Diffuse midline glioma: review of epigenetics

Bibliometric and visualization analysis in the field of epigenetics and glioma (2009-2024)

Introduction

Glioma represents the most prevalent primary malignant tumor in the central nervous system, a deeper understanding of the underlying molecular mechanisms driving glioma is imperative for guiding future treatment strategies. Emerging evidence has implicated a close relationship between glioma development and epigenetic regulation. However, there remains a significant lack of comprehensive summaries in this domain. This study aims to analyze epigenetic publications pertaining to gliomas from 2009 to 2024 using bibliometric methods, consolidate the extant research, and delineate future prospects for investigation in this critical area.

Methods

For the purpose of this study, publications spanning the years 2009 to 2024 were extracted from the esteemed Web of Science Core Collection (WoSCC) database. Utilizing advanced visualization tools such as CiteSpace and VOSviewer, comprehensive data pertaining to various aspects including countries, authors, author co-citations, countries/regions, institutions, journals, cited literature, and keywords were systematically visualized and analyzed.

Results

A thorough analysis was conducted on a comprehensive dataset consisting of 858 publications, which unveiled a discernible trend of steady annual growth in research output within this specific field. The nations of the United States, China, and Germany emerged as the foremost contributors to this research domain. It is noteworthy that von Deimling A and the Helmholtz Association were distinguished as prominent authors and institutions, respectively, in this corpus of literature. A rigorous keyword search and subsequent co-occurrence analysis were executed, ultimately leading to the identification of seven distinct clusters: "epigenetic regulation", "DNA repair", "DNA methylation", "brain tumors", "diffuse midline glioma (DMG)", "U-87 MG" and "epigenomics". Furthermore, an intricate cluster analysis revealed that the primary foci of research within this field were centered around the exploration of glioma pathogenesis and the development of corresponding treatment strategies.

Conclusion

This article underscores the prevailing trends and hotspots in glioma epigenetics, offering invaluable insights that can guide future research endeavors. The investigation of epigenetic mechanisms primarily centers on DNA modification, non-coding RNAs (ncRNAs), and histone modification. Furthermore, the pursuit of overcoming temozolomide (TMZ) resistance and the exploration of diverse emerging therapeutic strategies have emerged as pivotal avenues for future research within the field of glioma epigenetics.

Therapeutic targeting of differentiation-state dependent metabolic vulnerabilities in diffuse midline glioma

H3K27M diffuse midline gliomas (DMG), including diffuse intrinsic pontine gliomas (DIPG), exhibit cellular heterogeneity comprising less-differentiated oligodendrocyte precursors (OPC)-like stem cells and more differentiated astrocyte (AC)-like cells. Here, we establish in vitro models that recapitulate DMG-OPC-like and AC-like phenotypes and perform transcriptomics, metabolomics, and bioenergetic profiling to identify metabolic programs in the different cellular states. We then define strategies to target metabolic vulnerabilities within specific tumor populations. We show that AC-like cells exhibit a mesenchymal phenotype and are sensitized to ferroptotic cell death. In contrast, OPC-like cells upregulate cholesterol biosynthesis, have diminished mitochondrial oxidative phosphorylation (OXPHOS), and are accordingly more sensitive to statins and OXPHOS inhibitors. Additionally, statins and OXPHOS inhibitors show efficacy and extend survival in preclinical orthotopic models established with stem-like H3K27M DMG cells. Together, this study demonstrates that cellular subtypes within DMGs harbor distinct metabolic vulnerabilities that can be uniquely and selectively targeted for therapeutic gain.

State of the art in pediatric nanomedicines

In recent years, the continuous development of innovative nanopharmaceuticals is expanding their biomedical and clinical applications. Nanomedicines are being revolutionized to circumvent the limitations of unbound therapeutic agents as well as overcome barriers posed by biological interfaces at the cellular, organ, system, and microenvironment levels. In many ways, the use of nanoconfigured delivery systems has eased challenges associated with patient differences, and in our opinion, this forms the foundation for their potential usefulness in developing innovative medicines and diagnostics for special patient populations. Here, we present a comprehensive review of nanomedicines specifically designed and evaluated for disease management in the pediatric population. Typically, the pediatric population has distinguishing needs relative to those of adults majorly because of their constantly growing bodies and age-related physiological changes, which often need specialized drug formulation interventions to provide desirable therapeutic effects and outcomes. Besides, child-centric drug carriers have unique delivery routes, dosing flexibility, organoleptic properties (e.g., taste, flavor), and caregiver requirements that are often not met by traditional formulations and can impact adherence to therapy. Engineering pediatric medicines as nanoconfigured structures can potentially resolve these limitations stemming from traditional drug carriers because of their unique capabilities. Consequently, researchers from different specialties relentlessly and creatively investigate the usefulness of nanomedicines for pediatric disease management as extensively captured in this compilation. Some examples of nanomedicines covered include nanoparticles, liposomes, and nanomicelles for cancer; solid lipid and lipid-based nanostructured carriers for hypertension; self-nanoemulsifying lipid-based systems and niosomes for infections; and nanocapsules for asthma pharmacotherapy.

