Applied pharmacogenomics in cardiovascular medicine

Cannabis Pharmacogenomics: A Path to Personalized Medicine

Cannabis and related compounds have created significant research interest as a promising therapy in many disorders. However, the individual therapeutic effects of cannabinoids and the incidence of side effects are still difficult to determine. Pharmacogenomics may provide the answers to many questions and concerns regarding the cannabis/cannabinoid treatment and help us to understand the variability in individual responses and associated risks. Pharmacogenomics research has made meaningful progress in identifying genetic variations that play a critical role in interpatient variability in response to cannabis. This review classifies the current knowledge of pharmacogenomics associated with medical marijuana and related compounds and can assist in improving the outcomes of cannabinoid therapy and to minimize the adverse effects of cannabis use. Specific examples of pharmacogenomics informing pharmacotherapy as a path to personalized medicine are discussed.

Pharmacogenomics Informs Cardiovascular Pharmacotherapy

Precision medicine exemplifies the emergence of personalized treatment options which may benefit specific patient populations based upon their genetic makeup. Application of pharmacogenomics requires an understanding of how genetic variations impact pharmacokinetic and pharmacodynamic properties. This particular approach in pharmacotherapy is helpful because it can assist in and improve clinical decisions. Application of pharmacogenomics to cardiovascular pharmacotherapy provides for the ability of the medical provider to gain critical knowledge on a patient's response to various treatment options and risk of side effects.

Han Chinese specific cytochrome P450 polymorphisms and their impact on the metabolism of anti-hypertensive drugs with adrenoreceptor blocking properties

Introduction: Cytochrome P450 (CYP) is a monooxygenase superfamily mediating the elimination of anti-hypertensive drugs. Polymorphisms of CYP would lead to differential drug efficacy. Building relationships between genotype and phenotype will benefit individual medical treatment of hypertension.Areas covered: The review systematically summarizes the polymorphisms of four CYPs (CYP2C9, CYP2C19, CYP2D6, and CYP3A4) concentrated distributed in the Han Chinese population. Moreover, the activity of variants on metabolizing anti-hypertensive drugs are reviewed, especially drugs with adrenoceptor blocking properties, as well as their clinical relevancies.Expert opinion: The polymorphisms of CYP can cause stratification in drug exposure of antihypertensive drugs. Although the clinical relevance has been built partially, the translational medicine still lacks reliable data support. Furthermore, the studies have demonstrated that even the same CYP variant will exhibit different catalytic capability for different drugs, which is another obstacle to hinder its application. With the deepening of multiomics research and structural biology, nucleotide polymorphisms can be combined with transcriptome, proteome, metabolome and molecular structure analyses to study the susceptibility to hypertension and drug efficacy. A complete data chain would be further estabolished by combining studies of pharmacokinetics-pharmacodynamics, which can effectively promote the precise application of anti-hypertensive drugs.

Genetic variants of GRK4 influence circadian rhythm of blood pressure and response to candesartan in hypertensive patients

Background: Genetic variants of coding genes related to blood pressure regulation participate in the pathogenesis of hypertension and determines the response to specific antihypertensive drugs. G protein-coupled receptor kinase 4 (GRK4) and its variants are of great importance in pathogenesis of hypertension. However, little is known about role of GRK4 variants in determine circadian rhythm of blood pressure and response to candesartan in hypertension. The aim of this study was to analyze the correlation of GRK4 variants and circadian rhythm of blood pressure, and to explore their effect on antihypertensive efficiency of candestartan.Methods: In this study, a total of 1239 cases were eligible, completed ambulatory blood pressure monitoring (ABPm) observation and exon sequencing of G protein-coupled receptor kinase 4 (GRK4). ABPm was obtained before and after 4-week treatment of candesartan. Diurnal variation of systolic blood pressure and antihypertensive effect of candesartan were then assessed.Results: Compared to GRK4 wild type (GRK4-WT), patients with GRK4 variants were more likely to be non-dippers (odds ratio (OR) 6.672, 95% confidence interval (CI) 5.124-8.688, P < .001), with GRK4 A142V (OR 5.888, 95% CI 4.332-8.003, P < .001), A486V (OR 7.102, 95% CI 5.334-9.455, P < .001) and GRK4 R65L (OR 3.273, 95% CI 2.271-4.718, P < .001), respectively. Correlation analysis revealed that non-dippers rhythm of blood pressure were associated with GRK4 variants (r = .420, P < .001), with GRK4 A142V (r = .416, P < .001), A486V (r = .465, P < .001) and GRK4 R65L (r = .266, P < .001), respectively. When given 4-week candesartan, patients with GRK4 variants showed better antihypertensive effect as to drop in blood pressure (24 h mSBP, 21.21 ± 4.99 vs 12.34 ± 4.78 mmHg, P < .001) and morning peak (MP-SBP, 16.54 ± 4.37 vs 11.52 ± 4.14 mmHg, P < .001), as well as greater increase in trough to peak ratio (SBP-T/P, .71 ± .07 vs .58 ± .07, P < .001) and smoothness index (SBP-SI, 1.44 ± .16 vs 1.17 ± .11, P < .001) than those with GRK4 WT.Conclusion: This study indicates that hypertensive patients with GRK4 variants are more likely to be non-dippers. What's more, patients with GRK4 variants possess a significantly better antihypertensive response to candesartan than those with GRK4 WT.

