CROI 2024 Abstract eBook

Abstract eBook

Poster Abstracts

Conclusion: We observed in our high dose rectal SHIV challenge model that a single dose of CAB LA and RPV LA given 24 hours after virus exposure provided clinical drug exposures for 4 weeks but was partially effective. Late and transient detection of SHIV RNA in breakthrough infections with or without seroconversion is similar to findings in persons failing prophylaxis with CAB LA and highlights diagnostic challenges of this PEP modality. Our results underscore the limitations of single-dose CAB LA and RPV LA use for PEP in humans.

percentage change (EAPC) with 95% confidence intervals (CI) and compared with trends in persons prescribed PrEP. Results: During 2013−2022, the annual number of PEP prescriptions ranged from 13,999−17,996. Among 16,826 PEP users in 2022, 51.2% were women, 60.1% were aged 25-44 years, 35.6% resided in the South, 37.5% had public insurance paying for their PEP, and 43.1% had private insurance. Among 12,042 PEP prescribers in 2022, 60.4% were physicians, and 38.3% were nurse practitioners or physician assistants. Among physicians, 47.2% were primary care doctors, followed by emergency care doctors (31.0%) and infectious diseases doctors (12.0%). Comparing with trends in number of persons prescribed PrEP (EAPC=33.0%, 95% CI 32.9-33.0), we observed modest increases in number of persons prescribed PEP during 2013-2022 (EAPC=1.4%, 95% CI 1.2-1.5, Figure). PEP increases were uneven between age groups. For persons aged 16-24 years, PEP prescriptions increased from 199 in 2013 to 1,373 in 2022 (EAPC=22.1%; 95% CI: 21.0-23.2); for persons aged 25-34 years, it increased from 1,864 in 2013 to 6,205 in 2022 (EAPC=11.8%; 95% CI: 11.4-12.2). Conclusion: We did not observe a consistent trend in PEP prescriptions, unlike the markedly increasing trend in PrEP over the last decade. PEP may be an underutilized tool for HIV prevention, particularly among the groups mostly experiencing new HIV infections. Interventions such as clinical decision support in electronic health systems, provider and population education, and structural interventions are needed to increase PEP use. Interventions to support PEP prescribing are particularly important in the primary care and emergency department clinical settings. 1132 Efficacy of Long-Acting Cabotegravir and Rilpivirine for PEP in a Macaque Model of RT SHIV Infection Priya Srinivasan , Jining Zhang, Tiancheng Edwards, Chuong Dinh, Ayanna Green, Dawn Little, Maria Mendoza, Yi Pan, Frank Deyounks, Ryan Johnson, Athena Kourtis, Walid Heneine, Gerardo Garcia-Lerma, James Smith Centers for Disease Control and Prevention, Atlanta, GA, USA Background: Current recommendations for post-exposure prophylaxis (PEP) for non-occupational HIV exposures include 28 days of daily oral antiretroviral drugs. However, low adherence, and inadequate regimen completion represents an important challenge. We examined whether a single injection of the combination of long-acting cabotegravir and rilpivirine (CAB LA and RPV LA) could be an effective PEP regimen in macaques. Methods: Human equivalent doses of CAB LA (50 mg/Kg) and RPV-LA (100 mg/Kg) were administered intramuscularly to 6 rhesus macaques 24 hours post rectal exposure to a single high dose of RT SHIV (10 3.3 TCID 50 ). Infection outcome was compared to 7 untreated controls (3 real-time, 4 historical). Blood was collected through 43 weeks post challenge to monitor for plasma CAB and RPV levels and SHIV infection. Plasma CAB and RPV levels were monitored by LC-MS/ MS. Poisson regression with robust error variance was applied to estimate PEP efficacy and confidence intervals. Results: Median concentrations of CAB and RPV in plasma during the first 28 days after injection were within clinically relevant levels (5,860, range= 2,130-15,650 and 64.5, range= 20-127 ng/mL), respectively. All controls became viremic 7 days post challenge with a median plasma viral peak of 5.13 x 10 6 copies/mL. Four of the six treated macaques remained aviremic and seronegative through week 43 post challenge. The remaining 2 animals had detectable SHIV RNA at week 11 (breakthrough 1) and 39 (breakthrough 2) post-exposure. The calculated efficacy of CAB LA/RPV LA was 0.667 (95% CI= -0.0335, 0.893) (p=0.0571). Breakthrough 1 was characterized by transient low-level viremia between weeks 11 to 13 (range 327-2736 SHIV RNA copies/ mL), a virus blip at week 33 (68 copies/mL), and absence of seroconversion. Breakthrough 2 had detectable viremia between weeks 39 and 43 (range 309-1033 SHIV RNA copies/mL) when CAB and RPV were low or undetectable in plasma and seroconverted at week 43 (Figure 1).

