bims-malgli 2021-10-03 papers

bims-malgli

Biomed News

on Biology of malignant gliomas

Issue of 2021‒10‒03
twenty-four papers selected by
Oltea Sampetrean
Keio University

The Presence and Potential Role of ALDH1A2 in the Glioblastoma Microenvironment.
Elimination of radiation-induced senescence in the brain tumor microenvironment attenuates glioblastoma recurrence.
Current Immunotherapeutic Strategies for the Treatment of Glioblastoma.
Multi-Platform Classification of IDH-Wild-Type Glioblastoma Based on ERK/MAPK Pathway: Diagnostic, Prognostic and Therapeutic Implications.
Ex Vivo Expanded and Activated Natural Killer Cells Prolong the Overall Survival of Mice with Glioblastoma-like Cell-Derived Tumors.
A vascularized tumoroid model for human glioblastoma angiogenesis.
Efficacy and safety of nivolumab in Japanese patients with first recurrence of glioblastoma: an open-label, non-comparative study.
A Modified Nucleoside 6-thio-2'-deoxyguanosine Exhibits Anti-tumor Activity in Gliomas.
Extracellular vesicles: the key for precision medicine in glioblastoma.
The Interplay between Glioblastoma and Its Microenvironment.
Generation, characterization, and drug sensitivities of 12 patient-derived IDH1-mutant glioma cell cultures.
Cancer stem cells in gliomas: evolving concepts and therapeutic implications.
Epigenetic encoding, heritability and plasticity of glioma transcriptional cell states.
DNA Damage Response in Glioblastoma: Mechanism for Treatment Resistance and Emerging Therapeutic Strategies.
Single-Cell Omics in Dissecting Immune Microenvironment of Malignant Gliomas-Challenges and Perspectives.
Applications of CRISPR-Cas9 Technology to Genome Editing in Glioblastoma Multiforme.
Bench to bedside radiosensitizer development strategy for newly diagnosed glioblastoma.
Toward the Next Generation of High-Grade Glioma Clinical Trials in the Era of Precision Medicine.
Single-cell multimodal glioma analyses identify epigenetic regulators of cellular plasticity and environmental stress response.
Clinical Targeting of Altered Metabolism in High-Grade Glioma.
Filamentous Bacteriophage-A Powerful Carrier for Glioma Therapy.
G-CSF secreted by mutant IDH1 glioma stem cells abolishes myeloid cell immunosuppression and enhances the efficacy of immunotherapy.
Precision Radiotherapy for Gliomas: Implementing Novel Imaging Biomarkers to Improve Outcomes With Patient-Specific Therapy.
Glial and myeloid heterogeneity in the brain tumour microenvironment.

Cells. 2021 Sep 20. pii: 2485. [Epub ahead of print]10(9):

The Presence and Potential Role of ALDH1A2 in the Glioblastoma Microenvironment.

Stephanie Sanders, Denise M Herpai, Analiz Rodriguez, Yue Huang, Jeff Chou, Fang-Chi Hsu, Darren Seals, Ryan Mott, Lance D Miller, Waldemar Debinski.

  Glioblastoma (GBM) is the most aggressive malignant glioma. Therapeutic targeting of GBM is made more difficult due to its heterogeneity, resistance to treatment, and diffuse infiltration into the brain parenchyma. Better understanding of the tumor microenvironment should aid in finding more effective management of GBM. GBM-associated macrophages (GAM) comprise up to 30% of the GBM microenvironment. Therefore, exploration of GAM activity/function and their specific markers are important for developing new therapeutic agents. In this study, we identified and evaluated the expression of ALDH1A2 in the GBM microenvironment, and especially in M2 GAM, though it is also expressed in reactive astrocytes and multinucleated tumor cells. We demonstrated that M2 GAM highly express ALDH1A2 when compared to other ALDH1 family proteins. Additionally, GBM samples showed higher expression of ALDH1A2 when compared to low-grade gliomas (LGG), and this expression was increased upon tumor recurrence both at the gene and protein levels. We demonstrated that the enzymatic product of ALDH1A2, retinoic acid (RA), modulated the expression and activity of MMP-2 and MMP-9 in macrophages, but not in GBM tumor cells. Thus, the expression of ALDH1A2 may promote the progressive phenotype of GBM.

Keywords:  ALDH1A2; MMP; enzyme; glioblastoma; invasion; low-grade glioma; macrophages; monocytic cells; progression; retinoic acid; single-cell sequencing; tumor microenvironment; tumor-associated macrophages

DOI:  https://doi.org/10.3390/cells10092485
Cancer Res. 2021 Sep 27. pii: canres.0752.2021. [Epub ahead of print]

Elimination of radiation-induced senescence in the brain tumor microenvironment attenuates glioblastoma recurrence.

Eliot Fletcher-Sananikone, Suman Kanji, Nozomi Tomimatsu, Luis Fernando Macedo Di Cristofaro, Rahul K Kollipara, Debabrata Saha, John R Floyd, Patrick Sung, Robert Hromas, Terry C Burns, Ralf Kittler, Amyn A Habib, Bipasha Mukherjee, Sandeep Burma.

