Dynavax Technologies announces first clinical data for HEPLISAV investigational hepatitis B vaccine

Dynavax Technologies Corporation (Nasdaq: DVAX) today announced the first clinical data for HEPLISAV^TM investigational hepatitis B vaccine in chronic kidney disease patients. These data will be presented in a poster session on Saturday, October 31, 2009 at the 47^th Annual Meeting of the Infectious Disease Society of America (IDSA) in Philadelphia, Pennsylvania.

Vaccinated with HEPLISAV, chronic kidney disease patients demonstrated rapid, increased protection against hepatitis B viral infection in fewer doses than patients receiving licensed vaccine. 96% of patients (n = 36) receiving 3 doses of HEPLISAV achieved seroprotection at month 7, compared to 88% of patients (n = 10) receiving 8 doses of Engerix-B^®. Dynavax recently began vaccinating chronic kidney disease patients with HEPLISAV in a Phase 3 registration trial.

“For chronic kidney disease patients at increased risk of exposure to hepatitis B viral infection, achieving rapid and efficacious protection is critical," commented Shelly McNeil, M.D., Canadian Center for Vaccinology, Halifax, Nova Scotia and Principal Investigator. "A vaccine that provides faster, superior immunogenicity with a more convenient dosing regimen could offer significant clinical benefits for hyporesponsive chronic kidney disease patients and the dialysis centers that routinely immunize these patients."

HEPLISAV Chronic Kidney Disease Data

Two single-blind, randomized, multi-center studies were conducted in 87 chronic kidney disease patients. In both studies, HEPLISAV was safe and well tolerated.

• In the first trial, 46 patients were randomized to receive 3 doses of HEPLISAV (HBsAg-ISS), administered at 0, 1, and 6 months, or 8 doses of Engerix-B licensed vaccine, administered at 0, 1, 2, and 6 months.
• In the second trial, 41 patients were enrolled to receive 3 doses of HEPLISAV, administered at 0, 1 and 6 months. This trial was halted after patients received two doses of HEPLISAV.

In the first trial, seroprotection rates were higher and achieved earlier for patients receiving HEPLISAV than for patients receiving Engerix-B.

In the second trial, seroprotection rates were 10% post first immunization, 59% post second immunization, and 100% at month 6 without any additional immunizations. Complete data from this second trial will be presented at a future medical conference.

At all time points, consistently higher geometric mean concentration (GMCs) of anti-HBsAg were observed in the HEPLISAV groups compared to the Engerix-B group. In the chronic kidney disease patient population, higher anti-HBsAg titers are important in maintaining seroprotection for a longer period of time.

In the first trial in 46 subjects, GMCs were as follows:

• Measured 1 month after the last dose of vaccine, 89% of patients receiving HEPLISAV achieved anti-HBsAg titers above 100 mIU/mL, compared to 63% of patients receiving Engerix-B.
• Measured 6 months after the last dose of vaccine, 86% of patients receiving HEPLISAV maintained anti-HBsAg titers above 100 mIU/mL, compared to 33% of patients receiving Engerix-B.