National trends in the treatment of adult diffuse midline gliomas: a rare clinical scenario

PURPOSE

Diffuse midline gliomas (DMG) include all midline gliomas with a point mutation to the histone H3 gene resulting in the substitution of a lysine with a methionine (K27M). These tumors are classified as World Health Organization grade 4 with a mean survival between 9- and 19-months following diagnosis. There is currently no standard of care for DMG, and palliative radiation therapy has been proven to only extend survival by months. Our current study aims to report current treatment trends and predictors of the overall survival of DMG.

METHODS

We searched the National Cancer Database for adult patients treated for DMG from 2016 to 2020. Patients were required to have been treated with primary radiation directed at the brain with or without concurrent chemotherapy. Univariable and multivariable Cox regressions were used to determine predictors of overall survival.

RESULTS

Of the 131 patients meeting the inclusion criteria, 113 (86%) received radiation and chemotherapy. Based on multivariable Cox regression, significant predictors of survival were Charlson-Deyo comorbidity index and race. Patients with a Charlson-Deyo score of 1 had 2.72 times higher odds of mortality than those with a score of 0. Patients not identifying as White or Black had 2.67 times higher odds of mortality than those identifying as White. The median survival for all patients was 19 months.

CONCLUSIONS

Despite being considered ineffective, chemotherapy is still administered in most adult patients diagnosed with DMG. Significant predictors of survival were Charlson-Deyo comorbidity index and race.

Elucidation and Pharmacologic Targeting of Master Regulator Dependencies in Coexisting Diffuse Midline Glioma Subpopulations

Diffuse Midline Gliomas (DMGs) are universally fatal, primarily pediatric malignancies affecting the midline structures of the central nervous system. Despite decades of clinical trials, treatment remains limited to palliative radiation therapy. A major challenge is the coexistence of molecularly distinct malignant cell states with potentially orthogonal drug sensitivities. To address this challenge, we leveraged established network-based methodologies to elucidate Master Regulator (MR) proteins representing mechanistic, non-oncogene dependencies of seven coexisting subpopulations identified by single-cell analysis-whose enrichment in essential genes was validated by pooled CRISPR/Cas9 screens. Perturbational profiles of 372 clinically relevant drugs helped identify those able to invert the activity of subpopulation-specific MRs for follow-up in vivo validation. While individual drugs predicted to target individual subpopulations-including avapritinib, larotrectinib, and ruxolitinib-produced only modest tumor growth reduction in orthotopic models, systemic co-administration induced significant survival extension, making this approach a valuable contribution to the rational design of combination therapy.

Prediction of H3K27M alteration in midline gliomas of the brain using radiomics: A multi-institute study

Background

Noninvasive prediction of H3K27M-altered Diffuse midline gliomas is important because of the involvement of deep locations and proximity to eloquent structures. We aim to predict H3K27M alteration in midline gliomas using radiomics features of T2W images.

Methods

Radiomics features extracted from 124 subjects (69 H3K27M-altered/55 H3K27M-wild type). T2W images were resampled to 1 × 1 × 1mm3 voxel size, preprocessed, and normalized for artifact correction, intensity variations. The feature set was normalized and subjected to reduction by variance thresholding, correlation coefficient thresholding, and sequential feature selector. Adaptive synthesis oversampling technique was used to oversample the training data. Random forest classifier (RFC), Decision tree classifier (DTC), and K-nearest neighbors classifier (KNN) were trained over the training dataset and the performance was assessed over the internal test dataset and external test data set (52 subjects: 33 H3K27M-altered/19-H3K27M-wild type).

Results

DTC achieved a validation score of 77.33% (5-fold cross-validation) and an accuracy of 80.64%, 75% on internal and external test datasets. RFC achieved a validation score of 80.7% (5-fold cross-validation) an accuracy of 80.6%, and 73% on internal and external test datasets. DTC achieved a validation score of 78.67% (5-fold cross-validation) an accuracy of 80.64%, and 61.53% on internal and external test datasets. The accuracy score of DTC, RFC, and KNN on the internal test dataset was approximately 80% while on the external test dataset, DTC achieved 75% accuracy, RFC achieved 73% accuracy and KNN achieved 65.1% accuracy.

