HIV :: Phase III trials of cellulose sulfate microbicide for HIV prevention closed

CONRAD, a reproductive health research organization, announced today that it has halted a Phase III clinical trial of cellulose sulfate — a topical microbicide gel being tested for HIV prevention in women — because preliminary results indicated that cellulose sulfate could lead to an increased risk of HIV infection in women who use the compound.

The trial was being conducted in South Africa, Benin, Uganda, and India.

Simultaneously, Family Health International (FHI) has halted a second Phase III cellulose sulfate trial in Nigeria. Although the FHI trial did not detect an increased HIV risk associated with cellulose sulfate, the decision was made as a precautionary measure, given the preliminary results in the CONRAD trial. Cellulose sulfate (CS) was one of four microbicides currently in effectiveness trials for prevention of HIV and other sexually transmitted infections.

At this point, it is not clear why use of cellulose sulfate was associated with an increased risk of HIV infection in the CONRAD trial. The Independent Data Monitoring Committee (IDMC), an independent advisory group of experts overseeing the trial, will conduct a detailed review of the data to better understand the findings, and help determine any implications for other microbicide studies.

Dr. Lut Van Damme, principal investigator of the CONRAD trial, stated: “It was our hope that this product would have helped women in protecting themselves from HIV. While the findings are unexpected and disappointing, we will learn scientifically important information from this trial that will inform future HIV prevention research.”

The microbicide, also known as Ushercell, is a cotton-based compound developed by Polydex Pharmaceuticals, based in Toronto, Canada. Prior to beginning the Phase III efficacy trials, there were 11 earlier safety and contraceptive trials on cellulose sulfate involving more than 500 participants in Africa, India, and the U.S. — none of which identified safety concerns.

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