Emerging low-density lipoprotein (LDL) therapies: Management of severely elevated LDL cholesterol—The role of LDL-apheresis

Advances in targeting LDL cholesterol: PCSK9 inhibitors and beyond

There is a direct relationship between the duration and level of exposure to low density lipoprotein cholesterol (LDL-C) levels over one's lifespan and cardiovascular events. Early treatment to lower elevated LDL-C is crucial for better outcomes with multiple therapies currently available to reduce atherogenic lipoproteins. Statins remain the foundation of LDL-C lowering therapy as one of the most cost-effective drugs to reduce atherosclerotic events (ASCVD) and mortality. Nonetheless, LDL-driven goal attainment remains suboptimal globally, highlighting a considerable need for non-statin therapies to address residual risk related to statin intolerance, non-adherence, and inherited lipoprotein disorders. LDL-C lowering interventions beyond statins include ezetimibe, PCSK9 monoclonal antibodies, inclisiran and bempedoic acid with specific guideline recommendations as to when to consider each. For patients with homozygous familial hypercholesterolemia requiring more advanced therapy, lomitapide and evinacumab are available, providing mechanisms that are not LDL receptor dependent. Lipoprotein apheresis remains an effective option for clinical familial hypercholesterolemia as well as elevated lipoprotein (a). There are investigational therapies being explored to add to our current armamentarium including CETP inhibitors, a third-generation PCSK9 inhibitor (small recombinant fusion protein oral PCSK9 inhibitor) and gene editing which aims to directly restore or disrupt genes of interest at the DNA level. This article is a brief review of the pharmacotherapy options beyond statins for lowering LDL-C and their impact on ASCVD risk reduction. Our primary aim is to guide physicians on the role these therapies play in achieving appropriate LDL-C goals, with an algorithm of when to consider each based on efficacy, safety and outcomes.

Emerging therapies for refractory hypercholesterolemia: a narrative review

Refractory hypercholesterolemia (RH) is characterized by the failure of patients to achieve therapeutic targets for low-density lipoprotein-cholesterol (LDL-C) despite receiving maximal tolerable doses of standard lipid-lowering treatments. It predominantly impacts individuals with familial hypercholesterolemia (FH), thereby elevating the risk of cardiovascular complications. The prevalence of RH is now recognized to be substantially greater than previously thought. This review provides a comprehensive insight into current and emerging therapies for RH patients, including groundbreaking genetic-based therapeutic approaches. The review places emphasis on the dependency of therapies on low-density lipoprotein receptors (LDLRs) and highlights the critical role of considering LDLR activity in RH patients for individualization of the treatment.

Updates on Non-Statin LDL-Lowering Therapy

PURPOSE OF REVIEW

There is ample evidence of the benefits and safety of low-density lipoprotein (LDL)-lowering therapies in the prevention of atherosclerotic cardiovascular disease. While statins remain the first-line agent for LDL reduction, several new therapies are now available. This narrative review provides an overview of currently available non-statin LDL-lowering agents, specifically mechanisms of action and data on efficacy and safety. It also discusses recommendations on their use in clinical practice.

RECENT FINDINGS

Ezetimibe, PCSK9 inhibitors, and bempedoic acid have proven safe and efficacious in reducing cardiovascular events in large randomized controlled trials. Inclisiran is a promising agent that suppresses PCSK9 mRNA translation and is currently under investigation in a large clinical outcomes randomized controlled trial assessing its effect on clinical outcomes. Expert consensus advocates for lower LDL targets in higher risk patients and escalation to or a combination of non-statin therapies as needed to achieve these goals.

Delipid extracorporeal lipoprotein filter from plasma system: a new intensive lipid lowering therapy for patients with acute ischemic stroke

Objectives

To investigate the safety and efficacy of the delipid extracorporeal lipoprotein filter from plasma (DELP) system, a new low-density lipoprotein cholesterol (LDL-C) adsorption system, in acute ischemic stroke (AIS) patients.

Patients and methods

In the present study, a total of 180 AIS patients were enrolled during March 2019 to February 2021. They were divided into DELP group (n1 = 90) and the control group (n2 = 90). The treatment protocol and vascular access of DELP treatment was established and evaluated. For the DELP group, clinical data and laboratory results including plasma lipid and safety parameters before and after the apheresis were collected and analyzed. For all participants, neurological scores were assessed and recorded.

