New Torcetrapib/Atorvastatin Research Further Supports Raising "Good" HDL Cholesterol
Mar 15, 2006 - 5:58:22 PM
Pfizer said today that new data, involving its medicine in development torcetrapib/atorvastatin, provides important information on the benefit of raising HDL, or "good" cholesterol, while simultaneously lowering LDL, or "bad" cholesterol. These new findings may play a critical role in reducing the burden of cardiovascular disease and potentially improving quality of life for patients. Data from three separate studies were presented this week at the American College of Cardiology meeting.
"As the first potential treatment to offer substantial HDL cholesterol elevations and significant LDL cholesterol lowering, torcetrapib/atorvastatin could well change how physicians manage their patients with cardiovascular disease," said Dr. John LaMattina, president of Pfizer Global Research and Development. "This comprehensive clinical trial program will help determine if this hypothesis can offer patients the benefit of slowing atherosclerosis and ultimately preventing cardiovascular events beyond what can be achieved with Lipitor alone."
It is estimated that 71 million Americans suffer from cardiovascular disease, a leading cause of death in the United States. Most people with elevated cholesterol, a leading risk factor for heart attacks and strokes, are either not diagnosed or have not reached their target LDL levels with medication. In addition, research has shown that raising HDL-cholesterol may provide further benefits in the management of cardiovascular disease, which may have the potential to further reduce cardiovascular risk for patients.
Discovered and developed by Pfizer, torcetrapib works by blocking CETP (cholesterol ester transfer protein) which is a protein that regulates cholesterol and is responsible for transferring cholesterol from its "good" HDL carrier to LDL, the "bad" carrier of cholesterol that results in plaque buildup in the arteries. Scientists believe that CETP inhibition raises HDL levels which results in cholesterol removal from the artery walls. Torcetrapib also lowers LDL cholesterol and LDL is known to cause heart attacks and stroke.
Presentation 1—HDL and LDL as Predictors for CV Disease/Sub- Analysis of Lipitor TNT Study
The primary objective of the Treating to New Targets (TNT) study was to demonstrate the clinical benefits of intensive LDL cholesterol lowering. This sub-analysis of TNT found that patients treated to LDL cholesterol levels that were below current medical guidelines showed a direct relationship between HDL cholesterol levels and the frequency of cardiovascular events—1 mg/dL increase in HDL cholesterol levels was estimated to have an associated 2 percent reduction in the risk of a heart attack or stroke.
"This study further supports the potential benefits of managing HDL levels as an additional target for patients who are already receiving statin therapy," said Dr. Philip Barter, lead author, TNT sub-analysis, The Heart Institute in Sydney, Australia. "While lowering LDL cholesterol remains a critical focus in cardiovascular disease prevention, the TNT sub-analysis suggests that HDL cholesterol may also provide important therapeutic benefits that may result in further reductions in cardiovascular risk."
Presentation 2—Torcetrapib/Atorvastatin: AM vs PM: Examining the Optimal Time of Dosing
Patients received either torcetrapib (100 mg) alone or torcetrapib (60 mg) and atorvastatin (20 mg) together, taken in the mornings or evenings, to determine if greater increases in HDL would be achieved based on the time of dosing. Torcetrapib, a CETP inhibitor is believed to be most effective when taken in the morning. Unlike most statins—which are taken in the evening for maximum reduction in LDL cholesterol—atorvastatin can be dosed anytime of the day and obtain equal LDL lowering effects.
Patients who took torcetrapib (60 mg) and atorvastatin (20 mg) in the morning experienced the most significant increase of 54.4 percent in HDL-cholesterol which was 12 percent higher than patients who took both torcetrapib and atorvastatin in the evening. Additionally, patients achieved a reduction in LDL cholesterol levels regardless of the time of day that therapy was taken.
"This is the first data to show that there are important differences in raising HDL cholesterol levels with torcetrapib depending on whether it is dosed in the morning or evening, and also highlights the flexibility and efficacy of atorvastatin," said Dr. Megan Gibbs, associate director of clinical research of Pfizer Global Research and Development.
Presentation 3—Torcetrapib/Atorvastatin: Exploring Benefits of Lipid-Modifying Effects
Pfizer researchers also presented data from another study involving 493 patients to determine the effectiveness of torcetrapib (30, 60, 90 mg) either alone or in combination with atorvastatin (10, 20, 40, 80 mg).
In particular, the study addressed the HDL and LDL particle size and number using new technology—nuclear magnetic resonance (NMR). Leading researchers believe both larger HDL and LDL particles, and lower numbers of LDL particles are less likely to contribute to the development of atherosclerosis, or plaque build-up in the arteries, which is important in cardiovascular health. In this study, patients taking torcetrapib and atorvastatin together experienced a decrease in LDL cholesterol, and an increase in HDL cholesterol levels, as well as increases in the particle size of both HDL and LDL.
"These data provide important information on how CETP inhibition with torcetrapib affects the number and nature of lipid particles," said Dr. Tom Thuren, director of clinical development, Pfizer Global Research and Development. "While the impact of these changes on cardiovascular risk is not currently known, we are diligently examining this and other areas in a large-scale clinical trial program."
In this study, side effects of torcetrapib and Lipitor were similar to those most commonly associated with statin therapy. Patients taking 60 mg of torcetrapib with Lipitor also experienced an increase in systolic blood pressure of approximately 2 mm Hg, which will be further defined in ongoing phase 3 studies.
Pfizer's torcetrapib/atorvastatin development program is the largest and most comprehensive clinical trial program the company has ever undertaken and is studying some 25,000 patients at hundreds of medical centers worldwide at a cost of about $800 million.
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