American Association for Cancer Research
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10780432ccr194110-sup-234180_2_supp_data_6318385_qmy570.docx (22.83 MB)

Supplementary Data from Anti–PD-1 Induces M1 Polarization in the Glioma Microenvironment and Exerts Therapeutic Efficacy in the Absence of CD8 Cytotoxic T Cells

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posted on 2023-03-31, 22:13 authored by Ganesh Rao, Khatri Latha, Martina Ott, Aria Sabbagh, Anantha Marisetty, Xiaoyang Ling, Daniel Zamler, Tiffany A. Doucette, Yuhui Yang, Ling-Yuan Kong, Jun Wei, Gregory N. Fuller, Fernando Benavides, Adam M. Sonabend, James Long, Shulin Li, Michael Curran, Amy B. Heimberger

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ARTICLE ABSTRACT

Anti-programmed cell death protein 1 (PD-1) therapy has demonstrated inconsistent therapeutic results in patients with glioblastoma (GBM) including those with profound impairments in CD8 T-cell effector responses. We ablated the CD8α gene in BL6 mice and intercrossed them with Ntv-a mice to determine how CD8 T cells affect malignant progression in forming endogenous gliomas. Tumor-bearing mice were treated with PD-1 to determine the efficacy of this treatment in the absence of T cells. The tumor microenvironment of treated and control mice was analyzed by IHC and FACS. We observed a survival benefit in immunocompetent mice with endogenously arising intracranial glioblastomas after intravenous administration of anti–PD-1. The therapeutic effect of PD-1 administration persisted in mice even after genetic ablation of the CD8 gene (CD8−/−). CD11b+ and Iba1+ monocytes and macrophages were enriched in the glioma microenvironment of the CD8−/− mice. The macrophages and microglia assumed a proinflammatory M1 response signature in the setting of anti–PD-1 blockade through the elimination of PD-1–expressing macrophages and microglia in the tumor microenvironment. Anti–PD-1 can inhibit the proliferation of and induce apoptosis of microglia through antibody-dependent cellular cytotoxicity, as fluorescently labeled anti–PD-1 was shown to gain direct access to the glioma microenvironment. Our results show that the therapeutic effect of anti–PD-1 blockade in GBM may be mediated by the innate immune system, rather than by CD8 T cells. Anti–PD-1 immunologically modulates innate immunity in the glioma microenvironment—likely a key mode of activity.