September 4 , 2002

Dynavax Initiates Phase II Clinical Trial of ISS Vaccine for Hepatitis B

Study Focuses on Single-Injection Approach

Dynavax Technologies - BERKELEY, Calif.,-a privately held biopharmaceutical company, today announced it has initiated a Phase II clinical study to evaluate the ability of its ISS (immunostimulatory DNA sequence) vaccine candidate to provide effective hepatitis B prophylaxis in patients after a single injection. The study will compare the protective immune response of patients after immunization with either Engerix-B(R) HBV vaccine, a commercially available hepatitis B vaccine, or recombinant hepatitis B surface antigen (rHBsAg) co-administered with Dynavax's proprietary immunostimulatory DNA sequences (1018-ISS).

Infection with the hepatitis B virus (HBV) is a major global health problem, with 350 million chronically infected individuals worldwide. One third of those with chronic infection develop cirrhosis of the liver and/or liver cancer. "Our ISS vaccine candidate has the potential to be a single-injection product that provides protection against HBV shortly after immunization," said Dino Dina, M.D., president and chief executive officer of Dynavax. "Previous clinical testing suggests its potential to address major limitations with current HBV vaccines -- the number of immunizations required, poor patient compliance in completing the regimen, and percentage of non-responders." As its primary objective, the Phase II observer-blind, randomized study will compare the proportions of subjects achieving seroprotective immune responses four weeks following the first immunization with Engerix-B HBV vaccine versus Dynavax's vaccine, consisting of rHBsAg and 3 milligrams of 1018-ISS. Additional immune response comparisons will be conducted following subsequent immunizations.

Principal investigators for the study are Simon Dobson, M.D., of the Children and Women's Health Centre of British Columbia, and Scott Halperin, M.D., of Dalhousie University and the IWK Health Centre in Halifax, Nova Scotia, Canada.

Results are expected by late 2002. Results from a Phase I/II clinical trial support the potential of the Dynavax ISS vaccine candidate as a single-injection product.

The double blind study compared HBV surface antigen alone and coadministered with 1018-ISS. At the highest dose tested, the coadministered vaccine produced protective antibody titers in 88 percent of subjects after a single administration, and all dose levels were well tolerated. Current commercial vaccines require up to three injections over a period of six months to achieve a comparable level of seroprotection. Development of a hepatitis B vaccine that provides rapid protection would be of major importance in reducing infection, particularly among high-risk individuals, including health care workers.

About Dynavax Technologies
Dynavax Technologies is a privately held biopharmaceutical company developing innovative products to treat allergy, inflammation-mediated diseases, infectious diseases and cancer. The company’s lead products are based on ImmunoStimulatory Sequences (ISS), short DNA sequences that enhance the ability of the immune system to fight disease and prevent inflammation. The company’s two most advanced products are AIC, which has provided positive results in recently completed phase II clinical trials for the treatment of ragweed allergy, and a next-generation hepatitis B vaccine that may offer single-dose protection. Dynavax is also developing an oral TNF-alpha synthesis inhibitor initially for the treatment of rheumatoid arthritis. The company has collaborations with Aventis-Pasteur, Triangle Pharmaceuticals and Stallergenes.

Andrew Gengos
Chief Financial Officer
Dynavax Technologies Corporation
(510) 848-5100