CROI 2024 Abstract eBook

Abstract eBook

Poster Abstracts

Methods: A panel of 4-1BB costimulated CAR T cells expressing 18 distinct bNAb-based CARs were generated against all well-characterized epitopes on HIV Env: V1/V2 apex, V3-glycan supersite, CD4 binding site, gp120-gp41 interface, fusion peptide, silent face, and MPER. CAR T products manufactured from primary human T cells were screened for potency via degranulation when cocultured with Env-expressing K562 (K.Env) cells, as well as K.Env killing assays and HIV suppression assays in the GXR25 cell line using the Incucyte SX5 live-cell imaging system. To map escape pathways and determine CAR efficacy, donor-matched CAR T products were adoptively transferred into HIV-infected, BLT humanized mice. CAR expansion and HIV viral loads were monitored weekly in the blood by flow cytometry and qRT-PCR, and HIV env sequences were amplified from plasma at >6-weeks post infection using nested PCR and deep sequenced to identify putative escape mutations. Results: Potency hierarchy, as measured by degranulation potential, K.Env killing kinetics, and effective suppression of virus replication in vitro was heterogeneous among bNAb CAR constructs, but clustered between epitope specificities. Notably, Env epitopes most distal (V1/V2 apex, V3-glycan supersite) from the plasma membrane were associated with greater killing potency. Deep sequencing of HIV env derived from bNAb CAR T-treated HIV-infected humanized mice identified bNAb CARs with overlapping versus orthogonal associated escape pathways. This data guided the design of bNAb CAR combinations hypothesized to restrict escape. Using this approach, we demonstrate that a triple combination of V1/V2 apex, V3-glycan supersite, and CD4 binding site-directed CARs were able to durably suppress acute viremia to undetectable levels in humanized mice. Conclusion: Distinct in vitro assays identified bNAb CARs with superior potency (PGT128, PGDM1400). HIV escape from individual bNAb CARs can be restricted when CARs associated with orthogonal escape pathways are combined, and restriction of HIV escape leads to durable suppression of HIV replication in vivo. Vaccination Combined With PD-1 Blockade Provides Sustained SIV Suppression in Mamu-A01(+) Macaques Bhrugu Yagnik 1 , Sheikh A. Rahman 1 , Sailaja Gangadhara 1 , Shan Liang 1 , Gordon Freeman 2 , Rafi Ahmed 3 , Rama R. Amara 1 1 Emory University, Atlanta, GA, USA, 2 Harvard Medical School, Boston, MA, USA, 3 Emory Vaccine Center, Atlanta, GA, USA Background: Dysfunctional T cells and persistent viral reservoir under anti retroviral therapy (ART) are the two major challenges to HIV cure. Towards this, here we evaluated therapeutic potential of intramuscular (IM) or intravenous (IV) vaccination combined with a latency reversal agent (LRA) and PD-1 blockade in SIV infected macaques. Methods: A total of 28 RMs were infected with SIVmac251, placed on daily ART at 2 weeks post infection (wpi) and divided into three groups. Two groups received two DNA/SIV vaccinations (34, 40 wpi; ID) followed by two modified vaccinia Ankara (MVA)/SIV vaccines (46, 66 wpi) via either IM (MVA-IM, n=14) or IV (MVA-IV, n=7), and the third group did not receive any vaccination (ART, n=7). All RMs received five weekly IV infusions of AZD5582 from weeks 52 to 56 under ART as an LRA after the 1st MVA. On the day of ATI (75 wpi), 7 RMs from MVA-IM group received six infusions of a primatized anti-PD-1 antibody (10mg/ kg body wt.) at three-week intervals (MVA-IM+PD-1). Viral rebound kinetics were studied for up to 32 weeks post ATI. In-depth immunological, virological, and reservoir analyses were performed throughout the study. Results: Both IM and IV routes of therapeutic vaccination generated broad and polyfunctional SIV specific CD4 and CD8 T cells in blood and lymph nodes. Surprisingly, administration of AZD5582 under ART led to a significant loss of vaccine-induced effector CD8 T cells but were restored to high frequencies following the 2nd MVA. Post ATI, all animals showed a strong viral rebound. The ART, MVA-IM and MVA-IV animals, irrespective of Mamu-A01 status, did not control rebounding viremia. However, anti-PD-1 Ab treated Mamu-A01(+) animals (n=4) showed a profound suppression (below 60 copies with small blips under 1000 copies/ml) of reemerging viremia up to 32 weeks post ATI. The PD-1 blockade also induced high frequencies of polyfunctional SIV-specific cytolytic (granzyme B+, perforin+) CD8 T cells in the T-cell zone and B cell follicles of LNs, which were associated with sustained viral control. Conclusion: A combination of vaccination during ART and PD-1 blockade post ATI can achieve a sustained functional cure for SIV in the presence of a potent anti-viral CD8 T cell response. These results also highlight the need for optimization of AZD5582 treatments in conjunction with vaccination to prevent the loss of vaccine-induced CD8 T cells.