1133 PrEP Following PEP: An Effective HIV Risk-Reduction Strategy Gary Whitlock , Courtney Taylor, Lucy Turner, Holly Thompson Chelsea and Westminster NHS Foundation Trust, London, United Kingdom Background: From January 2021, individuals attending a sexual health service in London, UK who receive HIV post-exposure prophylaxis following sexual exposure (PEPSE) are offered quick-start opt-out PrEP with a 1-month supply to take immediately following completion of PEP, PEP2PrEP, a risk reduction strategy for individuals with ongoing risk of HIV acquisition. We present the uptake of PrEP in GBMSM and transwomen attending our service for PEP and their subsequent PrEP follow-up. Methods: We performed a case note review of PEPSE recipients at our service from 1st March to 30th April 2022, collecting demographics, characteristics of the PEPSE risk, previous PrEP use and follow-up consultations up to 31st August 2023. Statistical analysis was done using chi-square and Mann-Whitney U tests. Results: 282 GBMSM and 6 transwomen received PEPSE during March- April 2022. Median age was 29 y (IQR: 25-37 y). Primary PEPSE indication was condomless anal intercourse: receptive (244, 84.7%) and insertive (43; 14.9%) and receptive vaginal intercourse (1; 0.3%). During the encounter, 31 (10.8%) used chems, 63 (21.9%) had sex with more than one individual. 126 (43.8%) PEPSE recipients stated previous PrEP use. Common reasons for not using PrEP were: having no supply (38, 30.2%), on break (30, 23.8%), spontaneous sex (19, 15.1%), incorrect PrEP dosing requiring PEPSE (16, 12.7%), reason not given (23, 18.3%). 212 (73.6%) subsequently started PrEP. Of these, 114 (54.2%) reattended for a subsequent PrEP consultation in the follow-up period. PEPSE users who subsequently started PrEP compared with those who did not were more likely to have used PrEP previously (50.0% vs. 26.3%, p=0.00036) and to have had sex with multiple individuals during their PEPSE exposure (25.0% vs. 13.2%; p=0.036). Conclusion: Almost half of PEPSE recipients have previously used PrEP. The most common reason for not using PrEP was having no supply. In PEPSE recipients, the subsequent uptake of PrEP is high with a majority reattending for PrEP in the subsequent year. Efforts to increase retention in PrEP care are required for those with ongoing risk of HIV acquisition. 1134 BIC/FTC/TAF as HIV PEP Was Well-Tolerated With High Adherence and No Seroconversions Darrell H Tan 1 , Reva Persaud 1 , Attia Qamar 2 , Isaac I. Bogoch 3 , Arlene Chan 4 , Allison Chris 5 , Karla Fisher 3 , Richard T. Lester 6 , John Maxwell 7 , James Murray 8 , Hong Qian 9 , Hubert Wong 9 1 St Michael's Hospital, Toronto, Canada, 2 Scarborough Health Network, Toronto, Canada, 3 University Health Network, Toronto, Canada, 4 Women's College Hospital, Toronto, Canada, 5 Toronto Public Health, Toronto, Canada, 6 University of British Columbia, Vancouver, Canada, 7 AIDS Committee of Toronto, Toronto, Canada, 8 Ontario Ministry of Health and Long-Term Care, Ontario, Canada, 9 Canadian HIV Trials Network, Vancouver, Canada Background: Integrase inhibitor-based regimens are the standard of care for HIV post-exposure prophylaxis (PEP), but no such single tablet regimens are recommended in current guidelines. We analyzed tolerability, adherence and HIV seroconversions with bictegravir, emtricitabine and tenofovir alafenamide (B/F/TAF) as HIV PEP in an ongoing clinical trial of text-messaging support versus standard of care for PEP users. Methods: Adults initiating a standard PEP regimen within the preceding five days for a confirmed or potential sexual exposure to HIV were randomized to either receive short message service (SMS) check-ins using the WelTel platform,

Poster Abstracts

CROI 2024 368