STING-induced blood-brain barrier opening combined with radiotherapy potentiates antitumor response in a high-grade glioma model
Shashwat Tripathi, Hinda Najem, Lisa Hurley, Ruochen Du, Crismita Dmello, Heba Ali, Kathleen McCortney, Karl J. Habashy, Peng Zhang, Craig M. Horbinski, Lara Leoni, Ryan J. Avery, Rimas V. Lukas, Timothy L. Sita, David R. Raleigh, Sean Sachdev, Roger Stupp, Maciej S. Lesniak, David M. Ashley, Daniele Procissi, Michael A. Curran, Irina Balyasnikova, Amy B. Heimberger
Shashwat Tripathi, Hinda Najem, Lisa Hurley, Ruochen Du, Crismita Dmello, Heba Ali, Kathleen McCortney, Karl J. Habashy, Peng Zhang, Craig M. Horbinski, Lara Leoni, Ryan J. Avery, Rimas V. Lukas, Timothy L. Sita, David R. Raleigh, Sean Sachdev, Roger Stupp, Maciej S. Lesniak, David M. Ashley, Daniele Procissi, Michael A. Curran, Irina Balyasnikova, Amy B. Heimberger
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Research Article Immunology Oncology Vascular biology

STING-induced blood-brain barrier opening combined with radiotherapy potentiates antitumor response in a high-grade glioma model

Abstract

Radiation therapy (RT) is the standard of care for glioblastoma but is not curative. Triggering the cGAS/stimulator of interferon genes (STING) pathway with potent agonists, such as 8803, exerts activity across high-grade glioma preclinical models. To determine if the combination of 8803 with RT warrants consideration in the up-front treatment setting and to clarify the underlying mechanisms of therapeutic activity, C57BL/6J mice harboring intracerebral CT-2A or QPP8v gliomas were treated with RT, intratumoral 8803, or both. The treatment with the combination resulted in 80% long-term survival in the CT-2A model but not in the radiation-resistant QPP8v model. This therapeutic effect was maintained in Sting–/– CT-2A cells, highlighting the direct role of the immune system in mediating the survival benefit. Single-cell RNA-Seq identified increased nitric oxide synthase 2 (Nos2) in inflammatory tumor-associated macrophages; however, the therapeutic effect was maintained in Nos2–/– mice. Additionally, 8803 reprogrammed the blood-brain barrier (BBB) by altering the Pecam and Cd147 pathways in endothelial cells; intracranial injection of 8803 induced bihemispheric BBB opening for up to 24 hours. Sting activation was visualized longitudinally using 3’-deoxy-3’-[18F]-fluorothymidine ([18F]-FLT) PET, which peaked 72–96 hours after 8803 administration. In summary, 8803 combined with RT triggers distinctive antiglioma immune reactivity, facilitates BBB opening, and warrants consideration for up-front clinical trials in glioblastoma, where treatment effects can be monitored using [18F]-FLT PET imaging.

Authors

Shashwat Tripathi, Hinda Najem, Lisa Hurley, Ruochen Du, Crismita Dmello, Heba Ali, Kathleen McCortney, Karl J. Habashy, Peng Zhang, Craig M. Horbinski, Lara Leoni, Ryan J. Avery, Rimas V. Lukas, Timothy L. Sita, David R. Raleigh, Sean Sachdev, Roger Stupp, Maciej S. Lesniak, David M. Ashley, Daniele Procissi, Michael A. Curran, Irina Balyasnikova, Amy B. Heimberger

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Figure 4

8803 triggers BBB opening.

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8803 triggers BBB opening. (A) Representative explanted whole brain moun...
(A) Representative explanted whole brain mount images from the experimental treatment groups. After fluorescein dye administration, mouse brains were collected and imaged using the Nikon epifluorescence microscope at 4× original magnification. Quantitative data were generated based on intensity thresholds, eliminating noise and then harmonizing across all images. Positive-intensity data points (pixels) are shown in red, and the baseline fluorescent expression is shown in green. The brain outline is illustrated with the white line. Brightness color adjustments were made to detect baseline green fluorescence of the brains for illustrative purposes, which does not alter the quantitative data generated based on the intensity thresholds harmonized across all images. (B) Summarized quantification of the fluorescent signal area of distribution between experimental groups (n = 2–4). (C) Representative images of explanted whole brain mounts from the experimental groups collected at baseline and 24 hours after intracerebral administration of either PBS or 8803 (5 μg) in the golden ticket background mice. (D) Summarized quantification of the fluorescent signal area of distribution between experimental groups, as shown in C. (E) Representative images of explanted whole brain mounts from the experimental groups collected at baseline and 24 hours after either PBS or 8803 (5 μg) administration in the NOS2-KO mice. (F) Summarized quantification of the fluorescent signal area of distribution between experimental groups as shown in E.