Conclusions

H3K27M alteration is a potential immunotherapeutic marker and is associated with poor prognosis and radiomics features extracted from conventional T2W-images can help in identifying H3K27M-altered cases non-invasively with high precision.

Classification of Brainstem Gliomas Based on Tumor Microenvironment Status

The inter-tumor heterogeneity of the tumor microenvironment (TME) and how it correlates with clinical profiles and biological characteristics in brainstem gliomas (BSGs) remain unknown, dampening the development of novel therapeutics against BSGs. The TME status was determined with a list of pan-cancer conserved gene expression signatures using a single-sample gene set enrichment analysis (ssGSEA) and was subsequently clustered via consensus clustering. BSGs exhibited a high inter-tumor TME heterogeneity and were classified into four clusters: "immune-enriched, fibrotic", "immune-enriched, non-fibrotic", "fibrotic", and "depleted". The "fibrotic" cluster had a higher proportion of diffuse intrinsic pontine gliomas (p = 0.041), and "PA-like" tumors were more likely to be "immune-enriched, fibrotic" (p = 0.044). The four TME clusters exhibited distinct overall survival (p < 0.001) and independently impacted BSG outcomes. A four-gene panel as well as a radiomics approach were constructed to identify the TME clusters and achieved high accuracy for determining the classification. Together, BSGs exhibited high inter-tumor heterogeneity in the TME and were classified into four clusters with distinct clinical outcomes and tumor biological properties. The TME classification was accurately identified using a four-gene panel that can potentially be examined with the immunohistochemical method and a non-invasive radiomics method, facilitating its clinical application.

A validated prognostic nomogram for patients with H3 K27M-mutant diffuse midline glioma

H3 K27M-mutant diffuse midline glioma (H3 K27M-mt DMG) is a rare, highly invasive tumor with a poor prognosis. The prognostic factors of H3 K27M-mt DMG have not been fully identified, and there is no clinical prediction model for it. This study aimed to develop and validate a prognostic model for predicting the probability of survival in patients with H3 K27M-mt DMG. Patients diagnosed with H3 K27M-mt DMG in the West China Hospital from January 2016 to August 2021 were included. Cox proportional hazard regression was used for survival assessment, with adjustment for known prognostic factors. The final model was established using the patient data of our center as the training cohort and data from other centers for external independent verification. One hundred and five patients were ultimately included in the training cohort, and 43 cases from another institution were used as the validation cohort. The factors influencing survival probability in the prediction model included age, preoperative KPS score, radiotherapy and Ki-67 expression level. The adjusted consistency indices of the Cox regression model in internal bootstrap validation at 6, 12, and 18 months were 0.776, 0.766, and 0.764, respectively. The calibration chart showed high consistency between the predicted and observed results. The discrimination in external verification was 0.785, and the calibration curve showed good calibration ability. We identified the risk factors that affect the prognosis of H3 K27M-mt DMG patients and then established and validated a diagnostic model for predicting the survival probability of these patients.

Radiotherapy and radio-sensitization in H3K27M -mutated diffuse midline gliomas

BACKGROUND

H3^K27M mutated diffuse midline gliomas (DMGs) are extremely aggressive and the leading cause of cancer-related deaths in pediatric brain tumors with 5-year survival <1%. Radiotherapy is the only established adjuvant treatment of H3^K27M DMGs; however, the radio-resistance is commonly observed.

METHODS

We summarized current understandings of the molecular responses of H3^K27M DMGs to radiotherapy and provide crucial insights into current advances in radiosensitivity enhancement.

RESULTS

Ionizing radiation (IR) can mainly inhibit tumor cell growth by inducing DNA damage regulated by the cell cycle checkpoints and DNA damage repair (DDR) system. In H3K27M DMGs, the aberrant genetic and epigenetic changes, stemness genotype, and epithelial-mesenchymal transition (EMT) disrupt the cell cycle checkpoints and DDR system by altering the associated regulatory signaling pathways, which leads to the development of radio-resistance.

CONCLUSIONS

The advances in mechanisms of radio-resistance in H3^K27M  DMGs promote the potential targets to enhance the sensitivity to radiotherapy.

