Tacrolimus dose requirement in relation to donor and recipient ABCB1 and CYP3A5 gene polymorphisms in Chinese liver transplant patients.

The aim of this study was to investigate whether the heterogeneity in tacrolimus dose requirement is associated with ABCB1 and CYP3A5 gene polymorphisms in Chinese liver transplant patients during the first month after transplantation. ABCB1 and CYP3A5 genotyping was performed using the polymerase chain reaction restriction sites polymorphism-based procedure in Chinese liver transplant recipients (n = 50) and their corresponding donors (n = 50). Tacrolimus whole-blood trough concentrations were measured by immunoassays on the IMx analyzers (Abbott Diagnostics Laboratories, Abbott-Park, IL). Doses required to achieve target blood concentrations and dose-adjusted trough concentrations (concentration/dose [C/D] ratios) were compared among patients according to allelic status of ABCB1 and CYP3A5. The ABCB1 3435CC was observed in 23 subjects (23%), whereas 64 (64%) carried 3435CT and 13 (13%) carried 3435TT. The CYP3A5*1/*1 was observed in 13 subjects (13%), 50 (50%) carried *1/*3, and 37 (37%) carried*3/*3. The tacrolimus C/D ratios were obviously lower in recipients carrying ABCB1 3435CC genotype. For CYP3A5, recipients who received organs from CYP3A5*3/*3 donors had higher C/D ratios. But the donors' ABCB1 and recipients' CYP3A5 genotype did not affect the recipients' pharmacokinetics. Analysis of the combination of recipients' ABCB1 and donors' CYP3A5 genotypes revealed that the tacrolimus C/D ratios were significantly lower in the ABCB1 3435CC-carrying recipients, regardless of donors' CYP3A5 genotype. In conclusion, our finding suggests that the recipients' ABCB1 and donors' CYP3A5 genotype affect the tacrolimus dose requirements. ABCB1 C3435T polymorphism is a major determinant of tacrolimus trough concentration in Chinese liver transplant recipients, and recipients with 3435CC genotype will require higher dose of tacrolimus.     

The Prognostic Role of CYP Enzyme in Kidney Transplantation: A Single Centre Experience

BackgroundThe main goal of immunosuppressive agents is to reach a balance of preserving allograft function while minimizing adverse effects. The purpose of our research is to corroborate the role of CYP3A enzyme in developing individual medication therapy via measuring medicine levels in patients’ blood samples.MethodsThis retrospective analysis studies 15 kidney transplant recipients. We carried out genotyping (CYP3A5, CYP3A4) after isolating DNA and RNA in patient and donor blood samples; we also determined CYP3A4 messenger RNA expression in case of recipients. Tacrolimus blood levels, dosage, and tacrolimus concentration normalized by dose and the body weight (C₀/D ratio) were evaluated.ResultsIn this research, recipients were divided into 2 groups based on their CYP3A5 genotype. Those who carry CYP3A5*1 allele (*1/*1 or *1/*3) are CYP3A5 expressors, whereas those who are homozygous for the nonfunctional CYP3A5*3 allele are CYP3A5 nonexpressors. There were 3 patients with functioning CYP3A5 enzyme (patients with CYP3A5*1/*3 genotype) where increased tacrolimus metabolism was expected. Our data show that C₀/D ratio of CYP3A5 nonexpressors was around 3 times higher than of CYP3A5 expressors.Looking at CYP3A4 enzyme, we found 1 patient carried CYP3A4*22/*22 genotype where we expected decreased CYP3A4 expression. It is clear that this patient had adequate therapy medication levels (9.50 μg/L) despite having received very low dosage of tacrolimus (0.03 mg/weight/d).ConclusionsOur results confirmed the importance of determining CYP status of recipients after a transplant because individual differences were observed in tacrolimus treatment that were partly influenced by CYP status of recipients.     

