Dendreon Presents Data at American Association for Cancer Research Supporting Mechanism of Action of PROVENGE

SEATTLE and WASHINGTON, April 21 /PRNewswire-FirstCall/ -- Dendreon Corporation (Nasdaq: DNDN) announced the presentation of additional data from the Phase 3 IMPACT (IMmunotherapy for Prostate AdenoCarcinoma Treatment) clinical trial showing evidence of immune responses in patients treated with PROVENGE® (sipuleucel-T) and supporting its proposed mechanism of action. The data were presented at the American Association for Cancer Research (AACR) 101st Annual Meeting 2010 in Washington, D.C.

Data presented from 237 patients who participated in the immune monitoring protocol in the IMPACT study demonstrated that PROVENGE:

• Generated antigen-specific responses, including responses to prostatic acid phosphatase (PAP), an antigen expressed in prostate cancer tissue, that were not seen following treatment with placebo;
• Triggered both cellular and humoral immune responses in vivo that were first detected at six weeks after dosing and persisted at 26 weeks after dosing;
• Induced a T-cell response as further evidenced by antibody isotope class switching from IgM to IgG, suggesting the induction of immunologic memory; and
• Demonstrated a cytokine profile indicative of T-cell activation in ex vivo culture over the course of therapy, with marked increases in IL-2, IFNgamma, TNFalpha, and IL-17.  

These results were presented in a podium presentation titled, "Sipuleucel-T generates robust and persistent cellular and humoral immune responses: results from the IMPACT trial."

Data presented in the poster presentation "Sipuleucel-T treatment results in sequential ex vivo activation of APCs and T cells during the culture step: evidence for in vivo immunological priming" showed that PROVENGE:

• Engages the immune system in vivo through ex vivo activation of antigen presenting cells (APC) and T-cells;
• Primes the immune system with the first dose; and
• Demonstrates engagement of T-cells at the second and third doses.

"These data strongly support our understanding of the proposed mechanism of action of active cellular immunotherapies," said David Urdal, Ph.D., senior vice president and chief scientific officer of Dendreon.  "There is clear evidence that PROVENGE primes the T-cell component of the immune system in vivo through ex vivo activation, generating a successful and long-lasting immune response."

About Active Cellular Immunotherapy

PROVENGE and other active cellular immunotherapies (ACI) are designed to stimulate a T-cell response to cancer cells.  An immune response is started by a specialized class of immune system cells called antigen-presenting cells (APCs). APCs take up antigen from their surroundings and process the antigen into fragments that are then displayed on the APC surface. Once displayed, these antigens can be recognized by specific classes of immune cells called T lymphocytes (T-cells), which are activated as a result of their engagement with APCs and combat disease by seeking antigen-bearing cells directly. PROVENGE is designed to target the prostate cancer antigen prostatic acid phosphatase (PAP), an antigen that is expressed in more than 95 percent of all prostate cancers.

IMPACT Study Detail

IMPACT (IMmunotherapy for Prostate AdenoCarcinoma Treatment) was a multi-center, randomized, double-blind, placebo-controlled study evaluating 512 men with asymptomatic or minimally symptomatic, metastatic, castrate-resistant prostate cancer. As previously reported in a primary analysis (34.1 months median follow-up; 331 deaths), the IMPACT study met its pre-specified primary endpoint of significantly improving overall survival compared to placebo, demonstrating that PROVENGE increased three-year survival by 38 percent compared to placebo (31.7 percent vs. 23.0 percent), extending median survival by 4.1 months compared to placebo (25.8 months vs. 21.7 months), with a 22.5 percent reduction in the risk of death [HR=0.775] and a p-value of 0.032.

Safety Data Across Controlled Clinical Trials

In controlled clinical trials of PROVENGE, the most common adverse reactions were chills, fatigue, fever, back pain, nausea, joint ache, and headache.  

The most serious adverse reactions were acute infusion reactions (occurring within 1 day of infusion).  Reported reactions included chills, fever, asthenia, dyspnea, hypoxia, bronchospasm dizziness, headache, hypertension, muscle ache, nausea, and vomiting.  In 95.1% of patients reporting acute infusion reactions, the events were mild or moderate.  Fevers and chills generally resolved in less than or equal to 2 days (71.9% and 89.0%, respectively).  

About PROVENGE

PROVENGE is Dendreon's investigational product candidate for men with advanced prostate cancer and may represent the first in a new class of active cellular immunotherapies (ACIs) specifically designed to engage the patient's own immune system against cancer. PROVENGE and other ACIs are uniquely designed to use live human cells to engage the patient's own immune system with the goal of eliciting a specific long-lasting response against cancer.  Dendreon is seeking licensure for PROVENGE for men with metastatic CRPC and submitted an amended Biologics License Application for PROVENGE, for which the U.S. Food and Drug Administration assigned a Prescription Drug User Fee Act date of May 1, 2010.

About Dendreon

Dendreon Corporation is a biotechnology company whose mission is to target cancer and transform lives through the discovery, development and commercialization of novel therapeutics. The Company applies its expertise in antigen identification, engineering and cell processing to produce active cellular immunotherapy product candidates designed to stimulate an immune response. Dendreon is also developing an orally-available small molecule that targets TRPM8 that could be applicable to multiple types of cancer. The Company is headquartered in Seattle, Washington and has manufacturing facilities in New Jersey, Georgia and California. Dendreon 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 and requisite receipt of FDA licensure for marketing and the risk that additional capital could be needed in the future for the potential commercialization of 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.

SOURCE Dendreon Corporation