Advocating for rectal microbicides

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Advocating for rectal microbicides

by Bob Roehr

The quest to develop a microbicide that protects against HIV infection is proving daunting. Such a compound would be part of a lube or other product used during sex, or perhaps before it, such as a douche.

But a couple of candidates have fallen by the wayside and that was in trials of vaginal sex, not anal sex where transmission of the virus is far more efficient and the challenges of protection presumably far greater.

International Rectal Microbicides Advocates is one of the few groups pushing for development of microbicides that can be used in the rectum. It issued a report on February 24 in New Delhi, India, at the start of the biennial confab of microbicides researchers. The title of that report said it all: "Less Silence, More Science."

A paltry $7 million a year is being spent on research into rectal microbicides, only about 3 percent of the total microbicide portfolio. Almost all of the rectal funding is coming from the National Institutes of Health. IRMA is calling for a five-fold increase to $35 million by 2010, and a diversification of funding from multiple sources.

Common misconceptions are that only gay men are interested in a rectal microbicide and that heterosexuals don't engage in anal sex. But research shows otherwise. Studies in the United States and the United Kingdom have found that anywhere from 10 percent to 35 percent of heterosexual women have engaged in anal sex.

"In absolute numbers, seven times more heterosexual women than gay men in the U.S. practice receptive anal intercourse," the IRMA report noted.

Given the biology of the vagina and rectum, transmission of HIV through the latter tissue is many-fold more efficient. And heterosexuals almost never use condoms when they practice anal sex. This could be an important but hidden source of HIV transmission among heterosexual couples.

Jim Pickett, chairman of IRMA and director of advocacy at the AIDS Foundation of Chicago, said, "This could be a sizable amount of the epidemic. Anal sex is a highly stigmatized behavior – people who are doing it don't want to talk about it, they lie about it, policymakers don't want to say it, funders don't want to talk about it – so we just don't know" the full extent of the role anal sex is playing in heterosexual transmission.

The 48-page IRMA report is a primer on the history of development of rectal microbicides and where the field is today. It also lays out research priorities for the coming years.

Surveys

Last year IRMA conducted an Internet survey on use of lubricants during anal sex.

"We were going to be happy if a couple of hundred people did this; our wildest dream was 500. We thought, no one was going to take some dusty survey, it is going to be like pulling teeth," said Pickett. "But it took on a life of its own; people were posting it, writing about it. It took on a bit of a viral quality, we were seeing periods where 100-150 people a day were taking it, and we kept extending it."

They finally called it quits after 8,945 people had completed the survey. Some 88 percent were men across a broad range of ages, and most (64 percent) lived in North America. The main survey was in English but volunteers translated it into a handful of languages, and the surprising star turned out to be Turkish. Almost 20 percent of the surveys were taken in Turkish.

One of the surprising findings from the survey was how many people use saliva in doing the act, regardless of whether they were using or not using condoms or lube. And that adds the research question of just what effect spit might have on any microbicide.

An earlier Internet survey found that more than a quarter of HIV-negative gay men, and almost half of HIV-positive gay men, douche before and/or after engaging in anal sex. A major reason was simple hygiene, and many thought that a post-sexual douche might protect them from infection with HIV.

Those findings came as a revelation to researchers who hadn't thought about the role that douching might play in making a person more vulnerable to or protected from infection. Now researchers are scurrying to find out just what effect douching might have on the lower reaches of the gut. They also are considering whether douching might be an effective way to deliver a microbicide.

Optimism

Pickett said that the recent failures of vaginal microbicides trials have had no effect on the rectal area because, "We're in such a different place, we just started safety trials, so the thought of efficacy trials is a long ways away."

He acknowledged that there has been "some tension" within the field of microbicide development. Some advocates have focused solely on a vaginal product and tried to ignore any possible rectal use, and even safety issues associated with that likely use. They wanted to minimize controversy that might delay development of a product that could "empower women."

But that has started to change, said Pickett. "I think there is much more willingness to talk about it, there is a much greater acknowledgment of the need."

He believes the Food and Drug Administration has come around to the need for rectal safety data on any microbicides that might be submitted for its approval.

"Less Silence, More Science" is available online at http://www.aidschicago.org/rectalmicrobicides.

03/06/2008

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