Maribavir: a novel antiviral agent with activity against cytomegalovirus.

OBJECTIVE: To review the pharmacology, pharmacokinetics, efficacy, and safety of maribavir, a novel antiviral agent in the benzimidazole drug class. DATA SOURCES: Articles were identified through searches of MEDLINE (January 1998-July 2008). Abstracts from recent scientific meetings and the manufacturer were also included. STUDY SELECTION AND DATA EXTRACTION: All English-language in vitro and in vivo studies and abstracts evaluating maribavir were reviewed and considered for inclusion. All human studies were included. DATA SYNTHESIS: Maribavir has significant activity against both human cytomegalovirus (CMV) and Epstein-Barr virus, but not other herpesviruses. Unlike ganciclovir, which needs to be phosphorylated by UL 97 kinase to become an active inhibitor of DNA polymerase, maribavir directly inhibits UL 97 kinase. UL 97 kinase is an early viral gene product involved in viral DNA elongation, DNA packaging, and egress or shedding of capsids from viral nuclei. Maribavir has also been found to be effective against ganciclovir-resistant CMV strains. Maribavir differs from current CMV antiviral agents in its adverse event profile. Maribavir is not associated with nephrotoxicity or hematologic toxicities, but has been associated with taste disturbances. In February 2007, maribavir was granted Food and Drug Administration orphan drug status for prevention of CMV viremia and diseases in at-risk populations. Maribavir Phase 2 trials in stem-cell transplant recipients have been completed, and there are ongoing Phase 3 trials in stem-cell and organ transplant recipients. CONCLUSIONS: Maribavir may be an option for treatment of ganciclovir-resistant CMV infections. Its bioavailability is greater than that of oral ganciclovir, but less than that of valganciclovir. No differences in pharmacokinetics were seen in renally impaired patients, although dialysis-dependent patients were not evaluated. Maribavir is not associated with hematologic toxicities; however, the high prevalence of taste disturbances may limit its tolerability.

Pharmacokinetics of mycophenolic acid, tacrolimus and sirolimus after gastric bypass surgery in end-stage renal disease and transplant patients: a pilot study.

BACKGROUND: Promising data regarding the safety and efficacy of gastric bypass surgery (GBS) as an option to address obesity in the transplant population are emerging. The data lack on how GBS may alter the pharmacokinetics (PK) of modern immunosuppression. The objective of this study was to describe the alterations in the PK of modern immunosuppressants and the GBS population. METHODS: Data are presented on six subjects who participated in this trial--four were on dialysis and two were renal transplant recipients. Dialysis-dependent bypass subjects received a single dose of 6 mg of sirolimus, two 4-mg doses of tacrolimus and two 1000-mg doses of mycophenolate mofetil (MMF) over the 24-h study period. Transplant recipients continued their current regimen. Maximum plasma concentration (C(max)), time to reach the maximum plasma concentration (T(max)) and the area under the plasma concentration vs. time curve (AUC(0-12) and AUC(0-infinity) where appropriate) were calculated for tacrolimus, sirolimus, mycophenolic acid (MPA) and mycophenolic acid glucuronide (MPAG). RESULTS: Significant inter-patient variability in the C(max), T(max) and AUC of tacrolimus, sirolimus MPA and MPAG was observed. A notable difference in the AUC:dose ratio for tacrolimus was seen when comparing data with published data in the non-bypass population. Similar differences in PK were seen with sirolimus, MPA and MPAG. CONCLUSIONS: When comparing the PK of sirolimus, tacrolimus, MPA and MPAG to published PK data in the non-bypass population, significant differences are observed. It is likely that transplant recipients with GBS would need higher doses of tacrolimus, sirolimus and MMF to provide similar exposure to a non-bypass patient.

BKV and JCV large T antigen-specific CD8+ T cell response in HLA A*0201+ kidney transplant recipients with polyomavirus nephropathy and patients with progressive multifocal leukoencephalopathy.

