Effects of lipoprotein apheresis on PCSK9 levels

Evinacumab: a new option in the treatment of homozygous familial hypercholesterolemia

INTRODUCTION

Familial hypercholesterolemia is a genetic disorder characterized by elevated levels of low-density lipoprotein cholesterol (LDL-C) since birth and an exceedingly high risk of premature cardiovascular disease, especially in the homozygous form (HoFH). Despite the availability of effective cholesterol-lowering drugs, substantial LDL-C and cardiovascular risk reductions in these patients are still problematic, especially in those carrying mutations in the low-density lipoprotein receptor (LDLR) gene.

AREAS COVERED

Loss-of-function mutations in angiopoietin-like 3 (ANGPTL3) encoding gene are associated with lower levels of LDL-C and reduced cardiovascular risk; the pharmacological inhibition of ANGPTL3 reduces LDL-C levels independently of LDLR. This approach can thus improve the treatment of HoFH using a monoclonal antibody targeting ANGPTL3 (evinacumab).

EXPERT OPINION

Most lipid-lowering agents available so far are insufficient to achieve an appropriate response in HoFH patients. The inhibition of ANGPTL3 with evinacumab halves LDL-C levels in HoFH patients by an LDLR-independent mechanism. The results obtained so far have clearly indicated a promising improvement in the management of these patients. As the reduction of CV risk is proportional to the absolute reduction in LDL-C levels, we can expect that treatment with evinacumab, added to the maximally tolerated lipid-lowering therapy, will turn into a significant clinical benefit.

The scientific basis and future of lipoprotein apheresis

Lipoprotein apheresis plays a vital role in the management of the severe hyperlipidemias that predispose to atherosclerosis. Determinants of efficacy are the acute reduction in lipoproteins achieved by each apheresis procedure, their frequency, and the fractional catabolic rates and hence pool sizes of low-density lipoprotein (LDL) or lipoprotein (a) (Lp(a)) of the patient being treated. A useful criterion of the efficacy of apheresis plus lipid-lowering drug therapy is the decrease in the interval (time-averaged) mean of serum total or LDL cholesterol or Lp(a) between procedures, expressed as the percent decrease in the interval means below the maximal levels of these lipoproteins when off all treatment. Recent advances in lipid-lowering drug therapy may diminish the use of lipoprotein apheresis but will not abolish its unique role as a therapeutic "last chance saloon," especially for children and pregnant women with homozygous familial hypercholesterolemia.

Plasma Purification Treatment Relieves the Damage of Hyperlipidemia to PBMCs

Background: Hyperlipidemia {hypercholesterolemia [cholesterol >5.18 mmol/L) or hypertriglyceridemia [triglycerides >2.3 mmol/L], mixed hyperlipidemia [cholesterol >5.18 mmol/L and triglycerides >2.3 mmol/L], and high low-density lipoproteinemia [low-density lipoprotein (LDL) >3.4 mmol/L]} is a strong risk factor for arteriosclerosis and cardiovascular disease (CVD). Therapy with lipid-lowering drugs often results in many side effects. Our study aimed to investigate the potential effects of non-drug therapy with double-filtration plasmapheresis (DFPP) on lipid metabolism-, endoplasmic reticulum (ER) stress-, and apoptosis-related proteins in peripheral blood mononuclear cells (PBMCs) before and after lipid clearance in patients with hyperlipidemia.

Methods: Thirty-five hyperlipidemia patients were selected. Proteins related to lipid metabolism [CD36, proprotein convertase subtilisin/kexin type 9 (PCSK9), and LDL receptor], ER stress [glucose-regulated protein 78 (Grp78), C/EBP homologous protein (CHOP), activating transcription factor 4 (ATF4), and eukaryotic initiation factor 2α (EIF2α)], and apoptosis [B-cell lymphoma-2 (Bcl-2), Bcl-2-associated X protein (BAX), and cysteinyl aspartate specific proteinase-3 (Caspase-3)] were assayed by Western blot, reactive oxygen species (ROS) were measured by flow cytometry (FCM), and ELISA detected serum inflammatory [interleukin (IL)-1β, IL-6, and tumor necrosis factor α (TNF-α)] factors.

Results: Compared with their pre-DFPP values, the values of most lipid metabolic parameters, such as cholesterol, triglycerides, LDL, lipoprotein a [Lp(a)], and small dense LDL (sdLDL) cholesterol, were reduced after DFPP. DFPP was associated with the downregulation of proteins related to lipid metabolism, ER stress, and apoptosis, resulting in decreased ROS and serum inflammatory factor release.

