Female HIV Prevention Trial Halted, Truvada Not Effective in Women
Family Health International (FHI), a nonprofit organization, has announced that they will close a clinical trial known as FEM-PrEP designed to test whether a drug called Truvada could prevent HIV infection in women at high risk of exposure to the virus. Investigators have determined that the drug would probably not be effective.
Poor Compliance May Be Factor in Ineffective Trial
Truvada is a combination of two antiretroviral drugs: emtricitabine (Emtriva) and tenofovir disoproxil fumarate (Viread). The once-a-day pill helps to block HIV-1 reverse transcriptase, an enzyme needed for HIV-1 to replicate. By interfering with the replication process, Truvada lowers the amount of virus in the blood (viral load). The drug does not cure HIV or AIDS, but may help to increase the number of T-cells produced by the immune system.
Previous studies indicated that prophylactic Truvada was effective in preventing HIV infection among gay men. The first study in a series that looked at the drug’s effectiveness in preventing HIV infection, called iPrEx, was published in the November 2010 issue of the New England Journal of Medicine. Participants assigned to Truvada had about a 73% lower risk of HIV infection if they were compliant with the medication regimen.
FEM-PrEP was being tested in women in Kenya, South Africa and Tanzania who were not already infected with HIV. As of February 28, 2011, the study had enrolled almost 2,000 women. Preliminary data indicated that a total of 56 new HIV infections had occurred among those taking Truvada, equal to the number taking a placebo.
FHI said one of the possible reasons for the drug’s ineffectiveness may be low adherence to the study regimen. According to Dr. Anthony Fauci of the National Institute of Allergy and Infectious Diseases, study participants reported higher compliance with other HIV prevention methods such as condom use or a decrease in the number of sexual partners.
The organization will conduct further analysis and share the findings when the study is formally closed over the next few months. FEM-PrEP was funded by the United States Agency for International Development and the Bill and Melinda Gates Foundation.
Gilead Sciences, the company that manufactures Truvada said, "While this development is a disappointing one, Gilead believes that antiretroviral therapies remain a promising potential HIV prevention strategy. We continue to support ongoing studies evaluating the company's antiretroviral therapies as potential preventatives."
Two additional studies of Truvada will continue enrolling women in Africa. Those results are expected to be reported in early 2013.