The influence of SLCO1B1 (OATP1B1) gene polymorphisms ... - Nature

The Pharmacogenomics Journal (2010) 10, 1–11 & 2010 Nature Publishing Group All rights reserved 1470-269X/10 $32.00 www.nature.com/tpj

REVIEW

The influence of SLCO1B1 (OATP1B1) gene polymorphisms on response to statin therapy SPR Romaine1, KM Bailey1, AS Hall2 and AJ Balmforth1 1 Division of Cardiovascular and Diabetes Research, Leeds Institute of Genetics, Health and Therapeutics, University of Leeds, Leeds, UK and 2 Multidisciplinary Cardiovascular Research Centre (MCRC), Leeds Institute of Genetics, Health and Therapeutics, University of Leeds, Leeds, UK

Correspondence: SPR Romaine, Division of Cardiovascular and Diabetes Research, Leeds Institute of Genetics, Health and Therapeutics, The LIGHT Laboratories, University of Leeds, Leeds LS2 9JT, UK. E-mail: [email protected]

Statins (3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors) are well established in the treatment of hypercholesterolaemia and the prevention of coronary artery disease. Despite this, there is wide interindividual variability in response to statin therapy, in terms of both lipidlowering and adverse drug reactions. The major site of statin action is within hepatocytes and recent interest has focussed on genetic variation in hepatic influx and efflux transporters for their potential to explain these differences. In this review we explore current literature regarding the pharmacokinetic and pharmacodynamic influence of the common c.388A4G and c.521T4C single-nucleotide polymorphisms (SNPs) within the solute carrier organic anion transporter 1B1 (SLCO1B1) gene, encoding the organic anion transporter polypeptide 1B1 (OATP1B1) influx transporter. We discuss their potential to predict the efficacy of statin therapy and the likelihood that patients will experience adverse effects. The Pharmacogenomics Journal (2010) 10, 1–11; doi:10.1038/tpj.2009.54; published online 3 November 2009 Keywords: cholesterol; myopathy; polymorphism; SLCO1B1; statin; transporter

Introduction Coronary artery disease is the most common cause of death in the United States, accounting for 1 in every 5 deaths.1 The 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) are established and widely prescribed in the treatment of hypercholesterolaemia and prevention of coronary artery disease.2 Despite their widespread use, there is large inter-individual variability in lipidlowering response to statins.2 Although this may partly be due to environmental and dietary factors, it is suggested that single-nucleotide polymorphisms (SNPs), or other DNA sequence variations, in genes encoding a number of drug metabolizing enzymes or transporters, may also contribute.2,3 The following review will explore the current literature regarding the potential influence of two common SNPs in the solute carrier organic anion transporter 1B1 (SLCO1B1) gene. This gene codes for a hepatic influx transporter, organic anion transporter polypeptide 1B1 (OATP1B1), thought to play a key role in statin transport into hepatocytes. Statin therapy

Received 23 April 2009; revised 15 September 2009; accepted 28 September 2009; published online 3 November 2009

Increased serum low-density lipoprotein cholesterol (LDL-C) is a significant risk factor in the development of coronary artery disease. Although dietary intake of fats often has the largest influence on an individual’s cholesterol level, de novo synthesis can also contribute. As a result, prevention and treatment of coronary

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artery disease places significant emphasis on lifestyle changes, including dietary advice and smoking cessation.4 In addition, statins have become established in the first-line treatment of hyperlipidaemia.4 They have proven both safe and effective in many large primary and secondary prevention trials.5 Despite this, there is wide inter-individual response to statins, with one study suggesting that only a third of patients reach LDL-C targets, falling to only 18% of coronary artery disease patients.6 In addition, as with any drug, a number of patients can be expected to suffer from adverse drug reactions. The majority of adverse effects are relatively minor such as gastrointestinal disturbance. However, potentially serious adverse events can occur, the most common of which is myopathy, a broad term used to describe any muscle symptom or pathology.7 Statin-associated myopathy can range from mild myalgia to severe rhabdomyolysis. Observational studies suggest that 10–15% of patients may experience muscle aches at some point during treatment.7 Although clinically benign, the occurrence of such symptoms is of great clinical importance, as they may affect a patient’s quality of life and result in decreased adherence to potentially life-saving medication.8 Fortunately, severe rhabdomyolysis (a clinical diagnosis characterized by muscle symptoms and marked elevation of serum creatinine kinase (typically 10  upper limit of normal) and the presence of urinary myoglobin) is rare, with an estimated incidence (for all statins combined) of 1.6 cases per 100 000 person-years.9 The mechanism by which statins increase the risk of myopathy is yet to be fully elucidated (see Vaklavas et al.10 for a detailed review of recent literature). In brief, three proposed mechanisms are frequently cited, each relating to decreased production of intermediate metabolites in biosynthetic pathways downstream of statin-mediated 3-hydroxy-3-methylglutaryl coenzyme A inhibition. First, decreased cholesterol levels within myocyte membranes are proposed to alter membrane function. Second, decreased production of ubiquinone (coenzyme Q10) is suggested to cause abnormal mitochondrial respiratory function. However, both these mechanisms are lacking robust scientific evidence.10 In contrast, support is stronger for the third mechanism—myofibre apoptosis mediated by decreased levels of key isoprenoids, such as farnesyl pyrophosphate and geranyl pyrophosphate.10 Although the exact mechanism for myopathy development is unclear, it is more widely accepted that clinical efficacy and the development of adverse reactions are related to hepatic and plasma concentration of statins, respectively.3 Unfortunately, there is currently no method of predicting which patients are at risk of treatment failure or adverse drug reactions, except for avoiding concomitant medication with known interacting drugs such as cyclosporine (INN, ciclosporin)11—for a detailed review of drug interactions with statins, including both their mechanisms and clinical effect, see Neuvonen et al.12 Therefore, genetic markers that are predictive of response to statin therapy or development of adverse drug reactions would be of huge clinical utility.3,13 Research in the field of pharmacogenetics aims to achieve this.

