Ionis Pharmaceuticals, Inc. filed a Form 8-K on September 4, 2026, disclosing that its partner Novartis reported the pelacarsen Phase 3 Lp(a)HORIZON cardiovascular outcomes study did not meet its primary endpoint compared to placebo.

Key Highlights

  • Primary endpoint missed: The Lp(a)HORIZON study did not meet its primary endpoint of reducing the risk of cardiovascular events compared to placebo.
  • Composite endpoint defined: The primary endpoint was a composite of cardiovascular death, non-fatal myocardial infarction, non-fatal stroke, and urgent coronary revascularization requiring hospitalization.
  • Lp(a) reduction observed: According to the filing, "consistent with previous studies, substantially lower lipoprotein (a) levels were achieved with pelacarsen."
  • Safety profile: The filing states pelacarsen "demonstrated an acceptable safety profile."
  • Data presentation pending: Full Lp(a)HORIZON data will be presented at an upcoming medical congress, according to the filing.
  • Licensing history: Ionis discovered and conducted early development of pelacarsen; Novartis exercised an option to license rights to develop and commercialize it in February 2019.

Ionis Discloses Novartis Lp(a)HORIZON Phase 3 Failure for Pelacarsen

Ionis Pharmaceuticals, Inc. (NASDAQ:IONS), headquartered in Carlsbad, California, filed a current report on September 4, 2026 under Items 7.01 and 8.01, disclosing that partner Novartis reported results from the pelacarsen Phase 3 Lp(a)HORIZON study. According to the filing, the study, described as "a pioneering cardiovascular outcomes trial," did not meet its primary endpoint of reducing the risk of cardiovascular events compared to placebo. The composite primary endpoint encompassed cardiovascular death, non-fatal myocardial infarction, non-fatal stroke, and urgent coronary revascularization requiring hospitalization.

The filing noted that, consistent with prior studies, substantially lower Lp(a) levels were achieved with pelacarsen, and that the drug demonstrated an acceptable safety profile. The filing also noted that elevated Lp(a) "is an inherited cardiovascular risk factor affecting approximately one in five people worldwide with no approved targeted treatment." Complete data from the Lp(a)HORIZON study are expected to be presented at an upcoming medical congress, though no specific date or venue was named in the filing.

Ionis disclosed that it originally discovered pelacarsen and conducted its early development. In February 2019, Novartis exercised an option to license the rights to develop and commercialize pelacarsen for targeted cardiovascular therapy. The filing includes forward-looking statements, which the company cautioned "are subject to certain risks and uncertainties" and which it said reflect only "facts and factors currently known by Ionis." The company stated it undertakes no obligation to update forward-looking statements except as required by law.

What Was Disclosed

Ionis Pharmaceuticals disclosed via an 8-K that the Novartis-led pelacarsen Phase 3 Lp(a)HORIZON trial failed to meet its primary cardiovascular outcomes endpoint compared to placebo, while Lp(a) reductions were achieved and the safety profile was reported as acceptable.