The Food and Drug Administration has approved Redemplo (plozasiran), marking a transformational milestone for Arrowhead Pharmaceuticals as the company's first commercial drug after more than two decades of development. The siRNA therapy was cleared Tuesday for treating familial chylomicronemia syndrome (FCS) in adults as an adjunct to diet, targeting a rare genetic condition that affects approximately 6,500 people in the United States.
Breakthrough for RNAi Technology
Redemplo represents the first FDA-approved medicine utilizing Arrowhead's proprietary Targeted RNAi Molecule (TRiM) platform, designed to suppress apoC-III protein production in the liver. The therapy addresses FCS, a severe condition characterized by triglyceride levels 10 to 100 times higher than normal, leading to substantially increased risk of acute, recurrent, and potentially fatal pancreatitis.
"The FDA approval of Redemplo is a transformational milestone for Arrowhead," said Christopher Anzalone, President and CEO. "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."
The approval positions Arrowhead as a commercial-stage company after years of pipeline development. Unlike competitor Alnylam Pharmaceuticals, which has several approved products and a $60 billion market value, Arrowhead has been worth only a fraction of that valuation and suffered a net loss of approximately $600 million last year.
Clinical Trial Results Drive Approval
The FDA approval was supported by data from the Phase 3 PALISADE study, a randomized, double-blind, placebo-controlled trial involving 75 subjects across 39 sites in 18 countries. The study met its primary endpoint and all multiplicity-controlled key secondary endpoints.
In the trial, 25 mg Redemplo achieved a median triglyceride reduction of 80% from baseline compared to 17% in the pooled placebo group at month 10. The therapy also demonstrated a lower numerical incidence of acute pancreatitis compared to placebo. The most common adverse reactions included hyperglycemia, headache, nausea, and injection site reactions, with no contraindications, warnings, or precautions in the approved package insert.
Competitive Landscape and Pricing Strategy
Arrowhead enters a market where Ionis Pharmaceuticals' Tryngolza launched last year as the first approved FCS treatment, generating $57 million in sales over the first nine months of 2025 with a yearly list price of $595,000. However, analysts suggest Redemplo may offer advantages in efficacy, safety, and convenience.
Comparative data across trials shows Redemplo demonstrated approximately 70% triglyceride reduction versus 59% for Tryngolza. Additionally, Ionis' drug carries a safety warning for hypersensitivity reactions—a side effect associated with treatment discontinuations that wasn't observed in Redemplo trials.
Arrowhead announced Redemplo will launch with a yearly wholesale acquisition cost of $60,000, substantially less than Tryngolza. CEO Anzalone explained the pricing strategy focuses on future opportunities in severe hypertriglyceridemia, a more common condition. "The large economic opportunity is in severe hypertriglyceridemia, so it's critical that we get the right price for that," he said. "If that means we give up some short term revenue in FCS, we view that as an investment in the future."
Patent Disputes and Future Development
The two companies are currently engaged in patent litigation, with dueling lawsuits filed in September. Ionis accused Arrowhead of patent infringement, while Arrowhead seeks court declaration that the patent is either invalid or not infringed upon.
Beyond FCS, both companies are developing their respective medicines for severe hypertriglyceridemia. Ionis' drug has already succeeded in late-stage trials, while Arrowhead could release study results next year according to federal databases. Previous results suggest Redemplo might "match [or] exceed" Tryngolza's results in this larger indication.
Technology Platform and Commercial Launch
Redemplo utilizes RNA interference to silence genes before they produce troublesome proteins, specifically targeting apoC-III which increases triglyceride levels by inhibiting breakdown of triglyceride-rich lipoproteins. The therapy is self-administered via subcutaneous injection once every three months, offering convenience advantages over existing treatments.
The drug received Breakthrough Therapy Designation, Fast Track Designation, and Orphan Drug Designation from the FDA, along with Orphan Medicinal Product Designation from the European Medicines Agency. Arrowhead plans to make Redemplo available in the U.S. before year-end and is launching "Rely On REDEMPLO," a patient support program providing treatment journey assistance and financial support options for eligible patients.
Lindsey Sutton Bryan, co-founder and co-president of the FCS Foundation, emphasized the approval's significance: "Today's approval marks a pivotal moment for people living with familial chylomicronemia syndrome and the physicians who support them. Because FCS symptoms are mostly invisible, this community historically has been often overlooked and misunderstood, making their journey to effective treatment especially difficult."
