PCSK9 (Proprotein convertase subtilisin/kexin type 9) inhibitors: past, present, and the future

Safety of Monoclonal Antibodies Inhibiting PCSK9 in Pregnancy: Disproportionality Analysis in VigiBase®

Safety data on the use of monoclonal antibodies inhibiting proprotein convertase subtilisin/kexin type 9 in pregnancy are scarce. This study queried VigiBase®, the World Health Organization global pharmacovigilance database, to search for signals of disproportionate reporting for pregnancy outcomes with alirocumab and evolocumab. As of November 22, 2023, there were 45 safety reports of exposure to evolocumab (N = 31) and alirocumab (N = 14) in pregnancy. Most of them originated from Europe (N = 25, 55.6%) and were more frequently reported by healthcare professionals (N = 35, 77.8%). Median patient age was 37 years (25th-75th percentiles; 32-41 years). Drug exposure occurred during pregnancy in 36 (80.0%) safety reports, via paternal exposure during pregnancy in four (8.9%), during lactation in three (6.7%), and in two safety reports the time of drug exposure remained unknown. Twenty safety reports (57.8%) merely reported drug exposure, while 19 (42.2%) also reported pregnancy outcomes, however, without specific maternal toxicities or patterns of birth defects. Spontaneous abortion was reported in eight safety reports without representing a signal of disproportionate reporting compared with either the full database (reporting odds ratio, ROR, 0.06 95% confidence interval, CI 0.03-0.12) or statins (ROR 0.16, 95% CI 0.08-0.32). In conclusion, this study showed that, currently, there are no signals of increased reporting of spontaneous abortion with alirocumab and evolocumab compared with the full database and statins in VigiBase®. Notwithstanding, lack of disproportionality is not synonymous with safety and, as disproportionality analyses depend on the number of safety reports that progressively accumulate in VigiBase®, they should be repeated at regular intervals to confirm the results of the present study.

Proteome-wide mendelian randomization investigates potential associations in heart failure and its etiology: emphasis on PCSK9

BACKGROUND

Heart failure (HF) is a prevalent clinical syndrome with diverse etiologies. It is crucial to identify novel therapeutic targets based on underlying causes. Here, we aimed to use proteome-wide Mendelian randomization (MR) analyses to identify the associations between genetically predicted elevated levels of circulating proteins and distinct HF outcomes, along with specific HF etiologies.

METHODS

Protein quantitative trait loci (pQTL) data for circulating proteins were sourced from the Atherosclerosis Risk in Communities (ARIC) study, encompassing 7,213 individuals and profiling 4,657 circulating proteins. Genetic associations for outcomes were obtained from the HERMES Consortium and the FinnGen Consortium. Colocalization analysis was employed to assess the impact of linkage disequilibrium on discovered relationships. For replication, two-sample MR was conducted utilizing independent pQTL data from the deCODE study. Multivariable MR (MVMR) and two-step MR were further conducted to investigate potential mediators.

RESULTS

Two proteins (PCSK9 and AIDA) exhibited associations with HF in patients with coronary heart disease (CHD), and four proteins (PCSK9, SWAP70, NCF1, and RELT) were related with HF in patients receiving antihypertensive medication. Among these associations, strong evidence from subsequent analyses supported the positive relationship between genetically predicted PCSK9 levels and the risk of HF in the context of CHD. Notably, MVMR analysis revealed that CHD and LDL-C did not exert a complete mediating effect in this relationship. Moreover, two-step MR results yielded valuable insights into the potential mediating proportions of CHD or LDL-C in this relationship.

CONCLUSIONS

Our findings provide robust evidence supporting the association between PCSK9 and concomitant HF and CHD. This association is partly elucidated by the influence of CHD or LDL-C, underscoring the imperative for additional validation of this connection and a thorough exploration of the mechanisms through which PCSK9 directly impacts ischemic HF.

PCSK9 inhibitors: current status and emerging frontiers in lipid control

INTRODUCTION

Atherosclerotic cardiovascular disease (ASCVD) is a leading cause of global mortality, imposing substantial healthcare economic burdens. Among the modifiable risk factors, hypercholesterolemia, especially elevated low-density lipoprotein cholesterol (LDL-C), plays a pivotal role in ASCVD development. Novel therapies such as PCSK9 (Proprotein Convertase Subtilisin/Kexin type 9) inhibitors are emerging to address this concern. These inhibitors offer the potential to reduce ASCVD risk by directly targeting LDL-C levels.

AREAS COVERED

The article reviews the structural and functional aspects of PCSK9, highlighting its role in LDL receptor regulation. The pharmacological strategies for PCSK9 inhibition, including monoclonal antibodies, binding peptides, gene silencing, and active immunization, are explored. Clinical evidence from various trials underscores the safety and efficacy of PCSK9 inhibitors in reducing LDL-C levels and potentially improving cardiovascular outcomes. Despite these promising results, challenges such as cost-effectiveness and long-term safety considerations are addressed.

EXPERT OPINION

Among PCSK9 inhibitors, monoclonal antibodies represent a cornerstone. Many trials have showed their efficacy in reducing LDL-C and the risk for major adverse clinical events, revealing long-lasting effects, with special benefits particularly for statin-intolerant and familial hypercholesterolemia patients. However, long-term impacts, high costs, and patient selection necessitate further research.

Immune Homeostasis Maintenance Through Advanced Immune Therapeutics to Target Atherosclerosis

Atherosclerosis remains the leading cause of coronary heart disease (CHD) with enormous health and societal tolls. Traditional drug development approaches have been focused on small molecule-based compounds that aim to lower plasma lipids and reduce systemic inflammation, two primary causes of atherosclerosis. However, despite the widely available lipid-lowering and anti-inflammatory small compounds and biologic agents, CHD prevalence still remains high. Based on recent advances revealing disrupted immune homeostasis during atherosclerosis pathogenesis, novel strategies aimed at rejuvenating immune homeostasis with engineered immune leukocytes are being developed. This chapter aims to assess basic and translational efforts on these emerging strategies for the effective development of atherosclerosis treatment, as well as key challenges in this important translational field.

Cholesterol in colorectal cancer: an essential but tumorigenic precursor?

