Diffuse brainstem gliomas in children: should we or shouldn't we biopsy?

Compassionate use of Quantum Magnetic Resonance Therapy for treatment of children with Diffuse Brainstem Glioma in Mexico City: a single institutional experience

PURPOSE

Diffuse Brainstem Glioma (DBG) is a catastrophic brain tumor with a survival rate of less than 10% two years after diagnosis despite the existence of different treatment protocols. Among the devices that use magnetic fields generated by Magnetic Resonance Imaging is Quantum Magnetic Resonance Therapy (QMRT).

METHODS

Five children diagnosed with DBG in our institution in Mexico City underwent treatment of compassionate use with QMRT between December 2018 and July 2019. A survival analysis was performed with previously reported historical data (n = 15).

RESULTS

Two patients (40%) survived after three years of follow-up; the log-rank test showed a statistically significant difference in overall survival between both groups (p = 0.032). All patients tolerated the treatment adequately without reporting any severe clinical or neuroradiological adverse effects. Of the patients included, all showed a decrease in the tumor one month after the end of the treatment, although there was great variability in the response and the difference was not statistically significant (p = 0.06).

CONCLUSIONS

Although future investigations are needed to confirm the findings reported in the present study, the improvement in survival is promising for a group of patients whose prognosis has been catastrophic over the years. Trial registration NCT03577600.

Safety and efficacy of brainstem biopsy in children and young adults

OBJECTIVE

Biopsies of brainstem lesions are performed to establish a diagnosis in the setting of an atypical clinical or radiological presentation, or to facilitate molecular studies. A better understanding of the safety and diagnostic yield of brainstem biopsies would help guide appropriate patient selection.

METHODS

All patients who underwent biopsy of a brainstem lesion during the period from January 2011 to June 2019 were reviewed. Demographic, radiological, surgical, and outcome data were collected.

RESULTS

A total of 58 patients underwent 65 brainstem biopsies during the study period. Overall, the median age was 7.6 years (IQR 3.9-14.2 years). Twenty-two of the 65 biopsies (34%) were open, 42 (65%) were stereotactic, and 1 was endoscopic. In 3 cases (5%), a ventriculoperitoneal shunt was placed, and in 9 cases (14%), a posterior fossa decompression was performed during the same operative session as the biopsy. An intraoperative MRI (iMRI) was performed in 28 cases (43%). In 3 of these cases (11%), the biopsy was off target and additional samples were obtained during the same procedure. New neurological deficits were noted in 5 cases (8%), including sensory deficits, ophthalmoparesis/nystagmus, facial weakness, and hearing loss; these deficits persisted in 2 cases and were transient in 3 cases. A pseudomeningocele occurred in 1 patient; no patients developed a CSF leak or infection. In 8 cases (13%) an additional procedure was needed to obtain a diagnosis.

CONCLUSIONS

Brainstem biopsies are safe and effective. Target selection and approach should be a collaborative effort. iMRI can be used to assess biopsy accuracy in real time, thereby allowing any adjustment if necessary.

Modulating autophagy as a therapeutic strategy for the treatment of paediatric high-grade glioma

Paediatric high-grade gliomas (pHGG) represent a therapeutically challenging group of tumors. Despite decades of research, there has been minimal improvement in treatment and the clinical prognosis remains poor. Autophagy, a highly conserved process for recycling metabolic substrates is upregulated in pHGG, promoting tumor progression and evading cell death. There is significant crosstalk between autophagy and a plethora of critical cellular pathways, many of which are dysregulated in pHGG. The following article will discuss our current understanding of autophagy signaling in pHGG and the potential modulation of this network as a therapeutic target.

Is biopsy safe in children with newly diagnosed diffuse intrinsic pontine glioma?

Diffuse intrinsic pontine gliomas (DIPGs), with a median survival of 9 months, represent the biggest therapeutic challenge in pediatric neuro-oncology. Despite many clinical trials, no major improvements in treatment have been made over the past 30 years. In most cases, biopsy is not needed for diagnosis because DIPG diagnosis is based on a typical clinical picture with radiologic evidence on magnetic resonance imaging. Therefore, little data on newly diagnosed DIPG have been published and are confounded by including autopsy (i.e., postradiation therapy) cases. In most cancers, advancing to cure has been linked to the discovery of relevant biomarkers, only found by access to tissue. Therefore, to further understand the biology of DIPG, fresh tissue samples must be obtained at diagnosis. However, most neurosurgical teams are reluctant to perform biopsy in pediatric patients, citing potential risks and lack of direct benefit. Yet, in reviewing 90 patients with and the published data on brainstem biopsy, these procedures have a diagnostic yield and morbidity and mortality rates similar to those reported for other brain locations. In addition, the quality and quantity of the material obtained confirm the diagnosis and inform an extended molecular screen, including biomarker study-information important to designing next-generation trials with targeted agents. Stereotactic biopsies can be considered a safe procedure in well-trained neurosurgical teams and could be incorporated in well-defined protocols for patients with DIPG.

