title: Differences in Cumulative Exposure and Adherence to Tenofovir in the VOICE, iPrEx OLE, and PrEP Demo Studies as Determined via Hair Concentrations.
abstract: Pre-exposure prophylaxis (PrEP) with oral tenofovir disoproxil fumarate (TDF)/emtricitabine (FTC) prevented HIV acquisition among men and women in several trials and is broadly recommended. In the VOICE and FEM-PrEP trials, however, TDF/FTC-based PrEP did not prevent HIV acquisition among women in eastern and southern Africa. Tenofovir was detected in plasma, reflecting exposure and adherence in recent days, in fewer than one-third of participants. Drug concentrations in hair, which represent cumulative exposure and adherence over weeks to months, have never previously been examined among women on PrEP. We compared tenofovir hair concentrations among women assigned to oral TDF/FTC in the VOICE trial to those among men and transgender women enrolled in 2 open-label PrEP studies, the iPrEx open-label extension (OLE) study and the U.S. PrEP Demonstration Project (PrEP Demo). Tenofovir hair concentrations were detectable in 55% of person-visits in VOICE, 75% of person-visits in iPrEx OLE (p = .006), and 98% of person-visits in PrEP Demo (p < .001). Median tenofovir hair concentrations corresponded to an estimated 0.2, 2.9, and 6.0 TDF/FTC doses taken per week in the three studies, respectively. In VOICE, combining tenofovir concentration data from plasma and hair suggested inconsistent, low-level product use. Incorporation of both short- and long-term adherence measures may allow for an improved understanding of patterns of drug-taking among women during global PrEP roll-out.
authors.affiliation: 1 Department of Medicine, University of California , San Francisco, San Francisco, California.
authors.forename: Catherine A
authors.initials: CA
authors.lastname: Koss
authors.affiliation: 2 Department of Epidemiology and Biostatistics, University of California , San Francisco, San Francisco, California.
authors.forename: Peter
authors.initials: P
authors.lastname: Bacchetti
authors.affiliation: 3 Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Pittsburgh , Pittsburgh, Pennsylvania.|4 Magee-Womens Research Institute , Pittsburgh, Pennsylvania.
authors.forename: Sharon L
authors.initials: SL
authors.lastname: Hillier
authors.affiliation: 4 Magee-Womens Research Institute , Pittsburgh, Pennsylvania.
authors.forename: Edward
authors.initials: E
authors.lastname: Livant
authors.affiliation: 5 Department of Bioengineering and Therapeutic Sciences, University of California , San Francisco, San Francisco, California.
authors.forename: Howard
authors.initials: H
authors.lastname: Horng
authors.affiliation: 6 University of Zimbabwe-University of California , San Francisco Collaborative Research Program, Harare, Zimbabwe .
authors.forename: Nyaradzo
authors.initials: N
authors.lastname: Mgodi
authors.affiliation: 7 Makerere University-Johns Hopkins University Research Collaboration , Kampala, Uganda .
authors.forename: Brenda G
authors.initials: BG
authors.lastname: Mirembe
authors.affiliation: 8 FHI 360, Durham, North Carolina.
authors.forename: Kailazarid
authors.initials: K
authors.lastname: Gomez Feliciano
authors.affiliation: 8 FHI 360, Durham, North Carolina.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Horn
authors.affiliation: 1 Department of Medicine, University of California , San Francisco, San Francisco, California.|9 San Francisco Department of Public Health, Bridge HIV , San Francisco, California.
authors.forename: Albert Y
authors.initials: AY
authors.lastname: Liu
authors.affiliation: 2 Department of Epidemiology and Biostatistics, University of California , San Francisco, San Francisco, California.
authors.forename: David V
authors.initials: DV
authors.lastname: Glidden
authors.affiliation: 1 Department of Medicine, University of California , San Francisco, San Francisco, California.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Grant
authors.affiliation: 5 Department of Bioengineering and Therapeutic Sciences, University of California , San Francisco, San Francisco, California.
authors.forename: Leslie Z
authors.initials: LZ
authors.lastname: Benet
authors.affiliation: 1 Department of Medicine, University of California , San Francisco, San Francisco, California.
authors.forename: Alexander
authors.initials: A
authors.lastname: Louie
authors.affiliation: 1 Department of Medicine, University of California , San Francisco, San Francisco, California.|10 RTI International , Women's Global Health Imperative, San Francisco, California.
authors.forename: Ariane
authors.initials: A
authors.lastname: van der Straten
authors.affiliation: 6 University of Zimbabwe-University of California , San Francisco Collaborative Research Program, Harare, Zimbabwe .
authors.forename: Z Mike
authors.initials: ZM
authors.lastname: Chirenje
authors.affiliation: 11 Department of Medicine, University of Alabama , Birmingham, Birmingham, Alabama.
authors.forename: Jeanne M
authors.initials: JM
authors.lastname: Marrazzo
authors.affiliation: 1 Department of Medicine, University of California , San Francisco, San Francisco, California.
authors.forename: Monica
authors.initials: M
authors.lastname: Gandhi
keywords: HIV and women; HIV prevention; PrEP Demo; VOICE; adherence monitoring; hair concentrations; iPrEx OLE; plasma concentrations; pre-exposure prophylaxis