Lepodisiran, an Extended-Duration Short Interfering RNA Targeting Lipoprotein(a)

Importance: Epidemiological and genetic data have implicated lipoprotein(a) as a potentially modifiable risk factor for atherosclerotic disease and aortic stenosis, but there are no approved pharmacological treatments. Objectives: To assess the safety, tolerability, pharmacokinetics, and effects of lepodisiran on lipoprotein(a) concentrations after single doses of the drug; lepodisiran is a short interfering RNA directed at hepatic synthesis of apolipoprotein(a), an essential component necessary for assembly of lipoprotein(a) particles. Design, Setting, and Participants: A single ascending-dose trial conducted at 5 clinical research sites in the US and Singapore that enrolled 48 adults without cardiovascular disease and with lipoprotein(a) serum concentrations of 75 nmol/L or greater (or ≥30 mg/dL) between November 18, 2020, and December 7, 2021; the last follow-up visit occurred on November 9, 2022. Interventions: Participants were randomized to receive placebo or a single dose of lepodisiran (4 mg, 12 mg, 32 mg, 96 mg, 304 mg, or 608 mg) administered subcutaneously. Main Outcomes and Measures: The primary outcome was the safety and tolerability of the single ascending doses of lepodisiran. The secondary outcomes included plasma levels of lepodisiran for 168 days after dose administration and changes in fasting lipoprotein(a) serum concentrations through a maximum follow-up of 336 days (48 weeks). Results: Of the 48 participants enrolled (mean age, 46.8 [SD, 11.6] years; 35% were women), 1 serious adverse event occurred. The plasma concentrations of lepodisiran reached peak levels within 10.5 hours and were undetectable by 48 hours. The median baseline lipoprotein(a) concentration was 111 nmol/L (IQR, 78 to 134 nmol/L) in the placebo group, 78 nmol/L (IQR, 50 to 152 nmol/L) in the 4 mg of lepodisiran group, 97 nmol/L (IQR, 86 to 107 nmol/L) in the 12-mg dose group, 120 nmol/L (IQR, 110 to 188 nmol/L) in the 32-mg dose group, 167 nmol/L (IQR, 124 to 189 nmol/L) in the 96-mg dose group, 96 nmol/L (IQR, 72 to 132 nmol/L) in the 304-mg dose group, and 130 nmol/L (IQR, 87 to 151 nmol/L) in the 608-mg dose group. The maximal median change in lipoprotein(a) concentration was -5% (IQR, -16% to 11%) in the placebo group, -41% (IQR, -47% to -20%) in the 4 mg of lepodisiran group, -59% (IQR, -66% to -53%) in the 12-mg dose group, -76% (IQR, -76% to -75%) in the 32-mg dose group, -90% (IQR, -94% to -85%) in the 96-mg dose group, -96% (IQR, -98% to -95%) in the 304-mg dose group, and -97% (IQR, -98% to -96%) in the 608-mg dose group. At day 337, the median change in lipoprotein(a) concentration was -94% (IQR, -94% to -85%) in the 608 mg of lepodisiran group. Conclusions and Relevance: In this phase 1 study of 48 participants with elevated lipoprotein(a) levels, lepodisiran was well tolerated and produced dose-dependent, long-duration reductions in serum lipoprotein(a) concentrations. The findings support further study of lepodisiran. Trial Registration: ClinicalTrials.gov Identifier: NCT04914546.