BACKGROUND: BK virus (BKV), which causes polyomavirus-associated nephropathy (PVN) in kidney transplant recipients (KTx), has 75% homology with JC virus (JCV), the etiologic agent of progressive multifocal leukoencephalopathy (PML). The large T-antigen (T-ag) is the main regulatory protein of polyomaviruses that is expressed early in the viral cycle. OBJECTIVES: To characterize epitopes of BKV and JCV T-ag recognized by CD8+ T-cells and explore the role of these cells in containing polyomavirus infection. STUDY DESIGN: We tested peripheral blood mononuclear cells of HLA A*0201+ BKV- and JCV-seropositive individuals, including patients with active BKV or JCV infection and healthy control subjects in a cross-sectional study. RESULTS: CD8+ T-cells that recognized the nonamer BKV Tp579, which is identical to JCV Tp578, were detected by tetramer staining in 10/13 (77%) healthy individuals, 3/10 (30%) KTx/PVN, and 4/9 (44%) patients with PML and/or HIV-infection. Conversely, BKV Tp398- and Tp410-specific CD8+ T cells were detected in 3/13 (23%) and 1/13 (8%) healthy individuals only. CONCLUSION: These data suggest that, as it is the case for the VP1 protein, the same population of CD8+ T-cells may recognize epitopes located on the BKV and JCV T protein. The overall cellular immune response against polyomavirus T-ag, however, is lower than against the VP1 protein and is more frequently detected in healthy individuals than in patients with active BKV or JCV infection.

Posttransplant lymphoproliferative disorder.

OBJECTIVE: To define and discuss the pathogenesis, clinical presentation, diagnosis, risk factors, and current preventive and treatment strategies of posttransplant lymphoproliferative disorder (PTLD). DATA SOURCES: MEDLINE was searched for articles published from January 1966 to July 2007. Search terms used include posttransplant lymphoproliferative disease, posttransplant malignancy, antiviral agents, interferon-alfa, rituximab, immunosuppression, chemotherapy, radiation, and surgery. Additional articles were identified by a hand search of references. STUDY SELECTION AND DATA EXTRACTION: Studies in English of pediatric and adult solid organ transplantation populations published were selected and analyzed. Data from these studies and information from review articles were included in this review. DATA SYNTHESIS: PTLD occurs in 1-20% of organ recipients following solid organ transplantation. PTLD risk factors include recipient pretransplant Epstein-Barr virus (EBV) negative serostatus, type of transplant, intensity of immunosuppression, and age. The PTLD presentation is variable. Some patients present asymptomatically; in others, early symptoms can be nonspecific. To prevent PTLD, minimizing immunosuppression burden and using antiviral agents active against EBV are useful strategies. PTLD treatment may require reduction of immunosuppression, radiation, surgical excision, monoclonal antibodies, interferon-alfa, and chemotherapy. CONCLUSIONS: Screening for patients at risk and balancing the intensity of immunosuppressive regimens against the risk of rejection can substantially reduce the risk of developing PTLD. If PTLD occurs, an individualized treatment plan including decreased immunosuppression and other agents should be chosen based on the severity and extent of disease.

Simultaneous corticosteroid avoidance and calcineurin inhibitor minimization in renal transplantation.

Steroids and calcineurin inhibitors (CNI) have been mainstays of immunosuppression but both have numerous side effects that are associated with substantial morbidity and mortality. This study was carried out to determine if steroids can be eliminated with early discontinuation of cyclosporine A (CsA) and later discontinuation of mycophenolate mofetil (MMF). Ninety-six patients with kidney transplants were entered into four subgroups of two pilot studies. All patients received Thymoglobulin induction, rapamycin (RAPA), and the immunonutrients arginine and an oil containing omega-3 fatty acids. Mycophenolate mofetil was started in standard doses and discontinued by 2 years. CsA was given in reduced doses for either 4, 6, or 12 months. Follow-up was 12-36 months. Thirteen first rejection episodes occurred during the first year (14%). Combining all patients, 86% were rejection-free at 1 year, 80% at 2 years and 79% at 3 years. No kidney has been lost to acute rejection. Ninety percent of the 84 patients at risk at the end of the study were steroid-free and 87% were off CNI. Fifty-seven percent of 54 patients with a functioning kidney at 3 years were receiving monotherapy with RAPA. We conclude that this therapeutic strategy is worthy of a prospective multi-center clinical trial.

Pharmacotherapeutic options for the management of human polyomaviruses.

Polyomaviruses [BK virus (BKV), JC virus (JCV) and simian virus 40 (SV40)] have been known to be associated with diseases in humans for over thirty years. BKV-associated nephropathy and JCV-induced progressive multifocal leukoencephalopathy (PML) were for many years rare diseases occurring only in patients with underlying severe impaired immunity. Over the past decade, the use of more potent immunosuppression (IS) in transplantation, and the Acquired Immune Deficiency Syndrome (AIDS) epidemic, have coincided with a significant increase in the prevalence of these viral complications. Prophylactic and therapeutic interventions for human polyomavirus diseases are limited by our current understanding of polyomaviral pathogenesis. Clinical trials are limited by small numbers of patients affected with clinically significant diseases, lack of defined risk factors and disease definitions, no proven effective treatment and the overall significant morbidity and mortality associated with these diseases. This chapter will focus on a review of the current and future research related to therapeutic targets and interventions for polyomavirus-associated diseases.

