Lower biomarker, unchanged clinical outcome
Pelacarsen, a monthly antisense oligonucleotide designed to lower lipoprotein(a), substantially reduced that blood marker in patients with established cardiovascular disease. But in a large international randomized trial, the reduction did not translate into fewer major adverse cardiovascular events.
The finding comes from a study published online November 7 in the New England Journal of Medicine, timed with the American Heart Association Scientific Sessions 2026 in Chicago. It is an important result for a therapy aimed at a cardiovascular risk factor that has attracted sustained attention: the treatment altered the measure it targeted, yet the study’s primary clinical endpoint was essentially unchanged.
Investigators enrolled patients with preexisting cardiovascular disease whose lipoprotein(a) level was at least 70 mg/dL. They randomly assigned 4,157 people to receive 80 mg of subcutaneous pelacarsen once a month and 4,165 to receive matching placebo. Median follow-up was 4.7 years.
What the trial found
Participants began the study with a median lipoprotein(a) concentration of 236 nmol/L. At 12 months, the median level was 64.4 nmol/L in the pelacarsen group, compared with 233.4 nmol/L in the placebo group.
That biomarker separation was not accompanied by a difference in the trial’s primary endpoint, major adverse cardiovascular events. Such an event occurred in 12.3% of patients receiving pelacarsen and 12.1% of those receiving placebo.
The neutral result also persisted in the group with higher starting levels. Among patients whose baseline lipoprotein(a) was at least 90 mg/dL, a primary-endpoint event occurred in 12.3% of both the pelacarsen and placebo groups.
Serious adverse events were reported in 37.3% of patients assigned pelacarsen and 41.1% of those assigned placebo. The supplied report does not provide further detail on the nature of those events or establish why the clinical endpoint remained unchanged despite the large reduction in lipoprotein(a).
A difficult result for a targeted approach
Lipoprotein(a), often written as Lp(a), was central to the trial’s design. The researchers selected people with both established cardiovascular disease and elevated levels of the marker, then tested whether persistent monthly treatment could improve hard cardiovascular outcomes over years of follow-up.
On the first part of that question, the trial produced a clear biochemical result. The reported 12-month medians show a marked difference between groups. Senior author Steven E. Nissen of the Cleveland Clinic said pelacarsen lowered lipoprotein(a) measures by 78%.
On the second and more consequential question, the answer was negative: cardiovascular outcomes did not improve under the primary endpoint. Nissen characterized the conclusion as disappointing and said the neutral finding had been unexpected.
The distinction matters because a change in a laboratory measure, even a pronounced one, is not the same as a demonstrated reduction in heart attacks, strokes, or other major cardiovascular events. This trial was built to assess both. Its results show that lowering lipoprotein(a) with this regimen was achievable, while a benefit on the composite clinical endpoint was not observed.
Scale and duration give the finding weight
The trial included more than 8,300 participants across the two randomized groups and followed them for a median of nearly five years. That scale and duration made it possible to compare event rates rather than relying only on short-term changes in blood measurements.
The reported event rates were close: 12.3% for pelacarsen and 12.1% for placebo. In the higher-baseline subgroup cited in the report, they were identical at 12.3% in each group. Those figures frame the study’s central conclusion more directly than the large difference in lipoprotein(a) levels alone.
For patients and clinicians, the result does not negate the observed effect on lipoprotein(a). It does, however, mean that the trial did not demonstrate that monthly pelacarsen reduced major adverse cardiovascular events in the studied population.
What is established by this study
- Monthly 80 mg subcutaneous pelacarsen lowered lipoprotein(a) levels in patients with established cardiovascular disease and elevated lipoprotein(a).
- At 12 months, median lipoprotein(a) was 64.4 nmol/L with pelacarsen and 233.4 nmol/L with placebo.
- Over a median 4.7 years, major adverse cardiovascular events occurred at similar rates in the two groups.
- The reported serious-adverse-event rate was lower in the pelacarsen group than in the placebo group, though the supplied source does not provide a breakdown.
The study therefore delivers a sharply defined message. Pelacarsen had the intended effect on lipoprotein(a), but in this trial that effect did not produce a reduction in the major cardiovascular events measured by the researchers. The full study is identified as “Pelacarsen and Cardiovascular Outcomes in Patients with High Lipoprotein(a)” and carries the DOI 10.1056/nejmoa2610159.
This article is based on reporting by Medical Xpress. Read the original article.
Originally published on medicalxpress.com
