Pediatric high-grade glioma: biologically and clinically in need of new thinking

IL13RA2-integrated genetically engineered mouse model allows for CAR T cells targeting pediatric high-grade gliomas

Pediatric high-grade gliomas (pHGG) and pediatric diffuse midline gliomas (pDMG) are devastating diseases without durable and curative options. Although targeted immunotherapy has shown promise, the field lacks immunocompetent animal models to study these processes in detail. To achieve this, we developed a fully immunocompetent, genetically engineered mouse model (GEMM) for pDMG and pHGG that incorporates the glioma-associated antigen, interleukin 13 receptor alpha 2 (IL13RA2). Utilizing the RCAS-Tva delivery system in Nestin-Tva mice, we induced gliomagenesis by overexpressing PDGFB and deleting p53 (p53fl/fl) or both p53 and PTEN (p53fl/fl PTENfl/fl), with or without IL13RA2 in neonatal mice. De novo tumors developed in models with and without IL13RA2, showing no statistical difference in onset (n = 33, 38 days, p = 0.62). The p53fl/fl PTENfl/fl tumors displayed more aggressive characteristics (n = 12, 31 days). Tumors exhibited features typical of high-grade glioma, including infiltration, pseudopalisading necrosis, and microvascular proliferation. They also showed a high Ki-67 index, variable IL13RA2 expression, a high frequency of CD11b + macrophages, and a low proportion of CD3 + T cells. The model proved effective for evaluating IL13RA2-targeted immunotherapies, with a significant response to CAR T-cell treatment that extended survival (46 days vs. 28 days control; p < 0.0001) and achieved 25% long-term survival in mice. This model facilitates the preclinical assessment of IL13RA2-directed therapies and holds potential for clinical application.

Gross tumor volume increase and need for adaptive radiotherapy in pediatric-type diffuse high-grade glioma of the midline structures

INTRODUCTION

Current pediatric-type diffuse high-grade glioma radiotherapy protocols apply a 1.0 cm clinical target volume (CTV) margin around the gross tumor volume (GTV). However, in adults with glioblastoma, large variations in GTV are observed during radiotherapy. The study aimed to map the GTV variation during a 6-week course of radiotherapy using repeated MR-imaging and to evaluate the need for plan adaptation. Also, the relation between GTV increase and time to disease progression (TTP) was assessed.

MATERIAL AND METHODS

Patients with newly diagnosed diffuse midline glioma or diffuse pediatric-type high-grade glioma of the midline structures undergoing a 6-week radiotherapy course, were eligible for inclusion. MRI scans were performed in the pre-treatment phase (MRI0), and at fraction 10 + 20 (rMRI10/rMRI20). On all scans, GTV was delineated. An increase was defined as a >5 % increase of GTV between scans. The need for treatment plan adaptation was based on dosimetric and visual criteria. GTV increase was compared to TTP.

RESULTS

Twenty patients were eligible. In 12/20 patients, a GTV increase was observed at rMR10/rMR20, more specifically in 6/11 pontine and 6/9 non-pontine tumors. Combining dosimetric criteria and visual inspection, 20 plan adaptations in 14 patients were required. The TTP (range: 1.6-17.6 months) was not significantly different between the group with (median 8.1 months) versus without a GTV increase (median 7.6 months; p = 0.66).

CONCLUSION

Repeated imaging demonstrated a GTV increase in 60 % of patients and plan adaptation in 70 %. When applying CTV margins of 1.0 cm, plan adaptation is recommended to ensure adequate radiotherapy treatment.

FET-CREB fusion-positive extra-axial myxoid mesenchymal tumor in the cerebellum: illustrative case

BACKGROUND

Myxoid mesenchymal tumor (MMT) is an exceptionally rare central nervous system (CNS) tumor, with even fewer reported cases in the cerebellum. Its complex histopathological features and nonspecific clinical presentation pose considerable challenges in diagnosis. The rarity of the tumor, coupled with its poorly characterized clinical and radiological features, complicates early detection and effective treatment.

OBSERVATIONS

xsThe authors present the case of an 18-year-old female who presented with persistent headaches and intermittent diplopia. MRI revealed a hypervascular mass in the right cerebellum, showing marked contrast enhancement. The patient underwent total tumor resection, and histopathological examination revealed lobulated tumor cells that were positive for the FET-CREB fusion gene. Immunohistochemical staining was positive for epithelial membrane antigen, vimentin, and H3K27me3, with a Ki-67 proliferation index of 8%, confirming the diagnosis of MMT. The patient had an uneventful recovery and remained recurrence free during a 6-month follow-up.

LESSONS

This case highlights the critical role of the FET-CREB fusion gene in diagnosing cerebellar MMT. It emphasizes the importance of early recognition, comprehensive pathological evaluation, and genetic analysis in managing this rare tumor. A thorough, multidisciplinary diagnostic approach is essential for determining the optimal treatment and improving patient outcomes. https://thejns.org/doi/10.3171/CASE24872.

Clinical experience with immunotherapy in patients with diffuse intrinsic pontine glioma

The objective of the article is to report the case of three patients with diffuse intrinsic pontine glioma (DIPG) treated with immunotherapy. In particular we report the data related to the treatments' efficacy and tolerance.To achieve this, we review the medical records in the Paediatric Oncology and Haematology Unit of HM Hospitales/Centro Integral Oncológico Clara Campal (CIOCC). We focused on patients diagnosed with DIPG who were administered oncolytic viruses followed by immune checkpoint inhibitors (ICI) (pembrolizumab, anti PD-1) plus a concomitant antiangiogenic agent (bevacizumab).The results we obtained showed the three paediatric DIPG patients studied presented good tolerance, with disease stabilisation for approximately 5 months after immunotherapy. However, subsequent clinical worsening required clinicians to change the patients' treatment.In conclusion, immunotherapy combined with other conventional antineoplastic treatments (chemotherapy, radiotherapy) is postulated as a very promising future therapeutic option. However, further research is warranted in the paediatric population to demonstrate safety and effectiveness.

H3.3-G34R Mutation-Mediated Epigenetic Reprogramming Leads to Enhanced Efficacy of Immune Stimulatory Gene Therapy in Diffuse Hemispheric Gliomas

Diffuse hemispheric glioma (DHG), H3 G34-mutant, representing 9-15% of cases, are aggressive Central Nervous System (CNS) tumors with poor prognosis. This study examines the role of epigenetic reprogramming of the immune microenvironment and the response to immune-mediated therapies in G34-mutant DHG. To this end, we utilized human G34-mutant DHG biopsies, primary G34-mutant DHG cultures, and genetically engineered G34-mutant mouse models (GEMMs). Our findings show that the G34 mutation alters histone marks' deposition at promoter and enhancer regions, leading to the activation of the JAK/STAT pathway, which in turn results in an immune-permissive tumor microenvironment. The implementation of Ad-TK/Ad-Flt3L immunostimulatory gene therapy significantly improved median survival, and lead to over 50% long term survivors. Upon tumor rechallenge in the contralateral hemisphere without any additional treatment, the long-term survivors exhibited robust anti-tumor immunity and immunological memory. These results indicate that immune-mediated therapies hold significant potential for clinical translation in treating patients harboring H3.3-G34 mutant DHGs, offering a promising strategy for improving outcomes in this challenging cancer subtype affecting adolescents and young adults (AYA).

STATEMENT OF SIGNIFICANCE

This study uncovers the role of the H3.3-G34 mutation in reprogramming the tumor immune microenvironment in diffuse hemispheric gliomas. Our findings support the implementation of precision medicine informed immunotherapies, aiming at improving enhanced therapeutic outcomes in adolescents and young adults harboring H3.3-G34 mutant DHGs.

Opportunities in the translational pipeline for pediatric brain cancer therapies

Primary malignant central nervous system (CNS) tumors are the leading cause of cancer-related mortality in the pediatric population. Moreover, survivors often experience significant long-term treatment-related morbidity. Challenges unique to drug delivery to the central nervous system have hampered therapeutic progress. In the past decade, significant advancements in our understanding of molecular biology, genetic alterations, and the tumor microenvironment have allowed us to improve our in vitro and laboratory animal models to better replicate diseases seen in the pediatric population. Recently, a comparative approach using naturally-occurring CNS malignancies in dogs with similar disease progression, histologic presentation, and treatment response has been proposed as an enticing model system. Given these improvements in the translational pipeline, there is an opportunity to identify and implement effective therapies more efficiently to pediatric CNS malignancy populations. IMPACT: Relevant and translational pre-clinical studies are needed to find chemotherapeutics and targeted agents that can reach therapeutic doses within tumors in children without causing systemic adverse effects. A discussion of comparative oncology is provided with the intent to foster veterinary/human oncology collaboration. While the traditional pipeline for translating medications from bench to bedside has been evolving and improving over the last decade, the advances and remaining roadblocks of this pipeline are reviewed and discussed in this article.

