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

DIADEXUS ANNOUNCES ADDITIONAL U.S. PATENT FOR LP-PLA2 ACTIVITY-BASED ATHEROSCLEROSIS DIAGNOSTIC TEST

South San Francisco, CA - May 30, 2007 - diaDexus, Inc., today announced that the U.S. Patent and Trademark Office has issued U.S. Patent No. 7,217,535 covering methods of diagnosing an individual's susceptibility for developing atherosclerotic disease, including myocardial infarction and stroke, by analyzing a blood sample for lipoprotein-associated phospholipase A2 (Lp-PLA2) enzymatic activity.

Lp-PLA2, an enzyme implicated in the formation of vulnerable, rupture-prone plaque, was discovered by scientists at GlaxoSmithKline (GSK). This patent is one of a group of Lp-PLA2-related GSK patents to which diaDexus has an exclusive commercial diagnostic license.

Currently, diaDexus sells the PLAC® test, an Lp-PLA2 immunoassay, for use as an aid in assessing risk of stroke or heart attack.

About diaDexus
diaDexus, Inc., 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 measures a new risk factor for heart disease and stroke—Lp-PLA2, a cardiovascular-specific inflammatory marker implicated in the formation of vulnerable, rupture-prone plaque. The PLAC test is cleared for marketing by the Food and Drug Administration as an aid in determining 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.