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.