Interaction of novel platelet-increasing agent eltrombopag with rosuvastatin via breast cancer resistance protein in humans

A comprehensive pharmacogenomic study indicates roles for SLCO1B1, ABCG2 and SLCO2B1 in rosuvastatin pharmacokinetics

AIMS

The aim was to comprehensively investigate the effects of genetic variability on the pharmacokinetics of rosuvastatin.

METHODS

We conducted a genome-wide association study and candidate gene analyses of single dose rosuvastatin pharmacokinetics in a prospective study (n = 159) and a cohort of previously published studies (n = 88).

RESULTS

In a genome-wide association meta-analysis of the prospective study and the cohort of previously published studies, the SLCO1B1 c.521 T > C (rs4149056) single nucleotide variation (SNV) associated with increased area under the plasma concentration-time curve (AUC) and peak plasma concentration of rosuvastatin (P = 1.8 × 10^-12 and P = 3.2 × 10^-15 ). The candidate gene analysis suggested that the ABCG2 c.421C > A (rs2231142) SNV associates with increased rosuvastatin AUC (P = .0079), while the SLCO1B1 c.388A > G (rs2306283) and SLCO2B1 c.1457C > T (rs2306168) SNVs associate with decreased rosuvastatin AUC (P = .0041 and P = .0076). Based on SLCO1B1 genotypes, we stratified the participants into poor, decreased, normal, increased and highly increased organic anion transporting polypeptide (OATP) 1B1 function groups. The OATP1B1 poor function phenotype associated with 2.1-fold (90% confidence interval 1.6-2.8, P = 4.69 × 10^-5 ) increased AUC of rosuvastatin, whereas the OATP1B1 highly increased function phenotype associated with a 44% (16-62%; P = .019) decreased rosuvastatin AUC. The ABCG2 c.421A/A genotype associated with 2.2-fold (1.5-3.0; P = 2.6 × 10^-4 ) increased AUC of rosuvastatin. The SLCO2B1 c.1457C/T genotype associated with 28% decreased rosuvastatin AUC (11-42%; P = .01).

CONCLUSION

These data suggest roles for SLCO1B1, ABCG2 and SLCO2B1 in rosuvastatin pharmacokinetics. Poor SLCO1B1 or ABCG2 function genotypes may increase the risk of rosuvastatin-induced myotoxicity. Reduced doses of rosuvastatin are advisable for patients with these genotypes.

Classification of drugs for evaluating drug interaction in drug development and clinical management

During new drug development, clinical drug interaction studies are carried out in accordance with the mechanism of potential drug interactions evaluated by in vitro studies. The obtained information should be provided efficiently to medical experts through package inserts and various information materials after the drug's launch. A recently updated Japanese guideline presents general procedures that are considered scientifically valid at the present moment. In this review, we aim to highlight the viewpoints of the Japanese guideline and enumerate drugs that were involved or are anticipated to be involved in evident pharmacokinetic drug interactions and classify them by their clearance pathway and potential intensity based on systematic reviews of the literature. The classification would be informative for designing clinical studies during the development stage, and the appropriate management of drug interactions in clinical practice.

Febuxostat, But Not Allopurinol, Markedly Raises the Plasma Concentrations of the Breast Cancer Resistance Protein Substrate Rosuvastatin

Xanthine oxidase inhibitors febuxostat and allopurinol are commonly used in the treatment of gout. Febuxostat inhibits the breast cancer resistance protein (BCRP) in vitro. Rosuvastatin is a BCRP substrate and genetic variability in BCRP markedly affects rosuvastatin pharmacokinetics. In this study, we investigated possible effects of febuxostat and allopurinol on rosuvastatin pharmacokinetics. In a randomized crossover study with 3 phases, 10 healthy volunteers ingested once daily placebo for 7 days, 300 mg allopurinol for 7 days, or placebo for 3 days, followed by 120 mg febuxostat for 4 days, and a single 10 mg dose of rosuvastatin on day 6. Febuxostat increased the peak plasma concentration and area under the plasma concentration‐time curve of rosuvastatin 2.1‐fold (90% confidence interval 1.8–2.6; P = 5 × 10⁻⁵) and 1.9‐fold (1.5–2.5; P = 0.001), but had no effect on rosuvastatin half‐life or renal clearance. Allopurinol, on the other hand, did not affect rosuvastatin pharmacokinetics. In vitro, febuxostat inhibited the ATP‐dependent uptake of rosuvastatin into BCRP‐overexpressing membrane vesicles with a half‐maximal inhibitory concentration of 0.35 µM, whereas allopurinol showed no inhibition with concentrations up to 200 µM. Taken together, the results suggest that febuxostat increases rosuvastatin exposure by inhibiting its BCRP‐mediated efflux in the small intestine. Febuxostat may, therefore, serve as a useful index inhibitor of BCRP in drug‐drug interaction studies in humans. Moreover, concomitant use of febuxostat may increase the exposure to BCRP substrate drugs and, thus, the risk of dose‐dependent adverse effects.

