Assessment of effects of repeated oral doses of fedratinib on inhibition of cytochrome P450 activities in patients with solid tumors using a cocktail approach.

PURPOSE: Fedratinib, an oral selective kinase inhibitor with activity against both wild type and mutationally activated Janus kinase 2, has been approved for the treatment of adult patients with intermediate-2 or high-risk myelofibrosis by the US Food and Drug Administration. In vitro studies indicated that fedratinib was an inhibitor of several cytochrome P450 (CYP) enzymes. The primary objective of this study was to evaluate the effects of repeated doses of fedratinib on the activity of CYP2D6, CYP2C19, and CYP3A4 in patients with solid tumors using a CYP probe cocktail. METHODS: An open-label, one-sequence, two-period, two-treatment crossover study was conducted. Patients were administered a single oral dose cocktail of metoprolol (100 mg), omeprazole (20 mg), and midazolam (2 mg) used as probe substrates for CYP2D6, CYP2C19, and CYP3A4 enzyme activities, respectively, without fedratinib on Day -1 or with fedratinib on Day 15. RESULTS: Coadministration of 500 mg once-daily doses of fedratinib for 15 days increased the mean area under the plasma concentration-time curve from time zero to infinity following a single-dose cocktail containing metoprolol (CYP2D6 substrate), omeprazole (CYP2C19 substrate), and midazolam (CYP3A4 substrate) by 1.77-fold (90% confidence interval [CI] 1.27-2.47) for metoprolol, 2.82-fold (90% CI 2.26-3.53) for omeprazole, and 3.84-fold (90% CI 2.62-5.63) for midazolam, respectively. The mean plasma Day 14/Day 1 ratio of 4ß-hydroxycholesterol, an endogenous biomarker of CYP3A4 activity, was 0.59 (90% CI 0.54-0.66), suggesting a net inhibition of CYP3A4 by fedratinib. CONCLUSION: Fedratinib is a weak inhibitor of CYP2D6, and a moderate inhibitor of CYP2C19 and CYP3A4. These results serve as the basis for dose modifications of these CYP substrate drugs when co-administered with fedratinib.

A novel ligase chain reaction-based electrochemical biosensing strategy for highly sensitive point mutation detection from human whole blood.

Challenged by the detection of trace amounts of mutants and disturbance from endogenous substances in clinical samples, herein, we present a novel electrochemical biosensor based on ligase chain reaction (eLCR) via the thermostable ligase with high mutation recognizing ability. The lengthened double-stranded DNAs exponentially generated via LCR were uniformly distributed on a bovine serum albumin-modified gold electrode, in which the phosphate buffer was tactfully added to remove adsorbed uninterested-probes, and thereafter the amperometry current was collected for the specific binding of streptavidin-poly-HRP and subsequent catalysis in the 3, 3', 5, 5'-tetramethylbenzidine substrate that contained hydrogen peroxide. It found that, under optimized conditions, the proposed biosensor exhibited a high selectivity of mutant targets from the 104-fold excess of co-existent wild targets within a detection limit of 0.5 fM. Impressively, without the involvement of pre-PCR, the homozygous mutants were specifically distinguished from the wild genotype of CYP2C19*2 allele in human whole blood samples. Therefore, the proposed eLCR, due to its advantages in simple primer design, operational ease and ease of miniaturization, has demonstrated its considerable potential for point-of-care testing in the diagnosis of point mutation-related diseases and personalized medicine.

How do CYP2C19*2 and CYP2C19*17 genetic polymorphisms affect the efficacy and safety of diazepam in patients with alcohol withdrawal syndrome?

Background Diazepam is one of the most commonly prescribed tranquilizers for therapy of alcohol withdrawal syndrome (AWS). Despite its popularity, there is currently no precise information on the effect of genetic polymorphisms on its efficacy and safety. The objective of our study was to investigate the effect of CYP2C19*2 and CYP2C19*17 genetic polymorphisms on the efficacy and safety of diazepam in patients with AWS. Methods The study was conducted on 30 Russian male patients suffering from the AWS who received diazepam in injections at a dosage of 30.0 mg/day for 5 days. The efficacy and safety assessment was performed using psychometric scales and scales for assessing the severity of adverse drug reactions. Results Based on the results of the study, we revealed the differences in the efficacy of therapy in patients with different CYP2C19 681G>A (CYP2C19*2, rs4244285) genotypes: (CYP2C19*1/*1) -8.5 [-15.0; -5.0], (CYP2C19*1/*2 and CYP2C19*2/*2) -12.0 [-13.0; -9.0], p = 0.021. The UKU scale scores, which were used to evaluate the safety of therapy, were also different: (CYP2C19*1/*1) 7.0 [6.0; 12.0], (CYP2C19*1/*2 and CYP2C19*2/*2) 9.5 [8.0; 11.0], p = 0.009. Patients carrying different CYP2C19 -806C>T (CYP2C19*17, rs12248560) genotypes also demonstrated differences in therapy efficacy and safety rates. Conclusions Thus, the effects of CYP2C19*2 and CYP2C19*17 genetic polymorphisms on the efficacy of diazepam were demonstrated.

