Antiinflammatory Therapy with Canakinumab for Atherosclerotic Disease

BACKGROUND

Experimental and clinical data suggest that reducing inflammation without affecting lipid levels may reduce the risk of cardiovascular disease. Yet, the inflammatory hypothesis of atherothrombosis has remained unproved.

METHODS

We conducted a randomized, double-blind trial of canakinumab, a therapeutic monoclonal antibody targeting interleukin-1β, involving 10,061 patients with previous myocardial infarction and a high-sensitivity C-reactive protein level of 2 mg or more per liter. The trial compared three doses of canakinumab (50 mg, 150 mg, and 300 mg, administered subcutaneously every 3 months) with placebo. The primary efficacy end point was nonfatal myocardial infarction, nonfatal stroke, or cardiovascular death.

RESULTS

At 48 months, the median reduction from baseline in the high-sensitivity C-reactive protein level was 26 percentage points greater in the group that received the 50-mg dose of canakinumab, 37 percentage points greater in the 150-mg group, and 41 percentage points greater in the 300-mg group than in the placebo group. Canakinumab did not reduce lipid levels from baseline. At a median follow-up of 3.7 years, the incidence rate for the primary end point was 4.50 events per 100 person-years in the placebo group, 4.11 events per 100 person-years in the 50-mg group, 3.86 events per 100 person-years in the 150-mg group, and 3.90 events per 100 person-years in the 300-mg group. The hazard ratios as compared with placebo were as follows: in the 50-mg group, 0.93 (95% confidence interval [CI], 0.80 to 1.07; P=0.30); in the 150-mg group, 0.85 (95% CI, 0.74 to 0.98; P=0.021); and in the 300-mg group, 0.86 (95% CI, 0.75 to 0.99; P=0.031). The 150-mg dose, but not the other doses, met the prespecified multiplicity-adjusted threshold for statistical significance for the primary end point and the secondary end point that additionally included hospitalization for unstable angina that led to urgent revascularization (hazard ratio vs. placebo, 0.83; 95% CI, 0.73 to 0.95; P=0.005). Canakinumab was associated with a higher incidence of fatal infection than was placebo. There was no significant difference in all-cause mortality (hazard ratio for all canakinumab doses vs. placebo, 0.94; 95% CI, 0.83 to 1.06; P=0.31).

CONCLUSIONS

Antiinflammatory therapy targeting the interleukin-1β innate immunity pathway with canakinumab at a dose of 150 mg every 3 months led to a significantly lower rate of recurrent cardiovascular events than placebo, independent of lipid-level lowering. (Funded by Novartis; CANTOS ClinicalTrials.gov number, NCT01327846 .).

Practical Approaches for Whole-Genome Sequence Analysis of Heart- and Blood-Related Traits

Whole-genome sequencing (WGS) allows for a comprehensive view of the sequence of the human genome. We present and apply integrated methodologic steps for interrogating WGS data to characterize the genetic architecture of 10 heart- and blood-related traits in a sample of 1,860 African Americans. In order to evaluate the contribution of regulatory and non-protein coding regions of the genome, we conducted aggregate tests of rare variation across the entire genomic landscape using a sliding window, complemented by an annotation-based assessment of the genome using predefined regulatory elements and within the first intron of all genes. These tests were performed treating all variants equally as well as with individual variants weighted by a measure of predicted functional consequence. Significant findings were assessed in 1,705 individuals of European ancestry. After these steps, we identified and replicated components of the genomic landscape significantly associated with heart- and blood-related traits. For two traits, lipoprotein(a) levels and neutrophil count, aggregate tests of low-frequency and rare variation were significantly associated across multiple motifs. For a third trait, cardiac troponin T, investigation of regulatory domains identified a locus on chromosome 9. These practical approaches for WGS analysis led to the identification of informative genomic regions and also showed that defined non-coding regions, such as first introns of genes and regulatory domains, are associated with important risk factor phenotypes. This study illustrates the tractable nature of WGS data and outlines an approach for characterizing the genetic architecture of complex traits.

Collaborative meta-analysis of individual participant data from observational studies of Lp-PLA2 and cardiovascular diseases

BACKGROUND

A large number of observational epidemiological studies have reported generally positive associations between circulating mass and activity levels of lipoprotein-associated phospholipase A2 (Lp-PLA2) and the risk of cardiovascular diseases. Few studies have been large enough to provide reliable estimates in different circumstances, such as in different subgroups (e.g., by age group, sex, or smoking status) or at different Lp-PLA2 levels. Moreover, most published studies have related disease risk only to baseline values of Lp-PLA2 markers (which can lead to substantial underestimation of any risk relationships because of within-person variability over time) and have used different approaches to adjustment for possible confounding factors.