Intratumoral catheter placement in pediatric patients with diffuse midline gliomas

INTRODUCTION

Diffuse midline brainstem gliomas have a poor prognosis and are generally not amenable to surgical resection. Occasionally, palliative surgical procedures can be performed to improve the quality of life of these patients. We describe three patients with solid-cystic brainstem gliomas in whom an Ommaya reservoir catheter was placed to reduce mass effect.

OBJECTIVES

To describe the characteristics, indications for, and operative technique of Ommaya reservoir catheter placement in patients with solid-cystic diffuse midline glioma.

MATERIALS AND METHODS

A review was conducted of the medical records of pediatric patients with solid-cystic diffuse midline glioma H3 K27-altered, treated with an Ommaya reservoir at Hospital J.P. Garrahan between 2014 and 2021 together with a search of the literature.

RESULTS

Three cases of stereotaxic Ommaya placement in solid-cystic diffuse midline gliomas, H3 K27M-altered were identified. After the procedure, clinical improvement and reduction of the size of the tumor cyst size was achieved. No associated complications were seen. At the time of the study, one patient died, and the remaining two patients continued in follow-up at our hospital.

CONCLUSION

We believe that the placement of an intratumoral Ommaya reservoir catheter may be considered a therapeutic option to improve symptoms and quality of life of selected patients with solid-cystic diffuse midline glioma.

DNA Methylation and Histone Modification in Low-Grade Gliomas: Current Understanding and Potential Clinical Targets

Gliomas, the most common type of malignant primary brain tumor, were conventionally classified through WHO Grades I-IV (now 1-4), with low-grade gliomas being entities belonging to Grades 1 or 2. While the focus of the WHO Classification for Central Nervous System (CNS) tumors had historically been on histopathological attributes, the recently released fifth edition of the classification (WHO CNS5) characterizes brain tumors, including gliomas, using an integration of histological and molecular features, including their epigenetic changes such as histone methylation, DNA methylation, and histone acetylation, which are increasingly being used for the classification of low-grade gliomas. This review describes the current understanding of the role of DNA methylation, demethylation, and histone modification in pathogenesis, clinical behavior, and outcomes of brain tumors, in particular of low-grade gliomas. The review also highlights potential diagnostic and/or therapeutic targets in associated cellular biomolecules, structures, and processes. Targeting of MGMT promoter methylation, TET-hTDG-BER pathway, association of G-CIMP with key gene mutations, PARP inhibition, IDH and 2-HG-associated processes, TERT mutation and ARL9-associated pathways, DNA Methyltransferase (DNMT) inhibition, Histone Deacetylase (HDAC) inhibition, BET inhibition, CpG site DNA methylation signatures, along with others, present exciting avenues for translational research. This review also summarizes the current clinical trial landscape associated with the therapeutic utility of epigenetics in low-grade gliomas. Much of the evidence currently remains restricted to preclinical studies, warranting further investigation to demonstrate true clinical utility.

Events in CNS Tumor Pathology Post-2016 WHO CNS: cIMPACT-NOW Updates and Other Advancements: A Comprehensive Review Plus a Summary of the Salient Features of 2021 WHO CNS 5

Introduction

The 2016 World Health Organization Classification (WHO) of Tumors of the Central Nervous System (CNS) represented a major change. It recommended an "integrated diagnosis" comprising histologic and molecular information facilitating a more precise diagnosis of specific CNS tumors. Its goal was to provide greater diagnostic precision and reproducibility resulting in more clinical relevance and predictive value, ultimately leading to better patient care. Advances in molecular classification, mostly resulting from DNA methylation array profiling of CNS tumors, were occurring at a very rapid pace and required more rapid integration into clinical practice.

Methods

cIMPACT-NOW updates and other recent papers plus salient features of 2021 WHO CNS5 in this comprehensive write-up were reviewed.

Results

CNS tumor classification needs to be updated at a rapid pace and mechanisms put into place to guide diagnosticians and clinicians in the interim period if major changes in the classification of tumor types came to light. Recognizing the need to integrate these into clinical practice more rapidly and without inordinate delay, the International Society of Neuropathology (ISN) 2016 sponsored an initiative called cIMPACT-NOW.

Discussion and/or Conclusion

Goal of cIMPACT-NOW was to provide clarification regarding contentious issues arising in the wake of the 2016 WHO CNS update as well as report new advancements in molecular classification of CNS tumors and new tumor entities emerging as a result of these advancements. cIMPACT-NOW updates: It thus laid the foundation for the 5th edition of the WHO Classification of CNS tumors (2021 WHO CNS 5). We have discussed cIMPACT updates in detail in this review. In addition, molecular diagnostics including DNA methylation-based classification of CNS tumors and the practical use of molecular classification in the prognostication and treatment of CNS tumors is discussed. Finally, the salient features of the new CNS tumor classification are summarized.

