Morphophenotypic variation predicts clinical behavior in childhood non-desmoplastic medulloblastomas

Loss of phosphatase CTDNEP1 potentiates aggressive medulloblastoma by triggering MYC amplification and genomic instability

MYC-driven medulloblastomas are highly aggressive childhood brain tumors, however, the molecular and genetic events triggering MYC amplification and malignant transformation remain elusive. Here we report that mutations in CTDNEP1, a CTD nuclear-envelope-phosphatase, are the most significantly enriched recurrent alterations in MYC-driven medulloblastomas, and define high-risk subsets with poorer prognosis. Ctdnep1 ablation promotes the transformation of murine cerebellar progenitors into Myc-amplified medulloblastomas, resembling their human counterparts. CTDNEP1 deficiency stabilizes and activates MYC activity by elevating MYC serine-62 phosphorylation, and triggers chromosomal instability to induce p53 loss and Myc amplifications. Further, phosphoproteomics reveals that CTDNEP1 post-translationally modulates the activities of key regulators for chromosome segregation and mitotic checkpoint regulators including topoisomerase TOP2A and checkpoint kinase CHEK1. Co-targeting MYC and CHEK1 activities synergistically inhibits CTDNEP1-deficient MYC-amplified tumor growth and prolongs animal survival. Together, our studies demonstrate that CTDNEP1 is a tumor suppressor in highly aggressive MYC-driven medulloblastomas by controlling MYC activity and mitotic fidelity, pointing to a CTDNEP1-dependent targetable therapeutic vulnerability.

Medulloblastomas in Pediatric and Adults

Medulloblastoma is the primary malignant embryonic tumor of the cerebellum and the most common malignant tumor of childhood, accounting up to 25% of all CNS tumors in children, but is extremely rare in adults. Despite the fact that medulloblastomas are one of the most malignant human tumors, it is worthy to note that a great breakthrough has been achieved in our understanding of oncogenesis and the development of real methods of treatment. The main objective of surgical treatment is a maximum resection of tumor with minimal impairment of neurological functions, in order to reduce the volume, remove tumor tissue, get the biopsy, and restore the cerebrospinal fluid flow. The progress of surgical techniques (using a microscope, ultrasound suction), anesthesiology, and intensive care has significantly decreased surgical mortality and increased radicality of tumor removal. Postoperative mortality is less than one percent in most studies, while neurological complications have been reported between 5-10%. Radiotherapy is the main method of treatment in patients older than 3 years, which dramatically improved the recurrence-free survival. Nevertheless, the radiation therapy without systemic chemotherapy leads to a high risk of systemic metastases. After the role of chemotherapy was statistically proven, investigations of the optimal combination of different chemotherapy regimens continued around the world. Currently, 80% of patients can already be cured, however, the quality of life of patients in the long-term period remains quite low, which depends on many factors including endocrinological, cognitive, neurological, and otoneurologic aspects. Thus, the main strategic goal of the development of neuro-oncology is to reduce the doses of radiation therapy to the CNS and the main task of international research is to optimize existing protocols and develop fundamentally new ones based on molecular genetic research in order to improve the quality of life.

A simplified overview of the World Health Organization classification of central nervous system tumors 2021

Background:

Building on the 2016 updated fourth edition and the work of consortium to inform molecular and practical approach to CNS tumor taxonomy, the major dramatic change occurs in 2021 fifth edition by advancing the role of molecular diagnostics in CNS tumor classification. The present review summarizes the major general changes in the 2021 fifth edition classification and the specific changes in each taxonomic category.

Methods:

The review was designed in accordance to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis. Articles published in PubMed Central, Medline, and Embase databases till now were all searched. Only nonexperimental and nonanimal clinical studies were included in the study. Articles written only in the English language were considered.

Results:

All IDH mutant diffuse astrocytic tumors are considered in a single type “astrocytoma IDH mutant” and then graded as CNS WHO Grades 2–4. Pediatric-type diffuse gliomas are now classified as separate entity. Anatomical site is also taken into consideration to classify ependymoma. The “Desmoplastic myxoid tumor of the pineal region, SMARCB1 mutant” and “Atypical neurofibromatous neoplasm of unknown biological potential” are new tumor type added to pineal and neurofibroma group, respectively. Mesenchymal tumor is now termed as only solitary fibrous tumor. Adamantinomatous and papillary subtype of craniopharyngioma are now classified as distinct tumor type. The new term “Pituitary neuroendocrine tumor” has been coined for pituitary adenoma.

Conclusion:

The WHO CNS-5 introduces a new knowledge into the classification with progressive manner by introducing newly recognizing entities, by obsoleting tumor type, and by adjusting the taxonomic structure.

Clinical Trials in High-Risk Medulloblastoma: Evolution of the SIOP-Europe HR-MB Trial

Medulloblastoma patients receive adapted therapies stratified according to their risk-profile. Favourable, standard, and high disease-risk groups are each defined by the status of clinical and pathological risk factors, alongside an evolving repertoire of diagnostic and prognostic biomarkers. Medulloblastoma clinical trials in Europe are coordinated by the International Society for Paediatric Oncology (SIOP-Europe) brain tumour group. Favourable and standard-risk patients are eligible for the SIOP-PNET5-MB clinical trial protocol. In contrast, therapies for high-risk disease worldwide have, to date, encompassed a range of different treatment philosophies, with no clear consensus on approach. Higher radiotherapy doses are typically deployed, delivered either conventionally or in hyper-fractionated/accelerated regimens. Similarly, both standard and high-dose chemotherapies were assessed. However, trials to date in high-risk medulloblastoma have commonly been institutional or national, based on modest cohort sizes, and have not evaluated the relative performance of different strategies in a randomised fashion. We describe the concepts and design of the SIOP-E high-risk medulloblastoma clinical trial (SIOP-HR-MB), the first international biomarker-driven, randomised, clinical trial for high-risk medulloblastoma. SIOP-HR-MB is programmed to recruit >800 patients in 16 countries across Europe; its primary objectives are to assess the relative efficacies of the alternative established regimens. The HR-MB patient population is molecularly and clinically defined, and upfront assessments incorporate a standardised central review of molecular pathology, radiology, and radiotherapy quality assurance. Secondary objectives include the assessment of (i) novel therapies within an upfront 'window' and (ii) therapy-associated neuropsychology, toxicity, and late effects, alongside (iii) the collection of materials for comprehensive integrated studies of biological determinants within the SIOP-HR-MB cohort.

Relapsed Medulloblastoma in Pre-Irradiated Patients: Current Practice for Diagnostics and Treatment

Relapsed medulloblastoma (rMB) accounts for a considerable, and disproportionate amount of childhood cancer deaths. Recent advances have gone someway to characterising disease biology at relapse including second malignancies that often cannot be distinguished from relapse on imaging alone. Furthermore, there are now multiple international early-phase trials exploring drug-target matches across a range of high-risk/relapsed paediatric tumours. Despite these advances, treatment at relapse in pre-irradiated patients is typically non-curative and focuses on providing life-prolonging and symptom-modifying care that is tailored to the needs and wishes of the individual and their family. Here, we describe the current understanding of prognostic factors at disease relapse such as principal molecular group, adverse molecular biology, and timing of relapse. We provide an overview of the clinical diagnostic process including signs and symptoms, staging investigations, and molecular pathology, followed by a summary of treatment modalities and considerations. Finally, we summarise future directions to progress understanding of treatment resistance and the biological mechanisms underpinning early therapy-refractory and relapsed disease. These initiatives include development of comprehensive and collaborative molecular profiling approaches at relapse, liquid biopsies such as cerebrospinal fluid (CSF) as a biomarker of minimal residual disease (MRD), modelling strategies, and the use of primary tumour material for real-time drug screening approaches.

Clinically Tractable Outcome Prediction of non-WNT/non-SHH Medulloblastoma Based on TPD52 Immunohistochemistry in a Multicohort Study

PURPOSE

International consensus and the 2021 WHO classification recognize eight molecular subgroups among non-WNT/non-SHH (Group 3/4) medulloblastoma, representing ~60% of tumors. However, very few clinical centers worldwide possess the technical capabilities to determine DNA-methylation profiles or other molecular parameters of high-risk for Group 3/4 tumors. As a result, biomarker-driven risk stratification and therapy assignment constitutes a major challenge in medulloblastoma research. Here, we identify an immunohistochemistry (IHC) marker as a clinically tractable method for improved medulloblastoma risk stratification.

