Genotype-guided therapy improves initial acenocoumarol dosing

Acenocoumarol Pharmacogenetic Dosing Algorithm versus Usual Care in Patients with Venous Thromboembolism: A Randomised Clinical Trial

Patients with venous thromboembolism (VTE) require immediate treatment with anticoagulants such as acenocoumarol. This multicentre randomised clinical trial evaluated the effectiveness of a dosing pharmacogenetic algorithm versus a standard-of-care dose adjustment at the beginning of acenocoumarol treatment. We included 144 patients with VTE. On the day of recruitment, a blood sample was obtained for genotyping (CYP2C9*2, CYP2C9*3, VKORC1, CYP4F2, APOE). Dose adjustment was performed on day 3 or 4 after the start of treatment according to the assigned group and the follow-up was at 12 weeks. The principal variable was the percentage of patients with an international normalised ratio (INR) within the therapeutic range on day 7. Thirty-four (47.2%) patients had an INR within the therapeutic range at day 7 after the start of treatment in the genotype-guided group compared with 14 (21.9%) in the control group (p = 0.0023). There were no significant differences in the time to achieve a stable INR, the number of INRs within the range in the first 6 weeks and at the end of study. Our results suggest the use of a pharmacogenetic algorithm for patients with VTE could be useful in achieving target INR control in the first days of treatment.

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.

Pharmacogenetics of vitamin K antagonists and bleeding risk prediction in atrial fibrillation

BACKGROUND

Polymorphisms in the vitamin K epoxide reductase complex 1 (VKORC1) and cytochrome P450 2C9 (CYP2C9) genes increase the bleeding risk in anticoagulated atrial fibrillation (AF) patients. Here, we aimed to investigate whether VKORC1 and CYP2C9 polymorphisms improved the predictive performance for major bleeding using the HAS-BLED score.

MATERIAL AND METHODS

We recruited 652 consecutive AF patients stable on vitamin K antagonist (INR 2.0-3.0) during at least the previous 6 months. A baseline venous blood sample was obtained for DNA extraction. We gave an extra point to the HAS-BLED score if the patient was a simultaneous carrier of the VKORC1 and CYP2C9 polymorphisms related to bleeding, and we called this modified score "GEN|HAS-BLED." During a median follow-up of 7.6 years (IQR 5.6-8.0), all major bleeding events were recorded.

RESULTS

During follow-up, 106 (16.2%) patients experienced a major bleeding (2.81%/y; 42 intracranial haemorrhages and 44 gastrointestinal bleeding) and 24 (3.7%) died from major bleeding (0.48%/y). Cox regression analyses demonstrated a significant association between HAS-BLED or GEN|HAS-BLED and major bleeds, both as continuous or categorical scores. Comparison of receiver operating characteristic (ROC) curves shows that original HAS-BLED clinical score had better predictive ability than GEN|HAS-BLED (0.660, 95% CI 0.622-0.696 vs 0.645, 95% CI 0.607-0.682; P = .030). Discrimination and reclassification analyses showed that GEN|HAS-BLED did not improve sensitivity compared with the original score and even showed significant negative reclassification.

CONCLUSION

Adding pharmacogenetic factors (ie polymorphisms of the VKORC1 and CYP2C9 genes) to the HAS-BLED score does not improve the prediction or discrimination performance for major bleeding.

