Dendreon Corporation Announces Presentation of PROVENGE® (sipuleucel-T) Data at the 2013 European Cancer Congress

  Dendreon Corporation Announces Presentation of PROVENGE® (sipuleucel-T) Data
  at the 2013 European Cancer Congress

  *Phase II Study Demonstrates Robust Immune Response When PROVENGE is
    Administered with Abiraterone Acetate
  *Data Indicate Immunological Memory in Patients Retreated with PROVENGE
    Several Years After Initial Treatment

ECC 2013

Business Wire

SEATTLE -- September 27, 2013

September 27, 2013 – Dendreon Corporation (NASDAQ: DNDN) announced today the
presentation of data from clinical studies featuring PROVENGE^®
(sipuleucel-T), an autologous cellular immunotherapy for metastatic
castrate-resistant prostate cancer (mCRPC), at the 2013 European Cancer
Congress in Amsterdam, September 27-October 1, 2013. Preliminary Phase II data
surrounding DN24-02, an investigational autologous cellular immunotherapy for
patients with surgically resected HER2+ urothelial cancer, will also be
presented.

Preliminary data from a Phase II combination study demonstrated that PROVENGE
product potency and immunological prime-boost responses are maintained when
administered concurrently or sequentially with abiraterone acetate (AA) plus
prednisone. Additionally, preliminary data from an ongoing open-label study of
PROVENGE treatment in men with mCRPC who were previously treated with PROVENGE
in the androgen dependent prostate cancer (ADPC) setting suggest long-lived
immunological memory to PROVENGE years following initial treatment.

“The data presented at this Congress surrounding PROVENGE and DN24-02 further
our understanding of the potential benefits of these personalized
immunotherapies,” said Mark Frohlich, M.D., executive vice president of
research and development and chief medical officer at Dendreon. “The ability
to sequence treatments such as PROVENGE with other therapies has the potential
to transform the treatment of advanced prostate cancer, particularly in the
current oncology landscape with the encouraging results from immunotherapy
combination regimens.”

Studies evaluating PROVENGE and DN24-02 data at the 2013 European Cancer
Congress include:

PROVENGE:

  *A Phase II Trial of Sipuleucel-T in Combination with Concurrent or
    Sequential Abiraterone Acetate (AA) in Patients with Metastatic
    Castrate-Resistant Prostate Cancer (mCRPC) [Abstract 2860]. Data from a
    Phase II study suggested that PROVENGE can be successfully manufactured
    during concurrent AA plus prednisone treatment without affecting PROVENGE
    product potency and immunological prime-boost responses.
    Poster Discussion Session: Genitourinary Malignancies – Prostate Cancer,
    Monday, September 30, 11:30 AM CEST, Hall 7.2 Lead Author: Eric Small,
    M.D., University of California, San Francisco, CA

  *P10-1, an Open-Label, Multicenter Study of Sipuleucel-T in Men with
    Metastatic Castrate-Resistant Prostate Cancer (mCRPC) Previously Treated
    with Sipuleucel-T: Analysis of Immunological Data [Abstract 2909].
    Preliminary data from an open-label study designed to evaluate the product
    potency and immune response to retreatment with PROVENGE suggested
    immunological memory to PROVENGE several years following initial
    treatment, and retreatment appeared to boost immunological measures. The
    patients were initially treated with PROVENGE when they had ADPC, and were
    retreated after they had progressed to mCPRC. The safety and effectiveness
    of PROVENGE has not been established for treatment of ADPC.
    General Poster Session: Genitourinary Malignancies – Prostate Cancer,
    Monday, September 30, 9:30 AM – 12:00 PM CEST, Hall 4 Lead Author: Tomasz
    Beer, M.D., Oregon Health & Science University, Knight Cancer Institute,
    Portland, OR

