July 20, 2015
Updated July 20, 2015
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The HPTN 052 study is a Phase III randomized clinical trial with the primary objective of evaluating whether antiretroviral drugs, which are mainly licensed to treat HIV infection, can prevent the sexual transmission of HIV among couples in which one partner is HIV-infected and the other is not (serodiscordant couples). Additionally, the study was designed to evaluate the optimal time to begin antiretroviral therapy in order to reduce illness and death among people infected with HIV.
The study was sponsored by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH). The trial was led by protocol chair Myron Cohen, M.D., Associate Vice Chancellor for Global Health at the University of North Carolina at Chapel Hill and director of the university’s Institute for Global Health and Infectious Diseases. The study was conducted by the HIV Prevention Trials Network (HPTN), which is largely funded by NIAID with additional funding from the National Institute on Drug Abuse and the National Institute of Mental Health, both part of NIH. Additional support was provided by the NIH-funded AIDS Clinical Trials Group.
A total of 1,763 serodiscordant couples participated in the study. Each participant was at least 18 years of age; the median age of the study population was 33. The vast majority of the couples (97 percent) were heterosexual. At the time of enrollment, the HIV-infected participants (890 men, 873 women) had CD4+ T-cell counts, a key measure of immune system health, between 350 and 550 cells per cubic millimeter (mm3) within 60 days of entering the study. The median CD4 count at study entry was 436 cells/mm3. The HIV-uninfected partners tested negative for the virus within 14 days of entering the study.
What was the study’s design?
Participating couples were randomly assigned to one of two treatment groups. In the first group, the HIV-infected participants immediately began taking a combination of three antiretroviral drugs. In the second group, the HIV-infected participants delayed taking antiretroviral drugs until either their CD4 counts fell below 250 cells/mm3 or they were diagnosed with an AIDS-related illness, as defined by World Health Organization guidelines. All participants in both groups received counseling on safe sex practices, free condoms, treatment for sexually transmitted infections, frequent HIV testing, and evaluation and treatment for any complications related to HIV infection.
HPTN 052 participants were given a combination three- or four-drug regimen using the following 11 HIV drugs:
In April 2011, the HPTN 052 investigators discovered that starting HIV treatment early, when the immune system is relatively healthy, reduced the risk of sexually transmitting the virus to an uninfected partner by 96 percent over 18 months.
The investigators observed a total of 78 new HIV infections among the originally uninfected partners. Cases where the HIV-infected study participant was the likely source of his or her partner’s infection, as determined by specialized laboratory testing, were classified as linked. Overall, 46 of the 78 partner infections were linked.
The difference between the efficacy reported in the 2011 interim analysis of the trial (96 percent) and the efficacy reported in the final results (93 percent) is small. Moreover, in the final analysis, all eight linked partner infections that were diagnosed after antiretroviral treatment began are likely to have occurred when the virus was not suppressed by the treatment regimen. The investigators did not observe any linked partner infections when the HIV-infected participant’s virus was stably suppressed by antiretroviral therapy. These results indicate that antiretroviral therapy is highly effective at preventing heterosexual transmission of HIV if viral suppression is achieved and maintained..
What happened to study participants who became infected with HIV during the trial?
All HIV-infected participants who started antiretroviral therapy during the study were connected to local health-care services for ongoing treatment after the trial ended.
A data and safety monitoring board (DSMB) is an independent committee composed of clinical research experts, statisticians, ethicists, and community representatives that provides additional oversight of a clinical study. The DSMB regularly reviews data while a clinical trial is underway to ensure the safety of the participants and that any benefits shown in the study are quickly made available to all participants. A DSMB may recommend that a clinical trial, or part of a trial, be stopped or modified if there are safety concerns or if the trial objectives have been achieved or are unlikely to be achieved. A DSMB looks at analyses that are not available to the investigators. Restricting certain information to the DSMB while the trial is ongoing helps to maintain the integrity of the study.
More information about the study is available at ClinicalTrials.gov.
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Last Updated July 20, 2015
Last Reviewed July 18, 2015