Glioblastomas (GBM) are routinely treated with ionizing radiation (IR) but inevitably recur and develop therapy resistance. During treatment, the tissue surrounding tumors is also irradiated. IR potently induces senescence, and senescent stromal cells can promote the growth of neighboring tumor cells by secreting factors that create a senescence-associated secretory phenotype (SASP). Here, we carried out transcriptomic and tumorigenicity analyses in irradiated mouse brains to elucidate how radiation-induced senescence of non-neoplastic brain cells promotes tumor growth. Following cranial irradiation, widespread senescence in the brain occurred, with the astrocytic population being particularly susceptible. Irradiated brains showed an altered transcriptomic profile characterized by upregulation of CDKN1A (p21), a key enforcer of senescence, and several SASP factors including HGF, the ligand of the receptor tyrosine kinase (RTK) Met. Pre-irradiation of mouse brains increased Met-driven growth and invasiveness of orthotopically implanted glioma cells. Importantly, irradiated p21-/- mouse brains did not exhibit senescence and consequently failed to promote tumor growth. Senescent astrocytes secreted HGF to activate Met in glioma cells and promote their migration and invasion in vitro, which could be blocked by HGF-neutralizing antibodies or the Met inhibitor crizotinib. Crizotinib also slowed the growth of glioma cells implanted in pre-irradiated brains. Treatment with the senolytic drug ABT-263 (navitoclax) selectively killed senescent astrocytes in vivo, significantly attenuating growth of glioma cells implanted in pre-irradiated brains. These results indicate that SASP factors in the irradiated tumor microenvironment drive GBM growth via RTK activation, underscoring the potential utility of adjuvant senolytic therapy for preventing GBM recurrence after radiotherapy.

DOI: https://doi.org/10.1158/0008-5472.CAN-21-0752
Cancers (Basel). 2021 Sep 10. pii: 4548. [Epub ahead of print]13(18):

Current Immunotherapeutic Strategies for the Treatment of Glioblastoma.

Mark Dapash, Brandyn Castro, David Hou, Catalina Lee-Chang.

  Glioblastoma (GBM) is a lethal primary brain tumor. Despite extensive effort in basic, translational, and clinical research, the treatment outcomes for patients with GBM are virtually unchanged over the past 15 years. GBM is one of the most immunologically "cold" tumors, in which cytotoxic T-cell infiltration is minimal, and myeloid infiltration predominates. This is due to the profound immunosuppressive nature of GBM, a tumor microenvironment that is metabolically challenging for immune cells, and the low mutational burden of GBMs. Together, these GBM characteristics contribute to the poor results obtained from immunotherapy. However, as indicated by an ongoing and expanding number of clinical trials, and despite the mostly disappointing results to date, immunotherapy remains a conceptually attractive approach for treating GBM. Checkpoint inhibitors, various vaccination strategies, and CAR T-cell therapy serve as some of the most investigated immunotherapeutic strategies. This review article aims to provide a general overview of the current state of glioblastoma immunotherapy. Information was compiled through a literature search conducted on PubMed and clinical trials between 1961 to 2021.

Keywords:  CAR-T; checkpoint inhibitors; glioblastoma; glioblastoma immunotherapy; immunotherapy; vaccine

DOI:  https://doi.org/10.3390/cancers13184548
Cancers (Basel). 2021 Sep 09. pii: 4532. [Epub ahead of print]13(18):

Multi-Platform Classification of IDH-Wild-Type Glioblastoma Based on ERK/MAPK Pathway: Diagnostic, Prognostic and Therapeutic Implications.

Maria-Magdalena Georgescu.

  Glioblastoma is the most aggressive and frequent glioma in the adult population. Because current therapy regimens confer only minimal survival benefit, molecular subgrouping to stratify patient prognosis and therapy design is warranted. This study presents a multi-platform classification of glioblastoma by analyzing a large, ethnicity-inclusive 101-adult-patient cohort. It defines seven non-redundant IDH-wild-type glioblastoma molecular subgroups, G1-G7, corresponding to the upstream receptor tyrosine kinase (RTK) and RAS-RAF segment of the ERK/MAPK signal transduction pathway. These glioblastoma molecular subgroups are classified as G1/EGFR, G2/FGFR3, G3/NF1, G4/RAF, G5/PDGFRA, G6/Multi-RTK, and G7/Other. The comprehensive genomic analysis was refined by expression landscaping of all RTK genes, as well as of the major associated growth pathway mediators, and used to hierarchically cluster the subgroups. Parallel demographic, clinical, and histologic pattern analyses were merged with the molecular subgrouping to yield the first inclusive multi-platform classification for IDH-wild-type glioblastoma. This straightforward classification with diagnostic and prognostic significance may be readily used in neuro-oncological practice and lays the foundation for personalized targeted therapy approaches.

Keywords:  EGFR; EPHB2; ERK/MAPK pathway; FGFR3; MET; NF1; PDGFRA; PI3K/PTEN pathway; glioblastoma molecular classification; receptor tyrosine kinase

DOI:  https://doi.org/10.3390/cancers13184532
Int J Mol Sci. 2021 Sep 15. pii: 9975. [Epub ahead of print]22(18):

Ex Vivo Expanded and Activated Natural Killer Cells Prolong the Overall Survival of Mice with Glioblastoma-like Cell-Derived Tumors.

