Pediatric Low-Grade Gliomas. Cancers (Basel). 2020;12. [PMID: 32375301 PMCID: PMC7281318 DOI: 10.3390/cancers12051152]

The role of focused ultrasound for pediatric brain tumors: current insights and future implications on treatment strategies

INTRODUCTION

Focused ultrasound (FUS) is an innovative and emerging technology for the treatment of adult and pediatric brain tumors and illustrates the intersection of various specialized fields, including neurosurgery, neuro-oncology, radiation oncology, and biomedical engineering.

OBJECTIVE

The authors provide a comprehensive overview of the application and implications of FUS in treating pediatric brain tumors, with a special focus on pediatric low-grade gliomas (pLGGs) and the evolving landscape of this technology and its clinical utility.

METHODS

The fundamental principles of FUS include its ability to induce thermal ablation or enhance drug delivery through transient blood-brain barrier (BBB) disruption, emphasizing the adaptability of high-intensity focused ultrasound (HIFU) and low-intensity focused ultrasound (LIFU) applications.

RESULTS

Several ongoing clinical trials explore the potential of FUS in offering alternative therapeutic strategies for pathologies where conventional treatments fall short, specifically centrally-located benign CNS tumors and diffuse intrinsic pontine glioma (DIPG). A case illustration involving the use of HIFU for pilocytic astrocytoma is presented.

CONCLUSION

Discussions regarding future applications of FUS for the treatment of gliomas include improved drug delivery, immunomodulation, radiosensitization, and other technological advancements.

Dissecting the Natural Patterns of Progression and Senescence in Pediatric Low-Grade Glioma: From Cellular Mechanisms to Clinical Implications

Pediatric low-grade gliomas (PLGGs) comprise a heterogeneous set of low-grade glial and glioneuronal tumors, collectively representing the most frequent CNS tumors of childhood and adolescence. Despite excellent overall survival rates, the chronic nature of the disease bears a high risk of long-term disease- and therapy-related morbidity in affected patients. Recent in-depth molecular profiling and studies of the genetic landscape of PLGGs led to the discovery of the paramount role of frequent upregulation of RAS/MAPK and mTOR signaling in tumorigenesis and progression of these tumors. Beyond, the subsequent unveiling of RAS/MAPK-driven oncogene-induced senescence in these tumors may shape the understanding of the molecular mechanisms determining the versatile progression patterns of PLGGs, potentially providing a promising target for novel therapies. Recent in vitro and in vivo studies moreover indicate a strong dependence of PLGG formation and growth on the tumor microenvironment. In this work, we provide an overview of the current understanding of the multilayered cellular mechanisms and clinical factors determining the natural progression patterns and the characteristic biological behavior of these tumors, aiming to provide a foundation for advanced stratification for the management of these tumors within a multimodal treatment approach.

Role of intraoperative ultrasound and MRI to aid grade of resection of pediatric low-grade gliomas: accumulated experience from 4 centers

PURPOSE

Pediatric low-grade gliomas (pLGG) are the most common brain tumors in children and achieving complete resection (CR) in pLGG is the most important prognostic factor. There are multiple intraoperative tools to optimize the extent of resection (EOR). This article investigates and discusses the role of intraoperative ultrasound (iUS) and intraoperative magnetic resonance imaging (iMRI) in the surgical treatment of pLGG.

METHODS

The tumor registries at Tuebingen, Rome and Pretoria were searched for pLGG with the use of iUS and data on EOR. The tumor registries at Liverpool and Tuebingen were searched for pLGG with the use of iMRI where preoperative CR was the surgical intent. Different iUS and iMRI machines were used in the 4 centers.

RESULTS

We included 111 operations which used iUS and 182 operations using iMRI. Both modalities facilitated intended CR in hemispheric supra- and infratentorial location in almost all cases. In more deep-seated tumor location like supratentorial midline tumors, iMRI has advantages over iUS to visualize residual tumor. Functional limitations limiting CR arising from eloquent involved or neighboring brain tissue apply to both modalities in the same way. In the long-term follow-up, both iUS and iMRI show that achieving a complete resection on intraoperative imaging significantly lowers recurrence of disease (chi-square test, p < 0.01).

CONCLUSION

iUS and iMRI have specific pros and cons, but both have been proven to improve achieving CR in pLGG. Due to advances in image quality, cost- and time-efficiency, and efforts to improve the user interface, iUS has emerged as the most accessible surgical adjunct to date to aid and guide tumor resection. Since the EOR has the most important effect on long-term outcome and disease control of pLGG in most locations, we strongly recommend taking all possible efforts to use iUS in any surgery, independent of intended resection extent and iMRI if locally available.

