Primary Pediatric Brain Tumors Research Articles

Abstract B27: Toxicity of convection-enhanced delivery with doxorubicin to treat pediatric brain-tumors depends on anatomical location

Abstract Introduction and Aim: Diffuse Intrinsic Pontine Glioma (DIPG) and pediatric High Grade Glioma (pHGG) are primary pediatric brain tumors that have a very high mortality and morbidity. Especially tumors that are not (DIPG) or only partially (midline pHGG) eligible for surgical resection have a very poor prognosis. Systemic chemotherapy regimens have failed to deliver satisfactory results but convection enhanced delivery (CED) is a promising technique that delivers chemotherapeutics directly to the tumor. Determining the best agent to deliver via CED is a challenge. Doxorubicin has shown to be highly effective when delivered via CED in preclinical glioma models, and against pHGG and DIPG cells in vitro. Liposomal doxorubicin is thought to improve distribution, bio-availability and subsequent efficacy of CED in glioma models. This preclinical study aims to determine the feasibility of performing CED with free doxorubicin or pegylated liposomal doxorubicin (PLD) in the brainstem and thalamus, and to study the efficacy of PLD and free doxorubicin when treating preclinical DIPG and pHGG models. Methods: Preclinical CED was performed with 15μl doxorubicin in the brainstem and thalamus of 6-week-old nude mice. Maximal tolerated dose was determined by treating mice with doxorubicin concentrations ranging from 2 mg/ml to 0.02 mg/ml. The efficacy study was performed with the highest possible dose and using the orthotopic diffusely growing E98-FM-DIPG model in the brainstem. Mice (n=12) were treated at day 9 after injection of cells. Follow-up consisted of BLI measurements, and determination of body weight and clinical symptoms. Results: Maximal tolerated dose was 0.02 mg/ml in the brainstem and 0.2 mg/ml in the thalamus for both free doxorubicin and PLD. Clinical toxicity after CED with higher concentrations consisted of weight loss and neurological deficits including paresis and loss of balance. Symptoms occurred after three (free doxorubicin) or six days (PLD). E98FM-DIPG bearing mice treated with 0.02 mg/ml of free doxorubicin, or PL-doxorubicin via CED did not show any survival benefit compared to vehicle treated animals. 0.2 mg/ml has previously shown to be effective in treating preclinical glioma models. Conclusions: Local drug delivery of concentrations that are safe in the thalamus show severe toxicity when delivered to the brainstem. No therapeutic window existed for treating orthotopic brainstem tumors in mice. However, therapeutic concentrations could be reached in the thalamus. This data suggest that anatomical location of the tumor is of vital importance when considering the best drugs to deliver via CED. Citation Format: A. Charlotte P. Sewing, Susanna J.E. Veringa, Tonny Lagerweij, David P. Noske, Dannis G. van Vuurden, Gertjan J.L. Kaspers, Esther Hulleman. Toxicity of convection-enhanced delivery with doxorubicin to treat pediatric brain-tumors depends on anatomical location. [abstract]. In: Proceedings of the AACR Special Conference: Advances in Brain Cancer Research; May 27-30, 2015; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2015;75(23 Suppl):Abstract nr B27.

Short-term mortality following surgical procedures for the diagnosis of pediatric brain tumors: outcome analysis in 5533 children from SEER, 2004-2011.

OBJECT Thirty-day mortality is increasingly a reference metric regarding surgical outcomes. Recent data estimate a 30-day mortality rate of 1.4-2.7% after craniotomy for tumors in children. No detailed analysis of short-term mortality following a diagnostic neurosurgical procedure (e.g., resection or tissue biopsy) for tumor in the US pediatric population has been conducted. METHODS The Surveillance, Epidemiology and End Results (SEER) data sets identified patients ≤ 21 years who underwent a diagnostic neurosurgical procedure for primary intracranial tumor from 2004 to 2011. One- and two-month mortality was estimated. Standard statistical methods estimated associations between independent variables and mortality. RESULTS A total of 5533 patients met criteria for inclusion. Death occurred within the calendar month of surgery in 64 patients (1.16%) and by the conclusion of the calendar month following surgery in 95 patients (1.72%). Within the first calendar month, patients < 1 year of age (n = 318) had a risk of death of 5.66%, while those from 1 to 21 years (n = 5215) had a risk of 0.88% (p < 0.0001). By the end of the calendar month following surgery, patients < 1 year (n = 318) had a risk of death of 7.23%, while those from 1 to 21 years (n = 5215) had a risk of 1.38% (p < 0.0001). Children < 1 year at diagnosis were more likely to harbor a high-grade lesion than older children (OR 1.9, 95% CI 1.5-2.4). CONCLUSIONS In the SEER data sets, the risk of death within 30 days of a diagnostic neurosurgical procedure for a primary pediatric brain tumor is between 1.16% and 1.72%, consistent with contemporary data from European populations. The risk of mortality in infants is considerably higher, between 5.66% and 7.23%, and they harbor more aggressive lesions.

