1 February 2007 A trial of a new treatment to prevent HIV/AIDS transmission in women has been stopped prematurely because of a higher number of infections among those taking the microbicide cellulose sulfate compared with the placebo group, according to United Nations agencies involved.
“This is a disappointing and unexpected setback in the search for a safe and effective microbicide that can be used by women to protect themselves against HIV infection,” the UN World Health Organization (WHO) and Joint UN Programme on HIV/AIDS (UNAIDS) said in a statement.
“At present there is no explanation for this higher rate of transmission of HIV. The need to continue research to find a user-controlled means of preventing HIV infection in women is urgent. Despite the effectiveness and availability of condoms, the HIV epidemic continues to spread and the search for a safe and effective microbicide is a vital part of the effort to stem the spread of the HIV epidemic,” they added.
Microbicides seek to reduce the transmission of HIV during sexual intercourse and could take the form of a gel, cream, film, tablet or sponge, or be contained in a vaginal ring that releases the active ingredient gradually.
The study was sponsored by CONRAD, a cooperative agreement between Eastern Virginia Medical School in the United States and the US Agency for International Development (USAID) with funding from both Government and private organizations, and conducted in Benin, India, South Africa and Uganda.
A second study on the same product sponsored by Family Health International, a non-profit organization, conducted in Nigeria has also been stopped because of the safety concerns in the first trial.
There are currently three other Phase III microbicide studies under way. The Carraguard study sponsored by the non-governmental organization (NGO) Population Council and conducted in three sites in South Africa is nearing completion and results are expected by the end of 2007.
Another product, PRO 2000, is being tested in one study in five sites in South Africa, Tanzania and Uganda with results expected in 2009, as well as in a second study in seven sites in Malawi, South Africa, Zambia and Zimbabwe, with results expected in 2008. In this second study a further compound, BufferGel, a vaginal defence enhancer, is being tested.
All the other compounds are products that block HIV infection, known as HIV entry inhibitors, and have a similar presumed mechanism of action. Data from these clinical trials will be indispensable to the researchers and developers of emerging and future microbicide candidates, the agencies said.