Implementing a pharmacogenomic-driven algorithm to guide antiplatelet therapy among Caribbean Hispanics: a non-randomised clinical trial.

OBJECTIVES: To assess whether genotype-guided selection of oral antiplatelet drugs using a clinical decision support (CDS) algorithm reduces the rate of major adverse cardiovascular and cerebrovascular events (MACCEs) among Caribbean Hispanic patients, after 6 months. DESIGN: An open-label, multicentre, non-randomised clinical trial. SETTING: Eight secondary and tertiary care hospitals (public and private) in Puerto Rico. PARTICIPANTS: 300 Caribbean Hispanic patients on clopidogrel, both genders, underwent percutaneous coronary intervention (PCI) for acute coronary syndromes, stable ischaemic heart disease and documented extracardiac vascular diseases. INTERVENTIONS: Patients were separated into standard-of-care (SoC) and genotype-guided (pharmacogenetic (PGx)-CDS) groups (150 each) and stratified by risk scores. Risk scores were calculated based on a previously developed CDS risk prediction algorithm designed to make actionable treatment recommendations for each patient. Individual platelet function, genotypes, clinical and demographic data were included. Ticagrelor was recommended for patients with a high-risk score ≥2 in the PGx-CDS group only, the rest were kept or de-escalated to clopidogrel. The intervention took place within 3-5 days after PCI. Adherence medication score was also measured. PRIMARY AND SECONDARY OUTCOMES: The occurrence rate of MACCEs (primary) and bleeding episodes (secondary). Statistical associations between patient time free of events and predictor variables (ie, treatment groups, risk scores) were tested using Kaplan-Meier survival analyses and Cox proportional-hazards regression models. RESULTS: The genotype-guided group had a clinically lower but not significantly different risk of MACCEs compared with the SoC group (8.7% vs 10.7%, p=0.56; HR=0.56). Among high-risk score patients, genotype-driven guidance of antiplatelet therapy showed superiority over SoC in reducing MACCE incidence 6 months postcoronary stenting (adjusted HR=0.104; p< 0.0001). CONCLUSIONS: The potential benefit of implementing our PGx-CDS algorithm to significantly reduce the incidence rate of MACCEs in post-PCI Caribbean Hispanic patients on clopidogrel was observed exclusively among high-risk patients, with apparently no evident effect in other patient groups. TRIAL REGISTRATION NUMBER: NCT03419325.

Pharmacogenomic polygenic risk score for clopidogrel responsiveness among Caribbean Hispanics: A candidate gene approach.

This multicenter clinical study was aimed at conducting a targeted pharmacogenomic association analysis of residual on-clopidogrel platelet reactivity in 474 Caribbean Hispanic patients. Platelet reactivity was measured using the VerifyNow P2Y12 assay and clopidogrel resistance was defined as P2Y12 reaction units (PRUs) greater than or equal to 208. Genotyping was performed using the whole-genome Infinium MEGA BeadChip array. An ancestry-adjusted, weighted polygenic risk score (wPGxRS) was developed to account for the effect of multiple variants on PRU and compared between clopidogrel responders and nonresponders. The mean PRU across the study cohort was 173.8 ± 68.5 and 33.5% of patients were defined as clopidogrel resistant. Multivariate linear regression showed that 19% of PRU variability was attributed to nine independent predictors, with CYP2C19*2 (rs4244285) accounting for ~ 7% of observed PRU variation (p < 0.001). PON1 rs662, ABCB1/MDR1 rs2032582, PEAR1 rs12041331 carrier status, and the interaction between African ancestry and rs12041331 carriers also predicted PRU among the participants (p ≤ 0.05). A clear gene-dose effect was detected between PRU and CYP2C19*2 genotype, consistent with previous studies in European patient populations, as well as rs12777823. Importantly, a significant positive correlation was detected between our novel wPGxRS (4 variants) and PRU among the Hispanic patient population (rp  = 0.35, p < 0.001). Moreover, the wPGxRS discriminated between nonresponders and responders (p = 0.003), indicating that this multigene-based score is a useful predictor of clopidogrel resistance among Caribbean Hispanics. Taken together, these results help close the gap of knowledge on clopidogrel pharmacogenomics and its potential clinical implementation in this under-represented population.

Assessment of the clinical utility of pharmacogenetic guidance in a comprehensive medication management service.

