April 18, 2011
In the latest twist on the biomedical prevention roller-coaster, a trial testing Pre-Exposure Prophylaxis (PrEP) in women has ended early because it failed to show positive results. That is bad news. It is also surprising news given the same intervention seems to have worked with men who have sex with men. Why the FEM-PrEP Project did not show positive outcomes is not yet known. Adherence to the drug seems to have been high, but we do not yet know how adherence was measured. Too many biomedical prevention trials have relied on self-report adherence, making negative results difficult to interpret. It is also possible that the different HIV transmission dynamics of vaginal and anal intercourse account for the findings. In addition, risk reduction counseling, condoms, and repeated testing that all women received may have reduced the study's statistical power. We will have to wait for more information.
One thing is clear. The behavioral implications of PrEP remain as important as ever. Behavioral and social scientists working in AIDS should pay close attention to what we hear next and consider how 30 years of behavioral research may help move biomedical prevention technologies along. The Press Release is reproduced below.
April 18, 2011
Following a scheduled interim review of the FEM-PrEP study data, the Independent Data Monitoring Committee (IDMC) advised that the FEM-PrEP study will be highly unlikely to be able to demonstrate the effectiveness of Truvada [emtricitabine (FTC) and tenofovir disoproxil fumarate (TDF)] in preventing HIV infection in the study population, even if it continued to its originally planned conclusion.