Innovative Lipid-Lowering Strategies: RNA-Based, Small Molecule, and Protein-Based Therapies

Statins

Statins inhibit the rate-limiting enzyme HMG-CoA reductase, reducing hepatic cholesterol synthesis and upregulating low-density lipoprotein (LDL) receptor expression. Statins revolutionized lipid-lowering therapy and remain the cornerstone of treatment in lipid-lowering treatment with demonstrating proportional reductions in cardiovascular risk per mmol/L LDL-C lowered. Clinical outcome trials including Scandinavian Simvastatin Survival Study (4S) [21], Heart Protection Study (HPS) of cholesterol lowering with simvastatin [22], Treating to New Targets (TNT) [23], Justification for the Use of Statins in Prevention: an Intervention Trial Evaluating Rosuvastatin (JUPITER) [24] etc. established statins as cornerstone therapy, showing 20% to 40% reductions in major adverse cardiovascular events (MACE). Benefits are dose-dependent, with high-intensity statins achieving >50% LDL-C reduction from the baseline level (Fig. 1A). Despite this success, a considerable proportion of patients remain at elevated risk due to statin intolerance, insufficient LDL-C lowering, elevated TG, or elevated Lp(a). This gap has driven development of additional small-molecule lipid-lowering therapies with complementary mechanisms of action. Table 1 summarizes the previous pivotal clinical trials of small molecules inhibitors of classical and new drugs in lipid-lowering treatment.

Fig. 1.

(A) Approximate percentage reduction in low-density lipoprotein cholesterol (LDL-C) achieved with representative oral agents, including high-intensity statins, ezetimibe, bempedoic acid (alone or combined with ezetimibe), obicetrapib (a cholesteryl ester transfer protein [CETP] inhibitor), AZD0780 (an oral proprotein convertase subtilisin/kexin type 9 [PCSK9] inhibitor), and lomitapide (a microsomal triglyceride transfer protein [MTP] inhibitor). (B) Stepwise LDL-C reductions achieved with sequential oral combination therapy demonstrate additive lipid-lowering effects, with triple or quadruple regimens (statin+ezetimibe+bempedoic acid±obicetrapib) producing >80% reductions comparable to those observed with injectable PCSK9 monoclonal antibodies.

Table 1.

Summary of Pivotal Trials in Small-Molecule Inhibitors of Lipid-Lowering Therapies

Ezetimibe

Ezetimibe blocks intestinal cholesterol absorption via Niemann–Pick C1-like 1 (NPC1L1) inhibition. The IMProved Reduction of Outcomes: Vytorin Efficacy International Trial (IMPROVE-IT) trial demonstrated that adding ezetimibe to simvastatin after acute coronary syndrome produced incremental LDL-C reduction of approximately 24% and significant approximately 6% reduction in MACE, validating non-statin small molecules as effective add-on therapies (Fig. 1) [25]. Beyond IMPROVE-IT [25], contemporary lipid guidelines position ezetimibe as the first-line nonstatin add-on to maximally tolerated statin therapy when LDL-C remains above target in patients with ASCVD, and as a reasonable option in statin intolerance (either as monotherapy or in combination with other agents). the European guidelines endorse early statin–ezetimibe combination to achieve risk-based LDL-C targets more reliably, and in very-high-risk patients (including familial hypercholesterolemia [FH]) recommend adding ezetimibe before moving to PCSK9 inhibition if goals are not met on maximal statin therapy. Response heterogeneity to ezetimibe appears partly genetically determined. Variants in NPC1L1 have been associated with greater LDL-C reductions and ‘good-responder’ phenotypes to ezetimibe, suggesting that enterocyte cholesterol-transport biology modulates pharmacodynamic effect.

Fibrates

Fibrates exert their lipid-modifying effects by activating peroxisome proliferator-activated receptor alpha (PPARα), a nuclear receptor that upregulates genes involved in fatty acid oxidation and lipoprotein lipase (LPL) activity, leading to reductions in plasma TG and modest increases in high-density lipoprotein cholesterol (HDL-C). Early outcome studies, including the Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) [26] (fenofibrate in type 2 diabetes) and Action to Control Cardiovascular Risk in Diabetes (ACCORD)-Lipid (fenofibrate plus simvastatin in type 2 diabetes) trials, reported neutral primary composite outcomes overall, but consistent post hoc signals suggested benefit in subgroups with atherogenic dyslipidemia, particularly patients with elevated TG (≥200 mg/dL) and reduced HDL-C [27]. These observations underpin ongoing debate regarding selective use of fibrates in patients with residual dyslipidemia despite statin therapy.

