Common genetic variation in the ABCB1 gene is associated with the cholesterol-lowering effect of simvastatin in males

EDC-DTI: An end-to-end deep collaborative learning model based on multiple information for drug-target interactions prediction

Innovations in drug-target interactions (DTIs) prediction accelerate the progression of drug development. The introduction of deep learning models has a dramatic impact on DTIs prediction, with a distinct influence on saving time and money in drug discovery. This study develops an end-to-end deep collaborative learning model for DTIs prediction, called EDC-DTI, to identify new targets for existing drugs based on multiple drug-target-related information including homogeneous information and heterogeneous information by the way of deep learning. Our end-to-end model is composed of a feature builder and a classifier. Feature builder consists of two collaborative feature construction algorithms that extract the molecular properties and the topology property of networks, and the classifier consists of a feature encoder and a feature decoder which are designed for feature integration and DTIs prediction, respectively. The feature encoder, mainly based on the improved graph attention network, incorporates heterogeneous information into drug features and target features separately. The feature decoder is composed of multiple neural networks for predictions. Compared with six popular baseline models, EDC-DTI achieves highest predictive performance in the case of low computational costs. Robustness tests demonstrate that EDC-DTI is able to maintain strong predictive performance on sparse datasets. As well, we use the model to predict the most likely targets to interact with Simvastatin (DB00641), Nifedipine (DB01115) and Afatinib (DB08916) as examples. Results show that most of the predictions can be confirmed by literature with clear evidence.

Genomewide Association Study of Simvastatin Pharmacokinetics

We investigated genetic determinants of single-dose simvastatin pharmacokinetics in a prospective study of 170 subjects and a retrospective cohort of 59 healthy volunteers. In a microarray-based genomewide association study with the prospective data, the SLCO1B1 c.521T>C (p.Val174Ala, rs4149056) single nucleotide variation showed the strongest, genomewide significant association with the area under the plasma simvastatin acid concentration-time curve (AUC; P = 6.0 × 10^-10 ). Meta-analysis with the retrospective cohort strengthened the association (P = 1.6 × 10^-17 ). In a stepwise linear regression candidate gene analysis among all 229 participants, SLCO1B1 c.521T>C (P = 1.9 × 10^-13 ) and CYP3A4 c.664T>C (p.Ser222Pro, rs55785340, CYP3A4*2, P = 0.023) were associated with increased simvastatin acid AUC. Moreover, the SLCO1B1 c.463C>A (p.Pro155Thr, rs11045819, P = 7.2 × 10^-6 ) and c.1929A>C (p.Leu643Phe, rs34671512, P = 5.3 × 10^-4 ) variants associated with decreased simvastatin acid AUC. Based on these results and the literature, we classified the volunteers into genotype-predicted OATP1B1 and CYP3A4 phenotype groups. Compared with the normal OATP1B1 function group, simvastatin acid AUC was 273% larger in the poor (90% confidence interval (CI), 137%, 488%; P = 3.1 × 10^-6 ), 40% larger in the decreased (90% CI, 8%, 83%; P = 0.036), and 67% smaller in the highly increased function group (90% CI, 46%, 80%; P = 2.4 × 10^-4 ). Intermediate CYP3A4 metabolizers (i.e., heterozygous carriers of either CYP3A4*2 or CYP3A4*22 (rs35599367)), had 87% (90% CI, 39%, 152%, P = 6.4 × 10^-4 ) larger simvastatin acid AUC than normal metabolizers. These data suggest that in addition to no function SLCO1B1 variants, increased function SLCO1B1 variants and reduced function CYP3A4 variants may affect the pharmacokinetics, efficacy, and safety of simvastatin. Care is warranted if simvastatin is prescribed to patients carrying decreased function SLCO1B1 or CYP3A4 alleles.

Glabratephrin reverses doxorubicin resistance in triple negative breast cancer by inhibiting P-glycoprotein

Triple-negative breast cancer is one of the most aggressive breast cancer. The first therapeutic option is chemotherapy, often based on anthracycline as doxorubicin. However, chemotherapy efficacy is limited in by the presence of P-glycoprotein (Pgp), a membrane transporter protein that effluxes doxorubicin, reducing its cellular accumulation and toxicity. Inhibiting Pgp activity with effective and non-toxic products is still an open challenge. In this work, we demonstrated that the natural product Glabratephrin (Glab), a prenylated flavonoid from Tephrosia purpurea with a unique chemical structure, increased doxorubicin accumulation and cytotoxicity in triple negative breast cancer cells with high levels of Pgp, characterized by both acquired or intrinsic resistance to doxorubicin. Glab also reduced the growth of Pgp-expressing tumors, without adding significant extra-toxicities to doxorubicin treatment. Interestingly, Glab did not change the expression of Pgp, but it reduced the affinity for Pgp and the efflux of doxorubicin, as suggested by the increased Km and the reduced Vmax. In silico molecular docking predicted that Glab binds two residues (phenylalanine 322, glutamine 721) localized in the transmembrane domains of Pgp, facing the extracellular environment. Moreover, site-directed mutagenesis identified glycine 185 as a critical residue mediating the reduced catalytic efficacy of Pgp elicited by Glab. We propose Glab as an effective and safe compound able to reverse doxorubicin resistance mediated by Pgp in triple negative breast cancers, opening the way to a new combinatorial approach that may improve chemotherapy efficacy in the most refractory and aggressive breast cancer.