INTRODUCTION: Pharmacists are poised to be the health care professionals best suited to provide medication-related consults and services based on a patient's genetics. Despite its potential benefits, the implementation of pharmacogenetic (PGx) testing into primary clinical settings has been slow among medically underserved populations. To our knowledge, this is the first time that PGx-driven recommendations have been incorporated into a Comprehensive Medication Management (CMM) service in a Hispanic population. OBJECTIVES: The aim of this study is to evaluate the clinical utility of adding PGx guidance into pharmacist-driven CMM. METHODS: This is a pre- and post-interventional design study. Patients were recruited from a psychologist's clinic. A total of 24 patients had a face-to-face interview with a pharmacist to complete a CMM, Personal Medication Record, and Medication-Related Action Plan (MAP) blind to PGx findings. Collected buccal DNA samples were genotyped using drug-metabolizing enzymes and transporters (DMET) Plus Array. RESULTS: The pharmacist generated new MAPs for each patient based on PGx results. Genetic variants that could potentially affect the safety and effectiveness of at least one drug in the pharmacotherapy were identified in 96% of patients, for whom the pharmacist changed the initial recommendations. Polymorphisms in genes encoding for isoenzymes CYP2D6, CYP2C19, and CYP2C9 were identified in 83%, 52%, and 41% of patients, respectively. Pharmacists performing CMM identified 22 additional medication problems after PGx determinations. Moreover, they agreed with the clinical utility of PGx in the studied sample based on perceived value of adding PGx to traditional CMM and its utility in the decision-making process of pharmacists. CONCLUSIONS: The study confirmed the critical role to be played by pharmacists in facilitating the clinical usage of relevant genetic information to optimize drug therapy decisions as well as their involvement on many levels of these multidisciplinary implementation efforts, including championing and leading PGx-guided CMM services.

Warfarin Anticoagulation Therapy in Caribbean Hispanics of Puerto Rico: A Candidate Gene Association Study.

Existing algorithms account for ~50% of observed variance in warfarin dose requirements after including common polymorphisms. However, they do not perform as well in populations other than Caucasians, in part because some ethno-specific genetic variants are overlooked. The objective of the present study was to identify genetic polymorphisms that can explain variability in warfarin dose requirements among Caribbean Hispanics of Puerto Rico. Next-Generation Sequencing of candidate genes CYP2C9 and VKORC1 and genotyping by DMET® Plus Assay of cardiovascular patients were performed. We also aimed at characterizing the genomic structure and admixture pattern of this study cohort. Our study used the Extreme Discordant Phenotype approach to perform a case-control association analysis. The CYP2C9 variant rs2860905, which was found in all the major haplotypes occurring in the Puerto Rican population, showed stronger association with warfarin sensitivity (<4 mg/day) than common variants CYP2C9*2 and CYP2C9*3. Although, CYP2C9*2 and CYP2C9*3 are separately contained within two of the haplotypes, 10 subjects with the sensitive phenotype were carriers of only the CYP2C9 rs2860905 variant. Other polymorphisms in CES2 and ABCB1 were found to be associated with warfarin resistance. Incorporation of rs2860905 in a regression model (R2 = 0.63, MSE = 0.37) that also includes additional genetics (i.e., VKORC1-1639 G>A; CYP2C9 rs1856908; ABCB1 c.IVS9-44A>G/ rs10276036; CES2 c.269-965A>G/ rs4783745) and non-genetic factors (i.e., hypertension, diabetes and age) showed better prediction of warfarin dose requirements than CYP2C9*2 and CYP2C9*3 combined (partial R2 = 0.132 vs. 0.023 and 0.007, respectively, p < 0.001). The genetic background of Puerto Ricans in the study cohort showed a tri-hybrid admixture pattern, with a slightly higher than expected contribution of Native American ancestry (25%). The genomic diversity of Puerto Ricans is highlighted by the presence of four different major haplotype blocks in the CYP2C9 locus. Although, our findings need further replication, this study contributes to the field by identifying novel genetic variants that increase predictability of stable warfarin dosing among Caribbean Hispanics.

Pharmacogenetic association study of warfarin safety endpoints in Puerto Ricans.

OBJECTIVE: This study was intended to determine the incidence rate of warfarin-related adverse events (e.g., bleeding) in Puerto Ricans and whether a genetic association between warfarin pharmacogenes and any of these adverse events was observed over the initiation period (i.e., the first 90 days of therapy). METHODS: We conducted an observational, retrospective cohort study of pharmacogenetic association in 122 warfarin-treated, male, Puerto Rican patients (69.9 +/- 9.6 years) from the Veterans Affair Caribbean Healthcare System (VACHS) who consented to participate. Genotyping was performed using the CYP2C9 and VKORC1 assays by Luminex. Event-free survival curves were estimated using the Kaplan-Meier method and analyzed by log-rank test. Cox regression models were constructed and hazard ratios (HR) calculated. RESULTS: Carriers of functional CYP2C9 and VKORC1 polymorphisms demonstrated a higher incidence rate of multiple adverse events (i.e., 5.2 vs. 1.0 cases per 100 patient-months; RR = 4.8, p = 0.12) than did wild types. A significant association was observed between multiple adverse events and carrier status (HR = 2.5; 95% CI: 1.0-6.3, p = 0.04). However, no significant associations between genotypes and individual outcomes over the first 90 days of therapy were found. CONCLUSION: The association of CYP2C9 and VKORC1 genotypes and risks for adverse events due to exposure to warfarin was examined for the first time in Puerto Ricans. Despite a lack of association with individual events in this study population, our findings revealed a potential utility of genotyping for the prevention of multiple adverse events during warfarin therapy.

