Study in Recipients of Renal Transplant Allograft to Evaluate the Impact of Two Immunosuppressive Regimens

Overview

The immune system is the body's defense against infection and other disease. After transplantation, the body sees the new organ as "foreign" and tries to destroy or "reject" it. Immunosuppressive medications help to prevent the immune system from attacking a transplanted organ. The primary purpose of this study is to investigate the impact of two maintenance immunosuppressive regimens. Subjects who enroll in this study will be randomly selected to have tacrolimus and everolimus (group 1) or tacrolimus and mycophenolate mofetil (group 2) as their immunosuppression medication. This study will enroll adult patients who are scheduled to receive a kidney transplant. The study is designed to understand the mechanisms of Everolimus in regards to kidney function in transplant recipients. The investigators hypothesis is that decreased exposure to Tacrolimus to the immune system will then translate in better renal allograft function.

Immunosuppressive therapy with the calcineurin inhibitors (CNI) Cyclosporine (CsA) and Tacrolimus (Tac), have radically changed the field of organ transplantation. Ironically, although extensively and effectively used for kidney transplantation and other solid organ transplants, CsA and Tac cause important adverse renal side effects: acute and chronic renal dysfunction, hemolytic-uremic syndrome, hypertension, electrolyte disturbances and tubular acidosis. Chronic nephrotoxicity from CNI has been implicated as a principal cause of post-transplant renal dysfunction and it is characterized by an irreversible and progressive tubular atrophy, interstitial fibrosis, and focal hyalinosis of small renal arteries and arterioles. Furthermore, this class of medications is associated also, by blocking Interleukin-2 (IL2) production, with negative impact on regulatory T cells (T-Regs) generation (an important subpopulation of T helper cells that has been associated with positive immunomodulation and donor specific hypo responsiveness). In renal transplant recipients, complete avoidance of calcineurin inhibitors from the time of renal transplant surgery has been associated with increased incidence of acute cellular rejection, and the combination of mammalian target of rapamycin (mTOR) inhibitors with full dose CNI has been shown to be synergistically nephrotoxic and it has been associated with poor graft outcome. CNI conversion to mTOR inhibitors, at different time point post-transplant, has been tested with promising results, by different investigators and by the investigators group. The investigators have shown that in a Prednisone-free immunosuppression, conversion from Tacrolimus to mTor inhibitors at different time point post transplant is safe, it is not associated with an increased risk of acute rejection and more importantly it is associated with an a persistent increase of regulatory T cells (Data presented at the American Transplant Congress (ATC) 09 and 2010) Recently the A2309 study allowed Everolimus to be FDA approved. The A2309 was a study designed to combined reduced dose Cyclosporine+Everolimus. Interesting the reduced exposure to Cyclosporine was not associated with an increase rate of albumin-creatinine ratio (ACR) and renal allograft function was well maintained compared to the control group. The A2309 opens then an important question regarding the mechanism(s) that can explain the efficacy of a low dose CNI with an mTOR inhibitor in preventing acute allograft rejection. The present proposal is designed to understand the mechanisms of the synergistic effect(s) of low dose CNI and mTOR inhibitors (Everolimus) in controlling allo-reactive T and B cells while expanding T-Regs. The investigators hypothesis based in published data and from their laboratory (see preliminary data-Supportive documents), is that mTOR inhibitors allow expansion of T-Regs and low exposure of CNI is sufficient to control allo-reactive T cells. Decrease exposure to CNI and concomitant increase of T-Regs will then translate in better renal allograft function and histology.