The anti-HIV microbicides research has finally given a positive outcome - the microbicide gel PRO2000 under research showed 30% reduction of HIV transmission in the human clinical trials.
Women who were offered PRO2000 microbicide gel plus condoms had 30 per cent fewer HIV infections than those offered condoms only or condoms plus a placebo gel, according to the clinical trial results presented by the trial's Protocol Chair, Dr Salim S. Abdool Karim, PhD, University of KwaZulu-Natal in Durban, South Africa. Dr Karim presented the results at the 2009 Conference on Retroviruses and Opportunistic Infections (CROI). This multi-site clinical trial is known as HPTN 035, and tests two candidate microbicides (PRO2000 and Buffer Gel). It was conducted by the US National Institute of Health (NIH) funded the Microbicides Trial Network (MTN) in South Africa, Malawi, Zambia, Zimbabwe and the US. The PRO2000 microbicide gel did show anti-HIV activity by reducing HIV risk among women by 30 per cent; however, the other candidate microbicide tested in the same clinical trial - Buffer Gel microbicide - did not reduce HIV risk among women.
This news is particularly encouraging to health advocates because microbicide research had a series of disappointing news reports in the past decade with different microbicide-candidate-products under research showing no positive anti-HIV effect in human trials.
According to the World Health Organization (WHO), microbicides are compounds that can be topically applied inside the vagina or rectum to protect against sexually transmitted infections (STIs) including HIV. They can be formulated as gels, creams, films, or suppositories. Microbicides may or may not have spermicidal activity (contraceptive effect). At present, an effective microbicide is not available, and different candidate-microbicides are in various stages of research.
The Global Campaign for Microbicides (GCM), an advocacy organization that has been campaigning to expand women's HIV prevention options for over a decade, said in a press statement that these trials not only found that women who were offered PRO2000 gel plus condoms had 30 per cent fewer HIV infections but also found that the reported adherence to the gel was high at 81 per cent. In another analysis, that accounted for the time that women did not use the product because they were pregnant, the study found PRO2000 to be 36% protective against HIV compared to the control arms.
"The results on PRO2000 are a ray of hope for women" observed Lori Heise, Director of the Global Campaign for Microbicides (GCM). "This is the first time that we have had human data actually showing that a vaginal gel can work to reduce infection. It's not a home run, but this "proof of concept" should "invigorate the field."
Another effectiveness trial of PRO2000, conducted by the UK-funded Microbicide Development Programme (MDP), is currently in its final stages in South Africa, Tanzania, Uganda and Zambia. This trial - known as MDP 301 - has enrolled over 9,000 women, three times the number enrolled in HPTN 035.
“This second trial should help us refine our estimate of how effective PRO2000 actually is,” noted Dr. Samu Dube, GCM’s Africa Program Leader in the GCM press statement. “With three times the number of women, the MDP trial will yield an even more precise estimate of effectiveness. We will need such data before deciding whether it makes sense to move this product forward toward licensing and distribution.”
The development of microbicides is seen as a key to empowering women to protect themselves from HIV. Women are biologically more vulnerable to the transmission of STIs and many cultural and economic factors compound this vulnerability.
Millions of women live in societies that permit them no role in sexual decision-making, that condone male infidelity and assign the burden of shame and stigma associated with infectious diseases to women. Existing preventative strategies have largely failed to address this vulnerability, focusing on abstinence, mutual monogamy and male condom use, none of which are easily controlled by women.
Vaginal microbicides are also likely to fail until men understand and respect the need for women to protect themselves against HIV and other STIs. Not only do women need preventative options that they can choose to use freely, but the gender inequalities that make it harder for women to insist on safer sex must be addressed alongside.