A longitudinal study of long-term renal outcome after pediatric liver transplantation in relation to CNI exposure

BACKGROUND

Chronic kidney disease (CKD) is reported in 20%-30% of children after liver transplantation (LT). One of the proposed underlying causes is the long-term exposure to tacrolimus, a calcineurin inhibitor (CNI), which is the main immunosuppressive drug used after LT. Variation in tacrolimus absolute exposure and relative dose requirements are believed to be important risk factors for developing CNI-associated nephrotoxicity.

AIM

To describe the long-term renal outcome of pediatric LT recipients and determine the effects of tacrolimus exposure on renal outcome parameters.

METHODS

Retrospective single center study of renal function (GFR, proteinuria) and pharmacokinetic parameters (C0 , AUC0-12h ) obtained during annual follow-up in children after liver transplantation, between 1998 and 2019. Relevant pharmacogenetic variants for tacrolimus disposition (CYP3A5 and ABCB1) were determined in recipients and donors. The evolution of individual renal function and tacrolimus exposure was evaluated using linear mixed models for repeated measurements.

RESULTS

Twenty-six children were included (mean follow-up: 10.4 years (range 2-18.9)). Mean estimated GFR was 109.3 (SE: 7.4), vs. measured: 91.3 mL/min/1.73 m2 (SE: 6.3), which remained stable during follow-up. CKD stage ≥2 was observed in 32.8% of the visits based on eGFR versus 50.0% on mGFR. CKD stage ≥3 was uncommon (4.1% and 6.2% resp.). Mean tacrolimus C0 was 5.3 ng/mL (SE: 2.5) with a AUC0-12h of 72.7 ng*h/mL (SE: 30.3), which demonstrated a small decrease during follow-up. There was a negative correlation between C0 and mGFR (rS  = -0.3; p < .001). We found no correlation between GFR and tacrolimus dose requirements ((ng/mL)/(mg/kg)) or pharmacogenetic background.

CONCLUSION

Renal function during long-term follow-up after pediatric LT remained stable for the majority of our cohort. However, mild CKD was relatively common, warranting follow-up into adulthood. Although absolute tacrolimus exposure has a small depressing effect on concurrent GFR, there is no progressive deterioration of GFR due to long-term exposure, dose requirements or genetic background under the current target levels. These findings should be confirmed in a larger sample set, ideally including data from multiple centers.

Lack of Improvement in Insulin Sensitivity After Pancreas Transplantation in Recipients With a High Level of Calcineurin Inhibitors

OBJECTIVES

This study aimed to assess posttransplant changes in insulin sensitivity and β-cell function of pancreas transplant recipients according to the type of diabetes mellitus (DM) and the pretransplant insulin sensitivity measured by the Matsuda Index (MI).

METHODS

We analyzed 60 patients who underwent pancreas transplantation and oral glucose tolerance test pretransplant and at 1 month posttransplant.

RESULTS

At 1 month posttransplant, insulin sensitivity did not show significant improvement; particularly, the MI was significantly lower after transplant in recipients with type 1 DM (T1DM) and those with pretransplant MI of 5 or greater. β-cell function was significantly improved after transplant in all recipients regardless of the type of DM and pretransplant MI values. Glucose control was significantly improved in recipients with T1DM and in all recipients regardless of the pretransplant MI values. Additional oral glucose tolerance test at 1 year posttransplant revealed that insulin sensitivity remained unimproved and β-cell function was higher compared with pretransplant. Glucose control had partially reverted to pretransplant levels in recipients with T1DM and those with pretransplant MI of 5 or greater.

CONCLUSIONS

Unlike β-cell function and glucose control, insulin sensitivity did not significantly improve until posttransplant 1 year after pancreas transplantation regardless of the type of DM or the degree of pretransplant insulin sensitivity.

Maintenance Immunosuppression in Solid Organ Transplantation: Integrating Novel Pharmacodynamic Biomarkers to Inform Calcineurin Inhibitor Dose Selection

Calcineurin inhibitors, the primary immunosuppressive therapy used to prevent alloreactivity of transplanted organs, have a narrow therapeutic index. Currently, treatment is individualized based on clinical assessment of the risk of rejection or toxicity guided by trough concentration monitoring. Advances in immune monitoring have identified potential markers that may have value in understanding calcineurin inhibitor pharmacodynamics. Integration of these markers has the potential to complement therapeutic drug monitoring. Existing pharmacokinetic-pharmacodynamic (PK-PD) data is largely limited to correlation between the biomarker and trough concentrations at single time points. Immune related gene expression currently has the most evidence supporting PK-PD integration. Novel biomarker-based approaches to pharmacodynamic monitoring including development of enhanced PK-PD models are proposed to realize the full clinical benefit.

