July 13, 2011
San Francisco, CA -- Two new studies of pre-exposure prophylaxis (PrEP) in heterosexuals in Africa have demonstrated that the antiretroviral (ARV) drug tenofovir, taken by HIV-negative people, substantially reduces the number of new HIV infections.
"The success of these new studies -- when combined with similar results from a recent international PrEP study in men who have sex with men (MSM) and transgender females -- validate that ARVs have the power to substantially alter the course of the AIDS epidemic worldwide," said Dana Van Gorder, Project Inform's Executive Director. "As a result, Project Inform urges the U.S. government to work quickly with other partners in the philanthropic and research communities to determine how best to roll out both PrEP and treatment-as-prevention programs on a global scale."
The two new studies differed slightly in their design, but both tested PrEP in heterosexuals in Africa. The PARTNERS PrEP study compared either Viread (tenofovir) or Truvada (tenofovir plus emtricitabine) to placebo in 4,758 heterosexual couples, where one partner was HIV-positive but not receiving ARV treatment and the other HIV-negative. The second study, TDF2, compared Truvada to placebo in roughly 1,200 HIV-negative men and women in Botswana.
PARTNERS found that Viread cut the rate of new infections by 62 percent compared to placebo and that infections dropped by 73 percent in those taking Truvada. In TDF2, Truvada cut infections by nearly 63 percent in both men and women. (The U.S. Centers for Disease Control and Prevention (CDC) originally stated in 2009 that it didn't believe the TDF2 study would be able to demonstrate efficacy, because the overall rate of new infections was much lower than expected. It turned out, however, that Truvada also worked much better than expected, so the CDC now claims that efficacy can be established.)
The positive results of these two studies stand in stark contrast to the news earlier this year from the FEM-PrEP study. The sponsors of that study shut it down early, because the rate of new infections was identical in those on Truvada and those on placebo in the first months of the study. This meant that the study wouldn't be able to determine efficacy if it continued. However, experts are now explaining that the difference between the Partners and TDF2 studies and the FEM-PrEP study is likely due to the fact that adherence was much higher in the new studies than in FEM-PrEP. This is a logical explanation, as the drugs can only work if people take them properly.
"While a deeper analysis of all of these studies is still necessary, one thing is clear -- PrEP really does work when taken correctly," said David Evans, Director of Research Advocacy for Project Inform. "Truvada is an expensive alternative to condoms and won't be appropriate for everyone. Nevertheless, when combined with optimal treatment of people living with HIV, PrEP could significantly reverse the course of the epidemic in communities with high rates of new infections. This should be cause for optimism and a renewed commitment on the part of funders to do what it will take to quickly test the feasibility of PrEP and to ensure that it becomes available where needed most."
Project Inform is particularly interested in assuring that there will be sufficient funding for PrEP demonstration projects -- in which researchers test the best methods for recruitment, screening, PrEP provision, adherence, care retention and HIV and STD testing and treatment outside of rigorously controlled clinical trials. Two demonstration projects in MSMs and transgender females are due to launch in the United States soon, and Project Inform is working with government partners and Truvada's maker, Gilead Sciences, to plan others.
"These new results lend greater urgency to expand current plans for testing the feasibility and cost-effectiveness of PrEP in all the communities who need it, including heterosexuals who are at particularly high risk of HIV infection," commented Evans. "While Project Inform will strenuously advocate for such projects to launch in sub-Saharan Africa and other areas of the highest HIV prevalence globally, we will also seek to ensure that demonstration projects in heterosexuals, particularly African Americans, are funded and implemented in the United States, which has its own unique challenges in care delivery systems and demographic variables."
"We also believe that PrEP demonstration projects should be combined with studies to explore the feasibility of intensive HIV testing and linkage to care and treatment (TLC+) projects that are underway or planned in the United States, " Evans continued. "At this point, with PrEP and TLC+ added to the prevention tool box, we might actually achieve the goal of the U.S. National HIV/AIDS Strategy to reduce the number of new HIV infections by 25 percent by 2015, provided that policy makers and charitable foundations make the necessary funding available soon."
In the meantime, Project Inform is calling on the CDC to meet quickly with the community and researchers to provide clear guidance on the use of PrEP in all communities. Given that Truvada is already available by prescription in the United States for people with HIV, it is therefore available to HIV-negative individuals wishing to use it for PrEP as well. For this reason, the CDC quickly issued an interim guidance on PrEP following the results of the iPrEx PrEP study in MSMs and transgender females. A similar interim guidance is now also needed for heterosexuals at risk of HIV infection. Project Inform encourages individuals who believe they could benefit from PrEP today, and physicians who see patients they believe could benefit from it, to discuss the benefits and risks of beginning PrEP.
"Some have argued that PrEP is not ready for primetime, and may not even be effective enough or cheap enough to warrant its use and approval in the United States," Evans commented. "I hope the results of these studies can move us past those arguments and into a meaningful discussion about the best ways to study when and how PrEP should be used."