A PCR-lateral flow assay system based on gold magnetic nanoparticles for CYP2C19 genotyping and its clinical applications.

Presently, clopidogrel is the standard therapeutic drugs for antiplatelet therapy. Variants in the CYP2C19 gene influence the clinical response of clopidogrel. Thus, the US Food and Drug Administration suggested CYP2C19 genotyping needs to identify before taking medicine. Due to high cost, time consuming, and sophisticated instruments, current single nucleotide polymorphism detection methods are limited in clinical application. In the present study, we established a genotyping method for CYP2C19, which combines amplification refractory mutation system (ARMS)-PCR with a lateral flow assay used gold magnetic nanoparticles (GMNPs) named as PCR-gold magnetic lateral flow assay system (PCR-GoldMag LFA). The PCR products with specific genotype can be explained within 5 minutes, either through visual or by a magnetic reader automatically according to the captured GMNPs probes on the test lines of the LFA strips. The limit of detection of this method is 5 ng of genomic DNA. The PCR-GoldMag LFA system was applied in a clinical trial with 1356 samples of Han Chinese. The concordance rate between the LFA system and sequencing is 99.93%. The allele frequency of CYP2C19*2 and CYP2C19*3 are 30.38 and 7.08% in Han Chinese, respectively. This method provides a new way in the clinical application of CYP2C19 genotyping to guide the clopidogrel medication.

Clinical Utility of CYP2C19 Genotyping to Guide Antiplatelet Therapy in Patients With an Acute Coronary Syndrome or Undergoing Percutaneous Coronary Intervention.

Current guidelines recommend dual antiplatelet therapy-a P2Y12 inhibitor (clopidogrel, prasugrel, or ticagrelor) and aspirin-for patients undergoing percutaneous coronary intervention. Although clopidogrel is the most commonly prescribed P2Y12 inhibitor, it is associated with an increased risk of major adverse cardiovascular events in patients carrying loss-of-function CYP2C19 alleles. In contrast, CYP2C19 genotype does not impact clinical response to prasugrel or ticagrelor. Nevertheless, routine implementation of CYP2C19 genotyping to guide antiplatelet therapy selection has remained controversial because of the lack of large randomized controlled trials evaluating this strategy. Emerging results from registry studies and small clinical trials of CYP2C19 genotype-guided antiplatelet therapy following percutaneous coronary intervention offer new insight and contribute to a growing evidence base that supports the clinical utility of a genotyping strategy to personalize antiplatelet therapy selection.

Vonoprazan versus proton pump inhibitors for the management of gastroesophageal reflux disease: A protocol for a systematic review with meta-analysis.

BACKGROUND AND AIM: Vonoprazan, a novel potassium-competitive acid blocking agent, is used in the management of gastroesophageal reflux disease (GERD). We aim to perform a systematic review and meta-analysis for the comparison of the effects of vonoprazan and proton pump inhibitors (PPIs) in GERD in randomized controlled trials (RCTs). METHODS: A systematic and comprehensive search will be performed using MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), Google Scholar, and clinical trial registries, for studies published up to September 2018. Only randomized clinical trials will be included. Primary outcomes of symptoms and esophageal erosion improvement in the intention-to-treat analysis, and secondary outcomes of symptoms and esophageal erosion improvement rate in the per protocol analysis, the comparative efficacy in terms of healing rate of esophageal erosion on endoscopy, the comparative efficacy in terms of improvement of esophageal impedance-pH study, adverse events, long-term safety, and the comparative efficacy in terms of CYP2C19 metabolite levels will be studied. The quality of included studies will be assessed using the modified risk of bias tool. Heterogeneity of estimates across studies as well as publication bias will be assessed. This systematic review and meta-analysis will be performed according to the protocol recommended by the Cochrane Collaboration and reported according to the preferred reporting items for systematic reviews and meta-analysis (PRISMA) guidelines. All statistical analyses will be conducted using Stata SE version 15.0. RESULTS: The results of this systematic review and meta-analysis will be published in a peer-reviewed journal. CONCLUSION: To our knowledge, this systematic review and meta-analysis will be the first to evaluate existing research comparing Vonoprazan and PPIs in GERD. Our study will provide information about the effect of vonoprazan and PPIs in GERD in RCTs. The review will benefit patients, healthcare providers, and policymakers.