A comprehensive analysis-based study of triphenyl phosphate-environmental explanation of glioma progression

As BFRs have gradually been banned recently, organophosphorus flame retardants (OPFRs) have been manufactured and used in their place. Although OPFRs are considered the better alternatives to BFRs, many studies have discovered that OPFRs may be associated with various cancers, including prostate cancer, bladder cancer, hepatocellular carcinoma, and colorectal cancer. However, few studies have examined the relationship between OPFRs and gliomas. This study investigated the relationship between triphenyl phosphate (TPP) and glioma using bioinformatics analysis approaches. The comparative toxicogenomics database (CTD) and The Cancer Genome Atlas (TCGA) databases were accessed for TPP-related genes and gene expression data from glioma patients. The Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses show that TPP might be closely related to many pathways. Further, the analysis of protein-protein interactions revealed strong intrinsic relationships between TPP-related genes. In addition, the TPP-based prognostic prediction model demonstrated promising results in predicting the prognosis of patients with gliomas. Several TPP-related genes were closely related to glioma patients' overall survival rates. The proliferation and migration abilities of glioma cells were further demonstrated to be significantly enhanced by TPP. In a bioinformatics analysis, we also discovered that melatonin is highly correlated with the presence of TPP and gliomas. According to the cell proliferation and migration assays, exposure to melatonin and TPP inhibited the ability of glioma cells to invade compared with the TPP group.

Comprehensive analyses reveal the role of histone deacetylase genes in prognosis and immune response in low-grade glioma

Many studies have shown that Histone deacetylases (HDAC) is involved in the occurrence of malignant tumors and regulates the occurrence, proliferation, invasion, and migration of malignant tumors through a variety of signaling pathways. In the present, we explored the role of Histone deacetylases genes in prognosis and immune response in low-grade glioma. Using consensus clustering, we built the new molecular clusters. Using HDAC genes, we constructed and validated the prognostic model in two independent cohort datasets. Patients were divided into high-risk and low-risk groups. Then, we explored the molecular characteristics, clinical characteristics, tumor microenvironment and immune infiltration levels of two clusters and risk groups. Receiver operating characteristic analyses were built for model assessment. We finally detected the expression levels of signature genes between tumor and normal tissues. Low-grade can be separated into two molecular clusters using 11 HDACs genes. Two clusters had different clinical characteristics and prognosis. Nex, we constructed a prognosis model using six HDAC genes (HDAC1, HDAC4, HDAC5, HDAC7, HDAC9, and HDAC10), which was also validated in an independent cohort dataset. Furthermore, multivariate cox regression indicated that the calculated risk score was independently associated with prognosis in low-grade glioma, and risk score can predict the five-year survival probability of low-grade glioma well. High-risk patients can be attributed to multiple complex function and molecular signaling pathways, and the genes alterations of high- and low-risk patients were significantly different. We also found that different survival outcomes of high- and low- risk patients could be involved in the differences of immune filtration level and tumor microenvironment. Subsequently, using signature genes, we identified several small molecular compounds that could be useful for low-grade glioma patients' treatment. Finally, we detected the expression levels of signature genes in tumor tissues. our study uncovers the biology function role of HDAC genes in low-grade glioma. We identified new molecular subtypes and established a prognostic model based on six HDAC genes, which was well applied in two independent cohort data. The regulation of HDAC genes in low-grade glioma involved in multiple molecular function and signaling pathways and immune infiltration levels. Further experiments in vivo and vitro were required to confirm the present findings.

Dynamic analysis of immune status in patients with intracranial germ cell tumor and establishment of an immune risk prognostic model

Introduction

Immune status was evaluated by means of lymphocyte subset counts and immune factors in cancer. This study analyzed the peripheral blood immune index and survival outcomes in intracranial germ cell tumor (iGCT) patients.

Methods

Peripheral blood lymphocyte subset counts and levels of interleukin (IL)-2, IL-4, IL-6, IL-10, tumor necrosis factor (TNF), and interferon-γ (IFN) from 133 iGCT patients were collected and retrospectively analyzed. Their clinical information was extracted from the hospital database, and prognosis was confirmed by telephone visit. Patients (n=11) underwent prospective review and their samples of peripheral blood lymphocytes were verified.