Impact of CYP3A5 and MDR1(ABCB1) C3435T polymorphisms on the pharmacokinetics of tacrolimus in renal transplant recipients

OBJECTIVE: The objective of this study was to assess the influence of CYP3A5 and MDR1 genetic polymorphisms on tacrolimus pharmacokinetics in Japanese renal transplant recipients. METHOD: The pharmacokinetic parameters of tacrolimus were calculated in steady-state on day 28 after transplantation. Polymerase chain reaction-restriction fragment length polymorphism and direct sequence methods were used for CYP3A5 and MDR1 polymorphisms, respectively. RESULTS: The dose-adjusted area under the concentration-time curve (AUC0-12) was significantly lower among CYP3A5*1 carriers than those bearing CYP3A5*3/*3. (0.570 +/- 0.105 vs 0.865 +/- 0.343 ng.h/mL per mg/kg, P = .00322). The daily tacrolimus dose per body weight was significantly higher in CYP3A5*1 carriers than those of CYP3A5*3/*3 carriers (0.271 +/- 0.110 vs 0.150 +/- 0.056 mg/kg, P = .00016). In this study, a distinction was made between carriers of CYP3A5*1/*1+*1/*3 and CYP3A5*3/*3 to investigate the influence of the MDR1 C3435T mutation on tacrolimus pharmacokinetics. The MDR1 C3435T polymorphisms did not affect any tacrolimus pharmacokinetic parameter in either group. CONCLUSIONS: Renal transplant recipients who were CYP3A5*1 carriers required a higher dose of tacrolimus than CYP3A5*3/*3, indicating a significantly lower dose-adjusted AUC0-12 of tacrolimus. In contrast, MDR1 C3435T polymorphism was not an important factor in tacrolimus pharmacokinetics.     

Multi-drug resistance gene-1 (MDR-1) haplotypes and the CYP3A5*1 genotype have no influence on ciclosporin dose requirements as assessed by C0 or C2 measurements

The intestinal efflux pump P-glycoprotein (P-gp), the product of the multi-drug resistance-1 (MDR-1) gene, significantly influences the pharmacokinetics of several drugs. Ciclosporin is a substrate for P-gp and is metabolized by cytochrome P450 (CYP) 3A enzymes. P-gp activity is affected by several known single nucleotide polymorphisms (SNPs) and haplotypes. MDR-1 genotypes of SNPs C1236T, G2677T/A and C3435T, as well as haplotypes C-G-C and T-T-T and CYP3A5*1 genotype (predictive of CYP3A5 expression), were related to ciclosporin blood concentrations measured at both 0 and 2 h after drug dosing in 197 stable renal transplant patients. Significant differences (of a magnitude unlikely to be relevant clinically) in dose-normalized blood ciclosporin concentrations were found only between MDR-1 genotypes of the C1236T SNP and between haplotype groups C-G-C and T-T-T in patients that were expressers of CYP3A5. MDR-1 SNPs and haplotypes and also CYP3A5*1 genotype, do not appear to have a major influence on ciclosporin pharmacokinetics.     

Influence of CYP3A5 and MDR1 polymorphisms on tacrolimus concentration in the early stage after renal transplantation

OBJECTIVE: Tacrolimus is an immunosuppressive drug with a narrow therapeutic range and wide interindividual variation in its pharmacokinetics. Cytochrome P450 (CYP) 3A and P-glycoprotein (P-gp, encoded by MDR1) play an important role in the absorption and metabolism of tacrolimus. The objective of this study was to evaluate whether or not CYP3A5*1/*3 or MDR1 C3435T polymorphisms are associated with the tacrolimus concentration per dose. METHODS: CYP3A5 and MDR1 genotypes were determined by polymerase chain reaction followed by restriction fragment length polymorphism analysis in 118 Chinese renal transplant patients receiving tacrolimus. Whole blood trough tacrolimus concentration was measured by enzyme-linked immunosorbent assay and dose-adjusted concentration (ng/mL per mg/kg/d) was calculated at 1 wk, 1 month, and 3 months after transplantation. RESULTS: The dose-adjusted concentration of CYP3A5*1/*1 and *1/*3 patients was significantly lower than *3/*3 patients (32.8 +/- 17.7 and 41.6 +/- 15.8 vs. 102.3 +/- 51.2 at 1 wk; 33.1 +/- 7.5 and 46.4 +/- 12.9 vs. 103 +/- 47.5 at 1 month; 35.3 +/- 20.9 and 59.0 +/- 20.6 vs. 150 +/- 85.3 at 3 months after transplantation respectively). At 1 wk, 46% of the CYP3A5*1 allele carriers had a tacrolimus concentration lower than 5 ng/mL and 77% lower than 8 ng/mL, whereas 20% of the *3/*3 patients had a concentration higher than 20 ng/mL. There was a mild difference between *1/*1 homozygotes and *1/*3 heterozygotes at 1 and 3 months after transplantation. No difference was found among the MDR1 genotypes. CONCLUSION: CYP3A5*1/*3 polymorphisms are associated with tacrolimus pharmacokinetics and dose requirements in renal transplant recipients. Pharmacogenetic methods could be employed prospectively to help initial dose selection and to individualize immunosuppressive therapy.     

