Introduction: Reduction of immunosuppression (IS) in response to BK viremia following kidney transplantation prevents the development of BK virus nephropathy, with no apparent increase in acute rejection rates. However, reduced IS is associated with development of donor specific antibodies, which is a risk factor for long term graft failure. It is unknown whether resumption of standard dose IS after viremia resolution can be achieved without viremia recurrence. To answer this question, we developed a protocol of IS reduction followed by resumption of standard dose IS after BK clearance.

Methods: Thirty-six consecutive kidney transplant recipients who developed BK viremia from 7/1/2014 until 12/1/2016 were studied. Upon detection of BK viremia, mycophenolate mofetil (MMF) and tacrolimus were immediately reduced to a daily dose of 1000mg and to trough levels of 3-5 ng/L, respectively. If BKV levels failed to decline progressively after 2 months, MMF was reduced further to a daily dose of 500mg/day, and ultimately discontinued if viremia persisted. After 4 weeks of absent viremia, MMF was increased by 500mg/day every two weeks up to pre-viremia dosage if BKV levels remained negative, followed by increase of tacrolimus trough levels to 5-7 ng/L. If viremia recurred during this increase, IS was reduced back again in this same stepwise fashion, with increase again after 2 months of negative viremia.

Results: The median time from transplant to BK viremia onset was 89 days (range:29-398) and median duration of viremia was 47 days(range:7-332). Mean level of tacrolimus was 8.3+2.7ng/L at onset, 5.3+3.6ng/L at resolution, with a final level of 5.5+2ng/L. Mean daily dose (mg) of MMF at onset was 1570+350, 910+230 at resolution, with a final dose of 1290+470. Two patients (5.5%) developed acute rejection following IS reduction. Two patients (5.5%) have not yet cleared with IS reduction. Only one patient developed low level viremia recurrence (peak 2875 copies/mL) during the period of IS increase and has not yet reached target IS goal (current 252 copies/mL).

Conclusion: Following BK viremia resolution, an increase in IS to pre BK viremia levels can be achieved safely in almost all patients without BK viremia recurrence. Longer-term trials will be needed to determine whether such an approach leads to improved long-term graft survival.

CITATION INFORMATION: Alquadan K, Santos A, Casey M, Ozrazgat-Baslanti T, Bozorgmehri S, Gregg J, Womer K. Resumption of Standard Dose Immunosuppression Following Resolution of BK Viremia Does Not Lead to Viremia Recurrence. Am J Transplant. 2017;17 (suppl 3).

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