Small Interfering RNA to Reduce Lipoprotein(a) in Cardiovascular Disease (OCEAN(a)-DOSE)

The OCEAN(a)-DOSE trial randomized 281 patients with established ASCVD and elevated Lp(a) (≥150 nmol/L) to one of four doses of olpasiran — a subcutaneous small interfering RNA (siRNA) targeting apo(a) synthesis — or placebo administered every 12 weeks.

Olpasiran produced dose-dependent, profound reductions in Lp(a): 70-100% reduction from baseline at the higher doses, sustained throughout the dosing interval. The placebo group had no meaningful Lp(a) change. Safety and tolerability were acceptable; injection site reactions were the most common adverse event. The trial was not powered for cardiovascular event reduction.

The clinical significance is very high — not because of current outcomes data but because of what this trial establishes about therapeutic feasibility. For the first time, a phase 2 trial demonstrated that Lp(a) can be nearly eliminated pharmacologically with a well-tolerated subcutaneous injection given quarterly. This was not achievable with any existing therapy (PCSK9 inhibitors reduce Lp(a) by only 25–30%).

Lp(a) is present at elevated levels in approximately 20% of the general population and has no reliably effective treatment. Mendelian randomization studies estimate that the cardiovascular risk attributable to Lp(a) is clinically significant and causally driven. Olpasiran and similar agents (pelacarsen, zerlasiran) are now in phase 3 cardiovascular outcomes trials.

We rate the evidence strong for a phase 2 dosing study. A landmark proof-of-concept trial demonstrating near-complete Lp(a) elimination with a novel siRNA agent — potentially the most important emerging therapy in cardiovascular prevention.