Testing of vaginal gel for HIV prevention halted after interim results showed no difference from placebo

Researchers involved with a multi-armed clinical trial designed to evaluate different antiretroviral (ARV) interventions for HIV prevention on Friday announced the arm testing a vaginal gel had been stopped because it was not working, the New York Times reports. The announcement marks "a major disappointment for AIDS research" because the gel "had seemed to work surprisingly well in a previous" trial, according to the newspaper. That study, called CAPRISA, found that the vaginal gel, which contains the ARV tenofovir, reduced the risk of HIV infection by 39 percent among women overall and by 54 percent among women who used it most consistently, the newspaper notes, adding, "It was hoped that the new trial, nicknamed VOICE (for Vaginal and Oral Interventions to Control the Epidemic), would confirm that earlier trial" (McNeil, 11/25).

"Another area of the three-part trial, involving a tenofovir pill, was scrapped in September for similar reasons, but studies are ongoing on a third avenue using tenofovir and a booster drug," Agence France-Presse writes (11/27). According to the New York Times, "The trial is expected to go on until mid-2012 and the data are to be released in early 2013" (11/25). In a statement, the Microbicide Trials Network, which is running the trial, said, "Investigators will not be able to determine why tenofovir gel was not effective in the women in VOICE until after the study is completed and all of the data is analyzed in full" (11/25).