Recently, attention has shifted to next-generation selective PPARα modulators (SPPARMα) such as pemafibrate, which was designed to improve efficacy and safety relative to traditional fibrates. Pemafibrate achieves potent reductions in TG (approximately 45%–50%) and increases in HDL-C with a lower incidence of renal and hepatic adverse events compared to fenofibrate. In early Japanese and multinational phase II/III studies, pemafibrate demonstrated marked improvements in TG, remnant lipoprotein cholesterol, and apolipoprotein C-III (apoC-III), supporting its role in reducing atherogenic remnant particles [28]. However, the large Pemafibrate to Reduce Cardiovascular Outcomes by Reducing TG in Patients with Diabetes (PROMINENT) trial, which enrolled over 10,000 patients with type 2 diabetes, elevated TG, and low HDL-C on statin therapy, found that pemafibrate significantly reduced TG (approximately 26% reduction) but did not improve cardiovascular outcomes [29]. This outcome underscores a recurring theme in fibrate research: robust biochemical efficacy in TG lowering does not necessarily translate into reductions in ASCVD events when tested in broad populations. Nevertheless, fibrates continue to play an important clinical role in severe hypertriglyceridemia (TG ≥500 to 1,000 mg/dL), where the immediate therapeutic goal is prevention of acute pancreatitis rather than ASCVD event reduction.

Niacin

Niacin lowers hepatic very-low-density lipoprotein (VLDL) production and raises HDL-C, but Atherothrombosis Intervention in Metabolic Syndrome with Low HDL/High TG: Impact on Global Health Outcomes (AIM-HIGH) [30] and Heart Protection Study 2–Treatment of HDL to Reduce the Incidence of Vascular Events (HPS2-THRIVE) [31] trials showed no incremental benefit when added to statins and highlighted increased adverse effects, including flushing, infection risk, and glucose intolerance. As such, niacin is now rarely used.

Omega-3 fatty acids

Eicosapentaenoic acid (EPA) is the only omega-3 agent with proven cardiovascular benefit. In Reduction of Cardiovascular Events with Icosapent Ethyl–Intervention Trial (REDUCE-IT), 4 g/day of purified EPA in statin-treated patients with elevated TG reduced major cardiovascular events by 25%, an effect greater than expected from TG lowering alone [32]. Substudies suggest anti-inflammatory, antithrombotic, and plaque-stabilizing mechanisms may contribute. By contrast, other omega-3 formulations have been neutral. The Long-Term Outcomes Study to Assess Statin Residual Risk with Epanova in High Cardiovascular Risk Patients with Hypertriglyceridemia (STRENGTH) trial (EPA/docosahexaenoic acid [DHA] mixture, 4 g/day) was stopped early for futility [33], and OMega-3 fatty acids in Elderly patients with Myocardial Infarction (OMEMI), which enrolled elderly post-myocardial infarction patients, showed no benefit. Differences in biologic effects of EPA vs. DHA—with DHA sometimes raising LDL-C—likely explain the discrepancy. Placebo choice (mineral oil in REDUCE-IT vs. corn oil in STRENGTH) may also have influenced results but does not account for consistent EPA-specific efficacy. Thus, current guidelines recommend high-dose purified EPA for statin-treated patients with persistent hypertriglyceridemia, while combination EPA/DHA products or low-dose fish oil cannot be advised for ASCVD prevention.

Bempedoic acid

Bempedoic acid is a liver-activated denosine triphosphate-citrate lyase (ACLY) inhibitor that lowers LDL-C by approximately 18% as monotherapy and around 30%–35% when co-formulated with ezetimibe (Fig. 1). The Cholesterol Lowering via Bempedoic Acid, an ACLY-inhibiting Regimen (CLEAR) Outcomes trial (2023) demonstrated a 13% reduction in MACE among more than 13,000 statin-intolerant patients, with significant decreases in myocardial infarction and revascularization [34]. High-sensitivity C-reactive protein levels also decreased, indicating possible anti-inflammatory effects. Current European guidelines, including the 2025 European Society of Cardiology/European Atherosclerosis Society Focused Update, placed bempedoic acid within the stepwise LDL-C lowering algorithm, recommending its use in patients who cannot take statins or who do not achieve LDL-C goals on maximally tolerated statin with or without ezetimibe. Guidance documents also highlight practical considerations such as caution in patients with a history of gout, although this is not a strict contraindication. In 2024, the European Commission expanded the indication for bempedoic acid, both alone and in fixed-dose combination with ezetimibe, to include not only the treatment of hypercholesterolemia but also the reduction of cardiovascular risk in high-risk adults. Clinically, this defines several roles for bempedoic acid: as the first oral add-on after ezetimibe when additional LDL-C lowering is needed and statin up-titration is not possible; as an effective therapy for statin-intolerant patients either as monotherapy at 180 mg daily or in the fixed-dose bempedoic acid/ezetimibe (180/10 mg) combination achieving about 30%–35% additional LDL-C lowering; and as a bridge for patients awaiting or not eligible for injectable therapies.

