The European Medicines Agency (EMA) has recommended granting marketing authorization for Redemplo (plozasiran, Arrowhead Pharmaceuticals) for treating adults with familial chylomicronemia syndrome (FCS). 

FCS is a rare inherited disease that prevents the body from breaking down lipids, which leads to very high levels of triglycerides in the blood and excess accumulation of fat in different parts of the body. Symptoms include severe abdominal pain, potentially fatal attacks of acute pancreatitis, hepatosplenomegaly, diabetes, lack of concentration, memory loss, and xanthomas.

Treatment typically includes a highly restrictive low-fat diet to reduce intake of triglycerides and chylomicron production. Pharmaceutical options exist as well, such as antisense oligonucleotide Tryngolza (olezarsen, Ionis Pharmaceuticals), which was approved by the European Commission for the condition in September 2025. Between 1 in 100,000 and 1 in 1,000,000 people in Europe are thought to have FCS. 

The active ingredient in Redemplo is plozasiran, a small interfering RNA conjugated with N-acetylgalactosamine. It works by selectively degrading messenger RNA for apolipoprotein C3 (APOC3) in hepatocytes, which reduces levels of hepatic and serum APOC3 protein and enhances lipoprotein lipase activity and hepatocyte uptake of triglyceride-rich lipoprotein remnants. These processes ultimately reduce levels of triglycerides in the blood as well as fat accumulation in the body, which may reduce risk of pancreatitis. 

The EMA’s decision comes after a phase 3 trial involving 75 patients with persistent chylomicronemia with or without a genetic diagnosis. In the trial, patients received subcutaneous plozasiran at 25 mg or 50 mg or a placebo every 3 months for 12 months while maintaining a controlled diet. 

At 10 months, those taking plozasiran at 25 mg saw an 80% decline in fasting triglycerides, while the 50 mg group saw a 78% decline. By comparison, triglyceride levels declined by 17% in the placebo group. The effects were observed in patients regardless of genetic diagnosis and remained for at least 18 months. Those taking plozasiran also had an 83% lower risk of acute pancreatitis. 

Both plozasiran and placebo groups had a similar risk of adverse events, the most common of which were abdominal pain, nasopharyngitis, headache, and nausea. Severe and serious adverse events, however, were less common among those taking plozasiran than placebo. Some patients taking plozasiran who had prediabetes or diabetes at the start of the study developed hyperglycemia during the study period. 

Redemplo will be available as a 25 mg solution for injection in prefilled syringes. It should be taken as an adjunct to diet. 

Detailed recommendations for using Redemplo will be published in the summary of product characteristics, which will be available on the EMA website in all official European Union languages when the European Commission has granted the drug marketing authorization.

Annie Lennon is a medical journalist. Her writing appears on Medscape, WebMD, and Medical News Today, among other outlets.