CROI 2020 Abstract eBook

Abstract eBook

Poster Abstracts

1028 DRUG LEVELS, ADHERENCE, AND RISKS FOR LOW ADHERENCE IN THE DISCOVER PrEP STUDY Susanne Doblecki-Lewis 1 , Olamide Dosekun 2 , Moti Ramgopal 3 , Jay Gladstein 4 , Mezgebe Berhe 5 , Kevin Nguyen 6 , Jason Hindman 6 , Yongwu Shao 6 , Ramin Ebrahimi 6 , Diana Brainard 6 , Moupali Das 6 , Scott McCallister 6 , Adriano Lazzarin 7 , Gerold F. Lang 8 , Peter L.Anderson 9 1 University of Miami, Miami, FL, USA, 2 Imperial College Healthcare NHS Trust, London, UK, 3 Midway Immunology and Research Center, Fort Pierce, FL, USA, 4 APLA Health, Los Angeles, CA, USE, 5 North Texas Infectious Diseases Consultants, Dallas, TX, USA, 6 Gilead Sciences, Inc, Foster City, CA, USA, 7 Ospedale San Raffaele, Milano, Italy, 8 Dr med unvi Gerold Felician Lang, Vienna, Austria, 9 University of Colorado, Aurora, CO, USA Background: In over 8,700 person-years (PY) follow up in the DISCOVER PrEP trial, the HIV incidence rates in the emtricitabine/tenofovir alafenamide (F/ TAF) and emtricitabine/tenofovir disoproxil fumarate (F/TDF) arms were 0.16 and 0.34/100 PY, demonstrating noninferiority for HIV prevention. Study investigators and site staff provided comprehensive adherence support to study participants at all visits. Methods: 5,387 men who have sex with men (MSM) and transgender women (TGW) at high HIV risk were randomized 1:1 to receive blinded once daily F/TAF or F/TDF. At all visits, adherence was assessed by self-report on a confidential questionnaire and also by pill count. Dried blood spot analyses of tenofovir diphosphate (TFV-DP) in red blood cells (RBCs) were assessed in a randomly selected subset of 10% participants, and in any participant who acquired HIV; peripheral blood mononuclear cell (PBMC) TFV-DP levels were assessed at W4 in the same subset. Adherence support included adherence counseling at each visit, personal communications from site staff as needed, optional text messaging daily, and email updates periodically. Results: 17 of the 22 HIV infections diagnosed in DISCOVER occurred while on study; 5/22 were suspected baseline infections. Of the 17 HIV infections that occurred on study, 6/17 occurred in the F/TAF arm and 11/17 occurred in the F/TDF arm. In 15 of the 17 on study HIV infections, DBS testing demonstrated that participants had undetectable or low TFV-DP levels in RBCs. By univariate logistical regression analysis, 5 baseline variables were significantly associated with low adherence by DBS (see Table); 2/5 were selected by multivariate stepwise analysis (asterisks). In both arms, adherence of at least 95%was >80% by self-report and was 69% by pill count. In the F/TAF and F/TDF arms respectively, 86-96% and 84-93% of participants were using at least 4 tablets/ week, as measured by TFV-DP levels in RBCs. Levels of TFV-DP in PBMCs strongly correlated with tablets per week adherence TFV-DP levels in RBCs. Conclusion: DISCOVER participants had very high adherence and very low HIV incidence rates. TFV-DP levels in RBCs were significantly lower in those with low adherence. The most important risk factor for acquisition of HIV on study was low adherence. Not using PrEP at baseline, black race, US residence, age below 25, and less than 4 years of college were significant risks for having low adherence to study drugs.

