Effects of Combinational CYP3A5 6986A>G Polymorphism in Graft Liver and Native Intestine on the Pharmacokinetics of Tacrolimus in Liver Transplant Patients: A Meta-Analysis

Population pharmacokinetic models of tacrolimus in paediatric solid organ transplant recipients: A systematic review

AIMS

This study aimed to provide up-to-date information on paediatric population pharmacokinetic models of tacrolimus and to identify factors influencing tacrolimus pharmacokinetic variability.

METHODS

Systematic searches in the Web of Science, PubMed, Scopus, Science Direct, Cochrane, EMBASE databases and reference lists of articles were conducted from inception to March 2023. All population pharmacokinetic studies of tacrolimus using nonlinear mixed-effect modelling in paediatric solid organ transplant patients were included.

RESULTS

Of the 21 studies reviewed, 62% developed from liver transplant recipients and 33% from kidney transplant recipients. Most studies used a 1-compartment model to describe tacrolimus pharmacokinetics. Body weight was a significant predictor for tacrolimus volume of distribution (Vd/F). The estimated Vd/F for 1-compartment models ranged from 20 to 1890 L, whereas the peripheral volume of distribution (Vp/F) for 2-compartment models was between 290 and 1520 L. Body weight, days post-transplant, CYP3A5 genotype or haematocrit were frequently reported as significant predictors of tacrolimus clearance. The estimated apparent clearance values range between 0.12 and 2.18 L/h/kg, with inter-individual variability from 13.5 to 110.0%. Only 29% of the studies assessed the generalizability of the models with external validation.

CONCLUSION

This review highlights the potential factors, modelling approaches and validation methods that impact tacrolimus pharmacokinetics in a paediatric population. The clinician could predict tacrolimus clearance based on body weight, CYP3A5 genotype, days post-transplant or haematocrit. Further research is required to determine the relationship between pharmacogenetics and tacrolimus pharmacodynamics in paediatric patients and confirm the applicability of nonlinear kinetics in this population.

Personalized Tacrolimus Dosing After Liver Transplantation: A Randomized Clinical Trial

Background

Inter- and intra-individual variability in tacrolimus dose requirements mandates empirical clinician-titrated dosing that frequently results in deviation from a narrow target range. Improved methods to individually dose tacrolimus are needed. Our objective was to determine whether a quantitative, dynamically-customized, phenotypic-outcome-guided dosing method termed Phenotypic Personalized Medicine (PPM) would improve target drug trough maintenance.

Methods

In a single-center, randomized, pragmatic clinical trial ( NCT03527238 ), 62 adults were screened, enrolled, and randomized prior to liver transplantation 1:1 to standard-of-care (SOC) clinician-determined or PPM-guided dosing of tacrolimus. The primary outcome measure was percent days with large (>2 ng/mL) deviation from target range from transplant to discharge. Secondary outcomes included percent days outside-of-target-range and mean area-under-the-curve (AUC) outside-of-target-range per day. Safety measures included rejection, graft failure, death, infection, nephrotoxicity, or neurotoxicity.

Results

56 (29 SOC, 27 PPM) patients completed the study. The primary outcome measure was found to be significantly different between the two groups. Patients in the SOC group had a mean of 38.4% of post-transplant days with large deviations from target range; the PPM group had 24.3% of post-transplant days with large deviations; (difference -14.1%, 95% CI: -26.7 to -1.5 %, P=0.029). No significant differences were found in the secondary outcomes. In post-hoc analysis, the SOC group had a 50% longer median length-of-stay than the PPM group [15 days (Q1-Q3: 11-20) versus 10 days (Q1-Q3: 8.5-12); difference 5 days, 95% CI: 2-8 days, P=0.0026].

Conclusions

PPM guided tacrolimus dosing leads to better drug level maintenance than SOC. The PPM approach leads to actionable dosing recommendations on a day-to-day basis.