Contrast Leakage Patterns from Dynamic Susceptibility Contrast Perfusion MRI in the Grading of Primary Pediatric Brain Tumors.

The pattern of contrast leakage from DSC tissue signal intensity time curves have shown utility in distinguishing adult brain neoplasms, but has limited description in the literature for pediatric brain tumors. The purpose of this study is to evaluate the utility of grading pediatric brain tumors with this technique. A retrospective review of tissue signal-intensity time curves from 63 pediatric brain tumors with preoperative DSC perfusion MR imaging was performed independently by 2 neuroradiologists. Tissue signal-intensity time curves were generated from ROIs placed in the highest perceived tumor relative CBV. The postbolus portion of the curve was independently classified as returning to baseline, continuing above baseline (T1-dominant contrast leakage), or failing to return to baseline (T2*-dominant contrast leakage). Interobserver agreement of curve classification was evaluated by using the Cohen κ. A consensus classification of curve type was obtained in discrepant cases, and the consensus classification was compared with tumor histology and World Health Organization grade. Tissue signal-intensity time curve classification concordance was 0.69 (95% CI, 0.54-0.84) overall and 0.79 (95% CI, 0.59-0.91) for a T1-dominant contrast leakage pattern. Twenty-five of 25 tumors with consensus T1-dominant contrast leakage were low-grade (positive predictive value, 1.0; 95% CI, 0.83-1.00). By comparison, tumors with consensus T2*-dominant contrast leakage or return to baseline were predominantly high-grade (10/15 and 15/23, respectively) with a high negative predictive value (1.0; 95% CI, 0.83-1.0). For pilomyxoid or pilocytic astrocytomas, a T1-dominant leak demonstrated high sensitivity (0.91; 95% CI, 0.70-0.98) and specificity (0.90, 95% CI, 0.75-0.97). There was good interobserver agreement in the classification of DSC perfusion tissue signal-intensity time curves for pediatric brain tumors, particularly for T1-dominant leakage. Among patients with pediatric brain tumors, a T1-dominant leakage pattern is highly specific for a low-grade tumor and demonstrates high sensitivity and specificity for pilocytic or pilomyxoid astrocytomas.

Molecular Subgrouping of Medulloblastoma: Impact Upon Research and Clinical Practice.

Medulloblastoma, the most common primary pediatric malignant brain tumor is a molecularly heterogeneous disease with different developmental origins, distinct phenotypes, diverse biological behaviour, and contrasting clinical outcomes. The current clinico-radiological risk-classification fails to take account of this heterogeneity and existent prognostic variability. It is widely accepted that dysregulation of normal developmental processes constitute a key mechanism of tumorigenesis in at least a subset of medulloblastomas. Several attempts at biological classification have successfully identified distinct subgroups with subgroup-specific gene signatures, demographics, histologic subtypes, and rates of metastases. Several research groups have classified medulloblastoma into molecular subgroups using a variety of different genomic approaches and platforms such as gene expression profiling, microRNA profiling and methylation arrays. Recently, a consensus has emerged that classifies medulloblastoma into four distinct molecular subgroups named as wingless (WNT), sonic hedgehog (SHH), Group 3 and Group 4 respectively. However, such integrative approaches have limited applicability in the clinic due to the need of fresh-frozen tissues and elaborate molecular biology tools. In parallel, some groups have proposed and validated traditional antibody-based approaches using immunohistochemistry on archival specimen for rapid and reliable molecular subgrouping to be applied in any basic neuropathology laboratory. Heterogeneity within each of these four consensus subgroups has also been demonstrated that needs to be considered in the design of future clinical trials. There is a compelling need to integrate molecular biomarkers with clinico-pathologic outcome indicators to refine risk-stratification as well as develop novel molecularly targeted agents for optimizing therapeutic index and personalizing therapy.

