Prototype Vaginal Gel Fails to Block HIV: Study

Hopes for an effective anti-HIV microbicide were dealt a setback when Phase III results of a major clinical trial found a vaginal gel candidate was safe but ineffective.

The PRO 2000 formula uses a large charged polymer to disrupt HIV interaction with targeted cells. PRO 2000 was tested at two levels of concentration - 2 percent and 0.5 percent - at 13 clinics in South Africa, Tanzania, Uganda, and Zambia. The study was closely monitored for ethical standards.

The study's subjects were more than 9,000 women age 18 and older who were sexually active and HIV-negative. They were given PRO 2000 at either concentration or a placebo cream. All participants were given safe-sex counseling and access to condoms. Their HIV status was tested at 12 weeks, 24 weeks, 40 weeks, and 52 weeks after study initiation.

According to the study, "Safety-related events were rare and at similar rates in all three groups [but] HIV-1 incidence was much the same between groups at study end."

However, the study did find use of the gel was high, with 89 percent of participants reporting use prior to intercourse - encouraging news, given that consistent use has posed a challenge to product developers.

An effective microbicide would revolutionize the global fight against HIV/AIDS by empowering women, particularly in African countries where coercive sex is common.

In July at the 18th International AIDS Conference in Vienna, researchers reported on a Phase IIb trial in South Africa in which the CAPRISA 004 cream reduced HIV infection risk by 39 percent overall and by 54 percent among the most consistent users. But this level of protection may not be enough to gain approval for CAPRISA, which contains the HIV drug tenofovir.

The study results, "PRO 2000 Vaginal Gel for Prevention of HIV-1 Infection (Microbicides Development Program 301): A Phase 3, Randomized, Double-Blind, Parallel-Group Trial," was published early online in The Lancet (doi:10.1016/S0140-6736(10)61086-0).

The Friends of AIDS Foundation is dedicated to enhancing the quality of life for HIV positive individuals and empowering people to make healthy choices to prevent the spread of the HIV virus. To learn more about The Friends of AIDS Foundation, please visit: http://www.friendsofaids.org.


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