Littérature scientifique sur le sujet « Anti-PCSK9 monoclonal antibodies »

Abstract Background: Proprotein convertase subtilisin kexin type 9 (PCSK9) is gaining attention as a key regulator of serum LDL-cholesterol (LDLC). This novel serine protease causes the degradation of hepatic LDL receptors by an unknown mechanism. In humans, gain-of-function mutations in the PCSK9 gene cause a form of familial hypercholesterolemia, whereas loss-of-function mutations result in significantly decreased LDLC and decreased cardiovascular risk. Relatively little is known about PCSK9 in human serum. Methods: We used recombinant human PCSK9 protein and 2 different anti-PCSK9 monoclonal antibodies to build a sandwich ELISA. We measured PCSK9 and lipids in 55 human serum samples and correlated the results. We used the anti-PCSK9 antibodies to assay lipoprotein particle fractions separated by sequential flotation ultracentrifugation. Results: Serum concentrations of PCSK9 ranged from 11 to 115 μg/L and were directly correlated with serum concentrations of LDLC (r = 0.45, P = 0.001) and total cholesterol (r = 0.50, P = 0.0003), but not with triglycerides (r = 0.15, P = 0.28) or HDL cholesterol concentrations (r = 0.13, P = 0.36). PCSK9 was not detectable in any lipoprotein particle fraction, including LDL. Conclusions: PCSK9 is present in human serum, likely not associated with specific lipoprotein particles. The circulating concentrations of human PCSK9 are directly correlated with LDL and total cholesterol concentrations.

Administration of PCSK9-specific monoclonal antibodies, as well as peptide-based PCSK9 vaccines, can lower plasma LDL cholesterol by blocking PCSK9. However, these treatments also cause an increase in plasma PCSK9 levels, presumably due to the formation of immune complexes. Here, we utilize a versatile capsid virus-like particle (cVLP)-based vaccine platform to deliver both full-length (FL) PCSK9 and PCSK9-derived peptide antigens, to investigate whether induction of a broader polyclonal anti-PCSK9 antibody response would mediate more efficient clearance of plasma PCSK9. This head-to-head immunization study reveals a significantly increased capacity of the FL PCSK9 cVLP vaccine to opsonize and clear plasma PCSK9. These findings may have implications for the design of PCSK9 and other vaccines that should effectively mediate opsonization and immune clearance of target antigens.

Abstract: Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors (PCSK9-I) are novel therapeutic tools to decrease cardiovascular risk. These agents work by lowering the low-density lipoprotein cholesterol (LDL-C) in hypercholesterolemic patients who are statin resistant/intolerant. Current clinically approved and investigational PCSK9- I act generally by blocking PCSK9 activity in the plasma or suppressing its expression or secretion by hepatocytes. The most widely investigated method is the disruption of PCSK9/LDL receptor (LDLR) interaction by fully-humanized monoclonal antibodies (mAbs), evolocumab and alirocumab, which have been approved for the therapy of hypercholesterolemia and atherosclerotic cardiovascular disease (CVD). Besides, a small interfering RNA called inclisiran, which specifically suppresses PCSK9 expression in hepatocytes, is as effective as mAbs but with administration twice a year. Because of the high costs of such therapeutic approaches, several other PCSK9-I have been surveyed, including peptide-based anti-PCSK9 vaccines and small oral anti-PCSK9 molecules, which are under investigation in preclinical and phase I clinical studies. Interestingly, anti-PCSK9 vaccination has been found to serve as a more widely feasible and more cost-effective therapeutic tool over mAb PCSK9-I for managing hypercholesterolemia. The present review will discuss LDL-lowering and cardioprotective effects of PCSK9-I, mainly immunotherapy- based inhibitors including mAbs and vaccines, in preclinical and clinical studies.