CETP inhibitors

CETP inhibition both raises HDL-C and lowers LDL-C by reducing the transfer of cholesteryl esters from HDL to apolipoprotein B (apoB)-containing lipoproteins. Despite strong mechanistic rationale, the first wave of CETP inhibitors yielded disappointing results. Torcetrapib was withdrawn due to excess mortality and off-target adverse effects, dalcetrapib [35] showed no efficacy in reducing cardiovascular outcomes, and evacetrapib [36] lowered LDL-C and raised HDL-C substantially but failed to demonstrate clinical benefit, leading to early termination. These failures cast doubt on CETP as a viable therapeutic target. However, obicetrapib, a next-generation CETP inhibitor, has renewed interest in this pathway. Phase II trials demonstrated dose-dependent reductions in LDL-C of up to 51% and large increases in HDL-C with a favorable safety profile compared to earlier CETP inhibitors. Importantly, obicetrapib has shown additive efficacy when combined with statins and ezetimibe, offering potential for oral triple therapy achieving LDL-C reductions comparable to PCSK9-targeted biologics. The ongoing Phase III Obicetrapib in Patients with ASCVD on Maximum Tolerated Lipid-Modifying Therapy (BROADWAY) [37], Obicetrapib in Statin-treated Patients with Heterozygous FH (HeFH) (BROOKLYN) [38], and Obicetrapib in Patients with Cardiovascular Disease on Statin Therapy with or without Ezetimibe (PREVAIL) trials are designed to determine whether these lipid improvements will translate into reductions in major cardiovascular events. If successful, obicetrapib may re-establish CETP inhibition as a clinically valuable, fully oral approach to achieving aggressive LDL-C targets in high-risk patients.

Oral PCSK9 inhibitors

Oral PCSK9 inhibitors, such as AZD0780, represent a transformative development. The Oral PCSK9 Inhibitor Trial (AZD0780) (PURSUIT) Phase IIb trial showed dose-dependent LDL-C reductions of approximately 50% at 12 weeks with good tolerability [39]. If phase III trials confirm reductions in cardiovascular outcomes similar to mAbs, oral PCSK9 inhibitors may expand accessibility to a broader patient population.

Lp(a) inhibitors

Muvalaplin, an oral small molecule, prevents the assembly of Lp(a) by disrupting apo(a)-apoB interactions. The Muvalaplin Phase II Trial in High Lp(a) (KRAKEN) phase II trial demonstrated up to 86% reductions in Lp(a), with secondary reductions in apoB and LDL-C. Given elevated Lp(a) as an independent risk factor, muvalaplin holds potential for filling a major unmet clinical need.

BET inhibitors

Apabetalone, an inhibitor of bromodomain and extra-terminal (BET) proteins, increases apoA-I expression and HDL-C. Although the Effect of Apabetalone on Major Adverse Cardiovascular Events in Patients with T2DM and Recent ACS (BETonMACE) trial did not meet its primary endpoint, reductions in heart failure hospitalizations suggest selective utility in patients with combined ASCVD and heart failure risk.

MTP inhibitors

Lomitapide inhibits microsomal TG transfer protein (MTP), preventing assembly of apoB-containing lipoproteins. Approved for homozygous familial hypercholesterolemia (HoFH), lomitapide reduces LDL-C by up to 50% independent of LDL receptor activity, though gastrointestinal intolerance and hepatic steatosis limit its use [40].

Treatment sequencing and clinical algorithms

For secondary prevention, high-intensity statins remain first-line. Ezetimibe is the preferred first add-on for residual LDL-C elevation, followed by bempedoic acid. Bempedoic acid is also strong consideration for statin-intolerant individuals. Oral PCSK9 inhibitors, once approved, are expected to play a significant role considering drug compliance. For patients with FH or extreme LDL-C elevation, lomitapide¹⁸ may be considered in specialized centers. Combination regimens allow additive LDL-C lowering often exceeding 70% to 80%, a level that may substantially reduce residual cardiovascular risk (Fig. 1B).

Safety considerations

Statins are generally well tolerated but associated with myalgias and a small increase in diabetes risk. Ezetimibe and icosapent ethyl exhibit favorable safety profiles. Bempedoic acid can increase uric acid and creatinine but has otherwise been well tolerated. Lomitapide use is constrained by steatohepatitis and gastrointestinal side effects. Ongoing long-term safety data for obicetrapib, oral PCSK9 inhibitors, and muvalaplin will inform their clinical implementation.