Results

For the DELP group, 90 patients including 70 males and 20 females were included. The mean LDL-C was significantly decreased from 3.15 ± 0.80 mmol/L to 2.18 ± 0.63 mmol/L (30.79%, p < 0.001) during a single DELP treatment, and decreased from 3.42 ± 0.87 mmol/L to 1.87 ± 0.48 mmol/L (45.32%, p < 0.001) after two DELP treatments. No clinically relevant changes were observed in hematologic safety parameters and blood pressure levels except for hematocrit and total protein throughout the whole period of DELP treatment. The DELP group showed improvement relative to the control group in National Institute of Health stroke scale scores (NIHSS) on the 14th and 90th day after stroke. Moreover, the DELP group had a significantly higher ratio of mRS 0 to 1 on the 90th day after stroke.

Conclusion

The new LDL-C adsorption system, the DELP system, may provide a new option for intensive lipid lowering therapy in AIS patients in view of its safety, efficacy, and operation feasibility.

The Long-Term Efficacy and Safety of Evinacumab in Patients With Homozygous Familial Hypercholesterolemia

Background

Homozygous familial hypercholesterolemia (HoFH) is characterized by early-onset atherosclerotic cardiovascular disease due to the high low-density lipoprotein cholesterol (LDL-C) burden. Patients with null-null low-density lipoprotein receptor (LDLR) variants respond poorly, if at all, to statins and proprotein convertase subtilisin/kexin type 9 inhibitors, which act by upregulating LDLR expression. The 24-week double-blind treatment period (DBTP) of the phase 3 ELIPSE HoFH (Evinacumab Lipid Studies in Patients with Homozygous Familial hypercholesterolemia; NCT03399786) study demonstrated significant LDL-C reductions in patients with HoFH; LDL-C reductions were also observed in those with null-null LDLR mutations.

Objectives

The purpose of this study was to evaluate longer-term efficacy and safety of evinacumab in patients with HoFH from the ELIPSE HoFH study.

Methods

Patients with HoFH on stable lipid-lowering therapies (LLTs) ± lipoprotein apheresis and screening LDL-C ≥70 mg/dL who completed the DBTP entered the 24-week open-label treatment period (OLTP) and received intravenous evinacumab 15 mg/kg every 4 weeks. OLTP results were summarized descriptively.

Results

A total of 64 patients completed the DBTP and received open-label evinacumab. Despite multiple LLTs, the mean baseline LDL-C at DBTP entry was 250.5 ± 162.3 mg/dL. From baseline to week 48 (end of OLTP), evinacumab reduced mean LDL-C by 46.3% (mean reduction, 134.3 ± 117.3 mg/dL), with similar mean LDL-C reductions for patients with null-null (47.2%) and non-null variants (45.9%). Adverse events occurred in 47 (73.4%) patients; 4 (6.3%) patients experienced adverse events considered evinacumab-related (drug hypersensitivity, infusion-related reaction and asthenia, generalized pruritis, and muscle spasms).

Conclusions

In patients with HoFH, evinacumab demonstrated substantial and sustained LDL-C reduction regardless of LDLR function, and was generally well tolerated.

Just not cosmesis! Role of low-density lipoprotein apheresis in familial hypercholesterolemia: Experience at a newly developed tertiary care institution in Northern India

Familial hypercholesterolemia (FH) is characterized by an increase in plasma low-density lipoprotein-cholesterol (LDL-C) levels. It presents with tendon/skin xanthomas and premature atherosclerotic cardiovascular disease. The most available treatment options for FH are lipid-lowering medications such as statins, lifestyle modification, and LDL apheresis. As per American Society for Apheresis guidelines 2019, the treatment of FH using LDL apheresis falls under Category I. Here, we are reporting an interesting case of a young patient who presented with chief complaints of progressively increasing yellowish lesions around eyes, neck, hands, and legs. She was thoroughly investigated and was diagnosed provisionally as a case of Type 2 FH. Her total serum cholesterol and LDL-C were 717.2 mg/dl and 690.6 mg/dl, respectively, at presentation. One cycle of LDL apheresis was planned for her. We found immediate post-procedural reduction of 55.8% and 55.3% for total serum and LDL cholesterol levels respectively while 70.58% and 77.41% reduction in the levels from the day of presentation to the hospital.