Advances in the Repurposing and Blood-Brain Barrier Penetrance of Drugs in Pediatric Brain Tumors

Central nervous system (CNS) tumors are the leading cause of cancer-related mortality in children, with prognosis remaining dismal for some of these malignancies. Though the past two decades have seen advancements in surgery, radiation, and targeted therapy, major unresolved hurdles continue to undermine the therapeutic efficacy. These include challenges in suboptimal drug delivery through the blood-brain barrier (BBB), marked intra-tumoral molecular heterogeneity, and the elusive tumor microenvironment. Drug repurposing or re-tasking FDA-approved drugs with evidence of penetration into the CNS, using newer methods of intracranial drug delivery facilitating optimal drug exposure, has been an area of intense research. This could be a valuable tool, as most of these agents have already gone through the lengthy process of drug development and the evaluation of safety risks and the optimal pharmacokinetic profile. They can now be used and tested in clinics with an accelerated and different approach. Conclusions: The next-generation therapeutic strategy should prioritize repurposing oncologic and non-oncologic drugs that have been used for other indication, and have demonstrated robust preclinical activity against pediatric brain tumors. In combination with novel drug delivery techniques, these drugs could hold significant therapeutic promise in pediatric neurooncology.

Identification of Key Biomarkers Associated with Glioma Hemorrhage: Evidence from Bioinformatic Analysis and Clinical Validation

Hemorrhagic stroke is a known complication of glioma, yet the underlying mechanisms remain poorly understood. This study aims to investigate key biomarkers of glioma-related hemorrhage to provide insights into glioma molecular therapies. Data were obtained from the Gene Expression Omnibus (GEO) and the Cancer Genome Atlas (TCGA) databases to analyze differentially expressed genes (DEGs) in glioma by contrasting glioblastoma (GBM) with low-grade gliomas (LGGs). We conducted enrichment analyses using the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and Gene Ontology (GO) databases through the Database for Annotation, Visualization, and Integrated Discovery (DAVID). A STRING-based protein-protein interaction (PPI) network was developed to identify hub genes, which were subsequently analyzed for their functions in the GeneCards database. To identify angiogenesis-associated genes, we utilized the Human Protein Atlas (HPA) and Gene Expression Profiling Interactive Analysis (GEPIA) databases. A clinical pathological study was conducted using immunohistochemistry (IHC) staining to confirm the findings. In the GEO database, the GEO Series Experiments GSE26576 and GSE184941 included 4523 and 1471 differentially expressed genes (DEGs), respectively. We identified 2715 DEGs using the cBioPortal within the TCGA database. A Venn diagram identified 39 common DEGs. The KEGG pathways and Gene Ontology (GO) analysis highlighted functions related to angiogenesis. PPI network analyses pinpointed 13 hub genes. Through cross-referencing a gene set related to tumor angiogenesis in the GeneCards database, we identified MMP-2 and EGFR as key genes. In the HPA database, we observed EGFR and MMP-2 expression in the normal cerebral cortex, confirmed by IHC. In GEPIA database, high MMP-2 levels were associated with decreased survival time, while EGFR expression showed no significant differences in survival. A clinical study of 21 patients, 11 in the control group and 10 in the stroke group with glioma hemorrhage, revealed no significant differences in their characteristics or comorbidities. IDH1 positivity was higher in the control group (4/11) vs the stroke group (0/10). Tumor cells exhibited increased MMP-2 and EGFR expression, with stronger staining in the stroke group. Our study concluded that IDH1, MMP-2, and EGFR are implicated in the molecular mechanism of glioma hemorrhage as key biomarkers. MMP-2 and IDH1 are potential targets for molecular therapy.

Detection of H3F3A K27M or BRAF V600E in liquid biopsies of brain tumor patients as diagnostic and monitoring biomarker: impact of tumor localization and sampling method

Gliomas are the most common brain tumor type in children and adolescents. To date, diagnosis and therapy monitoring for these tumors rely on magnetic resonance imaging (MRI) and histopathological as well as molecular analyses of tumor tissue. Recently, liquid biopsies (LB) have emerged as promising tool for diagnosis and longitudinal tumor assessment potentially allowing for a more precise therapeutic management. However, the optimal strategy for monitoring gliomas by LB remains to be determined. In this study, we analyzed circulating tumor DNA (ctDNA) from 78 liquid biopsies (plasma n = 44, cerebrospinal fluid n = 34 (CSF)) of 35 glioma patients, determining H3F3A K28M (K27M) and BRAF V600E mutation allele frequency using droplet digital PCR (ddPCR). All results were correlated to clinically relevant parameters including diagnostic imaging and CSF aspiration site (ventricular vs lumbar) with respect to tumor localization. Regarding diagnostic accuracy, the calculated sensitivity score in the H3F3A K27M cohort was 84.61% for CSF and 73.68% for plasma. In the BRAF V600E cohort, we determined a sensitivity of 83.3% in plasma and 80% in CSF. The overall specificity was 100%. With respect to the CSF aspiration, the intra-operatively obtained CSF demonstrated 100% detection rate, followed by ventricular CSF obtained via Ommaya Reservoir/shunt puncture (93%) and CSF obtained via lumbar puncture (66%). Notably, this further correlated with the proximity of the CSF site to tumor localization. Longitudinal CSF monitoring demonstrated a good correlation to clinical and radiological disease evolution. Importantly, we show for the first time that monitoring BRAF V600E by ddPCR could serve as treatment response assessment in gliomas. In summary, our observation may inform recommendations with regard to location of CSF aspiration when incorporating LB into future treatment protocols.

IL13RA2-integrated genetically engineered mouse model allows for CAR T cells targeting pediatric high-grade gliomas

Pediatric high-grade gliomas (pHGG) and pediatric diffuse midline gliomas (pDMG) are devastating diseases without durable and curative options. Although targeted immunotherapy has shown promise, the field lacks immunocompetent animal models to study these processes in detail. To achieve this, we developed a fully immunocompetent, genetically engineered mouse model (GEMM) for pDMG and pHGG that incorporates the glioma-associated antigen, interleukin 13 receptor alpha 2 (IL13RA2). Utilizing the RCAS-Tva delivery system in Nestin-Tva mice, we induced gliomagenesis by overexpressing PDGFB and deleting p53 (p53fl/fl) or both p53 and PTEN (p53fl/fl PTENfl/fl), with or without IL13RA2 in neonatal mice. De novo tumors developed in models with and without IL13RA2, showing no statistical difference in onset (n = 33, 38 days, p = 0.62). The p53fl/fl PTENfl/fl tumors displayed more aggressive characteristics (n = 12, 31 days). Tumors exhibited features typical of high-grade glioma, including infiltration, pseudopalisading necrosis, and microvascular proliferation. They also showed a high Ki-67 index, variable IL13RA2 expression, a high frequency of CD11b + macrophages, and a low proportion of CD3 + T cells. The model proved effective for evaluating IL13RA2-targeted immunotherapies, with a significant response to CAR T-cell treatment that extended survival (46 days vs. 28 days control; p < 0.0001) and achieved 25% long-term survival in mice. This model facilitates the preclinical assessment of IL13RA2-directed therapies and holds potential for clinical application.

Diffuse pediatric high-grade glioma of methylation-based RTK2A and RTK2B subclasses present distinct radiological and histomolecular features including Gliomatosis cerebri phenotype

Diffuse pediatric-type high-grade gliomas (pedHGG), H3- and IDH-wildtype, encompass three main DNA-methylation-based subtypes: pedHGG-MYCN, pedHGG-RTK1A/B/C, and pedHGG-RTK2A/B. Since their first description in 2017 tumors of pedHGG-RTK2A/B have not been comprehensively characterized and clinical correlates remain elusive. In a recent series of pedHGG with a Gliomatosis cerebri (GC) growth pattern, an increased incidence of pedHGG-RTK2A/B (n = 18) was observed. We added 14 epigenetically defined pedHGG-RTK2A/B tumors to this GC series and provided centrally reviewed radiological, histological, and molecular characterization. The final cohort of 32 pedHGG-RTK2A/B tumors consisted of 25 pedHGG-RTK2A (78%) and seven pedHGG-RTK2B (22%) cases. The median age was 11.6 years (range, 4-17) with a median overall survival of 16.0 months (range 10.9-28.2). Seven of 11 of the newly added cases with imaging available showed a GC phenotype at diagnosis or follow-up. PedHGG-RTK2B tumors exhibited frequent bithalamic involvement (6/7, 86%). Central neuropathology review confirmed a diffuse glial neoplasm in all tumors with prominent angiocentric features in both subclasses. Most tumors (24/27 with available data, 89%) diffusely expressed EGFR with focal angiocentric enhancement. PedHGG-RTK2A tumors lacked OLIG2 expression, whereas 43% (3/7) of pedHGG-RTK2B expressed this glial transcription factor. ATRX loss occurred in 3/6 pedHGG-RTK2B samples with available data (50%). DNA sequencing (pedHGG-RTK2A: n = 18, pedHGG-RTK2B: n = 5) found EGFR alterations (15/23, 65%; predominantly point mutations) in both subclasses. Mutations in BCOR (14/18, 78%), SETD2 (7/18, 39%), and the hTERT promoter (7/19, 37%) occurred exclusively in pedHGG-RTK2A tumors, while pedHGG-RTK2B tumors were enriched for TP53 alterations (4/5, 80%). In conclusion, pedHGG-RTK2A/B tumors are characterized by highly diffuse-infiltrating growth patterns and specific radiological and histo-molecular features. By comprehensively characterizing methylation-based tumors, the chance to develop specific and effective therapy concepts for these detrimental tumors increases.

