What Does CAPRISA Mean Future of Microbicides
07/20/2010
Zeda Rosenberg, CEO of the International Partnership for Microbicides, on findings
Today, at the 18th International AIDS Conference in Vienna, the Center for AIDS Programme of Research in South Africa (CAPRISA) announced successful results of a clinical trial testing an antiretroviral (ARV)-based vaginal microbicide for its ability to prevent HIV infection in women. This announcement marks a turning point in efforts to develop safe and effective female-initiated HIV prevention methods. The trial, named CAPRISA 004, showed that women who used a gel containing tenofovir, an ARV commonly used to treat HIV, had a 39 percent lower rate of infection compared to women who used a placebo gel.
CAPRISA 004 was the first-ever efficacy study of a "next generation" microbicide, which harnesses the power of ARVs to protect women from HIV. ARVs are the same drugs successfully used to treat HIV infection and prevent transmission of the virus from mothers to children during pregnancy and childbirth. Women enrolled in the study used a gel containing tenofovir up to 12 hours before and after sexual intercourse. The results are statistically significant and establish "proof-of-concept" that ARVs applied topically can prevent HIV infection.
These results come at the end of what has been a long and challenging road to develop methods that women can use to protect themselves from HIV, and the CAPRISA research team, donors, and trial participants and their families should all be commended for their efforts. Biologically and culturally, women are more susceptible to HIV. In sub-Saharan Africa, over 60 percent of adults living with HIV are women; and women and girls aged 15 to 24 are three times more likely to be HIV-infected than men in that same age range.
Though several methods of HIV prevention such as condoms, male circumcision and behavioral interventions exist today, all of these methods require the cooperation of a male partner. As the statistics of HIV infection among women clearly demonstrate, these methods are not effective for many women at risk. Women are often not able to negotiate condom use; many are subject to sexual violence and abuse; and women who would like to become pregnant cannot use a barrier method such as condoms to prevent infection.
Microbicides have always been among the most promising potential, female-initiated HIV prevention methods. They would give women a tool-in the form of a gel, a ring, or a thin film-that they can use themselves to prevent infection. But over the past few years, there have been eleven trials of early-generation microbicides, all of which produced disappointing results. CAPRISA 004 was the first study to test a product with an ARV as its active ingredient.
CAPRISA 004 is a significant victory. The gel is odorless and colorless, and women in the study reported a willingness to use the product, especially if it can help prevent HIV. The trial also showed a surprising added benefit, with tenofovir gel providing 51 percent protection again herpes simplex virus type-2 (HSV-2), which can make women two to three times more likely to acquire HIV.
Significant work remains before tenofovir gel-or any other microbicide-could be available to the public. Regulatory authorities will need to decide if additional confirmatory trials are necessary to support product licensure. Whatever their conclusions, these results have established a strong base of research on which to build future microbicide trials.
Clinical studies of several next generation microbicides and preclinical studies of combinations of ARVs are already under way by groups like the International Partnership for Microbicides (IPM) and other organizations. In addition, important acceptability studies ensure that we design microbicides that women want to use, and ideally provide sustained protection against HIV. Just last month, IPM announced a new study of a novel microbicide ring based on existing contraceptive technology that could deliver ARVs for a month at a time.
CAPRISA 004 also provides a model of how public-private partnerships can expedite the development of novel tools for HIV prevention. Gilead Sciences, a biopharmaceutical company, provided the tenofovir, which was then developed into the gel by CONRAD, a non-governmental organization collaborating with CAPRISA on the study. Both CONRAD and IPM have co-exclusive agreements with Gilead Sciences to develop tenofovir into a microbicide for developing countries. The agreements also provide that a successful product will be available to women in countries like South Africa at low or no cost.
Microbicides have the potential to transform the landscape of HIV prevention around the world. The road ahead is likely to remain long and complex, but with the CAPRISA 004 study, we are one step closer. Together, we must build on this research and continue to develop and expand access to methods that will enable women to take prevention into their own hands. With such efforts we could prevent thousands-or millions-of HIV infections among women and reverse the trend of an epidemic that has seemed unstoppable for far too long.
Dr. Zeda Rosenberg is CEO of the International Partnership for Microbicides.
The trial focused two groups like a case control study. What is the fate of the Placebo group; I believe some of them must have contracted HIV infection during this trial. Can this type of trial be done in the United States, UK, France or Germany?
— Dr. Kadri Ajileye on 2010-07-26
I agree with Dr.Rosenberg Statment “Together, we must build on this research and continue to develop and expand access to methods that will enable women to take prevention into their own hands. The New FDA approved cervical barrier FemCap that is designed with unique delivery system ( a reservoir facing the vaginal opening)that can store the microbicide for 48 hours and thus eliminate the frequent use of the applicator and thus enhance adherence and effectivness.
— Alfred Shihata, MD on 2010-08-01