Contacts:

Patrick Plewman diaDexus, Inc. (650) 246-6415

Carolyn Bumgardner Wang WeissComm Partners (415) 225-5050 cell (415) 692-4218 office carolyn@weisscommpartners.com

Scientific Sessions Abstract Poster Session #1013-101 & Oral Session #814-7

DATA PRESENTED AT ACC SCIENTIFIC SESSIONS 2005 DEMONSTRATE ELEVATED Lp-PLA2 LEVELS PREDICT CARDIOVASCULAR EVENTS

Second Study Highlights Lp-PLA2 as a Predictor of Ischemic Death and Angiographic Coronary Artery Disease

Orlando, FL - March 8, 2005 - diaDexus today announced findings from two studies that were presented at the American College of Cardiology (ACC) Scientific Sessions held in Orlando this week. The first study concluded that elevated levels of Lp-PLA2 (lipoprotein-associated phospholipase A2) appear to be independently predictive of future coronary events in patients with coronary heart disease (CHD). An additional study confirmed that Lp-PLA2 predicts risk of coronary artery disease (CAD) as diagnosed by angiography, as well as future ischemic death.

In the first study, "Lipoprotein-Associated Phospholipase A2 Plasma Concentrations Predict Cardiovascular Events in Patients with Coronary Heart Disease," researchers at the University of Ulm Medical Center, Ulm, Germany, used the PLAC® test to measure Lp-PLA2 in a cohort of 1033 patients aged 30-70 years with CHD. The study found that individuals with moderate to high levels of Lp-PLA2 were nearly twice as likely to suffer a myocardial infarction or stroke as those with the lowest levels.

"These results further support Lp-PLA2 as a predictor of future heart attack and stroke in individuals with diagnosed heart disease above and beyond traditional risk factors," said Professor Wolfgang Koenig, M.D., Department of Internal Medicine II-Cardiology, University of Ulm Medical Center, and lead investigator of the study. "Better identification of individuals at high risk for major vascular events allows for optimization of treatment strategies to minimize such episodes."

A second study, "Lipoprotein-Associated Phospholipase A2 Independently Predicts the Angiographic Diagnosis of Coronary Artery Disease," was performed by researchers at LDS Hospital, Intermountain Health Care, Salt Lake City, Utah, and measured both Lp-PLA2 and CRP levels in 1,493 patients enrolled in the registry of the Intermountain Heart Collaborative Study. All of these patients underwent coronary angiography to diagnose the presence or absence of CAD. The study confirmed that Lp-PLA2 predicts risk of CAD, independent of traditional risk factors and CRP. Lp-PLA2 was also found to predict the risk of ischemic death over a period of 6-8 years, suggesting that Lp-PLA2 may be considered a useful marker of clinical cardiovascular risk.

"The current research studies further support Lp-PLA2 as an independent risk factor for both heart attack and stroke," said Bob Wolfert, Ph.D., Vice President of Diagnostics at diaDexus. "Utilization of additional risk stratification tools, such as the PLAC test for Lp-PLA2, can help to more accurately identify those at high risk for a major cardiovascular event and to determine the most appropriate treatment strategy for the individual patient."

Both of these studies were supported by grants from diaDexus, Inc.

About Lp-PLA2 Lp-PLA2 (lipoprotein-associated phospholipase A2) is an enzyme that is implicated in the vascular inflammatory pathway that leads to plaque formation and atherosclerosis. Previous hypotheses on the cause of coronary heart disease focused around lipid accumulation within the arterial walls. Increasing evidence now suggests that atherosclerosis is largely an inflammatory disease. Multiple published studies in peer-reviewed journals show a statistically significant relationship between elevated Lp-PLA2 and the risk of a major cardiovascular event.

About diaDexus
diaDexus, 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, 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.