Incidence and patterns of neuraxis metastases in children with diffuse pontine glioma

High-Grade Temporal Ganglioglioma in an Older Adult Woman

Ganglioglioma (GG) is a WHO-grade 1 glioneuronal neoplasm. It is well differentiated with a slow-growing pattern and is composed of a combination of neoplastic ganglion and glial cells. Anaplastic ganglioglioma (AGG) is an extremely rare malignant variant of ganglioglioma, which is not included in the new WHO classification; however, the term is used to talk about gangliogliomas with data of malignancy. AGGs usually occur in children and young adults and are associated with high recurrence and mortality. The authors describe the case of a 62-year-old woman with AGG. She presented with cacosmia, vertigo, nausea, and focal-onset seizures with secondary generalization. Magnetic resonance imaging (MRI) revealed an intra-axial lesion in the left temporal lobe. She underwent microsurgical resection guided by electrocorticography (ECoG), and a diagnosis of AGG based on microscopic morphology and immunohistochemical analysis was obtained. She was discharged a few days after surgery with subtotal resection of the lesion, no additional neurological deficit, and adequate seizure control. AGG is a very rare and poorly studied entity. It is currently a controversial term used to refer to gangliogliomas with signs of malignancy. It occurs mainly in children and young adults with temporal lobe epilepsy. Total resection is the best prognostic factor, given the unknown efficacy of radiotherapy and chemotherapy. In our case, the patient was an adult woman with a subtotal resection followed by concomitant radiotherapy and chemotherapy, obtaining a mean survival similar to that reported in the literature, so it can be thought that there is a benefit obtained with chemotherapy and radiotherapy despite having performed a subtotal resection of the lesion. Further studies are needed to establish clear diagnostic criteria for AGG, and a multicenter database of AGGs is necessary for a better understanding of the pathology and to offer the best treatment and prognosis.

Spatially controlled construction of assembloids using bioprinting

The biofabrication of three-dimensional (3D) tissues that recapitulate organ-specific architecture and function would benefit from temporal and spatial control of cell-cell interactions. Bioprinting, while potentially capable of achieving such control, is poorly suited to organoids with conserved cytoarchitectures that are susceptible to plastic deformation. Here, we develop a platform, termed Spatially Patterned Organoid Transfer (SPOT), consisting of an iron-oxide nanoparticle laden hydrogel and magnetized 3D printer to enable the controlled lifting, transport, and deposition of organoids. We identify cellulose nanofibers as both an ideal biomaterial for encasing organoids with magnetic nanoparticles and a shear-thinning, self-healing support hydrogel for maintaining the spatial positioning of organoids to facilitate the generation of assembloids. We leverage SPOT to create precisely arranged assembloids composed of human pluripotent stem cell-derived neural organoids and patient-derived glioma organoids. In doing so, we demonstrate the potential for the SPOT platform to construct assembloids which recapitulate key developmental processes and disease etiologies.

Leptomeningeal dissemination in pediatric brain tumors

Leptomeningeal disease (LMD) in pediatric brain tumors (PBTs) is a poorly understood and categorized phenomenon. LMD incidence rates, as well as diagnosis, treatment, and screening practices, vary greatly depending on the primary tumor pathology. While LMD is encountered most frequently in medulloblastoma, reports of LMD have been described across a wide variety of PBT pathologies. LMD may be diagnosed simultaneously with the primary tumor, at time of recurrence, or as primary LMD without a primary intraparenchymal lesion. Dissemination and seeding of the cerebrospinal fluid (CSF) involves a modified invasion-metastasis cascade and is often the result of direct deposition of tumor cells into the CSF. Cells develop select environmental advantages to survive the harsh, nutrient poor and turbulent environment of the CSF and leptomeninges. Improved understanding of the molecular mechanisms that underlie LMD, along with improved diagnostic and treatment approaches, will help the prognosis of children affected by primary brain tumors.

The promise of metabolic imaging in diffuse midline glioma

Recent insights into histopathological and molecular subgroups of glioma have revolutionized the field of neuro-oncology by refining diagnostic categories. An emblematic example in pediatric neuro-oncology is the newly defined diffuse midline glioma (DMG), H3 K27-altered. DMG represents a rare tumor with a dismal prognosis. The diagnosis of DMG is largely based on clinical presentation and characteristic features on conventional magnetic resonance imaging (MRI), with biopsy limited by its delicate neuroanatomic location. Standard MRI remains limited in its ability to characterize tumor biology. Advanced MRI and positron emission tomography (PET) imaging offer additional value as they enable non-invasive evaluation of molecular and metabolic features of brain tumors. These techniques have been widely used for tumor detection, metabolic characterization and treatment response monitoring of brain tumors. However, their role in the realm of pediatric DMG is nascent. By summarizing DMG metabolic pathways in conjunction with their imaging surrogates, we aim to elucidate the untapped potential of such imaging techniques in this devastating disease.

CAR T-cells to treat brain tumors

Tremendous success using CAR T therapy in hematological malignancies has garnered significant interest in developing such treatments for solid tumors, including brain tumors. This success, however, has yet to be mirrored in solid organ neoplasms. CAR T function has shown limited efficacy against brain tumors due to several factors including the immunosuppressive tumor microenvironment, blood-brain barrier, and tumor-antigen heterogeneity. Despite these considerations, CAR T-cell therapy has the potential to be implemented as a treatment modality for brain tumors. Here, we review adult and pediatric brain tumors, including glioblastoma, diffuse midline gliomas, and medulloblastomas that continue to portend a grim prognosis. We describe insights gained from different preclinical models using CAR T therapy against various brain tumors and results gathered from ongoing clinical trials. Furthermore, we outline the challenges limiting CAR T therapy success against brain tumors and summarize advancements made to overcome these obstacles.

