CROI 2025 Abstract eBook

Abstract eBook

Oral Abstracts

Results: Among 19,676 individuals dispensed PrEP, 141 (0.7%) were administered CAB-LA during the study period. Among 141 CAB-LA users, 21.3% had no prior oral PrEP use; of those who had previously used oral PrEP, 21.6% had not been dispensed oral PrEP for >12 months prior to starting CAB-LA. Compared with oral-PrEP-only users, a lower proportion of CAB-LA users were commercially insured (82.3% vs 90.1%; P =0.002) and a higher proportion were female (9.2% vs 4.8%; P =0.049), Black (16.3% vs 6.1%; P <0.001), or Hispanic (36.2% vs 25.0%; P <0.001). There were no differences in history of diabetes or osteopenia/osteoporosis, but a higher proportion of CAB-LA users than oral-PrEP-only users had a history of hypertension (23.4% vs 13.4%; P =0.001) or bacterial sexually transmitted infection (44.7% vs 29.1%; P <0.001). Among CAB-LA users, 78.3% and 73.0% persisted on CAB-LA at 28 and 60 weeks after initiation, respectively. Of 450 non-lead-in injections, 92.2% were within 8 weeks + 7 days after the prior injection. Among 117 CAB-LA users with repeat HIV testing, there were zero HIV infections during 85.1 person-years of follow up. Conclusions: Uptake of CAB-LA was very low even in this insured setting, but persistence was high, with most CAB-LA users continuing to receive timely injections more than a year after initiation. CAB-LA is reaching populations who have been underserved by oral PrEP implementation, including individuals without private insurance, females, and racial and ethnic minority groups, as well as individuals who had not previously used oral PrEP or had used it but discontinued. ImPrEP CAB Brasil: Enhancing PrEP Coverage With CAB-LA in Young Key Populations Carolina Coutinho 1 , Brenda Hoagland 1 , Beatriz Grinsztejn 1 , Alessandro S. Farias 2 , Jose Valdez Madruga 3 , Josué Lima 4 , Maria Paula Mourão 5 , Roberta Pereira Trefiglio 3 , Marcos Benedetti 6 , Cristina Pimenta 6 , Ronaldo Ismério 1 , Raphael J. Landovitz 7 , Thiago Silva Torres 1 , Valdilea Gonçalves Veloso 1 , for the ImPrEP CAB Brasil Study Group 1 Instituto Nacional de Infectologia Evandro Chagas, Rio de Janeiro, Brazil, 2 Centro Especializado em Diagnóstico, Assistência e Pesquisa (CEDAP), Salvador, Brazil, 3 Centro de Referência e Treinamento DST/AIDS-SP, Sao Paulo, Brazil, 4 Centro de Referência em Infecções Sexualmente Transmissíveis, Vitória, Brazil, 5 Fundação de Medicina Tropical Heitor Vieira Dourado, Manaus, Brazil, 6 Oswaldo Cruz Foundation, Rio de Janeiro, Brazil, 7 University of California Los Angeles, Los Angeles, CA, USA Background: Long-acting agents hold promise for addressing challenges associated with adherence and persistence to daily oral PrEP. The ImPrEP CAB Brasil study aims to generate evidence to inform national policies about long acting cabotegravir (CAB-LA) PrEP implementation within public health PrEP services in Brazil. Methods: Study intervention consisted of person-centered choice of same-day delivery of oral TDF/FTC PrEP or CAB-LA (The Choice Cohort) for PrEP-naïve cis-MSM, non-binary and trans persons aged 18-30 years. Participants were enrolled from October 17, 2023 to October 31, 2024 and will be followed for 48-weeks, with the option to switching during follow-up. As comparison group, we assessed PrEP-naïve persons with the same demographics who initiated oral PrEP during the study period through the Brazilian public health system at ImPrEP clinics. PrEP coverage was defined as the proportion of persons covered by oral PrEP or CAB-LA during follow-up. We used pairwise comparisons with Bonferroni correction for PrEP coverage. We described injection visit coverage and HIV incidence. Results: Of 1,447 participants enrolled in The Choice Cohort, 83% (N=1,200) chose CAB-LA. Most were cis-MSM (91%), 42% aged 18-24, 60% non-White. A total of 3,744 CAB-LA injections were administered, 95.7% (n=3,583/3,744) delivered on time (+/-7days|) and 29 persons (2.4%; n=29/1,200) had at least one reload. Among persons using CAB-LA, 4% (n=48/1200) were lost to follow-up, 20.8% (n=10/48) of these received only the first injection. To date, 47 (3.2%) participants switched regimens, 26 from CAB-LA to oral PrEP and 21 from oral PrEP to CAB-LA. There were 8 seroconversions in 408.52 person-years of follow-up in the comparison group (incidence rate 1.96 [95%CI 0.98-3.92] per 100 person-years) and no seroconversions in 798.4 person-years in The Choice Cohort. A total of 2,263 persons initiated oral PrEP in the comparison group. PrEP coverage in The Choice Cohort was 96.2% for CAB-LA arm and 64.1% for oral PrEP arm, and 47.4% for the comparison group (Figure). Pairwise comparisons of coverage indicated differences between: CAB-LA vs oral PrEP, CAB-LA

