SAN FRANCISCO—Thanks to a new study conducted by the Gladstone Institutes of the University of California-SF, a combination drug currently being used to treat HIV sufferers has been found to prevent infection by the retrovirus in at least 78 percent of those exposed and who faithfully took the drug daily.
The study, which was published earlier this week in the New England Journal of Medicine, found that Truvada, the brand name for the combination of tenofovir disoproxil fumarate and emtricitabine, acts to prevent the HIV virus from attacking the cells that make up the human immune system. Although much further research needs to be done, early results found that when 1,251 participants in the study—all gay and bisexual males and a small number of transgendered women—took the drug combo daily, they had roughly half the number of infections—36 versus 64—as a control group containing almost as many volunteers taking a placebo.
The results of the drug regimen, called "pre-exposure prophylaxis" or Pr-EP, were complicated by the fact that two of the group taking Truvada were found to have been HIV-infected before the study began—they apparently had been pre-screened using an ELISA/antibody-detection method, which can take up to six months to register positive in an HIV-infected person—while of the 34 remaining who were found to be HIV-positive, only three had any drug in their bloodstreams, suggesting that the other 31 either had not taken the drug or had taken it sporadically. Moreover, many men in both the drug group and the control group had failed to take all of their pills: Some who claimed to have taken the medication either half or 90 percent of the time had little or none of the drug (or placebo) in their blood when tested.
"This is a dramatic finding, and in terms of the prevention, it is a very interesting one," said Dr. Robert Hogg of the British Columbia Centre for Excellence in HIV/AIDS. "It will be important for sex workers who are having trouble using condoms. This will be a great prevention method to reduce the risk, but it's not going to replace other prevention methods, like condoms or peer-to-peer education or other means of HIV prevention."
Worse, the drug is very expensive, with daily doses costing anywhere from $5,000 to $14,000 per year in the U.S., although a generic version is available overseas costing just 40 cents per day, and in any case, it's unlikely that most health insurance plans would cover the prevention drug.
Also, it is currently unknown how daily use of the drug would affect heterosexual males or women, since neither group were part of the current study.
"Clearly we need to know more about this therapy, and its effectiveness and how to deliver it, but it appears to have great promise," said Dan Van Gorder, executive director of Project Inform in San Francisco. "I think the world is at a real crossroads in terms of its ability to drive this epidemic to an end."
Still, with the 22nd annual World AIDS Day being celebrated on December 1, this has got to be considered good news for those at high risk who are sexually active—though sadly too late for the estimated 33 million worldwide who are currently infected.
