The US Food and Drug Administration has approved Ionis Pharmaceuticals’ drug Tryngolza (olezarsen), as an adjunct to a low-fat diet, to treat familial chylomicronemia syndrome (FCS). The RNA-targeted medicine is the first approved for this group of rare genetic disorders, in which the body cannot break down chylomicrons (lipoprotein particles, made up of about 90% triglycerides).

In the United States, the disease affects approximately 3,000 people. FCS leads to dangerously high fasting triglycerides in plasma (>500 mg dl–1) because of the genetically absent capacity to break down lipids, resulting in heightened risk of acute pancreatitis. Targeted reduction of apolipoprotein C-3 (APOC3), a protein produced in the liver and a key player in triglyceride metabolism, can correct this biochemical disturbance. Tryngolza is an N-acetylgalactosamine-conjugated antisense oligonucleotide targeted to hepatic APOC3 mRNA. By inhibiting APOC3 protein production, the treatment improves the body’s ability to break down fats, lowers circulating triglyceride-rich lipoproteins and improves atherogenic risk.