A Genetics-based Biomarker Risk Algorithm for Predicting Risk of Alzheimer's Disease.

BACKGROUND: A straightforward, reproducible blood-based test that predicts age dependent risk of Alzheimer's disease (AD) could be used as an enrichment tool for clinical development of therapies. This study evaluated the prognostic performance of a genetics-based biomarker risk algorithm (GBRA) established on a combination of Apolipoprotein E (APOE)/Translocase of outer mitochondrial membrane 40 homolog (TOMM40) genotypes and age, then compare it to cerebrospinal fluid (CSF) biomarkers, neuroimaging and neurocognitive tests using data from two independent AD cohorts. METHODS: The GBRA was developed using data from the prospective Bryan-ADRC study (n=407; 86 conversion events (mild cognitive impairment (MCI) or late onset Alzheimer's disease (LOAD)). The performance of the algorithm was tested using data from the ADNI study (n=660; 457 individuals categorized as MCI or LOAD). RESULTS: The positive predictive values (PPV) and negative predictive values (NPV) of the GBRA are in the range of 70-80%. The relatively high odds ratio (approximately 3-5) and significant net reclassification index (NRI) scores comparing the GBRA to a version based on APOE and age alone support the value of the GBRA in risk prediction for MCI due to LOAD. Performance of the GBRA compares favorably with CSF and imaging (fMRI) biomarkers. In addition, the GBRA "high" and "low" AD-risk categorizations correlated well with pathological CSF biomarker levels, PET amyloid burden and neurocognitive scores. CONCLUSIONS: Unlike dynamic markers (i.e., imaging, protein or lipid markers) that may be influenced by factors unrelated to disease, genomic DNA is easily collected, stable, and the technical methods for measurement are robust, inexpensive, and widely available. The performance characteristics of the GBRA support its use as a pharmacogenetic enrichment tool for LOAD delay of onset clinical trials, and merits further evaluation for its clinical utility in evaluating therapeutic efficacy.

Impact of CYP2C19 Metabolizer Status on Patients With ACS Treated With Prasugrel Versus Clopidogrel.

BACKGROUND: Certain alleles of the CYP2C19 gene are associated with higher platelet reactivity and increased ischemic events among patients treated with clopidogrel. However, the relationship of CYP2C19 genotype and outcomes in medically managed patients with acute coronary syndromes (ACS) is not known. OBJECTIVES: This study sought to assess the effect of CYP2C19 genotype on ischemic outcomes in patients with ACS initially managed medically without revascularization who were randomized to either clopidogrel or prasugrel. METHODS: We classified patients as extensive metabolizers (EM) or reduced metabolizers (RM) based on CYP2C19 genotype and evaluated ischemic outcomes and platelet reactivity. Among 9,326 patients enrolled from 2008 to 2011, 5,736 participated in the genetics cohort; of these, 2,236 had platelet function testing data. RESULTS: There was no association between CYP2C19 metabolizer status (EM vs. RM) and the primary composite endpoint of cardiovascular death, myocardial infarction (MI), or stroke (hazard ratio [HR]: 0.86). EM and RM patients had similar rates of the primary endpoint whether treated with prasugrel (HR: 0.82) or clopidogrel (HR: 0.91; p for interaction = 0.495). After adjusting for clinical and treatment variables, EM patients had a lower risk of MI versus RM patients (HR: 0.80), but risks of other outcomes were similar. RM patients had significantly higher mean P2Y12 reaction units versus EM patients when treated with clopidogrel (39.93), but not with prasugrel (3.87). CONCLUSIONS: CYP2C19 metabolizer status is not associated with the composite outcome of cardiovascular death, MI, or stroke in medically managed ACS patients treated with clopidogrel or prasugrel. Our findings do not support routine CYP2C19 genetic testing in this population. (A Comparison of Prasugrel and Clopidogrel in Acute Coronary Syndrome Subjects [TRILOGY ACS]; NCT00699998).

PON1 Q192R genetic variant and response to clopidogrel and prasugrel: pharmacokinetics, pharmacodynamics, and a meta-analysis of clinical outcomes.

