BK polyomavirus and urothelial carcinoma: Experience at a tertiary care centre in India with review of literature

High-sensitivity BK virus detection system using viewRNA in situ hybridization

OBJECTIVE

To establish a reliable molecular diagnostic system for precise identification of BK virus (BKV)-associated pathologies.

METHODS

We designed a set of in-situ hybridization (ISH) probes targeting two conserved sequences within the large T antigen region of BKV, exhibiting highly specificity from JC virus and SV40 homologs. By integrating the branched DNA signal amplification technology with these probes, we developed a novel ViewRNA-ISH detection system.

RESULTS

The optimized BKV-LT ViewRNA-ISH system demonstrated enhanced diagnostic specificity and sensitivity compared to conventional immunohistochemical methods in both cellular models and clinical specimens. Validation using 29 clinical samples and 3 subcutaneous planted tumor samples revealed 93.75 % (30/32) concordance with IHC findings, with 2 previously IHC-negative renal biopsies showing positive signals through ViewRNA-ISH detection.

CONCLUSIONS

Our BKV-LT ViewRNA-ISH system enables dual-mode (fluorescent/ chemical) detection of BKV nucleic acids, providing superior diagnostic performance for BKV-associated pathologies with potential clinical utility in renal allograft monitoring.

Management of bladder cancer in kidney transplant recipients: A narrative review

Background

Bladder cancer in the setting of previous a kidney transplant (KT) is challenging to manage due to complex medical and surgical considerations.

Objective

To provide a comprehensive evaluation of the scope of management of bladder cancer in KT patients, and describe the controversies surrounding these management options.

Methods

A systematic review of studies reporting management of KT patients with bladder cancer and involving ≥3 patients was performed. A narrative review was also performed for various aspects of management such as pathophysiology, surgical considerations, intravesical therapy, immunosuppression and oncological surveillance.

Results

Bladder cancer incidence in KT recipients is 2.8-4.1 times higher than the general population, and there is a notable association with aristolochic acid nephropathy as well as BK virus oncogenesis. Regarding surgical treatment, transurethral resection is preferred for non-muscle invasive tumors, and intravesical BCG for intermediate- and high-risk patients appears to be underutilized despite its safety and associated reduction in recurrence. Radical cystectomy with limited pelvic lymph node dissection, urinary diversion, and consideration of bilateral nephroureterectomy appears to be the safest method of oncological control in muscle-invasive tumors. A switch in immunosuppressive regimens to mTOR inhibitors may be considered in lieu of its antitumor effects. Routine surveillance in KT patients with risk factors for bladder cancer is challenging and may be warranted especially in the Asian population which has a higher rate of urothelial malignancy.

Conclusions

This review provides a thorough summary of management strategies for bladder cancer in the setting of previous KT.

Genitourinary malignancies in kidney transplant recipients

Advances in immunosuppressive therapy and postoperative management have greatly improved the graft and patient survival rates after kidney transplantation; however, the incidence of post-transplant malignant tumors is increasing. Post-renal transplantation malignant tumors are associated with renal failure, immunosuppression, and viral infections. Moreover, the risk of developing cancer is higher in kidney transplant recipients than in the general population, and the tendency to develop cancer is affected by the background and environment of each patient. Recently, cancer after kidney transplantation has become the leading cause of death in Japan. Owing to the aggressive nature and poor prognosis of genitourinary malignancies, it is crucial to understand their epidemiology, risk factors, and best practices in kidney transplant recipients. This review has a special emphasis on the epidemiology, risk factors, and treatment protocols of genitourinary malignancies in kidney transplant recipients to enhance our understanding of the appropriate management strategies. Optimal immunosuppressive therapy and cancer management for these patients remain controversial, but adherence to the general guidelines is recommended.

Post-transplant malignancy: Focusing on virus-associated etiologies, pathogenesis, evidence-based management algorithms, present status of adoptive immunotherapy and future directions

Modern immunosuppression has led to a decrease in rejection rates and improved survival rates after solid organ transplantation. Increasing the potency of immunosuppression promotes post-transplant viral infections and associated cancers by impairing immune response against viruses and cancer immunoediting. This review reflects the magnitude, etiology and immunological characteristics of various virus-related post-transplant malignancies, emphasizing the need for future research. A multidisciplinary and strategic approach may serve best but overall literature evidence targeting it is sparse. However, the authors attempted to provide a more detailed update of the literature consensus for the prevention, diagnosis, management and surveillance of post-transplant viral infections and associated malignancies, with a focus on the current role of adoptive immunotherapy and the way forward. In order to achieve long-term patient and graft survival as well as superior post-transplant outcomes, collaborative research on holistic care of organ recipients is imperative.

Urological Cancers and Kidney Transplantation: a Literature Review

PURPOSE OF REVIEW

The aim of this review is to provide an overview of epidemiology, risk factors, and treatment of urological malignancies in renal transplant recipients (RTR).

RECENT FINDINGS

Although optimal immunosuppressive therapy and cancer management in these patients remain controversial, adherence to general guidelines is recommended. Kidney transplantation is recognized as the standard of care for the treatment of end-stage renal disease (ESRD) as it offers prolonged survival and better quality of life. In the last decades, survival of RTRs has increased as a result of improved immunosuppressive therapy; nonetheless, the risk of developing cancer is higher among RTRs compared to the general population. Urological malignancies are the second most common after hematological cancer and often have more aggressive behavior and poor prognosis.