Advances in CAR-T therapy for central nervous system tumors

The application of chimeric antigen receptor T-cell therapy in central nervous system tumors has significantly advanced; however, challenges pertaining to the blood-brain barrier, immunosuppressive microenvironment, and antigenic heterogeneity continue to be encountered, unlike its success in hematological malignancies such as acute lymphoblastic leukemia and diffuse large B-cell lymphomas. This review examined the research progress of chimeric antigen receptor T-cell therapy in gliomas, medulloblastomas, and lymphohematopoietic tumors of the central nervous system, focusing on chimeric antigen receptor T-cells targeting antigens such as EGFRvIII, HER2, B7H3, GD2, and CD19 in preclinical and clinical studies. It synthesized current research findings to offer valuable insights for future chimeric antigen receptor T-cell therapeutic strategies for central nervous system tumors and advance the development and application of this therapeutic modality in this domain.

A phase 1 study of mebendazole with bevacizumab and irinotecan in high-grade gliomas

BACKGROUND

High-grade gliomas (HGG) have a dismal prognosis despite multimodal therapy. Mebendazole is an anti-helminthic benzimidazole that has demonstrated efficacy in numerous in vitro cancer models, and is able to cross the blood-brain barrier. We conducted a phase 1 trial (NCT01837862) to evaluate the safety of mebendazole in combination with bevacizumab and irinotecan in children and young adults with HGG.

OBJECTIVE

To determine the maximally tolerated dose of mebendazole when given in combination with bevacizumab and irinotecan in children with HGG; to describe the progression-free survival (PFS) and overall survival (OS) for this group.

DESIGN/METHOD

Patients between 1 and 21 years of age with HGG were enrolled in a 3 + 3 design to escalating doses of mebendazole in combination with bevacizumab (10 mg/kg/dose) and irinotecan (150 mg/m2 /dose). Subjects were eligible upfront after completion of radiation or at the time of progression. Mebendazole was taken orally twice per day continuously, and bevacizumab and irinotecan were given intravenously on Days 1 and 15 of 28-day cycles.

RESULTS

Between 2015 and 2020, 10 subjects were enrolled at mebendazole doses of 50 mg/kg/day (n = 3), 100 mg/kg/day (n = 4), and 200 mg/kg/day (n = 3). One subject assigned to 100 mg/kg/day was not evaluable. Seven subjects had a diagnosis of diffuse midline glioma, one subject had anaplastic astrocytoma, and one subject had a spinal HGG. All subjects received radiation. There were no dose-limiting toxicities. The most frequent G3/4 adverse events were neutropenia (n = 3) and lymphopenia (n = 4). The overall response rate was 33%, with two subjects achieving a partial response and one subject achieving a complete response sustained for 10 months. The mean PFS and OS from the start of study treatment were 4.7 and 11.4 months, respectively.

CONCLUSION

Mebendazole was safe and well tolerated when administered with bevacizumab and irinotecan at doses up to 200 mg/kg/day. Further studies are needed to determine the efficacy of this treatment.

A longitudinal single-cell and spatial multiomic atlas of pediatric high-grade glioma

Pediatric high-grade glioma (pHGG) is an incurable central nervous system malignancy that is a leading cause of pediatric cancer death. While pHGG shares many similarities to adult glioma, it is increasingly recognized as a molecularly distinct, yet highly heterogeneous disease. In this study, we longitudinally profiled a molecularly diverse cohort of 16 pHGG patients before and after standard therapy through single-nucleus RNA and ATAC sequencing, whole-genome sequencing, and CODEX spatial proteomics to capture the evolution of the tumor microenvironment during progression following treatment. We found that the canonical neoplastic cell phenotypes of adult glioblastoma are insufficient to capture the range of tumor cell states in a pediatric cohort and observed differential tumor-myeloid interactions between malignant cell states. We identified key transcriptional regulators of pHGG cell states and did not observe the marked proneural to mesenchymal shift characteristic of adult glioblastoma. We showed that essential neuromodulators and the interferon response are upregulated post-therapy along with an increase in non-neoplastic oligodendrocytes. Through in vitro pharmacological perturbation, we demonstrated novel malignant cell-intrinsic targets. This multiomic atlas of longitudinal pHGG captures the key features of therapy response that support distinction from its adult counterpart and suggests therapeutic strategies which are targeted to pediatric gliomas.

Myeloid cells as potential targets for immunotherapy in pediatric gliomas

Pediatric high-grade glioma (pHGG) including pediatric glioblastoma (pGBM) are highly aggressive pediatric central nervous system (CNS) malignancies. pGBM comprises approximately 3% of all pediatric CNS malignancies and has a 5-year survival rate of approximately 20%. Surgical resection and chemoradiation are often the standard of care for pGBM and pHGG, however, even with these interventions, survival for children diagnosed with pGBM and pHGG remains poor. Due to shortcomings associated with the standard of care, many efforts have been made to create novel immunotherapeutic approaches targeted to these malignancies. These efforts include the use of vaccines, cell-based therapies, and immune-checkpoint inhibitors. However, it is believed that in many pediatric glioma patients an immunosuppressive tumor microenvironment (TME) possess barriers that limit the efficacy of immune-based therapies. One of these barriers includes the presence of immunosuppressive myeloid cells. In this review we will discuss the various types of myeloid cells present in the glioma TME, including macrophages and microglia, myeloid-derived suppressor cells, and dendritic cells, as well as the specific mechanisms these cells can employ to enable immunosuppression. Finally, we will highlight therapeutic strategies targeted to these cells that are aimed at impeding myeloid-cell derived immunosuppression.

Updates on management of gliomas in the molecular age

Gliomas are primary brain tumors derived from glial cells of the central nervous system, afflicting both adults and children with distinct characteristics and therapeutic challenges. Recent developments have ushered in novel clinical and molecular prognostic factors, reshaping treatment paradigms based on classification and grading, determined by histological attributes and cellular lineage. This review article delves into the diverse treatment modalities tailored to the specific grades and molecular classifications of gliomas that are currently being discussed and used clinically in the year 2023. For adults, the therapeutic triad typically consists of surgical resection, chemotherapy, and radiotherapy. In contrast, pediatric gliomas, due to their diversity, require a more tailored approach. Although complete tumor excision can be curative based on the location and grade of the glioma, certain non-resectable cases demand a chemotherapy approach usually involving, vincristine and carboplatin. Additionally, if surgery or chemotherapy strategies are unsuccessful, Vinblastine can be used. Despite recent advancements in treatment methodologies, there remains a need of exploration in the literature, particularly concerning the efficacy of treatment regimens for isocitrate dehydrogenase type mutant astrocytomas and fine-tuned therapeutic approaches tailored for pediatric cohorts. This review article explores into the therapeutic modalities employed for both adult and pediatric gliomas in the context of their molecular classification.

Expression of lncRNAs in glioma: A lighthouse for patients with glioma

Glioma is the most common malignant tumour in the central nervous system, accounting for approximately 30 % of the primary tumours of this system. The World Health Organization grades for glioma include: Grade I (pilocytic astrocytoma), Grade II (astrocytoma, oligodastoma, etc.), Grade III (anaplastic astrocytoma, anaplastic oligodastoma, etc.) and Grade IV (glioblastoma). With grade increases, the proliferation, invasion and other malignant biological properties of the glioma are enhanced, and the treatment results are less satisfactory. The overall survival of patients with glioblastoma is less than 15 months. Recent research has focused on the roles of long non-coding RNAs, previously regarded as "transcriptional noise", in diseases, leading to a new understanding of these roles. Therefore, we conducted this review to explore the progress of research regarding the expression and mechanism of long non-coding RNAs in glioma.

Novel insights on genetics and epigenetics as clinical targets for paediatric astrocytoma

Paediatric and adult astrocytomas are notably different, where clinical treatments used for adults are not as effective on children with the same form of cancer and these treatments lead to adverse long-term health concerns. Integrative omics-based studies have shown the pathology and fundamental molecular characteristics differ significantly and cannot be extrapolated from the more widely studied adult disease. Recent clinical advances in our understanding of paediatric astrocytomas, with the aid of next-generation sequencing and epigenome-wide profiling, have led to the identification of key canonical mutations that vary based on the tumour location and age of onset. These driver mutations, in particular the identification of the recurrent histone H3 mutations in high-grade tumours, have confirmed the important role epigenetic dysregulations play in cancer progression. This review summarises the current updates of the classification, epidemiology, pathogenesis and clinical management of paediatric astrocytoma based on their grades and the ongoing clinical trials. It also provides novel insights on genetic and epigenetic alterations as diagnostic biomarkers, highlighting the potential of targeting these pathways as therapeutics for this devastating childhood cancer.

