Abstract
Homozygous familial hypercholesterolemia (HoFH) is an ultra-rare, life-threatening, genetic condition characterized by markedly elevated levels of low-density lipoprotein cholesterol (LDL-C). Standard lipid-lowering therapies minimally reduce LDL-C in these patients, and lifelong serial apheresis is the mainstay of treatment. Evinacumab is a monoclonal antibody against angiopoietin-like protein 3 that lowers LDL-C levels via a novel LDL receptor-independent mechanism, and is US Food and Drug Administration approved for HoFH in the United States. We present a pediatric HoFH patient from Ontario who has been receiving evinacumab through special access from Health Canada. A 17-year-old boy was diagnosed with severe HoFH due to compound heterozygous LDLR pathogenic variants. Treatment has included a statin, ezetimibe, and LDL apheresis every 2 weeks, with minimal overall effect on LDL-C levels. He remains asymptomatic from a cardiovascular perspective. At age 16, evinacumab infused intravenously every 4 weeks was added to his treatment. After 12 months, his time-averaged LDL-C decreased by 53.4% from 8.75 mmol/L (338.4 mg/dL) to 4.08 mmol/L (157.8 mg/dL), despite reduced frequency of LDL apheresis from biweekly to monthly. He has experienced no adverse events. Overall, treatment has increased quality of life for him and his family. Evinacumab shows great promise for patients with HoFH, a difficult-to-treat and potentially life-threatening condition.