Arrowhead Pharmaceuticals Secures First FDA Approval for FCS Treatment, Faces Competition from Ionis

Arrowhead Pharmaceuticals has achieved a significant milestone with the U.S. Food and Drug Administration (FDA) approval of Redemplo (plozasiran), marking the company's transition into a commercial-stage entity. The approval of this small interfering RNA (siRNA) therapy for familial chylomicronemia syndrome (FCS) represents a breakthrough in treatment options for this rare genetic disorder. However, Arrowhead faces immediate competition from Ionis Pharmaceuticals' Tryngolza in an increasingly contentious market.

FDA Approval and Clinical Efficacy

The FDA has approved Redemplo as an adjunct to diet for reducing triglycerides in adults with FCS. This rare condition affects approximately 6,500 people in the United States and is characterized by extremely high triglyceride levels, putting patients at risk of acute, recurrent, and potentially fatal pancreatitis.

In the pivotal Phase III PALISADE study, Redemplo demonstrated significant efficacy:

• A 25-mg dose led to a median 80% reduction in triglycerides from baseline, compared to a 17% reduction in the placebo group.
• The treatment group experienced fewer cases of acute pancreatitis than the placebo arm.

Christopher Anzalone, CEO of Arrowhead, stated, "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—one rooted in our unwavering commitment to delivering life-changing therapies to patients with serious diseases."

Market Competition and Legal Challenges

Arrowhead's entry into the FCS market puts it in direct competition with Ionis Pharmaceuticals, which received FDA approval for Tryngolza (olezarsen) in 2024. Both drugs target the reduction of the APOC-3 protein to lower triglyceride levels.

The competition has already spilled into the legal arena, with both companies filing lawsuits against each other in September 2025:

• Ionis alleges that Arrowhead infringed on its patented mRNA technology in developing Redemplo.
• Arrowhead counters that Ionis' patent is invalid and not infringed upon by Redemplo's commercialization.

Despite the legal challenges, Arrowhead plans to make Redemplo available in the U.S. by the end of the year, offering a patient assistance program called "Rely on Redemplo."

Pricing and Market Strategy

Arrowhead has announced a yearly wholesale acquisition cost of $60,000 for Redemplo, significantly lower than Tryngolza's reported price of $595,000 per year. This pricing strategy reflects Arrowhead's intention to maintain a consistent price across current and potential future indications, including severe hypertriglyceridemia.

Anzalone explained, "The large economic opportunity is in severe hypertriglyceridemia, so it's critical that we get the right price for that. If that means we give up some short-term revenue in FCS, we view that as an investment in the future."

Ionis reported Tryngolza sales of $32 million for the third quarter of 2025, with projected sales between $85 million and $95 million for the entire year.

As both companies navigate this competitive landscape, the FCS patient community stands to benefit from increased treatment options and potentially more accessible pricing. The ongoing legal disputes and market dynamics will likely shape the future of RNA-targeted therapies in rare genetic disorders.