Yoichi Shida, Tsutomu Nakazawa, Ryosuke Matsuda, Takayuki Morimoto, Fumihiko Nishimura, Mitsutoshi Nakamura, Ryosuke Maeoka, Shuichi Yamada, Ichiro Nakagawa, Young-Soo Park, Motoaki Yasukawa, Takashi Tojo, Takahiro Tsujimura, Hiroyuki Nakase.

  Glioblastoma (GBM) is the leading malignant intracranial tumor and is associated with a poor prognosis. Highly purified, activated natural killer (NK) cells, designated as genuine induced NK cells (GiNKs), represent a promising immunotherapy for GBM. We evaluated the anti-tumor effect of GiNKs in association with the programmed death 1(PD-1)/PD-ligand 1 (PD-L1) immune checkpoint pathway. We determined the level of PD-1 expression, a receptor known to down-regulate the immune response against malignancy, on GiNKs. PD-L1 expression on glioma cell lines (GBM-like cell line U87MG, and GBM cell line T98G) was also determined. To evaluate the anti-tumor activity of GiNKs in vivo, we used a xenograft model of subcutaneously implanted U87MG cells in immunocompromised NOG mice. The GiNKs expressed very low levels of PD-1. Although PD-L1 was expressed on U87MG and T98G cells, the expression levels were highly variable. Our xenograft model revealed that the retro-orbital administration of GiNKs and interleukin-2 (IL-2) prolonged the survival of NOG mice bearing subcutaneous U87MG-derived tumors. PD-1 blocking antibodies did not have an additive effect with GiNKs for prolonging survival. GiNKs may represent a promising cell-based immunotherapy for patients with GBM and are minimally affected by the PD-1/PD-L1 immune evasion axis in GBM.

Keywords:  NK cell; PD-1; PD-L1; glioblastoma

DOI:  https://doi.org/10.3390/ijms22189975
Sci Rep. 2021 Oct 01. 11(1): 19550

A vascularized tumoroid model for human glioblastoma angiogenesis.

Agavi Stavropoulou Tatla, Alexander W Justin, Colin Watts, Athina E Markaki.

Glioblastoma (GBM) angiogenesis is critical for tumor growth and recurrence, making it a compelling therapeutic target. Here, a disease-relevant, vascularized tumoroid in vitro model with stem-like features and stromal surrounds is reported. The model is used to recapitulate how individual components of the GBM's complex brain microenvironment such as hypoxia, vasculature-related stromal cells and growth factors support GBM angiogenesis. It is scalable, tractable, cost-effective and can be used with biologically-derived or biomimetic matrices. Patient-derived primary GBM cells are found to closely participate in blood vessel formation in contrast to a GBM cell line containing differentiated cells. Exogenous growth factors amplify this effect under normoxia but not at hypoxia suggesting that a significant amount of growth factors is already being produced under hypoxic conditions. Under hypoxia, primary GBM cells strongly co-localize with umbilical vein endothelial cells to form sprouting vascular networks, which has been reported to occur in vivo. These findings demonstrate that our 3D tumoroid in vitro model exhibits biomimetic attributes that may permit its use as a preclinical model in studying microenvironment cues of tumor angiogenesis.

DOI: https://doi.org/10.1038/s41598-021-98911-y
Int J Clin Oncol. 2021 Sep 29.

Efficacy and safety of nivolumab in Japanese patients with first recurrence of glioblastoma: an open-label, non-comparative study.

Tomokazu Aoki, Naoki Kagawa, Kazuhiko Sugiyama, Toshihiko Wakabayashi, Yoshiki Arakawa, Shigeru Yamaguchi, Shota Tanaka, Eiichi Ishikawa, Yoshihiro Muragaki, Motoo Nagane, Mitsutoshi Nakada, Satoshi Suehiro, Nobuhiro Hata, Junichiro Kuroda, Yoshitaka Narita, Yukihiko Sonoda, Yasuo Iwadate, Manabu Natsumeda, Yoichi Nakazato, Hironobu Minami, Yuki Hirata, Shunsuke Hagihara, Ryo Nishikawa.

  BACKGROUND: An open-label, non-comparative study assessed the efficacy and safety of nivolumab in Japanese patients with first recurrence glioblastoma.METHODS: Patients with first recurrence of histologically confirmed World Health Organization Grade IV glioma, after treatment with temozolomide and radiotherapy, received nivolumab 3 mg/kg every 2 weeks until confirmed disease progression (Response Assessment in Neuro-Oncology criteria) or toxicity. Primary endpoint was 1-year overall survival rate assessed by Bayesian approach. The prespecified efficacy criterion was that the Bayesian posterior probability threshold for exceeding the 1-year overall survival of bevacizumab (34.5%) from the Japanese phase 2 study (JO22506) would be 93%.
RESULTS: Of the 50 enrolled patients, 44 (88.0%) had recurrent malignant glioma (glioblastoma, gliosarcoma), and of these, 26 (59.1%) had at least one measurable lesion at baseline. The Bayesian posterior mean 1-year overall survival (90% Bayesian credible intervals) with nivolumab was 54.4% (42.27-66.21), and the Bayesian posterior probability of exceeding the threshold of the 1-year overall survival rate of bevacizumab (34.5%) was 99.7%. Median (90% confidence interval) overall and progression-free survival was 13.1 (10.4-17.7) and 1.5 (1.4-1.5) months, respectively. One partial response was observed (objective response rate 1/26 evaluable patients [3.8%]). Treatment-related adverse event rates were 14.0% for Grade 3-4 and 2.0% for Grade 5; most adverse events resolved and were manageable.
CONCLUSIONS: The 1-year overall survival with nivolumab monotherapy in Japanese patients with glioblastoma met the prespecified efficacy criterion. The safety profile of nivolumab was consistent with that observed in other tumor types.
CLINICAL TRIAL REGISTRATION: JapicCTI-152967.

