Tacrolimus Blood Level Fluctuation Predisposes to Coexisting BK Virus Nephropathy and Acute Allograft Rejection

Tacrolimus-why pharmacokinetics matter in the clinic

The calcineurin inhibitor (CNI) Tacrolimus (Tac) is the most prescribed immunosuppressant drug after solid organ transplantation. After renal transplantation (RTx) approximately 95% of recipients are discharged with a Tac-based immunosuppressive regime. Despite the high immunosuppressive efficacy, its adverse effects, narrow therapeutic window and high intra- and interpatient variability (IPV) in pharmacokinetics require therapeutic drug monitoring (TDM), which makes treatment with Tac a major challenge for physicians. The C/D ratio (full blood trough level normalized by daily dose) is able to classify patients receiving Tac into two major metabolism groups, which were significantly associated with the clinical outcomes of patients after renal or liver transplantation. Therefore, the C/D ratio is a simple but effective tool to identify patients at risk of an unfavorable outcome. This review highlights the challenges of Tac-based immunosuppressive therapy faced by transplant physicians in their daily routine, the underlying causes and pharmacokinetics (including genetics, interactions, and differences between available Tac formulations), and the latest data on potential solutions to optimize treatment of high-risk patients.

Correlation between CYP3A5 gene polymorphism and BK virus infection in kidney transplant recipients

BACKGROUND

Cytochrome P450 3A5 (CYP3A5) includes two active genotypes, namely CYP3A5*1/*1 or *1/*3 with the fast metabolic activity and CYP3A5*3/*3 with slow metabolic. We retrospectively analyzed the correlation between CYP3A5 gene polymorphism and the susceptibility to the BK virus (BKV) infection in renal transplant recipients.

METHODS

According to the inclusion/ exclusion criteria, we selected 134 recipients who received kidney transplantation at the Renmin Hospital of Wuhan University from January 2019 to December 2019. Based on the pre-operative CYP3A5 sequencing results, 134 recipients were divided into two groups: those expressing the fast metabolic CYP3A5*1/*1 or *1/*3 genotype; and, those expressing slow metabolic CYP3A5*3/*3 genotype. These two recipient groups were then analyzed for the BKV infection rate with different metabolic types to establish the potential relationship between CYP3A5 gene polymorphism and BKV infection.

RESULTS

The overall incidence of BKV viruria was 37.3%, whereas BKV viremia was 4.5% among all 134 recipients. The fast metabolism group had 9.1% incidence of BKV viremia and 49.1% incidence of BKV viruria. In contrast, the slow metabolism group had only 1.3%incidence of BKV viremia (P = 0.031) with only 29.1% BKV viruria (P = 0.011). The incidence of low levels of urinary BKV in the fast metabolism group was higher than that in the slow metabolism group (P = 0.005), while no significant statistical difference in the incidence of high levels of urinary BKV and high and low levels of blood BKV.

CONCLUSION

After kidney transplantation, CYP3A5 gene polymorphism of recipients present a certain relationship with the occurrence of BKV infection, which may be of value for the prediction and prevention of BKV infection.

A Prediction Model for Tacrolimus Daily Dose in Kidney Transplant Recipients With Machine Learning and Deep Learning Techniques

Tacrolimus is a major immunosuppressor against post-transplant rejection in kidney transplant recipients. However, the narrow therapeutic index of tacrolimus and considerable variability among individuals are challenges for therapeutic outcomes. The aim of this study was to compare different machine learning and deep learning algorithms and establish individualized dose prediction models by using the best performing algorithm. Therefore, among the 10 commonly used algorithms we compared, the TabNet algorithm outperformed other algorithms with the highest R² (0.824), the lowest prediction error [mean absolute error (MAE) 0.468, mean square error (MSE) 0.558, and root mean square error (RMSE) 0.745], and good performance of overestimated (5.29%) or underestimated dose percentage (8.52%). In the final prediction model, the last tacrolimus daily dose, the last tacrolimus therapeutic drug monitoring value, time after transplantation, hematocrit, serum creatinine, aspartate aminotransferase, weight, CYP3A5, body mass index, and uric acid were the most influential variables on tacrolimus daily dose. Our study provides a reference for the application of deep learning technique in tacrolimus dose estimation, and the TabNet model with desirable predictive performance is expected to be expanded and applied in future clinical practice.

