A pilot study using mycophenolate mofetil in relapsing or resistant ANCA small vessel vasculitis

Background. The treatment approaches to antineutrophil cytoplasmic autoantibody (ANCA) small vessel vasculitis expose patients to the risks associated with long-term use of corticosteroids and cytotoxic agents. In an effort to explore approaches to minimize risks, we conducted a pilot efficacy and safety study of mycophenolate mofetil (MMF) in the treatment of subjects with nonlife-threatening recurrent or cyclophosphamide-resistant ANCA-vasculitis. Methods. MMF was initiated at 500mg orally twice daily and gradually increased to a target dose of 1000mg twice daily for a duration of 24 weeks. Concomitant therapy with corticosteroids was allowed. The Birmingham Vasculitis Activity Score (BVAS) was used to assess disease activity and treatment efficacy. ANCA titres, serum creatinine and adverse events were secondary measures of efficacy and/or toxicity. Results. Twelve subjects were enrolled in the study. Treatment with MMF led to an improvement in disease activity as measured by the BVAS at 24 weeks (P= 0.0013) and 52 weeks (P= 0.0044) as compared to baseline. The BVAS decreased from an average of 9.1±3.5 at baseline (range, 3-17) to an average of 2.8±1.9 (range, 1-6) at 24 weeks and to 2.8±4.3 (range, 0-13) at 52 weeks. Early and sustained reductions in BVAS occurred in subjects initially classified as disease relapses vs those with treatment resistance. Side effect profile was consistent with the mechanism of action and pharmacokinetic disposition of MMF. Conclusions. MMF is a reasonable option in the treatment of non-life-threatening recurrent or resistant vasculitis and may obviate the immediate need for recurrent use of cytotoxic agents.