Perillyl alcohol for pediatric TP53- and RAS-mutated SHH-medulloblastoma: an in vitro and in vivo translational pre-clinical study

PURPOSE

Inhalation of perillyl alcohol (POH) recently emerged as an investigational promising antiglioma strategy. However, little attention has been paid to its therapeutic potential for other brain tumors, especially in the pediatric setting.

METHODS

The effects of POH were explored in medulloblastoma cell models belonging to the SHH variant with activation of RAS (ONS-76) or with TP53 mutations (DAOY and UW402), by means of proliferation and invasion assays. Interactions with methotrexate, thiotepa, or ionizing radiation were also assessed. Mice bearing subcutaneous tumors were treated with intraperitoneal injections. Alternatively, animals with intracranial tumors were exposed to intranasal POH alone or combined with radiation. Tumor growth was measured by bioluminescence. Analyses of cytotoxicity to the nasal cavity were also performed, and the presence of POH in the brain, lungs, and plasma was surveyed through chromatography/mass spectrometry.

RESULTS

POH decreased cell proliferation and colony formation, with conspicuous death, though the invasive capacity was only affected in the NRAS-mutated cell line. Median-drug effect analysis displayed synergistic combinations with methotrexate. Otherwise, POH showed to be a reasonable radiosensitizer. In vivo, intraperitoneal injection significantly decreased tumor volume. However, its inhalation did not affect orthotopic tumors, neither alone or followed by cranial irradiation. Nasal cavity epithelium showed unimportant alterations, though, no traces of POH or its metabolites were detected in tissue samples.

CONCLUSION

POH presents robust in vitro antimedulloblastoma effects and sensitizes cell lines to other conventional therapeutics, reducing tumor volume when administered intraperitoneally. Nevertheless, further improvement of delivery devices and/or drug formulations are needed to better characterize its effectiveness through inhalation.

Rapidly progressive medulloblastoma initially mimicking idiopathic intracranial hypertension and Chiari I malformation: A case report

Introduction

Medulloblastoma (MDB) often causes signs and symptoms of elevated intracranial pressure (ICP) with imaging findings of mass lesion. Here, we report a case of MDB who initially presented with clinical features imitating idiopathic intracranial hypertension (IIH) and Chiari I malformation (CIM).

Case presentation

A 19-year-old man had clinical symptoms of elevated ICP without mass lesion on imaging. He was initially diagnosed with IIH and CIM, which underwent shunt surgery and posterior fossa decompression. Later on, he had recurrent symptoms, and the new imaging revealed the development of MDB in the right cerebellar hemisphere. After tumor resection, the patient rapidly deteriorated with spinal metastases.

Discussion and conclusion

Management of the coexistence between IIH and CIM in patients with rising ICP is complicated. MDB is one of the aggressive malignant brain tumors showing a wide range of imaging features, including non-enhancing mass. Therefore, recognizing the possibility of brain tumors mimicking IIH or CIM is crucial.

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The coexistence of idiopathic intracranial hypertension (IIH) and Chiari I malformation (CIM) is complicated.

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Medulloblastoma (MDB) can present with a wide range of imaging features, including non-enhancing mass.

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Exclusion of the secondary cause of rising intracranial pressure is necessary before making the diagnosis of IIH or CIM

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Early diagnosis, including subtype of MDB, and urgent treatment are crucial for better outcome.

Multi-omics analysis of intertumoral heterogeneity within medulloblastoma uncharted-pathway subtypes

Medulloblastoma is a common pediatric malignant brain tumor. There were four consensus molecular subgroups (WNT, SHH, Group3 and Group4). Group 3 and Group 4 tumors exhibited a great degree of transcriptional overlap, and were neither derived from exact pathway aberration. We investigated transcriptional and chromatin accessibility of medulloblastoma by multi-omics single-cell analysis. Our work identified inter- and intra-tumoral heterogeneity within the Group 3, Group 4 and Group 3/4 intermediate subgroups. Unsupervised cluster of each tumor identified 9 cell clusters with transcriptional profiles and 6 cell clusters with chromatin accessibility profiles. OTX2 had the highest activity and expression level across the clusters in a special cluster based on open chromatin single-cell profilings. We identified multiple genes as a significant targeted gene within the OTX2 target genes, which made sense in prognosis. We analyzed the copy-number-variations which presented with expected subgroup distribution from transcriptional and chromatin accessibility profiles. Collectively, these data provide novel insights into Group 3 and Group 4 medulloblastoma and provide a potential therapeutic target.

Stem-Like Cell Populations, p53-Pathway Activation and Mechanisms of Recurrence in Sonic Hedgehog Medulloblastoma

While most Sonic Hedgehog-associated medulloblastomas (SHH-MBs) respond to therapeutic intervention, radiation therapy often causes deleterious long-term neurocognitive defects, especially in infants and young children. To limit neurological comorbidities, the development of a reduction-of-therapy treatment or de-escalation approach was investigated. Although retrospective analysis of MBs indicated low-dose therapy was potentially effective, clinical de-escalation trials showed poor outcomes in infant SHH-MBs and was prematurely terminated. Recent studies suggest the existence of cancer-stem-cell (CSC)-like cell populations that are more resistant to therapies and drive tumor recurrence. This review will discuss the mechanism of these CSC-like cells in SHH-MBs in resisting to p53-pathway activation, which may contribute to the disappointing outcomes of the recent de-escalation trials.

GLI3 Is Associated With Neuronal Differentiation in SHH-Activated and WNT-Activated Medulloblastoma

Glioma-associated oncogene homolog 3 (GLI3), whose main function is to inhibit GLI1, has been associated with neuronal differentiation in medulloblastoma. However, it is not clear what molecular subtype(s) show increased GLI3 expression. GLI3 levels were assessed by immunohistochemistry in 2 independent cohorts, including a total of 88 cases, and found to be high in both WNT- and SHH-activated medulloblastoma. Analysis of bulk mRNA expression data and single cell RNA sequencing studies confirmed that GLI1 and GLI3 are highly expressed in SHH-activated medulloblastoma, whereas GLI3 but not GLI1 is highly expressed in WNT-activated medulloblastoma. Immunohistochemical analysis has shown that GLI3 is expressed inside the neuronal differentiated nodules of SHH-activated medulloblastoma, whereas GLI1/2 are expressed in desmoplastic areas. In contrast, GLI3 is diffusely expressed in WNT-activated medulloblastoma, whereas GLI1 is suppressed. Our data suggest that GLI3 may be a master regulator of neuronal differentiation and morphology in these subgroups.

Systems pharmacogenomics identifies novel targets and clinically actionable therapeutics for medulloblastoma

BACKGROUND

Medulloblastoma (MB) is the most common malignant paediatric brain tumour and a leading cause of cancer-related mortality and morbidity. Existing treatment protocols are aggressive in nature resulting in significant neurological, intellectual and physical disabilities for the children undergoing treatment. Thus, there is an urgent need for improved, targeted therapies that minimize these harmful side effects.

METHODS

We identified candidate drugs for MB using a network-based systems-pharmacogenomics approach: based on results from a functional genomics screen, we identified a network of interactions implicated in human MB growth regulation. We then integrated drugs and their known mechanisms of action, along with gene expression data from a large collection of medulloblastoma patients to identify drugs with potential to treat MB.

RESULTS

Our analyses identified drugs targeting CDK4, CDK6 and AURKA as strong candidates for MB; all of these genes are well validated as drug targets in other tumour types. We also identified non-WNT MB as a novel indication for drugs targeting TUBB, CAD, SNRPA, SLC1A5, PTPRS, P4HB and CHEK2. Based upon these analyses, we subsequently demonstrated that one of these drugs, the new microtubule stabilizing agent, ixabepilone, blocked tumour growth in vivo in mice bearing patient-derived xenograft tumours of the Sonic Hedgehog and Group 3 subtype, providing the first demonstration of its efficacy in MB.

CONCLUSIONS

Our findings confirm that this data-driven systems pharmacogenomics strategy is a powerful approach for the discovery and validation of novel therapeutic candidates relevant to MB treatment, and along with data validating ixabepilone in PDX models of the two most aggressive subtypes of medulloblastoma, we present the network analysis framework as a resource for the field.