As dyslipidemias remain one of the main risk factors for developing cardiovascular disease, the question of maintaining optimal lipid levels with pharmacotherapy remains a subject of interest worldwide. In contrast to conventional pharmacotherapy, human monoclonal antibodies directed against proprotein convertase subtilisin/kexin type 9 (PSCK9) and small interfering RNA- (siRNA-) based drug targeting PCSK9 represent a new strategy for managing lipid disorders and reducing cardiovascular risk. Inclisiran is a long-acting, synthetic siRNA that targets hepatic production of PCSK9 and consequently causes a reduction in LDL-C concentrations by approximately 50% compared to placebo. The structural modification of inclisiran has led to better stability and prolonged biological activity of the drug. The main advantage over conventional pharmacotherapy and anti-PCSK9 monoclonal antibodies is its favorable administration regimen (0–90–180 days), which should lead to much better compliance. Clinical trials conducted so far have confirmed the tolerability and efficacy of inclisiran in long-term PCSK9 and LDL-C level reductions. Moreover, a short-term follow-up on the safety of inclisiran showed a relatively good safety profile of the drug. However, it is still of great importance for ongoing and forthcoming clinical trials to be continued on a larger group of patients in order to assess long-term tolerability, efficacy, and safety of inclisiran.

Hypolipidemic therapy is one of the essential components for the management of patients with cardiovascular diseases (CVD). In this regard, the main task of modern research is to find new targets for creating additional effective groups of hypolipidemic drugs. In 2003, canadian and french research groups led by N. Seidah and M. Abifadel discovered a new enzyme proprotein convertase subtilisin/kexin type 9 (PCSK9), which later turned out to play an important role in lipid metabolism. The main mechanism of action of PCSK9 is to regulate the density of low-density lipoprotein receptors (LDLR) in the cell membrane of hepatocytes. Increased activity of PCSK9 significantly accelerates the degradation of LDL and leads to an increase in the concentration of atherogenic classes of lipoproteins-low-density lipoproteins (LDL). In contrast, reduced PCSK9 activity is accompanied by a decrease in LDL concentrations and a reduced risk of developing atherosclerosis and CVD. The second of the recently discovered and less studied mechanism of PCSK9 protearogenic action is an increase in inflammatory processes in the atherosclerotic plaque. Given this adverse contribution of PCSK9 to the development and progression of atherosclerosis and CVD, the main task of the researchers was to develop drugs that inhibit THIS enzyme. To date, several new groups of drugs have been developed that target the stages of biosynthesis and the function of PCSK9. In this article, we will focus in detail on discussing the mechanisms of action and effectiveness of the following groups of hypolipidemic drugs: anti-PCSK9 monoclonal antibodies (alirocumab, evolocumab), small interfering ribonucleic acids (incliciran), and antisense nucleotides.

: Initially described as a factor involved in liver regeneration and neuronal differentiation, proprotein convertase subtilisin/kexin type 9 (PCSK9) has become one of the key regulators of low-density lipoprotein cholesterol. Beside that, a number of studies have suggested PCSK9 may play a role in cancer biology. This is particularly true for gastroenteric (gastric and liver cancers) and lung cancers, where higher PCSK9 levels were associated with the increased ability of the tumor to develop and give metastasis as well as with reduced overall survival. Accordingly, monoclonal antibodies blocking PCSK9 were recently shown to synergize with immunotherapy in different types of cancers to achieve tumor growth suppression through an increased intratumoral infiltration of cytotoxic T cells. Anti-PCSK9 vaccines have been tested in animal models with encouraging results only in colon carcinoma. As most of this evidence is based on pre-clinical studies, this has led to some controversies and inconsistencies, thus suggesting that additional research is needed to clarify the topic. Finally, modulation of intracellular PCSK9 levels by silencing RNA (siRNA) may help understand the physiological and pathological mechanisms of PCSK9.

The article discusses a literature review reflecting the importance of identifying novel biomarkers in cardiology for improving conventional methods for diagnosing and stratifying risk in patients with acute coronary syndrome (ACS). Recently, more and more studies have published on such markers, in particular, on the proprotein convertase subtilisin/ kexin type 9 (PCSK9). The aim of this review was to analyze the associations of PCSK9 with clinical and laboratory parameters in patients with ACS. It has been demonstrated that the PCSK9 level in acute myocardial infarction is significantly increased. In patients with ACS, the level of PCSK9 is directly related to the duration of pain, the severity of coronary artery disease, familial hypercholesterolemia and lipid parameters, as well as the severity of coronary atherosclerosis according to the SYNTAX score. It was found that statin therapy before ACS significantly affects the association of PCSK9 with lipid profile. There are conflicting data on the associations of PCSK9 with the parameters of inflammatory response in ACS, as well as isolated evidence of the positive role of anti-IL-6 receptor monoclonal antibodies in ACS patients with dyslipidemia. The impact of PCSK9 on ACS prognosis is currently unstudied.