Tumor-Associated CSF MicroRNAs for the Prediction and Evaluation of CNS Malignancies

Cerebrospinal fluid (CSF) is a readily reachable body fluid that is reflective of the underlying pathological state of the central nervous system (CNS). Hence it has been targeted for biomarker discovery for a variety of neurological disorders. CSF is also the major route for seeding metastases of CNS malignancies and its analysis could be informative for diagnosis and risk stratification of brain cancers. Recently, modern high-throughput, microRNAs (miRNAs) measuring technology has enabled sensitive detection of distinct miRNAs that are bio-chemicallystable in the CSF and can distinguish between different types of CNS cancers. Owing to the fact that a CSF specimen can be obtained with relative ease, analysis of CSF miRNAs could be a promising contribution to clinical practice. In this review, we examine the current scientific knowledge on tumor associated CSF miRNAs that could guide diagnosis of different brain cancer types, or could be helpful in predicting disease progression and therapy response. Finally, we highlight their potential applications clinically as biomarkers and discuss limitations.

Biopsy in a series of 130 pediatric diffuse intrinsic Pontine gliomas

PURPOSE

Diffuse intrinsic pontine glioma (DIPG) is the most severe pediatric solid tumor, with no significant improvement in the past 50 years. Possible reasons for failure to make therapeutic progress include poor understanding of the underlying molecular biology due to lack of tumor material.

METHODS

We performed a prospective analysis of children with typical appearance of DIPG who had a stereotactic biopsy in our unit since 2002. Technical approach, complications, histopathological results, and samples processing are exposed. The literature on this subject is discussed.

RESULTS

Reviewing our own 130 cases of DIPG biopsies and previous published data, these procedures appear to have a diagnostic yield and morbidity rates similar to those reported for other brain locations (3.9 % of transient morbidity in our series). In addition, the quality and the quantity of the material obtained allow to (1) confirm the diagnosis, (2) reveal that WHO grading was useless to predict outcome, and (3) perform an extended molecular screen, including biomarkers study and the development of preclinical models. Recent studies reveal that DIPG may comprise more than one biological entity and a unique oncogenesis involving mutations never described in other types of cancers, i.e., histones H3 K27M and activin receptor ACVR1.

CONCLUSION

Stereotactic biopsies of DIPG can be considered as a safe procedure in well-trained neurosurgical teams and could be incorporated in protocols. It is a unique opportunity to integrate DIPG biopsies in clinical practice and use the biology at diagnosis to drive the introduction of innovative targeted therapies, in combination with radiotherapy.

Pediatric diffuse intrinsic pontine glioma: can optimism replace pessimism?

Pediatric diffuse intrinsic pontine glioma (DIPG) has a dismal prognosis that has not seen a change in outcome despite multiple clinical trials. Possible reasons for failure to make progress in this aggressive childhood brain tumor include: poor understanding of the underlying molecular biology due to lack of access to tumor material; absence of accurate and relevant DIPG preclinical models for drug development; ill-defined therapeutic targets for novel agents; and inadequate drug delivery to the brainstem. This review will demonstrate that systematic studies to identify solutions for each of these barriers is starting to deliver progress that can turn pessimism to optimism in DIPG.

Proteomic analyses of CSF aimed at biomarker development for pediatric brain tumors

Primary brain tumors cumulatively represent the most common solid tumors of childhood and are the leading cause of cancer related death in this age group. Traditionally, molecular findings and histological analyses from biopsies of resected tumor tissue have been used for diagnosis and classification of these diseases. However, there is a dearth of useful biomarkers that have been validated and clinically implemented for pediatric brain tumors. Notably, diseases of the central nervous system (CNS) can be assayed through analysis of cerebrospinal fluid (CSF) and as such, CSF represents an appropriate medium to obtain liquid biopsies that can be informative for diagnosis, disease classification and risk stratification. Proteomic profiling of pediatric CNS malignancies has identified putative protein markers of disease, yet few effective biomarkers have been clinically validated or implemented. Advances in protein quantification techniques have made it possible to conduct such investigations rapidly and accurately through proteome-wide analyses. This review summarizes the current literature on proteomics in pediatric neuro-oncology and discusses the implications for clinical applications of proteomics research. We also outline strategies for translating effective CSF proteomic studies into clinical applications to optimize the care of this patient population.

