Tenofovir-based pre-exposure prophylaxis for HIV prevention
Topical tenofovir gel and oral tenofovir and emtricitabine-tenofovir [FTC/tenofovir disoproxyl fumarate (TDF)] have been demonstrated to have efficacy in preventing HIV-1 in some populations. Preexposure prophylaxis (PrEP) trials and future directions are summarized.Pericoital use of 1% tenofovir gel in the CAPRISA 004 study reduced HIV-1 acquisition by 39% and herpes simplex virus-2 acquisition by 51%. Daily oral FTC/TDF demonstrated 44% reduction in HIV-1 acquisition among MSM in the iPrEx study (Pre-Exposure Prophylaxis Initiative). Both studies showed higher efficacy among those with higher adherence. Efficacy of daily oral TDF and FTC/TDF was 66 and 73%, respectively, among HIV-1-uninfected partners in an HIV-1 serodiscordant partnership in the Partners PrEP Study. Efficacy of daily oral FTC/TDF was 66% in young heterosexuals in Botswana in the TDF2 trial. The FEM-PrEP and VOICE (Vaginal and Oral Interventions to Control the Epidemic) studies in African women found no efficacy with oral FTC/TDF and TDF, respectively. Safety and tolerability were excellent and limited resistance was observed in seroconverters.Topical tenofovir gel showed efficacy in African women and daily oral TDF and FTC/TDF were efficacious in MSM, and African HIV-1 serodiscordant couples and young heterosexuals. The reasons for lack of efficacy of oral FTC/TDF and TDF in two studies in African women are being investigated. Longer-acting formulations, invtravaginal rings, and new candidate antiretrovirals are being evaluated for pre-exposure prophylaxis (PrEP).