Common Statin Intolerance Variants in ABCB1 and LILRB5 Show Synergistic Effects on Statin Response: An Observational Study Using Electronic Health Records

Background: Statin intolerance impacts approximately 10% of statin users, with side effects ranging from mild myalgia to extreme intolerance resulting in myopathy and rhabdomyolysis. Statin intolerance results in poor adherence to therapy and can impact statin efficacy. Many genetic variants are associated with statin intolerance. The effect of these variants on statin efficacy has not been systematically explored.

Methods: Using longitudinal electronic health records and genetic biobank data from Tayside, Scotland, we examined the effect of seven genetic variants with previously reported associations with simvastatin or atorvastatin intolerance on the outcome of statin response. Statin response was measured by the reduction achieved when comparing pre- and post-statin non-high-density lipoprotein-cholesterol (non-HDL-C). Post-treatment statin response was limited to non-HDL-C measured within 6months of therapy initiation. Univariate and multivariable linear regression models were used to assess the main and adjusted effect of the variants on statin efficacy.

Results: Around 9,401 statin users met study inclusion criteria, of whom 8,843 were first prescribed simvastatin or atorvastatin. The average difference in post-treatment compared to pre-treatment non-HDL-cholesterol was 1.45 (±1.04) mmol/L. In adjusted analyses, only two variants, one in the gene ATP-binding cassette transporter B1 (ABCB1; rs1045642), and one in leukocyte immunoglobulin like receptor B5 (LILRB5; rs12975366), were associated with statin efficacy. In ABCB1, homozygous carriers of the C allele at rs1045642 had 0.06mmol/L better absolute reduction in non-HDL-cholesterol than carriers of the T allele (95% CI: 0.01, 0.1). In LILRB5 (rs12975366), carriers of the C allele had 0.04mmol/L better absolute reduction compared to those homozygous for the T allele (95% CI: 0.004, 0.08). When combined into a two-variant risk score, individuals with both the rs1045642-CC genotype and the rs12975366-TC or CC genotype had a 0.11mmol/L greater absolute reduction in non-HDL-cholesterol compared to those with rs1045642-TC or TT genotype and the rs12975366-TT genotype (95% CI: 0.05, 0.16; p<0.001).

Conclusion: We report two genetic variants for statin adverse drug reactions (ADRs) that are associated with statin efficacy. While the ABCB1 variant has been shown to have an association with statin pharmacokinetics, no similar evidence for LILRB5 has been reported. These findings highlight the value of genetic testing to deliver precision therapeutics to statin users.

Prevalence of dyslipidemia and gene polymorphisms of ABCB1 and SLCO1B1 in Han, Uygur, Kazak, Hui, Tatar, Kirgiz, and Sibe populations with coronary heart disease in Xinjiang, China

Background

Dyslipidemia is a predisposing factor for coronary heart disease (CHD). High-intensity statin therapy is recommended as secondary prevention. ABCB1 and SLCO1B1 genes influence the efficacy and safety of statins. Xinjiang is a multi-ethnic area; however, little is known about the prevalence of dyslipidemia and gene polymorphisms of ABCB1 and SLCO1B1 in minority groups with CHD.

Objective

To measure levels of lipid and apolipoprotein and the prevalence of dyslipidemia and gene polymorphisms of ABCB1, SLCO1B1 in Han, Uygur, Kazak, Hui, Tatar, Kirgiz, and Sibe populations with CHD in Xinjiang.

Methods

This descriptive retrospective study compares lipid levels in ethnic groups using Kruskal-Wallis test or analysis of variance. The study compared gene polymorphisms and the prevalence of dyslipidemia among different ethnic groups using the chi-square test. The lipid profiles in plasma were measured before lipid-lowering therapy using commercially available kits. Genotyping of SLCO1B1 and ABCB1 variants was performed using sequencing by hybridization.

Results

A total of 2218 patients were successfully screened, including 1044 Han, 828 Uygur, 113 Kazak, 138 Hui, 39 Tatar, 36 Kirgiz, and 20 Sibe patients. The overall mean age was 61.8 ± 10.8 years, and 72.5% of participants were male. Dyslipidemia prevalence in these ethnic groups was 42.1, 49.8, 52.2, 40.6, 48.7, 41.7, and 45.0%, respectively. The prevalence of dyslipidemia, high total cholesterol (TC), high triglycerides (TG), and high low density lipoprotein cholesterol (LDL-C) differed significantly among the groups (P = 0.024; P < 0.001; P < 0.001; P < 0.001, respectively). For the Han group, high LDL-C, high TC, and high TG prevalence differed significantly by gender (P = 0.001, P = 0.022, P = 0.037, respectively). The prevalence of high TC, high TG, and low high density lipoprotein cholesterol (HDL-C) differed significantly by gender in the Uygur group (P = 0.006, P = 0.004, P < 0.001, respectively). The prevalence of high TC in Hui patients significantly differed by gender (P = 0.043). These findings suggest that polymorphisms in ABCB1 and C3435T differ significantly across ethnicities (P < 0.001).

