HPTN 067

A Phase II, Randomized, Open-Label, Pharmacokinetic and Behavioral Study of the Use of Intermittent Oral Emtricitabine/Tenofovir Disoproxil Fumarate
Pre-Exposure Prophylaxis (PrEP)

Study Summary
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What is HPTN 067?

HPTN 067, also known as the ADAPT Study, was designed to assess whether non-daily use of oral FTC/TDF as pre-exposure prophylaxis (PrEP), compared with daily use, would demonstrate equivalent coverage of sex acts, lower number of pills needed for coverage and decreased self-reported drug side effects over 24 weeks. The study also evaluated self-reported adherence and analyzed drug levels in the blood of participants.

Who participated in the study?

The study of more than 500 participants included women in Cape Town, South Africa, and men who have sex with men (MSM) and transgender women (TGW) in Bangkok, Thailand, and Harlem, N.Y.

What happened during the study?

After a four-week period of once-a-week directly observed dosing, participants were randomly assigned to one of three PrEP dosing regimens for 24 weeks: a) daily, b) time-driven: twice weekly with a post-sex dose, or c) event-driven: before and after sex. Study participants were given a Wisepill device that tracks each time a participant opens the container to take a pill. These data were then used by a study team member to conduct weekly phone or in-person interviews to ask participants if the date and time recorded by the Wisepill device did indeed involve taking a dose. Dates and times of sex events over the past week were also collected in these interviews. The interviews were for data collection only, so interviewers remained neutral and no messaging on adherence or non-adherence was provided, nor were data shared with study adherence counselors.

Blood samples were collected and analyzed for tenofovir (FTC/TDF) and their active metabolites at 10 and 30 weeks on study. In addition to overall adherence, the study evaluated PrEP coverage for each sex event, defined as taking at least one pill in the four days (96 hours) before the sex event and at least one pill within 24 hours after sexual intercourse. The regimens used in this trial and the definition of PrEP coverage was based on information that was available when the trial was designed in 2010. More current information suggests that higher concentrations of PrEP medications are required for protection from vaginal exposure to HIV, as would be afforded by daily oral dosing or any topical dosing.

Results:

Results from each group of participants were analyzed separately.

Thai MSM in Bangkok had the highest levels of coverage and adherence to the daily and time-driven dosing regimens. These were both significantly higher compared to the event-driven arm (85% of all sex events were covered in the daily arm, 84% in the time-driven arm and 74% in the event-driven arm). These findings indicate that some MSM and TGW could adhere to these non-daily PrEP regimens, though coverage was significantly lower in the event-driven arm.

In a cohort of young, predominantly Black MSM in Harlem, N.Y., participants had a statistically significant higher level of coverage of sex acts in the daily arm (66% of all sex events were completely covered) compared to the non-daily arms (47% of all sex events were covered in the time-driven arm; 52% of all sex events were covered in the event-driven arm). Adherence was significantly higher among those assigned to the daily arm compared to those assigned to the non-daily arms.

HPTN 067 demonstrated that young, single, black women in South Africa can take and adhere to a daily regimen of PrEP. This study showed high levels of coverage of sex acts in the daily arm (75%) among study participants in Cape Town when they were aware that the product works and that they were receiving the active product (i.e., in the setting of an open label study, not a placebo-controlled trial).

067 team