Prediction of Clinical Transporter-Mediated Drug-Drug Interactions via Comeasurement of Pitavastatin and Eltrombopag in Human Hepatocyte Models

A structurally identifiable micro‐rate constant mechanistic model was used to describe the interaction between pitavastatin and eltrombopag, with improved goodness‐of‐fit values through comeasurement of pitavastatin and eltrombopag. Transporter association and dissociation rate constants and passive rates out of the cell were similar between pitavastatin and eltrombopag. Translocation into the cell through transporter‐mediated uptake was six times greater for pitavastatin, leading to pronounced inhibition of pitavastatin uptake by eltrombopag. The passive rate into the cell was 91 times smaller for pitavastatin compared with eltrombopag. A semimechanistic physiologically‐based pharmacokinetic (PBPK) model was developed to evaluate the potential for clinical drug–drug interactions (DDIs). The PBPK model predicted a twofold increase in the pitavastatin peak blood concentration and area under the concentration‐time curve in the presence of eltrombopag in simulated healthy volunteers. The use of structural identifiability supporting experimental design combined with robust micro‐rate constant parameter estimates and a semimechanistic PBPK model gave more informed predictions of transporter‐mediated DDIs.

Dose-Dependent Inhibition of OATP1B by Rifampicin in Healthy Volunteers: Comprehensive Evaluation of Candidate Biomarkers and OATP1B Probe Drugs

To address the most appropriate endogenous biomarker for drug–drug interaction risk assessment, eight healthy subjects received an organic anion transporting polypeptide 1B (OATP1B) inhibitor (rifampicin, 150, 300, and 600 mg), and a probe drug cocktail (atorvastatin, pitavastatin, rosuvastatin, and valsartan). In addition to coproporphyrin I, a widely studied OATP1B biomarker, we identified at least 4 out of 28 compounds (direct bilirubin, glycochenodeoxycholate‐3‐glucuronide, glycochenodeoxycholate‐3‐sulfate, and hexadecanedioate) that presented good sensitivity and dynamic range in terms of the rifampicin dose‐dependent change in area under the plasma concentration‐time curve ratio (AUCR). Their suitability as OATP1B biomarkers was also supported by the good correlation of AUC_0‐24h between the endogenous compounds and the probe drugs, and by nonlinear regression analysis (AUCR⁻¹ vs. rifampicin plasma C_max (maximum total concentration in plasma)) to yield an estimate of the inhibition constant of rifampicin. These endogenous substrates can complement existing OATP1B‐mediated drug–drug interaction risk assessment approaches based on agency guidelines in early clinical trials.

Development of precision medicine approaches based on inter-individual variability of BCRP/ABCG2

Precision medicine is a rapidly-developing modality of medicine in human healthcare. Based on each patient׳s unique characteristics, more accurate dosages and drug selection can be made to achieve better therapeutic efficacy and less adverse reactions in precision medicine. A patient׳s individual parameters that affect drug transporter action can be used to develop a precision medicine guidance, due to the fact that therapeutic efficacy and adverse reactions of drugs can both be affected by expression and function of drug transporters on the cell membrane surface. The purpose of this review is to summarize unique characteristics of human breast cancer resistant protein (BCRP) and the genetic variability in the BCRP encoded gene ABCG2 in the development of precision medicine. Inter-individual variability of BCRP/ABCG2 can impact choices and outcomes of drug treatment for several diseases, including cancer chemotherapy. Several factors have been implicated in expression and function of BCRP, including genetic, epigenetic, physiologic, pathologic, and environmental factors. Understanding the roles of these factors in controlling expression and function of BCRP is critical for the development of precision medicine based on BCRP-mediated drug transport.

