Reslizumab in the Treatment of Eosinophilic Granulomatosis With Polyangiitis (EGPA) Study

Inclusion Criteria: * Informed Consent: Able to give written informed consent prior to participation in the study, which will include the ability to comply with the requirements and restrictions listed in the consent form. Subjects must be able to read, comprehend, and write at a level sufficient to complete study related materials. * Gender and Age: Male or female subjects \>18 years old * EGPA diagnosis: subjects who have been diagnosed with EGPA for at least 6 months based on the history or presence of: asthma plus eosinophilia (\>1.0x109/L and/or \>10% of leucocytes) plus at least two of the following additional features of EGPA: * A biopsy showing histopathological evidence of eosinophilic vasculitis, or perivascular eosinophilic infiltration, or eosinophil-rich granulomatous inflammation; * Neuropathy, mono or poly (motor deficit or nerve conduction abnormality); * Pulmonary infiltrates, non-fixed; * Sino-nasal abnormality; * Cardiomyopathy (established by echocardiography or MRI); * Glomerulonephritis (haematuria, red cell casts, proteinuria); * Alveolar haemorrhage (by bronchoalveolar lavage); * Palpable purpura; * ANCA positive (MPO or PR3). * Subjects who have received a cyclophosphamide (CYC) induction regimen may be included a minimum of 2 weeks after the last dose of daily oral CYC, or 3 weeks after the last dose of pulsed IV CYC prior to visit 1, if their total WBC is ≥4x109/L prior to visit 1. * Subjects who have received a methotrexate, azathioprine, or mycophenolate mofetil induction regimen may be included if on a stable dose for at least 4 weeks prior to visit 1. * Corticosteroid therapy: Subject must be on a stable dose of oral prednisolone or prednisone of ≥5 mg/day for at least 4 weeks prior to visit 1. * Immunosuppressive therapy: If receiving immunosuppressive therapy (including methotrexate, azathioprine, or mycophenolate mofetil, but excluding restricted medications below) the dosage must be stable for the 4 weeks prior to visit 1 and during the study (dose reductions for safety reasons will be permitted). * Female subjects: To be eligible for entry into the study, females of childbearing potential (FCBP) must commit to consistent and correct use of an acceptable method of birth control beginning with consent, for the duration of the trial. Exclusion Criteria: * Hypereosinophilic Syndrome * Wegener's Granulomatosis * Malignancy * Parasitic disease * Pregnant or nursing * If female and of child-bearing potential, must have negative pregnancy test and must adhere to acceptable method of contraception (with \<1% failure rate) during the study and for four months after the study. * Any other medical illness that precludes study involvement * Patients who are currently receiving or have previously received reslizumab or any other type of anti-interleukin therapy (i.e. mepolizumab, lebrikizumab etc.) within the last three months. * Taking cyclophosphamide * Any patients with a known hypersensitivity to reslizumab or any of its excipients