Clinical Pharmacokinetic and Pharmacodynamic Considerations in the Treatment of Ulcerative Colitis

Ulcerative colitis (UC) is an inflammatory bowel disease (IBD) of unknown etiology, probably caused by a combination of genetic and environmental factors. The treatment of patients with active UC depends on the severity, localization and history of IBD medication. According to the classic step-up approach, treatment with 5-aminosalicylic acid compounds is the first step in the treatment of mild to moderately active UC. Corticosteroids, such as prednisolone are used in UC patients with moderate to severe disease activity, but only for remission induction therapy because of side effects associated with long-term use. Thiopurines are the next step in the treatment of active UC but monotherapy during induction therapy in UC patients is not preferred because of their slow onset. Therapeutic drug monitoring (TDM) of the pharmacologically active metabolites of thiopurines, 6-thioguanine nucleotide (6-TGN), has proven to be beneficial. Thiopurine S-methyltransferase (TMPT) plays a role in the metabolic conversion pathway of thiopurines and exhibits genetic polymorphism; however, the clinical benefit and relevance of TPMT genotyping is not well established. In patients with severely active UC refractory to corticosteroids, calcineurin inhibitors such as ciclosporin A (CsA) and tacrolimus are potential therapeutic options. These agents usually have a rather rapid onset of action. Monoclonal antibodies (anti-tumor necrosis factor [TNF] agents, vedolizumab) are the last pharmacotherapeutic option for UC patients before surgery becomes inevitable. Body weight, albumin status and antidrug antibodies contribute to the variability in the pharmacokinetics of anti-TNF agents. Additionally, the use of concomitant immunomodulators (thiopurines/methotrexate) lowers the rate of immunogenicity, and therefore the concomitant use of anti-TNF therapy with an immunomodulator may confer some advantage compared with monotherapy in certain patients. TDM of anti-TNF agents could be beneficial in patients with primary nonresponse and secondary loss of response. The potential benefit of applying TDM during vedolizumab treatment has yet to be determined.

Clinical observation on the effect of Wuzhi soft capsule on FK506 concentration in membranous nephropathy patients

The current research aimed to investigate the correlation between the effect of Wuzhi soft capsule (WZC) on FK506 concentration and CYP3A5 gene polymorphism in patients with membranous nephropathy (MN).Seventy-five patients with idiopathic MN were enrolled and divided according to the expression of CYP3A5 gene metabolic enzyme into group A (CP3A5 metabolic enzyme function expression types CYP3A5*1/*1 type and CYP3A5*1/*3 type), and group B (non-expression type CYP3A5*3/*3 type). All patients were given oral administration of tacrolimus capsule at the initial dose of 1 mg for twice a day 1 hour before breakfast and dinner. Afterwards, the oral administration of WZC was added at the dose of 0.5 g for 3 times a day within half an hour after 3 meals.The blood concentrations of FK506 in groups A and B were significantly higher than those before administration. Compared with that before administration, the FK506 blood concentration was increased by 3.051 ± 0.774 ng/ml after adding the WZC. Besides, the blood concentrations of FK506 in group A were lower than those in group B before and after administration; meanwhile, the 24 hours total urine protein and the biochemical indexes in both groups displayed no statistically significant difference. Only 1 case of diarrhea was observed, which was relieved after the reduction of tacrolimus.Wuzhi soft capsule can significantly increase the blood concentration of FK506 in MN patients. Moreover, the CYP3A5 genotyping should be considered when WZC is used to increase the blood concentration of FK506.

