Abstract-Text (inkl. Referenzen)

Introduction Efgartigimod, a human IgG1 antibody Fc-fragment blocking the neonatal Fc receptor, was effective and well tolerated in the ADAPT trial of patients with generalized myasthenia gravis (gMG). Patients completing ADAPT were eligible for the 3-year, open-label extension, ADAPT+. Objective: evaluate long-term safety and efficacy of efgartigimod.

Methods Efgartigimod (10mg/kg IV) administered in cycles of once-weekly infusions for 4 weeks; subsequent cycles initiated based on clinical evaluation. MG-ADL and QMG scales assessed efficacy.

Results Ninety percent of ADAPT patients (151/167) entered ADAPT+. As of February 2021, 106 AChR-Ab+ and 33 AChR-Ab– patients had received ≥1 efgartigimod dose (66 of them received placebo during ADAPT). Patients received a mean 5.1 cycles (20.5 infusions) over a median (range) study duration of 371 (50–586) days, resulting in 138 patient-years total observation. Mean between-cycle duration was 40.4 days. Most common AEs were headache (22.3%; 31/139), nasopharyngitis (10.8%; 15/139), and diarrhea (8.6%; 12/139), which were mostly mild or moderate. In cycle 1, a mean change (SE) of –5.1 (0.32) in MG-ADL and –4.8 (0.36) in QMG were observed, with similar results during subsequent cycles for ≤10 cycles. Repeated reductions in total IgG and AChR-Abs were observed across cycles.

Summary These analyses suggest long-term efgartigimod results in consistent decrease in IgG antibodies and repeatable improvement in function and strength.