Clopidogrel and prasugrel are antiplatelet therapies commonly used to treat patients with cardiovascular disease. They are both pro-drugs requiring biotransformation into active metabolites. It has been proposed that a genetic variant Q192R (rs662 A>G) in PON1 significantly alters the biotransformation of clopidogrel and affects clinical outcomes; however, this assertion has limited support. The relationship between this variant and clinical outcomes with prasugrel has not been studied. We genotyped PON1 Q192R in 275 healthy subjects treated with clopidogrel or prasugrel and 2922 patients with an ACS undergoing PCI randomized to treatment with clopidogrel or prasugrel in the TRITON-TIMI 38 trial. A meta-analysis was performed including 13 studies and 16,760 clopidogrel-treated patients. Among clopidogrel-treated subjects, there were no associations between Q192R and active drug metabolite levels (P = 0.62) or change in platelet aggregation (P = 0.51). Consistent with these results, in clopidogrel-treated patients in TRITON-TIMI 38, there was no association between Q192R and the rates of CV death, myocardial infarction, or stroke (RR 11.2 %, QR 8.6 %, and QQ 9.3 %; P = 0.66) or stent thrombosis (RR 2.4 %, QR 0.7 %, and QQ 1.6 %, P = 0.30), with patients with the putative at-risk Q variant having numerically lower event rates. Likewise, among prasugrel-treated subjects, there were no associations between Q192R and active drug metabolite levels (P = 0.88), change in platelet aggregation (P = 0.97), or clinical outcomes (P = 0.72). In a meta-analysis, the Q variant was not significantly associated with MACE (QQ vs. RR 1.22, 95 % CI 0.84-1.76) or stent thrombosis (QQ vs. RR OR 1.36, 95 % CI 0.77-2.38). Furthermore, when restricted to the validation studies, the OR (95 % CI) for MACE and stent thrombosis were 0.99 (0.77-1.27) and 1.23 (0.74-2.03), respectively. In the present study, the Q192R genetic variant in PON1 was not associated with the pharmacologic or clinical response to clopidogrel, nor was it associated with the response to prasugrel. The meta-analysis reinforced a lack of a significant association between Q192R and cardiovascular outcomes in clopidogrel-treated patients.

African-American TOMM40'523-APOE haplotypes are admixture of West African and Caucasian alleles.

BACKGROUND: Several studies have demonstrated a lower apolipoprotein E4 (APOE ε4) allele frequency in African-Americans, but yet an increased age-related prevalence of AD. An algorithm for prevention clinical trials incorporating TOMM40'523 (Translocase of Outer Mitochondria Membrane) and APOE depends on accurate TOMM40'523-APOE haplotypes. METHODS: We have compared the APOE and TOMM40'523 phased haplotype frequencies of a 9.5 kb TOMM40/APOE genomic region in West African, Caucasian, and African-American cohorts. RESULTS: African-American haplotype frequency scans of poly-T lengths connected in phase with either APOE ε4 or APOE ε3 differ from both West Africans and Caucasians and represent admixture of several distinct West African and Caucasian haplotypes. A new West African TOMM40'523 haplotype, with APOE ε4 connected to a short TOMM40'523 allele, is observed in African-Americans but not Caucasians. CONCLUSION: These data have therapeutic implications for the age of onset risk algorithm estimates and the design of a prevention trial for African-Americans or other mixed ethnic populations.

Clopidogrel metaboliser status based on point-of-care CYP2C19 genetic testing in patients with coronary artery disease.

We compared results obtained with the Nanosphere Verigene® System, a novel point-of-care (POC) genetic test capable of analysing 11 CYP2C19 variants within 3 hours, to an established, validated genotyping method (Affymetrix™ DMET+; reference assay) for identifying extensive and reduced metabolisers of clopidogrel. Based on genotyping, patients (N=82) with stable coronary artery disease on clopidogrel 75 mg daily were defined as extensive metabolisers (*1/*1, *1/*17, *17/*17), reduced metabolisers (*1/*2, *1/*8, *2/*2, *2/*3), or of indeterminate metaboliser status (*2/*17). Pharmacokinetic exposure to clopidogrel's active metabolite and pharmacodynamic measures with P2Y12 reaction units (PRU) (VerifyNow®P2Y12 assay) and VASP PRI (PRI) were also assessed. There was a 99.9% overall concordance of marker-level data between the Nanosphere Verigene and DMET+ systems in identifying the CYP2C19 variants and 100% agreement in classifying the patients as extensive (n=59) or reduced metabolisers (n=15). Extensive metabolisers had significantly higher active metabolite exposure than reduced metabolisers (LS means 12.6 ng*h/ml vs 7.7 ng*h/ml; p<0.001). Extensive metabolisers also had lower PRU (LS means 158 vs 212; p=0.003) and VASP PRI (LS means 48% vs 63%, p=0.01) compared to reduced metabolisers. Rates of high on-treatment platelet reactivity were higher in reduced metabolisers compared to extensive metabolisers (VASP PRI ≥ 50%: 79% vs 47%; PRU >235: 33% vs 16%). The Nanosphere Verigene CBS system identified 11 CYP2C19 alleles in less than 3 hours with a high degree of accuracy when compared to a conventional method, and was further validated against pharmacokinetic and pharmacodynamic phenotypes.

