The use of an anti-CD25 monoclonal antibody and mycophenolate mofetil enables the use of a low-dose tacrolimus and early withdrawal of steroids in renal transplant recipients.

BACKGROUND: Reducing calcineurin-inhibitor-induced nephrotoxicity and simultaneously avoiding long-term steroid related side-effects is a desirable goal in renal transplantation. We examined the hypothesis that using anti-CD25 monoclonal antibody induction and mycophenolate mofetil (MMF) would allow the lowering of target pre-dose blood concentrations of tacrolimus immediately after transplantation and subsequently stopping steroids at 5 months.

METHODS: Eighty-two kidney recipients were enrolled in a single-center study comparing two tacrolimus-based protocols. Group I (n = 41) patients received a standard-dose tacrolimus (blood concentration 10-15 ng/mL) with MMF and a standard dose corticosteroid. Group II (n = 41) patients were treated with a low-dose tacrolimus (blood concentration 5-10 ng/mL) and MMF, a low-dose corticosteroid (stopped after 5 months) and induction with daclizumab.

RESULTS: Patient (95.1 versus 100%) and graft survival (92.6 versus 97.5%) at 1 yr were not different between groups. Patients of group II experienced significantly less acute rejections than group I (17.1 versus 41.4% p = 0.03). Delayed graft function occurred less often in group II (5 versus 12% p = 0.43). Graft function at 1 yr was significantly better in group II (serum creatinine 1.49 versus 1.69 mg/dL and creatinine clearance 59.6 versus 49 mL/min; p < 0.05). Corticosteroids could be stopped after 5 months in 82.9% of group II patients.

CONCLUSION: A regimen consisting of anti-CD25 monoclonal antibody induction and MMF allows the safe and efficient use of low-target pre-dose trough concentrations of tacrolimus and enables the early discontinuation of steroids. Preliminary results indicate a better 1-yr graft function compared to a normal-dose tacrolimus regimen.