Refractory myasthenia gravis

Abstract

Although conventional therapies for myasthenia gravis (MG) are effective in most patients, a subset of patients remains resistant to treatment with persistent or progressive symptoms. Some patients are unable to tolerate conventional therapies due to severe side effects or contraindications from comorbidities. Although no standard definition currently exists and the use of the term "refractory MG" has varied across studies, it has commonly been used to refer to these patients for whom conventional therapies are not useful. Demographically, this subgroup has been reported to comprise up to 14.8% of MG patients and include a higher proportion of patients who are female, have a younger age of onset and have anti-muscle specific tyrosine kinase antibodies compared to the general MG population. Novel therapies are indicated for this group, and various medical and surgical options have been explored such as rituximab, cyclophosphamide, eculizumab and thymectomy. In particular, rituximab has recently met with wide interest for its relative safety and long-lasting effectiveness in diverse patients, as demonstrated in multiple small studies. Further investigation into these therapies is needed. This chapter focuses on these novel treatment options that have been studied for use in refractory MG.