Long-term safety, tolerability, and efficacy of evolocumab in patients with heterozygous familial hypercholesterolemia

Background: Evolocumab, a fully human monoclonal antibody against proprotein convertase subtilisin/kexin type 9, is safe and effective when dosed biweekly (Q2W) or monthly (QM) in patients with heterozygous familial hypercholesterolemia (HeFH) as demonstrated in two 12-week trials: Reduction of LDL-C With PCSK9 Inhibition in Heterozygous Familial Hypercholesterolemia Disorder (RUTHERFORD; phase 2) and RUTHERFORD-2 (phase 3).

Objective: The objective of the study was to evaluate long-term efficacy, safety, and tolerability of evolocumab during open-label extension trials.

Methods: Patients completing parent trials were re-randomized 2:1 to evolocumab plus standard of care (SOC) or SOC alone for 52 weeks (Open-Label Study of Long-term Evaluation Against LDL-C [OSLER-1]) or 48 weeks (OSLER-2). Evolocumab dosing was 420 mg QM (OSLER-1) and 140 mg Q2W or 420 mg QM (OSLER-2). A pooled analysis of OSLER data was performed from this subset of HeFH patients.

Results: Four hundred forty HeFH patients from RUTHERFORD (n = 147) and RUTHERFORD-2 (n = 293) (mean [standard deviation] age 51 [12] years, 58% male, 90% White) were randomized to evolocumab plus SOC (n = 289) or SOC (n = 151). The 48-week period was completed by 425 patients (96.6%). Eight patients discontinued evolocumab plus SOC (2.8%) and 7 discontinued SOC (4.6%). Compared to parent study baseline, patients receiving evolocumab plus SOC experienced a mean 53.6% reduction in low-density lipoprotein cholesterol after 48 weeks. No patient experienced an adverse event leading to permanent evolocumab discontinuation during the 1-year SOC-controlled period. Serious adverse event rates were similar between groups (evolocumab plus SOC, 7.3%; SOC, 8.6%).

Conclusion: Continued use of evolocumab added to SOC in patients with HeFH yields persistent and marked low-density lipoprotein cholesterol reductions during 48 weeks of follow-up. Long-term dosing of evolocumab with SOC was safe and well tolerated.