BK‐Virus and the Impact of Pre‐Emptive Immunosuppression Reduction: 5‐Year Results

A 1‐year, single‐center, randomized trial demonstrated that the calcineurin inhibitor or adjuvant immunosuppression, independently, does not affect BK‐viruria or viremia and that monitoring and pre‐emptive withdrawal of immunosuppression was associated with resolution of BK‐viremia and absence of clinical BK‐nephropathy without acute rejection or graft loss. A retrospective 5‐year review of this trial was conducted. In cases of BK viremia, the antimetabolite was withdrawn and for sustained viremia, the calcineurin inhibitor was minimized. Five‐year follow‐up was available on 97% of patients. Overall 5‐year patient survival was 91% and graft survival was 84%. There were no differences in patient‐survival by immunosuppressive regimen or presence of BK‐viremia. Immunosuppression and viremia did not influence graft survival. Acute rejection occurred in 12% by 5‐years after transplant, was less common with tacrolimus versus cyclosporine (9% vs. 18%; p = 0.082), and was lowest with the tacrolimus‐azathioprine regimen (5%, p = 0.127). Tacrolimus was associated with better renal function at 5‐years (eGFR 63 FK vs. 52 CsA mL/min, p = 0.001). Minimization of immunosuppression upon detection of BK‐viremia was associated with excellent graft survival at 5‐years, low rejection rates and excellent renal function. It is a safe, short and long‐term strategy that resulted in freedom from clinically evident BK‐virus nephropathy.