Longitudinal risk prediction for pediatric glioma with temporal deep learning

Pediatric glioma recurrence can cause morbidity and mortality; however, recurrence pattern and severity are heterogeneous and challenging to predict with established clinical and genomic markers. Resultingly, almost all children undergo frequent, long-term, magnetic resonance (MR) brain surveillance regardless of individual recurrence risk. Deep learning analysis of longitudinal MR may be an effective approach for improving individualized recurrence prediction in gliomas and other cancers but has thus far been infeasible with current frameworks. Here, we propose a self-supervised, deep learning approach to longitudinal medical imaging analysis, temporal learning, that models the spatiotemporal information from a patient's current and prior brain MRs to predict future recurrence. We apply temporal learning to pediatric glioma surveillance imaging for 715 patients (3,994 scans) from four distinct clinical settings. We find that longitudinal imaging analysis with temporal learning improves recurrence prediction performance by up to 41% compared to traditional approaches, with improvements in performance in both low- and high-grade glioma. We find that recurrence prediction accuracy increases incrementally with the number of historical scans available per patient. Temporal deep learning may enable point-of-care decision-support for pediatric brain tumors and be adaptable more broadly to patients with other cancers and chronic diseases undergoing surveillance imaging.

Advances in pediatric gliomas: from molecular characterization to personalized treatments

Pediatric gliomas, consisting of both pediatric low-grade (pLGG) and high-grade gliomas (pHGG), are the most frequently occurring brain tumors in children. Over the last decade, several milestone advancements in treatments have been achieved as a result of stronger understanding of the molecular biology behind these tumors. This review provides an overview of pLGG and pHGG highlighting their clinical presentation, molecular characteristics, and latest advancements in therapeutic treatments.  Conclusion: The increasing understanding of the molecular biology characterizing pediatric low and high grade gliomas has revolutionized treatment options for these patients, especially in pLGG. The implementation of next generation sequencing techniques for these tumors is crucial in obtaining less toxic and more efficacious treatments. What is Known: • Pediatric Gliomas are the most common brain tumour in children. They are responsible for significant morbidity and mortality in this population. What is New: • Over the last two decades, there has been a significant increase in our global understanding of the molecular background of pediatric low and high grade gliomas. • The implementation of next generation sequencing techniques for these tumors is crucial in obtaining less toxic and more efficacious treatments, with the ultimate goal of improving both the survival and the quality of life of these patients.

Pediatric high grade gliomas: A comprehensive histopathological, immunohistochemical and molecular integrated approach in routine practice

Pediatric high grade gliomas have undergone remarkable changes in recent time with discovery of new molecular pathways. They have been added separately in current WHO 2021 blue book. All the entities show characteristic morphology and immunohistochemistry. Methylation data correctly identifies these entities into particular group of clusters. The pediatric group high grade glioma comprises- Diffuse midline glioma, H3K27-altered; Diffuse hemispheric glioma, H3G34-mutant; Diffuse pediatric-type high-grade glioma, H3-wild type & IDH-wild type; Infant hemispheric glioma and Epithelioid glioblastoma/Grade 3 pleomorphic xanthoastrocytoma and very rare IDH-mutant astrocytoma. However it is not always feasible to perform these molecular tests where cost-effective diagnosis is a major concern. Here we discuss the major entities with their characteristic histopathology, immunohistochemistry and molecular findings that may help to reach to suggest the diagnosis and help the clinician for appropriate treatment strategies. We have also made a simple algorithmic flow chart integrated with histopathology, immunohistochemistry and molecular characteristics for better understanding.

Glutathione metabolism-related gene signature predicts prognosis and treatment response in low-grade glioma

Cancer cells can induce molecular changes that reshape cellular metabolism, creating specific vulnerabilities for targeted therapeutic interventions. Given the importance of reactive oxygen species (ROS) in tumor development and drug resistance, and the abundance of reduced glutathione (GSH) as the primary cellular antioxidant, we examined an integrated panel of 56 glutathione metabolism-related genes (GMRGs) across diverse cancer types. This analysis revealed a remarkable association between GMRGs and low-grade glioma (LGG) survival. Unsupervised clustering and a GMRGs-based risk score (GS) categorized LGG patients into two groups, linking elevated glutathione metabolism to poorer prognosis and treatment outcomes. Our GS model outperformed established clinical prognostic factors, acting as an independent prognostic factor. GS also exhibited correlations with pro-tumor M2 macrophage infiltration, upregulated immunosuppressive genes, and diminished responses to various cancer therapies. Experimental validation in glioma cell lines confirmed the critical role of glutathione metabolism in glioma cell proliferation and chemoresistance. Our findings highlight the presence of a unique metabolic susceptibility in LGG and introduce a novel GS system as a highly effective tool for predicting the prognosis of LGG.

Laser interstitial thermal therapy (LITT) for pediatric low-grade glioma-case presentations and lessons learned

BACKGROUND

The surgical treatment of brain tumors has developed over time, offering customized strategies for patients and their specific lesions. One of the most recent advances in pediatric neuro-oncological surgery is laser interstitial thermal therapy (LITT). However, its effectiveness and indications are still being evaluated. The aim of this work is to review the current literature on LITT for pediatric low-grade gliomas (pLGG) and evaluate our initial results in this context.

