Arrowhead’s siRNA Therapeutic Plozasiran Achieves Approximately 80% Triglyceride Reduction in Severe Hypertriglyceridemia Patients

September 13, 2026

TCTMD USA

Overview

Arrowhead Pharmaceuticals’ siRNA therapeutic, plozasiran (Redemplo), demonstrated potent efficacy in SHASTA-3 and SHASTA-4 trials, reducing triglyceride levels by approximately 80% in patients with severe hypertriglyceridemia. Targeting apolipoprotein C-III (APOC3), plozasiran offers a potentially transformative treatment option for patients with insufficient response to existing therapies. This data underscores siRNA technology’s capability to deliver dramatic clinical benefits through gene-level intervention in cardiometabolic diseases, with a favorable safety profile suggesting a new standard of care.

In Depth

Key Findings

Plozasiran (trade name Redemplo), an siRNA therapeutic developed by Arrowhead Pharmaceuticals, has demonstrated remarkable efficacy in the SHASTA-3 and SHASTA-4 clinical trials targeting patients with severe hypertriglyceridemia. This investigational drug successfully reduced plasma triglyceride levels by approximately 80%, positioning it as a potentially groundbreaking treatment option for patients whose conditions are challenging to manage with current therapies. This achievement distinctly highlights the capability of siRNA technology to deliver profound clinical benefits in metabolic disorders through gene silencing.

Technical / Clinical Details

Plozasiran is a small interfering RNA (siRNA) designed to specifically target the production of apolipoprotein C-III (APOC3). APOC3 is a protein known to inhibit the metabolism of triglyceride-rich lipoproteins, and elevated levels of APOC3 are directly linked to severe hypertriglyceridemia. By mediating the degradation of APOC3 mRNA in the liver, plozasiran effectively lowers APOC3 production, thereby promoting triglyceride clearance. In both the SHASTA-3 (patients with severe hypertriglyceridemia) and SHASTA-4 (patients with familial chylomicronemia syndrome) trials, a significant, dose-dependent reduction in triglycerides was observed in the plozasiran treatment arms compared to placebo. The safety profile was favorable, with no serious adverse events beyond injection site reactions reported. This combination of high efficacy and good tolerability holds significant implications for long-term disease management.

Background & Context

Severe hypertriglyceridemia increases the risk of pancreatitis and is an independent risk factor for cardiovascular disease. Current therapeutic strategies include dietary modifications, fibrates, and omega-3 fatty acids, but many patients do not achieve adequate control or cannot sustain treatment due to side effects. Particularly for severe inherited forms, treatment options have been limited. siRNA-based therapeutics like plozasiran intervene at the genetic root of the disease, enabling sustained and potent triglyceride reduction that is difficult to achieve with conventional treatments. This success indicates that RNA interference (RNAi) medicines are establishing themselves as a next-generation modality capable of addressing unmet medical needs in both inherited and acquired diseases.

Strategic Significance & Outlook

The robust Phase II data for plozasiran strongly supports its progression into Phase III clinical trials, raising expectations for its eventual market approval. If approved, this drug could bring about a significant transformation in the treatment algorithm for severe hypertriglyceridemia, drastically reducing the risk of pancreatitis episodes and potentially contributing to the prevention of cardiovascular events. For Arrowhead Pharmaceuticals, this represents a crucial success story within its siRNA pipeline, likely invigorating the development of other RNAi therapeutics for various metabolic and liver diseases. Investors and clinicians are closely watching the potential impact of this drug on future lipid management guidelines.

Source: https://www.tctmd.com/news/apoc3-targeting-drug-has-benefits-severe-hypertriglyceridemia

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