Eosinophilic granulomatosis with polyangiitis (EGPA), formerly called Churg-Strauss syndrome, is a rare systemic small-vessel vasculitis, associated with asthma and blood and tissue eosinophilia. EGPA belongs to the group of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV), and commonly involves upper and lower respiratory tracts, the lungs, the peripheral nerve and the heart.~Therapeutic management is based on glucocorticoids alone or in combination with conventional immunosuppressive agents, mainly azathioprine, methotrexate or cyclophosphamide, according to disease severity assessed by the Five Factor Score.~Such treatments, in addition to their common side effects, are frequently insufficiently effective to control chronic asthma and/or rhinosinusitis, requiring long-term high-dose corticosteroids. Because EGPA shares common pathophysiological features with eosinophilic disorders and asthma, new therapeutic options used in these conditions could be of interest, in particular mepolizumab, a monoclonal anti-interleukin (IL)-5 antibody, which has shown promising results in two small preliminary studies to control disease activity and decrease glucocorticoids in cortico-dependant patients. In addition, mepolizumab has been recently evaluated in a prospective trial, the MIRRA trial, targeting a small niche of patients, i.e. those with corticodependent asthma unable to achieve disease control with low dose of glucocorticoids. Results published revealed that mepolizumab led to significantly more accrued weeks of remission than placebo (28% vs. 3% of the participants had ≥24 weeks of accrued remission; odds ratio, 5.91; 95% confidence interval [CI], 2.68 to 13.03; P<0.001) and a higher percentage of participants in remission at both week 36 and week 48 (32% vs. 3%; odds ratio, 16.74; 95% CI, 3.61 to 77.56; P<0.001).~However, these studies did not evaluate the interest of mepolizumab during EGPA flare associating asthma, eosinophilic and vasculitis lesions, in order to induce remission of the disease and rapidly decrease and discontinue glucocorticoids.~Also, recent pathophysiological date strongly support in addition to previous therapeutic studies the major interest to target IL-5 as soon as EGPA is diagnosed: 1) genetic association studies demonstrated that polymorphisms in the IL-5 pathway are associated with EGPA in comparison with controls, 2) increased expression of IL-5 in mice model are able to induce vasculitis lesions as observed in the human diseases.~Patients will receive a standardized glucocorticoid tapering schedule. From day 28 post-baseline onwards, if the subject's BVAS=0 their oral prednisone dose should be tapered downwards. A standardized glucocorticoid tapering schedule provided in the protocol enables a reduction in oral prednisone dose every 2 weeks, with the intention of achieving a prednisone dose of 4 mg/day or less. Once a subject has achieved a dose of 4 mg/day prednisone, the investigator is encouraged to continue tapering downwards, if clinically warranted, at dose increments of 1.0 mg every week.~Upwards dose adjustments within the 0-4.0 mg range are permitted without necessarily being considered a relapse.
The purpose of this study is to compare mepolizumab-based regimen to conventional therapeutic strategy for remission induction in patients with Eosinophilic Granulomatosis with Polyangiitis.