Hypereosinophilic Syndrome (HES)

The rationale of the roll-over study (ROSY) is to provide continuous access to study treatment for participants who have completed or exited a parent study and are deemed appropriate for continued benralizumab treatment, as judged by the Investigator, while monitoring long-term safety and tolerability of benralizumab.

This single-center, non-commercial study will involve 160 participants (80 with eosinophilic asthma (EA), 30 with eosinophilic granulomatosis with polyangiitis (EGPA), 25 with hypereosinophilic syndrome (HES), and 25 healthy donors) to investigate eosinophil subpopulations in these diseases. The study will run from Q4 2024 to Q4 2026. Objectives: Primary: To verify two eosinophil subpopulations (iEos and rEos) in EGPA and HES and analyze the role of type 2 cytokines on their plasticity. Secondary: Compare iEos proportion between different eosinophilic diseases and correlate with disease severity. Exploratory: Assess the effect of mepolizumab on eosinophil subpopulations in vitro. Population: Adults aged 18-75 with EA, EGPA, or HES, and healthy controls. EA patients must have \>300 eosinophils/mcL, EGPA requires asthma + eosinophilia + other specific features, and HES requires high eosinophil counts (\>1500 cells/mL). Methods: Data will be analyzed using Mann-Whitney U, ANOVA, and Spearman correlation tests, with results presented as mean ± SEM. This study will help explore eosinophil behavior in eosinophilic diseases and evaluate mepolizumab's effects on these cells.