The dapivirine vaginal ring reduces the risk for HIV infection by an estimated 39%, according to phase 3b findings presented at the International AIDS Society Conference on HIV Science.
The results were part of a reanalysis of the HOPE trial, which was conducted in four African countries. The findings also showed that adherence to ring use was higher than in a previous trial.
“This open-label study suggests that the dapivirine vaginal ring can be taken up and used well, with good adherence and high persistence, by women at risk for HIV in Africa,” Jared Baeten, MD, PhD, professor of global health, medicine and epidemiology at the University of Washington, told Infectious Disease News. “The dapivirine vaginal ring thus may become an HIV prevention option that will be appealing and useable for many women in that setting.”
HOPE is an ongoing open-label extension of the phase 3 ASPIRE trial. The latter showed that the dapivirine ring was well-tolerated and reduced the incidence of HIV by approximately 27% compared with placebo. The goals of the HOPE trial were to gather additional data on safety and new data on whether and how women used the ring after earlier trials showed it was modestly effective, according to an NIH news release.
Baeten and colleagues conducted the trial from July 2016 to August 2018 at 14 sites in Malawi, South Africa, Uganda and Zimbabwe. They offered 1,456 HIV uninfected women from the ASPIRE trial 12 months of access to the vaginal ring.
The researchers tested used rings for residual levels of dapivirine monthly for 3 months and then quarterly. They compared HIV incidence with that expected by weighted bootstrap sampling of the placebo arm of ASPIRE and matched on trial site, age and presence of a curable STI at trial entry, with a limitation being a lack of a contemporaneous placebo group, the researchers explained.
According to Baeten and colleagues, acceptance of the ring was 92% at baseline and remained high throughout the study, with reported rates of 90%, 89%, 87%, 83%, and 79% at months 1, 2, 3, 6, and 9. They found that 86% of returned rings had residual dapivirine levels consistent with some use during the prior month, demonstrating a high adherence.
There were 35 HIV infections for a rate of 2.7% per 100 person years (95% CI, 1.9-3.8), compared with an expected incidence of 4.4 per 100 persons years (95% CI, 3.2-5.8), representing an estimated 39% reduced risk for HIV.
However, the NIH noted that the trial was not designed to determine the ring’s effectiveness.
“Effective and safe HIV prevention options continue to be needed the world over but particularly for women at risk for acquiring HIV,” Baeten said. “The more options that are developed and used, the better chance we have to turn the tide on the global HIV epidemic.” – by Joe Gramigna
Baeten J, et al. High adherence and sustained impact on HIV-1 incidence: Final results of an open-label extension trial of the dapivirine vaginal ring. Presented at: IAS Conference on HIV Science; July 21-25, 2019; Mexico City.
Disclosures: Baeten reports working as a consultant for Gilead Sciences, Merck and Janssen.