The treatment course of myasthenia gravis with complement C5 inhibitor

Abstract

Objective : Eculizumab and ravulizumab are monoclonal antibodies targeting complement C5 and are used for the treatment of anti–acetylcholine receptor antibody–positive generalized myasthenia gravis (MG). The correct use of these drugs is important, given their costliness and the potential for the serious adverse effect of invasive meningococcal infection. Thus, data on the outcomes of treatments using these drugs are a vital source of information. The present study evaluated the treatment course of patients with MG who received complement C5 inhibitors at the study center and discusses the therapeutic outcomes in light of the findings of Japanese registry studies.

Methods : The present study retrospectively analyzed the disease and treatment courses of eight of 75 patients with MG who were admitted to the study center between January and December 2024 for MG and received eculizumab or ravulizumab.

Results : The MG cases in the eight patients comprised the early–onset (62.5%), thymoma–associated (25.0%), and late–onset (12.5%) subtypes. Of five patients who began their treatment with eculizumab, one, one, and three patients continued the treatment, discontinued the treatment after improvement, and switched to ravulizumab, respectively. Three patients who began their treatment with ravulizumab continued the treatment. Quantitative MG (QMG) scores improved by one to 23 points in six patients, two of whom experienced clinical deterioration after switching from eculizumab to ravulizumab. The QMG score of the remaining two patients declined by two points despite improvement in the subjective symptoms. The daily prednisolone dosage remained unchanged in five patients and was reduced by 1 to 5 mg in three patients who were receiving more than 10 mg/day.

Conclusion : The QMG score and subjective symptoms of all the patients improved with complement C5 inhibitor therapy, but clinical deterioration was observed in the patients who switched from eculizumab to ravulizumab. Dosage reduction or discontinuation of prednisolone in patients receiving <10 mg/day should be carefully considered in light of the pathophysiology of MG. If symptoms improve with complement C5 inhibitor therapy, discontinuing the therapy may be considered.