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The Impact of HIV Cure-Related Study Drugs and Treatment Interruption on Viral Resuppression Rates Ming J Lee 1 , Miles Eason 1 , Antonella Castagna 2 , Laura Galli 3 , Marie-Angélique De Scheerder 4 , James L. Riley 5 , Pablo Tebas 5 , Jesper D. Gunst 6 , Ole S. Søgaard 6 , Eric Florence 7 , Eugene Kroon 8 , Mark S. de Souza 8 , Beatriz Mothe 9 , Marina Caskey 10 , Sarah Fidler 1 1 Imperial College London, London, United Kingdom, 2 San Raffaele Vita-Salute University, Milan, Italy, 3 San Raffaele Scientific Institute, Milan, Italy, 4 Ghent University, Ghent, Belgium, 5 University of Pennsylvania, Philadelphia, PA, USA, 6 Aarhus University Hospital, Aarhus, Denmark, 7 Institute of Tropical Medicine, Antwerp, Belgium, 8 SEARCH, Bangkok, Thailand, 9 IrsiCaixa Institute for AIDS Research, Badalona, Spain, 10 The Rockefeller University, New York, NY, USA Background: To assess the effectiveness of novel HIV curative strategies, "cure" trials require periods of closely monitored antiretroviral therapy (ART) analytical treatment interruptions (ATI). We performed a systematic review and meta-analysis to identify the impact of ATI with or without novel therapeutics in cure-related studies on the time to viral resuppression following ART restart. Methods: Medline and Embase databases were searched for human studies involving ATIs from January 2015 to March 2023. The primary outcome was proportion of participants who experienced viral resuppression (plasma HIV viral load (VL) <50 copies/mL) by 12 weeks post-ATI, stratified by receipt of interventional drug with ATI (IA) or ATI-only groups. A random-effects proportional meta-analysis and multivariable Cox proportional hazards analysis were performed using R. Results: Of 1049 studies screened, 12 were relevant with available data and included in the analysis (n=180 participants). 96% of participants achieved viral suppression within 12 weeks (95% confidence interval (CI): 83% - 99%), with no difference between ATI-only and IA subgroups (97% vs 96%, p=0·79) (Figure 1). In the adjusted time-to-event analysis, age (adjusted Hazard Ratio (aHR) 0·97, 95%CI 0·96 – 0·99, p < 0·001), greater VL at ART restart (aHR 0·47, 95%CI 0·38 – 0·59, p<0·001), use of protease inhibitors (aHR 0·34, p= 0·19 – 0·73, p = 0·004), duration of ATI (aHR 0·96, 95%CI 0·94 – 0·98), and longer intervals between HIV VL monitoring (aHR 0·66, 95%CI 0·59 – 0·74, p<0·001) were associated with a decreased likelihood over time of achieving viral suppression after restarting ART, but not receipt of trial interventions (HR 0·89, 95%CI 0·57 – 1·40, p=0·612). Conclusion: 96% of study participants who underwent ATIs achieved viral suppression by 12 weeks after restarting ART and this outcome did not differ with or without the receipt of any interventional drugs. When designing studies involving ATIs, time to viral resuppression after restarting ART should be regularly monitored and reported, to assess the impact and safety of specific trial interventions in ATI studies. The figure, table, or graphic for this abstract has been removed. Blockade of IFN-beta Reactivates HIV Reservoir in ART-Suppressed HIV-Infected BLT Humanized Mice Zhe Yuan 1 , Emmanouil Papasavvas 1 , Guorui Zu 1 , Lily Lu 1 , Matthew Fair 1 , Samuel Keller 2 , Luca Sardo 2 , Guoxin Wu 2 , Joel Cassel 1 , Joseph Salvino 1 , Pau Zuck 2 , Bonnie Howell 2 , Luis J. Monataner 1 1 Wistar Institute, Philadelphia, PA, USA, 2 Merck & Co, Inc, Kenilworth, NJ, USA Background: Despite the efficient suppression of HIV-1 replication can be achieved with combined antiretroviral therapy (cART), viral latency and low levels of type I interferon (IFN-I) signaling persist during chronic infection. This sustained signaling may promote T cell exhaustion and foster viral persistence. Using cloned human neutralizing antibodies specifically against IFNα or IFNβ, here we test the effects of blocking IFNα or IFNβ in ART suppressed BLT humanized mice to determine the role each Type I IFN in suppression. Methods: Antibodies used for infusions against IFNα or IFNβ were characterized by ELISA, STAT-1 phosphorylation, dimerization assay, and western blot to

Poster Abstracts

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CROI 2024 141