METHODS

We retrospectively reviewed our pediatric neurosurgery database for patients who received LITT treatment between November 2019 and December 2023. We collected data on the indications for LITT, technical issues during the procedure, and clinical and radiological follow-up.

RESULTS

Three patients underwent 5 LITT procedures for pLGG. The lesion was thalamo-peduncular in one patient, cingulate in one, and deep parietal in one patient. Two patients had a previous open resection done and were diagnosed with pLGG. One patient underwent a stereotaxic biopsy during the LITT procedure that was non-diagnostic. The same patient underwent a later open resection of the tumor in the cingulate gyrus. There were no surgical complications and all patients were discharged home on the first post-operative day. The follow-up period was between 20 and 40 months. Radiological follow-up showed a progressive reduction of the tumor in patients with LGG.

CONCLUSION

Laser interstitial thermal therapy is a minimally invasive treatment that shows promise in treating deep-seated pLGG in children. The treatment has demonstrated a reduction in tumor volume, and the positive results continue over time. LITT can be used as an alternative treatment for tumors located in areas that are difficult to access surgically or in cases where other standard treatment options have failed.

DMRTA2 supports glioma stem-cell mediated neovascularization in glioblastoma

Glioblastoma (GBM) is the most common and lethal brain tumor in adults. Due to its fast proliferation, diffusive growth and therapy resistance survival times are less than two years for patients with IDH-wildtype GBM. GBM is noted for the considerable cellular heterogeneity, high stemness indices and abundance of the glioma stem-like cells known to support tumor progression, therapeutic resistance and recurrence. Doublesex- and mab-3-related transcription factor a2 (DMRTA2) is involved in maintaining neural progenitor cells (NPC) in the cell cycle and its overexpression suppresses NPC differentiation. Despite the reports showing that primary GBM originates from transformed neural stem/progenitors cells, the role of DMRTA2 in gliomagenesis has not been elucidated so far. Here we show the upregulation of DMRTA2 expression in malignant gliomas. Immunohistochemical staining showed the protein concentrated in small cells with high proliferative potential and cells localized around blood vessels, where it colocalizes with pericyte-specific markers. Knock-down of DMRTA2 in human glioma cells impairs proliferation but not viability of the cells, and affects the formation of the tumor spheres, as evidenced by strong decrease in the number and size of spheres in in vitro cultures. Moreover, the knockdown of DMRTA2 in glioma spheres affects the stabilization of the glioma stem-like cell-dependent tube formation in an in vitro angiogenesis assay. We conclude that DMRTA2 is a new player in gliomagenesis and tumor neovascularization and due to its high expression in malignant gliomas could be a biomarker and potential target for new therapeutic strategies in glioblastoma.

Histological types of brain tumors diagnosed at the Kenyatta National Hospital between 2016 and 2019: a retrospective study

PURPOSE

To determine the histological types of brain tumors diagnosed at the Kenyatta National Hospital, Nairobi, Kenya.

METHODS

This retrospective study retrieved patient-archived records at the Kenyatta National Hospital for the period 2016-2019. The histological types of brain tumors were assessed according to age, sex, and the WHO classification for CNS tumors using the GNU PSPP version 1.6.2-g78a33 software. Results were presented in tables and figures.

RESULTS

During the study period, brain tumors appeared to increase gradually; however, there was a decline in 2018. During the study period, 345 brain tumor records were retrieved. Data on age were missing 33 records; hence, 312 records were included for age analyses. The mean age for the pediatrics and adults was 9 (± 5 SD) and 45 (± 14 SD) years, respectively. 88 (28.2%) and 224 (71.8%) tumors were diagnosed among pediatrics and adults, respectively. Most tumors, 60 (19.2%) were reported in patients aged ≤ 10 years, followed by 55 (17.6%), 48 (15.4%), and 47 (15.1%) in patients aged 31-40, 51-60, and 41-50, years, respectively. In both pediatrics and adults, most tumors were diagnosed in females aged ≤ 10 years and 31-40 years, respectively. Overall, two peaks were observed in patients aged 5-15 years and 40-45 years. Gliomas, 43 (48.9%) and medulloblastomas, 21 (23.9%) were the most common tumors in pediatrics, whereas meningiomas, 107 (47.8%) and gliomas, 70 (31.3%) were the most common tumors in adults. Most pediatric and adult tumors were benign with 50 (56.8%) and 157 (70.1%) cases, respectively. Low-grade gliomas and medulloblastomas were the commonest benign and malignant tumors among pediatrics, with 31 (62%) and 21 (55.3%) cases, respectively. Conversely, meningiomas and high-grade gliomas were the most common benign and malignant tumors in adults, with 106 (67.5%) and 44 (65.7%) cases, respectively.

CONCLUSION

This study highlights the existing burden of brain tumors in Kenya and data from KNH may be representative of the national burden of BTs. This study lays a foundation for subsequent clinical and epidemiological studies and emphasizes the need to adopt existing reporting standards to help realize a complete picture of the burden of brain tumors in Kenya.

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.