Colorectal cancer (CRC) is one of the most lethal human malignancies, and with the growth of societies and lifestyle changes, the rate of people suffering from it increases yearly. Important factors such as genetics, family history, nutrition, lifestyle, smoking, and alcohol can play a significant role in increasing susceptibility to this cancer. On the other hand, the metabolism of several macromolecules is also involved in the fate of tumors and immune cells. The evidence discloses that cholesterol and its metabolism can play a role in the pathogenesis of several cancers because there appears to be an association between cholesterol levels and CRC, and cholesterol-lowering drugs may reduce the risk. Furthermore, changes or mutations of some involved genes in cholesterol metabolism, such as CYP7A1 as well as signaling pathways, such as mitogen-activated protein kinase (MAPK), can play a role in CRC pathogenesis. This review summarized and discussed the role of cholesterol in the pathogenesis of CRC as well as available cholesterol-related therapeutic approaches in CRC.

PCSK9: A emerging participant in heart failure

Heart failure (HF) is a complex clinical syndrome caused by various cardiovascular diseases. Its main pathogenesis includes cardiomyocyte loss, myocardial energy metabolism disorder, and activation of cardiac inflammation. Due to the clinically unsatisfactory treatment of heart failure, different mechanisms need to be explored to provide new targets for the treatment of this disease. Proprotein convertase subtilisin/kexin type 9 (PCSK9), a gene mainly related to familial hypercholesterolemia, was discovered in 2003. Aside from regulating lipid metabolism, PCSK9 may be involved in other biological processes such as apoptosis, autophagy, pyroptosis, inflammation, and tumor immunity and related to diabetes and neurodegenerative diseases. Recently, clinical data have shown that the circulating PCSK9 level is significantly increased in patients with heart failure, and it is related to the prognosis for heart failure. Furthermore, in animal models and patients with myocardial infarction, PCSK9 in the infarct margin area was also found to be significantly increased, which further suggested that PCSK9 might be closely related to heart failure. However, the specific mechanism of how PCSK9 participates in heart failure remains to be further explored. The purpose of this review is to summarize the potential mechanism of PCSK9's involvement in heart failure, thereby providing a new treatment strategy for heart failure.

Plasma Levels of Proprotein Convertase Subtilisin/Kexin Type 9 Are Inversely Associated with N-Terminal Pro B-Type Natriuretic Peptide in Older Men and Women

BACKGROUND AND AIMS

Cardiac natriuretic peptides (NPs) exert several metabolic effects, including some on lipid metabolism. Higher NPs levels are likely to be associated with a favorable lipid profile. In in vitro studies, NPs have been found to modulate low-density lipoprotein receptor (LDLR) trafficking by preventing proprotein convertase subtilisin/kexin type 9 (PCSK9) overexpression. The aim of our study is to investigate a possible association between plasma levels of PCSK9 and N-terminal pro B-type natriuretic peptide (NT-proBNP) in vivo.

METHODS

We performed a cross-sectional study on 160 consecutive older male and female patients hospitalized for medical conditions. Patients taking lipid-lowering drugs and patients with an admission diagnosis of acute heart failure were excluded. Fasting blood samples were collected after clinical stabilization of the acute illness, the day before discharge.

RESULTS

The mean age was 87.8 ± 6.4 years with a female prevalence (62.5%). The median NT-proBNP was 2340 (814-5397) pg/mL. The mean plasma PCSK9 was 275.2 ± 113.2 ng/mL. We found an inverse correlation between plasma PCSK9 and NT-proBNP (r = -0.280; p = 0.001). This association was confirmed after taking into account NT-proBNP tertiles (plasma PCSK9 levels: 317.4 ± 123.6 ng/mL in the first tertile, 283.3 ± 101.8 ng/mL in the second tertile, 231.3 ± 99.0 ng/mL in the third tertile, p = 0.001) and even after an adjustment for confounding factors (beta = -0.361, p = 0.001 for ln(NT-proBNP); beta = -0.330, p = 0.001 for NT-proBNP tertiles). The strength of the correlation between plasma PCSK9 and NT-proBNP was likely greater in patients affected by type 2 diabetes mellitus (r = -0.483; p = 0.006) and in male patients (r = -0.431, p = 0.001).

CONCLUSION

The inverse association found between PCSK9 and NT-proBNP plasma levels in our real-life clinical study supports the hypothesis that NPs may play a role in cholesterol metabolism, possibly through an inhibitory action on circulating PCSK9 concentrations, thus increasing the availability of LDLR.

PCSK9 Monoclonal Antibodies: New Developments and Their Relevance in a Nucleic Acid-Based Therapy Era

Purpose of Review

To report on recent data about PCSK9 monoclonal antibodies and to evaluate their relevance in a nucleic acid–based therapy era for lipid lowering and prevention of cardiovascular disease.

Recent Findings

New methods of PCSK9 inhibition based on nucleic acid therapeutics such as antisense oligonucleotides, small interfering RNAs, and CRISPR tools for therapeutic gene editing are reported, and interesting new data regarding the clinical relevance of PCSK9 antibodies are discussed.

Summary

Promising methods of PCSK9 inhibition are in development, and one of them, the siRNA inclisiran targeting PCSK9, has already been approved for clinical use. However, PCSK9-mAb remains the PCSK9-inhibiting tool with the longest safety data and the only one having positive cardiovascular outcome trials. An ongoing cardiovascular outcome trial with inclisiran is planned to be completed in 2026. Other forms of PCSK9 inhibition, such as antisense oligonucleotides targeting PCSK9 and CRISPR base editing of PCSK9, are still in early phases of development, and their potential clinical relevance remains to be established.

How Can We Identify Very High-Risk Heterozygous Familial Hypercholesterolemia?

