Leflunomide for Polyomavirus Type BK Nephropathy

Abstract
Polyomavirus type BK nephropathy is an aggressively destructive disease occurring in up to 8 percent of patients with renal allografts,1,2 with rates of graft loss within one year of 30 to 65 percent.3,4 There is no therapy with proven efficacy. Leflunomide (Arava), approved for the treatment of rheumatoid arthritis, is an immunosuppressive drug, yet its active metabolite, A77 1726, has substantial antiviral activity in vitro and in animals.5