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Pharmacogenetics and statin response Statins work by inhibiting the conversion of 3-hydroxy-3methylglutaryl coenzyme A to mevalonate, the rate-limiting step in cholesterol synthesis. Inhibition occurs within hepatocytes and therefore factors that influence statin concentration in the liver are likely to affect their cholesterol-lowering abilities. Anything that modifies the way statins are absorbed, distributed, metabolized or excreted has the potential to alter their hepatic concentration, including the environment, diet and concomitant medication. Pharmacogenetics investigates the role of genetics in determining an individual’s response to a drug. It was initially thought that metabolism was the key determinant of drug disposition.14 More recently, however, the role of SNPs in drug transporters has been investigated.15 Hepatic transporters Statins are taken orally and access to their site of action in the liver is greatly facilitated by both intestinal and hepatic transport.13 Similarly, excretion into bile is also assisted by transporters. The extent to which individual statins rely on transporters to cross lipid membranes is yet to be fully elucidated—earlier suggestions that it may be dependent on lipophilicity16 have recently been questioned.17,18 Nevertheless, it has been suggested that a number of transporters may have a role in the disposition of statins, as illustrated in Figure 1. The strongest evidence exists for the influx transporter OATP1B1 (SLCO1B1; discussed below). Interestingly, studies of the closely related OATP1B3 (SLCO1B3; also expressed exclusively in the liver) and OATP2B1 (SLCO2B1) transporters are rare. Although atorvastatin, fluvastatin, pravastatin and rosuvastatin have been shown to be in vitro substrates, there are no studies showing an association between SNPs in these transporters and in vivo response to statins.15,19,20 Of the efflux transporters, breast cancer resistance protein (BCRP; ABCG2), multidrug resistance-associated protein 2 (MRP2; ABCC2) and P-glycoprotein (P-GP; MDR1, ABCB1) have been the most widely studied, although often not in the context of statin transport.15 For example, the role of permeability glycoprotein in the efflux of chemotherapeutic agents from cancer cells has long been established but its role in the disposition of different statins remains unclear.3,21–23 Similarly, in vitro studies of multidrug resistanceassociated protein 2 have shown that this protein transports a number of statins,24 but in vivo pharmacogenomic evidence is inconclusive and limited to two small pharmacokinetic studies using pravastatin; these studies obtained contrasting results.25,26 In contrast, the c.421C4A SNP in ABCG2 has been shown to alter the in vivo pharmacokinetics of both rosuvastatin27,28 and atorvastatin,27 although not pitavastatin29 or pravastatin.26 Both multidrug resistanceassociated protein 2 and breast cancer resistance protein are reviewed elsewhere by Ieiri et al.19 and although it is accepted that these and other transporters, both intestinal and hepatic, may play a role in statin disposition, this review

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Figure 1 Schematic diagram of uptake and efflux transporters expressed on human hepatocytes capable of drug, bile acid (BA) and organic anion (OA) transport. The transporter that is reviewed in this paper is shaded in black and labeled in white. ATP, adenosine triphosphate; BCRP, breast cancer resistance protein; BSEP, bile salt export pump; MDR, multiple drug resistance; MRP, multidrug resistance protein; NTCP, Na þ /taurocholate cotransporter; OAT, organic anion transporter; OATP, organic anion transporter polypeptide; OCT, organic cation transporter; P-GP, permeability glycoprotein; SLCO, solute carrier organic anion transporter. Image and legend adapted with permission from Macmillan Publishers Ltd: Clinical Pharmacology and Therpautics,14 copyright (2004).

will focus exclusively on OATP1B1, an hepatic influx transporter that is becoming increasing linked with differences in response to statin therapy. Organic anion transporter polypeptide 1B1 (OATP1B1) Organic anion transporter polypeptide 1B1 is a member of the OATPs, previously known as OATP2, OATP-C, liverspecific transporter 1 and SLC21A6. Under current nomenclature, the gene is known as SLCO1B1 and the protein as OATP1B1.14 Several studies have shown OATP1B1 to be expressed exclusively on the basolateral (sinusoidal) membrane of hepatocytes.30,31 OATP1B1 is known to transport a number of endogenous and exogenous substances, including bile acids, thyroid hormones and methotrexate,14 and has also been shown to transport many statins, including atorvastatin,16 cerivastatin,32 pravastatin30 and rosuvastatin.33 It is less clear whether simvastatin is transported by OATP1B1. It seems that the inactive parent drug (simvastatin lactone) is not,16,34 but the active acid form (formed through non-enzymatic and carboxylesterase-mediated conversion within the plasma, liver and intestinal muscosa) is an OATP1B1 substrate.30,34 A number of SNPs have been found within the SLCO1B1 gene, located on chromosome 12. SNPs that result in an amino-acid change are more likely to have an effect on function and are termed non-synonymous. Tirona et al.35

identified 14 non-synonymous SNPs, represented by 16 distinct haplotypes, named SLCO1B1*b to SLCO1B1*14 (reference haplotype ¼ SLCO1B1*1a). Since then, a further haplotype, *15, has also been identified. Of the 14 SNPs identified, only three occurred at a frequency of 40.02 in Caucasian individuals: c.388A4G, c.463C4A and c.521T4C. Of these, only c.388A4G (rs2306283) and c.521T4C (rs4149056) are associated with altered transport function (discussed below). It is these two SNPs that have been analysed most thoroughly. Table 1 shows allele frequencies of the c.388A4G and c.521T4C polymorphisms in Caucasian, African-American and Japanese populations. A comprehensive review of the global distribution of these, and other SLCO1B1 SNPs, is also available.39 The SNPs, c.388A4G and c.521T4C, occur alone or in combination with each other in three haplotypes: SLCO1B1*1b, *5 and *15. Table 2 reports the nucleotide and amino acid changes present in each haplotype. The effects of these SNPs and haplotypes on statin transport function has been well analysed and has used a number of approaches, both pharmacokinetic and pharmacodynamic. In vitro pharmacokinetic studies Tirona et al.35 used transfected HeLa cells to show that there was comparable transport of the recognized substrates estrone-3-sulphate (E1S) and estradiol 17b-D-glucuronide

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Table 1 The allele frequencies of solute carrier organic anion transporter 1B1 (SLCO1B1) c.388A4G and c.521T4C in Caucasian, African-American and Japanese populations SNP

Allele frequencies

c.388A4G (rs2306283)

Caucasian

African-American

0.38 0.51

0.77

Study Japanese

0.63 0.46 0.74

c.521T4C (rs4149056)

0.41 0.30 0.15 0.22

0.74 0.74 0.01 0.16

0.20 0.19 0.15 0.16 0.14

Table 2 The nucleotide and amino acid changes present in the *1a, *1b, *5 and *15 haplotypes of solute carrier organic anion transporter 1B1 (SLCO1B1) Haplotype

Nucleotide change(s)

Amino acid change(s)

*1a *1b *5 *15

Wild type c.388A4G c.521T4C c.388A4G; c.521T4C

Wild type p.Asn130Asp p.Val174Ala p.Asn130Asp; p.Val174Ala

(E217bG) between OATP1B1*1a and *1b proteins (see Table 3). However, they observed significantly impaired transport by the OATP1B1*5 protein compared with OATP1B1*1a (Po0.001). No differences were observed in the total expressed protein level of each variant transporter but cell surface biotinylation illustrated ‘remarkably reduced’ cell surface expression of OATP1B1*5. However, a percentage or significance level was not provided and the results for OATP1B1*1b were also not reported. Similar results were obtained by Ho et al.41 who observed comparable transport of rosuvastatin between OATP1B1*1a and *1b, but significantly decreased transport by OATP1B1*5 and OATP1B1*15. They also found a lack of relationship between SLCO1B1 mRNA and OATP1B1 protein in human liver samples and isolated hepatocyte suspensions. Although the two studies reported above are in general agreement, two similar studies conducted using HEK293 cells have reported different results. As above, similar transport activity was found for OATP1B1*1a and *1b using E1S42 and E217bG.43 However, both studies failed to show decreased transport for OATP1B1*5.42,43 In addition, both studies found that OATP1B1*1a, *1b and *5 were localized to the cell surface membrane, and Iwai et al.43 observed reduced transport function for OATP1B1*15 as compared with *1a.