An improved LC-MS/MS method for simultaneous evaluation of CYP2C9, CYP2C19, CYP2D6 and CYP3A4 activity.

AIM: To develop an LC-MS/MS assay to quantitate well-tolerated substrates; midazolam (CYP3A), omeprazole (CYP2C19), dextromethorphan (CYP2D6), losartan (CYP2C9) and their respective metabolites' concentrations in plasma samples. PATIENTS & METHODS: A solid-phase extraction method was optimized to extract analytes of interest simultaneously from human plasma samples. The assay analyzed plasma samples collected from patients who received equal or lower than therapeutic doses of CYP substrates. RESULTS: This assay was validated based on the European Medicines Agency guideline for bioanalytical method validation and was sensitive, linear, accurate and precise with acceptable recovery and matrix effects. CONCLUSION: Small sample volume and dose of cytochrome P450 substrates, short-run time, using stable isotope internal standards and being cost effective are the major advantages of the assay.

Serum derived from ulcerative colitis mouse changes the metabolism of the fluorescent substrate by P450 depending on the degree of disease progression.

Ulcerative colitis (UC) is characterized by erosions of the intestinal mucosa. The number of patients with UC has recently been increasing rapidly. Since the diagnosis of UC is complex and difficult, a simple, rapid, noninvasive technique for diagnosing UC is needed urgently. The expression of cytochrome P450 (P450 or CYP) species in mouse liver is known to be changed dependent on the disease. Various components such as P450 substrates and P450 metabolites in the blood may possibly change with the UC-specific way in mouse. In this study, in order to evaluate UC-specific components in UC mouse serum, we analyzed the influence of serum derived from UC mice on the results of fluorescent P450 inhibition assays based on 12 human P450 enzymes, such as CYP1A1, CYP2C8, CYP2E1,CYP3A4, CYP1A2, CYP2D6, CYP2A13, CYP2B6, CYP2C9, CYP2C18, CYP2C19, and CYP3A5. At first, in order to induce UC, mice received 4,4-dimethyl-4-silapentane-1-sulfonic acid (DSS) dissolved in their drinking water for 7 days. Next, these 12 human P450 enzymes were expressed in E. coli cells. Then, P450 fluorescent competition reaction was performed using these P450 enzymes and serum of UC mice. We found that the metabolism of fluorescent substrates by CYP2B6, CYP2C19, CYP2E1, and CYP1A1 in the presence of serum obtained from DSS-treated mice was activated by 42%, 37%, 37%, and 23%, respectively, relative to that associated with sera from control mice. A receiver operating characteristic (ROC) curve analysis was carried out with the 31 samples of UC mice and healthy mice. Area under the ROC curve (AUC) value was calculated from ROC curve. AUC value of CYP2E1 and CYP2C19 showed 0.921 and 0.892, respectively. Therefore, it was shown that CYP2C19 and CYP2E1 could be used as biomarkers for evaluating ulcerative colitis. From these results, it is suggested that these simple fluorescent P450 inhibition assays have potential as a new diagnostic procedure for UC in mouse. This study is the first report on a simple non-invasive method for evaluating UC using P450 enzyme and serum interaction.

Phenotypic Assessment of Drug Metabolic Pathways and P-Glycoprotein in Patients Treated With Antidepressants in an Ambulatory Setting.

