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Issue No. 17 | April 22, 2011

News and Features

FEM-PrEP HIV Prevention Study Closes Early: Implications for NIAID Research

“FHI announced that it is closing its FEM-PrEP HIV prevention clinical trial early because an independent monitoring committee concluded that based on current data, the study would be unable to demonstrate the effectiveness of the study drug in preventing HIV infection in the women enrolled in the trial. The Phase III clinical trial was examining whether once daily oral Truvada, an antiretroviral drug currently approved to treat HIV infection, could prevent male-to-female HIV infection among women at high risk for infection through sexual intercourse. The study was being conducted in Kenya, South Africa and Tanzania.

“Currently, the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, is evaluating Truvada, along with two other strategies, in a study known as VOICE (Vaginal and Oral Interventions to Control the Epidemic). The VOICE study is comparing daily use of Truvada, oral tenofovir—another antiretroviral drug approved to treat HIV infection—and a tenofovir-based vaginal gel for safety and effectiveness in preventing male-to-female HIV transmission. …

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

“NIAID will continue with the VOICE study while informing all current participants about the FHI findings as soon as possible; potential new volunteers will be informed as part of the screening and enrollment process.”

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NIAID Researchers Propose the Use of Adaptive Clinical Trial Designs in HIV Vaccine Studies

“In the past 12 years, four large-scale efficacy trials of HIV vaccines have been conducted in various populations.  Results from the most recent trial—the RV144 trial in Thailand,  which found a 31 percent reduction in the rate of HIV acquisition among vaccinated heterosexual men and women—have given scientists reason for cautious optimism. Yet building on these findings could take years, given that traditional HIV vaccine clinical trials are lengthy, and that it is still not known which immune system responses a vaccine needs to trigger to protect an individual from HIV infection.

“To accelerate HIV vaccine development, scientists working at and funded by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, propose using adaptive clinical trial designs. These designs allow a trial to be modified in response to data acquired during the study. ...

“In a paper appearing this week in Science Translational Medicine, the scientists review the four major HIV vaccine trials undertaken thus far and the scientific questions and challenges that remain.”

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Study Investigates Optimal Time to Initiate Antiretroviral Therapy in HIV-Infected People

“Most clinical guidelines recommend that AIDS-free, HIV-infected persons with CD4 cell counts below 0.350 × 10(9) cells/L initiate combined antiretroviral therapy (cART), but the optimal CD4 cell count at which cART should be initiated remains a matter of debate. … Prospective observational data from the HIV-CAUSAL Collaboration and dynamic marginal structural models were used to compare cART initiation strategies for CD4 thresholds between 0.200 and 0.500 × 10(9) cells/L. … 20 971 HIV-infected, therapy-naive persons with baseline CD4 cell counts at or above 0.500 × 10(9) cells/L and no previous AIDS-defining illnesses, of whom 8392 had a CD4 cell count that decreased into the range of 0.200 to 0.499 × 10(9) cells/L … were included in the analysis. … Compared with initiating cART at the CD4 cell count threshold of 0.500 × 10(9) cells/L, the mortality hazard ratio was 1.01 (95% CI, 0.84 to 1.22) for the 0.350 threshold and 1.20 (CI, 0.97 to 1.48) for the 0.200 threshold. The corresponding hazard ratios were 1.38 (CI, 1.23 to 1.56) and 1.90 (CI, 1.67 to 2.15), respectively, for the combined end point of AIDS-defining illness or death. … Initiation of cART at a threshold CD4 count of 0.500 × 10(9) cells/L increases AIDS-free survival. However, mortality did not vary substantially with the use of CD4 thresholds between 0.300 and 0.500 × 10(9) cells/L.”

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