Vaccine for AIDS shows promise

By Steve Sternberg, USA TODAY

The pent-up world of AIDS vaccine research erupted in controversy Monday over a new study showing that an HIV vaccine that failed to protect whites and Hispanics — the majority of the research volunteers — appeared to protect blacks and possibly Asians.

If the study holds up, it would mark the first time that any AIDS vaccine has been shown to protect humans. Blacks account for half of newly infected people in the USA each year.

"The vaccine did not succeed in the white population, but in African-Americans and Asians, at least, the trend is there. You can't ignore it," says Donald Francis, CEO of VaxGen in Brisbane, Calif., the maker of the vaccine.

The vaccine, called AIDSVAX, appears to be 78.3% effective in blacks and 68% effective in Asians. The controversy stems from the fact that blacks numbered just 314 of the roughly 5,400 people in the study, and the number of Asians was so small that doctors can't rule out the possibility that the positive finding was a result of chance.

Researchers familiar with the study, and its findings, say the unexpected benefit among racial minorities is worth pursuing.

"There's been a lot of talk, but nobody's ever seen protection in any of these vaccine studies. It may give us much more insight into what it takes to get protection than we ever had before," says Thomas Merigan, director of the Center for AIDS Research at Stanford University.

Samuel Katz of Duke University, one of the nation's leading vaccine experts and a member of the Food and Drug Administration's vaccine advisory committee, concurs. "If you accept this information about the black and Asian groups, that's totally remarkable and interesting," Katz says. "We need to do more study to see if this is real or just an aberration of small numbers."

"I don't think this is an occasion to scoff and walk away," he says. "I think it's an opportunity to say this is fascinating, we can't explain it, and we need to do some more research."

The vaccine has been controversial from the start. Many researchers dismissed AIDSVAX as unlikely to generate any sort of immune response, though they praise the company's success in mounting a massive clinical trial.

Critics caution that the study as a whole doesn't prove anything and that results from a small subgroup of participants could be misleading.

"The primary endpoint of the trial was negative, zero," says Seth Berkley, director of the International AIDS Vaccine Initiative, a non-profit group that sponsors AIDS vaccine research and has its own vaccine candidate in early clinical trials. He noted that only 13 of the black volunteers became infected: nine in the placebo group and four in the vaccine group. "It's an intriguing finding, but it's just 13 people."

Chris Collins of the AIDS Vaccine Advocacy Coalition, a group pushing for more AIDS vaccine research, worries that the study will raise false hopes. "The study was not designed to determine effectiveness in a subgroup."

After Monday's release of the study's findings, the price of VaxGen stock dropped 47%, to $6.86, by the close of the day's trading.

Francis says he and other experts who analyzed the study — including independent experts from the Centers for Disease Control and Prevention, Johns Hopkins University and some universities that took part in the trial — were just as surprised as the skeptics. "The data convinced us that this is not a statistical fluke."

He says lab results appear to support that. Studies of HIV taken from non-whites who were vaccinated show that "there is a chunk missing from the virus. That chunk is what accounts for the increased efficacy."

Phill Wilson of the African-American AIDS Policy and Training Center at the University of California-Los Angeles says it was fortunate that blacks took part in the trial. "For my money, this is a clear call for these trials to reflect the demographics of the AIDS epidemic."

Wilson and other AIDS advocates say that any vaccine is years from approval at best — and assert that the best way to avoid getting HIV is to eliminate risky behavior. "The epidemic isn't over," Wilson says.