FTY720, a synthetic myriocin analogue derived from culture filtrates of Isaria sinclairii, is a
novel immunosuppressant that in experimental animals and nonhuman primates produces
lymphocytopenia and prolongs allograft survival in dose-dependent fashion. FTY720 exerts
synergistic interactions not only with calcineurin antagonists, but also with proliferation
signal inhibitors. These interactions proffer the possibility of reducing exposure to and
mitigating toxicity of existing drugs. The mechanism of drug action is not entirely clear …