PM-01 * NEURAL DERIVATIVES FROM HUMAN EMBRYONIC STEM CELLS: A CELLULAR SYSTEM TO STUDY THE ROLE OF Otx2 IN MEDULLOBLASTOMA PROGRESSION

Medulloblastoma (MB) is the most common malignant primary pediatric brain tumor and is currently divided into 4 subtypes based on different genomic alterations, gene expression profiles and response to treatment: Wnt, Sonic Hedgehog (Shh), Group 3 and Group 4. This extensive heterogeneity has made it difficult to assess the functional relevance of genes to malignant progression. For example, expression of the transcription factor, Orthodenticle homeobox2 (Otx2) is frequently dysregulated in multiple MB variants; however, its role may be subtype-specific. We recently demonstrated that neural precursors derived from transformed human embryonic stem cells (trans-hENs), but not their normal counterparts (hENs), resemble Groups 3 and 4 MB in vitro and in vivo. These trans-hENs have >12-fold overexpression of Otx2. Here, we tested the utility of this model system as a means of dissecting the role of Otx2 in MB using gain and loss of function studies in hENs and trans-hENs respectively. Parallel experiments with MB cells revealed that Otx2 exerts tumor suppressive effects in hEN and Shh MB cells, likely by regulating self-renewal and decreasing expression of pluripotent genes such as Sox2, Lin28A, Oct4 and Nanog. Concomitant to the negative regulation of hESC genes, we observed a decrease in levels of the active histone mark, H3K4me3 at promoter loci of pluripotent genes as well as an increase in Otx2 recruitment at the Sox2 promoter by chromatin immunoprecipitation assays. This was supported by overexpression of Sox2 in Otx2+ Shh MB and hENs that resulted in significant rescue of self-renewal and cell migration. In contrast, Otx2 is oncogenic and promotes self-renewal of trans-hENs and Groups 3/4 MB independent of pluripotent genes. These results demonstrate a cell context-dependent function of Otx2. Our study underscores the value of hESC derivatives as developmental models of MB and for investigating key biological questions related to embryonal childhood cancers.

OTX2 exhibits cell-context-dependent effects on cellular and molecular properties of human embryonic neural precursors and medulloblastoma cells.

ABSTRACTMedulloblastoma (MB) is the most common malignant primary pediatric brain tumor and is currently divided into four subtypes based on different genomic alterations, gene expression profiles and response to treatment: WNT, Sonic Hedgehog (SHH), Group 3 and Group 4. This extensive heterogeneity has made it difficult to assess the functional relevance of genes to malignant progression. For example, expression of the transcription factor Orthodenticle homeobox2 (OTX2) is frequently dysregulated in multiple MB variants; however, its role may be subtype specific. We recently demonstrated that neural precursors derived from transformed human embryonic stem cells (trans-hENs), but not their normal counterparts (hENs), resemble Groups 3 and 4 MB in vitro and in vivo. Here, we tested the utility of this model system as a means of dissecting the role of OTX2 in MB using gain- and loss-of-function studies in hENs and trans-hENs, respectively. Parallel experiments with MB cells revealed that OTX2 exerts inhibitory effects on hEN and SHH MB cells by regulating growth, self-renewal and migration in vitro and tumor growth in vivo. This was accompanied by decreased expression of pluripotent genes, such as SOX2, and was supported by overexpression of SOX2 in OTX2+ SHH MB and hENs that resulted in significant rescue of self-renewal and cell migration. By contrast, OTX2 is oncogenic and promotes self-renewal of trans-hENs and Groups 3 and 4 MB independent of pluripotent gene expression. Our results demonstrate a novel role for OTX2 in self-renewal and migration of hENs and MB cells and reveal a cell-context-dependent link between OTX2 and pluripotent genes. Our study underscores the value of human embryonic stem cell derivatives as alternatives to cell lines and heterogeneous patient samples for investigating the contribution of key developmental regulators to MB progression.

Outcome of supratentorial intraaxial extra ventricular primary pediatric brain tumors: A prospective study.

