New immunosuppressive agents in clinical use: mycophenolate mofetil and tacrolimus

Since the early 1980s, a 3-drug regimen that includes cyclosporine, azathioprine, and usually corticosteroids has been the mainstay of immunosuppression for patients undergoing cardiac transplantation. This regimen, however, has a variety of inherent toxicities and is not associated with any lesser incidence of graft coronary artery disease than the earlier regimen. For these reasons, there has been a widely perceived need for the introduction of improved immunosuppressive agents. Two such agents have thus far been introduced into clinical organ transplantation: mycophenolate mofetil and tacrolimus. Mycophenolate mofetil is used as a substitute for azathioprine and has been shown to result in significantly lower mortality rates and freedom from rejection in heart transplant recipients. Tacrolimus can be used as a substitute for cyclosporine but (at least in the short-term) seems to offer no important advantage in terms of survival or rejection. The combination of these 2 new agents seems to have no short-term disadvantage and longer-term follow-up is pending.