P.045 Safety profile overview of Efgartigimod Clinical Trials in participants with diverse Diverse IgG-Mediated Autoimmune Diseases

Background: Efgartigimod is a human IgG1 antibody Fc-fragment that reduces IgG autoantibody levels through FcRn blockade. This study reports safety of efgartigimod across IgG-mediated disorders. Methods: The intravenous was evaluated in 204 efgartigimod-treated subjects with generalized myasthenia gravis (phase 3 ADAPT and 3-year open-label extension ADAPT+ trials), primary immune thrombocytopenia ADVANCE trial), or pemphigus (open-label phase 2 trial). These studies examined different doses (10–25 mg/kg), including cyclical dosing continuous weekly pemphigus. Results: Across all indications studied, demonstrated consistent profile, treatment-emergent adverse event (TEAE) rates comparable to placebo (ADAPT, 77.4% efgartigimod/84.3% placebo; ADVANCE, 93.0% efgartigimod/95.6% 85% the study). Most TEAEs were mild moderate severity. Discontinuation due events consistently low 3.6% efgartigimod/3.6% 3.5% efgartigimod/2.2% 3% participants). In ADAPT+, no increases infections occurred additional (19 cycles). Conclusions: well tolerated studied. TEAEs, infections, severity did not increase frequency recurrent dosing.