The efficacy of double filtration plasmapheresis in the treatment of homozygous familial hypercholesterolemia: A single-center experience

INTRODUCTION

Different modalities of low-density lipoprotein (LDL) apheresis are used to treat patients with familial hypercholesterolemia (FH). The aim of this study was to describe the efficacy of the Double Filtration Plasmapheresis (DFPP) method for FH cases in our hands and to compare with other LDL apheresis techniques.

MATERIALS AND METHODS

This retrospective study was conducted between January 2016 and January 2018 in the University of Health Sciences, Diskapi Yildirim Beyazit Training and Research Hospital, Adult Hematology Clinic and Therapeutic Apheresis Unit. The study included 5 patients with a diagnosis of homozygous FH. A total of 288 DFFP procedures were performed twice a month (every 15 days) for 2 years.

RESULTS

The percentage reductions in Lipoprotein A, total cholesterol, Low Density Lipoprotein-C, High Density Lipoprotein-C and triglyceride levels were found to be 84%, 69.2%, 69.8%, 58.8% and 50.1% respectively (5 cases, n = 288). No cardiac event occurred after the initiation of LA with DFPP.

CONCLUSION

DFPP is an effective and safe LA method that can be used in the treatment of homozygous FH patients who do not respond to diet and statin therapy.

Vascular access in lipoprotein apheresis: a retrospective analysis from the UK's largest lipoprotein apheresis centre

INTRODUCTION

Lipoprotein apheresis (LA) has proven to be an effective, safe and life-saving therapy. Vascular access is needed to facilitate this treatment but has recognised complications. Despite consistency in treatment indication and duration there are no guidelines in place. The aim of this study is to characterise vascular access practice at the UK's largest LA centre and forward suggestions for future approaches.

METHODS

A retrospective analysis of vascular access strategies was undertaken in all patients who received LA treatment in the low-density lipoprotein (LDL) Apheresis Unit at Harefield Hospital (Middlesex, UK) from November 2000 to March 2016.

RESULTS

Fifty-three former and current patients underwent 4260 LA treatments. Peripheral vein cannulation represented 79% of initial vascular access strategies with arteriovenous (AV) fistula use accounting for 15%. Last used method of vascular access was peripheral vein cannulation in 57% versus AV fistula in 32%. Total AV fistula failure rate was 37%.

CONCLUSIONS

Peripheral vein cannulation remains the most common method to facilitate LA. Practice trends indicate a move towards AV fistula creation; the favoured approach receiving support from the expert body in this area. AV fistula failure rate is high and of great concern, therefore we suggest the implementation of upper limb ultrasound vascular mapping in all patients who meet treatment eligibility criteria. We encourage close ties between apheresis units and specialist surgical centres to facilitate patient counselling and monitoring. Further prospective data regarding fistula failure is needed in this expanding treatment field.

Protein changes in non-LDL-lipoproteins in familial hypercholesterolemia: implications in cardiovascular disease manifestation and outcome

PURPOSE OF REVIEW

Familial hypercholesterolemia, represents one of the most extreme clinical entities associated with premature coronary artery disease (CAD). However, clinical manifestation of CAD varies across cohorts and individual patients suggesting the existence of additional non-LDL factors potentially contributing to their cardiovascular burden.

RECENT FINDINGS

Changes in HDL-associated proteins appear as one of the potential additional factors contributing to the cardiovascular risk in familial hypercholesterolemia. Specifically, the content of Apo M-SP1 in HDL3 has been directly associated with cholesterol efflux capacity. In addition, a coordinated decrease in the content of Apo L1 and LCAT in HDL3 has been related to the presence of corneal arcus and to bad prognosis in familial hypercholesterolemia patients after an acute ischemic event. In fact, HDL3 particles of familial hypercholesterolemia patients have diminished antioxidant and anti-inflammatory function.

SUMMARY

The identification of the specific changes in HDL-associated proteins that contribute to the increased cardiovascular risk of familial hypercholesterolemia patients could be useful for the development of novel therapeutic targets. These novel strategies, in combination with current lipid-lowering therapies, may help to reduce the residual risk found in these patients.