Lay Summary

In a study on 62 adults who underwent liver transplantation, researchers investigated whether a new dosing method called Phenotypic Personalized Medicine (PPM) would improve daily dosing of the immunosuppression drug tacrolimus. They found that PPM guided tacrolimus dosing leads to better drug level maintenance than the standard-of-care clinician-determined dosing. This means that the PPM approach leads to actionable dosing recommendations on a day-to-day basis and can help improve patient outcomes.

The Impact of ABCB1 SNPs on Tacrolimus Pharmacokinetics in Liver or Kidney Transplant Recipients: A Meta-analysis

PURPOSE

We aimed to investigate the association between ATP Binding Cassette Subfamily B Member 1 (ABCB1) single nucleotide polymorphisms (SNPs) and the pharmacokinetics of tacrolimus.

METHODS

A search was conducted in Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science (SCI), MEDLINE, and Embase from inception to November 2022. Outcomes included weightadjusted daily dose (DD) and dose-adjusted trough concentration (C0/Dose).

RESULTS

A total of 1059 liver or kidney transplant recipients from 14 publications were included. For adult liver transplantation recipients, DD of ABCB1 3435C>T CC carriers was 0.03 mg/kg/day (WMD = 0.03, 95% CI: 0.01 to 0.05, I2 = 0%) higher than ABCB1 3435C>T T carriers at post-transplantation ≤ 7 days; C0/dose of ABCB1 3435C>T CC carriers were 31.88 (WMD = -31.88, 95% CI: -62.32 to -1.45, I2 = 83.5%) or 34.61 (ng/ml)/(mg/kg/day) (WMD = -34.61, 95% CI: -65.26 to -3.97, I2 = 55.3%) lower than ABCB1 3435C>T T carriers at post-transplantation ≤ 7 or 14 days, respectively. No difference in C0/dose was observed for ABCB1 2677G>T/A or ABCB1 1236C>T SNPs in both liver and kidney transplant recipients.

CONCLUSION

ABCB1 3435C>T SNP might have a potential impact on tacrolimus pharmacokinetics in the early stage after liver transplantation, indicating the probability of individualized immunosuppressive therapy based on genetic polymorphism. Given some limitations, further well-designed prospective studies are warranted to validate these conclusions.

CYP3A7, CYP3A4, and CYP3A5 genetic polymorphisms in recipients rather than donors influence tacrolimus concentrations in the early stages after liver transplantation

AIM

The purpose of this study was to investigate the effect of CYP3A7, CYP3A4, and CYP3A5 genetic polymorphisms in liver transplant recipients and donors on tacrolimus concentrations in the early stages after liver transplantation.

METHODS

One hundred and thirty-eight liver transplant recipients and matched donors were genotyped for CYP3A7 (rs10211 and rs2257401), CYP3A4 (rs4646437 and rs2242480), and CYP3A5*3 (rs776746) polymorphisms. The relationships between dose-adjusted trough concentrations (C₀/D) of tacrolimus and corresponding genotypes were investigated.

RESULTS

Recipient CYP3A polymorphisms were associated with tacrolimus concentrations. The CYP3A7 rs10211 AA carriers (186.2 vs 90.5, p < 0.001), CYP3A4 rs4646437 CC carriers (184.0 vs 88.8, p < 0.001), CYP3A4*1G rs2242480 CC carriers (189.8 vs 99.7, p < 0.001), and CYP3A5*3 rs776746 GG carriers (197.3 vs 86.0, p < 0.001) had an almost twofold increase in the tacrolimus C₀/D compared to that of the non-carriers. We further investigated the effect of the combination of recipient (intestinal) and donor (hepatic) genotypes on tacrolimus concentrations. Regardless of the genotype of the matched donor, CYP3A7 rs10211, CYP3A4*1G (rs2242480), and CYP3A5*3 (rs776746) polymorphisms of recipients could affect tacrolimus concentrations. For the CYP3A4 rs4646437 polymorphisms, when the donor carried CYP3A4 rs4646437 CC, the recipient CYP3A4 rs4646437 polymorphism was associated with the C₀/D of tacrolimus, and when the donor carried CYP3A4 rs4646437 CT/TT genotype, the recipient CYP3A4 rs4646437 polymorphism also affected on tacrolimus C₀/D, although the effect was not significant.

