The goal of this clinical trial is to compare the degree of HLA sensitization at 2 years in patients with late renal graft failure (> 3 months) when receiving reduced immunosuppressant treatment versus stopping immunosuppression at 6 months.

The main question this study aims to answer is:

Does maintaining long-term immunosuppression in patients with a late renal graft failure (> 3 months) safely reduce the risk of HLA sensitization?

To answer this question, patients will be assigned to a control arm or investigational arm:

• Patients assigned to the control arm will receive standard treatment, in which immunosuppressant treatment is withdrawn after 6 months.
• Patients assigned to the investigatonal arm will continue immunosuppressant treatment at low doses for 2 years.

Patients recruited in this clinical trial will be followed for up to 2 years. During this time, patients will visit the clinic every 3 months for checkups and tests.

Inclusion Criteria:

• Patient must be able to understand and provide written informed consent
• Patients older than 18 years who had received at least one previous renal transplant
• Patients with a retained kidney graft failed for any reason which survived at least 3 months
• Patients on dialysis, either hemodialysis or peritoneal dialysis. Patients can be on dialysis for a maximum of 6 months at the time of randomization, as long as the patients have taken an uninterrupted immunosuppressive regimen of calcineurin inhibitors (tacrolimus or cyclosporine) and steroids since dialysis was restarted
• Patients already relisted or candidates to relist to deceased donor kidney transplantation according to the treating physician criteria
• Patients taking immunosuppressants tacrolimus or cyclosporine
• cPRA at the time of randomization ≤ 90%

Exclusion Criteria:

• Patients who have received another solid organ transplantation (liver, lung, heart or pancreas)
• Patients waiting for a living related / unrelated kidney transplant
• Graft survival of the failed graft lower than 3 months
• Patients in dialysis more than 6 months at the time of randomization
• Patients not accomplishing criteria to relist in the transplantation list according to the treating physician criteria
• Pregnant women
• Females of childbearing age who have not used or do not plan to use acceptable birth control measures, for the duration of the study. Patients should use one of the acceptable birth control measures recommended in the document "Recommendations related to contraception and pregnancy testing in clinical trials" published by the Clinical Trials Facilitation and Coordination Group (CTFG) (version 1.1, published 21/09/2020). Recommended birth control measures include oral, injected or implanted hormonal contraceptive, barrier methods (condom or diaphragm with spermicide), intrauterine device, surgical sterilization, transdermal delivery, or sexual abstinence. If sexually active, the subject must have been using one of the accepted birth control methods at least one month prior to study entry.