Arrowhead’s Plozasiran Achieves Up to 81% Triglyceride Reduction in Severe Hypertriglyceridemia Phase 3, Pressuring Ionis

July 26, 2026

Fierce Biotech USA

Overview

Arrowhead Pharmaceuticals has reported robust Phase 3 SHASTA-3 and SHASTA-4 trial data for its siRNA therapeutic, plozasiran, in patients with severe hypertriglyceridemia (sHTG), putting pressure on competitor Ionis Pharmaceuticals. Plozasiran achieved dramatic triglyceride reductions of 79% and 81%, respectively, and significantly reduced the risk of acute pancreatitis events. Already approved as Redemplo for familial chylomicronemia syndrome (FCS), Arrowhead plans a supplemental New Drug Application (sNDA) for sHTG by late 2026, aiming to capture a significant share of the large cardiovascular market.

In Depth

Key Findings

Arrowhead Pharmaceuticals has announced exceptionally positive data from its Phase 3 SHASTA-3 and SHASTA-4 trials for plozasiran, an siRNA therapeutic designed for patients with severe hypertriglyceridemia (sHTG). Plozasiran demonstrated remarkable triglyceride reductions of 79% and 81% in the respective studies, coupled with a significant reduction in acute pancreatitis events. This strong performance places considerable competitive pressure on companies like Ionis Pharmaceuticals, which are developing similar therapies.

Technical and Clinical Details

Plozasiran is a small interfering RNA (siRNA) therapeutic engineered to target genes in the liver involved in triglyceride metabolism. The mechanism of action for siRNAs involves degrading specific messenger RNA (mRNA) molecules, thereby inhibiting the expression of target proteins. Plozasiran is specifically designed with N-acetylgalactosamine (GalNAc) conjugation to ensure highly efficient and sustained delivery to hepatocytes, allowing for potent and long-lasting effects.

The Phase 3 SHASTA-3 and SHASTA-4 trials reported clinically significant results, with plozasiran leading to a 79% and 81% reduction in triglyceride levels compared to placebo. Hypertriglyceridemia is not only a significant risk factor for cardiovascular disease but, in its severe forms, can also lead to acute pancreatitis. The substantial reduction in acute pancreatitis events observed in these trials following plozasiran administration holds immense importance for improving patient outcomes.

Notably, plozasiran has already received approval as ‘Redemplo’ for familial chylomicronemia syndrome (FCS), a rare genetic disorder characterized by extremely high triglyceride levels. Building on the success of these sHTG Phase 3 trials, Arrowhead Pharmaceuticals plans to submit a supplemental New Drug Application (sNDA) to the U.S. FDA for an expanded indication in sHTG by the end of 2026.

Background and Industry Context

Hypertriglyceridemia is a prevalent lipid disorder globally, representing a critical risk factor for the development of cardiovascular disease. Existing treatment options have limitations, and there is a particular unmet need for effective therapies in severe cases. The market for lipid-lowering RNA-based therapeutics is highly competitive, with multiple companies, including Ionis Pharmaceuticals, actively developing drugs. Plozasiran’s robust data suggests Arrowhead Pharmaceuticals is well-positioned to gain a significant share in this evolving landscape.

Strategic Significance and Outlook

The potential approval of plozasiran for sHTG will allow Arrowhead Pharmaceuticals to expand its market reach from the rare disease FCS population into the much larger and broader hypertriglyceridemia market. This expansion is expected to substantially increase Arrowhead’s revenue opportunities and bring a transformative therapeutic option to a larger number of patients. Furthermore, this success reiterates the significant potential of siRNA technology in managing chronic diseases and is likely to accelerate the development of other RNA-based therapies for various cardiometabolic conditions, solidifying Arrowhead’s position as a leader in this field.

Source: https://www.biospace.com/drug-development/arrowhead-puts-pressure-on-ionis-with-positive-data-for-triglyceride-lowering-drug

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