Pharmacokinetic Drug Interaction Between Rosuvastatin and Tanjin in Healthy Volunteers and Rats

Background

Tanjin is an herbal medicine made from the root of salvia miltiorrhiza. It is predominantly given to arteriosclerotic patients as a supplement to ameliorate the clinical symptoms of cardiovascular diseases. In China, tanjin is used frequently in combination treatment for hypercholesterolemia. Thus, there is a high probability of combination of tanjin and statins in these arteriosclerotic patients. This study investigated the interaction between tanjin and rosuvastatin.

Methods

We performed a randomized single-blind, two-period crossover clinical trial on six healthy male volunteers. Volunteers were administered rosuvastatin with placebo or a tanjin-containing drug randomly. The blood samples were collected before drug administration, and at 0.5, 1, 1.5, 2, 4, 8, and 12 hours after administration. Lymphocytes were isolated from blood samples before and 12 hours after drug administration to measure mRNA. As an animal experiment, an in situ intestinal injection with portal vein sampling model was used to examine the interaction between tanjin and rosuvastatin during the absorption phase. Rosuvastatin or rosuvastatin combined with tanjin solution was injected into the intestine. After injection, blood from the portal vein was collected and the concentration of rosuvastatin was measured by LC/MS/MS analysis. A portion of the intestine and liver from the rats was collected and stored at -80°C for mRNA measurement.

Results

In the clinical trial, co-administration of tanjin decreased the maximum plasma concentration (C_max) of rosuvastatin by 26.85% compared with rosuvastatin alone, and also decreased the area under the plasma concentration-time curve of rosuvastatin from 0 to 12 h (AUC_0-12) by 19.43%. The relative expression of BCRP and OATP mRNA in human lymphocytes was increased by co-administration of tanjin. In the animal experiment, co-administration of tanjin extract reduced the concentration of rosuvastatin to 84.4, 64.4, and 50.0% at 15, 30, and 45 minutes, respectively. The tanjin-containing drug had a similar effect to tanjin extract. Furthermore, tanjin significantly reduced the absorption of rosuvastatin and the inhibitory effects lasted for at least 24 hours. Tanjin increased the relative expression of BCRP mRNA in the intestine, but it did not change the expression of OATP. Moreover, the concentration of rosuvastatin in the portal vein and systemic blood was reduced. In the liver, tanjin increased both BCRP and OATP mRNA expression, which was consistent with the results from human lymphocytes.

Conclusion

The clinical trial and animal experiment revealed that tanjin can significantly reduce the absorption of rosuvastatin. This interaction occurred, at least, at the absorption phase in the small intestine due to the enhanced efflux transport. Thus, as tanjin and rosuvastatin were found to interact, their combination needs to be paid attention to.

ABCG2/BCRP: variants, transporter interaction profile of substrates and inhibitors

INTRODUCTION

ABCG2 has a broad substrate specificity and is one of the most important efflux proteins modulating pharmacokinetics of drugs, nutrients and toxicokinetics of toxicants. ABCG2 is an important player in transporter-mediated drug-drug interactions (tDDI). Areas covered: The aims of the review are i) to cover transporter interaction profile of substrates and inhibitors that can be utilized to test interaction of drug candidates with ABCG2, ii) to highlight main characteristics of in vitro testing and iii) to describe the structural basis of the broad substrate specificity of the protein. Preclinical data utilizing Abcg2/Bcrp1 knockouts and clinical studies showing effect of ABCG2 c.421C>A polymorphism on pharmacokinetics of drugs have provided evidence for a broad array of drug substrates and support drug - ABCG2 interaction testing. A consensus on using rosuvastatin and sulfasalazine as intestinal substrates for clinical studies is in the formation. Other substrates relevant to the therapeutic area can be considered. Monolayer efflux assays and vesicular transport assays have been extensively utilized in vitro. Expert opinion: Clinical substrates display complex pharmacokinetics due to broad interaction profiles with multiple transporters and metabolic enzymes. Substrate-dependent inhibition has been observed for several inhibitors. Harmonization of in vitro and in vivo testing makes sense. However, rosuvastatin and sulfasalazine are not efficiently transported in either MDCKII or LLC-PK1-based monolayers. Caco-2 monolayer assays and vesicular transport assays are potential alternatives.

