Olpasiran, Oxidized Phospholipids, and Systemic Inflammatory Biomarkers: Results From the OCEAN(a)-DOSE Trial.

Importance: Lipoprotein(a) (Lp[a]) is thought to be the major carrier of oxidized phospholipids (OxPL). OxPL are believed to be a potent driver of inflammation and atherosclerosis. Olpasiran, a small interfering RNA, blocks Lp(a) production by inducing degradation of apolipoprotein(a) messenger RNA. Olpasiran's effects on OxPL and systemic markers of inflammation are not well described. Objective: To assess the effects of olpasiran on OxPL, high-sensitivity interleukin 6 (hs-IL-6), and hs-C-reactive protein (hs-CRP) in the OCEAN(a)-DOSE randomized clinical trial. Design, Setting, and Participants: OCEAN(a)-DOSE was an international, multicenter, placebo-controlled, phase 2, dose-finding randomized clinical trial conducted between July 2020 and November 2022. A total of 281 patients with atherosclerotic cardiovascular disease and Lp(a) levels greater than 150 nmol/L were included. Intervention: Participants were randomized to receive 1 of 4 active subcutaneous doses of olpasiran vs placebo: (1) 10 mg, administered every 12 weeks (Q12W); (2) 75 mg, Q12W; (3) 225 mg, Q12W; or (4) 225 mg, administered every 24 weeks (Q24W). OxPL on apolipoprotein B (OxPL-apoB), hs-CRP, and hs-IL-6 were assessed at baseline, week 36, and week 48 in 272 patients. Main Outcomes and Measures: The primary outcome was placebo-adjusted change in OxPL-apoB from baseline to week 36. Results: Among 272 participants, median (IQR) age was 62 years (56-69), and 86 participants (31.6%) were female. Baseline median (IQR) Lp(a) concentration was 260.3 nmol/L (198.1-352.4) and median (IQR) OxPL-apoB concentration was 26.5 nmol/L (19.7-33.9). The placebo-adjusted mean percentage change in OxPL-apoB from baseline to week 36 was -51.6% (95% CI, -64.9% to -38.2%) for the 10-mg Q12W dose, -89.7% (95% CI, -103.0% to -76.4%) for the 75-mg Q12W dose, -92.3% (95% CI, -105.6% to -78.9%) for the 225-mg Q12W dose, and -93.7% (95% CI, -107.1% to -80.3%) for the Q24W dose (P < .001 for all). These effects were maintained to week 48 (-50.8%, -100.2%, -104.7%, and -85.8%, respectively; P < .001 for all). There was a strong correlation between percentage reduction in Lp(a) and OxPL-apoB for patients treated with olpasiran (r = 0.79; P < .001). Olpasiran did not significantly impact hs-CRP or hs-IL-6 compared with placebo to weeks 36 or 48 (P > .05). Conclusion and Relevance: In the OCEAN(a)-DOSE multicenter randomized clinical trial, olpasiran led to a significant and sustained reduction in OxPL-apoB but no significant effects on hs-CRP or hs-IL-6.