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0.04 0.02

Ho et al.26 Lee et al.36 Nishizato et al.37 Pasanen et al.38 Pasanen et al.39 Thompson et al.40 Tirona et al.35 Ho et al.26 Lee et al.36 Nishizato et al.37 Pasanen et al.38 Pasanen et al.39 Tachibana-Iimori et al.4 Thompson et al.40 Tirona et al.35

Table 3 A summary of the in vitro transport function of organic anion transporter polypeptide 1B1 haplotypes *1b, *5 and *15 compared with the reference haplotype (*1a) Transport activity vs *1a Cell type Substrate *1b

*5

*15

2 2 2 2 2 m 2 2 2 2 2 2 2 m k

k k k 2 2 k k k k k k 2 — — —

— — k — k k k k k k k 2 — — —

HeLa HeLa HEK293 HEK293 HeLa HEK293 HeLa HEK293 HeLa HeLa HeLa MDCKII MDCKII MDCKII

E1S E217bG Rosuvastatin E1S E217bG E1S E1S E217bG E217bG Atorvastatin Pravastatin Simvastatin E217bG BSP C-tau

Study

Tirona et al.35 Ho et al.41 Nozawa et al.42 Iwai et al.43 Kameyama et al.16

Michalski et al.44

Abbreviations: m, increased transport activity; 2, unchanged transport activity; k, decreased transport activity; —, not investigated; BSP, bromosulfophthalein; C-tau, cholyltaurine; E1S, estrone-3-sulphate; E217bG, estradiol 17b-D-glucuronide; MDCKII, Madin-Darby canine kidney cells strain II.

Although these two sets of results may seem contradictory, it is likely that differences between the two cells types (HeLa and HEK293) are the source of the discrepancy. It is suggested that the intrinsic transporting activity of OATP1B1*5 remains in both cell types, but an in vivo alteration in membrane trafficking may lead to impaired functional expression in HEK293 cells.42 It is interesting to note, however, that the only study with a similar design conducted using both cell types showed that OATP1B1*5

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and *15 showed significantly decreased transport of E1S and E217bG in both HeLa and HEK293 cells (Po0.001) and reduced cell surface expression in HEK293 cells.16 Furthermore, this study also observed that OATP1B1*5 and OATP1B1*15 transfected HeLa cells showed reduced transport of both atorvastatin and pravastatin, but not simvastatin.16 Finally, this study also provides further information about the transport activity of OATP1B1*1b — for E1S and E217bG in HEK293 cells and for the majority of substrates (E217bG, atorvastatin, pravastatin and simvastatin) in transfected HeLa cells, the transport activity of OATP1B1*1b was not significantly different to that of *1a. However, an increase in transport activity in comparison with *1a was observed for E1S in HeLa cells, suggesting that the effect of *1b may be substrate specific. This is supported by the findings of Michalski et al.44 who, in concordance with the above studies,16,35,43 observed comparable transport of E217bG between OATP1B1*1a and OATP1B1*b transfected Madin-Darby canine kidney II cells, but increased transport of bromosulphophthalein and decreased transport of cholyltaurine in OATP1B1*1b compared with *1a transfected cells. Therefore, in summary, the in vitro evidence suggests that OATP1B1*1b is likely to have a similar transport activity to the reference haplotype (*1a), although this may be substrate dependent, as illustrated in Table 3. It also seems likely that both OATP1B1*5 and *15 show significantly reduced transport activity as a result of in vivo trafficking errors. However, in vitro studies in cell types different to those of interest in vivo cannot be considered to be sound evidence. In addition, only two of these studies16,41 used statins as OATP1B1 substrates. Therefore, the results of in vivo studies using statins must be considered (see Table 4).

In vivo pharmacokinetic studies Pasanen et al.18 analysed the pharmacokinetics of atorvastatin and rosuvastatin in 32 healthy Caucasian individuals genotyped for SLCO1B1 c.521T4C. Individuals with genotype CC had a significantly higher area under the plasma concentration-time curve (AUC)(048 h) of atorvastatin than those genotyped TT (144%; Po0.001) or TC (61%; P ¼ 0.049) when administered a single dose of 20 mg atorvastatin. TCgenotyped individuals also had a 52% higher atorvastatin AUC(048 h) compared with TT (P ¼ 0.040). This suggests that both heterozygous (TC) and homozygous (CC) carriers of the c.521T4C substitution show decreased uptake of atorvastatin into the liver, resulting in increased plasma concentration. These findings are supported by Ho et al.,26 who investigated pravastatin. However, this did not hold true when Pasanen et al.18 Investigated rosuvastatin and found that although the CC genotype resulted in a significant increase in AUC(048 h) compared with TT (65%; P ¼ 0.002), only a strong trend was shown for TC versus TT (P ¼ 0.053). These results suggest that a gene-dose effect may be present with this SNP and that although it is likely that a single copy of the c.521C allele may impair in vivo statin

transport to some degree, smaller studies may not be able to detect a significant pharmacokinetic difference. This suggestion is supported by studies using single doses of 40 mg pravastatin46 and 40 mg rosuvastatin (Caucasian subgroup).36 Further support is also provided by diplotype analysis studies, using pravastatin26 and pitavastatin.17,29 These show that the presence of a single *15 haplotype is associated with a significant decrease in hepatic uptake, an effect that is enhanced by having two copies of this haplotype. Therefore, although it is not proven whether two copies of the variant allele are required to observe a significant effect, these results suggest that the SLCO1B1 c.521T4C SNP impairs the hepatic uptake of atorvastatin, pitavastatin, pravastatin and rosuvastatin. However, it does not seem to influence fluvastatin plasma concentration — Niemi et al.46 found no significant differences in fluvastatin AUC(0N) between TT versus CC or TT versus TC genotyped individuals. Indeed, although nonsignificant trends were observed (increase in fluvastatin AUC(0N) for CC vs TT ¼ 19.1%; TC vs TT ¼ 13.4%), in relative terms these were much smaller than the results observed with atorvastatin, pravastatin and rosuvastatin.18,36,46 Similarly, nonsignificant trends have been observed for simvastatin lactone.34 Interestingly, in contrast, Pasanen et al.34 showed significant increases in the simvastatin acid AUC(0N) for CC individuals when compared with both TT (221%; Po0.001) and TC (162%; Po0.001) individuals, although a significant increase in AUC(0N) for TC compared with TT individuals was not observed (23%; P40.05). Importantly, it is the acid form of this drug that is active, leading the researchers to suggest that the SLCO1B1 c.521T4C SNP may result in decreased cholesterol-lowering efficacy and an increased risk of adverse drug reactions with simvastatin therapy. This has recently been confirmed by the high-profile publication of a strong association between SLCO1B1 genotype and statininduced myopathy (discussed below).47 A noticeable weakness in the applicability of the above results to differences in patients’ response to statins is that each study uses only a single statin administration. In response to this, Igel et al.45 conducted a repeated-dose pharmacokinetic study. Participants were grouped by SLCO1B1 genotype and given a daily dose of pravastatin (40 mg) for 3 weeks. All the participants in the control group (n ¼ 8) had the *1a/*1a diplotype. The variant group contained three heterozygous carriers of the *15 allele, four heterozygous carriers of a *17 allele (*15 þ the promoter SNP g.-11187G4A) and one homozygous carrier of the *17 allele. Participants in the variant group had a mean AUC(010 h) 110% higher than those in the control group (P ¼ 0.012). As the *17 allele can be considered a subtype of the *15 allele, and therefore should not obscure its effects, these results suggest that as seven out of eight participants in the variant group carried a single copy of the *1a allele, it is likely that a single copy of the *15 allele is capable of causing a significant decrease in hepatic uptake of statins. Importantly, this study is also able to provide evidence that the decrease in transport function observed in single-dose

