CROI 2025 Abstract eBook

Abstract eBook

Poster Abstracts

708

A Strategy for Durable AAV-Vectored bNAb Expression in Adult Rhesus Macaques Michael Kuipa, Peter Koroma, Isai Leguizamo, Priya Dhole, Matthew R. Gardner Emory University, Atlanta, GA, USA Background: Sustained expression of adeno-associated virus (AAV)-vectored anti-HIV-1 broadly neutralizing antibodies (bNAbs) could prevent and treat HIV-1 infection. However, durable expression of AAV-vectored bNAbs in vivo is limited by host immune responses, impeding efficacy studies in preclinical nonhuman primate (NHP) models. Programmed cell death protein (PD)-1 is an immune checkpoint protein on T cells that inhibits T-cell activity upon binding to programmed cell death protein ligand (PD-L)1. We hypothesized that PD-L1 co-expression on AAV.bNAb-transduced cells maintains bNAb expression by suppressing host anti-bNAb antibodies and T-cell responses. The goal of this research is to develop a model for prolonged AAV-vectored bNAb production in NHPs and possibly advance AAV-delivery of bNAbs for human clinical trials. Methods: Five groups of six rhesus macaques each received the following vectors: 1) AAV9.PD-L1; 2) AAV9.10-1074; 3) AAV9.PD-L1 and AAV9.10-1074; 4) AAV9.3BNC117; and 5) AAV9.PD-L1 and AAV9.3BNC117. Serum antibody concentrations were determined by gp120 ELISA and B and T cell reactivity were assessed by anti-drug antibody ELISA and by ELISpot assay, respectively. Beginning at 20- or 30-weeks post AAV9 administration, all animals were challenged biweekly via low-dose, intrarectal challenge using SHIV-AD8. Protection from SHIV challenge was determined by monitoring plasma viremia by qPCR. Additionally, to assess the safety of our approach, we have ongoing studies to determine the immunomodulatory effect of AAV9.PD-L1 in PBMCs by RNASeq and off-target AAV transduction by ddPCR post necropsy. Results: All six macaques that received AAV9.10-1074 and AAV9.PD-L1 had sustained concentrations of 10-1074 throughout the study compared to four of six macaques that only received AAV.10-1074. Similarly, five of six macaques that received AAV9.3BNC117 and AAV9.PD-L1 compared to three of six macaques that only received AAV9.3BNC117 had sustained expression of 3BNC117. We observed a negative correlation between bNAb serum titers and both host anti-bNAb antibodies and T cell reactivity. All macaques that achieved sustained expression of 10-1074 were significantly protected from SHIV challenges. Macaques that received AAV9.3BNC117 and AAV9.PD-L1 were significantly protected against SHIV challenge. Conclusions: We have developed a strategy for sustained bNAb expression in NHPs. This will allow the prophylactic and therapeutic efficacy of AAV-delivered bNAbs to be studied in preclinical NHP models. Trosunilimab Safety, Pharmacokinetics, and Pharmacodynamics in People With and Without HIV-1 Manal Abunimeh 1 , Cynthia Brinson 2 , Olayemi Osiyemi 3 , Ana Pires 1 , Mong-Jen Chen 1 , Preethi Krishnan 1 , Franco Antonio Felizarta 4 , Harsh Sharthiya 1 , Heide Betman 1 , Nael Mostafa 1 , Veronica Wangsadipura 1 , Daniel Cohen 1 , Moti Ramgopal 5 1 AbbVie, Inc, North Chicago, IL, USA, 2 Central Texas Clinical Research, Austin, TX, USA, 3 Triple O Research Institute, West Palm Beach, FL, USA, 4 Private Practice, Bakersfield, CA, USA, 5 Midway Immunology and Research Center, Fort Pierce, FL, USA Background: ART-free HIV viral control remains an unmet need for people with HIV (PWH). Trosunilimab, an anti-α4β7 integrin antibody with preserved Fc functionality, is expected to induce immune responses to control viral replication, and was evaluated in a phase 1 program in healthy volunteers (HV) and PWH. Methods: The double-blind, placebo (PBO) controlled phase 1 studies evaluated single-ascending doses (SAD) ranging from 50 to 1800 mg IV, and 800 mg SC in healthy volunteers (Study M19-968) and 800 mg and 1600 mg IV (SAD) in viremic PWH off ART (Part A) and multiple ascending doses of 800 mg IV and SC and 1600 mg IV in aviremic PWH on ART (Part B) (Study M19-966). Safety analysis included adverse events (AEs) and lab abnormalities. Pharmacodynamic (PD) analysis included α4β7 integrin receptor target engagement. α4β7 integrin expression on HIV virion was assessed in viremic PWH. Results: In M19-968, 55 HV received either trosunilimab or PBO. In M19-966, 9 participants received trosunilimab in Part A, and 45 received either trosunilimab or PBO in Part B. Demographics of PWH are reported in Table 1. In M19-966 Part A, no subject had significant sustained decline in HIV RNA (>0.5 Log 10) in the absence of ART. No serious AEs or drug-related AEs Grade ≥3 or leading to discontinuation of study drug occurred in either study and the frequency of drug-related AEs was low. One HV (1800 mg IV dose) had drug-related elevated

