New England Journal of Medicine November 24, 2022

Triglyceride Lowering with Pemafibrate to Reduce Cardiovascular Risk

Aruna Das Pradhan, Robert J. Glynn, Jean-Charles Fruchart, Jean G. MacFadyen, Elaine S. Zaharris, Brendan M. Everett, et al.

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Bottom Line

In statin-treated patients with type 2 diabetes, mild-to-moderate hypertriglyceridemia, and low HDL cholesterol, the selective PPARα modulator pemafibrate successfully lowered triglycerides but failed to reduce the incidence of cardiovascular events compared to placebo.

Key Findings

1. At 4 months, pemafibrate lowered median fasting triglycerides by 26.2% relative to placebo, with accompanying reductions in VLDL cholesterol (-25.8%), remnant cholesterol (-25.6%), and apolipoprotein C-III (-27.6%). [3.1.2]

2. Despite the reduction in triglycerides, pemafibrate therapy was associated with a 4.8% increase in apolipoprotein B and an increase in LDL cholesterol.

3. Over a median follow-up of 3.4 years, the primary efficacy endpoint occurred in 572 patients in the pemafibrate group and 560 in the placebo group (Hazard Ratio 1.03; 95% CI, 0.91 to 1.15; P=0.67), indicating no cardiovascular benefit.

4. Safety analysis revealed that pemafibrate was associated with a higher incidence of adverse renal events and venous thromboembolism, though it did show a reduced incidence of nonalcoholic fatty liver disease.

Study Design

Design

RCT

Double-Blind

Sample

10,497

Patients

Duration

3.4 yr

Median

Setting

24 countries

Population Patients with type 2 diabetes, mild-to-moderate hypertriglyceridemia (fasting triglycerides 200 to 499 mg/dL), and HDL cholesterol levels of 40 mg/dL or lower, who were on guideline-directed lipid-lowering therapy or statin intolerant.

Intervention Pemafibrate 0.2 mg tablets administered orally twice daily.

Comparator Matching placebo tablets administered orally twice daily.

Outcome A composite of nonfatal myocardial infarction, ischemic stroke, coronary revascularization, or cardiovascular death.

Study Limitations

• The intervention inadvertently increased apolipoprotein B and LDL cholesterol, which may have mechanistically counteracted any cardiovascular benefits of lowering triglycerides.

• The study population was already well-treated with guideline-directed statin therapy (median baseline LDL-C was 78 mg/dL), limiting the residual risk that could be modified by further lipid interventions.

• The 3.4-year median follow-up time may have been relatively short to detect long-term macrovascular event divergence in a population with well-controlled baseline LDL-C.

Clinical Significance

The PROMINENT trial effectively closes the door on the hypothesis that fibrate-like PPARα modulation reduces cardiovascular risk in statin-treated patients with diabetic dyslipidemia. It highlights the critical principle that lowering triglycerides does not automatically translate to atherothrombotic risk reduction if the intervention fails to lower, or inversely raises, atherogenic particle number (Apolipoprotein B). Consequently, pemafibrate and other fibrates are not recommended for the purpose of reducing atherosclerotic cardiovascular disease events in this population.

Historical Context

For decades, hypertriglyceridemia and low HDL cholesterol have been recognized as robust markers of residual cardiovascular risk. While pre-statin era fibrate trials like the Helsinki Heart Study and VA-HIT showed some cardiovascular benefit, modern trials investigating fibrates added to statins (such as FIELD and ACCORD-Lipid) failed to demonstrate overall primary endpoint reductions. However, subgroup analyses from those trials suggested a potential benefit in patients with high triglycerides and low HDL-C. The PROMINENT trial was explicitly designed to test this exact high-risk phenotype using a novel, highly selective PPARα modulator (pemafibrate), definitively proving that this targeted strategy does not confer cardiovascular benefit.

Guided Discussion

High-yield insights from every perspective

Med Student

Medical Student

How does the mechanism of a selective PPAR alpha modulator like pemafibrate differ from traditional statins, and why was it hypothesized to reduce cardiovascular risk in patients with elevated triglycerides?

Key Response

Statins primarily inhibit HMG-CoA reductase to lower atherogenic LDL cholesterol. PPAR alpha agonists upregulate lipoprotein lipase to lower triglycerides and increase HDL. The hypothesis was that addressing this residual risk profile in statin-treated diabetic patients would lower cardiovascular events, but the trial showed no benefit, highlighting the difference between modifying lipid profiles and actual atherogenesis.

Resident

Given the results of the PROMINENT trial, how should you approach a patient with type 2 diabetes on a high-intensity statin who presents with a fasting triglyceride level of 350 mg/dL?

