Pharmacogenetics and oral antithrombotic drugs

Genetic polymorphisms and major bleeding risk during vitamin K antagonists treatment: The BLEEDS case-cohort

BACKGROUND

Major bleeding occurs annually in 1%-3% of patients on vitamin K antagonists (VKAs), despite close monitoring. Genetic variants in proteins involved in VKA response may affect this risk.

AIM

To determine the association of genetic variants (cytochrome P450 enzymes 2C9 [CYP2C9] and 4F2 [CYP4F2], gamma-glutamyl carboxylase [GGCX]) with major bleeding in VKA users, separately and combined, including vitamin K epoxide reductase complex subunit-1 (VKORC1).

METHODS

A case-cohort study was established within the BLEEDS cohort, which includes 16,570 patients who initiated VKAs between 2012 and 2014. We selected all 326 major bleeding cases that occurred during 17,613 years of follow-up and a random subcohort of 978 patients. We determined variants in CYP2C9, CYP4F2, GGCX, VKORC1 and evaluated the interaction between variant genotypes. Hazard ratios for major bleeding with 95% confidence intervals (95% CI) were estimated by weighted Cox regression.

RESULTS

Genotype was determined in 256 cases and 783 subcohort members. Phenprocoumon was the most prescribed VKA for both cases and the subcohort (78% and 75%, respectively). Patients with major bleeding were slightly older than subcohort patients. CYP4F2-TT carriership was associated with a 1.6-fold (95% CI 0.9-2.8) increased risk of major bleeding compared with CC-alleles, albeit not statistically significant. For the CYP2C9 and GGCX variants instead, the major bleeding risk was around unity. Carrying at least two variant genotypes in CYP2C9 (poor metabolizer), CYP4F2-TT, and VKORC1-AA was associated with a 4.0-fold (95%CI 1.4-11.4) increased risk, while carriers of both CYP4F2-TT and VKORC1-AA had a particularly increased major bleeding risk (hazard ratio 6.7, 95% CI 1.5-29.8) compared with carriers of CC alleles in CYP4F2 and GG in VKORC1. However, the number of major bleeding cases in carriers of multiple variants was few (8 and 5 patients, respectively).

CONCLUSIONS

CYP4F2 polymorphism was associated with major bleeding, especially in combination with VKORC1 genetic variants. These variants could be considered to further personalize anticoagulant treatment.

Application of Advanced Technologies-Nanotechnology, Genomics Technology, and 3D Printing Technology-In Precision Anesthesia: A Comprehensive Narrative Review

There has been increasing interest and rapid developments in precision medicine, which is a new medical concept and model based on individualized medicine with the joint application of genomics, bioinformatics engineering, and big data science. By applying numerous emerging medical frontier technologies, precision medicine could allow individualized and precise treatment for specific diseases and patients. This article reviews the application and progress of advanced technologies in the anesthesiology field, in which nanotechnology and genomics can provide more personalized anesthesia protocols, while 3D printing can yield more patient-friendly anesthesia supplies and technical training materials to improve the accuracy and efficiency of decision-making in anesthesiology. The objective of this manuscript is to analyze the recent scientific evidence on the application of nanotechnology in anesthesiology. It specifically focuses on nanomedicine, precision medicine, and clinical anesthesia. In addition, it also includes genomics and 3D printing. By studying the current research and advancements in these advanced technologies, this review aims to provide a deeper understanding of the potential impact of these advanced technologies on improving anesthesia techniques, personalized pain management, and advancing precision medicine in the field of anesthesia.

Clinical significance of the series of CYP2C9*non3 variants, an unignorable predictor of warfarin sensitivity in Chinese population

Backgrounds

Gene polymorphisms are critical for variations in warfarin dose. To date, more than 70 CYP2C9 alleles have been identified. This study was designed to clarify the clinical significance of CYP2C9*non-3 variants to warfarin sensitivity in Chinese Han patients.

