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Mostböck S, Wu HH, Fenn T, Riegler B, Strahlhofer S, Huang Y, Hansen G, Kroe-Barrett R, Tirapu I, Vogt AB. Distinct immune stimulatory effects of anti-human VISTA antibodies are determined by Fc-receptor interaction. Front Immunol 2022; 13:862757. [PMID: 35967294 PMCID: PMC9367637 DOI: 10.3389/fimmu.2022.862757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Accepted: 07/01/2022] [Indexed: 11/13/2022] Open
Abstract
VISTA (PD-1H) is an immune regulatory molecule considered part of the next wave of immuno-oncology targets. VISTA is an immunoglobulin (Ig) superfamily cell surface molecule mainly expressed on myeloid cells, and to some extent on NK cells and T cells. In previous preclinical studies, some VISTA-targeting antibodies provided immune inhibitory signals, while other antibodies triggered immune stimulatory signals. Importantly, for therapeutic antibodies, the isotype backbone can have a strong impact on antibody function. To elucidate the mode of action of immune stimulatory anti-VISTA antibodies, we studied three different anti-human VISTA antibody clones, each on three different IgG isotypes currently used for therapeutic antibodies: unaltered IgG1 (IgG1-WT), IgG1-KO (IgG1-LL234,235AA-variant with reduced Fc-effector function), and IgG4-Pro (IgG4- S228P-variant with stabilized hinge region). Antibody functionality was analysed in mixed leukocyte reaction (MLR) of human peripheral blood mononuclear cells (PBMCs), as a model system for ongoing immune reactions, on unstimulated human PBMCs, as a model system for a resting immune system, and also on acute myeloid leukemia (AML) patient samples to evaluate anti-VISTA antibody effects on primary tumor material. The functions of three anti-human VISTA antibodies were determined by their IgG isotype backbones. An MLR of healthy donor PBMCs was effectively augmented by anti-VISTA-IgG4-Pro and anti-VISTA-IgG1-WT antibodies, as indicated by increased levels of cytokines, T cell activation markers and T cell proliferation. However, in a culture of unstimulated PBMCs of single healthy donors, only anti-VISTA-IgG1-WT antibodies increased the activation marker HLA-DR on resting myeloid cells, and chemokine levels. Interestingly, interactions with different Fc-receptors were required for these effects, namely CD64 for augmentation of MLR, and CD16 for activation of resting myeloid cells. Furthermore, anti-VISTA-IgG1-KO antibodies had nearly no impact in any model system. Similarly, in AML patient samples, anti-VISTA-antibody on IgG4-Pro backbone, but not on IgG1-KO backbone, increased interactions, as a novel readout of activity, between immune cells and CD34+ AML cancer cells. In conclusion, the immune stimulatory effects of antagonistic anti-VISTA antibodies are defined by the antibody isotype and interaction with different Fc-gamma-receptors, highlighting the importance of understanding these interactions when designing immune stimulatory antibody therapeutics for immuno-oncology applications.
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Affiliation(s)
- Sven Mostböck
- Cancer Immunology and Immune Modulation, Boehringer Ingelheim RCV GmbH & Co KG, Vienna, Austria
- *Correspondence: Sven Mostböck,
| | - Helen Haixia Wu
- Biotherapeutics Discovery, Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, CT, United States
| | - Timothy Fenn
- Biotherapeutics Discovery, Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, CT, United States
| | - Bettina Riegler
- Cancer Immunology and Immune Modulation, Boehringer Ingelheim RCV GmbH & Co KG, Vienna, Austria
| | - Susanne Strahlhofer
- Cancer Immunology and Immune Modulation, Boehringer Ingelheim RCV GmbH & Co KG, Vienna, Austria
| | - Yining Huang
- Biotherapeutics Discovery, Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, CT, United States
| | - Gale Hansen
- Biotherapeutics Discovery, Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, CT, United States
| | - Rachel Kroe-Barrett
- Biotherapeutics Discovery, Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, CT, United States
| | - Iñigo Tirapu
- Cancer Immunology and Immune Modulation, Boehringer Ingelheim RCV GmbH & Co KG, Vienna, Austria
| | - Anne B. Vogt
- Cancer Immunology and Immune Modulation, Boehringer Ingelheim RCV GmbH & Co KG, Vienna, Austria
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