Novartis Shares Fall After Pelacarsen Fails Heart Trial

Novartis shares fell over 3% on Monday after reporting that its experimental blood fat-lowering drug pelacarsen missed its primary endpoint in a major late-stage trial, failing to reduce heart attacks and strokes.

"These are not the results we hoped for," said Shreeram Aradhye, Novartis’s chief medical officer, adding that the data still "advances scientific understanding of the relationship between Lp(a) lowering and cardiovascular outcomes."

The Lp(a)HORIZON Trial Results

The late-stage trial, known as Lp(a)HORIZON, evaluated more than 8,000 patients diagnosed with elevated levels of lipoprotein(a), a specific type of blood fat strongly linked to cardiovascular disease. Although pelacarsen successfully reduced lipoprotein(a) concentrations in patients' blood as intended, this biochemical change did not translate into a statistically significant decrease in severe cardiovascular events such as heart attacks and strokes.

Partner Ionis Pharmaceuticals (NASDAQ: IONS), which developed the underlying technology, also absorbed immediate market pressure following the announcement. Shares of Ionis Pharmaceuticals fell 6% in aftermarket trading as investors processed the setback for the shared cardiovascular pipeline asset.

"Although pelacarsen substantially lowered lipoprotein(a) levels consistent with previous studies, we are disappointed that this did not translate to cardiovascular risk reduction," said Ionis CEO Brett Monia.

What Is Lipoprotein(a) and Why It Matters

Lipoprotein(a) is an inherited form of low-density lipoprotein cholesterol that circulates in the bloodstream. High concentrations are recognized by cardiologists as an independent risk factor for premature coronary heart disease, aortic stenosis, and stroke, largely because standard statin medications do not effectively lower Lp(a) levels.

Pharmaceutical developers have spent years pursuing targeted therapies to lower Lp(a), hypothesizing that reducing this specific lipid would directly lower cardiovascular morbidity. The failure of the Lp(a)HORIZON trial challenges that premise, forcing a re-evaluation of how researchers interpret Lp(a) reduction as a surrogate endpoint for clinical benefit in drug development.