Interplay of cellular and humoral immune responses against BK virus in kidney transplant recipients with polyomavirus nephropathy.

Reactivation of the polyomavirus BK (BKV) causes polyomavirus nephropathy (PVN) in kidney transplant (KTx) recipients and may lead to loss of the renal allograft. We have identified two HLA-A*0201-restricted nine-amino-acid cytotoxic T lymphocyte (CTL) epitopes of the BKV major capsid protein VP1, VP1(p44), and VP1(p108). Using tetramer staining assays, we showed that these epitopes were recognized by CTLs in 8 of 10 (VP1(p44)) and 5 of 10 (VP1(p108)) HLA-A*0201+ healthy individuals, while both epitopes elicited a CTL response in 10 of 10 KTx recipients with biopsy-proven PVN, although at variable levels. After in vitro stimulation with the respective peptides, CTLs directed against VP1(p44) were more abundant than against VP1(p108) in most healthy individuals, while the converse was true in KTx recipients with PVN, suggesting a shift in epitope immunodominance in the setting of active BKV infection. A strong CTL response in KTx recipients with PVN appeared to be associated with decreased BK viral load in blood and urine and low anti-BKV antibody titers, while a low or undetectable CTL response correlated with viral persistence and high anti-BKV antibody titers. These results suggest that this cellular immune response is present in most BKV-seropositive healthy individuals and plays an important role in the containment of BKV in KTx recipients with PVN. Interestingly, the BKV CTL epitopes bear striking homology with the recently described CTL epitopes of the other human polyomavirus JC (JCV), JCV VP1(p36) and VP1(p100). A high degree of epitope cross-recognition was present between BKV and corresponding JCV-specific CTLs, which indicates that the same population of cells is functionally effective against these two closely related viruses.

Experience with antibody-mediated rejection in kidney allograft recipients.

In our case series, AMR occurred in patients who had DSA. Twelve of the 21 patients (57%) who developed de novo antibodies post-transplant had biopsy-proven episodes of either rejection (of any Banff classification) and/or chronic allograft nephropathy. Only one-third of these 12 patients with rejection episodes were classified as AMR. It is unclear when and how often measurements for DSA should be performed after transplantation. When AMR is suspected, the detection of anti-HLA antibodies should be done using very sensitive assays. An increase in PRA and/or the detection of anti-HLA antibodies specific to previous sensitization events may precede an episode of AMR, even in the absence of DSA. Prospective clinical trials are needed to assess the predictive value of the presence of DSA after transplant. It is uncertain which therapeutic response should follow after the detection of these antibody responses in the absence of clinical symptoms. AMR requires intensive therapy, but no standard treatment has been established. Three patients who had AMR at our center were treated with rituximab in addition to various combinations of plasmapheresis, methylprednisolone, OKT3, and intravenous immune globulin. Only one patient responded to this treatment. Well-controlled clinical trials would help to evaluate the efficacy and benefit of B-cell depletion in combination with other immunosuppressive agents.

Multivariate analysis of risk factors for acute rejection in early corticosteroid cessation regimens under modern immunosuppression.

The purpose of this study was to define risk factors for acute rejection with early corticosteroid withdrawal (CSWD; within 7 days posttransplant) in renal transplantation. Data from prospective, IRB-approved early CSWD trials were analyzed. Overall acute rejection rate in 308 patients was 17.1%. Acute rejection rates and observed risks (OR) in patients with individual risk factors were: repeat transplants 38.6%; current PRA >25%; 29.4%; African Americans 23.5%; delayed graft function (DGF) 26.1%; HLA DR mismatches >0 17.9%; female gender 19.7%; Thymoglobulin induction 15.3%; type 1 diabetes 30.8%; type 2 diabetes 11.1%; deceased donor recipients 21%; and living donor recipients 14%. Logistic regression analysis provided the following risks (OR) for acute rejection: repeat transplant 2.51; current PRA > 25% 1.53; African Americans 1.47; DGF 1.58; HLA DR mismatches > 0 1.61; female gender 1.43; Thymoglobulin induction 0.61; type 1 diabetes 2.23, type 2 diabetes 0.5, deceased donor recipients 1.11, and living donor recipients 0.9. Risk factors for acute rejection under early corticosteroid withdrawal are similar to those previously defined under chronic corticosteroid therapy. These observations provide implications for future CSWD trials including: use of T cell depleting antibody induction therapy (thymoglobulin) to reduce acute rejection risk, 2) enrollment stratification for high risk groups, and 3) modified immunosuppression for high risk groups.