EXPERIMENTAL DESIGN

We bioinformatically analyzed published medulloblastoma transcriptomes and proteomes identifying as a potential biomarker TPD52, whose IHC prognostic value was validated across three Group 3/4 medulloblastoma clinical cohorts (n = 387) treated with conventional therapies.

RESULTS

TPD52 IHC positivity represented a significant independent predictor of early relapse and death for Group 3/4 medulloblastoma (HRs between 3.67-26.7 [95% CIs between 1.00-706.23], p = 0.05, 0.017 and 0.0058). Cross-validated survival models incorporating TPD52 IHC with clinical features outperformed existing state-of-the-art risk stratification schemes, and reclassified ~50% of patients into more appropriate risk categories. Finally, TPD52 immunopositivity was a predictive indicator of poor response to chemotherapy (HR 12.66 [95% CI 3.53-45.40], p < 0.0001), suggesting important implication for therapeutic choices.

CONCLUSIONS

The current study redefines the approach to risk stratification in Group 3/4 medulloblastoma in global practice. Since integration of TPD52 IHC in classification algorithms significantly improved outcome prediction, this test could be rapidly adopted for risk stratification on a global scale, independently of advanced but technically challenging molecular profiling techniques.

The 2021 WHO Classification of Tumors of the Central Nervous System: a summary

The fifth edition of the WHO Classification of Tumors of the Central Nervous System (CNS), published in 2021, is the sixth version of the international standard for the classification of brain and spinal cord tumors. Building on the 2016 updated fourth edition and the work of the Consortium to Inform Molecular and Practical Approaches to CNS Tumor Taxonomy, the 2021 fifth edition introduces major changes that advance the role of molecular diagnostics in CNS tumor classification. At the same time, it remains wedded to other established approaches to tumor diagnosis such as histology and immunohistochemistry. In doing so, the fifth edition establishes some different approaches to both CNS tumor nomenclature and grading and it emphasizes the importance of integrated diagnoses and layered reports. New tumor types and subtypes are introduced, some based on novel diagnostic technologies such as DNA methylome profiling. The present review summarizes the major general changes in the 2021 fifth edition classification and the specific changes in each taxonomic category. It is hoped that this summary provides an overview to facilitate more in-depth exploration of the entire fifth edition of the WHO Classification of Tumors of the Central Nervous System.

Pathology, diagnostics, and classification of medulloblastoma

Medulloblastoma (MB) is the most common CNS embryonal tumor. While the overall cure rate is around 70%, patients with high‐risk disease continue to have poor outcome and experience long‐term morbidity. MB is among the tumors for which diagnosis, risk stratification, and clinical management has shown the most rapid advancement. These advances are largely due to technological improvements in diagnosis and risk stratification which now integrate histomorphologic classification and molecular classification. MB stands as a prototype for other solid tumors in how to effectively integrate morphology and genomic data to stratify clinicopathologic risk and aid design of innovative clinical trials for precision medicine. This review explores the current diagnostic and classification of MB in modern neuropathology laboratories.

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.

Pediatric Posterior Fossa Medulloblastoma: The Role of Diffusion Imaging in Identifying Molecular Groups

BACKGROUND AND PURPOSE

The molecular groups WNT activated (WNT), Sonic hedgehog activated (SHH), group 3, and group 4 are biologically and clinically distinct forms of medulloblastoma. We evaluated apparent diffusion coefficient (ADC) values' utility in differentiating/predicting medulloblastoma groups at the initial diagnostic imaging evaluation and prior to surgery.

METHODS

We retrospectively measured the ADC values of the enhancing, solid portion of the tumor (EST) and of the whole tumor (WT) and performed Kruskal-Wallis testing to compare the absolute tumor ADC values and cerebellar and thalamic ratios of three medulloblastoma groups (WNT, SHH, and group 3/group 4 combined).

RESULTS

Ninety-three children (65 males) were included. Fifty-seven children had group 3/group 4, 27 had SHH, and 9 had WNT medulloblastomas. The median absolute ADC values in the EST and WT were .719 × 10^-3 and .864 × 10^-3 mm² /s for group 3/group 4; .660 × 10^-3 and .965 × 10^-3 mm² /s for SHH; and .594 × 10^-3 and .728 × 10^-3 mm² /s for WNT medulloblastomas (P = .02 and .13). The median ratio of ADC values in the EST or the WT to normal cerebellar tissue was highest for group 3/group 4 and lowest for WNT medulloblastomas (P = .03 and .09), with similar results in pairwise comparisons of the corresponding thalamic ADC values (P = .02 and .06).

CONCLUSION

ADC analysis of a tumor's contrast-enhancing solid portion may aid preoperative molecular classification/prediction of pediatric medulloblastomas and may facilitate optimal surgical treatment planning, reducing surgery-induced morbidity.

Differentiation of Outcomes by Treatment Regimen and Histology in Central Nervous System Primary Embryonal Tumors

BACKGROUND

Central nervous system (CNS) embryonal tumors are malignant neoplasms of undifferentiated embryonic cells that typically occur in the pediatric population. They are further divided into many subgroups by distinct histologic and genetic profiles. We present the largest study to date to identify differential survival outcomes within each subgroup by treatment regimen.

METHODS

The SEER (Surveillance Epidemiology and End Results) database was queried from 1973 to 2015 for embryonal tumors of primary CNS origin (n = 3900). The effects of patient demographics, tumor characteristics, and treatment regimen were analyzed using a multivariate Cox proportional hazard model in CNS embryonal tumor subtypes divided into medulloblastoma, atypical teratoid/rhabdoid tumor, and primitive neuroectodermal tumor.

RESULTS

No significant patient demographic factors were found to be associated with increased mortality. In all 3 CNS embryonal tumor subtypes, most monotherapy and combinatorial treatment paradigms showed a higher hazard ratio compared with gross total resection with adjuvant chemoradiotherapy (hazard ratio, 1.72-22.94; P < 0.05 for all). In a subgroup analysis of patients with medulloblastoma ≤3 years of age, patients who did not receive radiation showed lower survival probabilities at 1, 5, and 10 years (odds ratio [OR], 0.37, P < 0.0001; OR, 0.39, P < 0.0001; OR, 0.34, P < 0.0001, respectively). Kaplan-Meier analysis of medulloblastoma histologic subtypes showed that use of radiation imparted a higher survival probability in the desmoplastic/nodular medulloblastoma and medulloblastoma not otherwise specified groups (P < 0.001 for both).

CONCLUSIONS

CNS embryonal tumors are highly malignant in all populations and the best survival is seen with aggressive combination therapies. Radiation therapy may have a role in prolonging survival in patients with medulloblastoma ≤3 years of age.

Proteomics data of ovine mastitis associated with Mannheimia haemolytica

Proteomics data have been obtained from experimental mastitis in ewes after intramammary challenge with Mannheimia haemolytica. Animals were sampled before and sequentially after challenge; blood plasma and milk whey samples were produced and were subjected to proteomics evaluation by means of two-dimensional gel electrophoresis and MALDI-TOF mass spectrometry. Full protein maps and differential proteomics in sequential samples from blood plasma and milk whey of experimental ewes were presented. Post-challenge, 33 and 89 proteins were identified with differential abundance in blood plasma and milk whey, respectively. Also, 74 proteins were identified with differential abundance between the inoculated and contralateral glands. The data provide further insight in the pathogenesis of mastitis in sheep and indicate potential biomarkers for the disease. The data are further discussed in the research article “Differential quantitative proteomics study of experimental Mannheimia haemolytica mastitis in sheep” [1].