Results

A total of 113 (84.2%) patients received comprehensive treatments, including 96 standard therapy (combination of full course chemotherapy and radiology with or without surgery) and 17 comprehensive but non-standard therapy (either without full course chemotherapy or with non-standard radiotherapy) and 98 (73.7%) reached complete or partial response. T lymphocytes (CD3⁺), cytotoxic T cells (CD3⁺CD8⁺ or Tc), and B lymphocytes (CD19⁺) decreased (p=0.047, p=0.004, and p<0.001, respectively), while activated cytotoxic T lymphocytes (CD8⁺CD25⁺) and IFN increased (p<0.001 and p=0.002, respectively) after treatment. Median survival was 45.33 months, and patients with increased Tc cells and activated Tc cells as well as IFN presented encouraging outcomes (p=0.039, p=0.041, and p=0.017 respectively). Regression analysis showed that non-increased Tc cells and non-increased activated Tc cells were independent factors of poor prognosis (p=0.016, HR=3.96, 95%CI=1.288-12.20; p=0.002, HR=4.37 95%CI= 1.738-10.97). Standard chemo-radiotherapy was independently related to reduced risk of death(p=0.022, HR=0.19, 95%CI=0.044-0.79). Consistence was seen in a nomogram established through retro and prospective studies. An immune risk model indicated the activated group (with both increased activated T cells and IFN levels) had the best prognosis, the mildly activated type with elevated IFN levels had intermediate outcome, and patients with the silent immune status had the worst outcomes (Log rank test, p=0.011).

Conclusion

Implementation of standard comprehensive treatments led to positive responses. Dynamic monitoring of peripheral blood lymphocyte subsets can be used as an auxiliary indicator for prognosis judgment.

Clinical Features and Prognosis of Diffuse Midline Glioma: A Series of 24 Cases

BACKGROUND

Diffuse midline glioma (DMG) which occurs in midline structures and characterized by harboring K27M mutation in genes encoding the histone 3 protein is classified as World Health Organization (WHO) grade IV regardless of histological findings and has a poor prognosis. Nevertheless, because of its relatively rare incidence compared with other high-grade gliomas, a comprehensive description encompassing clinical features and genomic profiles of DMG is still lacking.

METHODS

In this study, we analyzed data of 24 patients who were diagnosed as DMG which was confirmed by surgical specimens in both pediatric and adult patients. We described the clinical outcomes of patients with DMG and their genomic profiles through a retrospective analysis of 24 patients with DMG.

RESULTS

The clinical characteristics of the 24 patients with DMG were analyzed. Ten patients (41%) underwent tumor resection and 14 patients (59%) underwent tumor biopsy. The median overall survival was 10.4 months (95% confidence interval [CI], 8.4 to 12.5) and progression free survival was 3.9 months (95% CI, 2.6 to 5.2). Fifteen patients (62%) were accompanied by hydrocephalus. None of the patient, tumor, or treatment factors had any significant associated with survival. In both immunohistochemistry staining (n=24) and targeted next generation sequencing (n=15), TP53 mutation was the most common genetic mutation (25% and 46%, respectively) found in the patients except alterations in histone 3 protein.

CONCLUSION

Although surgical treatment of patient with DMG does not affect the overall survival prognosis, it can help improve the patient's accompanying neurological symptoms in some limited cases. Hydrocephalus is often accompanied with DMG and treatment for hydrocephalus is often also required. Multidisciplinary therapeutic approach is needed.

Compassionate Treatment of Brainstem Tumors with Boron Neutron Capture Therapy: A Case Series

Brainstem tumors are heterogenous and cancerous glioma tumors arising from the midbrain, pons, and the medulla that are relatively common in children, accounting for 10% to 20% of all pediatric brain tumors. However, the prognosis of aggressive brainstem gliomas remains extremely poor despite aggressive treatment with chemotherapy and radiotherapy. That means there are many life-threatening patients who have exhausted all available treatment options and are beginning to face end-of-life stage. Therefore, the unique properties of highly selective heavy particle irradiation with boron neutron capture therapy (BNCT) may be well suited to prolong the lives of patients with end-stage brainstem gliomas. Herein, we report a case series of life-threatening patients with end-stage brainstem glioma who eligible for Emergency and Compassionate Use, in whom we performed a scheduled two fractions of salvage BNCT strategy with low treatment dosage each time. No patients experienced acute or late adverse events related to BNCT. There were 3 patients who relapsed after two fractionated BNCT treatment, characterized by younger age, lower T/N ratio, and receiving lower treatment dose. Therefore, two fractionated low-dose BNCT may be a promising treatment for end-stage brainstem tumors. For younger patients with low T/N ratios, more fractionated low-dose BNCT should be considered.

