Targeting Complement Activation in Antineutrophil Cytoplasmic Autoantibodies (ANCA)-Vasculitis - Eculizumab

"induction : pulse methyl prednisolone (7 mg/kg/day x3) then prednisone 1 mg/kg/day (not to exceed 60 mg/day) for 4 weeks, then taper over the following 12 weeks. Cyclophosphamide starting at 0.75 gm/m2 IV (decreased to 0.5 gm/m\^2 for patients \> than 70 or with estimated Glomerular Filtration Rate (eGFR) \< 20 ml/min) to be titrated up to 1 gm/m\^2 depending on the 2 week white blood count (WBC) nadir \> 3000 cell/μL. Subsequent cyclophosphamide will be given every 4 weeks for at least 2 more doses. Once complete remission for 2 months, patient may be switched from cyclophosphamide to maintenance therapy with azathioprine 1.5-2 mg/kg/day for 6-9 months (to a total of 12 months of therapy) .~For patients who cannot tolerate cyclophosphamide, or who have received it in large doses previously, another medication called rituximab may be used instead. However, if rituximab is indicated for the patient, he cannot participate in the study."

In addition to conventional therapy, patients randomized to eculizumab will receive 600 mg by IV infusion over 35 minutes every 7 days for the first 4 weeks, then 900 mg by IV infusion for the fifth dose 7 days later (week 5), then 900 mg every 14 days thereafter, for a total of 9 doses (about 3 months of treatment). This dosing scheme is based on that used for the treatment of Paroxysmal Nocturnal Hemoglobinuria (PNH). The length of treatment is shorter than for PNH, based on a desire to target the addition of eculizumab to the period of maximal disease activity, while limiting the risks of infectious complications in this first pilot study.