Promise of Vical's CMV Vaccine Noted by Independent Experts

SAN DIEGO (Map) - SAN DIEGO, June 5 /PRNewswire-FirstCall/ -- In an editorial commentary(1) in the current issue of The Journal of Infectious Diseases (JID), independent experts on cytomegalovirus (CMV) said the vaccine under development by Vical Incorporated (Nasdaq: VICL), at the optimal dose and regimen tested, "holds promise" based on its ability to elicit persistent immune responses in a majority of CMV-seronegative subjects, and warrants further evaluation for its potential to prevent infection and disease. The commentary accompanies the issue's lead article(2), which expands on previously reported immunogenicity data from a Phase 1 study of the immunotherapeutic DNA vaccine.

The senior author on the JID article, Michael J. Boeckh, M.D., said, "Despite antiviral drug therapies, CMV infection continues to be a problem in the transplant setting. CMV immunity appears to play a critical role in controlling viral load and disease in these patients. The ability to stimulate CMV immunity with vaccination may have an important role in the management of CMV infection and disease in transplant patients. Clinical trials are ongoing to test this strategy."

Dr. Boeckh, Associate Member of the Fred Hutchinson Cancer Research Center and Associate Professor at the University of Washington, also is an investigator in Vical's current Phase 2 trial, a double-blind, placebo- controlled study designed to compare safety of the vaccine against placebo in approximately 80 patients scheduled for hematopoietic stem cell transplants. Because most recipients are expected to face a natural viral challenge as pre- existing CMV infection reactivates under immunosuppression, this trial will examine the vaccine's impact on important clinical parameters such as antiviral drug use and viral load in patients receiving vaccine compared with patients receiving placebo. Other important evaluations will include measurement of specific immune responses against CMV targeted by the vaccine.

"We are advancing well toward completion of enrollment in our Phase 2 CMV vaccine trial," said Ronald B. Moss, M.D., Vice President of Clinical Development at Vical, "and are on track for our planned interim evaluation of safety and efficacy data in the second half of 2008. Our immunotherapeutic vaccine may help address the serious healthcare problem of CMV reactivation for transplant patients, and could eventually be useful in preventing birth defects caused by CMV infection of pregnant women."

About CMV

CMV is a herpes virus that infects more than half of all adults in the United States by age 40, and is even more widespread in developing countries. While a healthy immune system typically protects an infected person against CMV disease, it rarely succeeds in completely eliminating the infection, and those whose immune systems are not fully functional are at high risk of CMV proliferation, potentially leading to severe illness or death. These include transplant patients who take immunosuppressive drugs, and fetuses and newborns of mothers who first become infected during pregnancy.

CMV infection affects 30 to 60 percent of the patients undergoing various transplant procedures, causing transplant rejection, serious illness and even death if untreated. Expensive antiviral drug therapy is used to control the disease, but does not eliminate the infection. Congenital CMV infection affects one out of every hundred infants, and causes severe consequences in about 3,600 infants and death in about 400 each year in the United States.

There is no approved vaccine against CMV. Vaccine approaches that result in predominantly antibody responses to CMV have not proven highly effective in transplant patients. Vaccine approaches using live, attenuated viruses can induce both antibody and cellular immune responses, but pose a potential safety concern, particularly for immunocompromised patients, of causing the disease they are intended to prevent. Vical's novel DNA vaccine approach is designed to induce both antibody and cellular immune responses against specific features of the CMV virus without the risk of causing CMV disease. Vical's vaccine has received orphan drug designation for hematopoietic stem cell transplant and solid organ transplant patients.

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 CMV vaccine; whether the company will complete an interim evaluation of safety and efficacy in the Phase 2 trial in the second half of 2008, if at all; whether memory T-cells will result in control of CMV disease; whether the company's DNA vaccine candidate will be effective in protecting humans against CMV disease; whether the company will successfully enroll 80 stem cell transplant recipients in a timely manner, if at all; whether the CMV vaccine will achieve the safety and efficacy endpoints in the Phase 2 trial; whether the company will expand development of a CMV vaccine to address prevention of congenital disease; 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.

(1) Go V, Pollard RB. A Cytomegalovirus Vaccine for Transplantation: Are We Closer? J Infect Dis 2008; (http://www.journals.uchicago.edu/toc/jid/current) 197:1631-3.

(2) Wloch MK et al. Safety and Immunogenicity of a Bivalent Cytomegalovirus DNA Vaccine in Healthy Adult Subjects. J Infect Dis 2008; (http://www.journals.uchicago.edu/toc/jid/current) 197:1634-42.

Contact: Alan R. Engbring

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              Website:  http://www.vical.com