Tissue Pathogens and Cancers: A Review of Commonly Seen Manifestations in Histo- and Cytopathology

Tissue pathogens are commonly encountered in histopathology and cytology practice, where they can present as either benign mimickers of malignancy or true malignancies. The aim of this review is to provide a timely synthesis of our understanding of these tissue pathogens, with an emphasis on pertinent diagnostic conundrums associated with the benign mimickers of malignancy that can be seen with viral infections and those which manifest as granulomas. The oncogenic pathogens, including viruses, bacteria, and parasites, are then discussed with relationship to their associated malignancies. Although not exhaustive, the epidemiology, clinical manifestations, pathogenesis, and histological findings are included, along with a short review of emerging therapies.

Post-renal transplant malignancies: Opportunities for prevention and early screening

GOAL OF THE REVIEW

While transplant recipients are aware of increased malignancy risk, there is little consensus on the preventative measures. The goal of this review is to bring available preventative measures to light and prompt more research to be done with ultimate goal of developing an individualized prevention plan for each patient based on risk factors and available screening tools.

INTRODUCTION

Transplant surgery offers patients with end-stage renal disease a longer life expectancy with help of immunosuppressive therapies. Nonetheless, life-long immunosuppression comes at a cost of post-renal transplant malignancies, which have become the leading cause of morbidity in this patient group.

DISCUSSION

Post-renal transplant cancers can develop through either de novo, by donor-related transmission, or recurrence of recipient's pre-transplant cancer. While immunosuppressive therapy is considered to be the leading cause, weakened immunosurveillance of neoplastic cells and inadequate immune response against oncogenic viruses also plays an important role. The most common cancers seen in renal transplant patients are skin cancers and post-transplant lymphoproliferative disorder (PTLD). Risk factors for skin cancers have are ultraviolet light, human papilloma virus infection, and use of cyclosporin and azathioprine. Numerous viral infections have been associated with transplant-related malignancies post-transplant.

CONCLUSION

While lowering of immunosuppressive therapy remains the treatment of choice, it may lead to graft failure. Given some of the presented malignancies have modifiable risk factors and options for screening, clinical outcomes can be improved. Limiting skin exposure, dermatologic screening, and prophylactic retinoids can help lower the incidence rate of skin malignancy. Endoscopic screening for renal transplant patients can help identify gastric adenocarcinoma early and improve survival rates. Some of the post-transplant malignancies have been responsive to anti-viral treatment.

Reactivation of BK Polyomavirus in Urine Cytology is Not Associated with Urothelial Cell Carcinoma

BK polyomavirus (BKPyV) has been associated with some high-grade and special urothelial cell carcinoma (UCC) subtypes in immunosuppressed patients. Here, we evaluated the relationship of BKPyV-positive urine cytology specimens (UCS) with UCC. A large single-institution database was retrospectively searched for UCS positive for decoy cells, suggesting BKPyV infection. These were tested for the presence of BKPyV by PCR and immunohistochemistry (IHC) in urine sediments and formalin-fixed paraffin-embedded (FFPE) tissue samples of UCC. Decoy cells were reported in 30 patients out of the database with 22.867 UCS. Of these 30 patients, 16 (53.3%) had no history of UCC. Six patients out of these 16 had a history of transplantation, 4 had a history of severe chronic medical conditions, and 6 had no chronic disease. The other fourteen patients were diagnosed with either in situ or invasive UCC of the urinary bladder (14/30; 46.6%) prior to the detection of decoy cells in the urine. Nine of these UCC patients received intravesical treatment (BCG or mitomycin) after the first presentation with UCC. However, the clinical data on the treatment of the other five UCC patients was lacking. IHC identified BKPyV-positivity in the urine samples of non-UCC and UCC patients, while no BKPyV positivity was found in FFPE tissues of primary UCCs and metastases. In addition, BKPyV-PCR results revealed the presence of BKPyV DNA in the urine of the UCC cases, yet none in the UCC tissues itself. These data strongly indicate that BKPyV reactivation is not restricted to immunosuppression. It can be found in UCS of the immunocompetent patients and may be related to the intravesical BCG or mitomycin treatment of the UCC patients.

BK Virus RNA in Renal Allograft Biopsies

BK polyomavirus-associated nephropathy (BKpyVAN) remains a cause of graft loss in kidney transplant recipients on immunosuppressive therapy. Its diagnosis relies on the identification of BK virus (BKV) in the renal allograft biopsy by positive immunohistochemical (IHC) stain for the viral SV40 large T antigen, although in situ hybridization (ISH) for viral DNA is used in some centers. We examined tissue detection of BKV RNA by RNAscope, a novel, automated ISH test, in 61 allograft biopsies from 56 patients with BKpyVAN. We found good correlation between the estimate of BKV tissue load by RNAscope ISH and SV40 IHC (R² = 0.65, p<0.0001). RNAscope ISH showed 88% sensitivity and 79% specificity and, as an alternative test, could confirm the presence of BKV tissue in presumed BKpyVAN and rule out BKV as the causative agent in JC virus nephropathy. We also used tissue BK viral load estimates by both RNAscope ISH and SV40 IHC to examine the relation between tissue and plasma BK levels and found significant correlation only between BK viremia and tissue BK measured by RNAscope ISH. Our findings suggest that the RNAscope ISH assay could be a reliable test for BKV detection in allograft biopsies.

The case for BK polyomavirus as a cause of bladder cancer

In 2014, the International Agency for Research on Cancer judged Merkel cell polyomavirus (MCPyV) to be a probable human carcinogen. BK polyomavirus (BKPyV, a distant cousin of MCPyV) was ruled a possible carcinogen. In this review, we argue that it has recently become reasonable to view both of these viruses as known human carcinogens. In particular, several complementary lines of evidence support a causal role for BKPyV in the development of bladder carcinomas affecting organ transplant patients. The expansion of inexpensive deep sequencing has opened new approaches to investigating the important question of whether BKPyV causes urinary tract cancers in the general population.