bims-malgli 2022-02-13 papers

bims-malgli

Biomed News

on Biology of malignant gliomas

Issue of 2022–02–13
thirteen papers selected by
Oltea Sampetrean, Keio University

Disruption of DNA Repair and Survival Pathways through Heat Shock Protein inhibition by Onalespib to Sensitize Malignant Gliomas to Chemoradiation therapy.
Chaperone-mediated autophagy controls proteomic and transcriptomic pathways to maintain glioma stem cell activity.
Ferroptosis, as the most enriched programmed cell death process in glioma, induces immunosuppression and immunotherapy resistance.
ASCL1 phosphorylation and ID2 upregulation are roadblocks to glioblastoma stem cell differentiation.
ADAR1-mediated RNA editing links ganglioside catabolism to glioblastoma stem cell maintenance.
Immune cell gene expression signatures in diffuse glioma are associated with IDH mutation status, patient outcome and malignant cell state, and highlight the importance of specific cell subsets in glioma biology.
Single-cell analysis of human glioma and immune cells identifies S100A4 as an immunotherapy target.
Serial H3K27M cell-free tumor DNA (cf-tDNA) tracking predicts ONC201 treatment response and progression in diffuse midline glioma.
Tumor-related molecular determinants of neurocognitive deficits in patients with diffuse glioma.
GD2-CAR T cell therapy for H3K27M-mutated diffuse midline gliomas.
Glioblastoma mutations alter EGFR dimer structure to prevent ligand bias.
DLL3 expression and methylation are associated with lower-grade glioma immune microenvironment and prognosis.
Irradiation of the subventricular zone and subgranular zone in high- and low-grade glioma patients: an atlas-based analysis on overall survival.

Clin Cancer Res. 2022 Feb 09. pii: clincanres.0468.2020. [Epub ahead of print]

Disruption of DNA Repair and Survival Pathways through Heat Shock Protein inhibition by Onalespib to Sensitize Malignant Gliomas to Chemoradiation therapy.

Jihong Xu, Pei-Jung Wu, Tzung-Huei Lai, Pratibha Sharma, Alessandro Canella, Alessandra M Welker, Christine Beattie, Cynthia D Timmers, Frederick F Lang, Naduparambil K Jacob, J Bradley Elder, Russell Lonser, Michelle Easley, Maciej Pietrzak, Deepa Sampath, Vinay K Puduvalli.

PURPOSE: Proficient DNA repair by homologous recombination (HR) facilitates resistance to chemo-radiation in glioma stem cells (GSCs). We evaluated whether compromising HR by targeting HSP90, a molecular chaperone required for the function of key HR proteins, using onalespib, a long-acting, brain-penetrant HSP90 inhibitor, would sensitize high-grade gliomas to chemo-radiation in vitro and in vivo Experimental Design: The ability of onalespib to deplete HR client proteins, impair HR repair capacity, and sensitize GBM to chemo-radiation was evaluated in vitro in GSCs, and in vivo using zebrafish and mouse intracranial glioma xenograft models. The effects of HSP90 inhibition on the transcriptome and cytoplasmic proteins was assessed in GSCs and in ex vivo organotypic human glioma slice cultures.
RESULTS: Treatment with onalespib depleted CHK1 and RAD51, two key proteins of the HR pathway, and attenuated HR repair, sensitizing GSCs to the combination of radiation and temozolomide (TMZ). HSP90 inhibition reprogrammed the transcriptome of GSCs and broadly altered expression of cytoplasmic proteins including known and novel client proteins relevant to GSCs. The combination of onalespib with radiation and TMZ extended survival in a zebra fish and a mouse xenograft model of GBM compared to the standard of care (radiation and TMZ) or onalespib with radiation.
CONCLUSIONS: The results of this study demonstrate that targeting HR by HSP90 inhibition sensitizes GSCs to radiation and chemotherapy and extends survival in zebrafish and mouse intracranial models of GBM. These results provide a preclinical rationale for assessment of HSP90 inhibitors in combination with chemoradiation in GBM patients.

