Plozasiran, an RNA Interference Agent Targeting APOC3, for Mixed Hyperlipidemia.

BACKGROUND: Persons with mixed hyperlipidemia are at risk for atherosclerotic cardiovascular disease due to an elevated non-high-density lipoprotein (HDL) cholesterol level, which is driven by remnant cholesterol in triglyceride-rich lipoproteins. The metabolism and clearance of triglyceride-rich lipoproteins are down-regulated through apolipoprotein C3 (APOC3)-mediated inhibition of lipoprotein lipase. METHODS: We carried out a 48-week, phase 2b, double-blind, randomized, placebo-controlled trial evaluating the safety and efficacy of plozasiran, a hepatocyte-targeted APOC3 small interfering RNA, in patients with mixed hyperlipidemia (i.e., a triglyceride level of 150 to 499 mg per deciliter and either a low-density lipoprotein [LDL] cholesterol level of ≥70 mg per deciliter or a non-HDL cholesterol level of ≥100 mg per deciliter). The participants were assigned in a 3:1 ratio to receive plozasiran or placebo within each of four cohorts. In the first three cohorts, the participants received a subcutaneous injection of plozasiran (10 mg, 25 mg, or 50 mg) or placebo on day 1 and at week 12 (quarterly doses). In the fourth cohort, participants received 50 mg of plozasiran or placebo on day 1 and at week 24 (half-yearly dose). The data from the participants who received placebo were pooled. The primary end point was the percent change in fasting triglyceride level at week 24. RESULTS: A total of 353 participants underwent randomization. At week 24, significant reductions in the fasting triglyceride level were observed with plozasiran, with differences, as compared with placebo, in the least-squares mean percent change from baseline of -49.8 percentage points (95% confidence interval [CI], -59.0 to -40.6) with the 10-mg-quarterly dose, -56.0 percentage points (95% CI, -65.1 to -46.8) with the 25-mg-quarterly dose, -62.4 percentage points (95% CI, -71.5 to -53.2) with the 50-mg-quarterly dose, and -44.2 percentage points (95% CI, -53.4 to -35.0) with the 50-mg-half-yearly dose (P<0.001 for all comparisons). Worsening glycemic control was observed in 10% of the participants receiving placebo, 12% of those receiving the 10-mg-quarterly dose, 7% of those receiving the 25-mg-quarterly dose, 20% of those receiving the 50-mg-quarterly dose, and 21% of those receiving the 50-mg-half-yearly dose. CONCLUSIONS: In this randomized, controlled trial involving participants with mixed hyperlipidemia, plozasiran, as compared with placebo, significantly reduced triglyceride levels at 24 weeks. A clinical outcomes trial is warranted. (Funded by Arrowhead Pharmaceuticals; MUIR ClinicalTrials.gov number NCT04998201.).

ANGPTL3 and ApoC-III inhibitors for treating hypertriglyceridemia in context: horses for courses?

PURPOSE OF REVIEW: Hypertriglyceridemia (HTG) is an independent and casual risk factor for atherosclerotic cardiovascular disease (ASCVD). There is an unmet need for more effective treatments for patients with HTG. Angiopoietin-like protein 3 (ANGPTL3) and apolipoprotein C-III (apoC-III) are key regulators of triglyceride-rich lipoprotein (TRL) metabolism. We review recent clinical trials targeting ANGPTL3 and apoC-III with monoclonal antibody and nucleic acid therapies, including antisense oligonucleotides and small interfering RNA. RECENT FINDINGS: ANGPTL3 and apoC-III inhibitors are effective in lowering plasma triglycerides and TRLs, with possibly greater efficacy with the inhibition of apoC-III. By contrast to ANGPTL3 inhibition that has the advantage of greater lowering of plasma low-density lipoprotein (LDL)-cholesterol and apoB levels, apoC-III inhibition only has a modest or no effect in lowering plasma LDL-cholesterol and apoB concentrations. Therapeutic inhibition of ANGPTL3 and apoC-III can correct HTG possibly by reducing production and increasing catabolism of TRL particles, but this remains to be formally investigated in patients with HTG. SUMMARY: Novel agents targeting ANGPTL3 and apoC-III can correct HTG and potentially lower risk of ASCVD in patients with HTG. The long-term safety and cost-effectiveness of these agents await confirmation in ongoing and future studies.

