PCSK9 Inhibitors: Clinical Relevance, Molecular Mechanisms, and Safety in Clinical Practice

PCSK9 Inhibitors: The Evolving Future

Introduction

PCSK9 inhibitors are a novel class of medications that lower LDL cholesterol (LDL-C) by increasing LDL receptor activity, promoting clearance of LDL-C from the bloodstream. Over the years, PCSK9 inhibitors have been explored as adjunct therapies to statins or as monotherapy in high-risk cardiovascular patients.

Aim

This review aims to provide an updated perspective on PCSK9 inhibitors, assessing their clinical efficacy, safety, and significance, especially in light of recent clinical trials.

Methods

The review examines the role of PCSK9 in cholesterol regulation and summarizes the results of major cardiovascular trials, including FOURIER, SPIRE-1, SPIRE-2, and ODYSSEY Outcomes. It also discusses emerging treatments like small interfering RNA (siRNA) therapies and evaluates PCSK9 inhibitor effects on LDL-C and lipoprotein(a) levels.

Results

Clinical trials have shown PCSK9 inhibitors reduce LDL-C by up to 60%. In the FOURIER trial, evolocumab reduced LDL-C by 59% and major cardiovascular events by 15%-20%. The SPIRE-2 trial, despite early termination, showed a 21% risk reduction in the primary composite endpoint with bococizumab. The ODYSSEY Outcomes trial reported a 57% LDL-C reduction with alirocumab, alongside a 15% reduction in adverse events. Emerging treatments like Inclisiran offer long-term LDL-C control with fewer doses. PCSK9 inhibitors are generally well-tolerated, with the most common side effect being injection site reactions.

Conclusion

PCSK9 inhibitors significantly lower LDL-C and reduce cardiovascular events, offering promising therapies for high-risk patients, including those with familial hypercholesterolemia (FH) and those who cannot tolerate statins. Future research will focus on optimizing these inhibitors, integrating complementary therapies, and exploring gene-editing technologies to improve patient outcomes.

Identification of novel proteins for coronary artery disease by integrating GWAS data and human plasma proteomes

Background

Most coronary artery disease (CAD) risk loci identified by genome-wide association studies (GWAS) are located in non-coding regions, hampering the interpretation of how they confer CAD risk. It is essential to integrate GWAS with molecular traits data to further explore the genetic basis of CAD.

Methods

We used the probabilistic Mendelian randomization (PMR) method to identify potential proteins involved in CAD by integrating CAD GWAS data (∼76,014 cases and ∼264,785 controls) and human plasma proteomes (N = 35,559). Then, Bayesian co-localization analysis, confirmatory PMR analysis using independent plasma proteome data (N = 7752), and gene expression data (N1 = 213, N2 = 670) were performed to validate candidate proteins. We further investigated the associations between candidate proteins and CAD-related traits and explored the rationality and biological functions of candidate proteins through disease enrichment, cell type-specific, GO, and KEGG enrichment analysis.

Results

This study inferred that the abundance of 30 proteins in the plasma was causally associated with CAD (P < 0.05/4408, Bonferroni correction), such as PLG, IL15RA, and CSNK2A1. PLG, PSCK9, COLEC11, ZNF180, ERP29, TCP1, FN1, CDH5, IL15RA, MGAT4B, TNFRSF6B, DNM2, and TGF1R were replicated in the confirmatory PMR (P < 0.05). PCSK9 (PP.H4 = 0.99), APOB (PP.H4 = 0.89), FN1 (PP.H4 = 0.87), and APOC1 (PP.H4 = 0.78) coding proteins shared one common variant with CAD. MTAP, TCP1, APOC2, ERP29, MORF4L1, C19orf80, PCSK9, APOC1, EPOR, DNM2, TNFRSF6B, CDKN2B, and LDLR were supported by PMR at the transcriptome level in whole blood and/or coronary arteries (P < 0.05). Enrichment analysis identified multiple pathways involved in cholesterol metabolism, regulation of lipoprotein levels and telomerase, such as cholesterol metabolism (hsa04979, P = 2.25E-7), plasma lipoprotein particle clearance (GO:0034381, P = 5.47E-5), and regulation of telomerase activity (GO:0051972, P = 2.34E-3).

Conclusions

Our integration analysis has identified 30 candidate proteins for CAD, which may provide important leads to design future functional studies and potential drug targets for CAD.