DOI: https://doi.org/10.1158/1078-0432.CCR-20-0468
Cancer Res. 2022 Feb 07. pii: canres.2161.2021. [Epub ahead of print]

Chaperone-mediated autophagy controls proteomic and transcriptomic pathways to maintain glioma stem cell activity.

Jaione Auzmendi-Iriarte, Maddalen Otaegi-Ugartemendia, Estefania Carrasco-Garcia, Mikel Azkargorta, Antonio Diaz, Ander Saenz-Antoñanzas, Joaquin Andrés Andermatten, Mikel García-Puga, Idoia Garcia, Alejandro Elua-Pinin, Irune Ruiz, Nicolás Samprón, Felix Elortza, Ana Maria Cuervo, Ander Matheu.

Chaperone-mediated autophagy (CMA) is a homeostatic process essential for the lysosomal degradation of a selected subset of the proteome. CMA activity directly depends on the levels of LAMP2A, a critical receptor for CMA substrate proteins at the lysosomal membrane. In glioblastoma (GBM), the most common and aggressive brain cancer in adulthood, high levels of LAMP2A in the tumor and tumor-associated pericytes have been linked to temozolomide resistance and tumor progression. However, the role of LAMP2A, and hence CMA, in any cancer stem cell type or in glioblastoma stem cells (GSC) remains unknown. In this work, we show that LAMP2A expression is enriched in patient-derived GSCs, and its depletion diminishes GSC-mediated tumorigenic activities. Conversely, overexpression of LAMP2A facilitates the acquisition of GSC properties. Proteomic and transcriptomic analysis of LAMP2A-depleted GSCs revealed reduced extracellular matrix (ECM) interaction effectors in both analyses. Moreover, pathways related to mitochondrial metabolism and the immune system were differentially deregulated at the proteome level. Furthermore, clinical samples of GBM tissue presented with overexpression of LAMP2, which correlated with advanced glioma grade and poor overall survival. In conclusion, these results identify a novel role of CMA in directly regulating GSCs activity via multiple pathways at the proteome and transcriptome levels.

DOI: https://doi.org/10.1158/0008-5472.CAN-21-2161
Neuro Oncol. 2022 Feb 11. pii: noac033. [Epub ahead of print]

Ferroptosis, as the most enriched programmed cell death process in glioma, induces immunosuppression and immunotherapy resistance.

Tianqi Liu, Chen Zhu, Xin Chen, Gefei Guan, Cunyi Zou, Shuai Shen, Jianqi Wu, Yuhang Wang, Zhiguo Lin, Ling Chen, Peng Cheng, Wen Cheng, Anhua Wu.

   BACKGROUND: Immunosuppressive microenvironment is a major cause of immunotherapeutic resistance in glioma. In addition to secreting compounds, tumor cells under programmed cell death (PCD) processes release abundant mediators to modify the neighboring microenvironment. However, the complex relationship among PCD status, immunosuppressive microenvironment and immunotherapy is still poorly understood.
METHODS: Four independent glioma cohorts comprising 1,750 patients were enrolled for analysis. The relationships among PCD status, microenvironment cellular components and biological phenotypes were fully explored. Tissues from our hospital and experiments in vitro and in vivo were used to confirm the role of ferroptosis in glioma.
RESULTS: Analyses to determine enriched PCD processes showed that ferroptosis was the main type of PCD in glioma. Enriched ferroptosis correlated with progressive malignancy, poor outcomes and aggravated immunosuppression in glioblastoma (GBM) patients. Enhanced ferroptosis was shown to induce activation and infiltration of immune cells but attenuated antitumor cytotoxic killing. Tumor-associated macrophages (TAMs) were found to participate in ferroptosis-mediated immunosuppression. Preclinically, ferroptosis inhibition combined with PD-1/L1 blockade generated a synergistic therapeutic outcome in GBM murine models.
CONCLUSIONS: This work provides a molecular, clinical and biological landscape of ferroptosis, suggesting a role of ferroptosis in glioma malignancy and a novel synergic immunotherapeutic strategy that combines immune checkpoint blockade (ICB) treatment with ferroptosis inhibition.

