LPA disruption with AAV-CRISPR potently lowers plasma apo(a) in transgenic mouse model: A proof-of-concept study

Lipoprotein(a) as a Stroke Biomarker: Pathophysiological Pathways and Therapeutic Implications

Lipoprotein(a) [Lp(a)] has attracted widespread interest as a potential biomarker for cerebrovascular diseases due to its genetically determined and stable plasma concentration throughout life. Lp(a) exhibits pro-atherogenic and pro-thrombotic properties that contribute to vascular pathology in both extracranial and intracranial vessels. Elevated Lp(a) levels are strongly associated with large-artery atherosclerotic stroke, while data on its role in other ischemic subtypes and hemorrhagic stroke remains limited and inconsistent. Recent advances in Lp(a)-lowering therapies, such as antisense oligonucleotides and RNA-based agents, have demonstrated significant efficacy in reducing plasma Lp(a) levels. These advances have prompted increasing research into their potential application in the prevention and treatment of cerebrovascular diseases, aiming to determine whether Lp(a) reduction may translate into a reduced risk of stroke and large-artery atherosclerosis. This narrative review summarizes the current evidence on the association between Lp(a) and stroke, focusing on its utility in patient risk stratification. It also highlights existing knowledge gaps and outlines directions for future research, particularly in understanding subtype-specific effects and evaluating the clinical benefits of Lp(a)-targeted therapies.

Lipoprotein(a) as a Pharmacological Target: Premises, Promises, and Prospects

Atherosclerotic cardiovascular disease is a major health concern worldwide and requires effective preventive measures. Lp(a) (lipoprotein [a]) has recently garnered attention as an independent risk factor for astherosclerotic cardiovascular disease, with proinflammatory and prothrombotic mechanisms contributing to its atherogenicity. On an equimolar basis, Lp(a) is ~5 to 6 times more atherogenic than particles that have been widely associated with adverse cardiovascular outcomes, such as LDL (low-density lipoprotein). Lp(a) can enter the vessel wall, leading to the accumulation of oxidized phospholipids in the arterial intima, which are crucial for initiating plaque inflammation and triggering vascular disease progression. In addition, Lp(a) may cause atherothrombosis through interactions between apoA (apolipoprotein A) and the platelet PAR-1 (protease-activated receptor 1) receptor, as well as competitive inhibition of plasminogen. Because Lp(a) is mostly determined on genetic bases, a 1-time assessment in a lifetime can suffice to identify patients with elevated levels. Mendelian randomization studies and post hoc analyses of randomized trials of LDL cholesterol-lowering drugs showed a causal link between Lp(a) concentrations and cardiovascular outcomes, with therapeutic reduction of Lp(a) expected to contribute to estimated cardiovascular risk mitigation. Many Lp(a)-lowering drugs, including monoclonal antibodies, small interfering ribonucleic acids, antisense oligonucleotides, small molecules, and gene editing compounds, are at different stages of clinical investigation and show promise for clinical use. In particular, increased Lp(a) testing and treatment are expected to have a substantial impact at the population level, enabling the identification of high-risk individuals and the subsequent prevention of a large number of cardiovascular events. Ongoing phase 3 trials will further elucidate the cardiovascular benefits of Lp(a) reduction over the long term, offering potential avenues for targeted interventions and improved cardiovascular outcomes.

Lipid nanoparticle delivery of TALEN mRNA targeting LPA causes gene disruption and plasma lipoprotein(a) reduction in transgenic mice

Lipoprotein(a), or Lp(a), is encoded by the LPA gene and is a causal genetic risk factor for cardiovascular disease. Individuals with high Lp(a) are at risk for cardiovascular morbidity and are refractory to standard lipid-lowering agents. Lp(a)-lowering therapies currently in clinical development require repetitive dosing, while a gene editing approach presents an opportunity for a single-dose treatment. In this study, mRNAs encoding transcription activator-like effector nucleases (TALENs) were designed to target human LPA for gene disruption and permanent Lp(a) reduction. TALEN mRNAs were screened in vitro and found to cause on-target gene editing and target protein reduction with minimal off-target editing. TALEN mRNAs were then encapsulated with LUNAR, a proprietary lipid nanoparticle (LNP), and administered to transgenic mice that expressed a human LPA transgene. A single dose of TALEN mRNA-LNPs reduced plasma Lp(a) levels in mice by over 80%, which was sustained for at least 5 weeks. Moreover, both standard and long-read next-generation sequencing confirmed the presence of gene-inactivating deletions at LPA transgene loci. Overall, this study serves as a proof-of-concept for using TALEN-mediated gene editing to disrupt LPA in vivo, paving the way for the development of a feasible gene editing therapy for patients with high Lp(a).