Fibroblast growth factor receptor 1 gene mutation as a potential risk factor for spontaneous intracranial hemorrhage in pediatric low-grade glioma patients

Background

Fibroblast growth factor receptor 1 (FGFR1) mutations have been associated with poorer prognoses in pediatric central nervous system tumor patients. A recent study highlighted a link between FGFR1 mutations and spontaneous intracranial hemorrhage (ICH), demonstrating that all patients with an FGFR1 alteration experienced hemorrhage at some point during their course of treatment.

Methods

The current study examined 50 out of 67 pediatric patients with low-grade gliomas (LGGs) who had genomic testing between 2011 and 2022 at our institution to determine whether a correlation exists between FGFR1 mutations and spontaneous ICH.

Results

We found that of the 50 patients with genomic data, 7 (14%) experienced ICH, and an additional spontaneous hemorrhage was recorded; however, no genomic testing was performed for this case. Five of the seven patients (71.4%) had an FGFR1 modification. In our patient population, 6 expressed a detectable FGFR1 mutation (66.7% [4/6] had N546K alteration, 16.7% [1/6] FGFR1 exons duplication, and 16.7% [1/6] had a variant of unknown significance [VUS]). The patient with the FGFR1 VUS had no reported spontaneous hemorrhage. Statistical analysis found a significant association between FGFR1 and spontaneous intracranial hemorrhage (P-value = < .0001). In the patient population, all cases of PTPN11 alterations (n = 3) co-occurred with FGFR1 mutations.

Conclusions

Our case series highlights this link between the FGFR1 mutation and spontaneous intracranial hemorrhage in pediatric LGGs.

Patient- and xenograft-derived organoids recapitulate pediatric brain tumor features and patient treatments

Brain tumors are the leading cause of cancer-related death in children. Experimental in vitro models that faithfully capture the hallmarks and tumor heterogeneity of pediatric brain cancers are limited and hard to establish. We present a protocol that enables efficient generation, expansion, and biobanking of pediatric brain cancer organoids. Utilizing our protocol, we have established patient-derived organoids (PDOs) from ependymomas, medulloblastomas, low-grade glial tumors, and patient-derived xenograft organoids (PDXOs) from medulloblastoma xenografts. PDOs and PDXOs recapitulate histological features, DNA methylation profiles, and intratumor heterogeneity of the tumors from which they were derived. We also showed that PDOs can be xenografted. Most interestingly, when subjected to the same routinely applied therapeutic regimens, PDOs respond similarly to the patients. Taken together, our study highlights the potential of PDOs and PDXOs for research and translational applications for personalized medicine.

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.

Integrative multi-omics reveals two biologically distinct groups of pilocytic astrocytoma

Pilocytic astrocytoma (PA), the most common pediatric brain tumor, is driven by aberrant mitogen-activated protein kinase signaling most commonly caused by BRAF gene fusions or activating mutations. While 5-year overall survival rates exceed 95%, tumor recurrence or progression constitutes a major clinical challenge in incompletely resected tumors. Here, we used similarity network fusion (SNF) analysis in an integrative multi-omics approach employing RNA transcriptomic and mass spectrometry-based proteomic profiling to molecularly characterize PA tissue samples from 62 patients. Thereby, we uncovered that PAs segregated into two molecularly distinct groups, namely, Group 1 and Group 2, which were validated in three non-overlapping cohorts. Patients with Group 1 tumors were significantly younger and showed worse progression-free survival compared to patients with group 2 tumors. Ingenuity pathways analysis (IPA) and gene set enrichment analysis (GSEA) revealed that Group 1 tumors were enriched for immune response pathways, such as interferon signaling, while Group 2 tumors showed enrichment for action potential and neurotransmitter signaling pathways. Analysis of immune cell-related gene signatures showed an enrichment of infiltrating T Cells in Group 1 versus Group 2 tumors. Taken together, integrative multi-omics of PA identified biologically distinct and prognostically relevant tumor groups that may improve risk stratification of this single pathway driven tumor type.

Seizure outcomes after resection of primary brain tumors in pediatric patients: a systematic review and meta-analysis

PURPOSE

Primary brain neoplasms are the most common solid tumors in pediatric patients and seizures are a common presenting symptom. Surgical intervention improves oncologic outcomes and seizure burden. A better understanding of factors that influence seizure outcomes in the surgical management of primary brain tumors of childhood can guide treatment approach thereby improving patient quality of life.

METHODS

We performed a systematic analysis using articles queried from PubMed, EMBASE, and Cochrane published from January 1990 to August 2022 to determine predictors of seizure outcomes in pediatric patients undergoing resection of primary brain tumors.

RESULTS

We identified 24 retrospective cohort studies, one prospective cohort study, and one mixed retrospective and prospective study for the systematic analysis. A total of 831 pediatric patients were available for analysis. 668 (80.4%) patients achieved seizure freedom after surgery. Complete tumor resection increased the likelihood of a seizure-free (Engel I) outcome compared to subtotal resection (OR 7.1, 95% CI 2.3-21.9). Rates of Engel I seizure outcomes did not significantly differ based on factors such as age at seizure onset, duration of epilepsy, gender, tumor laterality, or age at surgery, but trended towards significance for improved outcomes in temporal lobe tumors.

