Drug-drug interaction between diltiazem and tacrolimus in relation to CYP3A5 genotype status in Chinese pediatric patients with nephrotic range proteinuria: a retrospective study

Background

Tacrolimus is widely used to treat pediatric nephrotic range proteinuria (NRP). Diltiazem, a CYP3A4/5 inhibitor, is often administered with tacrolimus, affecting its pharmacokinetic profile. The impact of this combination on tacrolimus exposure, particularly in CYP3A5*3 genetic polymorphism, remains unclear in pediatric NRP patients. This study aimed to evaluate the effects of diltiazem on tacrolimus pharmacokinetics, focusing on the CYP3A5*3 polymorphism.

Methods

We conducted a retrospective clinical study involving pediatric NRP patients, divided into two groups: those receiving tacrolimus with diltiazem and those receiving tacrolimus alone. Propensity score matching (PSM) was used to balance the baseline characteristics between the groups. We compared daily dose-adjusted trough concentrations (C0/D) of tacrolimus in both the original and PSM cohorts. The influence of diltiazem on tacrolimus C0/D, stratified by CYP3A5*3 genetic polymorphism, was assessed in a self-controlled case series study.

Results

Before PSM, the tacrolimus C0/D in patients taking diltiazem was significantly higher compared to those with tacrolimus alone (75.84 vs. 56.86 ng/mL per mg/kg, P = 0.034). This finding persisted after PSM (75.84 vs. 46.93 ng/mL per mg/kg, P= 0.028). In the self-controlled case study, tacrolimus C0/D elevated about twofold (75.84 vs. 34.76 ng/mL per mg/kg, P < 0.001) after diltiazem administration. CYP3A5 expressers (CYP3A5*1/*1 and *1/*3) and CYP3A5 non-expressers (CYP3A5*3/*3) experienced a 1.8-fold and 1.3-fold increase in tacrolimus C0/D when combined with diltiazem, respectively.

Conclusion

Diltiazem significantly increased tacrolimus C0/D, with CYP3A5*3 expressers showing higher elevations than non-expressers among pediatric NRP patients. These findings highlight the importance of personalized tacrolimus therapy based on CYP3A5*3 genotypes in pediatric patients taking diltiazem.

Assessment of omeprazole and famotidine effects on the pharmacokinetics of tacrolimus in patients following kidney transplant-randomized controlled trial

Tacrolimus is metabolized in the liver with the participation of the CYP3A4 and CYP3A5 enzymes. Proton pump inhibitors are used in kidney transplant patients to prevent duodenal and gastric ulcer disease due to glucocorticoids. Omeprazole, unlike famotidine, is a substrate and inhibitor of the enzymes CYP2C19, CYP3A4, CYP3A5. The aim of this study was to compare the impact of omeprazole and famotidine on the pharmacokinetics of tacrolimus. A randomized, non-blinded study involving 22 stabilized adult kidney transplant patients was conducted. Patients received the standard triple immunosuppression regimen and omeprazole 20 mg (n = 10) or famotidine 20 mg (n = 12). The study material consisted of blood samples in which tacrolimus concentrations were determined using the Chemiluminescent Microparticle Immuno Assay method. A single administration of omeprazole increased tacrolimus concentrations at 2 h (day 2) = 11.90 ± 1.59 ng/mL vs. 2 h (day 1 - no omeprazole administration) = 9.40 ± 0.79 ng/mL (p = 0.0443). AUC0-6 amounted to 63.07 ± 19.46 ng × h/mL (day 2) vs. 54.23 ± 10.48 ng × h/mL (day 1), (p = 0.0295). AUC2-6 amounted to 44.32 ± 11.51 ng × h/mL (day 2) vs. 38.68 ± 7.70 ng × h/mL (day 1), (p = 0.0130). Conversely, no significant changes in values of pharmacokinetic parameters were observed for famotidine. Omeprazole significantly increases blood exposure of tacrolimus. The administration of famotidine instead of omeprazole seems safer for patients following kidney transplantation. Clinical Trial Registration: clinicaltrials.gov, identifier NCT05061303.

