Belatacept 3 Month Post Transplant Conversion Study

Overview

This study is being done to investigate the impact of changing immunosuppressive medications from tacrolimus (Prograf®) to belatacept (Nulojix®) between three (3) and six (6) months after kidney transplantation. 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 the transplanted organ. The primary purpose of this research study is to evaluate the effects of three (3) different immunosuppressive treatments on rejection in post-transplant kidney recipients. This study will test whether switching from tacrolimus to belatacept will improve long-term kidney function. Three of the immunosuppressants used in this study- mycophenolic acid (MPA), mycophenolate mofetil (MMF) and tacrolimus- are medications approved by the United States Food and Drug Administration (FDA) to be used after transplant. All of these medications have been routinely used in kidney recipients here at Northwestern University. Belatacept (the "study drug") has been approved by the FDA for use at the time of transplant. However, the use of belatacept in this study is considered investigational as it has not been FDA approved for use beginning at 3 months after transplant. This study will involve 51 adult kidney transplant recipients at Northwestern.

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. Attempts to minimize CNIs and their known toxicities have been marginally successful due to unacceptable rates of acute rejection and drug toxicity. Patients are converted to alternative immunosuppressive therapy related to CNI side effects including neurotoxicity, nephrotoxicity, cardiovascular (HTN, hyperlipidemia), metabolic (NODAT), and cosmetic side effects. Furthermore, this class of medications is associated also, by blocking Interleukin 2 (IL2) production, with negative impact on regulatory T cells (Tregs) generation (an important subpopulation of T helper cells that has been associated with positive immunomodulation and donor specific hypo-responsiveness). Until the approval of Belatacept for adult EBV+ renal transplant recipients, there have been limited alternative immunosuppressive agents available to mitigate drug induced renal impairment. The phase III drug trials of Belatacept in combination with MMF and corticosteroids have resulted in significant and sustained improvement in glomerular filtration rate (GFR) at one year through three years post transplant. The overall safety of belatacept compared to cyclosporine in de novo transplant recipients was similar. However, there was an increased rate and severity of early acute rejection and post-transplant lymphoproliferative disorder (PTLD) of the central nervous system in patients treated with belatacept. In a phase II switch study conducted by Bristol Myers Squibb (BMS), the incidence of acute rejection at 24 months post conversion was similar in patients remaining on CNI (4%) compared to those converted to belatacept (7%). There were no reported cases of post-transplant lymphoproliferative disorder (PTLD) in this patient population as of two years post randomization. However, one belatacept patient from Mexico developed tuberculosis and there were more non-serious fungal infections in the belatacept treated patients. Mechanistically, CD28 (Cluster of Differentiation 28) and CTLA-4 (cytotoxic T-lymphocyte-associated protein 4) are important for the function of regulatory T cells (Tregs). Belatacept binds to CD80/CD86 (Cluster of Differentiation 80/Cluster of Differentiation 86) ligands on antigen presenting cells (APCs) preventing CD28 to bind with these ligands and deliver the costimulatory signal to activate the T Cell. CTLA-4 is a related receptor expressed on activated T cells that also recognizes CD80/CD86 (Cluster of Differentiation 80/Cluster of Differentiation 86) and is thus termed co-inhibitory. It transmits both cell intrinsic and cell extrinsic negative signals that impair activation. Investigation of the effect of early conversion to Belatacept at month 3 post-transplant on the subpopulations of T cells and B cells and peripheral blood and allograft biopsy-derived gene expression subpopulation profiles are planned. Optimization of the Belatacept immunosuppressive regimen to achieve good long term renal function and improved graft survival requires understanding the relationships of these cell populations to clinical outcomes.