Verification of candidate biomarkers requires specific assays to selectively detect and quantify target proteins in accessible biofluids. The primary objective of verification is to screen potential ...biomarkers to ensure that only the highest quality candidates from the discovery phase are taken forward into preclinical validation. Because antibody reagents for a clinical grade immunoassay often exist for a small number of candidates, alternative methodologies are required to credential new and unproven candidates in a statistically viable number of serum or plasma samples. Using multiple reaction monitoring coupled with stable isotope dilution MS, we developed quantitative, multiplexed assays in plasma for six proteins of clinical relevance to cardiac injury. The process described does not require antibodies for immunoaffinity enrichment of either proteins or peptides. Limits of detection and quantitation for each signature peptide used as surrogates for the target proteins were determined by the method of standard addition using synthetic peptides and plasma from a healthy donor. Limits of quantitation ranged from 2 to 15 ng/ml for most of the target proteins. Quantitative measurements were obtained for one to two signature peptides derived from each target protein, including low abundance protein markers of cardiac injury in the nanogram/milliliter range such as the cardiac troponins. Intra- and interassay coefficients of variation were predominantly <10 and 25%, respectively. The configured multiplex assay was then used to measure levels of these proteins across three time points in six patients undergoing alcohol septal ablation for hypertrophic obstructive cardiomyopathy. These results are the first demonstration of a multiplexed, MS-based assay for detection and quantification of changes in concentration of proteins associated with cardiac injury in the low nanogram/milliliter range. Our results also demonstrate that these assays retain the necessary precision, reproducibility, and sensitivity to be applied to novel and uncharacterized candidate biomarkers for verification of proteins in blood.
Abstract
Aims
Subjects with lipoprotein(a) Lp(a) elevation have increased arterial wall inflammation and cardiovascular risk. In patients at increased cardiovascular risk, arterial wall inflammation ...is reduced following lipid-lowering therapy by statin treatment or lipoprotein apheresis. However, it is unknown whether lipid-lowering treatment in elevated Lp(a) subjects alters arterial wall inflammation. We evaluated whether evolocumab, which lowers both low-density lipoprotein cholesterol (LDL-C) and Lp(a), attenuates arterial wall inflammation in patients with elevated Lp(a).
Methods and results
In this multicentre, randomized, double-blind, placebo-controlled study, 129 patients {median interquartile range (IQR): age 60.0 54.0–67.0 years, Lp(a) 200.0 155.5–301.5 nmol/L 80.0 (62.5–121.0) mg/dL; mean standard deviation (SD) LDL-C 3.7 1.0 mmol/L 144.0 (39.7) mg/dL; National Cholesterol Education Program high risk, 25.6%} were randomized to monthly subcutaneous evolocumab 420 mg or placebo. Compared with placebo, evolocumab reduced LDL-C by 60.7% 95% confidence interval (CI) 65.8–55.5 and Lp(a) by 13.9% (95% CI 19.3–8.5). Among evolocumab-treated patients, the Week 16 mean (SD) LDL-C level was 1.6 (0.7) mmol/L 60.1 (28.1) mg/dL, and the median (IQR) Lp(a) level was 188.0 (140.0–268.0) nmol/L 75.2 (56.0–107.2) mg/dL. Arterial wall inflammation most diseased segment target-to-background ratio (MDS TBR) in the index vessel (left carotid, right carotid, or thoracic aorta) was assessed by 18F-fluoro-deoxyglucose positron-emission tomography/computed tomography. Week 16 index vessel MDS TBR was not significantly altered with evolocumab (−8.3%) vs. placebo (−5.3%) treatment difference −3.0% (95% CI −7.4% to 1.4%); P = 0.18.
Conclusion
Evolocumab treatment in patients with median baseline Lp(a) 200.0 nmol/L led to a large reduction in LDL-C and a small reduction in Lp(a), resulting in persistent elevated Lp(a) levels. The latter may have contributed to the unaltered arterial wall inflammation.
Cytochrome p-450 polymorphisms and response to clopidogrel Mega, Jessica L; Close, Sandra L; Wiviott, Stephen D ...
New England journal of medicine/The New England journal of medicine,
01/2009, Letnik:
360, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Clopidogrel requires transformation into an active metabolite by cytochrome P-450 (CYP) enzymes for its antiplatelet effect. The genes encoding CYP enzymes are polymorphic, with common alleles ...conferring reduced function.
