Do complement inhibitors improve outcomes for myasthenia gravis patients?
Complement inhibitors are a class of drugs that block part of the immune system called the complement cascade, which can damage the nerve-muscle connection in myasthenia gravis (MG). For patients with acetylcholine receptor antibody-positive (AChR-Ab+) generalized MG, these drugs have been shown to improve muscle strength, daily activities, and quality of life. Several large trials and real-world analyses support their use, especially for people who do not respond well to standard treatments.
What the research says
A 2025 systematic review and meta-analysis of six randomized controlled trials (739 patients) found that complement inhibitors (eculizumab, ravulizumab, zilucoplan) and FcRn blockers significantly improved MG symptoms compared to placebo 6. Specifically, patients taking these drugs had an average 1.7-point greater improvement on the MG-ADL scale (a measure of daily functioning) and 2.7-point greater improvement on the Quantitative Myasthenia Gravis (QMG) score (a measure of muscle strength) 6. The odds of achieving a meaningful clinical response were more than doubled 6.
Two landmark trials provide key evidence. The REGAIN trial (2017) showed that eculizumab led to greater improvements in MG-ADL and QMG scores than placebo in patients with refractory (treatment-resistant) AChR-Ab+ generalized MG 9. A 2022 trial of ravulizumab, a longer-acting complement inhibitor, also found significant benefits: MG-ADL improved by 3.1 points with ravulizumab versus 1.4 with placebo, and QMG improved by 2.8 versus 0.8, with improvements seen within one week 8.
Real-world data from a 2025 German study of 153 patients compared complement inhibitors (eculizumab, ravulizumab) with the FcRn blocker efgartigimod 10. Both approaches led to rapid clinical improvements and allowed reductions in steroid (prednisolone) doses, though 20-49% of patients did not have an adequate response 10. Importantly, no new safety concerns were identified 10. Complement inhibitors are generally reserved for AChR-Ab+ patients who have not responded to other therapies, and they require vaccination against meningococcal infection before starting treatment 9.
What to ask your doctor
- Am I a candidate for a complement inhibitor like eculizumab, ravulizumab, or zilucoplan?
- What are the potential side effects and risks, especially the need for meningococcal vaccination?
- How do complement inhibitors compare with other newer treatments like FcRn blockers for my situation?
- Will my insurance cover these medications, and what is the expected out-of-pocket cost?
- How quickly might I see improvement, and how will we monitor my response?
This question is drawn from common patient questions about Rheumatology and answered using cited medical research. We do not provide individualized advice.