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*1a/*1a ¼ 26 EA and 3 AA; *1a/*15 ¼ 8 EA; *15/*15 ¼ 2 EA; TT ¼ 88; TC ¼ 17; CC ¼ 2

n ¼ 22; all male *1b/*1b ¼ 11; *1b/*15 ¼ 8; *15/*15 ¼ 3

Caucasian, n ¼ 16; all male *1a/*1a ¼ 8; *1a/*15 ¼ 3; *1a/*17 ¼ 4; *17/*17 ¼ 1 Caucasian, n ¼ 36; 31M, 5F TT ¼ 25; TC ¼ 6; CC ¼ 5; *1a/*1a ¼ 8; *1a/*15 ¼ 5; *15/*15 ¼ 4

Caucasian, n ¼ 32 TT ¼ 16 (8M, 8F); TC ¼ 12 (7M, 5F); CC ¼ 4 (3M, 1F)

Ho et al.26

Ieiri et al.29

Igel et al.45

Niemi et al.46

0–N

Pasanen et al.34 Caucasian, n ¼ 32 TT ¼ 16 (8M, 8F); TC ¼ 12 (7M, 5F); CC ¼ 4 (3M, 1F)

—

Simvastatin lactone (after simvastatin 40 mg)

Pravastatin (40 mg) Atorvastatin (20 mg)

m43.6% NS

m20.8% NS

—

— —

m13.4% NS

m19.1% NS

m116.9% Po0.05

Rosuvastatin (10 mg) m65.0% P ¼ 0.002 m57.6% P ¼ 0.053 Simvastatin acid (after m221.3% Po0.001 m22.6% NS simvastatin 40 mg)

m6.3% NS

m116.7% Po0.05

—

m208.3% Po0.01

— m38.8% Po0.05

m98.9% Po0.001 m91.7% Po0.05

—

As above.

Results adjusted for gender, body surface area and assay sensitivity; raw values for genotype analyses not provided. m77.6% Po0.01 *1b replaces *1a; all participants matched for ABCG2 (c.421CC) reference genotype, except one *15/*15 individual, who had CA genotype. m110.5% P ¼ 0.012 The *1a/*15 group also contained participants with the *17 allele. m16.9% NS Gender not specified for genotype groups. Results also available for 36 Chinese, 35 Malay and 35 Asian-Indian subjects (not shown). — Only reference ABCC2 (c.1446CC) and CYP2C9 (c.1075AA) genotypes included. — As above. — Only CYP3A5 nonexpressers (*3/*3) were included. — As above. — As above.

—

*1a/*15 vs *1a/*1a Comments

m162.0% Po0.001

*15/*15 vs *1a/*1a

— —

—

—

—

— mP ¼ 0.015

—

TC vs TT

m91.2% P ¼ 0.018 m9.6% NS m144.4% Po0.001 m51.7% P ¼ 0.040

Fluvastatin (40 mg)

Rosuvastatin (40 mg)

Pravastatin (40 mg; once daily for 21 days)

—

— mP ¼ 0.009

Pravastatin (40 mg) Pravastatin (40 mg)

Pitavastatin (2 mg)

—

CC vs TT

Pitavastatin (4 mg)

Statin

Abbreviations: m, increased transport activity; 2, unchanged transport activity; k, decreased transport activity; —, not investigated; AA, African American; AUC, area under the plasma concentration—time curve; EA, European American, F, female; M, male; NS, non significant; 0–t, time zero to time of last quantifiable concentration.

0–48 h

0–N

0–t

0–10 h

0–10 h

0–5 h

Pasanen et al.18 Caucasian, n ¼ 32 TT ¼ 16 (8M, 8F); TC ¼ 12 (7M, 5F); CC ¼ 4 (3M, 1F)

Lee et al.36

Korean, n ¼ 11; all male *1a/*1a ¼ 6; *15/*15 ¼ 5

Deng et al.17 0–N

Participants’ genotype, sex and ethnicity AUC (if stated)

Study

Table 4 A summary of the effects of variant alleles (CC or TC) and variant haplotypes (*15/*15 or *1a/*15) of organic anion transporter polypeptide 1B1 on area under the statin plasma concentration curve

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studies is also present in repeated-dose studies. Although not considered by the researchers to affect the results, it should be noted that participants in the control group were significantly older than those in the variant group (40.5 years vs 31.9 years; P ¼ 0.010). It therefore seems that the in vivo evidence supports the in vitro findings that the protein product of the *15 allele shows reduced transport function. However, it is less clear whether the activity of the *1b allele protein product is similar to that of the reference protein (*1a). Mwinyi et al.48 suggested that carriers of the *1b allele may have a 60% smaller pravastatin AUC(06 h) than those with the *1a/*1a diplotype. However, this difference was not statistically significant and 8 of the 10 carriers of the *1b allele had the diplotype *1a/*1b. Maeda et al.49 observed a similar reduction in pravastatin AUC(024 h) in *1b/*1b carriers compared with *1a/*1a carriers (65%; P ¼ 0.049) and also showed a 45% lower AUC(024 h) in *1b/*15 carriers compared with *1a/*15 carriers (P ¼ 0.024). Therefore, in contrast to the above in vitro studies,16,35,41,43 these in vivo studies using pravastatin suggest that the *1b allele confers an increased transport activity compared with *1a. However, these studies were small and used only a single statin. Consequently, larger studies using other statins are required to provide further information about the effect of the *1b allele on in vivo OATP1B1 transport function and its clinical relevance. Indeed, the substrate specificity of this SNP has been previously highlighted with two drugs from the meglitinide class of blood glucose lowering medications— Kalliokoski et al.50 observed a significant decrease in repaglinide AUC(0N) (32%; P ¼ 0.007) but not nateglinide AUC(0N) (11.5%; P40.05) for *1b/*1b carriers, compared with *1a/*1a carriers. In summary, from in vivo pharmacokinetic studies, it seems likely that a single copy of the *15 allele increases plasma AUC. This effect is more pronounced and well established when two copies of the *15 allele are present but, as with the in vitro findings, may be substrate specific (illustrated in Table 4). Although positive results have been obtained for evidence of an effect of a single *15 allele for atorvastatin, pitavastatin, pravastatin and simvastatin acid, two copies of the *15 allele may be required to observe an effect with rosuvastatin. Furthermore, no effect on fluvastatin or simvastatin lactone has been observed. Consequently, many researchers have suggested that the presence of one or two variant alleles (*5 or *15 haplotypes) would lead to an attenuated lipid-lowering response to affected statins, as less statin would be able to reach its primary site of action in the liver. Furthermore, it has been suggested that the resulting increase in statin plasma concentration may lead to increased reporting of adverse drug reactions, including myopathy.34 Pharmacodynamic studies have investigated these suggestions (see Table 5).

