| First Author | Rao G | Year | 2020 |
| Journal | Clin Cancer Res | Volume | 26 |
| Issue | 17 | Pages | 4699-4712 |
| PubMed ID | 32554515 | Mgi Jnum | J:355136 |
| Mgi Id | MGI:7737749 | Doi | 10.1158/1078-0432.CCR-19-4110 |
| Citation | Rao G, et al. (2020) Anti-PD-1 Induces M1 Polarization in the Glioma Microenvironment and Exerts Therapeutic Efficacy in the Absence of CD8 Cytotoxic T Cells. Clin Cancer Res 26(17):4699-4712 |
| abstractText | PURPOSE: 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. EXPERIMENTAL DESIGN: We ablated the CD8alpha 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. RESULTS: 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. CONCLUSIONS: 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. |
