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Tuesday December 15th, 2009

HIV ‘prevention’ gel PRO 2000 proven ineffective

HIV ‘prevention’ gel PRO 2000 proven ineffective

The largest international clinical trial to date into a preventative HIV gel has found no evidence that the vaginal microbicide, PRO 2000, reduces the risk of HIV infection in women, scientists announced today. This placebo-controlled trial involved 9,385 women at six research centres in four African countries and found that the risk of HIV infection in women who were supplied with PRO 2000 gel was not significantly different than in women supplied with placebo gel. Although ineffective in providing protection, PRO 2000 gel itself was safe to use.

A vaginal microbicide is a product intended for use before sexual intercourse to help reduce HIV infection, as it is clear that condom promotion alone has not controlled the epidemic. The gel was given to participants together with a package of prevention against HIV infection that included free condoms, counselling for safer sex negotiation and sexual health throughout the trial.

The trial, known as MDP 301, took place between September 2005 and September 2009 and was carried out by the Microbicides Development Programme (MDP), a not-for-profit partnership of 16 African and European research institutions. It was funded by the UK Department for International Development (DFID) and the UK Medical Research Council (MRC).

To date, no microbicide has been shown to be effective against HIV infection. This trial shows conclusively that PRO 2000 gel is of no added benefit, ending scientific speculation about its clinical importance.

MDP 301 Chief Investigator, Dr Sheena McCormack of the Medical Research Council said: “This result is disheartening; particularly in light of the results of a smaller trial sponsored by the US National Institutes of Health (NIH) which suggested that PRO 2000 could reduce the risk of HIV infection by 30 per cent. Nevertheless we know this is an important result and it shows clearly the need to undertake trials which are large enough to provide definitive evidence for whether or not a product works.”

Professor Jonathan Weber, co-Chair of the MDP Programme Management Board from the Division of Medicine at Imperial College London, said: “This is a disappointing result for the product, as the trial shows that it is not effective. However, the trial itself was very well designed and undertaken, so we know that the results are definitive.

“It is unfortunate that this microbicide is ineffective at preventing HIV infection, but it’s still vital for us as scientists to continue to look for new ways of preventing HIV. There are many research groups exploring different avenues to tackle HIV; it is a slow process, but we are making progress. Now that we know this microbicide is not the answer, we can concentrate on other treatments that might be.”

Dr Maureen Chisembele, Principal Investigator of the Zambian site, said: “In Sub-Saharan Africa, nearly 60 per cent of all people living with HIV/AIDS are women. Many are highly vulnerable to HIV despite the fact that they are faithful to their partners. The women will be disappointed by this result as they really liked the gel and hoped it would work.”

A South African trial participant commented: “Even though the gel proved not to be effective, we played a role in the fight against HIV. We learnt a lot about caring for ourselves, such as using condoms. We also learnt to encourage others to test for HIV and we gained confidence in helping those who were already infected.”

CRESIB (Hospital Clínic de Barcelona – Universitat de Barcelona) investigator, Dr. Robert Pool, was the coordinator of the social science component of the study: “This trial had the largest and most detailed social science component that has ever been used in a clinical trial and involved the use of mixed-methods to collect more accurate data on sexual behaviour and adherence, which is crucial in such clinical trials. The social science component also focused verifying participants’ understanding of the trial and assessing acceptability. Although our centre at Manhiça is part of the Microbicide Development Programme, they were not part of this trial. Currently, together with Dra Khatia Munguambe and Dr Sibone Micumbi and their team in Mahiça, we are conducting feasibility studies for the next trial”.

The trial participants are being informed of the trial outcome. The full results will be submitted for presentation at international conferences in 2010, as well as for publication in a peer-reviewed scientific journal.

The gel used in the study was provided by Endo Pharmaceuticals, a specialty pharmaceutical company with headquarters in Chadds Ford, Pennsylvania, USA.

More information about the MDP 301 microbicides trial can be found at http://www.mdp.mrc.ac.uk/

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