Keywords:  ICB; Programmed cell death; ferroptosis; immune microenvironment; immunotherapy

DOI:  https://doi.org/10.1093/neuonc/noac033
Sci Rep. 2022 Feb 11. 12(1): 2341

ASCL1 phosphorylation and ID2 upregulation are roadblocks to glioblastoma stem cell differentiation.

Roberta Azzarelli, Aoibheann McNally, Claudia Dell'Amico, Marco Onorati, Benjamin Simons, Anna Philpott.

The growth of glioblastoma (GBM), one of the deadliest adult cancers, is fuelled by a subpopulation of stem/progenitor cells, which are thought to be the source of resistance and relapse after treatment. Re-engagement of a latent capacity of these cells to re-enter a trajectory resulting in cell differentiation is a potential new therapeutic approach for this devastating disease. ASCL1, a proneural transcription factor, plays a key role in normal brain development and is also expressed in a subset of GBM cells, but fails to engage a full differentiation programme in this context. Here, we investigated the barriers to ASCL1-driven differentiation in GBM stem cells. We see that ASCL1 is highly phosphorylated in GBM stem cells where its expression is compatible with cell proliferation. However, overexpression of a form of ASCL1 that cannot be phosphorylated on Serine-Proline sites drives GBM cells down a neuronal lineage and out of cell cycle more efficiently than its wild-type counterpart, an effect further enhanced by deletion of the inhibitor of differentiation ID2, indicating mechanisms to reverse the block to GBM cell differentiation.

DOI: https://doi.org/10.1038/s41598-022-06248-x
J Clin Invest. 2022 Feb 08. pii: e143397. [Epub ahead of print]

ADAR1-mediated RNA editing links ganglioside catabolism to glioblastoma stem cell maintenance.

Li Jiang, Yajing Hao, Changwei Shao, Qiulian Wu, Briana C Prager, Ryan C Gimple, Gabriele Sulli, Leo Jk Kim, Guoxin Zhang, Zhixin Qiu, Zhe Zhu, Xiang-Dong Fu, Jeremy N Rich.

  Glioblastoma (GBM) is the most common and lethal primary malignant brain tumor, containing GBM stem cells (GSCs) that contribute to therapeutic resistance and relapse. Exposing potential GSC vulnerabilities may provide therapeutic strategies against GBM. Here, we interrogated the role of Adenosine-to-Inosine (A-to-I) RNA editing mediated by ADAR1 (adenosine deaminase acting on RNA 1) in GSCs and found that both ADAR1 and global RNA editomes were elevated in GSCs compared to normal neural stem cells (NSCs). ADAR1 inactivation or blocking the upstream JAK/STAT pathway through TYK2 inhibition impaired GSC self-renewal and stemness. Downstream of ADAR1, RNA editing of the 3'UTR of GM2A, a key ganglioside catabolism activator, proved to be critical, as interfering with ganglioside catabolism showed similar functional impact on GSCs as ADAR1 disruption. These findings reveal RNA editing links ganglioside catabolism to GSC self-renewal and stemness, exposing a potential vulnerability of GBM for therapeutic intervention.

Keywords:  Brain cancer; Human stem cells; Oncology; Stem cells

DOI:  https://doi.org/10.1172/JCI143397
Acta Neuropathol Commun. 2022 Feb 10. 10(1): 19

Immune cell gene expression signatures in diffuse glioma are associated with IDH mutation status, patient outcome and malignant cell state, and highlight the importance of specific cell subsets in glioma biology.

Bharati Mehani, Saleembhasha Asanigari, Hye-Jung Chung, Karen Dazelle, Arashdeep Singh, Sridhar Hannenhalli, Kenneth Aldape.