Drug-Drug Interaction Study of Apixaban with Cyclosporine and Tacrolimus in Healthy Volunteers

Apixaban is metabolized by cytochrome P450 (CYP) 3A4 in the liver and intestine, undergoes direct intestinal excretion, and is a substrate to permeability glycoprotein (P-gp) and breast cancer resistance protein (BCRP) transporters. We examined the drug interactions between cyclosporine and tacrolimus (combined inhibitors of CYP3A4, P-gp, and BCRP) with apixaban in 12 healthy adult male volunteers. Apixaban 10 mg was administered orally alone, in combination with 100 mg cyclosporine or 5 mg tacrolimus. Co-administration with cyclosporine resulted in increase in apixaban maximum plasma concentration (Cmax ) and area under the plasma concentration-time curve from time zero to the last quantifiable concentration (AUC(0-tlast) ) with associated geometric mean ratios (GMRs) and 90% confidence intervals (CIs) of 143% (112, 183) and 120% (97, 148), respectively. Co-administration with tacrolimus resulted in reduction in apixaban Cmax and AUC(0-tlast) with associated GMRs (90% CI) of 87% (69, 112) and 78% (63, 97), respectively. The observed changes in apixaban exposure margins with cyclosporine or tacrolimus are within the range of the historical clinical development program, therefore, apixaban dose adjustments are not warranted.

Population pharmacokinetics of tacrolimus in children with nephrotic syndrome

AIMS

Nephrotic syndrome (NS) is the most common clinical manifestation of glomerular disease in children. Currently, tacrolimus (TAC) is widely used in children with NS. However, pharmacokinetic data in children with nephrotic syndrome is limited. This study was intended to evaluate the population pharmacokinetics (PPK) of TAC in paediatric NS and to optimize dosing regimen.

METHODS

Blood samples from NS children treated with TAC were collected and the blood concentrations of TAC were detected using HPLC-MS/MS. A PPK model was developed using NONMEM software. Pharmacogenetic analysis was carried out in the CYP3A5 gene.

RESULTS

The data from 28 children were used for PPK analysis. A one-compartment model and first-order elimination were accorded with the TAC data in paediatric NS. A covariate analysis showed that body weight and CYP3A5 genotype significantly affected TAC pharmacokinetics. Monte Carlo simulation indicated that NS children with CYP3A5*3/*3 receiving 0.10 mg kg-1  dose-1 twice daily and NS children with CYP3A5*1 receiving 0.25 mg kg-1  dose-1 twice daily TAC could achieve the target concentrations of 5-10 ng ml-1 .

CONCLUSION

The PPK of TAC was estimated in children with NS and a CYP3A5 genotype-based dosing regimen was set up based on simulations.

Modeling of Tacrolimus Exposure in Kidney Transplant According to Posttransplant Time Based on Routine Trough Concentration Data

OBJECTIVES

The aim of this study was to develop a pharmacokinetics model allowing the description of the evolution of tacrolimus exposure in kidney transplant patients over the first months after transplant, using trough concentrations of routinely collected blood.

MATERIALS AND METHODS

The authors performed a retrospective analysis of trough concentration data collected from adult kidney transplant recipients (from 2008 to 2013). The total data set was divided into a building data set, used to build the structural model, and a validation data set, used to validate the structural model. (C0 = 133; 26 patients). A pharmacokinetics analysis was carried out by applying a nonparametric adaptive grid approach. The structural model parameters were tacrolimus clearance and volume of distribution.

RESULTS

In patients in the building set group, estimated clearance was 3.6 ± 0.57 L/h and estimated volume of distribution was 9.9 ± 1.14 L. No covariate was significantly associated with tacrolimus clearance or volume of distribution. The model adequately described tacrolimus dose-normalized trough concentration evolution after transplant (the plot of individual model predicted versus observed concentrations resulted in r = 0.84). The prediction performance in the validation group yielded 2.3% mean prediction error and 21.4% root mean squared error.

CONCLUSIONS

This model could be highly useful in the optimization of tacrolimus prescription at any posttransplant time in kidney transplant patients.

Comparative Proteomic Analysis of Rapamycin Versus Cyclosporine Combination Treatment in Mouse Podocytes

BACKGROUND

The mechanism of podocyte injury observed with the use of rapamycin (RPM) remains unclear. The conversion from calcineurin inhibitors (CNIs) to RPM in kidney transplant recipients has been associated with a higher incidence of proteinuria and renal injury. In this study, we performed proteomic analyses to investigate the alteration of protein expression in mouse podocytes treated with RPM in comparison with CNI/RPM combination.

