Development of BK nephropathy in recipients of simultaneous pancreas-kidney transplantation. Transplantation. 2009;87:525-530. [PMID: 19307788 DOI: 10.1097/tp.0b013e3181949629]

Polyomavirus and cytomegalovirus infections are risk factors for grafts loss in simultaneous pancreas and kidney transplant

BACKGROUND

Published literature on predictors of polyomavirus (BKV) and cytomegalovirus (CMV) infections in simultaneous pancreas and kidney (SPK) transplant and their impact on allograft outcomes remain sparse. We hypothesize that BKV and CMV viremia infections decrease allograft survival in SPK. Identifying modifiable predictors of BKV and CMV may help tailor immunosuppression and improve allograft survival.

METHODS

All SPK recipients at our institution between January 2000 and April 2016 were included (n = 757). Thirty-nine recipients had BKV only and 25 had CMV only, and infection occurred at median follow-up times of 217 and 163 days, respectively. Event density sampling was used to match recipients with BKV or CMV to up to 10 recipients without infection by age, sex, and HLA mismatch status, and these were followed for a median of 4.3 years after infection.

RESULTS

Older age (HR 1.49 for each decade; 95% CI: 0.95, 2.35; P = .083) and tacrolimus use (HR 20.6; 95% CI: 2.37, 179.53; P = .006) were associated with increased incidence of BKV, but not CMV, infection. Both BKV and CMV infections were associated with increased risk of allograft failure for both pancreas (BKV [HR 2.17; 95% CI 1.47, 3.208; P = .000], CMV [HR 1.7; 95% CI 1.077, 2.687; P = .023]) and kidney (BKV [HR 2.65; 95% CI 1.765, 3.984; P = .000], CMV [HR 2.07; 95% CI 1.295, 3.308; P = .002]).

CONCLUSION

Older age at time of transplant and tacrolimus may help predict BKV infection in SPK recipients.

Clinical characteristics and outcomes of late-onset BK virus nephropathy in kidney and kidney-pancreas transplant recipients

BACKGROUND

BK virus nephropathy (BKPyVAN) is a major complication in kidney transplant recipients (KTR) and typically occurs within 1 year of transplant. Guidelines vary in recommendations for BKPyV screening beyond 1 year. A systematic characterization of risk factors and outcomes of late-onset (>1 year) BKPyVAN has not previously been reported.

METHODS

We retrospectively compared characteristics and outcomes of early- (<1 year) and late-onset BKPyVAN (definitive [biopsy-confirmed] or presumptive [plasma BKPyV >10 000 copies/mL]) in a cohort of 671 KTR and simultaneous kidney-pancreas transplant (SPK) recipients between 2008 and 2013 at a single US transplant center. Proportions were compared using Chi-square or Fisher's exact test with P < .05 considered significant.

RESULTS

BKPyVAN was diagnosed in 96 (14.3%) patients (proven 16.7%, presumptive 83.3%): 79 (82.3%) early- and 17 (17.7%) late-onset. The proportion with late-onset BKPyVAN was significantly higher among SPK than KTR (4 of 7 [57.1%] vs 13 of 89 [14.6%], P = .017). Late-onset represented "de novo" infection (no BKPyV detection within the first year) in 14 (82.4%) and progression of earlier lower grade BKPyV reactivation in 3 (17.6%). Clinical outcomes were similar for early- and late-onset BKPyVAN (P > .05 all comparisons). In a pooled analysis of prior studies of BKPyVAN in SPK recipients, 62.9% (17 of 27) were late-onset.

CONCLUSION

A significant proportion of BKPyVAN is late-onset, especially among SPK recipients, and supports a longer duration of BKPyV monitoring for SPK recipients than recommended in some guidelines.

BK viremia surveillance and outcomes in simultaneous pancreas-kidney transplant recipients

BACKGROUND

While screening for asymptomatic BK viremia (BKV) has been well studied in isolated kidney transplant recipients, there is a paucity of published outcomes in simultaneous pancreas-kidney (SPK) transplant recipients who underwent BKV screening followed by pre-emptive reduction in immunosuppression.

METHODS

This is a single-center, retrospective review of 31 consecutive SPK recipients who were transplanted over a 5-year period following the initiation of a serum BKV screening protocol.

