Effects of CYP4F2 Gene Polymorphisms on Warfarin Clearance and Sensitivity in Korean Patients With Mechanical Cardiac Valves

Impact of CYP2C19 gene polymorphisms on warfarin dose requirement: a systematic review and meta-analysis

Background: Various genetic factors influence warfarin maintenance dose. Methods: A literature search was performed on PubMed, Embase and the Cochrane Library, and a meta-analysis to analyze the impact of CYP2C19 polymorphisms on warfarin maintenance dose was conducted. Results: From nine studies encompassing 1393 patients, three CYP2C19 SNPs were identified: rs4244285, rs4986893 and rs3814637. Warfarin maintenance dose was significantly reduced by 10% in individuals with the rs4986893 A allele compared with the GG carriers and was 34%, 16% and 18% lower in patients with rs3814637 TT and CT genotypes and T allele, respectively, than that in CC carriers. No significant dose difference was observed among the rs4244285 genotypes. Conclusion: CYP2C19 rs4986893 and rs3814637 are associated with significantly reduced warfarin dose requirements.

Ethnic Diversity and Warfarin Pharmacogenomics

Warfarin has remained the most commonly prescribed vitamin K oral anticoagulant worldwide since its approval in 1954. Dosing challenges including having a narrow therapeutic window and a wide interpatient variability in dosing requirements have contributed to making it the most studied drug in terms of genotype-phenotype relationships. However, most of these studies have been conducted in Whites or Asians which means the current pharmacogenomics evidence-base does not reflect ethnic diversity. Due to differences in minor allele frequencies of key genetic variants, studies conducted in Whites/Asians may not be applicable to underrepresented populations such as Blacks, Hispanics/Latinos, American Indians/Alaska Natives and Native Hawaiians/other Pacific Islanders. This may exacerbate health inequalities when Whites/Asians have better anticoagulation profiles due to the existence of validated pharmacogenomic dosing algorithms which fail to perform similarly in the underrepresented populations. To examine the extent to which individual races/ethnicities are represented in the existing body of pharmacogenomic evidence, we review evidence pertaining to published pharmacogenomic dosing algorithms, including clinical utility studies, cost-effectiveness studies and clinical implementation guidelines that have been published in the warfarin field.

Genetic Associations With Stable Warfarin Dose Requirements in Han Chinese Patients

ABSTRACT

Warfarin is a commonly prescribed anticoagulant for valvular heart disease that plays an important role in clinical management to prevent thrombotic events. In this study, we aim to perform a comprehensive study to investigate the genetic biomarkers of stable warfarin dose in the Han Chinese population. We performed an integrative study on 211 Han Chinese patients with valvular heart disease. A total of 40 single nucleotide polymorphisms (SNPs) in 10 important genes (CYP2C9, VKORC1, ABCB1, CYP4F2, APOE, PROC, GGCX, EPHX1, CALU, and SETD1A) which are involved in the warfarin metabolic pathway and equilibrium of coagulation and anticoagulation were selected. We applied MassARRAY technology to genotype the 40 SNPs identified in these Han Chinese patients. Our results showed that 13 SNPs on 6 genes (CYP2C9, VKORC1, ABCB1, PROC, EPHX1, and SETD1A) were associated with the individual stable warfarin dose. Two VKORC1 SNPs (rs9934438 and rs2359612) were the strongest genetic factors determining warfarin dose requirements (P = 8 × 10-6 and 9 × 10-6, respectively). Rs4889599 in SETD1A was first reported to be associated with warfarin dose at a significant level of 0.001 in our study (Padjust = 0.040 after Bonferroni correction). We discovered that genetic variants in CYP2C9, VKORC1, ABCB1, PROC, EPHX1, and SETD1A may affect the stable warfarin dose requirement in Han Chinese patients with valvular disease. The discovery of these potential genetic markers will facilitate the development of advanced personalized anticoagulation therapy in Han Chinese patients.

