Thursday, April 26, 2007

An AIDS vaccine for blacks and Asians only

NEW YORK - This morning, Brisbane, Calif.-based VaxGen unveiled the results of the first AIDS vaccine to finish human clinical trials. Overall, the HIV vaccine didn't work. But it does seem to have been effective in blacks and Asians, a finding that is sure to stir up controversy.

Already, expectations for VaxGen's AIDSVax were somewhat lowered: The bar of success had been placed at reducing infections by a mere 30%. But the 3,000 volunteers who received the vaccine were only 3.8% less likely to be infected with HIV than 1,500 volunteers who received only the placebo. That small benefit could occur purely by chance.

But the results were stunningly different among the 314 black volunteers, who saw their rate of infection reduced by a whopping 78%. When Asian and black volunteers were lumped together, the reduction was 67%. But because these results came from such small subsets of the study, it is still somewhat difficult to be sure of the results. The U.S. Food and Drug Administration might not be willing to put a vaccine on the market based on such limited data.

How skimpy is the data? A few more patients getting the disease in the black subgroup would have completely changed the results. Moreover, this particular vaccine would not be effective in sub-Saharan Africa, where AIDS has been most devastating. It targets a strain of the HIV virus that is predominant only in Europe and Asia.

Why would an AIDS vaccine work along racial lines? Geneticists have tried to have it both ways when it comes to genetic diversity. Companies like Myriad Genetics and DeCode Genetics have tried to use particular populations to find genes linked to disease. At the same time, many prominent geneticists, including those who mapped the human genome, have publicly said that genetic differences, especially those that occur along racial lines, don't amount to much.

But there are genes that are more likely to occur in Europeans, who are descended from a relatively tiny population that made its way up the continent, than in Africans. (There is also far more genetic diversity in Africa than anywhere else.) And sometimes these genes are medically important enough that guessing at their presence based on skin color is worthwhile to some doctors. For instance, some blood pressure medicines tend not to work as well in African-Americans as in Caucasians.

VaxGen, however, says that blacks and Asians also had higher elevations of antibodies against the proteins in AIDSVax. That could mean there is a genetic difference that determines whether the vaccine works, and that an assay might measure how effective the vaccine is in a particular patient. On its conference call today, VaxGen spoke about finding such an assay. That would be a step in the right direction to making this vaccine usable.

In a prepared statement, VaxGen co-founder, President and Chief Scientific Officer Dr. Donald Francis said, "The results from this groundbreaking effort will provide new insights into HIV and hopefully pave the way to ever more effective vaccines." The depressing thing for VaxGen investors is that the next effective vaccine could very well come from Aventis or Merck, both of which are working to develop their own AIDS vaccines.

AIDS activists have plenty to be sad about as well. The dream of a widely usable AIDS vaccine just slipped a little further away. At the same time, Roche and Trimeris announced that, at least in Europe, their widely anticipated AIDS drug Fuzeon would cost about $20,000 a year--twice as much as many currently available treatments. The companies explain the high price by saying that the drug is expensive to make.

(This article from Feb 24, 2003 is still up on Forbes but Google does not have it and it seems to have been totally forgotten. The company that made the vaccine has now just about gone broke)

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