West Coast Editor

Aiming to file a biologics license application in 2007, Dynavax Technologies Inc. began a pivotal Phase III trial to test its Toll-like receptor 9 hepatitis B vaccine against the efficacy of Engerix-B, GlaxoSmithKline plc's HBV vaccine, in older adults.

"There are already two established vaccines," noted Jane Green, vice president of corporate communications for Berkeley, Calif.-based Dynavax, but London-based GSK's product is the market leader, and the one Dynavax intends to beat. The other is Recombivax-HB, made by Merck & Co. Inc., of Whitehouse Station, N.J.

The trial will enroll more than 400 seronegative adults (that is, those with no detectable HBV antibodies), aged 40 to 70 years, a population that especially is hard to immunize, and will take place at study sites in Singapore, Taiwan, Korea and the Philippines.

Randomized and double-blinded, the study will include one group to get three doses of Dynavax's HBV vaccine at a dose of 20 micrograms HBV surface antigen (HBsAg) co-administered with 3 mg of its proprietary immunostimulatory sequence (ISS) technology, by intramuscular injection at zero, two months and six months.

The second group will be given three doses of GSK's Engerix-B at a dose of 20 micrograms HBsAg by the same route at zero, one and six months.

"It's always wise to be conservative" when estimating the length of the trial, Green said, predicting the duration to be "at least a year." Also in 2006, the company will start a second pivotal trial in a younger population at sites in Europe and Canada.

The ISS technology uses short synthetic DNA molecules designed to stimulate Th1 immune response while suppressing Th2 immune response, and is being developed not only as part of the HBV program but also as part of ragweed allergy and asthma studies.

"It functions as an adjuvant," Green said, adding that the ISS is "the fundamental technology the company is pursuing."

In the HBV trial, the primary endpoint is seroprotection four weeks after the third vaccination at month seven, and study subjects will be followed for five months longer. With its TLR-9 vaccine, Dynavax is targeting subjects who need an enhanced vaccine, such as hemodialysis patients, health care and emergency response personnel, people infected with HIV or hepatitis C, and those who get multiple transfusions.

About a week ago, Dynavax reported positive data from a Phase II/III trial with the vaccine, which showed statistically significant superiority in protective antibody response and robustness of protective effect after three vaccinations vs. GSK's product in older adults.

Dynavax's stock (NASDAQ:DVAX) closed Thursday at $3.92, up 7 cents.

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