Genotype-guided warfarin dosing may benefit patients with mechanical aortic valve replacements: randomized controlled study

This prospective, single-blind, randomized study was designed to evaluate the effect of genotype-based warfarin dosing compared with standard warfarin dosing in Korean patients with mechanical cardiac valves. Patients were assigned to either the genotype-based dosing group or the standard dosing group using stratified block randomization. The genotype-based dosing equation was adopted from a previous study which included VKORC1 rs9934438, CYP2C9 rs1057910, CYP4F2 rs2108622, and age. Primary outcomes included the percentage of time in the therapeutic range (pTTR): (i) during the first week following initiation of warfarin therapy, (ii) during hospitalization and (iii) until the first outpatient visit. A total of 91 patients were included in the analysis, 42 treated with genotype-based warfarin dosing and 49 treated with standard warfarin dosing. The genotype frequency differences of the three SNPs included in this study (ie, VKORC1, CYP2C9, CYP4F2), between the genotype-based dosing and standard dosing groups were not different. The genotype-based dosing group trended toward higher pTTR when compared with the standard dosing group, although this difference was not statistically significant. In patients with aortic valve replacement, TTR_Traditional and TTR_Rosendaal were significantly higher in the genotype-based dosing group when compared with the standard dosing group during the first week following treatment initiation [ie, 58.5% vs. 38.1% (p = 0.009) and 64.0% vs. 44.6% (p = 0.012), respectively]. Based on the results, the genotype-guided dosing did not offer a significant clinical advantage, but a possible benefit in patients with aortic valve replacement has been suggested.

Effect of CYP4F2, VKORC1, and CYP2C9 in Influencing Coumarin Dose: A Single-Patient Data Meta-Analysis in More Than 15,000 Individuals

The cytochrome P450 (CYP)4F2 gene is known to influence mean coumarin dose. The aim of the present study was to undertake a meta-analysis at the individual patients level to capture the possible effect of ethnicity, gene-gene interaction, or other drugs on the association and to verify if inclusion of CYP4F2*3 variant into dosing algorithms improves the prediction of mean coumarin dose. We asked the authors of our previous meta-analysis (30 articles) and of 38 new articles retrieved by a systematic review to send us individual patients' data. The final collection consists of 15,754 patients split into a derivation and validation cohort. The CYP4F2*3 polymorphism was consistently associated with an increase in mean coumarin dose (+9% (95% confidence interval (CI) 7-10%), with a higher effect in women, in patients taking acenocoumarol, and in white patients. The inclusion of the CYP4F2*3 in dosing algorithms slightly improved the prediction of stable coumarin dose. New pharmacogenetic equations potentially useful for clinical practice were derived.

The pharmacoepigenomics informatics pipeline defines a pathway of novel and known warfarin pharmacogenomics variants

AIM

'Pharmacoepigenomics' methods informed by omics datasets and pre-existing knowledge have yielded discoveries in neuropsychiatric pharmacogenomics. Now we evaluate the generality of these methods by discovering an extended warfarin pharmacogenomics pathway.

MATERIALS & METHODS

We developed the pharmacoepigenomics informatics pipeline, a scalable multi-omics variant screening pipeline for pharmacogenomics, and conducted an experiment in the genomics of warfarin.

RESULTS

We discovered known and novel pharmacogenomics variants and genes, both coding and regulatory, for warfarin response, including adverse events. Such genes and variants cluster in a warfarin response pathway consolidating known and novel warfarin response variants and genes.

CONCLUSION

These results can inform a new warfarin test. The pharmacoepigenomics informatics pipeline may be able to discover new pharmacogenomics markers in other drug-disease systems.

Influence of genetic and non-genetic factors on acenocoumarol maintenance dose requirement in a Tunisian population

PURPOSE

We aimed to study potential variables involved in interindividual variability to acenocoumarol (AC) response in order to establish a pharmacogenetic algorithm (PA) that includes clinical and genetic factors to predict adequate AC dose to stabilize anticoagulation in a cohort of Tunisian patients.

METHODS

Genotyping of the CYP2C9, VKORC1, CYP4F2, and CALU polymorphisms was conducted on 246 patients using PCR-RFLP technique. AC normalized maintenance dose (NMD): ((mean maintenance dose/international normalized ratio (INR)) equilibrium) was calculated. The statistical study was carried out with SPSS V20.

