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iPrEx study on Pre-Exposure Prophylaxis (PrEP) Shows Some Effectiveness in Preventing HIV

November 23, 2010
MHRP applauds study results published online today in the New England Journal of Medicine that show antiretroviral medications taken orally on a daily basis resulted in an estimated 44% reduction of risk of HIV transmission among men who have sex with men

Study results, published in today’s online issue of the New England Journal of Medicine, show that antiretroviral medications taken orally on a daily basis by men who have sex with men can provide partial protection from HIV infection. 

The study included 2,499 volunteers in high-risk populations in Brazil, Ecuador, Peru, South Africa, Thailand and the U.S. The study participants were given a once-daily combination of tenofovir and emtricitabine in one tablet (Truvada). There were 100 incident infections, 64 of which occurred in the placebo group and 36 in the FTC–TDF group, for an estimated efficacy of 44% with 95% confidence intervals of 15 to 63. 

MHRP Director COL Nelson L. Michael wrote the accompanying editorial in the NEJM. “The results of the iPrEx study represent a significant advance in HIV-prevention research by providing the proof of concept that a combination antiretroviral drug in widespread clinical use in the treatment of chronic HIV infection reduces the risk of HIV acquisition in men who have sex with men,” wrote Michael.  He added, "The iPrEx trial team and volunteers should be congratulated on conducting a landmark study in HIV prevention."

While these results are encouraging for the future of HIV prevention, Michael noted that the implementation of PrEP, especially in resource-limited health care settings, presents many challenges. "The development of drug resistance in individuals with undiagnosed, acute HIV infection exposed to oral antiretroviral drugs, along with some kidney problems, will need to be addressed in order to implement this prevention approach," said Michael.

The last year has seen many advances in HIV prevention including results from RV144, the discovery of neutralizing antibodies and positive results from the CAPRISA 004 microbicide study. In his editorial, Michael concludes that the iPrEx study, when taken with data from other ongoing PrEP trials, is likely to “place another arrow in the quiver for HIV prevention.”

The iPrEx study was funded and sponsored by NIH, with co-funding by the Gates Foundation and drug donation by Gilead, Inc.

Editorial: www.nejm.org/doi/full/10.1056/NEJMe1012929

Manuscript: www.nejm.org/doi/full/10.1056/NEJMoa1011205

iPrEx Study FAQ and fact sheets: www.iprexnews.com