Conclusions

The prevalences of dyslipidemia, high TC, high TG, and high LDL-C in Han, Uygur, Kazak, Hui, Tatar, Kirgiz, and Sibe CHD patients in Xinjiang differed concerning ethnicity. Ethnic, gender, and lifestyle were the key factors that affected the lipid levels of the population. The prevalence of polymorphisms of ABCB1 and C3435T significantly differed across ethnicities. These findings will aid the selection of precision lipid-lowering medications and prevention and treatment of CHD according to ethnicity in Xinjiang.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12944-021-01544-3.

Pharmacogenomics of statins: lipid response and other outcomes in Brazilian cohorts

Statins are inhibitors of 3-hydroxy-3-methylglutaryl-CoA reductase, a key enzyme in cholesterol biosynthesis, that are highly effective in reducing plasma low-density lipoprotein (LDL) cholesterol and decreasing the risk of cardiovascular events. In recent years, a multitude of variants in genes involved in pharmacokinetics (PK) and pharmacodynamics (PD) have been suggested to influence the cholesterol-lowering response. However, the vast majority of studies have analyzed the pharmacogenetic associations in populations in Europe and the USA, whereas data in other populations, including Brazil, are mostly lacking. This narrative review provides an update of clinical studies on statin pharmacogenomics in Brazilian cohorts exploring lipid-lowering response, adverse events and pleiotropic effects. We find that variants in drug transporter genes (SLCO1B1 and ABCB1) positively impacted atorvastatin and simvastatin response, whereas variants in genes of drug metabolizing enzymes (CYP3A5) decreased response. Furthermore, multiple associations of variants in PD genes (HMGCR, LDLR and APOB) with statin response were identified. Few studies have explored statin-related adverse events, and only ABCB1 but not SLCO1B1 variants were robustly associated with increased risk in Brazil. Statin-related pleiotropic effects were shown to be influenced by variants in PD (LDLR, NR1H2) and antioxidant enzyme (NOS3, SOD2, MTHFR, SELENOP) genes. The findings of these studies indicate that statin pharmacogenomic associations are distinctly different in Brazil compared to other populations. This review also discusses the clinical implications of pharmacogenetic studies and the rising importance of investigating rare variants to explore their association with statin response.

Association of ABCB1 C3435T Polymorphism with Echocardiographic Index Among Patients with Atherosclerotic Ischemic Stroke and Transient Ischemic Attack

Emerging evidence has suggested that patients with ischemic stroke (IS) and/or transient ischemic attack (TIA) are more likely to exhibit myocardial disorders, which can be reflected by transthoracic echocardiography (TTE). ATP binding cassette transporter 1 (ABCB1) plays an important role in the development and progression of atherosclerotic pathology. The objective of the current study was to investigate the associations of ABCB1 C3435T polymorphism with echocardiographic performances among patients with acute ischemic stroke. Patients with IS or TIA, who were hospitalized and received TTE between October 2016 to March 2019, were enrolled in this study. Demographic data and echocardiographic parameters of each participant were recorded. We included 122 patients, with the respective distribution of 12.30%, 48.36%, and 39.34% in CC, CT, and TT genotypes. There were significant differences among the three ABCB1 types, with respect to RV (P = 0.036). The presence of the TT genotype was associated with increased MVE (OR = 0.13, P = 0.02) but correlated with decreased RV (OR = -1.46, P = 0.02). Our study indicated that ABCB1 C3435T polymorphism is associated with echocardiographic parameters among patients with acute ischemic stroke. The presence of the TT genotype is associated with diastolic function and cardiac hypertrophy.

Role of Genetic Variations in the Hepatic Handling of Drugs

The liver plays a pivotal role in drug handling due to its contribution to the processes of detoxification (phases 0 to 3). In addition, the liver is also an essential organ for the mechanism of action of many families of drugs, such as cholesterol-lowering, antidiabetic, antiviral, anticoagulant, and anticancer agents. Accordingly, the presence of genetic variants affecting a high number of genes expressed in hepatocytes has a critical clinical impact. The present review is not an exhaustive list but a general overview of the most relevant variants of genes involved in detoxification phases. The available information highlights the importance of defining the genomic profile responsible for the hepatic handling of drugs in many ways, such as (i) impaired uptake, (ii) enhanced export, (iii) altered metabolism due to decreased activation of prodrugs or enhanced inactivation of active compounds, and (iv) altered molecular targets located in the liver due to genetic changes or activation/downregulation of alternative/compensatory pathways. In conclusion, the advance in this field of modern pharmacology, which allows one to predict the outcome of the treatments and to develop more effective and selective agents able to overcome the lack of effect associated with the existence of some genetic variants, is required to step forward toward a more personalized medicine.