Keywords:  Bayesian approach; Bevacizumab; Clinical Trial; Glioblastoma; Nivolumab; Phase II; Programmed cell death

DOI:  https://doi.org/10.1007/s10147-021-02028-1
Clin Cancer Res. 2021 Sep 30. pii: clincanres.0374.2021. [Epub ahead of print]

A Modified Nucleoside 6-thio-2'-deoxyguanosine Exhibits Anti-tumor Activity in Gliomas.

Shengnan Yu, Shiyou Wei, Milan Savani, Xiang Lin, Kuang Du, Ilgen Mender, Silvia Siteni, Themistoklis Vasilopoulos, Zachary J Reitman, Yin Ku, Di Wu, Hao Liu, Meng Tian, Yaohui Chen, Marilyne Labrie, Casey M Charbonneau, Eric Sugarman, Michelle Bowie, Seethalakshmi Hariharan, Matthew Waitkus, Wen Jiang, Roger E McLendon, Edward Pan, Mustafa Khasraw, Kyle M Walsh, Yiling Lu, Meenhard Herlyn, Gordon Mills, Utz Herbig, Zhi Wei, Stephen T Keir, Keith Flaherty, Lunxu Liu, Kongming Wu, Jerry W Shay, Kalil Abdullah, Gao Zhang, David M Ashley.

PURPOSE: To investigate the therapeutic role of a novel telomere-directed inhibitor, 6-thio-2'-deoxyguanosine (THIO) in gliomas both in vitro and in vivo Experimental Design: A panel of human and mouse glioma cell lines were used to test therapeutic efficacy of THIO using cell viability assays, flow cytometric analyses and immunofluorescence. Integrated analyses of RNA sequencing and reverse phase protein array data revealed the potential anti-tumor mechanisms of THIO. Four patient-derived xenografts (PDX), two patient-derived organoid (PDOs) and two xenografts of human glioma cell lines were used to further investigate the therapeutic efficacy of THIO.RESULTS: THIO was effective in the majority of human and mouse glioma cell lines with no obvious toxicity against normal astrocytes. THIO as a monotherapy demonstrated efficacy in three glioma cell lines that had acquired resistance to TMZ. In addition, THIO showed efficacy in 4 human glioma cell lines grown as neurospheres by inducing apoptotic cell death. Mechanistically, THIO induced telomeric DNA damage not only in glioma cell lines but also in PDX tumor specimens. Integrated computational analyses of transcriptomic and proteomic data indicated that THIO significantly inhibited cell invasion, stem cell and proliferation pathways while triggering DNA damage and apoptosis. Importantly, THIO significantly decreased tumor proliferation in two PDO models and reduced the tumor size of a GBM xenograft and a PDX model.
CONCLUSIONS: The current study established the therapeutic role of THIO in primary and recurrent gliomas and revealed the acute induction of telomeric DNA damage as a primary anti-tumor mechanism of THIO in gliomas.

DOI: https://doi.org/10.1158/1078-0432.CCR-21-0374
Neuro Oncol. 2021 Sep 28. pii: noab229. [Epub ahead of print]

Extracellular vesicles: the key for precision medicine in glioblastoma.

Massimiliano Del Bene, Daniela Osti, Stefania Faletti, Galina V Beznousenko, Francesco DiMeco, Giuliana Pelicci.

  Glioblastoma (GBM) represents the most aggressive and lethal disease of the central nervous system. Diagnosis is delayed following the occurrence of symptoms, and treatment is based on standardized approaches that are unable to cope with its heterogeneity, mutability, and invasiveness. The follow-up of patients relies on burdensome schedules for magnetic resonance imaging (MRI). However, to personalize treatment, biomarkers and liquid biopsy still represent unmet clinical needs. Extracellular vesicles (EVs) may be the key to revolutionize the entire process of care for patients with GBM. EVs can be collected noninvasively (e.g., blood) and impressively possess multilayered information, which is constituted by their concentration and molecular cargo. EV-based liquid biopsy may facilitate GBM diagnosis and enable the implementation of personalized treatment, resulting in customized care for each patient and for each analyzed time point of the disease, thereby tackling the distinctive heterogeneity and mutability of GBM that confounds effective treatment. Herein, we discuss the limitations of current GBM treatment options and the rationale behind the need for personalized care. We also review the evidence supporting GBM-associated EVs as a promising tool capable of fulfilling the still unmet clinical need for effective and timely personalized care of patients with GBM.

Keywords:  biomarker; extracellular vesicles; glioblastoma; liquid biopsy

DOI:  https://doi.org/10.1093/neuonc/noab229
Cells. 2021 Aug 31. pii: 2257. [Epub ahead of print]10(9):

The Interplay between Glioblastoma and Its Microenvironment.