Introduction:Tumors of the central nervous system (CNS) are the second most frequent malignancy of childhood and the most common solid tumor in this age group. CNS tumors represent approximately 17% of all malignancies in the pediatric age range, including adolescents. Glial neoplasms in children account for up to 60% of supratentorial intraaxial tumors. Their histological distribution and prognostic features differ from that of adults.Aims and Objectives:To study clinical and pathological characteristics, and to analyze the outcome using the Engel's classification for seizures, Karnofsky's score during the available follow-up period of minimum 1 year following the surgical and adjuvant therapy of supratentorial intraaxial extraventricular primary pediatric (SIEPP) brain tumors in children equal or less than 18 years.Materials and Methods:The study design is a prospective study done in NIMS from October 2008 to January 2012. All the patients less than 18 years of age operated for SIEPP brain tumors proven histopathologically were included in the study. All the patients with recurrent or residual primary tumors or secondaries were excluded from the study. Post operative CT or magnetic resonance imaging (MRI) is done following surgery.Results and Analysis:There were 2, 8 and 20 patients in the age range of 0-2 years, >2-10 years and 10-18 years, respectively. There were 21 male patients and 9 female patients. Out of 30 patients, 16 had lesion in the temporal lobe, 6 in frontal lobe, 4 in thalamus, 3 in parietal lobe and 1 in occipital lobe. Out of 30 patients, 11 patients had malignant lesions and nineteen patients had benign lesions. Gross total excision could be achieved in 19 patients and subtotal in 11 patients. Seven patients had mortality and four of the remaining 23 patients had increased deficits postoperatively. Remaining 19 patients either improved or remained same.Conclusions:SIEPP brain tumors have male preponderance, occur in 95% of patients in the age range of 7-18 years and have temporal lobe as the most common site of origin. The seizure presentation has good outcome compared to raised intracranial pressure features. The seizure control is quite good irrespective of subtotal or gross total excision in temporal lobe low grade tumors. All PNETs have survival of less than 1 year even with adjuvant chemo and radiotherapy.

Treatment Options for Medulloblastoma and CNS Primitive Neuroectodermal Tumor (PNET)

Medulloblastoma and central nervous system (CNS) primitive neuroectodermal tumor (PNET) are primary pediatric brain tumors that require multidisciplinary therapies. Although often treated similarly in clinical trials, they are biologically different diseases. Even within medulloblastomas and CNS PNETs, there are molecularly distinct subgroups with differing presentations and prognoses. Overall, prognosis is better for medulloblastomas. Specific treatments for these types of cancer are continuously evolving to maximize survival and minimize long-term sequelae of treatment. Patients should be treated on a clinical trial, if eligible, as they may gain benefit with minimal risk over current standard of care. The amount of residual disease after surgery better correlates with survival for medulloblastomas than for CNS PNETs. Maximal surgical resection of tumor should be done, only if additional permanent, neurologic deficits can be spared. Patients should have a staging work-up to assess the extent of disease. This includes postoperative magnetic resonance imaging (MRI) of the brain, MRI of the entire spine and lumbar cerebrospinal fluid (CSF) sampling for cytological examination, if deemed safe. Radiation therapy to the entire CNS axis is required, with a greater dose (boost) given to the region of the primary site or any bulky residual disease for older children. Adjuvant chemotherapy must be given even if no evidence of disease after radiation therapy exists, as the risk of relapse is substantial after radiation alone. Subsets of younger children with medulloblastoma, arbitrarily defined as those younger than 3years of age in some studies and 4 or even 5years in other studies, can be effectively treated with chemotherapy alone. Recent genomic studies have revealed further subtypes of disease than previously recognized. Clinical trials to exploit these biologic differences are required to assess potential efficacy of targeted agents. The treatment of medulloblastoma and CNS PNET can cause significant impairment in neurologic function. Evaluations by physical therapy, occupational therapy, speech therapy and neurocognitive assessments should be obtained, as needed. After therapy is completed, survivors need follow-up of endocrine function, surveillance scans and psychosocial support.

Deconstruction of Medulloblastoma Cellular Heterogeneity Reveals Differences between the Most Highly Invasive and Self-Renewing Phenotypes

Medulloblastoma (MB) is the most common malignant primary pediatric brain tumor. Major research efforts have focused on characterizing and targeting putative brain tumor stem or propagating cell populations from the tumor mass. However, less is known about the relationship between these cells and highly invasive MB cells that evade current therapies. Here, we dissected MB cellular heterogeneity and directly compared invasion and self-renewal. Analysis of higher versus lower self-renewing tumor spheres and stationary versus migrating adherent MB cells revealed differential expression of the cell surface markers CD271 [p75 neurotrophin receptor (p75NTR)] and CD133. Cell sorting demonstrated that CD271 selects for subpopulations with a higher capacity for self-renewal, whereas CD133 selects for cells exhibiting increased invasion in vitro. CD271 expression is higher in human fetal cerebellum and primary samples of the Shh MB molecular variant and lower in the more aggressive, invasive group 3 and 4 subgroups. Global gene expression analysis of higher versus lower self-renewing MB tumor spheres revealed down-regulation of a cell movement transcription program in the higher self-renewing state and a novel potential role for axon guidance signaling in MB-propagating cells. We have identified a cell surface signature based on CD133/CD271 expression that selects for MB cells with a higher self-renewal potential or invasive capacity in vitro. Our study underscores a previously unappreciated role for CD271 in selecting for MB cell phenotypes and suggests that successful treatment of pediatric brain tumors requires concomitant targeting of a spectrum of transitioning self-renewing and highly infiltrative cell subpopulations.

