Abstract Details

In the ADAPT study, efgartigimod (a human IgG1 antibody Fc-fragment that reduces pathogenic autoantibody and total IgG levels through neonatal Fc receptor blockade) was well tolerated and effective in a broad gMG population.

Assess efficacy of efgartigimod in anti-AChR autoantibody positive (AChR-Ab+) patients with generalized myasthenia gravis (gMG) early in their disease and management course.

Efgartigimod 10 mg/kg or placebo was administered intravenously in cycles of 4 weekly infusions, with subsequent cycles initiated based on clinical evaluation. Efficacy assessment included Myasthenia Gravis Activities of Daily Living (MG-ADL) and Quantitative Myasthenia Gravis (QMG) scales, with response defined as ≥2-point (MG-ADL) or ≥3-point (QMG) improvement for ≥4 consecutive weeks, occurring ≤1 week after last infusion. This analysis assessed responder status and minimal symptom expression (MSE; MG-ADL 0 or 1) in subgroups of AChR-Ab+ patients with <3 years and ≥6 years disease duration.

In patients with <3 years disease duration, 78.6% (n=11/14) efgartigimod-treated vs 23.5% (n=4/17) placebo-treated were MG-ADL responders (95% CI, 25.6–84.5) during cycle 1. In patients with ≥6 years disease duration, the proportion of MG-ADL responders was 56.8% (n=21/37) for efgartigimod-treated and 21.9% (n=7/32) for placebo-treated patients (95% CI, 13.4-56.3). Similar results were observed in proportion of QMG responders between efgartigimod- and placebo-treated patients among <3 and ≥6-year subgroups. Additionally, 42.9% (n=6/14) of patients with <3 years disease duration and 40.5% (n=15/37) of patients with ≥6 years disease duration receiving efgartigimod were able to achieve MSE compared with 12.5% (n=2/16) and 9.4% (n=3/32) of those receiving placebo, respectively. Adverse events were mostly mild-moderate and included headache, nasopharyngitis, nausea, diarrhea, and upper respiratory/urinary tract infection.

A greater percentage of patients early in their disease course (<3 years disease duration) treated with efgartigimod were responders and achieved MSE compared with placebo.