Pharmacodynamic studies Tachibana-Iimori et al.4 retrospectively explored the response of 66 Japanese patients to atorvastatin (n ¼ 11),

pravastatin (n ¼ 22) and simvastatin (n ¼ 33). After SLCO1B1 c.521T4C genotyping, they found that heterozygous patients (TC) showed an attenuated response to statin therapy compared with homozygous TT patients in terms of totalcholesterol reduction (16.5 vs 22.3%; Po0.05). A nonsignificant trend towards an attenuated LDL-C response in TC patients compared with TT patients was also observed (12.4 vs 29.0%; P ¼ 0.094). No significant differences were observed for high-density lipoprotein cholesterol (HDL-C) or triglycerides. Tachibana-Iimori et al.4 were unable to include any homozygous CC patients but suggested that a single copy of the c.521T4C substitution was predictive of an attenuated total-cholesterol response. However, it is not clear how long each patient was taking the prescribed statin and at which point cholesterol levels were measured. Additionally, all patients were grouped together in their analyses, making comments on the effects of this polymorphism on a single statin response impossible. The small number of patients is a further weakness of the study. In concordance, Zhang et al.52 studied 45 Chinese patients with coronary heart disease who received 20 mg pravastatin, for 30 days, and found that TC patients had an attenuated total-cholesterol lowering response compared to TT homozygotes (14.5 vs 22.4%; P ¼ 0.03). There was no significant difference observed in LDL-C, high-density lipoprotein cholesterol and triglyceride response between genotypes. In contrast, Igel et al.45 were unable to show a significant difference in SLCO1B1-mediated response after 3 weeks of pravastatin treatment (40 mg per day; n ¼ 16). However, weak trends were observed between the variant and control groups in total-cholesterol reduction (13.1 vs 19.1%; P ¼ 0.19) and LDL-C reduction (27.7 vs 32.3%; P ¼ 0.37). The researchers highlight the low statistical power of their study, and suggest that a larger study may detect a significant difference in cholesterol reduction. However, given that the SLCO1B1 c.521T4C SNP does not lead to complete loss of function, it is plausible that the larger dose of pravastatin used (40 vs 20 mg) may have obscured any effects of SLCO1B1 genotype. A larger study was conducted by Thompson et al.,40 who investigated the effects of 43 SNPs within 16 genes thought to have a role in coronary artery disease. Participants (n ¼ 2735) were taken from the Atorvastatin Comparative Cholesterol Efficacy and Safety Study and received atorvastatin, fluvastatin, lovastatin, pravastatin or simvastatin. Thompson et al.40 conducted a large number of analyses but in relation to SLCO1B1 genotype only found significant results for the effect of atorvastatin (P ¼ 0.037) and fluvastatin (P ¼ 0.0061) on raising high-density lipoprotein cholesterol levels. These significant increases were only true between homozygotes (TT vs CC). Although the reliability of these results is boosted by the large number of participants, these results may not actually be significant after correction for multiple analyses. Therefore, after analysing the effects of many statins and SLCO1B1 genotype on total cholesterol, LDL-C, high-density lipoprotein cholesterol and triglycerides, only two possibly significant results were reported. However, as with Tachibana-Iimori et al.,4 it is not clear at which stage of

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Caucasian, n ¼ 16; all male *1a/*1a ¼ 8; *1a/*15 ¼ 3; *1a/*17 ¼ 4; *17/*17 ¼ 1

Igel et al.45

Japanese, n ¼ 66; 17M, 49F TT ¼ 44, TC ¼ 20

Tachibana-Iimori et al.4 Atorvastatin (n ¼ 11) Pravastatin (n ¼ 22) Simvastatin (n ¼ 33)

Simvastatin 40 mg

Not stated

28–42 days

TChol: attenuated response associated with TC genotype (16.5%) vs TT (22.3%; Po0.05). LDL-C: nonsignificant trend towards attenuation with TC genotype (12.4%) vs TT (29.0%; P ¼ 0.094). HDL-C and TG: no differences were observed.

LDL-C: attenuated response associated with C allele (1.28% per allele; Po0.001). TChol, HDL-C and TG: not reported.

TChol, LDL-C, HDL-C and TG: no significant differences were observed between wild-type and variant haplotypes.

Lipid lowering—key findings

Pravastatin (mean dose ¼ 9.4 mg)

56 days; 1 year

Atorvastatin (10 mg) Fluvastatin (20 mg) Lovastatin (20 mg) Pravastatin (20 mg) Simvastatin (10 mg)

Response evaluated at 6, 12, 18 and 24 weeks and treatment dose increased in non-responders

HDL-C: significant increases were observed among variant allele homozygotes in the atorvastatin (P ¼ 0.037) and fluvastatin (P ¼ 0.0061) treatment arms. No differences were observed for other statins. TChol, LDL-C and TG: no differences were observed.

After 56 days, *15 carriers showed an attenuated response compared with non-carriers for both TChol (9.8 vs 20.9%; Po0.05) and LDL-C (14.1 vs 28.9%; Po0.05). After 1 year, no differences were observed. HDL-C and TG were not investigated.

Chinese, n ¼ 45; 28M, 17F. TT ¼ 36; TC ¼ 9

Pravastatin (20 mg)

30 days

TChol: Attenuated response associated with TC genotype (14.5%) vs TT (22.4%; P ¼ 0.03). LDL-C, HDL-C & TG: No differences observed

NB: 43 SNPs in 16 genes analysed for effect on TChol, LDL-C, HDL-C and TG; P-values should be interpreted with caution. Dose adjustment of nonresponding participants may have masked further genotype effects.

Caucasian, n ¼ 2454; African-American, n ¼ 160; Asian, n ¼ 36; Hispanic, n ¼ 85

NB: It is not clear whether non-responding patients had their treatment dose increased.

Japanese, n ¼ 33; 14M, 19F. *15 noncarriers ¼ 26; *15 carriers ¼ 7

Abbreviations: F, female; HDL-C, high-density lipoprotein cholesterol; HPS, Heart Protection Study; LDL-C, low-density lipoprotein cholesterol; M, male; SEARCH, Study of the Effectiveness of Additional Reductions in Cholesterol and Homocysteine; SNPs, single-nucleotide polymorphisms; TChol, total cholesterol; TG, triglycerides.

Zhang et al.52

Thompson et al.40

21 days

Treatment duration

NB: All statins were analysed together and therefore no conclusions regarding individual statins can be drawn. Dose of statin not reported.

Caucasian, n ¼ 16 660 TT ¼ 12 072; TC ¼ 4228; CC ¼ 360

SEARCH collaborative group (HPS replication cohort)47

Takane et al.51

Pravastatin (40 mg)

Statin

NB: The researchers attribute the lack of significant findings to low statistical power.

