Contacts:

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

DIADEXUS ANNOUNCES SCIENTIFIC PRESENTATIONS AT AACR

Studies of Novel Markers in Ovarian, Prostate and Lung Cancer

South San Francisco, CA - March 26, 2004 - diaDexus, Inc., today announced six scientific presentations on novel cancer markers and discovery methodologies at the annual meeting of the American Association for Cancer Research (AACR), March 27 - 31 in Orlando, Florida.

"One area of focus for us is the detection of ovarian and breast cancers," said Dr. Jacqueline Papkoff, Vice President of Discovery for diaDexus. "These cancers still have enormous unmet clinical need in terms of detection and treatment. Ovarian cancer, for example, is typically diagnosed after it has spread, when the cure rate is quite low. If we can detect ovarian cancer early in the course of the disease we could have a significant impact on treatment and survival."

Three presentations (abstract numbers 3013, 3298, 3963) will describe the discovery and characterization of Ovr110, a novel membrane protein over expressed in ovarian, breast and endometrial cancer tissues and detected in the serum of women with ovarian cancer. Our work has also elucidated new functions for this protein and these findings suggest novel therapeutic and diagnostic strategies for the detection and treatment of cancer. One of the poster presentations will feature a collaboration with the University of Colorado Health Sciences Center.

Two other presentations (abstract numbers 413 and 427) will present work on novel markers in other prevalent and fatal cancers. "Another area where we have made inroads into detection is lung and prostate cancers," said Dr. Robert Wolfert, V.P. of Diagnostics at diaDexus. "Lung cancer is the leading cause of cancer death in the world, and yet there are no adequate methods for early detection of curable disease." diaDexus has identified the Lng105 protein that is measurable in the serum of lung cancer patients that may lead to earlier detection of the malignancy. "We have also identified and characterized Pro108, a new biomarker that in conjunction with prostate-specific antigen (PSA), may improve the detection rate of prostate cancer, a disease that will kill more than 30,000 men in the U.S. alone this year," said Wolfert.

The final presentation (abstract number 2703) will describe the discovery and validation of multiple novel splice variants of a membrane protein, Ovr232, in ovarian cancer. "This poster will feature diaDexus' target discovery and validation pipeline, including our capabilities to incorporate a comprehensive splice variant analysis of our targets," said Dr. Papkoff.

Separately, diaDexus scientists Dr. Tim Burcham and Barbara Lin will present a poster at the Eighth Annual International Conference on Research in Computational Molecular Biology (RECOMB) in San Diego, March 27 - 31. The poster, "Using the Human Genome as a Framework for Sequence Clustering and Microarray Design," discusses an advanced method of microarray chip design, developed and used at diaDexus, for both new biomarker discovery and validation.

AACR Sessions:
1.) Multiple splice variants of Ovr232 (Ep-CAM) differentially expressed in human cancer

Shu-Hui Liu, Maria Rodriguez, Steffan Vartanian, Melinda Au, Yongming Sun, Tim Burcham, Leah Turner, Jackie Papkoff and Roberto A. Macina diaDexus Inc, 343 Oyster Point Blvd, South San Francisco, CA 94080

Session ID: Cellular, Molecular, and Tumor Biology 53
Session Date and Start Time: Monday, March 29, 2004,
1:00 PM
Permanent Abstract Number: 2703

2.) Ovr110, a novel membrane associated protein up-regulated in ovarian and breast carcinomas, is expressed on some activated leukocyte populations
Laura Corral et al., diaDexus

Session ID: Experimental and Molecular Therapeutics 28
Session Date and Start Time: Monday, March 29, 2004,
1:00 PM
Permanent Abstract Number: 3013

3.) Evaluation of Ovr110 expression in normal endometrium, endometrial hyperplasia, and endometrioid carcinoma.
Barbara Tringler et al., University of Colorado Heath Sciences Center

Session ID: Cellular, Molecular, and Tumor Biology 63
Session Date and Start time: Tuesday, March 30, 2004,
8:00 AM
Permanent Abstract Number: 3298

4.) Detection of a novel membrane protein in serum: Ovr110, a potential serum marker for early detection of ovarian cancer
Iris Simon, Nam W. Kim, Theresa Kuo, Laura Corral, Shirley Vong, David Lowe, Susana Salceda, Robert Cafferkey, Roberto A. Macina, Mark J. Sarno, Robert L. Wolfert diaDexus Inc, 343 Oyster Point Blvd., South San Francisco CA 94080

Minisymposium
Session ID: Clinical Research 10
Session Date and Start Time: Tuesday, March 30, 2004,
9:00 AM
Permanent Abstract Number: 3963

5.) Characterization of Lng105/napsin A in human serum: a potential diagnostic with utility in lung cancer
Andrea Fan et al., diaDexus

Session ID: Clinical Research 2
Session Date and Start Time: Sunday, March 28, 2004,
8:00 AM
Permanent Abstract Number: 413

6.) Detection of Pro108/Spondin-2 protein in serum: A novel serum marker for cancer Iris Simon, Charis E. Lawrenson, Nam W. Kim, Daniel Bedinger, Danny Terwey, Shujath Ali, Robert Cafferkey, Roberto A. Macina, Tomonao Ouki, Mark J. Sarno, Robert L. Wolfert diaDexus, Inc., 343 Oyster Point Blvd., South San Francisco, CA 94080

Session ID: Clinical Research 2
Session Date and Start Time: Sunday, March 28, 2004,
8:00 AM
Permanent Abstract Number: 427

About diaDexus
diaDexus, Inc., a privately held biotechnology company, based in South San Francisco, Calif., is focused on the discovery, development and commercialization of novel, patent-protected diagnostic and therapeutic products with high clinical value. diaDexus utilizes genomics and bioinformatics to identify numerous disease-associated molecular targets. More information about the company may be found at www.diaDexus.com.