Contacts:

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

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

DIADEXUS ANNOUNCES PRESENTATIONS ON NOVEL CANCER MARKERS AT THE 96TH ANNUAL MEETING OF THE AMERICAN ASSOCIATION FOR CANCER RESEARCH

South San Francisco, CA - April 15, 2005 - diaDexus announced today multiple presentations highlighting novel cancer markers and discovery methodologies. The presentations will take place at the 96th Annual Meeting of the American Association for Cancer Research (AACR) being held April 16-20, 2005 at the Anaheim Convention Center in Anaheim, CA.

The presentations are as follows:

Sunday, April 17, 2005
Poster Session: Molecular Markers in Diagnosis and Prognosis 1: Gastrointestinal Malignancies (Colorectal, Gastric, Pancreatic, and Hepatocellular)
Title: Evaluation of DcR3 (DD-C248) as a serum diagnostic biomarker for colon cancer
Abstract #1259: 1:00 p.m. - 5:00 p.m.

Monday, April 18, 2005
Poster Session: Cancer Profiling and Therapeutics
Title: A novel splice variant of human Ep-CAM as a potential therapeutic antibody target for epithelial cell-based cancers
Abstract #2706: 1:00 p.m. - 5:00 p.m.

Tuesday, April 19, 2005
Poster Session: Molecular Genetics 4: Reproductive Cancers
Title: B7-H4 (DD-0110) is overexpressed in uterine endometrioid carcinomas independent of tumor grade, T cell infiltration, or apoptotic index
Abstract #3604: 8:00 a.m. - 12:00 p.m.

Poster Session: Molecular Markers in Diagnosis and Prognosis 6: Gynecologic and Epithelial Cancers
Title: Evaluation of B7-H4 (DD-O110) as a prognostic marker in tissue and serum of ovarian cancer patients
Abstract #4882: 1:00 p.m. - 5:00 p.m.

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.