On the Genesis of Neuroblastoma and Glioma

As the emergence of cancer is most frequent in proliferating tissues, replication errors are considered to be at the base of this disease. This review concentrates mainly on two neural cancers, neuroblastoma and glioma, with completely different backgrounds that are well documented with respect to their ontogeny. Although clinical data on other cancers of the nervous system are available, usually little can be said about their origins. Neuroblastoma is initiated in the embryo at a moment when the nervous system (NS) is in full expansion and occasionally genomic damage can lead to neoplasia. Glioma, to the contrary, occurs in the adult brain supposed to be mostly in a postmitotic state. According to current consensus, neural stem cells located in the subventricular zone (SVZ) in the adult are thought to accumulate enough genomic mutations to diverge on a carcinogenic course leading to diverse forms of glioma. After weighing the pros and cons of this current hypothesis in this review, it will be argued that this may be improbable, yielding to the original old concept of glial origin of glioma.

"Occult" post-contrast signal enhancement in pediatric diffuse intrinsic pontine glioma is the MRI marker of angiogenesis?

INTRODUCTION

In diffuse intrinsic pontine gliomas (DIPG), subtracting pre-contrast from post-contrast T1-weighted images (T1WI) occasionally reveals subtle, "occult" enhancement. We hypothesized that this represents intravascular enhancement related to angiogenesis and hence that these tumors should have greater blood volume fractions than do non-enhancing tumors.

METHODS

We retrospectively screened MR images of 66 patients initially diagnosed with DIPG and analyzed pretreatment conventional and dynamic susceptibility contrast (DSC) perfusion MRI studies of 61 patients. To determine the incidence of occult enhancement, cerebral blood volume (CBV) values were compared in areas of occult enhancement (OcE), no enhancement (NE), and normal-appearing deep cerebellar white matter (DCWM).

RESULTS

Tumors of 10 patients (16.4 %) had occult enhancement; those of 6 patients (9.8 %) had no enhancement at all. The average CBV in areas of occult enhancement was significantly higher than that in non-enhancing areas of the same tumor (P = .03), within DCWM in the same patient (P = .03), and when compared to anatomically paired/similar regions of interest (ROI) in patients with non-enhancing tumors (P = .005).

CONCLUSION

Areas of OcE correspond to areas of higher CBV in DIPG, which may be an MRI marker for angiogenesis, but larger scale studies may be needed to determine its potential relevance to grading by imaging, treatment stratification, biopsy guidance, and evaluation of response to targeted therapy.

Diagnostic value and safety of stereotactic biopsy for brainstem tumors: a systematic review and meta-analysis of 1480 cases

BACKGROUND

The feasibility and safety of stereotactic biopsy for brainstem tumors (BSTs) are controversial. Although magnetic resonance imaging (MRI) has been reported as the preferred diagnostic tool, histopathological analysis is frequently necessary to establish a definitive diagnosis. Recent advances in molecular characterization of brainstem gliomas-accounting for the majority of BSTs-have revealed several potential targets for molecular-based therapies. Hence, a molecular stereotactic biopsy that combines histopathological diagnosis with molecular-genetic analysis will become increasingly important for patients with BSTs.

OBJECTIVE

We conducted a systemic review and meta-analysis to determine the risks and benefits of stereotactic biopsy for BSTs.

METHODS

A systematic search in PubMed, Embase, and the Web of Science yielded 3766 potentially eligible abstracts. Meta-analysis was conducted on 38 studies describing 1480 biopsy procedures for BSTs. Primary outcome measures were diagnostic success and procedure-related complications. Data were analyzed according to standard meta-analytic techniques.

RESULTS

The weighted average proportions across the analyzed studies were: 96.2% (95% confidence interval [CI]: 94.5%-97.6%) for diagnostic success, 7.8% (95% CI: 5.6%-10.2%) for overall morbidity, 1.7% (95% CI: 0.9%-2.7%) for permanent morbidity, and 0.9% (95% CI: 0.5%-1.4%) for mortality. Meta-regression revealed a significant correlation between diagnostic success rates and the number of biopsy procedures performed annually in each center (P = .011). Other factors did not affect the outcome measures.

CONCLUSION

Stereotactic biopsy of BSTs is safe. It allows exact histopathological diagnosis as a prerequisite for adequate treatment and opens new perspectives for the molecular characterization of these tumors as a crucial first step toward more individualized treatment concepts.

ABBREVIATIONS

: BST, brainstem tumorCI, confidence intervalD-BSG, diffuse brainstem gliomaHGG, high-grade gliomaLGG, low-grade gliomasTC, transcerebellarTF, transfrontal.