Frequencies and Association of CYP3A5 Polymorphism With Tacrolimus Concentration Among Renal Transplant Recipients in Vietnam

BackgroundThis study aims to investigate the frequencies and association of CYP3A5 polymorphism with tacrolimus concentration among renal transplant recipients in Vietnam. Methods. Sixty-eight kidney transplant recipients were included in this study from the department of nephrology and dialysis, Military Hospital 103. Blood samples were collected for monitoring of tacrolimus levels and determination of CYP3A5 genetic polymorphism.ResultsA total of 68 patients studied. The CYP3A5*3*3, CYP3A5*1*3, and CYP3A5*1*1 genotypes were detected in 48 (70.6%), 16 (23.5%), and 4 (5.9%), respectively. Tacrolimus concentrations were much lower in CYP3A5 expressors than in CYP3A5 nonexpressors on the first day, month 1, 3, 6, and 12 (5.98 ± 1.05 vs 6.57 ± 1.03, P = .03; 5.79 ± 1.13 vs 6.82 ± 1.05, P < .001; 4.76 ± 1.48 vs 6.73 ± 1.09, P < .001; 4.29 ± 1.64 vs 6.46 ± 1.23, P < .001; 4.20 ± 1.36 vs 6.04 ± 1.26, P < .001), respectively. Notably, the concentration/dose ratio in the CYP3A5 expressors was lower than in CYP3A5 nonexpressors at time points of follow up (P < .001). However, there were no significant differences in the age, sex, HLA mismatch, type of donors, acute rejection, and creatinine levels at time points between group of CYP3A5 expressors and those of CYP3A5 nonexpressors.ConclusionIn conclusion, this research indicated the significant association of CYP3A5 genetic polymorphism with daily dose and tacrolimus concentrations in renal transplant recipients. This study provided a closer step to individualize the dose of tacrolimus in renal transplant patients in Vietnam.     

肾移植受者CYP3A5基因多态性对术后他克莫司药物代谢的影响

目的 研究肾移植受者细胞色素P450 3A(CMP3A)酶系中的CYP3A5基因多态性对术后他克莫司(Tac)药物代谢的影响,并探讨测定CYP3A5基因型的方法 .方法 选取97例肾移植术后常规使用Tac+吗替麦考酚酯+泼尼松三联免疫抑制方案的受者.用焦磷酸测序法测定受者CYP3A5基因型;用均相酶扩大免疫分析法(EMIT)测定受者全血Tac浓度谷值(C0);比较不同基因型的受者肾移植术后第7天、第14天、1个月、3个月和6个月时的Tac C0,与Tac校正剂量的比值(Tac G0/Tac校正剂量).结果 焦磷酸测序法能够快速准确的测定肾移植受者CYP3A5基因型;97例肾移植受者CYP3A5基因型分别为:CYP3A5+1/*1型17例(17.5%),CYP3A5* 1/*3型35例(36.1%),CYP3A5*3/*3型45例(46.4%).CYP3A5*1/*1型和CYP3A5*1/*3型受者肾移植术后Tac G0/Tac校正剂量均显著低于CYP3A5*3/*3型受者.结论 肾移植受者CYP3A5基因型对Tac药物代谢具有显著的影响.采用焦磷酸法测定肾移植受者CYP3A5基因多态性,有助于确定不同个体移植术后理想的Tac起始剂量,实现Tac个体化用药.     

