Cyclosporine in thoracic organ transplantation.

The discovery of cyclosporine proved to be a breakthrough that helped transform the status of both heart and lung transplantation from experimental to established therapeutic procedures. Cyclosporine inhibits the early phase of T-cell activation and thus of the alloimmune response. It proved to be highly effective in prophylaxis against acute rejection but its use has been limited by dose-related renal toxicity. Consequently, it has generally been used in regimens that combine it with other immunosuppressive agents with the aim of preventing acute rejection while minimising toxicity. For many years 'triple therapy' using cyclosporine, azathioprine and corticosteroids was the most commonly used regimen for both heart and lung transplantation. Other agents have now become available that provide more effective prophylaxis against acute rejection than azathioprine; these include, mycophenolate and the TOR inhibitors sirolimus and everolimus. Everolimus has also been shown to inhibit the early phase of cardiac allograft vasculopathy. Unfortunately, the TOR inhibitors also potentiate the nephrotoxicity of cyclosporine. Both mycophenolate and the TOR inhibitors are subject to pharmacokinetic interactions with cyclosporine. We are now entering a new phase of clinical immunosuppression where we need to learn how to best combine the agents that are currently available to provide the safest and most effective immunosuppression for patients undergoing heart or lung transplantation.