Pablo Corral: Is the Lp(a) Hypothesis Wrong?

Pablo Corral, Pharmacology Professor at FASTA University, Past President of Argentine Lipid Society, shared a post on LinkedIn:

“Lp(a)HORIZON is negative.

Does this mean the Lp(a) hypothesis is wrong?

Not necessarily.

Before seeing the full dataset, at least 17 potential explanations deserve consideration:

1. Background therapy matters.

Aggressive LDL-C or ApoB lowering may reduce the residual risk attributable to Lp(a).

2. Too little, too late?

Genetics reflects lifelong exposure; a few years of treatment after established ASCVD may not reverse decades of vascular injury.

3. Magnitude and duration matter.

We need achieved absolute Lp(a) levels, sustained reduction, adherence and exposure over time.

4. The extreme-tail hypothesis.

Benefit may be concentrated in patients with the highest baseline Lp(a).

5. Lp(a) concentration is not equal to biological activity.

Apo(a) phenotype, particle composition and other features may influence pathogenicity.

6. Endpoint dilution.

Lp(a) lowering may affect coronary outcomes more than other components of 4-point MACE.

7. Genetics predicts causality better than treatment effect size.

Lifelong genetic exposure cannot be directly translated into a few years of pharmacological lowering.

8. What about OxPL?

Lp(a) is a major carrier of oxidized phospholipids.

Perhaps OxPL burden matters as much as Lp(a) concentration itself.

9. Antiplatelet therapy may matter.

In secondary prevention, widespread aspirin or P2Y12 use could attenuate part of Lp(a)’s prothrombotic effect.

10. Low event rates.

Despite 8,323 high-risk patients, events accumulated more slowly than expected – potentially leaving less absolute risk to modify.

11. Was the expected effect too large?

Even a large event-driven trial can miss a smaller-than-anticipated true treatment effect.

12. Slow event accrual may itself be informative.

Very high Lp(a) may confer major lifetime risk but less short-term modifiable risk under contemporary treatment.

13. Six years changes medicine.

Therapeutic ‘drop-ins’ and better risk-factor control during prolonged follow-up may further reduce events in both groups.

14. Not all MACE components are equally Lp(a)-dependent.

MI and coronary events may tell a different story from the overall composite.

15. First events may not tell the whole story.

Total and recurrent coronary events will be important.

16. ‘Risk-factor exhaustion.’

With LDL-C approximately 65 mg/dL, intensive lipid lowering, antiplatelet therapy and excellent contemporary prevention, little modifiable residual risk may remain.

17. Lp(a) may depend on its biological environment.

Its clinical impact may reflect the interaction of apoB burden plus OxPL-driven inflammation plus thrombosis – pathways already partially suppressed in HORIZON.

Perhaps HORIZON did not fail because Lp(a) is irrelevant.

Perhaps it tells us that ‘causal’ does not mean equally modifiable at every stage of disease.

The full data should tell us not only whether Lp(a) lowering works, but how much, in whom, and – critically – when.”

Romit Bhattacharya, Associate Director of the Cardiac Lifestyle Program at Massachusetts General Hospital, shared this post on LinkedIn, adding:

“Clear eyed questions re: Lp(a) HORIZON trial with pelacarsen.

Rather than offering quick takedowns based on top line results – let’s ask careful questions and approach with curiosity.

Looking forward to digging into the data once released!”

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