Abstract 5361: Enriching and characterizing cancer stem cell grown on collagen type IV-coated plate in primary pediatric brain tumors

Abstract There is accumulating evidence that cancer stem cells (CSC) in adherent culture maintain and enrich their characteristics by extracellular matrix (ECM). This study focused on differential expression of not only CSC markers and differentiation markers, but also embryonic signaling pathways when cultured on various ECM-coated plates. Four cells from pediatric patients with brain tumor were grown in DMEM/F12 medium supplemented with 10ng/ml FGF, bFGF and 0.5x B-27. After forming of neurosphere, the cells were cultivated on each three kinds of ECM-coated plate including collagen type IV, fibronectin and poly-D-lysine. And the expression level of CD133, CD15, Nestin, Oct3/4, SOX2 as CSC markers, GFAP, β-tubuliln III for differentiation markers, Wnt, Notch, Shh, their transcription factors like β-catenin, Hes1, Gli1 respectively for embryonic signaling pathways was assessed by reverse transcriptase (RT)-PCR. As a result, two among four brain tumor cells grown on collagen type IV-coated plate expressed higher expression level of CD133, CD15, Nestin, SOX2, Oct3/4, Wnt5a and Notch than in the cells cultured on fibronectin or poly-D-lysine-coated plate. And residual two cells cultivated on collagen type IV and fibronectin, not on poly-D-lysine were shown similar expression level of almost all genes. There is no difference of Shh, Gli1, GFAP and β-tubuliln III expressions in all cells grown on each of three ECM-coated plates. In conclusion, collagen type IV is required for enriching and maintaining of CSC characteristics in primary pediatric brain tumors. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5361. doi:1538-7445.AM2012-5361

Hydrocephalus with brain tumors in children

Tumor-associated hydrocephalus is common in primary pediatric brain tumors. The managements involve radical tumor resection, temporary external ventricular drainage, and different definite shunting procedures. The purpose of this study is to sum up our experience of definite shunting procedures for tumoral hydrocephalus in children and correlate with reported literatures. This is a retrospective review of a series of 1,250 cases of primary pediatric brain tumors in patients <18years of age collected in Taipei Veterans General Hospital from 1971 to 2008. Cases with questionable records about hydrocephalus were excluded. A total of 56.7% of cases presented hydrocephalus, including hydrocephalus that occurred at tumor diagnosis (51.5%), and hydrocephalus developed after tumor diagnosis (5.1%). At tumor diagnosis, the hydrocephalus was mainly obstructive type (98%) and rarely communicating type (1.9%). Definite shunting procedures in this series comprised of ventriculoperitoneal (VP) shunt in 54.4%, endoscopic third ventriculostomy (ETV) in 10.9%, subduroperitoneal (SP) shunt in 4.8%, septostomy in 0.7%, lumboperitoneal shunt in 0.6%, and ventriculoatrial shunt in 0.1% of patients with hydrocephalus. There was a tendency of decreasing requirement and changing timing for VP shunt implantation. There was a gradual increase in usage of ETV for hydrocephalus in specific types and locations of tumors. In the past two decades, we tended to use the VP shunt more cautiously for obstructive tumoral hydrocephalus. We try to perform initial radical resection of tumors as indicated and the more frequent use of ETV in selective cases that help to decrease the requirement of VP shunt implantation.

Abstract 3461: A chemical screen for the identification of novel therapeutics for pediatric brain tumors

