Joy MS et al. (2005) A pilot study using mycophenolate mofetil in relapsing or resistant ANCA small vessel vasculitis. Nephrol Dial Transplant 20: 2725–2732

The immunosuppressant mycophenolate mofetil (MMF) could provide an effective alternative to combined corticosteroids and cytotoxic agents in the treatment of ANTINEUTROPHIL CYTOPLASMIC AUTOANTIBODY-ASSOCIATED SMALL VESSEL VASCULITIS (ANCA-SVV). Joy et al. report that MMF obviates the need for cytotoxic drugs and avoids some of the risks associated with long-term use of the combined regimen, such as secondary malignancies, nephrotoxicity, and reduced fertility.

This small, dose-escalating pilot study enrolled patients with non-life-threatening ANCA-SVV who had relapsing disease (n = 6) or who had failed to respond to previous cyclophosphamide treatment (n = 6). MMF was administered twice daily from the first study day, with the target dose of 1,000–1,500 mg twice daily administered for 24 weeks. Concomitant corticosteroids were permitted. From weeks 24 to 52, other agents could be used to replace or bolster MMF treatment.

As measured by the BVAS, disease activity significantly decreased with MMF induction treatment between baseline and week 24 (P = 0.0013), and between baseline and week 52 (P = 0.0044). Recurrent use of a cytotoxic agent was avoided in 10/12 patients. Some disease activity remained, however, and only a minority of patients achieved a long-lasting remission, while several patients responded poorly to treatment. Interestingly, all patients who showed an early and sustained decrease in disease activity were in the relapsing group, indicating that MMF is ineffective in those resistant to cyclophosphamide induction therapy.

Joy et al. recommend that therapy is tailored to each individual's disease course, and suggest that combination therapy is likely to be most effective in controlling disease and limiting toxicity. Further investigations into MMF treatment are needed.