Factors Affecting the Ability to Discontinue Oral Corticosteroid Use in Patients with EGPA Treated with Anti-Interleukin-5 Therapy.

INTRODUCTION: Patients with eosinophilic granulomatosis with polyangiitis (EGPA) and some with severe eosinophilic asthma require continuous long-term oral corticosteroid (OCS) treatment for disease control. The anti-interleukin-5 agent, mepolizumab, has recently become available for the treatment of severe eosinophilic asthma and EGPA, with promising results and safety profiles. The proportion of patients with EGPA who discontinued oral steroids was 18% in the MIRRA trial. To compare patients with EGPA who were able to discontinue steroids with mepolizumab with those who could not.

METHODS: Twenty patients with EGPA treated with mepolizumab were evaluated at Osaka Habikino Medical Center. The OCS dose, asthma control test score, fractional exhaled nitric oxide levels, peripheral eosinophil count, and spirometric parameters were evaluated before and after treatment.

RESULTS: There was a significant reduction in the mean OCS dose from a prednisolone equivalent of 8.88 ± 4.99 mg/day to 3.18 ± 3.47 mg/day (p < 0.001). In this study, 40% of patients discontinued oral steroids. The most common reason for the failure to discontinue steroids in patients was poor asthma control. The percentage of predicted forced expiratory volume in 1 s significantly improved in patients with EGPA who could discontinue steroids after receiving mepolizumab.

CONCLUSION: In this real-world study, treatment with mepolizumab for EGPA was associated with a significant reduction in OCS use; however, poor asthma control was identified as an inhibiting factor for steroid reduction.