[The role of apolipoprotein C3 in the regulation of nonalcoholic fatty liver disease, glucose and lipid metabolism, and islet ß cell function].

As a member of the apolipoprotein C (ApoC) family with a relatively high content, ApoC3 plays a major role in the regulation of triglyceride metabolism, and plays an important role in the occurrence and development of cardiovascular diseases, glucose and lipid metabolism disorders. Nonalcoholic fatty liver disease (NAFLD) refers to the accumulation of a large amount of fat in the liver in the absence of a history of chronic alcohol consumption or other damage to the liver. A large number of previous studies have shown that there is a correlation between the gene polymorphism and high expression of ApoC3 and NAFLD. In the context of hypertriglyceridemia (HTG), this article reviews the relationship between ApoC3 and NAFLD, glucose and lipid metabolism, and islet ß cell function, showing that ApoC3 can not only inhibit lipoprotein lipase (LPL) and hepatic lipase (HL) activity, delay the decomposition of triglyceride in plasma to maintain the body's energy metabolism during fasting, but also be significantly increased under insulin resistance, prompting the liver to secrete a large amount of very low-density lipoprotein (VLDL) to induce HTG. Therefore, targeting and inhibiting ApoC3 might become a new approach to treat HTG. Increasing evidence suggests that ApoC3 does not appear to be an independent "contributor" to NAFLD. Similarly, our previous studies have shown that ApoC3 is not an independent factor triggering islet ß cell dysfunction in ApoC3 transgenic mice, but in a state of excess nutrition, HTG triggered by ApoC3 high expression may exacerbate the effects of hyperglycemia and insulin resistance on islet ß cell function, and the underlying mechanism remains to be further discussed.

Volanesorsen and Triglyceride Levels in Familial Chylomicronemia Syndrome.

BACKGROUND: Familial chylomicronemia syndrome is a rare genetic disorder that is caused by loss of lipoprotein lipase activity and characterized by chylomicronemia and recurrent episodes of pancreatitis. There are no effective therapies. In an open-label study of three patients with this syndrome, antisense-mediated inhibition of hepatic APOC3 mRNA with volanesorsen led to decreased plasma apolipoprotein C-III and triglyceride levels. METHODS: We conducted a phase 3, double-blind, randomized 52-week trial to evaluate the safety and effectiveness of volanesorsen in 66 patients with familial chylomicronemia syndrome. Patients were randomly assigned, in a 1:1 ratio, to receive volanesorsen or placebo. The primary end point was the percentage change in fasting triglyceride levels from baseline to 3 months. RESULTS: Patients receiving volanesorsen had a decrease in mean plasma apolipoprotein C-III levels from baseline of 25.7 mg per deciliter, corresponding to an 84% decrease at 3 months, whereas patients receiving placebo had an increase in mean plasma apolipoprotein C-III levels from baseline of 1.9 mg per deciliter, corresponding to a 6.1% increase (P<0.001). Patients receiving volanesorsen had a 77% decrease in mean triglyceride levels, corresponding to a mean decrease of 1712 mg per deciliter (19.3 mmol per liter) (95% confidence interval [CI], 1330 to 2094 mg per deciliter [15.0 to 23.6 mmol per liter]), whereas patients receiving placebo had an 18% increase in mean triglyceride levels, corresponding to an increase of 92.0 mg per deciliter (1.0 mmol per liter) (95% CI, -301.0 to 486 mg per deciliter [-3.4 to 5.5 mmol per liter]) (P<0.001). At 3 months, 77% of the patients in the volanesorsen group, as compared with 10% of patients in the placebo group, had triglyceride levels of less than 750 mg per deciliter (8.5 mmol per liter). A total of 20 of 33 patients who received volanesorsen had injection-site reactions, whereas none of the patients who received placebo had such reactions. No patients in the placebo group had platelet counts below 100,000 per microliter, whereas 15 of 33 patients in the volanesorsen group had such levels, including 2 who had levels below 25,000 per microliter. No patient had platelet counts below 50,000 per microliter after enhanced platelet-monitoring began. CONCLUSIONS: Volanesorsen lowered triglyceride levels to less than 750 mg per deciliter in 77% of patients with familial chylomicronemia syndrome. Thrombocytopenia and injection-site reactions were common adverse events. (Funded by Ionis Pharmaceuticals and Akcea Therapeutics; APPROACH Clinical Trials.gov number, NCT02211209.).