RESULTS

BK viremia developed in 11 (35.5%) patients, and all patients achieved complete viral clearance following reduction in immunosuppression. Two patients (6.5%) developed BK virus nephropathy, but both had preserved allograft function. One patient developed mild rejection of the kidney allograft following clearance of BKV, and two patients developed mild rejection of the pancreas allograft after reduction in immunosuppression, but there were no kidney or pancreas allograft losses due to rejection. The development of BK viremia did not impact overall patient survival or kidney and pancreas allograft survival.

CONCLUSION

Screening asymptomatic SPK recipients for BKV followed by reduction in maintenance immunosuppression appears to be an effective strategy to prevent kidney allograft dysfunction and graft loss due to BK virus nephropathy, without compromising pancreas allograft outcomes.

BK nephropathy in the native kidneys of patients with organ transplants: Clinical spectrum of BK infection

Nephropathy secondary to BK virus, a member of the Papoviridae family of viruses, has been recognized for some time as an important cause of allograft dysfunction in renal transplant recipients. In recent times, BK nephropathy (BKN) of the native kidneys has being increasingly recognized as a cause of chronic kidney disease in patients with solid organ transplants, bone marrow transplants and in patients with other clinical entities associated with immunosuppression. In such patients renal dysfunction is often attributed to other factors including nephrotoxicity of medications used to prevent rejection of the transplanted organs. Renal biopsy is required for the diagnosis of BKN. Quantitation of the BK viral load in blood and urine are surrogate diagnostic methods. The treatment of BKN is based on reduction of the immunosuppressive medications. Several compounds have shown antiviral activity, but have not consistently shown to have beneficial effects in BKN. In addition to BKN, BK viral infection can cause severe urinary bladder cystitis, ureteritis and urinary tract obstruction as well as manifestations in other organ systems including the central nervous system, the respiratory system, the gastrointestinal system and the hematopoietic system. BK viral infection has also been implicated in tumorigenesis. The spectrum of clinical manifestations from BK infection and infection from other members of the Papoviridae family is widening. Prevention and treatment of BK infection and infections from other Papovaviruses are subjects of intense research.

BK Virus in Kidney Transplant: Current Concepts, Recent Advances, and Future Directions

BK virus nephropathy is a challenging clinical problem in kidney transplant recipients with wide range of surveillance and management practices, based on individual experience. BK virus reactivation in kidney transplant recipients can result in BK virus nephropathy and graft loss. The most effective strategy for early diagnosis and treatment of BK virus nephropathy is regular monitoring for BK virus, currently achieved by quantification of viral DNA in blood by quantitative polymerase chain reaction. Immunosuppression reduction remains the mainstay of treatment; however, viral clearance is often followed by acute rejection, likely secondary to a delay between immune reconstitution and viral clearance. Impaired cell-mediated immune response to BK virus has been shown to correlate with progression to BK virus nephropathy, while reconstitution of this response correlates with resolution of nephropathy. There is recent research to support monitoring BK virus-specific cell-mediated immune response as a predictor of disease progression and resolution. In this article, we review the current concepts and recent developments in understanding BK virus-associated disease in the context of kidney transplant and outline areas for future research.

BK virus infection: an update on diagnosis and treatment

BK virus, first isolated in 1971, is a significant risk factor for renal transplant dysfunction and allograft loss. Unfortunately, treatment options for BK virus infection are limited, and there is no effective prophylaxis. Although overimmunosuppression remains the primary risk factor for BK infection after transplantation, male gender, older recipient age, prior rejection episodes, degree of human leukocyte antigen mismatching, prolonged cold ischemia time, BK serostatus and ureteral stent placement have all been implicated as risk factors. Routine screening for BK has been shown to be effective in preventing allograft loss in patients with BK viruria or viremia. Reduction of immunosuppression remains the mainstay of BK nephropathy treatment and is the best studied intervention. Laboratory-based methods such as ELISPOT assays have provided new insights into the immune response to BK and may help guide therapy in the future. In this review, we will discuss the epidemiology of BK virus infection, screening strategies, treatment options and future research directions.

