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

Effect of SLCO1B1 c.521T>C polymorphism on the lipid response to statins in people living with HIV on a boosted protease inhibitor-containing regimen

AIMS

We previously observed that some individuals on HIV boosted protease inhibitor-containing regimen do not achieve their lipid targets despite elevated statin concentrations. This study evaluated whether the common single polymorphism c.521T>C in SLCO1B1, associated with reduced statin uptake in the liver, could explain this observation.

METHODS

People living with HIV in the Swiss HIV Cohort Study were eligible if they were on a boosted protease inhibitor concomitantly with a statin for at least 6 months and if their SLCO1B1 genotype was available. Furthermore, their lipids had to be documented before and after the introduction of the statin. The statin efficacy was defined as % change in total cholesterol, low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol and triglycerides levels after statin initiation compared to pretreatment levels. Lipid response was adjusted for differences in potency and dose between statins.

RESULTS

In total, 88 people living with HIV were included, of whom 58, 28 and 2 carried the SLCO1B1 TT, TC and CC genotypes, respectively. The change in lipid levels after statin initiation tended to be lower in carriers of the polymorphism although the difference was not statistically significant (TT vs. TC/CC: total cholesterol: -11.7 vs. -4.8%; low-density lipoprotein- cholesterol: -20.6 vs. -7.4%; high-density lipoprotein-cholesterol: 1.6 vs. 0%; triglycerides: -11.5 vs. -7.9%). In the multiple linear regression, change in total cholesterol was inversely correlated with the total cholesterol level prestatin treatment (coefficient -6.60, 95% confidence interval: -9.63 to -3.56, P < .001).

CONCLUSION

The lipid-lowering effect of statins tended to be attenuated by SLCO1B1 polymorphism and progressively declined as total cholesterol under the boosted protease inhibitor treatment decreased.

Associations between SLCO1B1, APOE and CYP2C9 and lipid-lowering efficacy and pharmacokinetics of fluvastatin: a meta-analysis

Objective: This meta-analysis was designed to investigate the associations between SLCO1B1, APOE and CYP2C9 and the lipid-lowering effects and pharmacokinetics of fluvastatin. Methods: Studies were searched from inception to March 2023, including three SNPs related to fluvastatin, SLCO1B1, CYP2C9 and APOE. Weighted mean differences and corresponding 95% CIs were analyzed to evaluate the associations between SNPs and outcomes. Results: SLCO1B1 521T>C was associated with lower total cholesterol and low-density lipoprotein reduction. Patients carrying 521CC or total cholesterol had a significantly higher area under the curve than those carrying 521TT, but no significant difference existed. Conclusion: CYP2C9 and SLCO1B1 may be associated with the efficacy and pharmacokinetics of fluvastatin.

Pharmacogenomics of lipid-lowering agents: the impact on efficacy and safety

Hyperlipidemia is a significant risk factor for cardiovascular disease morbidity and mortality. The lipid-lowering drugs are considered the cornerstone of primary and secondary prevention of atherosclerotic cardiovascular disease. Unfortunately, the lack of efficacy and associated adverse effects, ranging from mild-to-moderate to potentially life-threatening, lead to therapy discontinuation. Numerous reports support the role of gene polymorphisms in drugs' pharmacokinetic parameters and their associated adverse reactions. Therefore, this study aims to understand the pharmacogenomics of lipid-lowering drugs and the impact of genetic variants of key genes on the drugs' efficacy and toxicity. Indeed, genetically guided lipid-lowering therapy enhances overall safety, improves drug adherence and achieves long-term therapy.