Influence of CYP3A5 and MDR1(ABCB1) polymorphisms on the pharmacokinetics of tacrolimus in Chinese renal transplant recipients

The aims of this study were to investigate the influence of CYP3A5 and MDR1 genetic polymorphisms on tacrolimus pharmacokinetics in Chinese renal transplant recipients, so as to help rational administration in clinical practice. We calculated pharmacokinetic parameters of tacrolimus from blood concentrations in steady state at day 28. Polymerase chain reaction restriction fragment length polymorphisms were used for CYP3A5 and MDR1 analysis. The results showed that the dose-adjusted area under the concentration time curve (AUC_0-12) and renal clearance showed a significant difference between CYP3A5*1 carriers and the CYP3A5*3/*3 genotype (P < .01). In the following study, a distinction was made between carriers of CYP3A5*1/ vs CYP3A5*3/*3 seeking to investigate the influence of the MDR13435T>C polymorphism on tacrolimus pharmacokinetics. MDR1 3435T>C polymorphism did not affect any tacrolimus pharmacokinetic parameter in either group. Renal transplant recipients who were CYP3A5*1 carriers required a higher dose of tacrolimus than CYP3A5*3/*3, indicating a significantly lower dose-adjusted AUC_0-12 of tacrolimus. In contrast, MDR1 3435T>C polymorphism was not an important factor in tacrolimus pharmacokinetics. Pharmacogenetic methods may be used prospectively to aid dose selection and individualize immunosuppressive therapy.     

CYP3A5 and ABCB1 Polymorphisms and Tacrolimus Pharmacokinetics in Renal Transplant Candidates: Guidelines from an Experimental Study

Genetic polymorphisms in biotransformation enzyme CYP3A5 (6986G > A, CYP3A5*3; 14690A > G, CYP3A5*6) and drug transporter ABCB1 (1236C > T; 2677G > T/A; 3435C > T) are known to influence tacrolimus (Tac) dose requirements and trough blood levels in stable transplant patients. In a group of 19 volunteers selected with relevant genotypes among a list of 221 adult renal transplant candidates, we evaluated whether consideration of CYP3A5 and ABCB1 genetic polymorphisms could explain the interindividual variability in Tac pharmacokinetics after the first administration of a standard dose (0.1 mg/kg body weight twice a day). Lower area under the time versus blood concentration curves (AUC) or lower trough concentrations were observed among CYP3A5 expressors (n = 9) than among nonexpressors (n = 10) using two different analytical methods for Tac determination (liquid chromatography with tandem mass spectrometry (LC-MS/MS) and immunoassay). The median AUC(0-infinity) was 2.6- and 2.1-fold higher in nonexpressors for LC-MS/MS and immunologic methods, respectively. No difference was observed in Tac pharmacokinetic parameters in relation to ABCB1 polymorphisms. In conclusion, our study confirms the very significant effect of CYP3A5 polymorphism early after the first administration of Tac. It also provides a strong argument for a doubling of the loading dose in patients early identified a priori on the transplantation list as possessing at least one CYP3A5*1 allele.     

The Influence of Pharmacogenetics on the Time to Achieve Target Tacrolimus Concentrations after Kidney Transplantation

Previously, we reported that, at 3 months after renal transplantation, individuals with CYP3AP1 genotype CYP3AP1*1 (linked to CYP3A5*1 and strongly associated with expression of CYP3A5) required twofold higher doses of tacrolimus to achieve target blood concentrations than individuals with the genotype CYP3AP1*3/*3 (CYP3A5 nonexpressors). This study assesses the relationship between concentration-controlled dosing during the early period after transplantation, the time to achieve target concentrations and genotype in 178 renal transplant recipients (CYP3AP1*1/*3 or *1/*1: n = 53, CYP3AP1*3/*3: n = 125). Patients with CYP3AP1*1/*3 or *1/*1 had lower mean tacrolimus concentrations during the first week (Median 13.5 vs. 18.5 microg/L, p < 0.0001) with significant delay in achieving target concentrations (15-20 microg/L during week 1, then 10-15 microg/L). More CYP3AP1*3/*3 patients had tacrolimus concentrations above target during the first week (73.6% vs. 35.8%, p = 0.003). There was no difference in the rate of biopsy-confirmed acute rejection, but rejection occurred earlier in the CYP3AP1*1/*3 or *1/*1 group (median 7 d vs. 13 d, p = 0.005). In conclusion, an initial dosing regimen for tacrolimus based on knowledge of the CYP3AP1 genotype and subsequently guided by concentration measurements has the potential to increase the proportion of patients achieving target blood concentrations early after transplantation.     

