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Promising HIV gel fails in latest trial

Anti-HIV gel doesn’t stop virus transmission, new study confirms, and may not increase infection risk

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4:49pm, July 30, 2008
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The anti-HIV gel Ushercell is not effective at stopping HIV transmission, an international research team reports in the July 31 New England Journal of Medicine. The gel also appears not to increase rates of HIV transmission as earlier results had suggested.

A clinical trial testing the effectiveness of the gel in preventing HIV infection was stopped early last year after an analysis not only showed a lack of effectiveness, but also linked the gel to higher HIV transmission rates.

But in a detailed analysis of the results, scientists showed that the supposed increased risk of contracting HIV, the virus that causes AIDS, when using the gel is not statistically significant. The new study clarifies the 2007 interim findings.  

The phase III clinical trial was launched in 2006 and initially enrolled 1,398 women living in Africa and India. These women were randomly assigned so that half received the experimental gel and half received the placebo.

In 2007, an independent committee reviewed the trial’s interim results and found that 24 women using the experimental gel became infected with HIV, while only 11 women using the placebo gel contracted the virus. Because of this finding, the committee recommended the trial be terminated early. The researchers complied.

Later data that took into account newfound infections, however, shows that the trend to contract the virus was still higher in the experimental group. But the increase was not statistically significant, so the difference could have been due to chance, says Lut Van Damme, lead author of the study and now at the nonprofit Family Health International in Arlington, Va.

“The key message is that this data analysis shows that the gel doesn’t appear to be unsafe, just ineffective at preventing HIV transmission,” says Wafaa El-Sadr, a clinical epidemiologist at ColumbiaUniversity’s Mailman School of Public Health. El-Sadr was not involved in this study, but did help conduct one of the many earlier trials to ensure that the gel was not harmful to women’s health.

The full results of the trial are “most disappointing because researchers in this field have been waiting, hoping and promising that this gel would be a success,” El-Sadr adds.

When the trial was stopped in early 2007, 706 women had been given the experimental gel and 692 women received a placebo gel. Women who already had HIV were not allowed to participate. The participants, from South Africa, Benin, Uganda and India, were instructed to use the gel one hour before having sex and to use condoms, although participants did not always adhere to instructions.

Judging from the data collected in interviews, women were more likely to use the gel with or without a condom when with new or intermittent partners, but less likely to use any HIV-prevention method when having sex with their primary partners, says Van Damme.

Women who tested positive for HIV after the trial began were given antiretroviral treatment and access to medical care.

Sociocultural norms make it difficult for women living in Africa and parts of India to persuade men to wear condoms during sex, El-Sadr says, so women there desperately need ways to protect themselves against HIV.

Currently there are 14 other compounds in advanced development and 41 in discovery, or early development, that might fill that need, Vann Damme notes.

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