METHODS

Immortalized mouse podocytes were treated with 20 nmol/L RPM or 20 nmol/L RPM + 1 μg/mL cyclosporine. Podocyte proteins were separated by 2-dimensional polyacrylamide gel electrophoresis (2DE) and identified by matrix-assisted laser desorption time-of-flight (MALDI-TOF) mass spectrometry and peptide fingerprinting. Selected proteins were analyzed by means of Western blot assay.

RESULTS

We identified 36 differently expressed proteins after isolated RPM or CNI/RPM combination treatment in cultured mouse podocytes. There are 3 distinct patterns of protein expression: (1) potentiated down- or upregulation of proteins by CNI/RPM treatment compared with isolated RPM treatment (n = 4); (2) partial offset of down-regulation by CNI/RPM in comparison with RPM treatment (n = 25); (3) no difference in down-regulation between RPM and CNI/RPM treatment (n = 5). We found a significant interplay between RPM and CNI on the expression of the selected proteins in mouse podocytes. This might explain the higher incidence of proteinuria by CNI/RPM combination in clinical settings.

CONCLUSIONS

Further study is required to elucidate the target protein associated with RPM-induced podocyte injury.

Effects of Genetic Polymorphism in CYP3A4 and CYP3A5 Genes on Tacrolimus Dose Among Kidney Transplant Recipients

INTRODUCTION

This study aimed to evaluate the effects of single nucleotide polymorphisms CYP3A4*1B and CYP3A5*3 on tacrolimus dose requirement among kidney transplant recipients.

MATERIALS AND METHODS

Blood levels of tacrolimus were measured using microparticle enzyme immunoassay. Genotyping analysis utilized specific polymerase chain reaction-restriction fragment length polymorphism methods for 137 kidney transplant recipients.

RESULTS

The median tacrolimus dose was significantly lower in the CYP3A4*1/*1 carriers (0.06 mg/kg/d; range, 0.007 mg/kg/d to 0.17 mg/kg/d) as compared to the CYP3A4*1B/*1B carriers (0.1 mg/kg/d; range, 0.03 mg/kg/d to 0.22 mg/kg/d; P = .001). Patients with at least 1 CYP3A5*1 wild-type allele required higher median doses of tacrolimus (median, 0.08 mg/kg/d; range, 0.03 mg/kg/d to 0.22 mg/kg/d) as compared to the CYP3A5*3 carriers (median, 0.05 mg/kg/d; range, 0.007 mg/kg/d  to 0.17 mg/kg/d; P = .002).

CONCLUSIONS

This study showed that tacrolimus dose requirement is lower in Jordanian kidney transplant recipients compared to other populations. Moreover, we found a correlation between genetic variations in CYP3A4 and CYP3A5 enzymes and tacrolimus blood levels among our kidney transplant recipients.

Polymorphism of the CYP3A5 gene and its effect on tacrolimus blood level

OBJECTIVES

Tacrolimus is the cornerstone for immunosuppression in renal transplant and is metabolized by the cytochrome P 450 3A (CYP3A) subfamily of enzymes in the liver and small intestine. A polymorphism in intron 3 of the CYP3A5 gene affects the expression of this enzyme and tacrolimus trough blood levels. The purpose of this study was to identify the proportion of CYP3A5 gene polymorphisms in South Indian renal transplant patients and determine the effect of CYP3A5 gene polymorphisms on tacrolimus trough blood levels in patients with and without CYP3A5 expression.

MATERIALS AND METHODS

We included 25 adult patients who underwent renal transplant at Government Medical College, Trivandrum. All patients received tacrolimus (dose, 0.1 mg/kg/body weight, in 2 divided doses). Tacrolimus trough blood levels were determined on postoperative day 6. The CYP3A5 genotype analysis was performed by polymerase chain reaction amplification of target and detection by restriction fragment length polymorphism analysis.

RESULTS

The CYP3A5*1/*1 genotype was detected in 5 recipients (20%), *1/*3 genotype in 5 recipients (20%), and *3/*3 genotypes in 15 recipients (60%) of the total 25 graft recipients. Mean tacrolimus level in the CYP3A5*1/*1 group was 5.154 ng/mL (range, 4.42 to 6.5 ng/mL), CYP3A5*1/*3 group was 5.348 ng/mL (range, 3.1 to 9.87 ng/mL), and CYP3A5*3/*3 group was 9.483 ng/mL (range, 4.5 to14.1 ng/mL). Acute rejection episodes were significantly more frequent for CYP3A5*1/*1 homozygous patients (40%) than patients with CYP3A5*1/*3 (20%) or CYP3A5*3/*3 (13%) genotypes.

