Study Finds PrEP Is Safe in Gay and Bi Men

Animal studies have suggested that antiretroviral drugs taken before exposure to HIV may prevent infection. One pre-exposure prophylaxis (PrEP) candidate, proved safe in a new CDC study presented Friday at the 18th International AIDS Conference in Vienna.

The double-blinded study involved 400 HIV-negative men who have sex with men (MSM) and reported having anal sex at least once in the previous year. Of the MSM, who were recruited from Atlanta, San Francisco, and Boston, 373 initiated the drug trial. Median age was 39; 73 percent were white, 15 percent African American, 4 percent Asian/Pacific Islander, and 9 percent Hispanic.

The men were randomized to receive either once-daily oral tenofovir or placebo at enrollment or after a nine-month delay. All subjects were regularly tested for HIV and received intensive HIV prevention counseling and condoms throughout the study.

"This study was not designed to detect efficacy of [tenofovir] in preventing HIV infection," the authors wrote in their conclusion. Seven study participants seroconverted: four from the placebo arm, including one HIV-negative at enrollment but subsequently found to be acutely infected, and three in the delayed PrEP group before they had initiated tenofovir.

The men taking tenofovir did not experience significant biomedical safety issues compared with the placebo group, found Dr. Lisa Grohskopf and colleagues. Early results from an ongoing review suggested that the men taking pills did not seem to forego condom use or take more HIV risks.

"We didn't find any increased risk of harm in medical terms, and on the behavioral side the preliminary work we've done also suggests there is no increased risk," Grohskopf said.