  The tumor micro-environment (TME) plays an important role in various cancers, including gliomas. We estimated immune cell type-specific gene expression profiles in 3 large clinically annotated glioma datasets using CIBERSORTx and LM22/LM10 blood-based immune signatures and found that the proportions and estimated gene expression patterns of specific immune cells significantly varied according to IDH mutation status. When IDH-WT and IDH-MUT tumors were considered separately, cluster-of-cluster analyses of immune cell gene expression identified groups with distinct survival outcomes. We confirmed and extended these findings by applying a signature matrix derived from single-cell RNA-sequencing data derived from 19 glioma tumor samples to the bulk profiling data, validating findings from the LM22/LM10 results. To link immune cell signatures with outcomes in checkpoint therapy, we then showed a significant association of monocytic lineage cell gene expression clusters with patient survival and with mesenchymal gene expression scores. Integrating immune cell-based gene expression with previously described malignant cell states in glioma demonstrated that macrophage M0 abundance significantly correlated with mesenchymal state in IDH-WT gliomas, with evidence of a previously implicated role of the Oncostatin-M receptor and macrophages in the mesenchymal state. Among IDH-WT tumors that were enriched for the mesenchymal cell state, the estimated M0 macrophage expression signature coordinately also trended to a mesenchymal signature. We also examined IDH-MUT tumors stratified by 1p/19q status, showing that a mesenchymal gene expression signature the M0 macrophage fraction was enriched in IDH-MUT, non-codeleted tumors. Overall, these results highlight the biological and clinical significance of the immune cell environment related to IDH mutation status, patient prognosis and the mesenchymal state in diffuse gliomas.

Keywords:  CIBERSORTx; Deconvolution; Glioma; Malignant cell-state; Prognosis; Tumor microenvironment

DOI:  https://doi.org/10.1186/s40478-022-01323-w
Nat Commun. 2022 Feb 09. 13(1): 767

Single-cell analysis of human glioma and immune cells identifies S100A4 as an immunotherapy target.

Nourhan Abdelfattah, Parveen Kumar, Caiyi Wang, Jia-Shiun Leu, William F Flynn, Ruli Gao, David S Baskin, Kumar Pichumani, Omkar B Ijare, Stephanie L Wood, Suzanne Z Powell, David L Haviland, Brittany C Parker Kerrigan, Frederick F Lang, Sujit S Prabhu, Kristin M Huntoon, Wen Jiang, Betty Y S Kim, Joshy George, Kyuson Yun.

A major rate-limiting step in developing more effective immunotherapies for GBM is our inadequate understanding of the cellular complexity and the molecular heterogeneity of immune infiltrates in gliomas. Here, we report an integrated analysis of 201,986 human glioma, immune, and other stromal cells at the single cell level. In doing so, we discover extensive spatial and molecular heterogeneity in immune infiltrates. We identify molecular signatures for nine distinct myeloid cell subtypes, of which five are independent prognostic indicators of glioma patient survival. Furthermore, we identify S100A4 as a regulator of immune suppressive T and myeloid cells in GBM and demonstrate that deleting S100a4 in non-cancer cells is sufficient to reprogram the immune landscape and significantly improve survival. This study provides insights into spatial, molecular, and functional heterogeneity of glioma and glioma-associated immune cells and demonstrates the utility of this dataset for discovering therapeutic targets for this poorly immunogenic cancer.

DOI: https://doi.org/10.1038/s41467-022-28372-y
Neuro Oncol. 2022 Feb 06. pii: noac030. [Epub ahead of print]

Serial H3K27M cell-free tumor DNA (cf-tDNA) tracking predicts ONC201 treatment response and progression in diffuse midline glioma.

Evan Cantor, Kyle Wierzbicki, Rohinton S Tarapore, Karthik Ravi, Chase Thomas, Rodrigo Cartaxo, Viveka Nand Yadav, Ramya Ravindran, Amy K Bruzek, Jack Wadden, Vishal John, Clarissa May Babila, Jessica R Cummings, Abed Rahman Kawakibi, Sunjong Ji, Johanna Ramos, Alyssa Paul, Dustin Walling, Marcia Leonard, Patricia Robertson, Andrea Franson, Rajen Mody, Hugh J L Garton, Sriram Venetti, Yazmin Odia, Cassie Kline, Nicholas A Vitanza, Soumen Khatua, Sabine Mueller, Joshua E Allen, Sharon Gardner, Carl Koschmann.