Developmental process, mechanism, and clinical trials of PCSK9 mAb

PCSK9 binds to low-density lipoprotein receptors (LDL-R) on hepatocytes and promotes their lysosomal degradation, thereby reducing the hepatic clearance of circulating LDL-C. Inhibitory mAbs targeting PCSK9, such as evolocumab and alirocumab, inhibit this interaction, enhancing LDL-R recycling and facilitating LDL-C uptake by hepatocytes, ultimately leading to substantial reductions in plasma LDL-C levels [41]. The development of PCSK9 inhibitors was strongly supported by genetic evidence. Individuals with loss-of-function (LOF) mutations in PCSK9 exhibit significantly lower LDL-C levels and a markedly reduced risk of coronary artery disease (CAD) [42]. Mendelian randomization studies have confirmed the causal relationship between PCSK9 activity, LDL-C levels, and ASCVD, providing a robust genetic rationale for therapeutic PCSK9 inhibition [43,44].

Initial animal studies demonstrated that inhibition of PCSK9 could lead to dramatic reductions in LDL-C by enhancing LDL receptor availability on hepatocyte surfaces [45]. These preclinical findings paved the way for early-phase human trials. In phase 1 and 2 studies, evolocumab and alirocumab showed dose-dependent LDL-C reductions exceeding 60% in patients with hypercholesterolemia, including those on statin therapy [46,47]. The safety profile was favorable, with no significant immunogenicity observed during short-term follow-up.

Immunogenicity and the case of bococizumab

Not all PCSK9 mAbs were successful. Bococizumab, a humanized mAb, was developed to inhibit PCSK9 but ultimately failed in late-phase trials. In the Studies of PCSK9 Inhibition and the Reduction of Vascular Events (SPIRE-1 and SPIRE-2) trials, bococizumab initially achieved substantial LDL-C lowering, but this effect attenuated over time. The underlying cause was the formation of anti-drug antibodies (ADA), including neutralizing antibodies, which diminished the drug’s efficacy [48]. The immunogenicity of bococizumab is largely attributed to its humanized structure, where murine variable regions are grafted onto human constant regions. This partial murine origin can trigger an immune response in humans, leading to ADA formation and loss of therapeutic effect (Fig. 2A) [49]. In contrast, fully human antibodies such as evolocumab and alirocumab are produced using transgenic mouse platforms that generate entirely human immunoglobulin sequences. These antibodies are then expressed and refined using phage display techniques or Chinese Hamster Ovary cell systems, resulting in products with minimal immunogenic potential as summarized in Fig. 2B [50]. This structural difference translates into clinical outcomes. Evolocumab and alirocumab have demonstrated durable LDL-C lowering without attenuation over long-term follow-up. In the open-label extension of the Further Cardiovascular Outcomes Research With PCSK9 Inhibition in Subjects With Elevated Risk (FOURIER) trial, evolocumab showed progressive cardiovascular event reduction over time, suggesting no significant interference from ADA formation [51]. This case highlights the critical role of antibody design in determining therapeutic longevity.

Fig. 2.

Structural differences and immunogenicity of monoclonal antibodies against proprotein convertase subtilisin/kexin type 9 (PCSK9). (A) Humanized antibody manufacturing: The variable region of a mouse antibody is combined with the Fc region of a human antibody to generate a humanized monoclonal antibody (e.g., bococizumab). Partial murine sequences can elicit anti-drug and neutralizing antibodies, leading to attenuation of low-density lipoprotein cholesterol (LDL-C)–lowering efficacy. (B) Fully human antibody manufacturing: Fully human monoclonal antibodies (e.g., evolocumab and alirocumab) are generated using transgenic mouse platforms, and the antibody gene is inserted into Chinese hamster ovary (CHO) cells for large-scale production. These antibodies exhibit durable LDL-C lowering with minimal immunogenicity.

Clinical outcomes trials

The clinical efficacy of PCSK9 inhibitors was conclusively established through two landmark cardiovascular outcomes trials. The FOURIER trial evaluated evolocumab in 27,564 patients with ASCVD on maximally tolerated statin therapy. Over a median follow-up of 2.2 years, evolocumab reduced the risk of MACE, including myocardial infarction, stroke, and coronary revascularization, by 15%, with LDL-C reductions exceeding 59% from baseline [52]. In the long-term open-label extension of the FOURIER trial, patients originally assigned to evolocumab continued therapy for up to 5 years [51]. The relative risk reduction increased from 15% at 2.2 years to 23% at 5 years, and the absolute risk reduction nearly doubled from 1.5% to 2.9%. Correspondingly, the number-needed-to-treat improved from 67 to 34 over time, reinforcing the principle that earlier and more sustained LDL-C lowering provides greater clinical benefit. Importantly, no attenuation of LDL-C reduction or emergence of ADAs were observed, underscoring the pharmacodynamic durability and immunologic stability of evolocumab as a fully human mAb. The Evaluation of Cardiovascular Outcomes After an Acute Coronary Syndrome During Treatment With Alirocumab (ODYSSEY OUTCOMES) trial investigated alirocumab in 18,924 patients with recent acute coronary syndrome, focusing on high-risk individuals with elevated LDL-C despite statin therapy. Over a median of 2.8 years, alirocumab reduced MACE by 15%, with greater absolute benefit in patients with baseline LDL-C >100 mg/dL [53]. Subgroup analyses from these trials revealed that patients with polyvascular disease, multivessel disease, high baseline LDL-C, diabetes, and those with recurrent events derived greater absolute risk reductions [52,53]. Particularly, individuals with peripheral artery disease or prior stroke benefited substantially from PCSK9 inhibition, suggesting a more pronounced effect in patients with extensive atherosclerotic burden.

