 |
| Dapivirine ring (Photo: International Partnership for Microbicides) |
“Across multiple analyses, we see a statistically significant relationship between ring use and HIV protection,” said Elizabeth R. Brown, ScD, from the Fred Hutchinson Cancer Research Center and University of Washington in Seattle, who presented the ASPIRE Study data at the conference on Tuesday.The vaginal dapivirine ring prevented 56% of HIV infections, and possibly provided HIV risk reduction between 75% and 92% for women who used the ring consistently, new analyses of the ASPIRE Study data show.
The vaginal ring, which is inserted into the vagina and slowly releases the antiretroviral dapivirine over a month, is the first HIV-prevention product designed specifically for women. If it were approved for use, it would be an alternative antiretroviral-based HIV-prevention method along with Truvada-based PrEP.“These results suggest the ring use is associated with at least a 56%, and potentially 75% or greater protection against HIV when used consistently,” she said.
“People need [PrEP] options,” said Roy Gulick, from Weill Cornell Medicine. “One approach is probably not going to work for everyone. Some people may prefer pills, some people may prefer injections, some people may prefer rings. I think we have the room for lots of different approaches, and I think that’s how we’ll be successful.”
Earlier results of the ASPIRE Study and The Ring Study, which were presented at the 2016 Conference on Retroviruses and Opportunistic Infections (CROI), showed that the ring reduced HIV infection risk by 27% and 31%, respectively. The modest, though significant, HIV risk reduction seen in these studies was likely due to adherence issues—with women possibly removing the rings and putting them back in place between study visits. These earlier efficacy analyses did not take into account whether or not people in the study used the ring, and at what level they used it.
The HIV risk reduction estimation reported today is based on new analyses of women in ASPIRE who used the rings most consistently (based on the amount of residual drug remaining on the rings when they were returned). Because the drug in the ring is released slowly over the 28-day lifespan of the ring, it was possible for researchers to estimate how often women in the study used the rings—without having to rely on self-report data.
The analyses presented at AIDS 2016 included 2,359 women and data from more than 12,000 returned rings.
In the placebo arm, there were a total of 50 HIV infections over 1,089 person-years of follow up for an incidence rate of 4.6%. There was no statistically significant difference between this incidence rate and the incidence rate among people who were non-adherent (3.6%). The risk reduction estimate for the “non-adherent” group relative to placebo was 31%.
Risk reduction improved, and HIV-incidence declined, in groups of people who returned the rings with less drug in them (indicating that they had higher adherence). Among people with “low to high” adherence, who returned rings with less than 23.5 mg of drug, there were 14 HIV infections, with an incidence rate of 1.9% and a risk reduction of 56%. Among people who with “medium to high” adherence, and returned rings with less than 22 mg of drug, there were seven HIV infections for an incidence rate of 1.5% and a risk reduction estimate of 65%.
The researchers conducted separate “length-adjusted” analyses, to take into consideration the amount of time that women had the ring in their possession before they were provided a new one (which could vary by +/- two weeks). Using these analyses, Brown reported that risk reduction was higher—up to 75%—for people with better adherence.
In a final set of analyses, the researchers looked at rings used over time by women who seroconverted during the study, to see if there was a relation between adherence (as measured by residual drug) and HIV infection. They found a dose-response relationship. In other words, HIV infections were more likely to happen when the ring was not used or used inconsistently. Consistent use was associated with the lowest incidence rate (0.4%) and the highest estimation of HIV risk reduction (92%).
“I think many of us had really waited and were really keen to hear this data—and we’re excited about these new results of high efficacy. This is great news,” said Nono Simelela, from the South Africa Ministry of Health.
Women who participated in ASPIRE have the option of enrolling in a one-year open-label continuation study called HOPE which will provide the dapivirine ring to participants.
This open-label study (and The Ring Study’s open-label continuation, called DREAM) will gather additional data on the ring’s safety and also investigate how women use the ring when they know there is no chance of receiving a placebo ring.
No comments:
Post a Comment