Methods

The entire CYP2C9 gene region was sequenced in 1,993 individuals, and clinical data and VKORC1 genotypes were collected from 986 patients with atrial fibrillation treated with warfarin. The SKAT-O method was used to analyze the effects of CYP2C9*non-3 variants on warfarin sensitivity.

Results

A total of 20 CYP2C9 variants were identified, of which four were novel. Carriers with CYP2C9*non-3 variants may have lower warfarin dose requirements, and similar to CYP2C9*3, CYP2C9*non-3 variants are clearly relevant to warfarin-sensitive and highly sensitive responders.

Conclusion

Our results showed that, besides CYP2C9*3, the series of CYP2C9*non-3 variants is an unignorable predictor for warfarin sensitivity in Chinese population. From a safety consideration, people carried such variants may need a preferred choice of NOACs when they started anticoagulation therapy.

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.

New insights into vitamin K biology with relevance to cancer

Phylloquinone (vitamin K1) and menaquinones (vitamin K2 family) are essential for post-translational γ-carboxylation of a small number of proteins, including clotting factors. These modified proteins have now been implicated in diverse physiological and pathological processes including cancer. Vitamin K intake has been inversely associated with cancer incidence and mortality in observational studies. Newly discovered functions of vitamin K in cancer cells include activation of the steroid and xenobiotic receptor (SXR) and regulation of oxidative stress, apoptosis, and autophagy. We provide an update of vitamin K biology, non-canonical mechanisms of vitamin K actions, the potential functions of vitamin K-dependent proteins in cancer, and observational trials on vitamin K intake and cancer.

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.

Pharmacogenetics of Anticoagulation and Clinical Events in Warfarin-Treated Patients: A Register-Based Cohort Study with Biobank Data and National Health Registries in Finland

PURPOSE

To assess the association between VKORC1 and CYP2C9 variants and the incidence of adverse drug reactions in warfarin-treated patients in a real-world setting.

MATERIALS AND METHODS

This was a register-based cohort study (PreMed) linking data from Finnish biobanks, national health registries and patient records between January 1st 2007 and June 30th 2018. The inclusion criteria were: 1) ≥18 years of age, 2) CYP2C9 and VKORC1 genotype information available, 3) a diagnosis of a cardiovascular disease, 4) at least one warfarin purchase, 5) regular INR tests. Eligible individuals were divided into two warfarin sensitivity groups; normal responders, and sensitive and highly sensitive responders based on their VKORC1 and CYP2C9 genotypes. The incidences of clinical events were compared between the groups using Cox regression models.

RESULTS

The cohort consisted of 2508 participants (45% women, mean age of 69 years), of whom 65% were categorized as normal responders and 35% sensitive or highly sensitive responders. Compared to normal responders, sensitive and highly sensitive responders had fewer INR tests below 2 (median: 33.3% vs 43.8%, 95% CI: -13.3%, -10.0%) and more above 3 (median: 18.2% vs 6.7%, 95% Cl: 8.3%, 10.8%). The incidence (per 100 patient-years) of bleeding outcomes was 5.4 for normal responders and 5.6 for the sensitive and highly sensitive responder group (HR=1.03, 95% CI: 0.74, 1.44). The incidence of thromboembolic outcomes was 4.9 and 7.8, respectively (HR=1.48, 95% CI: 1.08, 2.03).

CONCLUSION

In a real-world setting, genetically sensitive and highly sensitive responders to warfarin had more high INR tests and required a lower daily dose of warfarin than normal responders. However, the risk for bleeding events was not increased in sensitive and highly sensitive responders. Interestingly, the risk of thromboembolic outcomes was lower in normal responders compared to the sensitive and highly sensitive responders.

TRIAL REGISTRATION

NCT04001166.

Warfarin dosing algorithms: A systematic review

Aims

Numerous algorithms have been developed to guide warfarin dosing and improve clinical outcomes. We reviewed the algorithms available for various populations and the covariates, performances and risk of bias of these algorithms.