Impact of SLCO1B1*5 on Flucloxacillin and Co-Amoxiclav-Related Liver Injury

Background: Idiosyncratic drug-induced liver injury (DILI) is a serious uncommon disease that may develop as a result of the intake of certain drugs such as the antimicrobials flucloxacillin and co-amoxiclav. The reported cases showed significant associations between DILI and various human leukocyte (HLA) markers. The solute carrier organic anion transporter 1B1 (SLCO1B1), a non-HLA candidate gene, was previously reported as a risk factor for liver injury induced by rifampin and methimazole. This study presumed that SLCO1B1 may play a general role in the DILI susceptibility and therefore investigated the association of rs4149056 (SLCO1B1*5, T521C) polymorphism with flucloxacillin- and co-amoxiclav-induced liver injury. Methodology: We recruited 155 and 165 DILI cases of white ancestral origin from various European countries but mainly from the United Kingdom owing to flucloxacillin and co-amoxiclav, respectively. Only adult patients (≥18 years) who were diagnosed with liver injury and who showed i) clinical jaundice or bilirubin >2x the upper limit of normal (ULN), ii) alanine aminotransferase (ALT) >5x ULN or iii) alkaline phosphatase (ALP) >2x ULN and bilirubin > ULN were selected. The population reference sample (POPRES), a European control group (n = 282), was used in comparison with the investigated cases. TaqMan SNP genotyping custom assay designed by Applied Biosystems was used to genotype both DILI cohorts for SLCO1B1 polymorphism (rs4149056). Allelic discrimination analysis was performed using a step one real-time PCR machine. Genotype differences between cases and controls were examined using Fisher's exact test. GraphPad Prism version 5.0 was used to determine the p-value, odds ratio, and 95% confidence interval. Compliance of the control group with Hardy-Weinberg equilibrium was proven using a web-based calculator available at https://wpcalc.com/en/equilibrium-hardy-weinberg/. Results: A small number of cases failed genotyping in each cohort. Thus, only 149 flucloxacillin and 162 co-amoxiclav DILI cases were analyzed. Genotyping of both DILI cohorts did not show evidence of association with the variant rs4149056 (T521C) (OR = 0.71, 95% CI = 0.46-1.12; p = 0.17 for flucloxacillin cases and OR = 0.87, 95% CI = 0.56-1.33; p = 0.58 for co-amoxiclav), although slightly lower frequency (22.8%) of positive flucloxacillin cases was noticed than that of POPRES controls (29.4%). Conclusion: Carriage of the examined allele SLCO1B1*5 is not considered a risk factor for flucloxacillin DILI or co-amoxiclav DILI as presumed. Testing a different allele (SLCO1B1*1B) and another family member gene (SLCO1B3) may still be needed to provide a clearer role of SLCO1B drug transporters in DILI development-related to the chosen antimicrobials.

Genetic variants of SLCO1B7 are of relevance for the transport function of OATP1B3-1B7

The family of Organic Anion Transporting Polypeptides are known to facilitate the transmembrane transport. OATP1B3-1B7 is a novel member of the OATP1B-subfamily, and is encoded by SLCO1B3-SLCO1B7 readthrough deriving from the genes SLCO1B3 and SLCO1B7 on chromosome 12. The resulting protein is expressed in the smooth endoplasmatic reticulum of hepatocytes, is functional, and transports dehydroepiandrosterone-sulfate (DHEAS). In the gene area encoding for the 1B7-part of the protein, there are coding polymorphisms. It was the aim of this study to test the frequency and the impact of these genetic variants on transport activity. The minor allele frequency (MAF) of the coding polymorphisms was determined in a cohort of 192 individuals. DHEAS transport function was determined by applying the vTF-7 based heterologous expression system using plasmids encoding for OATP1B3-1B7 or the respective variants. The genetic variants 641 T (MAF 0.021), 1073 G (MAF 0.169) and 1775 A (MAF 0.013) significantly reduced DHEAS accumulation in cells transfected with OATP1B3-1B7, albeit without significantly influencing expression of the transporter as determined by Western blot analysis and immunofluorescence after heterologous expression. Genotyping revealed complete linkage of the variants 884A, 1073 G and 1501C. Presence of the haplotype abolished the DHEAS-transport function of OATP1B3-1B7. Naturally and frequently occurring genetic variants located within the gene region of SLCO1B7 encoding for the 1B7-part of OATP1B3-1B7 influence the in vitro function of this member of the OATP1B-family. With their functional characterisation, we provide the basis for pharmacogenetic studies, which may help to understand the in vivo relevance of this transporter.

The influence of genetic polymorphisms in drug metabolism enzymes and transporters on the pharmacokinetics of different fluvastatin formulations

