A topically applied microbicide gel containing a potent anti-HIV drug has been found to significantly reduce infection when applied to rectal tissue that was subsequently exposed to HIV in the laboratory, according to a new study by the UCLA AIDS Institute.
The gel was also found to be safe and acceptable to users.
The first-ever phase 1 clinical trial of the rectal HIV-prevention drug known as UC781, a non-nucleoside reverse transcriptase inhibitor, is described in the current edition of the online journal PLoS ONE.
The trial represents the first use of this novel approach to obtain early insights into the drug’s potential to prevent real-life infections during sexual exposure. In addition, it represents an important contribution to efforts aimed at strategically preventing HIV transmission during receptive anal intercourse.
While anal-receptive intercourse is known to be the main route for new HIV infections in men who have sex with men, researchers said that far more women than men worldwide practice anal intercourse.
The risk of HIV infection, per sex act, is anywhere from 20 to 2,000 times greater with receptive anal sex than receptive vaginal sex — particularly if there are other infections present, such as herpes, gonorrhoea or chlamydia, according to the study’s lead author, Dr. Peter Anton, a professor of medicine at the David Geffen School of Medicine at UCLA.
“While the main goal of this trial was also to evaluate safety, these new tests enabled us to evaluate, indirectly, whether this drug and route of delivery might potentially reduce new HIV infections,” said Anton, who is also a member of the UCLA AIDS Institute.
“Of course, it is very gratifying that the results were so impressive. This approach reflects the kind of intensive analyses these dedicated participants in these early trials are willing to tolerate to help us evaluate a drug’s potential earlier in the pipeline of drug development.”
Until now, microbicide clinical trials have focused on vaginal transmission. These trials, fortunately, have had successful results in the past year, after nearly a decade of disappointment. But the development of a microbicide prevention gel for rectal application has only been under way for the past five to six years.
Based on a media release written by Enrique Rivero