For many years, researchers have been trying to develop a cream or gel, known as a microbicide, that could be used to help prevent HIV transmission during sex. However, the latest and largest study, which took place in Uganda, South Africa, Tanzania and Zambia, has yielded disappointing results.
About 9,000 people took part in the PRO 2000 trial, which began in 2005.
Mitchell Warren, head of the AIDS Vaccine Advocacy Coalition, was in the Ugandan capital, Kampala, for Monday’s announcement of the trial results.
“A microbicide is a product that could be a gel or potentially a film or a ring, basically all different kinds of formulations, that could be used either to prevent HIV (transmission) through vaginal sex or potentially through anal intercourse as well,” he says.
So, far, however, no microbicide candidate has been proven to be both safe and effective. A successful microbicide could help empower women to protect themselves against HIV/AIDS.
The trial was sponsored by the British-funded Microbicide Development Program, along with partners in Africa. Researchers had been encouraged by an earlier, smaller study of PRO 2000.
“That trial found a trend toward potential protection with PRO 2000, although the results were modest and they weren’t statistically significant. So this larger trial was really meant to answer more definitively whether PRO 2000 was effective. And in fact the trial today reported that…it wasn’t effective at all in reducing risk from HIV. So very disappointing today,” he says.
The next chapter
Since the 1990s, researchers have tried many times to come up with a successful microbicide. Warren says the failure of PRO 2000 is the closing of one chapter in research but the beginning of another.
“That is looking microbicides that would be formulated to include anti-retrovirals. So, there’s a trial actually talking place in South Africa that is testing a gel that incorporates Tenofovir, a very common anti-retroviral drug. The active ingredient is now formulated in a gel, he says.
Warren says the results of that trial could be released in mid-2010, possibly at the next International AIDS conference, in Vienna.
What they did learn
The trial did gather a lot of information on the social aspects of a microbicide.
“So while the product didn’t work, we have more data from this trial that looks at women’s attitudes toward the gel, their acceptance of the product, and they were very enthusiastic about it. So there’s a tremendous amount of data that has been collected through this trial that will be incorporated into the next trial,” he says.