The following is a summary of “Mepolizumab incompletely suppresses clinical flares in a pilot study of episodic angioedema with eosinophilia,” published in the March 2024 issue of Allergy & Immunology by Khoury, et al.

Episodic angioedema with eosinophilia (EAE) is a rare cyclic syndrome characterized by recurrent angioedema, myalgia, fatigue, and fever, resolving between episodes without treatment. Elevated serum IL-5 levels and neutrophils precede absolute eosinophil count (AEC) increases in most cases. For a study, researchers sought to evaluate the impact of IL-5-driven eosinophilia on EAE clinical manifestations.

An open-label pilot study administered mepolizumab (700 mg intravenously monthly for 3 months, followed by dose reduction to 300 mg subcutaneously monthly). Primary endpoints assessed reduction in symptom number and severity via patient-reported questionnaires. Secondary endpoints included ≥75% reduction in peak AEC after one mepolizumab dose and sustained AEC reduction after three doses. Exploratory endpoints examined mepolizumab’s effects on other cell lineages, plasma mediator levels, and eosinophil activation biomarkers.

Five participants (4 female, 1 male; median age: 45 years) were enrolled. None experienced reduced symptomatic flares on mepolizumab; one withdrew due to lack of improvement. Peak AEC decreased by ≥75% after one dose in three participants and after three doses in four.

In the small EAE cohort, mepolizumab did not significantly reduce clinical symptoms despite AEC reduction.

Reference: jacionline.org/article/S0091-6749(23)01397-0/abstract