Towards Standardisation of a Diffuse Midline Glioma Patient-Derived Xenograft Mouse Model Based on Suspension Matrices for Preclinical Research

Diffuse midline glioma (DMG) is an aggressive brain tumour with high mortality and limited clinical therapeutic options. Although in vitro research has shown the effectiveness of medication, successful translation to the clinic remains elusive. A literature search highlighted the high variability and lack of standardisation in protocols applied for establishing the commonly used HSJD-DIPG-007 patient-derived xenograft (PDX) model, based on animal host, injection location, number of cells inoculated, volume, and suspension matrices. This study evaluated the HSJD-DIPG-007 PDX model with respect to its ability to mimic human disease progression for therapeutic testing in vivo. The mice received intracranial injections of HSJD-DIPG-007 cells suspended in either PBS or Matrigel. Survival, tumour growth, and metastases were assessed to evaluate differences in the suspension matrix used. After cell implantation, no severe side effects were observed. Additionally, no differences were detected in terms of survival or tumour growth between the two suspension groups. We observed delayed metastases in the Matrigel group, with a significant difference compared to mice with PBS-suspended cells. In conclusion, using Matrigel as a suspension matrix is a reliable method for establishing a DMG PDX mouse model, with delayed metastases formation and is a step forward to obtaining a standardised in vivo PDX model.

H3K27-altered diffuse midline glioma: a paradigm shifting opportunity in direct delivery of targeted therapeutics

INTRODUCTION

Despite much progress, the prognosis for H3K27-altered diffuse midline glioma (DMG), previously known as diffuse intrinsic pontine glioma when located in the brainstem, remains dark and dismal.

AREAS COVERED

A wealth of research over the past decade has revolutionized our understanding of the molecular basis of DMG, revealing potential targetable vulnerabilities for treatment of this lethal childhood cancer. However, obstacles to successful clinical implementation of novel therapies remain, including effective delivery across the blood-brain barrier (BBB) to the tumor site. Here, we review relevant literature and clinical trials and discuss direct drug delivery via convection-enhanced delivery (CED) as a promising treatment modality for DMG. We outline a comprehensive molecular, pharmacological, and procedural approach that may offer hope for afflicted patients and their families.

EXPERT OPINION

Challenges remain in successful drug delivery to DMG. While CED and other techniques offer a chance to bypass the BBB, the variables influencing successful intratumoral targeting are numerous and complex. We discuss these variables and potential solutions that could lead to the successful clinical implementation of preclinically promising therapeutic agents.

Four cases of acute comitant esotropia associated with diffuse intrinsic pontine glioma in children

BACKGROUND

Acute acquired concomitant esotropia (AACE) is usually a benign form of strabismus that infrequently is associated with intracranial pathology. Clinicians have noted an increase in its incidence and theorize that it may be related to public health "lockdown" measures taken in response to the COVID-19 pandemic. With an increased incidence of AACE clinicians must firstly differentiate AACE from common accommodative esotropia and secondly recognize AACE as a possible sign of serious neuropathology.Diffuse Intrinsic Pontine Glioma (DIPG) is a devastating diagnosis for affected families. Children typically present at age 6-7 years with cranial nerve palsies, long tract signs, and/or cerebellar signs. Diagnosis is made from characteristic findings on magnetic resonance brain imaging (MRI brain) and treatment includes radiotherapy and palliative care. Two years from diagnosis, 90% of affected children will have died from their disease.

CASE SERIES

We present four cases that attended our pediatric ophthalmology clinic with AACE either as a presenting sign of DIPG or as a clinical finding following a DIPG diagnosis. Patient A (age 5 years) presented to the emergency eye clinic with sudden onset diplopia and intermittent esotropia. Suppression later developed, they had 0.00 logMAR visual acuity either eye, and bilateral physiological hypermetropia. MRI brain imaging requested as a result of the unusual presentation led to the DIPG diagnosis. The other 3 cases (ages 11, 5 & 5 years) were assessed post DIPG diagnosis and found to have an esotropia measuring bigger on 1/3-meter fixation than 6-meter fixation, full ocular motility, physiological hypermetropia or emmetropia, and visual acuity normal for age. Other than patient B (age 11 years), who had papilledema and gaze evoked nystagmus when they were assessed 2 weeks prior to death, no patient had any other clinical eye findings.

CONCLUSIONS

This small series of 4 patients attending our clinic within a 12-month period supports the notion that children presenting with AACE should routinely be offered brain MRI. Not all children with DIPG-associated AACE have significant ophthalmic findings indicative of intracranial pathology. With the potential for increased incidence of AACE related to lockdowns, clinicians should be reminded of the infrequent possibility their patient has a more serious condition.

Leptomeningeal metastases in glioma revisited: incidence and molecular predictors based on postcontrast fluid-attenuated inversion recovery imaging

OBJECTIVE

Leptomeningeal metastases (LMs) in glioma have been underestimated given their low incidence and the lack of reliable imaging. Authors of this study aimed to investigate the real-world incidence of LMs using cerebrospinal fluid (CSF)–sensitive imaging, namely postcontrast fluid-attenuated inversion recovery (FLAIR) imaging, and to analyze molecular predictors for LMs in the molecular era.

