Safety and efficacy of alirocumab 150 mg every 2 weeks, a fully human proprotein convertase subtilisin/kexin type 9 monoclonal antibody: A Phase II pooled analysis

Effectiveness and safety of injectable PCSK9 inhibitors in dyslipidaemias' treatment and cardiovascular disease prevention: An overview of 86 systematic reviews and a network metaanalysis

OBJECTIVE

Multiple systematic reviews (SR) have been performed on the effects of proprotein convertase subtilisin/kexin type 9 inhibitors (PCSK9i), often providing conflicting findings. This overview and network meta-analysis (NMA) aimed to summarize SR findings on the efficacy and safety of PCSK9i and provide an updated NMA.

MATERIALS AND METHODS

MEDLINE (Pubmed), Scopus, Cochrane, Epistemonikos and Google Scholar were searched from inception to September 21, 2023 for SRs of randomized controlled trials (RCTs) and from January 1, 2020 to September 21, 2023 for additional RCTs. Double-independent study selection, data extraction and quality assessment were performed. Qualitative analysis was performed for SRs and a frequentist random-effects model NMA was performed for RCTs.

RESULTS

Totally, 86 SRs and 76 RCTs were included. Alirocumab (77/86 [90%]) and evolocumab (73/86 [85%]) were mostly analyzed. Associations from SRs (35/42 [83%]) and the updated NMA indicated PCSK9i benefit on major adverse cardiovascular events (MACEs). Reductions were also noted for cerebrovascular events (47/66 [71%]), coronary revascularization (29/33 [88%]) and myocardial infarction (41/63 [65%]). Alirocumab was associated with reductions on all-cause mortality (RR=0.82, 95%CI [0.72,0.94]). Data on any CV event reduction were conflicting (7/16 [44%]). Inclisiran appeared effective only on MACEs (RR=0.76, 95%CI [0.61,0.94]). No reductions in heart failure were observed (0/16). No increases were identified between PCSK9i and any (0/35) or serious adverse events (0/52). However, PCSK9i were associated with injection-site reactions (20/28 [71%]).

CONCLUSION

PCSK9i appeared to be effective in CV outcomes and their clinical application was generally safe.

Hepatic Sensing Loop Regulates PCSK9 Secretion in Response to Inhibitory Antibodies

BACKGROUND

Monoclonal antibodies against proprotein convertase subtilisin/kexin type 9 (PCSK9i) lower LDL-C by up to 60% and increase plasma proprotein convertase subtilisin/kexin type 9 (PCSK9) levels by 10-fold.

OBJECTIVES

The authors studied the reasons behind the robust increase in plasma PCSK9 levels by testing the hypothesis that mechanisms beyond clearance via the low-density lipoprotein receptor (LDLR) contribute to the regulation of cholesterol homeostasis.

METHODS

In clinical cohorts, animal models, and cell-based studies, we measured kinetic changes in PCSK9 production and clearance in response to PCSK9i.

RESULTS

In a patient cohort receiving PCSK9i therapy, plasma PCSK9 levels rose 11-fold during the first 3 months and then plateaued for 15 months. In a cohort of healthy volunteers, a single injection of PCSK9i increased plasma PCSK9 levels within 12 hours; the rise continued for 9 days until it plateaued at 10-fold above baseline. We recapitulated the rapid rise in PCSK9 levels in a mouse model, but only in the presence of LDLR. In vivo turnover and in vitro pulse-chase studies identified 2 mechanisms contributing to the rapid increase in plasma PCSK9 levels in response to PCSK9i: 1) the expected delayed clearance of the antibody-bound PCSK9; and 2) the unexpected post-translational increase in PCSK9 secretion.

CONCLUSIONS

PCSK9 re-entry to the liver via LDLR triggers a sensing loop regulating PCSK9 secretion. PCSK9i therapy enhances the secretion of PCSK9, an effect that contributes to the increased plasma PCSK9 levels in treated subjects.

Cardiovascular Outcomes of PCSK9 Inhibitors: With Special Emphasis on Its Effect beyond LDL-Cholesterol Lowering

PCSK9 inhibitors, monoclonal antibodies, are novel antihypercholesterolemic drugs. FDA first approved them in July 2015. PCSK9 protein (692-amino acids) was discovered in 2003. It plays a major role in LDL receptor degradation and is a prominent modulator in low-density lipoprotein cholesterol (LDL-C) metabolism. PCSK9 inhibitors are monoclonal antibodies that target PCSK9 protein in liver and inhibiting this protein leads to drastically lowering harmful LDL-C level in the bloodstream. Despite widespread use of the statin, not all the high-risk patients were able to achieve targeted level of LDL-C. Using PCSK9 inhibitors could lead to a substantial decrement in LDL-C plasma level ranging from 50% to 70%, either as a monotherapy or on top of statins. A large number of trials have shown robust reduction of LDL-C plasma level with the use of PCSK9 inhibitors as a monotherapy or in combination with statins in familial and nonfamilial forms of hypercholesterolemia. Moreover, PCSK9 inhibitors do not appear to increase the risk of hepatic and muscle-related side effects. PCSK9 inhibitors proved to be a highly potent and promising antihypercholesterolemic drug by decreasing LDL-R lysosomal degradation by PCSK9 protein. Statin drugs are known to have some pleiotropic effects. In this article, we are also focusing on the effects of PCSK9 inhibitor beyond LDL-C reduction like endothelial inflammation, atherosclerosis, its safety in patients with diabetes, obesity, and chronic kidney disease, and its influence on neurocognition and stroke.

