BK polyomavirus and valganciclovir: Evidence is still lacking

CMV infection, valganciclovir exposure, and the risk of BK viremia and associated nephropathy after kidney transplantation: Is there a link?

BACKGROUND

Immunomodulatory effects attributable to cytomegalovirus (CMV) would predispose to BK polyomavirus (BKPyV) infection after kidney transplantation (KT), although available evidence is conflicting. It has been suggested that (val)ganciclovir therapy may increase the risk of BKPyV viremia and BKPyV-associated nephropathy (BKPyVAN) as a result of drug-induced T-cell impairment.

METHODS

We investigated whether CMV replication and/or (val)ganciclovir exposure (either as prophylaxis or treatment) were associated with the development of BKPyV viremia or BKPyVAN in a prospective cohort of 399 KT recipients. CMV infection (any level or high-level viremia and area under the curve of DNAemia) and (val)ganciclovir exposure (any duration of therapy and cumulative days of treatment) during the first post-transplant year were explored through separate landmark survival analyses.

RESULTS

Cumulative incidence of BKPyV viremia and BKPyVAN after a median follow-up of 551 days was 23.1% and 2.5%, respectively. One-year rates of CMV infection and (val)ganciclovir therapy were 47.4% and 54.1%, respectively. No differences were observed in BKPyV viremia- or BKPyVAN-free survival according to previous CMV infection or (val)ganciclovir exposure in any of the landmark analyses. Adjusted Cox models confirmed this lack of association.

CONCLUSION

Our findings do not confirm the existence of a relevant impact of CMV infection or (val)ganciclovir therapy on the risk of post-transplant BKPyV events.

Clinical features of BK-polyomavirus and cytomegalovirus co-infection after kidney transplantation

BK polyomavirus (BKPyV) and cytomegalovirus (CMV) are the main viral pathogens affecting the graft and recipient outcome after allogenic kidney transplantation. It has recently been found that infection with both viruses has a greater impact on kidney graft function than a single infection. We retrospectively analyzed a cohort of 723 recipients who received kidney transplantation between 2007 and 2015 after living and postmortal donation for differences in risk and outcome parameters regarding BKPyV (DNAemia) and CMV (CMV DNAemia) co-infection compared to sole viremias and to patients without viremia. Of all kidney allograft recipients in our cohort, 8.2% developed co-infection with BKPyV DNAemia and CMV DNAemia, 15.1% showed BKPyV viremia alone and 25.2% sole CMV DNAemia. Acute rejection was closely linked with co-infection (multivariable analysis, p = 0.001). Despite the fact that the estimated glomerular filtration rate of patients with co-infection was noticeably reduced compared to patients with BKV or CMV infection alone, transplant survival and patient survival were not significantly reduced. Co-infection with BKPyV and CMV in kidney transplanted patients is significantly associated with inferior allograft function. Since co-infection is strongly associated with acute rejection, co-infected individuals should be considered a risk collective.