The Link between miRNAs and PCKS9 in Atherosclerosis

Cardiovascular disease (CDV) represents the major cause of death globally. Atherosclerosis, as the primary cause of CVD, is a chronic immune-inflammatory disorder with complex multifactorial pathophysiology encompassing oxidative stress, enhanced immune-inflammatory cascade, endothelial dysfunction, and thrombosis. An initiating event in atherosclerosis is the subendothelial accumulation of low-density lipoprotein (LDL), followed by the localization of macrophages to fatty deposits on blood vessel walls, forming lipid-laden macrophages (foam cells) that secrete compounds involved in plaque formation. Given the fact that foam cells are one of the key culprits that underlie the pathophysiology of atherosclerosis, special attention has been paid to the investigation of the efficient therapeutic approach to overcome the dysregulation of metabolism of cholesterol in macrophages, decrease the foam cell formation and/or to force its degradation. Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a secretory serine proteinase that has emerged as a significant regulator of the lipid metabolism pathway. PCSK9 activation leads to the degradation of LDL receptors (LDLRs), increasing LDL cholesterol (LDL-C) levels in the circulation. PCSK9 pathway dysregulation has been identified as one of the mechanisms involved in atherosclerosis. In addition, microRNAs (miRNAs) are investigated as important epigenetic factors in the pathophysiology of atherosclerosis and dysregulation of lipid metabolism. This review article summarizes the recent findings connecting the role of PCSK9 in atherosclerosis and the involvement of various miRNAs in regulating the expression of PCSK9-related genes. We also discuss PCSK9 pathway-targeting therapeutic interventions based on PCSK9 inhibition, and miRNA levels manipulation by therapeutic agents.

Reduction of Cardiovascular Risk Using Proprotein Convertase Subtilisin/Kexin Type 9 Inhibitors in Patients With Acute Coronary Syndrome: A Systematic Review

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a hepatic enzyme that regulates blood cholesterol levels by degrading low-density lipoprotein (LDL) receptors from the surface of hepatocytes. Studies have shown that inhibiting this molecule decreases the cardiovascular risk in individuals with atherosclerotic cardiovascular disease (ASCVD) by lowering low-density lipoprotein cholesterol (LDL-C). Two major cardiovascular outcome trials showed that the use of the PCSK9 inhibitors (alirocumab and evolocumab) in patients with recent acute coronary syndrome (ACS) is associated with a lower risk of further cardiovascular (CV) events. Information regarding the use of these monoclonal antibodies for primary prevention has also been reported by these trials. The goal of this systematic review is to describe the mechanism of PCSK9 inhibitors and further discuss their ability to reduce CV risk in high-risk populations. The search strategy was used in a systematic way using PubMed Central, Google Scholar, and ScienceDirect. We included randomized control trials (RCTs), systematic reviews, and narrative reviews in English published in the last five years. Observational studies, case reports, and case studies were excluded. The quality of the studies was evaluated using the Cochrane Collaboration Risk of Bias Tool, Assessment of Multiple Systematic Reviews 2, and Scale for the Assessment of Narrative Review Articles. A total of 10 articles were included in this systematic review. These included an RCT, a systematic review, and eight narrative reviews. Our study suggested that adding PCSK9 inhibitors to background statin therapy for selected patients with high-risk factors demonstrated substantial benefits in reducing overall CV morbidity and mortality after ACS. Multiple studies have demonstrated the short-term safety of low LDL-C levels caused by these drugs. However, long-term safety must be assessed with further studies.

Ischemic stroke caused by large-artery atherosclerosis: a red flag for subclinical coronary artery disease

Background

The coronary calcium score (CAC) measured on chest computerized tomography is a risk marker of cardiac events and mortality. We compared CAC scores in two multiethnic groups without symptomatic coronary artery disease: subjects in the chronic phase after stroke or transient ischemic attack and at least one symptomatic stenosis ≥50% in the carotid or vertebrobasilar territories (Group_athero) and a control group (Group_control).

Methods

In this cross-sectional study, Group_athero included two subgroups: Group_ExtraorIntra, with stenoses in either cervical or intracranial arteries, and Group_Extra&Intra, with stenoses in at least one cervical and one intracranial artery. Group_control had no history of prior stroke/transient ischemic attacks and no stenoses ≥50% in cervical or intracranial arteries. Age and sex were comparable in all groups. Frequencies of CAC ≥100 and CAC > 0 were compared between Group_athero and Group_control, as well as between Group_ExtraorIntr, Group_Extra&Intra, and Group_control, with bivariate logistic regressions. Multivariate analyses were also performed.

Results

A total of 120 patients were included: 80 in Group_athero and 40 in Group_control. CAC >0 was significantly more frequent in Group_athero (85%) than Group_control (OR, 4.19; 1.74-10.07; p = 0.001). Rates of CAC ≥100 were not significantly different between Group_athero and Group_control but were significantly greater in Group_Extra&Intra (n = 13) when compared to Group_control (OR 4.67; 1.21-18.04; p = 0.025). In multivariate-adjusted analyses, "Group_athero" and "Group_Extra&Intra" were significantly associated with CAC.