METHODS

A total of 1405 adult glioma (World Health Organization [WHO] grade 2–4) patients underwent postcontrast FLAIR imaging at initial diagnosis and during treatment monitoring between 2001 and 2021. Collected molecular data included isocitrate dehydrogenase (IDH) mutation, 1p/19q codeletion, H3 K27 alteration, and O6-methylguanine–DNA methyltransferase (MGMT) promoter methylation status. LM diagnosis was performed with MRI including postcontrast FLAIR sequences. Logistic regression analysis for LM development was performed with molecular, clinical, and imaging data. Overall survival (OS) was compared between patients with and those without LM.

RESULTS

LM was identified in 228 patients (16.2%), 110 (7.8%) at the initial diagnosis and 118 (8.4%) at recurrence. Among the molecular diagnostics, IDH-wildtype (OR 3.14, p = 0.001) and MGMT promoter unmethylation (OR 1.43, p = 0.034) were independent predictors of LM. WHO grade 4 (OR 10.52, p < 0.001) and nonlobar location (OR 1.56, p = 0.048) were associated with LM at initial diagnosis, whereas IDH-wildtype (OR 5.04, p < 0.001) and H3 K27 alteration (OR 3.39, p = 0.003) were associated with LM at recurrence. Patients with LM had a worse median OS than those without LM (16.7 vs 32.0 months, p < 0.001, log-rank test), which was confirmed as an independent factor on multivariable Cox analysis (p = 0.004).

CONCLUSIONS

CSF-sensitive imaging aids the diagnosis of LM, demonstrating a high incidence of LM in adult gliomas. Furthermore, molecular markers are associated with LM development in glioma, and patients with aggressive molecular markers warrant imaging surveillance for LM.

Disseminated diffuse midline glioma associated with poorly differentiated orbital lesion and metastases in an 8-year-old girl: case report and literature review

BACKGROUND

Disseminated diffuse midline glioma (DMG) is a devastating diagnosis. Molecular subtyping has increased our understanding of this tumor.

CASE

Here, we report the case of an 8-year-old girl who presented with symptoms of brainstem dysfunction and was found to have disseminated DMG with lesions in the pons, thalamus and bilateral temporal lobes. Molecular subtyping of the temporal lobe tumor tissue was consistent with H3 K27me3 loss and EZHIP overexpression, falling under the newly designated "H3 K27-altered" AQ5WHO subtype of DMG. Pathology from biopsy of the orbital lesion showed poorly differentiated rhabdoid-like disseminated tumor cells. The patient went on to develop lesions in the peritoneum, infratemporal fossa, and along the lumbosacral nerve roots.

CONCLUSION

This unique case illustrates the aggressive behavior of H3 K27-altered tumors and their potential to metastasize.

Immunotherapy approaches for the treatment of diffuse midline gliomas

Diffuse midline gliomas (DMG) are a highly aggressive and universally fatal subgroup of pediatric tumors responsible for the majority of childhood brain tumor deaths. Median overall survival is less than 12 months with a 90% mortality rate at 2 years from diagnosis. Research into the underlying tumor biology and numerous clinical trials have done little to change the invariably poor prognosis. Continued development of novel, efficacious therapeutic options for DMGs remains a critically important area of active investigation. Given that DMGs are not amenable to surgical resection, have only limited response to radiation, and are refractory to traditional chemotherapy, immunotherapy has emerged as a promising alternative treatment modality. This review summarizes the various immunotherapy-based treatments for DMG as well as their specific limitations. We explore the use of cell-based therapies, oncolytic virotherapy or immunovirotherapy, immune checkpoint inhibition, and immunomodulatory vaccination strategies, and highlight the recent clinical success of anti-GD2 CAR-T therapy in diffuse intrinsic pontine glioma (DIPG) patients. Finally, we address the challenges faced in translating preclinical and early phase clinical trial data into effective standardized treatment for DMG patients.

Leptomeningeal and subependymal seeding of diffuse intrinsic pontine glioma: a case report

DIPG (diffuse intrinsic pontine glioma) is a deadly cancerous tumor of the brainstem that spreads across the pons. The tumor's infiltrative nature, as well as the tumor's critical pathway and nuclei compression, contributes to the tumor's extremely poor prognosis and limited existing therapeutic options. A previous study revealed that in 40 patients with brainstem glioma, 13 (33%) patients had leptomeningeal spreading. In this paper, we reported a 7-year-old female patient who presented with a history of decreased consciousness and weakness of the right limb. Her magnetic resonance imaging (MRI) revealed a pontine mass. She was given 35 fractions of 54 Gy whole-brain radiotherapy. The post-radiotherapy MRI evaluation showed multiple nodules in periventricular region, and was suggestive of leptomeningeal and subependymal seeding of the pontine glioma in the lateral ventricles. This case report elucidated the leptomeningeal seeding in a pediatric patient with diffuse intrinsic pontine glioma.

Leptomeningeal disease and tumor dissemination in a murine diffuse intrinsic pontine glioma model: implications for the study of the tumor-cerebrospinal fluid-ependymal microenvironment

Background

Leptomeningeal disease and hydrocephalus are present in up to 30% of patients with diffuse intrinsic pontine glioma (DIPG), however there are no animal models of cerebrospinal fluid (CSF) dissemination. As the tumor-CSF-ependymal microenvironment may play an important role in tumor pathogenesis, we identified characteristics of the Nestin-tumor virus A (Nestin-Tva) genetically engineered mouse model that make it ideal to study the interaction of tumor cells with the CSF and its associated pathways with implications for the development of treatment approaches to address CSF dissemination in DIPG.

Methods

A Nestin-Tva model of DIPG utilizing the 3 most common DIPG genetic alterations (H3.3K27M, PDGF-B, and p53) was used for this study. All mice underwent MR imaging and a subset underwent histopathologic analysis with H&E and immunostaining.

