Cardiovascular pharmacogenetics

The Role of Gender Pharmacogenetics in the Personalization of Drug Treatment

The use of pharmacogenetic guidelines in personalizing treatments has shown the potential to reduce interindividual variability in drug response by enabling genotype-matched dosing and drug selection. However, other important factors, such as patient gender, may interact strongly with pharmacogenetics in determining the individual profile of toxicity and efficacy but are still rarely considered when planning pharmacological treatment. The literature indicates that males and females respond differently to drugs, with women being at higher risk for toxicity and having different plasma exposure to drugs at standard doses. Recent studies have shown that pharmacogenetic variants may have different predictive value in different sexes, as in the case of treatment with opioids, angiotensin-converting enzyme inhibitors, or proton pump inhibitors. Of particular interest is the case of treatment with fluoropyrimidines for cancer. A significant increase in toxicity has been described in female patients, with a more pronounced effect of specific DPYD and TYMS polymorphisms also noted. This manuscript reviews the major findings in the field of sex-specific pharmacogenomics. SIGNIFICANCE STATEMENT: Interindividual variability in drug response is an emerging issue in pharmacology. The genetic profile of patients, as well as their gender, may play a role in the identification of patients more exposed to the risk of adverse drug reactions or poor efficacy. This article reviews the current state of research on the interaction between gender and pharmacogenetics in addressing interindividual variability.

Pilot study in pharmacogenomic management of empagliflozin in type 2 diabetes mellitus patients

Background

Type 2 diabetes mellitus (T2DM) is a metabolic disorder in which the patients with high blood sugar develop insufficient insulin secretion or insulin resistance. The solute carrier family, 5 member 2 (SLC5A2) gene is a member of sodium/glucose transporter family which can reduce heart and kidney problems. The current study aims to look into any association between rs11646054 variant in SLC5A2 gene and the anti-diabetic efficacy and safety of empagliflozin.

Methods

14 T2DM who failed to respond to previous treatments, empagliflozin 10 mg was added for 6 months. Genotyping of the rs11646054 variant of SLC5A2 gene was performed by polymerase chain reaction (PCR) followed by Sanger sequencing.

Results

Although hemoglobin A1c (HbA1c) and low-density lipoprotein (LDL) were not significantly different, but the mean fasting blood sugar (FBS), 2-h post prandial (2hpp), albumin-to-creatinine ratio (ACR), and total cholesterol (TC) were significantly decreased after 6 months empagliflozin treatment. There was a significant difference in the mean final reductions in FBS level among genotypes. It's important to mention that those who were GG homozygotes had a tendency to have more decrements.

Conclusions

The study results indicate that effects of variation in SLC5A2 (rs11646054) on the clinical efficacy of empagliflozin were negligible.

Pharmacogenetic polymorphisms affecting bisoprolol response

β-blockers are commonly prescribed to treat multiple cardiovascular (CV) diseases, but, frequently, adverse drug reactions and intolerance limit their use in clinical practice. Interindividual variability in response to β-blockers may be explained by genetic differences. In fact, pharmacogenetic interactions for some of these drugs have been widely studied, such as metoprolol. But studies that explore genetic variants affecting bisoprolol response are inconclusive, limited or confusing because of mixed results with other β-Blockers, different genetic polymorphisms observed, endpoint studied etc. Because of this, we performed a systematic review in order to find relevant genetic variants affecting bisoprolol response. We have found genetic polymorphism in several genes, but most of the studies focused in ADRB variants. The ADRB1 Arg389Gly (rs1801253) was the most studied genetic polymorphism and it seems to influence the response to bisoprolol, although studies are inconclusive. Even, we performed a meta-analysis about its influence on systolic/diastolic blood pressure in patients treated with bisoprolol, but this did not show statistically significant results. In conclusion, many genetic polymorphisms have been assessed about their influence on patients´ response to bisoprolol and the ADRB1 Arg389Gly (rs1801253) seems the most relevant genetic polymorphism in this regard but results have not been confirmed with a meta-analysis. Our results support the need of further studies about the impact of genetic variants on bisoprolol response, considering different genetic polymorphisms and conducting single and multiple SNPs analysis, including other clinical parameters related to bisoprolol response in a multivariate study.

Bisoprolol responses (PK/PD) in hypertensive patients: A cytochrome P450 (CYP) 2D6 targeted polymorphism study

BACKGROUND

Bisoprolol is an effective β1-adrenergic blocker, an inter-individual genetic variability was recorded in its response. This study aimed at investigating the association of CYP2D6*2A (rs1080985) and CYP2D6*10 (rs1065852) single-nucleotide polymorphism (SNP) with Bisoprolol response in cardiac patients attending King Abdulaziz University Hospital, Jeddah, Kingdom of Saudi Arabia.

