<unk>  logo<unk>  (from , "pre-exposure prophylaxis initiative") was a phase III clinical trial to determine whether the antiretroviral medication emtricitabine/tenofovir (as tenofovir disoproxil fumarate) could safely and effectively prevent HIV acquisition through sex in men who have sex with men and transgender women.<unk>  was the first human study of an HIV prevention strategy known as pre-exposure prophylaxis, or PrEP. The study began in 2007 at four study sites in Peru and Ecuador, following three years of extensive community and stakeholder consultation. In 2008 the study expanded to seven additional sites in Brazil, South Africa, Thailand and the United States.
IPrEx
C-KAD
QS-21
Ze339
ACDC 
GcMAF
BGR-34
PC3