VaxGen Inc and the Chemo-Sero-Therapeutic Research Institute (Kaketsuken) have entered into initial agreements that will allow VaxGen to initiate development of Kaketsuken's attenuated smallpox vaccine for use in the United States. VaxGen believes that the vaccine, licensed in Japan in 1980, will have a better safety profile, yet be equally effective, compared to smallpox vaccines currently available in the United States.

The vaccine, LC16-Kaketsuken, already has been administered to approximately 50,000 Japanese children, in whom no serious side effects were observed. "In a field trial of 50,000 persons, (the vaccine) was found to produce a markedly lower frequency of reactions than that noted for other strains" of vaccinia used to make smallpox vaccines, according to the authoritative reference, Vaccines. (Stanley A. Plotkin, and Walter A. Orenstein, 1999)

The vaccine gives a pock, or "take", at the site of injection at a rate similar to smallpox vaccines currently stockpiled in the United States. The "take" has long been accepted by public health authorities as evidence of successful immunization against smallpox. The vaccine is based on the LC16m8 clone of the internationally accepted Lister strain of vaccinia virus.

The agreement calls for VaxGen to initiate clinical trials with LC16-Kaketsuken in the U.S., which VaxGen expects to start early next year, subject to consent from the U.S. Food and Drug Administration (FDA). VaxGen will be responsible for clinical development and related activities necessary to meet the requirement for licensure through the FDA. VaxGen and Kaketsuken are currently negotiating the extension of their partnership to address vaccine supply and commercialization.

"LC16-Kaketsuken may offer a valuable alternative to conventional and new non-attenuated vaccines for protecting people against the threat of smallpox as a bioterrorist weapon," said Lance K. Gordon, VaxGen's chief executive. "We believe this vaccine could be an essential tool in the U.S. biodefense arsenal if it can be shown to meet U.S. requirements."

In a corporate statement, Kaketsuken added: "We look forward to working with VaxGen on this very important initiative. Through this partnership, we intend to make LC16-Kaketsuken available to the United States to help protect its citizens against the threat of smallpox."