There was significant interest in and discussion of pre-exposure prophylaxis (PrEP) as a potential tool for HIV prevention during the 17th International AIDS Conference in Mexico City.
In a symposium on the future of microbicides, Timothy Mastro presented an overview of PrEP knowledge and studies. There has been one completed trial to date (Phase II with 936 women in West Africa), which showed no evidence of clinical or laboratory adverse effects, and no evidence of increased risk behavior, but was not powered for efficacy. There are presently five ongoing PrEP trials and two more trials in the planning stages. These studies are occurring in a variety of populations including MSM, IDU, women, and discordant couples.
Funded by the Gates Foundation, the iPrEX study is the only efficacy trial of PrEP in MSM, and will enroll 3000 subjects. Three studies are using tenofovir (TDF) versus placebo, two are evaluating tenofovir/emtricitabine (TDF/FTC) versus placebo, one study is comparing TDF versus TDF/FTC versus placebo, and one is comparing tenofovir gel to oral TDF and to TDF/FTC. These seven studies include a total of 19800 subjects, and should go a long way in answering questions about feasibility, safety, efficacy, adherence, risk behavior, and changes in the natural history of HIV and resistance profiles in those who seroconvert on PrEP.
Knowledge of PrEP in the men who have sex with men community appears to be relatively low (Liu, et al: WEPE0259; Mimiaga, et al: CDRom publication 0377), but once educated about the potential of PrEP there was a high level (74%) of reported intent to use PrEP in the future. (Mimiaga, et al). There was also a reported high level of interest in use of PrEP in high-risk women (Dunkle, et al: WEPE0258). Future directions include evaluating intermittent versus daily PrEP, as well as new anitretrovirals (ARVs), ARV combinations, and formulations for PrEP.
08/07/08
Pre-Exposure Prophylaxis is Subject of Symposium at International AIDS Conference
Source: Reporting from Mexico City for PRN News: Anita Radix, MD, MPH and Rona Vail, MD