受者CYP3A5基因多态性对肾移植术后早期血他克莫司浓度的影响

目的 研究细胞色素P450 3A酶系中CYP3A5基因多态性对肾移植术后早期血他克莫司(Tac)浓度的影响.方法 90例肾移植患者均采用Tac、霉酚酸酯和泼尼松预防排斥反应.患者于术后第2～3天开始口服Tac,初始剂量为0.15 mg·kg-1·d-1.用酶联免疫吸附试验法测定血Tac浓度谷值,记录术后1个月内的数据,并据此调整药物剂量,使Tae浓度谷值维持在5～10μg/L.根据患者服用Tac的剂量,计算浓度/剂量比值(C/D),并记录患者每日血肌酐的下降速度.用聚合酶链反应-限制性片段长度多态性法进行CYP3A5基因多态性的检测.结果 CYP3A5基因型为野生型纯合子(*1/*1型)者9例,突变型纯合子(*3/*3型)者41例,突变型杂合子(*1/*3)者40例.*3/*3型者的初次Tac浓度谷值为(9.8±3.1)μg/L,明显高于基因型为*1/*1型和*1/*3型者(P＜0.05,P＜0.05).术后2周内,*3/*3型者的C/D最高,*1/*3型者次之,*1/*1型者最低.前者与后二者相比较,差异有统计学意义(P＜0.05,P＜0.05).术后第1周,*3/*3型者血肌酐的下降速度最快,每天下降(127.4±59.6)μmol/L,高于*1/*3型者和*1/*1型者(P＜0.05,P＜0.05).结论 CYP3A5基因型对肾移植术后1个月内血Tac的浓度谷值有一定影响.     

Tacrolimus Dosing in Pediatric Heart Transplant Patients is Related to CYP3A5 and MDR1 Gene Polymorphisms

Tacrolimus is a substrate for P-glycoprotein (P-gp) and cytochrome (CYP) P4503A. P-gp is encoded by the multiple drug resistance gene MDR1 and CYP3A is the major enzyme responsible for tacrolimus metabolism. Both MDR1 and CYP3A5 genes have multiple single nucleotide polymorphisms. The objective of this study was to evaluate whether the MDR1 exon21 and exon26 polymorphisms and the CYP3A5 polymorphism are associated with tacrolimus disposition in pediatric heart transplant patients. At 3, 6 and 12 months post transplantation, a significant difference in tacrolimus blood level per dose/kg/day was found between the CYP3A5 *1/*3 (CYP3A5 expressor) vs. *3/*3 (nonexpressor) genotypes with the *1/*3 patients requiring a larger tacrolimus dose to maintain the same blood concentration. There were no significant differences in tacrolimus blood level per dose/kg/day between MDR1 exon21 G2677T and exon 26 C3435T at 3 months, but both were found to have a significant association with tacrolimus blood level per dose/kg/day at 6 and 12 months. We conclude that specific genotypes of MDR1 and CYP3A5 in pediatric heart transplant patients require larger tacrolimus doses to maintain their tacrolimus blood concentration, and that this information could be used prospectively to manage patient's immunosuppressive therapy.     

Tacrolimus Therapeutic Drug Monitoring in Stable Kidney Transplantation and Individuation of CYP3A5 Genotype