Meta-Analysis of Genotype-Guided Versus Standard Dosing of Vitamin K Antagonists

Vitamin K antagonist (VKA) is a commonly prescribed anticoagulant with a narrow therapeutic window. Genetic polymorphisms account for high VKA dosage variability. Hence, we performed an updated meta-analysis of all randomized clinical trials (RCTs) comparing genotype-guided VKA versus standard dosing algorithms. We conducted a systematic search of electronic databases from inception to October 2017 for all RCTs. The primary outcome was the percentage of time in therapeutic range (TTR). Secondary outcomes were international normalized ratio >4, major and all bleeding events, thromboembolism, adverse and serious adverse events, and all-cause mortality. We calculated the weighted mean difference for the primary outcome and risk ratio (RR) for secondary outcomes using a random-effect model. We included 20 RCTs and analyzed a total of 5,980 adult patients. Our pooled analysis showed greater improvement in TTR for the genotype-guided group in comparison with the standard group (mean difference 3.41%, 95% confidence interval [CI] 0.71 to 6.10, p = 0.01). In addition, there were significant reductions in major and all bleeding events ((RR 0.35, 95% CI 0.20 to 0.63, p = 0.0004) and (RR 0.79, 95% CI 0.66 to 0.95, p = 0.01), respectively). However, there were no significant differences between the groups for international normalized ratio >4 (RR 0.89, 95% CI 0.80 to 1.00, p = 0.06), thromboembolism (RR 0.81, 95% CI 0.56 to 1.17, p = 0.25), serious adverse events (RR 0.79, 95% CI 0.61 to 1.03, p = 0.08), any adverse events (RR 0.94, 95% CI 0.88 to 1.01, p = 0.07), or all-cause mortality (RR 0.73, 95% CI 0.32 to 1.66, p = 0.46). In conclusion, genotype-guided VKA dosing can improve the TTR and reduce the risk for bleeding episodes, in comparison with standard dosing algorithms.

Role of CYP4F2, CYP2C19, and CYP1A2 polymorphisms on acenocoumarol pharmacogenomic algorithm accuracy improvement in the Greek population: need for sub-phenotype analysis

BACKGROUND

We have earlier developed a pharmacogenomic algorithm for acenocoumarol dose prediction in Greek patients that included CYP2C9/VKORC1 genetic information. This study aims at analyzing the potential effect of CYP4F2, CYP2C19, and CYP1A2 gene polymorphisms on acenocoumarol dose requirements and at further improving the Greek-specific pharmacogenomic algorithm.

METHODS

A total of 205 Greek patients taking acenocoumarol (140 who reached and 65 who did not reach stable dose), participants of acenocoumarol EU-PACT trial, were included in the study. CYP4F2, CYP2C19, and CYP1A2 polymorphisms were genotyped by use of the PCR-RFLP method. All patients were previously genotyped for CYP2C9/VKORC1 polymorphisms.

RESULTS

In the pooled sample, CYP4F2, CYP2C19, and CYP1A2 polymorphisms do not affect independently acenocoumarol dose requirements. For CYP4F2, significant effects were found on patients' ability to reach stable dose and on acenocoumarol dose requirements when CYP2C9/VKORC1 sub-phenotypes were analyzed. Specifically, when the patients were stratified according to their CYP2C9/VKORC1 functional bins, in sensitive responders, CYP4F2*3 allele carriers (CYP4F2 *1/*3 and *3/*3 genotypes) were more frequent in the patient group who reached stable dose (p=0.049). Additionally, in CYP2C9 intermediate metabolizers (IMs), after adjusting for age, weight, and VKORC1 genotypes, CYP4F2 genotypes were significantly associated with acenocoumarol stable dose (β: 0.07; 95% CI: 0.006-0.134; p=0.033).

CONCLUSIONS

CYP4F2 gene shows a prominent weak association with acenocoumarol dose requirements. Sub-phenotype analysis is potentially important in determining additional gene polymorphisms that are associated with acenocoumarol dose requirements.