CONCLUSION

The large inter-individual variation in tacrolimus concentrations in the early stages after liver transplantation is influenced by genetic polymorphisms of CYP3A7, CYP3A4, and CYP3A5. Recipient (intestinal) CYP3A7, CYP3A4, and CYP3A5 polymorphisms seem to contribute more to such variation than donors. Therefore, the detection of CYP3A polymorphisms in recipients could help to predict the tacrolimus starting dose in the early stages after liver transplantation.

Therapeutic drug monitoring of immunosuppressive drugs in hepatology and gastroenterology

Immunosuppressive drugs have been key to the success of liver transplantation and are essential components of the treatment of inflammatory bowel disease (IBD) and autoimmune hepatitis (AIH). For many but not all immunosuppressants, therapeutic drug monitoring (TDM) is recommended to guide therapy. In this article, the rationale and evidence for TDM of tacrolimus, mycophenolic acid, the mammalian target of rapamycin inhibitors, and azathioprine in liver transplantation, IBD, and AIH is reviewed. New developments, including algorithm-based/computer-assisted immunosuppressant dosing, measurement of immunosuppressants in alternative matrices for whole blood, and pharmacodynamic monitoring of these agents is discussed. It is expected that these novel techniques will be incorporate into the standard TDM in the next few years.

Frequency of CYP3A5 Genetic Polymorphisms and Tacrolimus Pharmacokinetics in Pediatric Liver Transplantation

The evidence available in the pediatric population is limited for making clinical decisions regarding the optimization of tacrolimus (TAC) in pharmacotherapy. The objective of this study was to estimate the frequency of CYP3A5 genetic polymorphisms and their relationship with tacrolimus requirements in the pediatric population. This was a longitudinal cohort study with a two-year follow-up of 77 patients under 18 years old who underwent a liver transplant during the period 2009–2012 at the J.P. Garrahan Pediatric Hospital. Tacrolimus levels from day five up to two years after the transplant were obtained from hospital records of routine therapeutic drug monitoring. The genotyping of CYP3A5 (CYP3A5*1/*3 or *3/*3) was performed in liver biopsies from both the donor and the recipient. The frequency of CYP3A5*1 expression for recipients was 37.1% and 32.2% for donors. Patients who received an expresser organ showed lower Co/dose, especially following 90 days after the surgery. The role of each polymorphism is different according to the number of days after the transplant, and it must be taken into account to optimize the benefits of TAC therapy during the post-transplant induction and maintenance phases.

Effects of CYP3A5 Polymorphisms on Efficacy and Safety of Tacrolimus Therapy in Patients with Idiopathic Membranous Nephropathy

Background

Tacrolimus (TAC) is beneficial for patients with idiopathic membranous nephropathy (IMN). It has a narrow therapeutic concentration range and many factors influence TAC blood concentration. CYP3A5 is the most important enzyme in TAC metabolism. The aim of this study was to analyze the effects of CYP3A5 gene polymorphisms on the efficacy and safety of TAC in IMN patients.

Patients and Methods

Patients with IMN who received oral TAC (0.05-0.075mg/kg/day) combined with prednisone (0.5mg/kg/day) from March 2016 to October 2018 were included. The data of clinical characteristics, therapeutic drugs and adverse reactions of patients were collected at baseline and during 24 weeks of treatment. Patients were divided into two groups according to different CYP3A5 genetic polymorphisms. The significant differences in the efficacy and side effects between the two groups were analyzed.

Results

A total of 76 patients who completed follow-up were divided into CYP3A5 nonexpresser (CYP3A5*3/*3) group and CYP3A5 expresser (CYP3A5 *1/*3) group. The significant association between the CYP3A5 phenotype and TAC metabolism was observed. A total of 43 case-times patients exhibited adverse effects. The infection rate in CYP3A5 nonexpresser group (21.95%) was remarkably higher than the rate in CYP3A5 expresser group (5.71%). Blood concentration and C₀/D levels were risk factors for adverse events through logistic regression analysis. There was no statistical difference between the study groups with respect to the efficacy.

