New research has concluded that the vaginal microbicide gel PRO 2000 does not prevent HIV infection in women, a study released on Monday said.
"The researchers agree that while the results mean the end of the road for PRO 2000 - and the entire "second generation" of microbicide formulations, they are upbeat about next generation microbicides which are already in trials," a statement said.
The trial involved 9,385 women in east and southern Africa and though the gel was safe, it did not prevent infection.
"This was a large and important trial and while it's disappointing that PRO 2000 did not show an effect against HIV infection, nonetheless the product was safe and the trial was well conducted," said Professor Helen Rees, executive director of the Reproductive Health and HIV Research Unit, one of the participants in the trial.
Should prevent transmission
Microbicides are gels, foams or creams used to prevent the vaginal sexual transmission of the HI virus and other sexually transmitted infections when applied inside the vagina.
Other trials have also been disappointing and have been stopped, but researchers keep trying to find one that works properly, with trials using microbicides that contain anti-retrovirals already underway.
The latest trial known as "MDP 301" was conducted between September 2005 and September 2009.
Besides the centres in Africa, women were drawn from Mazabuka in Zambia, Masaka in Uganda, and Mwanza in Tanzania.
In Masaka, the trial population consisted of mostly HIV discordant couples - couples where one partner has the virus, and the other does not, and some concordant couples - where both have the virus.
In Tanzania, women were recruited from high risk groups whereas at all other centres, participants were women from the general communities.
The clinical trial tested the microbicide gels at two different doses for safety and their ability to prevent HIV infection against a placebo - a gel with no activity against HIV.
The active gel tested was PRO 2000 in 0.5% and 2% doses, developed by Indevus Pharmaceuticals in the US.
In earlier laboratory and animal testing, PRO 2000 had demonstrated a protective effect against HIV and other sexually transmitted infections by preventing HIV cell entry.
All participants underwent a comprehension test to assess their understanding of the trial prior to enrolment and throughout the study, and were given information about the risks.
All women in the study who became HIV positive were provided counselling and were referred for ongoing psychosocial care. Women were also invited to remain in contact with sites for long-term care and monitoring of their HIV infections, and referrals were made to local health service providers for ongoing care.
HIV prevention education
The researchers believe that in spite of the disappointing results, the trial provided an opportunity to deliver HIV
prevention education to thousands of women at risk of HIV.
They lauded the commitment of the women and said this spurs them on to continue with their work.
In sub-Saharan Africa, women represent nearly 60% of adults living with HIV, and in several southern African countries young women are at least three times more likely to be HIV-positive than young men.
The study was conducted by the HIV Prevention Research Unit of the SA Medical Research Council, the Reproductive Health and HIV Research Unit of the University of the Witwatersrand, and the Africa Centre for Health and Population Studies of the University of KwaZulu-Natal.
It was funded by the UK Medical Research Council and the UK Department for International Development. - (Sapa, December 2009)