AIDS Vaccine Fails, Yet Yields Hope

Donald P. Francis, M.D., D.Sc., president of VaxGen, with Phillip W. Berman, Ph.D., VaxGen's senior vice president of Research and Development, holding a vial of the AIDS vaccine candidate he invented. VaxGen

It was the first AIDS vaccine ever tested in human clinical trials and hopes were high, but the long awaited results show it does not work, reports CBS News Medical Correspondent Elizabeth Kaledin.

"Of course I'm disappointed," said Dr. Donald Francis, president of VaxGen, Inc., "but having worked in AIDS this long I'm accustomed to being disappointed.

From the start VaxGen, the bio tech firm making the vaccine, was hoping its product could prevent 30 percent of HIV infections. But in more than 5000 volunteers tested over 3 years, the vaccine reduced the infection rate by just 3.8 percent.

The results were not all dismal though.

The expected infection rate for the 314 black volunteers who received the vaccine was reduced by 78 percent -- a finding the researchers said was unexpected. The rate was reduced by 67 percent for all nonwhite volunteers other than Hispanics.

The company jumped on this glimmer of hope as a sign the vaccine may not be a total loss.

"As we dove into the data, we found that there was clearly a sub-group here of about 10 percent of the individuals, made up interestingly of racial and ethnic minorities, that responded quite effectively," Francis said. "So if that opens the way, I'm thrilled."

The Brisbane, Calif.-based company said it planned to continue developing the vaccine and will examine more closely why it worked better in blacks and Asians than it did in whites and Hispanics.

"We don't know why. There's a lot of factors that could be involved," VaxGen vice president Phillip Berman said Monday in a conference call, specifying factors such as geography, age and education. "We need to investigate each one of these possibilities."

Genetic factors may be at play, the company said.

Experts believe a vaccine is the most promising way to slow the worldwide AIDS epidemic, which has already killed 20 million people and infected 40 million more. Several other vaccines are in development.

Chris Collins, executive director of the AIDS Vaccine Advocacy Coalition, said he believes that lessons are being learned every day.

"In essence, the news didn’t prove or establish anything," he said. "What is does say is that further mining of the data is necessary, and perhaps further studies on this product to see if there really is something there."

For many Western patients, treatment of AIDS now involves an expensive, complicated regimen of drugs that block the spread of the disease. In developing countries, efforts focus on preventing the spread of AIDS from women to their children.

The soaring increase in AIDS cases in the developing world, especially Africa, has increased the urgency of efforts to develop a vaccine. A government study recently said AIDS' spread was so destabilizing that the disease should be considered a national security threat.

Even in wealthier countries where the drug cocktails are available, a falloff in infections may be reversing because the very existence of the life-saving drugs appears to be encouraging a return to risky behavior.
The data is being furiously debated in the highly political AIDS world.

"These results are promising. The trial provides clear evidence that a vaccine can work," said Dr. Peter Piot, executive director of UNAIDS, the U.N.'s AIDS agency. "However, there is an urgent need for more targeted research to find out why the candidate vaccine only seems to work in certain population sub-groups.

"In the meantime, we must continue to expand existing prevention efforts, which have proved their effectiveness when they are implemented at full scale," Piot said.

Gregg Gonsalves of the Gay Men's Health Crisis says the company is trying to put a positive spin on negative results.

"By using spurious subset data they can give false hopes to African Americans and Asians that somehow there's a new vaccine on the horizon," he told Kaledin.

Others are taking a wait and see approach to the results in ethnic groups
"It's a small sub group and we don't know what to make of it," said Seth Berkeley of the International Aids Vaccine Initatiative.

But Tom Shroeder, one of the volunteers who participated after his partner, Dan Breen died of AIDS, feels all is not lost.

"I don't regret a moment of it and again as long as it helped someone then absolutely I'm thrilled to be a part of it," he said.

The Food and Drug Administration told Vaxgen it would consider approving its AIDSVAX vaccine even if it was only 30 percent effective -- reflecting the urgency of finding weapons against the AIDS epidemic. VaxGen did not manage that reduced threshold. Most approved vaccines are more than 80 percent effective.

The publicly traded company's stock has risen and fallen dramatically during the last year as rumors of the experiment's results swirled. It sold for as low as $4.81 a share and as high as $23.25. It closed at $13.02 in trading on the Nasdaq Stock Market Friday. Trading was halted when the markets opened Monday morning.

The experiment, which initially involved 5,400 people at high risk for the disease, had been criticized by some activists who say it could encourage risky behavior. Even if the vaccine proved effective on some level, there might be no way to tell if it has worked on a particular individual.

But VaxGen has won widespread praise from doctors and the FDA for its handling of an ethically difficult test. The company counseled patients in the experiments to practice safe sex because the vaccine may not work and because one-third of the volunteers received the placebo.

AIDSVAX works by inducing the immune system to produce antibodies that attach to a protein on the surface of the virus, blocking its ability to infect healthy cells.

The company is also conducting a test of 2,500 intravenous drug users in Thailand, with results to be released later this year.
  • John Esterbrook

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