Olpasiran: The Quarterly Injection That Silences Lp(a) at the Gene — Inside Amgen's OCEAN(a)-Outcomes Readout (August 6, 2026)
Table of Contents
The risk factor genetics deal you at birth
Lipoprotein(a) — written Lp(a) and spoken 'L-P-little-a' — is one of the most important cardiovascular risk factors most people have never heard of. Roughly one in five people worldwide inherit high levels, and it is a causal driver of heart attack, stroke, peripheral artery disease, and calcific aortic valve stenosis. The frustrating part is that your Lp(a) is set almost entirely by your genes. It barely moves with diet or exercise, and the two workhorses of modern cholesterol care — statins and PCSK9 inhibitors — leave it essentially untouched. You can drive someone's LDL cholesterol to the floor and still leave a dangerous Lp(a) level fully intact. There is no approved therapy that lowers it specifically.
What olpasiran is
Olpasiran (AMG 890) is a once-every-12-weeks injectable being developed by Amgen. It is not a peptide or an antibody but a small interfering RNA — an siRNA — a short, double-stranded piece of genetic material that works through the RNA-interference pathway your cells already use to regulate their own genes. A sugar tag called GalNAc acts as a homing beacon that delivers the drug to liver cells. Once inside, olpasiran hands its guide strand to the cell's RISC machinery (the RNA-induced silencing complex), which then finds and chops up the messenger RNA for apolipoprotein(a), the protein that defines the Lp(a) particle. With that mRNA destroyed, the liver makes far less apo(a) and assembles far fewer Lp(a) particles.
Why one shot lasts three months
The elegance of the siRNA approach is that RISC is catalytic — it doesn't get used up cleaving one mRNA and then stop. A loaded RISC complex keeps finding and cutting apo(a) messages for a long time, so a single dose keeps suppressing Lp(a) for months. That is why olpasiran can be given subcutaneously just once every 12 weeks — a quarterly injection rather than a daily pill or a monthly shot. In the Phase 2 extension, meaningful Lp(a) lowering was still visible many weeks after the last dose, underlining just how durable the effect is.
How well does it lower Lp(a)?
Strikingly well. In the Phase 2 OCEAN(a)-DOSE trial — 281 patients with atherosclerotic cardiovascular disease and Lp(a) above 150 nmol/L — the 75 mg every-12-week dose lowered Lp(a) by about 97% versus placebo at 36 weeks, with higher doses reaching similar near-total suppression. Those results were published in the New England Journal of Medicine in 2022. As with the rest of this class, the open question was never whether olpasiran lowers Lp(a) — it clearly, dramatically does — but whether that lowering actually prevents heart attacks and strokes.
OCEAN(a)-Outcomes: the experiment that matters
That question is what the Phase 3 OCEAN(a)-Outcomes trial (NCT05581303) was built to answer. It enrolled about 7,000 patients with established atherosclerotic cardiovascular disease and Lp(a) of at least 200 nmol/L into a global, randomized, double-blind, placebo-controlled study, testing whether 225 mg of olpasiran every 12 weeks reduces major coronary events — a composite of coronary heart disease death, heart attack, and urgent coronary revascularization. The trial began in December 2022, is now fully enrolled and no longer recruiting, and is expected to read out around December 2026. Amgen has also started a coronary CT angiography substudy to see whether lowering Lp(a) changes plaque itself.
Where olpasiran sits in the class
Olpasiran is not alone — it is one of a tight cluster of Lp(a)-lowering drugs racing toward the same finish line. The antisense oligonucleotide pelacarsen (Ionis/Novartis) is furthest along, with its Lp(a)HORIZON outcomes trial also reading out in 2026; the other siRNAs are Eli Lilly's lepodisiran and Silence Therapeutics' zerlasiran. All of them rest on the same unproven premise: that lowering Lp(a) will translate into fewer cardiovascular events. Because pelacarsen and olpasiran both report outcomes in 2026, this is the year the field finds out — and olpasiran specifically serves as the bellwether for the siRNA arm of the class.
The bottom line
Olpasiran is an investigational, once-every-12-weeks siRNA from Amgen that lowers lipoprotein(a) by up to about 97% by silencing the apolipoprotein(a) gene in the liver. It is not approved anywhere, and it is a prescription clinical-stage medicine — not a supplement or research chemical; anything sold under the names 'olpasiran,' 'AMG 890,' or 'ARO-LPA' by a vendor is unverified. Its Phase 3 OCEAN(a)-Outcomes trial is one of the pivotal 2026 readouts asking whether lowering Lp(a) prevents heart attacks and strokes, sitting alongside pelacarsen's Lp(a)HORIZON at the very top of preventive cardiology's watch list — and testing the promise of the whole Lp(a)-lowering class that also includes lepodisiran and zerlasiran.
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Citations
- [1] Nissen SE et al. — Olpasiran for Lowering Lipoprotein(a) in ASCVD (OCEAN(a)-DOSE Phase 2), New England Journal of Medicine (2022) Source
- [2] OCEAN(a)-Outcomes — Olpasiran Trials of Cardiovascular Events and Lipoprotein(a) Reduction (ClinicalTrials.gov NCT05581303) Source
- [3] Amgen Presents Late-Breaking Phase 2 Olpasiran Data at ESC 2023 Source
- [4] Lipoprotein(a): An Independent Risk Factor for CV Disease — American College of Cardiology Source
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