Differential quantitative proteomics study of experimental Mannheimia haemolytica mastitis in sheep

Objective was the differential quantitative proteomics study of ovine mastitis induced by Mannheimia haemolytica; clinical, microbiological, cytological and histopathological methods were employed for confirmation and monitoring. Proteins were separated by two-dimensional gel electrophoresis (2-DE) for all samples and differentially abundant proteins were identified by mass spectrometry; comparisons were performed with pre- (blood, milk) and post- (milk of contralateral gland) inoculation findings. Animals developed mastitis, confirmed by isolation of challenge strain and increase of neutrophils in milk and by histopathological evidence. In blood plasma, 33 differentially abundant proteins (compared to findings before challenge) were identified: 6 with decrease, 13 with new appearance and 14 with varying abundance. In a post-challenge milk whey protein reference map, 65 proteins were identified; actin cytoplasmic-1, beta-lactoglobulin-1/B, cathelicidin-1 predominated. Further, 89 differentially abundant proteins (compared to findings before challenge) were identified: 18 with decrease, 53 with new appearance, 3 with increase and 15 with varying abundance; 15 proteins showed status changes in blood plasma and milk whey. Differential abundance from inoculated and contralateral glands revealed 74 proteins only from the inoculated gland. Most differentially abundant proteins in milk whey were involved in cell organisation and biogenesis (n = 17) or in inflammatory and defence response (n = 13). SIGNIFICANCE: The proteomes of blood and milk from ewes with experimental mastitis caused by Mannheimia haemolytica and the differential proteomics in sequential samples after challenge are presented for the first time. This is the first detailed proteomics study in M. haemolytica-associated mastitis in ewes. An experimental model fully simulating natural mastitis has been used. Use of experimentally induced mastitis minimised potential variations and allowed consistency of results. The study included evaluation of changes in blood plasma and milk whey. Protein patterns have been studied, indicating with great accuracy changes that had occurred as part of the disease process and development, during the acute phase of infection. Relevant protein-protein interactions were studied. The entirety of proteomics findings has suggested that affected ewes had mounted a defence response that had been regulated by many proteins (e.g., cathelicidins, haptoglobin, serum amyloid A) and through various pathways (e.g., acute phase response, binding and transporting significant ions and molecules); these were interdependent at various points. Potential biomarkers have been indicated for use in diagnostic assays of mastitis.

Twenty years experience in treating childhood medulloblastoma: Between the past and the present

PURPOSE

Medulloblastoma is the most common primary malignant central nervous system tumour in children. These last decades, treatment modalities have largely evolved resulting in better survival rates. Nevertheless, long-term toxicity is a major concern in this setting. The purpose of this study was to analyse the clinical results and medical outcomes of a cohort of paediatric patients treated for medulloblastoma in Xhinhua Hospital in Shanghai. These results are compared with those from other centres reported in literature.

PATIENTS AND METHODS

This was a retrospective study conducted at Xhinhua Hospital in Shanghai, China. It included 121 patients treated for medulloblastoma from 1993 to December 2013.

RESULTS

Mean age at diagnosis was 6.7 years (range: 1-14.3 years). Total surgical resection was achieved in 60% of the cases. Classic medulloblastoma was found in 59% of the cases. Adjuvant radiotherapy was delivered in all cases and chemotherapy concerned 70.2% of the studied cohort. The median follow-up time of the study was 84 months (range: 24-120 months). Five- and 10 years progression-free survival rates were 83.2%, and 69.5% and 5 years and 10 years. Overall survival rates were 82.5%, and 72.5%. Patient's age significantly influenced survival: patients under 3 years old had the worse outcomes (P=0.01). T and M stages also significantly impacted survival rates: advanced stages were associated with lower rates (P=0.08 and 0.05 respectively). Finally, patients receiving temezolomide had bad outcomes when compared to the new standard protocol used in the department (P=0.03). The most commonly reported late toxicity was growth suppression in 35 patients (52.2%). Hypothyroidism requiring hormone replacement was recorded in 29% of the cases. Hearing loss, and problems including poor concentration, poor memory and learning difficulties were reported in 19% and 25% of the cases respectively. Second cancers were noted in three cases.

CONCLUSION

Overall, our results are comparable to those reported in literature. Nevertheless, efforts should be made to ensure longer follow-ups and correctly assess treatment-related toxicity.

Medulloblastoma

Medulloblastoma (MB) comprises a biologically heterogeneous group of embryonal tumours of the cerebellum. Four subgroups of MB have been described (WNT, sonic hedgehog (SHH), Group 3 and Group 4), each of which is associated with different genetic alterations, age at onset and prognosis. These subgroups have broadly been incorporated into the WHO classification of central nervous system tumours but still need to be accounted for to appropriately tailor disease risk to therapy intensity and to target therapy to disease biology. In this Primer, the epidemiology (including MB predisposition), molecular pathogenesis and integrative diagnosis taking histomorphology, molecular genetics and imaging into account are reviewed. In addition, management strategies, which encompass surgical resection of the tumour, cranio-spinal irradiation and chemotherapy, are discussed, together with the possibility of focusing more on disease biology and robust molecularly driven patient stratification in future clinical trials.

Treatment of pediatric average-risk medulloblastoma using craniospinal irradiation less than 2500 cGy and chemotherapy: single center experience in Korea

BACKGROUND

Although craniospinal irradiation (CSI) of 2340 cGy plus tumor booster with chemotherapy have been established as a standard treatment of childhood average-risk (AvR) medulloblastoma (MBL) in Western counties, there are a few recent reports in outcomes of AvR MBL using this strategy in Korean and other Asian children. We investigated the outcome of the Korean children with AvR MBL who were treated with CSI <2500 cGy and chemotherapy.

METHODS

Between January 2001 and December 2010, clinical characteristics and outcomes of 42 patients who were diagnosed with AvR MBL postoperatively and treated with radiation including CSI <2500 cGy and chemotherapy in Seoul National University Children's Hospital were analyzed.

RESULTS

Their median age was 9 years (range: 3-18.8), and 29 were male. Histological subtypes were classic type in 28 patients, nodular/desmoplastic in 7, and large cell/anaplastic (LCA) in 7. All the patients received adjuvant radiotherapy (CSI with median 2340 cGy and booster) and multiagent chemotherapy as the first-line treatment. With a median follow-up of 54 months, 12 patients experienced relapse or progression of the tumor. The 3- and 5-year disease-free survival (DFS) rates were 78.0%±6.5% and 75.0%±6.9%, respectively, and overall survival (OS) rates were 85.3%±5.6% and 76.8%±6.9%, respectively. The LCA subtype was associated with poorer DFS (P=0.023) and OS (P=0.008), compared with non-LCA subtypes.

CONCLUSIONS

The outcomes of children and adolescents with AvR MBL treated with radiation including CSI <2500 cGy and chemotherapy, are compatible to those in Western countries; however, the LCA subtype has a poor outcome with this strategy.

Large cell/anaplastic medulloblastoma is associated with poor prognosis-a retrospective analysis at a single institute

PURPOSE

Medulloblastoma (MB) is the most commonly occurring malignant pediatric brain tumor worldwide. However, a recent study found that the treatment outcomes in those with high-risk disease receiving conventional treatment were suboptimal. This study aimed to assess outcomes and treatment strategies for specific histologic subtypes of pediatric MB.

METHODS

A total of 114 pediatric patients (age < 20 years) diagnosed with MB between March 1998 and August 2011 were retrospectively reviewed; 52 that were treated with surgery followed by adjuvant radiotherapy (RT) and chemotherapy (CHT) were included.

RESULTS

The 5-year overall survival (OS) and relapse-free survival (RFS) rates were 73 and 69%, respectively. Median time to relapse was 17 months with a median survival time of 6 months after relapse. Patients of average risk had a better 5-year OS rate compared with high-risk patients (p = 0.027). The 5-year RFS of high-risk patients was lower compared with average risk (p = 0.038). A greater proportion of patients with large cell/anaplastic (LC/A) MB had recurrence than classic MB with 5-year RFS rate of 34 and 76%, respectively (p = 0.001), and OS rate of 56 and 76%, respectively (p = 0.04).

CONCLUSION

High-risk group and histology of LC/A were the most significant factors associated with worse OS and RFS. Patients with LC/A-MB had higher relapse rates and worse survival than those with classic MB. LC/A-MB carries a high risk for recurrence and should be treated with the more aggressive strategies.

The new WHO 2016 classification of brain tumors-what neurosurgeons need to know

BACKGROUND

The understanding of molecular alterations of tumors has severely changed the concept of classification in all fields of pathology. The availability of high-throughput technologies such as next-generation sequencing allows for a much more precise definition of tumor entities. Also in the field of brain tumors a dramatic increase of knowledge has occurred over the last years partially calling into question the purely morphologically based concepts that were used as exclusive defining criteria in the WHO 2007 classification.

METHODS

Review of the WHO 2016 classification of brain tumors as well as a search and review of publications in the literature relevant for brain tumor classification from 2007 up to now.

