Disappointing Results Prompt Early End to FEM-PrEP Study of Pill-Based PrEP in African Women
Posted Apr 18 2011 5:24pm
The recent success of the iPrEx study has raised hopes that pill-based pre-exposure prophylaxis (PrEP) will become an important new tool for preventing HIV transmission. However, because the iPrEx study included only men who have sex with men (MSM) and transgender women, many HIV researchers and advocates have been awaiting the results of other studies to see whether pill-based PrEP can also reduce the risk of HIV infection in other groups, including mixed-HIV-status couples, heterosexual women, and injection drug users.
The hopes that pill-based PrEP might be a widely applicable prevention tool suffered a major setback on April 18, when Family Health International (FHI) announced its decision to end the FEM-PrEP study due to disappointing early results. After reviewing the study’s interim data, FEM-PrEP’s Independent Data Monitoring Committee (IDMC) concluded that the study “will be highly unlikely to be able to demonstrate the effectiveness of Truvada…in preventing HIV infection in the study populations.”
Working in partnership with African research centers, FHI enrolled nearly 2,000 HIV-negative heterosexual women in the FEM-PrEP study between early 2009 and February 2011. The participating women were between the ages of 18 and 35 and from Kenya, South Africa, and Tanzania. About half of the participating women have received daily PrEP with the antiretroviral (ARV) pill Truvada, which contains the ARVs tenofovir and emtricitabine. The remaining women have received a placebo (dummy) pill.
The study’s IDMC found that by February 2011, a total of 56 women in the FEM-PrEP study had become infected with HIV and that there were an equal number of infections in the PrEP and placebo groups. The HIV-infection rates in both groups were 5% per year.
According to FHI:
The FEM-PrEP outcome is surprising and disappointing, given a number of earlier studies suggesting the promise of PrEP using antiretrovirals… There are a number of possible reasons for the study findings, including low adherence to study regimen, a true lack of effect of the product among women (versus men who have sex with men), or other factors still to be determined. FHI will be conducting further analyses and will share additional findings in the coming months. The IDMC commended the trial team on a study conducted to a high standard with good follow-up and careful attention to good clinical practice and ethical standards.
The global prevention advocacy group AVAC issued a statement after the announcement that included the following:
“Today’s announcement about the FEM-PrEP study is disappointing,” said Mitchell Warren, AVAC executive director. “However, it must be seen as what it is – the closure of a single trial in a field that has generated exciting results in the recent past. Even with this finding, there is still a strong rationale for continuing other trials, including those in women, in hopes of obtaining better results in the future.
“The premature closing from FEM-PrEP does not predict the findings from either VOICE or Partners PrEP,” Warren said. [VOICE and Partners PrEP are ongoing African studies looking at pill-based PrEP in mixed-HIV-status couples and heterosexual women.] “It is too soon to tell whether the differences observed between iPrEx and FEM-PrEP are due to the route of exposure, pill-taking behavior, biological differences in drug activity, or some other factor. Along with further analysis of FEM-PrEP data, VOICE, Partners PrEP, and other ongoing trials will add critical pieces to the puzzle of if and how to deploy PrEP as an effective prevention tool.”