Intravital imaging reveals synergistic effect of CAR T-cells and radiation therapy in a preclinical immunocompetent glioblastoma model

Surya Murty; Samuel T Haile; Corinne Beinat; Amin Aalipour; Israt S Alam; Tara Murty; Travis M Shaffer; Chirag B Patel; Edward E Graves; Crystal L Mackall; Sanjiv S Gambhir

doi:10.1080/2162402X.2020.1757360

Intravital imaging reveals synergistic effect of CAR T-cells and radiation therapy in a preclinical immunocompetent glioblastoma model

Oncoimmunology. 2020 May 13;9(1):1757360. doi: 10.1080/2162402X.2020.1757360.

Authors

Surya Murty^{1

2}, Samuel T Haile³, Corinne Beinat², Amin Aalipour^{1

2

4}, Israt S Alam², Tara Murty⁴, Travis M Shaffer², Chirag B Patel^{2

5}, Edward E Graves^{6

7}, Crystal L Mackall^{7

8}, Sanjiv S Gambhir^{1

2

7

9

10}

Affiliations

¹ Department of Bioengineering, Stanford University School of Medicine, Stanford, CA.
² Molecular Imaging Program at Stanford, Stanford University School of Medicine, Stanford, CA, USA.
³ Department of Immunology, Stanford University School of Medicine, Stanford, CA, USA.
⁴ Medical Scientist Training Program, Stanford University School of Medicine, Stanford, CA, USA.
⁵ Division of Neuro-Oncology, Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA, USA.
⁶ Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA, USA.
⁷ Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA, USA.
⁸ Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, USA.
⁹ Department of Radiology, Stanford University School of Medicine, Stanford, CA, USA.
¹⁰ Canary Center at Stanford for Cancer Early Detection, Stanford University School of Medicine, Palo Alto, CA, USA.

Abstract

Recent advances in novel immune strategies, particularly chimeric antigen receptor (CAR)-bearing T-cells, have shown limited efficacy against glioblastoma (GBM) in clinical trials. We currently have an incomplete understanding of how these emerging therapies integrate with the current standard of care, specifically radiation therapy (RT). Additionally, there is an insufficient number of preclinical studies monitoring these therapies with high spatiotemporal resolution. To address these limitations, we report the first longitudinal fluorescence-based intravital microscopy imaging of CAR T-cells within an orthotopic GBM preclinical model to illustrate the necessity of RT for complete therapeutic response. Additionally, we detail the first usage of murine-derived CAR T-cells targeting the disialoganglioside GD2 in an immunocompetent tumor model. Cell culture assays demonstrated substantial GD2 CAR T-cell-mediated killing of murine GBM cell lines SB28 and GL26 induced to overexpress GD2. Complete antitumor response in advanced syngeneic orthotopic models of GBM was achieved only when a single intravenous dose of GD2 CAR T-cells was following either sub-lethal whole-body irradiation or focal RT. Intravital microscopy imaging successfully visualized CAR T-cell homing and T-cell mediated apoptosis of tumor cells in real-time within the tumor stroma. Findings indicate that RT allows for rapid CAR T-cell extravasation from the vasculature and expansion within the tumor microenvironment, leading to a more robust and lasting immunologic response. These exciting results highlight potential opportunities to improve intravenous adoptive T-cell administration in the treatment of GBM through concurrent RT. Additionally, they emphasize the need for advancements in immunotherapeutic homing to and extravasation through the tumor microenvironment.

Keywords: Chimeric antigen receptor (CAR); glioblastoma; imaging; immunotherapy; intravital microscopy.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Cell Line, Tumor
Glioblastoma* / radiotherapy
Immunotherapy, Adoptive
Intravital Microscopy
Mice
Receptors, Antigen, T-Cell
T-Lymphocytes
Tumor Microenvironment
Xenograft Model Antitumor Assays

Substances

Receptors, Antigen, T-Cell

Grants and funding

S10 RR027431/RR/NCRR NIH HHS/United States