The posology of tacrolimus (TAC) is usually guided by its therapeutic drug monitoring. Some patients reach target concentrations (CTs) quickly, others more slowly. In a retrospective study, 20 kidney transplant recipients were included (mean age, 50.7 ± 14.1 years; weight 64.0 ± 14.2 kg; patients clinically stable for over a year). We studied cytochrome CYP3A5 genotype, in particular CYP3A5 6986A>G, the most important polymorphism related to the metabolism of TAC (wild genotype CYP3A5 *1 genotype, and CYP3A5 *3 variants). One year after transplantation, the CTs were 5.0 to 8.0 ng/mL. The patients were divided into group A (TAC doses < 6.0 mg/d) and group B (TAC doses > 6.0 mg/d). All were tested for the CYP3A5 gene sequence to characterize their polymorphism. Patients with CYP3A5 *1/*1 and *1/*3 were extensive metabolizers, and those with CYP3A5 *3/*3 were poor metabolizers. In group A and group B, the average TAC doses at the time of therapeutic drug monitoring were 3.0 ± 1.4 ng/mL (0.05 ± 0.03 mg/kg) and 12.8 ± 3.7 ng/mL (0.2 ± 0.1 mg/kg), respectively (P < .001). Group A was the poor metabolizers genotype, while in group B, the extensive metabolizers genotype was present. Patients with the CYP3A5 *1/*1 or *1/*3 genotype required 1.5 to 2 times higher doses than patients *3/*3 to reach CT. This genetic test allows clinicians to know, before the kidney transplant, the patient's TAC metabolism pattern and then to optimize the drug exposure.     

Multidrug resistance gene-1 (MDR-1) haplotypes have a minor influence on tacrolimus dose requirements

P-glycoprotein (P-gp) and the drug metabolizing enzymes have major pharmacokinetic effects. Variability in tacrolimus absorption is influenced by P-gp activity which, in turn, is affected by single nucleotide polymorphisms (SNPs) within the multidrug resistance-1 gene (MDR-1). Tacrolimus dose requirements of 206 stable renal transplant patients were related to MDR-1 genotypes of SNPs C1236T, G2677T/A and C3435T, as well as haplotypes: C-G-C and T-T-T. Lower dose-normalized blood tacrolimus concentrations were achieved for: 2677-GG genotype patients, as compared to 2677-TT, and for 3435-CC patients as compared to 3435-TT patients. There was a small, but significant, difference in dose requirements between haplotypes C-G-C and T-T-T patients, which was not significant when patients were subclassified as producers and non-producers of cytochrome P450 3A5 (CYP3A5). The activities of CYP3A5 and P-gp have been shown to influence bioavailability of several drugs. Our data suggest that MDR-1 haplotypes have a relatively minor association with tacrolimus pharmacokinetics.     

他克莫司代谢率与肾移植术后早期BK病毒感染的关系

目的  探讨他克莫司（FK506）代谢率与肾移植术后早期BK病毒感染的关系。方法  选择解放军第309医院全军器官移植研究所接受同种异体肾移植术的80例受体作为研究对象。对纳入研究的80例受体进行细胞色素P450（CYP）3A5基因多态性检测,根据基因检测结果分为快代谢组（CYP3A5*1/*3基因型和CYP3A5*1/*1基因型,38例）和慢代谢组（CYP3A5*3/*3基因型,42例）。分析80例受体的CYP3A5基因型分布情况;比较两组受体FK506代谢率[浓度/剂量比（C/D值）];比较两组受体术后6个月内BK病毒感染事件[包括BK病毒尿症、BK病毒血症、BK病毒性肾病（BKVN）]的发生率。结果  80例受体中,CYP3A5*1/*1基因型5例（6%）,CYP3A5*1/*3基因型33例（41%）,CYP3A5*3/*3基因型42例（53%）。在80例受体的160个等位基因中,CYP3A5*3等位基因占117个,即CYP3A5*3等位基因变异率为73.1%。快代谢组受体术后1、3、6个月的C/D值均低于相应时间的慢代谢组,差异均有统计学意义（均为P < 0.01）。快代谢组和慢代谢组受体BK病毒尿症发生率分别为37%和29%,BK病毒血症发生率分别为18%和2%,BKVN发生率分别为3%和0,快代谢组BK病毒血症的发生率高于慢代谢组,差异有统计学意义（P=0.02）,两组受体BK病毒尿症和BKVN发生率比较,差异均无统计学意义（均为P > 0.05）。结论  根据CYP3A5基因型学检测结果发现FK506代谢率高的肾移植受体,其术后早期BK病毒血症发生风险高。     

The role of CYP3A5 genotypes in dose requirements of tacrolimus and everolimus after heart transplantation