Methods

We systematically searched MEDLINE up to 20 May 2020 and selected studies describing the development, external validation or clinical utility of a multivariable warfarin dosing algorithm. Two investigators conducted data extraction and quality assessment.

Results

Of 10 035 screened records, 266 articles were included in the review, describing the development of 433 dosing algorithms, 481 external validations and 52 clinical utility assessments. Most developed algorithms were for dose initiation (86%), developed by multiple linear regression (65%) and mostly applicable to Asians (49%) or Whites (43%). The most common demographic/clinical/environmental covariates were age (included in 401 algorithms), concomitant medications (270 algorithms) and weight (229 algorithms) while CYP2C9 (329 algorithms), VKORC1 (319 algorithms) and CYP4F2 (92 algorithms) variants were the most common genetic covariates. Only 26% and 7% algorithms were externally validated and evaluated for clinical utility, respectively, with <2% of algorithm developments and external validations being rated as having a low risk of bias.

Conclusion

Most warfarin dosing algorithms have been developed in Asians and Whites and may not be applicable to under‐served populations. Few algorithms have been externally validated, assessed for clinical utility, and/or have a low risk of bias which makes them unreliable for clinical use. Algorithm development and assessment should follow current methodological recommendations to improve reliability and applicability, and under‐represented populations should be prioritized.

Role of Whole Plant Extract of Nelumbo nucifera Gaertn in the Treatment of Thrombolysis

AIM

This study aims to find out the components responsible for the antithrombotic activity of Nelumbo nucifera.

MATERIAL AND METHODS

Petroleum ether, chloroform and hydroalcoholic extracts of whole plant of Nelumbo nucifera (Lotus) were prepared and assessed for its thrombolytic, anti-platelet aggregation activity and bleeding time. The extracts were further analyzed through HPTLC and GC-MS. Statistical analysis was conducted through ANOVA trailed by Tukey's multiple comparison test test.

RESULTS

Hydroalcoholic extract showed the highest activity at the concentration of 400µg/ml in thrombolytic assay (42.03 ± 5.76), anti-platelet aggregation assay (57.93 ± 1.68) and bleeding time (70.17 ± 2.16) in comparison to clopodigrel (33.76 ± 3.43), aspirin (66.55 ± 1.86) and aspirin (93.85 ± 2.75) at the concentration of 100 µg/ml respectively. 25 peaks were identified through GC-MS, out of which, ferulic acid (14.2µ/g) and quercetin (5.4 µ/g) are active chemical compounds. HPTLC showed different chromatograms in hydroalcoholic extracts like (1) chlorogenic, (2) quercetin, (3) benzoic acid, (4) caffeic acid, (5) ferulic acid, (6) kaempferol, and (7) gallic acid.

CONCLUSION

Based on these findings, flavonoids present in hydroalcoholic extract may be developed into a drug for clinical application for the treatment of thrombosis in patients.

Genetic determinants of dabigatran safety (CES1 gene rs2244613 polymorphism) in the Russian population: multi-ethnic analysis

This study was aimed to investigate the prevalence of the CES1 gene (c.1168-33A > C, rs2244613) polymorphism among 12 different ethnic groups living in Russia to provide a basis for future clinical studies concerning genetic determinants of dabigatran safety. The study involved 1630 apparently healthy, unrelated, and chronic medication-free volunteers of both genders from 12 different ethnic groups in Russia: 136 Russians, 90 Avars, 50 Dargins, 46 Laks, 120 Kabardians, 112 Balkars, 244 Ossetians, 206 Mari, 204 Mordvinians, 238 Chuvashes, 114 Buryats and 70 Nanays. Genotyping was performed by using real-time polymerase chain reaction-based methods. The allelic prevalence of the ethnic groups was compared with Caucasus population participating in the RE-LY study. Statistically significant differences for the following gene polymorphism were found between all ethnic groups and RE-LY participants. Based on obtained results, it can be assumed that patients of all ethnic groups living in Russia taking dabigatran have a lower risk of bleeding.