Developments in pharmacogenetics, pharmacogenomics, and personalized medicine

The development of Pharmacogenetics and Pharmacogenomics in Western Europe is highly relevant in the worldwide scenario. Despite the usually low institutional support, many research groups, composed of basic and clinical researchers, have been actively working for decades in this field. Their contributions made an international impact and paved the way for further studies and pharmacogenomics implementation in clinical practice. In this manuscript, that makes part of the Special Issue entitled Spanish Pharmacology, we present an analysis of the state of the art of Pharmacogenetics and Pharmacogenomics research in Europe, we compare it with the developments in Spain, and we summarize the most salient contributions since 1988 to the present, as well as recent developments in the clinical application of pharmacogenomics knowledge. Finally, we present some considerations on how we could improve translation to clinical practice in this specific scenario.

Safety analysis of co-administering tacrolimus and omeprazole in renal transplant recipients - A review

Tacrolimus is a calcineurin inhibitor used to prevent rejection in allogenic solid organ transplant recipients, which is metabolized in the liver with cytochrome P450 isoforms 3A4 and 3A5 (CYP3A4, CYP3A5). In turn, proton pump inhibitors (PPIs), such as Omeprazole - a substrate and inhibitor of CYP2C19 and CYP3A4 enzymes - are administered to kidney transplant patients in order to prevent duodenal and gastric ulcer disease, associated with the glucocorticoid treatment. Simultaneous administration of both drugs in renal patients has the potential to trigger drug interactions. In fact, there are several mechanisms which may impact the pharmacokinetics of tacrolimus. Inhibition of the CYP2C19 isoform may suppress the metabolism of omeprazole, subsequently altering its metabolic pathway to be metabolized by the CYP3A4 enzyme in order to maintain adequate biotransformation. Therefore, the competition for CYP3A4 may affect the metabolism of tacrolimus and result in its increased plasma concentrations, as well as in adverse reactions. Another mechanism has been related to the genetic polymorphism of the CYP2C19 isoform. Since all these interactions may lead to dysfunctions of the transplanted kidney, it seems significant to eliminate their consequences, for instance via the administration of drugs which are neither substrates, nor inhibitors of the CYP3A4 enzyme. Finally, the nephrotoxic effect of omeprazole should also be accounted for. Bearing in mind the aforementioned observations, the aim of the presented paper was to review the available studies addressing the effect of omeprazole on the pharmacokinetics of tacrolimus.

The impact of cytochrome P450 3A5 genotype on early tacrolimus metabolism and clinical outcomes in lung transplant recipients

Background Tacrolimus (Tac) is the cornerstone of immunosuppressant therapy after lung transplantation (LTx). It shows great inter-individual variability in pharmacokinetics, which could partly be explained by pharmacogenetic factors. Aim We aim to investigate the influence of cytochrome P450 3A5 (CYP3A5) genotypes on early post-LTx Tac metabolism and whether it is affected by concomitant use of azole antifungals. Also, we explored the association between CYP3A5 genotype and clinical outcomes. Method 90 recipients who underwent LTx from 2017 to 2019 were enrolled in the study. The effect of CYP3A5 genotype on Tac metabolism and interaction with azole antifungals were assessed during week 1-4 after transplantation. Associations between CYP3A5 genotype and the incidence of acute kidney injury (AKI), length of hospital stay and mortality were analyzed. ResultsCYP3A5*1 carriers had lower dose adjusted concentration (C/D) than CYP3A5*3/*3 group at all time points (p < 0.05). The dose ratio of CYP3A5*1 carriers to CYP3A5*3/*3 was between 1.3 and 2.4 when comparable concentrations were reached. Use of azole antifungals did not blunt the effect of CYP3A5 genotypes on Tac metabolism. Logistic regression showed Tac concentration ≥ 7.5 ng/mL at week 1 was associated with higher incidence of AKI. No statistically significant difference was found between CYP3A5 genotypes and the length of hospital stay. Kaplan-Meier analysis showed no statistically significant difference between 30-day or 1-year mortality and CYP3A5 genotype. Conclusion CYP3A5 genotype could affect Tac metabolism early after LTx. However, it had no influence on the incidence of AKI, length of hospital stay and mortality.