PATIENTS AND METHODS

In the study, 107 patients were enrolled. Five mL of venous blood was collected from each patient and genotyping for CYP2D6*2A and CYP2D6*10 using Vivid® CYP2D6 Green Screening Kit (Life Technologies, USA). Response to Bisoprolol was evaluated through assessment of diastolic and systolic blood pressure and by measuring Bisoprolol plasma level using triple quad mass spectrometer (TQ-MS).

RESULTS

All patients were found to carry homozygous wild type CYP2D6*10 (GG) and none were carrying heterozygous (GA) or mutant homozygous (AA) genotype. CYP2D6*2A allele was detected in the homozygous wild type (GG) in 70 out of 107 patients, the heterozygous (GC) in 19 patients, and the homozygous mutant (CC) in 18 patients with minor allele frequency (MAF) of 25.7%. The plasma concentrations of Bisoprolol in CC carriers were significantly lower than those in GG & CC carriers by 25%, and 51%; respectively. Higher systolic and diastolic blood pressures were also observed in CC carriers than GG and CC carriers.

CONCLUSION

There is a possible association of CYP2D6*2A genotype with plasma concentration of bisoprolol. This could provide a helpful tool to choose the optimum dose for bisoprolol, depending on the patient's genotyping, in order to increase effectiveness and ameliorate its toxicity.

Sexual Dimorphism in Drug Metabolism and Pharmacokinetics

Background:

Sex and gender-based differences are observed well beyond the sex organs and affect several physiological and biochemical processes involved in the metabolism of drug molecules. It is essential to understand not only the sex and gender-based differences in the metabolism of the drug but also the molecular mechanisms involved in the regulation of drug metabolism for avoiding sex-related adverse effects of drugs in the human.

Method:

The articles on the sex and gender-based differences in the metabolism of drug molecules were retrieved from the Pub Med database. The articles were classified into the metabolism of the drug molecule, gene expression regulation of drug-metabolizing enzymes, the effect of sex hormones on the metabolism of drug, expression of drugmetabolizing enzymes, etc.

Result:

Several drug molecules are known, which are metabolized differently in males and females. These differences in metabolism may be due to the genomic and non-genomic action of sex hormones. Several other drug molecules still require further evaluation at the molecular level regarding the sex and gender-based differences in their metabolism. Attention is also required at the effect of signaling cascades associated with the metabolism of drug molecules.

Conclusion:

Sex and gender-based differences in the metabolism of drugs exist at various levels and it may be due to the genomic and non-genomic action of sex hormones. Detailed understanding of the effect of sex and related condition on the metabolism of drug molecules will help clinicians to determine the effective therapeutic doses of drugs dependingon the condition of patient and disease.

Perplexed by PGx? Exploring the impact of pharmacogenomic results on medical management, disclosures and patient behavior

Pharmacogenomic (PGx) tests represent significant advances in precision medicine. Our aim was to explore perceptions following the return of PGx results, medication management, and disclosure to providers. We surveyed clients who had PGx testing and conducted a chart review of PGx results. Respectively, 84% and 94% of participants found pre- and post-test genetic counseling helpful. There was a significant difference in disclosure, while 6% disclosed results to a pharmacist, 50% disclosed to a physician. Qualitative analysis identified three themes: 1) psychological response; 2) perceived utility; 3) experiences with disclosure. Our study supports the provision of genetic counseling for a non-disease related genetic test. Benefits of PGx testing can be optimized by the collaboration of physicians, pharmacists, genetic counselors and patients.

Influence of common polymorphisms in the SLC5A2 gene on metabolic traits in subjects at increased risk of diabetes and on response to empagliflozin treatment in patients with diabetes

OBJECTIVE

Inhibition of the renal sodium-glucose cotransporter 2 (SGLT2) is a novel concept in the therapy of diabetes mellitus. In this study, we first assessed whether common single nucleotide polymorphisms (SNPs) in the SGLT2-encoding gene SLC5A2 affect diabetes-related metabolic traits in subjects at risk for type 2 diabetes and, second, whether these have pharmacogenetic relevance by interfering with the response to empagliflozin treatment in patients with type 2 diabetes.

PATIENTS AND METHODS

Samples from a metabolically well-phenotyped cross-sectional study population (total N=2600) at increased risk for type 2 diabetes and pooled pharmacogenetic samples from patients from four phase III trials of empagliflozin (in total: 603 receiving empagliflozin, 305 receiving placebo) were genotyped for five common SNPs (minor allele frequencies ≥5%) present in the SLC5A2 gene locus.