Heterozygous familial hypercholesterolemia (HeFH) is a genetic disorder that elevates low-density lipoprotein cholesterol and increases the risk of premature atherosclerotic cardiovascular disease (ASCVD). However, despite their atherogenic lipid profiles, the cardiovascular risk of HeFH varies in each individual. Their variety of phenotypic features suggests the need for better risk stratification to optimize their therapeutic management. The current review summarizes three potential approaches, including (1) definition of familial hypercholesterolemia (FH)-related risk scores, (2) genetic analysis, and (3) biomarkers. The International Atherosclerosis Society has recently proposed a definition of severe FH to identify very high-risk HeFH subjects according to their clinical characteristics. Furthermore, published studies have shown the association of FH-related genetic phenotypes with ASCVD, which indicates the genetic analysis's potential to evaluate individual cardiovascular risks. Biomarkers reflecting disease activity have been considered to predict the formation of atherosclerosis and the occurrence of ASCVD in HeFH subjects. Incorporating these risk stratifications will be expected to allocate adequate intensity of lipid-lowering therapies in HeFH subjects, which ultimately improves cardiovascular outcomes.

Efficacy and safety of alirocumab and evolocumab: a systematic review and meta-analysis of randomized controlled trials

AIMS

The effect of low-density lipoprotein cholesterol-lowering therapy with alirocumab or evolocumab on individual clinical efficacy and safety endpoints remains unclear. We aimed to evaluate the efficacy and safety of alirocumab and evolocumab in patients with dyslipidaemia or atherosclerotic cardiovascular disease.

METHODS AND RESULTS

We performed a review of randomized controlled trials (RCTs) comparing treatment with alirocumab or evolocumab vs. placebo or other lipid-lowering therapies up to March 2018. Primary efficacy endpoints were all-cause death, cardiovascular death, myocardial infarction (MI), and stroke. We estimated risk ratios (RR) and 95% confidence intervals (CI) using random effect models. We included 39 RCTs comprising 66 478 patients of whom 35 896 were treated with proprotein convertase subtilisin-kexin type 9 (PCSK9) inhibitors (14 639 with alirocumab and 21 257 with evolocumab) and 30 582 with controls. Mean weighted follow-up time across trials was 2.3 years with an exposure time of 150 617 patient-years. Overall, the effects of PCSK9 inhibition on all-cause death and cardiovascular death were not statistically significant (P = 0.15 and P = 0.34, respectively). Proprotein convertase subtilisin-kexin type 9 inhibitors were associated with lower risk of MI (1.49 vs. 1.93 per 100 patient-year; RR 0.80, 95% CI 0.74-0.86; I  2 = 0%; P < 0.0001), ischaemic stroke (0.44 vs. 0.58 per 100 patient-year; RR 0.78, 95% CI 0.67-0.89; I  2 = 0%; P = 0.0005), and coronary revascularization (2.16 vs. 2.64 per 100 patient-year; RR 0.83, 95% CI 0.78-0.89; I  2 = 0%; P < 0.0001), compared with the control group. Use of these PCSK9 inhibitors was not associated with increased risk of neurocognitive adverse events (P = 0.91), liver enzymes elevations (P = 0.34), rhabdomyolysis (P = 0.58), or new-onset diabetes mellitus (P = 0.97).

CONCLUSION

Proprotein convertase subtilisin-kexin type 9 inhibition with alirocumab or evolocumab was associated with lower risk of MI, stroke, and coronary revascularization, with favourable safety profile.

Dammarane-type saponins with proprotein convertase subtilisin/kexin type 9 inhibitory activity from Gynostemma pentaphyllum

Seven undescribed dammarane-type saponins, gypenosides LXXXI-LXXXVII, together with four known compounds, were isolated from the whole herb of Gynostemma pentaphyllum. The chemical structures of these undescribed compounds were elucidated on the basis of physical and spectroscopic analysis and comparison with literature data. All the isolates were evaluated for their proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitory activities in HepG2 cells. Among them, gypenosides LXXXII-LXXXVII, gynosaponin II, IV and VI suppressed the expression of PCSK9 in LPDS-induced HepG2 cells at 20 μM; gypenosides LXXXII, LXXXV and LXXXVII showed inhibitory activities against PCSK9 at 10 μM; notably, gypenoside LXXXII still exhibited inhibitory activity against PCSK9 at 5 μM.

High Dietary Intervention of Lauric Triglyceride Might be Harmful to Its Improvement of Cholesterol Metabolism in Obese Rats

Hypercholesterolemia is often considered to be a major risk factor for atherosclerosis, and medium-chain fatty acids have been found to reduce the total cholesterol (TC) level and maintain low-density lipoprotein cholesterol (LDL-c) stability. However, we unexpectedly found that the levels of TC and LDL-c were increased in obese rats treated with high-dose lauric triglycerides (LT). The study aimed to investigate the effect and mechanism of LT on cholesterol metabolism in obese rats. Our results showed that LT intervention could reduce cholesterol biosynthesis by downregulating the expression of HMG-CoA reductase in obese rats. LT increased the expression levels of PPARγ1, LXRα, ABCA1, and ABCG8 in the liver. These results indicated that LT could improve the lipid transfer and bile acid efflux. However, LT significantly increased the expression of PCSK 9, resulting in accelerated degradation of LDLR, thus reducing the transport of very LDL (VLDL) and LDL to the liver. Together with the increased expression of NPC1L1 protein, LT impaired the uptake of VLDL/LDL by the liver and increased the reabsorption of sterols, leading to an increase in the levels of TC and LDL-c in obese rats.

[The triglyceride-lowering effects of PCSK9 inhibitor differ in patients with different baseline triglyceride levels]

OBJECTIVE

To investigate the triglyceride (TG)-lowering effects of PCSK9 inhibitor in patients with in different baseline triglyceride levels.

METHODS

Between February, 2019 and March, 2020, a total of 59 patients were treated with PCSK9 inhibitor (Evolocumab) in 5 hospitals, including Nanfang Hospital, Guangdong Provincial People's Hospital, First Affiliated Hospital of Sun Yat-sen University, Foshan Nanhai District People's Hospital and Yulin First People's Hospital. According to baseline triglyceride levels, the patients were divided into normal TG group (< 1.70 mmol/L, n=24), mild hypertriglyceridemia group (1.70-2.29 mmol/L, n=11), moderate hypertriglyceridemia group (2.30-5.63 mmol/L, n=13), and severe hypertriglyceridemia group (≥5.64 mmol/L, n=11), and the changes in TG level after the treatment were compared among the 4 groups.

