Effects of anti-CD20 monoclonal antibody as a rescue treatment for ANCA-associated idiopathic systemic vasculitis with or without overt renal involvement.

BACKGROUND Cyclophosphamide (CYC) is thought to be the most effective treatment for antineutrophil cytoplasmatic antibody (ANCA)-associated idiopathic systemic vasculitis with severe organ or life threatening presentation. The key mechanism of action of CYC is suppression of the B lymphocyte activity. However, a considerable minority of patients either remains refractory to conventional therapy or experiences dose-limiting side effects. METHODS In the present study, rituximab (4 weekly doses of 375 mg/m2 and 2 more doses at 1-month interval) was intravenously administered as a rescue therapy to 7 patients (4 affected by idiopathic systemic microscopic polyangiitis, 2 by Wegener's granulomatosis, and 1 affected by Churg Strauss syndrome). The study group was made up of 3 women and 4 men, mean age 61.5 years (39-71), intolerant or refractory to more conventional therapy. Four patients had histologically confirmed paucimmune necrotizing glomerulonephritis. RESULTS Significant decreases were observed in levels of serum creatinine, proteinuria, erythrocyte sedimentation rate, C-reactive protein, and ANCA titers within the first 12 months of follow-up. Arthralgia and weakness rapidly disappeared in all patients. Four out of five patients reported a decrease in the degree of paresthesia, paralleled by an improvement in the electrodiagnostic parameters. A significant improvement was observed in both Birmingham Vasculitis Activity Score and Vasculitis Damage Index. Side effects were negligible. CONCLUSION In this sample of patients with idiopathic systemic vasculitis that was refractory or intolerant to conventional treatment, rituximab was found to be a safe and effective rescue therapy.