BMP signaling in cancer stemness and differentiation

The BMP (Bone morphogenetic protein) signaling pathway plays a central role in metazoan biology, intricately shaping embryonic development, maintaining tissue homeostasis, and influencing disease progression. In the context of cancer, BMP signaling exhibits context-dependent dynamics, spanning from tumor suppression to promotion. Cancer stem cells (CSCs), a modest subset of neoplastic cells with stem-like attributes, exert substantial influence by steering tumor growth, orchestrating therapy resistance, and contributing to relapse. A comprehensive grasp of the intricate interplay between CSCs and their microenvironment is pivotal for effective therapeutic strategies. Among the web of signaling pathways orchestrating cellular dynamics within CSCs, BMP signaling emerges as a vital conductor, overseeing CSC self-renewal, differentiation dynamics, and the intricate symphony within the tumor microenvironment. Moreover, BMP signaling's influence in cancer extends beyond CSCs, intricately regulating cellular migration, invasion, and metastasis. This multifaceted role underscores the imperative of comprehending BMP signaling's contributions to cancer, serving as the foundation for crafting precise therapies to navigate multifaceted challenges posed not only by CSCs but also by various dimensions of cancer progression. This article succinctly encapsulates the diverse roles of the BMP signaling pathway across different cancers, spanning glioblastoma multiforme (GBM), diffuse intrinsic pontine glioma (DIPG), colorectal cancer, acute myeloid leukemia (AML), lung cancer, prostate cancer, and osteosarcoma. It underscores the necessity of unraveling underlying mechanisms and molecular interactions. By delving into the intricate tapestry of BMP signaling's engagement in cancers, researchers pave the way for meticulously tailored therapies, adroitly leveraging its dualistic aspects-whether as a suppressor or promoter-to effectively counter the relentless march of tumor progression.

Pediatric Neuro-oncology

OBJECTIVE

This article reviews the most common pediatric brain tumors, neurocutaneous syndromes, treatment-related neurotoxicities, and the long-term outcomes of survivors.

LATEST DEVELOPMENTS

In the era of molecular diagnostics, the classification, management, and prognostication of pediatric brain tumors and neurocutaneous syndromes has been refined, resulting in advancements in patient management. Molecular diagnostics have been incorporated into the most recent World Health Organization 2021 classification. This knowledge has allowed for novel therapeutic approaches targeting the biology of these tumors with the intent to improve overall survival, decrease treatment-related morbidity, and improve quality of life. Advances in management have led to better survival, but mortality remains high and significant morbidity persists. Current clinical trials focus on tumor biology targeted therapy, deescalation of therapy, and multimodal intensified approaches with targeted therapy in more high-risk tumors.

ESSENTIAL POINTS

Molecular diagnostics for pediatric brain tumors and neurocutaneous syndromes have led to novel therapeutic approaches targeting the biology of these tumors with the goals of improving overall survival and decreasing treatment-related morbidity. Further understanding will lead to continued refinement and improvement of tumor classification, management, and prognostication.

Inhibition of exosome biogenesis affects cell motility in heterogeneous sub-populations of paediatric-type diffuse high-grade gliomas

BACKGROUND

Paediatric-type diffuse High-Grade Gliomas (PDHGG) are highly heterogeneous tumours which include distinct cell sub-populations co-existing within the same tumour mass. We have previously shown that primary patient-derived and optical barcoded single-cell-derived clones function as interconnected networks. Here, we investigated the role of exosomes as a route for inter-clonal communication mediating PDHGG migration and invasion.

RESULTS

A comprehensive characterisation of seven optical barcoded single-cell-derived clones obtained from two patient-derived cell lines was performed. These analyses highlighted extensive intra-tumour heterogeneity in terms of genetic and transcriptional profiles between clones as well as marked phenotypic differences including distinctive motility patterns. Live single-cell tracking analysis of 3D migration and invasion assays showed that the single-cell-derived clones display a higher speed and longer travelled distance when in co-culture compared to mono-culture conditions. To determine the role of exosomes in PDHGG inter-clonal cross-talks, we isolated exosomes released by different clones and characterised them in terms of marker expression, size and concentration. We demonstrated that exosomes are actively internalized by the cells and that the inhibition of their biogenesis, using the phospholipase inhibitor GW4689, significantly reduced the cell motility in mono-culture and more prominently when the cells from the clones were in co-culture. Analysis of the exosomal miRNAs, performed with a miRNome PCR panel, identified clone-specific miRNAs and a set of miRNA target genes involved in the regulation of cell motility/invasion/migration. These genes were found differentially expressed in co-culture versus mono-culture conditions and their expression levels were significantly modulated upon inhibition of exosome biogenesis.

CONCLUSIONS

In conclusion, our study highlights for the first time a key role for exosomes in the inter-clonal communication in PDHGG and suggests that interfering with the exosome biogenesis pathway may be a valuable strategy to inhibit cell motility and dissemination for these specific diseases.

Sex-related incidence and survival differences in pediatric high-grade glioma subtypes: A population-based cohort study

Not much is known on sex differences in incidence, survival, and treatment characteristics for midline and hemispheric pHGGs. This population-based study confirms previously reported study results that found worse survival outcomes for malignant diffuse gliomas in girls in the age group 0-9 years. Additionally, in our study we pinpoint this difference to girls with midline pHGGs aged 0-4 years. We provide insight in the possible underlying mechanisms contributing to sex survival differences in pHGG patients. With first line treatment having no impact on the higher risk of dying for girls, but age and tumor characteristics having a neutralizing effect. The results of this population-based study serve as a basis for future pre-clinical and clinical studies to further unravel the underlying mechanisms responsible for the survival gap between sexes in midline pHGG.

Successes and challenges in modeling heterogeneous BRAFV600E mutated central nervous system neoplasms

Central nervous system (CNS) neoplasms are difficult to treat due to their sensitive location. Over the past two decades, the availability of patient tumor materials facilitated large scale genomic and epigenomic profiling studies, which have resulted in detailed insights into the molecular underpinnings of CNS tumorigenesis. Based on results from these studies, CNS tumors have high molecular and cellular intra-tumoral and inter-tumoral heterogeneity. CNS cancer models have yet to reflect the broad diversity of CNS tumors and patients and the lack of such faithful cancer models represents a major bottleneck to urgently needed innovations in CNS cancer treatment. Pediatric cancer model development is lagging behind adult tumor model development, which is why we focus this review on CNS tumors mutated for BRAFV600E which are more prevalent in the pediatric patient population. BRAFV600E-mutated CNS tumors exhibit high inter-tumoral heterogeneity, encompassing clinically and histopathological diverse tumor types. Moreover, BRAFV600E is the second most common alteration in pediatric low-grade CNS tumors, and low-grade tumors are notoriously difficult to recapitulate in vitro and in vivo. Although the mutation predominates in low-grade CNS tumors, when combined with other mutations, most commonly CDKN2A deletion, BRAFV600E-mutated CNS tumors are prone to develop high-grade features, and therefore BRAFV600E-mutated CNS are a paradigm for tumor progression. Here, we describe existing in vitro and in vivo models of BRAFV600E-mutated CNS tumors, including patient-derived cell lines, patient-derived xenografts, syngeneic models, and genetically engineered mouse models, along with their advantages and shortcomings. We discuss which research gaps each model might be best suited to answer, and identify those areas in model development that need to be strengthened further. We highlight areas of potential research focus that will lead to the heightened predictive capacity of preclinical studies, allow for appropriate validation, and ultimately improve the success of "bench to bedside" translational research.

Novel therapeutic approaches for pediatric diencephalic tumors: improving functional outcomes

Pediatric diencephalic tumors represent a histopathologically and molecularly diverse group of neoplasms arising in the central part of the brain and involving eloquent structures, including the hypothalamic-pituitary axis (HPA), optic pathway, thalamus, and pineal gland. Presenting symptoms can include significant neurological, endocrine, or visual manifestations which may be exacerbated by injudicious intervention. Upfront multidisciplinary assessment and coordinated management is crucial from the outset to ensure best short- and long-term functional outcomes. In this review we discuss the clinical and pathological features of the neoplastic entities arising in this location, and their management. We emphasize a clear move towards 'function preserving' diagnostic and therapeutic approaches with novel toxicity-sparing strategies, including targeted therapies.