Establishing Serum Reference Ranges for Antihypertensive Drugs

BACKGROUND

Therapeutic drug monitoring (TDM) involves the measurement of serum drug concentrations to optimize pharmacotherapy. Traditionally, blood pressure measurements alone, and not TDM, have been used to evaluate the antihypertensive drug response. However, approximately 50% of hypertensive patients treated with lifestyle changes and antihypertensive drugs fail to achieve blood pressure control. Serum drug concentration measurements could be useful to select the optimal drugs in adjusted doses and to identify nonadherence. Implementation of TDM in clinical routine for antihypertensive drugs depends on established serum reference ranges.

METHODS

Commonly used antihypertensive drugs were identified based on prescription data. The authors performed a review of authoritative literature on reported serum drug concentrations and calculated expected concentrations from previously reported pharmacokinetic parameters with commonly prescribed daily doses. Finally, serum drug concentrations in samples from patients undergoing antihypertensive treatment were measured.

RESULTS

Serum reference ranges for 24 frequently used antihypertensive drugs were established based on results from 3 approaches.

CONCLUSIONS

Serum drug concentration measurements, interpreted in light of the established reference ranges, together with blood pressure measurements and other clinical data, may help identify nonadherent patients and tailor individual antihypertensive treatment when deviant drug responses appear in line with the concept of personalized medicine.

Circulating non-coding RNAs in biomarker-guided cardiovascular therapy: a novel tool for personalized medicine?

Current clinical guidelines emphasize the unmet need for technological innovations to guide physician decision-making and to transit from conventional care to personalized cardiovascular medicine. Biomarker-guided cardiovascular therapy represents an interesting approach to inform tailored treatment selection and monitor ongoing efficacy. However, results from previous publications cast some doubts about the clinical applicability of biomarkers to direct individualized treatment. In recent years, the non-coding human transcriptome has emerged as a new opportunity for the development of novel therapeutic strategies and biomarker discovery. Non-coding RNA (ncRNA) signatures may provide an accurate molecular fingerprint of patient phenotypes and capture levels of information that could complement traditional markers and established clinical variables. Importantly, ncRNAs have been identified in body fluids and their concentrations change with physiology and pathology, thus representing promising non-invasive biomarkers. Previous publications highlight the translational applicability of circulating ncRNAs for diagnosis and prognostic stratification within cardiology. Numerous independent studies have also evaluated the potential of the circulating non-coding transcriptome to predict and monitor response to cardiovascular treatment. However, this field has not been reviewed in detail. Here, we discuss the state-of-the-art research into circulating ncRNAs, specifically microRNAs and long non-coding RNAs, to support clinical decision-making in cardiovascular therapy. Furthermore, we summarize current methodological and conceptual limitations and propose future steps for their incorporation into personalized cardiology. Despite the lack of robust population-based studies and technical barriers, circulating ncRNAs emerge as a promising tool for biomarker-guided therapy.