OBJECTIVE: Drug-metabolizing enzymes (DMEs), such as cytochrome P450 (CYP) enzymes, and transporters have emerged as major determinants of variability in drug metabolism and response. This study investigated the association between CYP and P-glycoprotein activities and plasma antidepressant concentration in an outpatient clinical setting. Secondary outcomes were antidepressant efficacy and tolerance. We also describe phenotypes in patients treated with antidepressants and evaluate the tolerance of a minimally invasive phenotyping approach. METHODS: From January 2015 to August 2015, 64 patients on a stable antidepressant regimen underwent a simultaneous assessment of steady-state antidepressant concentration and DME (CYP1A2, CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP3A) and P-glycoprotein transporter activity using a cocktail phenotyping approach. Psychiatric diagnoses were in accordance with DSM-5. RESULTS: We observed a high proportion of subjects (> 20%) with reduced activity of CYP2C19, CYP2D6, CYP3A4, and P-glycoprotein. As expected, higher CYP activity for major metabolic pathways was associated with lower concentration of the parent compound (CYP2C19 and escitalopram, P = .025; CYP2D6 and fluoxetine, P < .001; CYP2C19 and sertraline, P = .001), higher concentration of the metabolite (CYP2D6 and O-desmethylvenlafaxine, P = .007), and higher metabolite-to-parent drug ratio (CYP2C19 and escitalopram, P = .03; CYP2D6 and fluoxetine, P < .001; CYP2C19 and sertraline, P = .048; CYP2B6 and sertraline, P = .006). Phenotyping also highlighted the relevance of a minor metabolic pathway for venlafaxine (CYP3A4). Insufficient response and adverse reactions to antidepressants were not significantly associated with plasma antidepressant concentration, DME, or P-glycoprotein activity. Tolerance of the phenotypic test in ambulatory settings was found to be excellent. CONCLUSIONS: The phenotypic assessment of DMEs and a transporter is a valuable, well-tolerated method to explore the interindividual variability in drug disposition in clinical settings. The method is able to account for the inhibitory activity of antidepressants themselves and for polymedication, which is frequent in this population of refractory depressed patients. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02438072.

Development of a Polymerase Chain Reaction/Ligase Detection Reaction Assay for Detection of CYP2C19 Polymorphisms.

AIMS: Cytochrome P450 2C19 (CYP2C19) genotypes are associated with differential drug metabolism. The aim of this study was to establish a reliable assay for CYP2C19 genotyping based on a polymerase chain reaction/ligase detection reaction (PCR-LDR). MATERIALS AND METHODS: Specific primers and probes were designed to detect CYP2C19*1, *2, *3, and *17. A control for each allele was prepared and used for performance evaluation. A total of 200 clinical samples were analyzed using the PCR-LDR assay and Sanger sequencing. RESULTS: The detection limit of the PCR-LDR assay was 2 ng/µL of genomic DNA. Common interfering substances in the blood did not affect the results of the detection. For the clinical samples, the results of the PCR-LDR and the Sanger sequencing were identical. Among the 200 patients, 104 (52%) were wild type (*1/*1), 64 (32%) were *1/*2, 16 (8%) were *1/*3, 8 (4%) were *2/*2, 7 (3.5%) were *2/*3, and 1 (0.5%) was *1/*7. No *3/*3 genotype was detected in these patients. CONCLUSION: This PCR-LDR assay is reliable for the detection of CYP2C19 genotypes in a clinical setting. It will be a useful tool to screen for CYP2C19 loss-of-function alleles in patients before clopidogrel and proton pump inhibitor treatment.

Cerium dioxide-doped carboxyl fullerene as novel nanoprobe and catalyst in electrochemical biosensor for amperometric detection of the CYP2C19*2 allele in human serum.

The disposition dose of clopidogrel is different in CYP2C19*2 gene carriers and non-carriers. High-dose clopidogrel has been recommended to overcome a low-responsiveness to clopidogrel in patients with the CYP2C19*2 gene. To guide the choice of clopidogrel dosage and catalyse a development in the field of personalized therapy, we developed an ultrasensitive electrochemical biosensor to detect CYP2C19*2 gene. We constructed a novel assay based on cerium dioxide (CeO2)-functionalized carboxyl fullerene (c-C60) supported by Pt nanoparticles (c-C60/CeO2/PtNPs) for signal amplification. Au nanoparticles @ Fe-MIL-88NH2 (AuNPs@Fe-MOFs) were synthesized by one-step method as the support platform to enhance the conductivity and immobilize more biotin-modified capture probe (bio-CP) through the superior affinity and specificity between streptavidin and biotin. c-C60/CeO2/PtNPs were labeled with signal probe to form the signal label. After the sandwich reaction of CYP2C19*2 gene between capture probe and the signal label, a distinguishing electrochemical signal from the catalysis of H2O2 by signal label would be observed. Amperometry was applied to record electrochemical signals. Under optimized conditions, the approach showed a good linear dependence between current and the logarithm of CYP2C19*2 gene concentrations in the range of 1 fM to 50nM with a low detection limit of 0.33fM (S/N = 3). The proposed method showed good specificity to target DNA compared with possible interfering substances. More importantly, the fabricated biosensor achieved accurate quantitative detection of CYP2C19*2 gene in human serum samples demonstrated by excellent correlations with standard DNA sequencing and provided a promising strategy for electrochemical biosensor detection of other gene mutations.