Polyomavirus-associated nephropathy in renal transplantation: interdisciplinary analyses and recommendations.

Polyomavirus-associated nephropathy (PVAN) is an emerging cause of kidney transplant failure affecting 1-10% of patients. As uncertainty exists regarding risk factors, diagnosis, and intervention, an independent panel of experts reviewed the currently available evidence and prepared this report. Most cases of PVAN are elicited by BK virus (BKV) in the context of intense immunosuppression. No specific immunosuppressive drug is exclusively associated with PVAN, but most cases reported to date arise while the patient is on triple immunosuppressive combinations, often comprising tacrolimus and/or mycophenolate mofetil plus corticosteroids. Immunologic control of polyomavirus replication can be achieved by reducing, switching, and/or discontinuing components of the immunosuppressive regimen, but the individual's risk of rejection should be considered. The success rate of this intervention is increased with earlier diagnosis. Therefore, it is recommended that all renal transplant recipients should be screened for BKV replication in the urine: 1) every three months during the first two years posttransplant; 2) when allograft dysfunction is noted; and 3) when allograft biopsy is performed. A positive screening result should be confirmed in <4 weeks and assessed by quantitative assays (e.g. BKV DNA or RNA load in plasma or urine). Definitive diagnosis of PVAN requires allograft biopsy. If PVAN and concurrent acute rejection is diagnosed, antirejection treatment should be considered, coupled with subsequently reducing immunosuppression. The antiviral cidofovir is not approved for PVAN, but investigational use at low doses (0.25-0.33 mg/kg intravenously biweekly) without probenicid should be considered for refractory cases. Retransplantation after renal allograft loss to PVAN remains a treatment option for patients clearing polyomavirus replication.

Analysis of factors that influence survival with post-transplant lymphoproliferative disorder in renal transplant recipients: the Israel Penn International Transplant Tumor Registry experience.

Significant mortality is associated with post-transplant lymphoproliferative disorder (PTLD) in kidney transplant recipients (KTX). Univariate/multivariate risk factor survival analysis of US PTLD KTX reported to Israel Penn International Transplant Tumor Registry from November 1968 to January 2000 was performed. PTLD presented 18 (median) (range 1-310) months in 402 KTX. Death rates were greater for those diagnosed within 6 months (64%) versus beyond 6 months (54%, p = 0.04). No differences in death risk for gender, race, immunosuppression, EBV, B or T cell positivity were identified. Death risk increased for multiple versus single sites (73% vs. 53%, hazards ratio (HR) 1.4). A 1-year increase in age increased HR for death by 2%. Surgery was associated with increased survival (55% vs. 0% without surgery) (p < 0.0001). Patients with allograft involvement, treated with transplant nephrectomy alone (n = 20), had 80% survival versus 53% without allograft removal (n = 15) (p < 0.001). Overall survival was 69% for allograft involvement alone versus 36% for other organ involvement plus allograft (n = 19 alive) (p < 0.0001). Death risk was greater for multiple site PTLD and increasing age, and risks were additive. Univariate analysis identified increased death risk for those not receiving surgery, particularly allograft involvement alone.

African-American renal transplant recipients benefit from early corticosteroid withdrawal under modern immunosuppression.

African-Americans (AAs) have historically been considered high-risk renal transplant recipients due to increased rejection rates and reduced long-term graft survival. As a result, AAs are often excluded from corticosteroid withdrawal (CSWD) protocols. Modern immunosuppression has reduced rejections and improved graft survival in AAs and may allow successful CSWD. Outcomes in 56 AAs were compared to 56 non-AAs. All patients were enrolled in one of four early CSWD protocols. Results are reported as AA versus non-AA. Acute rejection at 1-year was 23% and 18%; (p = NS); creatinine clearance at 1-year was 75 versus 80 mL/min (p = NS); patient and graft survival was 96% versus 98% and 91% versus 91%; (p = NS). AAs benefit from early CSWD with significantly improved blood pressure, LDL < 130 mg/dL and HDL > 45 mg/dL at 1-year, post-transplant diabetes of 8.7%, and mean weight change at 1-year of 4.8 +/- 7.2 kg. In conclusion, early CSWD in AAs is associated with acceptable rejection rates, excellent patient and graft survival, and improved cardiovascular risk, indicating that the risks and benefits of early CSWD are similar between AAs and non-AAs. Additional follow-up is needed to determine long-term renal function, graft survival, and cardiovascular risk in AAs with early CSWD.

