Dendreon Identifies Novel Approach to Improve Immunization Efficiency; Data Published in Nature Biotechnology May Further Cancer Vaccine Development.

Business Editors/Health & Medical Writers

SEATTLE--(BW HealthWire)--Nov. 28, 2000

Researchers at Dendreon Corporation (Nasdaq:DNDN) have reported a novel method for generating an enhanced immune response with potentially important implications for improving the efficiency of therapeutic cancer vaccines.

The data, published in the December issue of Nature Biotechnology, highlights a method for modifying targets on cancer cells called antigens to facilitate activation of cytotoxic T cells -- a key component of the immune system responsible for destroying cancerous cells.

Cancer vaccines are designed to jumpstart the immune system's natural disease-fighting ability. Cytotoxic T-cells in particular have been shown to be directly responsible for killing cancerous cells. Cytotoxic T-cells are educated to detect antigens on cancer cells by dendritic cells -- immune system watchdogs that internalize and process antigens prior to bringing them to the attention of T-cells.

In their study, Dendreon researchers found that a cytotoxic T-cell response could be greatly enhanced by engineering an antigen in a way that optimizes its uptake and processing by dendritic cells. Their approach involves the addition of a peptidic sequence to a modified, soluble protein antigen. Researchers analyzed the T-cell response elicited by the modified antigen in mouse models and found that mice immunized with the modified antigen generated significant cytotoxic T-cell activity while mice that received unmodified antigen showed no T-cell response.

"Our research provides strong evidence that a robust, enhanced T-cell response can be elicited through this type of antigen engineering. These findings also complement our Antigen Delivery CassetteTM technology," said Dr. Reiner Laus, lead author of the publication and vice president of immunology at Dendreon Corporation. "This is a novel approach with important implications for the immunotherapy of cancer."

The methodology described in the report is applicable to the development of a variety of vaccines and highlights a method for generating a strong immune response with a small amount of antigen. Dendreon's current vaccine products in development utilize a proprietary Antigen Delivery Cassette technology that targets engineered antigens to dendritic cells. Dendreon has synthesized Antigen Delivery Cassettes for a variety of different tumor targets.

Dendreon Corporation (www.dendreon.com) is dedicated to the discovery and development of novel products for the treatment of cancer through its innovative manipulation of the immune system. Dendreon is focused on the development of therapeutic cancer vaccines through the use of antigen discovery, antigen engineering and dendritic cell technologies. Dendreon's vaccine for the treatment of prostate cancer, Provenge(TM), is in Phase III clinical trials and its vaccine for the treatment of multiple myeloma, Mylovenge(TM), is in Phase II clinical trials.

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 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 related to Dendreon's limited operating history, risks associated with completing our clinical trials, dependence on the efforts of third parties, and our 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, including Dendreon's Form 10-Q and Form S-1 Registration Statement, which are available at www.sec.gov.