Role of Lipoprotein (A) in aortic valve stenosis: Novel disease mechanisms and emerging pharmacotherapeutic approaches

Lipoprotein(a) (Lp(a)) has garnered increasing attention as a significant contributor to the pathogenesis of aortic stenosis (AS), prompting a focused investigation into innovative pharmacological strategies to target this lipoprotein and its associated risks. Despite its recognized role in AS progression, Lp(a) often remains overlooked in clinical assessments, mirroring the broader challenges observed in holistic disease management. This review delves into the mechanistic intricacies of Lp(a) involvement in AS pathophysiology and its potential as a therapeutic target. Drawing parallels with the imperative for healthcare providers to proactively engage with patients regarding treatment regimens, this review underscores the essential role of cardiologists and physicians in recognizing and addressing Lp(a) as a modifiable risk factor in AS management. Furthermore, it explores promising avenues of novel drug approaches, including emerging pharmacotherapies and targeted interventions, aimed at modulating Lp(a) levels and attenuating AS progression. By navigating the complexities of Lp(a) modulation and its implications for AS management, this review aims to bridge critical gaps in understanding and clinical practice, ultimately optimizing treatment strategies and improving patient outcomes in the realm of AS therapeutics.

Genetics of Calcific Aortic Stenosis: A Systematic Review

Background: Calcific aortic stenosis is the most prevalent valvular abnormality in the Western world. Factors commonly associated with calcific aortic stenosis include advanced age, male sex, hypertension, diabetes and impaired renal function. This review synthesises the existing literature on genetic associations with calcific aortic stenosis. Methods: A systematic search was conducted in the PubMed, Ovid and Cochrane libraries from inception to 21 July 2024 to identify human studies investigating the genetic factors involved in calcific aortic stenosis. From an initial pool of 1392 articles, 78 were selected for full-text review and 31 were included in the final qualitative synthesis. The risk of bias in these studies was assessed using the Newcastle Ottawa Scale. Results: Multiple genes have been associated with calcific aortic stenosis. These genes are involved in different biological pathways, including the lipid metabolism pathway (PLA, LDL, APO, PCSK9, Lp-PLA2, PONS1), the inflammatory pathway (IL-6, IL-10), the calcification pathway (PALMD, TEX41) and the endocrine pathway (PTH, VIT D, RUNX2, CACNA1C, ALPL). Additional genes such as NOTCH1, NAV1 and FADS1/2 influence different pathways. Mechanistically, these genes may promote a pro-inflammatory and pro-calcific environment in the aortic valve itself, leading to increased osteoblastic activity and subsequent calcific degeneration of the valve. Conclusions: Numerous genetic associations contribute to calcific aortic stenosis. Recognition of these associations can enhance risk stratification for individuals and their first-degree relatives, facilitate family screening, and importantly, pave the way for targeted therapeutic interventions focusing on the identified genetic factors. Understanding these genetic factors can also lead to gene therapy to prevent calcific aortic stenosis in the future.