CONCLUSIONS

Most patients carried the mutant allele CYP3A5*3 (A6986G). Tacrolimus drug level correlated well with presence or absence of CYP3A5 polymorphisms. Acute rejection episodes were more frequent in expressors, and they may require higher doses of tacrolimus. Similarly, tacrolimus nephrotoxicity was more frequent in non-expressors. Therefore, CYP3A5 polymorphism analysis before renal transplant may help determine the optimal dose of tacrolimus in this population and prevent acute rejection episodes or tacrolimus toxicity.

The proton pump inhibitor lansoprazole, but not rabeprazole, the increased blood concentrations of calcineurin inhibitors in Japanese patients with connective tissue diseases

OBJECTIVE

Proton pump inhibitors (PPIs) are frequently coadministered with calcineurin inhibitors (CNIs) such as tacrolimus (TAC) and cyclosporin A (CSA), to treat or prevent upper gastrointestinal complications in Japanese patients with connective tissue diseases (CTDs). The coadministration of PPIs increases the blood concentration of TAC due to drug interaction. We retrospectively investigated the influence of the coadministration of PPIs and CNIs, as well as the influence of the cytochrome P450 (CYP) 2C19 gene polymorphism status, on the blood concentrations of TAC and CSA in patients with CTDs.

METHODS

Patients treated with TAC (n=35) or CSA (n=30) were enrolled and divided into three groups according to the PPI they received: lansoprazole (LPZ)-combined, rabeprazole (RPZ)-combined, and non-PPI-combined groups. We compared the blood concentrations of TAC or CSA and the incidences of adverse events among the three groups. CYP2C19 gene polymorphisms were also assessed to investigate its influence on the blood concentration of TAC or CSA.

RESULTS

LPZ significantly increased the blood concentration of TAC 12 hours after TAC administration (p=0.030 and p=0.003, respectively) and CSA (p=0.047 and p=0.014, respectively) in comparison with RPZ and non-PPI-combined treatment. There were no significant differences in the mean CSA blood concentration two hours after administration in patients with or without PPI treatment, in the incidence of adverse events, or in the CYP2C19 gene polymorphism status among the three groups.

CONCLUSION

Combining agents that are mainly metabolized by CYP3A4 such as LPZ elevates the blood concentrations of TAC and CSA, which could leading to adverse events.

Higher Serum Trough Levels of Tacrolimus Increase 5-Year Allograft Survival in Antibody Positive Renal Transplant Patients

BACKGROUND

The presence of human leukocyte antigen (HLA) and major histocompatibility complex class I chain-related gene-A (MICA) antibodies after transplantation is correlated with rejection episodes, proteinuria, and renal allografts loss. We assessed the clinical value of high-dose tacrolimus on post-transplant HLA and MICA antibodies and proteinuria after renal transplantation.

METHODS

Post-transplant sera of 310 renal transplantation patients who were negative for antibodies prior to transplant were tested by Luminex flow cytometry for HLA antibodies and MICA antibodies posttransplant. Once a patient was found to be antibody positive (Ab+), tacrolimus was dosed at two different concentrations: high tacrolimus Ab+ group (11 ± 1.36 ng/mL average tacrolimus trough) or low tacrolimus Ab+ group (7 ± 1.28 ng/mL average tacrolimus trough). Antibody negative (Ab-) patients were also studied and were given comparable tacrolimus doses to the low tacrolimus Ab+ group (7 ± 1.28 ng/mL average tacrolimus trough). Proteinuria was measured using the pyrogallol method. All patients were followed for 5 years after renal transplantation. Associations between tacrolimus, proteinuria, and survival were analyzed.

RESULTS

In the HLA or MICA Ab+ patients, proteinuria decreased after 5 years in the high tacrolimus Ab+ group unlike the low tacrolimus Ab+ group. Allograft survival in the high tacrolimus Ab+ group was significantly higher than the low tacrolimus Ab+ group and was similar to that of the Ab- group.

CONCLUSIONS

High-dose tacrolimus might play a role in improving allograft survival in HLA or MICA Ab+ post-transplant patients. Increasing tacrolimus concentration might be a plausible treatment for Ab+ post-transplant patients.