Key Response

The trial demonstrated that adding pemafibrate to lower mild-to-moderate triglycerides does not reduce cardiovascular events. Therefore, residents should focus on optimizing glycemic control, implementing lifestyle modifications, and considering evidence-based therapies like icosapent ethyl or SGLT2/GLP-1 agents rather than initiating a fibrate to lower cardiovascular risk.

Fellow

In the PROMINENT trial, despite significant reductions in triglycerides and VLDL cholesterol, apolipoprotein B (ApoB) levels did not decrease. How does the ApoB hypothesis explain the failure of pemafibrate to reduce cardiovascular events?

Key Response

ApoB is the primary structural protein of all atherogenic lipoproteins. Pemafibrate reduced the lipid content (triglycerides) within VLDL particles but did not reduce the actual number of circulating ApoB-containing particles. Because cardiovascular risk is driven primarily by the number of atherogenic particles rather than their triglyceride content, the lack of ApoB reduction explains the lack of clinical benefit.

Attending

Decades of fibrate trials have shown mixed or negative results, yet fibrates remain widely prescribed for cardiovascular risk reduction. How do the PROMINENT findings help you definitively teach colleagues to deprescribe or avoid initiating fibrates in statin-treated diabetic patients for the purpose of preventing ASCVD?

Key Response

Attendings must shape evidence-based practice. PROMINENT definitively closes the door on the triglyceride hypothesis for fibrates in statin-treated patients, serving as a powerful teaching tool to shift clinical focus away from simply making the triglyceride numbers look better, toward interventions that actually reduce atherogenic particle number or provide proven cardiovascular benefit.

Scholarly Review

Critical appraisal through the lens of expert reviewers and guideline development

PhD

The PROMINENT trial observed an unexpected lack of ApoB lowering in the pemafibrate group. How might future trial designs integrating Mendelian randomization for target validation have better predicted this discordance between triglyceride lowering and ApoB response prior to a massive phase 3 trial?

Key Response

Mendelian randomization studies of the LPL and PPAR pathways often indicate that triglyceride lowering without a concomitant reduction in ApoB does not translate to cardiovascular benefit. A rigorous evaluation of human genetic data could have predicted the futility of this mechanism for ASCVD reduction, saving substantial research resources.

Journal Editor

As an editor reviewing the PROMINENT manuscript, how do you critically evaluate the decision of the data safety monitoring board to continue the trial after early mechanistic data might have shown no effect on ApoB, considering the growing consensus that ApoB reduction is essential for ASCVD benefit?

Key Response

Editors must evaluate trial ethics and continuation criteria. The uncoupling of triglyceride lowering from ApoB reduction is a major red flag for futility in lipid trials. A tough reviewer would question the justification for persisting with a primary cardiovascular endpoint that was biologically discordant with the drug's pharmacodynamic effect on atherogenic particles.

Guideline Committee

Current AHA/ACC guidelines do not strongly endorse fibrates for ASCVD risk reduction in statin-treated patients with mild-moderate hypertriglyceridemia but leave room for clinical judgment. How do the PROMINENT results influence the next iteration of lipid management guidelines regarding the concept of residual risk?

Key Response

PROMINENT provides definitive Level A evidence to assign a Class III (No Benefit) recommendation against using PPAR alpha modulators or fibrates for ASCVD risk reduction in statin-treated patients with mild-to-moderate hypertriglyceridemia. Guidelines must explicitly state that treating isolated triglyceride elevations (200-499 mg/dL) with these agents to lower ASCVD risk is futile, reinforcing the preference for proven agents like icosapent ethyl.

Clinical Landscape

Noteworthy Related Trials

2005

FIELD Trial

n = 9,795 · Lancet

Tested

Fenofibrate 200mg daily

Population

Patients with type 2 diabetes

Comparator

Placebo

Endpoint

Coronary events (CHD death or non-fatal MI)

Key result: Fenofibrate did not significantly reduce the primary outcome of coronary events, though it reduced total cardiovascular events and microvascular complications.

2010

ACCORD-Lipid Trial

n = 5,518 · NEJM

Tested

Fenofibrate added to simvastatin

Population

Patients with type 2 diabetes at high risk for cardiovascular disease

Comparator

Placebo added to simvastatin

Endpoint

3-point MACE

Key result: The addition of fenofibrate to simvastatin did not reduce the rate of cardiovascular events compared to simvastatin alone overall, though a subgroup with high triglycerides showed possible benefit.

2018

REDUCE-IT Trial

n = 8,179 · NEJM

Tested

Icosapent ethyl 4g daily

Population

Statin-treated patients with elevated triglycerides and high cardiovascular risk

Comparator

Placebo

Endpoint

5-point MACE

Key result: Icosapent ethyl significantly reduced the risk of ischemic events, including cardiovascular death, by 25 percent compared to placebo.

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