diaDexus Inc announced that the U.S. Food and Drug Administration (FDA) has granted the Company marketing clearance for the PLAC test. This test is cleared as an aid in predicting an individual's risk for coronary heart disease (CHD), in conjunction with clinical evaluation and patient risk assessment.

The PLAC test measures the level of lipoprotein-associated phospholipase A2 (Lp-PLA2) in human blood. Lp-PLA2 is an enzyme that has been identified as a novel risk factor for coronary events.

As the leading cause of death in the United States, CHD accounts for more than one in every five deaths. Each year, more than 500,000 Americans die from CHD-associated events. Nearly half of all individuals who experience a coronary event do not exhibit traditional risk factors such as high blood pressure, elevated LDL cholesterol ("bad" cholesterol), smoking, diabetes mellitus, marked obesity or physical inactivity.

"The PLAC test is an important new tool which physicians may use to more accurately predict who is at risk for heart disease," said Christie Ballantyne, director of the Center for Cardiovascular Disease Prevention at Baylor College of Medicine and the Methodist DeBakey Heart Center in Houston. "Somewhere between one-third and one-half of heart attacks occur in people considered to have normal LDL cholesterol. This test enables us to better determine who is at risk for CHD before an adverse event occurs, allowing both the individual and his or her physician to take proactive and preventative measures, such as lifestyle modification or therapeutic intervention."

Results from a study presented by Dr. Ballantyne at the American College of Cardiology Annual Meeting 2003 show that individuals with normal LDL, but elevated levels of Lp-PLA2, are twice as likely to experience a coronary event as those individuals with normal levels of both LDL and Lp-PLA2, independent of traditional risk factors and C-reactive protein (CRP). Additional results show that individuals with normal LDL, but high levels of both Lp-PLA2 and CRP, have the greatest risk of a coronary event.

"Receiving marketing clearance for the PLAC test represents an important milestone for diaDexus. There is significant market potential for a product that helps identify patients at risk for CHD who are not currently identified by traditional risk factors," said Patrick Plewman, chief executive officer of diaDexus.

Research is currently underway to evaluate the effects of statin therapy on Lp-PLA2 levels. In addition, GlaxoSmithKline is developing an inhibitor to Lp-PLA2 as a potential treatment for atherosclerosis. This inhibitor is currently in Phase II clinical trials.