Apolipoprotein C-III and cardiovascular diseases: when genetics meet molecular pathologies.

Cardiovascular diseases (CVD) have overtaken infectious diseases and are currently the world's top killer. A quite strong linkage between this type of ailments and elevated plasma levels of triglycerides (TG) has been always noticed. Notably, this risk factor is mired in deep confusion, since its role in atherosclerosis is uncertain. One of the explanations that aim to decipher this persistent enigma was provided by apolipoprotein C-III (apoC-III), a small protein historically recognized as an important regulator of TG metabolism. Preeminently, hundreds of studies have been carried out in order to explore the APOC3 genetic background, as well as to establish a correlation between its variants and dyslipidemia-related disorders, pointing to an earnest predictive power for future outcomes. Among several polymorphisms reported within the APOC3, the SstI site in its 3'-untranslated region (3'-UTR) was the most consistently and robustly associated with an increased CVD risk. As more genetic data supporting its importance in cardiovascular events aggregate, it was declared, correspondingly, that apoC-III exerts various atherogenic effects, either by intervening in the function and catabolism of many lipoproteins, or by inducing endothelial inflammation and smooth muscle cells (SMC) proliferation. This review was designed to shed the light on the structural and functional aspects of the APOC3 gene, the existing association between its SstI polymorphism and CVD, and the specific molecular mechanisms that underlie apoC-III pathological implications. In addition, the translation of all these gathered knowledges into preventive and therapeutic benefits will be detailed too.

The next generation of triglyceride-lowering drugs: will reducing apolipoprotein C-III or angiopoietin like protein 3 reduce cardiovascular disease?

PURPOSE OF REVIEW: Apolipoprotein C-III (ApoC-III) and angiopoietin like protein 3 (angptl3) have emerged as key regulators of triglyceride metabolism. Based on Mendelian randomisation studies, novel therapeutic strategies inhibiting these proteins using monoclonal antibodies or gene silencing techniques might reduce residual cardiovascular disease (CVD) risk in dyslipidemic patients. This article aims to review the role of apoC-III and angptl3 in triglyceride metabolism and combine early clinical evidence of CVD reducing potential of these new therapeutic targets. RECENT FINDINGS: Angptl3 inhibition by mAb or antisense therapy has recently completed phase I and II studies, respectively and demonstrate robust apolipoprotein B (apoB) lowering up to 46%. Volanesorsen is an antisense therapy approved for patients with extremely elevated plasma triglyceride levels in which it showed no consistent apoB reduction. However, the GalNAc-conjugated oligonucleotide showed moderate (up to ∼30%) apoB reduction in a phase 1/2a dose-finding study. SUMMARY: Angptl3 and apoC-III are novel targets in lipoprotein metabolism that reduce triglycerides when inhibited. The expected CVD risk reduction may be mediated through reduced triglyceride-rich lipoprotein particle number, reflected by apoB, rather than triglyceride reduction per se. Limited human evidence shows that apoC-III and angptl3 inhibition both potently lower triglycerides, but since angptl3 inhibition reduces apoB more robustly it may be expected to confer more favorable CVD risk reduction.

Efficacy and Safety of Volanesorsen (ISIS 304801): the Evidence from Phase 2 and 3 Clinical Trials.

