Therapeutic approach to myasthenia gravis treatment in the era of new biologics — review of existing and upcoming therapies

Myasthenia gravis (MG) is a heterogenous autoimmune disease affecting the neuromuscular junction, which in many patients leads to devastating symptoms significantly influencing patients' lives or causing life-threatening episodes. The incidence and prevalence of myasthenia are growing worldwide. By definition, MG is characterized by muscle weakness exacerbated with activity and improving with rest. A total of 15-20% of patients during the course of the disease develop myasthenic crisis (MC), defined as respiratory insufficiency requiring intubation, with a high mortality rate. Approximately 30-50% of patients have unsatisfactory response to the standard treatment. Moreover, the standard of care (SoC), although efficient in most of patients, may be complicated by significant side effects, in most cases resulting from long-term treatment with glucocorticosteroids. In recent decades, new therapies have been approved for MG, including neonatal Fc receptor (FcRn) antagonists and complement component 5 (C5) inhibitors, as add-on to standard therapy. They showed efficacy and safety, even in patients previously considered as resistant MG. In several cases their rapid onset of action led to successful use as rescue treatments in impending crisis. Furthermore, it is noteworthy that new biologics show relevant steroid-sparing effects. This review summarizes new therapeutic approaches already approved for MG and introduces upcoming ones.