Mark Dapash, David Hou, Brandyn Castro, Catalina Lee-Chang, Maciej S Lesniak.

  GBM is the most common primary brain tumor in adults, and the aggressive nature of this tumor contributes to its extremely poor prognosis. Over the years, the heterogeneous and adaptive nature of GBM has been highlighted as a major contributor to the poor efficacy of many treatments including various immunotherapies. The major challenge lies in understanding and manipulating the complex interplay among the different components within the tumor microenvironment (TME). This interplay varies not only by the type of cells interacting but also by their spatial distribution with the TME. This review highlights the various immune and non-immune components of the tumor microenvironment and their consequences f the efficacy of immunotherapies. Understanding the independent and interdependent aspects of the various sub-populations encapsulated by the immune and non-immune components will allow for more targeted therapies. Meanwhile, understanding how the TME creates and responds to different environmental pressures such as hypoxia may allow for other multimodal approaches in the treatment of GBM. Ultimately, a better understanding of the GBM TME will aid in the development and advancement of more effective treatments and in improving patient outcomes.

Keywords:  blood-brain-barrier; glioblastoma; immune cells; immunosuppression; microenvironment; regulatory T cells; tumor-associated myeloid cells

DOI:  https://doi.org/10.3390/cells10092257
Neurooncol Adv. 2021 Jan-Dec;3(1):3(1): vdab103

Generation, characterization, and drug sensitivities of 12 patient-derived IDH1-mutant glioma cell cultures.

Cassandra Verheul, Ioannis Ntafoulis, Trisha V Kers, Youri Hoogstrate, Pier G Mastroberardino, Sander Barnhoorn, César Payán-Gómez, Romain Tching Chi Yen, Eduard A Struys, Stijn L W Koolen, Clemens M F Dirven, Sieger Leenstra, Pim J French, Martine L M Lamfers.

  Background: Mutations of the isocitrate dehydrogenase (IDH) gene occur in over 80% of low-grade gliomas and secondary glioblastomas. Despite considerable efforts, endogenous in vitro IDH-mutated glioma models remain scarce. Availability of these models is key for the development of new therapeutic interventions.Methods: Cell cultures were established from fresh tumor material and expanded in serum-free culture media. D-2-Hydroxyglutarate levels were determined by mass spectrometry. Genomic and transcriptomic profiling were carried out on the Illumina Novaseq platform, methylation profiling was performed with the Infinium MethylationEpic BeadChip array. Mitochondrial respiration was measured with the Seahorse XF24 Analyzer. Drug screens were performed with an NIH FDA-approved anti-cancer drug set and two IDH-mutant specific inhibitors.
Results: A set of twelve patient-derived IDHmt cell cultures was established. We confirmed high concordance in driver mutations, copy numbers and methylation profiles between the tumors and derived cultures. Homozygous deletion of CDKN2A/B was observed in all cultures. IDH-mutant cultures had lower mitochondrial reserve capacity. IDH-mutant specific inhibitors did not affect cell viability or global gene expression. Screening of 107 FDA-approved anti-cancer drugs identified nine compounds with potent activity against IDHmt gliomas, including three compounds with favorable pharmacokinetic characteristics for CNS penetration: teniposide, omacetaxine mepesuccinate, and marizomib.
Conclusions: Our twelve IDH-mutant cell cultures show high similarity to the parental tissues and offer a unique tool to study the biology and drug sensitivities of high-grade IDHmt gliomas in vitro. Our drug screening studies reveal lack of sensitivity to IDHmt inhibitors, but sensitivity to a set of nine available anti-cancer agents.

Keywords:  IDH1; drug repurposing; glioma; patient-derived cell culture; preclinical models

DOI:  https://doi.org/10.1093/noajnl/vdab103
Curr Opin Neurol. 2021 Sep 27.

Cancer stem cells in gliomas: evolving concepts and therapeutic implications.

Sheila Alcantara Llaguno, Luis F Parada.

PURPOSE OF REVIEW: Cancer stem cells (CSCs) have been implicated in the hierarchical heterogeneity and treatment resistance of hematologic and solid tumor malignancies, including gliomas, for several decades now but their therapeutic targeting has not been fully realized. Recent studies have uncovered deeper layers of CSC complexity, related to developmental origins, plasticity, cellular states, and interface with the microenvironment.RECENT FINDINGS: Sequencing and in-vivo lineage-tracing studies in mouse and patient-derived models show evidence of stem and progenitor origin of glioma, at the same time that genomic studies show a relatedness of glioma CSCs with radial glia. The spate of single-cell sequencing analyses demonstrates the diversity of transcriptional cellular states, which are susceptible to transitions, indicating the plasticity of glioma CSCs. The evolution of glioma CSCs and their interactions with niche cells play important roles in CSC treatment resistance and immune evasion, with epigenetic modulation as one of the emerging mechanisms.
SUMMARY: To harness the potential of CSCs for clinical application, there is urgent need to investigate their complex nature and myriad interactions, to better understand the contribution of these self-renewing, stem-like cancer cells in the pathogenesis and therapy resistance of malignant brain tumors.

DOI: https://doi.org/10.1097/WCO.0000000000000994
Nat Genet. 2021 Sep 30.