We tested the association between functional genetic variants in CYP genes, plasma concentrations of active drug metabolite, and platelet inhibition in response to clopidogrel in 162 healthy subjects. We then examined the association between these genetic variants and cardiovascular outcomes in a separate cohort of 1477 subjects with acute coronary syndromes who were treated with clopidogrel in the Trial to Assess Improvement in Therapeutic Outcomes by Optimizing Platelet Inhibition with Prasugrel-Thrombolysis in Myocardial Infarction (TRITON-TIMI) 38.
In healthy subjects who were treated with clopidogrel, carriers of at least one CYP2C19 reduced-function allele (approximately 30% of the study population) had a relative reduction of 32.4% in plasma exposure to the active metabolite of clopidogrel, as compared with noncarriers (P<0.001). Carriers also had an absolute reduction in maximal platelet aggregation in response to clopidogrel that was 9 percentage points less than that seen in noncarriers (P<0.001). Among clopidogrel-treated subjects in TRITON-TIMI 38, carriers had a relative increase of 53% in the composite primary efficacy outcome of the risk of death from cardiovascular causes, myocardial infarction, or stroke, as compared with noncarriers (12.1% vs. 8.0%; hazard ratio for carriers, 1.53; 95% confidence interval CI, 1.07 to 2.19; P=0.01) and an increase by a factor of 3 in the risk of stent thrombosis (2.6% vs. 0.8%; hazard ratio, 3.09; 95% CI, 1.19 to 8.00; P=0.02).
Among persons treated with clopidogrel, carriers of a reduced-function CYP2C19 allele had significantly lower levels of the active metabolite of clopidogrel, diminished platelet inhibition, and a higher rate of major adverse cardiovascular events, including stent thrombosis, than did noncarriers.
Patients with stable ischemic heart disease and previous myocardial infarction (MI) vary in their risk for recurrent cardiovascular events. Atherothrombotic risk assessment may be useful to identify ...high-risk patients who have the greatest potential to benefit from more intensive secondary preventive therapy such as treatment with vorapaxar.
We identified independent clinical indicators of atherothrombotic risk among 8598 stable, placebo-treated patients with a previous MI followed up for 2.5 years (median) in TRA 2°P-TIMI 50 Thrombin Receptor Antagonist in Secondary Prevention of Atherothrombotic Ischemic Events-TIMI 50. The efficacy and safety of vorapaxar (SCH 530348; MK-5348) were assessed by baseline risk among patients with previous MI without prior stroke or transient ischemic attack for whom there is a clinical indication for vorapaxar. End points were cardiovascular death, MI, or ischemic stroke and GUSTO (Global Use of Strategies to Open Occluded Coronary Arteries) severe bleeding.
The 9 independent risk predictors were age, diabetes mellitus, hypertension, smoking, peripheral arterial disease, previous stroke, previous coronary bypass grafting, heart failure, and renal dysfunction. A simple integer-based scheme using these predictors showed a strong graded relationship with the rate of cardiovascular death/MI/ischemic stroke and the individual components (P for trend <0.001 for all). High-risk patients (≥3 risk indicators; 20% of population) had a 3.2% absolute risk reduction in cardiovascular disease/MI/ischemic stroke with vorapaxar, and intermediate-risk patients (1-2 risk indicators; 61%) had a 2.1% absolute risk reduction (P<0.001 each), translating to a number needed to treat of 31 and 48. Bleeding increased across risk groups (P for trend<0.01); however, net clinical outcome was increasingly favorable with vorapaxar across risk groups. Fatal bleeding or intracranial hemorrhage was 0.9% with both treatments in high-risk patients.
Stratification of baseline atherothrombotic risk can assist with therapeutic decision making for vorapaxar use for secondary prevention after MI.
URL: https://www.clinicaltrials.gov. Unique identifier: NCT00526474.
This study sought to evaluate the ability of the proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitor evolocumab to reduce the risk of complex coronary atherosclerosis requiring ...revascularization.
PCSK9 inhibitors induce plaque regression and reduce the risk of coronary revascularization overall.
FOURIER (Further Cardiovascular Outcomes Research with PCSK9 Inhibition in Subjects with Elevated Risk) was a randomized trial of the PCSK9 inhibitor evolocumab versus placebo in 27,564 patients with stable atherosclerotic cardiovascular disease on statin therapy followed for a median of 2.2 years. Clinical documentation of revascularization events was blindly reviewed to assess coronary anatomy and procedural characteristics. Complex revascularization was the composite of complex percutaneous coronary intervention (PCI) (as per previous analyses, ≥1 of: multivessel PCI, ≥3 stents, ≥3 lesions treated, bifurcation PCI, or total stent length >60 mm) or coronary artery bypass grafting surgery (CABG).