The impact of R353Q genetic polymorphism in coagulation factor VII on the initial anticoagulant effect exerted by warfarin

BACKGROUND

The initial rise in INR following warfarin is attributed to rapid decline in coagulation factor VII (F7). The R353Q polymorphism in F7 accounts for approximately 1/3 of the variability in F7 activity (FVIIc).

OBJECTIVE

Evaluate the role of R353Q in the initial response to warfarin.

METHODS

Twenty-eight healthy, males, carrying CYP2C9*1/*1 (n = 14), CYP2C9*1/*2 (n = 4) or CYP2C9*1/*3 (n = 10) genotypes, received single 20 mg warfarin. S&R-warfarin concentrations, INR, and FVIIc were monitored periodically for 7 days.

RESULTS

Baseline and maximal INR were 5.6% and 33.5% higher among carriers of the RQ (n = 12) as compared with those carrying the RR (n = 16) genotype (p = 0.032, p = 0.003, respectively). Baseline and nadir FVIIc were 21.6% and 42.0% lower among subjects carrying the RQ as compared with carriers of the RR genotype (p = 0.001, p = 0.007 respectively). In multiple regression analysis, R353Q predicted 36.6% of the variability in peak INR whereas 20.2%, 9.9%, and 5.9% were attributed to VKORC1 genetic polymorphism, cholesterol concentration, and S Warfarin concentration after 24 h, respectively.

CONCLUSIONS

R353Q genetic polymorphism plays a key role in determining the initial response to warfarin. The incorporation of this genetic variant into warfarin loading algorithm should be further investigated.

Plasma contact factors as therapeutic targets

Direct oral anticoagulants (DOACs) are small molecule inhibitors of the coagulation proteases thrombin and factor Xa that demonstrate comparable efficacy to warfarin for several common indications, while causing less serious bleeding. However, because their targets are required for the normal host-response to bleeding (hemostasis), DOACs are associated with therapy-induced bleeding that limits their use in certain patient populations and clinical situations. The plasma contact factors (factor XII, factor XI, and prekallikrein) initiate blood coagulation in the activated partial thromboplastin time assay. While serving limited roles in hemostasis, pre-clinical and epidemiologic data indicate that these proteins contribute to pathologic coagulation. It is anticipated that drugs targeting the contact factors will reduce risk of thrombosis with minimal impact on hemostasis. Here, we discuss the biochemistry of contact activation, the contributions of contact factors in thrombosis, and novel antithrombotic agents targeting contact factors that are undergoing pre-clinical and early clinical testing.

Pharmacogenetics of novel oral anticoagulants: a review of identified gene variants & future perspectives

Novel oral anticoagulants (NOACs) are becoming a therapy of choice in everyday clinical practice after almost 50 years during which warfarin and related coumarin derivatives were used as the main anticoagulants. Advantages of NOACs over standard anticoagulants include their predictable pharmacodynamics and pharmacokinetics, stable plasma concentrations and less drug-drug and food-drug interactions. However, pharmacogenetics has its place in administration of NOACs, as considerable interindividual variations have been detected. In this review, previous findings in pharmacogenetics of dabigatran, rivaroxaban, apixaban and edoxaban are summarized, along with recommendations for studying genes encoding metabolically important enzymes for four selected NOACs. Future directions include identification of clinically relevant SNPs, and change in optimum dosage for patients who are carriers of significant variants.

