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Anti-HIV Microbicide Trials Halted

Preliminary results indicate that the risk for HIV infection is higher among women using cellulose sulfate than among those using placebo.

Topical microbicides that prevent sexual transmission of HIV could have a major impact on the pandemic, but progress in this area has been slow and rather disappointing. Now, the field has been dealt yet another blow. On January 31, 2007, the research organization CONRAD halted a phase III clinical trial of cellulose sulfate in Africa and India because preliminary results indicated an increased risk for HIV infection among women who used the compound. As a precautionary measure, based on these results, Family Health International also halted its phase III trial of cellulose sulfate in Nigeria.

Cellulose sulfate (Ushercell) is a cotton-based compound that was designed to prevent HIV entry into mucosal cells. Eleven previous clinical trials, which included more than 500 women in Africa, India, and the U.S., gave no indication that cellulose sulfate might be unsafe. Encouraged by the promising results of these trials, the CONRAD group initiated a randomized, double-blinded trial among approximately 1300 women in South Africa, Benin, Uganda, and India in July 2005. Half of the participating women received cellulose sulfate, and half received placebo gel. All the women received free condoms and intensive prevention counseling on a monthly basis.

During a scheduled interim analysis, the Data and Safety Monitoring Board found a higher incidence of HIV infection in the cellulose-sulfate group than in the placebo group. The trial was consequently halted, as was a similar trial in Nigeria involving 1700 women. Investigation of the preliminary findings is ongoing, with final numbers expected in the next few months. Three other phase III trials of microbicides are still underway.

— ACC Editors

Published in AIDS Clinical Care February 12, 2007

Citation(s):

Phase III trials of cellulose sulfate microbicide for HIV prevention closed [press release]. Arlington, Va : CONRAD; January 31 , 2007. (http://www.conrad.org/press/phaseIIItrials.htm)