H3.3-G34 mutations impair DNA repair and promote cGAS/STING-mediated immune responses in pediatric high-grade glioma models
Santiago Haase, … , Pedro R. Lowenstein, Maria G. Castro
Santiago Haase, … , Pedro R. Lowenstein, Maria G. Castro
Published September 20, 2022
Citation Information: J Clin Invest. 2022;132(22):e154229. https://doi.org/10.1172/JCI154229.
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Research Article Oncology

H3.3-G34 mutations impair DNA repair and promote cGAS/STING-mediated immune responses in pediatric high-grade glioma models

Abstract

Pediatric high-grade gliomas (pHGGs) are the leading cause of cancer-related deaths in children in the USA. Sixteen percent of hemispheric pediatric and young adult HGGs encode Gly34Arg/Val substitutions in the histone H3.3 (H3.3-G34R/V). The mechanisms by which H3.3-G34R/V drive malignancy and therapeutic resistance in pHGGs remain unknown. Using a syngeneic, genetically engineered mouse model (GEMM) and human pHGG cells encoding H3.3-G34R, we demonstrate that this mutation led to the downregulation of DNA repair pathways. This resulted in enhanced susceptibility to DNA damage and inhibition of the DNA damage response (DDR). We demonstrate that genetic instability resulting from improper DNA repair in G34R-mutant pHGG led to the accumulation of extrachromosomal DNA, which activated the cyclic GMP–AMP synthase/stimulator of IFN genes (cGAS/STING) pathway, inducing the release of immune-stimulatory cytokines. We treated H3.3-G34R pHGG–bearing mice with a combination of radiotherapy (RT) and DNA damage response inhibitors (DDRi) (i.e., the blood-brain barrier–permeable PARP inhibitor pamiparib and the cell-cycle checkpoint CHK1/2 inhibitor AZD7762), and these combinations resulted in long-term survival for approximately 50% of the mice. Moreover, the addition of a STING agonist (diABZl) enhanced the therapeutic efficacy of these treatments. Long-term survivors developed immunological memory, preventing pHGG growth upon rechallenge. These results demonstrate that DDRi and STING agonists in combination with RT induced immune-mediated therapeutic efficacy in G34-mutant pHGG.

Authors

Santiago Haase, Kaushik Banerjee, Anzar A. Mujeeb, Carson S. Hartlage, Fernando M. Núñez, Felipe J. Núñez, Mahmoud S. Alghamri, Padma Kadiyala, Stephen Carney, Marcus N. Barissi, Ayman W. Taher, Emily K. Brumley, Sarah Thompson, Justin T. Dreyer, Caitlin T. Alindogan, Maria B. Garcia-Fabiani, Andrea Comba, Sriram Venneti, Visweswaran Ravikumar, Carl Koschmann, Ángel M. Carcaboso, Maria Vinci, Arvind Rao, Jennifer S. Yu, Pedro R. Lowenstein, Maria G. Castro

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Figure 12

H3.3-G34R pHGG shows an improved therapeutic response to DDRi in combination with RT, and long-term survivors acquire antitumor immunological memory.

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H3.3-G34R pHGG shows an improved therapeutic response to DDRi in combina...
(A) Illustration depicting the time frame of the combined treatment with DDRi and RT. (B) Kaplan-Meier survival plot of H3.3-G34R–bearing mice treated with RT alone or in combination with the PARPi pamiparib. (C) Kaplan-Meier survival plot of H3.3-G34R–bearing mice treated with RT alone or in combination with the CHK1/2i AZD7762. (D) Results of the in vivo imaging of tumor size in response to the DDRi plus RT treatment. The mark indicates that the animal was euthanized because of signs of tumor burden. (E) Kaplan-Meier survival plot of H3.3-G34R–bearing mice that survived following RT plus DDRi therapies and that were rechallenged with H3.3-G34R pHGG cells, compared with naive mice implanted with the same cells (control group). (F) Kaplan-Meier survival plot of CD8-KO mice implanted with H3.3-G34R cells and treated with RT alone or in combination with the CHK1/2i AZD7762 or the PARPi pamiparib. n = 5 mice/group. *P < 0.05, **P < 0.01, and ***P < 0.005; log-rank (Mantel-Cox) test.