Officer, Alexion, said: “This positive CHMP opinion is an important step towards bringing Klygefa, an innovative dual-binding nanobody C5 inhibitor, to people living with gMG in the EU. Building on our pioneering work demonstrating the efficacy of C5 inhibition with Soliris and Ultomiris, Klygefa is designed to offer rapid and sustained symptom control with convenient once-weekly subcutaneous self-administration via autoinjector.”
Results from the PREVAIL trial showed that Klygefa met its primary endpoint, demonstrating improvement from baseline in Myasthenia Gravis Activities of Daily Living (MG-ADL) total score at week 26 compared to placebo (treatment difference: -1.6 [95% CI: -2.4, -0.8], p<0.0001). A clinically meaningful improvement was observed as early as week one, and was sustained through week 26.1
Klygefa was generally well-tolerated, and the safety profile was consistent with previous trials of C5 inhibitors eculizumab and ravulizumab in gMG.1
Klygefa is approved in Japan and other countries for certain adults with gMG. Regulatory submissions based on the PREVAIL results are under review in the US, China and additional countries.
References
1. Gwathmey KG, Saccà F, Howard JF Jr, et al. Efficacy and safety of gefurulimab in generalized myasthenia gravis: the PREVAIL phase 3 randomized clinical trial. JAMA Neurol. 2026 Jul 27.
2. Jung-Plath W, et al. Assessment of myasthenia gravis patients’ quality of life. The Journal of Neurosurgical Nursing. 2023;12(2):74-83.
3. AstraZeneca Data on File – Epidemiology estimates are composed of a triangulation of different data sources including Data Monitor, Decision Resources Group, Kantar Health, and internal input. Accessed September 2026.