A phase 2, placebo-controlled study of the opioid receptor antagonist LY2196044 for the treatment of alcohol dependence.

BACKGROUND: Endogenous opioid-mediated reward pathways may play a role in the development and maintenance of alcohol dependence. This study tested whether LY2196044, an opioid receptor antagonist, in combination with medical management would reduce drinking in alcohol-dependent patients. METHODS: This was a multicenter, outpatient, randomized, double-blind, parallel, and placebo-controlled trial with a 16-week treatment period. Patients (N = 375) were alcohol-dependent, treatment-seeking adults. Patients were randomly assigned to once-daily LY2196044 (final doses of 125 or 250 mg/d) or placebo. DNA samples were collected at baseline. At each visit, patients underwent safety assessments, laboratory testing, efficacy measures, and medical management. Blood samples were also obtained for pharmacokinetic testing. The primary measure was the change from baseline in the percent heavy drinking days (HDD). Secondary efficacy measures were percent days abstinent per month and number of drinks per day. RESULTS: The treatment difference in change from baseline in % HDD between LY2196044 and placebo was not statistically significant (-43.02 vs. -38.72%, respectively; p = 0.12). There was a trend toward greater change from baseline in the percent days abstinent per month for the LY2196044 group compared with the placebo group (33.49 vs. 28.12%, respectively; p = 0.051). The decrease from baseline for mean number of drinks per day was statistically significantly greater in the LY2196044 group compared with the placebo group (-5.37 vs. -4.66 drinks per day, respectively; p = 0.013). LY2196044-treated patients who were dopamine receptor type 4-variable number tandem repeat L carriers had greater reductions in % HDD (p = 0.0565), increased percent days abstinent (p = 0.0496), and reduced drinks per day (p = 0.0069) than placebo-treated L carriers. The safety profile for LY2196044 appeared similar to that of other opioid antagonists. CONCLUSIONS: The results from this proof-of-concept clinical trial warrant further evaluation of LY2196044 for the treatment of alcohol dependence.

Peroxisome proliferator-activated receptor gamma 2 and acyl-CoA synthetase 5 polymorphisms influence diet response.

Peroxisome proliferator-activated receptor gamma (PPARgamma) and its response gene, Acyl CoA synthetase 5 (ACSL5), which has an important role in fatty acid metabolism, may affect weight loss in response to caloric restriction. Therefore, we aimed to determine whether these genes were involved in the interindividual response to dietary treatment. Genotypic/phenotypic comparisons were made between selected obese women from the quintiles losing the most (diet responsive, n = 74) and the quintiles losing the least (diet-resistant, n = 67) weight in the first 6 weeks of a 900-kcal formula diet. Two common PPARgamma single nucleotide polymorphisms, Pro(12)Ala and C1431T, and eight polymorphisms across the ACSL5 gene were selected for single locus and haplotypic association analyses. The PPARgamma Pro(12)Ala single nucleotide polymorphism was associated with diet resistance (odds ratio = 3.48, 95% confidence interval = 1.41 to 8.56, p = 0.03), and the rs2419621, located in the 5'untranslated region of the ACSL5 gene, displayed the strongest association with diet response (odds ratio = 3.45, 95% confidence interval = 1.61 to 7.69, p = 0.001). Skeletal muscle ACSL5 mRNA expression was significantly lower in carriers of the wildtype compared with the variant rs2419621 allele (p = 0.03). Our results suggest a link between PPARgamma2 and ACSL5 genotype and diet responsiveness.

Multiple QTLs influencing triglyceride and HDL and total cholesterol levels identified in families with atherogenic dyslipidemia.