Single Low-Density Lipoprotein Apheresis Does Not Improve Vascular Endothelial Function in Chronically Treated Hypercholesterolemic Patients

Objective. To investigate vascular endothelial function (VEF) responses to a single low-density lipoprotein (LDL) apheresis session in hypercholesterolemic patients undergoing chronic treatment. Methods. We measured brachial artery flow-mediated dilation (FMD), plasma lipids, vitamin E (α- and γ-tocopherol), markers of oxidative/nitrative stress (malondialdehyde (MDA) and nitro-γ-tocopherol (NGT)), and regulators of NO metabolism (arginine (ARG) and asymmetric dimethylarginine (ADMA)) prior to (Pre) and immediately following (Post) LDL apheresis and at 1, 3, 7, and 14 d Post in 5 hypercholesterolemic patients (52 ± 11 y). Results. Relative to Pre, total cholesterol (7.8 ± 1.5 mmol/L) and LDL-cholesterol (6.2 ± 1.2 mmol/L) were 61% and 70% lower (P < 0.01), respectively, at Post and returned to Pre levels at 14 d. Brachial FMD responses (6.9 ± 3.6%) and plasma MDA, ARG, and ADMA concentrations were unaffected by LDL apheresis. Plasma α-tocopherol, γ-tocopherol, and NGT concentrations were 52-69% lower at Post (P < 0.01), and α-tocopherol remained 36% lower at 1 d whereas NGT remained 41% lower at d 3. Conclusions. Acute cholesterol reduction by LDL apheresis does not alter VEF, oxidative stress, or NO homeostasis in patients treated chronically for hypercholesterolemia.

Targeting lipoprotein (a): an evolving therapeutic landscape

Robust epidemiologic and genetic studies have solidified the role of lipoprotein (a) [Lp(a)] as an independent and causal risk factor for cardiovascular disease. The increased cardiovascular risk of Lp(a) is mediated through both proatherogenic and prothrombotic/antifibrinolytic mechanisms. Several societies recommend Lp(a) screening for patients with high cardiovascular risk, although no consensus exists on the management of patients with elevated Lp(a). However, numerous pharmacologic approaches are being evaluated that have the potential to reduce Lp(a) and will be the focus of this review. The majority of these interventions have been developed for other lipid-lowering indications, but also lower Lp(a). There are also novel therapies in development that specifically target Lp(a). The efficacy of these therapies varies, and their role in the evolving lipoprotein therapeutic landscape has yet to be determined. Nevertheless, targeted Lp(a) reduction is certainly intriguing and will likely continue to be an active area of investigation in the future.

Mipomersen, an antisense oligonucleotide to apolipoprotein B-100, reduces lipoprotein(a) in various populations with hypercholesterolemia: results of 4 phase III trials

OBJECTIVE

Lp(a) is an independent, causal, genetic risk factor for cardiovascular disease and aortic stenosis. Current pharmacological lipid-lowering therapies do not optimally lower Lp(a), particularly in patients with familial hypercholesterolemia (FH).

APPROACH AND RESULTS

In 4 phase III trials, 382 patients on maximally tolerated lipid-lowering therapy were randomized 2:1 to weekly subcutaneous mipomersen 200 mg (n=256) or placebo (n=126) for 26 weeks. Populations included homozygous FH, heterozygous FH with concomitant coronary artery disease (CAD), severe hypercholesterolemia, and hypercholesterolemia at high risk for CAD. Lp(a) was measured 8× between baseline and week 28 inclusive. Of the 382 patients, 57% and 44% had baseline Lp(a) levels >30 and >50 mg/dL, respectively. In the pooled analysis, the mean percent decrease (median, interquartile range in Lp(a) at 28 weeks was significantly greater in the mipomersen group compared with placebo (-26.4 [-42.8, -5.4] versus -0.0 [-10.7, 15.3]; P<0.001). In the mipomersen group in patients with Lp(a) levels >30 or >50 mg/dL, attainment of Lp(a) values ≤30 or ≤50 mg/dL was most frequent in homozygous FH and severe hypercholesterolemia patients. In the combined groups, modest correlations were present between percent change in apolipoprotein B-100 and Lp(a) (r=0.43; P<0.001) and low-density lipoprotein cholesterol and Lp(a) (r=0.36; P<0.001) plasma levels.