Fifty years of DIPG: looking at the future with hope

Diffuse intrinsic pontine glioma (DIPG) is a primary brainstem tumor of childhood that carries a dismal prognosis, with median survival of less than 1 year. Because of the brain stem location and pattern of growth within the pons, Dr. Harvey Cushing, the father of modern neurosurgery, urged surgical abandonment. Such a dismal prognosis remained unchanged for decades, coupled with a lack of understanding of tumor biology and an unchanging therapeutic panorama. Beyond palliative external beam radiation therapy, no therapeutic approach has been widely accepted. In the last one to two decades, however, increased tissue availability, an improving understanding of biology, genetics, and epigenetics have led to the development of novel therapeutic targets. In parallel with this biological revolution, new methods intended to enhance drug delivery into the brain stem are contributing to a surge of exciting experimental therapeutic strategies.

A biobank of pediatric patient-derived-xenograft models in cancer precision medicine trial MAPPYACTS for relapsed and refractory tumors

Pediatric patients with recurrent and refractory cancers are in most need for new treatments. This study developed patient-derived-xenograft (PDX) models within the European MAPPYACTS cancer precision medicine trial (NCT02613962). To date, 131 PDX models were established following heterotopical and/or orthotopical implantation in immunocompromised mice: 76 sarcomas, 25 other solid tumors, 12 central nervous system tumors, 15 acute leukemias, and 3 lymphomas. PDX establishment rate was 43%. Histology, whole exome and RNA sequencing revealed a high concordance with the primary patient's tumor profile, human leukocyte-antigen characteristics and specific metabolic pathway signatures. A detailed patient molecular characterization, including specific mutations prioritized in the clinical molecular tumor boards are provided. Ninety models were shared with the IMI2 ITCC Pediatric Preclinical Proof-of-concept Platform (IMI2 ITCC-P4) for further exploitation. This PDX biobank of unique recurrent childhood cancers provides an essential support for basic and translational research and treatments development in advanced pediatric malignancies.

Bridging the age gap: a review of molecularly informed treatments for glioma in adolescents and young adults

Gliomas are the most common primary central nervous system (CNS) tumors and a major cause of cancer-related mortality in children (age <15 years), adolescents and young adults (AYA, ages 15-39 years), and adults (age >39 years). Molecular pathology has helped enhance the characterization of these tumors, revealing a heterogeneous and ever more complex group of malignancies. Recent molecular analyses have led to an increased appreciation of common genomic alterations prevalent across all ages. The 2021 World Health Organization (WHO) CNS tumor classification, 5th edition (WHO CNS5) brings forward a nomenclature distinguishing "pediatric-type" and "adult-type" gliomas. The spectrum of gliomas in AYA comprises both "pediatric-like" and "adult-like" tumor entities but remains ill-defined. With fragmentation of clinical management between pediatric and adult centers, AYAs face challenges related to gaps in medical care, lower rates of enrollment in clinical trials and additional psychosocial and economic challenges. This calls for a rethinking of diagnostic and therapeutic approaches, to improve access to appropriate testing and potentially beneficial treatments to patients of all ages.

A comprehensive genomic study of 390 H3F3A-mutant pediatric and adult diffuse high-grade gliomas, CNS WHO grade 4

Malignant brain tumors, known as H3K27-altered diffuse midline glioma (DMG) and H3G34-mutant diffuse hemispheric glioma (DHG), can affect individuals of all ages and are classified as CNS WHO grade 4. We comprehensively characterized 390 H3F3A-mutant diffuse gliomas (201 females, 189 males) arising in pediatric patients (under 20 years old) and adults (20 years and older) evaluated by the CGP program at Foundation Medicine between 2013 and 2020. We assessed information from pathology reports, histopathology review, and clinical data. The cohort included 304 H3K27M-mutant DMG (156 females, 148 males) and 86 H3G34-mutant DHG (45 females, 41 males). Median patient age was 20 years (1-74 years). The frequency of H3K27M-mutant DMG was similar in both pediatric and adult patients in our cohort-48.6% of the patients were over 20 years old, 31.5% over 30, and 18% over 40 at initial diagnosis. FGFR1 hotspot point mutations (N546K and K656E) were exclusively identified in H3K27M-mutant DMG tumors (64/304, 21%; p = 0.0001); these tend to occur in older patients (median age: 32.5 years) and mainly arose in the diencephalon. H3K27M-mutant DMG had higher rates of mutations in NF1 (31.0 vs 8.1%; p = 0.0001) and PIK3CA/PIK3R1 (27.9% vs 15.1%; p = 0.016) compared to H3G34-mutant DHG. However, H3G34-mutant DHG had higher rates of targetable alterations in cell-cycle pathway genes (CDK4 and CDK6 amplification; CDKN2A/B deletion) (27.0 vs 9.0%). Potentially targetable PDGFRA alterations were identified in ~ 20% of both H3G34-mutant DHG and H3K27M-mutant DMG. Overall, in the present study H3K27M-mutant DMG occurred at similar rates in both adult and patient patients. Through our analysis, we were able to identify molecular features characteristic of DMG and DHG. By identifying the recurrent co-mutations including actionable FGFR1 point mutations found in nearly one-third of H3K27M-mutant DMG in young adults, our findings can inform clinical translational studies, patient diagnosis, and clinical trial design.

Identification and validation of a novel HOX-related classifier signature for predicting prognosis and immune microenvironment in pediatric gliomas

Background: Pediatric gliomas (PGs) are highly aggressive and predominantly occur in young children. In pediatric gliomas, abnormal expression of Homeobox (HOX) family genes (HFGs) has been observed and is associated with the development and progression of the disease. Studies have found that overexpression or underexpression of certain HOX genes is linked to the occurrence and prognosis of gliomas. This aberrant expression may contribute to the dysregulation of important pathological processes such as cell proliferation, differentiation, and metastasis. This study aimed to propose a novel HOX-related signature to predict patients' prognosis and immune infiltrate characteristics in PGs. Methods: The data of PGs obtained from publicly available databases were utilized to reveal the relationship among abnormal expression of HOX family genes (HFGs), prognosis, tumor immune infiltration, clinical features, and genomic features in PGs. The HFGs were utilized to identify heterogeneous subtypes using consensus clustering. Then random forest-supervised classification algorithm and nearest shrunken centroid algorithm were performed to develop a prognostic signature in the training set. Finally, the signature was validated in an internal testing set and an external independent cohort. Results: Firstly, we identified HFGs significantly differentially expressed in PGs compared to normal tissues. The individuals with PGs were then divided into two heterogeneous subtypes (HOX-SI and HOX-SII) based on HFGs expression profiles. HOX-SII showed higher total mutation counts, lower immune infiltration, and worse prognosis than HOX-SI. Then, we constructed a HOX-related gene signature (including HOXA6, HOXC4, HOXC5, HOXC6, and HOXA-AS3) based on the cluster for subtype prediction utilizing random forest supervised classification and nearest shrunken centroid algorithm. The signature was revealed to be an independent prognostic factor for patients with PGs by multivariable Cox regression analysis. Conclusion: Our study provides a novel method for the prognosis classification of PGs. The findings also suggest that the HOX-related signature is a new biomarker for the diagnosis and prognosis of patients with PGs, allowing for more accurate survival prediction.

Preliminary findings of German-sourced ONC201 treatment in H3K27 altered pediatric pontine diffuse midline gliomas

PURPOSE

H3K27 altered pediatric pontine diffuse midline gliomas (pDMG) have a poor prognosis, and conventional treatments offer limited benefits. However, recent advancements in molecular evaluations and targeted therapies have shown promise. The aim of this retrospective analysis was to evaluate the effectiveness of German-sourced ONC201, a selective antagonist of dopamine receptor DRD2, for the treatment of pediatric H3K27 altered pDMGs.

METHODS

Pediatric patients with H3K27 altered pDMG treated between January 2016 and July 2022 were included in this retrospective analysis. Tissue samples were acquired from all patients via stereotactic biopsy for immunohistochemistry and molecular profiling. All patients received radiation treatment with concurrent temozolomide, and those who could acquire GsONC201 received it as a single agent until progression. Patients who could not obtain GsONC201 received other chemotherapy protocols.

RESULTS

Among 27 patients with a median age of 5.6 years old (range 3.4-17.9), 18 received GsONC201. During the follow-up period, 16 patients (59.3%) had progression, although not statistically significant, the incidence of progression tended to be lower in the GsONC201 group. The median overall survival (OS) of the GsONC201 group was considerably longer than of the non-GsONC201 group (19.9 vs. 10.9 months). Only two patients receiving GsONC201 experienced fatigue as a side effect. 4 out of 18 patients in the GsONC201 group underwent reirradiation after progression.

CONCLUSION

In conclusion, this study suggests that GsONC201 may improve OS in pediatric H3K27-altered pDMG patients without significant side effects. However, caution is warranted due to retrospective design and biases, highlighting the need for further randomized clinical studies to validate these findings.