CYP3A5 Genotype-Dependent Drug-Drug Interaction Between Tacrolimus and Nifedipine in Chinese Renal Transplant Patients

Purpose: The drug-drug interactions (DDIs) of tacrolimus greatly contributed to pharmacokinetic variability. Nifedipine, frequently prescribed for hypertension, is a competitive CYP3A5 inhibitor which can inhibit tacrolimus metabolism. The objective of this study was to investigate whether CYP3A5 genotype could influence tacrolimus-nifedipine DDI in Chinese renal transplant patients.

Method: All renal transplant patients were divided into CYP3A5*3/*3 homozygotes (group I) and CYP3A5*1 allele carriers (CYP3A5*1/*1 + CYP3A5*1/*3) (group II). Each group was subdivided into patients taking tacrolimus co-administered with nifedipine (CONF) and that administrated with tacrolimus alone (Controls). Tacrolimus trough concentrations (C₀) were measured using high performance liquid chromatography. A retrospective analysis compared tacrolimus dose (D)-corrected trough concentrations (C₀) (C₀/D) between CONF and Controls in group I and II, respectively. At the same time, a multivariate line regression analysis was made to evaluate the effect of variates on C₀/D.

Results: In this study, a significant DDI between tacrolimus and nifedipine with respect to the CYP3A5*3 polymorphism was confirmed. In group I (n = 43), the C₀/D of CONF was significantly higher than in Controls [225.2 ± 66.3 vs. 155.1 ± 34.6 ng/ml/(mg/kg); p = 0.002]. However, this difference was not detected in group II (n = 27) (p = 0.216). The co-administrated nifedipine and CYP3A5*3/*3 homozygotes significantly increased tacrolimus concentrations in multivariate line regression analysis.

Discussion: A CYP3A5 genotype-dependent DDI was found between tacrolimus and nifedipine. Therefore, personalized therapy accounting for CYP3A5 genotype detection as well as therapeutic drug monitoring are necessary for renal transplant patients when treating with tacrolimus and nifedipine.

A Machine Learning-Based Identification of Genes Affecting the Pharmacokinetics of Tacrolimus Using the DMETTM Plus Platform

Tacrolimus is an immunosuppressive drug with a narrow therapeutic index and larger interindividual variability. We identified genetic variants to predict tacrolimus exposure in healthy Korean males using machine learning algorithms such as decision tree, random forest, and least absolute shrinkage and selection operator (LASSO) regression. rs776746 (CYP3A5) and rs1137115 (CYP2A6) are single nucleotide polymorphisms (SNPs) that can affect exposure to tacrolimus. A decision tree, when coupled with random forest analysis, is an efficient tool for predicting the exposure to tacrolimus based on genotype. These tools are helpful to determine an individualized dose of tacrolimus.

Association of Genetic Variants in CYP3A4, CYP3A5, CYP2C8, and CYP2C19 with Tacrolimus Pharmacokinetics in Renal Transplant Recipients

BACKGROUND

Our study aimed to investigate the pharmacogenetics of cytochrome P3A4 (CYP3A4), CYP3A5, CYP2C8, and CYP2C19 and their influence on TAC Pharmacokinetics (PKs) in short-term renal transplant recipients.

METHODS

A total of 105 renal transplant recipients were enrolled. Target Sequencing (TS) based on next-generation sequencing technology was used to detect all exons, exon/intron boundaries, and flanking regions of CYP3A4, CYP3A5, CYP2C8, and CYP2C19. After adjustment of Minor Allele Frequencies (MAF) and Hardy-Weinberg Equilibrium (HWE) analysis, tagger Single-nucleotide Polymorphisms (SNPs) and haplotypes were identified. Influence of tagger SNPs on TAC concentrations was analyzed.

RESULTS

A total of 94 SNPs were identified in TS analysis. Nine tagger SNPs were selected, and two SNPs (rs15524 and rs4646453) were noted to be significantly associated with TAC PKs in short-term post-transplant follow-up. Measurement time points of TAC, body mass index (BMI), usage of sirolimus, and incidence of Delayed Graft Function (DGF) were observed to be significantly associated with TAC PKs. Three haplotypes were identified, and rs15524-rs4646453 was found to remarkably contribute to TAC PKs. Recipients carrying H2/H2 (GG-AA) haplotype also showed significantly high weight- and dose-adjusted TAC concentrations in posttransplant periods of 7, 14, and 30 days and 3 and 6 months.

