Atherosclerosis stabilization with PCSK-9 inhibition: An evolving concept for cardiovascular prevention

Two decades of vaccine development against atherosclerosis

Atherosclerosis is an immune-mediated chronic inflammatory disease that leads to the development of fatty plaques in the arterial walls, ultimately increasing the risk of thrombosis, stroke, and myocardial infarction. The immune response in this complex disease is both atheroprotective and pro-atherogenic, involving both innate and adaptive immunity. Current treatments include the adjustment of lifestyle factors, cholesterol-lowering drugs such as statins, and immunotherapy, whereas vaccine development has received comparatively little attention. In this review, we discuss the potential of antigen-specific vaccination as a preventative approach based on more than 20 years of research and innovation. Vaccination targets include proteins that are more abundant in atherosclerotic patients, such as oxidized low-density lipoprotein (LDL), apolipoprotein B-100, proprotein convertase subtilisin/kexin type-9 serine protease (PCSK9), cholesteryl ester transfer protein (CETP), and heat shock proteins HSP60 and HSP65. Immunization with such proteins or their peptide epitopes has been shown to induce T-cell activation, produce antigen-specific antibodies, reduce the size of atherosclerotic lesions, and/or reduce serum cholesterol levels. Vaccination against atherosclerosis therefore offers a new strategy to address the burden on healthcare systems caused by cardiovascular disease, the leading cause of death worldwide.

A single-dose Qβ VLP vaccine against S100A9 protein reduces atherosclerosis in a preclinical model

The standard therapy for cardiovascular disease (CVD) is the administration of statins to reduce plasma cholesterol levels, but this requires lifelong treatment. We developed a CVD vaccine candidate that targets the pro-inflammatory mediator calprotectin by eliciting antibodies against the S100A9 protein. The vaccine, based on bacteriophage Qβ virus-like particles (VLPs) displaying S100A9 peptide epitopes, was formulated as a slow-release PLGA:VLP implant by hot-melt extrusion. The single-dose implant elicited S100A9-specific antibody titers comparable to a three-dose injection schedule with soluble VLPs. In an animal model of CVD (ApoE-/- mice fed on a high-fat diet), the implant reduced serum levels of calprotectin, IL-1β, IL-6 and MCP-1, resulting in less severe aortic lesions. This novel implant was therefore able to attenuate atherosclerosis over a sustained period and offers a novel and promising strategy to replace the repetitive administration of statins for the treatment of CVD.

A single-dose, implant-based, trivalent virus-like particle vaccine against "cholesterol checkpoint" proteins

Cardiovascular disease is the number one cause of death globally. Lowering cholesterol levels in plasma is the mainstay therapy; however lifelong treatment and adverse effects call for improved therapeutic interventions. We developed a trivalent vaccine candidate targeting proprotein convertase subtilisin/kexin-9 (PCSK9), apolipoprotein B (ApoB), and cholesteryl ester transfer protein (CETP). Vaccine candidates were developed using bacteriophage Qβ-based virus-like particles (VLPs) displaying antigens of PCKS9, ApoB, and CETP, respectively. Vaccine candidate mixtures were formulated as slow-release PLGA:VLP implants using hot-melt extrusion. The delivery of the trivalent vaccine candidate via the implant produced antibodies against the cholesterol checkpoint proteins at levels comparable to a three-dose injection schedule with soluble mixtures. The reduction in PCSK9 and ApoB levels in plasma, inhibition of CETP (in vitro), and total plasma cholesterol decrease was achieved. All-together, we present a platform technology for a single-dose multi-target vaccination platform targeting cholesterol checkpoint proteins.

New strategies for the development of lipid-lowering therapies to reduce cardiovascular risk

The very high occurrence of cardiovascular events presents a major public health issue, because treatment remains suboptimal. Lowering LDL cholesterol (LDL-C) with statins or ezetimibe in combination with a statin reduces major adverse cardiovascular events. The cardiovascular risk reduction in relation to the absolute LDL-C reduction is linear for most interventions without evidence of attenuation or increase in risk at low LDL-C levels. Opportunities for innovation in dyslipidaemia treatment should address the substantial risk of lipid-associated cardiovascular events among patients optimally treated per guidelines but who cannot achieve LDL-C goals and who could benefit from additional LDL-C-lowering therapy or experience side effects of statins. Fresh approaches are needed to identify promising drug targets early and develop them efficiently. The Cardiovascular Round Table of the European Society of Cardiology (ESC) convened a workshop to discuss new lipid-lowering strategies for cardiovascular risk reduction. Opportunities to improve treatment approaches and the efficient study of new therapies were explored. Circulating biomarkers may not be fully reliable proxy indicators of the relationship between treatment effect and clinical outcome. Mendelian randomization studies may better inform development strategies and refine treatment targets before Phase 3. Trials should match the drug to appropriate lipid and patient profile, and guidelines may move towards a precision-based approach to individual patient management. Stakeholder collaboration is needed to ensure continued innovation and better international coordination of both regulatory aspects and guidelines. It should be noted that risk may also be addressed through increased attention to other risk factors such as smoking, hypertension, overweight, and inactivity.

Determining When to Add Nonstatin Therapy: A Quantitative Approach

BACKGROUND

Costs and uncertainty about the benefits of nonstatin therapies limit their use.

