HIV Trial Scrapped After Gel Found to Be Ineffective

A routine review of data from a large clinical trial found that a tenofovir-based vaginal gel was not effective in preventing HIV in women, researchers reported Friday.

Since the review found no safety concerns with the gel, women in the vaginal gel arms of the VOICE (Vaginal and Oral Interventions to Control the Epidemic) study will be told to discontinue its use at their next regularly scheduled clinic visit, the Microbicides Trial Network said.

In 2010, the CAPRISA (Center for the AIDS Program of Research in South Africa) study in South Africa found a tenofovir-based microbicide vaginal gel was 39 percent more effective than placebo gel when used before and after sex. In regular users, it was 54 percent effective. The VOICE study, begun in 2009 with 5,029 sexually active HIV-negative women in South Africa, Uganda, and Zimbabwe, was expected to back those findings. Instead, the interim data review found no difference between the tenofovir gel and placebo, with an annual HIV incidence of 6 percent in the placebo group, compared with 6.1 percent for tenofovir gel users.

Although VOICE previously scrapped a trial of oral tenofovir for lacking efficacy, it is continuing to study the safety and effectiveness of oral Truvada (tenofovir and emtricitabine) taken daily to prevent HIV, or pre-exposure prophylaxis (PrEP).

"For now, the study will continue and we will work to complete the remaining visits for the women continuing in the study," wrote researchers Sharon Hillier and Ian McGowan. "We are all eager to understand whether adherence, our daily dosing strategy, inflammation or other factors could explain the lack of oral and vaginal tenofovir effectiveness in VOICE. We will not likely have all of the assays completed until later next year."

For more information, visit: www.mtnstopshiv.org/node/3909.

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