Treating heterosexual men and women at risk of HIV infection with a daily pill containing 1 or 2 antiretroviral drugs can reduce this risk by more than 60%, according to results from a pair of studies released today by the University of Washington in Seattle and the US Centers for Disease Control and Prevention (CDC). A previous clinical trial demonstrated that such preexposure prophylaxis (PrEP) is effective for men who have sex with men.
The results of the Partners PrEP Study were released early after the study’s data and safety monitoring board concluded that the data to date are strong enough to suggest a protective effect of the treatment.
The Partners PrEP Study compared HIV infection rates among nearly 5000 uninfected partners of HIV-infected individuals in Kenya or Uganda who were randomized into 3 groups: 1 group received a daily pill containing tenofovir, 1 group received a daily pill containing tenofovir plus emtricitabine, and 1 group received a placebo. As of May 31, the study had identified 78 HIV infections among participants, 47 among those assigned a placebo, 18 among those being treated with tenofovir (62% fewer infections compared with the placebo group), and 13 among those receiving tenofovir plus emtricitabine (73% fewer infections compared with the placebo group).
Based on these results, the study’s data and safety monitoring board recommended discontinuing the study’s placebo group and offering PrEP to participants not infected with HIV. The continuing study will assess the 2 treatment groups to determine whether 1 treatment regimen offers superior protection.
The release of the Partners PrEP Study results prompted the CDC to release the findings of another trial, the TDF2 study involving more than 1200 HIV-uninfected sexually active males and females in Botswana, half of whom received tenofovir and emtricitabine and half of whom received a placebo. There were 9 new infections among those taking the drugs compared with 24 new infections among those receiving placebo, which translated to a 62.6% reduction in new infections. Results of both studies will be presented at a scientific meeting in Rome next week.
The CDC is advising heterosexual individuals who wish to receive PrEP to wait to initiate treatment until guidelines for such care can be created. However, if individuals feel that such preventive measures are urgently needed, they and their clinician should follow the guidelines the agency has already established for men who have sex with men.
“PrEP is not for everyone and will not solve the epidemic,” said Jonathan Mermin, MD, director of the CDC’s Division of HIV/AIDS Prevention. “But it’s an additional tool that can be used.”