Studies Presented at AHA Confirm Role of Inflammatory Marker Lp-PLA2 in Assessing Cardiovascular Risk and in Secondary Prevention.

PLAC([R]) Test from diaDexus Measures Novel Heart Disease and Stroke Risk Factor

CHICAGO -- Research presented at the American Heart Association Scientific Sessions 2006 validate the role of lipoprotein-associated phospholipase A2 (Lp-PLA2), a cardiovascular-specific inflammatory enzyme associated with unstable plaque that can lead to heart attack and stroke, in the identification of patients at risk for cardiovascular disease and the prevention of subsequent events.

Lp-PLA2 levels in all studies were measured using the PLAC test from diaDexus. 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. Because traditional risk factors fail to identify many people at risk, novel markers such as Lp-PLA2 are increasingly being used to improve risk stratification and determine optimal treatment strategies.

Eight Lp-PLA2-focused abstracts will be presented during the meeting, with five highlighted during a morning session on novel risk markers and biomarkers Tuesday, Nov. 14, 2006. Key studies include:

* Researchers at the Mayo Clinic College of Medicine in Rochester, Minn., used the PLAC test to evaluate the value of Lp-PLA2 in assessing risk for subsequent death in 240 heart attack patients. Results show that Lp-PLA2 is not materially associated with any of the known prognostic factors after heart attack, including hypertension, diabetes, obesity, co-morbidity, myocardial infarction characteristics, C-reactive protein, and medication use, and adds to both the sensitivity and specificity of traditional risk estimates. The authors concluded that because Lp-PLA2 is an independent marker of vascular inflammation, it might be a useful diagnostic indicator in heart attack patients. (Nov. 14, 2006CoGerber Y, et al. Lipoprotein-Associated Phospholipase A2 and Prognosis After Myocardial Infarction in a Geographically Defined Cohort, Session AOP.93.2, 9-9:15 a.m., Abstract #4032)

* University of California San Diego researchers concluded that elevated levels of Lp-PLA2 independently predict heart disease in apparently healthy adults. In the study, blood samples were collected from 1,077 individuals, who were followed for 15-18 years for heart disease events, including fatal and non-fatal myocardial infarction, angina, or coronary revascularization. Participants with elevated Lp-PLA2 had significantly increased risk of heart disease, even after adjusting for age, sex, and other risk factors. (Nov. 14, 2006CoDaniels LB, et al. Lipoprotein-Associated Phospholipase A2 [Lp-PLA2] Independently Predicts Incident Coronary Heart Disease [CHD] in an Apparently Healthy Older Population: The Rancho Bernardo Study, Session AOP.93.2, 10-10:15 a.m., Abstract #4036)

According to Richard Lanman, M.D., diaDexus' chief medical officer, these and numerous other studies presented at the meeting add to the large and growing body of clinical evidence supporting the use of the PLAC test as an aid in identifying patients at high risk of a heart attack or stroke. "This impressive body of clinical research by leading investigators from around the country underscores the valuable diagnostic information Lp-PLA2 provides in independently identifying patients at high risk for heart attack and stroke," Lanman said. "Better risk assessment allows early, aggressive lifestyle and medical treatment, which is key to preventing potentially devastating cardiovascular events."

Lp-PLA2 is an enzyme that associates in the blood primarily with low-density lipoprotein (LDL, the "bad" cholesterol). Lp-PLA2 is carried to the walls of coronary arteries by LDL, where the enzyme can activate an inflammatory response, promoting atherosclerosis. As a result, Lp-PLA2 serves as a specific indicator of vascular inflammation. Individuals identified as being at high risk for coronary heart disease or stroke based on elevated Lp-PLA2 levels are candidates for proactive preventive measures, such as lifestyle modification and therapeutic intervention.

About diaDexus

diaDexus, Inc., a privately held biotechnology company based in South San Francisco, Calif., is focused on the discovery, development, and commercialization of clinically valuable, patent-protected diagnostic products. 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.

Note to editors: The AHA annual conference is being held at McCormick Place in Chicago, Nov. 12-15, 2006. diaDexus' booth number is 1689. For copies of the abstracts or a list of Lp-PLA2, clinical studies presented at the meeting, please contact Barbara Sullivan at 714/374-6174.