Recent Development in Microbicide Studies: Statement on Early Generation Microbicide Gel PRO 2000
Dr. Zeda Rosenberg, CEO of the International Partnership for Microbicides, issued the following statement on the results of the Phase III effectiveness study of PRO 2000:
(December 14, 2009) – Today the UK-based Microbicides Development Programme (MDP), a partnership of African and European researchers, announced the results of its Phase III clinical trial of PRO 2000, a vaginal gel being tested to prevent HIV transmission to women during sex. The results revealed that PRO 2000 (0.5 % concentration), an early generation microbicide candidate, was safe as tested but did not provide protection against HIV as compared to a placebo.
One arm of the MDP study testing PRO 2000 in a 2% strength gel was discontinued in 2008 when the study’s Independent Data Monitoring Committee concluded that it was not likely to show benefit in preventing HIV. The four-year PRO 2000 study (MDP 301) was the largest microbicide trial to date, and involved some 9,404 participants across six research centres in South Africa, Tanzania, Uganda and Zambia.
While results of a smaller study of 0.5% PRO 2000 released earlier this year signaled potential support for the product, today’s announcement provides conclusive evidence that PRO 2000 is not an effective tool for HIV prevention, and closes the chapter on the early generation of microbicides that were based on large polyanions thought to non-specifically block HIV from attaching to its target cells.
IPM acknowledges the hard work of the UK’s Microbicides Development Programme, its staff, the communities in which the trials took place, and, especially, the study participants and their families. While IPM was not involved in the PRO 2000 study, all of us working to develop new HIV-prevention tools will incorporate valuable lessons from the study into our own trial designs to conduct the most efficient and safe trials. The fact that this study was able to engage nearly 10,000 women over four years testifies to the shared commitment to give women the power to protect themselves — and to stop the spread of HIV.
The need remains urgent. According to a recent report on the health challenges facing women and girls by the World Health Organization, HIV/AIDS is now the number one killer of women of reproductive age in the world, particularly in developing countries where the epidemic has hit hardest.
Fortunately, microbicide development has already entered a new and promising chapter. In the last few years, researchers have begun work on a potentially highly potent generation of long-acting microbicide products containing antiretrovirals (ARVs) and formulated as long-acting vaginal rings, gels and films.
These next generation products are based on the same ARVs already being used to treat HIV/AIDS and to prevent mother-to-child transmission. ARVs work by specifically targeting the virus and either preventing it from entering a healthy cell or from replicating once it is inside the cell. Antiretroviral treatment (ART) has saved millions of lives across the globe. Adapting these highly potent treatments to create female-initiated prevention technologies has the potential to transform the global response to HIV infection.
ARV-based microbicides are already being studied in clinical trials in Africa, Europe and North America sponsored by IPM and other organizations, including CAPRISA in South Africa and the Microbicide Trials Network, a global research network funded by the US National Institutes of Health. IPM and others are working to find ways to deliver ARVs in formulations that are acceptable to women and their partners, easy for women to use, and can potentially provide long-lasting protection against HIV, such as once-daily gels, films, and tablets as well as longer-lasting monthly vaginal rings.
Challenges lie ahead, but ARV-based microbicides remain one of the best hopes for female-initiated HIV-prevention, and we are confident that safe and effective products are within reach. With the next generation of product development well underway, the microbicide field can focus on products that have already proven effective in treating HIV and show tremendous promise for prevention. We do this alongside donors, advocates, national governments, and private sector partners who continue to provide steadfast and commendable support for these efforts.
Our shared responsibility stems from the knowledge that HIV continues to devastate communities and families around the world. By one day putting the power of protection into women’s hands, we give them the power to help stop the spread of HIV/AIDS.
About IPM: IPM is a nonprofit organization established in 2002 to prevent HIV transmission by accelerating the development and availability of safe and effective vaginal microbicides in developing countries. IPM has offices in the United States, Belgium and South Africa.