Advancements in Omics and Breakthrough Gene Therapies: A Glimpse into the Future of Peripheral Artery Disease

Peripheral artery disease (PAD), a highly prevalent global disease, associates with significant morbidity and mortality in affected patients. Despite progress in endovascular and open revascularization techniques for advanced PAD, these interventions grapple with elevated rates of arterial restenosis and vein graft failure attributed to intimal hyperplasia (IH). Novel multiomics technologies, coupled with sophisticated analyses tools recently powered by advances in artificial intelligence, have enabled the study of atherosclerosis and IH with unprecedented single-cell and spatial precision. Numerous studies have pinpointed gene hubs regulating pivotal atherogenic and atheroprotective signaling pathways as potential therapeutic candidates. Leveraging advancements in viral and nonviral gene therapy (GT) platforms, gene editing technologies, and cutting-edge biomaterial reservoirs for delivery uniquely positions us to develop safe, efficient, and targeted GTs for PAD-related diseases. Gene therapies appear particularly fitting for ex vivo genetic engineering of IH-resistant vein grafts. This manuscript highlights currently available state-of-the-art multiomics approaches, explores promising GT-based candidates, and details GT delivery modalities employed by our laboratory and others to thwart mid-term vein graft failure caused by IH, as well as other PAD-related conditions. The potential clinical translation of these targeted GTs holds the promise to revolutionize PAD treatment, thereby enhancing patients' quality of life and life expectancy.

Advances in nucleic acid-targeted therapies for cardiovascular disease prevention

Nucleic acid-based therapies are being rapidly developed for prevention and management of cardiovascular diseases (CVD). Remarkable advancements have been achieved in the delivery, safety, and effectiveness of these therapeutics in the past decade. These therapies can also modulate therapeutic targets that cannot be sufficiently addressed using traditional drugs or antibodies. Among the nucleic acid-targeted therapeutics under development for CVD prevention are RNA-targeted approaches, including antisense oligonucleotides (ASO), small interfering RNAs (siRNA), and novel genome editing techniques. Genetic studies have identified potential therapeutic targets that are suggested to play a causative role in development and progression of CVD. RNA- and DNA-targeted therapeutics can be particularly well delivered to the liver, where atherogenic lipoproteins and angiotensinogen (AGT) are produced. Current targets in lipid metabolism include proprotein convertase subtilisin/kexin type 9 (PCSK9), apolipoprotein A (ApoA), apolipoprotein C3 (ApoC3), angiopoietin-like 3 (ANGPTL3). Several large-scale clinical development programs for nucleic acid-targeted therapies in cardiovascular prevention are under way, which may also be attractive from a therapy adherence point of view, given the long action of these therapeutics. In addition to genome editing, the concept of gene transfer is presently under assessment in preclinical and clinical investigations as a potential approach for addressing low-density lipoprotein receptor deficiency. Furthermore, ongoing research is exploring the use of RNA-targeted therapies to treat arterial hypertension by reducing hepatic angiotensinogen (AGT) production. This review summarizes the rapid translation of siRNA and ASO therapeutics as well as gene editing into clinical studies to treat dyslipidemia and arterial hypertension for CVD prevention. It also outlines potential innovative therapeutic options that are likely relevant to the future of cardiovascular medicine.

New insights into the therapeutic options to lower lipoprotein(a)

BACKGROUND

Elevated levels of lipoprotein(a) [Lp(a)] represent a risk factor for cardiovascular disease including aortic valve stenosis, myocardial infarction and stroke. While the patho-physiological mechanisms linking Lp(a) with atherosclerosis are not fully understood, from genetic studies that lower Lp(a) levels protect from CVD independently of other risk factors including lipids and lipoproteins. Hereby, Lp(a) has been considered an appealing pharmacological target.

RESULTS

However, approved lipid lowering therapies such as statins, ezetimibe or PCSK9 inhibitors have a neutral to modest effect on Lp(a) levels, thus prompting the development of new strategies selectively targeting Lp(a). These include antisense oligonucleotides and small interfering RNAs (siRNAs) directed towards apolipoprotein(a) [Apo(a)], which are in advanced phase of clinical development. More recently, additional approaches including inhibitors of Apo(a) and gene editing approaches via CRISPR-Cas9 technology entered early clinical development.

CONCLUSION

If the results from the cardiovascular outcome trials, designed to demonstrate whether the reduction of Lp(a) of more than 80% as observed with pelacarsen, olpasiran or lepodisiran translates into the decrease of cardiovascular mortality and major adverse cardiovascular events, will be positive, lowering Lp(a) will become a new additional target in the management of patients with elevated cardiovascular risk.