The diagnostic and therapeutic dilemma of the co-existence of BK virus nephropathy with acute rejection - an experience from a single Centre and review of the literature

INTRODUCTION

BKV nephropathy (BKVN) is one of the major causes of graft loss with the advent of potent immunosuppressive drugs. The literature on the co-existence of acute rejection (AR) and BKVN is scarce.

MATERIALS AND METHODS

This is a single-center retrospective analysis, where the allograft biopsies of patients transplanted between 2011 and 2021 were reviewed. The biopsies, which showed evidence of coexistent AR and BKVN, were included. In addition, demographic profiles, clinical presentation, treatment details, response to therapy, and follow-up were analyzed.

RESULTS

Out of 1175 live transplants done between January 2011 and March 2021, 49 had BKVN representing 4.17%. Only seven patients (0.59%) had coexistent BKVN with AR. The mean serum creatinine at presentation was 2.3 mg/dl. The mean duration to diagnosis from transplant was seven months (range 3-22 months). All had significant viremia at presentation (17450-4,750,000 copies/ml). All biopsies showed type 1 inclusion bodies with SV40 positivity except one. Coexistent acute T cell-mediated rejection (TCMR) was found in five and acute ABMR in two patients. Three patients received pulse IV methylprednisolone, five received 2 g/kg IVIG, two received plasma exchange as upfront therapies. Maintenance immunosuppression reduction was made in all. Viremia clearance was noted at a mean duration of 3.5 months. However, three patients lost their grafts on follow-up. Four had stable graft function with a mean serum creatinine of 1.54 mg/dl.

CONCLUSION

Intensifying immunosuppression to treat AR followed by a reduction in maintenance immunosuppression and IVIG and antiviral therapies seems optimal strategy and showed good long-term graft survival in patients with coexistent BKVN and AR.

Impact of intrapatient blood level variability of calcineurin inhibitors on heart transplant outcomes

INTRODUCTION AND OBJECTIVES

Intrapatient blood level variability (IPV) of calcineurin inhibitors has been associated with poor outcomes in solid-organ transplant, but data for heart transplant are scarce. Our purpose was to ascertain the clinical impact of IPV in a multi-institutional cohort of heart transplant recipients.

METHODS

We retrospectively studied patients aged ≥18 years, with a first heart transplant performed between 2000 and 2014 and surviving≥ 1 year. IPV was assessed by the coefficient of variation of trough levels from posttransplant months 4 to 12. A composite of rejection or mortality/graft loss or rejection and all-cause mortality/graft loss between years 1 to 5 posttransplant were analyzed by Cox regression analysis.

RESULTS

The study group consisted of 1581 recipients (median age, 56 years; women, 21%). Cyclosporine immediate-release tacrolimus and prolonged-release tacrolimus were used in 790, 527 and 264 patients, respectively. On multivariable analysis, coefficient of variation> 27.8% showed a nonsignificant trend to association with 5-year rejection-free survival (HR, 1.298; 95%CI, 0.993-1.695; P=.056) and with 5-year mortality (HR, 1.387; 95%CI, 0.979-1.963; P=.065). Association with rejection became significant on analysis of only those patients without rejection episodes during the first year posttransplant (HR, 1.609; 95%CI, 1.129-2.295; P=.011). The tacrolimus-based formulation had less IPV than cyclosporine and better results with less influence of IPV.

CONCLUSIONS

IPV of calcineurin inhibitors is only marginally associated with mid-term outcomes after heart transplant, particularly with the tacrolimus-based immunosuppression, although it could play a role in the most stable recipients.

