On February 24 2003, VaxGen announced that AIDSVAX B/B did not prove effective in the trials conducted in North America and Europe. The study did not show a statistically significant reduction of HIV infection within the study population as a whole, which was the primary endpoint of the trial.

In 1998, the first multicentre phase III trial of AIDSVAX B/B, was conducted principally in Canada and the U.S., but also at some sites in the Netherlands and Puerto Rico.The trial involved more than 5,400 volunteers from the U.S., Canada, and the Netherlands, the majority of whom were men who had sex with men. The trial was completed at the end of 2002.

The second phase III trial was conducted in Thailand with the AIDSVAX B/E vaccine. VaxGen announced in July 2002 that it would be delaying its Biologics License Application (BLA) for AIDSVAX until 2004 to enable the company to fulfil pre-approval manufacturing requirements.

AIDSVAX is based on an earlier monovalent gp120 vaccine developed by Genentech that was shown to be safe in humans. VaxGen (formerly Genenvax) was formed as a spin-off company from Genentech with the sole purpose of developing the gp120 vaccine.