Contacts:

Sharon Tetlow diaDexus, Inc. (650) 246-6400

Carolyn Bumgardner Wang WeissComm Partners (415) 362-5018 x123 carolyn@weisscommpartners.com

NEW WEBSITE EXPOSES HIDDEN RISK FACTORS FOR HEART DISEASE AND WHAT YOU CAN DO ABOUT THEM

www.plactest.com Launched to Raise Awareness of the Role of Inflammation in Heart Disease

South San Francisco, CA - September 29, 2004 - diaDexus today announced the launch of www.plactest.com to inform physicians, lab professionals and patients of the connection between inflammation and coronary heart disease (CHD). The new website also provides information about a simple test that can help physicians assess the risk of a cardiovascular event in their patients. In addition, healthcare providers can access the latest published information, clinical overviews and slide decks directly from the site's Scientific Resource Center.

According to the American Heart Association, more than 500,000 Americans die each year from CHD-related events, such as heart attacks. Many of these deaths occur in individuals who do not know they are at risk for heart disease and heart attack. For many years, physicians and patients alike have focused on LDL cholesterol as the cause of atherosclerosis leading to heart disease, yet nearly half of all coronary events occur in people who have low to moderate LDL cholesterol levels.

"Cardiac events are extremely difficult to predict and it is therefore important to know what the risk factors are and how to test for them," said Krishna Sudhir, M.D., Ph.D. and vice president of Medical Affairs at diaDexus. "Prevention of CHD is much easier if a person is armed with information about their risks and what to do about them."

The PLAC® test, developed by diaDexus, is a simple blood test that can aid in determining if a patient with non-elevated LDL cholesterol may be at increased risk for developing CHD. The PLAC test can be performed following a traditional risk assessment help better determine a clear clinical strategy for appropriate patients.

The PLAC test measures the level of the enzyme, lipoprotein-associated phospholipase A2 (Lp-PLA2), in the blood. Several published studies have demonstrated the clear and independent association between levels of this enzyme and risk of a CHD event. Studies also suggest that Lp-PLA2 promotes vascular inflammation through the hydrolysis of oxidized LDL within the intima of the blood vessel, contributing directly to the process that builds plaque that can eventually rupture and precipitate a CHD event.

About diaDexus
diaDexus, Inc., a privately held biotechnology company, based in South San Francisco, California, is focused on the discovery, development and commercialization of novel, patent-protected diagnostic and therapeutic products with high clinical value. The PLAC test, developed by diaDexus, Inc., is a blood test cleared by the U.S. Food and Drug Administration to aid in the prediction of an individual's risk for a coronary event, in conjunction with clinical evaluation and patient risk assessment. The PLAC test is currently available through laboratories nationwide. For more information about the PLAC test visit www.plactest.com. More information about the company may be found at www.diaDexus.com.