Conclusion: DFPP has lipid-lowering activity and can also regulate lipid metabolism-, ER stress-, and apoptosis-related proteins in PBMCs and reduce the levels of inflammatory factors in patients with hyperlipidemia (ClinicalTrials.gov number: NCT03491956).

Heparin-induced lipoprotein precipitation apheresis in dyslipidemic patients: A multiparametric assessment

Low-density lipoprotein (LDL) apheresis (LA) selectively eliminates lipoproteins containing apolipoprotein B 100 (ApoB100) on patients affected by severe dyslipidemia. In addition to lowering lipids, LA is thought to exert pleiotropic effects altering a number of other compounds associated with atherosclerosis, such as pro- and anti-inflammatory cytokines or pro-thrombotic factors. More knowledge needs to be gathered on the effects of LA, and particularly on its ability to modify blood components other than lipids. We performed a multiparametric assessment of the inflammatory, metabolic and proteomic profile changes after Heparin-induced lipoprotein precipitation (H.E.L.P.) apheresis on serum samples from nine dyslipidemic patients evaluating cholesterol and lipoproteins, plasma viscosity and density, metabolites, cytokines, PCSK9 levels and other proteins selectively removed after the treatment. Our results show that H.E.L.P. apheresis is effective in lowering lipoprotein and PCSK9 levels. Although not significantly, complement and inflammation-related proteins are also affected, indicating a possible transient epiphenomenon induced by the extracorporeal procedure.

Current Role of Lipoprotein Apheresis in the Treatment of High-Risk Patients

Lipoprotein apheresis (LA) is a therapeutic approach to save the lives of patients who are at an extremely high risk of developing cardiovascular events (CVE), especially after all other therapeutic options were not tolerated, or appeared not to be effective enough. Homozygous familial hypercholesterolemia represents a clear indication to start LA therapy. Another recognized indication is a severe hypercholesterolemia, which induced CVE, often in association with other risk factors. In the last years, an expressive elevation of lipoprotein(a) (Lp(a)) emerged as an indication for LA. In Germany, progress of atherosclerosis should have been documented before the permission to start LA therapy is given in these patients. Usually, all LA methods acutely decrease both LDL-C and Lp(a). However, specific columns which reduce only Lp(a) are available. Case reports and prospective observations comparing the situation before and during LA therapy clearly show a high efficiency with respect to the reduction of CVE, especially in patients with high Lp(a) levels. PCSK9 inhibitors may reduce the need for LA in patients with heterozygous or polygenetic hypercholesterolemia, but in some patients, a combination of these drugs with LA will be necessary. In the future, an antisense oligonucleotide against apolipoprotein(a) may offer an alternative therapeutic approach.

Effect of mipomersen on LDL-cholesterol in patients with severe LDL-hypercholesterolaemia and atherosclerosis treated by lipoprotein apheresis (The MICA-Study)

BACKGROUND AND AIMS

In this study, we evaluated the effect of mipomersen in patients with severe LDL-hypercholesterolaemia and atherosclerosis, treated by lipid lowering drugs and regular lipoprotein apheresis.

METHODS

This prospective, randomized, controlled phase II single center trial enrolled 15 patients (9 males, 6 females; 59 ± 9 y, BMI 27 ± 4 kg/m²) with established atherosclerosis, LDL-cholesterol ≥130 mg/dL (3.4 mmol/L) despite maximal possible drug therapy, and fulfilling German criteria for regular lipoprotein apheresis. All patients were on stable lipid lowering drug therapy and regular apheresis for >3 months. Patients randomized to treatment (n = 11) self-injected mipomersen 200 mg sc weekly, at day 4 after apheresis, for 26 weeks. Patients randomized to control (n = 4) continued apheresis without injection. The primary endpoint was the change in pre-apheresis LDL-cholesterol.

RESULTS

Of the patients randomized to mipomersen, 3 discontinued the drug early (<12 weeks therapy) for side effects. For these, another 3 were recruited and randomized. Further, 4 patients discontinued mipomersen between 12 and 26 weeks for side effects (moderate to severe injection site reactions n = 3 and elevated liver enzymes n = 1). In those treated for >12 weeks, mipomersen reduced pre-apheresis LDL-cholesterol significantly by 22.6 ± 17.0%, from a baseline of 4.8 ± 1.2 mmol/L to 3.7 ± 0.9 mmol/L, while there was no significant change in the control group (+1.6 ± 9.3%), with the difference between the groups being significant (p=0.006). Mipomersen also decreased pre-apheresis lipoprotein(a) (Lp(a)) concentration from a median baseline of 40.2mg/dL (32.5,71) by 15% (-19.4,3.6) though without significance (p=0.3).