Epigenetic encoding, heritability and plasticity of glioma transcriptional cell states.

Ronan Chaligne, Federico Gaiti, Dana Silverbush, Joshua S Schiffman, Hannah R Weisman, Lloyd Kluegel, Simon Gritsch, Sunil D Deochand, L Nicolas Gonzalez Castro, Alyssa R Richman, Johanna Klughammer, Tommaso Biancalani, Christoph Muus, Caroline Sheridan, Alicia Alonso, Franco Izzo, Jane Park, Orit Rozenblatt-Rosen, Aviv Regev, Mario L Suvà, Dan A Landau.

Single-cell RNA sequencing has revealed extensive transcriptional cell state diversity in cancer, often observed independently of genetic heterogeneity, raising the central question of how malignant cell states are encoded epigenetically. To address this, here we performed multiomics single-cell profiling-integrating DNA methylation, transcriptome and genotype within the same cells-of diffuse gliomas, tumors characterized by defined transcriptional cell state diversity. Direct comparison of the epigenetic profiles of distinct cell states revealed key switches for state transitions recapitulating neurodevelopmental trajectories and highlighted dysregulated epigenetic mechanisms underlying gliomagenesis. We further developed a quantitative framework to directly measure cell state heritability and transition dynamics based on high-resolution lineage trees in human samples. We demonstrated heritability of malignant cell states, with key differences in hierarchal and plastic cell state architectures in IDH-mutant glioma versus IDH-wild-type glioblastoma, respectively. This work provides a framework anchoring transcriptional cancer cell states in their epigenetic encoding, inheritance and transition dynamics.

DOI: https://doi.org/10.1038/s41588-021-00927-7
Cancer J. 2021 Sep-Oct 01;27(5):27(5): 379-385

DNA Damage Response in Glioblastoma: Mechanism for Treatment Resistance and Emerging Therapeutic Strategies.

Alipi Bonm, Santosh Kesari.

ABSTRACT: Glioblastoma (GBM) is an intrinsically treatment-resistant tumor and has been shown to upregulate DNA damage response (DDR) components after treatment. DNA damage response signaling mediates treatment resistance by promoting cell cycle arrest in order to allow for DNA damage repair and avoid mitotic catastrophe. Therefore, targeting the DDR pathway is an attractive strategy to combat treatment resistance in GBM. In this review, we discuss the different DDR pathways and then summarize the current preclinical evidence for DDR inhibitors in GBM, as well as completed and ongoing clinical trials.

DOI: https://doi.org/10.1097/PPO.0000000000000540
Cells. 2021 Aug 31. pii: 2264. [Epub ahead of print]10(9):

Single-Cell Omics in Dissecting Immune Microenvironment of Malignant Gliomas-Challenges and Perspectives.

Bozena Kaminska, Natalia Ochocka, Pawel Segit.

  Single-cell technologies allow precise identification of tumor composition at the single-cell level, providing high-resolution insights into the intratumoral heterogeneity and transcriptional activity of cells in the tumor microenvironment (TME) that previous approaches failed to capture. Malignant gliomas, the most common primary brain tumors in adults, are genetically heterogeneous and their TME consists of various stromal and immune cells playing an important role in tumor progression and responses to therapies. Previous gene expression or immunocytochemical studies of immune cells infiltrating TME of malignant gliomas failed to dissect their functional phenotypes. Single-cell RNA sequencing (scRNA-seq) and cytometry by time-of-flight (CyTOF) are powerful techniques allowing quantification of whole transcriptomes or >30 protein targets in individual cells. Both methods provide unprecedented resolution of TME. We summarize the findings from these studies and the current state of knowledge of a functional diversity of immune infiltrates in malignant gliomas with different genetic alterations. A precise definition of functional phenotypes of myeloid and lymphoid cells might be essential for designing effective immunotherapies. Single-cell omics studies have identified crucial cell subpopulations and signaling pathways that promote tumor progression, influence patient survival or make tumors vulnerable to immunotherapy. We anticipate that the widespread usage of single-cell omics would allow rational design of oncoimmunotherapeutics.

Keywords:  glioma associated microglia/macrophages; glioma heterogeneity; immunosuppression; immunotherapy; malignant gliomas; mass cytometry; single-cell RNA sequencing; tumor infiltrating lymphocytes

DOI:  https://doi.org/10.3390/cells10092264
Cells. 2021 Sep 07. pii: 2342. [Epub ahead of print]10(9):

Applications of CRISPR-Cas9 Technology to Genome Editing in Glioblastoma Multiforme.

Nadia Al-Sammarraie, Swapan K Ray.

  Glioblastoma multiforme (GBM) is an aggressive malignancy of the brain and spinal cord with a poor life expectancy. The low survivability of GBM patients can be attributed, in part, to its heterogeneity and the presence of multiple genetic alterations causing rapid tumor growth and resistance to conventional therapy. The Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-CRISPR associated (Cas) nuclease 9 (CRISPR-Cas9) system is a cost-effective and reliable gene editing technology, which is widely used in cancer research. It leads to novel discoveries of various oncogenes that regulate autophagy, angiogenesis, and invasion and play important role in pathogenesis of various malignancies, including GBM. In this review article, we first describe the principle and methods of delivery of CRISPR-Cas9 genome editing. Second, we summarize the current knowledge and major applications of CRISPR-Cas9 to identifying and modifying the genetic regulators of the hallmark of GBM. Lastly, we elucidate the major limitations of current CRISPR-Cas9 technology in the GBM field and the future perspectives. CRISPR-Cas9 genome editing aids in identifying novel coding and non-coding transcriptional regulators of the hallmarks of GBM particularly in vitro, while work using in vivo systems requires further investigation.