The purpose of the present study was to investigate the impact of genetic polymorphism on fluvastatin pharmacokinetics. In addition, we compared the fluvastatin pharmacokinetics differences between extended-release (ER) 80 mg tablet and immediate-release (IR) 40 mg capsule in terms of drug metabolism enzyme and transporter genetic polymorphisms. In this open-label, randomized, two-period, two-treatment, crossover study (n = 24), effects of ABCG2, SLCO1B1, ABCB1, CYP2C9 and CYP3A5 polymorphisms on the pharmacokinetics of fluvastatin were analyzed. The administration dosage for IR 40 mg and ER 80 mg were twice and once daily, respectively, for total 7 d. Blood samples for pharmacokinetic evaluation were taken on the 1st and 7th d. The lower exposure following ER was observed. For ER tablets, SLCO1B1 T521C genotype correlated with AUC_0-24 of repeat doses (P = 0.010). SLCO1B1 T521C genotype had no statistically significant effect on AUC_0-24 of IR capsule of fluvastatin after single or repeated doses. In vitro study demonstrated that when the concentration of fluvastatin was low (< 1 µmol/l), the uptake of fluvastatin in the HEK293-OATP1B1 with SLCO1B1 521TT (K_m =0.18 µmol/l) was faster than that with SLCO1B1 521CC (K_m =0.49 µmol/l), On the other hand, when concentration reached to higher level (> 1 µmol/l), transport velocity of fluvastatin by HEK293-OATP1B1 with SLCO1B1 521TT (K_m  = 11.4 µmol/l) and with SLCO1B1 521TCC (K_m =15.1 µmol/l) tend to be the same. It suggests that the increased effect of SLCO1B1 T521C genotype on ER formulation of fluvastatin was mainly caused by lower blood concentrations. We recommend that formulation should be incorporated into future pharmacogenomics studies.

The impact of statins on physical activity and exercise capacity: an overview of the evidence, mechanisms, and recommendations

PURPOSE

Statins are among the most widely prescribed medications worldwide. Considered the 'gold-standard' treatment for cardiovascular disease (CVD), statins inhibit HMG-CoA reductase to ultimately reduce serum LDL-cholesterol levels. Unfortunately, the main adverse event of statin use is the development of muscle-associated problems, referred to as SAMS (statin-associated muscle symptoms). While regular moderate physical activity also decreases CVD risk, there is apprehension that physical activity may induce and/or exacerbate SAMS. While much work has gone into identifying the epidemiology of SAMS, only recent research has focused on the extent to which these muscle symptoms are accompanied by functional declines. The purpose of this review is to provide an overview of possible mechanisms underlying SAMS and summarize current evidence regarding the relationship between statin treatment, physical activity, exercise capacity, and SAMS development.

METHODS

PubMed and Google Scholar databases were used to search the most relevant and up-to-date peer-reviewed research on the topic.

RESULTS

The mechanism(s) behind SAMS, including altered mitochondrial metabolism, reduced coenzyme Q10 levels, reduced vitamin D levels, impaired calcium homeostasis, elevated extracellular glutamate, and genetic polymorphisms, still lack consensus and remain up for debate. Our summation of the evidence leads us to suggest that the etiology of SAMS development is likely multifactorial. Our review also demonstrates that there is limited evidence for statins impairing exercise adaptations or reducing exercise capacity for the majority of the investigated populations.

CONCLUSION

The available evidence indicates that the benefits of engaging in physical activity while on statin medication largely outweigh the risks.

Roles of Hepatic Drug Transporters in Drug Disposition and Liver Toxicity

Hepatic drug transporters are mainly distributed in parenchymal liver cells (hepatocytes), contributing to drug's liver disposition and elimination. According to their functions, hepatic transporters can be roughly divided into influx and efflux transporters, translocating specific molecules from blood into hepatic cytosol and mediating the excretion of drugs and metabolites from hepatic cytosol to blood or bile, respectively. The function of hepatic transport systems can be affected by interspecies differences and inter-individual variability (polymorphism). In addition, some drugs and disease can redistribute transporters from the cell surface to the intracellular compartments, leading to the changes in the expression and function of transporters. Hepatic drug transporters have been associated with the hepatic toxicity of drugs. Gene polymorphism of transporters and altered transporter expressions and functions due to diseases are found to be susceptible factors for drug-induced liver injury (DILI). In this chapter, the localization of hepatic drug transporters, their regulatory factors, physiological roles, and their roles in drug's liver disposition and DILI are reviewed.

The association between the SLCO1B1, apolipoprotein E, and CYP2C9 genes and lipid response to fluvastatin: a meta-analysis

OBJECTIVE

The aim of this study was to determine the impact of the SLCO1B1, apolipoprotein E (ApoE), and CYP2C9 genotypes on the lipid-lowering efficacy of fluvastatin.

METHODS

We performed electronic searches on the PubMed, Embase, and Cochrane Library databases to identify studies published through October 2017. Studies that reported the effect estimates with 95% confidence intervals (CIs) of total cholesterol (TC), triglyceride, low-density lipoprotein (LDL), and high-density lipoprotein were included so that the different genotype categories could be compared. Weighted mean difference (WMD) was used to summarize the effect estimates.