CONCLUSIONS

Mipomersen reduces LDL-cholesterol (significantly) and Lp(a) (non-significantly) in patients on maximal lipid-lowering drug therapy and regular apheresis, but is often associated with side effects.

Lipoprotein apheresis in the management of severe hypercholesterolemia and of elevation of lipoprotein(a): current perspectives and patient selection

This review reports the current situation with respect to therapeutic options (lifestyle and drugs) reducing the concentrations of atherogenic low-density lipoprotein cholesterol (LDL-C) and lipoprotein(a) (Lp[a]). Three lipoprotein apheresis (LA) principles have been realized: precipitation, filtration, and adsorption. Available LA methods are herein described in detail - major components, pumps, extracorporeal volume, treated volume, and anticoagulation. General features of all LA methods as well as pleotropic effects are elaborated. Indications for LA therapy are quoted: homozygous familial hypercholesterolemia (HCH), severe HCH, and isolated elevation of Lp(a) and progress of atherosclerotic disease. A major focus is on the evidence of the effect of LA on cardiovascular outcome data, and the most important publications are cited in this context. The best studies have been performed in patients with elevated Lp(a) in whom cardiovascular events were reduced by more than 80%. Major adverse effects and contraindications are listed. The impact of an LA therapy on patient quality of life and the requirements they have to fulfill are also highlighted. Finally, the future role of LA in treating high-risk patients with high LDL-C and/or high Lp(a) is discussed. It is probable that the significance of LA for treating patients with elevated LDL-C will decrease (with the exception of homozygous familial HCH) due to the application of PCSK9 inhibitors. The antisense oligonucleotide against apolipoprotein(a) could replace LA in patients with high Lp(a), provided positive outcome data are generated.

Biology of proprotein convertase subtilisin kexin 9: beyond low-density lipoprotein cholesterol lowering

Proprotein convertase subtilisin kexin 9 (PCSK9) is a key regulator of low-density lipoprotein receptor levels and LDL-cholesterol levels. Loss-of-function mutations in PCSK9 gene are associated with hypocholesterolaemia and protection against cardiovascular disease, identifying PCSK9 inhibition as a valid therapeutic approach to manage hypercholesterolaemia and related diseases. Although PCSK9 is expressed mainly in the liver, it is present also in other tissues and organs with specific functions, raising the question of whether a pharmacological inhibition of PCSK9 to treat hypercholesterolaemia and associated cardiovascular diseases might be helpful or deleterious in non-hepatic tissues. For example, PCSK9 is expressed in the vascular wall, in the kidneys, and in the brain, where it was proposed to play a role in development, neurocognitive process, and neuronal apoptosis. A link between PCSK9 and immunity was also proposed as both sepsis and viral infections are differentially affected in the presence or absence of PCSK9. Despite the increasing number of observations, the debate on the exact roles of PCSK9 in extrahepatic tissues is still ongoing, and as very effective drugs that inhibit PCSK9 have become available to the clinician, a better understanding of the biological roles of PCSK9 is warranted.

Lipoprotein apheresis: present and future uses

PURPOSE OF REVIEW

For the past 40 years, apheresis, in particular, lipoprotein apheresis, has been the therapy of choice to lower LDL-C for familial hypercholesterolemia patients with uncontrolled dyslipidemia and cardiovascular disease. With the advent of recent and future lipid-modifying agents and their ability to lower LDL-C, the question arises on what will be the future of lipoprotein apheresis.

RECENT FINDINGS

Lipoprotein apheresis lowers not only plasma levels of apolipoprotein B lipoproteins but also markers of vascular inflammation and blood rheology. Other vascular diseases, not necessarily associated with familial hypercholesterolemia, such as nephrotic syndrome and peripheral arterial disease have profited from lipoprotein apheresis therapy. In 2013, the Food and Drug Administration approved lipoprotein apheresis therapy for patients with focal segmental glomerulosclerosis. Since 2010, the German healthcare ministry has approved lipoprotein apheresis therapy for patients with an elevated lipoprotein(a) and ongoing cardiovascular disease irrespective of LDL-C levels.

SUMMARY

Recent and future lipid-modifying therapies will most likely reduce the practice of lipoprotein apheresis therapy for familial hypercholesterolemia patients. Future implications for lipoprotein apheresis will involve vascular diseases that are at present lacking clinically effective therapy, whereas acute and chronic reductions of lipids, vascular inflammation, and/or rheology may improve the clinical outcome.