Keywords:  CRISPR-Cas9 genome editing; angiogenesis; apoptosis; autophagy; cell invasion and migration; glioblastoma multiforme (GBM); proliferation

DOI:  https://doi.org/10.3390/cells10092342
Radiat Oncol. 2021 Sep 28. 16(1): 191

Bench to bedside radiosensitizer development strategy for newly diagnosed glioblastoma.

Charlotte Degorre, Philip Tofilon, Kevin Camphausen, Peter Mathen.

  Glioblastoma is the most common primary brain malignancy and carries with it a poor prognosis. New agents are urgently needed, however nearly all Phase III trials of GBM patients of the past 25 years have failed to demonstrate improvement in outcomes. In 2019, the National Cancer Institute Clinical Trials and Translational Research Advisory Committee (CTAC) Glioblastoma Working Group (GBM WG) identified 5 broad areas of research thought to be important in the development of new herapeutics for GBM. Among those was optimizing radioresponse for GBM in situ. One such strategy to increase radiation efficacy is the addition of a radiosensitizer to improve the therapeutic ratio by enhancing tumor sensitivity while ideally having minimal to no effect on normal tissue. Historically the majority of trials using radiosensitizers have been unsuccessful, but they provide important guidance in what is required to develop agents more efficiently. Improved target selection is essential for a drug to provide maximal benefit, and once that target is identified it must be validated through pre-clinical studies. Careful selection of appropriate in vitro and in vivo models to demonstrate increased radiosensitivity and suitable bioavailability are then necessary to prove that a drug warrants advancement to clinical investigation. Once investigational agents are validated pre-clinically, patient trials require consistency both in terms of planning study design as well as reporting efficacy and toxicity in order to assess the potential benefit of the drug. Through this paper we hope to outline strategies for developing effective radiosensitizers against GBM using as models the examples of XPO1 inhibitors and HDAC inhibitors developed from our own lab.

Keywords:  Glioblastoma; Pre-clinical/clinical studies; Radiosensitizers

DOI:  https://doi.org/10.1186/s13014-021-01918-y
Cancer J. 2021 Sep-Oct 01;27(5):27(5): 410-415

Toward the Next Generation of High-Grade Glioma Clinical Trials in the Era of Precision Medicine.

Rifaquat Rahman.

ABSTRACT: In the era of precision medicine, there is a desire to harness our improved understanding of genomic and molecular underpinnings of gliomas to develop therapies that can be tailored to individual patients and tumors. With the rapid development of novel therapies, there has been a growing need to develop smart clinical trials that are designed to efficiently test promising agents, identify therapies likely to benefit patients, and discard ineffective therapies. We review clinical trial design in gliomas and developments designed to address the unique challenges of precision medicine. To provide an overview of this topic, we examine considerations for endpoints and response assessment, biomarkers, and novel clinical trial designs such as adaptive platform trials in the testing of new therapies for glioma patients.

DOI: https://doi.org/10.1097/PPO.0000000000000549
Nat Genet. 2021 Sep 30.

Single-cell multimodal glioma analyses identify epigenetic regulators of cellular plasticity and environmental stress response.

Kevin C Johnson, Kevin J Anderson, Elise T Courtois, Amit D Gujar, Floris P Barthel, Frederick S Varn, Diane Luo, Martine Seignon, Eunhee Yi, Hoon Kim, Marcos R H Estecio, Dacheng Zhao, Ming Tang, Nicholas E Navin, Rahul Maurya, Chew Yee Ngan, Niels Verburg, Philip C de Witt Hamer, Ketan Bulsara, Michael L Samuels, Sunit Das, Paul Robson, Roel G W Verhaak.

Glioma intratumoral heterogeneity enables adaptation to challenging microenvironments and contributes to therapeutic resistance. We integrated 914 single-cell DNA methylomes, 55,284 single-cell transcriptomes and bulk multi-omic profiles across 11 adult IDH mutant or IDH wild-type gliomas to delineate sources of intratumoral heterogeneity. We showed that local DNA methylation disorder is associated with cell-cell DNA methylation differences, is elevated in more aggressive tumors, links with transcriptional disruption and is altered during the environmental stress response. Glioma cells under in vitro hypoxic and irradiation stress increased local DNA methylation disorder and shifted cell states. We identified a positive association between genetic and epigenetic instability that was supported in bulk longitudinally collected DNA methylation data. Increased DNA methylation disorder associated with accelerated disease progression and recurrently selected DNA methylation changes were enriched for environmental stress response pathways. Our work identified an epigenetically facilitated adaptive stress response process and highlights the importance of epigenetic heterogeneity in shaping therapeutic outcomes.

DOI: https://doi.org/10.1038/s41588-021-00926-8
Cancer J. 2021 Sep-Oct 01;27(5):27(5): 386-394

Clinical Targeting of Altered Metabolism in High-Grade Glioma.