Adult spinal cord diffuse midline glioma, H3 K27-altered mimics symptoms of central nervous system infection: a case report

Diffuse midline gliomas, H3 K27-altered are infiltrative growth gliomas with histone H3K27M mutations. This glioma is more common in the pediatric population, and the prognosis is usually poor. We report a case of diffuse midline gliomas, H3 K27-altered in an adult patient that mimicked symptoms of central nervous system infection. The patient was admitted due to double vision for 2 months and paroxysmal unconsciousness for 6 days. Initially, lumbar puncture showed persistent high intracranial pressure, high protein, and low chlorine. Magnetic resonance imaging showed diffuse thickening and enhancement of meninges and spinal meninges, and later, fever occurred. The initial diagnosis was meningitis. We suspected central nervous system infection, so we started anti-infection treatment, but the treatment was ineffective. The patient's condition gradually worsened, with lower limb weakness and even the consciousness became unclear. A repeat magnetic resonance imaging and positron emission tomography-computed tomography scan showed space-occupying lesions in the spinal cord, which was considered a tumor. Following neurosurgery, pathological tests identified the tumor as diffuse midline gliomas, H3 K27-altered. The patient was recommended for radiotherapy and temozolomide chemotherapy. The patient's condition improved after chemotherapy treatment, and he survived for an additional 6 months. Our case shows that diagnosing diffuse midline gliomas, H3 K27-altered in the central nervous system is complex and can be confused with the clinical characteristics of central nervous system infection. Therefore, clinicians should pay attention to such diseases to avoid misdiagnosis.

Considerations for modelling diffuse high-grade gliomas and developing clinically relevant therapies

Diffuse high-grade gliomas contain some of the most dangerous human cancers that lack curative treatment options. The recent molecular stratification of gliomas by the World Health Organisation in 2021 is expected to improve outcomes for patients in neuro-oncology through the development of treatments targeted to specific tumour types. Despite this promise, research is hindered by the lack of preclinical modelling platforms capable of recapitulating the heterogeneity and cellular phenotypes of tumours residing in their native human brain microenvironment. The microenvironment provides cues to subsets of glioma cells that influence proliferation, survival, and gene expression, thus altering susceptibility to therapeutic intervention. As such, conventional in vitro cellular models poorly reflect the varied responses to chemotherapy and radiotherapy seen in these diverse cellular states that differ in transcriptional profile and differentiation status. In an effort to improve the relevance of traditional modelling platforms, recent attention has focused on human pluripotent stem cell-based and tissue engineering techniques, such as three-dimensional (3D) bioprinting and microfluidic devices. The proper application of these exciting new technologies with consideration of tumour heterogeneity and microenvironmental interactions holds potential to develop more applicable models and clinically relevant therapies. In doing so, we will have a better chance of translating preclinical research findings to patient populations, thereby addressing the current derisory oncology clinical trial success rate.

Applying single cell multi-omic analyses to understand treatment resistance in pediatric high grade glioma

Despite improvements in cancer patient outcomes seen in the past decade, tumor resistance to therapy remains a major impediment to achieving durable clinical responses. Intratumoral heterogeneity related to genetic, epigenetic, transcriptomic, proteomic, and metabolic differences between individual cancer cells has emerged as a driver of therapeutic resistance. This cell to cell heterogeneity can be assessed using single cell profiling technologies that enable the identification of tumor cell clones that exhibit similar defining features like specific mutations or patterns of DNA methylation. Single cell profiling of tumors before and after treatment can generate new insights into the cancer cell characteristics that confer therapeutic resistance by identifying intrinsically resistant sub-populations that survive treatment and by describing new cellular features that emerge post-treatment due to tumor cell evolution. Integrative, single cell analytical approaches have already proven advantageous in studies characterizing treatment-resistant clones in cancers where pre- and post-treatment patient samples are readily available, such as leukemia. In contrast, little is known about other cancer subtypes like pediatric high grade glioma, a class of heterogeneous, malignant brain tumors in children that rapidly develop resistance to multiple therapeutic modalities, including chemotherapy, immunotherapy, and radiation. Leveraging single cell multi-omic technologies to analyze naïve and therapy-resistant glioma may lead to the discovery of novel strategies to overcome treatment resistance in brain tumors with dismal clinical outcomes. In this review, we explore the potential for single cell multi-omic analyses to reveal mechanisms of glioma resistance to therapy and discuss opportunities to apply these approaches to improve long-term therapeutic response in pediatric high grade glioma and other brain tumors with limited treatment options.

Histone H3K9 methyltransferase SETDB1 overexpression correlates with pediatric high-grade gliomas progression and prognosis

Pediatric high-grade gliomas (pHGGs) are heterogeneous, diffuse, and highly infiltrative tumors with dismal prognosis. Aberrant post-translational histone modifications with elevated histone 3 lysine trimethylation (H3K9me3) have been recently implicated in pHGGs' pathology, conferring to tumor heterogeneity. The present study investigates the potential involvement of H3K9me3 methyltransferase SETDB1 in the cellular function, progression, and clinical significance of pHGG. The bioinformatic analysis detected SETDB1 enrichment in pediatric gliomas compared to the normal brain, as well as positive and negative correlations with a proneural and mesenchymal signature, respectively. In our cohort of pHGGs, SETDB1 expression was significantly increased compared to pLGG and normal brain tissue and correlated with p53 expression, as well as reduced patients' survival. In accordance, H3K9me3 levels were also elevated in pHGG compared to the normal brain and were associated with worse patient survival. Gene silencing of SETDB1 in two patient-derived pHGG cell lines showed a significant reduction in cell viability followed by reduced cell proliferation and increased apoptosis. SETDB1 silencing further reduced cell migration of pHGG cells and the expression of the mesenchymal markers N-cadherin and vimentin. mRNA analysis of epithelial-mesenchymal transition (EMT) markers upon SETDB1 silencing showed a reduction in SNAI1 levels and downregulation of CDH2 along with the EMT regulator gene MARCKS. In addition, SETDB1 silencing significantly increased the bivalent tumor suppressor gene SLC17A7 mRNA levels in both cell lines, indicating its implication in the oncogenic process.Altogether, our findings demonstrate a predominant oncogenic role of SETDB1 in pHGG which along with elevated H3K9me3 levels correlate significantly to tumor progression and inferior patients' survival. There is evidence that targeting SETDB1 may effectively inhibit pHGG progression, providing a novel insight into the therapeutic strategies for pediatric gliomas. KEY MESSAGES: SETDB1 gene expression is enriched in pHGG compared to normal brain. SETDB1 expression is increased in pHGG tissues and associates with reduced patients' survival. Gene silencing of SETDB1 reduces cell viability and migration. SETDB1 silencing affects mesenchymal markers expression. SETDB1 silencing upregulates SLC17A7 levels. SETDB1 has an oncogenic role in pHGG.

Pediatric spinal cord diffuse midline glioma with H3 K27M-alteration with leptomeningeal dissemination: a rare case with intracranial hypertension onset and no spinal cord-related symptom

PURPOSE

Spinal cord diffuse midline glioma (DMG) with H3 K27-alteration is a group of spinal cord high-grade glioma with poor outcome. We present a case with rare onset symptom pattern of pediatric spinal DMG, contributing to the understanding of the clinical presentations and natural history of pediatric spinal cord DMG.

METHODS AND RESULTS

A 7-year-old boy was admitted due to symptoms of intracranial hypertension without obvious spinal cord-related symptoms. Head radiological examinations, blood and cerebral spinal fluid tests did not support intracranial lesion, infection, or autoimmune diseases. Spinal magnetic resonance imaging revealed intraspinal occupying lesion with leptomeningeal dissemination. Pathology of the lesion verified DMG with H3 K27M-alteration.

CONCLUSION

Pediatric DMG with leptomeningeal dissemination could present with initial symptoms of intracranial hypertension without obvious spinal cord-related symptoms. Spinal cord examinations in cases of intracranial hypertension with negative head radiological examination results could be valuable in finding the etiology.

The emerging applications and advancements of Raman spectroscopy in pediatric cancers

Although the survival rate of pediatric cancer has significantly improved, it is still an important cause of death among children. New technologies have been developed to improve the diagnosis, treatment, and prognosis of pediatric cancers. Raman spectroscopy (RS) is a non-destructive analytical technique that uses different frequencies of scattering light to characterize biological specimens. It can provide information on biological components, activities, and molecular structures. This review summarizes studies on the potential of RS in pediatric cancers. Currently, studies on the application of RS in pediatric cancers mainly focus on early diagnosis, prognosis prediction, and treatment improvement. The results of these studies showed high accuracy and specificity. In addition, the combination of RS and deep learning is discussed as a future application of RS in pediatric cancer. Studies applying RS in pediatric cancer illustrated good prospects. This review collected and analyzed the potential clinical applications of RS in pediatric cancers.

How I treat recurrent pediatric high-grade glioma (pHGG): a Europe-wide survey study

PURPOSE

As there is no standard of care treatment for recurrent/progressing pediatric high-grade gliomas (pHGG), we aimed to gain an overview of different treatment strategies.

METHODS

In a web-based questionnaire, members of the SIOPE-BTG and the GPOH were surveyed on therapeutic options in four case scenarios (children/adolescents with recurrent/progressing HGG).