RESULTS

The idea of incorporating the molecular features in classifying tumors of the central nervous system led the authors of the new WHO 2016 classification to encounter inevitable conceptual problems, particularly with respect to linking morphology to molecular alterations. As a solution they introduced the concept of a "layered diagnosis" to the classification of brain tumors that still allows at a lower level a purely morphologically based diagnosis while partially forcing the incorporation of molecular characteristics for an "integrated diagnosis" at the highest diagnostic level. In this context the broad availability of molecular assays was debated. On the one hand molecular antibodies specifically targeting mutated proteins should be available in nearly all neuropathological laboratories. On the other hand, different high-throughput assays are accessible only in few first-world neuropathological institutions. As examples oligodendrogliomas are now primarily defined by molecular characteristics since the required assays are generally established, whereas molecular grouping of ependymomas, found to clearly outperform morphologically based tumor interpretation, was rejected from inclusion in the WHO 2016 classification because the required assays are currently only established in a small number of institutions.

CONCLUSION

In summary, while neuropathologists have now encountered various challenges in the transitional phase from the previous WHO 2007 version to the new WHO 2016 classification of brain tumors, clinical neurooncologists now face many new diagnoses allowing a clearly improved understanding that could offer them more effective therapeutic opportunities in neurooncological treatment. The new WHO 2016 classification presumably presents the highest number of modifications since the initial WHO classification of 1979 and thereby forces all professionals in the field of neurooncology to intensively understand the new concepts. This review article aims to present the basic concepts of the new WHO 2016 brain tumor classification for neurosurgeons with a focus on neurooncology.

Medulloblastoma

Medulloblastoma accounts for nearly 10% of all childhood brain tumors. These tumors occur exclusively in the posterior fossa and have the potential for leptomeningeal spread. Treatment includes a combination of surgery, radiation therapy (in patients >3 years old). Patients >3 years old are stratified based on the volume of postoperative residual tumor and the presence or absence of metastases into "standard risk" and "high risk" categories with long-term survival rates of approximately 85% and 70%, respectively. Outcomes are inferior in infants and children younger than 3 years with exception of those patients with the medulloblastoma with extensive nodularity histologic subtype. Treatment for medulloblastoma is associated with significant morbidity, especially in the youngest patients. Recent molecular subclassification of medulloblastoma has potential prognostic and therapeutic implications. Future incorporation of molecular subgroups into treatment protocols will hopefully improve both survival outcomes and posttreatment quality of life.

Childhood medulloblastoma

Medulloblastoma accounts for 15-20% of childhood nervous system tumours. The risk of dying was reduced by 30% in the last twenty years. Patients are divided in risk strata according to post-surgical disease, dissemination, histology and some molecular features such as WNT subgroup and MYC status. Sixty to 70% of patients older than 3 years are assigned to the average-risk group. High-risk patients include those with disseminated and/or residual disease, large cell and/or anaplastic histotypes, MYC genes amplification. Current and currently planned clinical trials will: (1) evaluate the feasibility of reducing both the dose of craniospinal irradiation and the volume of the posterior fossa radiotherapy (RT) for those patients at low biologic risk, commonly identified as those having a medulloblastoma of the WNT subgroup; (2) determine whether intensification of chemotherapy (CT) or irradiation can improve outcome in patients with high-risk disease; (3) find target therapies allowing tailored therapies especially for relapsing patients and those with higher biological risk.

Milk of Greek sheep and goat breeds; characterization by means of proteomics

Over the past 30years there has been a growing interest to unravel the dynamic framework of the milk proteome, and now that available technology is mature enough to enable techniques of protein fractionation and identification, this process is on-going. Due to its rarity and unique biological traits, as well as its growing financial value, milk of dairy Greek animals is continuously attracting interest from both the scientific community and industry. In the present study we employed cutting-edge proteomics methodologies to investigate and characterize, in depth, the proteome of whey from all pure-breed Greek sheep and goats. A mean of >500 protein groups were identified in whey from each breed of each animal species, reporting for the first time the proteome dataset of this precious biological material. Given its high nutritional value, the protein properties exposed herein will govern future steps in optimizing characteristics and features of sheep and goat milk products.

SIGNIFICANCE

In the present study we employed cutting-edge proteomics methodologies to investigate and characterize, in depth, the proteome of milk from all pure-breed Greek sheep and goats. A mean of >500 protein groups were identified in milk whey from each breed of each animal species, reporting for the first time the proteome dataset of this precious biological material. Given its high nutritional value, the protein properties exposed herein will govern future steps in optimizing characteristics and features of sheep and goat milk products.

Biomarker-driven stratification of disease-risk in non-metastatic medulloblastoma: Results from the multi-center HIT-SIOP-PNET4 clinical trial

PURPOSE

To improve stratification of risk-adapted treatment for non-metastatic (M0), standard-risk medulloblastoma patients by prospective evaluation of biomarkers of reported biological or prognostic significance, alongside clinico-pathological variables, within the multi-center HIT-SIOP-PNET4 trial.

METHODS

Formalin-fixed paraffin-embedded tumor tissues were collected from 338 M0 patients (>4.0 years at diagnosis) for pathology review and assessment of the WNT subgroup (MBWNT) and genomic copy-number defects (chromosome 17, MYC/MYCN, 9q22 (PTCH1) and DNA ploidy). Clinical characteristics were reviewed centrally.

RESULTS

The favorable prognosis of MBWNT was confirmed, however better outcomes were observed for non-MBWNT tumors in this clinical risk-defined cohort compared to previous disease-wide clinical trials. Chromosome 17p/q defects were heterogeneous when assessed at the cellular copy-number level, and predicted poor prognosis when they occurred against a diploid (ch17(im)/diploid(cen)), but not polyploid, genetic background. These factors, together with post-surgical tumor residuum (R+) and radiotherapy delay, were supported as independent prognostic markers in multivariate testing. Notably, MYC and MYCN amplification were not associated with adverse outcome. In cross-validated survival models derived for the clinical standard-risk (M0/R0) disease group, (ch17(im)/diploid(cen); 14% of patients) predicted high disease-risk, while the outcomes of patients without (ch17(im)/diploid(cen)) did not differ significantly from MBWNT, allowing re-classification of 86% as favorable-risk.

CONCLUSIONS

Biomarkers, established previously in disease-wide studies, behave differently in clinically-defined standard-risk disease. Distinct biomarkers are required to assess disease-risk in this group, and define improved risk-stratification models. Routine testing for specific patterns of chromosome 17 imbalance at the cellular level, and MBWNT, provides a strong basis for incorporation into future trials.

[Evolution of the management of pediatric and adult medulloblastoma]

Medulloblastoma are cerebellar tumours belonging to the group of primitive neuroectodermal tumours (PNET) and are the most common malignant brain tumours of childhood. These tumours are rare and heterogeneous, requiring some multicentric prospective studies and multidisciplinary care. The classical therapeutic approaches are based on clinical, radiological and surgical data. They involve surgery, radiation therapy and chemotherapy. Some histological features were added to characterize risk. More recently, molecular knowledge has allowed to devise risk-adapted strategies and helped to define groups with good outcome and reduce long-term sequelae, improve the prognostic of high-risk medulloblastoma and develop new therapeutic tools.

Clinical significance of anaplasia in childhood rhabdomyosarcoma

BACKGROUND

The presence of anaplastic features has been known to correlate with poor clinical outcome in various pediatric malignancies, including Wilms tumor and medulloblastoma but not in rhabdomyosarcoma.

AIM

Aim was to study the frequency of anaplasia at presentation in childhood rhabdomyosarcoma and its relationship to clinical and pathological characteristics as well as to outcome.

PATIENTS AND METHODS

Anaplasia was retrospectively assessed in 105 consecutive pediatric rhabdomyosarcoma patients who were registered at the Children's Cancer Hospital in Egypt (CCHE) during the period from July 2007 till the end of May 2010.

RESULTS

Anaplasia was diagnosed in 18 patients (17.1%), focal in 10 (9.5%) and diffuse in 8 (7.6%). The distribution of anaplasia was found to be more common in older patients having age⩾10 years. Also it was more likely to occur in the high risk group and in tumors with unfavorable histology (alveolar subtype), and stage IV. The 3-year failure free survival rates for patients with and without anaplasia were 27.8±10.6% and 53.4±5.8%, respectively (p=0.014) and the 3-year overall survival rates were 35.3±11.6% and 61±6%, respectively (p=0.019).