Pediatric Neuro-Oncology

Central nervous system (CNS) tumors are the most common solid tumor in pediatrics and represent the largest cause of childhood cancer-related mortality. With advances in molecular characterization of tumors, considerable developments have occurred impacting diagnosis and management, and refined prognostication. Advances in management have led to better survival, but mortality remains high and significant morbidity persists. Novel therapeutic approaches targeting the biology of these tumors are being investigated to improve overall survival and decrease treatment-related morbidity. Further molecular understanding of pediatric CNS tumors will lead to continued refinement of tumor classification, management, and prognostication.

Overview and recent advances in the targeting of medulloblastoma cancer stem cells

Introduction: Medulloblastoma, an embryonal small round blue cell tumor primarily arising in the posterior fossa, is the most common malignancy of the central nervous system in children and requires intensive multi-modality therapy for cure. Overall 5-year survival is approximately 75% in children with primary disease, but outcomes for relapsed disease are very poor. Recent advances have identified molecular subgroups with excellent prognosis, with 5-year overall survival rates >90%, and subgroups with very poor prognosis with overall survival rates <50%. Molecular subtyping has allowed for more sophisticated risk stratification of patients, but new treatments for the highest risk patients have not yet improved outcomes. Targeting cancer stem cells may improve outcomes, and several candidate targets and novel drugs are under investigation.Areas covered: We discuss medulloblastoma epidemiology, biology, treatment modalities, risk stratification, and molecular subgroup analysis, links between subgroup and developmental biology, cancer stem cell biology in medulloblastoma including previously described cancer stem cell markers and proposed targeted treatments in the current literature.Expert opinion: The understanding of cancer stem cells in medulloblastoma will advance therapies targeting the most treatment-resistant cells within the tumor and therefore reduce the incidence of treatment refractory and relapsed disease.

Simultaneous Brg1 Knockout and MYCN Overexpression in Cerebellar Granule Neuron Precursors Is Insufficient to Drive Tumor Formation but Temporarily Enhances their Proliferation and Delays their Migration

Medulloblastoma (MB) is the most common malignant brain tumor in childhood. According to the World Health Organization (WHO) classification of central nervous system (CNS) tumors, this embryonal tumor is divided into a wingless (WNT)-activated, Sonic hedgehog (SHH)-activated, and non-WNT/non-SHH entity. The latter is poorly defined but frequently carries mutations in Brahma-related gene 1 (BRG1) or amplifications of MYCN. Here, we investigated whether a combination of a Brg1 knockout and an overexpression of MYCN in cerebellar granule neuron precursors or multipotent neural stem cells is sufficient to drive brain tumor formation in mice. To this end, we generated Math1-creERT2::Brg1fl/fl::lslMYCN and hGFAP-cre::Brg1fl/fl::lslMYCN mice, respectively. We did not observe brain tumor formation in any of these models. hGFAP-cre::Brg1fl/fl::lslMYCN mice revealed severe CNS abnormalities with short survival, similar to the situation with a sole loss of Brg1, as we previously described. Investigation of Math1-creERT2::Brg1fl/fl::lslMYCN mice with a tamoxifen induction at postnatal day 3 revealed a regular survival but significant increase in cerebellar granule neuron precursor proliferation, followed by a delayed inward migration of these cells. This is in stark contrast to the hypoplastic cerebellum that we previously observed after embryonic deletion of Brg1 in Math1 positive cerebellar granule neurons. Our results indicate a time-specific function of Brg1 in cerebellar granule neuron precursors. Yet, the exact temporal and spatial origin of non-WNT/non-SHH MB remains unclear.

Surgical outcome of children with medulloblastoma: a retrospective study of a 405-patient series from Children's Cancer Hospital Egypt (CCHE-57357)

PURPOSE

To analyze the impact of increasing the extent of resection (EOR) on the survival rates and on the surgical outcome of children with medulloblastoma.

METHODS

A series of consecutive 405 children operated for medulloblastoma between July 2007 and April 2018 was identified. The details of pre-operative data, surgical interventions, post-operative complications, and survival rates were analyzed.

RESULTS

The Kaplan-Meier (KM) analysis showed no advantage of gross total resection (GTR) over near and subtotal resection regarding over all (OS) (p=0.557) and progression free survival (PFS) (p=0.146). In the same time, increasing the EOR was not associated with higher morbidity. Tumor dissemination at onset correlated to worse OS (KM: p=0.003, OR 1.999, 95% CI: 1.242-3.127; p = 0.004) and PFS (KM: p<0.001, Cox: OR 2.171, 95% CI: 1.406-3.353; p<0.001). OS was significantly affected in patients < 3 years old (KM: p=0.011, OR 2.036, 95% CI: 1.229-3.374; p = 0.006), while PFS was worse among patients who had pre-op seizures (KM: p=0.036, Cox: OR 2.852, 95% CI: 1.046-7.773; p=0.041) or post-op pseudomeningocele (KM: p=0.021, Cox: OR 2.311, 95% CI: 1.123-4.754; p=0.023).

CONCLUSIONS

Although surgical excision of medulloblastoma is the standard of care, there was no significant benefit for GTR over near or subtotal resection on the OS or PFS rates that are mainly influenced by the patient's age and tumor dissemination. However, GTR should be targeted, as it is not associated with increased incidence of mutism or other surgery-related complications.

Intramedullary metastasis in medulloblastoma: a case report and literature review

BACKGROUND

Cerebellar medulloblastomas are the most common malignant tumors of the posterior fossa in childhood that frequently metastasize. Leptomeningeal dissemination and distant metastasis have been associated with medulloblastomas; however, intramedullary metastases are rare with very few case reports in the literature available.

METHODS

We present a case of a 3-year-old girl with a medulloblastoma who underwent surgical resection of spinal intramedullary metastases. Histopathology revealed the tumor to be an anaplastic medulloblastoma similar to the intracranial lesions. The patient subsequently underwent postoperative chemotherapy followed by radiotherapy.

RESULTS

Following the surgery and subsequent follow-up, the patient showed a good recovery without any new neurological dysfunction.

CONCLUSIONS

Intramedullary metastasis of medulloblastoma remains a rare disease. Surgical resection could play a possible role in the management in addition to radiation and chemotherapy.

Expertise is crucial to prolong survival in average risk medulloblastoma: long-term results of a retrospective study

PURPOSE

Medulloblastoma is a rare tumor in adults and the use of adjuvant chemotherapy in average risk patients is debated.

METHODS

Patients included in our study were ⩾16 years of age, had histologically confirmed medulloblastoma, and underwent adjuvant radiotherapy with or without chemotherapy. Average risk was defined according to the Chang classification.

RESULTS

We included 48 average-risk patients. Median follow-up was 151.5 months (95% confidence interval, 124.5-178.5). Both progression-free survival (PFS) and overall survival (OS) were significantly influenced by adjuvant chemotherapy (PFS: hazard ratio [HR], 0.334, p = 0.05; OS: HR, 0.187, p = 0.017) and by receiving the treatment in a referral center (PFS: HR, 0.250, p = 0.008; OS: HR, 0.295, p = 0.038).

CONCLUSIONS

Treating patients with average-risk medulloblastoma in a referral center improves both PFS and OS, does adding adjuvant chemotherapy.

Application of Genome-Wide DNA Methylation Analysis to Differentiate a Case of Radiation-Induced Glioblastoma From Late-Relapsed Medulloblastoma

Recurrent medulloblastoma can be difficult to diagnose with conventional diagnostic methods because other lesions mimic tumor relapse, particularly at later stages. We report 2 cases of medulloblastoma, both of which seemed to develop late recurrences. Case 1 was a 6-year-old girl who had a medulloblastoma with focal desmoplasia. She was in complete remission for 9 years after treatment but developed an intradural lesion in her thoracic spine, which was pathologically confirmed as tumor recurrence by biopsy. Case 2 was a 10-year-old girl who had a nonmetastatic medulloblastoma. She developed a left cerebellar mass 5 years after the initial diagnosis; the pathological diagnosis was tumor relapse. We performed t-distributed stochastic neighbor embedding of the methylation data from these cases and reference data. In contrast to the consistency of methylation profiling and copy number abnormalities between primary and recurrent tumors of Case 1, the analysis of the recurrent tumor in Case 2 was distinct from medulloblastomas and clustered with "IDH-wild type glioblastomas," suggesting that the recurrent tumor was a radiation-induced glioblastoma. This report highlights the clinical utility of molecular genetic/epigenetic analysis combined with a standard diagnostic approach to confirm the diagnosis of brain tumor recurrence.