Participants’ genotype, sex and ethnicity (if stated)

Study

Table 5 A summary of the effects of variant alleles (CC or TC) and haplotypes (*15/*15 or *1a/*15) of organic anion transporter polypeptide 1B1 on the lipid-lowering response to statins

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treatment cholesterol data were obtained. Patients were administered the highest available starting dose of each statin and evaluated at 6, 12, 18 and 24 weeks. Those not achieving cholesterol-reduction goals had their dosage increased. If the study data were obtained at 24 weeks, the dose increase may have eliminated the effects of SLCO1B1 genotype, as highlighted above, attenuating its clinical relevance. Takane et al.51 reinforce the importance of knowing when cholesterol data were obtained. They conducted a retrospective analysis of 33 Japanese hypercholesterolaemic patients treated with pravastatin. After 8 weeks (mean dose ¼ 9.4 mg), they observed a significantly attenuated reduction in total cholesterol for SLCO1B1*15 carriers compared with non-carriers (9.8 vs 20.9%; Po0.05). A similar effect was also observed for LDL-C (14.1 vs 28.9%; Po0.05). However, when the analysis was repeated after 1 year of treatment, no significant differences were observed, leading the researchers to suggest that SLCO1B1 genotype is only predictive of a slower response to pravastatin treatment. Although this may explain the nonsignificant results obtained by Thompson et al.,40 the study is also liable to the same criticism—it is not clear whether patients who were not responding to their initial treatment had their dose increased, which may have eliminated the effect of SLCO1B1 polymorphisms. More robust evidence for the role of the SLCO1B1 c.521T4C SNP in predicting an attenuated response to statin therapy has recently been provided by the Study of the Effectiveness of Additional Reductions in Cholesterol and Homocysteine collaborative group, who published an analysis of data from the Heart Protection Study.53 These data suggested that among 16 660 patients taking 40 mg simvastatin for 4–6 weeks, reduction in LDL-C was 1.28% smaller per copy of the c.521C allele (Po0.001).47 Initially, these results seem to support the findings of the earlier smaller studies in suggesting that impaired transport function of OATP1B1 results in an attenuated LDL-C reduction response. However, the differences in cholesterol reduction are much smaller (1.28% per variant allele) than previously reported and with a study-wide mean LDL-C reduction of 40.57%, the clinical significance of these differences may be debated. Nevertheless, it must also be noted that all participants received simvastatin. Therefore, only limited comparisons can be made and it is possible that more clinically significant results may be obtained with other statins. In contrast, findings from the main Study of the Effectiveness of Additional Reductions in Cholesterol and Homocysteine trial47 may have much greater clinical significance. This trial recruited 12 064 patients who were randomized to 20 or 80 mg simvastatin. After an average follow-up of 6 years, investigators identified 85 individuals with myopathy, either definitive (muscle symptoms and creatinine kinase 410 times the upper limit of normal) or incipient (creatine kinase 43 times the upper limit of normal and 45 times the baseline level and alanine aminotransferase 41.7 times the baseline level, with or

without muscle symptoms). A genome-wide scan of these individuals and 90 controls (both from the 80 mg arm) revealed that a non-coding SNP in the SLCO1B1 gene (rs4363657) was strongly associated with myopathy (P ¼ 4  109).47 This SNP is in strong linkage disequilibrium with SLCO1B1 c.521T4C (r2 ¼ 0.97). Further analysis showed that carriers of a c.521C allele were found to be at a significantly increased risk of myopathy (odds ratio 4.5; 95% confidence interval 2.6–7.7). This risk further increased among homozygous CC individuals (odds ratio 16.9; 95% confidence interval 4.7–61.1).47 The association between c.521C and myopathy was replicated among participants from the Heart Protection Study53 receiving 40 mg simvastatin (P ¼ 0.004), although the relative risk per C allele was reduced (odds ratio 2.6; 95% confidence interval 1.3–5.0).47 These results provide strong evidence in support of previous suggestions34 that the c.521T4C SNP may be a highly predictive marker for the development of myopathy in patients treated with simvastatin. However, as with the previous findings, it must be remembered that both these trials included patients who received only simvastatin. Therefore, it cannot be assumed that this association will remain with other statins and further studies are required to show this. In summary, the strong pharmacokinetic evidence that SLCO1B1 genotype affects OATP1B1 transport function provides a promising suggestion that SLCO1B1 genotype may be able to predict attenuated lipid-lowering response to statin therapy. However, this effect may be substrate dependent and the pharmacodynamic evidence is mixed. Small studies have shown that carriers of a variant SLCO1B1 allele show an attenuated total or LDL-cholesterol lowering response but larger studies in the area are contradictory. Stronger evidence has been provided for the role of SLCO1B1 genotype in predicting myopathy among patients receiving statin therapy, but only a single statin was used. Therefore, despite the promising results provided by the recent publication of a number of large studies, significant weaknesses mean that firm conclusions about the role of SLCO1B1 genotype in predicting attenuated cholesterol reduction or the development of myopathy for a range of statins cannot be drawn.

Conclusion The wide inter-individual response to statins is well established.2,6 It has been suggested that genetic differences in hepatic transporters may alter the exposure of statins to their site of action, altering their cholesterol-lowering ability. Although there are a large number of transporters that may have a role in statin transport (see Figure 1), only a few have been analysed. This review has focussed on one such transporter, OATP1B1, an influx transporter located exclusively on the basolateral membrane of hepatocytes. The link between SLCO1B1 genotype and statin response, although ‘intensively studied’, is still unresolved.

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In vitro pharmacokinetic studies suggest that despite a large number of detected polymorphisms, only two relatively common, non-synonymous SNPs (c.388A4G and c.521T4C) show altered transport function. The latter is present in haplotypes SLCO1B1*5 and SLCO1B1*15, both of which confer decreased transport function as a result of in vivo trafficking errors. In vivo pharmacokinetic studies support these findings and suggest that a single copy of either variant haplotype is sufficient to increase statin plasma concentration. The suggestion that this would affect cholesterol-lowering ability was confirmed by a number of small in vivo pharmacodynamic studies, but larger studies have been less conclusive with one suggesting that there is no significant relationship between SLCO1B1 genotype and cholesterol reduction40 and the other showing a strong statistically, but not necessarily clinically, significant relationship.47 Unfortunately, the first study had a significant methodological weakness — dose adjustment of nonresponding participants, which is likely to have masked the effect of the SLCO1B1 genotypes and the second included only patients who received 40 mg simvastatin, limiting comparisons with other studies. However, a much stronger link was shown between SLCO1B1 genotype and the development of myopathy but again this was among only patients who received simvastatin.47 It is therefore suggested that future research should focus on studies that directly analyse the effects of SLCO1B1 SNPs on the cholesterol-lowering abilities, and the induction of adverse drug reactions, for a wide range of statins. Large studies are required as the reviewed polymorphisms occur at low frequencies in many ethnic groups and are unlikely to explain the variation in response when considered alone. Further to this, it is noted that a small number of studies included in this review used sufficient participant numbers to enable the matching of participants for other gene polymorphisms that are thought to have a role in statin disposition. This is a significant methodological strength as it reduces the number of confounding factors and allows the effect of a single polymorphism to be reliably analysed. It is recommended that this methodology is used by future studies to eliminate the effects of SNPs in cytochrome P450 metabolizing enzymes and other hepatic transporters that are reported to alter statin response. Such studies may be capable of incorporating this information into a predictive model. Although there are likely to be a number of unquantifiable influencing factors, such as diet, it is suggested that the design of a highly predictive pharmacogenetic model of response to statin therapy is achievable and would be of significant benefit in both improving the effectiveness of treatment and reducing adverse drug reactions on an individual patient basis.