Development of a High Throughput Screen for the Identification of Inhibitors of Peptidoglycan O-Acetyltransferases, New Potential Antibacterial Targets

The O-acetylation of peptidoglycan occurs in many Gram-negative and most Gram-positive pathogens and this modification to the essential wall polymer controls the lytic activity of the autolysins, particularly the lytic transglycosylases, and inhibits that of the lysozymes of innate immunity systems. As such, the peptidoglycan O-acetyltransferases PatA/B and OatA are recognized as virulence factors. In this study, we present the high throughput screening of small compound libraries to identify the first known inhibitors of these enzymes. The fluorometric screening assay developed involved monitoring the respective O-acetyltransferases as esterases using 4-methylumbelliferylacetate as substrate. Pilot screens of 3921 compounds validated the usefulness of the HTS protocol. A number of potential inhibitors were identified amongst a total of 145,000 low molecular-weight compounds, some of which were common to both enzymes, while others were unique to each. After eliminating a number of false positives in secondary screens, dose response curves confirmed the apparent specificity of a benzothiazolyl-pyrazolo-pyridine as an inhibitor of Neisseria gonorrhoeae PatB, and several coumarin-based compounds as inhibitors of both this PatB and OatA from Staphylococcus aureus. The benzothiazolyl-pyrazolo-pyridine was determined to be a non-competitive inhibitor of PatB with a Ki of 126 µM. At 177 µg/mL and close to its solubility limit, this compound caused a 90% reduction in growth of N. gonorrhoeae, while growth of Escherichia coli, a bacterium that lacks PatB and, hence, does not produce O-acetylated peptidoglycan, was unaffected. These data provide preliminary proof of concept that peptidoglycan O-acetyltransferases would serve as useful antibacterial targets.

Personalised Medicine: The Odyssey from Hope to Practice

In this endeavour, inspired by the Odyssey, we aim to embark with the reader on a journey on a ship from Troy to Ithaca, coursing through the history of the momentous events and achievements that paved the way for personalised medicine. We will set sail amidst important genetic discoveries, beginning with the discovery of the first human genome, and voyage through the projects that contributed to the progress of pharmacogenomic studies. Concurrently, we will propose methods to overcome the obstacles that are slowing the potential full implementation of accumulated knowledge into everyday practice. This journey aims to reflect on the frontiers of current genetic knowledge and the practical use of this knowledge in preventive, diagnostic and pharmacogenomic approaches to directly impact the socio-economic aspects of public health.

Translating Knowledge Into Therapy for Acute Kidney Injury

No therapies have been shown to improve outcomes in patients with acute kidney injury (AKI). Given the high morbidity and mortality associated with AKI this represents an important unmet medical need. A common feature of all of the therapeutic development efforts for AKI is that none were driven by target selection or preclinical modeling that was based primarily on human data. This is important when considering a heterogeneous and dynamic condition such as AKI, in which in the absence of more accurate molecular classifications, clinical cohorts are likely to include patients with different types of injury at different stages in the injury and repair continuum. The National Institutes of Health precision medicine initiative offers an opportunity to address this. By creating a molecular tissue atlas of AKI, defining patient subgroups, and identifying critical cells and pathways involved in human AKI, this initiative has the potential to transform our current approach to therapeutic discovery. In this review, we discuss the opportunities and challenges that this initiative presents, with a specific focus on AKI, what additional efforts will be needed to apply these discoveries to therapeutic development, and how we believe this effort might lead to the development of new therapeutics for subsets of patients with AKI.

Pharmacokinetic Variability of Drugs Used for Prophylactic Treatment of Migraine

In this review, we evaluate the variability in the pharmacokinetics of 11 drugs with established prophylactic effects in migraine to facilitate 'personalized medicine' with these drugs. PubMed was searched for 'single-dose' and 'steady-state' pharmacokinetic studies of these 11 drugs. The maximum plasma concentration was reported in 248 single-dose and 115 steady-state pharmacokinetic studies, and the area under the plasma concentration-time curve was reported in 299 single-dose studies and 112 steady-state pharmacokinetic studies. For each study, the coefficient of variation was calculated for maximum plasma concentration and area under the plasma concentration-time curve, and we divided the drug variability into two categories; high variability, coefficient of variation >40%, or low or moderate variability, coefficient of variation <40%. Based on the area under the plasma concentration-time curve in steady-state studies, the following drugs have high pharmacokinetic variability: propranolol in 92% (33/36), metoprolol in 85% (33/39), and amitriptyline in 60% (3/5) of studies. The following drugs have low or moderate variability: atenolol in 100% (2/2), valproate in 100% (15/15), topiramate in 88% (7/8), and naproxen and candesartan in 100% (2/2) of studies. For drugs with low or moderate pharmacokinetic variability, treatment can start without initial titration of doses, whereas titration is used to possibly enhance tolerability of topiramate and amitriptyline. The very high pharmacokinetic variability of metoprolol and propranolol can result in very high plasma concentrations in a small minority of patients, and those drugs should therefore be titrated up from a low initial dose, depending mainly on the occurrence of adverse events.