Conclusion

The frequency of coronary calcification was higher in subjects with stroke caused by large-artery atherosclerosis than in controls.

A Systematic Review on the Safety and Efficacy of PCSK9 Inhibitors in Lowering Cardiovascular Risks in Patients With Chronic Kidney Disease

Cardiovascular events caused by dyslipidemia are one of the leading causes of death in patients with Chronic Kidney Disease (CKD). Statins are the first line of treatment for patients with hyperlipidemia and in the treatment regimen for patients with CKD. Therefore, the introduction of Proprotein Convertase Subtilisin-Kexin type 9 inhibitors (PCSK9 inhibitors) is a viable and possibly effective treatment option for patients who, despite high doses of statins, struggle to lower their low-density lipoprotein cholesterol (LDL-C) levels. Our paper's objective is to explore the safety of these biological agents, particularly in patients with varying stages of impaired kidney function, and the correlating effectiveness in lowering their LDL-C levels, thereby reducing cardiovascular risks in these patients. We methodically retrieved relevant articles from PubMed, PubMed Central, Medline, and Google scholar in April 2022. We used the Medical Subject Heading (MeSH) Strategy and used the relevant keyword, then applied our inclusion and exclusion criteria; the initial search gave 10,542 results; with the removal of duplicates, irrelevant articles, and application of quality assessments done, we finally included 15 papers for our review with 37,188 patients. PCSK9 inhibitors are reliable, safe, and efficient therapy in lowering LDL-C levels in patients with CKD. However, its safety and efficacy in severe and end-stage kidney disease are grey, as other factors such as infections lead to morbidity and mortality. Future trials on chronic kidney disease and PCSK9 inhibitors should investigate the inhibitors' ability to improve kidney functions at all stages of kidney disease while lowering lipid levels and finally analyze the safety in patients with end-stage kidney disease.

Antitumor activity and molecular mechanism of proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibition

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a member of the proprotein convertase family of proteins that activate other proteins in cells. Functionally, PCSK9 binds to the receptor of low-density lipoprotein particles (LDL) to regulate cholesterol metabolism and lipoprotein homeostasis in human body. PCSK9 inhibition is a novel pharmacological strategy to control hypercholesterolemia and cardiovascular diseases. Recently accumulating evidence realizes that PCSK9 possesses other roles in cells, such as regulation of tissue inflammatory response, intratumoral immune cell infiltration, and tumor progression. This review discussed the advancement of PCSK9 research on its role and underlying mechanisms in tumor development and progression. For example, PCSK9 inhibition could attenuate progression of breast cancer, glioma, colon tumor, hepatocellular cancer, prostate cancer, and lung adenocarcinoma and promote apoptosis of glioma, prostate cancer, and hepatocellular cancer cells. PCSK9 deficiency could reduce liver metastasis of B16F1 melanoma cells by lowering the circulating cholesterol levels. PCSK9 gene knockdown substantially attenuated mouse tumor growth in vivo by activation of cytotoxic T cells, although PCSK9 knockdown had no effect on morphology and growth rate of different mouse cancer cell lines in vitro. PCSK9 inhibition thus can be used to control human cancers. Future preclinical and clinical studies are warranted to define anti-tumor activity of PCSK9 inhibition.

Genetics, Dyslipidemia, and Cardiovascular Disease: New Insights

PURPOSE OF REVIEW

The cardiovascular (CV) risk related to lipid disorders is well established and is based on a robust body of evidence from well-designed randomized clinical trials, as well as prospective observational studies. In the last two decades, significant advances have been made in understanding the genetic basis of dyslipidemias. The present review is intended as a comprehensive discussion of current knowledge about the genetics and pathophysiology of disorders that predispose to dyslipidemia. We also focus on issues related to statins and the proprotein convertase subtilisin/kexin type 9 (PCSK9) and some of its polymorphisms, as well as new cholesterol-lowering medications, including PCSK9 inhibitors.

RECENT FINDING

Cholesterol is essential for the proper functioning of several body systems. However, dyslipidemia-especially elevated low-density lipoprotein (LDL-c) and triglyceride levels, as well as reduced lipoprotein lipase activity-is associated with an increased risk of coronary artery disease (CAD). High-density lipoprotein (HDL-c), however, seems to play a role as a risk marker rather than as a causal factor of the disease, as suggested by Mendelian randomization studies. Several polymorphisms in the lipoprotein lipase locus have been described and are associated with variations in the activity of this enzyme, producing high concentrations of triglycerides and increased risk of CAD. Dyslipidemia, especially increased LDL-c and triglyceride levels, continues to play a significant role in CV risk. The combination of genetic testing and counseling is important in the management of patients with dyslipidemia of genetic etiology. Strategies focused on primary prevention can offer an opportunity to reduce CV events.