Early-phase applications and plaque stabilization

Beyond their role in chronic lipid management, PCSK9 inhibitors have been explored for their potential vascular effects in acute settings. In the High-Resolution Assessment of Coronary Plaque in Patients With Acute Coronary Syndrome Treated With Evolocumab (HUYGENS) study, evolocumab administered to patients with non-ST elevation myocardial infarction resulted in a rapid 50% LDL-C reduction within 72 hours. Intravascular imaging demonstrated increased fibrous cap thickness and a reduction in lipid-rich plaque burden after 52 weeks of treatment [54]. Although plaque stabilization is not an approved indication, these findings suggest atheroprotective effects beyond simple cholesterol lowering. Emerging data also indicate that PCSK9 may play a role in vascular inflammation. Experimental studies have shown that PCSK9 promotes macrophage activation, endothelial dysfunction, and expression of adhesion molecules, contributing to plaque instability. Inhibition of PCSK9 has been associated with reduced inflammatory markers and favorable modulation of plaque composition [55,56]. While these anti-inflammatory properties are promising, clinical trials have yet to establish a direct impact on inflammatory endpoints.

ANGPTL3 inhibition and remnant cholesterol reduction

ANGPTL3 is a liver-derived inhibitor of LPL and endothelial lipase, regulating TG and remnant cholesterol metabolism. Individuals with LOF mutations in ANGPTL3 exhibit significantly lower levels of LDL-C, TG, and remnant cholesterol, and demonstrate reduced risk of CAD [57]. ANGPTL3 is a key regulator of TG metabolism through its inhibitory action on LPL and endothelial lipase. In the capillary lumen, LPL exists in equilibrium between its active dimeric form and inactive monomeric form. Glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1 (GPIHBP1) transports LPL to the endothelial surface and stabilizes its active dimeric form, allowing efficient hydrolysis of TRLs such as chylomicrons and VLDL into free fatty acids. ANGPTL3 disrupts this process by promoting conversion of active LPL dimers into inactive monomers, thereby reducing LPL-mediated lipolysis (Fig. 3). This leads to impaired clearance of TRLs and accumulation of their remnants, including intermediate-density lipoproteins (IDLs) and small dense LDL. Conversely, inhibition of ANGPTL3 enhances TRL clearance, reduces remnant cholesterol burden, and lowers circulating levels of TG, LDL-C, and apoB-containing lipoproteins. This mechanistic role forms the biological rationale for targeting ANGPTL3 in lipid-lowering strategies—particularly in patients with elevated remnant cholesterol and hypertriglyceridemia (Fig. 3).

Fig. 3.

Mechanism of angiopoietin-like protein 3 (ANGPTL3) inhibition and regulation of triglyceride metabolism. ANGPTL3 inactivates lipoprotein lipase (LPL), reducing clearance of triglyceride-rich lipoproteins (TRLs). Inhibition of ANGPTL3 restores LPL activity, enhancing lipolysis and clearance of remnant cholesterol and apolipoprotein B–containing lipoproteins. GPIHBP1, glycosylphosphatidylinositolanchored high-density lipoprotein-binding protein 1; FFA, free fatty acid; ApoC-III, apolipoprotein C-III.

Evinacumab, a fully human mAb targeting ANGPTL3, has been approved by the U.S. Food and Drug Administration (FDA) for HoFH. In pivotal trials, evinacumab demonstrated robust reductions in LDL-C (up to 50%), TRLs, and apoB-containing particles, with notable increases in the clearance of IDL and LDL [58]. In HoFH patients (n=153), evinacumab increased the clearance rate of IDL by 616%, LDL by 131%, and VLDL by 16%, showing efficacy even in patients with minimal LDL-R activity [59]. Despite its efficacy, evinacumab is currently limited to orphan indications and is administered intravenously, which poses a challenge for wider adoption. The feasibility of large-scale trials in secondary prevention settings remains uncertain. Nonetheless, the development of siRNA-based ANGPTL3 inhibition offers a promising therapeutic option in the future.