RESULTS

139 clinicians with experience in pediatric neuro-oncology from 22 European countries participated in the survey. Most respondents preferred further oncological treatment in three out of four cases and chose palliative care in one case with marked symptoms. Depending on the case, 8-92% would initiate a re-resection (preferably hemispheric pHGG), combined with molecular diagnostics. Throughout all case scenarios, 55-77% recommended (re-)irradiation, preferably local radiotherapy > 20 Gy. Most respondents would participate in clinical trials and use targeted therapy (79-99%), depending on molecular genetic findings (BRAF alterations: BRAF/MEK inhibitor, 64-88%; EGFR overexpression: anti-EGFR treatment, 46%; CDKN2A deletion: CDK inhibitor, 18%; SMARCB1 deletion: EZH2 inhibitor, 12%). 31-72% would administer chemotherapy (CCNU, 17%; PCV, 8%; temozolomide, 19%; oral etoposide/trofosfamide, 8%), and 20-69% proposed immunotherapy (checkpoint inhibitors, 30%; tumor vaccines, 16%). Depending on the individual case, respondents would also include bevacizumab (6-18%), HDAC inhibitors (4-15%), tumor-treating fields (1-26%), and intraventricular chemotherapy (4-24%).

CONCLUSION

In each case, experts would combine conventional multimodal treatment concepts, including re-irradiation, with targeted therapy based on molecular genetic findings. International cooperative trials combining a (chemo-)therapy backbone with targeted therapy approaches for defined subgroups may help to gain valid clinical data and improve treatment in pediatric patients with recurrent/progressing HGG.

Addressing blood-brain-tumor-barrier heterogeneity in pediatric brain tumors with innovative preclinical models

Brain tumors represent the leading cause of disease-related mortality and morbidity in children, with effective treatments urgently required. One factor limiting the effectiveness of systemic therapy is the blood-brain-barrier (BBB), which limits the brain penetration of many anticancer drugs. BBB integrity is often compromised in tumors, referred to as the blood-brain-tumor-barrier (BBTB), and the impact of a compromised BBTB on the therapeutic sensitivity of brain tumors has been clearly shown for a few selected agents. However, the heterogeneity of barrier alteration observed within a single tumor and across distinct pediatric tumor types represents an additional challenge. Herein, we discuss what is known regarding the heterogeneity of tumor-associated vasculature in pediatric brain tumors. We discuss innovative and complementary preclinical model systems that will facilitate real-time functional analyses of BBTB for all pediatric brain tumor types. We believe a broader use of these preclinical models will enable us to develop a greater understanding of the processes underlying tumor-associated vasculature formation and ultimately more efficacious treatment options.

Pediatric diffuse midline glioma H3K27- altered: A complex clinical and biological landscape behind a neatly defined tumor type

The 2021 World Health Organization Classification of Tumors of the Central Nervous System, Fifth Edition (WHO-CNS5), has strengthened the concept of tumor grade as a combination of histologic features and molecular alterations. The WHO-CNS5 tumor type "Diffuse midline glioma, H3K27-altered," classified within the family of "Pediatric-type diffuse high-grade gliomas," incarnates an ideally perfect integrated diagnosis in which location, histology, and genetics clearly define a specific tumor entity. It tries to evenly characterize a group of neoplasms that occur primarily in children and midline structures and that have a dismal prognosis. Such a well-defined pathological categorization has strongly influenced the pediatric oncology community, leading to the uniform treatment of most cases of H3K27-altered diffuse midline gliomas (DMG), based on the simplification that the mutation overrides the histological, radiological, and clinical characteristics of such tumors. Indeed, multiple studies have described pediatric H3K27-altered DMG as incurable tumors. However, in biology and clinical practice, exceptions are frequent and complexity is the rule. First of all, H3K27 mutations have also been found in non-diffuse gliomas. On the other hand, a minority of DMGs are H3K27 wild-type but have a similarly poor prognosis. Furthermore, adult-type tumors may rarely occur in children, and differences in prognosis have emerged between adult and pediatric H3K27-altered DMGs. As well, tumor location can determine differences in the outcome: patients with thalamic and spinal DMG have significantly better survival. Finally, other concomitant molecular alterations in H3K27 gliomas have been shown to influence prognosis. So, when such additional mutations are found, which one should we focus on in order to make the correct clinical decision? Our review of the current literature on pediatric diffuse midline H3K27-altered DMG tries to address such questions. Indeed, H3K27 status has become a fundamental supplement to the histological grading of pediatric gliomas; however, it might not be sufficient alone to exhaustively define the complex biological behavior of DMG in children and might not represent an indication for a unique treatment strategy across all patients, irrespective of age, additional molecular alterations, and tumor location.

Functional genomic analysis of adult and pediatric brain tumor isolates

Background

Adult and pediatric tumors display stark differences in their mutation spectra and chromosome alterations. Here, we attempted to identify common and unique gene dependencies and their associated biomarkers among adult and pediatric tumor isolates using functional genetic lethal screens and computational modeling.

Methods

We performed CRISRP-Cas9 lethality screens in two adult glioblastoma (GBM) tumor isolates and five pediatric brain tumor isolates representing atypical teratoid rhabdoid tumors (ATRT), diffuse intrinsic pontine glioma, GBM, and medulloblastoma. We then integrated the screen results with machine learning-based gene-dependency models generated from data from >900 cancer cell lines.

Results

We found that >50% of candidate dependencies of 280 identified were shared between adult GBM tumors and individual pediatric tumor isolates. 68% of screen hits were found as nodes in our network models, along with shared and tumor-specific predictors of gene dependencies. We investigated network predictors associated with ADAR, EFR3A, FGFR1 (pediatric-specific), and SMARCC2 (ATRT-specific) gene dependency among our tumor isolates.

Conclusions

The results suggest that, despite harboring disparate genomic signatures, adult and pediatric tumor isolates share a preponderance of genetic dependences. Further, combining data from primary brain tumor lethality screens with large cancer cell line datasets produced valuable insights into biomarkers of gene dependency, even for rare cancers.

Importance of the Study

Our results demonstrate that large cancer cell lines data sets can be computationally mined to identify known and novel gene dependency relationships in adult and pediatric human brain tumor isolates. Gene dependency networks and lethality screen results represent a key resource for neuro-oncology and cancer research communities. We also highlight some of the challenges and limitations of this approach.

Evaluating preclinical evidence for clinical translation in childhood brain tumours: Guidelines from the CONNECT, PNOC, and ITCC brain networks

Clinical outcomes for many childhood brain tumours remain poor, despite our increasing understanding of the underlying disease biology. Advances in molecular diagnostics have refined our ability to classify tumour types and subtypes, and efforts are underway across multiple international paediatric neuro-oncology consortia to take novel biological insights in the worst prognosis entities into innovative clinical trials. Whilst for the first time we are designing such studies on the basis of disease-specific biological data, the levels of preclincial evidence in appropriate model systems on which these trials are initiated is still widely variable. We have considered these issues between CONNECT, PNOC and ITCC-Brain, and developed a framework in which we can assess novel concepts being brought forward for possible clinical translation. Whilst not intended to be proscriptive for every possible circumstance, these criteria provide a basis for self-assessment of evidence by laboratory scientists, and a platform for discussion and rational decision-making prior to moving forward clinically.

Amplification of the PLAG-family genes-PLAGL1 and PLAGL2-is a key feature of the novel tumor type CNS embryonal tumor with PLAGL amplification

Pediatric central nervous system (CNS) tumors represent the most common cause of cancer-related death in children aged 0-14 years. They differ from their adult counterparts, showing extensive clinical and molecular heterogeneity as well as a challenging histopathological spectrum that often impairs accurate diagnosis. Here, we use DNA methylation-based CNS tumor classification in combination with copy number, RNA-seq, and ChIP-seq analysis to characterize a newly identified CNS tumor type. In addition, we report histology, patient characteristics, and survival data in this tumor type. We describe a biologically distinct pediatric CNS tumor type (n = 31 cases) that is characterized by focal high-level amplification and resultant overexpression of either PLAGL1 or PLAGL2, and an absence of recurrent genetic alterations characteristic of other pediatric CNS tumor types. Both genes act as transcription factors for a regulatory subset of imprinted genes (IGs), components of the Wnt/β-Catenin pathway, and the potential drug targets RET and CYP2W1, which are also specifically overexpressed in this tumor type. A derived PLAGL-specific gene expression signature indicates dysregulation of imprinting control and differentiation/development. These tumors occurred throughout the neuroaxis including the cerebral hemispheres, cerebellum, and brainstem, and were predominantly composed of primitive embryonal-like cells lacking robust expression of markers of glial or neuronal differentiation (e.g., GFAP, OLIG2, and synaptophysin). Tumors with PLAGL1 amplification were typically diagnosed during adolescence (median age 10.5 years), whereas those with PLAGL2 amplification were diagnosed during early childhood (median age 2 years). The 10-year overall survival was 66% for PLAGL1-amplified tumors, 25% for PLAGL2-amplified tumors, 18% for male patients, and 82% for female patients. In summary, we describe a new type of biologically distinct CNS tumor characterized by PLAGL1/2 amplification that occurs predominantly in infants and toddlers (PLAGL2) or adolescents (PLAGL1) which we consider best classified as a CNS embryonal tumor and which is associated with intermediate survival. The cell of origin and optimal treatment strategies remain to be defined.