Pharmacogenetics of statins treatment: Efficacy and safety

WHAT IS KNOWN AND OBJECTIVE

Statins are widely used worldwide in the prevention and treatment of coronary atherosclerotic heart disease and ischaemic stroke. However, in clinical application, statins have shown great individual differences in terms of the efficacy and safety, some of which are related to genetic factors. The purpose of this article was to summarize the recent advances about the correlation between gene polymorphisms and the efficacy/safety of statins.

METHODS

We searched the databases including PharmGKB and PubMed (published before June 2019) using the keywords such as 'statin', 'gene polymorphism' and 'SNP' and obtained more than 100 articles. In this review, we described the clinical studies of genetic variants associated with both the efficacy and adverse reactions of statins. We also clarified the importance of taking pharmacogenetic variation into account to improve the clinical application of statins.

RESULTS AND DISCUSSION

The available data were collected and analysed to present the polymorphisms of candidate genes encoding the most promising proteins including SLCO1B1 (encoding uptake transporters); ABCB1, ABCC2, ABCG2 (encoding effluent transporter); APOE, APOA5 (encoding apolipoprotein); genes encoding cytochrome P450 enzyme system; KIF6, HMGCR, LDLR, LPA, PCSK9, COQ2, CETP, etc These genes were proved to be related to the pharmacodynamics and pharmacokinetics of statins, thus affecting the efficacy and safety.

WHAT IS NEW AND CONCLUSION

In this paper, the correlation between gene polymorphisms and the efficacy/safety of statins was summarized. The authors reached a consensus that the variants of the genes encoding uptake and effluent transporters have the most effect on the efficacy/safety of statins. It pointed out that it is desirable to do genetic testing of these transporter genes to reduce the incidence of myopathy or to achieve better outcomes before patients use statins, especially in the regions with high frequency of risk allele.

Assessment of the Risk of Rhabdomyolysis and Myopathy During Concomitant Treatment with Ticagrelor and Statins

The introduction of ticagrelor, one of the first directly-acting oral antiplatelet drugs, provided new possibilities in the prevention of thrombotic events in patients with acute coronary syndromes (ACS). Current guidelines recommend ticagrelor in dual antiplatelet therapy with aspirin over clopidogrel for prevention of stent thrombosis in patients with ACS. Moreover, in the management of ACS, lipid-lowering treatment with high-intensity statin therapy is advised for secondary prevention of cardiovascular events over the long term. Despite the apparent advantages of combined antiplatelet and lipid-lowering treatments, a possible interaction between statins and ticagrelor may lead to myopathy and rhabdomyolysis. In this review, relevant information was gathered on the ticagrelor-statin interaction that might lead to this life-threatening condition. This review focuses on the most widely used statins—simvastatin, atorvastatin, and rosuvastatin. Possible mechanisms of this interaction are discussed, including CYP3A4 isoenzymes, organic anion transporter polypeptide (OATPs), P-glycoprotein and glucuronidation. PubMed database was searched for relevant case reports and all data gathered from the introduction of ticagrelor to March 2018 are presented and discussed. In summary, co-administration of statins and ticagrelor was found to be relatively safe in routinely prescribed doses. However, caution should be exercised, especially in elder populations.

ATP-Binding Cassette Transporters in the Clinical Implementation of Pharmacogenetics

ATP-binding cassette (ABC) transporters are involved in a large number of processes and contribute to various human genetic diseases. Among other functions, ABC proteins are involved in the transport of multiple drugs through cells. Most of the genes coding for these transporters are highly polymorphic and DNA variants in these genes can affect the normal functioning of these proteins, affecting the way drugs are transported, increasing or decreasing drug levels. These changes in the intracellular and extracellular drug levels may be associated with altered drug effectiveness or severe drug-induced adverse events. This review presents a state-of-art of the most pharmacogenetics clinically relevant ABC transporters closed to the clinical implementation.

Pharmacogenetic Foundations of Therapeutic Efficacy and Adverse Events of Statins

Background: In the era of precision medicine, more attention is paid to the search for predictive markers of treatment efficacy and tolerability. Statins are one of the classes of drugs that could benefit from this approach because of their wide use and their incidence of adverse events. Methods: Literature from PubMed databases and bibliography from retrieved publications have been analyzed according to terms such as statins, pharmacogenetics, epigenetics, toxicity and drug–drug interaction, among others. The search was performed until 1 October 2016 for articles published in English language. Results: Several technical and methodological approaches have been adopted, including candidate gene and next generation sequencing (NGS) analyses, the latter being more robust and reliable. Among genes identified as possible predictive factors associated with statins toxicity, cytochrome P450 isoforms, transmembrane transporters and mitochondrial enzymes are the best characterized. Finally, the solute carrier organic anion transporter family member 1B1 (SLCO1B1) transporter seems to be the best target for future studies. Moreover, drug–drug interactions need to be considered for the best approach to personalized treatment. Conclusions: Pharmacogenetics of statins includes several possible genes and their polymorphisms, but muscular toxicities seem better related to SLCO1B1 variant alleles. Their analysis in the general population of patients taking statins could improve treatment adherence and efficacy; however, the cost–efficacy ratio should be carefully evaluated.

Seventeen years of statin pharmacogenetics: a systematic review

AIM

We evaluated the evidence of pharmacogenetic associations with statins in a systematic review.