Experience with 274 cardiac transplant recipients with posttransplant lymphoproliferative disorder: a report from the Israel Penn International Transplant Tumor Registry.

BACKGROUND: Posttransplant lymphoproliferative disorder (PTLD) is a life-threatening complication that occurs in a small but significant minority of solid organ transplant recipients. Published experiences with PTLD in cardiac transplant recipients are limited to relatively small single-center reports. METHODS: This report presents experience with 274 cases of PTLD in cardiac transplant recipients reported to the Israel Penn International Transplant Tumor Registry (IPITTR). RESULTS: PTLD carried an ominous prognosis: Kaplan Meier survival after PTLD diagnosis was 45%, 33%, 30%, and 13%, respectively, at 1, 3, 5, and 10 years. Common causes of death included: PTLD, cardiovascular collapse, and infection; all occurred at a median of less than 6 months. Risk of death from cardiovascular collapse secondary to immunosuppression withdrawal was substantial (28%), indicating that a fine balance exists between death from PTLD and from sudden cardiac death due to acute rejection. PTLD therapy in the majority of patients consisted of combination therapy (49%). Survival in patients receiving immunosuppression minimization (ISM) alone was 32%, with ISM plus other therapy was 27%, and with other therapies not containing ISM was 11% (P < 0.01). CONCLUSION: PTLD in cardiac transplant recipients is associated with low long-term survival rates. Analysis of PTLD therapies and outcomes suggest that immunosuppression minimization, when applied, improves survival. However, risk of sudden death may mitigate the positive effect of ISM. This observation has important implications for ISM in PTLD therapy in cardiac transplant recipients. Carefully designed prospective studies are needed to evaluate the positive and negative effects of ISM in cardiac transplant recipients with PTLD.

Characteristics and survival patterns of solid organ transplant patients developing de novo colon and rectal cancer.

PURPOSE: Immunosuppression used in transplantation is associated with an increased incidence of various cancers. Although the incidence of colorectal cancer in transplant patients seems to be equal to nontransplant population, the effects of immunosuppression on patients who develop colorectal cancer are not well defined. The purpose of this study was to define the characteristics and survival patterns of transplant patients developing de novo colorectal cancer. METHODS: The Israel Penn International Transplant Tumor Registry was queried for patients with colorectal cancer. Analysis included patient demographics, age at transplantation and colorectal cancer diagnosis, tumor stage, and survival. Age and survival rates were compared to United States population-based colorectal cancer statistics using the National Cancer Institute Surveillance Epidemiology and End Results database. RESULTS: A total of 150 transplant patients with de novo colorectal cancer were identified: 93 kidney, 29 heart, 27 liver, and 1 lung. Mean age at transplantation was 53 years. Age at transplantation and colorectal cancer diagnosis was not significant for gender, race, or stage of disease. Compared to National Cancer Institute Surveillance Epidemiology and End Results database, transplantation patients had a younger mean age at colorectal cancer diagnosis (58 vs. 70 years; P < 0.001), and a worse five-year survival (overall, 44 vs. 62 percent, P < 0.001; Dukes A and B, 74 vs. 90 percent, P < 0.001; Dukes C, 20 vs. 66 percent, P < 0.001; and Dukes D, 0 vs. 9 percent, P = 0.08). CONCLUSIONS: Transplant patients develop colorectal cancer at a younger age and exhibit worse five-year survival rates than the general population. These data suggest that chronic immunosuppression results in a more aggressive tumor biology. Frequent posttransplantation colorectal cancer screening program may be warranted.

Posttransplant malignancy.

In the past few decades, great advances have been made in the field of solid-organ transplantation. A greater understanding of immune system function, the development of modern immunosuppression, and advancements in surgical technique have led to marked improvements in both recipient and graft survivals, as well as recipients' quality of life. However, improved survival rates have also led to prolonged exposure to chronic immunosuppression, which increases the risk for the development of posttransplant malignancies. In addition, older transplant candidates are being considered, carrying with them the increased likelihood of preexisting malignancy. Consequently, the potential risk of posttransplant malignancy must be considered. Moreover, as long-term transplant survivors continue to age, posttransplant malignancies will be seen more frequently. This review presents the more commonly encountered posttransplant malignancies and the measures that are currently being utilized to prevent and treat them.