Prediction of warfarin dose reductions in Puerto Rican patients, based on combinatorial CYP2C9 and VKORC1 genotypes.

BACKGROUND: The influence of CYP2C9 and VKORC1 polymorphisms on warfarin dose has been investigated in white, Asian, and African American populations but not in Puerto Rican Hispanic patients. OBJECTIVE: To test the associations between genotypes, international normalized ratio (INR) measurements, and warfarin dosing and gauge the impact of these polymorphisms on warfarin dose, using a published algorithm. METHODS: A retrospective warfarin pharmacogenetic association study in 106 Puerto Rican patients was performed. DNA samples from patients were assayed for 12 variants in both CYP2C9 and VKORC1 loci by HILOmet PhyzioType assay. Demographic and clinical nongenetic data were retrospectively collected from medical records. Allele and genotype frequencies were determined and Hardy-Weinberg equilibrium (HWE) was tested. RESULTS: Sixty-nine percent of patients were carriers of at least one polymorphism in either the CYP2C9 or the VKORC1 gene. Double, triple, and quadruple carriers accounted for 22%, 5%, and 1%, respectively. No significant departure from HWE was found. Among patients with a given CYP2C9 genotype, warfarin dose requirements declined from GG to AA haplotypes; whereas, within each VKORC1 haplotype, the dose decreased as the number of CYP2C9 variants increased. The presence of these loss-of-function alleles was associated with more out-of-range INR measurements (OR = 1.38) but not with significant INR >4 during the initiation phase. Analyses based on a published pharmacogenetic algorithm predicted dose reductions of up to 4.9 mg/day in carriers and provided better dose prediction in an extreme subgroup of highly sensitive patients, but also suggested the need to improve predictability by developing a customized model for use in Puerto Rican patients. CONCLUSIONS: This study laid important groundwork for supporting a prospective pharmacogenetic trial in Puerto Ricans to detect the benefits of incorporating relevant genomic information into a customized DNA-guided warfarin dosing algorithm.

CYP2C9 and VKORC1 genotypes in Puerto Ricans: A case for admixture-matching in clinical pharmacogenetic studies.

BACKGROUNDS: Admixture is of great relevance to the clinical application of pharmacogenetics and personalized medicine, but unfortunately these studies have been scarce in Puerto Ricans. Besides, allele frequencies for clinically relevant genetic markers in warfarin response (i.e., CYP2C9 and VKORC1) have not yet been fully characterized in this population. Accordingly, this study is aimed at investigating whether a correlation between overall genetic similarity and CYP2C9 and/or VKORC1 genotypes could be established. METHODS: 98 DNA samples from Puerto Ricans were genotyped for major CYP2C9 and VKORC1 polymorphisms and tested on a physiogenomic (PG)-array to infer population structure and admixture pattern. RESULTS: Analysis affirmed that Puerto Ricans are broadly admixed. A genetic distance dendrogram was constructed by clustering those subjects with similar genetic profiles. Individual VKORC1 and CYP2C9 genotypes were visually overlaid atop the three dendrogram sectors. Sector-1, representing Amerindian ancestry, showed higher VKORC1 -1639G>A variant frequency than the rest of the population (p=0.051). Although CYP2C9*3 allele frequencies matched the expected HapMap values, admixture may explain deviations from published findings regarding VKORC1 -1639G>A and CYP2C9*2 allele frequencies in sector-3. CONCLUSIONS: Results suggest that the observed inter-individual variations in ancestral contributions have significant implications for the way each Puerto Rican responds to warfarin therapy. Our findings provide valuable evidence on the importance of controlling for admixture in pharmacogenetic studies of Puerto Rican Hispanics.

Exposure to non-therapeutic INR in a high risk cardiovascular patient: potential hazard reduction with genotype-guided warfarin (Coumadin) dosing.

