Fast-dissolving anal insert found safe for protecting against HIV

An insert being engineered as an “on-demand” HIV prevention method was found to be safe and well-tolerated in the first study of its use rectally. The insert had the capacity to deliver high levels of the anti-retroviral drugs tenofovir alafenamide (TAF) and elvitegravir (EVG) to rectal tissue and fluid, with very little drug circulating elsewhere in the body.

It could provide protection for up to three days after use

“Not everyone wants to take a tablet every day or go to a clinic for long-acting injectable PrEP,” said Sharon Riddler, M.D, a professor of infectious diseases at the University of Pittsburgh School of Medicine, referring to currently approved methods, such as daily oral pre-exposure prophylaxis (PrEP) and injections of cabotegravir given every two months.

“Finding the insert was safe and delivered high concentrations of drug within the rectum – at the site of potential infection – with low systemic exposure, supports its continued evaluation as an alternative method of HIV prevention,” added Riddler, who led the study.

The study enrolled 23 HIV-negative participants at the University of Pittsburgh and the University of Alabama at Birmingham and gave them a single dose of the insert in the clinic. Researchers then collected samples of blood, rectal fluid, and rectal tissue to assess drug levels at different time points that day and in the three days that followed.

One negative side effect

Only one adverse event, a mild case of redness around the anus (anal erythema), was deemed possibly related to the use of the insert. 

“The MTN-039 study has provided important information about the safety of the TAF/EVG insert used rectally as well as its potential efficacy, augmenting the data collected in our Phase I study of the insert as a vaginal product. Both clinical studies, which involved single administration (rectal or vaginal), have shown high and long-lasting drug levels compatible with protection against HIV. We are very encouraged by these results as we plan the next set of studies of this promising and unique product, which we believe would fill a gap in existing HIV prevention methods,” commented in a press release Gustavo Doncel, M.D., Ph.D. professor of obstetrics and gynecology at Eastern Virginia Medical School and scientific and executive director of CONRAD, which is developing the TAF/EVG fast-dissolving insert.

CONRAD is also planning to conduct a second study of the insert used vaginally.