Abstract Treatment of brain tumors in children has greatly improved over the past decades, but current treatment protocols lack specificity, killing not only tumor cells, but also “healthy” normal brain cells. Moreover, current therapy still fails in approximately 20% of medulloblastoma patients, 50% of ependymomas and 80% of children suffering from high grade glioma. Treatment mostly consists of surgery, followed by chemotherapy and radiotherapy, and although this kind of therapy is among the most effective treatment options available, it is not sufficient. Therefore, new therapeutic drugs are required that specifically kill brain tumor cells and/or sensitize to irradiation, sparing normal brain tissue. In order to identify such novel compounds, drug screens were set up in a semi-high throughput format, using Gaussia luciferase (Gluc) activity as cell viability readout. As opposed to other forms of luciferase, Gluc is secreted in the medium, allowing the measurement of luciferase activity without lysing the cells. Since the Gluc signal has been shown to be linearly related to cell number, this assay can be used to determine cell viability at different points after drug treatment. In addition, an Acumen eX3 laser scanning cytometer was used in parallel, to determine cell number and cytometric parameters. We screened two small molecule libraries (2960 compounds) for cell growth inhibitory or radiosensitizing properties on pediatric high-grade glioma, ependymoma and medulloblastoma cell lines and primary patient material. Cells were incubated with a concentration of 1µM of the different compounds, either as single agent or in combination with 3 Gray irradiation, and cell viability was determined over a period of 4 days of incubation. A reduction of &amp;gt;75% of cell growth was considered to be significant. In general, 4 different groups of small molecules could be distinguished: 1) compounds that did not affect cell proliferation compared to controls, 2) compounds that block cell cycle progression, 3) compounds that induce cell death independently of irradiation, and 4) radiosensitizers. A total of 114 compounds was identified that inhibited cell growth and/or sensitized towards irradiation. Among the compounds that induced cell death were microtubule inhibitors, alkylating agents, topoisomerase inhibitors and anthracyclins. Besides these known anti-cancer agents we also identified a large number of cardiotonic drugs, benzimidazoles and limonoids that effectively killed brain tumor cells. We are currently investigating these hits and expanding our drug screens with additional primary pediatric brain tumor cells. In addition, we are repeating the screens on non neoplastic primary human cells, including astrocytes, to assess the therapeutic index of these drugs. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3461. doi:10.1158/1538-7445.AM2011-3461

Molecular biology of medulloblastoma: bridging the gap between research and practice

Evaluation of: Northcott PA, Korshunov A, Witt H et al. Medulloblastoma comprises four distinct molecular variants. J. Clin. Oncol. DOI: 10.1200/JCO.2009.27.4324 (2010) (Epub ahead of print).Medulloblastoma, the most common primary pediatric malignant brain tumor, is a molecularly heterogeneous disease with different developmental origins, distinct phenotypes, diverse biological behavior and contrasting clinical outcomes. The current clinico-radiological risk classification fails to take account of this heterogeneity and resultant prognostic variability. It is widely accepted that dysregulation of normal developmental processes constitutes a key mechanism of tumorigenesis in at least a subset of medulloblastomas. Several attempts at biological classification have successfully identified distinct subgroups with subgroup-specific gene signatures, demographics, histologic subtypes and metastases; among these, tumors involving the wingless and sonic hedgehog signaling pathways have been the most reliably and consistently identified. However, such integrative genomic approaches have limited applicability in the clinic owing to the need for fresh frozen tissues and elaborate molecular biology tools. A novel four-antibody approach to subgroup medulloblastoma using immunohistochemistry on archival specimens as proposed by Northcott et al. appears extremely promising as it can be applied in any basic neuropathology laboratory across the globe. There is a compelling need to integrate assays of molecular biomarkers performed on archival specimens into stratification schemes for medulloblastoma alongside clinical and pathologic outcome indicators to refine risk stratification for individualizing therapy.

Spectrum of pediatric brain tumors in India: A multi-institutional study

Till date there is no published multi-institutional data regarding the epidemiological profile of pediatric brain tumors in India. The present retrospective study analyses the histological spectrum of pediatric age group brain tumors in seven tertiary care hospitals in India. Data regarding frequencies of various primary brain tumors (diagnosed according to the World Health Organization (WHO) classification), in 3936 pediatric patients (<18 yrs of age), was collected from seven tertiary care hospitals in India. The most common primary pediatric brain tumors were astrocytic tumors (34.7%), followed by medulloblastoma and supratentorial primitive neuro-ectodermal tumors (22.4%), craniopharyngiomas (10.2%) and ependymal tumors (9.8%). The most common astrocytic tumor was pilocytic astrocytoma. In comparison to adults, oligodendrogliomas and lymphomas were rare in children. Our study is the first such report on the histological spectrum of brain tumors in children in India. Except for a slightly higher frequency of craniopharyngiomas, the histological profile of pediatric brain tumors in India is similar to that reported in the Western literature.

Inhibition of Aurora Kinase A enhances chemosensitivity of medulloblastoma cell lines

