Arrowhead Pharmaceuticals has hit the bullseye with its first successful commercial target, after the US Food and Drug Administration (FDA) approved the company’s small interfering RNA (siRNA) medicine for the treatment of familial chylomicronemia syndrome (FCS).
Redemplo (plozasiran) has been authorised as an adjunct to diet to reduce triglycerides in adults with FCS, a rare disease that disrupts the body’s ability to break down fats in the bloodstream.
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Patients with FCS have triglyceride levels that can be “ten to 100 times higher than normal”, according to Arrowhead. Acute pancreatitis is the most serious complication of the disease, according to the Endocrine Society.
Redemplo is an siRNA therapeutic designed to suppress the production of apoC-III, a protein produced in the liver that raises triglyceride levels by slowing their breakdown and clearance. The drug can be self-administered at home every three months.
The FDA based its decision on results from the Phase III PALISADE study (NCT05089084). The PALISADE study met its primary endpoint and all key secondary endpoints, including demonstrating significant reductions in triglycerides and APOC3 – the latter being the gene that encodes the apoC-III protein. Redemplo helped patients achieve an 80% reduction in triglycerides from baseline, compared to just 17% in the placebo group. The company’s siRNA also led to a reduced incidence of acute pancreatitis compared with placebo.
The approval marks a long-awaited turning point for Arrowhead, as it marks the first commercial product in the company’s portfolio since its founding in 1989. The company has historically been a busy licence partner with other drugmakers. For example, Novartis signed a licensing deal worth up to $2.2bn with Arrowhead in September 2025.
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By GlobalDataArrowhead’s CEO Christopher Anzalone said: “The FDA approval of Redemplo is a transformational milestone for Arrowhead. This approval, and subsequent launch, marks the beginning of a new chapter in our journey.”
On a conference call announcing the news, Anzalone said the biotech is already eyeing a fruitful commercial future with its RNAi platform.
“While Redemplo is our first approved product, it will not be our last,” Anzalone said.
“We’ve spent years building the TRiM platform to enable us to bring RNAi where it is needed. We are now able to address seven different cell types and have current clinical programmes in five of these. In the coming years, we expect to continue to create new medicines in these areas while we further expand our reach into even more cell types and disease states.”
Ionis competition comes into view
While Redemplo is the first approved product for Arrowhead, it is not the first specifically for FCS patients. In December 2024, Ionis Pharmaceuticals won FDA approval for Tryngolza (olezarsen), marking the first drug approved for the disease. Ionis’ medicine is an RNA-targeted ligand conjugated antisense drug that also targets the production of apoC-III. Arrowhead’s approval, almost a year later, means the company will now be in direct competition with Ionis in the FCS market. Tryngolza was also approved in Europe for FCS treatment in September 2025.
Ionis reported that Tryngolza generated Q3 2025 sales of $32m, with a total of between $85m and $95m forecast for the entire year. This target was up on a previous estimate of $75m-$80m based on stronger than anticipated growth.
On the conference call, executives at Arrowhead announced that Redemplo will launch with a yearly wholesale acquisition cost of $60,000, less than Tryngolza’s $595,000. Arrowhead aims to place its drug at the same price across any future indications it wins approval in.
