title: Tenofovir-based pre-exposure prophylaxis for HIV prevention:  evolving evidence.
abstract: OBJECTIVE
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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).
authors.affiliation: Departments of Global Health, Medicine, and Epidemiology, University of Washington, Seattle, Washington 98104, USA. ccelum@uw.edu
authors.forename: Connie
authors.initials: C
authors.lastname: Celum
authors.forename: Jared M
authors.initials: JM
authors.lastname: Baeten
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives* / Q000627:therapeutic use; D000284:Administration, Oral; D000287:Administration, Topical; D019380:Anti-HIV Agents / Q000627:therapeutic use*; D005260:Female; D015658:HIV Infections / Q000517:prevention & control* / Q000635:transmission; D015497:HIV-1; D006801:Humans; D008297:Male; D055118:Medication Adherence; D063065:Organophosphonates / Q000627:therapeutic use*; D018894:Reverse Transcriptase Inhibitors / Q000627:therapeutic use*; D000068698:Tenofovir
chemical_list: D019380:Anti-HIV Agents; D063065:Organophosphonates; D018894:Reverse Transcriptase Inhibitors; D000068698:Tenofovir; D000225:Adenine