Results

Tumor dissemination within the CSF pathways (ventricles, leptomeninges) from the subependyma was present in 76% (25/33) of mice, with invasion of the choroid plexus, disruption of the ciliated ependyma and regional subependymal fluid accumulation. Ventricular enlargement consistent with hydrocephalus was present in 94% (31/33). Ventricle volume correlated with region-specific transependymal CSF flow (periventricular T2 signal), localized anterior to the lateral ventricles.

Conclusions

This is the first study to report CSF pathway tumor dissemination associated with subependymal tumor in an animal model of DIPG and is representative of CSF dissemination seen clinically. Understanding the CSF-tumor-ependymal microenvironment has significant implications for treatment of DIPG through targeting mechanisms of tumor spread within the CSF pathways.

Pediatric midline H3K27M-mutant tumor with disseminated leptomeningeal disease and glioneuronal features: case report and literature review

BACKGROUND

H3K27M-mutant midline lesions were recently reclassified by the World Health Organization (WHO) as "diffuse midline glioma" (DMG) based entirely on their molecular signature. DMG is one of the most common and most lethal pediatric brain tumors; terminal progression is typically caused by local midbrain or brainstem progression, or secondary leptomeningeal dissemination. H3K27M mutations have also been infrequently associated with a histologically and prognostically diverse set of lesions, particularly spinal masses with early leptomeningeal spread.

CASE PRESENTATION

A 15-year-old girl after 1 week of symptoms was found to have a T2/FLAIR-hyperintense and contrast-enhancing thalamic mass accompanied by leptomeningeal enhancement along the entire neuraxis. Initial infectious workup was negative, and intracranial biopsy was inconclusive. Spinal arachnoid biopsy revealed an H3K27M-mutant lesion with glioneuronal features, classified thereafter as DMG. She received craniospinal irradiation with a boost to the thalamic lesion. Imaging 1-month post-radiation demonstrated significant treatment response with residual enhancement at the conus.

CONCLUSIONS

This case report describes the unique presentation of an H3K27M-mutant midline lesion with significant craniospinal leptomeningeal spread on admission and atypical glioneuronal histopathological markers. With such florid leptomeningeal disease, spinal dural biopsy should be considered earlier given its diagnostic yield in classifying the lesion as DMG. Consistent with similar prior reports, this lesion additionally demonstrated synaptophysin positivity-also potentially consistent with a diagnosis of diffuse leptomeningeal glioneuronal tumor (DLGNT). In atypical DMG cases, particularly with leptomeningeal spread, further consideration of clinical and histopathological context is necessary for accurate diagnosis and prognostication.

Case series of diffuse extraneural metastasis in H3F3A mutant high-grade gliomas: Clinical, molecular phenotype and literature review

H3K27M and H3.3G34R/V mutations have been identified in pediatric high-grade gliomas (pHGG), though extraneural metastases are rarely reported and poorly characterized. Three pHGG patients from two institutions were identified with extraneural metastasis, harboring histone mutations. Their clinical, imaging and molecular characteristics are reported here. A 17-year old female presented with supratentorial H3.3G34R-mutant glioma with metastatic osseous lesions in the spine, pelvis, bone marrow, pleural effusion and soft tissue of pelvis. Bone marrow biopsy and soft tissue of pelvis biopsy showed neoplastic cells positive for P53. A 20-year old female was diagnosed with H3F3A H3K27M-mutant thalamic glioma. She developed diffuse sclerotic osseous lesions. Biopsy of an osseous lesion was non-diagnostic. A 17-year old female presented with a H3F3A H3K27M-mutant diffuse midline glioma with diffuse spinal cord metastasis. She further developed multifocal chest lymphadenopathy, pleural effusions, and a soft tissue mass in the abdominal wall. The latter was positive for H3K27M mutation. We present the first case series of pHGG with H3F3A mutation and diffuse extraneural dissemination, describing their clinical and molecular profile.

MR imaging features of diffuse intrinsic pontine glioma and relationship to overall survival: report from the International DIPG Registry

BACKGROUND

This study describes imaging features of diffuse intrinsic pontine glioma (DIPG) and correlates with overall survival (OS) and histone mutation status in the International DIPG Registry (IDIPGR).

METHODS

Four hundred cases submitted to the IDIPGR with a local diagnosis of DIPG and baseline MRI were evaluated by consensus review of 2 neuroradiologists; 43 cases were excluded (inadequate imaging or alternative diagnoses). Agreement between reviewers, association with histone status, and univariable and multivariable analyses relative to OS were assessed.

RESULTS

On univariable analysis imaging features significantly associated with worse OS included: extrapontine extension, larger size, enhancement, necrosis, diffusion restriction, and distant disease. On central review, 9.5% of patients were considered not to have DIPG. There was moderate mean agreement of MRI features between reviewers. On multivariable analysis, chemotherapy, age, and distant disease were predictors of OS. There was no difference in OS between wild-type and H3 mutated cases. The only imaging feature associated with histone status was the presence of ill-defined signal infiltrating pontine fibers.

CONCLUSIONS

Baseline imaging features are assessed in the IDIPGR. There was a 9.5% discordance in DIPG diagnosis between local and central review, demonstrating need for central imaging confirmation for prospective trials. Although several imaging features were significantly associated with OS (univariable), only age and distant disease were significant on multivariable analyses. There was limited association of imaging features with histone mutation status, although numbers are small and evaluation exploratory.

