Prep

The iPrEx study, testing the safety and effectiveness of daily tenofovir/emtricitabine in preventing HIV transmission in 3000 HIV-negative men who have sex with men (MSM), is expecting to release results in early 2011. In addition, a study funded by the CDC testing daily dosage of tenofovir (CDC 4323) to prevent HIV infection in injection drug users in Bangkok, Thailand is expecting to release results by early 2011. These trials will provide the first effectiveness results for daily oral use of ARVs for HIV prevention. Depending upon the results in PrEP trials of tenofovir or tenofovir/emtricitabine (CDC 4323, iPrEx), a second confirmatory trial for licensure may be needed. If these trials provide proof of concept for ARV prophylaxis as a method of HIV prevention, there may be a movement to find an ARV that is not currently used in treatment programs for use as a PrEP drug. Thus, additional ARVs may need to be tested as PrEP agents to address safety or resistance concerns. The cost of additional PrEP trials could equal US$40-60 million each based upon the cost of current PrEP trials.