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

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

RESULTS FROM LANDMARK 14-YEAR STUDY SHOW LP-PLA2 IS INDEPENDENT PREDICTOR OF CORONARY EVENTS

MONICA Study in Circulation is Third Peer-reviewed Study of PLACTM Test in Large Population

South San Francisco, CA - October 5, 2004 - A prospective cohort study of the MONICA population, a landmark 14-year population study, published in today's issue of Circulation, the Journal of the American Heart Association, supports the measurement of lipoprotein-associated phospholipase A2 (Lp-PLA2) as an independent predictor of individuals at risk for future coronary events.

Coronary heart disease (CHD) is the leading cause of death in the United States. Nearly half of all coronary events occur in individuals who do not have high cholesterol. Therefore, novel risk factors like Lp-PLA2, may help assess risk in patients without high cholesterol and other commonly measured risk factors.

"This study demonstrates that Lp-PLA2 is a novel, independent risk marker for coronary events across all levels of total cholesterol," said Professor Wolfgang Koenig, M.D., Department of Internal Medicine II-Cardiology, University of Ulm Medical Center, Ulm, Germany, and lead author of the study. "Our study also confirmed CRP as an independent risk factor, with an additive effect of both markers on risk prediction."

Study Details & Results
The research team investigated simultaneously the association between plasma concentrations of Lp-PLA2, CRP, and long-term risk of CHD in initially healthy middle-aged men.

This cohort of the MONICA (MONItoring of trends and determinants in CArdiovascular disease) population includes 934 men, aged 45-64 years who were originally surveyed in 1984 from the general population in Augsburg, Germany. In a follow-up study, baseline plasma concentrations of Lp-PLA2 were measured by the PLAC test and results were correlated with the 1998 vital statistics on the population. The prospective, full-cohort study established that baseline levels of Lp-PLA2 were higher in the 97 men who developed CHD events than the 837 event-free subjects during the 14 year follow up period. Moreover, a one standard deviation increase in Lp-PLA2 was associated with a 37% increase in the incidence of a coronary event. In multivariate models both Lp-PLA2 and CRP were independently predictive of coronary events, while individuals with elevated levels of both markers had the highest risk of an event.

"This MONICA publication adds to the growing body of evidence supporting Lp-PLA2 as a risk factor for CHD in large populations," said Krishna Sudhir, M.D., Ph.D. and vice president of Medical Affairs at diaDexus. "The results from this peer reviewed study further validate clinical use of the PLAC test to assist physicians in their diagnosis and treatment of CHD."

The results from the Atherosclerosis Risk in Communities (ARIC) study, published in the February 2004 issue of Circulation, and the West of Scotland Coronary Prevention Study (WOSCOPS) study, published in October 2000 in the New England Journal of Medicine, both showed a statistically significant relationship between elevated Lp-PLA2 and the risk of a cardiac event. Among individuals in ARIC who had normal LDL levels (<130 mg/dL), those with elevated Lp-PLA2 levels were shown to be at twice the risk for a coronary event compared to similar individuals with the lowest levels of Lp-PLA2.

This study was supported by a grant from diaDexus, Inc.

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.