Dissemination Patterns and Short-Term Management of Multifocal Rosette-Forming Glioneuronal Tumors

BACKGROUND

Multifocal rosette-forming glioneuronal tumors (RGNTs) are challenging to manage. Gross total resection is often impossible, and data on adjunctive therapies are limited. We reviewed cases of multifocal RGNTs in the literature with special focus on dissemination patterns and management.

METHODS

A literature review was conducted using PubMed and the key words "(multifocal OR multicentric OR satellite OR dissemination) AND glioneuronal."

RESULTS

There were 21 cases of multifocal RGNTs identified. Follow-up was available in 18 cases at a median of 17 months. Progression-free survival and overall survival at 1 year were 84% and 94%, respectively. Of all cases, 43% had cerebrospinal fluid (CSF) dissemination, 48% had intraparenchymal spread, and 10% had both. The presence of CSF dissemination led to palliative care and/or death in 20% of cases (n = 2). None of the cases with intraparenchymal spread progressed. Radiotherapy was used in 50% of cases with CSF dissemination, chemotherapy was used in 20%, and CSF shunting was used in 36%. No tumors with intraparenchymal spread required adjunctive therapy or shunting.

CONCLUSIONS

RGNTs with CSF dissemination are more likely to behave aggressively, and early adjunctive therapies should be discussed with patients. Tumors with intraparenchymal spread grow slowly, and maximal safe resection followed by observation is likely sufficient in the short term. Long-term behavior of multifocal RGNTs is still unclear.

Diffuse intrinsic pontine glioma: current insights and future directions

Diffuse intrinsic pontine glioma (DIPG) is a lethal pediatric brain tumor and the leading cause of brain tumor–related death in children. As several clinical trials over the past few decades have led to no significant improvements in outcome, the current standard of care remains fractionated focal radiation. Due to the recent increase in stereotactic biopsies, tumor tissue availabilities have enabled our advancement of the genomic and molecular characterization of this lethal cancer. Several groups have identified key histone gene mutations, genetic drivers, and methylation changes in DIPG, providing us with new insights into DIPG tumorigenesis. Subsequently, there has been increased development of in vitro and in vivo models of DIPG which have the capacity to unveil novel therapies and strategies for drug delivery. This review outlines the clinical characteristics, genetic landscape, models, and current treatments and hopes to shed light on novel therapeutic avenues and challenges that remain.

Spinal Drop Metastasis of Glioblastoma-Two Case Reports, Clinicopathologic Features, Current Modalities of Evaluation, and Treatment with a Review of the Literature

BACKGROUND

Glioblastomas (World Health Organization grade IV) are aggressive primary neoplasms of the central nervous system. Spinal metastasis occurs supposedly in 2%-5% of patients. This percentage may be only the tip of iceberg because most succumb to the disease before clinical detection and few documented cases are reported.

CASE DESCRIPTIONS

A 45-year-old man presented with history of diplopia and gait disturbance. Magnetic resonance imaging showed a left cerebellar space-occupying lesion. The histopathology was consistent with glioblastoma. The patient underwent adjuvant chemoradiation. A year later, he presented with seizures, worsening headache, neck stiffness, and low back pain. Imaging showed metastasis to the S1/S2 region of the spinal canal. A 29-year-old man presented with episodic headaches associated with nausea, vomiting, neck stiffness, and imbalance while walking. Computed tomography of the brain showed a hypodense lesion involving the left midbrain, pons, and left middle cerebellar peduncle, causing fourth ventricular pressure with obstructive hydrocephalus. A navigation-guided biopsy of the brainstem lesion confirmed the diagnosis of glioblastoma World Health Organization grade IV, isocitrate dehydrogenase 1 (R132 H) and H3K27M negative. Isocitrate dehydrogenase gene sequencing was suggested. The patient was referred for chemoradiation. During treatment, he worsened neurologically and developed axial neck and back pain. Neuraxis screening showed disseminated leptomeningeal spread, which was confirmed on dural biopsy.

CONCLUSIONS

Spinal and dural metastasis should always be suspected in patients with glioblastoma with signs and symptoms not explained by primary lesion. A regular protocol with postcontrast magnetic resonance imaging before and after initial surgery is mandatory to detect spinal metastasis before it becomes clinically apparent, thereby improving the prognosis and quality of life in patients.

Response assessment in diffuse intrinsic pontine glioma: recommendations from the Response Assessment in Pediatric Neuro-Oncology (RAPNO) working group

Optimising the conduct of clinical trials for diffuse intrinsic pontine glioma involves use of consistent, objective disease assessments and standardised response criteria. The Response Assessment in Pediatric Neuro-Oncology working group, consisting of an international panel of paediatric and adult neuro-oncologists, clinicians, radiologists, radiation oncologists, and neurosurgeons, was established to address issues and unique challenges in assessing response in children with CNS tumours. A working group was formed specifically to address response assessment in children and young adults with diffuse intrinsic pontine glioma and to develop a consensus on recommendations for response assessment. Response should be assessed using MRI of brain and spine, neurological examination, and anti-inflammatory or antiangiogenic drugs. Clinical imaging standards are defined. As with previous consensus recommendations, these recommendations will need to be validated in prospective clinical trials.