Multiple Reaction Monitoring-Based Targeted Assays for the Validation of Protein Biomarkers in Brain Tumors

The emergence of omics technologies over the last decade has helped in advancement of research and our understanding of complex diseases like brain cancers. However, barring genomics, no other omics technology has been able to find utility in clinical settings. The recent advancements in mass spectrometry instrumentation have resulted in proteomics technologies becoming more sensitive and reliable. Targeted proteomics, a relatively new branch of mass spectrometry-based proteomics has shown immense potential in addressing the shortcomings of the standard molecular biology-based techniques like Western blotting and Immunohistochemistry. In this study we demonstrate the utility of Multiple reaction monitoring (MRM), a targeted proteomics approach, in quantifying peptides from proteins like Apolipoprotein A1 (APOA1), Apolipoprotein E (APOE), Prostaglandin H2 D-Isomerase (PTGDS), Vitronectin (VTN) and Complement C3 (C3) in cerebrospinal fluid (CSF) collected from Glioma and Meningioma patients. Additionally, we also report transitions for peptides from proteins - Vimentin (VIM), Cystatin-C (CST3) and Clusterin (CLU) in surgically resected Meningioma tissues; Annexin A1 (ANXA1), Superoxide dismutase (SOD2) and VIM in surgically resected Glioma tissues; and Microtubule associated protein-2 (MAP-2), Splicing factor 3B subunit 2 (SF3B2) and VIM in surgically resected Medulloblastoma tissues. To our knowledge, this is the first study reporting the use of MRM to validate proteins from three types of brain malignancies and two different bio-specimens. Future studies involving a large cohort of samples aimed at accurately detecting and quantifying peptides of proteins with roles in brain malignancies could potentially result in a panel of proteins showing ability to classify and grade tumors. Successful application of these techniques could ultimately offer alternative strategies with increased accuracy, sensitivity and lower turnaround time making them translatable to the clinics.

Medulloblastoma recurrence and metastatic spread are independent of colony-stimulating factor 1 receptor signaling and macrophage survival

PURPOSE

Tumor infiltration by immunosuppressive myeloid cells or tumor-associated macrophages (TAMs) contributes to tumor progression and metastasis. In contrast to their adult counterparts, higher TAM signatures do not correlate with aggressive tumor behavior in pediatric brain tumors. While prominent TAM infiltrates exist before and after radiation, the degree to which irradiated macrophages and microglia support progression or leptomeningeal metastasis remains unclear. Patients with medulloblastoma often present with distant metastases and tumor recurrence is largely incurable, making them prime candidates for the study of novel approaches to prevent neuroaxis dissemination and recurrence.

METHODS

Macrophage depletion was achieved using CSF-1 receptor inhibitors (CSF-1Ri), BLZ945 and AFS98, with or without whole brain radiation in a variety of medulloblastoma models, including patient-derived xenografts bearing Group 3 medulloblastoma and a transgenic Sonic Hedgehog (Ptch1^+/-, Trp53^-/-) medulloblastoma model.

RESULTS

Effective reduction of microglia, TAM, and spinal cord macrophage with CSF-1Ri resulted in negligible effects on the rate of local and spinal recurrences or survival following radiation. Results were comparable between medulloblastoma subgroups. While notably few tumor-infiltrating lymphocytes (TILs) were detected, average numbers of CD3+ TILs and FoxP3+ Tregs did not differ between groups following treatment and tumor aggressiveness by Ki67 proliferation index was unaltered.

CONCLUSION

In the absence of other microenvironmental influences, medulloblastoma-educated macrophages do not operate as tumor-supportive cells or promote leptomeningeal recurrence in these models. Our data add to a growing body of literature describing a distinct immunophenotype amid the medulloblastoma microenvironment and highlight the importance of appropriate pediatric modeling prior to clinical translation.

Identification of pseudolaric acid B as a novel Hedgehog pathway inhibitor in medulloblastoma

Aberrant activation of the Hedgehog (Hh) pathway is implicated in the pathogenesis and development of multiple cancers, especially Hh-driven medulloblastoma (MB). Smoothened (SMO) is a promising therapeutic target of the Hh pathway in clinical cancer treatment. However, SMO mutations frequently occur, which leads to drug resistance and tumor relapse. Novel inhibitors that target both the wild-type and mutant SMO are in high demand. In this study, we identified a novel Hh pathway inhibitor, pseudolaric acid B (PAB), which significantly inhibited the expression of Gli1 and its transcriptional target genes, such as cyclin D1 and N-myc, thus inhibiting the proliferation of DAOY and Ptch1^+/- primary MB cells. Mechanistically, PAB can potentially bind to the extracellular entrance of the heptahelical transmembrane domain (TMD) of SMO, based on molecular docking and the BODIPY-cyclopamine binding assay. Further, PAB also efficiently blocked ciliogenesis, demonstrating the inhibitory effects of PAB on the Hh pathway at multiple levels. Thus, PAB may overcome drug-resistance induced by SMO mutations, which frequently occurs in clinical setting. PAB markedly suppressed tumor growth in the subcutaneous allografts of Ptch1^+/- MB cells. Together, our results identified PAB as a potent Hh pathway inhibitor to treat Hh-dependent MB, especially cases resistant to SMO antagonists.

SEOM clinical guideline for management of adult medulloblastoma (2020)

Recent advances in molecular profiling, have reclassified medulloblastoma, an undifferentiated tumor of the posterior fossa, in at least four diseases, each one with differences in prognosis, epidemiology and sensibility to different treatments. The recommended management of a lesion with radiological characteristics suggestive of MB includes maximum safe resection followed by a post-surgical MR < 48 h, LCR cytology and MR of the neuroaxis. Prognostic factors, such as presence of a residual tumor volume > 1.5 cm2, presence of micro- or macroscopic dissemination, and age > 3 years as well as pathological (presence of anaplastic or large cell features) and molecular findings (group, 4, 3 or p53 SHH mutated subgroup) determine the risk of relapse and should guide adjuvant management. Although there is evidence that both high-risk patients and to a lesser degree, standard-risk patients benefit from adjuvant craneoespinal radiation followed by consolidation chemotherapy, tolerability is a concern in adult patients, leading invariably to dose reductions. Treatment after relapse is to be considered palliative and inclusion on clinical trials, focusing on the molecular alterations that define each subgroup, should be encouraged. Selected patients can benefit from surgical rescue or targeted radiation or high-dose chemotherapy followed by autologous self-transplant. Even in patients that are cured by chemorradiation presence of significant sequelae is common and patients must undergo lifelong follow-up.

Veliparib Is an Effective Radiosensitizing Agent in a Preclinical Model of Medulloblastoma

Medulloblastoma is the most common malignant childhood brain tumor, and 5-year overall survival rates are as low as 40% depending on molecular subtype, with new therapies critically important. As radiotherapy and chemotherapy act through the induction of DNA damage, the sensitization of cancer cells through the inhibition of DNA damage repair pathways is a potential therapeutic strategy. The poly-(ADP-ribose) polymerase (PARP) inhibitor veliparib was assessed for its ability to augment the cellular response to radiation-induced DNA damage in human medulloblastoma cells. DNA repair following irradiation was assessed using the alkaline comet assay, with veliparib inhibiting the rate of DNA repair. Veliparib treatment also increased the number of γH2AX foci in cells treated with radiation, and analysis of downstream pathways indicated persistent activation of the DNA damage response pathway. Clonogenicity assays demonstrated that veliparib effectively inhibited the colony-forming capacity of medulloblastoma cells, both as a single agent and in combination with irradiation. These data were then validated in vivo using an orthotopic implant model of medulloblastoma. Mice harboring intracranial D425 medulloblastoma xenografts were treated with vehicle, veliparib, 18 Gy multifractionated craniospinal irradiation (CSI), or veliparib combined with 18 Gy CSI. Animals treated with combination therapy exhibited reduced tumor growth rates concomitant with increased intra-tumoral apoptosis observed by immunohistochemistry. Kaplan–Meier analyses revealed a statistically significant increase in survival with combination therapy compared to CSI alone. In summary, PARP inhibition enhanced radiation-induced cytotoxicity of medulloblastoma cells; thus, veliparib or other brain-penetrant PARP inhibitors are potential radiosensitizing agents for the treatment of medulloblastoma.