Panobinostat in adults with H3 K27M-mutant diffuse midline glioma: a single-center experience

INTRODUCTION

Diffuse midline gliomas (DMG) with the H3 K27M-mutation are a well-described entity with most DMG harboring this mutation, with notable heterogeneity in adults. No therapy has been proven to improve survival in this tumor type. Panobinostat is a histone deacetylase inhibitor that may have therapeutic benefit.

METHODS

We report our retrospective experience with use of panobinostat in adults (> 18 years) with H3 K27M-mutant DMG treated at Mayo Clinic (Rochester) from January 2016 to August 2020, with follow-up until October 2021. Survival was calculated using the Kaplan-Meier method.

RESULTS

4 patients with H3 K27M-mutant glioma were treated with panobinostat as compassionate use. Patients had a median age of 40 years (range 22-62 years) and 2 were female. Tumor location was midline for all patients, spinal cord (n = 2), brainstem (n = 1), and thalamus (n = 1). All tumors were IDH1/IDH2 wildtype. 3 patients received radiotherapy followed by adjuvant panobinostat. All patients had no other pharmacologic therapy utilized prior to or during panobinostat therapy aside from concurrent dexamethasone utilized in 3 patients. No patient experienced a grade 2 or higher (per CTCAE grade) adverse effect. The median overall survival was 42 months, median progression free survival of 19 months, 2 patients were alive at last follow up (both with spinal cord tumors and received radiation). The best response was stable disease in 2 patients and a partial response in 1 patient.

CONCLUSIONS

This is the first report of clinical outcomes of panobinostat in adults with H3 K27M-mutant DMG. We showed that it is well-tolerated at the dosage schedule that we describe, with no serious adverse effects throughout the study period.

Dynamic susceptibility contrast-MRI parameters, ADC values, and the T2-FLAIR mismatch sign are useful to differentiate between H3-mutant and H3-wild-type high-grade midline glioma

OBJECTIVES

Diffuse midline gliomas, H3K27-altered (DMG-A), are malignant gliomas with an unfavorable prognosis. Knowledge of dynamic susceptibility contrast (DSC) MRI findings and imaging differences with high-grade midline glioma without H3K27 alteration (DMG-W) has been limited. We compared the DSC, ADC, and conventional MRI findings between DMG-A and DMG-W.

METHODS

In this single institutional retrospective study, the electronic database of our hospital between June 2015 and May 2021 was searched. Twenty and 17 patients with DMG-A (median, 13 years; range, 3-52 years; 11 females) and DMG-W (median, 40 years; 7-73 years; 9 females), respectively, were found. Normalized relative cerebral blood flow (nrCBF) and normalized corrected relative cerebral blood volume (ncrCBV); normalized maximum, mean, and minimum ADC values; and the prevalence of T2-FLAIR mismatch sign were compared between the two groups using Mann-Whitney U tests and Fisher's exact test.

RESULTS

The nrCBF and ncrCBV were significantly lower in DMG-A compared with DMG-W (nrCBF: median 0.88 [range, 0.19-2.67] vs. 1.47 [range, 0.57-4.90] (p < 0.001); ncrCBV: 1.17 [0.20-2.67] vs. 1.56 [0.60-4.03] (p = 0.008)). Normalized maximum ADC (nADC_max) was significantly higher in DMG-A (median 2.37 [1.25-3.98] vs. 1.95 [1.23-2.77], p = 0.02). T2-FLAIR mismatch sign was significantly more common in DMG-A (11/20 (55.0%) vs. 1/17 (5.9%), p = 0.0017). When at least two of nrCBF < 1.11, nADC_max ≥ 2.48, and T2-FLAIR mismatch sign were positive, the diagnostic performance was the highest with accuracy of 0.81.

CONCLUSION

DSC-MRI parameters, ADC values, and the T2-FLAIR mismatch sign are useful to differentiate between DMG-A and DMG-W.

KEY POINTS

• Diffuse midline glioma, H3K27-altered (DMG-A), showed a significantly lower normalized relative cerebral blood flow and volume compared with H3K27-wild-type counterparts (DMG-W). • T2-fluid-attenuated inversion recovery (FLAIR) mismatch sign was significantly more frequent in DMG-A compared to DMG-W. • Indicators that combined DSC parameters, ADC values, and T2-FLAIR mismatch sign, with or without age, are useful to distinguish the two tumors.