BK virus replication and nephropathy after alemtuzumab-induced kidney transplantation

BK virus nephropathy (BKVN) is a recognized cause of graft failure in kidney transplant recipients. There are limited data on the epidemiology of BK virus (BKV) infection after alemtuzumab induction. By clinical protocol, the kidney transplant recipients at our center were screened with BKV plasma PCR monthly for the first 4 months posttransplant then every 2-3 months for 2 years. A single center retrospective cohort study of all kidney transplant recipients from January 2008 to August 2010 was conducted to determine incidence and outcomes of BKV infection. Descriptive statistics and Kaplan-Meier analysis was performed. Of 666 recipients, 250 (37.5%) developed viruria, 80 (12%) developed viremia and 31 (4.7%) developed BKVN at a median of 17, 21 and 30 weeks, respectively. Induction with alemtuzumab did not significantly affect incidence of BKVN. Increased recipient age, African American race, acute graft rejection and CMV infection were significantly associated with the development of BKVN in multivariate analysis. The incidence of BK viruria, viremia and nephropathy was not significantly different among kidney transplant recipients who received alemtuzumab induction compared to patients receiving less potent induction.

BK virus nephropathy in simultaneous pancreas kidney transplant: a potentially preventable cause of kidney allograft loss

More than half of the simultaneous pancreas kidney transplant (SPK) patients afflicted with BK virus nephropathy (BKVN) lose their kidney allograft. Fear of pancreatic rejection limits the ability to reduce immunosuppression; this may result in inadequate treatment of BKVN. This single-center retrospective review included 138 SPK patients who underwent periodic BKV screening and were managed with IS reduction alone as a treatment of choice for BKVN. All patients underwent rabbit anti-thymocyte globulin (rATG) induction and were maintained on tacrolimus/sirolimus or mycophenolate. The incidence of BKVN was 4.4%. BKVN was diagnosed at a median of 11 months; mean serum creatinine 2.1 mg/dL and the geometric mean BK serum viral load at diagnosis 1,758,000 DNA copies/mL. Median time to BKV clearance was 5.6 months; there was 96% reduction in the mycophenolate dose, 100% reduction in sirolimus, and 40% reduction in the tacrolimus blood level at BKVN clearance. No BKVN-related kidney failure was noted, and patients retained excellent kidney and pancreatic allograft function till last follow-up (43 months). BKVN in SPK is a potentially preventable cause of end-stage kidney disease, and IS reduction alone is an acceptable treatment modality in SPK without a higher risk of kidney/pancreas allograft loss as long as close monitoring can be ensured.

BK virus nephropathy after simultaneous pancreas-kidney transplantation

BACKGROUND

BK virus nephropathy (BKVN) was reported in up to 7.5% of patients after simultaneous pancreas-kidney transplantation (SPK). Its management by reduction in immunosuppression might pre-dispose to pancreatic graft loss.

METHODS

A retrospective analysis of 178 SPK recipients was performed. All patients received thymoglobulin, daclizumab and a maintenance of low-dose steroids, tacrolimus, and either sirolimus or mycophenolate.

RESULTS

Two (1.1%) patients were identified with BKVN. Time of diagnosis was 22 and 45 months after transplant. Both patients had superimposed calcineurin toxicity in their graft biopsies. Immunosuppression was reduced in both patients, and leflunomide (LEF) was used in one patient. Concurrent kidney rejection episodes were treated with steroid pulses in both patients. One kidney graft improved with a last estimated glomerular filtration rate (GFR) of 43 mL/min, and another kidney graft showed limited improvement with a last GFR of 30 mL/min. Pancreatic graft function remained excellent in both patients as assessed by serum c-peptide, glycosylated hemoglobin, amylase-lipase, and urine amylase levels.

CONCLUSION

Low incidence of BKVN was observed in our SPK series. Reduction in immunosuppression and sometimes LEF can be effective. The underlying mechanism of stable pancreatic allograft function despite ongoing kidney rejection warrants further investigation.

Simultaneous pancreas and kidney transplantation with concurrent allograft nephrectomy for recipients with prior renal transplants lost to BK virus nephropathy: two case reports

Candidacy for retransplantation after allograft loss due to BK virus-associated nephropathy (BKVN) with or without allograft nephrectomy is controversial. This report describes 2 renal transplant recipients who lost their grafts to BKVN and subsequently underwent simultaneous kidney and pancreas transplantation with allograft nephrectomy.

