The iPrEx study (Iniciativa Profilaxis Pre Exposicion or Prexposure Prophylaxis Initiative) was a double-blind, placebo controlled Phase III clinical trial that began in 2007 following three years of community consultation. iPrEx was the first human efficacy study of pre-exposure prophylaxis (PrEP) to report efficacy data. iPrEx was sponsored by the U.S. National Institutes of Health (NIH) through a grant to the J. David Gladstone Institutes, a non-profit independent research organization affiliated with the University of California at San Francisco. Additional support for the study was provided by the Bill & Melinda Gates Foundation. Study medication was donated by Gilead Sciences.
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iPrEx was funded by the U.S. National Institutes of Health and the Bill & Melinda Gates Foundation through a grant to the J. David Gladstone Institutes.[1]
Study medication was donated by Gilead Sciences.
Researchers studied 2,499 individuals at risk of HIV infection at study sites in six countries. All study participants received a HIV prevention package to reduce their risk of contracting HIV, including monthly HIV testing, safer sex counseling, condoms and treatment and care for sexually transmitted infections. Half of study participants received an experimental PrEP pill called Truvada, while the other half received a placebo.[1]
Participants in the study were recruited geographically as follows:[2]
| Geographical Demographics of IPrEx Recruitment | ||||
|---|---|---|---|---|
| country | study sites | percentage of participants | notes | |
| United States | Fenway Health (Boston) San Francisco Department of Public Health (San Francisco) |
9% | ||
| Ecuador | Fundación Ecuatoriana Equidad (Guayaquil) | 12% | ||
| Peru | Asociacion Civil Selva Amazonica (Iquitos) Asociación Civil Impacta Salud y Educación (Lima) Investigaciones Medicas en Salud (Lima) |
55% | ||
| Brazil | Evandro Chagas Institute Oswaldo Cruz Foundation (Rio de Janeiro) Projecto Praca Onze (Rio de Janeiro) University of São Paulo (São Paulo) |
15% | ||
| Thailand | Research Institute for Health Sciences (Chiang Mai) | 5% | ||
| South Africa | Desmond Tutu HIV Foundation (Cape Town) | 4% | ||
| total | 100% | |||
Of the 1248 study participants who received the placebo, researchers found that 64 became HIV infected. There were 36 HIV infections among the 1,251 participants who received Truvada, so there was an average reduction in HIV infection risk of 43.8%. This number includes study participants who did not take their daily pill consistently.[1]
This result prompted researchers to state that the treatment provided protection against the acquisition of HIV infection, and that there was a correlation between the presence of study drug in participants' blood and the protective effect.[3]
Time, an American magazine, named the result of iPrEx to be the most significant medical breakthrough of 2010.[4]
The Centers for Disease Control responded to the test results with the following cautions[5] -
The International Partnership for Microbicides issued a statement by founder Zeda Rosenberg saying that "The hard work and dedication of the iPrEx team and trial participants has led to a second successful proof-of-concept this year for an ARV-based HIV-prevention product. We must not falter at this important time in history when science shows us that, with sufficient resolve, we can begin to control and potentially reverse the HIV epidemic."[6]