PURPOSE OF REVIEW: To revise the clinical evidence supporting the use of volanesorsen as new lipid-lowering drug and to assess the efficacy and safety of volanesorsen (ISIS 304801) through a systematic review of the literature and a meta-analysis of the available phase 2 and phase 3 clinical studies. RECENT FINDINGS: The meta-analysis of three clinical studies comprising 11 arms (N = l 156 subjects, with 95 in the active-treated arm and 61 in the control one) shows that volanesorsen significantly affects plasma levels of triglycerides (TG) [MD = - 67.90%, 95%CI = - 85.32, - 50.48, P < 0.001], high-density lipoprotein cholesterol (HDL-C) [MD = 40.06%, 95%CI: 32.79, 47.34, P < 0.001], very-low-density lipoprotein cholesterol (VLDL-C) [MD = - 72.90%, 95%CI = - 82.73, - 63.07, P < 0.001], apolipoprotein B (Apo B) [MD = 8%, 95%CI = 2.17, 13.84, P = 0.007], Apo B-48 [MD = - 64.63, 95%CI = - 105.37, - 23.88, P = 0.002], ApoCIII [MD = - 74.83%, 95%CI = - 85.93, - 63.73, P < 0.001], and VLDL ApoCIII [MD = - 83.69%, 95%CI = - 94.08, - 73.29, P < 0.001], without significant impact on LDL-C [MD = 47.01%, 95%CI = - 1.31, 95.33, P = 0.057] levels. Treatment with volanesorsen was associated with an higher risk of injection site reaction (OR = 32.89, 95%CI = 7.97,135,74, P < 0.001) and with an increased risk of upper respiratory tract infections (OR = 10.58, 95%CI = 1.23, 90.93, P < 0.05) when compared to placebo. Volanesorsen has a relevant impact on plasma TG and related parameters without affecting LDL cholesterolemia and is associated with an acceptable safety profile.

Nucleic Acid-Based Therapies for Atherosclerosis.

PURPOSE OF REVIEW: Atherosclerosis is characterized by accumulation of lipids and chronic inflammation in medium size to large arteries. Recently, RNA-based antisense oligonucleotides (ASOs) and small interfering RNAs (siRNAs) are being developed, along with small molecule-based drugs and monoclonal antibodies, for the treatment of risk factors associated with atherosclerosis.. The purpose of this review is to describe nucleic acid-based therapeutics and introduce novel RNAs that might become future tools for treatment of atherosclerosis. RECENT FINDINGS: RNA-based inhibitors for PCSK9, Lp(a), ApoCIII, and ANGPTL3 have been successfully tested in phase II-III clinical trials. Moreover, multiple microRNA and long non-coding RNAs have been found to reduce atherogenesis in preclinical animal models. Clinical trials especially with ASOs and siRNAs directed to liver, targeting cholesterol and lipoprotein metabolism, have shown promising results. Additional research in larger patient cohorts is needed to fully evaluate the therapeutic potential of these new drugs.

N-acetyl galactosamine-conjugated antisense drug to APOC3 mRNA, triglycerides and atherogenic lipoprotein levels.

AIMS: Elevated apolipoprotein C-III (apoC-III) levels are associated with hypertriglyceridaemia and coronary heart disease. AKCEA-APOCIII-LRx is an N-acetyl galactosamine-conjugated antisense oligonucleotide targeted to the liver that selectively inhibits apoC-III protein synthesis. METHODS AND RESULTS: The safety, tolerability, and efficacy of AKCEA-APOCIII-LRx was assessed in a double-blind, placebo-controlled, dose-escalation Phase 1/2a study in healthy volunteers (ages 18-65) with triglyceride levels ≥90 or ≥200 mg/dL. Single-dose cohorts were treated with 10, 30, 60, 90, and 120 mg subcutaneously (sc) and multiple-dose cohorts were treated with 15 and 30 mg weekly sc for 6 weeks or 60 mg every 4 weeks sc for 3 months. In the single-dose cohorts treated with 10, 30, 60, 90, or 120 mg of AKCEA-APOCIII-LRx, median reductions of 0, -42%, -73%, -81%, and -92% in apoC-III, and -12%, -7%, -42%, -73%, and -77% in triglycerides were observed 14 days after dosing. In multiple-dose cohorts of 15 and 30 mg weekly and 60 mg every 4 weeks, median reductions of -66%, -84%, and -89% in apoC-III, and -59%, -73%, and -66% in triglycerides were observed 1 week after the last dose. Significant reductions in total cholesterol, apolipoprotein B, non-high-density lipoprotein cholesterol (HDL-C), very low-density lipoprotein cholesterol, and increases in HDL-C were also observed. AKCEA-APOCIII-LRx was well tolerated with one injection site reaction of mild erythema, and no flu-like reactions, platelet count reductions, liver, or renal safety signals. CONCLUSION: Treatment of hypertriglyceridaemic subjects with AKCEA-APOCIII-LRx results in a broad improvement in the atherogenic lipid profile with a favourable safety and tolerability profile. ClinicalTrials.gov Identifier: NCT02900027.