Low-pass whole-genome and targeted sequencing of cell-free DNA from cerebrospinal fluid in pediatric patients with central nervous system tumors

Background

Central nervous system tumors are the most common pediatric solid tumors and the most frequent cause of cancer-related morbidity in childhood. Significant advances in understanding the molecular features of these tumors have facilitated the development of liquid biopsy assays that may aid in diagnosis and monitoring response to therapy. In this report, we describe our comprehensive liquid biopsy platform for detection of genome-wide copy number aberrations, sequence variants, and gene fusions using cerebrospinal fluid (CSF) from pediatric patients with brain, spinal cord, and peripheral nervous system tumors.

Methods

Cell-free DNA was isolated from the CSF from 55 patients, including 47 patients with tumors and 8 controls.

Results

Abnormalities in cell-free DNA were detected in 24 (51%) patients including 11 with copy number alterations, 9 with sequence variants, and 7 with KIAA1549::BRAF fusions. Positive findings were obtained in patients spanning histologic subtypes, tumor grades, and anatomic locations.

Conclusions

This study demonstrates the feasibility of employing this platform in routine clinical care in upfront diagnostic and monitoring settings. Future studies are required to determine the utility of this approach for assessing response to therapy and long-term surveillance.

Inter and intra-tumor heterogeneity of paediatric type diffuse high-grade gliomas revealed by single-cell mass cytometry

Paediatric-type diffuse high-grade gliomas (PDHGG) are aggressive tumors affecting children and young adults, with no effective treatment. These highly heterogeneous malignancies arise in different sites of the Central Nervous System (CNS), carrying distinctive molecular alterations and clinical outcomes (inter-tumor heterogeneity). Moreover, deep cellular and molecular profiling studies highlighted the coexistence of genetically and phenotypically different subpopulations within the same tumor mass (intra-tumor heterogeneity). Despite the recent advances made in the field, the marked heterogeneity of PDHGGs still impedes the development of effective targeted therapies and the identification of suitable biomarkers. In order to fill the existing gap, we used mass cytometry to dissect PDHGG inter- and intra-heterogeneity. This is one of the most advanced technologies of the "-omics" era that, using antibodies conjugated to heavy metals, allows the simultaneous measurement of more than 40 markers at single-cell level. To this end, we analyzed eight PDHGG patient-derived cell lines from different locational and molecular subgroups. By using a panel of 15 antibodies, directly conjugated to metals or specifically customized to detect important histone variants, significant differences were highlighted in the expression of the considered antigens. The single-cell multiparametric approach realized has deepened our understanding of PDHGG, confirming a high degree of intra- and inter-tumoral heterogeneity and identifying some antigens that could represent useful biomarkers for the specific PDHGG locational or molecular subgroups.

Three-Dimensional Cell Culture Systems in Pediatric and Adult Brain Tumor Precision Medicine

Primary brain tumors often possess a high intra- and intertumoral heterogeneity, which fosters insufficient treatment response for high-grade neoplasms, leading to a dismal prognosis. Recent years have seen the emergence of patient-specific three-dimensional in vitro models, including organoids. They can mimic primary parenteral tumors more closely in their histological, transcriptional, and mutational characteristics, thus approximating their intratumoral heterogeneity better. These models have been established for entities including glioblastoma and medulloblastoma. They have proven themselves to be reliable platforms for studying tumor generation, tumor-TME interactions, and prediction of patient-specific responses to establish treatment regimens and new personalized therapeutics. In this review, we outline current 3D cell culture models for adult and pediatric brain tumors, explore their current limitations, and summarize their applications in precision oncology.

The Transcriptomic Landscape of Pediatric Astrocytoma

Central nervous system tumors are the most common solid neoplasia during childhood and represent one of the leading causes of cancer-related mortality. Tumors arising from astrocytic cells (astrocytomas) are the most frequently diagnosed, and according to their histological and pathological characteristics, they are classified into four categories. However, an additional layer of molecular classification considering the DNA sequence of the tumorigenesis-associated genes IDH1/2 and H3F3A has recently been incorporated into the classification guidelines. Although mutations in H3F3A are found exclusively in a subtype of grade IV pediatric astrocytoma, mutations in IDH1/2 genes are very rare in children under 14 years of age. The transcriptomic profiles of astrocytoma in adults and children have been extensively studied. However, there is scarce information on these profiles in pediatric populations considering the status of tumorigenesis-associated genes. Therefore, here we report the transcriptomic landscape of the four grades of pediatric astrocytoma by RNA sequencing. We found several well-documented biological functions associated with the misregulated genes in the four grades of astrocytoma, as well as additional biological pathways. Among the four grades of astrocytoma, we found shared misregulated genes that could have implications in tumorigenesis. Finally, we identified a transcriptional signature for almost all grades of astrocytoma that could be used as a transcription-based identification method.

News from around the RNA world: new avenues in RNA biology, biotechnology and therapeutics from the 2022 SIBBM meeting

Since the formalization of the Central Dogma of molecular biology, the relevance of RNA in modulating the flow of information from DNA to proteins has been clear. More recently, the discovery of a vast set of non-coding transcripts involved in crucial aspects of cellular biology has renewed the enthusiasm of the RNA community. Moreover, the remarkable impact of RNA therapies in facing the COVID19 pandemics has bolstered interest in the translational opportunities provided by this incredible molecule. For all these reasons, the Italian Society of Biophysics and Molecular Biology (SIBBM) decided to dedicate its 17th yearly meeting, held in June 2022 in Rome, to the many fascinating aspects of RNA biology. More than thirty national and international speakers covered the properties, modes of action and applications of RNA, from its role in the control of development and cell differentiation to its involvement in disease. Here, we summarize the scientific content of the conference, highlighting the take-home message of each presentation, and we stress the directions the community is currently exploring to push forward our comprehension of the RNA World 3.0.

The emerging role of pyroptosis in pediatric cancers: from mechanism to therapy

Pediatric cancers are the driving cause of death for children and adolescents. Due to safety requirements and considerations, treatment strategies and drugs for pediatric cancers have been so far scarcely studied. It is well known that tumor cells tend to progressively evade cell death pathways, which is known as apoptosis resistance, one of the hallmarks of cancer, dominating tumor drug resistance. Recently, treatments targeting nonapoptotic cell death have drawn great attention. Pyroptosis, a newly specialized form of cell death, acts as a critical physiological regulator in inflammatory reaction, cell development, tissue homeostasis and stress response. The action in different forms of pyroptosis is of great significance in the therapy of pediatric cancers. Pyroptosis could be induced and consequently modulate tumorigenesis, progression, and metastasis if treated with local or systemic therapies. However, excessive or uncontrolled cell death might lead to tissue damage, acute inflammation, or even cytokine release syndrome, which facilitates tumor progression or recurrence. Herein, we aimed to describe the molecular mechanisms of pyroptosis, to highlight and discuss the challenges and opportunities for activating pyroptosis pathways through various oncologic therapies in multiple pediatric neoplasms, including osteosarcoma, neuroblastoma, leukemia, lymphoma, and brain tumors.

Anlotinib combined with temozolomide for the treatment of patients with diffuse midline glioma: a case report and literature review

BACKGROUND

Diffuse midline glioma with a histone H3-K27M mutation is a brand-new tumor entity according to the 2016 edition of World Health Organization (WHO) classification. As diffuse midline gliomas are aggressive and incurable brain tumors, characterized by high levels of intrinsic and acquired resistance to therapy, as well as conventional treatment can hardly work due to an intact blood-brain barrier, leading to very poor outcomes for patients. Anlotinib is a multitarget tyrosine kinase inhibitor and has been used for the treatment of multiple tumor species, with satisfying outcomes. However, anlotinib has not been reported for the treatment of patients with diffuse midline glioma.

CASE DESCRIPTION

This is a case report about a 51-year-old man suffering from diffuse midline glioma with a histone H3-K27M mutation. After surgery, the patient underwent chemoradiation treatment and then adjuvant temozolomide (TMZ). After 7 months, the tumor had enlarged with severe peritumor edema and hydrocephalus. Bevacizumab was treated for 3 cycles, and then the treatment was changed to anlotinib combined with TMZ. After 8 months, magnetic resonance imaging (MRI) scans showed that the mass was significantly reduced compared with before targeted therapy. Until the present time, the patient has survived for 20 months.

CONCLUSIONS

Therapy combining anlotinib with TMZ is potential therapeutic option for the patients with diffuse midline glioma.