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A vaginal gel containing Gilead Sciences Inc.’s HIV drug Viread, which has shown promise at preventing infections in past tests, was ineffective when used by at-risk women in South Africa, a study found.
In a trial of 2,059 HIV-negative South African women, there were 123 HIV infections, with 61 in the group that got the gel and 62 in the group that got a placebo.
The failure to prevent infections was likely because women weren’t able to consistently use the gel, which is meant to be applied before and after sex, according to research presented Tuesday at the Conference on Retroviruses and Opportunistic Infections in Seattle.
The results are the latest in a series of setbacks for a strategy to stop HIV that involves the use of preventive drugs, called PrEP, or pre-exposure prophylaxis.
“A product that is applied around the time of sex may be suitable for some women, but it did not meet the needs of the majority in our study, most of whom were young, single and lived with their parents,”
Helen Rees, the lead author of the study, said in a statement. “Methods that are easier for women to incorporate into their lives are likely to be more effective.”
The study found that trial participants used the gel as directed at least half of the time, and that only a small group used it every time before and after sex. Those who showed signs of having used the drug consistently had a lower rate of HIV acquisition than others.
The study was sponsored by the Bill & Melinda Gates Foundation, U.S. Agency for International Development and the South African Departments of Science Technology and Health and followed the women from October 2011 to August 2014.
Women were randomly assigned either the gel or a placebo and trained in its use. Both groups contracted the virus at the same rate, with four out of every 100 women becoming infected each year.
Gilead made $1.06 billion from Viread in 2014 and $3.4 billion from Truvada. The Foster City, California-based company has licensed the Viread gel for use in poor countries to CONRAD, a reproductive health research group that’s been part of USAID since 2006.
Rees said she’s hopeful PrEP can be made more effective by using more convenient ways of administering the drugs, including antiviral rings inserted vaginally once a month, eliminating the need to use the gel every time women have sex.
While Gilead’s Truvada didn’t catch on for preventive use at first, new evidence suggests people will use it consistently if it’s available, according to Mitchell Warren, executive director of AVAC, a New York-based organization that advocates for HIV prevention.
“We now have data emerging over the last four or five years that oral PrEP amongst a range of populations does have higher efficacy” than gels, Warren said in a phone interview. “We’re seeing very high levels of adherence, very high levels of efficacy.”
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