OBJECTIVES

By combination of data from individual participants from all relevant observational studies in a systematic 'meta-analysis', with correction for regression dilution (using available data on serial measurements of Lp-PLA2), the Lp-PLA2 Studies Collaboration will aim to characterize more precisely than has previously been possible the strength and shape of the age and sex-specific associations of plasma Lp-PLA2 with coronary heart disease (and, where data are sufficient, with other vascular diseases, such as ischaemic stroke). It will also help to determine to what extent such associations are independent of possible confounding factors and to explore potential sources of heterogeneity among studies, such as those related to assay methods and study design. It is anticipated that the present collaboration will serve as a framework to investigate related questions on Lp-PLA2 and cardiovascular outcomes.

METHODS

A central database is being established containing data on circulating Lp-PLA2 values, sex and other potential confounding factors, age at baseline Lp-PLA2 measurement, age at event or at last follow-up, major vascular morbidity and cause-specific mortality. Information about any repeat measurements of Lp-PLA2 and potential confounding factors has been sought to allow adjustment for possible confounding and correction for regression dilution. The analyses will involve age-specific regression models. Synthesis of the available observational studies of Lp-PLA2 will yield information on a total of about 15 000 cardiovascular disease endpoints.

A colitogenic memory CD4+ T cell population mediates gastrointestinal graft-versus-host disease

Damage to the gastrointestinal tract is a major cause of morbidity and mortality in graft-versus-host disease (GVHD) and is attributable to T cell-mediated inflammation. In this work, we identified a unique CD4+ T cell population that constitutively expresses the β2 integrin CD11c and displays a biased central memory phenotype and memory T cell transcriptional profile, innate-like properties, and increased expression of the gut-homing molecules α4β7 and CCR9. Using several complementary murine GVHD models, we determined that adoptive transfer and early accumulation of β2 integrin-expressing CD4+ T cells in the gastrointestinal tract initiated Th1-mediated proinflammatory cytokine production, augmented pathological damage in the colon, and increased mortality. The pathogenic effect of this CD4+ T cell population critically depended on coexpression of the IL-23 receptor, which was required for maximal inflammatory effects. Non-Foxp3-expressing CD4+ T cells produced IL-10, which regulated colonic inflammation and attenuated lethality in the absence of functional CD4+Foxp3+ T cells. Thus, the coordinate expression of CD11c and the IL-23 receptor defines an IL-10-regulated, colitogenic memory CD4+ T cell subset that is poised to initiate inflammation when there is loss of tolerance and breakdown of mucosal barriers.

Abstract 52: Efficacy and Safety of Mipomersen in Patients with Familial Hypercholesterolemia and Inadequately Controlled LDL-C Levels

Aim: Mipomersen is an antisense oligonucleotide inhibitor of apolipoprotein B-100 synthesis, FDA-approved to treat homozygous familial hypercholesterolemia. The primary objective of this study was to determine whether mipomersen significantly reduced atherogenic lipid levels in patients with severe heterozygous familial hypercholesterolemia (HeFH).

Methods: This was a randomized, double-blind, placebo-controlled, parallel-group study comprised of two cohorts (NCT01475825). Cohort 1 had severe HeFH (LDL-C ≥200 mg/dL + coronary heart disease, or LDL-C ≥300 mg/dL) and Cohort 2 had milder HeFH (LDL-C ≥160 and <200 mg/dL). For each cohort, patients were randomized 1:1 to 200 mg SC once weekly or 70 mg SC thrice weekly, then 2:1 to receive mipomersen or placebo for 60 weeks. The primary outcome was percent change from baseline in LDL-C in Cohort 1. The % change from baseline in LDL-C at Week 61 for mipomersen treated patients was compared to placebo using a mixed model for repeated measures (MMRM), as well as by ANCOVA on the value closest to 7 days post last treatment (LOCF).

Results: Mean baseline LDL-C levels were 265 mg/dL in Cohort 1 (N=200) and 176 mg/dL in Cohort 2 (N=109). In Cohort 1, mipomersen 200 mg weekly reduced LDL-C levels by -29.7% (vs -7.9% placebo, P <.001) in the mixed model, and by -36.3% (vs -7.6% placebo, P <.001) using the LOCF. Analysis of LDL-C over time (Figure) showed a mean absolute reduction of 138 mg/dL in mipomersen patients who completed the blinded treatment period (n=32), achieving a mean level of 147 mg/dL from a mean 285 mg/dL baseline level. Tolerability to treatment and adverse events were similar between dose regimens. Adverse events were consistent with the drug’s known safety and tolerability profile.

Conclusions: The primary analysis showed a significant reduction in LDL-C levels in patients with severe HeFH who received mipomersen 200 mg once weekly versus placebo. A highly relevant absolute reduction in LDL-C was achieved over time.

