Glioblastoma (GBM) is a notoriously immunosuppressive primary brain tumor. The long-term goal of this proposal is to understand the mechanisms of GBM-mediated immunosuppression, identify effective means for reversing immunosuppression, and optimize anti-glioma vaccine therapies. B7-Homologue 1 (B7H1), also known as programmed death ligand 1 (PD-L1), is a cell surface protein that inhibits anti-tumor immunity. It is unique as an immunosuppressive protein because its expression is linked to a fundamental step in oncogenesis: PTEN loss and activation of PI 3-kinase (PI(3)K). This provides potential opportunities for reversal of B7-H1 induction through pharmacological inhibition of the PI(3)K pathway. Another unique feature of B7-H1 is its ability to directly faciliate immunosuppression through multiple mechanisms such as apoptosis of CD8+ T-cells, CD4+ helper T-cells (Thelp) and NK cells, or expansion of immunosuppressive CD4+ regulatory T-cells (Tregs). Expression of B7H1 on circulating monocytes, infiltrating macrophages and resident microglia provides an additional layer of immunoresistance in the tumor microenvironment. Thus, the cell surface expression of B7H1 provides another opportunity to reverse immunosuppression through administration of blocking antibodies against B7H1 or its receptor PD-1. To date, the effects of B7H1 on brain tumor immunity have only been tested using highly passaged glioma cell lines and non-autologous T-cells. Mechanisms of B7H1-mediated immunosuppression have not been fully elucidated. Furthermore, the effects of B7H1 on efficacy of glioma vaccine therapy have not been studied. This proposal seeks to thoroughly characterize the immunosuppressive mechanisms of B7H1 using autologous reagents from GBM patients and animal models of glioma that can be immunologically manipulated. We hypothesize that B7H1 expression in the GBM microenvironment confers immunoresistance that can be effectively reversed by B7H1/PD-1 blockade or pharmacologic inhibition of the PI(3)K pathway. The availability of drugs that inhibit the PI(3)K pathway or block B7-H1 and its receptor PD-1 provides a natural extension of these studies into the realm of patient care.

Public Health Relevance

Glioblastoma (GBM) is an aggressive form of brain tumor for which we have no effective treatment. Immunotherapy offers the hope of highly specific therapy with minimal toxicity, but is limited by local immunoresistance mediated by proteins such as B7 homolog 1 (B7H1). A thorough understanding of B7H1- mediated immunoresistance mechanisms may provide opportunities to augment immunotherapy and extend survival for GBM patients.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
7R01CA164714-07
Application #
9887591
Study Section
Clinical Neuroimmunology and Brain Tumors Study Section (CNBT)
Program Officer
Mccarthy, Susan A
Project Start
2013-09-17
Project End
2019-06-30
Budget Start
2019-06-07
Budget End
2019-06-30
Support Year
7
Fiscal Year
2018
Total Cost
Indirect Cost
Name
University of California Davis
Department
Type
DUNS #
047120084
City
Davis
State
CA
Country
United States
Zip Code
95618
DiDomenico, Joseph; Lamano, Jonathan B; Oyon, Daniel et al. (2018) The immune checkpoint protein PD-L1 induces and maintains regulatory T cells in glioblastoma. Oncoimmunology 7:e1448329
Bloch, Orin; Lim, Michael; Sughrue, Michael E et al. (2017) Autologous Heat Shock Protein Peptide Vaccination for Newly Diagnosed Glioblastoma: Impact of Peripheral PD-L1 Expression on Response to Therapy. Clin Cancer Res 23:3575-3584
Lamano, Jonathan B; Ampie, Leonel; Choy, Winward et al. (2016) Immunomonitoring in glioma immunotherapy: current status and future perspectives. J Neurooncol 127:1-13
Ampie, Leonel; Choy, Winward; Lamano, Jonathan B et al. (2015) Heat shock protein vaccines against glioblastoma: from bench to bedside. J Neurooncol 123:441-8
Clark, Aaron J; Safaee, Michael; Oh, Taemin et al. (2014) Stable luciferase expression does not alter immunologic or in vivo growth properties of GL261 murine glioma cells. J Transl Med 12:345
Oh, Taemin; Ivan, Michael E; Sun, Matthew Z et al. (2014) PI3K pathway inhibitors: potential prospects as adjuncts to vaccine immunotherapy for glioblastoma. Immunotherapy 6:737-53
Bloch, Orin; Crane, Courtney A; Fuks, Yelena et al. (2014) Heat-shock protein peptide complex-96 vaccination for recurrent glioblastoma: a phase II, single-arm trial. Neuro Oncol 16:274-9
Oh, Taemin; Fakurnejad, Shayan; Sayegh, Eli T et al. (2014) Immunocompetent murine models for the study of glioblastoma immunotherapy. J Transl Med 12:107