CONCLUSIONS

Two tagger SNPs, namely, rs15524 and rs4646453, are significantly related to the variability of TAC disposition, and TAC measurement time points, BMI, usage of sirolimus, and incidence of DGF contribute to this influence. Recipients carrying H2/H2 (GG-AA) haplotype in rs15524-rs4646453 may require a low dosage of TAC during 1-year follow-up posttransplant.

Biomarkers for individualized dosage adjustments in immunosuppressive therapy using calcineurin inhibitors after organ transplantation

Calcineurin inhibitors (CNIs), such as cyclosporine A and tacrolimus, are widely used immunosuppressive agents for the prevention of post-transplantation rejection and have improved 1-year graft survival rates by up to 90%. However, CNIs can induce severe reactions, such as acute or chronic allograft nephropathy, hypertension, and neurotoxicity. Because CNIs have varied bioavailabilities, narrow therapeutic ranges, and individual propensities for toxic effects, therapeutic drug monitoring is necessary for all CNIs. Identifying the genetic polymorphisms in drug-metabolizing enzymes will help to determine personalized dosage regimens for CNIs, as CNIs are substrates for CYP3A5 and P-glycoprotein (P-gp, MDR1). CNIs are often concomitantly administered with voriconazole or proton pump inhibitors (PPIs), giving rise to drug interaction problems. Voriconazole and PPIs can increase the blood concentrations of CNIs, and both are primarily metabolized by CYP2C19. Thus, it is expected that interactions between CNIs and voriconazole or PPI would be affected by CYP2C19 and CYP3A5 polymorphisms. CNI-induced acute kidney injury (AKI) is a serious complication of transplantations. Neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule 1 (KIM-1) are noninvasive urinary biomarkers that are believed to be highly sensitive to CNI-induced AKI. In this article, we review the adverse events and pharmacokinetics of CNIs and the biomarkers related to CNIs, including CYP3A5, CYP2C19, MDR1, NGAL, and KIM-1. We hope that these data will help to identify the optimal biomarkers for monitoring CNI-based immunosuppressive therapy after organ transplantation.

SNPs affecting the clinical outcomes of regularly used immunosuppressants

Recent studies have suggested that genomic diversity may play a key role in different clinical outcomes, and the importance of SNPs is becoming increasingly clear. In this article, we summarize the bioactivity of SNPs that may affect the sensitivity to or possibility of drug reactions that occur among the signaling pathways of regularly used immunosuppressants, such as glucocorticoids, azathioprine, tacrolimus, mycophenolate mofetil, cyclophosphamide and methotrexate. The development of bioinformatics, including machine learning models, has enabled prediction of the proper immunosuppressant dosage with minimal adverse drug reactions for patients after organ transplantation or for those with autoimmune diseases. This article provides a theoretical basis for the personalized use of immunosuppressants in the future.

Attempted validation of 44 reported SNPs associated with tacrolimus troughs in a cohort of kidney allograft recipients

AIM

Multiple genetic variants have been associated with variation in tacrolimus (TAC) trough concentrations. Unfortunately, additional studies do not confirm these associations, leading one to question if a reported association is accurate and reliable. We attempted to validate 44 published variants associated with TAC trough concentrations.

MATERIALS & METHODS

Genotypes of the variants in our cohort of 1923 kidney allograft recipients were associated with TAC trough concentrations.

RESULTS

Only variants in CYP3A4 and CYP3A5 were significantly associated with variation in TAC trough concentrations in our validation.

CONCLUSION

There is no evidence that common variants outside the CYP3A4 and CYP3A5 loci are associated with variation in TAC trough concentrations. In the future rare variants may be important and identified using DNA sequencing.

