Complement C5 inhibitor: revolutionizing treatment for refractory anti-acetylcholine receptor antibody positive generalized myasthenia gravis

Background:Recently, increasing evidence has demonstrated the rapid beneficial effect of monoclonal antibodies blocking the terminal complement protein C5 in refractory generalized myasthenia gravis (gMG); therefore, they have emerged as a promising option for fast-acting therapy (FT).Case Report: We describe the case of a 21-year-old female with a 4-year history of non-thymomatous anti-acetylcholine receptor antibody (anti-AChR Ab) positive refractory gMG (Myasthenia Gravis Foundation of America [MGFA] class V) who responded to complement C5 inhibitor within the first week, achieving minimal symptom expression within 2 months.This rapid-onset efficacy challenged the existing understanding of antibody-mediated destruction of AChR, where instant restoration of neuromuscular junction neurotransmission from recovery of the destroyed postsynaptic membrane of the motor endplate and reduction in the number of AChR receptors is theoretically not possible with membrane attack complex inhibition. Conclusion:The rapid target attainment effect of complement inhibition can be considered as an additional novel indication for conventional FT.