Ten-eleven translocation protein 1 modulates medulloblastoma progression

BACKGROUND

Medulloblastoma (MB) is the most common malignant pediatric brain tumor that originates in the cerebellum and brainstem. Frequent somatic mutations and deregulated expression of epigenetic regulators in MB highlight the substantial role of epigenetic alterations. 5-hydroxymethylcytosine (5hmC) is a highly abundant cytosine modification in the developing cerebellum and is regulated by ten-eleven translocation (TET) enzymes.

RESULTS

We investigate the alterations of 5hmC and TET enzymes in MB and their significance to cerebellar cancer formation. We show total abundance of 5hmC is reduced in MB, but identify significant enrichment of MB-specific 5hmC marks at regulatory regions of genes implicated in stem-like properties and Nanog-binding motifs. While TET1 and TET2 levels are high in MBs, only knockout of Tet1 in the smoothened (SmoA1) mouse model attenuates uncontrolled proliferation, leading to a favorable prognosis. The pharmacological Tet1 inhibition reduces cell viability and platelet-derived growth factor signaling pathway-associated genes.

CONCLUSIONS

These results together suggest a potential key role of 5hmC and indicate an oncogenic nature for TET1 in MB tumorigenesis, suggesting it as a potential therapeutic target for MBs.

Clinical-MRI radiomics enables the prediction of preoperative cerebral spinal fluid dissemination in children with medulloblastoma

BACKGROUND

Medulloblastoma (MB) is the most common pediatric embryonal tumor. Accurate identification of cerebral spinal fluid (CSF) dissemination is important in prognosis prediction. Both MRI of the central nervous system (CNS) and CSF cytology will appear false positive and negative. Our objective was to investigate the added value of preoperative-enhanced T1-weighted image-based radiomic features to clinical characteristics in predicting preoperative CSF dissemination for children with MB.

MATERIALS AND METHODS

This retrospective study included 84 children with histopathologically confirmed MB between November 2006 and November 2018 (training cohort, n=60; internal validation cohort, n=24). A set of cases between December 2018 and February 2020 were used for external validation (n=40). The children with normal head and spine magnetic resonance images (MRI) and no subsequent dissemination in 1 year were diagnosed as non-CSF dissemination. The CSF dissemination was manifested as intracranial or intraspinal nodular-enhanced lesions. Clinical features were collected, and conventional MRI features of preoperative head MRI examinations were evaluated. A total of 385 radiomic features were extracted from preoperative-enhanced T1-weighted images. Minimum redundancy, maximum correlation, and least absolute shrinkage and selection operator were performed to select the features with the best performance in predicting preoperative CSF dissemination. A combined clinical-MRI radiomic prediction model was developed using multivariable logistic regression. Receiver operating curve analysis (ROC) was used to validate the predictive performance. Nomogram and decision curve analysis (DCA) were developed to evaluate the clinical utility of the combined model.

RESULTS

One clinical and nine radiomic features were selected for predicting preoperative CSF dissemination. The combined model incorporating clinical and radiomic features had the best predictive performance in the training cohort with an AUC of 0.89. This was validated in the internal and external cohorts with AUCs of 0.87 and 0.73. The clinical utility of the model was confirmed by a clinical-MRI radiomic nomogram and DCA.

CONCLUSIONS

The combined model incorporating clinical, conventional MRI, and radiomic features could be applied to predict preoperative CSF dissemination for children with MB as a noninvasive biomarker, which could aid in risk evaluation.

Congenital medulloblastoma presented in the neonatal period

Congenital medulloblastoma is a rare brain tumor that appears in less than 1% of pediatric patients. Congenital medulloblastoma has a poor prognosis and should be suspected in patients with clinical manifestations of hyporeactivity, slow suction reflexes, and the presence of hydrocephalus. Herein we present the case of a 12-day-old female newborn who developed non-communicative hydrocephalus, hyporeactivity, and hyporeflexia. Magnetic resonance imaging of her brain showed a heterogeneous and cystic mass on the posterior cranial fossa. A suboccipital craniotomy was performed. The histopathologic analysis reported a congenital medulloblastoma. She remained in hospital until her death at 112 days old. This is one of the first case reports with clinical-radiological and pathological documentation. Awareness of this diagnosis can allow prenatal intervention, rendering a better prognosis. This case report exemplifies the importance of good prenatal follow-up.

as novel Smoothened inhibitors with anti-proliferation effects on DAOY medulloblastoma cells

Constitutive activation of Hedgehog (Hh) pathway is intimately related with the occurrence and development of several malignancies, such as medulloblastoma (MB) and other tumors. Therefore, small molecular inhibitors of Hh pathway are urgently needed. In this study, three new steroidal alkaloids, ⊿⁵ (20R, 24R) 23-oxo-24-methylsolacongetidine, ⊿⁵ (20S, 24R) 23-oxo-24-methylsolacongetidine and veralinine 3-O-α-l-rhamnopyranosyl-(1 → 2)-β-D-glucopyranoside, together with six known alkaloids, 20-epi-verazine, verazine, protoverine 15-(l)-2'-methylbutyrate, jervine, veramarine and β1-chaconine, were isolated and determined from Veratrum grandiflorum Loes. The dual-luciferase bioassay indicated that all compounds exhibited significant inhibitions of Hh pathway with IC₅₀ values of 0.72-14.31 μM against Shh-LIGHT 2 cells. To determine whether these Hh pathway inhibitors act with the Smoothened (Smo) protein, which is an important oncoprotein and target for this pathway, BODIPY-cyclopamine (BC) competitive binding assay was preferentially performed. Compared with BC alone, all compounds obviously reduced the fluorescence intensities of BC binding with Smo in Smo-overexpression HEK293T cells through fluorescence microscope and flow cytometer. By directly interacting with Smo, it revealed that they were actually novel natural Smo inhibitors. Then, their anti-tumor effects were investigated against the human MB cell line DAOY, which is a typical pediatric brain tumor cells line with highly expressed Hh pathway. Interestingly, most of compounds had slight proliferation inhibitions on DAOY cells after treatment for 24 h same as vismodegib, while β1-chaconine showed the strongest inhibitory effect on the growth of DAOY with IC₅₀ value of 5.35 μM. In conclusion, our studies valuably provide several novel natural Smo inhibitors for potential targeting treatment of Hh-dependent tumors.

Medulloblastoma in Adults: Cytogenetic Phenotypes Identify Prognostic Subgroups

Adult medulloblastomas (MB) are rare. We investigated the genetic landscape and prognostic impact of genetic aberrations in a cohort of 117 adult medulloblastomas. Histological features and pathway activation were evaluated at the protein level; 14.5% showed wingless-type activation, 63.3% SHH activation, and 22.2% were classified as non-WNT/non-SHH-MB. Genome-wide copy number analysis was performed by molecular inversion probe array technology. MB-related genes were sequenced in WNT- and SHH-activated MBs. 79.7% of SHH-MBs showed desmoplastic/nodular histology; all other MBs had classic histology. WNT-MBs carried oncogenic CTNNB1 mutations in 88.2% and had monosomy 6 in 52.9%. In SHH-MBs, TERT promoter mutations occurred in 97%, mutations in PTCH1 in 38.2%, SMO in 15.5%, SUFU in 7.4%, and TP53-mutations in 4.1%. In all, 84.6% of non-WNT/non-SHH-MBs had an isochromosome 17q. A whole chromosomal aberration (WCA) signature was present in 45.1% of SHH-TP53-wild type (wt)-MBs and 65.4% of non-WNT/non-SHH-MBs. In 98 cases with survival data, WNT-MBs had a 5-year overall survival (OS) of 68.6%. SHH-MBs TP53wt type and non-WNT/non-SHH-MBs showed 5-year OS of 80.4% and 70.8%, respectively. TP53-mutant SHH-MBs represented a prognostically unfavorable entity; all patients died within 5 years. Patients with a WCA signature showed significantly increased OS (p = 0.011 for SHH-TP53wt-MBs and p = 0.048 for non-WNT/non-SHH-MBs).