Genome-wide association study identifies the common variants in CYP3A4 and CYP3A5 responsible for variation in tacrolimus trough concentration in Caucasian kidney transplant recipients

The immunosuppressant tacrolimus (TAC) is metabolized by both cytochrome P450 3A4 (CYP3A4) and CYP3A5 enzymes. It is common for European Americans (EA) to carry two CYP3A5 loss-of-function (LoF) variants that profoundly reduces TAC metabolism. Despite having two LoF alleles, there is still considerable variability in TAC troughs and identifying additional variants in genes outside of the CYP3A5 gene could provide insight into this variability. We analyzed TAC trough concentrations in 1345 adult EA recipients with two CYP3A5 LoF alleles in a genome-wide association study. Only CYP3A4*22 was identified and no additional variants were genome-wide significant. Additional high allele frequency genetic variants with strong genetic effects associated with TAC trough variability are unlikely to be associated with TAC variation in the EA population. These data suggest that low allele frequency variants, identified by DNA sequencing, should be evaluated and may identify additional variants that contribute to TAC pharmacokinetic variability.

Impact of Single Nucleotide Polymorphisms (SNPs) on Immunosuppressive Therapy in Lung Transplantation

Lung transplant patients present important variability in immunosuppressant blood concentrations during the first months after transplantation. Pharmacogenetics could explain part of this interindividual variability. We evaluated SNPs in genes that have previously shown correlations in other kinds of solid organ transplantation, namely ABCB1 and CYP3A5 genes with tacrolimus (Tac) and ABCC2, UGT1A9 and SLCO1B1 genes with mycophenolic acid (MPA), during the first six months after lung transplantation (51 patients). The genotype was correlated to the trough blood drug concentrations corrected for dose and body weight (C0/Dc). The ABCB1 variant in rs1045642 was associated with significantly higher Tac concentration, at six months post-transplantation (CT vs. CC). In the MPA analysis, CT patients in ABCC2 rs3740066 presented significantly lower blood concentrations than CC or TT, three months after transplantation. Other tendencies, confirming previously expected results, were found associated with the rest of studied SNPs. An interesting trend was recorded for the incidence of acute rejection according to NOD2/CARD15 rs2066844 (CT: 27.9%; CC: 12.5%). Relevant SNPs related to Tac and MPA in other solid organ transplants also seem to be related to the efficacy and safety of treatment in the complex setting of lung transplantation.

Association of SNPs with the efficacy and safety of immunosuppressant therapy after heart transplantation

Aim: Studying the possible influence of SNPs on efficacy and safety of calcineurin inhibitors upon heart transplantation. Materials & methods: In 60 heart transplant patients treated with tacrolimus or cyclosporine, we studied a panel of 36 SNPs correlated with a series of clinical parameters during the first post-transplantation year. Results: The presence of serious infections was correlated to ABCB1 rs1128503 (p = 0.012), CC genotype reduced the probability of infections being also associated with lower blood cyclosporine concentrations. Lower renal function levels were found in patients with rs9282564 AG (p = 0.003), related to higher blood cyclosporine blood levels. A tendency toward increased graft rejection (p = 0.05) was correlated to rs2066844 CC in NOD2/CARD15, a gene related to lymphocyte activation. Conclusion: Pharmacogenetics can help identify patients at increased risk of clinical complications.

Original submitted 30 January 2015; revision submitted 27 March 2015

Genotyping of CYP2C19 polymorphisms and its clinical validation in the ethnic Arab population

OBJECTIVES

The drug-metabolizing enzymes and transporters (DMET) Plus microarray and x-Tag assays have recently been developed for genotyping individuals in personalized medicine. Furthermore, the cytochrome 450-2C19 (CYP2C19) is a key metabolic enzyme encoded by a polymorphic gene commonly associated with diminished metabolism and variable clinical responses to several drugs in an ethnicity-dependent fashion. Therefore, validation of these clinical procedures as well as knowledge of the ethnic-specific incidences of these gene variants is prerequisite for determining their clinical relevance in any given population.

METHODS

We determined the distribution of familiar CYP2C19 variants by the DMET Plus chip in 600 candidates and replicated the findings by the Affymetrix Axiom Genome-Wide Asian Structure Identification Array in 5413 individuals, all Saudis of ethic Arab origin. We then tested the robustness of employing the Luminex xMAP system clinically by comparing the results of genotyping 500 Saudi individuals visiting the Blood Bank of our institution with the findings of the two platforms.

