DIADEXUS CLOSES $102.5 MILLION PRIVATE PLACEMENT

Santa Clara, CA - April 11, 2000 - diaDexus, Inc. today announced the completion of a $102.5 million private placement of Series C preferred Stock. The financing was co-led by BA Venture Partners, the venture partnership funded by Bank of America, and American Express Financial Corporation. Prudential Vector Healthcare Group acted as sole placement agent.

"Genomics will transform the detection and treatment of disease, and diaDexus is at the vanguard of novel genomic biomarker discovery," said George Poste, DVM, Ph.D., diaDexus' Chairman. "The proceeds from the private placement will enable diaDexus to capitalize on the utility of novel genomic biomarkers for the detection of disease, as potential antigens for the development of therapeutic monoclonal antibodies and as immunizing antigens for therapeutic vaccines."

"With these additional funds, we will continue to accelerate our development efforts in cancer and expand the application of our biomarker discovery model into new disease areas. We will also assess selected antigens for development as therapeutic products," noted Patrick Plewman, President and Chief Operating Officer.

"We are extremely pleased with this endorsement by the investment community, " said Sharon Tetlow, diaDexus' Vice President of Finance and Chief Financial Officer. "With this money we are well positioned to extend our record of technical accomplishments."

The Company also announces the election of Louis Bock, General Partner, BA Venture Partners, to the diaDexus Board of Directors. Mr. Bock currently serves on the board of a number of privately held biotechnology companies including Seattle Genetics and Dynavax Technologies. He joined BA Venture Partners in 1997 and was previously with Gilead Sciences and Genentech.

diaDexus is a leader in the discovery and validation of novel genomic biomarkers for the detection and treatment of disease. The Company believes its products will enable physicians to detect disease at an early stage, predict and monitor response to therapy and select the most appropriate therapeutic regimen. The Company further believes its patented genomic biomarkers will be used to develop novel therapeutic monoclonal antibodies and therapeutic vaccines.

diaDexus was founded in 1997 by Incyte Genomics and SmithKline Beecham (SB), acknowledged leaders in genomics and bioinformatics. Incyte and SB contribute a substantial asset base of genomic intellectual property to the Company. diaDexus has access to Incyte's human and microbial genomic databases, LifeSeq® Gold and PathoSeqT. In addition, diaDexus has an exclusive license to certain diagnostic intellectual property arising from research and development efforts conducted at SB, including diagnostic rights arising from SB's collaboration with Human Genome Sciences, Inc.

The Company converted to a C corporation from an LLC in conjunction with the closing of this financing.

For more information, visit the diaDexus Web site.