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FDA committee backs combo PrEP for prevention of HIV in those at highest risk
The FDA Antiviral Drugs Advisory Committee voted in favor of recommending combination emtricitabine/tenofovir for HIV pre-exposure prophylaxis in those at high-risk for acquiring HIV infection. A final recommendation is expected in June.
“Globally, the number of new HIV infections continues to outpace treatment initiations, so we must continue to find new effective primary HIV prevention strategies,” Connie Celum, MD, MPH, professor of medicine and global health at the University of Washington, told the panel.
The supplemental new drug application was submitted by Gilead, the maker of combination emtricitabine/tenofovir (Truvada). This decision affects HIV-uninfected men who have sex with men, HIV-uninfected partners in serodiscordant couples and other individuals at risk for acquiring HIV through sexual activity.
The committee considered data from several studies including PrEP for the prevention of HIV acquisition. However, the principal data came from two studies: the Pre-exposure Prophylaxis Initiative (iPrEx) study and the Partners PrEP study.
As previously reported in Infectious Disease News, the Partners PrEP study included 4,747 serodiscordant couples, of which the HIV-uninfected partner was randomly assigned to tenofovir (Viread, Gilead), combination emtricitabine/tenofovir or placebo.
“In the primary analysis of the Partners PReP study, there was a 67% reduction in HIV acquisition in the tenofovir arm and a 75% reduction in HIV acquisition in the emtricitabine/tenofovir arm,” Jared Baeten, MD, PhD, associate professor of global health at the University of Washington, told the panel.
The iPrEx study included 2,499 individuals who were randomly assigned to combination emtricitabine/tenofovir or placebo. Those who were assigned to emtricitabine/tenofovir had a 44% lower risk of HIV acquisition compared with placebo. Among recipients with a high degree of adherence, there was a 73% in the risk of HIV acquisition. The combination treatment was well-tolerated.
Although the FDA is not required to take the advice of the advisory committee, it usually does.
Perspective
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Safe and effective new prevention approaches are urgently needed to further reduce new HIV infections, both in the US and across the globe. If delivered effectively and targeted to those at highest risk, CDC believes that PrEP may play a role in helping to reduce the significant continuing toll of HIV in the United States. However, its impact will depend on resolving many real-world issues, such as access, adherence and effective use in combination with other prevention methods. Demonstration projects to determine how to most effectively address some of these issues will be critical as we move forward.
While FDA will be determining if and how the drug itself can be labeled and marketed for prevention, CDC’s role is to provide guidance to physicians and at-risk populations on how to most effectively use all available prevention tools.
Perspective
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The recommendation by the FDA committee to approve antiretroviral PrEP makes sense, but the story is not as simple as that. There is little doubt that the combination of the two drugs tested — tenofovir and emtricitabine — prevents infection. But, ONLY if it's taken more or less exactly as prescribed. And it is, of course, very difficult to predict adherence to this or any drug. In addition to the unknown element of adherence, two issues have been widely raised. What is the cost, and what are the safety concerns? The public health cost — the amount needed to prevent a new infection for example — is raised by reduced effects from poor adherence. And the combination, while very safe overall in HIV infected adults, still has some adverse effects and these are of heightened concern in healthy uninfected persons. Still, this does represent a potentially great advance and allows those otherwise unable to protect themselves to do so. The recommended approval is based on extensive data and the answers to the remaining questions will only be resolved with more experience in ‘real world’ settings.