Efgartigimod in Patients with Generalized Myasthenia Gravis Refractory or Intolerant to IVIg

Introduction: Generalized myasthenia gravis (gMG) is a rare chronic autoimmune disorder of the neuromuscular junction caused by pathogenic autoantibodies directed against a postsynaptic target. The therapeutic landscape of gMG has recently expanded with the introduction of FcRn inhibitors. This study aimed to assess the real-world effectiveness and safety of efgartigimod (EFG) in AChR-positive gMG patients who failed or were intolerant to intravenous immunoglobulin (IVIg). Methods: EFG was administered as four consecutive weekly intravenous infusions at 10 mg/kg. Treatment efficacy was evaluated using the Myasthenia Gravis Activity of Daily Living (MG-ADL) and Myasthenia Gravis quantitative (QMG) scales at baseline and after 4 weeks. Incidence of adverse events and prednisone use were collected at each time point. Results: Thirteen patients (6 women and 7 men, mean age 52.9 years) received EFG following IVIg therapy. After one treatment cycle, both MG-ADL and QMG scores showed significant clinical improvement. MG-ADL responder rate (MG-ADL reduction > 2) was 84.6% while 69.2% on QMG (QMG reduction > 3). Minimal symptom expression was reached in one patient, accompanied by a mean reduction in daily prednisone dose of 6.9 mg. Conclusion: In this real-world cohort, efgartigimod demonstrated a rapid and meaningful clinical benefit with a favorable tolerability profile in patients with AChR-positive gMG after IVIg failure or intolerance. These findings support the potential role of EFG as an effective therapeutic option in this difficult-to-treat population.