Andrew J Scott, Costas A Lyssiotis, Daniel R Wahl.

ABSTRACT: High-grade gliomas are among the deadliest of all cancers despite standard treatments, and new therapeutic strategies are needed to improve patient outcome. Targeting the altered metabolic state of tumors with traditional chemotherapeutic agents has a history of success, and our increased understanding of cellular metabolism in the past 2 decades has reinvigorated the concept of novel metabolic therapies in brain tumors. Here we highlight metabolic alterations in advanced gliomas and their translation into clinical trials using both novel agents and already established drugs repurposed for cancer treatment in an effort to improve outcome for these deadly diseases.

DOI: https://doi.org/10.1097/PPO.0000000000000550
Front Immunol. 2021 ;12 729336

Filamentous Bacteriophage-A Powerful Carrier for Glioma Therapy.

Yicun Wang, Jiyao Sheng, Jin Chai, Cuilin Zhu, Xin Li, Wei Yang, Ranji Cui, Tongtong Ge.

  Glioma is a life-threatening malignant tumor. Resistance to traditional treatments and tumor recurrence present major challenges in treating and managing this disease, consequently, new therapeutic strategies must be developed. Crossing the blood-brain barrier (BBB) is another challenge for most drug vectors and therapy medications. Filamentous bacteriophage can enter the brain across the BBB. Compared to traditional drug vectors, phage-based drugs offer thermodynamic stability, biocompatibility, homogeneity, high carrying capacity, self-assembly, scalability, and low toxicity. Tumor-targeting peptides from phage library and phages displaying targeting peptides are ideal drug delivery agents. This review summarized recent studies on phage-based glioma therapy and shed light on the developing therapeutics phage in the personalized treatment of glioma.

Keywords:  BBB; BBTB; antibody; filamentous bacteriophage; glioma; target peptide

DOI:  https://doi.org/10.3389/fimmu.2021.729336
Sci Adv. 2021 Oct;7(40): eabh3243

G-CSF secreted by mutant IDH1 glioma stem cells abolishes myeloid cell immunosuppression and enhances the efficacy of immunotherapy.

Mahmoud S Alghamri, Brandon L McClellan, Ruthvik P Avvari, Rohit Thalla, Stephen Carney, Margaret S Hartlage, Santiago Haase, Maria Ventosa, Ayman Taher, Neha Kamran, Li Zhang, Syed Mohd Faisal, Felipe J Núñez, María Belén Garcia-Fabiani, Wajd N Al-Holou, Daniel Orringer, Shawn Hervey-Jumper, Jason Heth, Parag G Patil, Karen Eddy, Sofia D Merajver, Peter J Ulintz, Joshua Welch, Chao Gao, Jialin Liu, Gabriel Núñez, Dolores Hambardzumyan, Pedro R Lowenstein, Maria G Castro.

[Figure: see text].

DOI: https://doi.org/10.1126/sciadv.abh3243
Cancer J. 2021 Sep-Oct 01;27(5):27(5): 353-363

Precision Radiotherapy for Gliomas: Implementing Novel Imaging Biomarkers to Improve Outcomes With Patient-Specific Therapy.

Michael Connor, Michelle M Kim, Yue Cao, Jona Hattangadi-Gluth.

ABSTRACT: Gliomas are the most common primary brain cancer, yet are extraordinarily challenging to treat because they can be aggressive and infiltrative, locally recurrent, and resistant to standard treatments. Furthermore, the treatments themselves, including radiation therapy, can affect patients' neurocognitive function and quality of life. Noninvasive imaging is the standard of care for primary brain tumors, including diagnosis, treatment planning, and monitoring for treatment response. This article explores the ways in which advanced imaging has and will continue to transform radiation treatment for patients with gliomas, with a focus on cognitive preservation and novel biomarkers, as well as precision radiotherapy and treatment adaptation. Advances in novel imaging techniques continue to push the field forward, to more precisely guided treatment planning, radiation dose escalation, measurement of therapeutic response, and understanding of radiation-associated injury.

DOI: https://doi.org/10.1097/PPO.0000000000000546
Nat Rev Cancer. 2021 Sep 28.

Glial and myeloid heterogeneity in the brain tumour microenvironment.

Brian M Andersen, Camilo Faust Akl, Michael A Wheeler, E Antonio Chiocca, David A Reardon, Francisco J Quintana.

Brain cancers carry bleak prognoses, with therapeutic advances helping only a minority of patients over the past decade. The brain tumour microenvironment (TME) is highly immunosuppressive and differs from that of other malignancies as a result of the glial, neural and immune cell populations that constitute it. Until recently, the study of the brain TME was limited by the lack of methods to de-convolute this complex system at the single-cell level. However, novel technical approaches have begun to reveal the immunosuppressive and tumour-promoting properties of distinct glial and myeloid cell populations in the TME, identifying new therapeutic opportunities. Here, we discuss the immune modulatory functions of microglia, monocyte-derived macrophages and astrocytes in brain metastases and glioma, highlighting their disease-associated heterogeneity and drawing from the insights gained by studying these malignancies and other neurological disorders. Lastly, we consider potential approaches for the therapeutic modulation of the brain TME.

DOI: https://doi.org/10.1038/s41568-021-00397-3