WASHINGTON, Aug. 24, 2011 /PRNewswire-USNewswire/ — To stem the estimated 2.6 million new HIV infections that occur worldwide each year, more than 200 representatives from the scientific and HIV/AIDS communities took an important step in assessing the safety and public health implications of providing antiretroviral drugs to uninfected men and women exposed to HIV through sexual contact – a strategy called pre-exposure prophylaxis, or PrEP.
Assembling August 19 at an open public meeting and interactive webcast convened by the Forum for Collaborative HIV Research, these researchers, HIV/AIDS advocates, members of industry and representatives from National Institutes of Health, the Centers for Disease Control and Prevention (CDC), Food and Drug Administration (FDA) and state public health departments applied the findings from a number of large trials to discuss a roadmap for FDA and CDC to develop guidance on the safe use of PrEP in otherwise healthy individuals at high risk of acquiring HIV. Held with the encouragement of FDA, this meeting has important implications for medical practice in the U.S. because recent data strongly support the efficacy of antiretroviral intervention for this purpose.
Although FDA has not yet approved PrEP to reduce HIV acquisition in uninfected individuals, one form of PrEP recently studied for use in healthy men or in couples where one partner is HIV positive –a daily pill containing tenofovir plus emtricitabine (TDF/FTC) – is FDA-approved for the treatment of HIV infection. In women, studies have also demonstrated the efficacy of prophylactic treatment with tenofovir applied as a vaginal gel.
"We now have findings from large studies that support a conclusion that PrEP is effective in gay and bisexual men, who represent more than half of new HIV infections in the U.S., and now, there is evidence that PrEP may reduce HIV infection in heterosexual men and women, the population hardest hit by HIV worldwide," said Jur Strobos, M.D., Deputy Director of the Forum. "We must however, apply these promising data to develop workable strategies that mitigate risk that may be associated with the prophylactic use of antiretrovirals. These include both medical and socio-behavioral risk. We must ensure that people at greatest risk for acquiring HIV receive a comprehensive package of prevention services, including regular HIV testing, condom provision, risk reduction counseling and management of other sexually transmitted infections. The purpose of our meeting was to help identify what the components of a complete package should be."
Among the data reviewed at the meeting were results from the large-scale, multinational iPrEx trial, which found that a daily dose of TDF/FTC provided at least 44 percent protection to men and transgender women who have sex with men (MSM). Among those patients who were most adherent (used TDF/FTC on 90 percent or more of the days during the trial), HIV risk was reduced by 73 percent. Reinforcing these findings, a new CDC trial called the TDF2 study, along with Partners PrEP conducted by researchers at the University of Washington, showed that PrEP reduced the risk of HIV in 63 percent of the uninfected heterosexual men and women in the study population. While unsuccessful in demonstrating efficacy for as yet unknown reasons, data from the FEMPrEP study presented at the meeting also confirmed that there were minimal if any safety concerns associated with daily use of the antiretroviral drugs. As limited studies, none could assess safety problems that may arise with broader use – the purpose of this meeting.
Charting the future use of PrEP as a prevention strategy, the meeting participants considered how FDA’s broad authority to require Risk Evaluation and Mitigation Strategies (REMS) could be applied to mitigate the risks associated with the scale-up of prophylactic use of antiretrovirals. The participants focused on several medical complications associated with use of the TDF/FTC combination including a potential impairment in renal function in some patients with long-term use and an early decrease in bone mineral density that could stabilize over time.
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