Olezarsen Doesn’t Lower Plaque Volume: Essence-TIMI 73b

Why It Matters

The findings highlight that short‑term triglyceride reduction may not translate into plaque regression, emphasizing the need for large outcomes trials to confirm any cardiovascular benefit of APOC3 inhibition.

Key Takeaways

• Olezarsen cut TG 63.9% in 6 months.
• No significant change in noncalcified plaque at 12 months.
• ApoB reduced only 16%, LDL unchanged.
• 97% patients on background lipid therapy.
• Longer trials may reveal cardiovascular benefits.

Pulse Analysis

Olezarsen, an antisense oligonucleotide that silences APOC3 mRNA, entered phase III testing in the Essence‑TIMI 73b trial to see whether aggressive triglyceride reduction could translate into measurable changes in coronary plaque. In the 468‑patient cohort, the drug lowered fasting triglycerides by nearly 64 % and cut remnant cholesterol by 72 % after six months, while apolipoprotein B fell 16 % and LDL cholesterol remained flat. Despite these lipid shifts, a 12‑month coronary CTA subanalysis showed no statistically significant difference in non‑calcified plaque volume compared with placebo.

The neutral imaging result underscores a growing recognition that short‑term plaque metrics may not capture the full clinical benefit of triglyceride‑targeted therapies, especially when patients are already on high‑intensity statins and other lipid‑lowering agents. Nearly all participants (97 %) received background therapy, limiting the incremental impact of APOC3 inhibition on atherogenic particle burden. Moreover, the modest absolute reduction in apoB suggests that without a larger shift in LDL‑family lipoproteins, plaque regression is unlikely within a single year. Longer follow‑up may be required to observe outcome differences.

Regulators have approved Olezarsen for familial chylomicronemia syndrome, but its role in broader hypertriglyceridemia remains uncertain. The trial’s investigators liken the situation to ezetimibe, which failed to shrink plaque in ENHANCE yet proved valuable in the outcomes‑driven IMPROVE‑IT study. A dedicated cardiovascular outcomes trial lasting four to five years could determine whether the triglyceride‑lowering effect of APOC3 silencing ultimately reduces myocardial infarction or death. If positive, Olezarsen could join icosapent ethyl and other adjuncts as a niche therapy for residual risk management.