The iPrEx Open-Label Extension Study (iPrEx OLE), the next phase of the first human study to report efficacy results on pre-exposure prophylaxis (PrEP) to prevent HIV infection, has begun at clinical trial sites around the world. Approximately 2,000 men and transgender women who have sex with men are expected to participate in the 72-week iPrEx OLE study. Study sites in the United States and South Africa are enrolling participants now, as other study sites finalize the regulatory approval process.
In PrEP, antiretroviral medications that are usually used to treat HIV are taken by uninfected people to reduce their risk of infection. The iPrEx study found that men and transgender women who have sex with men (MSM) who took a single daily tablet containing the HIV medications emtricitabine and tenofovir (FTC/TDF), known commercially as Truvada®, experienced an average of 44% fewer HIV infections than those who received a placebo (blank pill). HIV infection rates in the iPrEx study dropped by 90% among those who used PrEP consistently enough to have detectable drug in the body. The HIV risk reduction benefits of PrEP were in addition to those provided by safer sex counseling, condoms, HIV testing and the detection and treatment of sexually transmitted infections. iPrEx study results were published in the New England Journal of Medicine in November, 2010.
The news of the start of iPrEx OLE follows the announcements by two other major PrEP studies, Partners PrEP and the CDC study in Botswana, known as TDF2, which demonstrated the safety and efficacy of PrEP in heterosexual women and men.
AdvertisementiPrEx OLE is a continuation of the iPrEx study that will collect additional data on PrEP efficacy, safety and adherence. All HIV-negative participants who took part in the original iPrEx study and who wish to participate will receive FTC/TDF for HIV prevention for 72 weeks through iPrEx OLE. No placebo will be used in the Open Label Extension.
"We are in a critical moment in HIV prevention research," said iPrEx Protocol Chair Robert Grant, MD, MPH of the Gladstone Institutes and the University of California at San Francisco. "iPrEx provided the first proof of an important new method of HIV prevention that can help slow the global toll of 2.6 million new HIV infections each year. Partners PrEP and the TDF2 study have now expanded that finding by demonstrating the effectiveness of PrEP in heterosexual women and men. Developing and deploying proven HIV prevention methods -- including PrEP, microbicides, vaginal gels, clean needles, medical male circumcision, early treatment, counseling, testing, condoms and suppressive therapy for pregnant women will all be key to slowing the global epidemic."
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