Search for AIDS ‘cure’ suffers another setback
AFFORTS to create a drug that can protect people against Human Immuno-deficiency Virus (HIV)/Acquired Immune Deficiency Syndrome (AIDS) will suffer a significant setback with the announcement that the leading “infection blocking” gel has failed in a trial of more than 9,000 women.
With a scientific consensus growing that an AIDS vaccine is many years away – despite promising results from a recent trial in Thailand – microbicides had been considered a more realistic drug strategy to protect people against HIV infection.
Earlier this year a preliminary trial involving PRO 2000 suggested that the gel might reduce the chances of women contracting HIV by almost a third. The latest study, a four-year international collaboration led by British scientists and funded by the Government and the Medical Research Council (MRC) confirms that the early finding was simply the result of chance.
Microbicides are formulated as gels or creams designed to destroy bacteria and viruses or to reduce their ability to establish an infection. The gel is applied to the vagina or rectum before sex to kill HIV, to prevent the virus entering human cells and to inhibit HIV replication.
The trial took place between 2005 and 2009 and was carried out by the Microbicides Development Programme, a partnership of 16 African and European research institutions. The gel was given to participants along with free condoms, counselling for “safer sex negotiation” and sexual health advice.
Sheena McCormack, the chief investigator from the MRC, told The Times that the trial showed conclusively that PRO 2000 is of no added benefit and that it ended scientific speculation about its clinical importance. To date, no microbicide has been shown to be effective against HIV infection.
McCormack said: “It is a clear answer and in that respect it shows a clear path forward. We need to find a better, more radical approach to preventing infection.”
She said that the result was particularly disheartening given the positive indications from the earlier trial, which was funded by the U.S. National Institutes of Health and involved 3,000 women.
“Nevertheless it shows clearly the need to undertake trials, which are large enough to provide definitive evidence for whether or not a product works,” she said.
This year the United States Government and the Bill & Melinda Gates Foundation committed a grant of more than £90 million to support ten new clinical trials investigating more sophisticated “second generation” gels, such as those made with specific antiretroviral drugs, over the next five years.