CROI 2015 Program and Abstracts

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Poster Abstracts

Results: Anti-HIV antibody titers, by both BED-CEIA and BioPlex assays did not differ between women assigned to TFV gel compared to those assigned to placebo gel. However, women assigned to TFV gel demonstrated slower antibody avidity maturation as determined by the Bio-Rad assay (p=0.04). In the Cox proportional hazard model, after adjustment for CD4 count and viral load, there was a significant reduction in the time to high avidity (HR=0.52, CI=0.32-0.84; p=0.008). For the Bio-Plex assay, there was a statistically significant slower increase in antibody avidity to gp120 (p=0.03) and a trend in gp160 (p=0.06) using a linear mixed effects model. Conclusions: Women assigned to topical TFV had slower antibody maturation, similar to effects previously seen in TFV PrEP treated rhesus macaques. These results may have substantial public health implications for antibody-based incidence measurement as PrEP use increases globally. 988 Medication Sharing Among African HIV Serodiscordant Couples Enrolled in a PrEP Trial Kerry A. Thomson 1 ; Jessica Haberer 4 ; Connie Celum 1 ; Andrew Mujugira 1 ; Patrick Ndase 1 ; Craig Hendrix 2 ; Mark A. Marzinke 2 ; Allan Ronald 3 ; David Bangsberg 4 ; Jared Baeten 1 On behalf of the Partners PrEP StudyTeam 1 University of Washington, Seattle, MA, US; 2 Johns Hopkins University, Baltimore, MD, US; 3 University of Manitoba, Winnipeg, Canada; 4 Massachusetts General Hospital, Boston, MA, US Background: Pre-exposure prophylaxis (PrEP) demonstrated high efficacy for HIV prevention among African HIV serodiscordant couples. One concern for PrEP implementation in all populations, and specifically for HIV serodiscordant couples, is the potential for PrEP medications to be shared with HIV-1 infected individuals. Drug sharing undermines PrEP efficacy for the HIV uninfected person prescribed PrEP and risks development of antiretroviral resistance in the HIV infected person who surreptitiously takes PrEP. Methods: The Partners PrEP Study was a randomized placebo-controlled trial of daily oral tenofovir disproxil fumarate, alone or in combination with emtricitabine, among 4,747 African HIV serodiscordant couples. HIV infected partners were not eligible for or taking antiretroviral therapy (ART) at enrollment and were referred for ART during follow-up based on national ART eligibility guidelines. Self-reported data on sharing study drug tablets between study partners were collected from HIV uninfected partners at monthly study visits and from HIV infected partners annually. To examine biological evidence of drug sharing, tenofovir concentrations (>0.31 ng/mL) were measured in plasma collected at unannounced home visits from a random sample of 100 HIV infected partners not reporting ART. Results: In 95,520 monthly study visits completed with HIV uninfected partners, there were three reports (0.003%) of drug sharing with their study partner; their HIV infected partner had taken a maximum of three study tablets in the prior month. In 5,605 annual visits with HIV infected partners, there was one (0.02%) report of taking one dose of the partner’s study tablets. Tenofovir was detected in zero of 99 HIV infected partners at unannounced home visits (0%, 95% CI: 0-3.0%); one additional HIV-1 infected individual had an undetectable plasma HIV RNA concentration and tenofovir detected at enrollment and throughout follow-up, suggesting unreported use of tenofovir-containing combination ART rather than PrEP sharing. Conclusions: In this clinical trial of PrEP, self-reported drug sharing appeared to be extremely rare and limited to HIV infected partners taking a small number of study pills during one study month. Plasma tenofovir testing supported the finding that sharing PrEP within HIV serodiscordant couples was uncommon. Concern about PrEP sharing should not be a limitation for PrEP implementation, although ongoing study outside of clinical trials is warranted. 2:30 pm– 4:00 pm HIV Prevention, Miscellaneous 989 HIV-1 Transmission Risk Persists During the First 6 Months of Antiretroviral Therapy AndrewMujugira 1 ; KatherineThomas 1 ; Connie Celum 1 ; Deborah Donnell 2 ; Carey Farquhar 1 ; Elizabeth Bukusi 3 ; Jared Baeten 1 On behalf of the Partners PrEP StudyTeam 1 University of Washington, Seattle, WA, US; 2 Fred Hutchinson Cancer Research Center, University of Washington, Seattle, WA, US; 3 Kenya Medical Research Institute, Nairobi, Kenya Background: Combination antiretroviral therapy (ART) decreases the risk of sexual HIV-1 transmission by suppressing HIV-1 RNA concentrations in blood and genital secretions to below undetectable levels. However, HIV-1 transmission may still occur prior to complete viral suppression. Methods: Using data from a prospective study of heterosexual HIV-1 serodiscordant African couples (Partners PrEP Study, placebo arm), we quantified HIV-1 transmission risk in 3 time periods: between ART eligibility and treatment initiation, during the first 6 months of ART, and after more than 6 months of ART by when viral suppression is usually achieved. Sexual behavior, self-report of ART use by infected partners, and HIV-1 status of uninfected partners were assessed every 1-3 months. HIV-1 testing was performed using paired rapid antibody tests, with positive results confirmed by ELISA. The primary outcome was phylogenetically-linked HIV-1 transmission within the couple. Results: We followed 496 uninfected members of serodiscordant couples for 510 person-years. The estimated proportion of unprotected sex acts was 8.1% between ART eligibility and ART initiation, 9.9% during the first 6 months of ART, and 10.8% during > 6 months of ART. HIV-1 incidence in couples eligible but not yet initiating ART was 1.71 per 100 person-years (95% CI: 0.35-5.01, 3 infections in 175 person-years). During the first 6 months after ART initiation, HIV-1 incidence was similar - 1.79 per 100 person-years (95% CI: 0.37-5.22, 3 infections in 168 person-years). There were no transmissions in 167 person-years after >6 months of ART (incidence rate, 0.00 per 100 person-years; 95% CI: 0.00, 2.20). Conclusions: There was residual risk of HIV-1 transmission during the first 6 months after starting ART, as well as in couples who were eligible for ART but had not yet started treatment. For HIV-1 serodiscordant couples in which the infected partner is starting ART, or is eligible for ART but delays or declines therapy, other prevention options, such as antiretroviral pre-exposure prophylaxis, are needed, in addition to counseling to encourage ART initiation. 990 Long-Term ART Outcomes in Botswana Encouraging Treatment as Prevention Approach Hermann Bussmann 4 ;William C.Wester 1 ; Ernest Fetogang 2 ;Tony Chebani 2 ; Sikhulile Moyo 3 ; Naledi M. Mlaudzi 2 ; ErikV.Widenfelt 3 ; Joseph Makhema 3 ; Max Essex 4 ; Richard Marlink 4 1 Vanderbilt University School of Medicine, Nahville, TN, US; 2 Ministry of Health, Gaborone, Botswana; 3 Botswana Harvard AIDS Institute Partnership for HIV Research and Education, Gaborone, Botswana; 4 Harvard School of Public Health, Boston, MA, US Background: Treatment as prevention (TasP) is currently the most promising HIV prevention strategy. Long-term adherence to TasP regimens and retention in care are critical to the success of this strategy. We herein report 10-year follow up among ART cohort participants initially enrolled in a 3-year randomized clinical trial (RCT) with two adherence strategies. THURSDAY, FEBRUARY 26, 2015 Session P-V6 Poster Session Poster Hall

Poster Abstracts

584

CROI 2015