Prospective study of efgartigimod in severe myasthenia gravis exacerbations requiring ventilatory or enteral support

Background and objectives To evaluate the safety and clinical efficacy of efgartigimod in adults with severe generalized myasthenia gravis (MG) exacerbations requiring ventilatory or enteral support. Methods Prospective, single-arm, open-label study conducted between November 2024 and April 2025. Sixteen consecutive adults with AChR- or MuSK-antibody-positive generalized MG requiring invasive or non-invasive ventilatory support or enteral feeding were enrolled; all met 2016 MG Guidelines criteria for impending myasthenic crisis. MGFA classification included Class IIIb (n=14), IIIa (n=1), and IVb (n=1). The primary endpoint was clinically meaningful improvement (CMI) in MG Activities of Daily Living (MG-ADL), defined as ≥2-point reduction from baseline at weeks 4 and 8. Results All 16 participants (mean age 58.5±17.4 years; 8 women) completed eight weeks of follow-up. At week 8, 12 patients (75%; 95% CI 47–91%) achieved the primary endpoint. Median MG-ADL decreased from 11 (IQR 9–13) to 7 (IQR 6–9) (median change −5 points; p=0.003). Median QMG decreased from 21 (IQR 19–23) to 13 (IQR 11–16) (median change −7.5 points; p<0.001), with 56% meeting QMG-CMI by week 1. Among 12 participants receiving corticosteroids (mean starting dose 21.2 mg/day), 50% reduced or discontinued by week 8. No treatment-related serious adverse events occurred. Discussion Efgartigimod produced rapid, clinically meaningful improvement in severe MG exacerbations without safety concerns. FcRn blockade may represent a practical alternative to plasma exchange or IVIG in acute care settings. Findings are limited by the absence of a control arm, which precludes definitive attribution of clinical improvement to efgartigimod alone. Clinical trials registration NCT06688253.