Metabolism and Disposition of Volanesorsen, a 2'-O-(2 methoxyethyl) Antisense Oligonucleotide, Across Species.

Volanesorsen (previously known as ISIS 304801) is a 20-nucleotide partially 2'-O-(2-methoxyethyl) (2'-MOE)-modified antisense oligonucleotide (ASO) gapmer, which was recently approved in the European Union as a novel, first-in-class treatment in the reduction of triglyceride levels in patients with familial chylomicronemia syndrome. We characterized the absorption, distribution, metabolism, and excretion characteristics of volanesorsen in mice, rats, monkeys, and humans, in either radiolabeled or nonradiolabeled studies. This also included the characterization of all of the observed ASO metabolite species excreted in urine. Volanesorsen is highly bound to plasma proteins that are similar in mice, monkeys, and humans. In all species, plasma concentrations declined in a multiphasic fashion, characterized by a relatively fast initial distribution phase and then a much slower terminal elimination phase following subcutaneous bolus administration. The plasma metabolite profiles of volanesorsen are similar across species, with volanesorsen as the major component. Various shortened oligonucleotide metabolites (5-19 nucleotides long) were identified in tissues in the multiple-dose mouse and monkey studies, but fewer in the [3H]-volanesorsen rat study, likely due to a lower accumulation of metabolites following a single dose in rats. In urine, all metabolites identified in tissues were observed, consistent with both endo- and exonuclease-mediated metabolism and urinary excretion being the major elimination pathway for volanesorsen and its metabolites. SIGNIFICANCE STATEMENT: We characterized the absorption, distribution, metabolism, and excretion (ADME) of volanesorsen, a partially 2'-MOE-modified antisense oligonucleotide, from mouse to man utilizing novel extraction and quantitation techniques in samples collected from preclinical toxicology studies, a 3H rat ADME study, and a phase 1 clinical trial.

Emerging Evidence that ApoC-III Inhibitors Provide Novel Options to Reduce the Residual CVD.

PURPOSE OF REVIEW: Apolipoprotein C-III (apoC-III) is known to inhibit lipoprotein lipase (LPL) and function as an important regulator of triglyceride metabolism. In addition, apoC-III has also more recently been identified as an important risk factor for cardiovascular disease. This review summarizes the mechanisms by which apoC-III induces hypertriglyceridemia and promotes atherogenesis, as well as the findings from recent clinical trials using novel strategies for lowering apoC-III. RECENT FINDINGS: Genetic studies have identified subjects with heterozygote loss-of-function (LOF) mutations in APOC3, the gene coding for apoC-III. Clinical characterization of these individuals shows that the LOF variants associate with a low-risk lipoprotein profile, in particular reduced plasma triglycerides. Recent results also show that complete deficiency of apoC-III is not a lethal mutation and is associated with very rapid lipolysis of plasma triglyceride-rich lipoproteins (TRL). Ongoing trials based on emerging gene-silencing technologies show that intervention markedly lowers apoC-III levels and, consequently, plasma triglyceride. Unexpectedly, the evidence points to apoC-III not only inhibiting LPL activity but also suppressing removal of TRLs by LPL-independent pathways. Available data clearly show that apoC-III is an important cardiovascular risk factor and that lifelong deficiency of apoC-III is cardioprotective. Novel therapies have been developed, and results from recent clinical trials indicate that effective reduction of plasma triglycerides by inhibition of apoC-III might be a promising strategy in management of severe hypertriglyceridemia and, more generally, a novel approach to CHD prevention in those with elevated plasma triglyceride.

Apolipoprotein C-III in triglyceride-rich lipoprotein metabolism.

PURPOSE OF REVIEW: Apolipoprotein (apo) C-III is a key player in triglyceride-rich lipoprotein metabolism and strongly associated with elevated plasma triglyceride levels. Several new studies added important insights on apoC-III and its physiological function confirming its promise as a valid therapeutic target. RECENT FINDINGS: APOC3 is expressed in liver and intestine and regulates triglyceride-rich lipoprotein (TRL) catabolism and anabolism. The transcriptional regulation in both organs requires different regulatory elements. Clinical and preclinical studies established that apoC-III raises plasma triglyceride levels predominantly by inhibiting hepatic TRL clearance. Mechanistic insights into missense variants indicate accelerated renal clearance of apoC-III variants resulting in enhanced TRL catabolism. In contrast, an APOC3 gain-of-function variant enhances de novo lipogenesis and hepatic TRL production. Multiple studies confirmed the correlation between increased apoC-III levels and cardiovascular disease. This has opened up new therapeutic avenues allowing targeting of specific apoC-III properties in triglyceride metabolism. SUMMARY: Novel in vivo models and APOC3 missense variants revealed unique mechanisms by which apoC-III inhibits TRL catabolism. Clinical trials with Volanesorsen, an APOC3 antisense oligonucleotide, report very promising lipid-lowering outcomes. However, future studies will need to address if acute apoC-III lowering will have the same clinical benefits as a life-long reduction.