Decoy cells and malignant cells coexisting in the urine from a transplant recipient with BK virus nephropathy and bladder adenocarcinoma

The search for decoy cells (DC) in urine is widely used as screening for BK virus (BKV) reactivation in transplant recipients. BKV cytopathic effect of DC must not be confused with high-grade urothelial carcinoma. This report presents a case of coexistence of DC and malignant cells in the urine from a transplant recipient with BKV-associated nephropathy (BKVN) and bladder adenocarcinoma. A 38-year-old female with type 1 diabetes mellitus and end-stage renal disease underwent a simultaneous pancreas and kidney transplant. Four years post-transplantation, BK virus studies were performed for renal dysfunction. Isolated DC and DC in casts were identified in urine. Also, the tests for BKV DNA were positive in serum and renal allograft biopsy. BKVN was treatment-resistant and the patient returned to hemodialysis. A kidney transplant nephrectomy was performed 2 years later. The next urine cytology showed, in addition to DC, other distinct cells with nuclear atypia highly suggestive of malignancy. Some cells showed both, malignant and DC features. A bladder adenocarcinoma was diagnosed on biopsy and BKV proteins were demonstrated on tumor cells, supporting a possible role for BKV in the oncogenic pathway in this clinical setting. The presence of DC in the urine from a transplant recipient is the hallmark of BKV activation, but it does not exclude the existence of carcinoma. Furthermore, the presence of highly atypical cells should raise, not eliminate, the possibility of neoplastic transformation of the bladder.

Renal failure five years after lung transplantation due to polyomavirus BK-associated nephropathy

Polyomavirus-associated nephropathy (PyVAN) is rare in nonrenal solid organ transplantation and only limited information is available from single cases. We describe a 67-year-old female presenting with hypertension and progressive kidney failure due to PyVAN 60 months after lung transplantation. Plasma BK virus (BKV) loads were 4.85 log¹⁰ copies/mL at diagnosis and cleared slowly over 14 months after switching from tacrolimus, mycophenolate and prednisone to low-dose tacrolimus, sirolimus and leflunomide, the latter being discontinued for anemia and diarrhea. BKV- and JC virus-specific immunoglobulins were detectable prior to transplantation. Only BKV-specific IgG and IgM increased during follow-up. BKV-specific T cells were detectable in blood following in vitro expansion, but cleared with reincreased sirolimus, yet BKV viremia remained undetectable. We identified eight other cases of PyVAN in nonrenal solid organ transplantation including lung (n = 1), heart (n = 6) and pancreas (n = 1). Overall, diagnosis was later than commonly seen in kidney transplants (median 18 months, interquartile range 10-29). Seven patients were male, five received triple immunosuppression consisting of tacrolimus, mycophenolate, prednisone. Immunosuppression was reduced in four cases and cidofovir and/or leflunomide administered in five and two cases, respectively. Renal function deteriorated in five requiring hemodialysis in four. We discuss mTOR inhibitors versus cidofovir and leflunomide as potential PyVAN rescue therapy.

Immunosuppression in simultaneous pancreas-kidney transplantation: progress to date

Simultaneous pancreas-kidney transplantation (SPKT) is the treatment of choice for patients with end-stage renal failure due to type 1 diabetes mellitus. With advances in surgical techniques and immunosuppression management, outcomes have improved, with current 1- and 10-year pancreas graft survival rates of 86% and 53%, respectively. Induction therapy with either alemtuzumab or rabbit antithymocyte globulin (rATG) in combination with a calcineurin inhibitor (CNI) and mycophenolate mofetil (MMF) or sirolimus appears to be safe and effective in the setting of rapid steroid withdrawal (RSW), with excellent graft survival and low rejection rates. There are no large randomized trials between alemtuzumab and rATG to determine whether one is better than the other. Anti-interleukin (IL)-2 receptor antibody induction and no induction in combination with a CNI, MMF or sirolimus, and prednisone have demonstrated excellent graft survival rates but are associated with a higher incidence of acute rejection. The efficacy of anti-IL-2 receptor antibodies or no induction in the setting of RSW is unproven. Both of the CNIs, ciclosporin and tacrolimus, are effective in preventing acute rejection in SPKT recipients; however, pancreas allograft survival may be better with tacrolimus. MMF is more effective than azathioprine in preventing acute rejection. Sirolimus appears to be effective in preventing acute rejection, but the combination of sirolimus with a CNI may accentuate the nephrotoxicity of the CNI. RSW with induction therapy is safe and effective in SPKT recipients, but longer follow-up data on outcomes are needed. Recent analysis of registry data shows that most transplant centres are using an induction agent followed by a combination of tacrolimus, MMF and corticosteroids in SPKT recipients.