RESULTS

A significant correlation was found between age, BMI, and daily AC dose (r = - 0.397; p < 0.001 and r = 0.215; p = 0.001, respectively). The carriers of mutated alleles CYP2C9*2 or CYP2C9*3 or VKORC1 haplotypes (H1 and H7) were associated with AC hyper-sensibility. After adjustment to potential covariates, these patients presented supra-therapeutic INR during treatment period and needed low AC dose (ORs* = 0.28 [0.06-0.60], p = 0.004; ORs* = 0.12 [0.04-0.05], p < 0.001; ORs* = 0.45 [0.24-0.84], p = 0.01; and ORs* = 0.28 [0.06-0.98], p = 0.049, respectively). However, carriers of VKORC1 haplotypes (H3 and H12) or mutated alleles CYP4F2 (rs2108622) or CALU (rs1043550) tend to resist to treatment, hence long period of therapy initiation, and must be treated with high AC dose (ORs* = 2.67 [81.12-5.91], p = 0.013; ORs* = 8.76 [1.07-76.26], p = 0.019; ORs* = 3.12 [1.01-9.63], p = 0.047; and ORs* = 3.96 [1.41-11.09], p = 0.009, respectively). A final multivariate regression model explained 48.1% of the global interindividual variability in AC dose requirement.

CONCLUSION

The PA demonstrated that VKORC1 and CYP2C9 polymorphisms contribution was more important than clinical factors. Applying the PA would allow dose adjustment to treat patients in a personalized manner.

Influence of NR3C1 and VDR polymorphisms on stable warfarin dose in patients with mechanical cardiac valves

OBJECTIVES

The aim of this study was to evaluate the associations between polymorphisms of VKORC1, CYP2C9, CYP4F2, NR3C1 and VDR genes and stable warfarin doses in Korean patients with mechanical heart valves.

METHODS

Seventeen single-nucleotide polymorphisms (SNPs) in 204 patients with stable warfarin dose were analyzed: VKORC1 (rs9934438), CYP2C9 (rs1057910), CYP4F2 (rs2108622), NR3C1 (rs41423247, rs1800445, rs56149945, rs10052957, rs6198, rs33388, rs6196, and rs244465), and VDR (rs1544410, rs11568820, rs731236, rs757343, rs7975232, and rs2228570). Statistical analyses were conducted to evaluate the associations of gene variations with stable warfarin dose. Number needed to genotype was obtained by calculating the percentage of patients whose predicted dose was at least 20% higher or lower than the actual stable dose.

RESULTS

The combined genotypes of rs7975232 and rs2228570 of the VDR gene revealed a significant association with stable warfarin dose, along with VKORC1, CYP2C9, and CYP4F2 polymorphisms. Patients with the genotype combination GT,TT/CT,CC of VDR rs7975232/rs2228570 required significantly higher stable warfarin dose (5.79±2.02mg) than those with the other genotypic combinations (5.19±1.78mg, p=0.034). Multivariate analysis showed that VDR rs7975232/rs2228570 explained 2.0% of the 47.5% variability in overall warfarin dose. Adding VDR SNP combinations to the base model including non-genetic variables (age, sex, and body weight) and genetic variables (VKORC1 rs9934438, CYP2C9 rs1057910, and CYP4F2 rs2108622) gave a number needed to genotype of 41.

CONCLUSIONS

This study showed that stable warfarin dose is associated with VDR SNPs along with VKORC1, CYP2C9, and CYP4F2 SNPs.

The association between GGCX, miR-133 genetic polymorphisms and warfarin stable dosage in Han Chinese patients with mechanical heart valve replacement

WHAT IS KNOWN AND OBJECTIVE

Warfarin is a widely used anticoagulant with a narrow therapeutic index. Polymorphisms in the VKORC1, CYP2C9 and CYP4F2 genes have been verified to correlate with warfarin stable dosage (WSD). Whether any other genes or variants affect the dosage is unknown. The aim of our study was to investigate the relationship between GGCX, miR-133 variants and the WSD in Han Chinese patients with mechanical heart valve replacement (MHVR).

