BK virus nephropathy: a pediatric nephrologist's perspective

Leflunomide as adjunct therapy for BK viremia management in pediatric kidney transplant recipients

BACKGROUND

BK viremia after kidney transplantation (KT) poses significant risk for BK virus-associated nephropathy and impacts graft survival. Conventional treatment involves reduction of immunosuppression, which in turn may increase risk for rejection. To address this dilemma, use of anti-viral therapy with immunosuppressive properties such as leflunomide is an attractive option.

METHODS

We performed a multi-center, retrospective chart review to report tolerability and effectiveness of leflunomide use for the eradication of BK viremia and prevention of BK virus-associated nephropathy in pediatric KT recipients.

RESULTS

Seventy patients prescribed leflunomide were included and were followed up from initiation until 1 year following leflunomide completion. BK viremia was eradicated in 64 (91.4%) patients including 8 of 11 with nephropathy (BKVN) on initial biopsy. Reduced anti-proliferative medication (AP) dosing was not associated with increase in biopsy proven rejection (BPAR). However, complete discontinuation of AP during leflunomide therapy was associated with increase in BPAR in uni- and multivariate logistic regression, as was targeted reduction in calcineurin inhibitor (CNI) trough goals. One graft was lost to BKVN. There was no significant association found between time to BK eradication and leflunomide trough concentration, mycophenolate dose reduction, or steroid use (univariate logistic regression). Few leflunomide adverse drug reactions (ADR) were reported (most commonly: gastrointestinal, hematologic).

CONCLUSION

Leflunomide is a promising adjunctive treatment to immunosuppression reduction for BK virus eradication with minimal ADR. AP reduction, not discontinuation, and judicious reduction in CNI trough goals with close monitoring, is a promising strategy for treatment of BK viremia with concomitant use of leflunomide therapy.

BK polyomavirus infection in pediatric heart transplant recipients: a prospective study

BKV infection and nephropathy complicate pediatric HTx, but the incidence and time course of the disease are unknown. We assessed the incidence of BKV infection and its association with kidney dysfunction in pediatric HTx recipients. A single center prospective study compared pediatric (<18 years) HTx recipients, with and without BKV infection, who received an allograft between September 2013 and December 2014. Screening of urine for BKV was performed prior to transplant, and at week 1, and at months 3, 6, 9, 12, and 15 months post-transplantation. Serum for BKV DNA was assayed if BK viruria was present. Statistics included Fisher's exact test and Student's t test. Twelve patients were enrolled. Two patients were removed per parent request. Two (20%) had BK viruria and one (10%) had BK viremia. No patients developed BKVN. BK viruria was present within 2 months following transplantation. There were no identifiable risk factors for BKV infection and no statistically significant difference in renal function between the groups; however, there was a trend toward worsening renal function in those with BKV infection. BKV infection can occur early following heart transplantation. Screening for BK viruria should be considered in HTx recipients.

Perception, diagnosis and management of BK polyomavirus replication and disease in paediatric kidney transplant recipients in Europe

BACKGROUND

BK polyomavirus (BKPyV)-associated nephropathy remains a challenge to the success of kidney transplantation, but its impact varies in different transplant programmes.

METHODS

We investigated current practice through a web-based questionnaire made available by the European Society for Paediatric Nephrology (ESPN).

RESULTS

A total of 90 physicians (23% of 391 active members) from 27 countries participated in the study. BKPyV-associated nephropathy is seen in 1-5% of patients annually with treatment success in 30-60%, and graft loss in 10%. Quantitative BKPyV load testing is available to >90% of physicians. Screening is performed in urine alone in 26%, in urine and blood in 37% and in blood alone in 37%. Most physicians (47%) screen at month 1, 2, 3, 6, 9 and 12 post-transplant. For patients with baseline renal function and plasma BKPyV loads of 10 000-1 000 000 copies/mL, 50% report performing renal biopsies prior to intervention. Intervention consists of reducing immunosuppression first with mycophenolate (Myc) in 40%, first with calcineurin inhibitors (CNI) in 29% or with both in 31%. Changing immunosuppressive drugs is considered mainly for biopsy-proven nephropathy consisting of discontinuation of Myc in 75%, and switching from CNI to mTOR inhibitors (52%). Cidofovir, intravenous immunoglobulin G, leflunomide and fluoroquinolones are used in less than one-third of this group. Furthermore, 66% of participants see a need for new antiviral drugs and new immmunosuppressive strategies, and almost 90% are willing to participate in future observational and interventional trials.

CONCLUSION

This ESPN survey suggests that prompt translation of a positive screening test into reducing immunosuppression could improve outcomes.

Prevalence of BK polyomavirus infection and association with renal dysfunction in pediatric heart transplant recipients

BACKGROUND

BK polyomavirus (BKV) infection and nephropathy complicate renal allografts; however, their effect in the native kidneys of pediatric heart transplant (HTx) recipients is unknown. We assessed the prevalence of BKV infection and its association with kidney dysfunction in survivors of pediatric HTx.