RESULTS

In the groups with normal and mildly elevated baseline TG level, the patients did not show significant changes in TG levels after the treatment. In patients with moderately and severely elevated baseline TG levels, treatment with PCSK9 inhibitor significantly reduced their TG levels (P < 0.005).

CONCLUSIONS

PCSK9 inhibitor has a significant TG-lowering effect in patients with moderate to severe hypertriglyceridemia but not in patients with only mildly elevated baseline TG level.

Lipoprotein Apheresis and Proprotein Convertase Subtilisin/Kexin Type 9 Inhibitors in Patients With Heterozygous Familial Hypercholesterolemia: A One Center Study

AIM

We evaluated the lipid-lowering (LL) effect of proprotein convertase subtilisin/kexin type 9 inhibitors (PCSK9i) in patients with heterozygous familial hypercholesterolemia (HeFH) treated with LL-drugs and lipoprotein apheresis (LA).

PATIENTS AND METHODS

The PCSK9i treatment (evolocumab 420 mg/4 weeks, alirocumab 150 mg/2 weeks, or alirocumab 75 mg/2 weeks: 9, 6, and 2 patients, respectively) was initiated in patients with HeFH (n = 17; aged 35-69 years, 10 men, previously treated with statins + ezetimibe ± colesevelam and LA sessions for 2-12 years). A lipid profile was obtained before and immediately after the LA session and before, 1 and 2 months after switching to PCSK9i treatment. The duration of PCSK9i therapy ranged from 3 to 18 months.

RESULTS

Median total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides (TG) levels before LA were 268, 198, 46, and 126 mg/dL, respectively, and decreased (at the end of the LA session) to 117, 50, 40, and 51 mg/dL, respectively (P < .001 for TC and P = .001 for all other comparisons). The median time-averaged LDL-C levels following LA were 155 (121, 176; median [25th, 75th percentile]) mg/dL. Median TC, LDL-C, and TG levels before PCSK9i therapy were 269, 190, and 127 mg/dL and decreased to 152, 100, and 95 mg/dL, respectively (P = .002, P < .002, and P < .03, respectively). Steady LDL-C levels with PCSK9i treatment were significantly lower compared with time-averaged LDL-C levels following LA (median value: 100 vs 155 mg/dL; P = .008). With PCSK9i, from 13 patients with CHD, 6 (46.1%) patients achieved LDL-C <70 mg/dL, and 2 patients (15.4%) achieved LDL-C <100 mg/dL. Lipoprotein apheresis was discontinued in all patients except for 2 who continued once monthly.

CONCLUSIONS

PCSK9i can reduce LDL-C more consistently over time compared with a transient decrease following LA in HeFH patients. PCSK9i therapy may reduce the frequency of LA. Larger trials are required to establish the clinical implications of PCSK9i in patients previously on LA.

PCSK9 Protein and rs562556 Polymorphism Are Associated With Arterial Plaques in Healthy Middle-Aged Population: The STANISLAS Cohort

Background PCSK9 (Proprotein convertase subtilisin/kexin type 9) binds low-density lipoprotein receptor, preventing its recycling. PCSK9 is a risk predictor and a biotarget in atherosclerosis. The PCSK9-rs562556 variant has been reported as a gain-of-function mutation. The aim of this study was to determine whether the PCSK9-low-density lipoprotein receptor-rs562556 axis is associated with carotid artery plaques between 2 visits separated by almost 20 years in a longitudinal population cohort. Methods and Results The STANISLAS (Suivi Temporaire Annuel Non-Invasif de la Santé des Lorrains Assurés Sociaux) cohort is a longitudinal familial cohort from the Lorraine region of France. Participants attending 2 visits (visit 1 and visit 4) separated by 18.5 years (mean) were included (n=997). Carotid artery plaques were determined with standardized vascular echography. The mean age of the adult population at visit 1 was 42±5 years. At visit 4, 203 (20.4%) participants had arterial plaques. Participants who developed arterial plaques were older (42.7±5.4 versus 41.7±4.7 years), more often male (60% versus 49%), smokers (29% versus 18%), with diabetes mellitus (6% versus 3%), and higher cholesterol levels (low-density lipoprotein cholesterol, 1.6±0.4 versus 1.5±0.3 g/L) (all P<0.05). The independent factors associated with arterial plaques were age, smoking, and low-density lipoprotein cholesterol. Higher PCSK9 levels were associated with arterial plaques on top of the clinical model (odds ratio, 2.14; 95% CI,= 1.28-3.58); the missense mutation coding the single-nucleotide polymorphism rs562556 was associated with both higher PCSK9 concentration and incident carotid arterial plaques. Conclusions Higher PCSK9 concentration was associated with the development of arterial plaques almost 20 years in advance in a healthy middle-aged population. Mutations of the single-nucleotide polymorphism rs562556 associated with both PCSK9 levels and arterial plaques reinforce the potential causality of our findings. PCSK9 inhibitors could be useful for primary cardiovascular prevention.

Enhanced clinical phenotyping by mechanistic bioprofiling in heart failure with preserved ejection fraction: insights from the MEDIA-DHF study (The Metabolic Road to Diastolic Heart Failure)