Autoantibodies against CYP-2C19: A Novel Serum Marker in Pediatric De Novo Autoimmune Hepatitis?

Diagnosis of de novo autoimmune hepatitis (AIH) after orthotopic liver transplantation (OLT) is challenging especially in the absence of hyper-γ-globulinemia. Circulating autoantibodies are not sensitive nor specific in de novo AIH but when positive increase the diagnostic probability. We report the discovery of novel liver microsomal (LM) autoantibodies against CYP-2C19 in a 9-year-old boy with "de novo" AIH developed 7 years after OLT. Graft dysfunction presented with hypertransaminasemia (up to 400 IU/L), while serum γ-globulins remained within the normal range for age. Liver histology and response to high dose prednisone (2 mg/kg/day) with the addition of azathioprine therapy further supported the diagnosis of de novo AIH. Autoantibodies investigation by indirect immunofluorescence (IF) on rodent tissues showed a novel staining pattern involving the pericentral liver zone and sparing the renal tissue. Human but not rat liver proteins immunoblotting allowed us to characterize the novel LM antibodies and to identify CYP-2C19 as human antigen. The finding offers insights into the controversial discussion about autoimmunity versus alloreactivity with regard to the pathogenesis of de novo AIH. Correct information on human versus rat tissue antigens tested by methods other than IF for antibodies detection may have significant implications for the correct diagnosis and management of patients followed up after OLT.

Genetic Polymorphism of CYP2C19 and Inhibitory Effects of Ticagrelor and Clopidogrel Towards Post-Percutaneous Coronary Intervention (PCI) Platelet Aggregation in Patients with Acute Coronary Syndromes.

BACKGROUND The aim of this study was to observe the effects of genetic polymorphism of CYP2C19 on inhibitory effects of ticagrelor (Tic) and clopidogrel (Clo) towards post-percutaneous coronary intervention (PCI) platelet aggregation (IPA) and major cardiovascular events (MACE) in patients with acute coronary syndromes (ACS). MATERIAL AND METHODS From August 2013 to March 2014, 166 patients with ACS undergoing PCI were selected. The patients were randomly grouped into the Tic group and the Clo group. IPA was detected by thromboelastography (TEG) at 1 week after taking the pills. Genotyping of CYP2C19 gene was determined by analysis of gene sequence detection. Patients were followed up for 1 month and MACE was observed. RESULTS The total IPA in the Clo group was significantly increased compared with the Tic group (P<0.05). The IPAs in the 3 subgroups of Clo group were all significantly increased compared with the 3 subgroups of the Tic group (all P<0.05). MACE was not significantly different between Clo and Tic groups (P>0.05). MACE had no significant difference among the 3 subgroups of the Tic group (P>0.05). MACE in the low metabolism subgroup of the Clo group was significantly increased compared with the fast metabolism subgroup and middle metabolism subgroup of Clo group (P<0.05). MACE was not significant different between the fast metabolism subgroup and the middle metabolism subgroup of the Clo group (P>0.05). MACE in the low metabolism subgroup of the Tic group was significantly decreased compared with the low metabolism subgroup of the Clo group (P<0.05). CONCLUSIONS Ticagrelor has a better effect on inhibition platelet aggregation than Clopidogrel in ACS patients undergoing PCI.

Voriconazole plasma concentrations in immunocompromised pediatric patients vary by CYP2C19 diplotypes.