vs comparison group, and oral PrEP vs comparison group (p<0.0001 for all comparisons). Conclusions: CAB-LA significantly improved PrEP coverage and protection, showing promise in addressing adherence challenges to daily oral PrEP, particularly among young key populations. Injection visit coverage was high and consistent during follow-up.

Oral Abstracts

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Estimation of Prevention-Effective CAB-LA Concentrations Among MSM/ TGW in HPTN 083 Brett S. Hanscom 1 , Mark A. Marzinke 2 , Robert R. Bies 3 , Deborah J. Donnell 1 , Craig Hendrix 2 , Xinnong Li 3 , Zhe Wang 1 , Carolina Acuipil 4 , Alex Rinehart 5 , James F. Rooney 6 , Lydia Soto-Torres 7 , Marybeth McCauley 8 , Beatriz Grinsztejn 9 , Raphael J. Landovitz 10 1 Fred Hutchinson Cancer Center, Seattle, WA, USA, 2 The Johns Hopkins University School of Medicine, Baltimore, MD, USA, 3 University at Buffalo, Buffalo, NY, USA, 4 ViiV Healthcare, Brentford, UK, 5 ViiV Healthcare, Durham, NC, USA, 6 Gilead Sciences, Inc, Foster City, CA, USA, 7 Division of AIDS, Bethesda, MD, USA, 8 Family Health International 360, Durham, NC, USA, 9 Institute de Pesquisa Clinica Evandro Chagas, Rio de Janeiro, Brazil, 10 University of California Los Angeles, Los Angeles, CA, USA Background: HIV Prevention Trials Network (HPTN) 083 Trial was a randomized controlled trial that demonstrated the superiority of long-acting injectable cabotegravir (CAB-LA) over daily oral TDF/FTC for HIV PrEP among cisgender men and transgender women who have sex with men. The threshold of plasma CAB concentrations ([CAB]) needed for HIV protection in humans is difficult to define due to limited numbers of incident infections, unknown HIV-exposure timing, and unknown [CAB] at HIV exposure. A nested case-control study was conducted among HPTN 083 participants randomized to the CAB arm to investigate the association between plasma [CAB] and HIV protection. Methods: For each of the 25 CAB-arm participants with confirmed HIV during the randomized blinded study and the first year post-unblinding, four matched, HIV-negative controls were randomly selected; matching was based on region, gender identity, race, and duration of follow-up. Plasma [CAB] was assessed throughout follow-up, and a multicompartment PK model was used to estimate [CAB] concentration-time profiles. The analysis window for each case and their matched controls was defined as the time between the last-negative HIV test and the first-positive HIV test visits for HIV-positive cases, i.e., the period when HIV acquisition likely occurred. All participants were classified according to whether their minimum concentrations during the analysis window fell within [CAB] strata bounded by the protein adjusted inhibitory concentration 1x PA-IC 90 and 4x PA-IC 90 . Conditional logistic regression was used to estimate the association between [CAB] and risk of HIV infection. Results: During the analysis window, minimum plasma [CAB] was below 1x PA-IC 90 for 64% of confirmed HIV cases, and above 4x PA-IC 90 in 76% of matched controls (Table). Minimum [CAB] above the 4x PA-IC 90 was associated with a 93% (95%CI: 77%, 98%) reduction in risk of HIV acquisition compared to participants with a minimum [CAB] < 1x PA-IC 90 . A minimum [CAB] between 1x and 4x had an estimated risk reduction of 79% (95% CI: -20%, 96%). Conclusions: Plasma [CAB] above 4x PA-IC 90 is estimated to provide >90% protection against HIV acquisition, consistent with the target C τ for the selected dose derived from non-human primate models. Data are insufficient for a precise estimate for plasma [CAB] between 1x and 4x PA-IC 90 . Q2M dosing has been shown to achieve [CAB] above 4x PA-IC 90 . Novel formulations, dosing, and time-to-protection estimates may be informed by these results.

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CROI 2025