CROI 2025 Abstract eBook

Abstract eBook

Poster Abstracts

Results: With this HLA-A allele-specific BLT humanized mice, we found the in vivo half-life of TCRm ScDb post IP injection was 3.9 hrs, peaking at 2.4 ug/ml. TCRm ScDb was well tolerated in BLT hu-mice with stable bodyweight. TCRm ScDb HI12 added to early cART achieved suppression quicker than the H2 control group. CD38+HLA-DR+ double positive population was significantly elevated in CD4+ and CD8+ T cells during the HI12 treatment period. Intact (P=0.026), 3’ defective (p=0.002), and total (p=0.007) HIV proviruses in splenocytes were significantly decreased post HI12 treatment, whereas the 5’ (p=0.295) defective proviruses did not show a significant decrease. In an independent experiment, the viral rebound time was significantly delayed (p=0.0026) in HI12 treated animals over H2 control treated ones. Conclusions: Using HLA-A matched BLT mice, the addition of TCRm ScDb targeting Pol epitope in corresponding HLA complexes during early ART increased T cell immune activation and reduced the intact provirus burden on ART resulting in a delay of viral rebound after cART interruption. The use of TCRm ScDb strategies warrants further clinical studies towards HIV cure. Targeting TCF-1 to Potentiate the Functional Capacity of HIV/SIV-Specific CD8+ T Cells Hiroshi Takata 1 , Benjamin D. Varco-Merth 1 , Shelby Hoffmeister 1 , Paula Armitage 1 , Lydie Trautmann 2 , Afam Okoye 1 1 Oregon Health and Science University, Portland, OR, USA, 2 Henry M Jackson Foundation, Bethesda, MD, USA Background: The transcription factor T cell factor 1 (TCF-1) plays a critical role in maintaining functional memory CD8 + T cells and regulation of their proliferation capacity. TCF-1 expression in HIV-specific CD8 + T cells has been associated with viral control and may be important for promoting the functional activity of HIV-specific CD8 + T cells. Glycogen synthase kinase-3 (GSK-3) inhibitors prevent the degradation of β-catenin, which promotes TCF-1 expression and its transcriptional activity. In this study, we asked whether GSK-3 inhibitors can be used to induce TCF-1 expression in antiviral CD8 + T cells. Methods: TCF-1 expression in SIV-specific CD8 + T cells from 5 SIV-infected rhesus macaques (RM) with pVL between 1,700-170,000 SIV RNA copies/mL and 7 SIV controllers (pVL < 15 SIV RNA copies/mL) were assessed by flow cytometry. CD8 + T cells from humans (n=13) and RM (n=21) were treated with 5 different GSK-3 inhibitors (BIO, CHIR99021, TWS119, Li 2 CO 3 , and LY2090314) for 16 hours to evaluate their potential to induce TCF-1 expression. PBMC from 5 SIV-infected RM on ART were treated with LY2090314 for 16 hours, followed by culture with IL-7 (50ng/mL) for 6 days to assess expansion of Mamu*A01 immunodominant Gag-CM9- and Tat-SL8-specific CD8 + T cells. Results: TCF-1 expression was significantly higher in SIV-specific CD8 + T cells of controller RM compared with viremic RM (p=0.04), confirming data from human studies. Among the five GSK-3 inhibitors tested, LY2090314 induced the highest expression of TCF-1 in CD8 + T cells from humans ( Figure 1A ) and RM after overnight exposure. LY2090314 also induced TCF-1 expression in SIV-specific CD8 + T cells compared with DMSO control (p=0.004). To determine whether TCF-1 induction by LY2090314 can enhance the expansion of antigen specific CD8 + T cells, PBMCs from SIV-infected RM on ART were cultured with IL-7 after LY2090314 exposure. After 6 days of culture, we observed an enrichment of total CD8 + central memory (TCM) (p=0.008) and Gag-CM9- and Tat-SL8-specific CD8 + T CM (p=0.008) ( Figure 1B ) compared with DMSO+IL-7 alone. Conclusions: These data suggest that GSK-3 inhibitors can be used to induce TCF-1 in CD8 + T cells in both human and RM. In addition, LY2090314 was able to induce TCF-1 expression in SIV-specific CD8 + T cells of RM on ART. These data support the further evaluation of LY2090314 in SIV-infected RM on ART to determine whether TCF-1 induction can enhance the functional activity of CD8 + T cells and promote durable virologic control. The figure, table, or graphic for this abstract has been removed. CD4 T Cell-Targeting Lipid Nanoparticles in the Search for a Genetic HIV Cure Maaike De Cock 1 , Wojciech Witkowski 1 , Sarah Gerlo 1 , Bruno De Geest 2 , Linos Vandekerckhove 1 , Jolien Van Cleemput 1 , for the HIV Cure Research Center 1 HIV Cure Research Center, Ghent University, Ghent, Belgium, 2 Ghent University, Ghent, Belgium Background: Insights gained from successfully treated individuals demonstrate that a definite HIV cure must purge the replication-competent The figure, table, or graphic for this abstract has been removed.