Conflict of interest The authors declare no conflict of interest.

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Acknowledgments SPRR thanks Heart Research UK who provided support in the form of a Leeds Undergraduate Research Enterprise (LURE) scholarship, and the Jean Shanks Foundation who provided support in the form of an intercalated degree bursary. KMB was supported by the Arnold Tunstall Fellowship awarded by the Leeds Teaching Hospitals Charitable Foundation.

References 1 Rosamond W, Flegal K, Friday G, Furie K, Go A, Greenlund K et al. Heart disease and stroke statistics—2007 update: a report from the American Heart Association Statistics Committee and Stroke Statistics Subcommittee. Circulation 2007; 115: e69–e171. 2 Zineh I. HMG-CoA reductase inhibitor pharmacogenomics: overview and implications for practice. Future Cardiol 2005; 1: 191–206. 3 Mangravite LM, Thorn CF, Krauss RM. Clinical implications of pharmacogenomics of statin treatment. Pharmacogenomics J 2006; 6: 360–374. 4 Tachibana-Iimori R, Tabara Y, Kusuhara H, Kohara K, Kawamoto R, Nakura J et al. Effect of genetic polymorphism of OATP-C (SLCO1B1) on lipid-lowering response to HMG-CoA reductase inhibitors. Drug Metab Pharmacokinet 2004; 19: 375–380. 5 Baigent C, Keech A, Kearney PM, Blackwell L, Buck G, Pollicino C et al. Efficacy and safety of cholesterol-lowering treatment: prospective metaanalysis of data from 90,056 participants in 14 randomised trials of statins. Lancet 2005; 366: 1267–1278. 6 Pearson TA, Laurora I, Chu H, Kafonek S. The lipid treatment assessment project (L-TAP): a multicenter survey to evaluate the percentages of dyslipidemic patients receiving lipid-lowering therapy and achieving low-density lipoprotein cholesterol goals. Arch Intern Med 2000; 160: 459–467. 7 Harper CR, Jacobson TA. The broad spectrum of statin myopathy: from myalgia to rhabdomyolysis. Curr Opin Lipidol 2007; 18: 401–408. 8 Joy TR, Hegele RA. Narrative review: statin-related myopathy. Ann Intern Med 2009; 150: 858–868. 9 Law M, Rudnicka AR. Statin safety: a systematic review. Am J Cardiol 2006; 97: 52C–60C. 10 Vaklavas C, Chatzizisis YS, Ziakas A, Zamboulis C, Giannoglou GD. Molecular basis of statin-associated myopathy. Atherosclerosis 2009; 202: 18–28. 11 Armitage J. The safety of statins in clinical practice. Lancet 2007; 370: 1781–1790. 12 Neuvonen PJ, Niemi M, Backman JT. Drug interactions with lipidlowering drugs: mechanisms and clinical relevance. Clin Pharmacol Ther 2006; 80: 565–581. 13 Mangravite LM, Krauss RM. Pharmacogenomics of statin response. Curr Opin Lipidol 2007; 18: 409–414. 14 Kim RB. 3-Hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (statins) and genetic variability (single nucleotide polymorphisms) in a hepatic drug uptake transporter: what’s it all about? Clin Pharmacol Ther 2004; 75: 381–385. 15 Maeda K, Sugiyama Y. Impact of genetic polymorphisms of transporters on the pharmacokinetic, pharmacodynamic and toxicological properties of anionic drugs. Drug Metab Pharmacokinet 2008; 23: 223–235. 16 Kameyama Y, Yamashita K, Kobayashi K, Hosokawa M, Chiba K. Functional characterization of SLCO1B1 (OATP-C) variants, SLCO1B1*5, SLCO1B1*15 and SLCO1B1*15+C1007G, by using transient expression systems of HeLa and HEK293 cells. Pharmacogenet Genomics 2005; 15: 513–522. 17 Deng JW, Song IS, Shin HJ, Yeo CW, Cho DY, Shon JH et al. The effect of SLCO1B1*15 on the disposition of pravastatin and pitavastatin is substrate dependent: the contribution of transporting activity changes by SLCO1B1*15. Pharmacogenet Genomics 2008; 18: 424–433. 18 Pasanen MK, Fredrikson H, Neuvonen PJ, Niemi M. Different effects of SLCO1B1 polymorphism on the pharmacokinetics of atorvastatin and rosuvastatin. Clin Pharmacol Ther 2007; 82: 726–733. 19 Ieiri I, Higuchi S, Sugiyama Y. Genetic polymorphisms of uptake (OATP1B1, 1B3) and efflux (MRP2, BCRP) transporters: implications for inter-individual differences in the pharmacokinetics and pharmacodynamics of statins and