Antisense Inhibition of Apolipoprotein C-III in Patients with Hypertriglyceridemia.

BACKGROUND: Apolipoprotein C-III (APOC3) is a key regulator of plasma triglyceride levels. Elevated triglyceride levels are associated with a risk of adverse cardiovascular events and pancreatitis. ISIS 304801 is a second-generation antisense inhibitor of APOC3 synthesis. METHODS: We conducted a randomized, double-blind, placebo-controlled, dose-ranging, phase 2 study to evaluate ISIS 304801 in untreated patients with fasting triglyceride levels between 350 mg per deciliter (4.0 mmol per liter) and 2000 mg per deciliter (22.6 mmol per liter) (ISIS 304801 monotherapy cohort), as well as in patients receiving stable fibrate therapy who had fasting triglyceride levels between 225 mg per deciliter (2.5 mmol per liter) and 2000 mg per deciliter (ISIS 304801-fibrate cohort). Eligible patients were randomly assigned to receive either ISIS 304801, at doses ranging from 100 to 300 mg, or placebo, once weekly for 13 weeks. The primary outcome was the percentage change in APOC3 level from baseline. RESULTS: A total of 57 patients were treated in the ISIS 304801 monotherapy cohort (41 received active agent, and 16 received placebo), and 28 patients were treated in the ISIS 304801-fibrate cohort (20 received active agent, and 8 received placebo). The mean (±SD) baseline triglyceride levels in the two cohorts were 581±291 mg per deciliter (6.6±3.3 mmol per liter) and 376±188 mg per deciliter (4.2±2.1 mmol per liter), respectively. Treatment with ISIS 304801 resulted in dose-dependent and prolonged decreases in plasma APOC3 levels when the drug was administered as a single agent (decreases of 40.0±32.0% in the 100-mg group, 63.8±22.3% in the 200-mg group, and 79.6±9.3% in the 300-mg group, vs. an increase of 4.2±41.7% in the placebo group) and when it was administered as an add-on to fibrates (decreases of 60.2±12.5% in the 200-mg group and 70.9±13.0% in the 300-mg group, vs. a decrease of 2.2±25.2% in the placebo group). Concordant reductions of 31.3 to 70.9% were observed in triglyceride levels. No safety concerns were identified in this short-term study. CONCLUSIONS: We found that treatment with ISIS 304801 was associated with significant lowering of triglyceride levels, among patients with a broad range of baseline levels, through selective antisense inhibition of APOC3 synthesis. (Funded by Isis Pharmaceuticals; ClinicalTrials.gov number, NCT01529424.).

Targeting APOC3 in the familial chylomicronemia syndrome.

The familial chylomicronemia syndrome is a genetic disorder characterized by severe hypertriglyceridemia and recurrent pancreatitis due to a deficiency in lipoprotein lipase (LPL). Currently, there are no effective therapies except for extreme restriction in the consumption of dietary fat. Apolipoprotein C-III (APOC3) is known to inhibit LPL, although there is also evidence that APOC3 increases the level of plasma triglycerides through an LPL-independent mechanism. We administered an inhibitor of APOC3 messenger RNA (mRNA), called ISIS 304801, to treat three patients with the familial chylomicronemia syndrome and triglyceride levels ranging from 1406 to 2083 mg per deciliter (15.9 to 23.5 mmol per liter). After 13 weeks of study-drug administration, plasma APOC3 levels were reduced by 71 to 90% and triglyceride levels by 56 to 86%. During the study, all patients had a triglyceride level of less than 500 mg per deciliter (5.7 mmol per liter) with treatment. These data support the role of APOC3 as a key regulator of LPL-independent pathways of triglyceride metabolism.