OBJECTIVES

The authors sought to identify patients who might benefit from the addition of a nonstatin to background statin therapy.

METHODS

We performed systematic reviews of subgroup analyses from randomized trials and observational studies with statin-treated participants to determine estimated 10-year absolute risk of atherosclerotic cardiovascular disease (ASCVD) and to define high-risk and very high-risk patients. We used the relative risk reductions for the addition of a nonstatin to lower low-density lipoprotein (LDL-C) used to determine the number needed to treat (NNT) to prevent 1 ASCVD event over 5 years for each patient group and to allow comparisons with 5-year cost analyses.

RESULTS

The 10-year ASCVD risk is at least 30% (very high risk) for statin-treated participants with clinical ASCVD and comorbidities, and 20% to 29% (high risk) for those with ASCVD without comorbidities or who have heterozygous familial hypercholesterolemia. Adding ezetimibe to reduce low-density LDL-C by 20% would provide a 5-year NNT ≤50 for very high-risk patients with LDL-C ≥130 mg/dl or for high-risk patients with LDL-C ≥190 mg/dl, and an NNT ≤30 for very high-risk patients with LDL-C ≥160 mg/dl. Adding a PCSK9 monoclonal antibody to lower LDL-C by at least 50% would provide an NNT ≤50 for very high-risk and high-risk patients with LDL-C ≥70 mg/dl, and an NNT ≤30 for very high-risk and high-risk patients with an LDL-C ≥130 mg/dl.

CONCLUSIONS

Adding ezetimibe or PCSK9 monoclonal antibodies to maximally tolerated statin therapy may be cost effective in very high-risk and high-risk patients, depending on baseline LDL-C levels.

Health Benefits and Cost-Effectiveness of Asymptomatic Screening for Hypertension and High Cholesterol and Aspirin Counseling for Primary Prevention

PURPOSE

Our aim was to update estimates of the health and economic impact of clinical services recommended for the primary prevention of cardiovascular disease (CVD) for the comparative rankings of the National Commission on Prevention Priorities, and to explore differences in outcomes by sex and race/ethnicity.

METHODS

We used a single, integrated, microsimulation model to generate comparable results for 3 services recommended by the US Preventive Services Task Force: aspirin counseling for the primary prevention of CVD and colorectal cancer, screening and treatment for lipid disorders (usually high cholesterol), and screening and treatment for hypertension. Analyses compare lifetime outcomes from the societal perspective for a US-representative birth cohort of 100,000 persons with and without access to each clinical preventive service. Primary outcomes are health impact, measured by the net difference in lifetime quality-adjusted life years (QALYs), and cost-effectiveness, measured in incremental cost per QALY or cost savings per person in 2012 dollars. Results are also presented for population subgroups defined by sex and race/ethnicity.

RESULTS

Health impact is highest for hypertension screening and treatment (15,600 QALYs), but is closely followed by cholesterol screening and treatment (14,300 QALYs). Aspirin counseling has a lower health impact (2,200 QALYs) but is found to be cost saving ($31 saved per person). Cost-effectiveness for cholesterol and hypertension screening and treatment is $33,800 per QALY and $48,500 per QALY, respectively. Findings favor hypertension over cholesterol screening and treatment for women, and opportunities to reduce disease burden across all services are greatest for the non-Hispanic black population.

CONCLUSIONS

All 3 CVD preventive services continue to rank highly among other recommended preventive services for US adults, but individual priorities can be tailored in practice by taking a patient's demographic characteristics and clinical objectives into account.

Relationship between changes in coronary atherosclerotic plaque burden measured by intravascular ultrasound and cardiovascular disease outcomes: a systematic literature review

Objective Evidence from coronary imaging studies suggests an association between increased atherosclerotic plaque burden and cardiovascular disease (CVD) outcomes. A systematic review was performed to evaluate the relationship between coronary atherosclerotic plaque burden changes measured by intravascular ultrasound (IVUS) and CVD outcomes. Research design and methods Rigorous systematic review methodology was used to identify prospective studies of any design assessing the relationship between atherosclerotic plaque volume (percentage or total atheroma volume [PAV or TAV]) changes and CVD outcomes, using multivariable analyses. Main outcome measures CVD outcomes including major adverse cardiac events (MACEs) and major adverse cardiac and cerebrovascular events (MACCEs). Results Literature searches from inception to February 2015 retrieved 6958 records after de-duplication. From these four studies (14 papers) were included. One study reported a significantly lower rate of CVD outcomes associated with a greater reduction in PAV (hazard ratio [HR] 0.26, 95% confidence interval [CI] 0.07-0.83). One study reported that large plaque volume was significantly associated with a greater risk of major adverse cardiac events (MACEs) (HR 1.73, 95% CI: 1.02-2.96). Similarly, a third study reported a significant increase in MACE with an increase in baseline PAV (HR 1.51, 95% CI: 1.06-2.51). Only one potentially inadequately powered Japanese study did not find a statistically significant relationship between PAV changes and MACE. Conclusions The current evidence suggests an independent and statistically significant association between increases in coronary atherosclerotic plaque burden measured by IVUS and greater long-term risk of future CVD outcomes. However, this evidence comes from a limited number of studies which mainly focus on Japanese populations and populations after PCI. Further large prospective studies are required to confirm these findings.