A case to illustrate the utility of genetic screening in warfarin (Coumadin) management is reported. A 45 year-old woman of Puerto Rican ancestry was admitted to the emergency room twice within one month with chest pain. She was diagnosed with congestive heart failure, which was stabilized both times. At her second release, warfarin therapy was initiated at 5 mg/ day to prevent thrombus formation and was lowered to 3.75 mg/day at day 7 by her primary physician. International Normalized Ratio (INR) test results in the follow-up period at days 1, 7, and 10 of warfarin therapy were 4.5, 6.5, and 7.3, respectively-far in excess of the therapeutic range, despite the lower dosage in effect from day 7 onward. The patient achieved target INR over the next 43 days after downward adjustment of the dose to a dose of 1.5 mg/day by trial and error. DNA-typing specific for the CYP2C9*2,*3,*4,*5,*6 alleles and seven variants in the VKORC1 gene, including the VKORC1-1639 G > A polymorphism, revealed the presence of combinatorial CYP2C9*2/*3 and VKORC1-1639 G/A genotypes in this patient. Entering the patient's demographic and genotype status data into independent algorithms available in the public domain to predict effective warfarin dose yielded predicted doses which ranged from 1.5 to 1.8 mg/day. Notably, the prediction of 1.5 mg/day, which was generated by the online resource www.warfarindosing.org, coincided with the patient's actual effective warfarin dose. We conclude that the rapid rise in INR observed upon the initiation of warfarin therapy and the final effective warfarin dose of 1.5 mg/day, are attributable in some part to the presence of two minor alleles in CYP2C9, which together significantly reduce warfarin metabolism. Warfarin genotyping can therefore inform the clinician of the predicted effective warfarin dose. The results highlight the potential for warfarin genetic testing to improve patient care.

Physiogenomic analysis of the Puerto Rican population.

AIMS: Admixture in the population of the island of Puerto Rico is of general interest with regards to pharmacogenetics to develop comprehensive strategies for personalized healthcare in Latin Americans. This research was aimed at determining the frequencies of SNPs in key physiological, pharmacological and biochemical genes to infer population structure and ancestry in the Puerto Rican population. MATERIALS & METHODS: A noninterventional, cross-sectional, retrospective study design was implemented following a controlled, stratified-by-region, random sampling protocol. The sample was based on birthrates in each region of the island of Puerto Rico, according to the 2004 National Birth Registry. Genomic DNA samples from 100 newborns were obtained from the Puerto Rico Newborn Screening Program in dried-blood spot cards. Genotyping using a physiogenomic array was performed for 332 SNPs from 196 cardiometabolic and neuroendocrine genes. Population structure was examined using a Bayesian clustering approach as well as by allelic dissimilarity as a measure of allele sharing. RESULTS: The Puerto Rican sample was found to be broadly heterogeneous. We observed three main clusters in the population, which we hypothesize to reflect the historical admixture in the Puerto Rican population from Amerindian, African and European ancestors. We present evidence for this interpretation by comparing allele frequencies for the three clusters with those for the same SNPs available from the International HapMap project for Asian, African and European populations. CONCLUSION: Our results demonstrate that population analysis can be performed with a physiogenomic array of cardiometabolic and neuroendocrine genes to facilitate the translation of genome diversity into personalized medicine.

Prevalence of combinatorial CYP2C9 and VKORC1 genotypes in Puerto Ricans: implications for warfarin management in Hispanics.

Polymorphisms in the cytochrome P450 2C9 (CYP2C9) and vitamin K epoxide reductase complex subunit 1 (VKORC1) genes significantly alter the effective warfarin dose. We determined the frequencies of alleles, single carriers, and double carriers of single nucleotide polymorphisms (SNPs) in the CYP2C9 and VKORC1 genes in a Puerto Rican cohort and gauged the impact of these polymorphisms on warfarin dosage using a published algorithm. A total of 92 DNA samples were genotyped using Luminex x-MAP technology. The polymorphism frequencies were 6.52%, 5.43% and 28.8% for CYP2C9 *2, *3 and VKORC1-1639 C>A polymorphisms, respectively. The prevalence of combinatorial genotypes was 16% for carriers of both the CYP2C9 and VKORC1 polymorphisms, 9% for carriers of CYP2C9 polymorphisms, 35% for carriers of the VKORC1 polymorphism, and the remaining 40% were non-carriers for either gene. Based on a published warfarin dosing algorithm, single, double and triple carriers of functionally deficient polymorphisms predict reductions of 1.0-1.6, 2.0-2.9, and 2.9-3.7 mg/day, respectively, in warfarin dose. Overall, 60% of the population carried at least a single polymorphism predicting deficient warfarin metabolism or responsiveness and 13% were double carriers with polymorphisms in both genes studied. Combinatorial genotyping of CYP2C9 and VKORC1 can allow for individualized dosing of warfarin among patients with gene polymorphisms, potentially reducing the risk of stroke or bleeding.