Fact Sheet - Results

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Understanding the Results of VOICE



Key Points About The Results of VOICE


Results of VOICE

Results from the study’s primary data analysis – the answers to the study’s main questions about safety and effectiveness – include the following:

Because massive amounts of data were collected in VOICE as well as in VOICE sub-studies, results of these and other analyses are not expected to be available until the coming months or later in the year.

Context and Implications

Tenofovir Gel

In July 2010, the CAPRISA 004 study found tenofovir gel was safe and reduced the risk of HIV by 39 percent among women who used it before and after sex compared to women who used a placebo gel, a finding that was considered a major milestone for the field. (CAPRISA 004 also unexpectedly found that tenofovir gel also reduced the risk of HSV-2 by 51 percent, the first time that any kind of biomedical prevention method was shown to be effective against HSV-2.) But the study was relatively small (889 women from one region in South Africa) and its results included a wide confidence interval that in statistical terms meant the true level of effectiveness of tenofovir gel – when used before and after sex – could be anywhere between 6 and 60 percent. More data from a larger trial would be needed, and the U.S. FDA indicated that along with the results of CAPRISA 004, it would review data from VOICE, testing the gel’s daily use, as the second pivotal trial to support possible licensure of tenofovir gel. Subsequently, when a routine interim review of study data during VOICE determined that the gel wasn’t effective in preventing HIV, hope shifted to FACTS 001. FACTS 001 is an ongoing Phase III trial of the same regimen tested in CAPRISA 004 (before and after sex) that plans to enroll 2,900 women at nine South African sites, with results expected in 2015. Also ongoing is CAPRISA 008, an open-label follow-on study for former CAPRISA 004 participants that aims to determine the feasibility of gel delivery through family planning services.


As a co-licensee for tenofovir gel, CONRAD has been leading all discussions with drug regulatory authorities, including the FDA and the South African Medicines Control Council in support of the gel’s possible approval. In addition to data from CAPRISA 004 and FACTS 001, the FDA has indicated it will review the VOICE results and data from a large portfolio of studies conducted by both the MTN and CONRAD, including two studies that the MTN is currently conducting. One is a Phase II trial looking at safety and drug absorption in pregnant and breastfeeding women (MTN-008), while the other is a Phase I study examining how vaginal intercourse may affect drug absorption and drug activity (MTN-011).


In other MTN studies, researchers are evaluating a reduced glycerin formulation of tenofovir gel. In one trial to be conducted in South Africa and the United States, researchers will examine drug absorption patterns in both rectal and vaginal tissue when the gel is applied either vaginally or rectally (MTN-014), while a Phase II trial, MTN-017, hopes to determine whether the reformulated gel is safe and acceptable as a rectal microbicide among men who have sex with men (MSM) and transgender women in Peru, South Africa, Thailand and the United States. MTN-017, which is the first Phase II trial of a rectal microbicide, is expected to begin mid-2013.



The U.S. FDA’s approval of Truvada for HIV prevention, granted in July 2012, was based primarily on the results of two pivotal studies involving two different populations. The Partners PrEP Study involved 4,758 heterosexual couples in which one partner has HIV, while the iPrEx study enrolled 2,500 MSM. In Partners PrEP, which tested both tenofovir and Truvada, there were 75 percent fewer infections among those who took Truvada compared to placebo, while in iPrEx, Truvada was associated with a 42 percent reduction in HIV risk. A smaller trial of 1,200 heterosexual men and women in Botswana found a 62.6 percent reduction in HIV among those assigned to take Truvada.


These same studies also demonstrated that Truvada was more effective in protecting against HIV when the daily regimen was followed consistently. Indeed, Truvada was not effective in the FEM-PrEP Study, and many of its participants, 2,119 women from Kenya, South Africa and Tanzania, did not follow the daily pill-taking regimen as instructed.


In July 2012, the World Health Organization (WHO) issued guidance on PrEP for serodiscordant couples (in whom one partner is HIV-infected) and MSM, recommending its use only in the context of demonstration projects. WHO expects to issue formal PrEP implementation guidelines in 2015 that will consider emerging evidence from trials such as VOICE, as well as outcomes of in-country demonstration projects. Information about Truvada and its “real world” use is being collected in open-label trials, such as iPrEx OLE and the Partners Demonstration Project, and in several other demonstration projects and implementation studies taking place in the United States.


Oral Tenofovir

The Partners PrEP Study of serodiscordant couples found tenofovir reduced the risk of HIV by 67 percent compared to a placebo. Other than VOICE, only one other trial has evaluated daily use of oral tenofovir for preventing HIV. The Bangkok Tenofovir Study involved 2,400 injection drug users in Thailand, with results expected later in 2013.


Current HIV Prevention Trials in Women

There are three ongoing Phase III HIV prevention trials specifically focused on women. In addition to FACTS testing tenofovir gel used before and after sex, ASPIRE and The Ring Study are assessing whether a vaginal ring containing the ARV drug dapivirine is safe and effective for protecting against HIV when used by women for a month at a time. The dapivirine ring is the first ARV-based product to enter efficacy testing that is intended for monthly use and the first involving an ARV other than tenofovir or a tenofovir combination. ASPIRE – A Study to Prevent Infection with a Ring for Extended Use – is being conducted by the MTN. The Ring Study is being conducted by the International Partnership for Microbicides (IPM), which developed the dapivirine ring. More than 5,000 women from Africa will take part in these sister studies. Results of both are expected late 2014 or early 2015.


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More information about VOICE can be found at http://www.mtnstopshiv.org/news/studies/mtn003. A summary of other oral PrEP and microbicide studies can be found at www.avac.org.


About the MTN

The Microbicide Trials Network (MTN) is an HIV/AIDS clinical trials network established in 2006 by the National Institute of Allergy and Infectious Diseases with co-funding from the Eunice Kennedy Shriver National Institute of Child Health and Human Development and the National Institute of Mental Health, all components of the U.S. National Institutes of Health. Based at Magee-Womens Research Institute and the University of Pittsburgh, the MTN brings together international investigators and community and industry partners who are devoted to preventing or reducing the sexual transmission of HIV through the development and evaluation of products applied topically to mucosal surfaces or administered orally.


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See Also

Daily HIV Prevention Approaches Didn’t Work for African Women in the VOICE Study
Mar 4, 2013


Microbicide Trials Network Statement on Decision to Discontinue Use of Tenofovir Gel in VOICE, a Major HIV Prevention Study in Women

Nov 25, 2011


Questions and Answers on Decision to Modify VOICE, Outcome of November 17 DSMB Review

Nov 25, 2011


Microbicide Trials Network Statement on Decision to Discontinue Use of Oral Tenofovir Tablets in VOICE, a Major HIV Prevention Study in Women

Sep 28, 2011


Questions and Answers on Decision to Modify VOICE

Sep 28, 2011


HIV Prevention Trial Milestone: VOICE Study Completes Enrollment of 5,000 Women

Jun 6, 2011


Microbicide Trials Network Statement on the status of VOICE Study following announcement to close the FEM-PrEP trial

Apr 18, 2011


Trial shows ARVs can prevent HIV in men who have sex with men, making VOICE study in women more important than ever

Nov 23, 2010


Results of CAPRISA 004 a turning point for HIV prevention, say MTN researchers conducting VOICE

Jul 19, 2010


VOICE Study, a major HIV prevention trial for women, is launched in Zimbabwe

Sep 16, 2009


HIV prevention trial of ARV-based strategies to begin next month

Jul 20, 2009




MTN-003 (VOICE) Study Protocol

Source URL: https://www.mtnstopshiv.org/news/fact-sheet-results