New Approaches in Targeted Therapy for Medulloblastoma in Children

Medulloblastoma (MB) is the most frequent malignant brain tumor in children. Treatment of MB is based on histopathological and molecular stratification, and includes surgical intervention, often with craniospinal irradiation and adjuvant chemotherapy. Unfortunately, however, this treatment leads to a high morbidity rate, and it does not cure all patients either, with around 30% succumbing to their disease. With improved cancer genomics and better molecular characterization, MB has been classified into four major subgroups, wingless-activated, sonic hedgehog-activated, Group 3, and Group 4, with each group consisting of additional subtypes. Recently disclosed genetic drivers of MB may in the future help improve treatment, and in this way reduce therapy-related toxicity. In this review, we describe the heterogeneity of the MB subgroups, and potential new options for targeted therapy.

Posterior fossa extra-axial variations of medulloblastoma: a pictorial review as a primer for radiologists

Manifestations of an atypical variant of medulloblastoma of the posterior fossa in extra-axial locations have been reported, and key questions concerning its interpretation have been raised previously. This review illustrated the clinico-radiological and histopathological features of the posterior fossa extra-axial medulloblastoma and described possible management strategies. We thoroughly reviewed all atypical anatomical locations of medulloblastoma reported within the posterior fossa and extra-axial spaces. The main characteristics of diagnostic imaging and histopathological results, primarily the distinctive radiopathological characteristics, were summarized to distinguish between intra- and extra-axial medulloblastoma, or pathologies mimicking this tumor. Most cases of posterior fossa extra-axial medulloblastoma have been reported in the cerebellopontine angle, followed by the tentorial and lateral cerebellar locations. The dural tail sign, which is commonly observed in meningioma, is rarely seen in intra- or extra-axial medulloblastoma and might be associated with other benign or malignant lesions. In addition to magnetic resonance imaging, the proposed new imaging techniques, including advances in modern neuroimaging modalities, were discussed, as potentially efficient modalities for characterizing extra-axial medulloblastoma. Radionuclide imaging and magnetic resonance perfusion imaging are practical alternatives to limit the number of differential diagnoses. We believe that medulloblastoma cases are likely under-reported because of publication bias and frequent tumors in unusual locations. Addressing these issues would help establish a more accurate understanding of this entity.

Radiation-induced intracranial aneurysm presenting with acute hemorrhage in a child treated for medulloblastoma

Radiation-associated aneurysms are rare, difficult to treat, and associated with high morbidity and mortality when ruptured, compared with aneurysms unrelated to radiation treatment. We present a 16-year-old patient with a radiation-induced intracranial aneurysm arising from the left posterior inferior cerebellar artery (PICA), 10 years following radiotherapy for medulloblastoma. The patient successfully underwent endovascular coil embolization of the parent artery across the neck of the aneurysm. CT angiography and MRI in the days following the procedure demonstrated maintained flow in the anterior and lateral medullary PICA segments with no brainstem infarct.

Radiation-induced spinal cord glioblastoma subsequent to treatment of medulloblastoma: case report

Medulloblastomas are one of the most common malignant pediatric brain tumors. Therapy has evolved into multimodality treatments consisting of surgery, radiation, and adjuvant chemotherapy. While craniospinal radiation remains standard for patients older than 3 years of age, it is not free of side effects and long-term complications. The development of malignant gliomas following therapy is a well-documented phenomenon. However, the majority of these radiation-induced glioblastomas (RIG) are intracranial, and intraspinal lesions are rare. The patient is a 22-year-old female with a history of a posterior fossa medulloblastoma diagnosed 8 years prior for which she underwent surgical resection followed by adjuvant chemotherapy and craniospinal radiation. Surveillance imaging showed no evidence of recurrence or new lesions for the following 5 years. She presented with nausea and vomiting and imaging revealing a new intramedullary cervical spinal cord lesion. She then developed acute quadriplegia several days after presentation. She underwent a cervical laminectomy and resection of this lesion, which was initially diagnosed as recurrent medulloblastoma before genomic analysis ultimately revealed it to be a RIG. Spinal RIGs that occur secondary to treatment for an intracranial neoplasm are exceedingly rare. The majority of spinal cord RIGs have been reported secondary to treatment for tumors outside of the neuroaxis, while the majority of RIGs secondary to treatment for intracranial tumors remain intracranial. Nevertheless, RIGs are associated with a short clinical history, aggressive progression, and poor outcome.

Predictive Factors for Postoperative Tracheostomy Requirement in Children Undergoing Surgical Resection of Medulloblastoma

OBJECTIVE

This study is aimed at identifying factors predicting tracheostomy requirement in children diagnosed with a posterior fossa medulloblastoma postoperatively.

METHODS

A retrospective chart review of all patients younger than 18 undergoing medulloblastoma resection from 2012 to 2020 at Namazi Hospital was conducted.

RESULTS

Forty-five patients (26%) needed tracheostomy after the operation. The most common correlates were brainstem compression and absence of gag reflex before operation. Patients who had brainstem compression and infiltration by medulloblastoma, bilateral absence of gag reflex before operation, subtotal resection of the tumor, and postoperative brainstem contusion were more likely to require tracheostomy. No statistically significant difference was observed between males and females and different ages.

CONCLUSIONS

Medulloblastoma is the most common pediatric malignancy. Postoperative ventilator dependency is an important complication in postoperative recovery of patients undergoing medulloblastoma resection. Considering the mutism syndrome with all its question marks by means of predisposing factors, we dealt with a 2-week policy whether there would be any clinical resolution regarding patients' gag reflex. The results show that if we aim for total tumor resection, tracheostomy that is a highly costly and stressful postoperative morbidity can be prevented.

Circ-SKA3 upregulates ID3 expression by decoying miR-326 to accelerate the development of medulloblastoma

Medulloblastoma (MB), the most common malignant childhood brain tumor, is a serious threat to life. Circular RNA (circRNA) is involved in the development of various cancers, including MB. We aimed to explore the role of circRNA spindle and kinetochore associated complex subunit 3 (circ-SKA3) in MB progression. Circ-SKA3 expression was elevated in MB tissues and cells. Depleted expression of circ-SKA3 inhibited MB cell proliferation, migration and invasion and induced apoptosis and cell cycle arrest, and circ-SKA3 knockdown inhibited MB growth in vivo. Mechanism analyses revealed that circ-SKA3 directly targeted miR-326 that could bind to ID3, and circ-SKA3 decoyed miR-326 to increasing ID3 expression. Rescue experiments showed that miR-326 inhibition reversed the effects of circ-SKA3 knockdown, and ID3 overexpression recovered MB cell proliferation, migration and invasion blocked by miR-326 restoration. In conclusion, circ-SKA3 functioned as an oncogene to promote the development of MB by increasing ID3 expression via decoying miR-326, hinting that circ-SKA3 might be a therapeutic target of MB.

The mammalian Hedgehog pathway is modulated by ANP32 proteins

Medulloblastoma (MB) is the most common malignant brain tumor in children. Transcriptional profiling has so far delineated four major MB subgroups of which one is driven by uncontrolled Hedgehog (Hh) signaling (SHH-MB). This pathway is amenable to drug targeting, yet clinically approved compounds exclusively target the transmembrane component Smoothened (SMO). Unfortunately, drug resistance against SMO inhibitors is encountered frequently, making the identification of novel Hh pathway components mandatory, which could serve as novel drug targets in the future. Here, we have used MB as a tool to delineate novel modulators of Hh signaling and have identified the Acidic Nuclear Phosphoprotein 32 (ANP32) family of proteins as novel regulators. The expression of all three family members (ANP32A, ANP32B, ANP32E) is increased in Hh-induced MB and their expression level is negatively associated with overall survival in SHH-MB patients. Mechanistically, we could find that ANP32 proteins function as positive modulators of mammalian Hh signaling upstream of GLI transcription factors. These findings add hitherto unknown regulators to the mammalian Hh signaling cascade and might spur future translational efforts to combat Hh-driven malignancies.