ApoA-I–centric protein-based therapies

Interest in ApoA-I–centric therapies was sparked by the discovery of a rare apoA-I variant in an Italian family in the 1980s. Despite markedly reduced HDL-C levels (7 to 14 mg/dL), carriers of the ApoA-I Milano mutation (Arg173Cys) exhibited no clinical signs of atherosclerosis. This paradox—low HDL-C with preserved vascular health—suggested a potentially superior atheroprotective function of this ApoA-I isoform [60].

ApoA-I, the major protein constituent of HDL particles, plays a central role in reverse cholesterol transport. Initially, lipid-poor ApoA-I interacts with ATP-binding cassette transporter A1 (ABCA1) on macrophages within atherosclerotic plaques to facilitate cholesterol and phospholipid efflux. These nascent HDL particles mature via lecithin–cholesterol acyltransferase (LCAT) activity and further lipid acquisition through ATP-binding cassette transporter G1 (ABCG1). Fully mature HDL particles then deliver cholesterol to the liver for excretion, primarily through scavenger receptor class B type I (SR-BI)–mediated uptake as shown in Fig. 4 [61]. Beyond lipid mobilization, ApoA-I exhibits anti-inflammatory and antioxidant effects, modulates lipid rafts, and suppresses Toll-like receptor signaling, contributing to its multifaceted atheroprotective profile [61].

Fig. 4.

Role of apolipoprotein A-I (apoA-I) in reverse cholesterol transport. Lipid-poor apoA-I interacts with ATP-binding cassette transporter A1 (ABCA1) to form nascent high-density lipoprotein (HDL) particles, which mature via lecithin–cholesterol acyltransferase (LCAT) and ATP-binding cassette transporter G1 (ABCG1)-mediated lipid acquisition. Mature HDL delivers cholesterol to the liver through scavenger receptor class B type I (SR-BI). LDL, low-density lipoprotein.

One of the earliest and most widely discussed ApoA-I–based infusion therapies was recombinant ApoA-I Milano (MDCO-216), a variant carrying the Arg173Cys mutation identified in a small cohort of individuals from Limone sul Garda, Italy [62]. An Initial human pilot study using ApoA-I Milano demonstrated rapid regression of atherosclerotic plaque burden and favorable remodeling of coronary lesions [63]. These early findings led to the development of MDCO-216, a recombinant fusion of ApoA-I Milano with phospholipids, administered intravenously to mimic pre-β HDL function. However, subsequent trials failed to replicate the anticipated benefits [64]. The Milano variant inhibited LCAT activity, paradoxically lowering HDL-C levels, and despite theoretical promise, did not induce meaningful plaque regression or clinical benefit. Enthusiasm waned as further development was eventually halted. The case of ApoA-I Milano underscores the complexities of HDL biology and the challenges in translating promising mechanistic insights into therapeutic success. These mechanistic insights led to the development of various ApoA-I–based infusion therapies (Table 2).

Table 2.

Comparative Characteristics of ApoA-I–Based Infusion Therapies under Clinical Investigation

The disappointing outcomes with recombinant ApoA-I Milano shifted the therapeutic focus toward plasma-derived ApoA-I formulations, which might better preserve the native structure and function of the protein. Among these, CSL112, a reconstituted ApoA-I purified from human plasma and complexed with phosphatidylcholine, emerged as a leading candidate. In the ApoA-I Event Reduction in Ischemic Syndromes I (AEGIS-I) trial, CSL112 significantly increased cholesterol efflux capacity and markers of reverse cholesterol transport without hepatotoxicity or nephrotoxicity [65].The large-scale AEGIS-II trial randomized over 17,000 patients within 1 week of myocardial infarction to receive four weekly infusions of CSL112. Although cholesterol efflux capacity increased robustly, no significant reduction in 90-day major adverse MACE was observed (hazard ratio, 1.01; 95% confidence interval, 0.91 to 1.12) [66]. However, prespecified subgroup analyses showed a numerically greater reduction in MACE among patients with baseline LDL-C ≥100 mg/dL, whereas those with lower LDL-C derived no benefit [67]. These findings suggest that residual cholesterol burden may modulate the efficacy of ApoA-I therapy and warrant further study in higher-risk populations.

Another approach explored the use of CER-001, a recombinant wild-type ApoA-I formulated with sphingomyelin and phospholipids to mimic nascent HDL particles. Unlike CSL112, CER-001 was designed to resemble pre-β HDL and intended to facilitate rapid cholesterol efflux and plaque regression. However, in the Can HDL Infusions Significantly QUell Atherosclerosis by Remodeling Endothelium? (CHI-SQUARE) trial, which included patients with recent acute coronary syndrome, CER-001 failed to demonstrate a reduction in coronary atherosclerotic plaque burden as assessed by intravascular ultrasound [68]. The trial also observed a paradoxical decrease in HDL-C levels, possibly due to LCAT inhibition by the recombinant formulation.

