Screening and Management Practices for Polyoma (BK) Viremia and Nephropathy in Kidney Transplant Recipients From the Lands Down Under: Addressing the Unknowns and Rationale for a Multicenter Clinical Trial

Preferences in treating polyomavirus infection in kidney transplant recipients: A discrete choice experiment with patients, caregivers, and clinicians

BACKGROUND

Treatment strategies for BK polyomavirus (BKPyV) infection in kidney transplant recipients are heterogeneous among clinicians. We aimed to identify the treatment preferences of key stakeholders for BKPyV infection and measure the trade-offs between treatment outcomes.

METHODS

Adult kidney transplant recipients, caregivers, and clinicians were eligible to participate in a discrete choice experiment between February 2021 and June 2022. The five treatment-related attributes were achieving viral clearance and optimal graft function, as well as reducing the risk of graft loss, acute rejection, and complications. Results were analyzed using multinomial logistic models.

RESULTS

In total, 109 participants (57 kidney transplant recipients, 10 caregivers, and 42 health professionals) were included. The most important attribute was the risk of graft loss, followed by side effects and acute rejection. As the risk of graft loss increased, all participants were less inclined to accept an assigned treatment strategy. For instance, if graft loss risk was increased from 1% to 50%, the probability of uptake of a treatment strategy for BKPyV infection was reduced from 87% to 3%.

CONCLUSION

Graft loss is the predominant concern for patients, caregivers, and health professionals when deciding on the treatment for BKPyV infection, and should be included in intervention trials of BKPyV infection.

Incidence and Outcomes of BK Virus Nephropathy in Kidney Transplant Recipients With Steroid-Free Maintenance Immunosuppression

BACKGROUND

BK virus nephropathy (BKVN) is a significant complication in kidney transplant recipients, resulting in graft dysfunction and potentially leading to graft loss. This study aims to investigate the incidence and outcomes of BKVN in kidney transplant recipients receiving steroid-free maintenance immunosuppression in a Latin -American cohort.

METHODS

Case series study of BKVN among kidney transplant recipients who underwent transplantation between 2008 and 2023. The primary outcome was graft loss caused by BKVN, excluding death with function. Secondary outcomes included graft function and acute rejection episodes. The statistical analysis involved descriptive statistics and the Kaplan-Meier (K-M) method to plot the overall probabilities of not initiating dialysis.

RESULTS

During the 15-year period, 2236 kidney transplants were performed, BKVN was histologically diagnosed in 38 kidney recipients and 33 cases were analyzed. Median age was 50 years and men were 48.5% of patients. A total of 45.4% of BKVN occurred within the first 12 months of transplant. The incidence of BKVN was 1.6% but it varied by era. The rate of graft loss was 75.7% (25 cases). The K-M graft survival probability at 6 months and 12 months after diagnosis of BKVN was 38.3% (95% CI 24.7-59.4) and 22.3% (95% CI 11.7-42.8), respectively.

CONCLUSION

BKVN affected 1.6% of transplant recipients and it was associated with high-rate of graft loss. We observed that significant graft disfunction at the time of diagnosis resulted in worse outcomes with a reduced probability of graft survival.

Incidence, Risk Factors, and Outcomes of Kidney Transplant Recipients With BK Polyomavirus-Associated Nephropathy

Introduction

BK polyomavirus-associated nephropathy (BKPyVAN) is associated with graft dysfunction and loss; however, knowledge of immunosuppression reduction strategies and long-term graft, and patient outcomes across the disease spectrum is lacking.

Methods

This cohort study included 14,697 kidney transplant recipients in Australia and New Zealand (2005-2019), followed for 91,306 person years.