Abstract 14: Statin Use Before and After the 2013 American College of Cardiology/American Heart Association Cholesterol Management Guideline

Background: The 2013 ACC/AHA guideline, first published in 11/2013, recommends moderate to high intensity statin therapy in 4 specific patient groups (Table). Whether this guideline has impacted clinical practice is not known.

Methods: We examined statin use and dose intensity before (9/2012-10/2013) and after (2/2014-3/2015) the guideline in the 4 specific groups from cardiology practices participating in the ACC NCDR®’s PINNACLE Registry after excluding practices with missing data from either period. To assess the guidelines’ effect on statin use, using a hierarchical logistic model, we examined interaction between guideline publication and time to allow different slopes and intercepts during the 2 periods.

Results: There was a small increase in statin and a similar decrease in non-statin lipid lowering therapy use after the guideline in all 4 groups (overall change <6%, Table), mostly accounted for by a modest increase in high intensity statin use. Although there was significant interaction between guideline publication and time (p=0.034) with steeper slope in the post guideline period, the difference was only modest. For example, in 9/2014 the projected overall statin use was 68.6% without and 71.3% with the interaction the term, respectively.

Conclusion: There is suboptimal implementation of the 2013 ACC/AHA cholesterol guidelines in cardiology practices. Most high-risk patients are not receiving high intensity statin therapy. More efforts are needed for effective guideline implementation.

Prognostic Significance of High-Sensitivity Cardiac Troponin T Concentrations between the Limit of Blank and Limit of Detection in Community-Dwelling Adults: A Metaanalysis

BACKGROUND

There is controversy regarding whether to report concentrations of high-sensitivity cardiac troponin T (hs-cTnT) to the limit of blank (LOB) (3 ng/L) or the limit of detection (LOD) (5 ng/L) of the assay in community-based cohorts. We hypothesized that hs-cTnT concentrations between the LOB and LOD would be associated with poorer cardiovascular outcomes compared to concentrations below the LOB.

METHODS

hs-cTnT was analyzed in a total of 10 723 participants from the Cardiovascular Health Study (CHS), Atherosclerosis Risk in Communities (ARIC) study, and Dallas Heart Study (DHS). Participants were divided into 2 groups, those with hs-cTnT concentrations below the limit of blank (LOB) (<3 ng/L) and those with hs-cTnT between the LOB and limit of detection (LOD) (3-4.99 ng/L). Cross-sectional associations with traditional cardiovascular risk factors and cardiac structural measurements, and longitudinal associations with long-term cardiovascular outcomes of incident heart failure and cardiovascular death, were determined.

RESULTS

Participants with hs-cTnT between the LOB and LOD for all 3 cohorts were older, more likely to be male, and have a higher burden of cardiovascular risk factors and structural pathology. A metaanalysis of the 3 cohorts showed participants with hs-cTnT between the LOB and LOD were at increased risk of new-onset heart failure (hazard ratio, 1.18; 95% CI, 1.02-1.38) and cardiovascular mortality (hazard ratio, 1.29; 95% CI, 1.06-1.57).

CONCLUSIONS

hs-cTnT concentrations between the LOB and LOD (3-4.99 ng/L) are associated with a higher prevalence of traditional risk factors, more cardiac pathology, and worse outcomes than concentrations below the LOB (<3 ng/L).

Abstract 276: Postprandial Effects on Monocyte Phenotype in Obese Humans With Metabolic Syndrome

Monocytes are heterogeneous with 3 subsets in humans, identified by CD14 and CD16 levels and differing in numerous other markers. Under certain stimuli, monocytes undergo phenotypic changes, with accelerated trafficking into tissues, which play crucial roles in inflammation including atherogenesis. We used multicolor flow cytometry to examine postprandial effects of a high-fat meal, containing 910 kcal (53% from fat, 23% from saturated fat) and 535 mg cholesterol, on monocyte phenotype in 11 obese subjects with metabolic syndrome (MS) (BMI: 34.8 ± 2.2 kg/m2; fasting triglyceride [TG]: 217 ± 42 mg/dl) and 11 gender- and age-matched lean controls (BMI: 24.0 ± 0.7 kg/m2; fasting TG: 89 ± 10 mg/dl, P<0.01 vs obese group). Blood was taken after an overnight fast (T0) and at 3 (T3) and 5 (T5) hours after high-fat meal. At T0, obese subjects had higher counts of CD14dim/CD16+ nonclassical monocytes (ncM), but not CD14+/CD16- classical (cM) and CD14+/CD16+ intermediate monocytes (iM), than leans. Mean fluorescent intensity (MFI) of CD11c, CCR5 and HLA-DR, and percentages of TNFα+ and IL-1β+ cells were higher on/in iM and ncM than on/in cM (P<0.05) in each individual at T0, supporting inflammatory phenotype of iM and ncM. Compared to lean, obese subjects had higher levels of CD11c on iM and cM, CX3CR1 on iM and CCR5 and TNFα on/in cM and also higher proportion of Nile-red+ lipid-laden foamy monocytes at T0 (P<0.05), which correlated positively with fasting TG levels (P=0.02, r=0.53). After high-fat meal, both obese and lean groups had significant increases in TG levels (TG incremental area under the curve: 344 ± 52 in obese versus 225 ± 28 in leans, P=0.05). The proportions of foamy monocytes were significantly higher at T3 than T0 (P<0.05) in lean subjects and tended to be higher at T3 and T5 than T0 in obese subjects. Obese but not lean subjects had significant increases in CD11c MFI and percentages of IL-1β+ and TNFα+ cells in ncM at T3 compared to T0. In summary, in both obese and lean groups, iM and ncM had proinflammatory phenotype. Compared to leans, obese subjects with MS had increased lipid accumulation and enhanced inflammatory phenotype in monocyte subsets at baseline and showed further increases in inflammatory markers, particularly in ncM, after a high-fat meal.