Morphologic characteristics and immunohistochemical profile of diffuse intrinsic pontine gliomas

Tumors of the central nervous system are the second most common malignancy in children. In particular, diffuse intrinsic pontine gliomas (DIPGs) are aggressive tumors with poor prognosis and account for 10% to 25% of pediatric brain tumors. The majority of DIPGs are astrocytic, infiltrative, and localized to the pons. Studies have shown median survival times of less than a year, with 90% of children dying within 2 years. We built multitissue arrays with 24 postmortem DIPG samples and analyzed the morphology and expression of several proteins (p53, EGFR, GFAP, MIB1, BMI1, β-catenin, p16, Nanog, Nestin, OCT4, OLIG2, SOX2) with the goal of identifying potential treatment targets and improving our understanding of the biology of these tumors. The majority of DIPGs were high-grade gliomas (22), with 18 cases having features of glioblastoma (World Health Organization [WHO] grade IV) and 4 cases with high-grade features consistent with anaplastic astrocytoma (WHO grade III). One case was low grade (WHO grade II), and 1 case showed intermediate features between a grade II and grade III glioma (low mitotic rate but increased cellularity and cell atypia), being difficult to grade precisely. The majority of the tumors were positive for GFAP (24/24), MIB1 (23/24), OLIG2 (22/24), p16 (20/24), p53 (20/24), SOX2 (19/24), EGFR (16/24), and BMI1 (9/24). Our results suggest that dysregulation of EGFR and p53 may play an important role in the development of DIPGs. The majority of DIPGs express stem cell markers such as SOX2 and OLIG2, consistent with a role for tumor stem cells in the origin and maintenance of these tumors. Targeted therapies against these proteins could be beneficial in treatment.

Brainstem oligodendroglioma in a puppy

A 5 mo old male golden retriever presented for evaluation of an acute onset, progressive neurologic disease. Although computed tomography (CT) was unremarkable, MRI identified an ill-defined mass located in the medulla, which was considered likely responsible for the clinical signs. The imaging features closely resembled the classic features of human brainstem gliomas in the pediatric population. Histopathologic examination confirmed the lesion to be an anaplastic oligodendroglioma.

Can multiparametric MRI and FDG-PET predict outcome in diffuse brainstem glioma? A report from a prospective phase-II study

PURPOSE

To study the impact of multiparametric MRI and (18)F-FDG-PET on the outcome of children with diffuse intrinsic pontine gliomas (DIPG).

MATERIALS AND METHODS

Imaging data from a phase-II prospective therapeutic study in children with newly diagnosed DIPG were considered for evaluation. They included baseline MRI with contrast enhancement before treatment. Functional imaging included MR spectroscopy, MR perfusion and FDG-PET studies. All patients (n = 20) had baseline MRI and 11 patients had FDG-PET. Response was assessed by MRI and PET 4 weeks after therapy. Baseline imaging findings were correlated with survival. Presence or absence of adverse parameters on MRI (heterogeneous contrast enhancement, hyperperfusion or increased choline:NAA ratio) was used to develop a cumulative radiological prognostic index (RPI). Sensitivity and specificity of each imaging modality in tumour grading was estimated.

RESULTS

The cumulative RPI was able to classify the patients into different grades and was predictive of overall survival (p = 0.02). MR perfusion also predicted survival (p = 0.039). Sensitivity and specificity of MRI and FDG-PET to detect low-grade gliomas were low to moderate (33-66%), but moderate to high in detecting high-grade gliomas (50-100%). Baseline FDG uptake on PET scan did not correlate with survival (p = 0.7).

CONCLUSIONS

Cumulative RPI was able to classify tumours into different grades and predicted clinical outcome. At baseline, MR hyperperfusion indicated a shorter survival for DIPG patients. Sensitivity and specificity of imaging modalities to detect low-grade gliomas were poor.

Clinicopathological features of human brainstem gliomas

We describe the clinicopathological features of 25 brainstem gliomas (BSGs). Twenty BSGs located in the pons and were all in children. Four BSGs located in the medulla oblongata were in 2 children and 2 adults. One (in a child) was located in the midbrain. Radiological findings on MR images were low-intensity on T1 weighted images and high-intensity on T2 weighted images. Mean survival when pontine glioma was treated by radiotherapy and/or use of temozolomide was 14 months, although 4 patients (3 cervicomedullary types and one focal type arising from midbrain) are alive. Follow up was from 5 months to 6 years. Histopathological features of 10 cases of the diffuse type were: 4 grade II astrocytomas, 4 grade III astrocytomas, and 2 glioblastomas. MIB-1 index was from 0.8 to 38 %. P53 was positive for 80 % of 15 tumors and there were no negative results. MGMT was positive in 60 % of 15 tumors and negative in 12.4 %. IDH1 was negative in 61.6 %. There was no positive result for IDH1 in this study. Thus, our histopathological results were indicative of high p53 immunoreactivity and no IDH1 immunoreactivity related to secondary malignant change.

