Efgartigimod as Fast-Acting Rescue Therapy in Very Late-Onset Myasthenia Gravis.

Myasthenic crisis (MC) is a potentially fatal complication of myasthenia gravis (MG), often requiring intensive care and rescue therapies such as intravenous immunoglobulin (IVIG) and corticosteroids. Efgartigimod, a neonatal Fc receptor (FcRn) antagonist, offers a novel approach by selectively reducing circulating pathogenic IgG. We describe a 77-year-old man with anti-AChR-positive generalized MG who developed a severe MC, with little response to IVIG and high-dose corticosteroids. Intravenous efgartigimod was administered as rescue therapy with rapid and sustained clinical improvement. This case supports the utility of efgartigimod in MC unresponsive to conventional therapies, including in older patients with significant comorbidities.