METHODS

A total of 231 patients were enrolled in the study. Blood samples were collected for genotyping. The average WSD among subjects with different GGCX or miR-133 genotypes was compared. Regression analyses were performed to test for any association of genetic polymorphisms with WSD.

RESULTS AND DISCUSSION

The warfarin dosage in patients with the GGCX rs699664 TT and rs12714145 TT genotypes was 3.77±0.93 (95% CI: 3.35-4.19) mg/d and 3.70±1.00 (95% CI: 3.32-4.09) mg/d, respectively. The GGCX rs699664 and rs12714145 genotypes were significantly associated with WSD (P<.05). But they were ruled out in the multivariate regression analysis. There were no significant differences in the average warfarin stable dosage between subjects with MIR133B rs142410335 wild-type and variant genotypes (P>.05).

WHAT IS NEW AND CONCLUSION

The genotypes of GGCX rs699644 and rs12714145 were significantly associated with WSD (P<.05), but their contributions were not significant after accounting for other factors. MIR133B rs142410335 makes no significant contributions to warfarin stable dosage in Han Chinese patients with MHVR neither in univariate regression nor in multivariate regression analyses.

Pharmacogenetic-guided Warfarin Dosing Algorithm in African-Americans

We aim to develop warfarin dosing algorithm for African-Americans. We explored demographic, clinical, and genetic data from a previously collected cohort of 163 African-American patients with a stable warfarin dose. We explored 2 approaches to develop the algorithm: multiple linear regression and artificial neural network (ANN). The clinical significance of the 2 dosing algorithms was evaluated by calculating the percentage of patients whose predicted dose of warfarin was within 20% of the actual dose. Linear regression model and ANN model predicted the ideal dose in 52% and 48% of the patients, respectively. The mean absolute error using linear regression model was estimated to be 10.8 mg compared with 10.9 mg using ANN. Linear regression and ANN models identified several predictors of warfarin dose including age, weight, CYP2C9 genotype *1/*1, VKORC1 genotype, rs12777823 genotype, rs2108622 genotype, congestive heart failure, and amiodarone use. In conclusion, we developed a warfarin dosing algorithm for African-Americans. The proposed dosing algorithm has the potential to recommend warfarin doses that are close to the appropriate doses. The use of more sophisticated ANN approach did not result in improved predictive performance of the dosing algorithm except for patients of a dose of ≥49 mg/wk.

Impact of the CYP4F2 gene polymorphisms on the warfarin maintenance dose: A systematic review and meta-analysis

Warfarin is an oral anticoagulant with significant interpatient variability in dosage. A large number of studies have confirmed that the individual warfarin dose is mainly affected by the cytochrome P450 complex subunit 2C9 and vitamin K epoxide reductase complex subunit 1. However, the association between cytochrome P450 4F2 (CYP4F2) gene polymorphisms and warfarin dosage in the Asian population remains controversial. To investigate the impact of the CYP4F2 polymorphism rs2108622 (p.V433M) on warfarin dose requirement, a systematic review and meta-analysis were conducted. According to the strict inclusion and exclusion criteria set, a comprehensive literature search was performed, and the studies published before August 5, 2015 were searched for in PubMed, EMBASE and the China National Knowledge Infrastructure databases. The references were checked by two independent reviewers. The association between the warfarin maintenance dose and CYP4F2 polymorphism was analyzed. Twenty-two studies were included in the meta-analysis. Compared with the CYP4F2 genotype CC, carriers of the CT and TT genotypes required a 9 [95% confidence interval (CI): 6.0-13.0] and 20% (95% CI, 13.0-27.0) higher warfarin dose, respectively. In the combined analysis, T carriers (CT+TT) required an 11% (95% CI, 8.0-14.0) higher warfarin dose compared to the CC genotype. In addition, there was a 10% (95% CI, 5.0-15.0) higher warfarin dose in TT carriers compared to the CT genotype (all P<0.05). The results of the meta-analysis suggest that the effects of the CYP4F2 polymorphism on individual warfarin dose have a statistically significant difference, and the effect degree is variable in the subgroups. Further studies are expected to explore whether the pharmacogenetics model including the CYP4F2 polymorphism can strengthen the prediction of warfarin dose.

