New England Journal of Medicine November 05, 2026

Plozasiran for Severe Hypertriglyceridemia and Risk of Pancreatitis

Gerald F. Watts, Christie M. Ballantyne, Agustin Blanco Echevarria, et al.

Bottom Line

In two phase 3 trials (SHASTA-3 and SHASTA-4), the RNA interference therapeutic plozasiran significantly reduced fasting triglyceride levels and lowered the risk of acute pancreatitis compared with placebo in adults with severe hypertriglyceridemia.

Key Findings

1. At month 12, median fasting triglyceride levels were reduced from baseline by 79% and 81% in the plozasiran groups of the two trials, yielding placebo-adjusted reductions of -45 and -47 percentage points.

2. A triglyceride level of less than 500 mg per deciliter at 12 months was achieved by 91% and 93% of patients in the plozasiran groups, compared to 51% and 50% in the placebo groups (P<0.001).

3. The rate of acute pancreatitis was significantly lower with plozasiran (1 per 100 patient-years) than with placebo (5 per 100 patient-years), corresponding to a rate ratio of 0.22 (P=0.008).

4. Adverse events during treatment occurred at identical rates (73%) in both the pooled plozasiran and placebo groups.

Study Design

Design

RCT

Double-Blind

Sample

757

Patients

Duration

12 mo

Median

Setting

Multicenter, global

Population Adults with severe hypertriglyceridemia

Intervention Plozasiran (25 mg) administered at baseline and at months 3, 6, and 9

Comparator Placebo administered at baseline and at months 3, 6, and 9

Outcome Percent change in the fasting plasma triglyceride level from baseline to month 12

Study Limitations

• The 12-month follow-up period limits the assessment of long-term safety, durability of efficacy, and major adverse cardiovascular event reduction.

• The trial demographic was predominantly White and male, which may limit the generalizability of the findings to broader and more diverse demographic populations.

Clinical Significance

Plozasiran provides a highly targeted, quarterly-dosed RNA-interference therapy that effectively lowers extreme triglyceride levels in patients with severe hypertriglyceridemia. The significant reduction in acute pancreatitis rates demonstrates robust clinical benefit in a high-risk population where conventional oral lipid-lowering therapies frequently fall short.

Historical Context

Severe hypertriglyceridemia poses a profound and sometimes recurrent risk for acute pancreatitis. While statins, fibrates, and omega-3 fatty acids represent standard care, they often provide insufficient triglyceride clearance for severe cases. Plozasiran, a small interfering RNA targeting hepatic APOC3 production, previously demonstrated robust efficacy in familial chylomicronemia syndrome. The SHASTA-3 and SHASTA-4 trials mark a critical expansion of APOC3-targeted therapeutics, validating their efficacy in the broader non-monogenic severe hypertriglyceridemia population.

Guided Discussion

High-yield insights from every perspective

Med Student

Medical Student

Plozasiran is an RNA interference (RNAi) therapeutic. Based on the pathophysiology of severe hypertriglyceridemia, what specific target does plozasiran silence, and how does the reduction of this target lower both triglyceride levels and the subsequent risk of acute pancreatitis?

Key Response

Plozasiran targets apolipoprotein C-III (APOC3) mRNA in the liver. APOC3 normally inhibits lipoprotein lipase (LPL) and hepatic uptake of triglyceride-rich lipoproteins. Silencing APOC3 enhances LPL activity and the clearance of chylomicrons and VLDL, thereby drastically lowering triglycerides. High triglycerides cause pancreatitis via breakdown into toxic free fatty acids by pancreatic lipase, causing lipotoxicity and ischemia; lowering them removes this trigger.

Resident

When managing a patient with severe hypertriglyceridemia and a history of acute pancreatitis, how would the addition of an RNAi agent like plozasiran alter your step-wise management compared to the traditional use of fibrates, omega-3 fatty acids, and lifestyle modifications?

Key Response

Traditional therapies often fail to achieve sufficient triglyceride reduction in severe genetic or refractory hypertriglyceridemia to prevent pancreatitis. Residents should recognize that while lifestyle and fibrates remain first-line, RNAi therapies like plozasiran offer a definitive pharmacological escalation for patients who remain at high risk for recurrent pancreatitis despite standard care.

Fellow

Given that plozasiran profoundly lowers triglycerides by targeting APOC3, how might its efficacy and lipid profile effects differ between patients with familial chylomicronemia syndrome (FCS) who lack functional lipoprotein lipase (LPL) versus those with multifactorial severe hypertriglyceridemia?