Background: Heart failure with preserved ejection fraction (HFpEF) is a heterogeneous syndrome for which clear evidence of effective therapies is lacking. Understanding which factors determine this heterogeneity may be helped by better phenotyping. An unsupervised statistical approach applied to a large set of biomarkers may identify distinct HFpEF phenotypes.Methods: Relevant proteomic biomarkers were analyzed in 392 HFpEF patients included in Metabolic Road to Diastolic HF (MEDIA-DHF). We performed an unsupervised cluster analysis to define distinct phenotypes. Cluster characteristics were explored with logistic regression. The association between clusters and 1-year cardiovascular (CV) death and/or CV hospitalization was studied using Cox regression.Results: Based on 415 biomarkers, we identified 2 distinct clusters. Clinical variables associated with cluster 2 were diabetes, impaired renal function, loop diuretics and/or betablockers. In addition, 17 biomarkers were higher expressed in cluster 2 vs. 1. Patients in cluster 2 vs. those in 1 experienced higher rates of CV death/CV hospitalization (adj. HR 1.93, 95% CI 1.12-3.32, p = 0.017). Complex-network analyses linked these biomarkers to immune system activation, signal transduction cascades, cell interactions and metabolism.Conclusion: Unsupervised machine-learning algorithms applied to a wide range of biomarkers identified 2 HFpEF clusters with different CV phenotypes and outcomes. The identified pathways may provide a basis for future research.Clinical significanceMore insight is obtained in the mechanisms related to poor outcome in HFpEF patients since it was demonstrated that biomarkers associated with the high-risk cluster were related to the immune system, signal transduction cascades, cell interactions and metabolismBiomarkers (and pathways) identified in this study may help select high-risk HFpEF patients which could be helpful for the inclusion/exclusion of patients in future trials.Our findings may be the basis of investigating therapies specifically targeting these pathways and the potential use of corresponding markers potentially identifying patients with distinct mechanistic bioprofiles most likely to respond to the selected mechanistically targeted therapies.

Association of PCSK9 plasma levels with metabolic patterns and coronary atherosclerosis in patients with stable angina

OBJECTIVE

Aim of this study was to evaluate the relationship of plasma PCSK9 with metabolic and inflammatory profile and coronary atherosclerotic burden in patients with suspected CAD enrolled in the EVINCI study.

METHODS

PCSK9 was measured in 539 patients (60.3 ± 8.6 years, 256 males) with symptoms of CAD characterized by risk factors, bio-humoral profiles, and treatment. N = 412 patients underwent coronary computed tomography angiography (CTA) to assess the presence and characteristics of coronary atherosclerosis. A CTA score, combining extent, severity, composition, and location of plaques was computed.

RESULTS

Patients were divided according to PCSK9 quartiles: I (< 136 ng/mL), II-III (136-266 ng/mL), and IV quartile (> 266 ng/mL). Compared with patients in quartile IV, patients in quartile I had a higher prevalence of the metabolic syndrome and higher values of body mass index. LDL- and HDL-cholesterol were significantly lower in patients in the quartile I than in those in quartile IV. Coronary CTA documented normal vessels in 30% and obstructive CAD in 35% of cases without differences among PCSK9 quartiles. Compared with patients with the highest levels, patients with the lowest PCSK9 levels had a higher CTA score mainly due to higher number of mixed non-obstructive coronary plaques. At multivariable analysis including clinical, medications, and lipid variables, PCSK9 was an independent predictor of the CTA score (coefficient - 0.129, SE 0.03, P < 0.0001), together with age, male gender, statins, interleukin-6, and leptin.

CONCLUSION

In patients with stable CAD, low PCSK9 plasma levels are associated with a particular metabolic phenotype (low HDL cholesterol, the metabolic syndrome, obesity, insulin resistance and diabetes) and diffuse non-obstructive coronary atherosclerosis. Trial registration ClinicalTrials.gov NCT00979199. Registered September 17, 2009.

Modelling the cost-effectiveness of PCSK9 inhibitors vs. ezetimibe through LDL-C reductions in a Norwegian setting

Aims

Despite the success of statins, there remains unmet clinical need in cardiovascular disease (CVD) prevention. New proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors reduce low-density lipoprotein cholesterol (LDL-C) by 55-65%. Two PCSK9 inhibitors, evolocumab, and alirocumab, were approved for use in Norway but not yet for reimbursement through public national insurance. We aim to explore the cost-effectiveness of these compared with available treatments in a Norwegian setting.

Methods and results

A state transition Markov model was developed to model the cost-effectiveness of PCSK9 inhibitors for prevention of coronary heart disease, ischaemic strokes, and death among high-risk patient subpopulations in Norway, in both primary and secondary settings. Evolocumab and alirocumab are compared against ezetimibe and standard treatment. Risk of CVD is based on population incidence rates and adjusted according to baseline risk factors. Preventative effect of treatment was modelled according to absolute reduction in LDL-C. PCSK9 inhibitors were never found to be cost-effective in primary prevention. In secondary prevention they were cost-effective only for older, high-risk patients. The lowest cost-effectiveness ratios were for heterozygous familial hypercholesterolaemia patients and high-risk diabetics, with €63 200 and €68 400 per quality-adjusted life-year, respectively.

Conclusion

High lifetime costs of PCSK9 inhibitors may not be offset by estimated health gains for most eligible patients. PCSK9 inhibitors are found in the model only to be cost-effective in secondary prevention for older patients with high absolute risk of CVD. This picture is likely to change as price decreases. Future research is needed to determine the long-term preventative effects of PCSK9 inhibitors.

PCSK9 is Expressed in Human Visceral Adipose Tissue and Regulated by Insulin and Cardiac Natriuretic Peptides

Proprotein convertase subtilisin/kexin type 9 (PCSK9) binds to and degrades the low-density lipoprotein receptor (LDLR), contributing to hypercholesterolemia. Adipose tissue plays a role in lipoprotein metabolism, but there are almost no data about PCSK9 and LDLR regulation in human adipocytes. We studied PCSK9 and LDLR regulation by insulin, atrial natriuretic peptide (ANP, a potent lipolytic agonist that antagonizes insulin), and LDL in visceral adipose tissue (VAT) and in human cultured adipocytes. PCSK9 was expressed in VAT and its expression was positively correlated with body mass index (BMI). Both intracellular mature and secreted PCSK9 were abundant in cultured human adipocytes. Insulin induced PCSK9, LDLR, and sterol-regulatory element-binding protein-1c (SREBP-1c) and -2 expression (SREBP-2). ANP reduced insulin-induced PCSK9, especially in the context of a medium simulating hyperglycemia. Human LDL induced both mature and secreted PCSK9 and reduced LDLR. ANP indirectly blocked the LDLR degradation, reducing the positive effect of LDL on PCSK9. In conclusion, PCSK9 is expressed in human adipocytes. When the expression of PCSK9 is induced, LDLR is reduced through the PCSK9-mediated degradation. On the contrary, when the induction of PCSK9 by insulin and LDL is partially blocked by ANP, the LDLR degradation is reduced. This suggests that NPs could be able to control LDLR levels, preventing PCSK9 overexpression.