Insights into pediatric diffuse intrinsic pontine glioma through proteomic analysis of cerebrospinal fluid

Diffuse intrinsic pontine glioma (DIPG) is a leading cause of brain tumor-related death in children. DIPG is not surgically resectable, resulting in a paucity of tissue available for molecular studies. As such, tumor biology is poorly understood, and, currently, there are no effective treatments. In the absence of frozen tumor specimens, body fluids--such as cerebrospinal fluid (CSF), serum, and urine--can serve as more readily accessible vehicles for detecting tumor-secreted proteins. We analyzed a total of 76 specimens, including CSF, serum, urine, and normal and tumor brainstem tissue. Protein profiling of CSF from patients with DIPG was generated by mass spectrometry using an LTQ-Orbitrap-XL and database search using the Sequest algorithm. Quantitative and statistical analyses were performed with ProteoIQ and Partek Genomics Suite. A total of 528 unique proteins were identified, 71% of which are known secreted proteins. CSF proteomic analysis revealed selective upregulation of Cyclophillin A (CypA) and dimethylarginase 1 (DDAH1) in DIPG (n = 10), compared with controls (n = 4). Protein expression was further validated with Western blot analysis and immunohistochemical assays using CSF, brain tissue, serum, and urine from DIPG and control specimens. Immunohistochemical staining showed selective upregulation of secreted but not cytosolic CypA and DDAH1 in patients with DIPG. In this study, we present the first comprehensive protein profile of CSF specimens from patients with DIPG to demonstrate selective expression of tumor proteins potentially involved in brainstem gliomagenesis. Detection of secreted CypA and DDAH1 in serum and urine has potential clinical application, with implications for assessing treatment response and detecting tumor recurrence in patients with DIPG.

Treatment of recurrent diffuse intrinsic pontine glioma: the MD Anderson Cancer Center experience

Recurrent diffuse intrinsic pontine gliomas (DIPG) are traditionally treated with palliative care since no effective treatments have been described for these tumors. Recently, clinical studies have been emerging, and individualized treatment is attempted more frequently. However, an informative way to compare the treatment outcomes has not been established, and historical control data are missing for recurrent disease. We conducted a retrospective chart review of patients with recurrent DIPG treated between 1998 and 2010. Response progression-free survival and possible influencing factors were evaluated. Thirty-one patients were identified who were treated in 61 treatment attempts using 26 treatment elements in 31 different regimens. The most frequently used drugs were etoposide (14), bevacizumab (13), irinotecan (13), nimotuzumab (13), and valproic acid (13). Seven patients had repeat radiation therapy to the primary tumor. Response was recorded after 58 treatment attempts and was comprised of 0 treatment attempts with complete responses, 7 with partial responses, 20 with stable diseases, and 31 with progressive diseases The median progression-free survival after treatment start was 0.16 years (2 months) and was found to be correlated to the prior time to progression but not to the number of previous treatment attempts. Repeat radiation resulted in the highest response rates (4/7), and the longest progression-free survival. These data provide a basis to plan future clinical trials for recurrent DIPG. Repeat radiation therapy should be tested in a prospective clinical study.

Predicting outcome of children with diffuse intrinsic pontine gliomas using multiparametric imaging

Noninvasive evaluation using MRI is the primary means to routinely assess children with diffuse intrinsic pontine gliomas (DIPGs). However, no standard MR sequence has correlated with outcome in these patients. In this study, patients with DIPGs were assessed to determine the combined prognostic value via dynamic susceptibility contrast (DSC) MRI, single-voxel spectroscopy (SVS), multivoxel MR spectroscopy (MRS), and T1-weighted post-gadolinium imaging. Eligible patients had clinical and radiographic findings consistent with a DIPG. Imaging studies were acquired on a 1.5T MRI at various time points during each patient's course. Data were evaluated using a Cox proportional hazard model, a time-dependent covariant Cox model, a Wald test, and a Kaplan-Meier analysis. Ninety-eight studies were performed on 34 patients of median age 5.5 years. Median survival from diagnosis was 468 days. At baseline imaging only, increased ratio of choline to n-acetylaspartate (Cho:NAA) on SVS and increased perfusion on DSC-MRI each predicted shorter survival (relative risk [RR] = 1.48, P = .015 and RR = 4.91, P = .0012, respectively). When analyzing all subsequent time points, increased maximum Cho:NAA on MRS (RR = 1.45, P = .042), increased Cho:NAA on SVS (RR = 1.69, P = .003), increased perfusion (RR = 4.68, P = .0016), and the presence of enhancement (RR = 5.69, P = .022) each predicted shorter survival. Kaplan-Meier analysis showed shorter survival associated with increased perfusion at baseline (P = .0004). Increased perfusion at any time point predicts a significantly shorter survival in children with DIPG. In addition, enhancement, increased Cho:NAA on SVS, and increased maximum Cho:NAA on chemical shift imaging are predictive of shorter survival over time. Routine baseline and subsequent imaging for children with DIPG should, at minimum, incorporate DSC-MRI and SVS.