In this study, 1,724 patients underwent coronary revascularization, including 1,482 who underwent PCI, 296 who underwent CABG, and 54 who underwent both. Complex revascularization was performed in 632 (37%) patients. Evolocumab reduced the risk of any coronary revascularization by 22% (hazard ratio HR: 0.78; 95% CI: 0.71 to 0.86; p < 0.001), simple PCI by 22% (HR: 0.78; 95% CI: 0.70 to 0.88; p < 0.001), complex PCI by 33% (HR: 0.67; 95% CI: 0.54 to 0.84; p < 0.001), CABG by 24% (HR: 0.76; 95% CI: 0.60 to 0.96; p = 0.019), and complex revascularization by 29% (HR: 0.71; 95% CI: 0.61 to 0.84; p < 0.001). The magnitude of the risk reduction with evolocumab in complex revascularization tended to increase over time (20%, 36%, and 41% risk reductions in the first, second, and beyond second years).
Adding evolocumab to statin therapy significantly reduced the risk of developing complex coronary disease requiring revascularization, including complex PCI and CABG individually. (Further Cardiovascular Outcomes Research with PCSK9 Inhibition in Subjects with Elevated Risk (FOURIER); NCT01764633.)
Display omitted
Ticagrelor reduced major adverse cardiovascular event (MACE) by 15-16% in patients with prior myocardial infarction (MI) in PEGASUS-TIMI 54. We hypothesized that patients who recently discontinued ...P2Y12 inhibition, even years after MI, may be at particular risk of MACE and may derive particular benefit from continuation or reinitiation of therapy.
Patients in PEGASUS-TIMI 54 were categorized by time from last P2Y12 inhibitor (days: ≤30, >30-360, >360). The risk of MACE and the efficacy of ticagrelor were compared across categories. In the placebo arm, patients who more recently stopped P2Y12 inhibitor therapy had a greater number of risk factors but still had a higher risk of MACE after multivariable adjustment ≤30 days, hazard ratio (HR)adj 1.47, 95% confidence interval (CI) 1.12-1.93, P = 0.0051; 30 days-1 year, HRadj 1.28, 95% CI 0.98-1.67, P = 0.073 compared with those who stopped >1 year prior (P-trend = 0.0097). The benefit of ticagrelor depended on the time from last dose, with HRs (95% CI) for ticagrelor (pooled doses) vs. placebo of 0.73 (0.61-0.87), 0.86 (0.71-1.04), and 1.01 (0.80-1.27), respectively, by category (P-trend for interaction < 0.001). The benefit in those ≤30 days of stopping was similar regardless of time from MI (<2 years, HR 0.73, 95% CI 0.60-0.89 vs. ≥2 years, HR 0.71, 95% CI 0.50-1.00).
The benefit of ticagrelor for long-term secondary prevention in patients with prior MI and at least one additional risk factor appeared more marked in patients continuing on or re-starting after only a brief interruption of P2Y12 inhibition, when compared with patients who had proved themselves stable more than 2 years from their MI and off P2Y12 inhibitor therapy for more than a year. The increase in bleeding events with ticagrelor was similar regardless of this time interval. For clinicians considering a strategy of prolonged P2Y12 inhibitor therapy in high-risk patients, these data suggest greater benefit in the continuation of such therapy without interruption after MI, rather than re-initiating such therapy in patients who have remained stable for an extended period. Future analyses may help to clarify further the profile of post-MI patients most likely to benefit from uninterrupted dual antiplatelet therapy.
http://www.clinicaltrials.gov NCT01225562.
Some cholesteryl ester transfer protein (CETP) inhibitors lower low-density lipoprotein cholesterol (LDL-C) levels without reducing cardiovascular events, suggesting that the clinical benefit of ...lowering LDL-C may depend on how LDL-C is lowered.
To estimate the association between changes in levels of LDL-C (and other lipoproteins) and the risk of cardiovascular events related to variants in the CETP gene, both alone and in combination with variants in the 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) gene.
Mendelian randomization analyses evaluating the association between CETP and HMGCR scores, changes in lipid and lipoprotein levels, and the risk of cardiovascular events involving 102 837 participants from 14 cohort or case-control studies conducted in North America or the United Kingdom between 1948 and 2012. The associations with cardiovascular events were externally validated in 189 539 participants from 48 studies conducted between 2011 and 2015.
