HIV Prevention Trial Halted for Lack of Efficacy

Emma Hitt, PhD

April 20, 2011

April 20, 2011 — The FEM-PrEP HIV trial has been stopped early because of failure of the oral combination of tenofovir and emtricitabine (Truvada, Gilead) to show efficacy as pre-exposure prophylaxis (PrEP) for male-to-female HIV infection, according to the findings of a phase 3 clinical trial being conducted in Kenya, South Africa, and Tanzania.

Family Health International prematurely halted the FEM-PrEP study earlier this week after an independent monitoring committee concluded that current data did not support the effectiveness of the combination treatment in preventing male-to-female HIV transmission.

According to a National Institute of Allergy and Infectious Diseases (NIAID) news release, in 2009, "approximately half of the estimated 2.6 million new HIV infections globally occurred among females, the vast majority among women having unprotected sex with HIV-infected men."

The combination is already approved to treat HIV infection. Earlier studies using the combination treatment as PrEP showed promising results. NIAID sponsored a previous PrEP initiative clinical trial named iPrEx, which demonstrated that treatment reduced the risk for HIV transmission among men who have sex with men by 43.8%.

"Although it is disappointing that the FEM-PrEP trial will be unable to continue and to provide information about [the treatment’s] potential as HIV prevention among women, the need for continued research in this area is imperative," the NIAID states.

NIAID also launched a study known as VOICE (Vaginal and Oral Interventions to Control the Epidemic) in September 2009, which is designed to compare the safety and efficacy of oral tenofovir and a tenofovir-based vaginal gel in preventing HIV infection in heterosexual women. The VOICE study, which is being conducted in South Africa, Uganda, and Zimbabwe, has a target enrollment of 5000 women. That study will continue and is expected to conclude in 2013.

"Although male condoms effectively prevent HIV infection, women need methods to protect themselves that are not dependent on their sexual partners," they write.

The investigators have disclosed no relevant financial relationships.


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.