Therapeutic Gene Editing in Dyslipidemias

Dyslipidemia, characterized by abnormal lipid levels in the blood, significantly escalates the risk of atherosclerotic cardiovascular disease and requires effective treatment strategies. While existing therapies can be effective, long-term adherence is often challenging. There has been an interest in developing enduring and more efficient solutions. In this context, gene editing, particularly clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) technology, emerges as a groundbreaking approach, offering potential long-term control of dyslipidemia by directly modifying gene expression. This review delves into the mechanistic insights of various gene-editing tools. We comprehensively analyze various pre-clinical and clinical studies, evaluating the safety, efficacy, and therapeutic implications of gene editing in dyslipidemia management. Key genetic targets, such as low-density lipoprotein receptor (LDLR), proprotein convertase subtilisin/kexin type 9 (PCSK9), angiopoietin-like protein 3 (ANGPTL3), apolipoprotein C3 (APOC3), and lipoprotein (a) (Lp(a)), known for their pivotal roles in lipid metabolism, are scrutinized. The paper highlights the promising outcomes of gene editing in achieving sustained lipid homeostasis, discusses the challenges and ethical considerations in genome editing, and envisions the future of gene therapy in revolutionizing dyslipidemia treatment and cardiovascular risk reduction.

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.

High levels of lipoprotein(a) in transgenic mice exacerbate atherosclerosis and promote vulnerable plaque features in a sex-specific manner

BACKGROUND AND AIMS

Despite increased clinical interest in lipoprotein(a) (Lp(a)), many questions remain about the molecular mechanisms by which it contributes to atherosclerotic cardiovascular disease. Existing murine transgenic (Tg) Lp(a) models are limited by low plasma levels of Lp(a) and have not consistently shown a pro-atherosclerotic effect of Lp(a).

METHODS

We generated Tg mice expressing both human apolipoprotein(a) (apo(a)) and human apoB-100, with pathogenic levels of plasma Lp(a) (range 87-250 mg/dL). Female and male Lp(a) Tg mice (Tg(LPA+/0;APOB+/0)) and human apoB-100-only controls (Tg(APOB+/0)) (n = 10-13/group) were fed a high-fat, high-cholesterol diet for 12 weeks, with Ldlr knocked down using an antisense oligonucleotide. FPLC was used to characterize plasma lipoprotein profiles. Plaque area and necrotic core size were quantified and immunohistochemical assessment of lesions using a variety of cellular and protein markers was performed.

RESULTS

Male and female Tg(LPA+/0;APOB+/0) and Tg(APOB+/0) mice exhibited proatherogenic lipoprotein profiles with increased cholesterol-rich VLDL and LDL-sized particles and no difference in plasma total cholesterol between genotypes. Complex lesions developed in the aortic sinus of all mice. Plaque area (+22%), necrotic core size (+25%), and calcified area (+65%) were all significantly increased in female Tg(LPA+/0;APOB+/0) mice compared to female Tg(APOB+/0) mice. Immunohistochemistry of lesions demonstrated that apo(a) deposited in a similar pattern as apoB-100 in Tg(LPA+/0;APOB+/0) mice. Furthermore, female Tg(LPA+/0;APOB+/0) mice exhibited less organized collagen deposition as well as 42% higher staining for oxidized phospholipids (OxPL) compared to female Tg(APOB+/0) mice. Tg(LPA+/0;APOB+/0) mice had dramatically higher levels of plasma OxPL-apo(a) and OxPL-apoB compared to Tg(APOB+/0) mice, and female Tg(LPA+/0;APOB+/0) mice had higher plasma levels of the proinflammatory cytokine MCP-1 (+3.1-fold) compared to female Tg(APOB+/0) mice.

CONCLUSIONS

These data suggest a pro-inflammatory phenotype exhibited by female Tg mice expressing Lp(a) that appears to contribute to the development of more severe lesions with greater vulnerable features.

