Tacrolimus in heart transplantation

Tacrolimus (Tac), which blocks T- and B-cell proliferation by inhibiting calcineurin, was first used for immunosuppression following heart transplant (HT) in 1989. Two multicenter randomized trials have compared Tac to the oil-based cyclosporine (CsA) formulation (both combined with azathioprine and steroids) in HT patients. The two drugs displayed similar patient survival rates and incidences of rejection, nephrotoxicity, diabetes, and infections. The Tac group however, showed a lower incidence of arterial hypertension (and, in one study, of dyslipidemia). A pilot study of Tac in combination with mycophenolate mofetil (MMF) and steroids suggested that maintenance of serum mycophenolic acid levels at 2.5 to 4.5 mug/mL yields lower rejection rates without greater toxicity than previous regimens. Currently, a European multicenter randomized trial is comparing Tac with Neoral CsA, both used in combination with MMF, steroids, and induction antibodies. For patients undergoing primary immunosuppression with CsA, Tac has proved effective for rescue from steroid-resistant acute rejection. It also has tentatively been used without other drugs in selected patients. It is a valid alternative to CsA in current immunosuppressive regimens, because it does not cause gingival hyperplasia or hirsutism and, thus, may improve the quality of life and treatment compliance of female and pediatric patients. It may be preferable to CsA for patients with arterial hypertension or intractable dyslipidemia. Current and future studies will clarify the efficacy and safety of regimens combining Tac with MMF or rapamycin.