Dynavax and Merck & Co., Inc. Update Status of Clinical Hold of Investigational Vaccine...

Dynavax and Merck & Co., Inc. Update Status of Clinical Hold of Investigational Vaccine HEPLISAV(TM)

BERKELEY, Calif. & WHITEHOUSE STATION, N.J.--(Business Wire)--
Dynavax Technologies Corporation (Nasdaq:DVAX) and Merck & Co,
Inc. announced today the receipt of formal written notification from
the US Food and Drug Administration (FDA) detailing a request for
information relating to the previously announced clinical hold placed
on the two Investigational New Drug Applications for HEPLISAV(TM), an
investigational hepatitis B vaccine being jointly developed by Dynavax
and Merck for use in adults and in patients with end stage renal
disease. The FDA is requesting a review of clinical and preclinical
safety data for HEPLISAV. Additionally, the FDA has requested all
available information about the single case of Wegener's
granulomatosis reported in the Phase 3 trial. Dynavax and Merck plan
to provide a complete response to the FDA query in a timely manner.
The FDA will then determine whether the data provided are satisfactory
for the continuation of the clinical program.

About Dynavax

Dynavax Technologies Corporation discovers, develops, and intends
to commercialize innovative TLR9 agonist-based products to treat and
prevent infectious diseases, allergies, cancer, and chronic
inflammatory diseases using versatile, proprietary approaches that
alter immune system responses in highly specific ways. Our TLR9
agonists are based on immunostimulatory sequences, or ISS, which are
short DNA sequences that enhance the ability of the immune system to
fight disease and control chronic inflammation. Our product candidates
include: HEPLISAV, a hepatitis B vaccine in Phase 3 partnered with
Merck & Co. Inc.; TOLAMBA(TM), a ragweed allergy immunotherapy in
Phase 2; a therapy for non-Hodgkin's lymphoma (NHL) in Phase 2 and for
metastatic colorectal cancer in Phase 1; and a therapy for hepatitis B
also in Phase 1. Our preclinical asthma and COPD program is partnered
with AstraZeneca. The National Institutes of Health (NIH) partially
funds our preclinical work on a vaccine for influenza. Symphony
Dynamo, Inc. (SDI) funds our colorectal cancer trials and our
preclinical hepatitis C therapeutic program, and Deerfield Management
has committed funding for our allergy programs. While Deerfield, NIH
and SDI provide program support, Dynavax has retained rights to seek
strategic partners for future development and commercialization. For
more information, please visit http://www.dynavax.com.

About Merck

Merck & Co., Inc. is a global research-driven pharmaceutical
company dedicated to putting patients first. Established in 1891,
Merck currently discovers, develops, manufactures and markets vaccines
and medicines to address unmet medical needs. The Company devotes
extensive efforts to increase access to medicines through far-reaching
programs that not only donate Merck medicines but help deliver them to
the people who need them. Merck also publishes unbiased health
information as a not-for-profit service. For more information, visit
www.merck.com.

Dynavax Forward-looking Statement

This press release contains "forward-looking statements,"
including statements related to the clinical status of HEPLISAV, the
nature and timing of communications with the FDA regarding the current
clinical hold and whether or not and under what additional
requirements, if any, further clinical development will be permitted.
Actual results may differ materially from those set forth in this
press release due to the risks and uncertainties inherent in our
business, including difficulties or delays in development, initiation
and completion of clinical trials, the results of clinical trials and
the impact of those results on the initiation and completion of
subsequent trials and issues arising in the regulatory process;
achieving our Merck collaborative agreement objectives and obtaining
regulatory approval for HEPLISAV; the scope and validity of patent
protection and the possibility of claims against us based on the
patent rights of others; our ability to obtain additional financing to
support our operations; and other risks detailed in the "Risk Factors"
section of our Annual Report on Form 10-K. We undertake no obligation
to revise or update information herein to reflect events or
circumstances in the future, even if new information becomes
available.

Merck Forward-Looking Statement

This press release contains "forward-looking statements" as that
term is defined in the Private Securities Litigation Reform Act of
1995. These statements are based on management's current expectations
and involve risks and uncertainties, which may cause results to differ
materially from those set forth in the statements. The forward-looking
statements may include statements regarding product development,
product potential or financial performance. No forward-looking
statement can be guaranteed and actual results may differ materially
from those projected. Merck undertakes no obligation to publicly
update any forward-looking statement, whether as a result of new
information, future events, or otherwise. Forward-looking statements
in this press release should be evaluated together with the many
uncertainties that affect Merck's business, particularly those
mentioned in the risk factors and cautionary statements in Item 1A of
Merck's Form 10-K for the year ended Dec. 31, 2007, and in its
periodic reports on Form 10-Q and current reports on Form 8-K, if any,
which the Company incorporates by reference.

Dynavax
Investor Relations and Media
Shari Annes, 1-510-665-7210 (office)
cell: 1-650-888-0902
sannes@dynavax.com
or
for Merck
Investor Relations
Graeme Bell, 1-908-423-5185
or
Global Communications
Kelley P. Dougherty, 1-215-652-0059

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