CONCLUSIONS

Mipomersen consistently and effectively reduced Lp(a) levels in patients with a variety of lipid abnormalities and cardiovascular risk. Modest correlations were present between apolipoprotein B-100 and Lp(a) lowering but the mechanistic relevance mediating Lp(a) reduction is currently unknown.

Familial hypercholesterolemia: developments in diagnosis and treatment

BACKGROUND

Familial hypercholesterolemia (FH) is a congenital disorder of lipid metabolism characterized by a marked elevation of the plasma concentration of LDL (low-density lipoprotein) cholesterol beginning in childhood and by the early onset of coronary heart disease. It is among the commonest genetic disorders, with an estimated prevalence in Germany of at least 1 per 500 persons.

METHOD

Review of pertinent literature retrieved by a selective search.

RESULTS

FH is underdiagnosed and undertreated in Germany. It is clinically diagnosed on the basis of an elevated LDL cholesterol concentration (>190 mg/dL [4.9 mmol/L]), a family history of hypercholesterolemia, and early coronary heart disease, or the demonstration of xanthomas. The gold standard of diagnosis is the identification of the underlying genetic defect, which is possible in 80% of cases and enables the identification of affected relatives of the index patient. The recommended goals of treatment, based on the results of observational studies, are to lower the LDL cholesterol concentration by at least 50% or to less than 100 mg/dL (2.6 mmol/L) (for children: <135 mg/dL [3.5 mmol/L]). The target value is lower for patients with clinically overt atherosclerosis (<70 mg/dL [1.8 mmol/L]). Statins, combined with a health-promoting lifestyle, are the treatment of choice. Lipoprotein apheresis is used in very severe cases; its therapeutic effects on clinical endpoints and its side effect profile have not yet been documented in randomized controlled trials.

CONCLUSION

Familial hypercholesterolemia is a common disease that can be diagnosed simply and reliably on clinical grounds and by molecular genetic testing. Timely diagnosis and appropriate treatment can lower the risk of atherosclerosis in heterozygous patients to that of the general population.

AAV vectors expressing LDLR gain-of-function variants demonstrate increased efficacy in mouse models of familial hypercholesterolemia

RATIONALE

Familial hypercholesterolemia is a genetic disorder that arises because of loss-of-function mutations in the low-density lipoprotein receptor (LDLR) and homozygous familial hypercholesterolemia is a candidate for gene therapy using adeno-associated viral vectors. Proprotein convertase subtilisin/kexin type 9 (PCSK9) and inducible degrader of LDLR (IDOL) negatively regulate LDLR protein and could dampen adeno-associated viral vector encoded LDLR expression.

OBJECTIVE

We sought to create vectors expressing gain-of-function human LDLR variants that are resistant to degradation by human PCSK9 (hPCSK9) and IDOL and thereby enhance hepatic LDLR protein abundance and plasma LDL cholesterol reduction.

METHODS AND RESULTS

Amino acid substitutions were introduced into the coding sequence of human LDLR cDNA to reduce interaction with hPCSK9 and human IDOL. A panel of mutant human LDLRs was initially screened in vitro for escape from PCSK9. The variant human LDLR-L318D was further evaluated using a mouse model of homozygous familial hypercholesterolemia lacking endogenous LDLR and apolipoprotein B mRNA editing enzyme catalytic, APOBEC-1 (double knockout). Administration of wild-type human LDLR to double knockout mice, expressing hPCSK9, led to diminished LDLR activity. However, LDLR-L318D was resistant to hPCSK9-mediated degradation and effectively reduced cholesterol levels. Similarly, the LDLR-K809R\C818A construct avoided human IDOL regulation and achieved stable reductions in serum cholesterol. An adeno-associated viral vector serotype 8.LDLR-L318D\K809R\C818A vector that carried all 3 amino acid substitutions conferred partial resistance to both hPCSK9- and human IDOL-mediated degradation.

CONCLUSIONS

Amino acid substitutions in the human LDLR confer partial resistance to PCSK9 and IDOL regulatory pathways with improved reduction in cholesterol levels and improve on a potential gene therapeutic approach to treat homozygous familial hypercholesterolemia subjects.