The Promise of PCSK9 and Lipoprotein(a) as Targets for Gene Silencing Therapies

PURPOSE

High plasma concentrations of LDL and lipoprotein(a) (Lp[a]) are independent and causal risk factors for atherosclerotic cardiovascular disease (ASCVD). There is an unmet therapeutic need for high-risk patients with elevated levels of LDL-C and/or Lp(a). Recent advances in the development of nucleic acids for gene silencing (ie, triantennary N-acetylgalactosamine conjugated antisense-oligonucleotides [ASOs] and small interfering RNA [siRNA]) targeting proprotein convertase subtilisin/kexin type 9 (PCSK9) and Lp(a) offer effective and sustainable therapies.

METHODS

Related articles in the English language were identified through a search for original and review articles in the PubMed database using the following key terms: cardiovascular disease, dyslipidemia, PCSK9 inhibitors, Lp(a), LDL-cholesterol, familial hypercholesterolemia, siRNA, and antisense oligonucleotide and clinical trials (either alone or in combination).

FINDINGS

Inclisiran, the most advanced siRNA-treatment targeting hepatic PCSK9, is well tolerated, producing a >30% reduction on LDL-C levels in randomized controlled trials. Pelacarsen is the most clinical advanced ASO, whereas olpasiran and SLN360 are the 2 siRNAs directed against the mRNA of the LPA gene. Evidence suggests that all Lp(a)-targeting agents are safe and well tolerated, with robust and sustained reduction in plasma Lp(a) concentration up to 70% to 90% in individuals with elevated Lp(a) levels.

IMPLICATIONS

Cumulative evidence from clinical trials supports the value of ASO and siRNA therapies targeting the synthesis of PCSK9 and Lp(a) for lowering LDL-C and Lp(a) in patients with established ASCVD or high risk of ASCVD. Further research is needed to examine whether gene silencing therapy could improve clinical outcomes in patients with elevated LDL and/or Lp(a) levels. Confirmation of the tolerability and cost-effectiveness of long-term inhibition of PCSK9 and Lp(a) with this approach is essential.

Lipoprotein(a) in patients with breast cancer after chemotherapy: exploring potential strategies for cardioprotection

Developments in neoadjuvant and adjuvant chemotherapy (CHT) have led to an increase in the number of breast cancer survivors. The determination of an appropriate follow-up for these patients is of increasing importance. Deaths due to cardiovascular disease (CVD) are an important part of mortality in patients with breast cancer.This review suggests that chemotherapeutic agents may influence lipoprotein(a) (Lp(a)) concentrations in breast cancer survivors after CHT based on many convincing evidence from epidemiologic and observational researches. Usually, the higher the Lp(a) concentration, the higher the median risk of developing CVD. However, more clinical trial results are needed in the future to provide clear evidence of a possible causal relationship. This review also discuss the existing and emerging therapies for lowering Lp(a) concentrations in the clinical setting. Hormone replacement therapy, statins, proprotein convertase subtilisin/kexin-type 9 (PCSK9) inhibitors, Antisense oligonucleotides, small interfering RNA, etc. may reduce circulating Lp(a) or decrease the incidence of CVD.

Recent advances in the management and implementation of care for familial hypercholesterolaemia

Familial hypercholesterolaemia (FH) is a common autosomal semi-dominant and highly penetrant disorder of the low-density lipoprotein (LDL) receptor pathway, characterised by lifelong elevated levels of low-density lipoprotein cholesterol (LDL-C) and increased risk of atherosclerotic cardiovascular disease (ASCVD). However, many patients with FH are not diagnosed and do not attain recommended LDL-C goals despite maximally tolerated doses of potent statin and ezetimibe. Over the past decade, several cholesterol-lowering therapies such as those targeting proprotein convertase subtilisin/kexin type 9 (PCSK9) or angiopoietin-like 3 (ANGPTL3) with monoclonal antibody or ribonucleic acid (RNA) approaches have been developed that promise to close the treatment gap. The availability of new therapies with complementary modes of action of lipid metabolism has enabled many patients with FH to attain guideline-recommended LDL-C goals. Emerging therapies for FH include liver-directed gene transfer of the LDLR, vaccines targeting key proteins involved in cholesterol metabolism, and CRISPR-based gene editing of PCSK9 and ANGPTL3, but further clinical trials are required. In this review, current and emerging treatment strategies for lowering LDL-C, and ASCVD risk-stratification, as well as implementation strategies for the care of patients with FH are reviewed.