Event Review – IAS, Rome, Italy
From 17 to 20 July 2011 the 6th IAS Conference on HIV Pathogenesis, Treatment and Prevention took place in Rome. Important news at this conference was the irrefutable evidence from the HPTN 052 trial that antiretroviral treatment can effectively prevent HIV infections.
The HPTN 052 trial investigated the chance of infection of an uninfected partner in 1763 serodiscordant couples after the HIV-infected partner had started antiretroviral treatment. Upon enrolment in the trial the CD4 cell count of the HIV-infected partner had to be between 350 and 550 cells/mm3 when HIV treatment is not yet indicated. Half of the infected individuals started treatment immediately, in the other half treatment was delayed until their CD4 cell count had dropped to below 250 cells/mm3.
A total of 39 partners got infected with HIV, 28 of them by their own partner. All but one of these infections were caused by the group in which treatment had been delayed. The single infection in the group that started immediately, probably occurred shortly after the start of therapy, i.e. before viral load suppression. The results show that treatment of the infected partner prevents infection with HIV. In addition, the number of clinical events was lower in the group that started treatment immediately.
Two other studies reported on the prophylactic use of antiretroviral drugs, or PrEP, pre-exposure prophylaxis. In the Partners PrEP study, executed in Uganda and Kenya, the prophylactic effect of tenofovir and truvada, a combination of tenofovir and emtricitabine, was compared in 4747 serodiscordant heterosexual couples with the effect of a placebo. In both the tenofovir and the truvada group the chance of infection with HIV was 70% lower compared to the placebo group.
In the TDF2 study in Botswana, truvada was compared with a placebo in 1219 sexually active heterosexuals. In the truvada group 9 infections occurred, compared to 24 in the placebo group, which means that truvada provided protection in 62% of cases in both men and women.
In another study in HIV-negative African women, the FEM-PrEP study, no effect of truvada was found in preventing HIV infections. The reason for the deviating results in this prophylaxis study is unclear.
For an overview of the presentations in this session, including the HPTN 052 trial, the Partners PrEP and the TDF2 please go to http://pag.ias2011.org/session.aspx?s=98.