Extended Release Versus Immediate Release Tacrolimus Following Renal Allograft Failure to Reduce Allosensitisation

Inclusion Criteria: 1. Able to give informed consent. 2. Male or female, at least 18 years of age. 3. Has renal allograft failure and is due to start haemodialysis therapy or within 28 days following starting dialysis. 4. Has been already activated on the transplant wait list or is undergoing work up to be reactivated on the transplant list. 5. Has no indication for graft nephrectomy at the time of transplant failure. 6. Is receiving an immediate release tacrolimus maintenance immunotherapy regimen at the time of allograft failure. Exclusion Criteria: 1. Has another functioning organ transplanted (eg. pancreas, liver, cardiac) at the time of kidney allograft failure. 2. Allograft failure within a month of transplant. 3. Patients who are due to receive or receiving peritoneal dialysis following graft failure. 4. Patients with detectable DSA at the time of allograft failure 5. Receiving an extended release preparation of tacrolimus as immunotherapy at the time of graft failure. 6. Requires continuation of maintenance immunosuppression other than prednisolone or tacrolimus (eg. Mycophenolate mofetil or sirolimus). 7. Patients who on IR-FK conversion would require less than 0.75mg of Envarsus. 8. HLA type of donor is unknown. 9. Has a history of, or active co-morbidity that in the Investigator's opinion, could affect the conduct of the study. 10. Has any condition at the time of recruitment which would prohibit or pose a relative contraindication for the continued use of tacrolimus to a target trough level of between 3-5ng/ml 11. Active bacterial, viral (including CMV and EBV) or parasitic infections, including tuberculosis that, in the Investigator's opinion, could affect the conduct of the study. 12. Has active malignancy. 13. Female patients of child bearing age, who wish to consider pregnancy.