Researchers presented full results of Novartis's Lp(a)HORIZON trial at the American Heart Association's Scientific Sessions in Chicago on Saturday. The data confirmed that pelacarsen sharply lowered lipoprotein(a) but did not significantly reduce heart attacks, strokes or cardiovascular deaths. It was the first completed outcomes trial of a drug targeting the inherited cholesterol particle.

Novartis disclosed in topline results on 4 September that the phase 3 study had missed its primary endpoint, and said full data would follow at a scientific congress. The trial enrolled more than 8,000 patients with established cardiovascular disease and raised Lp(a) levels. Pelacarsen, a monthly antisense injection developed with Ionis Pharmaceuticals, had cut Lp(a) by roughly 80% in earlier studies.

The investigators said on Saturday that event rates in the pelacarsen group were numerically lower than in the placebo group, but the difference fell short of statistical significance. They pointed to subgroup and secondary analyses, including patients with the highest Lp(a) levels, as areas for further study. Novartis said it would review the full dataset with regulators before deciding on next steps.

The result casts a shadow over rival programmes, including Amgen's olpasiran and Eli Lilly's lepodisiran, whose outcomes trials are still running. Cardiologists attending the four-day meeting at McCormick Place said the findings raised questions about how far Lp(a) must fall, and for how long, before patients benefit. Some suggested the newer siRNA drugs, which lower Lp(a) more deeply, could still succeed where pelacarsen did not.

About one in five people worldwide carry elevated Lp(a), according to the American Heart Association, and no approved drug specifically lowers it. The AHA has urged doctors to test patients at least once in their lifetime. The Scientific Sessions continue until Monday with further late-breaking trials.