CONCLUSIONS

The frequency of anaplasia in pediatric patients with rhabdomyosarcoma in our study was 17.1%. The presence of anaplasia had statistically significant worse clinical outcome.

Medulloblastoma: recurrence and metastasis

Medulloblastoma is the most common malignant brain tumor of childhood. Although there is now long-term survival or cure for the majority of children, the survivors bear a significant burden of complications due, at least in part, to the intense therapies given to ensure eradication of the tumor. Significant efforts have been made over the years to be able to distinguish between patients who do and do not need intensive therapies. This review summarizes the history and current state of clinical risk stratification, pathologic diagnosis and genetics. Recent developments in correlation between genetics and pathology, genome-wide association studies and the biology of medulloblastoma metastasis are discussed in detail. The current state of clinical treatment trials are reviewed and placed into the perspective of potential novel therapies in the near term.

Proteomic studies of pediatric medulloblastoma tumors with 17p deletion

CNS tumors are the leading cause of cancer-related death in children. Medulloblastoma is the commonest pediatric CNS malignancy, wherein, despite multimodal therapy with surgery, radiation, and chemotherapy, 5 year survival rates merely approach 60%. Until present, gene expression and cytogenetic studies have produced contradicting findings regarding the molecular background of the specific disease. Through integration of genomics, bioinformatics, and proteomics, the current study aims to shed light at the proteomic-related molecular events responsible for MBL pathophysiology, as well as to provide molecular/protein/pathway answers concerning tumor-onset. Experiments were performed on tissues collected at surgery. With 17p loss being the commonest chromosomal aberrance observed in our sample set, array-CGH were employed to first distinguish for 17p-positive cases. 2-DE coupled to mass spectrometry identification exposed the MBL-specific protein profile. Protein profiles of malignant tissues were compared against profiles of normal cerebellar tissues, and quantitative protein differences were determined. Bioinformatics, functional and database analyses, characterization, and subnetwork profiling generated information on MBL protein interactions. Key molecules of the PI3K/mTOR signaling network were identified via the techniques applied herein. Among the findings IGF2, PI3K, Rictor, MAPKAP1, S6K1, 4EBP1, and ELF4A, as part of the IGF network (implicating PI3K/mTOR), were founded to be deregulated.

DJ-1 is activated in medulloblastoma and is associated with cell proliferation and differentiation

BACKGROUND

DJ-1 is a key regulator in human tumorigenesis, including brain malignancies. The mechanisms by which DJ-1 contributes to the pathogenesis of medulloblastoma (MB) remain unclear, and its impact on the prognosis for patients with MB has not been identified. The aim of this study was to determine whether the DJ-1 protein is associated with tumorigenesis of MBs, and whether DJ-1 is a valuable factor for predicting the prognosis of patients with MB.

METHODS

We collected 66 pairs of MB and adjacent normal cerebellum samples. Expression of DJ-1, Ser 473-phosphorylated-Akt (p-Akt), PTEN, and Ki-67 (MIB-1) was detected by immunohistochemical staining, and the correlation of these immunostaining results with the clinicopathological features of patients with MB was determined.

RESULTS

High DJ-1 expression (48.5%, 32/66) in tumor cells of MBs was significantly associated with the classic MB variant (P = 0.003), high proliferative activity (P = 0.002) and undifferentiated tumor (P = 0.001), whereas high p-Akt expression (56.1%, 37/66) was associated with tumor metastasis stage (P = 0.007), undifferentiated tumor (P = 0.007), and high-risk tumor (P = 0.002). High DJ-1 expression also correlated with high p-Akt expression and high MIB-1 index. However, only high levels of DJ-1(P = 0.009) and high MIB-1 index (P = 0.001) were strong independent prognostic factors associated with worse overall survival.

CONCLUSIONS

Although the validity of the preliminary data in this study needs to be confirmed by a larger number of cases, our study indicates that DJ-1, PTEN, and p-Akt might play important roles in cell proliferation and differentiation of MBs. The evaluation of expression of DJ-1 and related proteins might be useful for predicting the prognosis of patients with MB.

Advancements in the treatment of pediatric acute leukemia and brain tumor - continuous efforts for 100% cure

Treatment outcomes of pediatric cancers have improved greatly with the development of improved treatment protocols, new drugs, and better supportive measures, resulting in overall survival rates greater than 70%. Survival rates are highest in acute lymphoblastic leukemia, reaching more than 90%, owing to risk-based treatment through multicenter clinical trials and protocols developed to prevent central nervous system relapse and testicular relapse in boys. New drugs including clofarabine and nelarabine are currently being evaluated in clinical trials, and other targeted agents are continuously being developed. Chimeric antigen receptor-modified T cells are now attracting interest for the treatment of recurrent or refractory disease. Stem cell transplantation is still the most effective treatment for pediatric acute myeloid leukemia (AML). However, in order to reduce treatment-related death after stem cell transplantation, there is need for improved treatments. New drugs and targeted agents are also needed for improved outcome of AML. Surgery and radiation therapy have been the mainstay for brain tumor treatment. However, chemotherapy is becoming more important for patients who are not eligible for radiotherapy owing to age. Stem cell transplant as a means of high dose chemotherapy and stem cell rescue is a new treatment modality and is often repeated for improved survival. Drugs such as temozolomide are new chemotherapeutic options. In order to achieve 100% cure in children with pediatric cancer, every possible treatment modality and effort should be considered.

Medulloblastoma Down Under 2013: a report from the third annual meeting of the International Medulloblastoma Working Group

Medulloblastoma is curable in approximately 70 % of patients. Over the past decade, progress in improving survival using conventional therapies has stalled, resulting in reduced quality of life due to treatment-related side effects, which are a major concern in survivors. The vast amount of genomic and molecular data generated over the last 5–10 years encourages optimism that improved risk stratification and new molecular targets will improve outcomes. It is now clear that medulloblastoma is not a single-disease entity, but instead consists of at least four distinct molecular subgroups: WNT/Wingless, Sonic Hedgehog, Group 3, and Group 4. The Medulloblastoma Down Under 2013 meeting, which convened at Bunker Bay, Australia, brought together 50 leading clinicians and scientists. The 2-day agenda included focused sessions on pathology and molecular stratification, genomics and mouse models, high-throughput drug screening, and clinical trial design. The meeting established a global action plan to translate novel biologic insights and drug targeting into treatment regimens to improve outcomes. A consensus was reached in several key areas, with the most important being that a novel classification scheme for medulloblastoma based on the four molecular subgroups, as well as histopathologic features, should be presented for consideration in the upcoming fifth edition of the World Health Organization’s classification of tumours of the central nervous system. Three other notable areas of agreement were as follows: (1) to establish a central repository of annotated mouse models that are readily accessible and freely available to the international research community; (2) to institute common eligibility criteria between the Children’s Oncology Group and the International Society of Paediatric Oncology Europe and initiate joint or parallel clinical trials; (3) to share preliminary high-throughput screening data across discovery labs to hasten the development of novel therapeutics. Medulloblastoma Down Under 2013 was an effective forum for meaningful discussion, which resulted in enhancing international collaborative clinical and translational research of this rare disease. This template could be applied to other fields to devise global action plans addressing all aspects of a disease, from improved disease classification, treatment stratification, and drug targeting to superior treatment regimens to be assessed in cooperative international clinical trials.

Expression of heat shock proteins in medulloblastoma

OBJECT

Medulloblastoma (MB) is the most common malignant brain tumor in children. Heat shock proteins (HSPs) comprise a superfamily of proteins that serve as molecular chaperones and are overexpressed in a wide range of human cancers. The purpose of the present study was to investigate the expression of HSP27 (pSer(82)), HSP27 (pSer(15)), HSP40, HSP60, HSP70, HSP90-α, Akt, and phospho-Akt by multiplex bead array assay of MBs. The results of HSP and Akt expression were correlated with MB subtype; immunohistochemical expression of Ki-67 index, bcl-2, and p53; and patients' prognosis.

METHODS

The authors retrospectively evaluated 25 children with MB who underwent surgery. Immunohistochemical analysis of Ki-67, p53, and bcl-2 expression was performed in all cases. By using multiplex bead array assay, a simultaneous detection of HSP27 (pSer(82)), HSP27 (pSer(15)), HSP40, HSP60, HSP70, HSP90-α, Akt, and phospho-Akt was performed.