Medulloblastoma comprises approximately 20% of all primary pediatric brain tumors. Despite recent advances, the survival rate for high-risk patients and the morbidity associated with these treatments remains suboptimal. To improve outcomes and decrease morbidity, more targeted therapy is required. One possible target is the Aurora Kinase family. The objective of this study was to evaluate the impact of Aurora Kinase A inhibition in medulloblastoma cell lines. Cell proliferation was measured using an MTS assay after adding an Aurora Kinase inhibitor (C1368) at different concentrations. Cell cycle analysis was carried out by Flow Cytometry using propidium iodide (PI). RNAi experiments were performed using siRNA oligonucleotides. Luciferase experiments were carried out using the Cignal Finder 10 Pathway Reporter Arrays. Inhibition of Aurora Kinase A induces cell death in medulloblastoma cells and lowers the IC(50) of other chemotherapeutic agents (etoposide and cisplatin) used in medulloblastoma treatment. Cell arrest at G2/M phase was significantly increased in medulloblastoma cell lines treated with C1368 Sigma at IC(30) or transfected siRNA. Inhibition of Aurora Kinase A resulted in decreased activity of pro-proliferative signaling pathways including Wnt, Myc, and RB as measured by luciferase reporter assays. These data indicate that inhibition of Aurora Kinase A inhibits cell growth in medulloblastoma through inhibition of pro-proliferative signaling pathways Wnt, Myc, and RB. Additionally, combining Aurora Kinase A inhibition with other chemotherapeutic agents significantly lowers their IC(50), which make it a promising small molecule target for medulloblastoma therapy.

Pediatric Central Nervous System Germ Cell Tumors: A Review

Central nervous system (CNS) germ cell tumors (GCTs) represent approximately 3% of primary pediatric brain tumors and encompass a wide pathologic spectrum. CNS GCTs are most commonly located in the pineal and suprasellar regions of the brain and can be divided into major groups including germinomas and nongerminomatous GCTs (NGGCTs), with teratomas often considered a separate category. The clinical presentation varies by location and size, and it frequently includes endocrine abnormalities, visual changes, and signs of increased intracranial pressure. Neuroimaging studies cannot differentiate GCTs from other tumors, and therefore, the diagnosis usually requires histologic confirmation. The rare exceptions are the cases where characteristic elevations of tumor markers, including alpha-fetoprotein and/or beta-human chorionic gonadotropin are documented in the serum and/or cerebrospinal fluid. In these cases, the imaging findings along with the tumor marker elevation may be diagnostic in themselves without the need for tissue confirmation. Treatment and prognosis differ greatly between groups. Germinomas have a superior prognosis than NGGCTs. Five-year overall survival rates >90% were reported initially with the use of craniospinal irradiation. More recently, the use of chemotherapy in addition to radiation therapy has afforded the ability to decrease the dose and volume of radiation therapy without affecting survival rates. NGGCTs are less radiosensitive than germinomas, but the use of adjuvant chemotherapy has improved survival rates in this group as well. The standard management for CNS GCTs remains controversial. Treatment regimens aimed to improve progression-free and overall survival times are ongoing.

942. Adenoviral Mediated Re-Expression of Wnt Antagonist Dkk-1 Induces Apoptosis and Suppresses Tumor Growth in Medulloblastoma

Medulloblastoma comprises approximately 20% of all primary pediatric brain tumors. Advances in treatment with surgery, radiation and chemotherapy have resulted in a five-year survival rate of approximately 70% over the last 20 years. Unfortunately children less than 3 years of age continue to have significantly worse outcomes. Most importantly, the morbidity associated with these treatments can be devastating given their lack of specificity. To elucidate signaling pathways for potential directed therapy we sought to identify putative tumor suppressor genes down regulated by epigenetic mechanisms. Inappropriate epigenetic gene silencing results in the loss of critical regulators of proliferation and apoptotic pathways. We hypothesized that viral mediated re-expression of such epigenetically silenced tumor suppressor genes would result in suppression of tumor growth. A survey of epigenetically silenced genes identified the antagonist Dickkopf 1(Dkk1) as down-regulated medulloblastoma cell lines and in medulloblastoma patient samples; Dkk1 expression could be re-induced by histone de-acetylaseh inhibition. Importantly, re-expression of Dkk1via vector-mediated gene transfer caused medulloblastoma cell apoptosis and inhibited tumor formation in vitro as measured by colony formation on soft agar. Taken together our data implicate Wnt signaling as an important regulator of medulloblastoma pathogenesis, and suggest that re- introduction of Dkk1 may provide for therapeutic benefit in medulloblastoma patients.