Antithrombotic components of Malus halliana Koehne flowers

Flowers of Malus halliana (M. halliana) Koehne have been used as a Chinese traditional medicine to treat metrorrhagia and in our study, its chemical composition and anticoagulant effect were investigated. Five compounds were isolated and identified from M. halliana flowers, including limocitrin-3-O-glucoside (1), baohuoside Ⅱ (2), kaempferol-3-O-α-L-furan arabinoside (3), phloretin-4'-O-glycosidase (4) and afzeloside (5). Compound 1-3 were isolated for the first time from this genus. The anticoagulant effect of the compounds and extracts of M. halliana flowers were evaluated by APTT, PT, TT and FIB on plasma of rabbit in vitro. The results indicated that several fractions of M. halliana flowers and compounds 2-5 exhibited anticoagulant activity in vitro. Subsequently, afzeloside (5), the abundant component in M. halliana flowers, was investigated further for its antithrombotic effect in vivo and its antithrombotic mechanisms were evaluated on rats acute blood-stasis model. The antithrombotic effect was evaluated by WBV, PV, HCT, ESR, APTT, PT, TT, FIB, 6-keto-PGF1α, TXB2, ET-1 and eNOS in vivo. Afzeloside demonstrated inhibitory effect of thrombus formation, and its underlying antithrombotic mechanism was found to be related to the regulation of vascular endothelium active substance, activating blood flow and anticoagulant effect. Hence, we postulate that flavonoids may be the active ingredients of the plant.

Cytochrome P450 in Pharmacogenetics: An Update

Interindividual variability in drug disposition is a major cause of lack of efficacy and adverse effects of drug therapies. The majority of hepatically cleared drugs are metabolized by cytochrome P450 (CYP) enzymes, mainly in families CYP1, CYP2, and CYP3. Genes encoding these enzymes are highly variable with allele distribution showing considerable differences between populations. Genetic variability of especially CYP2C9, CYP2C19, CYP2D6, and CYP3A5 is known to have clear clinical impact on drugs that are metabolized by these enzymes. CYP1A2, CYP2A6, CYP2B6, CYP2C8, and CYP3A4 all show variability that affects pharmacokinetics of drugs as well, but so far the evidence regarding their clinical implications is not as conclusive. In this review, we provide an up-to-date summary of the pharmacogenetics of the major human drug-metabolizing CYP enzymes, focusing on clinically significant examples.

Pathogenesis of thrombosis: cellular and pharmacogenetic contributions

Our understanding of thrombosis formation has evolved significantly ever since physician Rudolf Virchow proposed his "triad" theory in 1856. Modern science has elucidated the mechanisms of stasis, hypercoagulability, and endothelial dysfunction. Today, we have a firm understanding of the key molecular factors involved in the coagulation cascade and fibrinolytic system, as well as the underlying genetic influences. This knowledge of cellular and genetic contributors has been translated into diverse pharmaceutical interventions. Here, we examine the molecular and cellular mechanisms of thrombosis and its associated pathologies. We also review the current state of pharmacologic interventions, including pro- and anti-thrombotics, direct oral anticoagulants, and anti-platelet therapies. The pharmacogenetic factors that guide clinical decision making and prognosis are described in detail. Finally, we explore new approaches to thrombosis drug discovery, repurposing, and diagnostics. We argue that network biology tools will enable a systems pharmacology revolution in the next generation of interventions, facilitating precision medicine applications and ultimately leading to improved patient outcomes.

Integrating pharmacogenetic testing into primary care

Introduction

Pharmacogenetic (PGx) testing has greatly expanded due to enhanced understanding of the role of genes in drug response and advances in DNA-based testing technology development. As many primary care visits result in a prescription, the use of PGx testing may be particularly beneficial in this setting. However, integration of PGx testing may be limited as no uniform approach to delivery of tests has been established and providers are ill-prepared to integrate PGx testing into routine care.

Areas covered

In this paper, the readiness of primary care practitioners are reviewed as well as strategies to address these barriers based on published research and ongoing activities on education and implementation of PGx testing.

Expert Commentary

Widespread integration of PGx testing will warrant continued education and point-of-care decisional support. Primary care providers may also benefit from consultation services or team-based care with laboratory medicine specialists, pharmacists, and genetic counselors.

