BK-virus and the impact of pre-emptive immunosuppression reduction: 5-year results

Abstract

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 In cases of BK viremia, the antimetabolite was withdrawn and for sustained viremia, the calcineurin inhibitor was minimized.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.

Figure 1

Patient Survival at 5-years: Sustained viremia (73%) vs no sustained viremia (92%); P=0.044

Figure 2

Acute Rejection at 5-years: Tacrolimus (9%) vs Cyclosporine (18%); P=0.082

Figure 3

Acute Rejection by Immunosuppressive Regimen at 5 years: FK-AZA (5%), FK-MMF (14%), CsA-MMF (17%), CsA-AZA (19%); P=0.127