Effects of NAD(P)H quinone oxidoreductase 1 polymorphisms on stable warfarin doses in Korean patients with mechanical cardiac valves

PURPOSE

NAD(P)H dehydrogenase, encoded by NAD(P)H quinone oxidoreductase 1 (NQO1), is an enzyme that catalyzes the reduction of quinones, including vitamin K. Given its potential role in vitamin K metabolism, this study aimed to investigate the effects of NQO1 polymorphisms on stable warfarin doses.

METHODS

We tested a possible effect of gene polymorphisms on variability in warfarin response using 206 Korean patients with mechanical cardiac valves. Single nucleotide polymorphisms (SNPs) of NQO1 with a minor allele frequency of at least 15% were included. Also, genotypes of vitamin K epoxide reductase complex subunit 1 (VKORC1), cytochrome P450 (CYP) 2C9, CYP4F2, gamma-glutamyl carboxylase (GGCX), and GATA4 were determined.

RESULTS

NQO1 rs1800566 (C>T) and rs10517 (C>T) were significantly associated with stable warfarin doses. Variant homozygote carriers required lower stable warfarin doses than those with wild-type C allele in rs1800566 (4.85 ± 1.61 vs. 5.61 ± 1.94 mg; p = 0.033), whereas patients with wild homozygote required lower doses than those with T allele in rs10517 (5.11 ± 1.73 vs. 5.75 ± 1.98 mg; p = 0.017). Similar results were obtained from stratified analysis using VKORC1 variant homozygote carriers in both SNPs. Multivariate analysis showed that rs10517 (C>T) increased contribution of gene variations to the overall warfarin dose variability from 42.5 to 43.8%.

CONCLUSION

Our results demonstrate that NQO1 gene polymorphisms influence stable warfarin doses in Korean patients.

Effects of Pregnane X Receptor Genetic Polymorphisms on Stable Warfarin Doses

Objective:

Pregnane X receptor (PXR) is a transcriptional regulator of many drug-metabolizing enzymes including cytochrome P450 (CYP) 2C9. The objective of this study was to assess the possible association between PXR single-nucleotide polymorphisms (SNPs) and stable warfarin doses.

Methods:

A total of 201 patients with stable warfarin doses from the EwhA-Severance Treatment (EAST) Group of Warfarin were included in this study. The influence of genetic polymorphisms on stable warfarin doses was investigated by genotyping 11 SNPs, that is, vitamin K epoxide reductase complex 1 (VKORC1) rs9934438, CYP2C9 rs1057910, CYP4F2 rs2108622, constitutive androstane receptor (CAR) rs2501873, hepatocyte nuclear factor 4α (HNF4α) rs3212198, and PXR (rs3814055, rs1403526, rs3732357, rs3732360, rs2276707 and rs2472682). Subgroup analysis was conducted on CYP2C9 wild-type homozygote allele (AA) carriers.

Results:

One PXR SNP of rs2472682 (A>C) exhibited significant association with stable warfarin doses in study population and the subgroup; variant homozygote carriers required significantly lower daily doses of warfarin than those carrying wild allele by about 0.8 mg. Approximate 43.7% of overall interindividual variability in warfarin dose requirement was explained by multivariate regression model. VKORC1, CYP2C9, age, CYP4F2, PXR rs2472682, and CAR/HNF4α rs2501873/rs3212198 accounted for 29.6%, 5.9%, 3.7%, 2.3%, 1.3%, and 0.9% of the variability, respectively. PXR SNP of rs2472682 remained a significant factor in CYP2C9 wild-type homozygote carriers based on univariate and multivariate analyses. The combination of CAR/HNF4α/PXR SNPs of rs2501873/rs3212198/rs2472682 showed about 1 mg dose difference between grouped genotypes in study population and subgroup.

Conclusion:

Our results revealed that PXR could be a determinant of stable warfarin doses.