Donor transmitted malignancies.

Early experiences in transplantation, which pre-dated brain death laws, utilized organs from donors with active malignancies. The use of organs from such donors occasionally resulted in the transmission of malignancy from the donor to an unknowing recipient. Over a period of three decades, Israel Penn, M. D. catalogued some two hundred and fifty cases of organs transplanted from donors with a history of malignancy; carefully examining each reported case for tumor histology, donor risk factors, method of tumor presentation and recipient outcome. Some recipients never developed malignancies, while others were less fortunate, developing cancers that were suspicious for donor origin. The evolution of transplantation has resulted in improved patient survival, which in turn has led to an increased demand for organ transplantation. Unfortunately, the supply of organs available for transplantation has failed to keep pace with the demand, with the worldwide deficit growing annually. In an effort to bridge the widening gap, utilization of older and more marginal donors has been suggested. However, use of older donors is accompanied by the likelihood that a significant proportion may have undiagnosed malignancies. Multiple transplant programs have considered the use of donors with tumors of non-malignant or even low-grade malignant histology, most often involving the central nervous system (CNS). According to a survey from the United Network for Organ Sharing (UNOS), central nervous system malignancies are among the most commonly identified malignancies found in potential donors. This study examines the distribution of potential donor transmitted malignancies reported to the Israel Penn International Transplant Tumor Registry. The incidence of tumor transmission is examined in the overall group as well as among individual histologies. We also seek to identify specific factors associated with the risk of malignancy transmission from donor to recipient, in an effort to minimize future transmission of donor tumors to unwitting recipients. The study is based on voluntary registry data, which some argue can be criticized for a lack of true incidence data. In reality, however, this data may provide a more accurate insight since it is based on transmissions from high-risk donors rather than from the general population.

Recurrence risk after organ transplantation in patients with a history of Hodgkin disease or non-Hodgkin lymphoma.

This study defines the incidence and recurrence risk of Hodgkin disease (HD) and non-Hodgkin lymphoma (NHL) after organ transplant. Patients from the United States with a history of HD or NHL before organ transplantation reported to the Israel Penn International Transplant Tumor Registry from 1968 to 2001 were analyzed. A total of 91 patients underwent organ transplantation with a lymphoma history: HD (38 patients) and NHL (53 patients). Median disease-free interval pretransplant was 99 (range 0-459.1) months, and median follow-up posttransplant was 25.7 (0.4-131.1) months. Ten patients were excluded from further analysis because of lack of follow-up information (n=9) or they never achieved remission (n=1). Recurrence incidence was 8 of 81 patients (10%) (HD=3/34 [9%] vs. NHL=5/47 [11%]). Gender, race, allograft type and source, age at lymphoma diagnosis, and immunosuppression did not influence recurrence. Patients with less than a 2-year period between diagnosis and transplant seem to be at increased risk of relapse. Median disease-free interval before transplant was longer for patients without recurrence (115 vs. 30.2 months, P=0.24), but was not statistically significant. Median time to recurrence posttransplant was 18.7 (range 1.9-82.2) months (HD=3.7 vs. NHL 23.6 months, P=0.10). Survival after recurrence was poor (HD [1/3] and NHL [1/5], median survival 6.8 [range 0-22.1] months). There is no difference in recurrence rates for HD and NHL. The outcome for recurrent lymphoma is poor. The low risk of recurrence (10%) indicates that preexisting HD and NHL need not be an absolute contraindication to transplantation.

Polyomavirus nephropathy in kidney transplantation.

Polyomavirus nephropathy has become an important complication in kidney transplantation, with a prevalence of 1% to 8%. Unfortunately, the risk factors for polyomavirus nephropathy and renal allograft loss are not well defined. The definitive diagnosis is made through assessment of a kidney transplant biopsy. Recently, noninvasive urine and serum markers have been used to assist in polyomavirus nephropathy diagnosis and monitoring. Primary treatment is immunosuppression reduction, but must be balanced with the risks of rejection. No antiviral treatments for polyomavirus nephropathy have been approved by the Food and Drug Administration. Although cidofovir has shown in vitro activity against murine polyomaviruses, and has been effective in some patients, it is associated with significant nephrotoxicity. Graft loss due to polyomavirus nephropathy should not be a contraindication to retransplantation; however, experience is limited. This review presents potential risk factors, screening, diagnostic and monitoring methods, therapeutic management, and retransplantation experience for polyomavirus nephropathy.