Vical Demonstrates Dose-Sparing of Protein-Based H5N1 Influenza Vaccine With Vaxfectin Adjuvant

LYON, France, October 09, 2007 /PRNewswire-FirstCall/ -- Vical Incorporated today announced that data from a study in mice demonstrated the potential of its patented Vaxfectin(TM) adjuvant to be used as a dose-sparing agent with a protein-based H5N1 pandemic influenza vaccine currently stockpiled by the U.S. government. Dose-sparing ability could be critical in extending limited vaccine supplies to protect the greatest number of people in the event of a pandemic influenza outbreak. Alain Rolland, Pharm.D., Ph.D., Vical's Senior Vice President of Product Development, presented the data at the World Vaccine Congress (Lyon, France, October 8 - 10).

Vaxfectin(TM)-formulated Measles DNA Vaccine

The company also announced that a measles DNA vaccine formulated with the company's Vaxfectin(TM) adjuvant elicited sustained protective levels of neutralizing antibodies in infant (6 - 10 week old) nonhuman primates confirmed by complete protection following challenge one year after intradermal vaccination, with no clinical signs of disease and no culturable virus after challenge. In May, the company announced similar results in juvenile (1 - 2 year old) nonhuman primates. Both measles studies were conducted in collaboration with Diane E. Griffin, M.D., Ph.D., Alfred and Jill Sommer Professor and Chair of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, under a grant from the Bill and Melinda Gates Foundation.

"We continue to expand the database demonstrating the dose-sparing and immunogenicity-enhancing capabilities of our Vaxfectin(TM) adjuvant," said Dr. Rolland, "as well as its potential safety and tolerability advantages. Our lead DNA vaccine candidate against H5N1 influenza, formulated with Vaxfectin(TM), provided 100% protection in mice and ferrets against lethal challenges, and is currently in Phase 1 human testing. We are encouraged by the recent influenza and measles data, and look forward to further evaluation of Vaxfectin(TM)."

Study Details

In the recent influenza study, mice were vaccinated with U.S. government-supplied H5N1 vaccine (rgA/Vietnam/1203/2004 - BEI Resources, Catalog No. NR-4143), with or without the Vaxfectin(TM) adjuvant, and evaluated for antibody responses by Enzyme-Linked ImmunoSorbent Assay (ELISA). After a single injection, the Vaxfectin(TM)-formulated vaccine yielded five-fold higher antibody responses at the same dose as the unformulated vaccine, and comparable or better antibody responses at one-third the dose of unformulated vaccine. After a second injection, the Vaxfectin(TM)-formulated vaccine yielded nine-fold higher antibody responses at the same dose as the unformulated vaccine, and five-fold better antibody responses at one-third the dose of the unformulated vaccine.

In an earlier influenza study, the company demonstrated that the Vaxfectin(TM) adjuvant significantly boosted the immune response to a protein-based seasonal influenza vaccine. Mice were vaccinated with trivalent inactivated influenza vaccine (Sanofi-Pasteur Fluzone(R) 2005-2006 Formula commercial product), with or without the Vaxfectin(TM) adjuvant, and evaluated for antibody responses through hemagglutination inhibition (HI) titers. The Vaxfectin(TM)-formulated vaccine yielded significantly higher antibody responses than the unformulated vaccine at the same dose as well as a dose-sparing effect.

In the recently completed measles study in infant nonhuman primates, neutralizing antibody levels exceeded the accepted protection threshold prior to the second injection at Week 4, peaked at Week 8, and remained above the threshold at least through the 20-week follow-up period. Animals were challenged by intratracheal inoculation after one year, resulting in complete protection of all vaccinated animals. None of the vaccinated animals had disease symptoms or culturable levels of measles virus, in contrast to negative control animals which all had rashes and positive virus cultures. No adverse events related to the vaccination were observed.

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 evaluation of Vaxfectin(TM) as an adjuvant for vaccines against influenza or measles; whether Vaxfectin(TM) will be used as a dose-sparing agent with conventional influenza vaccines against seasonal or pandemic influenza strains; whether Vical or others will continue development of the pandemic influenza or measles DNA vaccine candidates; whether H5N1 or other strains of influenza will emerge as pandemic threats; whether the company's DNA vaccine candidate will be effective in protecting humans against H5N1 or other strains of influenza; whether the measles vaccine will be effective in protecting juvenile or infant humans against infection or disease; whether the influenza or measles vaccines 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 influenza vaccine or any other product candidates; whether Vical or its collaborative partners will succeed in marketing the influenza 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:  http://www.vical.com

CONTACT: 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

Web site: http://www.vical.com/

Ticker Symbol: (NASDAQ-NMS:VICL)

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Posted: October 2007

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