METHODS

Two separate outcomes were considered of interest: modification of low-density lipoprotein cholesterol (LDL-C) response and modification of risk for cardiovascular events.

RESULTS

In candidate gene studies, 141 loci were claimed to be associated with LDL-C response. Only 5% of these associations were positively replicated. In addition, six genome-wide association studies of LDL-C response identified common SNPs in APOE, LPA, SLCO1B1, SORT1 and ABCG2 at genome-wide significance. None of the investigated SNPs consistently affected the risk reduction for cardiovascular events.

CONCLUSION

Only five genetic loci were consistently associated with LDL-C response. However, as effect sizes are modest, there is no evidence for the value of genetic testing in clinical practice.

Function-impairing polymorphisms of the hepatic uptake transporter SLCO1B1 modify the therapeutic efficacy of statins in a population-based cohort

BACKGROUND

The efficacy of statins, which are used commonly in primary and secondary prevention of cardiovascular diseases, shows a wide range of interindividual variability. Genetic variants of OATP1B1, a hepatic uptake transporter, can modify access of statins to its therapeutic target, thereby potentially altering drug efficacy. We studied the impact of genetic variants of OATP1B1 on the lipid-lowering efficacy of statins in a population-based setting.

MATERIALS AND METHODS

The basis of the analysis was the Study of Health in Pomerania, a cohort of 2732 men and women aged 20-81 years. Included in the statistical analysis to evaluate the impact of OATP1B1 on therapeutic efficacy of statins were 214 individuals diagnosed with dyslipidaemia during initial recruitment and receiving statins during the 5-year follow-up.

RESULTS

Analysing the impact of the OATP1B1 genotype, we observed a trend for lower statin-induced total cholesterol reduction in carriers of the SLCO1B1 512C variant. Restricting the analysis to patients receiving simvastatin, pravastatin, lovastatin and fluvastatin indicated a statistically significant association of the OATP1B1 genotype on lipid parameters at the 5-year follow-up. No such effect was observed for atorvastatin. Calculation of achievement of treatment goals according to the NCEP-ATPIII guidelines showed a lower rate of successful treatment when harbouring the mutant allele for patients taking simvastatin (46.7 vs. 73.9%). A similar trend was observed for pravastatin (34.4 vs. 70.4%).

CONCLUSION

Genetic variants of OATP1B1 leading to impaired hepatic uptake of statins translated into reduced drug efficacy in a population-based cohort.

Possible association of ABCB1:c.3435T>C polymorphism with high-density-lipoprotein-cholesterol response to statin treatment--a pilot study

The gene product ABCB1 (formerly MDR1 or P-glycoprotein) is hypothesized to be involved in cholesterol cellular trafficking, redistribution and intestinal re-absorption. Carriers of the ABCB1:3435T allele have previously been associated with decreases in ABCB1 mRNA and protein concentrations and have been correlated with changes in serum lipid concentrations. The aim of this study was to investigate possible association between the ABCB1:3435T>C polymorphism and changes in lipids in patients following statin treatment. Outpatients (n=130) were examined: 43 men (33%), 87 women (67%): treated with atorvastatin or simvastatin (all patients with equivalent dose of 20 or 40 mg/d simvastatin). Blood was taken for ABCB1:3435T>C genotyping, and before and after statin treatment for lipid concentration determination (total cholesterol, high-density-lipoprotein-cholesterol (HDL-C), triglycerides). Change (Δ) in lipid parameters, calculated as differences between measurements before and after treatment, were analyzed with multiple regression adjustments: gender, diabetes, age, body mass index, equivalent statin dose, length of treatment. Univariate and multivariate analyses showed significant differences in ΔHDL-C (univariate p=0.029; multivariate p=0.036) and %ΔHDL-C (univariate p=0.021; multivariate p=0.023) between patients with TT (-0.05 ± 0.13 g/l; -6.8% ± 20%; respectively) and CC+CT genotypes (0.004 ± 0.15 g/l; 4.1 ± 26%; respectively). Reduction of HDL-C in homozygous ABCB1:3435TT patients suggests this genotype could be associated with a reduction in the benefits of statin treatment.

Association between statin-induced creatine kinase elevation and genetic polymorphisms in SLCO1B1, ABCB1 and ABCG2

PURPOSE

Treatment with statins requires close monitoring of serum creatine kinase (CK) levels to prevent myopathy, a common and potentially serious dose-dependent adverse effect of these drugs. We have investigated the correlation between elevated CK levels and polymorphisms in the genes encoding transporters involved in statin disposition.

METHODS

Patients with and without statin-induced elevated serum CK levels were genotyped for polymorphisms in SLCO1B1 (SLCO1B1 A388G and SLCO1B1 T521C), ABCB1 (ABCB1 C1236T and ABCB1 C3435T) and ABCG2 (ABCG2 C421A).

