Efficacy and safety of rituximab in the treatment of eosinophilic granulomatosis with polyangiitis

INTRODUCTION: Eosinophilic granulomatosis with polyangiitis (EGPA) is a subset of antineutrophil cytoplasmic antibodies (ANCA) associated vasculitis with distinct pathophysiological mechanisms, clinical features and treatment responses. Rituximab is a licensed therapy for granulomatosis with polyangiitis and microscopic polyangiitis but there is limited experience of rituximab in EGPA. METHODS: EGPA patients from a tertiary centre who received rituximab for mostly refractory EGPA or in whom cyclophosphamide was contra indicated were studied. A standardised dataset was collected at time of initial treatment and every 3 months for 24 months. Response was defined as a Birmingham Vasculitis Activity Score (BVAS) of 0 and partial response as ≥50% reduction in BVAS from baseline. Remission was defined as a BVAS of 0 on prednisolone dose ≤5 mg. RESULTS: Sixty-nine patients (44 female) received rituximab between 2003 and 2017. Improvement (response and partial response) was observed in 76.8% of patients at 6 months, 82.8% at 12 months and in 93.2% by 24 months, while relapses occurred in 54% by 24 months, with asthma being the most frequent manifestation. The median BVAS decreased from 6 at baseline to 1 at 6 months, and 0 at 12 and 24 months. Prednisolone dose (mg/day, median) decreased from 12.5 to 7, 7.5 and 5 at 6, 12 and 24 months, respectively. ANCA positive patients had a longer asthma/ear, nose and throat (ENT) relapse-free survival time and a shorter time to remission. DISCUSSION: Rituximab demonstrated some efficacy in EGPA and led to a reduction in prednisolone requirement, but asthma and ENT relapse rates were high despite continued treatment. The ANCA positive subset appeared to have a more sustained response on isolated asthma/ENT exacerbations.