HELP LDL apheresis reduces plasma pentraxin 3 in familial hypercholesterolemia

BACKGROUND

Pentraxin 3 (PTX3), a key component of the humoral arm of innate immunity, is secreted by vascular cells in response to injury, possibly aiming at tuning arterial activation associated with vascular damage. Severe hypercholesterolemia as in familial hypercholesterolemia (FH) promotes vascular inflammation and atherosclerosis; low-density lipoprotein (LDL) apheresis is currently the treatment of choice to reduce plasma lipids in FH. HELP LDL apheresis affects pro- and antiinflammatory biomarkers, however its effects on PTX3 levels are unknown. We assessed the impact of FH and of LDL removal by HELP apheresis on PTX3.

METHODS

Plasma lipids, PTX3, and CRP were measured in 19 patients with FH undergoing chronic HELP LDL apheresis before and after treatment and in 20 control subjects. In the patients assessment of inflammation and oxidative stress markers included also plasma TNFα, fibrinogen and TBARS.

RESULTS

At baseline, FH patients had higher (p = 0.0002) plasma PTX3 than matched control subjects. In FH PTX3 correlated positively (p≤0.05) with age, gender and CRP and negatively (p = 0.01) with HELP LDL apheresis vintage. The latter association was confirmed after correction for age, gender and CRP. HELP LDL apheresis acutely reduced (p≤0.04) plasma PTX3, CRP, fibrinogen, TBARS and lipids, but not TNFα. No association was observed between mean decrease in PTX3 and in LDL cholesterol. PTX3 paralleled lipids, oxidative stress and inflammation markers in time-course study.

CONCLUSION

FH is associated with increased plasma PTX3, which is acutely reduced by HELP LDL apheresis independently of LDL cholesterol, as reflected by the lack of association between change in PTX3 and in LDL levels. These results, together with the finding of a negative relationship between PTX3 and duration of treatment suggest that HELP LDL apheresis may influence both acutely and chronically cardiovascular outcomes in FH by modulating PTX3.

The severe hypercholesterolemia phenotype: clinical diagnosis, management, and emerging therapies

The severe hypercholesterolemia phenotype includes all patients with marked elevation of low-density lipoprotein cholesterol (LDL-C) levels. The most common cause is autosomal dominant hypercholesterolemia, an inherited disorder caused by mutations either in LDL receptor, apolipoprotein B (APOB), or proprotein convertase subtilisin kexin type 9 (PCSK9) genes. However, it is now known that many subjects with severe inherited hypercholesterolemia have no defects in these genes. These cases are caused either by mutations in genes yet to be identified or are consequences of polygenic, epigenetic, or acquired defects. Because the clinical consequences of extreme hypercholesterolemia are the same no matter the cause, the focus should be on the identification of subjects with severe hypercholesterolemia, followed by phenotypic screening of family members. Genetic screening is not necessary to diagnose or initiate treatment for the severe hypercholesterolemia phenotype. Management of severe hypercholesterolemia is based on risk factor modification and use of multiple lipid-lowering medications. Lipoprotein apheresis is indicated for coronary artery disease (CAD) patients taking maximally tolerated therapy and with LDL-C levels >200 mg/dl (>300 mg/dl if without CAD). A microsomal triglyceride transfer protein inhibitor and an antisense oligonucleotide against APOB have recently been approved for use in subjects with clinically diagnosed homozygous familial hypercholesterolemia. PCSK9 inhibitors, currently in phase II and III trials, lower LDL-C up to an additional 70% in the setting of maximally tolerated medical therapy and have the potential to reduce LDL-C to <70 mg/dl in most patients. Early identification of affected individuals and aggressive treatment should significantly reduce the burden of cardiovascular disease in society.

New modalities in the chronic ischemic diabetic foot management

The diabetic population is increasing worldwide at a staggering rate. Diabetic foot ulcers are a major contributor to nontraumatic lower limb amputations and peripheral arterial disease is one of main contributing pathophysiologic causes of diabetic ulcers. The dire need to reduce complication and wound healing recovery period of the chronic ischemic diabetic foot (CIDF) is indispensable to limb salvage and improvement of quality of life of patients with CIDF. This article discusses newer modalities that have been proposed to improve CIDF efficiently, safely, and effectively either alone or as adjuvants to conventional therapy.