RESULTS

Patients carrying SLCO1B1 T521C or ABCB1 C1236T single nucleotide polymorphisms (SNPs) had an odds ratio (OR) for statin-induced elevated serum CK levels of 8.86 (p<0.01) and 4.67 (p<0.05), respectively, while patients carrying the SLCO1B1 A388G SNP had an OR of 0.24 (p<0.05). An arbitrary score based on genotype combination discriminated patients with and without CK elevation at a specificity of 97 % and a sensitivity of 39 %.

CONCLUSION

Genotyping of the SLCO1B1, ABCB1 and ABCG2 genes deserves consideration as a clinical approach to improve statin safety while concomitantly reducing the burden of blood tests for CK measurements.

Common genetic polymorphisms in the ABCB1 gene are associated with risk of major depressive disorder in male Portuguese individuals

Major depressive disorder (MDD) is a highly prevalent disorder, which has been associated with an abnormal response of the hypothalamus-pituitary-adrenal (HPA) axis. Reports have argued that an abnormal HPA axis response can be due to an altered P-Glycoprotein (P-GP) function. This argument suggests that genetic polymorphisms in ABCB1 may have an effect on the HPA axis activity; however, it is still not clear if this influences the risk of MDD. Our study aims to evaluate the effect of ABCB1 C1236T, G2677TA and C3435T genetic polymorphisms on MDD risk in a subset of Portuguese patients. DNA samples from 80 MDD patients and 160 control subjects were genotyped using TaqMan SNP Genotyping assays. A significant protection for MDD males carrying the T allele was observed (C1236T: odds ratio (OR)=0.360, 95% confidence interval [CI]: [0.140-0.950], p=0.022; C3435T: OR=0.306, 95% CI: [0.096-0.980], p=0.042; and G2677TA: OR=0.300, 95% CI: [0.100-0.870], p=0.013). Male Portuguese individuals carrying the 1236T/2677T/3435T haplotype had nearly 70% less risk of developing MDD (OR=0.313, 95% CI: [0.118-0.832], p=0.016, FDR p=0.032). No significant differences were observed regarding the overall subjects. Our results suggest that genetic variability of the ABCB1 is associated with MDD development in male Portuguese patients. To the best of our knowledge, this is the first report in Caucasian samples to analyze the effect of these ABCB1 genetic polymorphisms on MDD risk.

Associations of ABCB1 and IL-10 genetic polymorphisms with sirolimus-induced dyslipidemia in renal transplant recipients

BACKGROUND

Hyperlipidemia is a common adverse effect of sirolimus (SRL). We previously showed significant associations of ABCB1 3435C>T and IL-10 -1082G>A with log-transformed SRL dose-adjusted weighted-normalized trough. We further examined to see whether these polymorphisms were also associated with SRL-induced dyslipidemia.

METHODS

Genotyping was performed for ABCB1 1236C>T, 2677 G>T/A, and 3435C>T; CYP3A4 -392A>G; CYP3A5 6986A>G and 14690G>A; IL-10 -1082G>A; TNF -308G>A; and ApoE ε2, ε3, and ε4 alleles. The longitudinal changes of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and triglyceride (TG) levels after SRL treatment before statin therapy were analyzed by a linear mixed-effects model, with adjustments for selected covariates for each lipid.

RESULTS

Under the dominant genetic model, ABCB1 3435C>T was associated with TC (P=0.0001) and LDL-C (P<0.0001) values after SRL administration. Mean TC and LDL-C levels were 26.9 and 24.9 mg/dL higher, respectively, in ABCB1 3435T carriers than 3435CC homozygotes at an average SRL trough concentration of 4 ng/mL without concomitant medication. ABCB1 1236C>T under the recessive model and IL-10 -1082G>A under the dominant model were associated with log-transformed TG values (P=0.0051 and 0.0436, respectively). Mean TG value was 25.1% higher in ABCB1 1236TT homozygotes compared with ABCB1 1236C carriers and was 12.4% higher in IL-10 -1082AA homozygotes than -1082G carriers.

CONCLUSIONS

ABCB1 polymorphisms were found to be associated with lipid responses to SRL treatment, confirming the role of ABCB1 gene in SRL pharmacokinetics and pharmacodynamics. Further studies are necessary to define the role of ABCB1 and IL-10 polymorphisms on SRL-induced dyslipidemia in renal transplantation.

Novel CYP3A4 intron 6 single nucleotide polymorphism is associated with simvastatin-mediated cholesterol reduction in the Rotterdam Study

OBJECTIVES

CYP3A4 is involved in the oxidative metabolism of many drugs and xenobiotics including the HMG-CoA reductase inhibitor simvastatin. The objective of this study was to investigate whether a new CYP3A4 functional single nucleotide polymorphism (SNP) in intron 6 (CYP3A4*22) modifies the effect of simvastatin on total cholesterol (TOTc) or LDL cholesterol (LDLc) reduction in a population-based cohort study.

METHODS

In a total of 80 incident simvastatin users, the association between the CYP3A4 intron 6 C>T SNP (rs35599367) and reduction in cholesterol levels was analyzed using linear regression analysis and adjusting for potential confounding factors.

