Two phase III HIV microbicide trials stopped due to increased transmission

On 1 February 2007, the International AIDS Society (IAS) issued a press release to the halting of two large phase III studies of the HIV microbicide candidate Ushercell. Ushercell is a cellulose sulfate based topical gel that was being developed for HIV prevention in women by Polydex Pharmaceuticals.

This was because preliminary results at some sites indicating potential increased risk for HIV among women who use the compound. The findings of increased risk were identified at some sites in a trial sponsored by CONRAD, a research agency of USAID in the United States. The CONRAD trial was being conducted in South Africa, Benin, Uganda and India.

Family Health International, sponsor of the second halted trial in Nigeria, had not found similar results but halted the trial as a precautionary measure, given the preliminary results in the CONRAD trial. At this point, it is not clear why the use of cellulose sulfate was associated with increased risk for HIV infection among women in the CONRAD-sponsored trial. Earlier trials of the same compound involving 500 participants did not indicate safety concerns.

While extremely disappointing, this setback is also an opportunity to learn why some women who used Ushercell were found to be at increased risk of HIV infection, said Dr. Pedro Cahn, President of the IAS and Director of Fundaci