Kniepeiss D, Renner W, Trummer O, Wagner D, Wasler A, Khoschsorur GAli, Truschnig‐Wilders M, Tscheliessnigg K‐H. The role of CYP3A5 genotypes in dose requirements of tacrolimus and everolimus after heart transplantation.
Clin Transplant 2011: 25: 146–150. © 2009 John Wiley & Sons A/S. Abstract: Background: tacrolimus and everolimus are immunosuppressive drugs metabolized by enzymes of the CYP3A subfamily. A common variant of the CYP3A5 gene, CYP3A5*3, results in strongly decreased CYP3A5 activity and has been shown to influence Tacrolimus blood concentrations, but its role for the pharmacogenetics of Everolimus remains unclear. Aim of the study was to examine the role of CYP3A5*3 variant in tacrolimus and everolimus dose and drug levels after heart transplantation. Methods: The present study comprised 15 patients with Tacrolimus and 30 patients with Everolimus‐based maintenance therapy after heart transplantation. CYP3A5 genotypes were determined and correlated with clinical data. Results: In the Tacrolimus group, 13 subjects were CYP3A5 non‐expressors (*3/*3 genotype) and two were heterozygous expressors (*1/*3 genotype). Average Tacrolimus dose was significantly higher in subjects expressing CYP3A5 compared to non‐expressors. Tacrolimus levels were not significantly different at any point of time. In the Everolimus group, 27 subjects were CYP3A5 non‐expressors (*3/*3 genotype) and three were heterozygous expressors (*1/*3). Neither Everolimus dose nor levels were significantly different between CYP3A5 expressors and non‐expressors at any point of time. Discussion: We conclude that in adult patients after heart transplantation, CYP3A5 genotypes have a strong influence on Tacrolimus, but not Everolimus dose requirement.     

Consequences of Genetic Polymorphisms for Sirolimus Requirements After Renal Transplant in Patients on Primary Sirolimus Therapy

Sirolimus (SRL) is a substrate for cytochromes P-450 3A and P-glycoprotein, the product of the MDR1 gene. We postulated that single nucleotide polymorphisms (SNPs) of these genes could be associated with inter-individual variations in SRL requirements. We then evaluated in 149 renal transplant recipients the effect of polymorphisms CYP3A4*1/*1B, CYP3A5*1/*3 and MDR1 SNPs in exon 12, 21 and 26 on SRL concentration/dose (C/D) ratio 3 months after sirolimus introduction. SRL C/D ratio was significantly higher in patients treated with calcineurin inhibitors. The CYP3A4*1B and CYP3A5*1 alleles were present in 17% and 21% of patients, respectively. When treated with a SRL-based therapy and low-dose steroids, patients carrying the CYP3A4*1B or the CYP3A5*1 alleles required significantly more SRL to achieve adequate blood trough concentrations (p < 0.01 and p < 0.02, respectively). None of the MDR1 SNPs was associated with the SRL concentration/dose ratio. These findings suggest that the variations in SRL requirements are secondary to both genetic and non-genetic factors including pharmacokinetic interactions. In patients with SRL-based therapy, genotyping of the CYP3As genes may help to optimize the SRL management in transplant recipients.     

Effect of CYP3A5 genotype,steroids, and azoles on tacrolimus in a pediatric renal transplant population

Background

Numerous studies have described the impact of cytochrome P450 3A5 (CYP3A5) genotype on Tacrolimus (TAC) exposure. The purpose of this study was to conduct a comprehensive analysis of genetic and non-genetic factors affecting the TAC dose–exposure relationship over the first year post pediatric renal transplant.

Methods

Data were collected retrospectively for the first year post-transplant in pediatric renal transplant patients receiving TAC maintenance immunosuppression. The effect of CYP3A5 genotype (CYP3A5*3 and *6 alleles), age, azoles, and corticosteroids on TAC trough concentration normalized for dose (TAC Co/D ng/ml/mg/kg/day) was assessed using a linear mixed model.

Results

Over time, TAC Co/D was lower in recipients with CYP3A5*1/*3 genotype compared to those with CYP3A5*3/*3 genotype (44.5?±?14.4 vs. 107.6?±?6.4, p?=?0.03), increased in patients >12 years of age compared to?p?=?0.007), and decreased by concomitant corticosteroids (69.5?±?12.7 vs. 89.9?±?20.0, p?=?0.04). The observed increased TAC Co/D in the presence of azoles (271?±?41 vs. 111?±?91, p?=?0.016) could be attributed to clotrimazole.