Small molecules as inhibitors of PCSK9: Current status and future challenges

Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays an important role in regulating lipoprotein metabolism by binding to low-density lipoprotein receptors (LDLRs), leading to their degradation. LDL cholesterol (LDL-C) lowering drugs that operate through the inhibition of PCSK9 are being pursued for the management of hypercholesterolemia and reducing its associated atherosclerotic cardiovascular disease (CVD) risk. Two PCSK9-blocking monoclonal antibodies (mAbs), alirocumab and evolocumab, were approved in 2015. However, the high costs of PCSK9 antibody drugs impede their prior authorization practices and reduce their long-term adherence. Given the potential of small-molecule drugs, the development of small-molecule PCSK9 inhibitors has attracted considerable attention. This article provides an overview of the recent development of small-molecule PCSK9 inhibitors disclosed in the literature and patent applications, and different approaches that have been pursued to modulate the functional activity of PCSK9 using small molecules are described. Challenges and potential strategies in developing small-molecule PCSK9 inhibitors are also discussed.

Association between proprotein convertase subtilisin/kexin type 9 and late saphenous vein graft disease after coronary artery bypass grafting: a cross-sectional study

OBJECTIVE

The study aims to explore the association between serum proprotein convertase subtilisin/kexin type 9 (PCSK9) level and saphenous vein grafts disease (SVGD) after coronary artery bypass grafting (CABG).

DESIGN

A cross-sectional study.

SETTING

A secondary hospital in Tianjin City, China.

PARTICIPANTS

A total of 231 participants were included in the study. Inclusion criteria were as follows: age ≥18 years, previous CABG surgery at least 12 months ago, at least one SVG for bypass during CABG, abnormal non-invasive test results or recurrent stable angina pectoris by coronary angiography indications, and willing to participate and sign informed consent. Participants with any of the following were excluded from the study: congenital valvular disease, decompensated heart failure, anaemia defined as a haemoglobin level of <12 g/dL in women or <13 g/dL in men, malignant neoplasms, renal failure, severe hepatic disease, thyroid disease, acute or chronic inflammatory disease and chronic obstructive lung disease.

PRIMARY OUTCOME MEASURE

SVGD was defined as at least one SVG with significant stenosis (≥50%). Circulating PCSK9 levels were measured using commercial ELISA kits according to the manufacturer's instructions.

RESULTS

The mean PCSK9 level in the SVGD group was significantly higher than that in the patent group (275.2±38.6 vs 249.3±37.7, p<0.01). The multivariate logistic regression model revealed a significant association between serum PCSK9 and SVGD (OR 2.08, 95% CI 1.46-2.95) per 1 SD increase in serum PCSK9.

CONCLUSIONS

The present study is the first to identify an independent association between PCSK9 and late SVGD after adjustment for established cardiovascular risk factors. A multicentre prospective cohort study with large sample size should be conducted in the future to further research this relationship.

Emerging Trends in Clinical Research: With Implications for Population Health and Health Policy

Policy Points: Significant advances in clinical medicine that have broader societal relevance may be less accessible to population health researchers and policymakers because of increased specialization within fields. We describe important recent clinical advances and discuss their broader societal impact. These advances include more expansive strategies for disease prevention, the rise of precision medicine, applications of human microbiome research, and new and highly successful treatments for hepatitis C infection. These recent developments in clinical research raise important issues surrounding health care costs and equitable resource allocation that necessitate an ongoing dialogue among the fields of clinical medicine, population health, and health policy.

CONTEXT

Developments in clinical medicine have important implications for population health, and there is a need for interdisciplinary engagement among clinical medicine, the social sciences, and public health research. The aim of this article is to help bridge the divide between these fields by exploring major recent advances in clinical medicine that have important implications for population health.

METHODS

We reviewed the most cited articles published from 2010 to 2015 in 5 high-impact clinical journals and selected 5 randomized controlled trials and 2 related clinical practice guidelines that are broadly relevant to population health and policy.

FINDINGS

We discuss the following themes: (1) expanding indications for drug therapy and the inherent medicalization of the population as highlighted by studies and clinical guidelines supporting lower blood pressure targets or widespread statin use; (2) the tension in nutritional research between quantifying the impact of isolated nutrients and studying specific foods and dietary patterns, for example, the role of the Mediterranean diet in the primary prevention of cardiovascular disease; (3) the issue of high medication costs and the challenge of providing equitable access raised by the development of new and effective treatments for hepatitis C infection; (4) emerging clinical applications of research on the human microbiome as illustrated by fecal transplant to treat Clostridium difficile infections; and (5) the promise and limitations of precision medicine as demonstrated by the rise of novel targeted therapies in oncology.

CONCLUSIONS

These developments in clinical science hold promise for improving individual and population health and raise important questions about resource allocation, the role of prevention, and health disparities.

A retrospective study of NENs and miR-224 promotes apoptosis of BON-1 cells by targeting PCSK9 inhibition

Neuroendocrine neoplasms (NENs) represent relatively rare tumors. The lack of diagnostic, therapeutic method and prognostic factors makes them a challenge to us. We retrospectively reviewed the data of 205 NENs patients among which 157 cases were followed-up. Proprotein convertase subtilisin/kexin 9 (PCSK9), a regulator of low density lipoprotein cholesterol (LDL-C), was confirmed as a target gene of microRNA-224. We found an increased incidence of NENs from 2012 to 2015. Women were usually diagnosed at earlier stages than men (P < 0.05). Tumor grading was associated with primary tumor site, especially esophagus and cardia NENs all at G3 (P <0.001). Age, tumor grading and LDL-C levels were independent risk factors of digestive NENs. Low LDL-C level was significantly correlated with survival rate and median overall survival (OS, P < 0.05). MicroRNA-224 agomir and PCSK9 siRNA could promote apoptosis and suppress proliferation, invasion of BON-1 cells (P < 0.05), but increase the level of glucocorticoid (GC, P < 0.05). Taken together, age, tumor grading and LDL-C level are independent risk factors of NENs. The miR-224/PCSK9/GC axis binds to tumorigenesis and prognosis of pancreatic NENs (p-NENs).

