HDL and CETP Inhibition: Will This DEFINE the Future?

Area of Science:

• Cardiovascular Medicine
• Lipid Metabolism
• Clinical Trials

Background:

• The
• HDL-raising hypothesis
• suggests increasing high-density lipoprotein cholesterol (HDL-C) offers cardiovascular benefits beyond statin therapy.
• However, recent clinical trials have challenged this hypothesis.
• Low HDL-C remains an independent cardiovascular disease (CVD) risk factor.

Purpose of the Study:

• To evaluate the clinical utility of raising HDL-C as an adjunct to statin therapy.
• To assess the impact of extended-release niacin on cardiovascular outcomes in patients with low HDL-C and existing CVD.

Main Methods:

• The Atherothrombosis Intervention in Metabolic Syndrome with Low HDL/High Triglycerides: Impact on Global Health (AIM-HIGH) study aimed to equalize low-density lipoprotein cholesterol (LDL-C) levels between treatment groups.
• The niacin arm was designed to achieve higher HDL-C levels in patients with established cardiovascular disease (CVD) and low HDL-C.
• Previous studies like the Coronary Drug Project, Cholesterol Lowering Atherosclerosis Study (CLAS), and HDL-Atherosclerosis Treatment Study (HATS) informed the rationale.

Main Results:

• The AIM-HIGH study was prematurely stopped due to futility, indicating no additional cardiovascular benefit from raising HDL-C with niacin on top of statins.
• Prior trials with estrogen therapy (HERS) and cholesteryl ester transfer protein (CETP) inhibitors (torcetrapib in ILLUMINATE, dalcetrapib in dal-OUTCOMES) also failed to demonstrate benefits.
• Niacin increases HDL-C and alters HDL particle composition, but this did not translate to improved cardiovascular outcomes in AIM-HIGH.

Conclusions:

• Current evidence suggests that raising HDL-C with niacin does not provide additional cardiovascular benefits when used with statin therapy.
• The failure of multiple agents targeting HDL-C raises significant doubt about the
• HDL-raising hypothesis
• for improving cardiovascular outcomes.
• Focus remains on achieving LDL-C and non-HDL targets, as low HDL-C persists as a risk factor without proven therapeutic intervention for raising it.