- Category: HIV Prevention
- Published on Monday, 18 July 2011 00:00
- Written by Liz Highleyman
Researchers at the 6th IAS Conference on HIV Pathogenesis, Treatment and Prevention (IAS 2011) taking place this week in Rome presented eagerly awaited data from 3 large trials showing that starting combination antiretroviral therapy (ART) early, and pre-exposure prophylaxis (PrEP) using tenofovir/emtricitabine, can dramatically cut the risk of HIV transmission.
Top-line findings from the 2 PrEP studies -- Partners PrEP and TDF2 -- were released last week. Results from HPTN 052, the early ART trial, came out in May. Researchers at IAS 2011 presented further details from all these studies at a press conference and oral abstract session on Monday, July 18; the HTPN results were simultaneously published in the online edition of the New England Journal of Medicine.
"The issue of treatment as prevention is critical and huge and should all be considered in a comprehensive approach," National Institutes of Allergy and Infectious Diseases director Anthony Fauci said at the presser. "The idea of tension between treatment and prevention -- we should forget about and put it behind us, because treatment and prevention."
Researchers Myron Cohen, Michael Thigpen, and Jared Baeten discuss prevention trial results at IAS 2011 press conference:
HIVandHepatitis.com will feature more in-depth analysis of the extensive study data in coming days.
Below is an edited excerpt from an International AIDS Society press release summarizing the study findings.
Antiretroviral Treatment is HIV Prevention: The Proof is Here
Leading researchers and international experts to discuss the policy and prevention implications of three groundbreaking trial results: the HPTN 052 study, the Centers for Disease Control and Prevention TDF2 study and the University of Washington Partners PrEP Study
Monday, 18 July, 2011 -- Rome, Italy
In light of announcements this past week about new data on PrEP effectiveness, both the HPTN 052 abstract session (16.30, SR1) and press conference have been expanded to include presentations on the Partners PrEP Study and the CDC’s TDF2 study, both of which were released on 13 July in the US.
Myron Cohen: HPTN 052 Protocol Chair and Associate Vice Chancellor for Global Health and Director of the Institute of Global Health and Infectious Diseases at the University of North Carolina
About the HPTN 052 study:
The HIV Prevention Trials Network (HPTN) 052 study found that men and women, who were already infected with HIV, had a reduced risk of transmitting the virus to their uninfected sexual partners by 96% through early initiation of combination antiretroviral therapy (cART). HPTN 052 also found that early initiation of cART benefits the HIV-infected individual.
HPTN 052 was designed to evaluate whether early versus delayed use of cART by HIV-infected individuals would reduce transmission of HIV to their uninfected partners and benefit the HIV- infected individuals as well. During the course of the study, 39 participants who had been HIV- uninfected at the start of the study became infected with HIV. Of those, 29 were linked transmissions, where the virus from the originally-infected partner was confirmed by genetic analysis to be the source of infection in the newly infected sexual partner. Only one of the 29 infections occurred in the early cART arm. Based on the latest analyses, this one transmission most likely occurred close to the time the couple enrolled in the study and before HIV viral replication could have been suppressed by cART in the infected participant.
The new analyses also provide more insight as to how early initiation of cART benefits the HIV- infected person. Individuals who were put on early cART maintained higher absolute CD4 counts than those in the delayed arm, who received treatment when their CD4 counts fell below 250 cells/mm3 or an AIDS-related event occurred. Early cART was also associated with a 41% reduction in HIV-related illnesses or death, a direct benefit for the HIV-infected partner. The reliable suppression of HIV among HIV-infected people in the early treatment arm suggests potential impact on adherence when the infected individual is informed that their cART may also benefit their partner.
Michael C.Thigpen: Principal study investigator and epidemiologist at the Centers for Disease Control and Prevention (CDC)
About the TDF2 study:
The CDC TDF2 study was a randomized, placebo-controlled trial examining the safety and efficacy of a once-daily tablet containing tenofovir disoproxil fumarate and emtricitabine (TDF/FTC, known by the brand name Truvada) for reducing the risk of HIV acquisition among heterosexual men and women at two sites in Botswana. In addition to study medication, all participants received a comprehensive package of HIV prevention services. The study provides strong evidence that a daily oral dose of antiretroviral drugs used to treat HIV infection can reduce HIV acquisition among uninfected individuals exposed to the virus through heterosexual sex. The study, conducted in partnership with the Botswana Ministry of Health, found TDF/FTC reduced the risk of acquiring HIV infection by roughly 63 percent overall in the study population (95% CI, 21.5 to 83.4; p= 0.0133) ,and by 78 percent among trial participants believed to be taking study medications (95% CI 41.2 to 93.6, p=0.0053). Adherence (as measured by pill count) was high, both among those receiving TDF/FTC and those receiving placebo (84.1 percent and 83.7 percent, respectively). Reported sexual risk behavior was similar between the two study arms. Consistent with other PrEP studies, preliminary analyses did not identify any significant safety concerns associated with daily use of TDF/FTC.
Jared Baeten: Co-leader of the Partners PrEP Study and epidemiologist at the University of Washington
About the Partners PrEP Study:
This is a phase III, randomized, double-blind, placebo-controlled trial of daily oral tenofovir and emtricitabine/tenofovir for the prevention of HIV-1 acquisition among HIV-1 seronegative partners in heterosexual HIV-1 serodiscordant partnerships. The study is funded by the Bill & Melinda Gates Foundation. The University of Washington coordinated the trial, in collaboration with investigators at nine sites in Kenya and Uganda. The study enrolled 4758 HIV-1 serodiscordant couples; HIV-1 uninfected partners were randomly assigned in equal numbers to one of three study groups: one group received tenofovir, one emtricitabine/tenofovir, and one matching placebo. All study participants received a comprehensive package of HIV-1 prevention services. On 10 July 2011, the Partners PrEP Study independent Data and Safety Monitoring Board (DSMB) recommended, after review of the study data, that the study results be publically reported and the placebo arm be discontinued, because of definitive demonstration of HIV-1 protection from pre-exposure prophylaxis (PrEP) in the study population. Tenofovir reduced HIV-1 risk by 62% (95% CI 34 to 78, p=0.0003), emtricitabine/tenofovir by 73% (95% CI 49 to 85, p<0.0001). Efficacy for tenofovir and emtricitabine/tenofovir were not statistically different. 62% of HIV negative participants were male, 38% were female: both PrEP medications reduced HIV-1 risk in men and women. Adherence to the daily PrEP medication was very high – more than 97% of dispensed doses of the study medications were taken. More than 95% of participants were retained in study follow-up. Safety parameters were comparable across the three study groups.
M Cohen, Y Chen, M McCauley, et al. Antiretroviral treatment to prevent the sexual transmission of HIV-1: results from the HPTN 052 multinational randomized controlled trial. 6th International AIDS Society Conference on HIV Pathogenesis, Treatment and Prevention (IAS 2011). Rome. July 17-20, 2011. Abstract MOAX0102.
MS Cohen, YQ Chen, M McCauley, et al. Prevention of HIV-1 Infection with Early Antiretroviral Therapy. New England Journal of Medicine (abstract). July 18, 2011 (Epub ahead of print).
International AIDS Society. Antiretroviral Treatment is HIV Prevention: The Proof is Here. Press release. July 18, 2011.