Longitudinal associations between exposure to anesthesia and neurocognitive functioning in pediatric medulloblastoma

AIM

To examine whether anesthesia exposure is associated with neurocognitive decline in pediatric medulloblastoma.

METHODS

Patients were treated at St. Jude Children's Research Hospital and completed ≥2 protocol-directed neurocognitive assessments (n = 107) as part of a multisite clinical trial for pediatric medulloblastoma (NCT00085202). Patients received risk-adapted craniospinal photon irradiation, followed by four cycles of high-dose chemotherapy and stem cell rescue. Neurocognitive testing was completed at study baseline (after surgery and <2 weeks of starting radiation therapy) and annually for 5 years. Data on anesthesia exposure during treatment was abstracted from medical records.

RESULTS

Patients were 10.2 years at diagnosis on average (SD = 4.5; 37% female, 73% average-risk). Mean cumulative anesthesia duration was 20.4 h (SD = 15.2; range 0.7-55.6 h). In the overall group, longer anesthesia duration was associated with greater declines in IQ (Estimate = -0.08, P < 0.001), attention (Estimate = -0.10, P < .001) and processing speed (Estimate = -0.13, P < 0.001). Similar results were shown in subgroups of patients who were <7 years at diagnosis (IQ = -0.14, P = 0.027; Attention = -0.25: P = 0.011), ≥7 years at diagnosis (Attention = -0.07, P = 0.039; Processing Speed = -0.08, P = 0.022), treated for high-risk disease (IQ = -0.09, P = 0.024; Attention = -0.11, P = 0.034; Processing Speed = -0.13, P = 0.001), or treated for average-risk disease (IQ = -0.05, P = .022; Attention = -0.08, P = 0.011; Processing Speed = -0.10, P < 0.001).

CONCLUSION

Greater anesthesia exposure is a risk factor for clinically significant neurocognitive decline, in addition to factors of age at diagnosis and treatment risk arm. This result is notable as there are evidence-based strategies that can limit the need for anesthesia. Limiting anesthesia exposure, as feasible, may mitigate neurocognitive late effects, and thus, improve quality of life for survivors.

Activation of AMPK sensitizes medulloblastoma to Vismodegib and overcomes Vismodegib-resistance

Vismodegib, a Smoothened antagonist, is clinically approved for treatment of human basal cell carcinoma (BCC), in the clinical trials of medulloblastoma (MB) and other cancers. However, a significant proportion of these tumors fail to respond to Vismodegib after a period of treatment. Here, we find that AMPK agonists, A769662, and Metformin, can inhibit GLI1 activity and synergize with Vismodegib to suppress MB cell growth invitro and invivo. Furthermore, combination of AMPK agonists with Vismodegib is effective in overcoming Vismodegib‐resistant MB. This is the first report demonstrating that combining AMPK agonist (Metformin) and SHH pathway inhibitor (Vismodegib) confers synergy for MB treatment and provides an effective chemotherapeutic regimen that can be used to overcome resistance to Vismodegib in SHH‐driven cancers.

Topoisomerase IIβ immunoreactivity (IR) co-localizes with neuronal marker-IR but not glial fibrillary acidic protein-IR in GLI3-positive medulloblastomas: an immunohistochemical analysis of 124 medulloblastomas from the Japan Children's Cancer Group

We previously reported observing GLI3 in medulloblastomas expressing neuronal markers (NM) and/or glial fibrillary acidic protein (GFAP). Furthermore, patients with medulloblastomas expressing NM or GFAP tended to show favorable or poor prognosis, respectively. In the present study, we focused on the role of topoisomerase IIβ (TOP2β) as a possible regulator for neuronal differentiation in medulloblastomas and examined the pathological roles of GLI3, NM, GFAP, and TOP2β expressions in a larger population. We divided 124 medulloblastomas into three groups (NM-/GFAP-, NM +/GFAP-, and GFAP +) based on their immunoreactivity (IR) against NM and GFAP. The relationship among GLI3, NM, GFAP, and TOP2β was evaluated using fluorescent immunostaining and a publicly available single-cell RNA sequencing dataset. In total, 87, 30, and 7 medulloblastomas were classified as NM-/GFAP-, NM + /GFAP-, and GFAP +, and showed intermediate, good, and poor prognoses, respectively. GLI3-IR was frequently observed in NM +/GFAP-  and GFAP + , and TOP2β-IR was frequently observed only in NM +/GFAP-  medulloblastomas. In fluorescent immunostaining, TOP2β-IR was mostly co-localized with NeuN-IR but not with GFAP-IR. In single-cell RNA sequencing, TOP2β expression was elevated in CMAS/DCX-positive, but not in GFAP-positive, cells. NM-IR and GFAP-IR are important for estimating the prognosis of patients with medulloblastoma; hence they should be assessed in clinical practice.

A case of medulloblastoma in a patient with fetal ventricular enlargement

Medulloblastoma is the second-most common malignant tumor in children. Medulloblastoma has been categorized into four distinct molecular subgroups: WNT, sonic hedgehog (SHH), group 3, and group 4. We report on a male child with medulloblastoma, in whom an enlarged ventricle was diagnosed in utero. Magnetic resonance imaging showed cyst formation in the cerebellar hemisphere initially, with tumor growth being indicated later. Tumor resection was performed when the boy was 12 months old. The histological findings showed extensive nodularity. Further genetic analysis revealed the tumor to be SHH type. This is the first description of a medulloblastoma observed from the fetal stage. Our findings in this case indicate that cyst formation may be the pre-neoplastic lesion of SHH-subtype medulloblastomas.

A boy with a congenital cerebellar mass

PURPOSE

Tumorigenesis of medulloblastoma is believed to be associated with granule cell progenitor neurogenesis of the cerebellum. Nevertheless, congenital medulloblastomas are rarely found. Here, we report a case of congenital medulloblastoma that showed spontaneous albeit transient regression.

METHODS

A one-month-old baby presented with abnormal antenatal and postnatal imaging findings. Upon ultrasonography at 26 weeks of gestational age, Dandy-Walker malformation with vermian hypoplasia and cystic change was suspected. Brain MRI at 1 week after birth revealed gadolinium-enhancing lesions in the cerebellum with apparent infiltrative features along the cerebellar folia accompanied by three independent cysts in the upper and inferolateral sides of the lesion. Serial MRIs taken up to 5 months of age showed a decrease in the size and extent of enhancing solid portions. The baby did not show any abnormal signs or developmental delay. MRI at the age of 7 months showed enlargement of the lesion, and surgery was performed.

RESULTS

The lesion was diagnosed as medulloblastoma with histologically extensive nodularity (MBEN), genetically SHH-activated and TP53-wildtype.

CONCLUSION

This case provides an unusual chance of observing an early phase of medulloblastoma development and raises a suspicion that medulloblastoma may initiate itself very early in cerebellar organogenesis and progress later at a certain time of postnatal development.

A systematic view of pediatric medulloblastoma proteomics-current state of the field and future directions

Quantitative mass spectrometry (MS)-based approaches have allowed further characterization of medulloblastoma (MB) classification and clinical/biological behavior. By investigating protein expression, as well as the role of post-translational modifications in shaping cellular activity, novel avenues of research will clarify the current subgrouping, providing elements for tumor treatment-new molecular targets and signaling cascades-and introducing serum, urinary, and CSF markers of tumor growth and recurrence. We systematically searched and reviewed original research articles treating MB proteomics on PubMed. Reviews, opinion papers, and abstracts were excluded from the final work. A total of 30 novel articles treating the proteomic characterization of MB were included in our review. Research conducted on tissue samples, cell lines, CSF, and urine, as well as exosome and medullospheres, was considered, to picture a broad view of the different directions MS-based proteomic analysis is moving toward. In this review, we collect, summarize, and interpret the current literature on this topic. Significant progress has been achieved in the last decade in MB characterization, paving the way for further exploration of large biobanks of MB and other tissues that will allow a more systematic understanding of MB functioning and clinical progression.