Interpretation of magnetic resonance images in diffuse intrinsic pontine glioma: a survey of pediatric neurosurgeons

OBJECT

The current management paradigm for children with newly diagnosed diffuse intrinsic pontine glioma (DIPG) is to establish a diagnosis and begin therapy based on MR imaging findings correlated with an appropriate clinical presentation, and without a tissue diagnosis. This strategy assumes that pediatric neurosurgeons and neurooncologists uniformly interpret MR imaging findings in this population. This study sought to examine the consistency of North American pediatric neurosurgeons in assessing MR images in this patient population, and in their surgical plans based on the interpretation of those images.

METHODS

The authors created an online survey and invited all members of the American Society of Pediatric Neurosurgeons and the American Association of Neurological Surgeons/Congress of Neurological Surgeons Joint Section for Pediatric Neurosurgery to participate. The survey consisted of 58 questions, and 48 pertained to representative MR images from 16 children who presented to The Children's Hospital of Colorado with diffuse pontine tumors. Based on the imaging presented and a standard clinical scenario, the respondent was asked if she or he believed a lesion to be "typical" or "atypical," whether she or he would biopsy the lesion, and what surgical approach would be chosen. The remaining 10 questions pertained to respondent demographics and his or her practice regarding tissue preservation and interest in participating in a multicenter trial that included tumor biopsy in selected cases. Rates at which each lesion was considered to be typical or atypical and rates of recommended biopsy were calculated.

RESULTS

Surveys were received by 269 individuals. Eighty-six responses were received (32.0%). No tumor was judged to be either typical or atypical by all respondents. Individual surgeons varied widely regarding how many of the tumors were judged as typical or warranted a biopsy. The percentage of respondents who disagreed with the majority opinion regarding whether a tumor qualified as typical ranged from 2.3% to 48.8%, with a median of 28.6%. More than 75% agreement regarding whether a tumor was typical or atypical was found in 7 (43.8%) of 16 cases. The κ statistic regarding typicality was 0.297 ± 0.0004 (mean ± SEM), implying only fair agreement. For every tumor, at least 1 respondent who believed the lesion to be typical in appearance would nevertheless biopsy the lesion. Of those respondents who considered a lesion to be typical, a median of 5.1% (range 1.2%-66.7%) would choose to biopsy this lesion. Of those respondents who considered a lesion atypical, a median of 18.3% (range 3.7%-100%) would choose not to biopsy the lesion. Of 85 responses to the question, "Would you be willing to biopsy a typical diffuse pontine glioma as a part of a multicenter trial?," 59 (69.4%) of 85 respondents answered that they would.

CONCLUSIONS

Although making a diagnosis based on radiographic evidence alone represents a well-established management paradigm for children with suspected DIPG, this study demonstrates considerable inconsistency on the part of pediatric neurosurgeons in the application of this strategy to individual patients. As such, the practice of diagnosing DIPG based on imaging characteristics and clinical history alone does not reach the appropriate threshold to be considered a standard of care.

Temozolomide in the treatment of children with newly diagnosed diffuse intrinsic pontine gliomas: a report from the Children's Oncology Group

An open-label phase II study (ACNS0126) testing the efficacy of chemoradiotherapy with temozolomide (TMZ) followed by adjuvant TMZ was conducted by the Children's Oncology Group. During the period from July 6, 2004 through September 6, 2005, 63 children with newly diagnosed diffuse intrinsic pontine glioma (DIPG) were enrolled in the study. All patients received TMZ at a dosage of 90 mg/m(2)/day for 42 days to a dose of 59.4 Gy. Four weeks following irradiation, TMZ was given at a dosage of 200 mg/m(2)/day for 5 days every 28 days, for a total of 10 cycles. The primary objective of the statistical analysis was to determine whether the current treatment produced a 1-year event-free survival (EFS) rate higher than the historical baseline of 21.9% observed in CCG-9941. The mean 1-year EFS (± standard deviation) was 14% ± 4.5%, compared with 21.9% ± 5% for CCG-9941. The P value of the test of comparison of 1-year EFS, based on a 1-sided, 1-sample test of proportions, was .96. There was no evidence that temozolomide produced a 1-year EFS rate higher than 21.9%. The mean 1-year OS (± standard deviation) was 40% ± 6.5%, compared with 32% ± 6% for CCG-9941. The median time to death was 9.6 months. Chemoradiotherapy with TMZ followed by adjuvant TMZ is not more effective than previously reported regimens for the treatment of children with DIPG.