RESULTS

Medulloblastoma with extensive nodularity had significantly lower HSP27 (pSer(15)) expression (p = 0.039) but significantly higher HSP60 expression (p = 0.021) than classic MB. Large-cell MB had significantly higher HSP70 expression (p = 0.028) than classic MB. No significant difference was found between HSP27 (pSer(82)), HSP40, HSP90-α, Akt, or phospho-Akt expression and MB subtype. Large-cell MBs had significantly higher Ki-67 index compared with classic MBs (p = 0.033). When analyzing all MBs, there was a significant negative correlation between HSP27 (pSer(15)) and Ki-67 index (r = -0.475, p = 0.016); a significant positive correlation between HSP70 expression and Ki-67 index (r = 0.407, p = 0.043); and a significant positive correlation between HSP70 expression and bcl-2 index (r = 0.491, p = 0.023). Patients with large-cell MB had a worse survival than those with classic MB, but the difference did not reach statistical significance (p = 0.076).

CONCLUSIONS

A substantial expression of several HSPs in MB was observed. Given that HSPs represent an attractive strategy for anticancer therapy, further studies, involving larger series of patients, are obviously necessary to clarify the relationship of HSPs with tumor aggressiveness and prognosis.

Neuronal differentiation associated with Gli3 expression predicts favorable outcome for patients with medulloblastoma

Medulloblastoma (MB) is a malignant cerebellar tumor arising in children, and its ontogenesis is regulated by Sonic Hedgehog (Shh) signaling. No data are available regarding the correlation between expression of Gli3, a protein lying downstream of Shh, and neuronal differentiation of MB cells, or the prognostic significance of these features. We re-evaluated the histopathological features of surgical specimens of MB taken from 32 patients, and defined 15 of them as MB with neuronal differentiation (ND), three as MB with both glial and neuronal differentiation (GD), and 14 as differentiation-free (DF) MB. Gli3-immunoreactivity (IR) was evident as a clear circular stain outlining the nuclei of the tumor cells. The difference in the frequency of IR between the ND+GD (94.4%) and DF (0%) groups was significant (P < 0.001). The tumor cells with ND showed IR for both Gli3 and neuronal nuclei. Ultrastructurally, Gli3-IR was observed at the nuclear membrane. The overall survival and event-free survival rates of the patients in the ND group were significantly higher than those in the other groups. The expression profile of Gli3 is of considerable significance, and the association of ND with this feature may be prognostically favorable in patients with MB.

Distinctive MRI features of pediatric medulloblastoma subtypes

OBJECTIVE

We hypothesized that the apparent diffusion coefficient (ADC) and other MRI features can be used to predict medulloblastoma histologic subtypes, as defined by the World Health Organization (WHO) in WHO Classification of Tumours of the Central Nervous System.

MATERIALS AND METHODS

A retrospective review of pediatric patients with medulloblastoma between 1989 and 2011 identified 38 patients with both pretreatment MRI and original pathology slides. The mean and minimum tumor ADC values and conventional MRI features were compared among medulloblastoma histologic subtypes.

RESULTS

The cohort of 38 patients included the following histologic subtypes: 24 classic medulloblastomas, nine large cell (LC) or anaplastic medulloblastomas, four desmoplastic medulloblastomas, and one medulloblastoma with extensive nodularity. The median age at diagnosis was 8 years (range, 1-21 years) and the median follow-up time was 33 months (range, 0-150 months). The mean ADC (× 10(-3) mm(2)/s) was lower in classic medulloblastoma (0.733 ± 0.046 [SD]) than in LC or anaplastic medulloblastoma (0.935 ± 0.127) (Mann-Whitney test, p = 0.004). Similarly, the minimum ADC was lower in classic medulloblastoma (average ± SD, 0.464 ± 0.056) than in LC or anaplastic medulloblastoma (0.630 ± 0.053) (p = 0.004). The MRI finding of focal cysts correlated with the classic and desmoplastic subtypes (Fisher exact test, p = 0.026). Leptomeningeal enhancement positively correlated with the LC or anaplastic medulloblastoma subtype and inversely correlated with the classic medulloblastoma and desmoplastic medulloblastoma subtypes (p = 0.04). Ring enhancement correlated with tumor necrosis (p = 0.022) and with the LC or anaplastic medulloblastoma histologic subtype (p < 0.001).

CONCLUSION

The LC or anaplastic medulloblastoma subtype was associated with increased ADC and with ring enhancement, the latter of which correlated with tumor necrosis. These features could be considered in the evaluation of high-risk medulloblastoma subtypes.

Histological variants of medulloblastoma are the most powerful clinical prognostic indicators

BACKGROUND

Medulloblastoma histological classification has gained in importance and newer treatment protocols will include histology stratification. We centrally reviewed medulloblastoma cases from past 10 years reassessing their histology to ascertain its prognostic significance.

METHODS

Samples from 125 consecutive patients (99 males; 10 under age 3 years) were reviewed according to the two WHO classifications of 2000/2007.

RESULTS

Eighty-two patients did not have metastases, the primary tumor was completely resected in 101. The median follow-up was 96 months. Treatment was: our institutional protocol, that is, hyperfractionated accelerated radiotherapy (HART), for 39 non-metastatic cases up to 2003; according to the European PNET IV protocol in 31 cases; a HART-based strategy in 39 metastatic cases; tailored to the age below 3 years and based on high-dose chemotherapy in 10; and tailored to the patients conditions in 7. The 5-year PFS/OS rates were 76% and 81%, respectively. Histology was classic in 93 cases, nodular/desmoplastic in 20, anaplastic/large-cell in 9, and with extensive nodularity (MBEN) in 3. Stratification by residual disease after resection, metastases, age, or protocols was not prognostic. Histology suggested 5-year PFS rates of 82% for the desmoplastic and MBEN variants, 78% for classic medulloblastoma, 44% for the anaplastic/large-cell variants (P = 0.01). Multivariable analysis demonstrated statistically significant difference in PFS by histology (P = 0.02), due to the poor prognosis of anaplastic/large-cell medulloblastoma.

CONCLUSIONS

Tailoring treatments to known risk factors cancelled all prognostic differences, except for anaplasia (not considered as such within previous trials) which proved the most powerful prognostic factor, warranting appropriate treatment intensification.

Hyperfractionated Versus Conventional Radiotherapy Followed by Chemotherapy in Standard-Risk Medulloblastoma: Results From the Randomized Multicenter HIT-SIOP PNET 4 Trial

Purpose

To compare event-free survival (EFS), overall survival (OS), pattern of relapse, and hearing loss in children with standard-risk medulloblastoma treated by postoperative hyperfractionated or conventionally fractionated radiotherapy followed by maintenance chemotherapy.

Patients and Methods

In all, 340 children age 4 to 21 years from 122 European centers were postoperatively staged and randomly assigned to treatment with hyperfractionated radiotherapy (HFRT) or standard (conventional) fractionated radiotherapy (STRT) followed by a common chemotherapy regimen consisting of eight cycles of cisplatin, lomustine, and vincristine.

Results

After a median follow-up of 4.8 years (range, 0.1 to 8.3 years), survival rates were not significantly different between the two treatment arms: 5-year EFS was 77% ± 4% in the STRT group and 78% ± 4% in the HFRT group; corresponding 5-year OS was 87% ± 3% and 85% ± 3%, respectively. A postoperative residual tumor of more than 1.5 cm2 was the strongest negative prognostic factor. EFS of children with all reference assessments and no large residual tumor was 82% ± 2% at 5 years. Patients with a delay of more than 7 weeks to the start of RT had a worse prognosis. Severe hearing loss was not significantly different for the two treatment arms at follow-up.

Conclusion

In this large randomized European study, which enrolled patients with standard-risk medulloblastoma from more than 100 centers, excellent survival rates were achieved in patients without a large postoperative residual tumor and without RT treatment delays. EFS and OS for HFRT was not superior to STRT, which therefore remains standard of care in this disease.