Primary pediatric brain tumors

The purpose of the current study was to investigate a hospital series of 986 cases of primary pediatric brain tumors in Taiwan. The authors reviewed the database of primary pediatric brain tumors in patients < 18 years of age collected in Taipei Veterans General Hospital (Taipei VGH) from 1975 to May 2004. Age and gender distribution, location, and classification of brain tumors were analyzed. Intracranial tumors with diagnostic imaging were included. Nontumoral lesions, cysts, and vascular malformations were excluded. The mean age of these 986 patients was 7.8 years, and the male to female ratio was 1.4:1. Supratentorial (including pineal-quadrigeminal) located tumors (58.3%) was predominant to infratentorial tumors (41.1%). In these series, 886 patients had either histologic diagnosis (842 patients) or clinical diagnosis (44 patients). The most common 5 categories of tumors were astrocytic tumors (31.1%), germ cell tumors (14.0%), medulloblastomas (13.3%), craniopharyngiomas (8.3%), and ependymal tumors (5.8%). Atypical teratoid/rhabdoid tumors (AT/RTs), a rare but highly malignant tumor, were 2.1%. The high incidence of primary intracranial germ cell tumors correlated with reported series from Japan and Korea. For the remaining 100 patients without diagnostic classifications, the majority were most likely astrocytic tumors in brain stem. The authors analyzed a large hospital series of primary brain tumors in children. Both histologically verified and unverified tumors were recruited to avoid selective bias. Although it was not a study of a population-based brain tumor registry, it could still be representative of primary pediatric brain tumors in Taiwan.

Prenatal vitamin supplementation and pediatric brain tumors: huge international variation in use and possible reduction in risk.

An international case-control study of primary pediatric brain tumors included interviews with mothers of cases diagnosed from 1976-1994 and mothers of population controls. Data are available on maternal vitamin use during pregnancy for 1051 cases and for 1919 controls in eight geographic areas of North America, Europe and Israel. While risk estimates varied by study center, combined results suggest that maternal supplementation for two trimesters may decrease risk of brain tumor [odds ratio (OR)=0.7; 95% confidence interval (CI)=0.5-0.9], with a trend toward less risk with longer duration of use (P trend= 0.0007). The greatest risk reduction was among children diagnosed under 5 years of age whose mothers used supplements during all three trimesters (OR=0.5; CI=0.3- 0.8). This effect did not vary by histology and was seen for supplementation during pregnancy rather than during the month before pregnancy or while breast feeding. These findings are largely driven by data from the US, where most mothers took vitamins. The proportion of control mothers who took vitamins during pregnancy varied tremendously, from 3% in Israel and in France through 21% in Italy, 33% in Canada, 52% in Spain to 86-92% at the three US centers. The composition of the various multivitamin compounds taken also varied: daily dose of vitamin C ranged from 0 up to 600 mg; vitamin E from 0 to 70 mg; vitamin A from 0 to 30,000 IU and folate from 0 to 2000 mg. Mothers also took individual micronutrient supplements (e.g., vitamin C tablets), but most mothers who took these also took multivitamins, making it impossible to determine potential independent effects of these micronutrients.

The Use of the Laitinen Stereoadapter for Three-Dimensional Conformal Stereotactic Radiotherapy

3-D conformal therapy is used to treat a variety of tumors by delivering a high dose to the target volume while minimizing dose to surrounding tissue. Conventional irradiation of intracranial lesions involves treating substantial portions of healthy brain. Stereotactic radiosurgery (SRS) delivers a single fraction to a small lesion targeted by an invasive head frame. The Laitinen stereoadapter is a noninvasive localization/immobilization device that provides the precision of stereotactic techniques (within 2 mm) with the radiobiologic advantage of fractionation. This report describes the Northwestern experience of 3-D conformal Stereotactic radiotherapy (SRT) for intracranial lesions using the Laitinen Stereoadapter for reproducible, noninvasive immobilization. 17 patients with 18 isocenters were treated with SRT via noncoplanar, static, and/or rotational beams. Patient age ranged from 3 to 77. Total doses ranged from 1000 to 5580 cGy at 180 to 400 cGy per fraction. Histologies included primitive neuroectodermal tumor (PNET), recurrent medulloblastoma, mixed germ cell tumor, recurrent juvenile pilocytic astrocytoma, optic glioma, oligodendroglioma, cran-iopharyngioma, meningioma, metastatic carcinoma, and one orbital rhabdomyosarcoma. Patient positioning was checked daily, and verification port films were taken every other day. Port films showed excellent reproducibility of isocenter placement with the Laitinen stereoadapter. Follow-up ranged from 1 to 24 months. Post-treatment radiographic responses were similar to those seen with conventional radiation therapy. The Laitinen stereoadapter is very well tolerated with minimal acute effects. Its use does not require excessive preplanning (i.e., customized oral appliances) and can accommodate any cranial size. Patients can initiate treatment within 24 hours, if necessary. The relocatable frame exploits the accuracy of SRS with the biological advantage of fractionation. We currently use the Laitinen for primary adult and pediatric brain tumors as well as metastatic lesions too large for SRS. Further studies are currently underway to further define its utility.