The Role of Platelets in the Tumor-Microenvironment and the Drug Resistance of Cancer Cells

Besides the critical functions in hemostasis, thrombosis and the wounding process, platelets have been increasingly identified as active players in various processes in tumorigenesis, including angiogenesis and metastasis. Once activated, platelets can release bioactive contents such as lipids, microRNAs, and growth factors into the bloodstream, subsequently enhancing the platelet⁻cancer interaction and stimulating cancer metastasis and angiogenesis. The mechanisms of treatment failure of chemotherapeutic drugs have been investigated to be associated with platelets. Therefore, understanding how platelets contribute to the tumor microenvironment may potentially identify strategies to suppress cancer angiogenesis, metastasis, and drug resistance. Herein, we present a review of recent investigations on the role of platelets in the tumor-microenvironment including angiogenesis, and metastasis, as well as targeting platelets for cancer treatment, especially in drug resistance.

Eltrombopag for use in children with immune thrombocytopenia

Eltrombopag is currently the only US Food and Drug Administration-approved thrombopoietin receptor agonist for the treatment of chronic immune thrombocytopenia (ITP) in children. This oral, once-per-day therapy has shown favorable efficacy and adverse effect profiles in children. Two multicenter, double-blind, placebo controlled clinical trials (PETIT [Efficacy and Safety Study of Eltrombopag in Pediatric Patients With Thrombocytopenia From Chronic Idiopathic Thrombocytopenic Purpura (ITP)] and PETIT2 [Study of a New Medication for Childhood Chronic Immune Thrombocytopenia (ITP), a Blood Disorder of Low Platelet Counts That Can Lead to Bruising Easily, Bleeding Gums, and/or Bleeding Inside the Body]) demonstrated efficacy in raising platelet counts, reducing bleeding, and reducing the need for concomitant ITP therapies with relatively few adverse effects. The most commonly reported drug-related adverse effects include headache, nausea, and hepatobiliary laboratory abnormalities. Long-term safety data in children are limited, and studies in adults have not revealed a clinically significant increased incidence of thrombosis, marrow fibrosis, or cataract formation. Eltrombopag has also been approved for treating refractory severe aplastic anemia (AA) and has potential for expanded use in ITP and severe AA as well as in other conditions associated with thrombocytopenia.

Effect of Ursolic Acid on Breast Cancer Resistance Protein-mediated Transport of Rosuvastatin In Vivo and Vitro

OBJECTIVE

To evaluate whether ursolic acid can inhibit breast cancer resistance protein (BCRP)-mediated transport of rosuvastatin in vivo and in vitro.

METHODS

Firstly, we explored the pharmacokinetics of 5-fluorouracil (5-FU, a substrate of BCRP) in rats in the presence or absence of ursolic acid. Secondly, we studied the pharmacokinetics of rosuvastatin in rats in the presence or absence of ursolic acid or Ko143 (inhibitor of BCRP). Finially, the concentration-dependent transport of rosuvastatin and the inhibitory effects of ursolic acid and Ko143 were examined in Madin-Darby Canine Kidney (MDCK) 2-BCRP421CC (wild type) cells and MDCK2-BCRP421AA (mutant type) cells.

RESULTS

As a result, significant changes in pharmacokinetics parameters of 5-FU were observed in rats following pretreatment with ursolic acid. Both ursolic acid and Ko143 could significantly affect the pharmacokinetics of rosuvastatin. The rosuvastatin transport in the BCRP overexpressing system was increased in a concentration-dependent manner. However, there was no statistical difference in BCRP-mediated transport of rosuvastatin betweent the wild type cells and mutant cells. The same as Ko143, ursolic acid inhibited BCRP-mediated transport of rosuvastatin in vitro.

CONCLUSION

Ursolic acid appears to be a potent modulator of BCRP that affects the pharmacokinetic of rosuvastatin in vivo and inhibits the transport of rosuvastatin in vitro.

