A vaginal insert containing the antiretrovirals tenofovir alafenamide (TAF) and Vitekta (elvitegravir) greatly lowered the risk of acquisition of an HIV-like virus among female monkeys in a recent small study. Given these promising findings, researchers developing this new form of pre-exposure prophylaxis (PrEP) against HIV hope to advance research into trials of the insert among women.
Presenting their findings at 2019 Conference on Retroviruses and Opportunistic Infections (CROI) in Seattle, scientists studied 14 female pigtail macaques with normal menstrual cycles. All the animals were vaginally exposed to a laboratory-developed virus known as SHIV162P3 each week for up to 13 weeks.
Six of the monkeys received vaginal inserts containing 20 milligrams of TAF and 16 mg of Vitekta four hours before each vaginal exposure to SHIV. Eight control animals received a placebo insert following the same schedule.
Of the eight control animals, seven contracted SHIV and one remained SHIV negative after the 13 weekly exposures to the virus. The infected animals contracted the virus after a median of three exposures and between two and 13 exposures.
Five of the six monkeys that received the insert with the active drugs remained SHIV negative through all 13 exposures to the virus. This meant that the insert reduced the risk of SHIV by an estimated 92 percent.
Other studies are ongoing to determine the insert’s window of protection against SHIV, including its use up to 24 hours before and up to four hours after sex.
To read the conference abstract, click here.
To view a webcast of the conference presentation, click here.