Conclusion

Our results demonstrated that CYP3A5 polymorphisms had important guiding roles in the treatment of IMN with tacrolimus. CYP3A5 expressers required higher daily doses of TAC to achieve the target drug concentration, but with fewer side effects. CYP3A5 genetic polymorphism might be used for TAC dosing adjustment to optimize the treatment for patients with IMN.

Identification of Factors Affecting Tacrolimus Trough Levels in Latin American Pediatric Liver Transplant Patients

Tacrolimus is the cornerstone in pediatric liver transplant immunosuppression. Despite close monitoring, fluctuations in tacrolimus blood levels affect safety and efficacy of immunosuppressive treatments. Identifying the factors related to the variability in tacrolimus exposure may be helpful in tailoring the dose. The aim of the present study was to characterize the clinical, pharmacological, and genetic variables associated with systemic tacrolimus exposure in pediatric liver transplant patients. De novo transplant patients with a survival of more than 1 month were considered for inclusion and were genotyped for cytochrome P450 3A5 (CYP3A5). Peritransplant clinical factors and laboratory covariates were recorded retrospectively between 1 month and 2 years after transplant, including alanine aminotransferase (ALT), aspartate aminotransferase, hematocrit, and tacrolimus predose steady-state blood concentrations collected 12 hours after tacrolimus dosing. A linear mixed effect (LME) model was used to assess the association of these factors and the log-transformed tacrolimus dose-normalized trough concentration (logC0/D) levels. Bootstrapping was used to internally validate the final model. External validation was performed in an independent group of patients who matched the original population. The developed LME model described that logC0/D increases with increases in time after transplant (β = 0.019, 95% confidence interval [CI], 0.010-0.028) and ALT values (β = 0.00030, 95% CI, 0.00002-0.00056), whereas logC0/D is significantly lower in graft CYP3A5 expressers compared with nonexpressers (β = -0.349, 95% CI, -0.631 to -0.062). In conclusion, donor CYP3A5 genotype, time after transplant, and ALT values are associated with tacrolimus disposition between 1 month and 2 years after transplant. A better understanding of tacrolimus exposure is essential to minimize the occurrence of an out-of-range therapeutic window that may lead to adverse drug reactions or acute rejection.

Differences in CYP3A genotypes of a liver transplant recipient and the donor liver graft and adjustment of tacrolimus dose

Tacrolimus (Tac) is well established as main immunosuppressant in most immunosuppressive regimens in solid organ transplantation. Due to the narrow therapeutic window, pre dose Tac levels (C0) are monitored in all patients receiving Tac to reach optimal therapeutic levels. Tac is metabolized in the liver and intestine by the cytochrome P450 3A (CYP3A) isoforms CYP3A4 and CYP3A5. We present a case of an African American woman who underwent a liver transplantation in which adequate Tac levels were difficult to accomplish due to differences in cytochrome P450 3A4/5 (CYP3A4/5) polymorphisms of the transplant recipient and the donor liver graft. This case report highlights that genotyping the liver transplant recipient and the donor liver graft might provide data which could be used to predict the tacrolimus metabolism post transplantation.

Recipient ABCB1, donor and recipient CYP3A5 genotypes influence tacrolimus pharmacokinetics in liver transplant cases

BACKGROUND

Effective immunosuppression through optimization of trough levels tacrolimus reduces post-transplant mortality rate in liver transplant cases.

METHODS

Meta-analysis was carried out to evaluate how donor/recipient CYP3A5 (n = 678) and recipient ABCB1 (n = 318) genotypes influence tacrolimus pharmacokinetics till one-month of transplantation.