PCSK9 Mutations in Familial Hypercholesterolemia: from a Groundbreaking Discovery to Anti-PCSK9 Therapies

PURPOSE OF REVIEW

In 2003, Abifadel et al. (Nat. Genet. 34:154-156, 2003) identified PCSK9, encoding proprotein convertase subtilisin/kexin type 9, as the third causal gene for autosomal dominant hypercholesterolemia. This review focuses on the main steps from this major breakthrough in familial hypercholesterolemia (FH) to the latest clinical trials with the anti-PCSK9 antibodies.

RECENT FINDINGS

The year 2015 was remarkable in cardiovascular disease through the field of cholesterol. Nearly 30 years after the discovery of statins, a new class of effective lipid-lowering drugs has emerged: the anti-PCSK9 antibodies. The discovery of the first gain-of-function mutations of PCSK9 in FH rapidly became the center of interest of researchers worldwide. Preclinical and clinical studies launched by pharmaceutical companies led to the first three anti-PCSK9 antibodies, two of which (evolocumab and alirocumab) reduce LDL cholesterol levels by 50-60% and received FDA and European Medicines Agency approvals in 2015 on top of statin therapy. Recently, results of the Further Cardiovascular Outcomes Research With PCSK9 Inhibition in Subjects With Elevated Risk (FOURIER) trial, the outcome trial of evolocumab over 2.2 years, showed a reduction of 15-20% in the risk of major cardiovascular outcomes in high-risk patients receiving statin therapy. Results of ODYSSEY OUTCOMES trial, evaluating the effect of alirocumab in 18,000 patients with established CVD are also eagerly awaited in 2018. The evolution of research on PCSK9, starting from the discovery of the first set of mutations in PCSK9 in FH in 2003, is an amazing example of successful translational research. It shows how rigorous and powered genetic analyses can lead to the discovery of a new class of lipid-lowering drugs that give hope in fighting high cholesterol levels and their cardiovascular complications.

Incorporation of PCSK9 inhibitors into prevention of atherosclerotic cardiovascular disease

Primary and secondary prevention of atherosclerotic cardiovascular disease (ASCVD) has become recently more complex than ever, leaving the clinicians perplexed with outdated guidelines and emerging evidence about new LDL-C lowering therapies. 2013 American College of Cardiology (ACC)/American Heart Association (AHA) guidelines have focused on high intensity statin therapy for specific groups of patients, while abandoning long established LDL-C goals, a strategy which no longer seems valid. PCSK9 (proprotein convertase subtilisin/kexin type 9) inhibitors have emerged as the add-on therapy on top of statins and/or ezetimibe for the treatment of hypercholesterolemia and ASCVD prevention. In several clinical trials, PCSK9 inhibitors have demonstrated their safety and robust LDL-C-lowering power. One completed cardiovascular (CV) outcomes trial (FOURIER; Further Cardiovascular Outcomes Research with PCSK9 Inhibitions in Subjects with Elevated Risk) has demonstrated that PCSK9 inhibition reduces rates of CV death as well as non-fatal stroke and MI, while another major CV outcome trial is under way (ODYSSEY-OUTCOMES). Several trials studying CV benefits of novel LDL-C-lowering therapies are also being conducted. Prompt revision of ACC/AHA guidelines is necessary. In the meantime, physicians need to use clinical judgment integrating the most recent evidence into their practice.

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

Reduction in low-density lipoprotein cholesterol (LDL-C), mainly with statins, has decreased the risk of cardiovascular events over the last few decades. However, there are several patient populations that warrant further decrease in LDL-C by additional cholesterol-lowering therapy other than statins. Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors are a new class of drugs that have been shown to further decrease LDL-C by 50-70% when administered as a monotherapy or on a background therapy with statins. Proprotein convertase subtilisin/kexin type 9 inhibitors are also an excellent example of drug development in which discovery of gene mutations and its clinical effects have rapidly progressed into successful preclinical and clinical studies with multiple Phases 1-3 clinical trials completed or ongoing to date. This review summarizes the rapid evolution of the drug from genetic discovery to identification of targets for the drugs, to animal and human testing, and to large clinical outcomes trials, followed by discussion on foreseeable challenges of PCSK9 inhibitors.