Differences in mean high-density lipoprotein cholesterol (HDL-C), LDL-C, and apolipoprotein B (apoB) levels in participants with CETP scores at or above vs below the median.
Odds ratio (OR) for major cardiovascular events.
The primary analysis included 102 837 participants (mean age, 59.9 years; 58% women) who experienced 13 821 major cardiovascular events. The validation analyses included 189 539 participants (mean age, 58.5 years; 39% women) with 62 240 cases of coronary heart disease (CHD). Considered alone, the CETP score was associated with higher levels of HDL-C, lower LDL-C, concordantly lower apoB, and a corresponding lower risk of major vascular events (OR, 0.946 95% CI, 0.921-0.972) that was similar in magnitude to the association between the HMGCR score and risk of major cardiovascular events per unit change in levels of LDL-C (and apoB). When combined with the HMGCR score, the CETP score was associated with the same reduction in LDL-C levels but an attenuated reduction in apoB levels and a corresponding attenuated nonsignificant risk of major cardiovascular events (OR, 0.985 95% CI, 0.955-1.015). In external validation analyses, a genetic score consisting of variants with naturally occurring discordance between levels of LDL-C and apoB was associated with a similar risk of CHD per unit change in apoB level (OR, 0.782 95% CI, 0.720-0.845 vs 0.793 95% CI, 0.774-0.812; P = .79 for difference), but a significantly attenuated risk of CHD per unit change in LDL-C level (OR, 0.916 95% CI, 0.890-0.943 vs 0.831 95% CI, 0.816-0.847; P < .001) compared with a genetic score associated with concordant changes in levels of LDL-C and apoB.
Combined exposure to variants in the genes that encode the targets of CETP inhibitors and statins was associated with discordant reductions in LDL-C and apoB levels and a corresponding risk of cardiovascular events that was proportional to the attenuated reduction in apoB but significantly less than expected per unit change in LDL-C. The clinical benefit of lowering LDL-C levels may therefore depend on the corresponding reduction in apoB-containing lipoprotein particles.
The DAPA-HF trial (Dapagliflozin and Prevention of Adverse-Outcomes in Heart Failure) showed that dapagliflozin added to other guideline-recommended therapies reduced the risk of mortality and heart ...failure hospitalization and improved symptoms in patients with heart failure and reduced ejection fraction. We examined the effects of dapagliflozin according to age, given potential concerns about the efficacy and safety of therapies in the elderly.
Patients in New York Heart Association functional class II or greater with a left ventricular ejection fraction ≤40% and a modest elevation of NT-proBNP (N-terminal pro-B-type natriuretic peptide) were eligible. Key exclusion criteria included systolic blood pressure <95 mm Hg and estimated glomerular filtration rate <30 mL·min
·1.73 m
. The primary outcome was the composite of an episode of worsening heart failure (heart failure hospitalization or urgent heart failure visit) or cardiovascular death, whichever occurred first.
A total of 4744 patients 22 to 94 years of age (mean age, 66.3 SD 10.9 years) were randomized: 636 patients (13.4%) were <55 years of age, 1242 (26.2%) were 55 to 64 years of age, 1717 (36.2%) were 65 to 74 years of age, and 1149 (24.2%) were ≥75 years of age. The rate of the primary outcome (per 100 person-years, placebo arm) in each age group was 13.6 (95% CI, 10.4-17.9), 15.7 (95% CI, 13.2-18.7), 15.1 (95% CI, 13.1-17.5), and 18.0 (95% CI, 15.2-21.4) with corresponding dapagliflozin/placebo hazard ratios of 0.87 (95% CI, 0.60-1.28), 0.71 (95% CI, 0.55-0.93), 0.76 (95% CI, 0.61-0.95), and 0.68 (95% CI, 0.53-0.88;
for interaction=0.76). Consistent benefits were observed for the components of the primary outcome, all-cause mortality, and symptoms. Although adverse events and study drug discontinuation increased with age, neither was significantly more common with dapagliflozin in any age group.
Dapagliflozin reduced the risk of death and worsening heart failure and improved symptoms across the broad spectrum of age studied in DAPA-HF. There was no significant imbalance in tolerability or safety events between dapagliflozin and placebo, even in elderly individuals.
URL: https://www.clinicaltrials.gov. Unique identifier: NCT03036124.
PDF