RESULTS

The donor CYP3A5*3/*3 genotype exhibited higher concentration/dose (C/D) ratio of tacrolimus in week 1 (mean difference: 65.04, 95% CI: 15.30-114.79 ng/ml/mg/kg), week 2 (mean difference: 21.7, 95% CI: 12.6-30.9 ng/ml/mg/kg) and week 4 (mean difference: 43.28, 95% CI: 17.09 - 69.49 ng/ml/mg/kg) compared to *1/*1 and *1/*3 genotypes. The recipient CYP3A5 *3/*3 genotype did not showed significant difference in tacrolimus C/D ratio in week 1 compared to other two genotypes. However, week 2 (mean difference: 44.16, 95% CI: 3.68-84.65 ng/ml/mg/kg) and week 4 (mean difference: 43.74, 95% CI: 12.50-75.00 ng/ml/mg/kg) availability was higher in *3/*3 mutant recipients. However, the recipient ABCB1 3435 C > T polymorphism has no significant influence on tacrolimus pharmacokinetics till one month of transplant.

CONCLUSIONS

The donor and recipient CYP3A5*3 polymorphism influences tacrolimus pharmacokinetics in the first month post-transplantation, whereas the association with recipient ABCB1 3435 C > T is inconclusive.

Survival Time to Biopsy-Proven Acute Rejection and Tacrolimus Adverse Drug Reactions in Pediatric Liver Transplantation

BACKGROUND

Despite advances in surgical procedures and the optimization of immunosuppressive therapies in pediatric liver transplantation, acute rejection (AR) and serious adverse drug reaction (ADR) to tacrolimus still contribute to morbidity and mortality. Identifying risk factors of safety and efficacy parameters may help in optimizing individual immunosuppressive therapies. This study aimed to identify peritransplant predictors of AR and factors related to the risk of ADR to tacrolimus in a large Latin American cohort of pediatric liver transplant patients.

METHODS

We performed a retrospective cohort study in a pediatric liver transplant population (n = 72). Peritransplant variables were collected retrospectively including demographic, clinical, laboratory parameters, genomic (CYP3A5 donor and recipients polymorphism), and tacrolimus trough concentrations (C0) over a 2-year follow-up period. Variability in tacrolimus C0 was calculated using percent coefficient of variation and tortuosity. ADR- and AR-free survival rates were calculated using the Kaplan-Meier method, and risk factors were identified by multivariate Cox regression models.

RESULTS

Cox-proportional hazard models identified that high tortuosity in tacrolimus C0 was associated with an 80% increased risk of AR [hazard ratio (HR), 1.80; 95% confidence interval (CI), 1.01-3.22; P < 0.05], whereas steroid in maintenance doses decreased this risk (HR, 0.56; 95% CI, 0.31-0.99; P < 0.05). Forty-six patients experienced at least one ADR including hypomagnesemia, nephrotoxicity, hypertension, malignancies, and tremor as a first event. Multivariate analysis showed that C0 values 10 days before the event (HR, 1.25; 95% CI, 1.21-1.39; P < 0.0001) and CYP3A5 expresser recipients (HR, 2.05; 95% CI, 1.03-4.06; P < 0.05) were independent predictors of ADR.

CONCLUSIONS

Tacrolimus C0 values, its variability, and CYP3A5 polymorphisms were identified as risk factors of AR and tacrolimus ADR. This knowledge may help to control and reduce their incidence in pediatric liver transplant patients. Prospective studies are important to validate these results.

Effect of CYP3A5*1 expression on tacrolimus required dose for transplant pediatrics: A systematic review and meta-analysis

This systematic review was designed to find out optimal tacrolimus dose in pediatrics according to their CYP3A5*1 genotype by performing meta-analysis. PubMed, Scopus, ISI web of Science, ProQuest, Cochrane library, and clinicaltrail.gov were systematically searched to find studies in which tacrolimus dose and/or blood concentration and/or concentration-to-dose (C/D) ratio were determined in genotype groups of CYP3A5*1 in pediatric population. Data were extracted at 14 time points post-transplantation and meta-analysis of mean and SD was performed. In all, 11 studies including 596 pediatric transplant recipients were entered into systematic review and meta-analysis. Analysis of tacrolimus required dose, blood concentration, and C/D ratio in 14 time points post-transplantation resulted in significant differences between expressers and non-expressers of CYP3A5*1. It seems that 0.06 mg/kg/day higher tacrolimus dose in expressers can produce same blood level as non-expressers. Using results of TDM for tacrolimus dose adjustment, it takes about 1 month for patients to reach stable and optimum tacrolimus blood concentration. This is too long time period which increases the risk of immunosuppressive over/under-dose and drug toxicity or organ rejection. Considering our results, defining genetic profile helps to predict the individual required dose more rapidly, actually before beginning of treatment.