We conducted a genome-wide scan using variance components linkage analysis to localize quantitative-trait loci (QTLs) influencing triglyceride (TG), high density lipoprotein-cholesterol (HDL-C), low density lipoprotein-cholesterol, and total cholesterol (TC) levels in 3,071 subjects from 459 families with atherogenic dyslipidemia. The most significant evidence for linkage to TG levels was found in a subset of Turkish families at 11q22 [logarithm of the odds ratio (LOD)=3.34] and at 17q12 (LOD=3.44). We performed sequential oligogenic linkage analysis to examine whether multiple QTLs jointly influence TG levels in the Turkish families. These analyses revealed loci at 20q13 that showed strong epistatic effects with 11q22 (conditional LOD=3.15) and at 7q36 that showed strong epistatic effects with 17q12 (conditional LOD=3.21). We also found linkage on the 8p21 region for TG in the entire group of families (LOD=3.08). For HDL-C levels, evidence of linkage was identified on chromosome 15 in the Turkish families (LOD=3.05) and on chromosome 5 in the entire group of families (LOD=2.83). Linkage to QTLs for TC was found at 8p23 in the entire group of families (LOD=4.05) and at 5q13 in a subset of Turkish and Mediterranean families (LOD=3.72). These QTLs provide important clues for the further investigation of genes responsible for these complex lipid phenotypes. These data also indicate that a large proportion of the variance of TG levels in the Turkish population is explained by the interaction of multiple genetic loci.

Relation between atherogenic dyslipidemia and the Adult Treatment Program-III definition of metabolic syndrome (Genetic Epidemiology of Metabolic Syndrome Project).

Genetic Epidemiology of Metabolic Syndrome is a multinational, family-based study to explore the genetic basis of the metabolic syndrome. Atherogenic dyslipidemia (defined as low plasma high-density lipoprotein cholesterol with elevated triglycerides (<25th and >75th percentile for age, gender, and country, respectively) identified affected subjects for the metabolic syndrome. This report examines the frequency at which atherogenic dyslipidemia predicts the metabolic syndrome of the National Cholesterol Education Program Adult Treatment Panel III (ATP-III). One thousand four hundred thirty-six (854 men/582 women) affected patients by our criteria were compared with 1,672 (737 men/935 women) unaffected persons. Affected patients had more hypertension, obesity, and hyperglycemia, and they met a higher number of ATP-III criteria (3.2 +/- 1.1 SD vs 1.3 +/- 1.1 SD, p <0.001). Overall, 76% of affected persons also qualified for the ATP-III definition (Cohen's kappa 0.61, 95% confidence interval 0.59 to 0.64), similar to a separate group of 464 sporadic, unrelated cases (75%). Concordance increased from 41% to 82% and 88% for ages < or =35, 36 to 55, and > or =55 years, respectively. Affected status was also independently associated with waist circumference (p <0.001) and fasting glucose (p <0.001) but not systolic blood pressure (p = 0.43). Thus, the lipid-based criteria used to define affection status in this study substantially parallels the ATP-III definition of metabolic syndrome in subjects aged >35 years. In subjects aged <35 years, atherogenic dyslipidemia frequently occurs in the absence of other metabolic syndrome risk factors.

Ileal bile acid transporter inhibition, CYP7A1 induction, and antilipemic action of 264W94.

264W94 was designed to inhibit the ileal bile acid transporter (IBAT). Evaluated in vitro, 264W94 dose-dependently inhibited sodium-dependent uptake of 10 micro M [(3)H]taurocholic acid (TC) by rat and monkey brush border membrane vesicles with IC(50)s of 0.24 micro M and 0.41 micro M, and had a competitive profile with K(i) of 0.2 micro M against TC in Chinese hamster ovary cells expressing human IBAT. In distal ileum in situ, 1-10 micro M of 264W94 rapidly decreased uptake of 3mM TC by 24-39%, with corresponding decreases in biliary recovery. In rats and mice in vivo, oral 264W94 decreased absorption of TC analog, 23,25-(75)Se-homocholic acid taurine ((75)SeHCAT; quantitated in feces), with ED(30) of 0.02 mg/kg bid. (75)SeHCAT traced through the GI-tract revealed that peak (97%) inhibition of (75)SeHCAT absorption by the distal quarter of small intestine occurred at 4 h after single dose of 264W94 (0.1 mg/kg). Inhibition of IBAT by 264W94 in rats was associated with compensatory, same-day, 4-fold induction of hepatic cholesterol 7alpha-hydroxylase (CYP7A1) activity, exhibiting normal diurnal fluctuation for 3 days of dosing. In diet induced hypercholesterolemic rats, 264W94 (0.03-1.0 mg/kg bid) dose-dependently reduced serum LDL+VLDL cholesterol up to 61%. In conclusion, 264W94 is a potent new cholesterol lowering agent that acts through inhibition of IBAT and exhibits activity in a human model.