  *Preliminary Product Parameters from P11-1, a Phase II, Open-Label Trial of
    Sipuleucel-T in European Men with Metastatic Castrate-Resistant Prostate
    Cancer (mCRPC) [Abstract 2900]. Preliminary data demonstrated the
    manufacture of PROVENGE can be performed successfully by a European
    facility that serves multiple nations and resulted in a similar product
    parameter profile as PROVENGE manufactured in the U.S.
    General Poster Session: Genitourinary Malignancies – Prostate Cancer,
    Monday, September 30, 9:30 AM – 12:00 PM CEST, Hall 4 Lead Author: Peter
    Mulders, M.D., Radboud University Nijmegen Medical Centre, Netherlands

  *Metastatic Disease Detection is an Important Cause of Screen Failures in a
    Phase II Trial Evaluating the Optimal Sequence of Androgen Deprivation
    Therapy and Sipuleucel-T in Hormone-Naïve Patients with
    Biochemically-Recurrent Prostate Cancer (BRPC) [Abstract 2903]. Data
    analysis from the Phase II study indicated a high frequency of
    radiographic metastatic disease in the setting of hormone-naïve BRPC,
    which highlights the importance of screening for metastases in this
    early-stage patient population.
    General Poster Session: Genitourinary Malignancies – Prostate Cancer,
    Monday, September 30, 9:30 AM – 12:00 PM CEST, Hall 4 Lead Author: Adam
    Kibel, M.D., Dana-Farber Cancer Institute, Boston, MA

DN24-02:

  *NeuACT, a Phase II Randomised, Open-Label Trial of DN24-02 in Patients
    with Surgically Resected HER2+ Urothelial Cancer at High Risk for
    Recurrence: Updated Analysis of Product Parameters and Safety [Abstract
    2907]. A preliminary analysis demonstrated positive immune responses to
    DN24-02, and suggested that antigen presenting cell activation is
    comparable to that of PROVENGE.
    General Poster Session: Genitourinary Malignancies – Prostate Cancer,
    Monday, September 30, 9:30 AM – 12:00 PM CEST, Hall 4 Lead Author: Dean
    Bajorin, M.D., Memorial Sloan-Kettering Cancer Center, New York, NY

  *HER2 Tissue Expression in NeuACT, a Phase II, Randomised, Open-Label Trial
    of DN24-02 in Patients with Surgically Resected HER2+ Urothelial Cancer
    (UC) at High Risk for Recurrence [Abstract 2928]. An interim analysis
    demonstrated a high prevalence of HER2 protein expression in high-risk UC,
    which is consistent with prior studies noting a higher incidence in UC
    lymph node tumors compared with primary tumors.
    General Poster Session: Genitourinary Malignancies – Prostate Cancer,
    Monday, September 30, 9:30 AM – 12:00 PM CEST, Hall 4 Lead Author: Michael
    Press, M.D., University of Southern California Norris Comprehensive Cancer
    Center, Los Angeles, CA

“These preliminary data are encouraging, and suggest that combining
sipuleucel-T and abiraterone acetate plus prednisone is possible. It is not
known if the potential for an immunostimulatory effect from low testosterone
levels achieved with abiraterone may be offset by the potentially
immunosuppressive effects of prednisone,” said Eric J. Small, M.D., professor
of medicine and chief, Division of Hematology and Oncology, University of
California San Francisco and deputy director, Helen Diller Family
Comprehensive Cancer Center. “This study demonstrated that the
co-administration of sipuleucel-T with abiraterone acetate and prednisone was
generally well tolerated, and did not affect the product characteristics of
sipuleucel-T nor its capacity to show an immune response.”

The European Commission (EC) recently granted marketing authorization for
PROVENGE ^ (autologous peripheral blood mononuclear cells activated with
PAP-GM-CSF or sipuleucel-T) dispersion for infusion in the European Union (EU)
for the treatment of asymptomatic or minimally symptomatic metastatic
(non-visceral) castrate-resistant prostate cancer in male adults in whom
chemotherapy is not yet clinically indicated.

About PROVENGE

U.S. Indication and Important Safety Information

PROVENGE^® (sipuleucel-T) is an autologous cellular immunotherapy indicated
for the treatment of asymptomatic or minimally symptomatic metastatic castrate
resistant (hormone refractory) prostate cancer. PROVENGE is intended solely
for autologous use and is not routinely tested for transmissible infectious
diseases.