CONCLUSION

Primary brain tumors in the pediatric population are commonly associated with seizures. Resection of these lesions reduces seizure burden and is associated with high rates of seizure freedom. Complete resection, compared to subtotal resection, significantly increases the likelihood of seizure-free outcomes.

Genetically modified IL2 bone-marrow-derived myeloid cells reprogram the glioma immunosuppressive tumor microenvironment

Gliomas are one of the leading causes of cancer-related death in the adolescent and young adult (AYA) population. Two-thirds of AYA glioma patients are affected by low-grade gliomas (LGGs), but there are no specific treatments. Malignant progression is supported by the immunosuppressive stromal component of the tumor microenvironment (TME) exacerbated by M2 macrophages and a paucity of cytotoxic T cells. A single intravenous dose of engineered bone-marrow-derived myeloid cells that release interleukin-2 (GEMys-IL2) was used to treat mice with LGGs. Our results demonstrate that GEMys-IL2 crossed the blood-brain barrier, infiltrated the TME, and reprogrammed the immune cell composition and transcriptome. Moreover, GEMys-IL2 extended survival in an LGG immunocompetent mouse model. Here, we report the efficacy of an in vivo approach that demonstrates the potential for a cell-mediated innate immunotherapy designed to enhance the recruitment of activated effector T and natural killer cells within the glioma TME.

Cognitive and Behavioral Outcome of Pediatric Low-Grade Central Nervous System Tumors Treated Only with Surgery: A Single Center Experience

BACKGROUND

The present mono-institutional report aimed to describe the cognitive and behavioral outcomes of low-grade central nervous system (CNS) tumors in a cohort of children treated exclusively with surgical intervention.

METHODS

Medical records from 2000-2020 were retrospectively analyzed. We included 38 children (mean age at first evaluation 8 years and 3 months, 16 females) who had undergone presurgical cognitive-behavioral evaluation and/or at least 6 months follow-up. Exclusion criteria were a history of traumatic brain injury, stroke, cerebral palsy or cancer-predisposing syndromes.

RESULTS

The sample presented cognitive abilities and behavioral functioning in the normal range, with weaknesses in verbal working memory and processing speed. The obtained results suggest that cognitive and behavioral functioning is related to pre-treatment variables (younger age at symptoms' onset, glioneuronal histological type, cortical location with preoperative seizures), timing of surgery and seizure control after surgery, and is stable when controlling for a preoperative cognitive and behavioral baseline. Younger age at onset is confirmed as a particular vulnerability in determining cognitive sequelae, and children at older ages or at longer postsurgical follow-up are at higher risk for developing behavioral disturbances.

CONCLUSIONS

Timely treatment is an important factor influencing the global outcome and daily functioning of the patients. Preoperative and regular postsurgical cognitive and behavioral assessment, also several years after surgery, should be included in standard clinical practices.

Resection extent and BRAF V600E mutation status determine postoperative tumor growth velocity in pediatric low-grade glioma: results from a single-center cohort analysis

PURPOSE

Despite excellent long-term overall survival rates, pediatric low-grade gliomas (pLGG) show high variety of clinical behavior regarding progress or senescence post incomplete resection (IR). This study retrospectively analyzes tumor growth velocity (TGV) of pLGG before surgery and after IR to investigate the impact of surgical extent, tumor location and molecular BRAF status on postoperative residual tumor growth behavior.

METHODS

Of a total of 172 patients with pLGG receiving surgical treatment, 107 underwent IR (66%). Fifty-three vs 94 patients could be included in the pre- and post-operative cohort, respectively, and were observed over a mean follow-up time of 40.2 vs 60.1 months. Sequential three-dimensional MRI-based tumor volumetry of a total of 407 MRI scans was performed to calculate pre- and postoperative TGV.

RESULTS

Mean preoperative TGV of 0.264 cm3/month showed significant deceleration of tumor growth to 0.085 cm3/month, 0.024 cm3/month and -0.016 cm3/month after 1st, 2nd, and 3rd IR, respectively (p < 0.001). Results remained significant after excluding patients undergoing (neo)adjuvant treatment. Resection extent showed correlation with postoperative reduction of TGV (R = 0.97, p < 0.001). ROC analysis identified a residual cut-off tumor volume > 2.03 cm3 associated with a higher risk of progress post IR (sensitivity 78,6%, specificity 76.3%, AUC 0.88). Postoperative TGV of BRAF V600E-mutant LGG was significantly higher than of BRAF wild-type LGG (0.123 cm3/month vs. 0.016 cm3/month, p = 0.047).

CONCLUSION

This data suggests that extensive surgical resection may impact pediatric LGG growth kinetics post incomplete resection by inducing a significant deceleration of tumor growth. BRAF-V600E mutation may be a risk factor for higher postoperative TGV.

