Dendreon Begins Enrollment in Phase 2 Neu-ACT Trial for Second Active Cellular Immunotherapy Product Candidate, DN24-02 – TUCC Serves as an Enrollment Site for Trial

October 17, 2011

Dendreon Corporation (Nasdaq: DNDN) today announced that the company has begun enrolling patients into a Phase 2 trial for DN24-02, Dendreon’s investigational active cellular immunotherapy being evaluated for the treatment of HER2 positive cancer. The multicenter trial called Neu-ACT (NEU Active Cellular immunoTherapy) is expected to enroll approximately 180 patients to evaluate the safety and efficacy of DN24-02 as adjuvant therapy in patients with high risk HER2 positive invasive urothelial carcinoma, including bladder cancer, following surgical resection.

“We believe that our active cellular immunotherapy platform may have applications in the treatment of other cancers, and are pleased to offer patients and physicians access to DN24-02 through our Phase 2 Neu-ACT clinical trial,” said Mark Frohlich, M.D., executive vice president of research and development and chief medical officer. “Initiating a Phase 2 clinical trial to evaluate immunotherapy outside of the treatment of prostate cancer is a significant milestone for Dendreon, and we look forward to the outcome of this important study.”

Neu-ACT is a multicenter, open-label, Phase 2 study. Patients will be randomized to receive either the investigational product, DN24-02, or standard of care. The primary endpoint of the trial will be to evaluate overall survival between these two groups of patients. Other objectives of the study are to evaluate safety, disease-free survival, and immune response to treatment with DN24-02. Additional information is available at http://clinicaltrials.gov.

“Immunotherapy has great potential to offer breakthroughs in cancer care. In fact, bladder cancer recurrence rates have already seen a profound impact by immune manipulation. We are pleased to continue to lead this evolving field by participating in this Phase 2 trial clinical trial of DN24-02,” said John Corman, M.D., Medical Director of the Virginia Mason Cancer Institute in Seattle and clinical investigator for the Neu-ACT program. “Given the promise of immunotherapy, this is an important step forward for patients with this complex disease.”

Approximately 30 sites across the U.S. will participate in the Phase 2 Neu-ACT trial, including the following sites currently enrolling patients:

• Virginia Mason Medical Center, Seattle, Washington
Contact: Kathryn Dahl, 206-341-0578, kathryn.dahl@vmmc.org
Principal Investigator: John Corman, M.D.

• Columbia University Medical Center, New York, New York
Contact: Katherine Resto-Garces, 212-304-5522, kr2115@columbia.edu
Principal Investigator: Dan Petrylak, M.D.

• Fox Chase Cancer Center, Philadelphia, Pennsylvania
Contact: Charlotte Cione, RN, 215-728-3614, Charlotte.Cione@fccc.edu
Principal Investigator: Elizabeth Plimack, M.D.

• The Urology Center of Colorado, Denver, Colorado
Contact: Candice Fortuna-Smith, 303-421-5783, cfortuna@tucc.com
Principal Investigator: Lawrence Karsh, M.D.

• University of Chicago Medical Center, Chicago, Illinois
Contact: Toni Mazurek, 773-834-0669 or 855-702-8222, amazurek@medicine.bsd.uchicago.edu
Principal Investigator: Peter O’Donnell, M.D.

• Indiana University, Indianapolis, Indiana
Contact: Rhonda Loman, 317-274-0101, rloman@iupui.edu
Principal Investigator: Thomas Gardner, M.D.

• Duke University, Durham, North Carolina
Contact: Trish Creel, 919-668-0635, patricia.creel@duke.edu
Principal Investigator: Michael Harrison, M.D.

• Providence Medical Center, Portland, Oregon
Contact: Katrina Herz, 503-215-2617, Katrina.Herz@providence.org
Contact: Scot Lary, 503-215-2604, John.Lary@providence.org
Principal Investigator: Brendan Curti, M.D.

About Dendreon:
Dendreon Corporation is a biotechnology company whose mission is to target cancer and transform lives through the discovery, development, commercialization and manufacturing of novel therapeutics. The Company applies its expertise in antigen identification, engineering and cell processing to produce active cellular immunotherapy (ACI) product candidates designed to stimulate an immune response in a variety of tumor types. Dendreon’s first product, PROVENGE® (sipuleucel-T), was approved by the U.S. Food and Drug Administration (FDA) in April 2010. Dendreon is exploring the application of additional ACI product candidates and small molecules for the potential treatment of a variety of cancers. The Company is headquartered in Seattle, Washington and is traded on the NASDAQ Global Market under the symbol DNDN. For more information about the Company and its programs, visit http://www.dendreon.com/.

This news release contains forward-looking statements that are subject to risks and uncertainties. Factors that could affect these forward-looking statements include, but are not limited to, developments affecting Dendreon’s business and prospects, including progress on the commercialization efforts for PROVENGE. Information on the factors and risks that could affect Dendreon’s business, financial condition and results of operations are contained in Dendreon’s public disclosure filings with the U.S. Securities and Exchange Commission, which are available at www.sec.gov. Dendreon cautions investors not to place undue reliance on the forward-looking statements contained in this press release. All forward-looking statements are based on information currently available to Dendreon on the date hereof, and Dendreon undertakes no obligation to revise or update these forward-looking statements to reflect events or circumstances after the date of this press release, except as required by law.