Loss of INI1 protein expression defines a subgroup of aggressive central nervous system primitive neuroectodermal tumors

Pediatric embryonal brain tumors can be difficult to classify. Atypical teratoid rhabdoid tumors (ATRT) contain rhabdoid cells, while primitive neuroectodermal tumors (PNETs) are composed of "small round blue cells." Loss of INI1 is a common event in ATRT; therefore, we investigated if the loss of INI1 protein expression was also observed in central nervous system (CNS) PNET and pineoblastoma. A histological review of 42 CNS PNETs and six pineoblastomas was performed. INI1 expression was assessed by immunohistochemistry. Sequencing was performed on the mutational hotspots of INI1. INI1-immunonegative tumors were further investigated using fluorescence in situ hybridization. Epithelial membrane antigen (EMA) protein expression was assessed in six CNS PNETs to further define the phenotype. Five CNS PNETs without rhabdoid cell morphology were immuno-negative for both INI1 and EMA. Of these primary CNS PNET patients, three died <11 months postdiagnosis, which was dissimilar to the INI1-immunopositive primary CNS PNETs where 18/24 (75%) patients were alive 1 year postdiagnosis. We have identified a small subgroup of CNS PNETs which lack INI1 protein expression, but have no evidence of rhabdoid cell morphology. INI1 protein loss may occur through mechanisms other than gene deletion. INI1 immunohistochemistry should be performed for all CNS PNET cases.

Pediatric neuro-oncology: current status and future directions

Tumors of the central nervous system (CNS) are the most common solid malignancies in childhood and are the leading cause of cancer-related death in this age group. While an ongoing improvement in overall prognosis has been achieved in the last few decades, current therapeutic approaches still confer significant morbidities, especially for the very young. The traditional strategies of surgery, radiotherapy and conventional cytotoxic chemotherapy need to be further refined while newer approaches, including molecularly targeted agents, hold the promise of better responses, improved outcomes and reduced toxicities. This article discusses treatment standards, the focus of current clinical investigations and the future promise of novel, biologically based approaches for the most common pediatric CNS tumors: primitive neuroectodermal tumors including medulloblastomas, ependymomas and astrocytomas (both low-grade and high-grade glioma).

A mouse model of the most aggressive subgroup of human medulloblastoma

Medulloblastomas that display a large cell/anaplastic morphology and overexpress the cellular c-MYC gene are highly aggressive and carry a very poor prognosis. This so-called MYC-subgroup differs in its histopathology, gene expression profile, and clinical behavior from other forms of medulloblastoma. We generated a mouse model of MYC-subgroup medulloblastoma by transducing Trp53-null cerebellar progenitor cells with Myc. The cardinal features of these mouse medulloblastomas closely mimic those of human MYC-subgroup tumors and significantly differ from mouse models of the Sonic-Hedgehog- and WNT-disease subgroups. This mouse model should significantly accelerate understanding and treatment of the most aggressive form of medulloblastoma and infers distinct roles for MYC and MYCN in tumorigenesis.

Embryonal central nervous system neoplasms arising in infants and young children: a pediatric brain tumor consortium study

CONTEXT

Medulloblastomas (MBs) and atypical teratoid/rhabdoid tumors (AT/RTs) arising in infants and children can be difficult to distinguish; however, histologic characterization is prognostically important.

OBJECTIVE

To determine histologic and phenotypic markers associated with utility with progression-free survival (PFS) and overall survival (OS) in children younger than 3 years with MBs and AT/RTs.

DESIGN

We undertook a histologic and immunophenotypic study of MBs and AT/RTs arising in infants and children younger than 3 years treated in a Pediatric Brain Tumor Consortium study. The 41 girls and 55 boys ranged in age from 2 to 36 months at enrollment. These infants and children exhibited 51 MBs, 26 AT/RTs, and 24 other tumors (not further studied). Median follow-up of the patients was 17.2 months from diagnosis (range: 1.4-93 months).

RESULTS

Infants and children with AT/RT exhibited a statistically significant shorter PFS and OS when compared to infants and children with MBs (both P < .001). A lack of nuclear BAF47 immunohistochemical reactivity proved reliable in identifying AT/RTs. Among MBs, our data suggest an association of nodularity and prolonged PFS and OS, which must be independently confirmed. Anaplasia correlated with OTX2 reactivity and both OTX2 and moderate to severe anaplasia correlated with PFS but not with OS.

CONCLUSION

Distinguishing AT/RT from MBs is clinically important. For expert neuropathologists, the diagnoses of AT/RT and MB can be reliably made from hematoxylin-eosin stains in the vast majority of cases. However certain rare small cell variants of AT/RT can be confused with MB. We also found that immunohistochemical reactivity for BAF47 is clinically useful in distinguishing MBs from AT/RTs and for identifying certain small cell AT/RTs. Among MBs, nodularity may be an important prognostic factor for improved PFS and OS in infants and children.

Childhood medulloblastoma

Among all the childhood central nervous system tumours, medulloblastoma and other neuroectodermal tumours account for 16-25% of cases. The causative factors of medulloblastoma/PNET have not been well established. It is more frequent in boys than in girl and in children than in adults. There was a significant improvement of survival for children diagnosed in 2000-2002 compared to those diagnosed in 1995-1999. The risk of dying was reduced by 30%. Patients are generally divided into risk-stratified schemes on the basis of age, the extent of residual disease, and dissemination. Sixty to 70% of patients older than 3 years are assigned to the average-risk group. High-risk patients include those in the disseminated category, and in North American trials those that have less than a gross or near-total resection, which is arbitrarily defined as 1.5 cm(2) of post-operative residual disease. Current and currently planned clinical trials will:define molecular and biological markers that improve outcome prediction in patients with medulloblastoma and which can be incorporated for front-line stratification of newly defined risk subgroups.

Survival and prognostic factors of early childhood medulloblastoma: an international meta-analysis

PURPOSE

To assess the prognostic role of clinical parameters and histology in early childhood medulloblastoma.

PATIENTS AND METHODS

Clinical and histologic data from 270 children younger than age 5 years diagnosed with medulloblastoma between March 1987 and July 2004 and treated within prospective trials of five national study groups were centrally analyzed.

RESULTS

Two hundred sixty children with medulloblastoma and specified histologic subtype were eligible for analysis (median age, 1.89 years; median follow-up, 8.0 years). Rates for 8-year event-free survival (EFS) and overall survival (OS) were 55% and 76%, respectively, in 108 children with desmoplastic/nodular medulloblastoma (DNMB) or medulloblastoma with extensive nodularity (MBEN); 27% and 42%, respectively, in 145 children with classic medulloblastoma (CMB); and 14% and 14%, respectively, in seven children with large-cell/anaplastic (LC/A) medulloblastoma (P < .001). Histology (DNMB/MBEN: hazard ratio [HR], 0.44; 95% CI, 0.31 to 0.64; LC/A medulloblastoma: HR, 2.27; 95% CI, 0.95 to 5.54; P < .001 compared with CMB), incomplete resection and metastases (M0R1: HR, 1.86; 95% CI, 1.29 to 2.80; M+: HR, 2.28; 95% CI, 1.50 to 3.46; P < .001 compared with M0R0), and national group were independent prognostic factors for EFS, and OS. The HRs for OS ranged from 0.14 for localized M0 and DNMB/MBEN to 13.67 for metastatic LC/A medulloblastoma in different national groups.

CONCLUSION

Our results confirm the high frequency of desmoplastic variants of medulloblastomas in early childhood and histopathology as a strong independent prognostic factor. A controlled de-escalation of treatment may be appropriate for young children with DNMB and MBEN in future clinical trials.

Definition of disease-risk stratification groups in childhood medulloblastoma using combined clinical, pathologic, and molecular variables

PURPOSE

Medulloblastomas are heterogeneous and include relatively good-prognosis tumors characterized by Wnt pathway activation, as well as those that cannot be successfully treated with conventional therapy. Developing a practical therapeutic stratification that allows accurate identification of disease risk offers the potential to individualize adjuvant therapy and to minimize long-term adverse effects in a subgroup of survivors.

METHODS

Using formalin-fixed paraffin-embedded (FFPE) tissue for immunohistochemistry, fluorescent in situ hybridization, and direct sequencing to identify tumors with a Wnt pathway signature and those harboring copy number abnormalities (CNAs) of potential prognostic significance (MYC/MYCN amplification, CNAs of chromosome 6 and 17), we evaluated clinical, pathologic, and molecular outcome indicators and stratification models in a cohort (n = 207) of patients with medulloblastoma 3 to 16 years of age from the International Society of Pediatric Oncology CNS9102 (PNET3) trial.