These findings highlighted the delicate balance between HDL functionality and structure, and reinforced the notion that cholesterol efflux capacity alone may not predict clinical outcomes unless coupled with appropriate downstream lipid handling and hepatic clearance mechanisms.

PCSK9-targeted RNA therapeutics

PCSK9 is a key regulator of LDL-R homeostasis, promoting lysosomal degradation of LDL-Rs and thereby increasing circulating LDL-C levels [73]. Inclisiran is a GalNAc-conjugated siRNA targeting PCSK9 mRNA in hepatocytes (Fig. 5C) [74]. In the phase 3 ORION-9, ORION-10, and ORION-11 trials, inclisiran achieved sustained LDL-C reductions of approximately50% on top of maximally tolerated statin therapy, with dosing at day 0, month 3, and every 6 months thereafter [75]. Long-term extension data from ORION-3 demonstrated maintained efficacy and safety over 4 years [76]. In addition, inclisiran treatment resulted in significant reduction in MACE in a pooled analyses of phase III clinical trial by 26% [75]. However, individual components of MACE did not show significant reduction.

The FDA initially approved inclisiran in December 2021 as an adjunct to diet and maximally tolerated statin therapy in adults with HeFH or ASCVD and the indication was broadened in 2023 to include adults with primary hyperlipidemia. Importantly, in July 2025 the FDA further updated the label, approving inclisiran as a monotherapy, allowing its use alongside diet and lifestyle modification even without statin therapy.

Inclisiran has been shown to be well tolerated and the most common adverse events were mild injection site reactions. It is also being evaluated under the expansive VICTORION program, including the VICTORION-2P trial (NCT05030428), which will enroll more than 60,000 patients across over 50 countries to assess long-term efficacy and safety.

Lp(a)-targeted RNA therapeutics

Lp(a) is an LDL-like particle covalently bound to apolipoprotein(a), a glycoprotein structurally similar to plasminogen and elevated Lp(a) is a causal and independent risk factor for ASCVD [77]. Conventional lipid-lowering agents have minimal impact on Lp(a) levels, creating a need for targeted therapies.

Pelacarsen is a GalNAc-conjugated ASO targeting LPA mRNA (Fig. 5C) [78]. In phase 2 studies, monthly dosing reduced Lp(a) levels by up to 80% in patients with established ASCVD and elevated Lp(a) [79]. The pivotal phase 3 Lp(a) HORIZON trial (NCT04023552) enrolled approximately 8,000 patients with ASCVD and elevated Lp(a) (≥70 mg/dL) and the topline results will be released in 2026.

Lepodisiran is an investigational, ultra-long-acting GalNAc-conjugated siRNA targeting LPA mRNA, designed to allow very infrequent dosing (potentially once yearly) (Fig. 5C). In the phase 2 ALPACA trial, a single 608 mg subcutaneous dose of lepodisiran reduced Lp(a) by 93.9% at day 60, with >80% reduction sustained for nearly 1 year [80]. This duration of effect suggests that lepodisiran may become the first ‘once yearly’ injectable therapy for Lp(a) lowering. The pivotal phase 3 Lipoprotein(a) Lowering Outcomes Trial of Lepodisiran (ACCLAIM-Lp(a)) trial (NCT06613382) was launched in 2024 and is currently enrolling approximately 8,000 high-risk patients with established ASCVD and elevated Lp(a). The study aims to assess whether long-term Lp(a) lowering with lepodisiran translates into reduced cardiovascular events, with completion anticipated in 2029.

Zerlasiran is another siRNA that suppresses hepatic apolipoprotein(a) production, leading to marked reductions in Lp(a) (Fig. 5C) [81]. In the phase 2 Assessment of Lipoprotein(a) Lowering in Cardiovascular Disease with SLN360 (ALPACAR-360) trial, patients with ASCVD and elevated Lp(a) achieved >80% mean reductions sustained up to 60 weeks, with good tolerability and mainly mild injection site reactions, though cardiovascular outcome benefits remain to be proven.

ApoC-III–targeted RNA therapeutics

apoC-III is a key regulator of TG metabolism, inhibiting LPL and delaying clearance of TRLs (Fig. 3) [82]. Volanesorsen, a second-generation ASO, demonstrated marked TG reductions in familial chylomicronemia syndrome (FCS) and multifactorial severe hypertriglyceridemia. In the APPROACH trial, volanesorsen reduced TG by 77% in FCS patients [83]. However, its use has been limited by thrombocytopenia and injection site reactions and was not approved by FDA [83,84].