SLCO1B1 polymorphisms and statin therapy SPR Romaine et al

11

20 21

22

23 24

25

26

27

28

29

30

31

32

33

34

35

36

other clinically relevant drugs. Expert Opin Drug Metab Toxicol 2009; 5: 703–729. Niemi M. Role of OATP transporters in the disposition of drugs. Pharmacogenomics 2007; 8: 787–802. Keskitalo JE, Kurkinen KJ, Neuvoneni PJ, Niemi M. ABCB1 haplotypes differentially affect the pharmacokinetics of the acid and lactone forms of simvastatin and atorvastatin. Clin Pharmacol Ther 2008; 84: 457–461. Keskitalo JE, Kurkinen KJ, Neuvonen M, Backman JT, Neuvonen PJ, Niemi M. No significant effect of ABCB1 haplotypes on the pharmacokinetics of fluvastatin, pravastatin, lovastatin, and rosuvastatin. Br J Clin Pharmacol 2009; 68: 207–213. Holtzman CW, Wiggins BS, Spinler SA. Role of P-glycoprotein in statin drug interactions. Pharmacotherapy 2006; 26: 1601–1607. Shitara Y, Sugiyama Y. Pharmacokinetic and pharmacodynamic alterations of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors: drug-drug interactions and interindividual differences in transporter and metabolic enzyme functions. Pharmacol Ther 2006; 112: 71–105. Niemi M, Arnold KA, Backman JT, Pasanen MK, Godtel-Armbrust U, Wojnowski L et al. Association of genetic polymorphism in ABCC2 with hepatic multidrug resistance-associated protein 2 expression and pravastatin pharmacokinetics. Pharmacogenet Genomics 2006; 16: 801–808. Ho RH, Choi L, Lee W, Mayo G, Schwarz UI, Tirona RG et al. Effect of drug transporter genotypes on pravastatin disposition in European- and AfricanAmerican participants. Pharmacogenet Genomics 2007; 17: 647–656. Keskitalo JE, Zolk O, Fromm MF, Kurkinen KJ, Neuvonen PJ, Niemi M. ABCG2 polymorphism markedly affects the pharmacokinetics of atorvastatin and rosuvastatin. Clin Pharmacol Ther 2009; 86: 197–203. Zhang W, Yu BN, He YJ, Fan L, Li Q, Liu ZQ et al. Role of BCRP 421C4A polymorphism on rosuvastatin pharmacokinetics in healthy Chinese males. Clin Chim Acta 2006; 373: 99–103. Ieiri I, Suwannakul S, Maeda K, Uchimaru H, Hashimoto K, Kimura M et al. SLCO1B1 (OATP1B1, an uptake transporter) and ABCG2 (BCRP, an efflux transporter) variant alleles and pharmacokinetics of pitavastatin in healthy volunteers. Clin Pharmacol Ther 2007; 82: 541–547. Hsiang B, Zhu Y, Wang Z, Wu Y, Sasseville V, Yang WP et al. A novel human hepatic organic anion transporting polypeptide (OATP2). Identification of a liver-specific human organic anion transporting polypeptide and identification of rat and human hydroxymethylglutaryl-CoA reductase inhibitor transporters. J Biol Chem 1999; 274: 37161– 37168. Ito K, Suzuki H, Horie T, Sugiyama Y. Apical/basolateral surface expression of drug transporters and its role in vectorial drug transport. Pharm Res 2005; 22: 1559–1577. Shitara Y, Hirano M, Sato H, Sugiyama Y. Gemfibrozil and its glucuronide inhibit the organic anion transporting polypeptide 2 (OATP2/OATP1B1:SLC21A6)-mediated hepatic uptake and CYP2C8mediated metabolism of cerivastatin: analysis of the mechanism of the clinically relevant drug-drug interaction between cerivastatin and gemfibrozil. J Pharmacol Exp Ther 2004; 311: 228–236. Brown CDA, Windass A, Bleasby K, Lauffart B. Rosuvastatin is a high affinity substrate of hepatic organic anion transporter OATP-C (abstract). Atheroscler Suppl 2001; 2: 90. Pasanen MK, Neuvonen M, Neuvonen PJ, Niemi M. SLCO1B1 polymorphism markedly affects the pharmacokinetics of simvastatin acid. Pharmacogenet Genomics 2006; 16: 873–879. Tirona RG, Leake BF, Merino G, Kim RB. Polymorphisms in OATP-C: identification of multiple allelic variants associated with altered transport activity among European- and African-Americans. J Biol Chem 2001; 276: 35669–35675. Lee E, Ryan S, Birmingham B, Zalikowski J, March R, Ambrose H et al. Rosuvastatin pharmacokinetics and pharmacogenetics in white and

37

38

39 40

41

42

43

44

45

46

47

48

49

50

51

52

53

Asian subjects residing in the same environment. Clin Pharmacol Ther 2005; 78: 330–341. Nishizato Y, Ieiri I, Suzuki H, Kimura M, Kawabata K, Hirota T et al. Polymorphisms of OATP-C (SLC21A6) and OAT3 (SLC22A8) genes: consequences for pravastatin pharmacokinetics. Clin Pharmacol Ther 2003; 73: 554–565. Pasanen MK, Backman JT, Neuvonen PJ, Niemi M. Frequencies of single nucleotide polymorphisms and haplotypes of organic anion transporting polypeptide 1B1 SLCO1B1 gene in a Finnish population. Eur J Clin Pharmacol 2006; 62: 409–415. Pasanen MK, Neuvonen PJ, Niemi M. Global analysis of genetic variation in SLCO1B1. Pharmacogenomics 2008; 9: 19–33. Thompson JF, Man M, Johnson KJ, Wood LS, Lira ME, Lloyd DB et al. An association study of 43 SNPs in 16 candidate genes with atorvastatin response. Pharmacogenomics J 2005; 5: 352–358. Ho RH, Tirona RG, Leake BF, Glaeser H, Lee W, Lemke CJ et al. Drug and bile acid transporters in rosuvastatin hepatic uptake: function, expression, and pharmacogenetics. Gastroenterology 2006; 130: 1793–1806. Nozawa T, Nakajima M, Tamai I, Noda K, Nezu J, Sai Y et al. Genetic polymorphisms of human organic anion transporters OATP-C (SLC21A6) and OATP-B (SLC21A9): allele frequencies in the Japanese population and functional analysis. J Pharmacol Exp Ther 2002; 302: 804–813. Iwai M, Suzuki H, Ieiri I, Otsubo K, Sugiyama Y. Functional analysis of single nucleotide polymorphisms of hepatic organic anion transporter OATP1B1 (OATP-C). Pharmacogenetics 2004; 14: 749–757. Michalski C, Cui Y, Nies AT, Nuessler AK, Neuhaus P, Zanger UM et al. A naturally occurring mutation in the SLC21A6 gene causing impaired membrane localization of the hepatocyte uptake transporter. J Biol Chem 2002; 277: 43058–43063. Igel M, Arnold KA, Niemi M, Hofmann U, Schwab M, Lutjohann D et al. Impact of the SLCO1B1 polymorphism on the pharmacokinetics and lipid-lowering efficacy of multiple-dose pravastatin. Clin Pharmacol Ther 2006; 79: 419–426. Niemi M, Pasanen MK, Neuvonen PJ. SLCO1B1 polymorphism and sex affect the pharmacokinetics of pravastatin but not fluvastatin. Clin Pharmacol Ther 2006; 80: 356–366. Link E, Parish S, Armitage J, Bowman L, Heath S, Matsuda F et al. SLCO1B1 variants and statin-induced myopathy—a genomewide study. N Engl J Med 2008; 359: 789–799. Mwinyi J, Johne A, Bauer S, Roots I, Gerloff T. Evidence for inverse effects of OATP-C (SLC21A6) 5 and 1b haplotypes on pravastatin kinetics. Clin Pharmacol Ther 2004; 75: 415–421. Maeda K, Ieiri I, Yasuda K, Fujino A, Fujiwara H, Otsubo K et al. Effects of organic anion transporting polypeptide 1B1 haplotype on pharmacokinetics of pravastatin, valsartan, and temocapril. Clin Pharmacol Ther 2006; 79: 427–439. Kalliokoski A, Backman JT, Neuvonen PJ, Niemi M. Effects of the SLCO1B1*1B haplotype on the pharmacokinetics and pharmacodynamics of repaglinide and nateglinide. Pharmacogenet Genomics 2008; 18: 937–942. Takane H, Miyata M, Burioka N, Shigemasa C, Shimizu E, Otsubo K et al. Pharmacogenetic determinants of variability in lipid-lowering response to pravastatin therapy. J Hum Genet 2006; 51: 822–826. Zhang W, Chen BL, Ozdemir V, He YJ, Zhou G, Peng DD et al. SLCO1B1 521T-C functional genetic polymorphism and lipid-lowering efficacy of multiple-dose pravastatin in Chinese coronary heart disease patients. Br J Clin Pharmacol 2007; 64: 346–352. Heart Protection Study Collaborative Group. MRC/BHF heart protection study of cholesterol lowering with simvastatin in 20,536 high-risk individuals: a randomised placebo-controlled trial. Lancet 2002; 360: 7–22.

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