Drug-drug interactions that interfere with statin metabolism

INTRODUCTION

Lipid-lowering drugs, especially hydroxymethylglutaryl-CoA reductase inhibitors (statins), are widely used in the treatment and prevention of atherosclerotic diseases. The benefits of statins are well documented. However, myotoxic side effects, which can sometimes be severe, including myopathy or rhabdomyolysis, have been associated with the use of statins. In some cases, this toxicity is associated with pharmacokinetic alterations. Potent inhibitors of CYP 3A4 significantly increase plasma concentrations of the active forms of simvastatin, lovastatin and atorvastatin. Fluvastatin is metabolized by CYP2C9, while pravastatin, rosuvastatin and pitavastatin are not susceptible to inhibition by any CYP.

AREAS COVERED

This review discusses the pharmacokinetic aspects of the drug-drug interaction with statins and genetic polymorphisms in CYPs, which are involved in the metabolism of statins, and highlights the importance of establishing a system utilizing electronic medical information practically to avoid adverse drug reactions.

EXPERT OPINION

An understanding of the mechanisms underlying statin interactions will help to minimize drug interactions and develop statins that are less prone to adverse interactions. Quantitatively analyzed information for the low-density lipoprotein cholesterol lowering effects of statin based on electronic medical records may be useful for avoiding the adverse effect of statins.

The Use of Transporter Probe Drug Cocktails for the Assessment of Transporter-Based Drug-Drug Interactions in a Clinical Setting-Proposal of a Four Component Transporter Cocktail

Probe drug cocktails are used clinically to assess the potential for drug-drug interactions (DDIs), and in particular, DDIs resulting from coadministration of substrates and inhibitors of cytochrome P450 enzymes. However, a probe drug cocktail has not been identified to assess DDIs involving inhibition of drug transporters. We propose a cocktail consisting of the following substrates to explore the potential for DDIs caused by inhibition of key transporters: digoxin (P-glycoprotein, P-gp), rosuvastatin (breast cancer resistance protein, BCRP; organic anion transporting polypeptides, OATP), metformin (organic cation transporter, OCT; multidrug and toxin extrusion transporters, MATE), and furosemide (organic anion transporter, OAT). Furosemide was evaluated in vitro, and is a substrate of OAT1 and OAT3, with Km values of 38.9 and 21.5 μM, respectively. Furosemide was also identified as a substrate of BCRP, OATP1B1, and OATP1B3. Furosemide inhibited BCRP (50% inhibition of drug transport: 170 μM), but did not inhibit OATP1B1, OATP1B3, OCT2, MATE1, and MATE2-K at concentrations below 300 μM, and P-gp at concentrations below 2000 μM. Conservative approaches for the estimation of the likelihood of in vivo DDIs indicate a remote chance of in vivo transporter inhibition by these probe drugs when administered at low single oral doses. This four component probe drug cocktail is therefore proposed for clinical evaluation.

Role of the breast cancer resistance protein (BCRP/ABCG2) in drug transport--an update

The human breast cancer resistance protein (BCRP, gene symbol ABCG2) is an ATP-binding cassette (ABC) efflux transporter. It was so named because it was initially cloned from a multidrug-resistant breast cancer cell line where it was found to confer resistance to chemotherapeutic agents such as mitoxantrone and topotecan. Since its discovery in 1998, the substrates of BCRP have been rapidly expanding to include not only therapeutic agents but also physiological substances such as estrone-3-sulfate, 17β-estradiol 17-(β-D-glucuronide) and uric acid. Likewise, at least hundreds of BCRP inhibitors have been identified. Among normal human tissues, BCRP is highly expressed on the apical membranes of the placental syncytiotrophoblasts, the intestinal epithelium, the liver hepatocytes, the endothelial cells of brain microvessels, and the renal proximal tubular cells, contributing to the absorption, distribution, and elimination of drugs and endogenous compounds as well as tissue protection against xenobiotic exposure. As a result, BCRP has now been recognized by the FDA to be one of the key drug transporters involved in clinically relevant drug disposition. We published a highly-accessed review article on BCRP in 2005, and much progress has been made since then. In this review, we provide an update of current knowledge on basic biochemistry and pharmacological functions of BCRP as well as its relevance to drug resistance and drug disposition.