How have recent data on the antiretroviral drug Truvada and its
possible approval as an HIV prevention drug affected the design
of AIDS vaccine trials? Several novel strategies have in recent
years shown promise in preventing HIV infection (see VAX July
2011Spotlight article, An Antiretroviral Renaissance). Among
these is pre-exposure prophylaxis, or PrEP—the administration of
antiretrovirals (ARVs) either orally or topically to HIV-
uninfected individuals. One of those studies, known as iPrEx,
revealed that Truvada—a combination of the ARVs tenofovir and
emtricitabine—was 44% effective in preventing HIV infection
among nearly 2,500 men and transgendered women who have sex with
men. The study, which was conducted in six countries including
the US, prompted Truvada’s maker, Gilead Sciences, to apply for
regulatory approval from the US Food and Drug Administration
(FDA) to expand the use of ARV as a therapy to prevent HIV
acquisition, making it the first antiretroviral drug to be
considered for such use. In June