Vaxfectin(R) Enhances Preclinical Immune Responses to Baxter's Cell Culture-Derived Influenza Vaccines

SAN DIEGO, May 6, 2013 (GLOBE NEWSWIRE) -- Vical Incorporated (Nasdaq:VICL) today announced the online publication¹ of Baxter's (Baxter International Inc.) (NYSE:BAX) preclinical evaluations of Vical's Vaxfectin^® adjuvant in combination with Baxter's cell culture-derived seasonal and pandemic influenza vaccines. Simple addition of Vaxfectin^® to the influenza vaccines substantially increased both antibody and T-cell responses compared with nonadjuvanted vaccines in mice and guinea pigs.

Baxter's evaluations of Vaxfectin^®-adjuvanted vs. nonadjuvanted vaccines showed:

• Hemagglutination inhibition (HI) antibody titers up to 20X higher against each of the three influenza virus strains in a trivalent seasonal vaccine;
• HI antibody titers up to 8X higher against the H5N1 influenza virus strain in a monovalent pandemic vaccine;
• T-cell frequencies up to 10X higher for each of the trivalent seasonal vaccine strains; and
• T-cell frequencies up to 22X higher for the monovalent H5N1 strain.

"Seasonal influenza vaccines continue to provide suboptimal levels of efficacy, particularly in the elderly, and a good adjuvant could provide a meaningful boost in immunogenicity," said Larry R. Smith, Ph.D., Vical's Vice President of Vaccine Research and lead author on the paper. "In the pandemic influenza setting, particularly for emerging strains such as the current H7N9 outbreak in Asia, new vaccines become available initially only in very limited quantities. Lower doses of adjuvanted vaccine could provide sufficient efficacy, allowing the limited vaccine supplies to be shared among more people. Vaxfectin^® may have the potential to achieve both immunogenicity enhancement and dose sparing goals."

About Vaxfectin^®

Vaxfectin^® is a novel adjuvant discovered through extensive screening of Vical's lipid portfolio, and represents the best-performing among this new class of adjuvants. A growing library of research supports its broad utility with a variety of infectious disease and cancer applications. Vaxfectin^® has been shown in multiple animal models to significantly increase the antibody and T-cell immune responses to antigens expressed from DNA vaccines. Vaxfectin^® has achieved similar effects with protein-based vaccines for infectious diseases and with tumor-associated antigen peptides for cancer. Three Phase 1 clinical trials of Vaxfectin^®-formulated vaccines against pandemic strains of influenza extended the immunogenicity results to humans, and demonstrated a favorable safety and tolerability profile. Vical is developing Vaxfectin^®-formulated vaccines including CyMVectin™, a prophylactic DNA vaccine against cytomegalovirus (CMV), and a therapeutic DNA vaccine against herpes simplex virus type 2 (HSV-2).

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. Forward-looking statements include statements about Vical's Vaxfectin^® adjuvant, as well as Vical's focus, licensees, and independent and partnered product candidates. Risks and uncertainties include whether Vical, Baxter or others will develop any seasonal or pandemic influenza vaccines using Vical's Vaxfectin^® adjuvant; whether Vical or others will continue development of CyMVectin™, the therapeutic HSV-2 vaccine, or any other Vaxfectin^®-formulated product candidates; whether any Vaxfectin^®-formulated product candidates will be shown to be safe and effective in clinical trials or be commercially scalable; the timing, nature and cost of clinical trials; whether Vical or others will pursue any additional applications for its Vaxfectin^® adjuvant; whether Vical or its collaborative partners will seek or gain approval to market any product candidates; whether Vical or its collaborative partners will succeed in marketing 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.

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¹ Smith L, Kistner O et al. Preclinical evaluation of Vaxfectin^®-adjuvanted vero cell-derived seasonal split and pandemic whole virus influenza vaccines. Human Vaccines & Immunotherapeutics 9:7 (July 2013); http://dx.doi.org/10.4161/hv.24209.

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