The correlation between the expression of genes involved in drug metabolism and the blood level of tacrolimus in liver transplant receipts

Immunosuppressive medications, such as tacrolimus and mycophenolate mofetil, are commonly used for reducing the risk of organ rejection in receipts of allogeneic organ transplant. The optimal dosages of these drugs are required for preventing rejection and avoiding toxicity to receipts. This study aimed to identify the correlation between the expression profiling of genes involved in drug metabolism and the blood level of tacrolimus in liver transplant receipts. Sixty-four liver transplant receipts were enrolled in this retrospective study. Receipts were divided into low (2–5.9 ng/ml) and high (6–15 ng/ml) tacrolimus groups. Clinical assessment showed that the blood level of tacrolimus was inversely correlated with the liver function evaluated by blood levels of total bilirubin and creatinine. Compared to the high tacrolimus group, expression levels of six cytochrome P450 enzymes, CYP1A1, CYP2B6, CYP3A5, CYP4A11, CYP19A1, and CYP17A1 were significantly higher in the low tacrolimus group. The expression levels of these genes were negatively correlated with the tacrolimus blood level. Enzyme assays showed that CYP3A5 and CYP17A1 exerted direct metabolic effects on tacrolimus and mycophenolate mofetil, respectively. These results support clinical application of this expression profiling of genes in drug metabolism for selection of immunosuppressive medications and optimal dosages for organ transplant receipts.

Influence of donor-recipient CYP3A4/5 genotypes, age and fluconazole on tacrolimus pharmacokinetics in pediatric liver transplantation: a population approach

AIM

To characterize the effect of donor and recipient CYP3A4, CYP3A5 and ABCB1 genotypes as well as relevant patient characteristics on tacrolimus pharmacokinetics in pediatric liver transplantation.

PATIENTS & METHODS

Data from 114 pediatric liver transplant recipients were retrospectively collected during the first 3 months following transplantation. Population pharmacokinetic analysis was performed using nonlinear mixed effects modeling, including characterization of influential covariates.

RESULTS

A two-compartment model with first order elimination best fitted the data. Estimates of apparent volume of the central compartment, intestinal clearance, hepatic clearance and intercompartmental clearance were 79 l, 0.01 l/h, 10.9 l/h and 105 l/h, respectively. Time post-transplantation, recipient age, donor CYP3A5 and CYP3A4 genotypes and fluconazole administration significantly influenced tacrolimus apparent clearance while bodyweight influenced volume of distribution.

CONCLUSION

The proposed model displayed acceptable fitting performances and enabled identification of statistically significant and clinically relevant covariates on tacrolimus pharmacokinetics in the early pediatric post liver transplantation period.

Pharmacogenetics and immunosuppressive drugs

Several candidate genes have been proposed as potential biomarkers for altered pharmacodynamics or pharmacokinetics of immunosuppressive drugs. However, there is usually only limited clinical evidence substantiating the implementation of biomarkers into clinical practice. Testing for thiopurine-S-methyltransferase polymorphisms has been put into routine clinical use quite widely, while the other pharmacogenetic tests are much less frequently used. Relatively good evidence appeared for tacrolimus-related biomarkers; thus, their utilization may be envisaged in the near future. Although the biomarkers related to mycophenolate, sirolimus or other drugs in the therapeutic class may be promising, further research is necessary to provide more robust evidence. The present review focuses on immunosuppressive drugs, excluding biological treatment.