Key Response

APOC3 inhibition works through both LPL-dependent and LPL-independent pathways, such as hepatic receptor-mediated clearance of remnants. Fellows must understand that unlike traditional therapies which heavily rely on LPL, APOC3 inhibitors can still effectively lower triglycerides in FCS patients with defective LPL, highlighting the importance of LPL-independent hepatic clearance mechanisms.

Attending

With the SHASTA-3 and SHASTA-4 trials demonstrating a significant reduction in acute pancreatitis events, how should we weigh the 'number needed to treat' (NNT) and cost-effectiveness of using a novel RNAi therapeutic prophylactically, considering the high morbidity and healthcare costs of recurrent pancreatitis?

Key Response

Attendings must weigh the high upfront cost of novel RNAi therapies against the substantial downstream costs of recurrent acute pancreatitis, including ICU admissions and chronic pancreatitis. The practice-changing implication is shifting the paradigm of severe hypertriglyceridemia management from merely 'treating a number' to 'secondary prevention of a catastrophic abdominal event'.

Scholarly Review

Critical appraisal through the lens of expert reviewers and guideline development

PhD

The SHASTA trials assessed both fasting triglyceride reductions as a continuous biomarker and the incidence of acute pancreatitis as a discrete clinical event. What are the methodological challenges in adequately powering a trial for a secondary clinical endpoint like acute pancreatitis, and how might competing risks or dropout rates affect outcome validity?

Key Response

Acute pancreatitis is episodic and less frequent than cardiovascular events, making it difficult to power as a primary endpoint. Researchers must critique how the trial utilized event-driven follow-up, whether the duration was sufficient to capture enough pancreatitis events, and if statistical models like negative binomial regression adequately accounted for recurrent events in the same individuals.

Journal Editor

As a peer reviewer, how would you critically evaluate the independent adjudication process for acute pancreatitis events in the SHASTA trials, particularly regarding the potential for detection bias or functional unblinding due to profound changes in routine lipid panels visible to local investigators?

Key Response

A tough reviewer would flag that local investigators might guess the treatment assignment due to the dramatic drop in triglyceride levels and visually reduced lipemia in blood draws. This functional unblinding could lead to a lower threshold for investigating abdominal pain in the placebo group, requiring a rigorous, blinded, centralized clinical events committee to adjudicate events strictly using Atlanta criteria.

Guideline Committee

Current ACC/AHA guidelines emphasize statins, fibrates, and omega-3 fatty acids for severe hypertriglyceridemia to prevent pancreatitis, though evidence for fibrates reducing pancreatitis is historically weak. Based on the SHASTA trials, what specific level of evidence does plozasiran achieve, and how should it be positioned in the treatment algorithm?

Key Response

Current 2018 AHA/ACC guidelines give a Class IIa recommendation for treating severe hypertriglyceridemia to prevent pancreatitis, largely based on older, less robust data. Plozasiran provides high-quality, randomized trial evidence (Level A) demonstrating a direct reduction in pancreatitis risk. Committees must decide whether to recommend plozasiran as a second-line agent after fibrate failure or as a first-line agent for patients with a documented history of recurrent pancreatitis.

Clinical Landscape

Noteworthy Related Trials

2018

REDUCE-IT Trial

n = 8,179 · NEJM

Tested

Icosapent ethyl 4g daily

Population

Statin-treated patients with elevated triglycerides and cardiovascular risk

Comparator

Placebo (mineral oil)

Endpoint

Composite of cardiovascular death, nonfatal MI, nonfatal stroke, coronary revascularization, or unstable angina

Key result: Icosapent ethyl significantly reduced the risk of the primary composite ischemic endpoint by 25 percent.

2019

APPROACH Trial

n = 66 · NEJM

Tested

Volanesorsen 300mg subcutaneously weekly

Population

Patients with familial chylomicronemia syndrome

Comparator

Placebo

Endpoint

Percentage change in fasting triglycerides at 3 months

Key result: Volanesorsen reduced fasting triglyceride levels by 77 percent compared to an 18 percent increase in the placebo group.

2022

PROMINENT Trial

n = 10,497 · NEJM

Tested

Pemafibrate 0.2mg twice daily

Population

Patients with type 2 diabetes, mild-to-moderate hypertriglyceridemia, and low HDL cholesterol

Comparator

Placebo

Endpoint

Composite of nonfatal MI, ischemic stroke, coronary revascularization, or cardiovascular death

Key result: Despite reducing triglyceride levels by 26.2 percent, pemafibrate did not lower the risk of cardiovascular events compared to placebo.

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