Plozasiran, an RNA Interference Agent Targeting APOC3, for Mixed Hyperlipidemia

BACKGROUND Persons with mixed hyperlipidemia are at risk for atherosclerotic cardiovascular disease due to an elevated non–high-density lipoprotein (HDL) cholesterol level, which is driven by remnant cholesterol in triglyceride-rich lipoproteins. The metabolism and clearance of triglyceride-rich lipoproteins are down-regulated through apolipoprotein C3 (APOC3)–mediated inhibition of lipoprotein lipase. METHODS We carried out a 48-week, phase 2b, double-blind, randomized, placebo-controlled trial evaluating the safety and efficacy of plozasiran, a hepatocyte-targeted APOC3 small interfering RNA, in patients with mixed hyperlipidemia (i.e., a triglyceride level of 150 to 499 mg per deciliter and either a low-density lipoprotein [LDL] cholesterol level of ≥70 mg per deciliter or a non-HDL cholesterol level of ≥100 mg per deciliter). The participants were assigned in a 3:1 ratio to receive plozasiran or placebo within each of four cohorts. In the first three cohorts, the participants received a subcutaneous injection of plozasiran (10 mg, 25 mg, or 50 mg) or placebo on day 1 and at week 12 (quarterly doses). In the fourth cohort, participants received 50 mg of plozasiran or placebo on day 1 and at week 24 (half-yearly dose). The data from the participants who received placebo were pooled. The primary end point was the percent change in fasting triglyceride level at week 24. RESULTS A total of 353 participants underwent randomization. At week 24, significant reductions in the fasting triglyceride level were observed with plozasiran, with differences, as compared with placebo, in the least-squares mean percent change from baseline of −49.8 percentage points (95% confidence interval [CI], −59.0 to −40.6) with the 10-mg-quarterly dose, −56.0 percentage points (95% CI, −65.1 to −46.8) with the 25-mg-quarterly dose, −62.4 percentage points (95% CI, −71.5 to −53.2) with the 50-mg-quarterly dose, and −44.2 percentage points (95% CI, −53.4 to −35.0) with the 50-mg-half-yearly dose (P<0.001 for all comparisons). Worsening glycemic control was observed in 10% of the participants receiving placebo, 12% of those receiving the 10-mg-quarterly dose, 7% of those receiving the 25-mg-quarterly dose, 20% of those receiving the 50-mg-quarterly dose, and 21% of those receiving the 50-mg-half-yearly dose. CONCLUSIONS In this randomized, controlled trial involving participants with mixed hyperlipidemia, plozasiran, as compared with placebo, significantly reduced triglyceride levels at 24 weeks. A clinical outcomes trial is warranted.