immunization after infection and vaccination was noted for 12% (50/427) and 67% (287/427) of subjects, respectively. Absence of prior HBV immunization (21%, 90/427) was associated with tobacco use (p=0.05). Among HAV non- immune subjects, 96% (207/215) received ≥1 dose of HAV vaccine and 91% (172/189) received a complete scheme. Among HBV non-immune subjects, 98% (88/90) received ≥1 dose of HBV vaccine and 79% (58/73) received a complete scheme. Among subjects with complete scheme, anti-HAV IgG and anti-HBs Abs were detected on last available sample in 93% (148/159) and 80% (44/55) respectively. Among subjects with incomplete scheme, anti-HAV IgG and anti-HBs Abs were detected on last available sample in 80% (12/15) and 36% (5/14) respectively. After the 1st dose of HBV vaccine 63% (37/59) of subjects developed anti-HBs Abs. Conclusion: The acceptability and efficacy of HAV and HBV vaccination were high in the IPERGAY population. High receptivity to prevention messages and free of charge vaccination may have favored the acceptability. Physicians must consider HAV and HBV vaccination in subjects receiving PrEP. 1027 HIGH PrEP ADHERENCE BASED ON TFV-DP LEVELS IN THAI 15-19-YEAR- OLD MSM AND TRANSWOMEN Wipaporn Natalie Songtaweesin 1 , Thanyawee Puthanakit 1 , Surinda Kawichai 1 , Tim R. Cressey 2 , Prissana Wongharn 1 , Tuangtip Theerawit 1 , Somsong Teeratakulpisarn 3 , Danai Linjongrut 4 , Surang Janyam 5 , Nittaya Phanuphak 3 1 Chulalongkorn University, Bangkok, Thailand, 2 Harvard T.H. Chan School of Public Health, Boston, MA, USA, 3 Thai Red Cross AIDS Research Center, Bangkok, Thailand, 4 Rainbow Sky Association of Thailand, Bangkok, Thailand, 5 Service Workers In Group Foundation, Bangkok, Thailand Background: Thailand initiated the first regional pre-exposure prophylaxis (PrEP) program in 2014, which has reached 10,000 PrEP users, including adolescents. Our objective was to assess 6-month adherence to oral tenofovir- diphosphate/emtricitabine (TDF/FTC) PrEP among adolescent men who have sex with men (MSM) and transgender women (TGW) in Bangkok. Methods: MSM and TGW aged 15-19 years were provided free daily TDF/FTC with condoms funded by the Princess PrEP demonstration project and CIPHER program at youth-friendly clinics. Monthly contact was via clinic visits (months 0, 1, 3, 6) or telephone calls (months 2, 4, 5) after PrEP initiation. Clients were counselled on PrEP adherence and behavioral risk reduction. Self-reported sexual risk behaviors including sex acts and condom use were recorded. Dried blood spots (DBS) were collected for quantification of TFV-DP levels at months 3 and 6 using a validated LC-MS/MS assay. Behavioral risk data were summarized into 3-month blocks to assess HIV protection (PrEP and/or 100% condom use). TFV-DP levels of <100, ≥100-349, ≥350-699 and ≥700 were taken to be ‘not protective’, ‘partly protective’, ‘protective’ and ‘highly protective’ respectively against HIV. Results: Between March 2018 and June 2019, 148 MSM (74%) and 52 TGW (26%) were initiated on PrEP. Twenty-two percent had a sexually transmitted infection at enrollment. Median (IQR) sex acts per 3-month block was 8 (4-14). Retention at months 3 and 6 was 86% and 75%, respectively. There were 199 DBS samples collected (123 and 76 at months 3 and 6 respectively). TFV-DP levels were ≥700, ≥350-699, 100-349 and <100 fmol/punch in 47%, 17%, 20% and 16%, respectively. Among 199 risk periods, 46%were protected by PrEP only, (12% and 34% of samples with TFV-DP levels of ≥350-699 and ≥700 fmol/ punch, respectively), 15%were protected by PrEP and condom use, 11%were protected by condoms alone, and 28% remained at risk of HIV acquisition. Of the 76 adolescents who completed the study, 66%were protected at month 3, and of these, 37/50 (74%) remained protected at month 6 (see table 1). There were 8 adolescents (11%) whose adherence improved and 13 (17%) whom declined when comparing the first and second periods of PrEP use. No seroconversions occurred in this study. Conclusion: Youth-friendly clinics and monthly follow-up in adolescent MSM and TGW provided a 72% HIV risk reduction by either ‘protective’ TFV-DP levels and / or 100% condom use. PrEP rollout should be encouraged in adolescent MSM and TGW.

Poster Abstracts

CROI 2020 386