By Kim Coghill

Washington Editor

Seattle-based Corixa Corp. initiated a Phase III pivotal study of its RC-529 synthetic adjuvant when used in combination with AgB, a commercially approved vaccine, for the prevention of hepatitis B virus (HBV) infection.

The study is a randomized, controlled test to compare the efficacy and safety of AgB plus RC-529 to AgB alone in healthy adults who are not immune to HBV. Healthy adults will be randomized to one of two treatment arms and will receive three intramuscular injections of either AgB plus RC-529 or AgB alone on days 0, 30 and 180. Corixa will evaluate the number of subjects who become seroprotected at day 90 following two vaccinations with AgB plus RC-529 compared to AgB alone.

Corixa officials could not be reached for comment.

Commercial vaccines based on hepatitis B surface antigen (HBsAg) are currently available and are safe and effective in prophylactic reduction in the incidence of HBV infection. AgB, which contains recombinant hepatitis B surface antigen and alum, is an approved hepatitis B vaccine in Argentina.

RC-529, an aminoalkyl glucosaminide 4-phosphate molecule, when added to certain vaccines, has been shown in preclinical experiments to enhance the specific immune response to the vaccine antigen.

According to the World Health Organization, of the 2 billion people who have been infected with the hepatitis B virus, more than 350 million have chronic infections, which increase the risk of death from cirrhosis of the liver and liver cancers.

Corixa's stock (NASDAQ:CRXA) fell $1 Thursday to close at $23.