Treatment of ANCA-associated systemic vasculitis.

The antineutrophil cytoplasmic antibodies (ANCA)-associated small vessel vasculitides include Wegener's granulomatosis, Churg-Strauss syndrome, microscopic polyangiitis (MPA), and the renal limited form of MPA, also known as pauci-immune or idiopathic crescentic glomerulonephritis. ANCA are probably necessary but not sufficient for disease pathogenicity. Classical induction and maintenance therapy of these conditions with corticosteroids and long-term cyclophosphamide is associated with occasional relapse and major toxicities. Therefore, treatment regimens being investigated include induction with methotrexate or, especially for patients with more aggressive disease accompanied by renal insufficiency, therapies that include either pulses of methylprednisolone or plasma exchanges. Nontraditional options for maintenance therapy may include step-down treatment with azathioprine or mycophenolate mofetil. For patients with Wegener's granulomatosis, studies have shown a reduced occurrence of flares with the use of co-trimoxazole. Finally, although a carefully randomized controlled trial with etanercept demonstrated that this tumor necrosis factor (TNF)-blocking agent was not superior to conventional maintenance therapy, a biologic agent with a different mechanism of action, rituximab, may prove a satisfactory alternative.