Advancement in nanotechnology-based approaches for the treatment and diagnosis of hypercholesterolemia

Cardiovascular diseases have been the major cause of mortality and morbidity all over the world accounting for more than 80% of the deaths from heart attacks and strokes. Hypercholesterolemia, an autosomal disorder of lipoprotein metabolism is one of the foremost causes of CVDs. An increased level of low-density lipoprotein cholesterol (LDL-C) in the plasma results in the rise of incidence rates in disease patients. Several conventional and combinational therapies have been proposed for lowering the LDL-C levels in the blood. These therapeutic agents are designed to target some crucial molecules that participates in the lipid metabolism such as apolipoprotein B, HMGCoA reductase, proprotein convertase subtilisin/kexin 9, etc. Although these therapies are effective but are associated with certain side effects. This article presents an overview on different conventional and nanotechnology-based approaches for the treatment and diagnosis of hypercholesterolemia. Numerous nanomaterial-based therapies including polymeric nanoparticles, cationic lipids, liposomes, dendrimers and inorganic nanoparticles have been discussed in lowering the cholesterol level along with recent advancement in diagnosis and imaging.

Future Lipid-Altering Therapeutic Options Targeting Residual Cardiovascular Risk

Low-density lipoproteins (LDL) play a causal role in the development of atherosclerosis, and reduction of LDL cholesterol with a statin is a cornerstone in prevention of cardiovascular disease. However, it remains an unmet need to reduce the residual risk on maximally tolerated statin alone or in combination with other drugs such as ezetimibe. Among the new LDL-lowering therapies, PCSK9 inhibitors appear the most promising class. Genetic studies suggest that triglyceride-rich lipoproteins are associated with cardiovascular risk and several promising triglyceride-lowering therapies are at various stages of development. At the opposite end, high-density lipoprotein (HDL) cholesterol seems to not be causally associated with cardiovascular risk, and thus far, trials designed to reduce cardiovascular risk by mainly raising HDL cholesterol levels have been disappointing. Nevertheless, new drugs targeting HDL are still in development. This review describes the new drugs reducing LDL, apolipoprotein(a), and triglyceride-rich lipoproteins, and the strategies to modulate HDL metabolism.

PCSK9: BIOLOGICAL ACTIVITY REGULATION AND CONNECTION WITH LIPID AND CARBOHYDRATE METABOLISM

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a serine protease which plays an important role in the regulation of LDL receptor (LDLR) expression and apolipoprotein B (apoB) lipoprotein cholesterol metabolism. It is well known that hepatic PCSK9 expression, its activity and secretion influence cholesterol homeostasis. An upregulation of PCSK9 causes an increase of LDLR degradation, which results in decrease of apoB lipoprotein uptake, and a consequent increase in plasma lipoprotein concentration, including LDL. Therefore, PCSK9 has become a new target for lipid lowering therapy. The aim of this review is to consider current data on metabolic and dietary regulation of PCSK9 and its effect on cholesterol and apoB lipoproteins metabolism and risk of cardiovascular disease.

Plaque burden, microstructures and compositions underachieving very low LDL-C levels

PURPOSE OF REVIEW

To summarize the impact of lowering LDL-C on plaque progression, microstructures and compositions.

RECENT FINDINGS

Low-density lipoprotein cholesterol (LDL-C) is a major therapeutic target to prevent atherosclerotic cardiovascular disease. Intravascular imaging has elucidated antiatherosclerotic effects of lowering LDL-C in vivo. Intensive control of LDL-C with a statin has been shown to slow plaque progression and induce its regression if very low LDL-C level is achieved. This therapeutic approach has been also demonstrated to modulate plaque microstructures and compositions. These mechanistic insights on intravascular imaging support the benefit of lowering LDL-C in achieving better cardiovascular outcomes.

SUMMARY

Lowering LDL-C level has become the first-line therapy in the primary and secondary prevention settings. The effects of lowering LDL-C on plaque progression, microstructures and compositions will be reviewed in this article.

Nutritional and Lipid Modulation of PCSK9: Effects on Cardiometabolic Risk Factors

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a serine protease involved in the regulation of LDL receptor (LDLR) expression and apolipoprotein B lipoprotein cholesterol metabolism. Hepatic PCSK9 protein expression, activity, and secretion have been shown to affect cholesterol homeostasis. An upregulation of hepatic PSCK9 protein leads to increased LDLR degradation, resulting in decreased uptake of apoB lipoproteins and a consequent increase in the plasma concentration of these lipoproteins, including LDL and chylomicron remnants. Hence, PCSK9 has become a novel target for lipid-lowering therapies. The aim of this review is to outline current findings on the metabolic and dietary regulation of PCSK9 and effects on cholesterol, apoB lipoprotein metabolism, and cardiovascular disease (CVD) risk. PCSK9 gene and protein expression have been shown to be regulated by metabolic status and the diurnal pattern. In the fasting state, plasma PCSK9 is reduced via modulation of the nuclear transcriptional factors, including sterol regulatory element-binding protein (SREBP) 1c, SREBP2, and hepatocyte nuclear factor 1α. Plasma PCSK9 concentrations are also known to be positively associated with plasma insulin and homeostasis model assessment of insulin resistance, and appear to be regulated by SREBP1c independently of glucose status. Plasma PCSK9 concentrations are stable in response to high-fat or high-protein diets in healthy individuals; however, this response may differ in altered metabolic conditions. Dietary n-3 polyunsaturated fatty acids have been shown to reduce plasma PCSK9 concentration and hepatic PCSK9 mRNA expression, consistent with their lipid-lowering effects, whereas dietary fructose appears to upregulate PCSK9 mRNA expression and plasma PCSK9 concentrations. Further studies are needed to elucidate the mechanisms of how dietary components regulate PCSK9 and effects on cholesterol and apoB lipoprotein metabolism, as well as to delineate the clinical impact of diet on PCSK9 in terms of CVD risk.

