South Africa tests extended-release dapivirine ring for HIV prevention
Researchers in South Africa are currently testing a longer-acting version of the dapivirine vaginal ring, a device designed to help prevent HIV infection in women.
This development could be a game-changer, offering a more practical and sustainable alternative to existing HIV prevention methods.
The new version of the ring, which lasts for three months, is being compared to the current one-month ring, and early results suggest it could offer even greater protection while requiring fewer clinic visits and insertions.
What is the dapivirine ring?
The dapivirine ring is a form of pre-exposure prophylaxis (PrEP) that uses antiretroviral drugs to prevent HIV infection.
This ring, made of flexible silicone, is inserted into the vagina, where it releases a continuous dose of dapivirine, an antiretroviral drug that inhibits HIV replication.
Women can use the ring discreetly and, because it doesn't require daily action, it offers a more convenient option than the daily PrEP pill, which remains the most widely used form of HIV prevention in many parts of the world.
According to research published by Spotlight, the current one-month dapivirine ring is one of only two long-acting HIV prevention methods approved for use in South Africa.
The other is a bi-monthly injection of long-acting cabotegravir (CAB-LA). Both products are currently available only through implementation studies, but they represent a significant leap forward in HIV prevention, especially for women in regions with high HIV prevalence.
The three-month ring
At the recent HIV Research for Prevention (HIVR4P) conference in Lima, Peru, the Population Council, which manufactures the monthly dapivirine ring, presented early findings from a phase one trial testing the three-month version.
The new ring contains 100mg of dapivirine, four times the amount in the one-month version, allowing it to deliver the drug consistently over a longer period.
According to Jeremy Nuttall, senior director of preclinical sciences at the Population Council, the three-month ring could offer several benefits over the one-month version. Fewer insertions mean fewer clinic visits, which may improve adherence and overall effectiveness.
It could also reduce healthcare costs, waste, and the environmental impact associated with the production and disposal of single-use rings.
Early results: Effective and safe
The phase one trial, conducted in South Africa, enrolled 104 women who received either the three-month ring or a series of three one-month rings. During the study, researchers measured the levels of dapivirine in the participants' blood and vaginal fluid at various points.
The results were promising. Drug concentrations in the blood of women using the three-month ring were at least as high as those using the one-month ring, and in some cases, even higher.
Notably, the greatest difference was observed in the first month of use, where concentrations were higher in the three-month ring group. In terms of safety, both rings were well-tolerated, with no serious adverse events reported.
Common side effects included vaginal discharge and infections like bacterial vaginosis and candidiasis, but these were consistent across both groups.
Professor Linda-Gail Bekker, CEO of the Desmond Tutu Health Foundation, emphasized that the effectiveness of the ring, whether one-month or three-month, relies on consistent use.
The ring must be in place during times of potential HIV exposure (such as during sexual intercourse) to offer protection. Bekker is optimistic about the potential of the three-month ring and hopes it will soon be approved for use in South Africa.
What’s next?
Although the phase one trial results are encouraging, more research is needed before the three-month dapivirine ring can be made widely available. The next steps include further trials to confirm its efficacy and safety, particularly in pregnant and breastfeeding women, as well as in adolescents.
Currently, the one-month ring has not yet been approved for use in these groups due to a lack of initial safety data, but recent studies are addressing this gap.
If all goes well, the three-month ring could be available by 2026. However, this timeline depends on regulatory approval from bodies like the European Medicines Agency (EMA).
The cost of the new ring is also being finalized, with the aim of pricing it at around $16 (R279) per ring, just slightly more than the current one-month ring, which costs $12.80.