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.

Tacrolimus Trough Intravariability in Patients Treated With the Prolonged-Release Formulation Is a Risk Factor for Acute Graft Rejection

OBJECTIVES

Tacrolimus has a narrow therapeutic window, and lack of adherence to the therapeutic regimen is a main risk factor for acute graft rejection; hence, the prolonged-release formulation was created. A high intrapatient variability for tacrolimus trough levels has been associated with worse graft outcomes; therefore, we investigated the correlation between the tacrolimus variation coefficient and the development of biopsy-proven acute graft rejection in kidney transplant patients with typical maintenance immunosuppression versus the prolonged-release formulation.

MATERIALS AND METHODS

This was a single-center observational retrospective study that included all adult kidney transplants from deceased donors between January 2011 and December 2014 for which the transplant recipients were given maintenance therapy with tacrolimus prolonged-release formulation (Advagraf). The overall tacrolimus variation coefficient was calculated for the follow-up period from transplant until December 2019. Biopsy-proven acute graft rejection results were collected throughout follow-up. Statistical analysis was performed with SPSS software.

RESULTS

The study was composed of 147 patients with a mean follow-up time of 60.4 ± 15 months. The mean age of the patients was 47.5 ± 11.9 years and 67.3% were men. Of these 147 patients, 29 had at least 1 episode of acute graft rejection during follow-up. There was a significant correlation between patients with a higher tacrolimus variation coefficient and the presence of biopsy-proven acute graft rejection. Receiver operating characteristic curves were used to determine an intrapatient variability cutoff point of 28.3% for tacrolimus. Younger patients were also more likely than older patients to develop acute graft rejection in our sample.

CONCLUSIONS

High intrapatient variability of tacrolimus trough levels is a risk factor for acute graft rejection in kidney transplant patients.

Can uric acid blood levels in renal transplant recipients predict allograft outcome?

Background

Hyperuricemia is common after renal transplantation, especially in those receiving calcineurin inhibitors. Little, however, is known about the relationship between uric acid (UA) levels and allograft outcome.

Methods

We conducted a retrospective single-center analysis (N = 368) in order to assess UA blood levels post-transplant association with allograft outcome. For this study, a median serum UA level of all measured UA levels from 1 month to 1 year post renal transplantation was calculated.

Results

Patients were divided into 2 groups based on the median UA level measured between 1 and 12 months post-transplant. Those with median UA level ≥ 7 and ≥ 6 mg/dL (N = 164) versus median UA level < 7 and < 6 mg/dL for men and women respectively (N = 204) had lower GFR values at 1, 3 and 5 years posttransplant (mean GFR ± SD of 43.4 ± 20.6 and 58 ± 19.9 at 3 years post-transplant, p < 0.001). In multivariate models, UA levels were no longer significantly associated with renal allograft function. In a multivariate cox proportional hazard model, UA level was found to be independently associated with increased risk for death-censored graft loss (HR of 1.3, 95% CI 1.0–1.7, p < 0.05 for every increase of 1 mg/dL in UA level).

Conclusion

Hyperuricemia was found to be associated with increased death- censored graft loss but not with allograft function. Increased UA levels were not found to be an independent predictor of long-term allograft function despite the known association of hyperuricemia with the progression of cardiovascular and renal disease.

BK Polyomavirus Nephropathy in Kidney Transplantation: Balancing Rejection and Infection

BK polyomavirus nephropathy (BKVN) and allograft rejection are two closely-associated diseases on opposite ends of the immune scale in kidney transplant recipients. The principle of balancing the immune system remains the mainstay of therapeutic strategy. While patient outcomes can be improved through screening, risk factors identification, and rapid reduction of immunosuppressants, a lack of standard curative therapy is the primary concern during clinical practice. Additionally, difficulty in pathological differential diagnosis and clinicopathology’s dissociation pose problems for a definite diagnosis. This article discusses the delicate evaluation needed to optimize immunosuppression and reviews recent advances in molecular diagnosis and immunological therapy for BKVN patients. New biomarkers for BKVN diagnosis are under development. For example, measurement of virus-specific T cell level may play a role in steering immunosuppressants. The development of cellular therapy may provide prevention, even a cure, for BKVN, a complex post-transplant complication.