   BACKGROUND: Diffuse Midline Glioma (DMG) with the H3K27M mutation is a lethal childhood brain cancer, with patients rarely surviving 2 years from diagnosis.
METHODS: We conducted a multi-site Phase 1 trial of the imipridone ONC201 for children with H3K27M-mutant glioma (NCT03416530). Patients enrolled on Arm D of the trial (n=24) underwent serial lumbar puncture for cell-free tumor DNA (cf-tDNA) analysis and patients on all arms at the University of Michigan underwent serial plasma collection. We performed digital droplet polymerase chain reaction (ddPCR) analysis of cf-tDNA samples and compared variant allele fraction (VAF) to radiographic change (maximal 2D tumor area on MRI).
RESULTS: Change in H3.3K27M VAF over time ("VAF delta") correlated with prolonged PFS in both CSF and plasma samples. Non-recurrent patients that had a decrease in CSF VAF displayed a longer progression free survival (p=0.049). Decrease in plasma VAF displayed a similar trend (p=0.085). VAF "spikes" (increase of at least 25%) preceded tumor progression in 8/16 cases (50%) in plasma and 5/11 cases (45.4%) in CSF. In individual cases, early reduction in H3K27M VAF predicted long-term clinical response (>1 year) to ONC201, and did not increase in cases of later-defined pseudo-progression.
CONCLUSION: Our work demonstrates the feasibility and potential utility of serial cf-tDNA in both plasma and CSF of DMG patients to supplement radiographic monitoring. Patterns of change in H3K27M VAF over time demonstrate clinical utility in terms of predicting progression and sustained response and possible differentiation of pseudo-progression and pseudo-response.

Keywords:  Diffuse midline glioma; H3K27M; ONC201; circulating tumor DNA; liquid biopsy

DOI:  https://doi.org/10.1093/neuonc/noac030
Neuro Oncol. 2022 Feb 11. pii: noac036. [Epub ahead of print]

Tumor-related molecular determinants of neurocognitive deficits in patients with diffuse glioma.

Emma van Kessel, Sharon Berendsen, Anniek E Baumfalk, Hema Venugopal, Eva A Krijnen, Wim G M Spliet, Wim Van Hecke, Fabrizio Giuliani, Tatjana Seute, Martine J E Van Zandvoort, Tom J Snijders, Pierre A Robe.

   BACKGROUND: Cognitive impairment is a common and debilitating symptom in patients with diffuse glioma, and is the result of multiple factors. We hypothesized that molecular tumor characteristics influence neurocognitive functioning (NCF), and aimed to identify tumor-related markers of NCF in diffuse glioma patients.
METHODS: We examined the relation between cognitive performance (executive function, memory and psychomotor speed) and intratumoral expression levels of molecular markers in treatment-naive patients with diffuse glioma. We performed a single-center study in a consecutive cohort, through a two-step design: (1) hypothesis-free differential expression and gene set enrichment analysis to identify candidate oncogenetic markers for cognitive impairment. Nineteen molecular markers of interest were derived from this set of genes, as well as from prior knowledge; (2) correlation of cognitive performance to intratumoral expression levels of these nineteen molecular markers, measured with immunohistochemistry.
RESULTS: From 708 included patients with immunohistochemical data, we performed in-depth analysis of neuropsychological data in 197, and differential expression analysis in 65 patients. After correcting for tumor volume and location, we found significant associations between expression levels of CD3 and IDH-1 and psychomotor speed; between IDH-1, ATRX, NLGN3, BDNF, CK2Beta, EAAT1, GAT-3, SRF and memory performance; and between IDH-1, P-STAT5b, NLGN3, CK2Beta and executive functioning. P-STAT5b, CD163, CD3 and Semaphorin-3A were independently associated after further correction for histopathological grade.
CONCLUSION: Molecular characteristics of glioma can be independent determinants of patients' cognitive functioning. This suggests that besides tumor volume, location and histological grade, variations in glioma biology influence cognitive performance through mechanisms that include perturbation of neuronal communication. These results pave the way towards targeted cognition improving therapies in neuro-oncology.

Keywords:  cognitive functioning; diffuse glioma; oncobiological characteristics

DOI:  https://doi.org/10.1093/neuonc/noac036
Nature. 2022 Feb 07.