HIV reservoir, whilst making CD4+ cells resistant to HIV reinfection. Due to its versatility, the CRISPR-Cas9 genome editing tool holds great potential to eliminate latent proviral DNA and mutate the viral co-receptor CCR5. Still, its safety and effectiveness are hindered by the lack of precise delivery to infected cells. Here, we present CD4-targeted lipid nanoparticles (LNPs) for CRISPR-Cas9 delivery to achieve viral excision and CCR5 knockout with greater efficacy and precision. Methods: As primary human CD4 T cells do not readily take up cargo, we first optimized T cell mRNA transfection efficiency. First, we screened a LNP library to identify a lipid formulation with optimal properties including particle size, surface charge and mRNA encapsulation efficacy. Selected LNPs were then administered to various primary and immortalized T cells to select LNPs that efficiently bind and transfect T cells. In order to target this optimal LNP to HIV susceptible cells, we conjugated it to anti-CD4 nanobodies using biorthogonal click chemistry. Finally, we packaged sgRNA and Cas9 mRNA into our optimal LNP formulation and delivered it to T cells. We designed sgRNAs for CCR5 and LTR, to genetically edit the viral co-receptor in SupT1 cells, and to achieve viral excision in J-Lat 10.6 cells, respectively. Results: First, we identified a LNP formulation with optimal physiochemical properties that enabled up to 100% binding to and transfection of SupT1, Jurkat and J-Lat 10.6 cells. Moreover, we showed up to 95% transfection of activated, and up to 25% of non-activated primary human CD4 T cells. Interestingly, conjugating the optimal LNP to anti-CD4 nanobodies enhanced the binding to primary human CD4 cells with ten-fold, compared to LNP alone. Next, our results showed successful gene editing in T cell lines. These CRISPR LNPs were able to mutate CCR5 in SupT1 cells, with an indel (insertion and deletion) frequency of 46%. Lastly, delivery of LTR CRISPR LNPs to J-Lat 10.6 cells resulted in up to 100% proviral excision and up to 80% indels in the HIV LTR. Conclusions: Our results, demonstrating successful gene editing of the CCR5 co-receptor along with full-length provirus excision through targeted LNP delivery, provide proof of concept for CD4-targeted CRISPR LNPs as a genetic cure for HIV.

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CD4 Mimetics Sensitize HIV-Infected Cells to ADCC Mediated by Plasma From Early-Stage HIV Infection Andrés Finzi 1 , Alexandra Tauzin 1 , Delia Pinto-Santini 2 , Sayan Dasgupta 2 , Derek Yang 3 , William D. Tolbert 4 , Myriam Verly 1 , Marzena Pazgier 4 , Javier R. Lama 5 , Amos B. Smith III 3 , Shilei Ding 1 , Ann Duerr 2 1 Centre de Recherche du CHUM, Montreal, Canada, 2 Fred Hutchinson Cancer Center, Seattle, WA, USA, 3 University of Pennsylvania, Philadelphia, PA, USA, 4 Uniformed Services University of the Health Sciences, Bethesda, MD, USA, 5 Asociacion Civil Impacta Salud y Educacion, Lima, Peru Background: The HIV-1 reservoir in long lived memory CD4+ cells is the main obstacle for a cure and is established in the early stages of infection. Some strategies being developed to target the reservoir rely on rendering HIV-1 envelope glycoproteins (Env) visible to the immune system. Small molecule CD4 mimetics (CD4mcs) expose vulnerable Env epitopes which can be targeted by non-neutralizing antibodies (nnAbs) that are abundant in the plasma of people with HIV (PWH) and can mediate antibody-dependent cellular cytotoxicity (ADCC). Treatment with CD4mcs in combination with plasma from PWH or nnAbs efficiently reduces the size of HIV reservoir and postpones viral rebound upon ART interruption in humanized mice. However, it remains unclear when these nnAbs are elicited after HIV infection.

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