When used consistently for a month at a time, a vaginal ring containing an antiretroviral (ARV) drug called dapivirine provides significant protection against HIV, suggest results of new data analyses from the ASPIRE study announced at The International Conference on AIDS (AIDS 2016) in Durban, South Africa in July. Among women who appeared to use the vaginal ring most regularly, HIV risk was cut by more than half across all analyses, and in some, by 75 per cent or more.
ASPIRE – A Study to Prevent Infection with a Ring for Extended Use, or MTN-020, was a Phase III trial that involved 2,629 women ages 18-45 from Malawi, Uganda, South Africa and Zimbabwe. Its main results, which were reported earlier this year, found the dapivirine ring reduced the risk of HIV by 27 per cent, meaning that 27 per cent fewer women acquired HIV in the group assigned to use the dapivirine ring than in the group assigned to use a placebo ring containing no active drug.
The new results, which are based on additional exploratory analyses, suggest the dapivirine ring may be far more effective when used most or all the time, said researchers from the National Institutes of Health (NIH)-funded Microbicide Trials Network.
“Adherence to HIV prevention strategies is not always perfect, and we knew that not all women used the ring consistently, so we developed an analysis to explore the degree of HIV protection that was associated with more consistent use,” explained Elizabeth Brown, from the Fred Hutchinson Cancer Research Center and University of Washington in Seattle, who is the principal investigator of MTN’s Statistical and Data Management Center (SDMC). “Across all analyses we saw high adherence was associated with significantly better HIV protection.”
While these new results are encouraging, Dr. Brown and her colleagues are mindful that there are inherent limitations in these kinds of exploratory analyses, and that further study will be needed to validate the results.