Part 3: Newer therapies for ANCA-associated vasculitis.

Newer anti-proliferative drugs Deoxyspergualin is a novel anti-proliferative drug derived from bacillus laterosporus that suppresses lymphocyte and macrophage function and impairs neutrophil production (1). Studies in refractory ANCA-associated vasculitis and crescentic glomerulonephritis have demonstrated useful efficacy and in a murine model of spontaneous vasculitis, deoxyspergualin was superior to mycophenolate mofetil and as effective as cyclophosphamide in the control of vasculitis (2-5). A larger, multi-centre study of deoxyspergualin in 46 patients with refractory Wegenerʼs granulomatosis has recently been completed (6). This study found a response rate of 90% with almost half of patients reaching a sustained full remission accompanied by significant reductions in prednisolone requirement. The improvement in disease activity was maintained after stopping deoxyspergualin during treatment with azathioprine. Deoxyspergualin has the potential to replace cyclophosphamide for the induction of remission in vasculitis without exposing patients to the fertility and malignancy risks of cyclophosphamide. Reversible leukopenia was frequent with deoxyspergualin and required close monitoring of blood counts. Mycophenolate mofetil and leflunomide are licensed for the treatment of solid organ transplantation and rheumatoid arthritis respectively and are also under evaluation in vasculitis. Small studies in refractory vasculitis have reported a variable response to mycophenolate and a retrospective review in 53 patients with relapsing ANCA associated vasculitis found useful disease responses in over 50% of patients but dosing was limited by toxicity and subsequent relapse rates were high (7-9). A randomised comparison of leflunomide to methotrexate for remission maintenance after cyclophosphamide induction was stopped early due to an excess of major flares in the methotrexate group (10). However, adverse events were more frequent in the leflunomide limb and the differences between methotrexate and leflunomide may, in part, have related to dosing. This study supports the use of leflunomide as an alternative drug for remission maintenance. Two studies are investigating the roles of mycophenolate mofetil for remission induction and maintenance therapy in vasculitis (11).