RESULTS

The CYP3A4*22 allele was associated with a trend towards a stronger simvastatin lipid-lowering response, as reflected by the greater reduction in both TOTc and LDLc levels when compared with homozygous wild type. We observed that the CYP3A4*22 allele carriers had an increased reduction in TOTc and LDLc: -0.25 mmol/l (95% confidence interval [CI(95%)]=[-0.52; 0.01], P=0.058) and -0.29 mmol/l (CI(95%)=[-0.58; 0.01], P=0.054) when compared with homozygous CC. When we adjusted the model for potential confounding factors, the corresponding reduction in TOTc was -0.31 mmol/l (CI(95%)=[-0.59;-0.04], P=0.028) and for LDLc -0.34 mmol/l (CI(95%)=[-0.66; -0.02], P=0.034) greater for CYP3A4*22 allele carriers when compared with homozygotes wild type.

CONCLUSION

The CYP3A4*22 intron 6 SNP T-variant allele was associated with reduced CYP3A4 activity, resulting in a better lipid lowering response to simvastatin, when data were adjusted for confounding factors. This observation is a step towards the clarification of the reasons of interindividual variability in statins response and may potentially lead to improved tailoring of simvastatin therapy.

Genome-wide association study of genetic determinants of LDL-c response to atorvastatin therapy: importance of Lp(a)

We carried out a genome-wide association study (GWAS) of LDL-c response to statin using data from participants in the Collaborative Atorvastatin Diabetes Study (CARDS; n = 1,156), the Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT; n = 895), and the observational phase of ASCOT (n = 651), all of whom were prescribed atorvastatin 10 mg. Following genome-wide imputation, we combined data from the three studies in a meta-analysis. We found associations of LDL-c response to atorvastatin that reached genome-wide significance at rs10455872 (P = 6.13 × 10(-9)) within the LPA gene and at two single nucleotide polymorphisms (SNP) within the APOE region (rs445925; P = 2.22 × 10(-16) and rs4420638; P = 1.01 × 10(-11)) that are proxies for the ε2 and ε4 variants, respectively, in APOE. The novel association with the LPA SNP was replicated in the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER) trial (P = 0.009). Using CARDS data, we further showed that atorvastatin therapy did not alter lipoprotein(a) [Lp(a)] and that Lp(a) levels accounted for all of the associations of SNPs in the LPA gene and the apparent LDL-c response levels. However, statin therapy had a similar effect in reducing cardiovascular disease (CVD) in patients in the top quartile for serum Lp(a) levels (HR = 0.60) compared with those in the lower three quartiles (HR = 0.66; P = 0.8 for interaction). The data emphasize that high Lp(a) levels affect the measurement of LDL-c and the clinical estimation of LDL-c response. Therefore, an apparently lower LDL-c response to statin therapy may indicate a need for measurement of Lp(a). However, statin therapy seems beneficial even in those with high Lp(a).

Genetic variation in the ABCC2 gene is associated with dose decreases or switches to other cholesterol-lowering drugs during simvastatin and atorvastatin therapy

Several statins are substrates for the multidrug resistance-associated protein 2 transporter, encoded by the ABCC2 gene. We analyzed in the Rotterdam Study whether the common polymorphisms -24C>T, 1249G>A and 3972C>T in the ABCC2 gene were associated with a dose decrease or switch to another cholesterol-lowering drug in simvastatin and atorvastatin users. These events could indicate an adverse effect or a too strong reduction in cholesterol level. We identified 1014 simvastatin and atorvastatin users during the period 1 January 1991 to 1 January 2010. Associations between genetic variation and the risk of these events were analyzed using Cox proportional hazards modelling. The ABCC2 -24C>T genotype (HR 1.32 95% CI 1.04-1.69) and the H12 haplotype versus the H2 haplotype (HR 1.49; 95% CI 1.06-2.09) were associated with these events in simvastatin users. A similar but not significant association was found in atorvastatin users. To conclude, genetic variation in the ABCC2 gene is associated with these events in simvastatin users.

Functional significance of genetic polymorphisms in P-glycoprotein (MDR1, ABCB1) and breast cancer resistance protein (BCRP, ABCG2)

Recent pharmacogenomic/pharmacogenetic (PGx) studies have disclosed important roles for drug transporters in the human body. Changes in the functions of drug transporters due to drug/food interactions or genetic polymorphisms, for example, are associated with large changes in pharmacokinetic (PK) profiles of substrate drugs, leading to changes in drug response and side effects. This information is extremely useful not only for drug development but also for individualized treatment. Among drug transporters, the ATP-binding cassette (ABC) transporters are expressed in most tissues in humans, and play protective roles; reducing drug absorption from the gastrointestinal tract, enhancing drug elimination into bile and urine, and impeding the entry of drugs into the central nervous system and placenta. In addition to PK/pharmacodynamic (PD) issues, ABC transporters are reported as etiologic and prognostic factors (or biomarkers) for genetic disorders. Although a consensus has not yet been reached, clinical studies have demonstrated that the PGx of ABC transporters influences the overall outcome of pharmacotherapy and contributes to the pathogenesis and progression of certain disorders. This review explains the impact of PGx in ABC transporters in terms of PK/PD, focusing on P-glycoprotein and breast cancer resistance protein (BCRP).

