Background: Interest has recently been expressed in tacrolimus and mycophenolate mofetil (MMF), two potent immunosuppressants, for a variety of transplant indications. The efficacy of this combination was assessed as primary therapy following cardiac transplantation.
Methods: Forty-five patients were enrolled; 15 into Phase I and 30 to Phase II of the study. Intravenous tacrolimus was administered for 2-3 days to all patients prior to conversion to oral therapy; target blood concentrations were 10-15 ng/mL. Treatment also consisted of steroids and MMF. During Phase I, a fixed 2 g/day dose of MMF was given whilst doses were adjusted according to mycophenolic acid (MPA) plasma levels during Phase II (target range 2.5-4.5 microg/mL). Mean follow-up was 696 +/- 62 days and 436 +/- 88 days for Phases I and II, respectively.
Results: Phase I: Patient survival was 100%. Rejection was diagnosed in 66.7% of patients (mean number of episodes per patient 1.33 +/- 1.18). Retrospective analyses indicated that whereas mean MPA plasma levels >3.0 microg/mL were not associated with rejection, no correlation was found with tacrolimus blood concentrations. Phase II: A survival rate of 96.7% was evident, one patient having died from aspergillosis. Diagnoses of rejection were made in 10.0% of patients (0.10 +/- 0.31 episodes per patient) and confounding factors were present in all 3 cases. MPA trough levels were 1.0 +/- 0.3 microg/mL at this time. Resolution was apparent following pulse steroid therapy. Steroids were successfully withdrawn from all patients who completed 6 months' treatment.
Conclusions: Combination therapy with tacrolimus and MMF is associated with suppression of acute myocardial rejection; however, this is dependent upon routine therapeutic drug monitoring.