an integrase strand transfer inhibitor dolutegravir (DTG), was incorporated into the same formulation using co-solvent optimization. The pharmacokinetics of developed formulations were evaluated in BALB/c mice, and the pre-clinical efficacy of HIV suppression was assessed in humanized mice. Results: The DOR-ISFI delivered DOR plasma concentrations >10×IC95 for 140 days and efficiently protected against multiple vaginal HIV challenges in humanized mice. The two-drug formulation DTGDOR-ISFI co-delivered DTG and DOR in serum for 9 months above the IC90. Drugs penetrated tissues relevant for HIV infection including lymph nodes, brain, spleen, gut, and genital tracts of male and female humanized mice. During preclinical evaluation of HIV maintenance therapy, this DTGDOR-ISFI effectively suppressed HIV for at least 4 weeks after discontinuation of antiretroviral therapy (ART). Removal of the implant successfully stopped the delivery of both drugs. Conclusions: DTGDOR-ISFI is an important advance in managing HIV suppression by reducing the number of injections and simplifying LA drug delivery. Identification and Characterization of Novel Chemical Scaffolds With Anti-HIV Activities Ryan Jeep 1 , Liangqun Huang 1 , Tram A. Ngo 2 , Fu-Yue Zeng 2 , James Boehlke 1 , Luke Bennett 1 , Ian Pass 2 , Ashootosh Tripathi 3 , Pamela Schultz 3 , Pankaj Kumar 3 , Thomas D. Y. Chung 2 , David H. Sherman 3 , Chaoping Chen 1 1 Colorado State University, Fort Collins, CO, USA, 2 Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA, 3 University of Michigan, Ann Arbor, MI, USA Background: HIV-1 protease (PR) is initially synthesized as part of the Gag-Pol polyprotein precursor, which undergoes regulated autoprocessing to produce free mature PR, essential for viral particle maturation and infectivity. We previously demonstrated that precursors and mature PRs have distinct enzymatic properties, as precursors are up to 1,000-fold less-sensitive to protease inhibitors (PIs) compared to the mature PR. Thus, we established a cell-based functional assay for high-throughput screening (HTS) campaigns targeting precursor autoprocessing in the pursuit of first-in-class drug discovery. Methods: We screened approximately 350,000 small molecule compounds at a single dose (20 µM), along with about 2,000 natural product extracts (NPEs) and subfractions (each containing 5 to 25 diverse chemicals) at ~ 2 µg/ml apparent concentrations. Positive hits were further verified using the primary HTS assay and/or an orthogonal TR-FRET assay. Additionally, we assessed several confirmed hits using a newly established highly sensitive infectivity assay to evaluate their antiretroviral activities against the WT and mutant HIV strains known to be resistant to multiple protease inhibitors (PIs). Results: We identified several small molecule hits and NPE subfractions that exhibited partial activities in the primary HTS assay. The small molecule hits represented four scaffold groups, differing from known FDA-approved PIs. Notably, these confirmed compounds or NPE subfractions suppressed virus infectivity with single digit micromolar EC 50 values. Encouragingly, the top small molecule hit (C7, attached Figure, panel A) and an NPE subfraction (H2_11, attached Figure, panel B) showed comparable potency against WT and multi-PI resistant mutants, suggesting that these hit compounds may inhibit HIV-1 PR through mechanisms different from those of current PIs. Conclusions: This study establishes the feasibility of discovering novel autoprocessing inhibitors through HTS using a cell-based functional assay. The validated hits seemed to operate through mechanisms distinct from existing PIs, presenting a new treatment strategy for targeting a vital enzyme (HIV-1 PR) at two distinct functional states (precursor and mature PR), thereby addressing drug resistance challenges.

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Poster Abstracts

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CROI 2025 203