Yet another large study aimed at preventing the spread of HIV by giving antiretroviral uninfected women (ARV) pills had to redesign the trial because of surprising and negative intermediate results.
the Microbicide Trials Network (MTN), which is funded by the National Institutes of Health, today announced that it has decided to stop one arm of a study involving over 5,000 women in South Africa, Zimbabwe and Uganda. The decision follows an interim review of the current trial by an independent supervisory board, which found that the drug tenofovir when used as pre-exposure prophylaxis (PrEP) had less effect in protecting women than expected. Although the board did not offer details on how many women have been infected on the drug compared to placebo, they said continue with tenofovir arm was "futile" because he would not give significant results. They do not give numbers because the parts of the trial are ongoing, testing other prevention measures.
Sharon Hillier, who heads the MTN, said his team is "extremely disappointed" and that he personally is humbled and a little confused. "I have to stop guessing how the study will turn out," says Hillier. "It breaks your heart."
The study, vaginal and oral interventions to control the epidemic (VOICE), began in September 09 and should end up about 1 year from now. MTN VOICE designed to compare three different strategies for PrEP: pills tenofovir, tenofovir in vaginal gel and pills Truvada (a combination of tenofovir and a second antiretroviral drug, emtricitabine). Tenofovir gel and pills Truvada arm of the study is still ongoing. "Research on HIV prevention is a constant reminder of what we do not know," said Mitchell Warren, head of the Coalition for the Defence of vaccine against AIDS, which closely follows the PrEP studies.
The new results particularly baffled people who follow this promising prevention strategy because it was mixed but encouraging results in two similar studies presented earlier this year. In April, researchers stopped a study called FEM-PrEP which evaluated Truvada pills in nearly 2,000 young women not infected in South Africa, Kenya and Tanzania after an interim analysis revealed that the pursuit was futile. But in July, the first glimpse of infection in a study that assessed by taking either tenofovir or pills Truvada as PrEP was found that both worked well in women. A key difference in the second trial called Partners PrEP, is it involved more than 4,700 couples in Kenya and Uganda in which one partner has tested positive at first, while both VOICE and FEM-PrEP mainly young women enrolled single.
Timothy Mastro, who helped lead the FEM-PrEP trunk to FHI 360 in Durham, NC, said teasing why the same drugs fail in a population and work in another, it will analyze two main factors: the biology and behavior. Studies have shown that small amounts of antiretroviral drugs taken orally reach the vaginal mucosa. This protection may have been submerged in VOICE and FEM-PrEP if male partners had higher levels of HIV than those of PrEP partners. Or maybe women Partners PrEP had more motivation to "adhere" to study protocols and take pills every day as directed, because they knew for certain dissimilar women in the other two trials that they had sex with a man infected with HIV. Men infected Partners PrEP may also be encouraged to join their uninfected partners. "It is very important for our two groups to compare data and study populations," said Mastro.
VOICE Hillier said she is looking forward to the group of Mastro complete their detailed analysis of the factors behind the disappointing results of FEM-PrEP. "There will not be a simple answer about who should get PrEP, and it is very clear that different people can get different results," she said.
Hillier emphasizes that these conflicting results emphasize that there is still much to learn about PrEP, which also worked well in gay men in another large recent study. This analysis should be done before those responsible for public health are making recommendations for its use. "The data are telling us something very important," said Hillier. "People thought that ARVs would be magical, and you could sprinkle them there and people use them all the time and they prevent all infections. These studies teach us loud and clear that when and how they will work raises very nuanced questions. And these studies teach us things we do not want to know. "
VOICE hopes to have the results for the other two arms of the study by the end of next year.
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