RESULTS

Metastatic disease and large-cell/anaplastic (LC/A) phenotype were the clinicopathologic variables associated with poor progression-free survival (PFS). Nuclear immunoreactivity for β-catenin, CTNNB1 mutation, and monosomy 6 all identified a group of good-prognosis patients. MYC amplification was associated with poor outcome, but other CNAs were not. Low-risk medulloblastomas were defined as β-catenin nucleopositive tumors without metastasis at presentation, LC/A phenotype, or MYC amplification. High-risk medulloblastomas were defined as tumors with metastatic disease, LC/A phenotype, or MYC amplification. Low-risk, standard-risk, and high-risk categories of medulloblastoma had significantly (P < .0001) different outcomes.

CONCLUSION

Integrating assays of molecular biomarkers undertaken on routinely collected diagnostic FFPE tissue into stratification schemes for medulloblastoma alongside clinical and pathologic outcome indicators can refine current definition of disease risk and guide adjuvant therapy.

Childhood medulloblastoma: novel approaches to the classification of a heterogeneous disease

Increasing recognition of pediatric medulloblastoma as a heterogeneous disease, with histopathological and molecular variants that have distinct biological behaviors, will impact how the disease is classified and treated. A combination of clinicopathological evaluation and assays based on molecular subgroups of disease will allow stratification of patients into risk groups and a more tailored approach to therapy. Patients with low-risk disease could be treated with de-escalated adjuvant therapy to maximize cure while reducing long-term adverse effects, and novel therapies could be sought for patients with high-risk disease. My review encompasses a brief overview of the clinical landscape, the current World Health Organization (WHO) classification of medulloblastoma, the status of molecular subgroups, and how potential stratification schemes might impact pathologists and their practice.

Low-level copy number changes of MYC genes have a prognostic impact in medulloblastoma

High-level amplifications of MYC genes are associated with poor outcomes in childhood medulloblastoma (MB). However, the occurrence of MYCN and MYCC copy number increases below the intense amplification pattern is rarely reported, and its clinical impact has not yet been determined. Here, we describe this phenomenon and its prognostic significance in a cohort of 29 MB patients. Using interphase fluorescence in situ hybridization (I-FISH), low-level copy number alterations, i.e. gain of MYCN, were shown in 5/27 (19%) samples, whereas amplification was revealed in only 1/27 (4%) samples. MYCC gain was revealed in 6/29 (21%) MB, while amplification was disclosed in only 2/29 (7%). Hyperploidy and co-incidence of gains in both MYC loci were frequently observed in samples with copy number aberrations. Survival analysis has clearly shown that MYC copy number increases are associated with lowered event-free survival and overall survival in MB. In the case of MYCN, this negative correlation was statistically significant. We conclude that limited numerical alterations in loci 2p24 (MYCN) and 8q24 (MYCC), as assessed by I-FISH, are present in MB with a higher frequency than high-level amplifications. Poor prognoses were observed in patients with copy number increases in MYC genes. Our data illustrate the importance of further investigations in multicenter trials to better refine the emerging genomic-based prognostic stratification in MB.

Pleiotropic role for MYCN in medulloblastoma

Medulloblastoma (MB) is the most common malignant brain tumor of childhood. Sonic Hedgehog (SHH) signaling drives a minority of MB, correlating with desmoplastic pathology and favorable outcome. The majority, however, arises independently of SHH and displays classic or large cell anaplastic (LCA) pathology and poor prognosis. To identify common signaling abnormalities, we profiled mRNA, demonstrating misexpression of MYCN in the majority of human MB and negligible expression in normal cerebella. We clarified a role in pathogenesis by targeting MYCN (and luciferase) to cerebella of transgenic mice. MYCN-driven MB showed either classic or LCA pathologies, with Shh signaling activated in approximately 5% of tumors, demonstrating that MYCN can drive MB independently of Shh. MB arose at high penetrance, consistent with a role for MYCN in initiation. Tumor burden correlated with bioluminescence, with rare metastatic spread to the leptomeninges, suggesting roles for MYCN in both progression and metastasis. Transient pharmacological down-regulation of MYCN led to both clearance and senescence of tumor cells, and improved survival. Targeted expression of MYCN thus contributes to initiation, progression, and maintenance of MB, suggesting a central role for MYCN in pathogenesis.

Targeting brain cancer: advances in the molecular pathology of malignant glioma and medulloblastoma

Malignant brain tumours continue to be the cause of a disproportionate level of morbidity and mortality across a wide range of individuals. The most common variants in the adult and paediatric populations - malignant glioma and medulloblastoma, respectively - have been the subject of increasingly intensive research over the past two decades that has led to considerable advances in the understanding of their basic biology and pathogenesis. This Review summarizes these developments in the context of the evolving notion of molecular pathology and discusses the implications that this work has on the design of new treatment regimens.

Large cell/anaplastic medulloblastoma: outcome according to myc status, histopathological, and clinical risk factors

PURPOSE

To evaluate the prognostic impact of large cell/anaplastic (LC/A) histology together with molecular and clinical risk factors in childhood medulloblastoma.

METHODS

Three consecutive prospective medulloblastoma trials were screened for patients with the histological diagnosis of LC/A medulloblastoma. Tumors were considered as LC/A if they displayed areas of severe cytological anaplasia or a significant or predominant large cell component. Histology was centrally confirmed. Genomic DNA amplification of c-myc and n-myc, and mRNA expression of c-myc and trkC were analyzed.

RESULTS

Twenty-eight patients with LC/A medulloblastoma with a median age of 6.1 years (1.4-16.5 years) and a median follow-up of 4.5 years were identified (5% of all medulloblastoma). Four-year event-free (EFS) and overall survival (OS) were 58% and 67%. Young age and metastases (n = 13, 4-year EFS 31% vs. 82% in 15 children >4 years and without metastases, P = 0.001), large cell histology (n = 9, 4-year EFS 22% vs. 75%, P = 0.005) and c-myc amplification (n = 9, 4-year EFS 22% vs. 89%, P < 0.0001) were negative prognostic factors. C-myc amplification was highly correlated with young age (P < 0.001), metastases (P = 0.002) and large cell histology (P = 0.007). Outcome of 12 patients with severely anaplastic tumors without these risk factors was not impaired (4-year EFS 86%).

CONCLUSION

In a subgroup of patients without clinical and molecular risk factors outcome was favorable despite severely anaplastic histology. In contrast, c-myc amplification and large-cell histology were associated with an inferior outcome. Intensified treatment strategies should be considered for children with LC/A medulloblastoma and these characteristics.

Universal poor survival in children with medulloblastoma harboring somatic TP53 mutations

PURPOSE

Medulloblastoma is the prototype of treatment success in modern pediatric neuro-oncology. Unfortunately, 20% to 30% of tumors recur despite maximal resection and multimodal therapy. Multiple biologic prognostic markers have been investigated to predict recurrences, but controversy remains regarding their clinical utility. Because p53 immunopositivity is an adverse prognostic marker in pediatric medulloblastoma and TP53 mutations are associated with chemotherapy and radiation therapy resistance, we aimed to determine the extent and role of TP53 mutations in pediatric medulloblastoma treatment failure.

PATIENTS AND METHODS

One hundred eight of 111 consecutive patients diagnosed with medulloblastoma in our institution from 1995 to 2007 were included. Median follow-up time was 5.3 years in survivors. All samples were immunostained for p53 and erbB-2. Histologic grade and immunostaining were scored by two blinded reviewers. For 49 patients, frozen material was available for TP53 sequencing. The main outcome measures were overall and progression-free survival.

RESULTS

Sixteen percent of sequenced medulloblastomas harbored a TP53 mutation. As a screening test, p53 immunohistochemistry was 100% sensitive and 83% specific for a TP53 mutation. Strikingly, all mutated tumors recurred early, and 5-year survival for average-risk patients was 0% for TP53-mutated medulloblastoma compared with 74% +/- 8% for wild-type medulloblastoma (P < .0001). Furthermore, 75% of recurrences in average-risk patients were associated with TP53 mutations. On multivariate analysis, TP53 mutation status was the strongest adverse prognostic factor (hazard ratio = 10.4, P = .003).

CONCLUSION

Lack of long-term survival in TP53-mutated medulloblastomas highlights the role of TP53 mutations in medulloblastoma resistance to conventional therapies and the need for alternative treatments, and prospective validation of these findings is needed.