METHODS

A single-center retrospective study compared pediatric (aged <18 years ) HTx recipients, with and without BKV (controls), who received an allograft from May 1989 to July 2013. Screening of urine for BKV was performed in patients with chronic kidney disease (CKD) stage ≥2 since 2006, and since April 2012 in all HTx recipients at least at an annual evaluation. Serum for BKV DNA was assayed if BK viruria was present. Data collected included recipient and donor demographics, the immunosuppressive regimen, and history of Epstein-Bar virus (EBV) and cytomegalovirus infection. Statistics included Fisher's exact test, chi-square test, Student's t-test, and multivariate logistic regression.

RESULTS

Of 98 eligible recipients, 83 (85%) were screened: 28 (34%) had BK viruria, and 7 had BK viremia. One viremic patient had biopsy-proven BKV nephropathy that progressed to end-stage renal disease. Risk factors for BK viruria were (1) longer duration since HTx (6.02 vs 2.95 years; p = 0.01), (2) worsening estimated glomerular filtration rate (71.3 vs 86.3 ml/min/1.73 m(2), p = 0.03), (3) history of EBV infection (p = 0.0002), and (4) use of sirolimus (p = 0.0003). After multivariate logistic-regression, only history of EBV infection remained associated with BKV infection (p = 0.015).

CONCLUSIONS

BKV may lead to BK viremia and BK nephropathy in pediatric HTx patients. Routine screening for BK viruria should be considered.

Recent developments in kidney transplantation in children

PURPOSE OF REVIEW

Renal transplantation in childhood is a well established procedure with excellent short-term outcomes. However, waiting times for transplantation are still relatively long if living donation cannot be performed, and long-term outcomes after transplantation have not significantly improved during the last decade.

RECENT FINDINGS

This review describes alternative modalities to improve donation rates such as en bloc kidney transplantation from young donors, ABO-incompatible transplantation and kidney paired donation. This review also deals with long-term post-transplant morbidities, such as follows: first, medication side-effects (metabolic syndrome, cardiovascular disease) and with the benefits of steroid and calcineurin inhibitor drug minimization; second, the deleterious impact of viral infections and their management and third, chronic antibody-mediated rejection, its therapeutic and prevention possibilities.

SUMMARY

Donor shortage and long-term morbidities, after transplantation, are still relevant issues in paediatric renal transplantation medicine. Significant research and efforts have been made to advance the field and create novel approaches for improvement of transplantation rates and post-transplant graft or patient survival. These modalities are to be established in the routine setting.

Leflunomide therapy for BK virus allograft nephropathy after pediatric kidney transplantation

The BK virus (BKV) can be reactivated with immunosuppressive treatment in renal allograft recipients, which can result in interstitial nephritis (BKV-associated nephropathy, BKVAN) and lead to renal allograft failure. Recently, leflunomide has been reported in some case series of BKVAN with favorable results. Most studies have included only adult patients, we herein report a pediatric case and include a literature review. The patient was a nine-yr-old female with end-stage renal disease due to hypoxic kidney injury. A deceased donor renal transplant was performed and good initial allograft function was achieved following treatment with prednisolone, tacrolimus and mycophenolate mofetil. The serum Cr level increased to 1.6 mg/dL over the following four-month period. A kidney biopsy revealed pathologic findings of acute cellular rejection and BK nephropathy. After methylprednisolone pulse therapy was administered to control acute rejection, the tacrolimus dose was reduced, and intravenous immunoglobulin treatment and leflunomide therapy were administered to control the BKVAN. Over the following 18 months, the viral load steadily decreased and remained below 100 copies/mL in the plasma. Leflunomide therapy in addition to a reduction of the immunosuppressive therapies resulted in a significant decline in the BK viral load without further deterioration of renal function.

The BK virus in renal transplant recipients-review of pathogenesis, diagnosis, and treatment

The BK virus, a DNA virus from the Polyomavirus group, represents an opportunistic infection of immunosuppressed transplant recipients. Though the virus was discovered approximately 40 years ago, the emergence of BK virus nephropathy since 1995 onwards, with associated high graft loss rates, has revolutionized renal transplantation medicine. Kidney transplant professionals realized that the consequences of over-immunosuppression were as severe as the consequences of under-immunosuppression and we entered the era of immunosuppressive minimization. Despite this recognition, the optimal testing type for BK virus infections and frequency of testing are hotly debated. Similarly, optimal treatment strategies remain sources of intense controversy. The authors review the current strategies of screening, diagnosis, and possible treatment, and also review the amount and quality of evidence in favor or against. Similarities and differences between cytomegalovirus, Epstein-Barr virus, and BV virus, the three major viral infections in kidney transplantation, are highlighted.