Randomized Conversion of Calcineurin-Inhibitors in Renal Allograft Recipients

Sirolimus will initially be given at a dose of 2-4 mg orally (PO) daily. The dose will be modified to achieve 24 hours trough concentrations of 6-10 ng/ml by high-performance liquid chromatography (HPLC) assay. This medication will be given in an open label fashion. The first dose of sirolimus will be given at the time of randomization to those patients assigned to have tacrolimus switched to sirolimus.

Age at transplant, sex, race, cause of end-stage renal disease, medical history, donor age, cadaveric vs. living kidney transplant, histocompatibility/cross match data, viral serology, history of acute rejection and delayed graft function, use of induction therapy and immunosuppressants, use of Angiotensin Converting Enzyme Inhibitor (ACEI) and/or Angiotensin Receptor Blockers (ARB) level of renal allograft function-estimated GFR (e-GFR(12) using Modification of Diet in Renal Disease (MDRD) formula, proteinuria.

Subjects maintaining standard of care drug treatment of TAC and MMF will have monthly labs in addition to the baseline pre-randomization labs, at 6, 12, and 24 Months post-randomization. Peripheral blood leukocytes will be obtained.

This group will have monthly labs taken but will also have weekly labs during the period of conversion to monitor renal function and bone marrow function. In addition to the baseline pre-randomization labs, and labs collected at 6, 12, and 24 Months post-randomization, peripheral blood leukocytes will be obtained.

Peripheral blood leukocytes from living donors obtained at the time of randomization. These donor leukocytes will be used as stimulator cells to study the functional activity of the recipient's lymphocytes function.

Donor age, cadaveric vs. living donor, and histocompatibility and cross match to recipient

Kidney biopsy at 24 Months to compare to the standard of care biopsy taken at 12 Months. This information will help evaluate renal allograft pathology and renal allograft tissue gene expression profiles of the two groups. Renal allograft biopsies will be stored in RNA later (preservative) to further extend knowledge on the effect of calcineurin-inhibitors (CI) free immunosuppression on gene expression profiles.