Real-world mepolizumab treatment in eosinophilic granulomatosis with polyangiitis reduces disease burden in the United States.

Background: Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare, chronic inflammatory disease characterized by asthma and small/medium vessel vasculitis. Mepolizumab is approved for use in EGPA disease management alongside oral corticosteroids (OCS), but evidence of its real-world impact is limited.

Objective: To compare real-world treatment patterns and health outcomes, particularly OCS use, EGPA-related hospitalizations/relapses, and asthma exacerbations pre- and post-mepolizumab initiation in US patients with EGPA.

Methods: Patients with EGPA receiving ≥2 mepolizumab doses were identified using administrative claims data from Komodo Health's Comprehensive Dataset (December 2016-March 2020). Outcomes assessed pre- and post-mepolizumab initiation included corticosteroid/other medication use, EGPA-related hospitalizations/relapses, and asthma exacerbations.

Results: Overall, 114 patients were identified; of these, 60 (53%) received mepolizumab 300 mg at index. Average daily OCS dose per dispensing was significantly lower post- versus pre-mepolizumab initiation (21.2 vs 26.8 mg/day, 21% relative reduction, P<0.001); mean number of OCS bursts also decreased (0.9 vs 1.8, 50% relative reduction, P<0.001). Patients experienced significantly lower rates of EGPA-related hospitalization (0.86 vs 1.55 per person-year [PPY], 49% relative reduction, P=0.004) and EGPA relapse (3.18 vs 3.94 PPY, 19% relative reduction, P=0.004) post- versus pre-initiation. Most patients (91%) had an asthma diagnosis at baseline; among these patients, asthma exacerbation rates were significantly lower post- versus pre-initiation (1.05 vs 1.84 PPY, 42% relative reduction, P=0.004).

Conclusion: Mepolizumab was associated with significant steroid-sparing benefits and significantly reduced rates of EGPA-related hospitalizations, EGPA relapses, and asthma exacerbations in this real-world study of US patients with EGPA, confirming the benefits of mepolizumab treatment seen in clinical trials.