GD2-CAR T cell therapy for H3K27M-mutated diffuse midline gliomas.

Robbie G Majzner, Sneha Ramakrishna, Kristen W Yeom, Shabnum Patel, Harshini Chinnasamy, Liora M Schultz, Rebecca M Richards, Li Jiang, Valentin Barsan, Rebecca Mancusi, Anna C Geraghty, Zinaida Good, Aaron Y Mochizuki, Shawn M Gillespie, Angus Martin Shaw Toland, Jasia Mahdi, Agnes Reschke, Esther Nie, Isabelle J Chau, Maria Caterina Rotiroti, Christopher W Mount, Christina Baggott, Sharon Mavroukakis, Emily Egeler, Jennifer Moon, Courtney Erickson, Sean Green, Michael Kunicki, Michelle Fujimoto, Zach Ehlinger, Warren Reynolds, Sreevidya Kurra, Katherine E Warren, Snehit Prabhu, Hannes Vogel, Lindsey Rasmussen, Timothy T Cornell, Sonia Partap, Paul G Fisher, Cynthia J Campen, Mariella G Filbin, Gerald Grant, Bita Sahaf, Kara L Davis, Steven A Feldman, Crystal L Mackall, Michelle Monje.

Diffuse intrinsic pontine glioma (DIPG) and other H3K27M-mutated diffuse midline gliomas (DMG) are universally lethal paediatric central nervous system tumours1. We previously discovered that the disialoganglioside GD2 is highly expressed on H3K27M-mutant glioma cells and demonstrated promising preclinical efficacy of GD2-directed chimeric antigen receptor (CAR) T cells2, providing the rationale for a first-in-human Phase 1 clinical trial (NCT04196413). Because CAR T-cell-induced brainstem inflammation can result in obstructive hydrocephalus, increased intracranial pressure, and dangerous tissue shifts, neurocritical care precautions were incorporated. Here we present the clinical experience from the first four patients with H3K27M-mutant DIPG/DMG treated with GD2-CAR T cells (GD2-CART) at dose level 1 (1e6 GD2-CAR T cells/kg administered intravenously). Patients who exhibited clinical benefit were eligible for subsequent GD2-CAR T infusions administered intracerebroventricularly3. Toxicity was largely related to tumor location and reversible with intensive supportive care. On-target, off-tumor toxicity was not observed. Three of four patients exhibited clinical and radiographic improvement. Proinflammatory cytokines were increased in plasma and cerebrospinal fluid (CSF). Transcriptomic analyses of 65,598 single cells from CAR T cell products and CSF elucidate heterogeneity in response between subjects and administration routes. These early results underscore the promise of this approach for H3K27M+ DIPG/DMG therapy.

DOI: https://doi.org/10.1038/s41586-022-04489-4
Nature. 2022 Feb 09.

Glioblastoma mutations alter EGFR dimer structure to prevent ligand bias.

Chun Hu, Carlos A Leche, Anatoly Kiyatkin, Zhaolong Yu, Steven E Stayrook, Kathryn M Ferguson, Mark A Lemmon.

The epidermal growth factor receptor (EGFR) is frequently mutated in human cancer1,2, and is an important therapeutic target. EGFR inhibitors have been successful in lung cancer, where mutations in the intracellular tyrosine kinase domain activate the receptor1, but not in glioblastoma multiforme (GBM)3, where mutations occur exclusively in the extracellular region. Here we show that common extracellular GBM mutations prevent EGFR from discriminating between its activating ligands4. Different growth factor ligands stabilize distinct EGFR dimer structures5 that signal with different kinetics to specify or bias outcome5,6. EGF itself induces strong symmetric dimers that signal transiently to promote proliferation. Epiregulin (EREG) induces much weaker asymmetric dimers that drive sustained signalling and differentiation5. GBM mutations reduce the ability of EGFR to distinguish EREG from EGF in cellular assays, and allow EGFR to form strong (EGF-like) dimers in response to EREG and other low-affinity ligands. Using X-ray crystallography, we further show that the R84K GBM mutation symmetrizes EREG-driven extracellular dimers so that they resemble dimers normally seen with EGF. By contrast, a second GBM mutation, A265V, remodels key dimerization contacts to strengthen asymmetric EREG-driven dimers. Our results argue for an important role of altered ligand discrimination by EGFR in GBM, with potential implications for therapeutic targeting.

