What was HPTN 052?

 A Phase III, two-arm, randomized, controlled, multi-center trial to determine whether antiretroviral therapy (ART) can prevent the sexual transmission of HIV-1 in HIV-1 serodiscordant couples.

Who participated in the study?

HPTN 052 enrolled 1,763 HIV sero-discordant couples – where one person is HIV-infected and the other is not – at 13 sites in nine countries. The majority of the couples were heterosexual (97%).

What happened during the study?

HIV-infected partners were assigned to start ART at the beginning of the study, called the “early” arm (CD4 count at ART initiation 350-550 cells/mm3), or later in the study, called the “delayed” arm (CD4 count at ART initiation 350-550 cells/mm3). Those on the delayed arm started ART when their bodies’ immune systems were declining.

Results

In 2011, an interim review of the study data showed a 96% reduction of HIV transmission within the couples assigned to early ART, which was considered a major breakthrough finding. After the release of the results, all participants in the delayed ART arm were offered the opportunity to begin ART, and the study continued for four more years. By the end of the study, 1,171 couples remained in follow-up.

As reported at IAS 2015, the final results showed a 93% reduction of HIV transmission within couples when comparing the group in which the HIV-infected partner was assigned to early ART with the group in which the HIV-infected partners was assigned to the delayed ART group. Notably, there were only eight cases of HIV transmission within couples after the HIV-infected partner was given ART. Four of these eight cases were diagnosed soon after ART initiation and transmission likely occurred before the HIV-infected partner was virally suppressed. The other four were diagnosed when the HIV-infected partner had detectable levels of virus in the blood despite being on ART (i.e., treatment failure). 

Treatment failure may have occurred because participants either did not take their antiretroviral drugs as prescribed or had an HIV strain that resisted or acquired resistance to one or more of the drugs in their treatment regimen.

In the HPTN 052 study, HIV transmission from HIV-infected study participants to their partners was not observed when viral replication in the treated individual was stably suppressed by ART. 

In 2011, Science named HPTN 052 its "Breakthrough of the Year."

Why was this study important?

This was a landmark study proving that early ART can prevent HIV transmission.

Following the interim results of the HPTN 052 study, the World Health Organization recommended that antiretroviral treatment be offered to all people living with HIV who have uninfected partners to reduce HIV transmission in 2013.

“These findings demonstrate antiretroviral therapy, when taken until viral suppression is achieved and sustained, is a highly effective, durable intervention for HIV prevention,” - Myron Cohen, M.D., Director of the Institute for Global Health and Infectious Diseases at the University of North Carolina at Chapel Hill and Principal Investigator for HPTN 052.