diaDexus Inc has been granted the marketing clearance by the US FDA for the PLAC test, making it the first blood test to aid in predicting risk for ischemic stroke associated with atherosclerosis. The PLAC test measures an enzyme in the blood called lipoprotein-associated phospholipase A2 (Lp-PLA2).
Results from the National Heart Lung and Blood Institute’s Atherosclerosis Risk in Communities (ARIC) study demonstrated that individuals with elevated levels of Lp-PLA2 have a statistically significant twofold risk of suffering an ischemic stroke over a period of 6-8 years compared to individuals with low levels of Lp-PLA2. These findings are independent of traditional risk factors such as systolic blood pressure, smoking status and diabetes, as well as body mass index. Because Lp-PLA2 and systolic blood pressure levels are additive in their ability to predict stroke risk, the PLAC test can help identify stroke-prone hypertensive patients, according to a company release.
Stroke is the third largest killer in the United States and a leading cause of serious long-term disability. Each year approximately 700,000 strokes occur, 88% of which are ischemic strokes. While elevated cholesterol levels are highly predictive of heart disease, no such relationship has been established for stroke.
"Unlike cholesterol levels, which did not significantly vary between cases and noncases, Lp-PLA2 was a significant and independent predictor of stroke in the ARIC study," said Christie Ballantyne, director of the Centre for Cardiovascular Disease Prevention at Baylor College of Medicine and the Methodist DeBakey Heart Centre in Houston. "Current US guidelines for screening and prevention of cardiovascular disease are based on the risk for development of coronary heart disease and do not include risk for stroke. The PLAC test will help physicians more accurately predict who is at risk for future stroke, so that the individual and his or her physician can take proactive and preventative measures, such as lifestyle modification or therapeutic intervention, including statins and daily aspirin," Ballantyne added.
Recent research has shown that statin therapy significantly reduces Lp-PLA2 levels. In addition, GlaxoSmithKline is developing Lp-PLA2 inhibitors as a potential anti-atherosclerosis therapy. These inhibitors represent a new generation of therapeutics in development to potentially reduce cardiovascular disease and death.
Patrick Plewman, chief executive officer of diaDexus said, "The PLAC test provides new information, over and above traditional risk factors, that can guide physicians and patients to make the necessary changes that may prevent patients from suffering cardiovascular disease and events, like stroke and heart attack."
This study was supported by the National Institutes of Health (NIH) along with funding from GlaxoSmithKline.