Publication of Vical's H5N1 Results Paves the Way for H1N1 Clinical Trial

SAN DIEGO, Feb. 24, 2010 (GLOBE NEWSWIRE) -- Vical Incorporated (Nasdaq:VICL) announced today the publication in the online edition of Vaccine1 detailed data from two Phase 1 trials of the company's Vaxfectin®-adjuvanted DNA vaccines for H5N1 (avian-origin) influenza, demonstrating the potential of DNA vaccines for rapid deployment in future pandemics.

"Our Phase 1 results clearly demonstrated the ability of DNA vaccines against H5N1 avian-origin influenza to achieve antibody responses in the same range as conventional vaccines," said Larry Smith, Ph.D., Vical's Vice President of Vaccine Research and the lead author on the paper. "These trials are key to expanding the use of our Vaxfectin® adjuvant as they provided its first successful safety evaluations in humans. We seized the opportunity to further demonstrate the potential of our technology during the 2009 H1N1 pandemic influenza outbreaks. We completed successful pilot lot production and initiated animal immunogenicity testing of a Vaxfectin®-adjuvanted DNA vaccine for H1N1 pandemic influenza before conventional vaccine manufacturers even received the seed virus needed to start production. We published these data in late 2009, and expect to begin a U.S. government-funded Phase 1 clinical trial of our H1 pandemic influenza vaccine soon."

The double-blind, placebo-controlled, dose-escalation H5N1 Phase 1 trials were conducted in approximately 100 healthy volunteers age 18 to 45 at three U.S. clinical sites. The trials were designed to assess safety and immunogenicity following vaccination, and to evaluate monovalent and trivalent Vaxfectin®-formulated H5N1 pandemic influenza DNA vaccines at various doses. The vaccines were well-tolerated in the trial, and induced antibody responses and T-cell responses against a matching strain of influenza virus, and cross-clade antibody responses against different strains. Highlights include:

* H5 antibody responses predictive of protection in up to 67% of evaluable subjects at higher doses, in the same range as published protein-based H5 vaccine results;

* H5 antibody responses that persisted in a majority of responders through end of study at Day 182, suggesting potentially durable protection;

* Antibody responses against H5 influenza virus strains from two different clades, suggesting protection against emerging strains that may not match the vaccine;

* Persistent H5 T-cell responses for at least 6 months in 75% to 100% of evaluable subjects in the various monovalent cohorts, offering broader potential protection than antibodies alone;

* Antibody and/or T-cell responses against one or more antigens in 72% of subjects in trivalent cohorts, including specific responses against conserved influenza virus proteins;

* No significant safety issues observed at any of the vaccine doses tested, clearing the path for additional human trials of Vaxfectin®-adjuvanted vaccines.

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 <http://www.globenewswire.com/newsroom/ctr?d=184984&l=5&a=www.vical.com&u=http%3A%2F%2Fwww.vical.com%2F> www.vical.com<http://www.vical.com>.

The Vical Incorporated logo is available at http://www.globenewswire.com/newsroom/prs/?pkgid=5768<http://www.globenewswire.com/newsroom/ctr?d=184984&l=6&u=http%3A%2F%2Fwww.globenewswire.com%2Fnewsroom%2Fprs%2F%3Fpkgid%3D5768>

This press release contains forward-looking statements subject to risks and uncertainties that could cause actual results to differ materially from those projected. Forward-looking statements include statements about the results of the company's Vaxfectin®-formulated H5N1 influenza DNA vaccine Phase 1 clinical trial, the nonclinical results of the company's Vaxfectin®-formulated H1N1 influenza DNA vaccine, U.S. government funding, Vical's DNA vaccine and Vaxfectin® adjuvant technologies and their potential application in a vaccine against H1N1 influenza, potential human clinical testing of such a vaccine, and potential future directions for the H5N1 and H1N1 influenza vaccine programs. Risks and uncertainties include whether Vical or others will continue development of the H5N1 or H1N1 pandemic influenza vaccines or conduct additional human trials of other Vaxfectin®-adjuvanted vaccines; whether the company's pandemic influenza DNA vaccines will provide durable protection; whether the company's pandemic influenza DNA vaccines will protect against emerging strains that do not match the vaccine; whether T-cell responses will provide broader protection than antibodies alone; whether H5N1 influenza DNA vaccine Phase 1 clinical trial results will be confirmed in larger studies; whether any product candidates will be shown to be safe and efficacious in clinical trials; the timing of clinical trials; whether Vical or its collaborative partners will seek or gain approval to market any 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.

1 (Article in press) Smith LR, et al. Phase 1 clinical trials of the safety and immunogenicity of adjuvanted plasmid DNA vaccines encoding influenza A virus H5 hemagglutinin. Vaccine (2010), doi:10.1016/j.vaccine.2010.01.029.

CONTACT: Vical Incorporated Alan R. Engbring (858) 646-1127 www.vical.com

Posted: February 2010

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