The interactions of age, genetics, and disease severity on tacrolimus dosing requirements after pediatric kidney and liver transplantation

Purpose

In children, data on the combined impact of age, genotype, and disease severity on tacrolimus (TAC) disposition are scarce. The aim of this study was to evaluate the effect of these covariates on tacrolimus dose requirements in the immediate post-transplant period in pediatric kidney and liver recipients.

Methods

Data were retrospectively collected describing tacrolimus disposition, age, CYP3A5 and ABCB1 genotype, and pediatric risk of mortality (PRISM) scores for up to 14 days post-transplant in children receiving liver and renal transplants. Initial TAC dosing was equal in all patients and adjusted using therapeutic drug monitoring. We determined the relationship between covariates and tacrolimus disposition.

Results

Forty-eight kidney and 42 liver transplant recipients (median ages 11.5 and 1.5 years, ranges 1.5–17.7 and 0.05–14.8 years, respectively) received TAC post-transplant. In both transplant groups, younger children (<5 years) needed higher TAC doses than older children [kidney: 0.15 (0.07–0.35) vs. 0.09 (0.02–0.20) mg/kg/12h, p = 0.046, liver: 0.12 (0.04–0.32) vs. 0.09 (0.01–0.18) mg/kg/12h, p = 0.038]. In kidney but not liver transplants, CYP3A5 expressors needed significantly higher TAC doses than nonexpressors [0.15 (0.07–0.20) vs. 0.09 (0.02–0.35) mg/kg/12h, P = 0.001]. In these patients, age and CYP3A5 genotype were independently associated with TAC dosing requirement. In liver, but not kidney transplant patients, homozygous ABCB1 T-T-T haplotype carriers needed higher TAC doses than noncarriers [0.26 (0.15–0.32) vs. 0.11 (0.01–0.25) mg/kg/12h, p = 0.013].

Conclusion

CYP3A5 genotype may explain variation in tacrolimus disposition early after transplant in pediatric kidney recipients, independent of age-related variation. In contrast, in pediatric liver recipients, variation in tacrolimus disposition appears related to age and ABCB1 genotype. These findings illustrate the importance of the interplay among age, genotype, and transplant organ on tacrolimus disposition.

Effect of ABCB1 genotype on pre- and post-cardiac transplantation plasma lipid concentrations

Genetic variation of ATP-binding cassette subfamily B member 1 (ABCB1) which encodes P-glycoprotein (P-gp) has been associated with lipid levels and response to statins. Here, we studied these associations in patients with advanced heart failure who subsequently underwent transplantation. Fasting total cholesterol (TC), low density lipoprotein (LDL) cholesterol, high density lipoprotein (HDL) cholesterol and triglycerides (TG) concentrations in 268 adult heart transplant recipients were analysed retrospectively before and at 1 year after transplantation (n = 176). ABCB1 genotyping and haplotyping for C1236T, G2677T/A and C3435T was performed using polymerase chain reaction. Pre-transplant LDL cholesterol was found to be associated with the C3435T genotype and the G2677T/A-C3435T and C1236T-G2677T/A-C3435T haplotypes. T-allele carriers at all loci (n = 77) had higher LDL levels than non-T-allele carriers (n = 24, 3.5 ± 1.2 vs. 2.8 ± 1.2 mmol/L, respectively, p = 0.025). This association remained after adjustment for age, sex, body mass index, statin use and underlying ischaemic heart disease. ABCB1 genotype was not associated with post-transplant lipid parameters. Hypercholesterolaemia (TC >5.7 mmol/L) was more prevalent post-transplant than pre-transplant (51% vs. 30%, respectively) and was likely related to steroid and calcineurin inhibitor use. Muscle-related statin effects were only seen in patients possessing the T-haplotype. In conclusion, an association between ABCB1 haplotype and plasma fasting LDL cholesterol concentration was found in patients with advanced heart failure. This association was not seen 1 year after cardiac transplantation.

Pharmacogenetic interactions between ABCB1 and SLCO1B1 tagging SNPs and the effectiveness of statins in the prevention of myocardial infarction

AIMS

Genetic variability within the SLCO1B1 and ABCB1 transporter genes has been associated with modification of statin effectiveness in cholesterol management.

MATERIALS & METHODS

We conducted a case-control study using a population-based registry of pharmacy records linked to the hospital discharge records. Within a hypercholesterolemic cohort, we included 668 myocardial infarction cases and 1217 controls.

RESULTS

We tested 24 tagging SNPs and found two SNPs within ABCB1 (rs3789244, p = 0.01; rs1922242, p = 0.01) to interact with statin treatment. In addition, we found a nonsignificant haplotype-treatment interaction (p = 0.054). The odds ratio for subjects homozygous for SLCO1B1*1A was 0.49 (95% CI: 0.34-0.71) compared with 0.31 (95% CI: 0.24-0.41) for heterozygous or noncarriers of the *1A allele.

CONCLUSION

This is the first study to demonstrate that common genetic variability within the SLCO1B1 and ABCB1 genes is associated with the modification of the effectiveness of statins in the prevention of the clinical outcome, myocardial infarction.