Novartis pelacarsen Phase III trial fails to cut CV events
Novartis has reported that its Phase III Lp(a)HORIZON trial of pelacarsen, an investigational antisense oligonucleotide (ASO) targeting lipoprotein(a), failed to meet its primary endpoint. The study, conducted in 8,323 patients with elevated Lp(a) and established cardiovascular disease, did not demonstrate a statistically significant reduction in a four-point major adverse cardiovascular events (MACE) composite compared with placebo. That composite comprised cardiovascular death, non-fatal myocardial infarction, non-fatal stroke, and urgent coronary revascularisation requiring hospitalisation.
Crucially, pelacarsen did achieve its mechanistic goal: Lp(a) levels were measurably reduced in participants who were already receiving guideline-directed therapy, including lipid-lowering and antihypertensive agents. The disconnect between biomarker reduction and clinical benefit is the central scientific question the trial was designed to resolve.
What the data mean
Shreeram Aradhye, President of Development and Chief Medical Officer at Novartis, said the findings "provide important evidence that advances scientific understanding of the relationship between Lp(a) lowering and cardiovascular outcomes," while acknowledging they were "not the results we hoped for." The trial enrolled patients with baseline Lp(a) of at least 70 mg/dL, with a pre-specified subpopulation at 90 mg/dL or above. Novartis has not yet disclosed whether subgroup analyses show differential effects by baseline Lp(a) level; full data will be presented at an upcoming medical congress.
Elevated Lp(a) is an inherited trait, approximately 90% genetically determined and largely resistant to dietary or lifestyle intervention. It is estimated to affect around one in five people globally, and roughly one-third of those with premature cardiovascular disease carry elevated levels. Despite US and European guidelines recommending at least one lifetime Lp(a) measurement for all adults, no approved targeted therapy currently exists for the indication.
Market and competitive context
The Lp(a)HORIZON readout is a significant setback for the entire field of Lp(a)-targeted therapy, not just for Novartis. Pelacarsen was in-licensed from Ionis Pharmaceuticals and represented one of the most advanced and largest-powered outcomes studies in the space. The result will now raise hard questions about whether Lp(a) lowering per se, as a mechanism, translates into event reduction in patients already well-managed on modern background therapy.
A number of other companies have programmes targeting Lp(a) through different modalities, including small interfering RNA (siRNA) approaches. Inclisiran, Novartis's own approved siRNA targeting PCSK9, demonstrated cardiovascular event reduction, but that mechanism addresses LDL-C rather than Lp(a). Whether the Lp(a)HORIZON failure reflects a platform limitation specific to ASOs, a dosing question, a patient-selection issue, or a more fundamental challenge to the Lp(a) hypothesis itself will be closely debated once the full dataset is available.
For investors, the result removes a meaningful pipeline asset from Novartis's cardiovascular portfolio at a time when the company has been repositioning around cardiometabolic disease. Regulatory agencies in the US and Europe have signalled interest in Lp(a) as a therapeutic target in recent guideline updates, but a failed Phase III outcomes trial materially alters the evidentiary landscape and may prompt reconsideration of how the biomarker is weighted in future risk-stratification frameworks. The broader cardiovascular drug development community will be watching the congress presentation carefully for any signal, however modest, that a refined patient population or alternative dosing strategy could support a successor programme.