CAPRISA’S RESPONSE TO THE ANNOUNCEMENT OF THE VOICE STUDY RESULTS: WOMEN HAVE TO USE TENOFOVIR-CONTAINING TABLETS AND GELS TO SHOW THAT THEY PREVENT HIV INFECTION
Today’s announcement by the Microbicides Trials Network (MTN) on its tenofovir tablet and gel study (MTN 003) confirmed that low adherence to the prescribed daily pills and gels was the basis for its results which showed no protection against HIV. The results were released at the Conference on Retroviruses and Opportunistic Infections, taking place this week in Atlanta, USA.
“The high HIV infection rates in young African women, which were also seen in the VOICE trial, highlight the urgent need for women-initiated HIV prevention methods,” said CAPRISA’s Scientific Director and Lead Researcher on the CAPRISA 004 tenofovir gel trial, Professor Quarraisha Abdool Karim. “There is strong evidence that antiretroviral drugs like tenofovir are effective in preventing HIV but even the best proven medication will not be effective if it is not used as directed.”
The VOICE study set out to assess whether tenofovir-containing tablets and gels are safe and effective in preventing the sexual transmission of HIV in women. The study, which enrolled 5029 women from South Africa, Zimbabwe and Uganda, investigated the safety and effectiveness of three products taken daily: an oral tablet containing tenofovir; an oral tablet containing a tenofovir-emtricitabine combination (known as Truvada); and tenofovir gel (a vaginal microbicide with the same active ingredient as the oral tenofovir tablet). “CAPRISA commends the MTN team for their dedication and hard work in conducting this important study,” commented Professor Abdool Karim, “we are well aware of the challenges in obtaining high adherence to prevention medications – not just for HIV prevention medication.”
In September 2011, the tenofovir tablet arm and, in November 2011, the tenofovir gel arm of the VOICE study were stopped early. Interim results suggested that neither the tablet nor gel were any better at preventing HIV-infection than the placebos. The Truvada tablet arm continued through to study completion in late 2012.
Truvada and tenofovir tablets are widely used antiretroviral medications which are commonly prescribed for the treatment of HIV-positive patients. In May 2012, the US Food and Drug Administration (FDA) approved Truvada for HIV prevention to be taken as a daily tablet for pre-exposure prophylaxis (PrEP), based on the evidence from 3 trials which showed that Truvada successfully prevents HIV acquisition. In 2010, the CAPRISA 004 trial showed that tenofovir gel used at the time of sex can effectively prevent HIV in women. In this study, women who used the gel consistently had higher the levels of protection than women who were less adherent.
The quest continues to find women-initiated HIV prevention technologies. Using the same dosing strategy as CAPRISA 004, tenofovir gel is currently being assessed in a confirmatory study by the FACTS Consortium amongst 2900 women in nine sites across South Africa. The FACTS study together with the CAPRISA 004 results could lead to licensure of tenofovir gel for HIV prevention.
CAPRISA is also undertaking a study (known as CAPRISA 008) to assess coitally-prescribed gel uptake and adherence as part of providing post-trial access to tenofovir gel. In this 30-month study, which commenced in October 2012, the effectiveness of integrating tenofovir gel into family planning services is being assessed.
In sub-Saharan Africa, young women bear the brunt of the HIV epidemic, accounting for 60% of new HIV infections acquired through age-disparate sexual partnerships with limited ability to protect themselves, as they unable to negotiate mutual monogamy, condoms or medical male circumcision. CAPRISA reaffirms its commitment to continue working with the MTN and other partners in finding solutions and new biomedical technologies that empower women and to bring us closer to ending the HIV epidemic.