Proof-of-Concept Established for Microbicides

After decades of research, there is great reason to believe that safe and effective microbicides are within reach. The first clinical trial of an antiretroviral (ARV)-based microbicide has validated the preventive potential of these products.

The latest research shows that next-generation microbicides that are based on the same types of ARV drugs already being used successfully to treat HIV/AIDS and prevent mother-to-child transmission can also offer women protection against HIV.

ARV-based microbicides have the potential to transform the global response to HIV infection and save millions of lives.

The CAPRISA Trial 

In July 2010, the Centre for AIDS Programme of Research in South Africa (CAPRISA)  announced groundbreaking results showing proof-of-concept that an ARV-based microbicide can safely prevent women from becoming infected with HIV through sex with an HIV-positive male partner.

The findings demonstrate that women who used a vaginal gel containing an ARV called tenofovir were 39 percent less likely to be infected with HIV than those using a placebo gel. Among women who used it consistently and correctly, it cut the chances of HIV infection by more than 50 percent.

Participants were asked to use the gel within 12 hours before sex and again not more than 12 hours after sex, not exceeding two doses in 24 hours.

Tenofovir gel also cut by around half a woman’s risk of contracting herpes simplex virus type 2 (or HSV-2), which is a lifelong and incurable infection that can increase the risk of HIV infection.

These results have contributed significant momentum to the field. New products are rarely if ever licensed based on one efficacy trial. Regulatory bodies will need to determine what additional studies are needed (either those already underway or being planned) before tenofovir gel can be introduced as a new HIV prevention strategy.

Building on the CAPRISA results

IPM and other nonprofit organizations are working to try to build on the CAPRISA trial results, either by developing products containing different ARVs or using different delivery methods to increase the level of protection found in the CAPRISA trial. 

IPM is developing microbicides in a variety of forms, including once-daily vaginal gels and a long-acting ring that would provide protection for up to a month at a time. IPM’s most advanced microbicide candidate is a monthly vaginal ring containing dapivirine. The dapivirine ring is scheduled for Phase III clinical safety and efficacy evaluation in 2011.

Learn more about these milestone findings:

SAfm Interviews IPM’s Dr. Zeda Rosenberg About CAPRISA Trial