Alemtuzumab for ANCA Associated Refractory Vasculitis

Inclusion Criteria: 1. A diagnosis of AAV, according to a standardized definition 2. Active vasculitis with at least one severe or three non severe items of BVAS/WG activity (equivalent to BVAS/WG\>3) 3. Previous therapy with either cyclophosphamide or methotrexate, in combination with prednisolone for at least 3 months. Exclusion Criteria: 1. Age less than 18 or greater than 60 years 2. Creatinine \> 150μmol/l (1.7mg/dl) 3. Total white count \< 4x109/l or lymphocyte count \< 0.5x109/l, or IgG \< 5g/L, or neutrophil count \< 1.5x109/l. 4. Severe lung haemorrhage with hypoxia (\<85% on room air) 5. Severe gastrointestinal, central nervous system or cardiac vasculitis 6. Previous therapy with: 1. Alemtuzumab at any time 2. IVIg, infliximab, etanercept, adalimumab, abatacept, anti-thymocyte globulin or plasma exchange in past three months 3. Rituximab within the past 6 months 7. Intensive care unit requirement 8. Active infection with HIV, hepatitis B or hepatitis C or other infection requiring parenteral or long-term oral antibiotics 9. History of ITP or platelet count at screening below 50,000 x 106/l 10. Pregnancy or inadequate contraception in pre-menopausal women 11. Breast feeding 12. Any condition judged by the investigator that would cause the study to be detrimental to the patient. 13. Any other multisystem autoimmune disease including Churg Strauss angiitis, systemic lupus erythematosus, anti-GBM disease and cryoglobulinaemia 14. Any previous or current history of malignancy (other than resected basal cell carcinoma)