RESULTS

Six studies, involving a total of 1171 individuals, were included in the final analysis. We noted that the patient carrier SLCO1B1 521TT was associated with greater change in TC (WMD: -2.98; 95% CI: -5.12 to -0.84; P=0.006) and LDL (WMD: -5.58; 95% CI: -10.64 to -0.52; P=0.031) compared with 521TC or CC. Furthermore, the patient carrier ApoE*2/*3 showed more change in high-density lipoprotein compared with ApoE*3/*3 (WMD: 18.76; 95% CI: 8.97-28.55; P<0.001) and ApoE*3/*4 or *4/*4 (WMD: 22.51; 95% CI: 0.98-44.04; P=0.040). Finally, the CYP2C9 genotypes showed no correlation with the effects of fluvastatin on TC, triglyceride, and LDL.

CONCLUSION

The findings of this study suggested that the SLCO1B1 and ApoE polymorphisms could influence the lipid-lowering effect of fluvastatin, whereas the CYP2C9 genotypes were not associated with the therapeutic effects of fluvastatin.

Enantiospecific Pharmacogenomics of Fluvastatin

The aim of this study was to investigate how variability in multiple genes related to pharmacokinetics affects fluvastatin exposure. We determined fluvastatin enantiomer pharmacokinetics and sequenced 379 pharmacokinetic genes in 200 healthy volunteers. CYP2C9*3 associated with significantly increased area under the plasma concentration-time curve (AUC) of both 3R,5S-fluvastatin and 3S,5R-fluvastatin (by 67% and 94% per variant allele copy, P = 3.77 × 10^-9 and P = 3.19 × 10^-12 ). In contrast, SLCO1B1 c.521T>C associated with increased AUC of active 3R,5S-fluvastatin only (by 34% per variant allele copy; P = 8.15 × 10^-8 ). A candidate gene analysis suggested that CYP2C9*2 also affects the AUC of both fluvastatin enantiomers and that SLCO2B1 single-nucleotide variations may affect the AUC of 3S,5R-fluvastatin. Thus, SLCO transporters have enantiospecific effects on fluvastatin pharmacokinetics in humans. Genotyping of both CYP2C9 and SLCO1B1 may be useful in predicting fluvastatin efficacy and myotoxicity.

The influences of SLCO1B1 and ABCB1 genotypes on the pharmacokinetics of simvastatin, in relation to CYP3A4 inhibition

AIM

To investigate the combined effects of SLCO1B1 and ABCB1 genotypes on the pharmacokinetics of simvastatin and its active metabolite simvastatin acid, in relation to CYP3A4 inhibition.

METHODS

We conducted a single-dose pharmacokinetic study of simvastatin in 26 healthy volunteers screened for their SLCO1B1 c.521T>C and ABCB1 c.1236C>T-2677G>T-3435C>T genotypes, with and without amlodipine pretreatment. The genetic effects and drug-interaction effect on simvastatin pharmacokinetic parameters were analyzed using a linear-mixed model.

RESULTS

The SLCO1B1 c.521T>C variant significantly increased exposure to simvastatin acid by around 40% (p < 0.05), similar to that caused by the amlodipine pretreatment. The ABCB1 gene showed no influence on exposure to simvastatin or simvastatin acid.

CONCLUSION

Only SLCO1B1, not ABCB1 genotype, is likely to be associated with simvastatin-induced myopathy. SLCO1B1 genotyping may be particularly beneficial in simvastatin users who are co-administered CYP3A4 inhibitors.

Interindividual and interethnic variability in drug disposition: polymorphisms in organic anion transporting polypeptide 1B1 (OATP1B1; SLCO1B1)

OATP1B1 (SLCO1B1) is predominantly expressed at the basolateral membrane of hepatocytes and is critically important for the hepatic uptake and clearance of numerous drug substrates and endogenous compounds. In general, the organic anion transporting polypeptides (OATP; SLCO) represent a superfamily of uptake transporters that mediate the sodium-independent transport of a diverse range of amphipathic organic compounds including bile salts, steroid conjugates, thyroid hormones, anionic peptides, numerous drugs and other xenobiotic substances. OATP1B1 is highly polymorphic and a number of relevant and ethnically dependent polymorphisms have been identified and functionally characterized. In particular, the SLCO1B1 521T>C and 388A>G polymorphisms are commonly occurring variants in ethnically diverse populations and numerous in vitro and clinical studies have evaluated the consequences of these variants to interindividual differences in drug disposition and response. OATP1B1 is particularly important for the disposition of HMG-CoA reductase inhibitors, or statins, as it is known to efficiently transport most statins to their site of action within hepatocytes. Many studies have focused on the consequences of OATP1B1 variants to statin disposition in vitro and in vivo and would suggest that genetic variability in SLCO1B1 has important implications for statin pharmacokinetics, risk for statin-induced myopathy, and modulation of statin treatment response. This review describes what is currently known regarding SLCO1B1 genotype, OATP1B1 protein expression and interindividual and interethnic consequences to drug disposition, with particular focus on statin pharmacokinetics and implications for drug response and toxicity.