Invaders Exposed: Understanding and Targeting Tumor Cell Invasion in Diffuse Intrinsic Pontine Glioma

Diffuse Intrinsic Pontine Glioma (DIPG) is a rare, highly aggressive pediatric brain tumor that originates in the pons. DIPG is untreatable and universally fatal, with a median life expectancy of less than a year. Resection is not an option, due to the anatomical location of the tumor, radiotherapy has limited effect and no chemotherapeutic or targeted treatment approach has proven to be successful. This poor prognosis is partly attributed to the tumor's highly infiltrative diffuse and invasive spread. Thus, targeting the invasive behavior of DIPG has the potential to be of therapeutic value. In order to target DIPG invasion successfully, detailed mechanistic knowledge on the underlying drivers is required. Here, we review both DIPG tumor cell's intrinsic molecular processes and extrinsic environmental factors contributing to DIPG invasion. Importantly, DIPG represents a heterogenous disease and through advances in whole-genome sequencing, different subtypes of disease based on underlying driver mutations are now being recognized. Recent evidence also demonstrates intra-tumor heterogeneity in terms of invasiveness and implies that highly infiltrative tumor subclones can enhance the migratory behavior of neighboring cells. This might partially be mediated by “tumor microtubes,” long membranous extensions through which tumor cells connect and communicate, as well as through the secretion of extracellular vesicles. Some of the described processes involved in invasion are already being targeted in clinical trials. However, more research into the mechanisms of DIPG invasion is urgently needed and might result in the development of an effective therapy for children suffering from this devastating disease. We discuss the implications of newly discovered invasive mechanisms for therapeutic targeting and the challenges therapy development face in light of disease in the developing brain.

Defining Optimal Target Volumes of Conformal Radiation Therapy for Diffuse Intrinsic Pontine Glioma

PURPOSE

Optimal radiation therapy (RT) target margins for diffuse intrinsic pontine glioma (DIPG) are unknown. We sought to define disease progression patterns in a contemporary cohort treated with conformal RT using different clinical target volume (CTV) margins.

METHODS AND MATERIALS

We reviewed 105 patients with newly diagnosed DIPG treated with conformal conventionally fractionated RT at our institution from 2006 to 2014. CTV margins were classified as standard (1 cm) for 60 patients and extended (2-3 cm) for 45 patients. Survival and cumulative incidence of progression in treatment groups were compared by log-rank and Gray's tests, respectively. Cox proportional hazard models identified predictors of survival.

RESULTS

For 97 patients evaluated with magnetic resonance imaging at progression, the cumulative incidences of isolated local, isolated distant, and synchronous disease progression at 1 year were 62.6%, 12.3%, and 7.2%, respectively, and did not differ significantly according to the CTV margin. Central dosimetric progression (V_progression95% ≥95%) was observed in 80 of 81 evaluable patients. Median progression-free survival and overall survival (OS) were 7.6 months (95% confidence interval, 6.9-8.2) and 11.3 months (95% confidence interval, 10.0-12.8), respectively, and did not differ significantly according to margin status. DIPG survival prediction risk group (standard vs high, P = .02; intermediate vs high, P = .009) and development of distant metastasis (P = .003) were independent predictors of OS. For the 41 patients (39%) with a pathologic diagnosis, H3.3 K27M mutation was associated with shorter OS (hazard ratio [HR], 0.41; P =.02), whereas H3.1 K27M and ACVR1 mutations were associated with longer OS (HR, 3.56; P =.004 and HR, 2.58; P =.04, respectively).

CONCLUSIONS

All patients who experienced local failure showed progression within the high-dose volume, and there was no apparent survival or tumor-control benefit to extending the CTV margins beyond 1 cm. Given the increasing use of reirradiation, standardizing the CTV margin to 1 cm may improve retreatment tolerance.

Neuraxis Metastases Of Primary Central Nervous System Tumors: A Review Of Clinicopathological And Radiographic Characters Of 198 Cases In A Single Center

BACKGROUND

Neuraxis metastases (NM) from systemic and central nervous system (CNS) tumors have become increasingly common. However, a lack of systematic information restricts the development of the accurate diagnosis and treatment. The aim of this study is to facilitate the understanding of NM arising from CNS tumors in the largest cohort.

METHODS

Based on the clinicopathological and neuroimaging findings, we retrospectively analyze the epidemiological characters, radiographic classification, therapeutic strategies and prognostic factors.

RESULTS

A total of 198 cases are enrolled and the most common primary tumor is medulloblastoma (34.34%). The median age is 15.0 years and the majority of NM (79.29%) occur in the children and young adult groups. One hundred and forty-nine (75.25%) cases suffer from intracranial metastases, and 169 (85.35%) have intraspinal NM. The whole leptomeninges and cauda equine are the most preferential disseminated sites. Upon MRI parameters, the massive and miliary subgroup occurs most frequently in the intracranial and intraspinal NM, respectively. Treatment includes surgery (21.71%), chemotherapy alone (19.19%), radiation alone (10.10%) and combined therapy (55.56%). Operations are performed in order to identify pathology and relive masses, as well as the triple chemotherapeutic scheme consisting of ifosfamide, carboplatin and etoposide is recommended for most of NM. The median overall survival is 11.6 months. Younger age, coexistence of NM with primary tumors, shorter interval from primaries to metastases, glioma, leptomeningeal seeding and nodal subtype on MRI significantly correlate with poor prognosis.

CONCLUSION

In spite of controversial therapies and poor outcomes, the neuroimaging classification and comprehensive treatment contribute to the efficient administration of NM.

Diffuse intrinsic pontine glioma ventricular peritoneal shunt metastasis: a case report and literature review

Dissemination of diffuse intrinsic pontine glioma (DIPG) outside the central nervous system is exceptional. Here, we present a child diagnosed with DIPG who developed seeding along the track of the ventriculoperitoneal shunt and review the literature on this unusual occurrence.

A machine learning-based prediction model of H3K27M mutations in brainstem gliomas using conventional MRI and clinical features

BACKGROUND

H3K27M is the most frequent mutation in brainstem gliomas (BSGs), and it has great significance in the differential diagnosis, prognostic prediction and treatment strategy selection of BSGs. There has been a lack of reliable noninvasive methods capable of accurately predicting H3K27M mutations in BSGs.