RESULTS

In the cross-sectional study, none of the SLC5A2 SNPs significantly influenced metabolic traits such as body fat, insulin sensitivity/resistance, insulin release, HbA1c, plasma glucose, or systolic blood pressure when multiple testing was taken into account (all P≥0.0083). Further, no relevant effect on response to treatment with empagliflozin on HbA1c, fasting glucose, weight, or systolic blood pressure was observed for the SNPs tested in the pharmacogenetic study.

CONCLUSION

Common genetic variants in the SLC5A2 gene neither affects diabetes-related metabolic traits nor have a clinically relevant impact on response to treatment with the SGLT2 inhibitor empagliflozin.

Pharmacogenetic comparison of CYP2D6 predictive and measured phenotypes in a South African cohort

The relationship between genetic variation in CYP2D6 and variable drug response represents a potentially powerful pharmacogenetic tool. However, little is known regarding this relationship in the genetically diverse South African population. The aim was therefore to evaluate the relationship between predicted and measured CYP2D6 phenotype. An XL-PCR+Sequencing approach was used to determine CYP2D6 genotype in 100 healthy volunteers and phenotype was predicted using activity scores. With dextromethorphan as the probe drug, metabolic ratios served as a surrogate measure of in vivo CYP2D6 activity. Three-hour plasma metabolic ratios of dextrorphan/dextromethorphan were measured simultaneously using semi-automated online solid phase extraction coupled with tandem mass spectrometry. Partial adaptation of the activity score system demonstrated a strong association between genotype and phenotype, as illustrated by a kappa value of 0.792, inter-rater discrepancy of 0.051 and sensitivity of 72.7%. Predicted phenotype frequencies using the modified activity score were 1.3% for poor metabolisers (PM), 7.6% for intermediate metabolisers (IM) and 87.3% for extensive metabolisers (EM). Measured phenotype frequencies were 1.3% for PM, 13.9% for IM and 84.8% for EM. Comprehensive CYP2D6 genotyping reliably predicts CYP2D6 activity in this South African cohort and can be utilised as a valuable pharmacogenetic tool.

Evaluation of predictive CYP2C19 genotyping assays relative to measured phenotype in a South African cohort

AIM

To align predicted and measured CYP2C19 phenotype in a South African cohort.

MATERIALS & METHODS

Genotyping of CYP2C19*2, *3, *9, *15, *17, *27 and *28 was performed using PCR-RFLP, and an activity score (AS) system was used to predict phenotype. True phenotype was measured using plasma concentrations of omeprazole and its metabolite 5'-hydroxyomperazole.

RESULTS

Partial genotype-phenotype discrepancies were reported, and an adapted AS system was developed, which showed a marked improvement in phenotype prediction. Results highlight the need for a more comprehensive CYP2C19 genotyping approach to improve prediction of omeprazole metabolism.

CONCLUSION

Evidence for the utility of a CYP2C19 AS system is provided, for which the accuracy can be further improved by means of comprehensive genotyping and substrate-specific modification.

Evidence for Clinical Implementation of Pharmacogenomics in Cardiac Drugs

OBJECTIVE

To comprehensively assess the pharmacogenomic evidence of routinely used drugs for clinical utility.

METHODS

Between January 2, 2011, and May 31, 2013, we assessed 71 drugs by identifying all drug/genetic variant combinations with published clinical pharmacogenomic evidence. Literature supporting each drug/variant pair was assessed for study design and methods, outcomes, statistical significance, and clinical relevance. Proposed clinical summaries were formally scored using a modified AGREE (Appraisal of Guidelines for Research and Evaluation) II instrument, including recommendation for or against guideline implementation.

RESULTS

Positive pharmacogenomic findings were identified for 51 of 71 cardiovascular drugs (71.8%), representing 884 unique drug/variant pairs from 597 publications. After analysis for quality and clinical relevance, 92 drug/variant pairs were proposed for translation into clinical summaries, encompassing 23 drugs (32.4% of drugs reviewed). All were recommended for clinical implementation using AGREE II, with mean ± SD overall quality scores of 5.18±0.91 (of 7.0; range, 3.67-7.0). Drug guidelines had highest mean ± SD scores in AGREE II domain 1 (Scope) (91.9±6.1 of 100) and moderate but still robust mean ± SD scores in domain 3 (Rigor) (73.1±11.1), domain 4 (Clarity) (67.8±12.5), and domain 5 (Applicability) (65.8±10.0). Clopidogrel (CYP2C19), metoprolol (CYP2D6), simvastatin (rs4149056), dabigatran (rs2244613), hydralazine (rs1799983, rs1799998), and warfarin (CYP2C9/VKORC1) were distinguished by the highest scores. Seven of the 9 most commonly prescribed drugs warranted translation guidelines summarizing clinical pharmacogenomic information.

