NIH halts use of tenofovir gel in VOICE trial

The NIH has discontinued the use of tenofovir vaginal gel in women included in the Vaginal and Oral Interventions to Control the Epidemic — or VOICE — HIV prevention trial because of a lack of efficacy, according to an NIH press release.

The trial, conducted by the NIH-funded Microbicide Trials Network, was launched in September 2009 to evaluate two HIV prevention strategies in women — an investigational microbicide gel containing tenofovir, and oral tablets containing tenofovir alone or co-formulated with emtricitabine.

During an interim review, the data and safety monitoring board found that although tenofovir was safe, it did not appear effective. The data and safety monitoring board reported no difference in efficacy between once-daily 1% tenofovir vaginal gel vs. placebo gel. There was a 6% HIV incidence rate among participants in both groups.

Approximately 2,000 women in both groups were advised to discontinue use of the tenofovir and placebo gels, according to the press release. According to the NIH, there were no major safety concerns with either the tenofovir gel or oral tablets, and oral tenofovir and emtricitabine will continue to be investigated in the study.

“Because the trial is continuing, all other study data remain confidential, so NIAID cannot speculate about why tenofovir gel showed no benefit among VOICE study participants,” according to the NIH. “Factors that may have contributed to this outcome are being further investigated.”

For more information about the VOICE study, please visit: www.mtnstopshiv.org/news/studies/mtn003.

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