Dendreon Presents Promising Preclinical Results from New Technology for Cancer Immunotherapy.

Business Editors/Health/Medical Writers

BIOWIRE2K

SEATTLE--(BUSINESS WIRE)--April 24, 2003

Dendreon Corporation (Nasdaq:DNDN) today presents data for the first time relating to a new immunotherapy technology that allows for the selection of any gene as a target for cancer immunotherapy.

In preclinical animal testing to date, this approach has provided up to 100 percent protection from developing cancer.

Dendreon's proprietary alternative reading frame (ARF) technology uses, as a target for cancer vaccines, abnormal peptides produced by cells as they translate genes into proteins. The sequence of ARF-derived peptides is totally different from the sequence of the biologically relevant protein derived from a given gene. Researchers at Dendreon have discovered that ARF sequences are potent targets for cancer vaccines.

These findings are being presented today by Reiner Laus, M.D., vice president of research and development at Dendreon, at the Knowledge Foundation's conference on Advances in Designing Cancer Vaccines in Boston, Mass.

"This technology provides an innovative approach for designing cancer vaccines. ARF-derived immunogens can be designed for all known genes and provide a vast reservoir of targets that have not been previously known or exploited," said Laus. "It was very surprising and exciting to discover that ARFs can be better immunogens and targets than the protein derived from the main open reading frame of a gene."

Study details

In the data being presented, Dendreon researchers designed ARF-derived immunogens and used them to immunize mice. The mice were then inoculated with tumors that expressed the gene from which the ARF were derived. The well-known, tumor-associated antigen Her-2 served as a target. Ten out of 10 ARF-immunized mice survived tumor free indefinitely (p= less than 0.001), while 10 out of 10 control mice died within 35 days.

Dendreon has applied for a patent covering the compositions and methods that relate to ARF technology.

"The discovery of the ARF technology is another example of Dendreon's premier research capabilities and will provide an exceptional platform to develop future product opportunities," said Mitchell H. Gold, M.D., chief executive officer of Dendreon. "The ARF technology can be applied to Dendreon's extensive list of antigen targets that address a number of leading cancers."

Dendreon's antigen targets and associated indications include:

-- Prostatic acid phosphatase: prostate cancer (Provenge(R),

Phase 3)

-- Her-2: breast, ovarian and colon cancers (APC8024, Phase 1)

-- Trp-p8: prostate, lung, colon and breast cancers;

-- NY-ESO: bladder, lung, breast, prostate, ovarian/uterine

cancers;

-- CEA: colon, lung and breast cancers;

-- MN: kidney, cervical and colon cancers;

-- Telomerase: many cancers.

Dendreon Corporation is a biotechnology company developing targeted therapies for cancer. The company's lead investigational product candidate, Provenge(R), is a cancer immunotherapy undergoing Phase 3 clinical trials for the treatment of advanced-stage prostate cancer. In addition to its therapeutic vaccines in clinical and preclinical development for a variety of cancers, Dendreon's product pipeline also includes monoclonal antibodies and small molecule product candidates. Dendreon has established important research and development alliances with industry leaders Genentech, Inc. and Kirin Brewery Co., Ltd. For more information about the company and its programs, visit www.dendreon.com.

Except for historical information contained herein, this news release contains forward-looking statements that are subject to risks and uncertainties that may cause actual results to differ materially from the results discussed in the forward-looking statements, particularly those risks and uncertainties inherent in the process of discovering, developing and commercializing drugs that are safe and effective for use as human therapeutics. Factors that may cause such a difference include risks relating to Dendreon's relatively limited operating history, risks associated with development of early stage product candidates through preclinical and clinical research and development, risks associated with completing Dendreon's clinical trials, the risk that the safety and/or efficacy results of preclinical studies will not support further development, the risks that the safety and/or efficacy results of a clinical trial will not support an application for a biologics license, the risk that the FDA will not approve a product for which a biologics license has been applied, the uncertainty of Dendreon's future access to capital, the failure by Dendreon to secure and maintain relationships with collaborators, the dependence on the efforts of third parties, the risks that a patent will not be granted or that the claims will be restricted or challenged by a third party, and the dependence on intellectual property. Further information on the factors and risks that could affect Dendreon's business, financial condition and results of operations, are contained in Dendreon's SEC reports, which are available at www.sec.gov