METHODS

A total of 151 patients with newly diagnosed BSGs were included in this retrospective study. The H3K27M mutation status was obtained by whole-exome, whole-genome or Sanger's sequencing. A total of 1697 features, including 6 clinical parameters and 1691 imaging features, were extracted from pre- and post-contrast T1-weighted and T2-weighted images. Using a random forest algorithm, 36 selected MR image features were integrated with 3 selected clinical features to generate a model that was predictive of H3K27M mutations. Additionally, a simplified prediction model comprising the Karnofsky Performance Status (KPS) at diagnosis, symptom duration at diagnosis and edge sharpness on T2 was established for practical clinical utility using the least squares estimation method.

RESULTS

H3K27M mutation was an independent prognostic factor that conferred a worse prognosis (p = 0.01, hazard ratio = 3.0, 95% confidence interval [CI], 1.57-5.74). The machine learning-based model achieved an accuracy of 84.44% (area under the curve [AUC] = 0.8298) in the test cohort. The simplified model achieved an AUC of 0.7839 in the test cohort.

CONCLUSIONS

Using conventional MRI and clinical features, we established a machine learning-based model with high accuracy and a simplified model with improved clinical utility to predict H3K27M mutations in BSGs.

Beyond the Blood:Brain Barrier: The Importance of Central Nervous System (CNS) Pharmacokinetics for the Treatment of CNS Tumors, Including Diffuse Intrinsic Pontine Glioma

Over the past decade, we have made considerable progress in establishing diffuse intrinsic pontine glioma (DIPG) as a disease entity and developing preclinical tools to interrogate potential therapeutics. However, translation to improved clinical outcomes in children with DIPG has not yet been realized. This is in part due to difficulties encountered in delivering active drugs adequately to the tumor site. However, most preclinical evaluations gloss over the fundamental concepts of central nervous system (CNS) pharmacokinetics and requirements needed to optimize drug delivery and exposure and translate this into efficacious therapy. This article discusses not only the blood:brain barriers but additional barriers to drug delivery for CNS tumors and pharmacokinetic principles that need to be addressed and considered.

Histological and molecular analysis of a progressive diffuse intrinsic pontine glioma and synchronous metastatic lesions: a case report

There is no curative treatment for patients with diffuse intrinsic pontine glioma (DIPG). However, with the recent availability of biopsy and autopsy tissue, new data regarding the biologic behavior of this tumor have emerged, allowing greater molecular characterization and leading to investigations which may result in improved therapeutic options. Treatment strategies must address both primary disease sites as well as any metastatic deposits, which may be variably sensitive to a particular approach.

In this case report, we present a patient with DIPG treated with irradiation and serial investigational agents. The clinical, pathological and molecular phenotypes of both the progressive primary tumor as well as concomitant metastatic deposits obtained at autopsy are discussed. While some mRNA differences were demonstrated, all analyzed sites of disease shared similar mutational arrangements, suggesting that targeting the mutations of the primary tumor may be effective for all sites of disease.

Treatment-Related Noncontiguous Radiologic Changes in Children With Diffuse Intrinsic Pontine Glioma Treated With Expanded Irradiation Fields and Antiangiogenic Therapy

PURPOSE

We previously reported the cases of 3 children with diffuse intrinsic pontine glioma (DIPG) in whom noncontiguous treatment-related abnormalities (NCTRAs) developed in the brain after expanded-field radiation therapy (RT). To investigate the occurrence and putative mechanism of NCTRAs, we reviewed brain magnetic resonance imaging studies of patients with DIPG treated in 2 consecutive phase I clinical trials (trials 1 and 2).

METHODS AND MATERIALS

The 55 children included in these trials received small-molecule inhibitors: vandetanib in trial 1 (n=32; mean age 6.4 years) and vandetanib and dasatinib in trial 2 (n=23; mean age 5.8 years). The patients also received conformal 3-dimensional RT (cumulative dose 54 Gy). For patients enrolled in trial 1, the clinical target volume (CTV) was expanded by 1 cm from the gross tumor volume. In trial 2, the expansion to form the CTV was 2 to 3 cm. A review of imaging studies was performed from the initial diagnosis through the end of progression-free survival. The imaging findings were grouped into 5 categories according to the presence, absence, location, extent, and putative mechanism of NCTRAs. Statistical analysis was performed to evaluate the association between covariates and NCTRA, cohort characterization, and survival comparisons.

RESULTS

Overall survival was similar in both studies (P=.74). NCTRAs developed in 9 patients (39%) treated in trial 2 but in none treated in trial 1. The NCTRAs included T2-weighted hyperintensities with (n=3; radiation necrosis) or without (n=5) contrast uptake, supratentorial leukoencephalopathy (n=2), and ischemic stroke (n=1). All NCTRAs, except for 1, occurred within the CTV. Compared with nonaffected patients, patients with a NCTRA were younger (P=.003) and had had larger relative brain volumes exposed to doses >20 Gy.

CONCLUSIONS

The imaging features of NCTRAs suggest that their development is secondary to synergistic steno-occlusive vascular effects induced by the combination of RT, an expanded CTV, potent antiangiogenic therapy, young age, and, in 1 case, a genetic predisposition.

