CROI 2019 Abstract eBook

Abstract eBook

Poster Abstracts

in both groups 2) between day 2 and day 5, the rate of virus decay remained the same 3) plasma virus decay was independent of FcgRIII genotype. Pharmacokinetic analysis confirmed that during this period, both groups maintained serum antibody titers at ten-fold excess of the in vitro IC80 for SHIV SF162P3 neutralization, with higher serum concentrations for the LS-LALA antibody. Further, unlike the LA-LALA antibody, the LS-DEL antibody was able to engage natural killer cells as well as monocytes in vivo through interactions with FcgR. Conclusion: Increased or decreased Fc-effector function did not affect the timing or rate of plasma virus decay in vivo, highlighting that initial impact on plasma viremia by passive mAb therapy with VRC07-523-LS is predominantly mediated by virus neutralization rather than ADCC or phagocytosis. Measurements of decay of infected cell load and functionality of mAb-bound cells are ongoing.

V1/V2 bnAbs, resulted in coverage of up to 100% reservoir isolates for infected cell binding. Conclusion: We observed substantial heterogeneity in binding, ADCC and neutralization profiles of each bNAb to reactivated reservoir viruses. While we observed overall significant correlations between each of the functions tested, these were not always detected in terms of individual antibodies. Further study of this complexity may help guide the development of polyfunctional bNAb therapeutics. 359 MULTISPECIFIC ANTI-HIV DUOCAR-T CELLS POTENTLY ELIMINATE BNAB- RESISTANT HIV IN VIVO Kim Anthony-Gonda 1 , Ariola Bardhi 2 , Dimiter S. Dimitrov 3 , Weizao Chen 3 , Christina Ochsenbauer 4 , John C. Kappes 4 , Nina C. Flerin 2 , Winfried Krueger 1 , Dina Schneider 1 , Rimas Orentas 1 , Harris Goldstein 2 , Boro Dropulic 1 1 Lentigen, a Miltenyi Biotec Company, Gaithersburg, MD, USA, 2 Albert Einstein College of Medicine, Bronx, NY, USA, 3 National Cancer Institute, Frederick, MD, USA, 4 University of Alabama at Birmingham, Birmingham, AL, USA Background: Adoptive immunotherapy using chimeric antigen receptor gene- modified T cells (CAR-T) has made significant contributions to the treatment of certain B-cell malignancies. Such treatment modalities also show promise for the development of a single treatment for HIV/AIDS and obviating the need for long-term anti-retroviral drug therapy. We hypothesized that HIV-1 based lentiviral vectors encoding chimeric antigen receptors (CAR) targeting multiple highly conserved sites on the HIV-1 envelope glycoprotein (Env) using a two- molecule CAR architecture, termed duoCAR, would facilitate effectual binding of multiple targeting domains while improving CAR potency, breadth, and resistance to HIV-1 infection. Methods: To assess CAR functionality, we adapted a previously described neutralization assay that utilizes replication-competent infectious molecular clones of HIV (IMC) encoding different env genes and a Renilla luciferase reporter (Env-IMC-LucR) to allow for sensitive detection of HIV infection in primary cells to monitor the inhibitory activity of different CARs. Results: We show that transduction with lentiviral vectors encoding multi-specific anti-HIV duoCARs confer primary T cells with the capacity to potently suppress HIV infection in contrast to conventional CAR-T cells while simultaneously protecting them from genetically diverse Env-IMC-LucR viruses in vitro. Furthermore, the genetically modified CAR-T cells also potently suppressed broadly neutralizing antibody (bNAb)-resistant Env-IMC-LucR strains, including a VRC01/3BNC117-resistant virus. Lastly, multi-specific duoCAR-T cells effectively suppressed HIV infection in a humanized intrasplenic NOD/SCID/IL-2Rγ-/- model (hu-spl-PBMC-NSG) infected with VRC01/3BNC117- resistant virus in contrast to control-treated, HIV-infected mice. Conclusion: We conclude that multi-specific duoCAR-T cells are superior to conventional CAR-T cells and are highly efficacious against broad and bNAb-resistant Env-IMC-LucR viruses in vitro and in vivo, respectively. Collectively, our work represents a powerful and universal multi-targeting HIV-1 immunotherapy that has strong implications for a functional cure.

Poster Abstracts

358 RELATIONSHIPS BETWEEN NEUTRALIZATION, BINDING AND ADCC OF BNABs AGAINST RESERVOIR HIV Yanqin Ren 1 , Maria Korom 2 , Ronald Truong 2 , Dora Chan 2 , Szuhan Huang 1 , Colin Kovacs 3 , Erika Benko 3 , Jeffrey T. Safrit 4 , John H. Lee 4 , Hermes Garbán 4 , Rebecca Lynch 2 , R. Brad Jones 1 1 Weill Cornell Medicine, New York, NY, USA, 2 George Washington University, Washington, DC, USA, 3 Maple Leaf Medical Clinic, Toronto, ON, Canada, 4 NantKworks, Culver City, CA, USA Background: HIV-specific broadly neutralizing antibodies (bNAbs), may contribute to the elimination of HIV reservoirs by binding to reactivated cells, targeting them for antibody dependent cell-mediated cytotoxicity or phagocytosis (ADCC/ADCP). Harnessing virus neutralization, along with these functions, will provide additional benefit. Few studies have assessed the activities of bNAbs against viruses reactivated from patient-derived reservoirs. The relationships between neutralizing activity, ADCC function and binding to reservoir virus infected primary CD4+ T cells has not been comprehensively studied. Methods: Quantitative viral outgrowth assays (QVOAs) were performed with CD4+ T cells from participants on long-term ART from a clade B-infected cohort. A panel of 15 bNAbs were tested for binding and ADCC to cells infected with 36 reservoir isolates by flow cytometry, and for neutralizing activity against the same viruses using a TZM-bl assay. ADCC assays were performed with the same viruses, same bNAbs and a haNK cell line (a NantKwest product) as effectors. Results: Considering all bNAbs together, we observed overall correlations between: ADCC and infected cell binding (r=0.49, p<0.0001), neutralization IC80 and binding (r=0.56, p<0.0001), and neutralization IC80 and ADCC (r=0.46, p<0.0001). At the level of individual antibodies: 7/15 bNAbs showed significant correlations between ADCC and infected cell binding, and 10/14 bNAbs showed significant correlations between neutralization and binding. Despite the overall-correlation, we did not observe statistically significant correlations between ADCC and neutralization IC80 for any individual bNAb. PGT121 and 10-1074 showed broad and potent activity for all functions with 66-67% neutralization of reservoir isolates, 42-47% binding, and >15/36 ADCC. PG9 and PGDM1400 showed 22-36% neutralization with intermediate potency, and 72-75% binding; while CD4 binding site bNAbs displayed broader activity but generally lower potencies. Combinations of CD4bs bnAbs with V3-Glycan /

360 LIMITATIONS OF HIV SPECIFIC CAR-T CELLS TO LYSE CELLS BEARING HIV IMMUNE COMPLEXES Matthew T. Ollerton 1 , Edward Berger 2 , Gregory F. Burton 3 , Elizabeth Connick 1

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