Noninvasive Prenatal DNA Testing: The Vanguard of Genomic Medicine

Noninvasive prenatal DNA testing is the vanguard of genomic medicine. In only four years, this screening test has revolutionized prenatal care globally and opened up new prospects for personalized medicine for the fetus. There are widespread implications for increasing the scope of human genetic variation that can be detected before birth, and for discovering more about maternofetal and placental biology. These include an urgent need to develop pretest education for all pregnant women and consistent post-test management recommendations for those with discordant test results. The reduction in invasive testing has had downstream effects on specialist training and caused many countries to re-examine their national approaches to prenatal screening. Finally, the accumulating datasets of genomic information on pregnant women and their fetuses raise ethical issues regarding consent for future data mining and intellectual property.

Effects of 0.5% Timolol Maleate Ophthalmic Solution on Heart Rate and Selected Echocardiographic Indices in Apparently Healthy Cats

Background

Echocardiographic assessment of diastolic function is challenging in cats, partially because of transmitral flow pattern fusion associated with high heart rates. With heart rate (HR) reduction, transmitral flow waveforms separate, allowing identification of diastolic dysfunction. Timolol, an ophthalmic, nonselective beta‐blocker used in glaucoma is safe and transiently decreases HR in clinical trials.

Hypothesis

Administration of timolol ophthalmic solution decreases HR and facilitates echocardiographic assessment of diastolic function in cats without inducing clinically relevant adverse effects.

Animals

Twenty‐five apparently healthy cats.

Methods

Electrocardiograms and echocardiograms including transmitral flow patterns were evaluated before and 20 minutes after ocular administration of 1 drop of timolol 0.5% solution. Twenty cats underwent treatment with timolol, and 5 different cats served as untreated controls to evaluate the effects of acclimation to the hospital environment on HR.

Results

Acclimation to the hospital had no effect on HR in control cats. After timolol administration, a significant median HR reduction of 25 bpm was observed (P < .0001). Timolol had no effect on E/A ratio in cats without E/A fusion (7/20, P = .44). Of the 13 cats with E and A waves that were fused before timolol application, separation of these waves was identified in 8 cats (62%) after timolol treatment. No bradyarrhythmias were noted after timolol administration, but 2 cats had first‐degree atrioventricular block. Timolol resulted in resolution of dynamic outflow tract obstruction in 6 of 6 cats.

Conclusions and clinical importance

Ocular administration of timolol safely decreases HR in cats and could facilitate assessment of diastolic function.

Role of pharmacogenomics in dialysis and transplantation

PURPOSE OF REVIEW

Pharmacogenomics is the study of differences in drug response on the basis of individual genetic background. With rapidly advancing genomic technologies and decreased costs of genotyping, the field of pharmacogenomics continues to develop. Application to patients with kidney disease provides growing opportunities for improving drug therapy.

RECENT FINDINGS

Pharmacogenomics studies are lacking in patients with chronic kidney disease and dialysis, but are abundant in the kidney transplant field. A potentially clinically actionable genetic variant exists in the CYP3A5 gene, with the initial tacrolimus dose selection being optimized based on CYP3A5 genotype. Although many pharmacogenomics studies have focused on transplant immunosuppression pharmacokinetics, an expanding literature on pharmacodynamic outcomes, such as calcineurin inhibitor toxicity and new onset diabetes, is providing new information on patients at risk.

SUMMARY

Appropriately powered pharmacogenomics studies with well-defined phenotypes are needed to validate existing studies and unearth new findings in patients with kidney disease, especially the chronic kidney disease and dialysis population.