Eculizumab as Additional Rescue Therapy in Myasthenic Crisis.

Eculizumab is a monoclonal antibody blocking the terminal complement protein C5. As demonstrated in the phase III randomized, placebo-controlled, REGAIN clinical trial, eculizumab is efficacious in acetylcholine receptor antibody (AChR-Ab)-positive refractory generalized myasthenia gravis (gMG) (Myasthenia Gravis Foundation of America-MGFA class II-IV). It has not been studied in severe myasthenic exacerbation or myasthenic crisis (MGFA V). A 73-year-old man diagnosed with myasthenia gravis AChR-Ab positivity came to our observation for symptoms of bulbar and ocular weakness and unresponsiveness or intolerability to conventional immunosuppressive therapies (prednisone and azathioprine). Due to the recurrent clinical worsening with intubation over a short-term period, the patient was treated with eculizumab. After 15 days of eculizumab treatment, we observed a significant recovery of clinical condition. We discharged the patient to an outpatient regimen, where he is continuing with maintenance doses of eculizumab and slowly tapering steroid intake. The use of eculizumab in myasthenic crises is still anecdotal. Our case aims to provide eculizumab benefit for refractory severe gMG in a practical, real-world setting beyond the criteria of the REGAIN study. Further studies are needed to evaluate the efficacy and safety of eculizumab in myasthenic crises.