MRI as a central component of clinical trials analysis in brainstem glioma: a report from the Pediatric Brain Tumor Consortium (PBTC)

We report MRI findings from 2 pediatric clinical trials of diffuse intrinsic brainstem glioma (BSG) incorporating concurrent radiation therapy (RT) with molecularly targeted agents (gefitinib and tipifarnib). We determined associations of MRI variables with progression-free survival and overall survival and investigated effects of treatment on these variables. MRI (including diffusion and perfusion) was done before treatment, every 8 weeks (first year), every 12 weeks (thereafter), and at the end of treatment or disease progression. Reduced tumor volume (P < .0001) and tumor diffusion values (P <.0001) were apparent on the first post-RT/drug studies. Decreases in tumor volume correlated with pre-RT volume (P < .0001) and pre-RT diffusion values (P < .0001); larger decreases were noted for tumors with higher volumes and diffusion values. Patients with larger pre-RT tumors had longer progression-free survival (P < .0001). Patients with ≥ 25% decrease in tumor volume and diffusion values after RT had longer progression-free survival (P = .028) and overall survival (P = .0009). Enhancement at baseline and over time was significantly associated with shorter survival. Tumor diffusion values with baseline enhancement were significantly lower than those without (P = .0002). RT of BSG is associated with decreased tumor volume and intralesional diffusion values; patients with ≥ 25% decrease in values post-RT had relatively longer survival intervals, apparently providing an early imaging-based surrogate for relative outcomes. Patients with larger tumors and greater decreases in tumor volume and diffusion values had longer survival intervals. Tumor enhancement was associated with shorter survival, lower tumor diffusion values (increased cellularity), and a smaller drop in diffusion values after RT (P = .006). These associations justify continued investigation in other large clinical trials of brainstem glioma patients.

Homozygous loss of ADAM3A revealed by genome-wide analysis of pediatric high-grade glioma and diffuse intrinsic pontine gliomas

Overall, pediatric high-grade glioma (pHGG) has a poor prognosis, in part due to the lack of understanding of the underlying biology. High-resolution 244 K oligo array comparative genomic hybridization (CGH) was used to analyze DNA from 38 formalin-fixed paraffin-embedded predominantly pretreatment pHGG samples, including 13 diffuse intrinsic pontine gliomas (DIPGs). The patterns of gains and losses were distinct from those seen in HGG arising in adults. In particular, we found 1q gain in up to 27% of our cohort compared with 9% reported in adults. A total of 13% had a balanced genetic profile with no large-scale copy number alterations. Homozygous loss at 8p12 was seen in 6 of 38 (16%) cases of pHGG. This novel deletion, which includes the ADAM3A gene, was confirmed by quantitative real-time PCR (qPCR). Loss of CDKN2A/CDKN2B in 4 of 38 (10%) samples by oligo array CGH was confirmed by fluorescent in situ hybridization on tissue microarrays and was restricted to supratentorial tumors. Only ∼50% of supratentorial tumors were positive for CDKN2B expression by immunohistochemistry (IHC), while ∼75% of infratentorial tumors were positive for CDKN2B expression (P = 0.03). Amplification of the 4q11-13 region was detected in 8% of cases and included PDGFRA and KIT, and subsequent qPCR analysis was consistent with the amplification of PDGFRA. MYCN amplification was seen in 5% of samples being significantly associated with anaplastic astrocytomas (P= 0.03). Overall, DIPG shared similar spectrum of changes to supratentorial HGG with some notable differences, including high-frequency loss of 17p and 14q and lack of CDKN2A/CDKN2B deletion. Informative genetic data providing insight into the underlying biology and potential therapeutic possibilities can be generated from archival tissue and typically small biopsies from DIPG. Our findings highlight the importance of obtaining pretreatment samples.

Quantitative diffusion-weighted and dynamic susceptibility-weighted contrast-enhanced perfusion MR imaging analysis of T2 hypointense lesion components in pediatric diffuse intrinsic pontine glioma

BACKGROUND AND PURPOSE

Focal anaplasia characterized by T2 hypointensity, signal-intensity enhancement on postcontrast T1-weighted MR imaging and restricted water diffusion has been reported in a patient with juvenile pilocytic astrocytoma. We identified T2(HOF) with these MR imaging characteristics in children with DIPG and hypothesized that these represent areas of focal anaplasia; and may, therefore, have increased perfusion properties and should be characterized by increased perfusion. Thus, we used DSC to investigate our hypothesis.

MATERIALS AND METHODS

We retrospectively reviewed the baseline MR imaging scans of 86 patients (49 girls, 37 boys; median age, 6.1 years; range, 1.1-17.6 years) treated for DIPG at our hospital (2004-2009). T2(HOF) with the described MR imaging characteristics was identified in 10 patients. We used a region of interest-based approach to compare the ADC, FA, rCBV, rCBF, and rMTT of T2(HOF) with those of the typical T2(HRT).

RESULTS

The ADC of T2(HOF) with the specified MR imaging characteristics was significantly lower than that of T2(HRT) (range, 0.71-1.95 μm(2)/ms versus 1.36-2.13 μm(2)/ms; P < .01); and the FA (range, 0.12-0.34 versus 0.07-0.24; P = .03) and rCBV (range, 0.4-2.62 versus 0.23-1.57; P = .01) values of T2(HOF)s were significantly higher.

