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Barbara Sullivan Sullivan & Associates 714/374-6174 bsullivan@sullivanpr.com

Christina Andrian diaDexus, Inc. 650/246-6476 candrian@diadexus.com

STUDY PRESENTED AT THE ACC SHOWS INFLAMMATORY ENZYME LP-PLA2 PREDICTS HEART DISEASE RISK IN METABOLIC SYNDROME PATIENTS

PLAC® test from diaDexus measures key heart disease & stroke risk factor

New Orleans, LA - March 26, 2007 - Study results show that elevated lipoprotein-associated phospholipase A2 (Lp-PLA2), a cardiovascular-specific inflammatory enzyme associated with unstable plaque that can lead to heart attack and stroke, is especially predictive of heart disease risk in patients with the metabolic syndrome-a serious medical condition that affects nearly 50 million Americans. The results, which were presented today at the American College of Cardiology's annual scientific session, confirm previous findings demonstrating the association between elevated Lp-PLA2 and coronary heart disease.

Investigators at the University of Utah in Salt Lake City used the PLAC® test from diaDexus to measure Lp-PLA2 levels in blood samples from almost 1,500 patients enrolled in the Intermountain Heart Collaborative Study. The patients also underwent coronary angiography to determine the presence of heart disease and were tracked for up to 10 years. Results showed that Lp-PLA2 was a clinically important predictor of heart disease and future death in patients with the metabolic syndrome, a dangerous precursor to diabetes characterized by high blood pressure, high triglycerides, high fasting blood glucose, low high-density lipoprotein, and small, dense low-density lipoprotein (LDL). Lp-PLA2 also predicted heart disease death risk in non-metabolic syndrome patients.

According to Richard Lanman, M.D., diaDexus' chief medical officer, the findings are important because of the large number of patients with the metabolic syndrome who may be at significantly increased risk for diabetes, stroke, and heart disease. "Interest in the metabolic syndrome has been increasing along with Americans' growing waistlines," Lanman said. "This study confirms earlier results indicating that elevated Lp-PLA2 is independent from and additive to the increased cardiovascular risk associated with insulin resistance. The additional information about rupture-prone plaque provided by Lp-PLA2 can help identify which metabolic syndrome patients should be targeted with more aggressive treatment."

A second study presented at the meeting focused on treatment of 55 metabolic syndrome patients with elevated levels of Lp-PLA2 and triglycerides. The results presented by Dr. Robert Rosenson of the University of Michigan showed that three months of treatment with fenofibrate (160 mg/day) reduced Lp-PLA2 levels measured with the PLAC test. Lanman said these findings highlight the opportunity for plaque stabilization with lipid modifying medication when patients with the metabolic syndrome also have elevated Lp-PLA2. "The PLAC test identifies patients who benefit from lipid-modifying therapy such as fenofibrate to help prevent cardiovascular events," he said.

About diaDexus
diaDexus, Inc., a privately held biotechnology company based in South San Francisco, is focused on the discovery, development, and commercialization of innovative, patent-protected diagnostic products with high clinical value. The PLAC test is a simple blood test that has been cleared for marketing by the U.S. Food and Drug Administration as an aid in predicting risk for coronary heart disease and ischemic stroke associated with atherosclerosis. In addition to the PLAC test, diaDexus is developing a pipeline of novel cancer diagnostic tests. For more information, visit www.plactest.com or www.diaDexus.com.