ApoCIII as a Cardiovascular Risk Factor and Modulation by the Novel Lipid-Lowering Agent Volanesorsen.

PURPOSE OF REVIEW: Apolipoprotein CIII (ApoCIII) is now recognized as a key regulator in severe hypertriglyceridemia, chylomicronemia, and conditions of triglyceride-rich lipoprotein (TRL) remnant excess due to its inhibition of lipoprotein lipase (LPL) and hepatic lipase, leading to decreased hepatic reuptake of TRLs, as well as enhanced synthesis and secretion of VLDL from the liver. ApoCIII gain-of-function mutations are associated with atherosclerosis and coronary heart disease (CHD), and contribute to the development of cardiometabolic syndrome, hypertriglyceridemia, and type 2 diabetes mellitus. Conversely, loss-of-function mutations in ApoCIII are associated with lower levels of plasma triglycerides (TG), attenuation of vascular inflammatory processes such as monocyte adhesion and endothelial dysfunction, and potentially, a reduction in the incidence and progression of atherosclerosis and cardioprotection. RECENT FINDINGS: Evidence is now emerging that volanesorsen, a second-generation antisense oligonucleotide drug targeting ApoCIII messenger RNA resulting in decreases in TG in patients with familial chylomicronemia syndrome, severe hypertriglyceridemia, and metabolic dyslipidemia with type 2 diabetes giving support to the hypothesis that ApoCIII is a powerful inhibitor of LPL, and when reduced, endogenous clearance of TRLs can result in substantial reductions in TG levels. Discovery of the ApoCIII inhibitor volanesorsen opens a new era of lipid-lowering drugs for reduction in TG and potentially for reduction in LDL-C. Herein, this review will provide an update on the pathophysiology of ApoCIII-linked atherosclerosis and the development of the first drug to target ApoCIII, volanesorsen, as a promising lipid-lowering agent.

Antisense oligonucleotide inhibition of apolipoprotein C-III reduces plasma triglycerides in rodents, nonhuman primates, and humans.

RATIONALE: Elevated plasma triglyceride levels have been recognized as a risk factor for the development of coronary heart disease. Apolipoprotein C-III (apoC-III) represents both an independent risk factor and a key regulatory factor of plasma triglyceride concentrations. Furthermore, elevated apoC-III levels have been associated with metabolic syndrome and type 2 diabetes mellitus. To date, no selective apoC-III therapeutic agent has been evaluated in the clinic. OBJECTIVE: To test the hypothesis that selective inhibition of apoC-III with antisense drugs in preclinical models and in healthy volunteers would reduce plasma apoC-III and triglyceride levels. METHODS AND RESULTS: Rodent- and human-specific second-generation antisense oligonucleotides were identified and evaluated in preclinical models, including rats, mice, human apoC-III transgenic mice, and nonhuman primates. We demonstrated the selective reduction of both apoC-III and triglyceride in all preclinical pharmacological evaluations. We also showed that inhibition of apoC-III was well tolerated and not associated with increased liver triglyceride deposition or hepatotoxicity. A double-blind, placebo-controlled, phase I clinical study was performed in healthy subjects. Administration of the human apoC-III antisense drug resulted in dose-dependent reductions in plasma apoC-III, concomitant lowering of triglyceride levels, and produced no clinically meaningful signals in the safety evaluations. CONCLUSIONS: Antisense inhibition of apoC-III in preclinical models and in a phase I clinical trial with healthy subjects produced potent, selective reductions in plasma apoC-III and triglyceride, 2 known risk factors for cardiovascular disease. This compelling pharmacological profile supports further clinical investigations in hypertriglyceridemic subjects.

Inhibition of ApoCIII: the next PCSK9?