Therapeutic Targets in Diffuse Midline Gliomas-An Emerging Landscape

Simple Summary

Diffuse midline gliomas (DMGs) remain one of the most devastating childhood brain tumour types, for which there is currently no known cure. In this review we provide a summary of the existing knowledge of the molecular mechanisms underlying the pathogenesis of this disease, highlighting current analyses and novel treatment propositions. Together, the accumulation of these data will aid in the understanding and development of more effective therapeutic options for the treatment of DMGs.

Abstract

Diffuse midline gliomas (DMGs) are invariably fatal pediatric brain tumours that are inherently resistant to conventional therapy. In recent years our understanding of the underlying molecular mechanisms of DMG tumorigenicity has resulted in the identification of novel targets and the development of a range of potential therapies, with multiple agents now being progressed to clinical translation to test their therapeutic efficacy. Here, we provide an overview of the current therapies aimed at epigenetic and mutational drivers, cellular pathway aberrations and tumor microenvironment mechanisms in DMGs in order to aid therapy development and facilitate a holistic approach to patient treatment.

Advanced Diagnosis of Glioma by Using Emerging Magnetic Resonance Sequences

Glioma, the most common primary brain tumor in adults, can be difficult to discern radiologically from other brain lesions, which affects surgical planning and follow-up treatment. Recent advances in MRI demonstrate that preoperative diagnosis of glioma has stepped into molecular and algorithm-assisted levels. Specifically, the histology-based glioma classification is composed of multiple different molecular subtypes with distinct behavior, prognosis, and response to therapy, and now each aspect can be assessed by corresponding emerging MR sequences like amide proton transfer-weighted MRI, inflow-based vascular-space-occupancy MRI, and radiomics algorithm. As a result of this novel progress, the clinical practice of glioma has been updated. Accurate diagnosis of glioma at the molecular level can be achieved ahead of the operation to formulate a thorough plan including surgery radical level, shortened length of stay, flexible follow-up plan, timely therapy response feedback, and eventually benefit patients individually.

Chemosensitization of Temozolomide-Resistant Pediatric Diffuse Midline Glioma Using Potent Nanoencapsulated Forms of a N(3)-Propargyl Analogue

The lack of clinical response to the alkylating agent temozolomide (TMZ) in pediatric diffuse midline/intrinsic pontine glioma (DIPG) has been associated with O6-methylguanine-DNA-methyltransferase (MGMT) expression and mismatch repair deficiency. Hence, a potent N(3)-propargyl analogue (N3P) was derived, which not only evades MGMT but also remains effective in mismatch repair deficient cells. Due to the poor pharmacokinetic profile of N3P (t1/2 < 1 h) and to bypass the blood-brain barrier, we proposed convection enhanced delivery (CED) as a method of administration to decrease dose and systemic toxicity. Moreover, to enhance N3P solubility, stability, and sustained distribution in vivo, either it was incorporated into an apoferritin (AFt) nanocage or its sulfobutyl ether β-cyclodextrin complex was loaded into nanoliposomes (Lip). The resultant AFt-N3P and Lip-N3P nanoparticles (NPs) had hydrodynamic diameters of 14 vs 93 nm, icosahedral vs spherical morphology, negative surface charge (-17 vs -34 mV), and encapsulating ∼630 vs ∼21000 N3P molecules per NP, respectively. Both NPs showed a sustained release profile and instant uptake within 1 h incubation in vitro. In comparison to the naked drug, N3P NPs demonstrated stronger anticancer efficacy against 2D TMZ-resistant DIPG cell cultures [IC50 = 14.6 (Lip-N3P) vs 32.8 μM (N3P); DIPG-IV) and (IC50 = 101.8 (AFt-N3P) vs 111.9 μM (N3P); DIPG-VI)]. Likewise, both N3P-NPs significantly (P < 0.01) inhibited 3D spheroid growth compared to the native N3P in MGMT+ DIPG-VI (100 μM) and mismatch repair deficient DIPG-XIX (50 μM) cultures. Interestingly, the potency of TMZ was remarkably enhanced when encapsulated in AFt NPs against DIPG-IV, -VI, and -XIX spheroid cultures. Dynamic PET scans of CED-administered zirconium-89 (89Zr)-labeled AFt-NPs in rats also demonstrated substantial enhancement over free 89Zr radionuclide in terms of localized distribution kinetics and retention within the brain parenchyma. Overall, both NP formulations of N3P represent promising approaches for treatment of TMZ-resistant DIPG and merit the next phase of preclinical evaluation.