Another important advance in the field of ApoC-III–targeted therapies is olezarsen, a GalNAc-conjugated ASO that directly reduces APOC3 mRNA in hepatocytes (Fig. 5C). By silencing apoC-III production, olezarsen lowers TG levels, improves remnant clearance, and favorably alters atherogenic lipoprotein metabolism. Early phase 2 and 3 studies showed robust reductions in TG (40%–60%) and apoC-III levels (>70%), alongside meaningful increases in HDL cholesterol [85]. The clinical promise of olezarsen was confirmed in patients with FCS, a rare but severe form of hypertriglyceridemia associated with pancreatitis risk [86]. Importantly, these trials demonstrated that olezarsen had a favorable safety profile, avoiding some of the dose-limiting toxicities (notably thrombocytopenia) that limited the use of first-generation ASOs such as volanesorsen. In December 2024, the U.S. FDA approved olezarsen (marketed as Tryngolza, Ionis Pharmaceuticals, Carlsbad, CA, USA) as the first drug specifically indicated for FCS, making it a landmark in the treatment of rare lipid disorders.

Another ApoC-III–targeted therapies, plozasiran has drawn considerable attention as a next-generation siRNA designed to silence APOC3 expression in the liver (Fig. 5C). In Study to Evaluate ARO-APOC3 in Adults With Severe Hypertriglyceridemia (SHASTA-2), a phase 2 trial, patients with severe hypertriglyceridemia experienced significant reductions in TG of nearly 60% with plozasiran treatment, while apoC-III levels fell by more than 80% [87]. In MUIR trial, plozasiran significantly reduced TG levels in patients with mixed hyperlipidemia at 24 weeks [88]. In the phase 3 PALISADE trial conducted in patients with FCS, plozasiran reduced median TG levels by about 80% with 25 mg and 78% with 50 mg at 10 months, compared with only 17% in the placebo group [89].

ANGPTL3- and ApoB-100–targeted RNA therapies

ANGPTL3 inhibits lipoprotein and endothelial lipase, raising plasma TG, LDL-C, and HDL-C levels (Fig. 3) [82]. LOF mutations confer protection against ASCVD [57]. Zodasiran is a GalNAc-conjugated siRNA that targets ANGPTL3 mRNA in hepatocytes (Fig. 5C). By silencing ANGPTL3, zodasiran reduces TG, LDL-C, non-HDL-C, apoB, and remnant cholesterol simultaneously, addressing multiple components of residual lipid risk. In the phase 2b ARCHES-2 trial, patients with mixed dyslipidemia experienced reductions of up to 60% in TG and significant decreases across a broad lipid spectrum, with favorable safety and tolerability [90]. These results highlight zodasiran’s potential as a comprehensive lipid-lowering agent with durable efficacy after infrequent dosing. Building on these findings, a phase 3 trial (YOSEMITE) was launched in 2025 to evaluate zodasiran in patients with HoFH. If successful, zodasiran may become the first ANGPTL3-directed RNAi therapy with broad application in severe and mixed dyslipidemia.

ApoB-100 is essential for the assembly and secretion of atherogenic lipoproteins [91]. Mipomersen, a second-generation ASO targeting apoB mRNA, reduced LDL-C by 25% in HoFH [92]. However, mipomersen was associated with several adverse events, such as elevated liver enzymes, hepatic steatosis, injection site reactions, Flu-like symptoms and fatigue [93]. The European Medicines Agency declined approval of mipomersen due to safety concerns in 2013, and although FDA approved its use for HoFH in 2013, but withdrew in 2019 due to safety issues.

Safety and tolerability of RNA-based lipid-lowering therapies

The safety profile of RNA-based lipid-lowering therapies has improved substantially with advances in backbone chemistry and targeted delivery [69]. The most common adverse events are injection site reactions, which are typically mild and transient, and occasional flu-like symptoms. Laboratory findings may include mild elevations in transaminases and, in the case of some ASOs, thrombocytopenia. Importantly, GalNAc conjugation has markedly reduced systemic exposure, thereby lowering the risk of off-target effects.

Inclisiran has demonstrated a favorable long-term safety profile, with no excess hepatic, renal, or muscle-related adverse events reported [94]. Similarly, Lp(a)- and apoC-III–directed agents have not shown concerning immunogenicity or pro-inflammatory effects in phase 2 studies [69].

For volanesorsen, thrombocytopenia remains the principal safety concern and has led to treatment discontinuation in some patients [82,83]. Other adverse effects, such as injection site reactions, flu-like symptoms, and mild hepatic enzyme elevations, have been observed but are generally manageable. Careful monitoring of platelet counts is therefore recommended in clinical use.