While short-term graft outcomes in kidney transplantation have improved, this requires adherence to a complex medication regimen. The current twice-daily immunosuppressive regimen, immediate release tacrolimus and mycophenolate mofetil/mycophenolic acid, has reduced rejection rates significantly, but frequently cause neurologic and gastrointestinal side effects which impact recipient quality of life. These side effects often require dose adjustments and studies have shown inferior outcomes when multiple changes are made to the immunosuppressive regimen. Furthermore, patients taking twice-daily medications have poorer compliance and yet adherence to these medications is critical to mitigate the risk of allograft rejection. Acute and chronic rejection are important causes of graft failure and patient survival.~Immediate release (IR) tacrolimus based immunosuppressive regimens have become the standard of care at most US centers. With the introduction of a once-daily tacrolimus formulation, kidney transplant recipients can now be on a combination regimen (EnvarsusXR and azathioprine) that permits all immunosuppressive medications to be taken once a day instead of twice . Previous studies suggest that therapeutic goals with EnvarsusXR may be achieved at a lower dose than the currently recommended dose. This once a day medication schedule has the potential to simplify the immunosuppressive regimen by reducing adverse side effects and facilitating compliance.~The investigators seek to demonstrate that a once-daily regimen, including EnvarsusXR and azathioprine, will be at least equally effective with respect to acute rejection, graft and patient survival as compared to the standard, twice-daily, immediate release tacrolimus and mycophenolate mofetil/mycophenolic acid. The investigators will also assess graft function, medication complications and side effects in each arm.
The purpose of this study is to determine if the combination of once-daily tacrolimus extended-release (EnvarsusXR) and Azathioprine is non inferior with respect to the composite outcome of acute rejection, graft and patient survival as compared to a combination of twice-daily immediate release tacrolimus and mycophenolate mofetil/mycophenolic acid.