Efficacy and Safety of Benralizumab in EGPA Compared to Mepolizumab.

Inclusion Criteria: 1. Male or female subjects age 18 years or older. 2. EGPA diagnosis based on history or presence asthma and eosinophilia (\>1.0x10\^9/L and/or \>10% of leucocytes) and at least 2 of; biopsy with eosinophilic vasculitis or perivascular/granulomatous inflammation; mono-or polyneuropathy, non-fixed pulmonary infiltrates, sino-nasal abnormality; cardiomyopathy; glomerulonephritis; alveolar haemorrhage; palpable purpura; anti neutrophil cytoplasmic anti-body (ANCA) positivity (Myeloperoxidase or proteinease 3). 3. History of relapsing (at least 1 confirmed EGPA relapse within last 2 years and \> 12 weeks prior to screening), or refractory (failure to attain remission, defined as BVAS=0 and oral corticosteroid (OCS) dose \<=7.5 mg/day of prednisolone or equivalent, following standard induction regimen for at least 3 months and within 6 months prior to screening, or recurrence of symptoms upon OCS tapering at any dose of ≥7.5 mg/day prednisolone or equivalent. If induction with glucocorticoidsalone, patient must have failed to attain remission after 3 months and the glucocorticoid dose must be ≥15 mg/day prednisolone or equivalent for the 4 weeks prior to randomization. 4. Must be on a stable dose of oral prednisolone or prednisone of ≥7.5 mg/day (but not \>50mg/day) for at least 4 weeks prior to randomization. 5. If receiving immunosuppressive therapy (excluding cyclophosphamide) the dose must be stable for the 4 weeks prior to randomization and during the study (dose reductions for safety reasons will be permitted). 6. QTc(F)\<450 msec or QTc(F)\<480 msec for patients with bundle branch block. 7. Females of childbearing potential must use an acceptable method of birth control from randomization for at least 12 weeks after the last study drug administration. Exclusion Criteria: 1. Diagnosed with granulomatosis with polyangiitis (GPA) or microscopic polyangiitis (MPA) 2. Organ or life-threatening EGPA \< 3 months prior to screening 3. Currently pregnant or breastfeeding, or planning to become pregnant during study participation. 4. Current malignancy or history of malignancy, unless received curative therapy \>5 years ago, or \>1 year ago for basal cell carcinoma, localized squamous cell carcinoma of the skin or in situ carcinoma of the cervix 5. An untreated or refractory helminth parasitic infection \< 24 weeks prior to screening 6. Unstable liver disease 7. Severe or clinically significant, uncontrolled cardiovascular disease 8. Other concurrent disease that may put the patient at risk, or may influence the results of the study, or the patients' ability to complete entire duration of the study 9. Chronic or ongoing infectious disease requiring systemic anti-infective treatment 10. Known immunodeficiency disorder or positive HIV test 11. Prior receipt of mepolizumab, reslizumab, dupilumab or benralizumab. Receipt of intravenous/intramuscular/subcutaneous corticosteroids within 4 weeks prior to randomization, receipt of omalizumab within 130 days prior to screening, rituximab within 6 months prior to screening (or B-cells not recovered), interferon-α or alemtuzumab within 6 months prior to screening, receipt of anti-tumor necrosis factor therapy within 12 weeks prior to screening or an investigational non-biologic product within 30 days or 5 half-lives prior to screening, whichever is longer. Receipt of any other marketed or investigational biologic products within 4 months or 5 half-lives prior to screening, whichever is longer.