KEY FINDINGS

The DMET Plus genotyping revealed that eight of the CYP2C19 variants showed some changes. Thereby, the CYP2C19*17 exhibited the highest minor allele frequency (MAF) of 0.256, followed by the CYP2C19_801 (frequency = 0.055). Six other variants, including the CYP2C19*3, showed MAF in the range of 0.001-0.002. We replicated the frequencies of the CYP2C19*17 and CYP2C19*3, and additionally established that of the CYP2C19*2 (0.099) using the Axiom platform. The xTag genotyping also indicated that 0.834 of the 500 Saudi individuals were extensive metabolizers (*1/*1), 0.158 carried the *1/*2 genotype, 0.01% carried *2/*2 (poor metabolizers) and one each (0.2%) harboured the *1/*8, *2/*3 (intermediate metabolizers) and *8/*8 (poor metabolizers) genotypes.

CONCLUSIONS

The results showed reproducible genotyping of the CYP2C19 variants in the Saudi Arab population using two Affymetrix platforms and phenotyping using the Luminex xTag assay. The prevalence of two clinically relevant genotypes (CYP2C19*2 and CYP2C19*3) were similar to other ethnic groups, while that of the CYP2C19*17 was comparably higher.

Associations of HSD11B1 polymorphisms with tacrolimus concentrations in Chinese renal transplant recipients with prednisone combined therapy

Tacrolimus requires close therapeutic drug monitoring because of its narrow therapeutic index and marked interindividual pharmacokinetic variation. In this study, we investigated the associations of polymorphisms in the gene encoding 11β-hydroxysteroid dehydrogenase type 1 (HSD11B1) with tacrolimus concentrations in Chinese renal transplant recipients during the early posttransplantation stage. A total of 258 renal transplant recipients receiving tacrolimus with prednisone (30 mg) combined therapy were genotyped for HSD11B1 rs846908, rs846910, rs4844880, and CYP3A5*3 polymorphisms. Tacrolimus trough concentrations were determined on days 6-9 after transplantation, measured by a chemiluminescent microparticle immunoassay. Among the CYP3A5 expressers, the dose-adjusted trough concentration (C0/D) of tacrolimus in HSD11B1 rs846908 AA homozygous individuals was considerably lower than found in GG+GA carriers [56.2 (23.9-86.6) versus 76.7 (12.6-220.0) (ng/ml)/(mg/kg), P = 0.0204]; HSD11B1 rs846910 AA homozygotes had a lower tacrolimus C0/D compared with GG+GA carriers [51.2 (23.9-86.6) versus 76.3 (12.6-220.0) (ng/ml)/(mg/kg), P = 0.0367]; carriers with the HSD11B1 rs4844880 AA genotype had a significantly lower tacrolimus C0/D with respect to carriers of TT+TA genotypes [61.3 (23.9-97.5) versus 77.2 (12.6-220.0) (ng/ml)/(mg/kg), P = 0.0002]; the HSD11B1 AA-AA-AA haplotype carriers had a lower tacrolimus C0/D than noncarriers [51.2 (23.9-86.6) versus 76.3 (12.6-220.0) (ng/ml)/(mg/kg), P = 0.0367]. These findings illustrate that the HSD11B1 genotypes are closely correlated with tacrolimus trough concentrations, suggesting that these polymorphisms may be useful for safer dosing of tacrolimus.

Pediatric transplantation: opportunities for pharmacogenomics and genomics

Heterogeneity is the rule among pediatric heart transplant recipients. Patients vary in age, size, organ maturity, immune system maturity and underlying disease etiology, which can all influence post-transplant outcomes. Overall, the survival of pediatric transplant recipients continues to improve and the goal remains long-term survival of the primary graft and mitigation of long-term complications and adverse events. The evolving fields of pharmacogenomics and genomics have the potential to revolutionize and personalize the care of pediatric transplant recipients, and although clinical validation in a pediatric cohort is lacking, many of these technologies are becoming more readily available. We discuss genotype-guided dosing of immunosuppressant medications and other commonly used medications after transplantation, the influence of donor and recipient genotype on risk of post-transplant complications, genotype-guided selection of therapies to treat complications, and the use of next-generation sequencing for noninvasive detection of graft rejection.