A major phase 3 clinical trial has found that pelacarsen much reduced levels of lipoprotein(a) in patients with cardiovascular disease, but did not lower their risk of serious heart events compared with a dummy treatment.
The results were presented at the American Heart Association’s Scientific Sessions 2026 and simultaneously published in the New England Journal of Medicine, which published the full findings of the Lp(a)HORIZON trial. The study focused on patients who already have cardiovascular (heart and blood vessel) disease and who also carry high levels of lipoprotein(a) — a fatty protein in the blood that has long been associated with raised heart risk.
Pelacarsen did what it was designed to do. It brought lipoprotein(a) levels down. But when researchers looked at actual outcomes — heart attacks, strokes, and other major cardiovascular events — patients taking the drug fared no better than those given a placebo.
That gap between a measurable biological change and a real-world health benefit is a familiar challenge in cardiovascular research. Lowering a marker in the blood does not always translate into fewer deaths or hospital admissions, and the Lp(a)HORIZON results are a clear example of that distinction.
The trial is described as a phase 3 study, meaning it was a large, late-stage test designed to establish whether the treatment works well enough for wider clinical use. Its findings, according to the New England Journal of Medicine, suggest pelacarsen does not meet that bar for reducing major cardiovascular events.
Lipoprotein(a) — often written as Lp(a) — has attracted growing scientific interest because raised levels are largely inherited and cannot be addressed through diet or standard cholesterol-lowering drugs such as statins. The search for an effective treatment remains ongoing.
Source: @NEJM