Joint EANM/SIOPE/RAPNO practice guidelines/SNMMI procedure standards for imaging of paediatric gliomas using PET with radiolabelled amino acids and [18F]FDG: version 1.0

Positron emission tomography (PET) has been widely used in paediatric oncology. 2-Deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) is the most commonly used radiopharmaceutical for PET imaging. For oncological brain imaging, different amino acid PET radiopharmaceuticals have been introduced in the last years. The purpose of this document is to provide imaging specialists and clinicians guidelines for indication, acquisition, and interpretation of [18F]FDG and radiolabelled amino acid PET in paediatric patients affected by brain gliomas. There is no high level of evidence for all recommendations suggested in this paper. These recommendations represent instead the consensus opinion of experienced leaders in the field. Further studies are needed to reach evidence-based recommendations for the applications of [18F]FDG and radiolabelled amino acid PET in paediatric neuro-oncology. These recommendations are not intended to be a substitute for national and international legal or regulatory provisions and should be considered in the context of good practice in nuclear medicine. The present guidelines/standards were developed collaboratively by the EANM and SNMMI with the European Society for Paediatric Oncology (SIOPE) Brain Tumour Group and the Response Assessment in Paediatric Neuro-Oncology (RAPNO) working group. They summarize also the views of the Neuroimaging and Oncology and Theranostics Committees of the EANM and reflect recommendations for which the EANM and other societies cannot be held responsible.

NTRK2 gene fusions are uncommon in pilocytic astrocytoma

BACKGROUND

Pilocytic astrocytoma is the most frequent pediatric glioma. Despite its overall good prognosis, complete surgical resection is sometimes unfeasible, especially for patients with deep-seated tumors. For these patients, the identification of targetable genetic alterations such as NTRK fusions, raised as a new hope for therapy. The presence of gene fusions involving NTRK2 has been rarely reported in pilocytic astrocytoma. The aim of the present study was to investigate the frequency of NTRK2 alterations in a series of Brazilian pilocytic astrocytomas.

METHODS

Sixty-nine pilocytic astrocytomas, previously characterized for BRAF and FGFR1 alterations were evaluated. The analysis of NTRK2 alterations was performed using a dual color break apart fluorescence in situ hybridization (FISH) assay.

RESULTS

NTRK2 fusions were successfully evaluated by FISH in 62 of the 69 cases. Neither evidence of NTRK2 gene rearrangements nor NTRK2 copy number alterations were found.

CONCLUSIONS

NTRK2 alterations are uncommon genetic events in pilocytic astrocytomas, regardless of patients' clinicopathological and molecular features.

Neurosurgery for Optic Pathway Glioma: Optimizing Multidisciplinary Management

Optic pathway glioma (OPG) comprises 10% of pediatric brain tumors and 40% of all pediatric low-grade gliomas (pLGGs). While generally considered benign pathologically, many require interventions with chemotherapy, radiation, or targeted therapies. Management has historically foregone tissue diagnosis given the classical clinical/radiographic presentation of these tumors, inability to safely remove the lesions surgically, and efficacy and safety of available chemotherapy options. Furthermore, when considering such aspects as their delicate location, the role of surgery continues to be heavily debated. More recently, however, a greater understanding of the genetic drivers of OPGs has made operative tissue sampling a critical step in management planning, specifically for patients without Neurofibromatosis, Type I (NF1). Given the need for long-term, complex management of pediatric OPGs, it is crucial that a multidisciplinary approach is employed, and the rapidly expanding role of molecular characterization be incorporated into their management.

ADC Histogram Analysis of Pediatric Low-Grade Glioma Treated with Selumetinib: A Report from the Pediatric Brain Tumor Consortium

BACKGROUND AND PURPOSE

Selumetinib is a promising MAP (mitogen-activated protein) kinase (MEK) 1/2 inhibitor treatment for pediatric low-grade gliomas. We hypothesized that MR imaging-derived ADC histogram metrics would be associated with survival and response to treatment with selumetinib.

MATERIALS AND METHODS

Children with recurrent, refractory, or progressive pediatric low-grade gliomas who had World Health Organization grade I pilocytic astrocytoma with KIAA1549-BRAF fusion or the BRAF V600E mutation (stratum 1), neurofibromatosis type 1-associated pediatric low-grade gliomas (stratum 3), or sporadic non-neurofibromatosis type 1 optic pathway and hypothalamic glioma (OPHG) (stratum 4) were treated with selumetinib for up to 2 years. Quantitative ADC histogram metrics were analyzed for total and enhancing tumor volumes at baseline and during treatment.

RESULTS

Each stratum comprised 25 patients. Stratum 1 responders showed lower values of SD of baseline ADC_total as well as a larger decrease with time on treatment in ADC_total mean, mode, and median compared with nonresponders. Stratum 3 responders showed a greater longitudinal decrease in ADC_total. In stratum 4, higher baseline ADC_total skewness and kurtosis were associated with shorter progression-free survival. When all 3 strata were combined, responders showed a greater decrease with time in ADC_total mode and median. Compared with sporadic OPHG, neurofibromatosis type 1-associated OPHG had lower values of ADC_total mean, mode, and median as well as ADC_enhancement mean and median and higher values of ADC_total skewness and kurtosis at baseline. The longitudinal decrease in ADC_total median during treatment was significantly greater in sporadic OPHG compared with neurofibromatosis type 1-associated OPHG.