CONCLUSIONS

Our data suggest that T2(HOF) in DIPG may represent areas of focal anaplasia and underline the importance of regional, rather than global, tumor-field analysis. T2(HOF) may be the ideal target when stereotactic biopsy of tumors that present with an inhomogeneous T2 signal intensity is considered.

A prospective study of temozolomide plus thalidomide during and after radiation therapy for pediatric diffuse pontine gliomas: preliminary results of the Korean Society for Pediatric Neuro-Oncology study

This prospective study was performed to determine the efficacy and safety of temozolomide (TMZ) plus thalidomide during and after radiation therapy (RT) in pediatric patients with newly diagnosed diffuse pontine glioma (DPG). Seventeen patients with pediatric DPG were enrolled between November 2004 and March 2008. The median age was eight years (range, 3-16 years); seven patients were male and ten were female. With the exception of one glioblastoma case, which was diagnosed via open biopsy, all diagnoses were established using neuroradiological studies. The authors used the Korean Society for Pediatric Neuro-Oncology (KSPNO)-A053 protocol. The mean follow-up period was 12 months (range, 8.5-25 months). Five patients were withdrawn from the study. The rates of response to treatment and survival were analyzed in 12 patients. Ten out of the 12 patients showed a partial response (PR), whereas one patient exhibited stable disease (SD) and another patient had progressive disease (PD). The tumor control rate was 92% (11/12) and the response rate was 83% (10/12). The median progression-free survival (PFS) of the 12 patients was 7.2 months (95% confidence interval (CI), 3.6-10.7). Six-month and twelve-month PFS were 58.3 and 16.7%, respectively. Overall survival (OS) was 12.7 months (95% CI, 10.4-15.1). One and two-year survival were 58.3 and 25%, respectively. The main adverse effect was hematological toxicity, with four patients exhibiting grade 3 or 4 toxicity. All patients tolerated the regimen well enough to continue the adjuvant chemotherapy. No Pneumocystis jiroveci pneumonia was noted. The TMZ plus thalidomide regimen was safe and tolerated well enough to be administered on an outpatient basis. Larger studies are required to demonstrate the efficacy of this regimen.

Preclinical evaluation of radiation and perifosine in a genetically and histologically accurate model of brainstem glioma

Brainstem gliomas (BSG) are a rare group of central nervous system tumors that arise mostly in children and usually portend a particularly poor prognosis. We report the development of a genetically engineered mouse model of BSG using the RCAS/tv-a system and its implementation in preclinical trials. Using immunohistochemistry, we found that platelet-derived growth factor (PDGF) receptor alpha is overexpressed in 67% of pediatric BSGs. Based on this observation, we induced low-grade BSGs by overexpressing PDGF-B in the posterior fossa of neonatal nestin tv-a mice. To generate high-grade BSGs, we overexpressed PDGF-B in combination with Ink4a-ARF loss, given that this locus is commonly lost in high-grade pediatric BSGs. We show that the likely cells of origin for these mouse BSGs exist on the floor of the fourth ventricle and cerebral aqueduct. Irradiation of these high-grade BSGs shows that although single doses of 2, 6, and 10 Gy significantly increased the percent of terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL)-positive nuclei, only 6 and 10 Gy significantly induce cell cycle arrest. Perifosine, an inhibitor of AKT signaling, significantly induced TUNEL-positive nuclei in this high-grade BSG model, but in combination with 10 Gy, it did not significantly increase the percent of TUNEL-positive nuclei relative to 10 Gy alone at 6, 24, and 72 hours. Survival analysis showed that a single dose of 10 Gy significantly prolonged survival by 27% (P = 0.0002) but perifosine did not (P = 0.92). Perifosine + 10 Gy did not result in a significantly increased survival relative to 10 Gy alone (P = 0.23). This PDGF-induced BSG model can serve as a preclinical tool for the testing of novel agents.

The evolving role of surgery in the management of pediatric brain tumors

Surgery is an integral component and typically the first line of therapy for children with central nervous system tumors. The outcome with regard to surgical morbidity and disease control can be greatly influenced by the initial care that these children receive. Conventional aims of neurosurgery including tumor removal, management of hydrocephalus, and diagnostic sampling have been radically modified with innovative technologies such as navigational guidance, functional mapping, endoscopic surgery, second-look surgery, and physiologic imaging. The overall role of the pediatric neurosurgeon in caring for children with nervous system tumors is also expanding to include unconventional responsibilities including disease staging, tissue procurement, and drug delivery. It is thus anticipated that the pediatric neurosurgeon will be increasingly relied upon for oncologic therapeutic strategies and should thus remain abreast of forthcoming information and technologies.