Quantitative Assessment of CYP2C9 Genetic Polymorphisms Effect on the Oral Clearance of S-Warfarin in Healthy Subjects

BACKGROUND

Genetic polymorphisms in CYP2C9 account for 10-20% of the variability in warfarin dose requirement. As such CYP2C9 genetic polymorphisms are commonly included in algorithms aimed to optimize warfarin therapy as a way to account for variability in warfarin responsiveness that is due to altered pharmacokinetics. However, most of the currently available pharmacokinetic data were derived from studies among patients on chronic warfarin therapy and therefore suffer from the confounding effects of disease states and drug interactions.

OBJECTIVE

The purpose of the present study was to provide an accurate quantitative estimate of S-warfarin oral clearance (CL_S) among healthy subjects carrying different CYP2C9 genotypes.

METHODS

Single dose of warfarin was administered to 150 non-smokers, age (mean ± SD) 23.3 ± 4.5 years, 60% male, non-obese, healthy subjects. Blood samples were taken for up to 168 h and urine was collected over the entire study period.

RESULTS

Compared with carriers of the wild-type CYP2C9*1/*1 genotype (n = 69), CL_S was reduced by 25, 39 and 47% among heterozygote for CYP2C9*2 (n = 41) CYP2C9*3 (n = 26) and carriers of 2 variant alleles (n = 14), respectively (p < 0.001). The corresponding decrease in the formation clearance of 6 and 7 S-hydroxy-warfarin was 45, 65 and 75%, respectively (p < 0.001).

CONCLUSIONS

The current study provides an estimate concerning the effect of CYP2C9 polymorphisms on S-warfarin pharmacokinetics among healthy subjects. As such it is free of the confounding effects of disease states and drug interactions. Further research is needed to evaluate whether the incorporation of quantitative data obtained in the present study into pharmacogenetic warfarin algorithm may enhance its precision.

TRIAL REGISTRATION

Clinicaltrials.gov Identifier NCT00162474.

Effect of International Normalized Ratio monitoring at home versus the clinic on monitoring adherence in adults taking oral anticoagulant medications: a systematic review protocol

REVIEW QUESTION/OBJECTIVE

The objective of this review is to compare International Normalized Ratio (INR) monitoring adherence in two different settings: the outpatient INR clinic and the patient's home or residence. The review seeks to identify non-adherence trends in both settings to help providers determine which setting is best for patients on warfarin to improve INR monitoring adherence. Improved INR monitoring adherence correlates with maintaining routine INR testing.Specifically, the review question is what is the effect of home point-of-care INR monitoring compared to clinic monitoring on INR monitoring adherence in adults taking oral anticoagulant medications?

Evidence and resources to implement pharmacogenetic knowledge for precision medicine

PURPOSE

The current state of pharmacogenetic data curation and dissemination is described, and evidence-based resources for applying pharmacogenetic data in clinical practice are reviewed.

SUMMARY

Implementation of pharmacogenetics in clinical practice has been relatively slow despite substantial scientific progress in understanding linkages between genetic variation and variability of drug response and effect. One factor that has inhibited the adoption of genetic data to guide medication use is a lack of knowledge of how to translate genetic test results into clinical action based on currently available evidence. Other implementation challenges include controversy over selection of appropriate evidentiary thresholds for routine clinical implementation of pharmacogenetic data and the difficulty of compiling scientific data to support clinical recommendations given that large randomized controlled trials to demonstrate the utility of pharmacogenetic testing are not feasible or are not considered necessary to establish clinical utility. Organizations such as the Clinical Pharmacogenetics Implementation Consortium (CPIC) and the Pharmacogenomics Knowledgebase (PharmGKB) systematically evaluate emerging evidence of pharmacogenomic linkages and publish evidence-based prescribing recommendations to inform clinical practice. Both CPIC and PharmGKB provide online resources that facilitate the interpretation of genetic test results and provide prescribing recommendations for specific gene-drug pairs.

CONCLUSION

Resources provided by organizations such as CPIC and PharmGKB, which use standardized approaches to evaluate the literature and provide clinical guidance for a growing number of gene-drug pairs, are essential for the implementation of pharmacogenetics into routine clinical practice.