Effects of single-nucleotide polymorphisms of FMO3 and FMO6 genes on pharmacokinetic characteristics of sulindac sulfide in premature labor

This study aimed to investigate the effects of polymorphisms of the flavin-containing mono-oxygenase 3 (FMO3) and flavin-containing mono-oxygenase 6 (FMO6) genes on the pharmacokinetics of sulindac sulfide, the active metabolite of sulindac, in patients with preterm labor. Ten single-nucleotide polymorphisms (SNPs) were genotyped, and plasma sulindac sulfide concentrations were measured at 0, 1.5, 4, and 10 hours after drug administration. The area under the curve from time 0 to the last sampling time point (AUC(last)) for sulindac sulfide was obtained. The AUC(last) of sulindac sulfide was significantly higher in patients with variant-type homozygotes of FMO3 (rs909530) than those with ancestral alleles or heterozygotes. FMO3 (rs2266780) was in complete linkage disequilibrium with FMO6 (rs7885012), and there was marginal significance between the genotypes (P = 0.049). From multiple linear regression models, FMO3 (rs909530) was found to have significant influence on the AUClast of sulindac sulfide after adjusting for gestational age, weight, and all studied SNPs. The predictive contribution of rs909530 to the variability of sulindac sulfide AUC(last) was 27.0%. In conclusion, the results of this study could help clinicians predict the efficacies and side effects of sulindac in the development of individualized treatment of patients with preterm labor.

Effects of torsemide on pharmacodynamics and pharmacokinetics of warfarin in humans and rats

OBJECTIVES

This study aimed to evaluate the effects of torsemide on warfarin therapy in humans and rats.

METHODS

For the animal study, rats were orally dosed with warfarin (0.13 mg/kg, control group) or warfarin (0.13 mg/kg) with torsemide (2 mg/kg, low dose group and 10 mg/kg, high dose group). The pharmacodynamic response of warfarin was assessed by measuring the international normalized ratio (INR) for 5 consecutive days following drug administration. For the human study, 191 patients on warfarin with mechanical heart valves were followed up retrospectively. The stable dose was calculated as the mean dose in INR levels of 2-3 for 3 consecutive times.

KEY FINDINGS

In the animal study, the INR, maximum plasma concentration (Cmax ) and area under the plasma drug concentration-time curve (AUC0-∞ ) of (S)-warfarin in the high dose group were significantly higher than in other groups (P < 0.05). Compared with the control group, Cmax and AUC0-∞ of (R)-warfarin in the high and low dose groups were higher, whereas the volume of distribution/bioavailability and clearance/bioavailability were significantly lower (P < 0.05). In the univariate analysis of the clinical study, diuretics significantly lowered stable warfarin doses (P = 0.016) (5.07 ± 1.78 mg/day vs 5.77 ± 1.81 mg/day). After controlling confounding variables, the effects of diuretics were found to lower the warfarin dose by 0.464 mg.

CONCLUSIONS

It was concluded that warfarin dose needs to be lowered when it is used concomitantly with diuretics.

Influence of CYP4F2 polymorphisms and plasma vitamin K levels on warfarin sensitivity in Japanese pediatric patients

The aim of this study was to reveal the contribution of CYP4F2, CYP2C9, and VKORC1 genetic polymorphisms on the pharmacokinetics and pharmacodynamics of warfarin in Japanese pediatric patients. Genetic analyses of CYP4F2 (rs2108622), CYP2C9 (*2 and *3), and VKORC1 (-1639G>A) were performed, and plasma unbound warfarin, vitamin K1 (VK1), and menaquinone-4 (MK-4) concentrations were determined in 37 Japanese pediatric patients. The patients with CYP4F2 variant alleles C/T and T/T scored significantly lower values for the warfarin sensitivity index (INR/Cpss) and had significantly higher plasma concentrations of MK-4 than patients with the CYP4F2 allele C/C. Moreover, the plasma MK-4 concentration was negatively correlated with the warfarin sensitivity index. In contrast, the VKORC1 genetic polymorphism did not influence the warfarin sensitivity index. In patients with the CYP2C9 *3 allele, the unbound oral clearance values (normalized to body surface area) for S-warfarin were found to be significantly lower than in patients with the wild-type allele. In conclusion, CYP4F2 genetic polymorphism and plasma MK-4 concentration influence the pharmacodynamics of warfarin, suggesting a mechanism though which CYP4F2 genotype affects warfarin dose.