Detailed Data From Vical's TransVax(TM) CMV Vaccine Phase 2 Trial Presented in Late-Breaker Session at ICAAC

SAN DIEGO, Sept. 14, 2009 (GLOBE NEWSWIRE) -- Vical Incorporated (Nasdaq:VICL) announced today that detailed results from a four-month interim analysis in an ongoing Phase 2 trial of the company's TransVax(TM) therapeutic cytomegalovirus (CMV) DNA vaccine were presented yesterday in a late-breaker session at the Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC, San Francisco - September 12-15). Marissa Wilck, M.D., an infectious disease vaccine researcher at Brigham and Women's Hospital and one of the lead investigators in the trial, presented the data. The company had previously announced summary interim results from the trial.

"I am very encouraged by these interim results, which suggest that a DNA vaccine may provide clinical benefit in this highly immunocompromised patient population," said Dr. Wilck. "One of the objectives of this Phase 2 trial is to determine the most appropriate endpoints for a Phase 3 trial, and we have made great progress with this interim evaluation. I look forward to seeing final data in the first half of 2010, hopefully leading to a successful Phase 3 trial for this significant unmet medical need."

The trial is evaluating the potential for TransVax(TM) to prevent CMV reactivation in immunosuppressed CMV-seropositive hematopoietic stem cell transplant (HCT) recipients, which could reduce antiviral usage and CMV-associated disease. At the four-month analysis, the TransVax(TM) vaccine demonstrated a 40% reduction compared with placebo in the percentage of recipients experiencing CMV reactivation (30% for the vaccine group vs. 50% for the placebo group). TransVax(TM) vaccine showed a 67% decrease in recurrence of CMV reactivation (7% vs. 21%, respectively), a 35% decrease in duration of viremia (7.8 days vs. 11.9 days, respectively), and a 70% decrease in peak viral load (2,575 copies vs. 8,537 copies, respectively) compared with placebo. TransVax(TM) provided increased cellular immunological responses to both encoded CMV antigens compared with placebo. There was no difference in serious adverse events between the vaccine and placebo groups.

About the TransVax(TM) Phase 2 Trial

TransVax(TM) is a bivalent DNA vaccine containing plasmids (closed loops of DNA) encoding CMV phosphoprotein 65 (pp65) and glycoprotein B (gB) for induction of cellular and humoral immune responses. TransVax(TM) is formulated with a proprietary poloxamer-based delivery system. TransVax(TM) has received orphan drug designation for HCT and solid organ transplant patients.

The Phase 2 trial of TransVax(TM) included two arms. In the donor-recipient arm, vaccine or placebo was administered to both the donors and recipients undergoing stem cell transplants. In the recipient-only arm, vaccine or placebo was administered only to the stem cell transplant recipients. Transplant recipients received doses of vaccine or placebo at 3-5 days prior to the transplant, and again at 21-42 days after, 84 (+/-7) days after, and 196 (+/-14) days after. The recipient-only arm achieved full enrollment of 80 subjects in the fourth quarter of 2008. Data for the interim analysis were collected up to Day 126 for all recipient-only subjects, and 74 subjects (40 in the vaccine group, 34 in the placebo group) were evaluable. Data were unblinded by group, but not by individual subject, as many were still on study.

Interim results included safety and immunogenicity data as well as viral load endpoints based on central laboratory analyses of samples provided from the multiple U.S. trial sites, set at 500 or more viral copies/mL, which was the lower limit of detection by PCR. Occurrence of CMV infection was defined as any occurrence of 500 or more copies/mL during the study. Recurrence of CMV infection was defined as two or more separate episodes of 500 or more copies/mL. Time to initial viral reactivation was defined as the number of days before reaching 500 or more copies/mL. Duration of viremia was defined as the number of days on study with 500 or more copies/mL. Peak viral load was defined as the highest copy number by PCR during study.

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.

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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 technologies, the TransVax(TM) vaccine against CMV reactivation, as well as the company's focus, collaborative partners, and independent and partnered product candidates. Risks and uncertainties include whether Vical or others will continue development of TransVax(TM) or any other product candidates; whether TransVax(TM) will achieve the safety and efficacy endpoints in the Phase 2 trial; whether TransVax(TM) interim Phase 2 results will be predictive of final Phase 2 results; whether Vical or others will advance TransVax(TM) to Phase 3 testing; whether such testing, if conducted, will be successful; whether Vical or its collaborative partners will seek or gain approval to market TransVax(TM) or any other DNA-based human vaccine or therapeutic 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.

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