Title: Vical DNA Vaccine Elicits Lasting Memory T-cell Immune
Responses in Humans Date: 5/14/2007 6:30:00 AM
TOULOUSE, France, May 14, 2007 /PRNewswire-FirstCall via COMTEX News Network/ -- Vical
Incorporated (Nasdaq: VICL) announced today that antigen-specific memory T-cell responses
to cytomegalovirus (CMV), which may be important in protecting against CMV disease, were
detected six months after DNA vaccination in a majority of CMV-seronegative subjects in a
previously completed Phase 1 study. Memory T-cells are known to respond quickly upon
subsequent infection with virus, transforming into active, effector T-cells that can
control disease.
The company previously detected transient vaccine-induced effector T-cells in a
minority of subjects in the same Phase 1 study using an ex vivo ELISPOT assay. The recent
results were obtained with a highly sensitive alternative assay, a cultured ELISPOT assay,
which detects memory T-cells. "We are seeing a growing body of evidence that assays
measuring only effector immune responses may underestimate the extent of T-cell priming by
DNA vaccination," said Larry Smith, Ph.D., Vical's Vice President of Vaccine
Research. "An assay that measures pathogen-specific immune memory may provide a more
meaningful metric for DNA vaccines. We view the cultured ELISPOT assay results as an
important step toward understanding responses to DNA vaccination in humans and in
advancing DNA vaccines toward approval."
The highly sensitive cultured interferon-gamma ELISPOT assay detected memory T-cell
immune responses in 15 of 22 CMV-seronegative subjects (68%) using archived samples from
the company's completed Phase 1 trial of its bivalent DNA vaccine encoding CMV
phosphoprotein 65 (pp65) and glycoprotein B (gB). Memory T-cell responses against these
antigens were detected 10 to 12 weeks after the first vaccine dose and persisted for at
least 24 weeks after the last vaccine dose (the last point in time for which specimens
were available). Antigen-specific memory responses were detected by the cultured ELISPOT
assay in some subjects who failed to show effector T-cell responses at any point in time
by an ex vivo ELISPOT assay.
Mary K. Wloch, Ph.D., the company's Associate Director of Vaccinology, presented the
data at the 11th International Cytomegalovirus/Betaherpes Virus Workshop (Toulouse,
France, May 13 - 17). Vical conducted these studies in part under a grant from the
National Institutes of Health.
About Vical
Vical researches and develops biopharmaceutical products based on its patented DNA
delivery technologies for the prevention and treatment of serious or life-threatening
diseases. Potential applications of the company's DNA delivery technology include DNA
vaccines for infectious diseases or cancer, in which the expressed protein is an
immunogen; cancer immunotherapeutics, in which the expressed protein is an immune system
stimulant; and cardiovascular therapies, in which the expressed protein is an angiogenic
growth factor. The company is developing certain infectious disease vaccines and cancer
therapeutics internally. In addition, the company collaborates with major pharmaceutical
companies and biotechnology companies that give it access to complementary technologies or
greater resources. These strategic partnerships provide the company with mutually
beneficial opportunities to expand its product pipeline and address significant unmet
medical needs. Additional information on Vical is available at www.vical.com.
This press release contains forward-looking statements subject to risks and
uncertainties that could cause actual results to differ materially from those projected,
including: whether Vical or others will continue development of the CMV vaccine; whether
memory T-cells will result in control of CMV disease; whether the company's DNA vaccine
candidate will be effective in protecting humans against CMV disease; whether the use of
the cultured ELISPOT assay will help advance DNA vaccines toward approval; whether the CMV
vaccine or any other product candidates will be shown to be safe and effective in clinical
trials; the timing, nature and cost of clinical trials; whether Vical or others will seek
or gain approval to market the CMV vaccine or any other product candidates; whether Vical
or others will succeed in marketing the CMV vaccine or any other product candidates; and
additional risks set forth in the company's filings with the Securities and Exchange
Commission. These forward-looking statements represent the company's judgment as of the
date of this release. The company disclaims, however, any intent or obligation to update
these forward-looking statements.
Contacts: Investors: Media:
Alan R. Engbring Susan Neath
Vical Incorporated Porter Novelli Life Sciences
(858) 646-1127 (619) 849-6007
Website: www.vical.com
SOURCE Vical Incorporated
Investors, Alan R. Engbring of Vical Incorporated, +1-858-646-1127; or Media, Susan
Neath of Porter Novelli Life Sciences, +1-619-849-6007, for Vical Incorporated
http://www.vical.com
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