CONCLUSIONS

ADC histogram metrics are associated with progression-free survival and response to treatment with selumetinib in pediatric low-grade gliomas.

Pediatric and Adult Low-Grade Gliomas: Where Do the Differences Lie?

Two thirds of pediatric gliomas are classified as low-grade (LGG), while in adults only around 20% of gliomas are low-grade. However, these tumors do not only differ in their incidence but also in their location, behavior and, subsequently, treatment. Pediatric LGG constitute 65% of pilocytic astrocytomas, while in adults the most commonly found histology is diffuse low-grade glioma (WHO II), which mostly occurs in eloquent regions of the brain, while its pediatric counterpart is frequently found in the infratentorial compartment. The different tumor locations require different skillsets from neurosurgeons. In adult LGG, a common practice is awake surgery, which is rarely performed on children. On the other hand, pediatric neurosurgeons are more commonly confronted with infratentorial tumors causing hydrocephalus, which more often require endoscopic or shunt procedures to restore the cerebrospinal fluid flow. In adult and pediatric LGG surgery, gross total excision is the primary treatment strategy. Only tumor recurrences or progression warrant adjuvant therapy with either chemo- or radiotherapy. In pediatric LGG, MEK inhibitors have shown promising initial results in treating recurrent LGG and several ongoing trials are investigating their role and safety. Moreover, predisposition syndromes, such as neurofibromatosis or tuberous sclerosis complex, can increase the risk of developing LGG in children, while in adults, usually no tumor growth in these syndromes is observed. In this review, we discuss and compare the differences between pediatric and adult LGG, emphasizing that pediatric LGG should not be approached and managed in the same way as adult LCG.

Oxidative Stress Activated by Sorafenib Alters the Temozolomide Sensitivity of Human Glioma Cells Through Autophagy and JAK2/STAT3-AIF Axis

The development of temozolomide (TMZ) resistance in glioma leads to poor patient prognosis. Sorafenib, a novel diaryl urea compound and multikinase inhibitor, has the ability to effectively cross the blood-brain barrier. However, the effect of sorafenib on glioma cells and the molecular mechanism underlying the ability of sorafenib to enhance the antitumor effects of TMZ remain elusive. Here, we found that sorafenib could enhance the cytotoxic effects of TMZ in glioma cells in vitro and in vivo. Mechanistically, the combination of sorafenib and TMZ induced mitochondrial depolarization and apoptosis inducing factor (AIF) translocation from mitochondria to nuclei, and this process was dependent on STAT3 inhibition. Moreover, the combination of sorafenib and TMZ inhibited JAK2/STAT3 phosphorylation and STAT3 translocation to mitochondria. Inhibition of STAT3 activation promoted the autophagy-associated apoptosis induced by the combination of sorafenib and TMZ. Furthermore, the combined sorafenib and TMZ treatment induced oxidative stress while reactive oxygen species (ROS) clearance reversed the treatment-induced inhibition of JAK2/STAT3. The results indicate that sorafenib enhanced the temozolomide sensitivity of human glioma cells by inducing oxidative stress-mediated autophagy and JAK2/STAT3-AIF axis.

Association of HMGA2 Polymorphisms with Glioma Susceptibility in Chinese Children

Background

Glioma is a malignant central nervous system tumor in children, with poor outcomes and prognosis. HMGA2 is a proto-oncogene with increased expression in various malignancies.

Methods

We explored the association of HMGA2 polymorphisms with glioma susceptibility in Chinese children using a case-control study (191 cases, 248 controls). HMGA2 single nucleotide polymorphisms (rs6581658 A>G; rs8756 A>C; rs968697 T>C) were genotyped using PCR-based TaqMan.

Results

Increased glioma susceptibility was associated with rs6581658 A>G; AG (adjusted odds ratio (OR) = 1.71, 95% confidence interval (CI) = 1.13–2.58, P = 0.010) or GG (adjusted OR = 3.12, 95% CI = 1.26–7.74, P = 0.014) genotype carriers had significantly raised glioma risk compared with AA genotype carriers. The rs6581658 AG/GG (adjusted OR = 1.85, 95% CI = 1.25–2.73, P = 0.002) and AA/GG (adjusted OR = 2.58, 95% CI = 1.05–6.33, P = 0.038) genotypes were associated with an increased risk of glioma relative to the AA genotype. Subjects with 2–3 risk genotypes had a significantly elevated risk (adjusted OR = 1.93, 95% CI = 1.31–2.84, P = 0.001) relative to those with 0–1 risk genotype.

Conclusion

HMGA2 rs6581658 A>G is associated with glioma susceptibility in Chinese children.

