What happened
Pelacarsen fails to reduce major adverse cardiovascular events compared to placebo.
Lowering Lp(a) had zero effect on events in HORIZON, which points to the most pessimistic scenario.
He calls the trial a big bust, with no effect on cardiovascular events in patients above 70 or 90 mg/dL, however the data were analyzed. He reads this as favoring the view that lowering Lp(a) is very unlikely to move the needle.
General · Cleveland Clinic
Although the results are disappointing, neutral trials also provide scientific insights that help inform future research efforts. A single trial does not provide definitive evidence of a lack of benefit of lowering lipoprotein(a) as a strategy to reduce cardiovascular risk.
Lp(a)HORIZON Extended Analyses co-authorAlthough lower Lp(a) levels were observed with pelacarsen, the findings did not demonstrate that this translated into reduced cardiovascular risk in the overall study population. These are not the results we hoped for, but they provide important evidence that advances scientific understanding of the relationship between Lp(a) lowering and cardiovascular outcomes and may help inform future approaches to cardiovascular risk management.
Lp(a)HORIZON Extended AnalysesGeneral · Cleveland Clinic
I cannot avoid the disappointing conclusion – it didn't work. Pelacarsen improved Lp(a) measures significantly – 78% lower; however, cardiovascular outcomes were unchanged. The neutral finding was unexpected and surprising to the medical community,
Lp(a)HORIZON Extended Analyses co-author
General Cardiology
It seemed incredibly unlikely to me that this one small lipoprotein that is one of so many risk markers for heart disease could possibly have any significant effect on heart disease risk in the way that it has been hyped in the last few years,
Lp(a)HORIZON Extended AnalysesUniversity of Limerick
There's been a lot of shock and dismay. I think the question we're all left with is, is this a failure in some way of a hypothesis or is it a failure of a specific therapy or some quirk with a study design?
Lp(a)HORIZON Extended AnalysesOn the other hand, if that's the reason the trial was negative, then that at least would tell us in an analogous population, they don't necessarily need an Lp(a)-targeted drug
Lp(a)HORIZON Extended Analyses
Preventive Cardiology
In this study, patients actually had very well-controlled risk factors, including their LDL [low-density lipoprotein] cholesterol. If you control all of the risk factors and you reduce risk in every other way, is there enough residual risk from Lp(a) to make a difference?
Lp(a)HORIZON Extended AnalysesOpen questions from this trial that would benefit from expert input.
Answers are grounded in this paper and cite their sources.
Why the trial, tables, limitations, PICO, abstract, media & sources
After a randomized placebo-controlled trial showed that the lipoprotein(a)-lowering antisense oligonucleotide pelacarsen did not reduce major adverse cardiovascular events in patients with established cardiovascular disease, this extended analysis was conducted to further investigate the association between pelacarsen treatment and cardiovascular outcomes across various treatment exposures, achieved lipoprotein(a) levels, and patient subgroups.
Does pelacarsen reduce the composite of death from cardiovascular causes, nonfatal myocardial infarction, nonfatal stroke, or urgent coronary revascularization in patients with established cardiovascular disease and high lipoprotein(a) across extended on-treatment, landmark, and subgroup analyses?
Does pelacarsen reduce the composite of death from cardiovascular causes, nonfatal myocardial infarction, nonfatal stroke, or urgent coronary revascularization in patients with established cardiovascular disease and high lipoprotein(a) across extended on-treatment, landmark, and subgroup analyses?
Extended analyses of this randomized trial demonstrate that pelacarsen fails to reduce major adverse cardiovascular events even when accounting for on-treatment adherence, magnitude of lipoprotein(a) reduction at 3 months, total recurrent events, or baseline biomarker subgroups.
Experts read these extended analyses as a firm null result for pelacarsen, but they disagree over whether it sinks the idea of lowering lipoprotein(a) or only this drug and trial.
Nobody is arguing the drug cut cardiovascular events, and the reaction ranges from disappointment to open skepticism. Some read the result as a broad failure of the lipoprotein(a) hypothesis. Others say one neutral trial cannot settle it, and the live question is whether the hypothesis, the specific therapy, or the study design failed.
Hypothesis failure, or one trial that cannot settle the question?
3 takes classified by contention axis so far — the map appears as more land.
Experts ask whether the failure reflects the hypothesis, this specific therapy, or a quirk of the study design. They also question whether enough residual risk from lipoprotein(a) remains once other risk factors, including LDL cholesterol, are well controlled.
Pelacarsen does not reduce MACE in high-Lp(a) patients with CVD; confirms lack of cardiovascular benefit from Lp(a) lowering with this antisense oligonucleotide.
Background Pelacarsen is an antisense oligonucleotide that reduces serum levels of lipoprotein(a). In a randomized placebo-controlled trial in patients with established cardiovascular disease, pelacarsen did not reduce the risk of major adverse cardiovascular events compared to placebo. We further investigated the association of pelacarsen treatment with cardiovascular outcomes. Methods We report the association of pelacarsen treatment with a primary composite end point of death from cardiovascular causes, nonfatal myocardial infarction, nonfatal stroke, or urgent coronary revascularization. Analyses included on-treatment, uninterrupted treatment, total primary end point events (first and recurrent events), landmark analyses classified by changes in and achieved lipoprotein(a) at 3 months, and key subgroups including baseline lipoprotein(a), low-density lipoprotein (LDL) cholesterol, high-sensitivity C-reactive protein (CRP), and time from qualifying event to enrollment. Results For participants on treatment, a primary end point occurred in 434 participants (10.4%) randomly assigned to placebo and 380 participants (9.1%) assigned to pelacarsen (hazard ratio, 0.98; 95% confidence interval [CI], 0.85 to 1.12). When evaluating participants with uninterrupted treatment, a primary end point event occurred in 167 participants (11.0%) in the pelacarsen group and 204 participants (10.1%) in the placebo group (hazard ratio, 1.09; 95% CI, 0.89 to 1.34). When evaluating total primary end point events, there were 644 events in the pelacarsen group and 646 events in the placebo group (rate ratio, 1.00; 95% CI, 0.87 to 1.14). In landmark analyses evaluating participants alive and free of the composite end point at 3 months, when compared to placebo there was no association between pelacarsen treatment and the primary end point either in participants with reduction in lipoprotein(a) greater than or equal to the median (170 nmol/l) (hazard ratio, 1.09; 95% CI, 0.92 to 1.29) or in participants who achieved lipoprotein(a) lower than or equal to the median (69.5 nmol/l) (hazard ratio, 1.10; 95% CI, 0.93 to 1.29). There was also no association between pelacarsen treatment and the primary end point in any of the evaluated key subgroups including classification by median baseline lipoprotein(a), LDL cholesterol, high-sensitivity CRP, or time from qualifying cardiovascular disease to enrollment. Conclusions Pelacarsen was not associated with a reduction in major adverse cardiovascular events when evaluated by treatment exposure, changes in or achieved lipoprotein(a) levels at 3 months, considering total events, or within subgroups of baseline lipoprotein(a), LDL cholesterol, or high-sensitivity CRP levels.
Nissen et al. (2026) conducted an RCT in Established cardiovascular disease and high lipoprotein(a). Pelacarsen vs. Placebo was evaluated on Composite of death from cardiovascular causes, nonfatal myocardial infarction, nonfatal stroke, or urgent coronary revascularization (on-treatment analysis) (HR 0.98, 95% CI 0.85-1.12). Pelacarsen did not reduce major adverse cardiovascular events compared to placebo in on-treatment (9.1% vs 10.4%; HR 0.98; 95% CI 0.85-1.12) or landmark lipoprotein(a) analyses.
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