A genetic risk score is significantly associated with statin therapy response in the elderly population

The ability of statins to strongly reduce low-density lipoprotein cholesterol (LDL-C) varies interindividually and is partially influenced by genetic variants. Based on a comprehensive analysis of 23 single nucleotide polymorphisms (SNPs) known to be associated with pharmacokinetics and dynamics of statins, we developed a genetic risk score to study its impact on the therapy outcome in elderly individuals under at least 5 years statin therapy. The study was performed in a population-based cohort of 1016 elderly individuals, which comprised 168 statin users investigated at age 75 and 80. Using random forest models, the major variants influencing LDL-C levels were summarized in a weighted GRS (wGRS). The wGRS was tested with lipid and glucose outcomes and validated in an independent population-based cohort including 221 statin users. Four SNPs within the APOE cluster (rs7412, rs4420638), ABCC2 (rs2002042) and CELSR/SORT1/PSRC1 (rs646776), displayed a major impact on statin efficacy. The wGRS was significantly associated with lower LDL-C at age 75 and 80. This association was replicated displaying similar results. GRS analysis is a powerful tool to evaluate the additive effects of genetic variants on statin response and to estimate the magnitude of LDL-C reduction to a considerable extent in the older population.

Differences in genetic variants in lopinavir disposition among HIV-infected Bantu Africans

INTRODUCTION

Variability in lopinavir (LPV) plasma concentration among patients could be due to genetic polymorphisms. This study set to evaluate significance of variants in CYP3A4/5, SLCO1B1 and ABCC2 on LPV plasma concentration among African HIV-positive patients.

MATERIALS & METHODS

Eighty-six HIV-positive participants on ritonavir (LPV/r) were genetically characterized and LPV plasma concentration determined.

RESULTS & DISCUSSION

LPV plasma concentrations differed >188-fold (range 0.0206-38.6 µg/ml). Both CYP3A4*22 and SLCO1B1 rs4149056G (c.521C) were not observed in this cohort. CYP3A4*1B, CYP3A5*3, CYP3A5*6 and ABCC2 c.1249G>A which have been associated with LPV plasma concentration, showed no significant association.

CONCLUSION

These findings highlight the need to include African groups in genomics research to identify variants of pharmacogenomics significance.

Drug Transporters and Na+/H+ Exchange Regulatory Factor PSD-95/Drosophila Discs Large/ZO-1 Proteins

Drug transporters govern the absorption, distribution, and elimination of pharmacologically active compounds. Members of the solute carrier and ATP binding-cassette drug transporter family mediate cellular drug uptake and efflux processes, thereby coordinating the vectorial movement of drugs across epithelial barriers. To exert their physiologic and pharmacological function in polarized epithelia, drug transporters must be targeted and stabilized to appropriate regions of the cell membrane (i.e., apical versus basolateral). Despite the critical importance of drug transporter membrane targeting, the mechanisms that underlie these processes are largely unknown. Several clinically significant drug transporters possess a recognition sequence that binds to PSD-95/Drosophila discs large/ZO-1 (PDZ) proteins. PDZ proteins, such as the Na(+)/H(+) exchanger regulatory factor (NHERF) family, act to stabilize and organize membrane targeting of multiple transmembrane proteins, including many clinically relevant drug transporters. These PDZ proteins are normally abundant at apical membranes, where they tether membrane-delimited transporters. NHERF expression is particularly high at the apical membrane in polarized tissue such as intestinal, hepatic, and renal epithelia, tissues important to drug disposition. Several recent studies have highlighted NHERF proteins as determinants of drug transporter function secondary to their role in controlling membrane abundance and localization. Mounting evidence strongly suggests that NHERF proteins may have clinically significant roles in pharmacokinetics and pharmacodynamics of several pharmacologically active compounds and may affect drug action in cancer and chronic kidney disease. For these reasons, NHERF proteins represent a novel class of post-translational mediators of drug transport and novel targets for new drug development.

Insights into solute carriers: physiological functions and implications in disease and pharmacokinetics

SLCs transport many endogenous and exogenous compounds including drugs; SLCs dysfunction has implications in pharmacokinetics, drug toxicity or lack of efficacy.