Abstract 148: Stat2 Deficiency Does Not Protect From Atherosclerosis in Ldlr Knockout Mice Fed a Western Diet

Signal Transducer and Activator of Transcription ( Stat2 ) is a transcription factor that plays a critical role in type I interferon (IFN) signaling. Recent evidence supports a role for the type I IFN pathway in atherosclerosis, since recombinant IFN alpha and IFN beta both promote atherosclerosis in mice. We tested the hypothesis that constitutive type I IFN signaling through STAT2 may promote atherosclerotic lesion formation. Male Ldlr KO and Stat2/Ldlr DKO mice on a C57BL6/J background were fed a western diet for 16 weeks. Total cholesterol levels were indistinguishable at baseline ( Ldlr KO: 232 ± 24 vs. Stat2/Ldlr DKO: 239 ± 36 mg/dl, p=0.39), but significantly higher in the Stat2/Ldlr DKO mice after 16 weeks of western diet ( Ldlr KO: 856 ± 203 Vs Stat2/Ldlr DKO: 1015 ± 176 mg/dl, p=0.004). Despite consuming less food than Ldlr KO controls, the Stat2/Ldlr DKO animals weighed significantly more than controls and had greater fat mass in the inguinal subcutaneous and perigonadal depots respectively ( Ldlr KO: 0.45±0.23 Vs Stat2/Ldlr DKO: 0.69 ± 0.27 g, p=0.003 and Ldlr KO: 0.89 ± 0.50 Vs Stat2/Ldlr DKO: 1.39 ± 0.56 g, p=0.003). Surprisingly, no significant differences were observed in percent lesional area of aortae ( Ldlr KO: 9.7% ± 5.6% Vs Stat2/Ldlr DKO: 12.5% ± 6.8%, p=0.156). In conclusion, STAT2 does not appear to have a major impact on atherosclerosis in the absence of exogenous type I IFNs or other agonism of the pathway.

Inactivating mutations in NPC1L1 and protection from coronary heart disease

BACKGROUND

Ezetimibe lowers plasma levels of low-density lipoprotein (LDL) cholesterol by inhibiting the activity of the Niemann-Pick C1-like 1 (NPC1L1) protein. However, whether such inhibition reduces the risk of coronary heart disease is not known. Human mutations that inactivate a gene encoding a drug target can mimic the action of an inhibitory drug and thus can be used to infer potential effects of that drug.

METHODS

We sequenced the exons of NPC1L1 in 7364 patients with coronary heart disease and in 14,728 controls without such disease who were of European, African, or South Asian ancestry. We identified carriers of inactivating mutations (nonsense, splice-site, or frameshift mutations). In addition, we genotyped a specific inactivating mutation (p.Arg406X) in 22,590 patients with coronary heart disease and in 68,412 controls. We tested the association between the presence of an inactivating mutation and both plasma lipid levels and the risk of coronary heart disease.

RESULTS

With sequencing, we identified 15 distinct NPC1L1 inactivating mutations; approximately 1 in every 650 persons was a heterozygous carrier for 1 of these mutations. Heterozygous carriers of NPC1L1 inactivating mutations had a mean LDL cholesterol level that was 12 mg per deciliter (0.31 mmol per liter) lower than that in noncarriers (P=0.04). Carrier status was associated with a relative reduction of 53% in the risk of coronary heart disease (odds ratio for carriers, 0.47; 95% confidence interval, 0.25 to 0.87; P=0.008). In total, only 11 of 29,954 patients with coronary heart disease had an inactivating mutation (carrier frequency, 0.04%) in contrast to 71 of 83,140 controls (carrier frequency, 0.09%).

CONCLUSIONS

Naturally occurring mutations that disrupt NPC1L1 function were found to be associated with reduced plasma LDL cholesterol levels and a reduced risk of coronary heart disease. (Funded by the National Institutes of Health and others.).