Treatment of ANCA-associated vasculitis consists of two phases: remission induction with highly effective, but also relatively toxic drugs, and, secondly, after remission is achieved, maintenance therapy with less toxic drugs. The standard induction therapy of a relapse of Wegener's granulomatosis or microscopic polyangiitis consists of the combination of cyclophosphamide and prednisolone. Although this induction therapy is very effective, it is very toxic as well.~Searching for an alternative for cyclophosphamide, we will test the efficacy and safety of a new combination therapy with mycophenolate mofetil and prednisolone. We will compare the effect and safety of the standard induction therapy with the new therapy. When relapses occur, patients will be randomized for either the standard therapy with cyclophosphamide or for mycophenolate mofetil.
The purpose of this study is to determine the efficacy and safety of a new drug, mycophenolate mofetil, for the treatment of relapses of ANCA-associated vasculitis (Wegener's granulomatosis or microscopic polyangiitis). Therefore, we compare the standard therapy with cyclophosphamide to mycophenolate mofetil.~The investigators expect mycophenolate mofetil to be less toxic and almost equally effective as cyclophosphamide.