Preliminary results of a study of an antiretroviral-containing vaginal ring as prevention against HIV saw results similar to another large study: a modest overall benefit among women in sub-Saharan Africa, but greater protection against the virus among older women. The ongoing Phase III, multicenter, double-blind, randomized, placebo-controlled IPM 027 trial of 1,959 women (1,762 in South Africa and 197 in Uganda) randomized women at a 2-to-1 ratio to receive a vaginal ring containing the non-nucleoside transcriptase-inhibitor dapivirine or a placebo ring. Enrollment began in 2012.
Results were presented at the 2016 Conference on Retroviruses and Opportunistic Infections (CROI) in Boston. Like the other vaginal ring study, the presentation was met with enthusiastic applause as well as s standing ovation among many conference attendees.
In the trial, which is also known at The Ring Study, women received a new ring every four weeks.
The median age of the women upon entering the study was 25. Ninety-one percent were unmarried.
At the cutoff point for data to include in this preliminary analysis, the participants had contributed 2,805 person-years of follow-up. (Person-years are the cumulative years participants spend in a study.) At this point, 761 women had completed the study’s two-years follow-up period.
A total of 133 women contracted HIV during the study follow-up period analyzed, including 77 women in the dapivirine arm and 56 in the placebo arm, for respective HIV incidence rates of 4.08 and 6.1 per 100 person-years. (In other words, a respective 4.08 percent and 6.1 percent of the women in each group contracted HIV each year.) Thus, the dapivirine ring reduced the risk of HIV by 30.7 percent. A further analysis showed that, among women older than 21 years of age, the dapivirine ring lowered the risk of HIV by 37.5 percent. Younger women experienced low protection from the ring.
These findings were similar to those seen in the ASPIRE trial, also presented at CROI, which also looked at the dapivirine ring among sub-Saharan African women.
It is possible that anal sex among the participants reduced the effectivenss of the ring, because the product does not protect against anal acquisition of the virus.
There were no apparent differences in safety indicators between the two study arms. The ring, thus, was safe to use.
The trial investigators are planning an open-label phase of the trial to continue providing rings to female participants and further study their use among this population.