Vical Demonstrates Novel Method of Predicting DNA Vaccine Effectiveness

TORONTO, Oct. 14 /PRNewswire-FirstCall/ -- Vical Incorporated today announced conclusions from anthrax DNA vaccine studies in non-human primates reflecting data presented by Peggy A. Lalor, Ph.D., the company's Executive Director of Preclinical Safety and Efficacy, on Saturday at the annual meeting of the Infectious Diseases Society of America (Toronto, October 12 - 15). Key observations included:

* DNA vaccines encoding protective antigen (PA) elicited protective immunity against lethal anthrax spore challenge that could not be predicted by post-vaccination antibody immune responses. * Anthrax spore challenge resulted in more rapid and significantly higher anti-PA antibody responses and anthrax lethal toxin neutralizing antibody responses in DNA-vaccinated animals than in control animals. * "Pseudochallenge" with anthrax antigen (recombinant PA vaccine) also resulted in more rapid and measurably higher anti-PA antibody responses and anthrax lethal toxin neutralizing antibody responses in DNA-vaccinated animals than in control animals.

Traditional immunoassays following DNA vaccination may not be sufficient to predict vaccine protective efficacy. The results of these studies suggest that the protective efficacy of DNA vaccines may be evaluable by measuring immune responses after a pseudochallenge with the same antigen that was encoded in the DNA vaccine rather than a challenge with the pathogen itself. This method may present a new pathway to evaluation of DNA vaccine efficacy. Financial support for the anthrax vaccine studies was provided under previously-announced grants from the National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH). The recombinant PA vaccine was provided by VaxGen Inc.

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.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 anthrax vaccine; whether results, observations or conclusions from non- human primate studies will be predictive of results, observations or conclusions from human studies; whether evaluation of protective efficacy based on pseudochallenge will become an accepted method; whether the anthrax vaccine or any other product candidates will be shown to be safe and effective; the timing, nature and cost of clinical trials; whether Vical or its collaborative partners will seek or gain approval to market the anthrax vaccine or any other product candidates; whether Vical or its collaborative partners will succeed in marketing the anthrax 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 [phone] [phone] Website: http://www.vical.com/