From Nonadherence to Adherence

Medication nonadherence (MNA) after solid organ transplantation is highly prevalent and associated with (late) (sub)clinical acute rejection, graft dysfunction and graft loss, development of donor-specific anti-HLA antibodies, and antibody-mediated rejection. MNA is predominantly unintentional and originates from barriers to adherence that are often multifactorial and complex. Tools to establish an early diagnosis of MNA include incorporation of MNA as a vital sign in daily clinical practice, self-reporting using validated questionnaires, calculating intrapatient variability in drug exposure and applying electronic monitoring, and recent audio and video technologies such as in home telemonitoring. MNA is a modifiable risk factor after organ transplantation, and treatment is most effective if a multimodal approach is used. Management of MNA comprises education (cognitive) and counseling (behavioral) that require the involvement of a trained multidisciplinary team [ideally physician, nurse (specialist), social worker, transplant coordinator, psychologist, clinical pharmacist], electronic reminder and support systems (eg, Medication Event Monitoring System, smartphone), and different types of novel mobile health applications as well as simplification of the medication dosing regimen. Future studies that evaluate novel therapeutic approaches for MNA should assure the use of reliable MNA measures, focus on multimodal individualized therapy for enriched nonadherent target populations (eg, adolescents), and incorporate clinically relevant endpoints. Costs, time, and personnel investments should be taken into account when assessing scalability and cost-effectiveness of novel therapeutic strategies. This review provides suggestions how different types of transplant centers can set up a dedicated MNA program according to available resources to define and achieve realistic clinical goals in managing MNA.

Characterization of aberrant pathways activation and immune microenviroment of BK virus associated nephropathy

In the context of transplantation with the use of immunosuppressive drugs, BK virus infection has become the main cause of BK virus nephropathy(BKVN) in renal transplant recipients(KTRs). More importantly, BKVN may cause further allograft dysfunction and loss. However, the role of the immune microenvironment in the pathogenesis of BKVN remains unknown. Therefore, we collected microarray data of KTRs to elucidate the immune characteristics of BKVN. Via the CIBERSORT, we found that BKVN had relatively more activated memory CD4 T cells. Immunostaining showed that CD4+ and CD8+cells were significantly different between BKVN and stable allografts(STAs). In addition, the expression of immune-related genes(antigen presentation, cytotoxicity, and inflammation) was significantly higher in BKVN than in STAs. The results of gene set enrichment analysis(GSEA) and single-sample GSEA(ssGSEA) indicated that immune cell-,cytokine-,chemokine-, and inflammation-related pathways were significantly activated in BKVN, while metabolism- and renal development-related pathways were significantly downregulated in BKVN. In addition, the immune microenvironments of the peripheral blood in patients with BK viremia(BKV) or transplant kidney biopsy(TKB) with BKVN may be different. Overall, the immune microenvironment may play important roles in the occurrence and development of BKVN and provide a theoretical basis for preventing the occurrence of BKVN and finding novel treatments.

Off-label use of tacrolimus in children with glomerular disease: Effectiveness, safety and pharmacokinetics

Glomerular diseases are leading causes of end-stage renal disease in children. Tacrolimus is frequently used off-label in the treatment of glomerular diseases. The effectiveness, safety and pharmacokinetic data of tacrolimus in the treatment of glomerular diseases in children are reviewed in this paper to provide evidence to support its rational use in clinical practice. The remission rates in previously published studies were different. In 19 clinical trials on children with nephrotic syndrome, the overall remission rate was 52.6-97.6%. In four clinical trials on children with lupus nephritis, the overall remission rate was 81.8-89.5%. In a pilot study with paediatric Henoch-Schönlein purpura nephritis patients, the overall remission rate was 100.0%. Infection, nephrotoxicity, gastrointestinal symptoms and hypertension are the most common adverse events. Body weight, age, CYP3A5 genotype, cystatin-C and daily dose of tacrolimus may have significant effects on the pharmacokinetics of tacrolimus in children with glomerular disease. More prospective controlled trials with long follow-up are needed to demonstrate definitely the effectiveness, safety and pharmacokinetics of tacrolimus in children with glomerular diseases.