Inter and intra-tumoral heterogeneity as a platform for personalized therapies in medulloblastoma

Medulloblastoma is the most common malignant CNS tumor of childhood, affecting ~350 patients/year in the USA. In 2020, most children are cured of their disease, however, survivors are left with life-long late-effects as a consequence of intensive surgery, and application of chemo- and radio-therapy to the developing brain. A major contributor to improvements in patient survival has been the development of risk-stratified treatments derived from a better understanding of the prognostic value of disease biomarkers. The characterization and validation of these biomarkers has engendered a comprehensive understanding of the extensive heterogeneity that exists within the disease, which can occur both between and within tumors (inter- and intra-tumoral heterogeneity, respectively). In this review, we discuss inter-tumoral heterogeneity, describing the early characterization of clinical and histopathological disease heterogeneity, the more recent elucidation of molecular disease subgroups, and the potential for novel therapies based on specific molecular defects. We reflect on the limitations of current approaches when applied to a rare disease. We then review early investigations of intra-tumoral heterogeneity using FISH and immunohistochemical approaches, and focus on the application of next generation sequencing on bulk tumors to elucidate intra-tumoral heterogeneity. Finally, we critically appraise the applications of single-cell sequencing approaches and discuss their potential to drive next biological insights, and for routine clinical application.

Differentiation Between Ependymoma and Medulloblastoma in Children with Radiomics Approach

RATIONALE AND OBJECTIVES

Ependymoma (EP) and medulloblastoma (MB) of children are similar in age, location, manifestations and symptoms. Therefore, it is difficult to differentiate them through visual observation in clinical diagnosis. The aim of this study is to investigate the effectiveness of radiomics and machine-learning techniques on multimodal magnetic resonance imaging (MRI) in distinguish EP from MB.

MATERIALS AND METHODS

Three dimensional (3D) tumors were semi-automatic segmented by radiologists from postcontrast T1-weighted images and apparent diffusion coefficient maps in 51 patients (24 EPs, 27 MBs). Then, we extracted radiomics features and further reduced them by three feature selection methods. For each feature selection method, 4 classifiers were adopted which yield 12 different models. After extensive crossvalidation, pairwise test were carried out in receiver operating characteristic curves to explore performance of these models.

RESULTS

The radiomics model built with multivariable logistic regression as feature selection method and random forests as classifier had the best performance, area under the curve achieved 0.91 (95 % confidence interval 0.787-0.968). Five relevant features were highly correlated to discriminate EP and MB, which may used as imaging biomarkers to predict the kinds of tumors.

CONCLUSION

The combination of radiomics and machine-learning approach on 3D multimodal MRI could well distinguish EP and MB of childhood, which assistant doctors in clinical diagnosis. Since there is no uniform model to obtained best performance for every specific data set, it is necessary to try different combination methods.

Medulloblastoma drugs in development: Current leads, trials and drawbacks

Medulloblastoma (MB) is the most common malignant brain tumor in children. Current treatment for MB includes surgical resection, radiotherapy and chemotherapy. Despite significant progress in its management, a portion of children relapse and tumor recurrence carries a poor prognosis. Based on their molecular and clinical characteristics, MB patients are clinically classified into four groups: Wnt, Hh, Group 3, and Group 4. With our increased understanding of relevant molecular pathways disrupted in MB, the development of targeted therapies for MB has also increased. Targeted drugs have shown unique privileges over traditional cytotoxic therapies in balancing efficacy and toxicity, with many of them approved and widely used clinically. The aim of this review is to present the recent progress on targeted chemotherapies for the treatment of all classes of MB.

Medulloblastoma: clinicopathological parameters, risk stratification, and survival analysis of immunohistochemically validated molecular subgroups

BACKGROUND

Medulloblastoma (MB) is a heterogeneous disease, displaying distinct genetic profiles with specific molecular subgroups. This study aimed to validate MB molecular subgrouping using surrogate immunohistochemistry and associate molecular subgroups, histopathological types, and available clinicopathological parameters with overall survival (OS) and progression-free survival (PFS) of MB patients. This study included 40 MBs; immunohistochemical staining, using β-catenin and GRB2-Associated Binding Protein 1 (GAB1) antibodies, was used to classify MB cases into wingless signaling activated (WNT), sonic hedgehog (SHH), and non-WNT/SHH molecular subgroups. Nuclear morphometric analysis (for assessment of degree of anaplasia) and Kaplan-Meier survival curves were done.

RESULTS

MB cases were classified into WNT (10%), SHH (30%), and non-WNT/SHH (60%) subgroups. Histopathological types differed significantly according to tumor location (p< 0.001), degree of anaplasia (p = 0.014), molecular subgroups (p < 0.001), and risk stratification (p = 0.008). Molecular subgroups differed significantly in age distribution (p = 0.031), tumor location (p< 0.001), histopathological variants (p < 0.001), and risk stratification (p < 0.001). OS was 77.5% and 50% after 1 and 2 years, while PFS was 65% and 27.5% after 1 and 2 years, respectively. OS and PFS were associated significantly with histopathological variants (p < 0.001 and 0.001), molecular subgroups (p = 0.012 and 0.005), and risk stratification (p < 0.001 and < 0.001), respectively.

CONCLUSIONS

Medulloblastoma classification based on molecular subgroups, together with clinicopathological indicators, mainly histopathological types; accurately risk stratifies MB patients and predicts their survival.

Poly(2-oxazoline) nanoparticle delivery enhances the therapeutic potential of vismodegib for medulloblastoma by improving CNS pharmacokinetics and reducing systemic toxicity

We report a nanoparticle formulation of the SHH-pathway inhibitor vismodegib that improves efficacy for medulloblastoma, while reducing toxicity. Limited blood-brain barrier (BBB) penetration and dose-limiting extitle/citraneural toxicities complicate systemic therapies for brain tumors. Vismodegib is FDA-approved for SHH-driven basal cell carcinoma, but implementation for medulloblastoma has been limited by inadequate efficacy and excessive bone toxicity. To address these issues through optimized drug delivery, we formulated vismodegib in polyoxazoline block copolymer micelles (POx-vismo). We then evaluated POx-vismo in transgenic mice that develop SHH-driven medulloblastomas with native vasculature and tumor microenvironment. POx-vismo improved CNS pharmacokinetics and reduced bone toxicity. Mechanistically, the nanoparticle carrier did not enter the CNS, and acted within the vascular compartment to improve drug delivery. Unlike conventional vismodegib, POx-vismo extended survival in medulloblastoma-bearing mice. Our results show the broad potential for non-targeted nanoparticle formulation to improve systemic brain tumor therapy, and specifically to improve vismodegib therapy for SHH-driven cancers.

MT1 and MT2 melatonin receptors play opposite roles in brain cancer progression

Primary brain tumors remain among the deadliest of all cancers. Glioma grade IV (glioblastoma), the most common and malignant type of brain cancer, is associated with a 5-year survival rate of < 5%. Melatonin has been widely reported as an anticancer molecule, and we have recently demonstrated that the ability of gliomas to synthesize and accumulate this indolamine in the surrounding microenvironment negatively correlates with tumor malignancy. However, our understanding of the specific effects mediated through the activation of melatonin membrane receptors remains limited. Thus, here we investigated the specific roles of MT1 and MT2 in gliomas and medulloblastomas. Using the MT2 antagonist DH97, we showed that MT1 activation has a negative impact on the proliferation of human glioma and medulloblastoma cell lines, while MT2 activation has an opposite effect. Accordingly, gliomas have a decreased mRNA expression of MT1 (also known as MTNR1A) and an increased mRNA expression of MT2 (also known as MTNR1B) compared to the normal brain cortex. The MT1/MT2 expression ratio negatively correlates with the expression of cell cycle-related genes and is a positive prognostic factor in gliomas. Notably, we showed that functional selective drugs that simultaneously activate MT1 and inhibit MT2 exert robust anti-tumor effects in vitro and in vivo, downregulating the expression of cell cycle and energy metabolism genes in glioma stem-like cells. Overall, we provided the first evidence regarding the differential roles of MT1 and MT2 in brain tumor progression, highlighting their relevance as druggable targets. KEY MESSAGES: • MT1 impairs while MT2 promotes the proliferation of glioma and medulloblastoma cell lines. • Gliomas have a decreased expression of MT1 and an increased expression of MT2 compared to normal brain cortex. • Tumors with a high MT1/MT2 expression ratio have significantly better survival rates. • Functional selective drugs that simultaneously activate MT1 and inhibit MT2 downregulate the expression of cell cycle and energy metabolism genes in glioma stem-like cells and exert robust anti-tumor effects in vivo.

