Longer-Term Efficacy and Safety of Evinacumab in Patients With Refractory Hypercholesterolemia.

Importance: Patients with refractory hypercholesterolemia who do not achieve their guideline-defined low-density lipoprotein cholesterol (LDL-C) thresholds despite treatment with maximally tolerated combinations of lipid-lowering therapies (LLTs) have an increased risk of atherosclerotic cardiovascular disease (ASCVD).

Objective: To evaluate longer-term efficacy and safety of evinacumab in patients with refractory hypercholesterolemia.

Design, Setting, And Participants: This randomized clinical trial included a 2-week screening period followed by a 16-week double-blind treatment period (DBTP) for subcutaneous regimens (evinacumab, 450 mg, once weekly [QW]; evinacumab, 300 mg, QW; evinacumab, 300 mg, every 2 weeks; or placebo QW) or a 24-week DBTP for intravenous regimens (evinacumab, 15 mg/kg, every 4 weeks [Q4W]; evinacumab, 5 mg/kg, Q4W; or placebo Q4W); a 48-week open-label treatment period (OLTP) for intravenous treatment only; and a 24-week follow-up period. Patients from 85 sites across 20 countries were recruited for the study; patients with primary hypercholesterolemia (defined as heterozygous familial hypercholesterolemia or established clinical ASCVD without familial hypercholesterolemia) who entered the 48-week OLTP were included. In addition, the patients' hypercholesterolemia was refractory to maximally tolerated LLTs.

Interventions: All patients entering the OLTP received evinacumab, 15 mg/kg, intravenously Q4W.

Main Outcomes And Measures: Efficacy outcomes included change in LDL-C level and other lipid/lipoprotein parameters from baseline to week 72 (end of the OLTP). Safety outcomes included assessment of treatment-emergent adverse events (TEAEs).

Results: A total of 96 patients (mean [SD] age, 54.4 [11.3] years; 52 female [54.2%]) entered the OLTP, of whom 88 (91.7%) completed the OLTP. Mean (SD) baseline LDL-C level was 145.9 (55.2) mg/dL. At week 72, evinacumab, 15 mg/kg, reduced mean (SD) LDL-C level from baseline by 45.5% (28.7%) in the overall cohort. Evinacumab, 15 mg/kg, reduced mean (SD) apolipoprotein B (38.0% [22.1%]), non-high density lipoprotein cholesterol (48.4% [23.2%]), total cholesterol (42.6% [17.5%]), and median (IQR) fasting triglyceride (57.2% [65.4%-44.4%]) levels at week 72 from baseline in the overall cohort. TEAEs occurred in 78 of 96 patients (81.3%). Serious TEAEs occurred in 9 of 96 patients (9.4%); all were considered unrelated to study treatment.

Conclusions And Relevance: In patients with refractory hypercholesterolemia, evinacumab provided sustained reductions in LDL-C level and was generally well tolerated.

Trial Registration: ClinicalTrials.gov Identifier: NCT03175367.