CONCLUSION

Considerable clinically actionable pharmacogenomic information for cardiovascular drugs exists, supporting the idea that consideration of such information when prescribing is warranted.

Priority pharmacogenetics for the African continent: focus on CYP450

Countries in Africa have a high burden of communicable disease, and are experiencing an increase in noncommunicable diseases due to the effects of globalization, industrialization and urbanization. The costs incurred through adverse drug reactions and nonresponsiveness to therapy further aggravates the situation, and the application of pharmacogenetic principles is likely to provide some relief. Having undertaken an extensive evaluation of CYP450 reports in Africa, our objective was to map out areas of need based on regional disease burdens. The data confirms a paucity of CYP450 reports and illustrates large regions for which no population information exists. There is a dire need to address the health problems of Africa, and wide-scale pharmacogenetic profiling of these populations will add significantly to improving patient care on the continent. Priority pharmacogenetics for the African continent gives precedence to the profiling of clinically relevant pharmacogenetic biomarkers, and defines the immediate need in the context of disease burden.

Pharmacogenomics, pharmacokinetics and pharmacodynamics: interaction with biological differences between men and women

Pharmacological response depends on multiple factors and one of them is sex-gender. Data on the specific effects of sex-gender on pharmacokinetics, as well as the safety and efficacy of numerous medications, are beginning to emerge. Nevertheless, the recruitment of women for clinical research is inadequate, especially during the first phases. In general, pharmacokinetic differences between males and females are more numerous and consistent than disparities in pharmacodynamics. However, sex-gender pharmacodynamic differences are now increasingly being identified at the molecular level. It is now even becoming apparent that sex-gender influences pharmacogenomics and pharmacogenetics. Sex-related differences have been reported for several parameters, and it is consistently shown that women have a worse safety profile, with drug adverse reactions being more frequent and severe in women than in men. Overall, the pharmacological status of women is less well studied than that of men and deserves much more attention. The design of clinical and preclinical studies should have a sex-gender-based approach with the aim of tailoring therapies to an individual's needs and concerns.

Pharmacogenetic Biomarkers as Tools for Pharmacoepidemiology of Severe Adverse Drug Reactions

Preclinical Research

The development of new genomic technologies has led to an exponential increase in the number of biomarkers for drug safety and efficacy. Pharmacogenomics has the potential to impact clinically relevant outcomes in drug dosing, efficacy, toxicity, and prediction of adverse drug reactions (ADRs). Genotype‐based prescribing is anticipated to improve the overall efficacy rates and minimize ADRs, making personalized medicine a reality. Genome‐wide association studies have been increasingly applied to pharmacogenetics. Severe ADRs are a major issue for drug therapy because they can cause serious disorders and can be life threatening. For severe ADRs, significant associations have been reported for drug‐induced liver injury, statin‐induced myopathy, increased risk of hemorrhagic complications of anticoagulant use, drug‐induced torsade de pointes, drug‐induced long QT, and severe cutaneous ADRs. This review summarizes the current position concerning the clinical and pharmacoepidemiological relevance of pharmacogenetic biomarkers in ADR prediction and prevention, with an emphasis on genetic risk factors and biomarkers for three specific severe ADRs.

Direct-to-Consumer Genetic Testing

Genetics has fascinated societies since ancient times, and references to traits or behaviors that appear to be shared or different among related individuals have permeated legends, literature, and popular culture. Biomedical advances from the past century, and particularly the discovery of the DNA double helix, the increasing numbers of links that were established between mutations and medical conditions or phenotypes, and technological advances that facilitated the sequencing of the human genome, catalyzed the development of genetic testing. Genetic tests were initially performed in health care facilities, interpreted by health care providers, and included the availability of counseling. Recent years have seen an increased availability of genetic tests that are offered by companies directly to consumers, a phenomenon that became known as direct-to-consumer genetic testing. Tests offered in this setting range from the ones that are also provided in health care establishments to tests known as ‘recreational genomics,’ and consumers directly receive the test results. In addition, testing in this context often does not involve the availability of counseling and, when this is provided, it frequently occurs on-line or over the phone. As a field situated at the interface between biotechnology, biomedical research, and social sciences, direct-to-consumer genetic testing opens multiple challenges that can be appropriately addressed only by developing a complex, inter-disciplinary framework.