Provenge Hears from the FDA

Joel T. Nowak, Ma. MSW

Dear Joel,

I wanted to make sure you were aware that late yesterday we received a Complete Response Letter much like an approvable letter from the FDA regarding the application for PROVENGE for the treatment of advanced, metastatic prostate cancer which we just announced in the attached press release.

The letter comes as a major disappointment to us, our employees who have been dedicated to this product for nearly a decade, our clinical investigators and most importantly the patients and families who are in such desperate need of new options to treat this deadly and devastating disease. We remain committed to working with the FDA to pursue the final approval as soon as possible. We hope to have a better idea of our next steps over the coming weeks.

I want to thank you for you’re continued for your support of new therapies like PROVENGE.

Sincerely,

Chris Lockett

Senior Director, Government Affairs

Dendreon Corp.

17411 Ryefield Ct.

Dickerson MD 20842

Office- (301) 349-5403

PRESS RELEASE

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Dendreon Receives Complete Response Letter from FDA For
Provenge
®
Biologics License Application
SEATTLE, WA, May 9, 2007 – Dendreon Corporation (Nasdaq: DNDN) today announced that
it received a Complete Response Letter, commonly referred to as an “approvable” letter, on May
8, 2007 from the U.S. Food and Drug Administration (FDA) regarding its Biologics License
Application (BLA) for PROVENGE (sipuleucel-T) for the treatment of asymptomatic,
metastatic, androgen-independent (also known as hormone refractory) prostate cancer.
The FDA has requested additional clinical data in support of the efficacy claim contained in the
BLA. The Company is seeking a clarification from the FDA as to the nature of the data that is
being requested. The FDA has also requested additional information with respect to the
chemistry, manufacturing and controls (CMC) section of the BLA, which the Company believes
it can supply to the FDA in a timely manner.
“Given our strong belief in the survival benefit and safety profile of PROVENGE, coupled with
the positive outcome of the Advisory Committee meeting, we are disappointed that this decision
will cause a delay in the availability of PROVENGE for patients who suffer from advanced
prostate cancer,” said Mitchell H. Gold, M.D., president and chief executive officer of Dendreon.
“We are committed to working closely with the FDA to resolve these questions in a timely and
efficient manner to bring PROVENGE to patients with advanced prostate cancer who currently
have few appealing treatment options.”
On March 29, 2007, the FDA’s Office of Cellular, Tissue and Gene Therapies Advisory
Committee was asked if the submitted data established that PROVENGE is reasonably safe and
whether there is substantial evidence that the product is efficacious. The Advisory Committee
voted 17 to 0 in favor of the safety of PROVENGE and 13 to 4 in favor of the efficacy of
PROVENGE.
PROVENGE Biologics License Application
Dendreon’s BLA was submitted under a Fast Track designation and was accepted for filing by
the FDA in January 2007. The BLA was based primarily on a multi-center, randomized, double-
blind, placebo-controlled Phase 3 study (D9901) that showed that the group of men with
asymptomatic, metastatic, androgen-independent prostate cancer who received PROVENGE had
a median survival time 4.5 months longer than the median survival seen in the group that had
been assigned to receive placebo. For the men who received PROVENGE, there was a 41
percent overall reduction in the risk of death (p-value = 0.010; HR = 1.7). In addition, 34
percent of patients receiving PROVENGE were alive 36 months after treatment compared to 11
percent of patients randomized to receive placebo.
Treatment with PROVENGE was generally well tolerated. The majority of side effects were
mild, including infusion-related fever and chills that were usually of low grade and typically
lasted for one to two days following infusion.
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Ongoing Clinical Study
IMPACT (IMmunotherapy for Prostate AdenoCarcinoma Treatment) also known as D9902B, is
an ongoing Phase 3 clinical trial measuring overall survival in men with hormone-refractory
prostate cancer receiving PROVENGE versus those receiving placebo.
In order to be eligible to participate in the IMPACT study, a person must meet certain criteria,
such as having cancer that has spread outside the prostate (metastatic) or cancer that has
worsened while on hormone therapy among other additional criteria. Interested patients should
contact the Dendreon Prostate Cancer Information line at 1-866-4PROSTATE (1-866-477-
6782).
About Prostate Cancer
Prostate cancer is the most common non-skin cancer in the United States and the third most
common cancer worldwide. More than one million men in the United States have prostate
cancer, with an estimated 218,890 new cases expected to be diagnosed in 2007, and more than
27,000 men expected to die this year from the disease. Currently there are limited treatment
options for men with advanced, metastatic prostate cancer.
About PROVENGE
PROVENGE is the first in a new class of active cellular immunotherapies (ACIs) that are
uniquely designed to stimulate a patient’s own immune system. Approximately 95% of prostate
cancer cells express an antigen called prostatic acid phosphatase, or PAP. PROVENGE is
designed to help the man’s immune cells recognize cells that carry PAP as a foreign antigen and
attack those cells.
About Active Cellular Immunotherapy
Active cellular immunotherapy is an approach that uses live human cells to re-engage the
patient’s own immune system. The goal of active cellular immunotherapy is to turn the immune
system “back on” to elicit a specific long-lasting response against cancer. While ACIs are being
studied in various cancers, prostate cancer is the first to be treated with them.
Activated T cells may be the immune system’s most potent defense against cancer. Although a
variety of immune cells participate in the surveillance and elimination of cancer cells, T cells are
uniquely endowed to kill specific tumor cell types. When activated to recognize tumor-
associated antigens, T cells proliferate and attack cells bearing those antigens. For this reason,
the goal of many investigational ACIs is to stimulate and optimize activation of T cells.
The cellular orchestrators of T cell activation are antigen presenting cells (APCs). When
encountering tumor-associated antigens in the body, APCs process and display the antigens, and
then present them to T cells. When activated by APCs, T cells may recognize and lyse cells
bearing those antigens.
PROVENGE’s approach entails ex vivo activation of APCs with tumor-associated antigens.
Dendreon’s proprietary Antigen Delivery Cassette™ is a protein that enhances antigen binding
and entry into APCs. The Antigen Delivery Cassette targets each engineered antigen to a
receptor on APCs and provides a common key to unlock the potential of these cells to process
antigen. The APCs process antigen along pathways that stimulate cell-mediated immunity.
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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
that harness the immune system to fight cancer. 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. Active cellular immunotherapy holds
promise because it may provide patients with a meaningful clinical benefit, such as survival,
combined with low toxicity. The Company has headquarters 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 www.dendreon.com.
Except for historical information contained herein, this news release contains forward-looking
statements that are subject to risks and uncertainties surrounding the efficacy of PROVENGE to
treat men suffering from prostate cancer, risks and uncertainties surrounding the presentation of
data to the FDA and approval of product applications by the FDA and 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 differences include risks
related to our limited operating history, risks associated with completing our clinical trials, the
risk that the safety and/or efficacy results of existing clinical trials or from additional clinical
trials for PROVENGE will not support approval for a biologics license, the risk that the FDA
may interpret data differently than we do or require more data or a more rigorous analysis of
data than expected, the risk that the FDA will not approve a product for which a biologics
license has been applied, the risk that the results of a clinical trial for PROVENGE or other
product may not be indicative of results obtained in a later clinical trial, risks that we may lack
the financial resources and access to capital to fund required clinical trials or
commercialization of PROVENGE, our 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 public disclosure filings with the U.S. Securities and Exchange Commission, which
are available at www.sec.gov.
# # #
Contact:
Monique Greer
Sr. Director, Corporate Communications
Dendreon Corporation
(206) 829-1500
Katherine Stueland
WeissComm Partners
(312) 208-0320