CROI 2015 Program and Abstracts

Abstract Listing

Poster Abstracts

continued to use PrEP. For those not on PrEP 12 months after enrollment, the most frequent reasons included ART use by the HIV-infected partner (41%), loss to follow-up (30%), pregnancy and breastfeeding (9%), participant preference (8%), and partnership dissolution (6%). Tenofovir was detected in plasma at 86% of 168 visits from 74 randomly- selected participants receiving PrEP. Conclusions: In a demonstration project among high-risk HIV serodiscordant African couples, PrEP initiation was high. For most participants who chose to start PrEP, use was sustained while there was ongoing HIV risk. 970 PrEP Engagement for HIV Prevention: Results From the iPrEx Open Label Extension (OLE) David V. Glidden 6 ; Susan P. Buchbinder 1 ; Peter L. Anderson 2 ;Vanessa McMahan 3 ; K. Rivet Amico 4 ; Albert Liu 1 ; Sybil Hosek 5 ; Megha Mehrotra 6 ; Robert M. Grant 3 iPrEx Investigators 1 San Francisco Department of Public Health, San Francisco, CA, US; 2 University of Colorado, Denver, CO, US; 3 Gladstone Institute, San Francisco, CA, US; 4 University of Michigan, Ann Arbor, MI, US; 5 John Stronger Hospital, Chicago, IL, US; 6 University of California San Francisco, San Francisco, CA, US Background: Pre-exposure prophylaxis (PrEP) with FTC/TDF is a biologically potent strategy for interrupting HIV transmission. PrEP requires a chain of engagement termed the “prevention cascade”— seeking services, initiating FTC/TDF, HIV testing, medication refills and adequate adherence. We characterize this spectrum and identify potential predictors of engagement in the iPrEx OLE study. Methods: iPrEx OLE examined open-label PrEP uptake and adherence by enrolling men who have sex with men and transgender women at 11 sites in 6 countries and offering up to 18 months of open label FTC/TDF to HIV- former participants in 3 PrEP trials. They were followed quarterly with HIV testing and medical assessments regardless of whether they elected to receive PrEP. Exposure to FTC/TDF used a case/cohort design to test for TFV-DP in dried blood spots (DBS) collected for all on-PrEP seroconverters (n=28) and a randomly selected sample (n=325, 27%) of the cohort. iPrEx OLE showed TFV-DP levels ^ 700 fmol/punch (consistent with ^ 4 pills per week) as highly protective against HIV infection. Predictors of a DBS levels of ^ 700 fmol/punch were assessed in a probability weighted multivariable logistic regression model. Results: Of 1603 HIV- participants, 1125 (76%) initiated PrEP. At the 12 month visit after starting PrEP, 1005 of initiators (84%) attended, 813 had been dispensed PrEP at the last visit, and an estimated 354 had TFV-DP levels ^ 700 fmol/punch, yielding highly protective concentrations at 12 months in 22% of those offered PrEP. These percentages were 34% at 3 months and 26% at 6 months. TFV-DP levels ^ 700 fmol/punch at 12 months varied by site (p < 0.001) ranging from 11% to 63% of those offered PrEP. Percentages were higher among those reporting non-condom insertive anal intercourse (ncIAI) (p=0.02), a diagnosed sexual transmitted infection (p=0.046), a HIV+ partner (p=0.02), and secondary (p=0.03) or higher (P< 0.001) education. No significant differences were observed by transgender identity, age, non-condom receptive anal intercourse or drug use

Poster Abstracts

Conclusions: There are challenges across the prevention cascade in uptake of PrEP, as well as engagement with and adherence to PrEP. Less than half of participants who attended study visits and were dispensed medication had TFV-DP levels consistent with ^ 4 pills per week. Prevention engagement was higher among participants with secondary education, a HIV+ positive partner, a sexually transmitted infection, and ncIAI. 971 Preliminary Follow-up of Injecting Drug Users Receiving Preexposure Prophylaxis Michael T. Martin 1 ; SuphakVanichseni 2 ; Pravan Suntharasamai 2 ; Udomsak Sangkum 2 ; Philip Mock 1 ; Manoj Leethochawalit 3 ; Sithisat Chiamwongpaet 3 ; Somyot Kittimunkong 4 ; Marcel Curlin 1 ; Kachit Choopanya 2 1 US Centers for Disease Control and Prevention (CDC), Nonthaburi, Thailand; 2 Bangkok Tenofovir Study Group, Bangkok, Thailand; 3 Bangkok Metropolitan Administration, Bangkok, Thailand; 4 Ministry of Public Health, Nonthaburi, Thailand Background: The Bangkok Tenofovir Study (BTS) was a randomized, double-blind, placebo-controlled, HIV pre-exposure prophylaxis (PrEP) trial, conducted among people who inject drugs (PWID) in Bangkok 2005-2012. The trial demonstrated that taking tenofovir daily can reduce the risk of HIV infection 49% among PWID. Following the announcement of trial results, study participants were offered one year of open label tenofovir. We present demographic characteristics, risk behavior, and preliminary follow-up data from participants who chose to take daily open label tenofovir. Methods: BTS participants were offered tenofovir, free of charge, at 17 drug treatment clinics in Bangkok. Participant demographics and risk behaviors were assessed, using audio-computer-assisted self-interview, at baseline and every 3 months. HIV testing was done monthly and serum creatinine testing every 3 months. Results: From August 2013 through May 2014, 787 (35%) of 2254 surviving HIV-uninfected BTS participants chose to start taking tenofovir; 236 (30%) have completed 12 months follow-up. The median age of the 787 participants was 39 years, 631 (80%) were male, 394 (50%) had completed primary school or less education, and 128 (16%) were in prison. Risk behavior data were available for 718 (91%) participants; 149 (21%) reported injecting drugs during the 3 months before enrollment: 87 (58%) injected midazolam, 58 (39%) injected heroin, and 48 (32%) injected methamphetamine; 17 (11%) reported sharing needles. Based on summary data from participant adherence diaries, 26% of participants have missed <8 days in the most recent 28 days of follow-up. One participant has become HIV-infected after starting PrEP yielding an estimated HIV incidence of 3.3 (95% CI,

575

CROI 2015