July 13, 2012
Three new studies show the potential promise, as well as challenges, of using HIV drugs to prevent infection among healthy but high-risk patients.
Two studies of African heterosexuals show pre-exposure prophylaxis (PrEP) reduced the rate of HIV infection by 62 percent to 75 percent, a rate similar to that seen in PrEP studies involving gay men. A third study focusing on African women ended early after showing no effect, mostly because fewer than 40 percent of participants took the pills as prescribed.
The studies overall bolster the idea of PrEP as one of the several powerful HIV prevention tools, said Myron Cohen, a professor at the University of North Carolina and co-author of an editorial accompanying the studies.
"We're at some sort of turning point in the AIDS epidemic," said Cohen. "It's not a single thing going on here. It's the culmination of what's happened for 30 years. ... Each of them is moving the political world to start thinking about an AIDS-free generation."
A lingering challenge is finding ways to motivate uninfected patients to take the drugs properly. Researchers should investigate if the women in Africa stopped taking the drugs due to side effects or because they underestimated their risk of infection, Cohen said. About 3 percent of the women became infected during the study, whether they received the drugs or a placebo.
In two of the trials, patients were randomly assigned to receive either Truvada (tenofovir and emtricitabine) or placebo. In a third, they were randomly assigned to placebo, Truvada or tenofovir. The Truvada and tenofovir groups had similar results.
In May, a Food and Drug Administration advisory panel recommended the agency approve Truvada for PrEP.
[PNU editor's note: The three studies and editorial appear in the New England Journal of Medicine (2012;doi: 10.1056/NEJMoa1108524; doi: 10.1056/NEJMoa1202614; doi: 10.1056/NEJMoa1110711; and doi: 10.1056/NEJMe1207438]