Leflunomide in solid organ transplantation and polyoma virus infection.

Leflunomide, trade name Arava® (Aventis Pharmaceuticals Incorporation, Bridgewater, New Jersey, U.S.A.), belongs to a family of drugs called the malonitrilamides. Some, like leflunomide, have substantial immune suppressive activity in experimental allograft models. In addition to experimental data suggesting leflunomide’s value in preventing1, 2, 3, 4, 5 and reversing acute1,5 and chronic rejection,6,7 it has been shown to inhibit human cytomegalovirus (CMV) and herpes simplex virus (HSV) in vitro.8, 9, 10 Because it is a drug with a variety of biologic activities, it has been investigated for diseases as disparate as cancer and autoimmunity. Leflunomide was approved for the treatment of rheumatoid arthritis and has been used in more than 300,000 patients worldwide with efficacy and a favorable side effect profile. In this chapter, we will discuss the immunemodulatory effects of leflunomide and its metabolite A77 1726 that prevent organ rejection. We will also share our experience in the treatment of polyomavirus infections.