Comparison of Sirolimus to Tacrolimus for Long Term Therapy in Kidney Transplant With no Steroids

Abstract: Corticosteroids have been a mainstay of immunosuppression for kidney transplantation, but they are associated with significant toxicity after long-term use. Recent studies have concluded that steroid avoidance is safe and effective when combined with modern immunosuppressive maintenance therapy in low risk kidney transplant recipients. These studies have included antilymphocyte induction therapy with either an anti IL-2 receptor antibody, or an antithymocyte globulin, such as rabbit polyclonal antithymocyte globulin (Thymoglobulin). Mayo Clinic Scottsdale has adopted Thymoglobulin induction, tacrolimus, and mycophenolate mofetil with rapid steroid taper as their standard immunosuppressive therapy in low risk patients. Mayo Clinic Jacksonville is also utilizing this protocol. Together, both sites have utilized this approach in 64 patients. Recent improvements in immunosuppressive regimens have decreased acute rejection in kidney transplant recipients and increased one-year graft survival to nearly 90%. However, long-term graft survival has changed little with 30% of grafts being lost to ''chronic allograft nephropathy'' (CAN) in the first five years after transplantation. A recent paper highlighted this dilemma and demonstrated that a major cause of late CAN was chronic exposure to the nephrotoxic effects of calcineurin inhibitors (CNI) tacrolimus and cyclosporine and possibly cytomegalovirus infection. In this study, we will focus on the role of CNI in CAN. We propose a prospective, randomized, non-blinded trial of Thymoglobulin induction with rapid steroid elimination accompanied by tacrolimus (TAC) and mycophenolate mofetil (MMF) maintenance therapy. Patients are to be randomized at 1 month post-operatively to either remain on TAC/MMF or switch to SRL/MMF. The primary endpoint will be renal function at 1-year post-transplant. Secondary endpoints will include renal function at 2 years post-transplant, histology seen on protocol biopsies at 1 and 2 years post-transplant, incidence of biopsy proven rejection at 12 months, patient survival, graft survival, proportion of patients steroid free at 12 months, infectious complications, bone mineral density analysis, incidence of hyperlipidemia, and the incidence of new onset post-transplant diabetes mellitus.