DOI: https://doi.org/10.1038/s41586-021-04393-3
Genomics. 2022 Feb 04. pii: S0888-7543(22)00034-9. [Epub ahead of print]114(2): 110289

DLL3 expression and methylation are associated with lower-grade glioma immune microenvironment and prognosis.

Humaira Noor, Shane Whittaker, Kerrie L McDonald.

  Notch signalling pathway, particularly its ligand delta-ligand 3 (DLL3), is important in glioma, however, little is known about DLL3 regulation and prognostic effects. Immunohistochemistry on a cohort of 163 gliomas revealed DLL3 upregulation in IDH1 mutant gliomas, where it was associated with a favourable prognosis (HR[95% CI]: 0.28[0.09-0.87]; p = 0.021). We investigated the epigenetic regulation of DLL3, and identified individual CpG sites correlating with DLL3 mRNA expression, which were significant prognostic markers in LGG. In silico analysis revealed that infiltrating immune cells significantly correlated with DLL3 expression, methylation and somatic copy number alterations. The prognostic effects of DLL3 expression was significantly affected by infiltration of immune cells. RNA Sequencing of 83 LGGs and GO Term analysis of differentially expressed genes showed that low DLL3 expression was related to ciliogenesis, which was confirmed by TCGA LGG analysis. Thus, DLL3 may play an important role in the immune microenvironment and prognosis of LGGs.

Keywords:  DLL3; Delta-like ligand 3; IDH1 mutation; Lower-grade glioma; Notch signalling pathway; Prognostic biomarker

DOI:  https://doi.org/10.1016/j.ygeno.2022.110289
Neurooncol Adv. 2022 Jan-Dec;4(1):4(1): vdab193

Irradiation of the subventricular zone and subgranular zone in high- and low-grade glioma patients: an atlas-based analysis on overall survival.

Danique E Bruil, Szabolcs David, Steven H J Nagtegaal, Sophia F A M de Sonnaville, Joost J C Verhoeff.

   Background: Neural stem cells in the subventricular zone (SVZ) and subgranular zone (SGZ) are hypothesized to support growth of glioma. Therefore, irradiation of the SVZ and SGZ might reduce tumor growth and might improve overall survival (OS). However, it may also inhibit the repair capacity of brain tissue. The aim of this retrospective cohort study is to assess the impact of SVZ and SGZ radiotherapy doses on OS of patients with high-grade (HGG) or low-grade (LGG) glioma.
Methods: We included 273 glioma patients who received radiotherapy. We created an SVZ atlas, shared openly with this work, while SGZ labels were taken from the CoBrA atlas. Next, SVZ and SGZ regions were automatically delineated on T1 MR images. Dose and OS correlations were investigated with Cox regression and Kaplan-Meier analysis.
Results: Cox regression analyses showed significant hazard ratios for SVZ dose (univariate: 1.029/Gy, P < .001; multivariate: 1.103/Gy, P = .002) and SGZ dose (univariate: 1.023/Gy, P < .001; multivariate: 1.055/Gy, P < .001) in HGG patients. Kaplan-Meier analysis showed significant correlations between OS and high-/low-dose groups for HGG patients (SVZ: respectively 10.7 months (>30.33 Gy) vs 14.0 months (<30.33 Gy) median OS, P = .011; SGZ: respectively 10.7 months (>29.11 Gy) vs 15.5 months (<29.11 Gy) median OS, P < .001). No correlations between dose and OS were found for LGG patients.
Conclusion: Irradiation doses on neurogenic areas correlate negatively with OS in patients with HGG. Whether sparing of the SVZ and SGZ during radiotherapy improves OS, should be subject of prospective studies.

Keywords:  glioma; overall survival; radiotherapy; subgranular zone; subventricular zone

DOI:  https://doi.org/10.1093/noajnl/vdab193