Vical Expands Clinical Testing of DNA Vaccine Against H5N1 Pandemic Influenza

SAN DIEGO, Dec. 6 /PRNewswire-FirstCall/ -- Vical Incorporated (Nasdaq: VICL) today announced the expansion as planned of Phase 1 testing of the company's Vaxfectin(TM)-formulated plasmid DNA (pDNA) pandemic influenza vaccine to allow comparison of vaccination with needle and syringe to vaccination with the Biojector(R) 2000 needle-free injection system. The Biojector(R) 2000 needle-free injection system has been shown to enhance the immunogenicity of pDNA vaccines in previous animal studies, and has demonstrated encouraging safety and immunogenicity data in multiple human pDNA vaccine studies.

Needle and syringe testing in up to 60 subjects, following successful completion of initial safety evaluations, is now being tested at the highest planned dose. Needle-free testing is being conducted in up to 50 subjects at the two highest doses. All tests are double-blind and placebo-controlled, and are designed to evaluate safety, tolerability and immune responses.

"In August, we began our first human trial of a vaccine incorporating the novel Vaxfectin(TM) adjuvant," said Larry R. Smith, Ph.D., Vical's Vice President of Vaccine Research, "and we have now initiated the first human testing of a Vaxfectin(TM)-formulated vaccine delivered by needle-free injection. These advances are crucial steps in developing alternative vaccines for the prevention of pandemic influenza, and in pursuing potential future vaccine applications."

Vical's vaccine contains three individual plasmids encoding consensus sequences of two highly-conserved influenza virus proteins -- nucleoprotein (NP) and ion channel protein (M2) -- and a hemagglutinin (HA) surface protein from the H5N1 influenza virus strain, A/Vietnam/1203/04. The combination is designed to elicit both T-cell and antibody immune responses against emerging strains of influenza virus that have the potential to become pandemic. A monovalent pDNA vaccine encoding only the H5 protein will also be tested. Both vaccines are formulated with the company's Vaxfectin(TM) adjuvant, which has demonstrated effectiveness with a variety of pDNA vaccines in multiple animal models. It has also demonstrated dose-sparing and immune-enhancing ability with conventional seasonal and pandemic influenza vaccines in animals.

Pandemic Influenza Vaccine Background

Vical's pandemic influenza vaccine program goal is to design a vaccine that can be developed and manufactured quickly and safely without handling the infectious organism, provide cross-strain protection, and be stockpiled longer and in less restrictive conditions than conventional vaccines. Vical systematically tested prototype vaccines using a range of viral antigens to determine the optimum combination of conserved and variable targets. The company then systematically tested different formulations for maximum efficacy at the lowest possible dose. Initial virus challenge studies at Vical with Vaxfectin(TM)-formulated vaccines encoding NP, M2 and HA demonstrated significant protection in mice against H1N1 and H3N2 strains of human influenza. Subsequent studies at St. Jude Children's Research Hospital demonstrated complete protection with a single dose of the trivalent vaccine against a lethal challenge in ferrets with the highly pathogenic A/Vietnam/1203/04 (H5N1) influenza virus strain. Funding for the preclinical development was provided under a previously-announced grant from the National Institutes of Health.

About Vaxfectin(TM)

Vaxfectin(TM) is a novel cationic lipid formulation optimized by Vical to increase the immune response to pDNA vaccines. Vaxfectin(TM) formulations have demonstrated safety and adjuvant activity in pDNA vaccine applications in multiple animal models, including nonhuman primates. In addition to the influenza studies cited above, studies of pDNA vaccines against cytomegalovirus and measles have shown enhanced immunogenicity in rodent and nonhuman primates, respectively. In addition, Vaxfectin(TM) has demonstrated dose-sparing attributes as an adjuvant for protein-based influenza 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.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 Vaxfectin(TM)-formulated pandemic influenza DNA vaccine candidate; whether needle and syringe delivery or needle-free delivery of the vaccine will be safe and tolerable, or effective in eliciting immune responses; whether H5N1 or other strains of avian influenza will emerge as pandemic threats; whether the Vaxfectin(TM) adjuvant or needle-free delivery will be applied with other vaccine candidates; whether results from the pandemic influenza vaccine studies will be predictive of results in other vaccine applications; whether the company's DNA vaccine candidate will be effective in protecting humans against H5N1 or other strains of avian influenza; whether development of a pandemic influenza vaccine would lead to development of a seasonal influenza vaccine; whether results in mouse and ferret studies will be predictive of results in human studies; whether the influenza 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 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.

Contact: Alan R. Engbring

SOURCE Vical Incorporated