In disappointing news for AIDS fighters, the Gilead Sciences drug Truvada failed an HIV-prevention trial in high-risk women. The study was stopped early because researchers concluded the drug wasn't likely to prove effective. The results prompted a warning to doctors from the Centers for Disease Control and Prevention, because some women have already been using the drug as a preventive.
The study results were especially disappointing because Truvada had previously proven effective at keeping HIV at bay in high-risk men. Topical use of an AIDS drug in the vagina has also proven helpful. So, when study participants using Truvada contracted HIV in about the same numbers as women using placebo, researchers wondered at the cause. One possibility is that the participants didn't take the drug as directed.
Another hypothesis is that concentrations of the drug in vaginal tissue weren't high enough to provide a protective benefit. As the Wall Street Journal notes, research presented at a conference earlier this year showed that concentrations of tenofovir--one of the two active ingredients in Truvada--were 100 times higher in vaginal tissue when the drug was applied topically, in gel form, than when it was administered orally.
"While this development is a disappointing one," the company said in a statement, "Gilead believes that antiretroviral therapies remain a promising potential HIV prevention strategy." Whether the company will amp up focus on topical HIV remedies remains to be seen.