Arrowhead Pharmaceuticals has secured a major regulatory milestone with the U.S. Food and Drug Administration’s approval of REDEMPLO (plozasiran), marking the company’s first commercialized medicine and the first FDA-approved small interfering RNA (siRNA) therapy for adults living with familial chylomicronemia syndrome (FCS). The therapy, authorized as an adjunct to diet, is designed to significantly reduce triglyceride levels in patients with this ultra-rare and severe metabolic disorder.
FCS affects an estimated 6,500 people in the United States and is characterized by dangerously elevated triglyceride levels—often 10 to 100 times above normal—which dramatically increase the risk of recurrent and potentially fatal bouts of acute pancreatitis. With no curative treatments and limited existing options, the FDA’s decision represents a breakthrough moment for the FCS community.
REDEMPLO can be self-administered at home via a simple subcutaneous injection once every three months. The medicine is powered by Arrowhead’s proprietary Targeted RNAi Molecule (TRiM™) platform, which enables precise gene silencing. The approval also positions Arrowhead as a commercial-stage company for the first time and further validates the company’s RNAi technology, which has the potential to target multiple cell types and silence more than one gene simultaneously.
Arrowhead President and CEO Christopher Anzalone called the approval “a transformational milestone,” emphasizing both the scientific achievement and the impact for patients long underserved by existing therapies. He noted that the TRiM™ platform, now validated in an FDA-approved product, expands the company’s capacity to address a broader spectrum of serious diseases.
The FDA’s decision was supported by compelling results from the Phase 3 PALISADE trial, a randomized, double-blind, placebo-controlled study evaluating plozasiran in adults with genetically confirmed or clinically diagnosed FCS. The trial met its primary and all key secondary endpoints, demonstrating deep and durable triglyceride reductions. Patients receiving 25 mg of REDEMPLO achieved a median 80% reduction from baseline triglyceride levels, compared with a 17% decrease in the pooled placebo arm. The REDEMPLO group also experienced fewer episodes of acute pancreatitis, a major clinical concern in FCS management. Safety data showed common adverse reactions included hyperglycemia, nausea, headache, and injection-site reactions, with no contraindications or warnings listed in the approved label.
Leaders from the FCS Foundation hailed the approval as a long-awaited turning point for a community that has historically struggled to access effective therapies. Lindsey Sutton Bryan, the organization’s co-founder and co-president, emphasized the significance of a treatment shaped with direct patient input, noting that plozasiran “offers real hope for a better future.”
Arrowhead is also introducing Rely On REDEMPLO, a comprehensive patient-support program offering resources, guidance, and financial-assistance options to help ensure broad access. The company plans to make REDEMPLO available in the U.S. before year-end.
The FDA previously granted the therapy Breakthrough Therapy, Fast Track, and Orphan Drug Designations, while the European Medicines Agency awarded Orphan Medicinal Product Designation—reinforcing global recognition of the therapy’s potential.
With this first approval, Arrowhead enters a new era, strengthening its commercial presence and expanding its pipeline opportunities built on its maturing TRiM™ RNAi platform.