Concise review of stereotactic irradiation for pediatric glial neoplasms: Current concepts and future directions

Brain tumors, which are among the most common solid tumors in childhood, remain a leading cause of cancer-related mortality in pediatric population. Gliomas, which may be broadly categorized as low grade glioma and high grade glioma, account for the majority of brain tumors in children. Expectant management, surgery, radiation therapy (RT), chemotherapy, targeted therapy or combinations of these modalities may be used for management of pediatric gliomas. Several patient, tumor and treatment-related characteristics including age, lesion size, grade, location, phenotypic and genotypic features, symptomatology, predicted outcomes and toxicity profile of available therapeutic options should be considered in decision making for optimal treatment. Management of pediatric gliomas poses a formidable challenge to the physicians due to concerns about treatment induced toxicity. Adverse effects of therapy may include neurological deficits, hemiparesis, dysphagia, ataxia, spasticity, endocrine sequelae, neurocognitive and communication impairment, deterioration in quality of life, adverse socioeconomic consequences, and secondary cancers. Nevertheless, improved understanding of molecular pathology and technological advancements may pave the way for progress in management of pediatric glial neoplasms. Multidisciplinary management with close collaboration of disciplines including pediatric oncology, surgery, and radiation oncology is warranted to achieve optimal therapeutic outcomes. In the context of RT, stereotactic irradiation is a viable treatment modality for several central nervous system disorders and brain tumors. Considering the importance of minimizing adverse effects of irradiation, radiosurgery has attracted great attention for clinical applications in both adults and children. Radiosurgical applications offer great potential for improving the toxicity profile of radiation delivery by focused and precise targeting of well-defined tumors under stereotactic immobilization and image guidance. Herein, we provide a concise review of stereotactic irradiation for pediatric glial neoplasms in light of the literature.

Prognostic implications of immune-related eight-gene signature in pediatric brain tumors

Genomic studies have provided insights into molecular subgroups and oncogenic drivers of pediatric brain tumors (PBT) that may lead to novel therapeutic strategies. Participants of the cohort Pediatric Brain Tumor Atlas: CBTTC (CBTTC cohort), were randomly divided into training and validation cohorts. In the training cohort, Kaplan-Meier analysis and univariate Cox regression model were applied to preliminary screening of prognostic genes. The LASSO Cox regression model was implemented to build a multi-gene signature, which was then validated in the validation and CBTTC cohorts through Kaplan-Meier, Cox, and receiver operating characteristic curve (ROC) analyses. Also, gene set enrichment analysis (GSEA) and immune infiltrating analyses were conducted to understand function annotation and the role of the signature in the tumor microenvironment. An eight-gene signature was built, which was examined by Kaplan-Meier analysis, revealing that a significant overall survival difference was seen, either in the training or validation cohorts. The eight-gene signature was further proven to be independent of other clinic-pathologic parameters via the Cox regression analyses. Moreover, ROC analysis demonstrated that this signature owned a better predictive power of PBT prognosis. Furthermore, GSEA and immune infiltrating analyses showed that the signature had close interactions with immune-related pathways and was closely related to CD8 T cells and monocytes in the tumor environment. Identifying the eight-gene signature (CBX7, JADE2, IGF2BP3, OR2W6P, PRAME, TICRR, KIF4A, and PIMREG) could accurately identify patients' prognosis and the signature had close interactions with the immunodominant tumor environment, which may provide insight into personalized prognosis prediction and new therapies for PBT patients.

Effect of radiation therapy on overall survival following subtotal resection of adult pilocytic astrocytoma

OBJECTIVE

Pilocytic astrocytoma (PCA) is a low-grade glioma that primarily presents in children, but can also present in adulthood. Ideal primary treatment for PCA is gross total resection. However, for patients who are only able to undergo subtotal resection, the optimal course of post-operative therapy remains unclear. We investigated the association of patient characteristics and radiation therapy (RT) with overall survival specifically for adult PCA patients who underwent subtotal tumor resection.

METHODS

Information on adult patients (age ≥18 years old) who underwent subtotal PCA resection between 2004 and 2016 was collected from the National Cancer Database (NCDB). A multivariate Cox proportional hazards model was utilized to determine factors associated with overall survival.

RESULTS

A total of 451 patients were identified. The mean age of our patient cohort was 36.8 years old, and the majority of patients (83.4%) did not receive RT following subtotal PCA resection. Overall median survival was >93.8 months. On multivariate analysis, patients who were older at diagnosis (hazard ratio [HR] = 1.04, 95% confidence interval [CI] = 1.02-1.06, p < 0.01), black (HR = 2.35, CI = 1.05-5.23, p = 0.037), had a Charlson/Deyo comorbidity score ≥ 1 (HR = 2.27, CI = 1.00-5.14, p = 0.049), or received RT during their initial treatment (HR = 3.77, CI = 1.77-8.03, p < 0.01) had a significantly higher risk of death following subtotal PCA resection.

CONCLUSION

Post-operative RT was associated with a significantly higher risk of death among adults who underwent subtotal PCA resection. Our findings provide support for further inquiry into the efficacy of RT within this patient population.