Lp(a)-Lowering Drug Pelacarsen Fails to Reduce Major Cardiovascular Events in Phase 3 Trial

On September 4, 2026, the pharmaceutical company Novartis announced that its experimental drug pelacarsen failed to prevent heart attacks and strokes in a massive 8,323-patient clinical trial.[1][2]

The result marks a major setback in the effort to treat elevated Lipoprotein(a), or Lp(a), a genetically determined cholesterol particle that affects approximately 20% of the global population. Unlike standard LDL cholesterol, Lp(a) is largely immune to diet, exercise, and conventional statins.[5]

Pelacarsen, developed in partnership with Ionis Pharmaceuticals, is an antisense oligonucleotide administered as one monthly injection. It was designed to block the production of Lp(a) in the liver.[1][2]

The Phase 3 trial, known as Lp(a)HORIZON, enrolled patients who already had established cardiovascular disease and elevated Lp(a) levels above the 70 mg/dL threshold. All participants were already receiving optimized, guideline-directed care, including standard lipid-lowering and antihypertensive therapies.[2][4]

Chemically, the drug worked exactly as intended. Novartis confirmed that patients receiving pelacarsen achieved substantially lower Lp(a) levels compared to those on a placebo.[1][3]

However, that chemical reduction did not translate into a clinical benefit. The trial missed its primary endpoint, failing to significantly reduce the 4-point composite risk of cardiovascular death, non-fatal myocardial infarction, non-fatal stroke, and urgent coronary revascularization.[1][2][3]

"Although 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," said Shreeram Aradhye, M.D., Novartis' chief medical officer.[2]

For patients who recently discovered they have high Lp(a) following new screening guidelines, the result is disappointing but does not change immediate management. The clinical focus remains on aggressively controlling all other modifiable risk factors, such as blood pressure and LDL cholesterol, to mitigate overall risk.[5]

The failure now forces the cardiology community to ask whether the entire Lp(a) hypothesis is flawed, or if pelacarsen simply did not lower the particle deeply enough. In previous studies, pelacarsen reduced Lp(a) by roughly 72% to 80%.[2]

Newer therapies currently in Phase 3 trials, such as Amgen's olpasiran and Eli Lilly's lepodisiran, utilize a different mechanism—small interfering RNA (siRNA)—and have demonstrated the ability to lower Lp(a) by more than 90%.[2]

Analysts note that those deeper reductions might be necessary to actually prevent cardiovascular events. Novartis plans to present the full Lp(a)HORIZON data at an upcoming medical congress, which will provide crucial details on whether any specific subgroups saw a benefit during the minimum 2.5 years of follow-up.[2][4]