The safety evaluation of PROVENGE was based on 601 prostate cancer patients in
four randomized clinical trials who underwent at least one leukapheresis. The
most common adverse events (incidence greater-than or equal to 15%) are
chills, fatigue, fever, back pain, nausea, joint ache, and headache. Serious
adverse events reported in the PROVENGE group include acute infusion reactions
(occurring within 1 day of infusion) and cerebrovascular events. In controlled
clinical trials, severe (Grade 3) acute infusion reactions were reported in
3.5% of patients in the PROVENGE group. Reactions included chills, fever,
fatigue, asthenia, dyspnea, hypoxia, bronchospasm, dizziness, headache,
hypertension, muscle ache, nausea, and vomiting. No Grade 4 or 5 acute
infusion reactions were reported in patients in the PROVENGE group.

To fulfill a post marketing requirement and as a part of the company's ongoing
commitment to patients, Dendreon will conduct a registry of approximately 1500
patients to further evaluate a small potential safety signal of
cerebrovascular events. In four randomized clinical trials of PROVENGE in
prostate cancer patients, cerebrovascular events were observed in 3.5% of
patients in the PROVENGE group compared with 2.6% of patients in the control
group.

For the FDA approved full prescribing information, please visit
http://www.provenge.com.

AboutDendreon

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/.

Statements in this press release that are not strictly historical in nature
constitute "forward-looking statements." Such statements include, but are not
limited to, statements regarding the expected benefits of the restructuring,
the timing and elements of the restructuring, the timing and form of related
charges, the expected annual operating expense reduction, expectations and
beliefs regarding Dendreon's financial position, profitability and Dendreon's
ability to breakeven and achieve improved performance as a result of the
restructuring, statements regarding sequencing studies, statements regarding
studies to advance understanding of immunotherapy and the treatment of
advanced prostate cancer, statements regarding biomarkers, expectations about
the early detection study, expectations about advancing our pipeline,
expectations regarding reductions of cost of goods sold, expectations
regarding the presentation of clinical data, developments affecting Dendreon's
U.S. and global business and prospects, beliefs and expectations regarding
potential revenue and earnings from product sales, including beliefs regarding
Dendreon's ability to grow sales, expectations regarding market size, target
market, and market opportunity, beliefs regarding the impact of our direct to
consumer advertising, expectations with respect to our sales force execution
and effectiveness, progress generally on commercialization efforts for
PROVENGE, and expectations about clinical trial enrollments. Such
forward-looking statements involve known and unknown risks, uncertainties and
other factors which may cause Dendreon's actual results to be materially
different from historical results or from any results expressed or implied by
such forward-looking statements. These factors include, but are not limited
to, our inability to achieve and sustain commercial success for PROVENGE; the
identification of efficacy, safety or other issues with PROVENGE; a slower
than anticipated adoption by treating physicians of PROVENGE for the treatment
of patients with advanced prostate cancer for a variety of reasons, including
competing therapies, instability in our sales force, the risk that we cannot
replace vacant sales positions on a prompt basis, perceived difficulties in
the treatment process, delays in obtaining reimbursement or for other reasons;
any promotional limitations imposed by the FDA on our ability to commercialize
and market PROVENGE; unexpected difficulties and costs associated with the
rapid expansion of our commercial operations to support the commercial launch
of PROVENGE; the impact of competing therapies on sales of PROVENGE,
manufacturing difficulties, disruptions or delays and other factors discussed
in the "Risk Factors" section of Dendreon's Annual Report on Form 10-Q for the
quarter ended June 30, 2013. All forward-looking statements are qualified in
their entirety by this cautionary statement. Dendreon is providing this
information as of the date of this press release and does not undertake any
obligation to update any forward-looking statements contained in this release
as a result of new information, future events or otherwise.

Contact:

Dendreon Corporation
Corporate Communications
Lindsay Rocco, 862-596-1304
media@dendreon.com
or
Investor Relations
Nicole Soley, 206-455-2220
ir@dendreon.com