PCSK9 Monoclonal Antibodies in 2016: Current Status and Future Challenges

Cardiovascular disease remains the leading cause of morbidity and mortality in developed nations, with elevated low-density lipoprotein-cholesterol (LDL-C) levels being a major modifiable risk factor for coronary atherosclerosis. While lipid-lowering therapies such as statins are effective in lowering LDL-C, a proportion of patients do not achieve target LDL-C goals with statins or are intolerant to statins necessitating other treatment options. Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors are a new class of agents that reduce LDL-C beyond the maximum achievable LDL-C reductions with statins, and have been well studied in different patient groups. However, there are concerns regarding their potential adverse effects and cost, given that morbidity and mortality benefits have not yet been demonstrated. This state-of-the art review provides an overview of the development of PCSK9 inhibitors, the evidence regarding their clinical efficacy in specific target populations, and highlights future trials and challenges that need to be addressed before PCSK9 inhibitors are widely adopted into contemporary clinical practice.

Glycaemic control influences the relationship between plasma PCSK9 and LDL cholesterol in type 1 diabetes

Pro-protein convertase subtilisin/kexin type 9 (PCSK9) is a critical regulator of LDL cholesterol metabolism. Little is known, however, about the regulation of PCSK9 in patients with type 1 diabetes (T1D). In the present study, we aimed to determine the relationship between circulating PCSK9 and metabolic variables in T1D. Plasma PCSK9 levels were measured in 195 people with T1D (mean age 38.8 years, mean diabetes duration 17.2 years, mean glycated haemoglobin [HbA1c] 8.3%), who were free of any lipid-lowering agent. Plasma PCSK9 was positively correlated with LDL cholesterol (P = .0007), triglycerides (P = .004), apolipoprotein B (P = .005), HbA1c (P = .003), systolic (P = .003) and diastolic (P = .001) blood pressure and body mass index (0.02). In multivariate analysis, PCSK9 concentration was independently associated with HbA1c (P = .02) and LDL cholesterol (P = .03). After classifying patients according to HbA1c tertile, the correlation between PCSK9 and LDL cholesterol was only observed in the highest tertile (P = .0006; Rho = 0.43), whereas no correlation was found in the lowest and intermediate tertiles. This study suggests that good glycaemic control abolishes the positive relationship between PCSK9 and LDL cholesterol in patients with T1D; however, the underlying molecular mechanisms remain to be established.

2016 Russell Ross Memorial Lecture in Vascular Biology: Molecular-Cellular Mechanisms in the Progression of Atherosclerosis

Atherosclerosis is initiated by the subendothelial accumulation of apoB-lipoproteins, which initiates a sterile inflammatory response dominated by monocyte-macrophages but including all classes of innate and adaptive immune cells. These inflammatory cells, together with proliferating smooth muscle cells and extracellular matrix, promote the formation of subendothelial lesions or plaques. In the vast majority of cases, these lesions do not cause serious clinical symptoms, which is due in part to a resolution-repair response that limits tissue damage. However, a deadly minority of lesions progress to the point where they can trigger acute lumenal thrombosis, which may then cause unstable angina, myocardial infarction, sudden cardiac death, or stroke. Many of these clinically dangerous lesions have hallmarks of defective inflammation resolution, including defective clearance of dead cells (efferocytosis), necrosis, a defective scar response, and decreased levels of lipid mediators of the resolution response. Efferocytosis is both an effector arm of the resolution response and an inducer of resolution mediators, and thus its defect in advanced atherosclerosis amplifies plaque progression. Preclinical causation/treatment studies have demonstrated that replacement therapy with exogenously administered resolving mediators can improve lesional efferocytosis and prevent plaque progression. Work in this area has the potential to potentiate the cardiovascular benefits of apoB-lipoprotein-lowering therapy.

PCSK9 in chronic kidney disease

PURPOSE

Chronic kidney disease (CKD) is accompanied by a number of secondary metabolic dysregulations, such as lipid abnormalities, presenting with unique characteristics. Proprotein convertase subtilisin/kexin 9 (PCSK9) inhibitors have been introduced as the new era in the management of dyslipidemia with promising results in groups with refractory lipid abnormalities. Increasing number of studies investigate the possible association of PCSK9 levels with kidney function, especially with nephrotic range proteinuria, as well as its role as a prognostic cardiovascular risk marker in CKD. In this review, we discuss the existing evidence for PCSK9 levels in patient groups with nephrotic syndrome, non-dialysis CKD, end-stage renal disease and kidney transplantation.

METHODS

Online research was conducted in MEDLINE database to identify articles investigating PCSK9 in all different aspects of CKD. References from relevant studies were screened for supplementary articles.

RESULTS

Four cross-sectional studies, one secondary analysis, one publication from two independent cohort studies and one multicentre prospective cohort study assessed PCSK9 plasma levels in different subgroups of CKD patients. PCSK9 levels increase in nephrotic syndrome and have a positive correlation with proteinuria. In CKD patients, no correlation was found between PCSK9 levels and estimated GFR. Peritoneal dialysis patients have higher PCSK9 levels compared with hemodialysis and renal transplant patients as well as general population.

CONCLUSION

Accumulative evidence focuses on the possible association of PCSK9 levels with kidney function. No data are available for the administration of PCSK9 inhibitors in CKD patients. Further research will optimize knowledge on the role of PCSK9 levels and PCSK9 inhibitors in CKD.

Comprehensive genotyping in dyslipidemia: mendelian dyslipidemias caused by rare variants and Mendelian randomization studies using common variants

Dyslipidemias, especially hyper-low-density lipoprotein cholesterolemia and hypertriglyceridemia, are important causal risk factors for coronary artery disease. Comprehensive genotyping using the 'next-generation sequencing' technique has facilitated the investigation of Mendelian dyslipidemias, in addition to Mendelian randomization studies using common genetic variants associated with plasma lipids and coronary artery disease. The beneficial effects of low-density lipoprotein cholesterol-lowering therapies on coronary artery disease have been verified by many randomized controlled trials over the years, and subsequent genetic studies have supported these findings. More recently, Mendelian randomization studies have preceded randomized controlled trials. When the on-target/off-target effects of rare variants and common variants exhibit the same direction, novel drugs targeting molecules identified by investigations of rare Mendelian lipid disorders could be promising. Such a strategy could aid in the search for drug discovery seeds other than those for dyslipidemias.