Data presented today at the International AIDS Conference in Melbourne and published simultaneously in the Lancet provides the first clear evidence for who wants PrEP—and how they use it outside of the United States.
While PrEP demand and demonstration projects have gathered steady momentum in the United States, the pace has been far slower in other parts of the world—including countries where some of the original trials happened. In the absence of evidence that people want and will use PrEP, there's been plenty of debate about the viability of this strategy, particular in low- and middle-income settings.
The new data from the iPrEX Open Label Extension study (iPrEX OLE) are a welcome antidote to this skepticism. The study was open to iPrEx participants who remained HIV negative at the end of the blinded, randomized trial, as well as HIV-negative participants from two smaller safety studies. Participants were offered the chance to take daily oral tenofovir-based PrEP. Participants could also decline and remain enrolled, receiving the same counseling and care. The participants were gay men and other men who have sex with men and transgender women from Latin America, the US and South Africa. For much of the study, participants attended clinic visits every two months—less frequently than the monthly visits that were standard in the efficacy trials to date, including iPrEx.
There is much to learn from these data, and AVAC will be working with partners in the coming weeks to discuss the implications and findings in greater detail. For now, here are some key findings:
- Uptake of PrEP was higher among OLE participants than it has been in the general population of gay men, MSM and transgender women. This suggests that when people are informed—as these former trial participants were—of efficacy and safety of daily oral PrEP, they are more likely to use it. There's a lot of work to be done to build awareness and demand in many countries—especially since the argument that "there's low demand, so why roll it out?" is being used to justify a slow pace of oral PrEP roll out in many settings where it could reduce infections.
- PrEP works if you take it. This isn't news but the study confirms it. In OLE, as with every other efficacy trial, people who had detectable drug in their blood—indicating that they had taken one or more PrEP doses—had less risk of HIV than those who did not. As with the original adherence/efficacy data, OLE calculated the risk at a given study visit, rather than in individuals over time. For example, the study is able to draw conclusions about the probability that someone with drug level "x" in their blood at a given study visit would test HIV positive at that visit. Higher drug levels means more protection. OLE also analyzed levels of protection based on levels corresponding to more-or-less daily dosing, compared with more infrequent dosing. Not surprisingly, more frequent dosing led to more protection. But even infrequent dosing reduced risk compared to people who weren’t taking PrEP at all. Overall, PrEP use was associated with a 50 percent reduction in risk of HIV compared to people in OLE who weren’t taking PrEP—and to HIV rates in participants in previous trials.
- People at higher risk of HIV were more likely to choose to take PrEP and more likely to take PrEP consistently over time. The study authors write, "Such preferential use of PrEP during times of greater risk is expected to increase the effect and cost effectiveness of PrEP services, and shows people’s capacity to recognize and respond appropriately to risks when given attractive options." We couldn’t say it any better.
- Blood levels of tenofovir diphosphate (the active form of tenofovir-based PrEP) weren’t as high in transgender women, so protection also wasn’t as high. There is an urgent need to gather more data on how PrEP is used in transgender women, how tenofovir-based drugs interact with exogenous hormones, and how this strategy can be adapted for use by a population with soaring rates of HIV infection.