Efgartigimod shows homogeneous efficacy across sexes in AChR-Ab+ generalized myasthenia gravis.

INTRODUCTION/AIMS: Sex-specific differences in myasthenia gravis (MG) are widely acknowledged, yet data on sex-based outcomes of MG treatment are scarce. In accordance with Sex and Gender Equity in Research guidelines, this post hoc analysis assessed potential sex-specific differences in treatment outcomes in acetylcholine receptor antibody-positive (AChR-Ab+) generalized (g)MG participants in the Phase 3 ADAPT trial (NCT03669588). METHODS: Participants received four once-weekly efgartigimod infusions (10 mg/kg) or placebo per cycle. Endpoints (primary: proportion of Myasthenia Gravis Activities of Daily Living (MG-ADL) responders (Cycle 1); secondary: proportion of Quantitative Myasthenia Gravis (QMG) and early (Cycle 1) MG-ADL responders, and time with clinically meaningful improvements in MG-ADL score; additional: quality of life outcomes, pharmacodynamics) were assessed according to sex. RESULTS: Females were younger (mean age: 42.9 vs. 54.8 years), more likely to have undergone thymectomy (65.1% [56/86] vs. 44.2% [19/43]), and had higher baseline QMG scores (16.3 vs. 14.3) compared with males. Efgartigimod demonstrated homogeneous effects between sexes, with no significant difference in proportions of MG-ADL (p = 0.7014), early (Cycle 1) MG-ADL (p = 1.00), or QMG responders (p = 0.1595). Improvements in quality-of-life assessments, rates of minimal symptom expression, and mean total immunoglobulin G reductions (Cycle 1) were greater with efgartigimod verso placebo in females and males. Efgartigimod was well tolerated, with similar safety profiles across sexes. DISCUSSION: In ADAPT, efgartigimod-treated female and male AChR-Ab+ gMG patients had similar efficacy and safety outcomes. These data provide valuable insight for clinicians, given the established sex differences in MG disease course and treatment responses. TRIAL REGISTRATION: The ADAPT trial is registered on ClinicalTrials.gov (NCT03669588).