Anti-HIV microbicide may do more harm than good

Cellulose sulfate gel‑investigated as a vaginal microbicide against HIV‑didn't reduce HIV infections and may have even increased the risk in a sample of women, according to research published in the July 31 New England Journal of Medicine.

Lut Van Damme, MD, of CONRAD in Arlington, VA, and colleagues analyzed data from 1,398 women who were randomized to receive cellulose sulfate gel or placebo. Participants were recruited from five sites in Africa and India and were instructed to insert the gel an hour before intercourse. The primary end point was new infection with HIV type 1 or 2.

An interim analysis, which found an estimated hazard ratio of 2.23 in the treatment group, led to early termination of the study. In the final effectiveness analysis, 25 new infections were found in the cellulose sulfate group and 16 in the placebo group, for an estimated hazard ratio of 1.61 for the cellulose sulfate group, though this was not statistically significant. The treatment was not associated with a significant reduction of gonorrheal or chlamydial infection, which was the secondary end point.

“Despite the disappointing outcome of this study and recently halted vaccine trials, as well as the lack of a protective effect in other recently completed HIV prevention trials, the search for HIV prevention methods that can be initiated by women must continue to help stem the tide of infection in highly vulnerable populations,” the authors conclude.

Van Damme L, Govinden R, Mirembe FM, et al. Lack of effectiveness of cellulose sulfate gel for the prevention of vaginal HIV transmission. N Engl J Med. 2008;359:463-472.