PURPOSE OF REVIEW: Recent large Mendelian randomization studies associate loss-of-function mutations in apolipoprotein CIII (APOCIII) with low levels of triglycerides and decreased incidence of cardiovascular disease. With ample in-vitro and in-vivo evidence for a role of apoCIII in lipoprotein lipase-mediated triglyceride clearance and remnant removal, it is, thus, an attractive target for the treatment of hypertriglyceridemia and the prevention of cardiovascular disease. This review evaluates the current position of apoCIII in clinical practice and provides a glimpse into the future in terms of treatment options. RECENT FINDINGS: Two large Mendelian randomization studies have shown three identical loss-of-function mutations in APOCIII to be linked to favorable lipid profiles and lower incidence of coronary artery disease. A second-generation antisense oligonucleotide, which selectively inhibits apoCIII, was able to decrease serum apoCIII and triglyceride levels in rodents, nonhuman primates and humans. SUMMARY: The central role of apoCIII in hypertriglyceridemia and cardiovascular disease was further cemented by recent findings and promising intervention data that showed the possibility of using antisense therapy to lower apoCIII and triglyceride levels. Currently, planned phase 3 trials should provide answers in regards to long-term efficacy and safety of this novel therapy.

Statins suppress apolipoprotein CIII-induced vascular endothelial cell activation and monocyte adhesion.

AIMS: Activation of vascular endothelial cells (ECs) contributes importantly to inflammation and atherogenesis. We previously reported that apolipoprotein CIII (apoCIII), found abundantly on circulating triglyceride-rich lipoproteins, enhances adhesion of human monocytes to ECs in vitro. Statins may exert lipid-independent anti-inflammatory effects. The present study examined whether statins suppress apoCIII-induced EC activation in vitro and in vivo. METHODS AND RESULTS: Physiologically relevant concentrations of purified human apoCIII enhanced attachment of the monocyte-like cell line THP-1 to human saphenous vein ECs (HSVECs) or human coronary artery ECs (HCAECs) under both static and laminar shear stress conditions. This process mainly depends on vascular cell adhesion molecule-1 (VCAM-1), as a blocking VCAM-1 antibody abolished apoCIII-induced monocyte adhesion. ApoCIII significantly increased VCAM-1 expression in HSVECs and HCAECs. Pre-treatment with statins suppressed apoCIII-induced VCAM-1 expression and monocyte adhesion, with two lipophilic statins (pitavastatin and atorvastatin) exhibiting inhibitory effects at lower concentration than those of hydrophilic pravastatin. Nuclear factor κB (NF-κB) mediated apoCIII-induced VCAM-1 expression, as demonstrated via loss-of-function experiments, and pitavastatin treatment suppressed NF-κB activation. Furthermore, in the aorta of hypercholesterolaemic Ldlr(-/-) mice, pitavastatin administration in vivo suppressed VCAM-1 mRNA and protein, induced by apoCIII bolus injection. Similarly, in a subcutaneous dorsal air pouch mouse model of leucocyte recruitment, apoCIII injection induced F4/80+ monocyte and macrophage accumulation, whereas pitavastatin administration reduced this effect. CONCLUSIONS: These findings further establish the direct role of apoCIII in atherogenesis and suggest that anti-inflammatory effects of statins could improve vascular disease in the population with elevated plasma apoCIII.

Etiology and emerging treatments for familial chylomicronemia syndrome.

INTRODUCTION: Familial chylomicronemia syndrome (FCS) is a rare autosomal recessive condition. Effective treatment is important as patients are at risk for severe and potentially fatal acute pancreatitis. We review recent developments in pharmacologic treatment for FCS, namely biological inhibitors of apolipoprotein (apo) C-III and angiopoietin-like protein 3 (ANGPTL3). AREAS COVERED: FCS follows a biallelic inheritance pattern in which an individual inherits two pathogenic loss-of-function alleles of one of the five causal genes - LPL (in 60-80% of patients), GPIHBP1, APOA5, APOC2, and LMF1 - leading to the absence of lipolytic activity. Patients present from childhood with severely elevated triglyceride (TG) levels >10 mmol/L. Most patients with severe hypertriglyceridemia do not have FCS. A strict low-fat diet is the current first-line treatment, and existing lipid-lowering therapies are minimally effective in FCS. Apo C-III inhibitors are emerging TG-lowering therapies shown to be efficacious and safe in clinical trials. ANGPTL3 inhibitors, another class of emerging TG-lowering therapies, have been found to require at least partial lipoprotein lipase activity to lower plasma TG in clinical trials. ANGPTL3 inhibitors reduce plasma TG in patients with multifactorial chylomicronemia but not in patients with FCS who completely lack lipoprotein lipase activity. EXPERT OPINION: Apo C-III inhibitors currently in development are promising treatments for FCS.