Anti-HIV gel PRO 2000 fails to prevent infection in African women

PRO 2000, a vaginal gel to prevent HIV infection, has been failed in clinical trials.

PRO 2000, developed by Endo Pharma P has been studied in a clinical trial involving of more than 9,000 women from six locations in  Africa including Uganda, South Africa, Tanzania and Zambia.

PRO 2000 gel was supposed to block HIV infection when applied internally.

A preliminary trial involving PRO 2000 suggested that the gel might reduce the chances of women contracting HIV by almost a third, according to a report early this year. The earlier trial involved 3,000 women and was funded by the US National Institutes of Health.

However, the results were found purely incidental by the the latest study, a four-year international collaboration led by British scientists and funded by the Government and the Medical Research Council (MRC).

PRO 2000 trial showed conclusively that the gel is of no no added benefit. No microbicide has been shown to be effective against HIV infection, till date.

Trials found that rates of HIV infection were identical with PRO 2000 gel (0.5% concentration) and placebo in the four-year study, which ended in September.

The clinical study was conducted between 2005 and 2009. The study was carried out by the Microbicides Development Programme, a partnership of 16 African and European research institutions.

The study participants were supplied with the gel along with free condoms, counselling for safer sex negotiation and sexual health advice.

Microbicides had been considered a more realistic drug strategy to protect people against HIV infection. especially at a time when a vaccine against AIDS looks far off.

PRO 2000 is a microbicides formulated as gels or creams designed to destroy bacteria and viruses or to reduce their ability to establish an infection.

PRO 2000 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.

Study sponsors said adherence was high, as reported by participants and confirmed by returns of used applicators, and only slightly more than 10% of the maximum possible woman-years of data were lost during the study.They also indicated that neither compliance nor dropouts were problems.

PRO 2000 is the third microbicide to fail in a large Phase III trial. The spermicide nonoxynol-9 appeared to increase infection rates, and last year a product called Carraguard failed to show efficacy, although its safety profile was acceptable.

25 million people have died from Aids, and 16,000 people a day contract HIV, mostly from unprotected sex and mainly in sub-Saharan Africa and India, according to estimates. In sub-Saharan Africa, 60 per cent of those with HIV/Aids are women. In 2008, $868m (£540m) was spent on vaccines, $244m on microbicides, and $81m on other measures