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Taking two HIV drugs once-daily provided high-risk but HIV-negative participants an average 44 percent protection against HIV infection in a trailblazing new study. The clinical trial followed 2,499 HIV-negative men who have sex with men (MSM) and transgender women who have sex with men in six countries, including a study site in San Francisco. Participants were randomly assigned to receive a combination of two antiretroviral drugs, emtricitabine plus tenofovir disoproxil fumarate (FTC-TDF), to be taken orally once a day, or a once-daily placebo. FTC and TDF in combination are marketed as Truvada.
At a median follow-up of 1.2 years (maximum 2.8 years), 100 subjects subsequently became infected, including 64 in the placebo group and 36 in the FTC-TDF group. Taking FTC-TDF as pre-exposure prophylaxis (PrEP) provided trial participants an average of 44 percent additional protection against HIV infection (95 percent confidence interval, 15 percent-63 percent; P=0.005). Among those with an adherence rate to FTC-TDF of 90 percent or more, HIV risk was reduced by roughly 73 percent (95 percent confidence interval 41 percent-88 percent).
"It will only work if people use it consistently, and the real challenge is how do you use it consistently," said study leader Dr. Robert Grant, a University of California-San Francisco professor and researcher with the Gladstone Institute for Virology and Immunology. "Condoms are still our first line of defense, but this could potentially be a very good backup."
Researchers are not recommending PrEP be immediately used to prevent HIV. For one thing, PrEP was only proven effective among MSM and transgender women who have sex with men, not heterosexuals or IV drug users.
Cost presents another issue: Truvada sells for $750 to $1,000 a month in the United States. A generic version available overseas costs about 40 cents a day.
Public health officials and representatives from Bay Area HIV/AIDS groups were meeting Tuesday morning to discuss how the trial results could affect local prevention efforts. CDC will be developing interim guidance, and urges individuals and their doctors to await those guidelines for the appropriate use of PrEP. For more information, visit http://www.cdc.gov/nchhstp/newsroom/iPrExMediaStatement.html.
The study, "Preexposure Chemoprophylaxis for HIV Prevention in Men Who Have Sex with Men," was published in the New England Journal of Medicine (2010; doi:10.1056/NEJMoa1011205).
The Friends of AIDS Foundation is dedicated to enhancing the quality of life for HIV positive individuals and empowering people to make healthy choices to prevent the spread of the HIV virus. To learn more about The Friends of AIDS Foundation, please visit: http://www.friendsofaids.org.
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