Pelacarsen Lp(a) Landscape After the HORIZON Trial Miss

Pelacarsen, developed by Novartis under a license from Ionis, is an investigational drug built to lower lipoprotein(a), usually written Lp(a). It was the first Lp(a)-lowering therapy to report a large cardiovascular outcomes trial, and on September 4, 2026 Novartis said that trial did not meet its primary goal. This pelacarsen Lp(a) landscape article covers what was announced, what is still unknown as of November 4, 2026, and how rival programs are positioned.

Mechanism at a glance

Pelacarsen is an antisense oligonucleotide, a short piece of genetic material designed to inhibit the production of Lp(a). Novartis holds global development and commercialization rights under its agreement with Ionis, and notes that there is no approved targeted treatment for elevated Lp(a).

Why it matters

The Phase 3 trial, Lp(a)HORIZON (NCT04023552), enrolled 8,323 patients with elevated Lp(a) and established cardiovascular disease. Its primary endpoint was a composite of cardiovascular death, non-fatal heart attack, non-fatal stroke and urgent coronary revascularization requiring hospitalization, assessed in patients with Lp(a) of 70 mg/dL or higher and in a subgroup at 90 mg/dL or higher. Novartis reported that pelacarsen lowered Lp(a) but the overall population did not show reduced cardiovascular risk. Its press release gave no hazard ratios or subgroup results. Because it is the first outcomes readout for the whole drug category, the result matters to every sponsor in the field.

Competitive pressure points

• Olpasiran (Amgen): its Phase 3 outcomes trial, OCEAN(a)-Outcomes, enrolled 7,297 participants and is listed as active, not recruiting, with an estimated primary completion of March 2028.
• Lepodisiran (Lilly): the ACCLAIM-Lp(a) outcomes trial is active, not recruiting, with an estimated enrollment of 17,300 and estimated primary completion in March 2029.
• Muvalaplin (Lilly): a Phase 3 outcomes trial in adults with elevated Lp(a) (NCT07157774) is recruiting, with an estimated 10,450 participants and estimated primary completion in March 2031.
• Zerlasiran (Silence Therapeutics): in February 2025 Silence said it would start its Phase 3 outcomes study only after securing a partner. We did not find a signed partner in the sources reviewed.
• Trial design questions: commentators noted that background risk was well controlled, with mean LDL cholesterol around 66 mg/dL, which may leave less room to show benefit.

What to watch

• Whether the full data show an effect in the higher-Lp(a) subgroup, or in particular patient types.
• How much Lp(a) lowering was achieved, and whether event rates track it.
• Whether sponsors of competing outcomes trials change designs, enrollment or timelines. None of the sources we read reported such changes.
• Whether Novartis and Ionis describe any regulatory plans. Novartis’s release did not discuss filings.

For related context, see our guides to reading a ClinicalTrials.gov record and the Factor XI inhibitor landscape.

Recent developments

Updated November 4, 2026. Items are drawn from company announcements, regulators and trade press; links go to the sources.

• Sep 8, 2026: TCTMD reported expert reaction. Dr. Pam Taub noted how well controlled background risk was, and cardiologist David Brown questioned whether treating a possibly non-causal marker treats disease. (TCTMD)
• Sep 8, 2026: Dr. Deepak Bhatt told Healio that Lp(a) remains an independent risk marker, but the open question is whether it is a modifiable mediator of risk or merely a marker, and that ongoing trials should run to completion. (Healio)
• Sep 4, 2026: Novartis announced that Lp(a)HORIZON did not meet its primary endpoint versus placebo. Its chief medical officer called the outcome “not the results we hoped for.” Full data are to be presented at an upcoming congress. (Novartis)
• Feb 27, 2025: Silence Therapeutics said it would slow zerlasiran Phase 3 plans pending a partner. (Fierce Biotech)

Upcoming catalysts

• Nov 7, 2026, 8:35 a.m.: AHA Scientific Sessions (Chicago) opening late-breaking session, which TCTMD’s preview says will present Lp(a)HORIZON in full. The AHA program lists it as an extended analysis of cardiovascular outcomes with pelacarsen. (TCTMD)
• March 2028 (estimated): primary completion of olpasiran’s outcomes trial.
• March 2029 (estimated): primary completion of lepodisiran’s outcomes trial.
• March 2031 (estimated): primary completion of muvalaplin’s outcomes trial.

Bottom line

Pelacarsen lowered Lp(a) but, according to Novartis, did not reduce major cardiovascular events in its Phase 3 trial. Until the full data appear, it is not clear whether the result reflects this drug, the patient population or the Lp(a) hypothesis itself.

Competitors with outcomes trials still running will be read against this result, and the days after the AHA presentation are the first chance to see the detailed numbers.

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This article is for informational and competitive-intelligence purposes only and is not medical advice. Approvals, labels and trial results change; verify details against current prescribing information and primary sources.