AIM: Our objective was to describe the association between voriconazole concentrations and CYP2C19 diplotypes in pediatric cancer patients, including children homozygous for the CYP2C19*17 gain-of-function allele. MATERIALS & METHODS: A linear mixed effect model compared voriconazole dose-corrected trough concentrations (n = 142) among CYP2C19 diplotypes in 33 patients (aged 1-19 years). Voriconazole pharmacokinetics was described by a two-compartment model with Michaelis-Menten elimination. RESULTS: Age (p = 0.05) and CYP2C19 diplotype (p = 0.002) were associated with voriconazole concentrations. CYP2C19*17 homozygotes never attained therapeutic concentrations, and had lower dose-corrected voriconazole concentrations (median 0.01 µg/ml/mg/kg; p = 0.02) than CYP2C19*1 homozygotes (median 0.07 µg/ml/mg/kg). Modeling indicates that higher doses may produce therapeutic concentrations in younger children and in those with a CYP2C19*17/*17 diplotype. CONCLUSION: Younger age and the presence of CYP2C19 gain-of-function alleles were associated with subtherapeutic voriconazole concentrations. Starting doses based on age and CYP2C19 status could increase the number of patients achieving therapeutic voriconazole exposure.

The role of clinical parameters and of CYP2C19 G681 and CYP4F2 G1347A polymorphisms on platelet reactivity during dual antiplatelet therapy.

Dual antiplatelet therapy with aspirin and clopidogrel is used to lower the risk of arterial thrombosis. However, this strategy is not always successful owing to high interindividual variability in response to antiplatelet therapy. To evaluate an impact of CYP2C19 G681A and CYP4F2 G1347A polymorphisms and clinical factors on dual antiplatelet effect of clopidogrel and aspirin. Totally 89 patients who continued dual aspirin and clopidogrel antiplatelet therapy for at least of 14 days were included into the further study. Test for platelet aggregation was performed according to the classical Born method. Genotyping of CYP2C19*2 and CYP2C19*3 and CYP4F2*3 was done by using commercial probes from Applied Biosystems (UK). Patient age, weight and body weight index did not correlate significantly with platelet aggregation level both induced by ADP and epinephrine (P > 0.05). Serum concentration of creatinine, diabetes, angiotensin II receptor blockers, B-blockers, statin or omeprazole use had no significant effect on platelet aggregation. The users of angiotensin-converting enzyme inhibitors had lower platelet aggregation levels with epinephrine vs. nonusers: 28.80 ±â€Š13.25 vs. 51.15 ±â€Š23.50, P < 0.03, respectively. Platelet aggregation with ADP was higher in CYP2C19*1*2 genotype carriers than in CYP2C19*1*1 carriers (P = 0.01). Platelet aggregation with epinephrine was higher in CYP4F2 GA genotype carriers than in GG (P = 0.04) or AA (P = 0.01) carriers. Our study confirms that CYP2C19 G681A genotype has an impact on antiplatelet effect of clopidogrel. The novelty is that the platelet aggregation after induction with epinephrine is influenced by CYP4F2 G1347A genotype.

Decreased circulating microRNA-223 level predicts high on-treatment platelet reactivity in patients with troponin-negative non-ST elevation acute coronary syndrome.

To investigate the relationship between circulating microRNA 223 (miR-223) levels and clopidogrel responsiveness in patients with coronary heart disease. A total of 62 consecutive patients with troponin-negative non-ST elevation acute coronary syndrome (NSTE-ACS) scheduled for elective percutaneous coronary intervention were enrolled. The plasma circulating miR-223 levels were quantified by real-time PCR, and platelet reactivity was determined by platelet reactivity index (PRI), measured by vasodilator-stimulated phosphoprotein (VASP) phosphorylation flow cytometry after 300 mg (for at least 24 h) or 75 mg clopidogel (for at least 5 days) plus aspirin treatment. All subjects were dichotomized according to PRI median (normal-responders: PRI ≤ 56.3%, n = 31 and low-responders: PRI > 56.3%, n = 31). Compared with normal-responders, circulating miR-223 level was significantly decreased in low-responders (P = 0.007). In addition, miR-223 level was statistically correlated with PRI (Spearman r = -0.379, P = 0.002). Stepwise binary logistic regression analysis revealed that among factors that potentially influence platelet reactivity (CYP2C19*2/*3 loss-of-function genotypes, use of calcium channel blockers/proton-pump inhibitors, age, diabetes and smoking), decreased circulating miR-223 level was the only independent predictor for the presence of PRI-determined lower responders (OR 0.111, 95% CI 0.018-0.692, P = 0.019). Our data suggest that circulating miR-223 may serve as a novel biomarker for assessment of clopidogrel responsiveness in troponin-negative NSTE-ACS patients.