Results

BKPyVAN occurred in 460 recipients (3%) at a median posttransplant time of 4.8 months (interquartile range, 3.1-10.8). Graft loss (35% vs. 21%, P < 0.001), rejection (42% vs. 25%, P < 0.001), and death (18% vs. 13%, P = 0.002) were more common in the BKPyVAN group. The most frequent changes in immunosuppression after BKPyVAN were reduction (≤50%) in tacrolimus (172, 51%) and mycophenolate doses (134, 40%), followed by the conversion of mycophenolate to leflunomide (62, 19%) and tacrolimus to ciclosporin (20, 6%). Factors associated with the development of BKPyVAN included (adjusted hazard ratio [HR]; 95% confidence interval) male sex (1.66; 1.34-2.05), recipient age (≥70 vs. <20 [2.46; 1.30-4.65]), recipient blood group (A vs. B [2.00; 1.19-3.34]), donor age (≥70 vs. <20 [2.99; 1.71-5.22]), earlier era (1.74; 1.35-2.25), donor/recipient ethnic mismatch (1.52; 1.23-1.87), tacrolimus use (1.46; 1.11-1.91), and transplantation at a lower-volume transplant center (1.61; 1.24-2.09). The development of BKPyVAN was associated with an increased risk of all-cause (1.75; 1.46-2.09) and death-censored graft loss (2.49; 1.99-3.11), but not mortality (1.15; 0.91-1.45).

Conclusions

BKPyVAN is associated with an increased risk of all-cause and death-censored graft loss, but not death. Interventional trials are urgently needed to evaluate the efficacy of immunosuppression reduction and novel strategies to minimize the adverse outcomes associated with BKPyVAN.

Evaluating the antibody response to SARS-COV-2 vaccination amongst kidney transplant recipients at a single nephrology centre

BACKGROUND AND OBJECTIVES

Kidney transplant recipients are highly vulnerable to the serious complications of severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) infections and thus stand to benefit from vaccination. Therefore, it is necessary to establish the effectiveness of available vaccines as this group of patients was not represented in the randomized trials.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A total of 707 consecutive adult kidney transplant recipients in a single center in the United Kingdom were evaluated. 373 were confirmed to have received two doses of either the BNT162b2 (Pfizer-BioNTech) or AZD1222 (Oxford-AstraZeneca) and subsequently had SARS-COV-2 antibody testing were included in the final analysis. Participants were excluded from the analysis if they had a previous history of SARS-COV-2 infection or were seropositive for SARS-COV-2 antibody pre-vaccination. Multivariate and propensity score analyses were performed to identify the predictors of antibody response to SARS-COV-2 vaccines. The primary outcome was seroconversion rates following two vaccine doses.

RESULTS

Antibody responders were 56.8% (212/373) and non-responders 43.2% (161/373). Antibody response was associated with greater estimated glomerular filtration (eGFR) rate [odds ratio (OR), for every 10 ml/min/1.73m2 = 1.40 (1.19-1.66), P<0.001] whereas, non-response was associated with mycophenolic acid immunosuppression [OR, 0.02(0.01-0.11), p<0.001] and increasing age [OR per 10year increase, 0.61(0.48-0.78), p<0.001]. In the propensity-score analysis of four treatment variables (vaccine type, mycophenolic acid, corticosteroid, and triple immunosuppression), only mycophenolic acid was significantly associated with vaccine response [adjusted OR by PSA 0.17 (0.07-0.41): p<0.001]. 22 SARS-COV-2 infections were recorded in our cohort following vaccination. 17(77%) infections, with 3 deaths, occurred in the non-responder group. No death occurred in the responder group.

CONCLUSION

Vaccine response in allograft recipients after two doses of SARS-COV-2 vaccine is poor compared to the general population. Maintenance with mycophenolic acid appears to have the strongest negative impact on vaccine response.

Polyoma BK Virus in Kidney Transplant Recipients: Screening, Monitoring, and Management

Polyomavirus BK virus (BKPyV) infection is an important complication of kidney transplantation and allograft failure. The prevalence of viremia is 10%-15%, compared with BK-associated nephropathy (BKPyVAN) at 3%-5%. Given that there are no effective antiviral prophylaxis or treatment strategies for BKPyVAN, active screening to detect BKPyV viremia is recommended, particularly during the early posttransplant period. Immunosuppression reduction to allow viral clearance may avoid progression to severe and irreversible allograft damage. The frequency and duration of screening are highly variable between transplant centers because the evidence is reliant largely on observational data. While the primary treatment goals center on achieving viral clearance through immunosuppression reduction, prevention of subsequent acute rejection, premature graft loss, and return to dialysis remain as major challenges. Treatment strategies for BKPyV infection should be individualized to the recipient's underlying immunological risk and severity of the allograft infection. Efficacy data for adjuvant therapies including intravenous immunoglobulin and cidofovir are sparse. Future well-powered and high-quality randomized controlled trials are needed to inform evidence-based clinical practice for the management of BKPy infection.