Latent BK infection is benign and common in transplanted kidneys, but active infection causes viremia and kidney damage. Standard practice is to reduce tacrolimus (TAC) stepwise until viremia abates. However, recent reports describe new-onset antidonor antibodies (DSAs) due to increased antigenicity of infected tubules and reduced immunosuppression. We report 9 patients who were refractory to TAC reduction, in whom we substituted full dose cyclosporin (CSA) for minimized TAC, with dramatic control of viremia.

BK viremia was first detected 7.4 +/- 9 (mean +/- SD) months after transplantation. MMF was discontinued and TAC reduced over 40% over 5.7 +/- 9 months, decreasing trough from 10.6 +/- 3 to. 5.3 +/- 6 ng/ml. However, viremia increased almost tenfold, from an initial 148,818 +/- 303,770 to 1,399,399 +/- 1,746,825 copies/ml. 3 of 3 biopsies showed BK nephropathy. CSA conversion at that point permanently reduced BK pcr over 99% to < 10,000 copies by 3.7 +/- 3 months. Daily CSA dose at 3 months was 214 +/- 86 mg, given BID, with 2-hour peak levels of 741 +/- 138 and trough levels of 111 +/- 53 ng/ml.

Serum creatinine was 1.6 +/- 0.5 at detection, and 1.7 +/- 0.6 mg/dl when BK pcr was < 10,000 copies/ml. One biopsied patient had a pre transplant DSA that disappeared after a year on CSA. DSAs developed in another patient during TAC minimization, and in two more nonadherent patients after a year on CSA.

In summary, conversion to full dose CSA permanently controlled aggressive BK viremia that was unresponsive to markedly reduced TAC exposure. No patients failed to respond to CSA conversion. Our results suggest a permissive effect of TAC — but not CSA — on BK viral replication. Earlier institution of CSA may reduce DSA formation in this high risk group.Reduction of viremia with CSA in patients not included in the figure:

CITATION INFORMATION: Caero A, Shah M, McKay D, Kerr J, Joliat J, Chatfield E, Steiner R. Full Dose Cyclosporine Permanently Reverses Uncontrolled BK Viremia That Is Refractory to Tacrolimus Minimization. Am J Transplant. 2017;17 (suppl 3).

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