BACKGROUND AND AIM: Proprotein Convertase Subtilysin/Kexin Type 9 is a key regulator of LDL-C levels. Nevertheless, its physiological modulation is not fully understood. It is unclear whether PCSK9 has biological effects other than degrading the LDLR; consensus is lacking also on how PCSK9 is transported in the bloodstream, and whether this influences PCSK9 function. There are several conflicting data about PCSK9’s possible association with different lipoprotein subtypes. The biological function of the lipoprotein-bound PCSK9, also, is still a matter of debate. Due to its role in modulating plasma cholesterol levels, several approaches have been developed to modulate PCSK9 activity. Anti-PCSK9 mAbs represent the most advanced clinical available strategy for PCSK9 pharmacological inhibition, followed by the siRNA approach which seems promising. In this context, our aims were: 1) to establish a valid experimental procedure for the study of the possible association between PCSK9 and plasma lipoproteins. This would help us reach a clear idea about PCSK9’s lipoprotein compartmentation. 2) To characterize the lipoprotein fraction that binds PCSK9; 3) to address whether anti-PCSK9 mAbs therapy interferes with the PCSK9-LPs association, with resulting biological consequences. The capacity of PCSK9 to bind different lipoproteins raises the possibility that changes in the lipoprotein compartmentalization could regulate PCSK9 activity, and mAbs possible effects on such interaction may have biological consequences thus affecting their own pharmacological action. The study of such regulatory mechanisms could represent a potential avenue for developing new cholesterol-lowering drugs. METHODS: To reach our first aim, we compared several well-established methods in the lipoprotein isolation technique to clarify whether PCSK9 associates differently with circulating lipoproteins. The lipoprotein fractions collected were quantified for their cholesterol, triglycerides, PCSK9, apoB, apo AI and Lp(a) content using clinical grade reactives or ELISA. They were further characterized through immunoblotting, agarose gel electrophoresis, transmission electron microscopy (TEM), lipidomic and mass spectrometry. Following this, we analyzed PCSK9’s lipoprotein distribution among OptiPrep UC-isolated lipoproteins, obtained from anti-PCSK9 mAbs treated subjects before therapy (T0), and 1 (T1), 3 (T3) and 6 (T6) months after the beginning of treatment. The collected lipoprotein fractions were further characterized as described above. RESULTS AND CONCLUSION: Based on our results, the PCSK9-LDL association exists and is sensitive to high salt concentrations. OptiPrep UC and FPLC are both suitable methods for the study of this association. We believe that PCSK9 circulates mostly as a free type of protein, and partially (approx. 10-20% of total recovered PCSK9) associated through its active form with a light LDL subfraction resembling an IDL. We believe that this association originates in the circulation, as we did not find PCSK9 in the VLDL-containing fractions. PCSK9 did not associate with Lp(a) or HDL. Anti-PCSK9 mAbs administration induced a large decrease in LDL-C levels, - from 140,3±64,8 mg/dL to 51,5±35,6 mg/dL before and after treatment, respectively - parallel with a drastic increase in PCSK9 plasma levels - from 409,4±123,3 ng/mL to 3802,3±1001,0 ng/mL (n=22); despite this, they did not affect the PCSK9-LDL association but instead induce a more than 10-fold increase in the absolute quantity of LDL-bound PCSK9. Interestingly, the amount of PCSK9 recovered in the LDL fractions after therapy was about 242,3±164,8 ng/mL, like that of plasma of untreated subjects; this suggested that the LDL-bound PCSK9 may be inactive. Preliminary data obtained from Inclisiran-treated subjects suggest that the PCSK9- LDL association is maintained also when reducing both LDL and PCSK9 levels, therefore reinforcing the idea that the PCSK9-LDL association might be biologically meaningful.