Conclusions

Multiple factors, including CYP3A5 genotype, and age, influence TAC Co/D in pediatric kidney transplant recipients. Clotrimazole administered as troches also contribute to TAC Co/D variability.     

Influence of CYP3A5 and MDR1 (ABCB1) polymorphisms on the pharmacokinetics of tacrolimus in renal transplant recipients

BACKGROUND: A body-weight-based dose of tacrolimus often results in marked individual diversity of blood drug concentration. Tacrolimus is a substrate for cytochrome P450 (CYP) 3A5 and p-glycoprotein encoded by CYP3A5 and MDR1 (ABCB1), respectively, having multiple single nucleotide polymorphisms. In this study, we genotyped CYP3A5 A6986G, MDR1 G2677(A/T), and C3435T polymorphisms and investigated the association between these polymorphisms and the pharmacokinetics of tacrolimus in renal transplant recipients. METHODS: Thirty consecutive recipients were enrolled in this study. The pharmacokinetics of tacrolimus was analyzed on day 28 after transplant, when the daily dose was adjusted to the target trough level of 10-15 ng/mL. The polymerase chain reaction-restriction fragment length polymorphism and direct sequence method were used for genotyping the CYP3A5 and MDR1 polymorphisms, respectively. RESULTS: The single tacrolimus dose per body weight was significantly higher in CYP3A5 *1 carriers than CYP3A5 *3/*3 carriers (0.143+/-0.050 vs. 0.078+/-0.031 mg/kg, P<0.001). The dose-adjusted trough level and the area under the concentration-time curve (AUC0-12) were significantly lower in CYP3A5 *1 carriers than CYP3A5 *3/*3 carriers (0.040+/-0.014 vs. 0.057+/-0.024 ng/mL/mg/kg, P=0.015 and 0.583+/-0.162 vs. 0.899+/-0.319 ng.hr/mL/mg/kg, P=0.004), respectively. The MDR1 polymorphism was not associated with any pharmacokinetic parameters. CONCLUSIONS: Kidney transplant recipients with the CYP3A5 *1 allele required a higher daily tacrolimus dose compared with those with the CYP3A5 *3/*3 genotype to maintain both the target trough level and AUC0-12, suggesting that this polymorphism is useful for determining the appropriate dose of tacrolimus.     

Influence of Cytochrome P450 3A5 Polymorphisms on Viral Infection Incidence in Kidney Transplant Patients Treated With Tacrolimus

Objective

The aim of this retrospective study was to determine the risk of viral infection in tacrolimus-treated kidney transplant patients.

Methods

We analyzed kidney transplant recipients from 2002 to 2012, reporting all episodes of viral infection. All patients received induction with basiliximab followed by a standard regimen with tacrolimus, steroids, and antimetabolites. Genotypes of cytochrome P450 (CYP) 3A5 were determined with the use of the polymerase chain reaction method.

Results

Fifty-one patients (17 women, 34 men; mean age, 41.6 ± 65.7 years) underwent kidney transplantation with tacrolimus-based immunosuppressive therapy. Thirty patients were diagnosed with 34 viral infections, including herpes simplex, adenovirus, mumps, varicella, and cytomegalovirus (CMV). CMV was the most common viral infection. In multivariate analysis, the CYP3A5*1 allele (P = .049) and negative serology for CMV (P = .018) were factors independently associated with the incidence of viral infection. After excluding CMV infection in CMV-seropositive donor/CMV-seronegative (D+R−) recipients in the analysis, the presence of the CYP3A5*1 allele was found to be an independent risk factor for viral infection. Recipients with the CYP3A5*3/*3 genotype (nonexpressors) showed significantly higher dose-adjusted tacrolimus trough concentrations than patients with the CYP3A5*1 allele (expressors; respectively, 104.6 ± 65.6 vs 52.6 ± 62.3 ng/mL per mg/kg/d).

Conclusions

The CYP3A5*1 allele is associated with viral infection, possibly as a result of higher peak concentrations of tacrolimus. Further analyses, such as area under the concentration-time curve (AUC) for tacrolimus and polymorphisms of drug metabolism enzymes such as CYP3A4 are required to evaluate the influence of CYP3A5 on viral infection in kidney transplantation.