BACKGROUND: Homozygous familial hypercholesterolemia (HoFH) is characterized by early-onset atherosclerotic cardiovascular disease due to the high low-density lipoprotein cholesterol (LDL-C) burden. Patients with null-null low-density lipoprotein receptor () variants respond poorly, if at all, to statins and proprotein convertase subtilisin/kexin type 9 inhibitors, which act by upregulating expression. The 24-week double-blind treatment period (DBTP) of the phase 3 ELIPSE HoFH (Evinacumab Lipid Studies in Patients with Homozygous Familial hypercholesterolemia; NCT03399786) study demonstrated significant LDL-C reductions in patients with HoFH; LDL-C reductions were also observed in those with null-null mutations. OBJECTIVES: The purpose of this study was to evaluate longer-term efficacy and safety of evinacumab in patients with HoFH from the ELIPSE HoFH study. METHODS: Patients with HoFH on stable lipid-lowering therapies (LLTs) ± lipoprotein apheresis and screening LDL-C ≥70 mg/dL who completed the DBTP entered the 24-week open-label treatment period (OLTP) and received intravenous evinacumab 15 mg/kg every 4 weeks. OLTP results were summarized descriptively. RESULTS: A total of 64 patients completed the DBTP and received open-label evinacumab. Despite multiple LLTs, the mean baseline LDL-C at DBTP entry was 250.5 ± 162.3 mg/dL. From baseline to week 48 (end of OLTP), evinacumab reduced mean LDL-C by 46.3% (mean reduction, 134.3 ± 117.3 mg/dL), with similar mean LDL-C reductions for patients with null-null (47.2%) and non-null variants (45.9%). Adverse events occurred in 47 (73.4%) patients; 4 (6.3%) patients experienced adverse events considered evinacumab-related (drug hypersensitivity, infusion-related reaction and asthenia, generalized pruritis, and muscle spasms). CONCLUSIONS: In patients with HoFH, evinacumab demonstrated substantial and sustained LDL-C reduction regardless of LDLR function, and was generally well tolerated.