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Characterization of HIV Seroconverters in a TDF/FTC PrEP Study: HPTN 067/ADAPT
Mariya V Sivay1, Maoji Li, Estelle Piwowar-Manning
1*Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD; †Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, WA; ‡Department of Health Behavior and Health Education, School of Public Health, University of Michigan, Ann Arbor, MI; §Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD; ‖Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institute of Health, Bethesda, MD; ¶Division of Clinical Pharmacology, Johns Hopkins University School of Medicine, Baltimore, MD; #Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO; **FHI 360, Durham, NC; ††Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa; ‡‡Department of Epidemiology and Biostatistics, University of California San Francisco School of Medicine, San Francisco, CA; §§Departments of Medicine and Epidemiology, Columbia University Affiliation at Harlem Hospital, New York, NY; ‖‖Columbia University Mailman School of Public Health, New York, NY; ¶¶Department of Biostatistics, University of Washington, Seattle, WA; and ##University of California, San Francisco Gladstone Institutes, San Francisco, CA.
Background:
HIV Prevention Trials Network (HPTN) 067/ADAPT evaluated tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) pre-exposure prophylaxis (PrEP) in women (South Africa) and men who have sex with men (Thailand, US). Participants received once-weekly directly observed therapy (DOT) of TDF/FTC, and were then randomized to daily, time-driven, or event-driven PrEP. This report describes characterization of 12 HIV seroconversion events in this trial.
Methods:
HIV rapid testing was performed at study sites. Retrospective testing included fourth generation assays, HIV RNA testing, Western blot, an HIV-1/2 discriminatory assay, resistance testing, and antiretroviral drug testing.
Results:
Six of the 12 seroconverters received TDF/FTC in the DOT phase, but were not randomized (3 were acutely infected at enrollment; 2 were infected during the DOT phase; 1 was not randomized because of pregnancy). One of the 6 randomized participants had acute infection at randomization but was not diagnosed for 3-4 months because HIV rapid tests were nonreactive; continued daily PrEP use was associated with false-negative antibody tests and low HIV RNA levels. The 5 participants infected after randomization included 4 with low adherence to the PrEP regimen, and one who reported a 7-day period without dosing before infection. Three participants had TDF/FTC resistance (M184I, K65R), including 2 who received only 4 once-weekly TDF/FTC doses; most TDF/FTC mutations were detected by next generation sequencing only.
Conclusions:
In HPTN 067/ADAPT, participants who acquired HIV infection had infrequent PrEP dosing or low/suboptimal adherence. Sensitive assays improved detection of HIV infection and drug resistance. Drug resistance was observed with limited PrEP exposure.
