IAS 2015: Gay Youth PrEP Study Finds Good Retention and Reasonable Adherence

A U.S. study of Truvada pre-exposure prophylaxis (PrEP) looking at 200 young gay and bisexual men aged 18-22 in a dozen cities found reasonable levels of adherence, researchers reported at the 8th International AIDS Society Conference on HIV Pathogenesis, Treatment and Prevention last week in Vancouver. Adherence was highest among those with the highest risk of HIV. However, adherence dropped off considerably after study visits changed from monthly to quarterly, suggesting that gay youth starting PrEP would benefit from more intensive support than older participants. The study also found considerably lower adherence among young black and mixed-race men.

[Produced in collaboration with Aidsmap.com]

ATN (Adolescent Trials Network) study 110 is one of a series of studies investigating the safety and feasibility of PrEP in young gay men. A previous pilot study, ATN 082, was reported in 2013. A third study, ATN 113, which is looking at PrEP in teenagers aged 15-17, is due to report in 2016.

Sybil Hosek of Stroger Hospital in Cook County, Chicago told conference delegates that men who have sex with men (MSM) aged 13-24 were the group hardest hit by the HIV epidemic U.S., but were not represented in earlier PrEP studies.

ATN 110 was conducted at clinic sites in 12 cities throughout the U.S. (Baltimore, Boston, Chicago, Denver, Detroit, Houston, Los Angeles, Memphis, Miami, New Orleans, Philadelphia, and Tampa). Criteria for eligibility included condomless anal sex in the last 6 months with a partner of positive or unknown HIV status, more than 3 condomless sex partners in the last 6 months, sex in exchange for gifts or money, and sex with a partner diagnosed with a sexually transmitted infection (STI).

Initially, candidates for the study registered interest online or during information visits conducted at health venues. Over 2000 men were initially contacted at the pre-screening stage, but 42% decided they were not interested and 40% did not meet trial eligibility criteria. This left 400 eligible. Of these, 123 decided at this stage that they did not wish to participate, leaving 277 who were asked to attend a screening visit. Of these, 34 did not turn up or lost contact, 15 were excluded for medical reasons, and 11 (4.4% of those screened) tested HIV-positive. This left 200 participants, of whom 142 stayed the full length of the trial. 35 were lost to follow-up, which is actually quite a low proportion for this highly mobile population. 25 participants (12.5%) decided to stop taking PrEP due to side effects, largely gastrointestinal, during the study.

The average age of the 200 enrolled participants was 20 years, 78% identified as gay and the rest bisexual, 30% were unemployed, and a third had no education beyond age 16. 1 in 6 stated that they had been kicked out of their home, and 29% had been paid for sex. 53% were black, 17% were Hispanic/Latino, and 21% were white, with the rest mixed-race and Asian and Pacific Islanders.

The average number of partners in the last month was 5. 81% had condomless sex in the last 6 months; 58% of participants said the last sex they had involved being the passive partner in condomless anal sex. Over 20% had tested positive for an STI in the past.

The participants were not immediately given PrEP. First, they did either a 7-week behavioral course designed to strengthen self-care and assertiveness behaviors (Many Men, Many Voices), or the equivalent number of sessions of cognitive-behavioral counseling. Only after this were they given Truvada (tenofovir/emtricitabine) PrEP. They were not randomized to the interventions as the clinics involved in the study were already offering one or the other of these 2 interventions.

 

Adherence to PrEP was initially good, with just under 60% of participants with blood drug levels over the level that would indicate that at least 4r doses a week were being consistently taken, which is regarded as being fully protective. At the second monthly visit, 95% of participants showed evidence of having taken at least some PrEP.

However adherence levels fell noticeably after week 12 of the 48-week study, when clinic visits switched from monthly to quarterly. By the end of the study only 35% of participants were taking at least 4 doses of Truvada a week and 30% showed no sign of having taken PrEP at all.

There was a sharp racial divide in adherence. White and Latino participants maintained a median level of more than 700 ng/mL of tenofovir in their blood throughout the study, a level equivalent to 4+ doses a week. In contrast, black participants, on average, never quite achieved the 4+ doses a week level, and by the end of the study median drug levels in black participants was scarcely above zero, indicating very little use of PrEP.

Hosek commented: "This is a group of young men very few of whom have health insurance or go to healthcare regularly. We need to do more research on the health beliefs and levels of trust of our participants in order to understand what might support PrEP use."

One participant was found to have HIV at the 1 month visit and had been in his "window period" (HIV not yet detectable) at his first study visit. This was not counted as an HIV infection occurring within the study.

There were 4 new infections among participants during the study, at weeks 8, 32, 40, and 48, giving an annual incidence rate of 3.29% per year. All these 4 had taken PrEP at some point, but none had detectable levels of tenofovir in their blood at the study visit where HIV was diagnosed. The last man to be infected, at week 48, had maintained protective levels of PrEP until halfway through the study and had then started taking it less often; the other 3 had difficulties with adherence from the start.

Hosek reported that 40% of participants had had an STI in the last 24 weeks at baseline; this declined to 30% at weeks 24 and 48 of the study, though this decline was not statistically significant. The number of condomless sex partners fell from over 5 in the last month to 3 after the first visit and did not increase. This change was also not statistically significant, nor was any other change in risk behavior, either the number of partners or the proportion with whom they had condomless receptive anal sex.

However, participants who reported engaging in condomless sex had consistently higher levels of tenofovir at all study visits, indicating that PrEP use was significantly related to perceived risk (p=0.005).

"ATN 110 successfully engaged young men who had sex with men who would be eligible for PrEP," Hosek commented. "HIV incidence rate was high compared to PrEP arms in other open label trials but, given the high number of incident STIs, it would likely be even higher in the absence of PrEP."

7/31/15

Reference

S Hosek, B Rudy, R Landovitz, et al. An HIV pre-exposure prophylaxis (PrEP) demonstration project and safety study for young men who have sex with men in the United States (ATN 110). 8th International AIDS Society Conference on HIV Pathogenesis, Treatment, and Prevention. Vancouver, July 19-22, 2015. AbstractTUAC0204LB.