Association of Intrapatient Variability of Tacrolimus Concentration With Early Deterioration of Chronic Histologic Lesions in Kidney Transplantation

Supplemental Digital Content is available in the text.

High intrapatient variability (IPV) of tacrolimus (Tac) is increasingly recognized as a risk factor for poor graft outcomes in kidney transplantation. The timing of onset of its impact on kidney histologic lesions has not been investigated.

A randomized clinical trial of age and genotype-guided tacrolimus dosing after pediatric solid organ transplantation

BACKGROUND

Tacrolimus pharmacokinetics are influenced by age and CYP3A5 genotype with CYP3A5 expressors (CYP3A5*1/*1 or *1/*3) being fast metabolizers. However, the benefit of genotype-guided dosing in pediatric solid organ transplantation has been understudied.

OBJECTIVE

To determine whether age and CYP3A5 genotype-guided starting dose of tacrolimus result in earlier attainment of therapeutic drug concentrations.

SETTING

Single hospital-based transplant center.

METHODS

This was a randomized, semi-blinded, 30-day pilot trial. Between 2012 and 2016, pediatric patients listed for solid organ transplant were consented and enrolled into the study. Participants were categorized as expressors, CYP3A5*1/*1 or CYP3A5*1/*3, and nonexpressors, CYP3A5*3/*3. Patients were stratified by age (≤ or > 6 years) and randomized (2:1) after transplant to receive genotype-guided (n = 35) or standard (n = 18) starting dose of tacrolimus for 36-48 hours and were followed for 30 days.

RESULTS

Median age at transplant in the randomized cohort was 2.1 (0.75-8.0) years; 24 (45%) were male. Participants in the genotype-guided arm achieved therapeutic concentrations earlier at a median (IQR) of 3.4 (2.5-6.6) days compared to those in the standard dosing arm of 4.7 (3.5-8.6) days (P = 0.049), and had fewer out-of-range concentrations [OR (95% CI) = 0.60 (0.44, 0.83), P = 0.002] compared to standard dosing, with no difference in frequency of adverse events between the two groups.

CONCLUSIONS

CYP3A5 genotype-guided dosing stratified by age resulted in earlier attainment of therapeutic tacrolimus concentrations and fewer out-of-range concentrations.

Identification of potential key protein interaction networks of BK virus nephropathy in patients receiving kidney transplantation

We aim to identify the key protein interaction networks and implicated pathways of BK virus nephropathy (BKVN) via bioinformatic methods. The microarray data GSE75693 of 30 patients with stable kidney transplantation and 15 with BKVN were downloaded and analyzed by using the limma package to identify differentially expressed genes (DEGs). Then the gene ontology (GO) functional enrichment analysis and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were done to investigate the molecular function (MF), biological process (BP), cellular components (CC) and pathways of DEGs. Finally, protein-protein interactions (PPIs) were constructed, and the hub proteins were  identified. As a result, 249 up-regulated genes and 253 down-regulated genes of BKVN patients were selected based on criteria of P > 0.01 and fold change >2.0. GO and KEGG showed that DEGs were mainly located in nucleus and cytosol, and were implicated in the immune responses. In the PPI analysis, 26 up-regulated and 8 down-regulated proteins composed the pivotal interaction network. CXCL10, EGF and STAT1 were identified as hub proteins in BKVN. In conclusion, CXCL10, EGF and STAT1 may induce kidney injuries by promoting inflammation and prohibiting reparation of tissue damage in BKVN.