Development of hedgehog pathway inhibitors by epigenetically targeting GLI through BET bromodomain for the treatment of medulloblastoma

Medulloblastoma (MB) is a common yet highly heterogeneous childhood malignant brain tumor, however, clinically effective molecular targeted therapy is lacking. Modulation of hedgehog (HH) signaling by epigenetically targeting the transcriptional factors GLI through bromodomain-containing protein 4 (BRD4) has recently spurred new interest as potential treatment of HH-driven MB. Through screening of current clinical BRD4 inhibitors for their inhibitory potency against glioma-associated oncogene homolog (GLI) protein, the BRD4 inhibitor 2 was selected as the lead for further structural optimization, which led to the identification of compounds 25 and 35 as the high potency HH inhibitors. Mechanism profiling showed that both compounds suppressed HH signaling by interacting with the transcriptional factor GLI, and were equally potent against the clinical resistant mutants and the wild type of smoothened (SMO) receptor with IC₅₀ values around 1 nmol/L. In the resistant MB allograft mice, compound 25 was well tolerated and markedly suppressed tumor growth at both 5 mg/kg (TGI = 83.3%) and 10 mg/kg (TGI = 87.6%) doses. Although further modification is needed to improve the pharmacokinetic (PK) parameters, compound 25 represents an efficacious lead compound of GLI inhibitors, possessing optimal safety and tolerance to fight against HH-driven MB.

Retrospective investigation of hereditary syndromes in patients with medulloblastoma in a single institution

PURPOSE

To investigate the incidence rate of hereditary disease in patients with medulloblastoma.

METHODS

The genetic reports of 129 patients with medulloblastoma from January 2016 to December 2019 were retrospectively analyzed. A panel sequence of 39 genes (Genetron Health) were used for all patients to evaluate the tumor subgroup. Four genes (TP53, APC, PTCH1, SUFU) were screened to routinely rule out germline mutation.

RESULTS

Five patients (3.9%) were found with hereditary disease, and all belonged to the sonic hedgehog (SHH) subgroup. Two patients were retrospectively diagnosed with Gorlin-Goltz disease with germline PTCH1 and SUFU mutations. One patient (PTCH1 mutation) accepted whole craniospinal irradiation and had scalp nevoid basal cell carcinoma 5 years later. The other patient (SUFU mutation) accepted chemotherapy and had local tumor relapse 1 year later. Three patients were diagnosed with Li-Fraumeni syndrome and carried the TP53 mutation; all three patients died. One of the patients had bone osteosarcoma, while all three had early tumor relapse.

CONCLUSION

Patients with SHH medulloblastoma should routinely undergo genetic testing. We propose that whole genome, whole exome sequence, or custom-designed panel-targeted exome sequencing should be performed.

Functional tracts of the cerebellum-essentials for the neurosurgeon

The cerebellum is historically implicated in motor coordination, but accumulating modern evidence indicates involvement in non-motor domains, including cognition, emotion, and language. This correlates with the symptoms observed in postoperative cerebellar mutism syndrome (CMS). Profound knowledge of cerebellar functional topography and tractography is important when approaching cerebellar tumors, as surgical trauma to relevant structures of cerebellar pathways plays a role in the pathogenesis of CMS. The aim of this systematic review is to provide a concise overview of relevant modern neuroimaging data and cerebellar functional tracts with regard to neurosurgical procedures.

Benign skull and subdural lesions in patients with prior medulloblastoma therapy

PURPOSE

To report on our institutional cohort of patients and review the literature of medulloblastoma patients who developed skull/subdural-based lesions following treatment.

METHODS

Following institutional review board (IRB) approval, we retrospectively reviewed the medical records of four children with a history of treated medulloblastoma who developed non-specific skull-based/subdural lesions incidentally found on surveillance imaging.

RESULTS

Biopsies of the lesions proved the pathology to be low grade and included inflammatory myofibroblastic tumor, cortical fibrous defect consistent with fibroma, fibrous tissue, and fibrous dysplasia. The finding of calvarial or subdural fibrous lesions in children following therapy for medulloblastoma was noted in four out of 201 (136 with available follow-up data) medulloblastoma patients seen or discussed in our institution over the past 10 years.

CONCLUSIONS

These lesions can grow over time and pose a differential diagnostic challenge with metastatic disease when identified. The skull and subdural space should be scrutinized for secondary lesions on surveillance imaging of patients with medulloblastoma who have received craniospinal irradiation as knowledge of this benign occurrence will assist with management.

Invited Review: Dysregulation of chromatin remodellers in paediatric brain tumours - SMARCB1 and beyond

Mutations in chromatin remodelling genes occur in approximately 25% of all human tumours (Kadoch et al. Nat Genet 45: 592-601, 2013). The spectrum of alterations is broad and comprises single nucleotide variants, insertion/deletions and more complex structural variations. The single most often affected remodelling complex is the SWI/SNF complex (SWItch/sucrose non-fermentable). In the field of paediatric neuro-oncology, the spectrum of affected genes implicated in epigenetic remodelling is narrower with SMARCB1 and SMARCA4 being the most frequent. The low mutation frequencies in many of the SWI/SNF mutant entities underline the fact that perturbed chromatin remodelling is the most salient factor in tumourigenesis and could thus be a potential therapeutic opportunity. Here, I review the genetic basis of aberrant chromatin remodelling in paediatric brain tumours and discuss their impact on the epigenome in the respective entities, mainly medulloblastomas and rhabdoid tumours.

Harnessing brain development to understand brain tumours

Brain tumours are the commonest solid neoplasms in children, accounting for one quarter of all childhood cancers. Our growing knowledge of basic developmental mechanisms has significantly contributed to understanding the pathogenesis of these tumours and is beginning to impact clinical decisions on how children with these diseases are treated.

Surgical management of posterior fossa medulloblastoma in children: The Lyon experience

INTRODUCTION

Modern approach for the treatment of posterior fossa medulloblastomas remains a challenge for pediatric neurosurgeons and pediatric oncologists and requires a multidisciplinary approach to optimize survival and clinical results.

MATERIAL AND METHODS

We report the surgical principles of the treatment of posterior fossa medulloblastomas in children and how to avoid technical mistakes especially in very young patients. We also report our experience in a series of 64 patients operated from a medulloblastoma between 2000 and 2018 in Lyon.

RESULTS

All patients had a craniospinal MRI. Eighty-one percent of the patients (n=50) had strictly midline tumor while 19% (n=14) had lateralized one. Eleven percent (n=7) had metastasis at diagnosis on the initial MRI. Forty-one percent (n=29) had an emergency ETV to treat hydrocephaly and the intracranial hypertension. All patient underwent a direct approach and a complete removal was achieved in 78% (n=58) of the cases on the postoperative MRI realized within 48h postsurgery. Histological findings revealed classical medulloblastoma in 73% (n=46), desmoplastic medulloblastoma in 17% (n=11) and anaplastic/large cell medulloblastoma in 10% (n=7). Patients were classified as low risk in 7 cases, standard risk in 30 cases and high risk in 27 cases. Ninety-six percent (n=61) of the patient received radiotherapy. Seventy-six percent (n=48) received pre-irradiation or adjuvant chemotherapy. At last follow-up in December 2018, 65% (n=41) of the patient were in complete remission, 12% (n=8) were in relapse and 27% (n=15) had died from their disease. The overall survival at five , ten and fifteen years for all the series was of 76%, 73% and 65.7% respectively.

CONCLUSIONS

Medulloblastomas remain a chimiosensible and radiosensible disease and the complete surgical removal represents a favorable prognostic factor. The extension of surgery has also to be weighted in consideration of the new biomolecular and genetic knowledge that have to be integrated by surgeons to improve quality of life of patients.