CYP2C9 and VKORC1 in therapeutic dosing and safety of acenocoumarol treatment: implication for clinical practice in Hungary

The purpose of this work was to investigate the contribution of CYP2C9 and VKORC1 to acenocoumarol (AC) dose variability, bleeding events in Hungary. The study recruited 117 patients on long-term AC therapy (INR 2-3), and 510 healthy individuals to model the findings. Patients were genotyped for alleles proved to affect lower AC overdose CYP2C9*2, CYP2C9*3, VKORC1*2. Additionally, we tested VKORC1*3, VKORC1*4 to examine their effect in patients with higher AC requirements. Most impact on dose reduction is accountable for CYP2C9*2/*3 (59%) and for VKORC1*2/*2 (45.5%), and on dose increase for newly evaluated VKORC1*3/*4 (22.5%) diplotypes. VKORC1*3 and *4 alleles seem to balance the dose-reducing effect of VKORC1*2 allele. Being a carrier of combination of VKORC1*2 and CYP2C9*2,*3 polymorphisms, rather than of one of these SNPs, is associated with higher risk of over-anticoagulation (up to 34.3%) in long-term AC treatment. The pharmacogenetic dosing algorithm involving VKORC1, CYP2C9 diplotypes and age explains 30.4% of AC dosing variability (p<6.10×10^-9). Correlation between the studied diplotypes and bleeding events could not be revealed.

Dosing algorithms for vitamin K antagonists across VKORC1 and CYP2C9 genotypes

Essentials Prospective studies of pharmacogenetic-guided (PG) coumarin dosing produced varying results. EU-PACT acenocoumarol and phenprocoumon trials compared PG and non-PG dosing algorithms. Sub-analysis of EU-PACT identified differences between trial arms across VKORC1-CYP2C9 groups. Adjustment of the PG algorithm might lead to a higher benefit of genotyping.

SUMMARY

Background The multicenter, single-blind, randomized EU-PACT trial compared the safety and efficacy of genotype-guided and non-genetic dosing algorithms for acenocoumarol and phenprocoumon in patients with atrial fibrillation or deep vein thrombosis. The trial showed no differences in the primary outcome between the two dosing strategies. Objectives To explore possible reasons for the lack of differences between trial arms by performing a secondary analysis of EU-PACT data in order to evaluate the performance of both dosing algorithms across VKORC1-CYP2C9 genetic subgroups. Patients/Methods Anticoagulation control measured according to an International Normalized Ratio (INR) below (INR of < 2), within (INR of 2-3) and above (INR of > 3) the therapeutic range was compared across VKORC1-CYP2C9 subgroups. Owing to a low number of patients in each subgroup, trials for acenocoumarol and phenprocoumon were combined for analysis. Results Four weeks after therapy initiation, genotype-guided dosing increased the mean percentage of time in the therapeutic INR range (PTIR) in the VKORC1 GG-CYP2C9*1*1 subgroup as compared with the non-genetic dosing (difference of 14.68%, 95% confidence interval [CI] 5.38-23.98). For the VKORC1 AA-CYP2C9*1*1 subgroup, there was a higher risk of under-anticoagulation with the genotype-guided algorithm (difference of 19.9%; 95% CI 11.6-28.2). Twelve weeks after therapy initiation, no statistically significant differences in anticoagulation control between trial arms were noted across the VKORC1-CYP2C9 genetic subgroups. Conclusions EU-PACT genetic-guided dose initiation algorithms for acenocoumarol and phenprocoumon could have predicted the dose overcautiously in the VKORC1 AA-CYP2C9*1*1 subgroup. Adjustment of the genotype-guided algorithm could lead to a higher benefit of genotyping.

Antiplatelet and Antithrombotic Therapy in Patients with Atrial Fibrillation Undergoing Coronary Stenting

Stroke prevention is the main priority in the management cascade of atrial fibrillation. Most patients require long-term oral anticoagulation (OAC) and may require percutaneous coronary intervention. Prevention of recurrent cardiac ischemia and stent thrombosis necessitate dual antiplatelet therapy (DAPT) for up to 12 months. Triple antithrombotic therapy with OAC plus DAPT of shortest feasible duration is warranted, followed by dual antithrombotic therapy of OAC and antiplatelet agent, and OAC alone after 12 months. Because of elevated risk of hemorrhagic complications, new-generation drug-eluting stents, lower-intensity OAC, radial access, and routine use of gastric protection with proton pump inhibitors are recommended.