Management of Eosinophilic Granulomatosis with Polyangiitis with less myocardial involvement Using Early Mepolizumab without Immunosuppressants: Clinical Implications

Background. To investigate whether long-term remission can be maintained with corticosteroids plus mepolizumab, without the addition of conventional immunosuppressants, following initial remission induction in patients with eosinophilic granulomatosis with polyangiitis (EGPA). Methods. We retrospectively recruited 72 EGPA patients treated at the National Hospital Organization Yokohama Medical Center (April 2022 to March 2025). Patients were categorized into an IS-combination group (immunosuppressant + corticosteroid + mepolizumab) and a non-IS group (corticosteroid + mepolizumab) on the basis of immunosuppressant use at mepolizumab initiation. Peripheral blood eosinophil counts, Birmingham Vasculitis Activity Score (BVAS), systemic corticosteroid dosage, remission induction rates, and duration of relapse-free period following the introduction of mepolizumab were compared. Results. Compared with the IS-combination group, the non-IS group was older at EGPA onset ( P  = 0.02), had a shorter period from diagnosis to initiation of mepolizumab ( P  = 0.034), had less myocardial involvement ( P  = 0.01), and had lower BVAS before treatment with mepolizumab ( P  < 0.001). Immunosuppressant use during initial treatment was 100% in the IS-combination group and 75% in the non-IS group ( P  = 0.001). The non-IS group achieved remission faster ( P  = 0.03), had a higher cumulative remission rate ( P  = 0.04), and had a higher relapse-free rate ( P  = 0.02). Conclusion. In EGPA with less cardiac involvement, early initiation of mepolizumab in combination with corticosteroids, without concomitant immunosuppression, may achieve earlier remission and contribute to sustained long-term disease control.