Effective Drug Delivery in Diffuse Intrinsic Pontine Glioma: A Theoretical Model to Identify Potential Candidates

Despite decades of clinical trials for diffuse intrinsic pontine glioma (DIPG), patient survival does not exceed 10% at two years post-diagnosis. Lack of benefit from systemic chemotherapy may be attributed to an intact bloodbrain barrier (BBB). We aim to develop a theoretical model including relevant physicochemical properties in order to review whether applied chemotherapeutics are suitable for passive diffusion through an intact BBB or whether local administration via convection-enhanced delivery (CED) may increase their therapeutic potential. Physicochemical properties (lipophilicity, molecular weight, and charge in physiological environment) of anticancer drugs historically and currently administered to DIPG patients, that affect passive diffusion over the BBB, were included in the model. Subsequently, the likelihood of BBB passage of these drugs was ascertained, as well as their potential for intratumoral administration via CED. As only non-molecularly charged, lipophilic, and relatively small sized drugs are likely to passively diffuse through the BBB, out of 51 drugs modeled, only 8 (15%)-carmustine, lomustine, erlotinib, vismodegib, lenalomide, thalidomide, vorinostat, and mebendazole-are theoretically qualified for systemic administration in DIPG. Local administration via CED might create more therapeutic options, excluding only positively charged drugs and drugs that are either prodrugs and/or only available as oral formulation. A wide variety of drugs have been administered systemically to DIPG patients. Our model shows that only few are likely to penetrate the BBB via passive diffusion, which may partly explain the lack of efficacy. Drug distribution via CED is less dependent on physicochemical properties and may increase the therapeutic options for DIPG.

Rapid and fulminant leptomeningeal spread following radiotherapy in diffuse intrinsic pontine glioma

A 4-year-old male presented with rapid-onset cranial nerve palsy and ataxia. Brain magnetic resonance imaging (MRI) revealed a pontine mass lesion with discordant conventional and advanced imaging. A stereotactic core biopsy revealed glioblastoma with immunostaining suggestive of histone H3K27M and TP53 mutation, consistent with diffuse intrinsic pontine glioma. MRI 3 months after radiotherapy revealed extensive new leptomeningeal metastatic disease involving both the supra- and infratentorial brain, as well as the imaged portion of the spine. Tissue procured at the time of needle biopsy has undergone striking in vivo expansion as an orthotopic xenograft.

Adult Brain Tumors and Pseudotumors: Interesting (Bizarre) Cases

Some brain tumors results are interesting due to their rarity at presentation and overwhelming imaging characteristics, posing a diagnostic challenge in the eyes of any experienced neuroradiologist. This article focuses on the most important features regarding epidemiology, location, clinical presentation, histopathology, and imaging findings of cases considered "bizarre." A review of the most recent literature dealing with these unusual tumors and pseudotumors is presented, highlighting key points related to the diagnosis, treatments, outcomes, and differential diagnosis.

Diffuse Intrinsic Pontine Glioma: New Pathophysiological Insights and Emerging Therapeutic Targets

Abstract: Background

Diffuse Intrinsic Pontine Glioma (DIPG) is the leading cause of brain tumor-related death in children, with median survival of less than one year. Despite decades of clinical trials, there has been no improvement in prognosis since the introduction of radiotherapy over thirty years ago.

Objective

To review the clinical features and current treatment challenges of DIPG, and discuss emerging insights into the unique genomic and epigenomic mechanisms driving DIPG pathogenesis that present new opportunities for the identification of therapeutic targets.

Conclusion

In recent years, an increased availability of biopsy and rapid autopsy tissue samples for preclinical investigation has combined with the advent of new genomic and epigenomic profiling tools to yield remarkable advancements in our understanding of DIPG disease mechanisms. As well, a deeper understanding of the developmental context of DIPG is shedding light on therapeutic targets in the microenvironment of the childhood brain.

Spatial genomic heterogeneity in diffuse intrinsic pontine and midline high-grade glioma: implications for diagnostic biopsy and targeted therapeutics

Introduction

Diffuse intrinsic pontine glioma (DIPG) and midline high-grade glioma (mHGG) are lethal childhood brain tumors. Spatial genomic heterogeneity has been well-described in adult HGG but has not been comprehensively characterized in pediatric HGG. We performed whole exome sequencing on 38-matched primary, contiguous, and metastatic tumor sites from eight children with DIPG (n = 7) or mHGG (n = 1) collected using a unique MRI-guided autopsy protocol. Validation was performed using Sanger sequencing, Droplet Digital polymerase-chain reaction, immunohistochemistry, and fluorescent in-situ hybridization.

Results

Median age at diagnosis was 6.1 years (range: 2.9–23.3 years). Median overall survival was 13.2 months (range: 11.2–32.2 months). Contiguous tumor infiltration and distant metastases were observed in seven and six patients, respectively, including leptomeningeal dissemination in three DIPGs. Histopathological heterogeneity was evident in seven patients, including intra-pontine heterogeneity in two DIPGs, ranging from World Health Organization grade II to IV astrocytoma. We found conservation of heterozygous K27M mutations in H3F3A (n = 4) or HIST1H3B (n = 3) across all primary, contiguous, and metastatic tumor sites in all DIPGs. ACVR1 (n = 2), PIK3CA (n = 2), FGFR1 (n = 2), and MET (n = 1) were also intra-tumorally conserved. ACVR1 was co-mutated with HIST1H3B (n = 2). In contrast, PDGFRA amplification and mutation were spatially heterogeneous, as were mutations in BCOR (n = 1), ATRX (n = 2), and MYC (n = 1). TP53 aberrations (n = 3 patients) varied by type and location between primary and metastatic tumors sites but were intra-tumorally conserved.

Conclusion

Spatial conservation of prognostically-relevant and therapeutically-targetable somatic mutations in DIPG and mHGG contrasts the significant heterogeneity of driver mutations seen in adult HGG and supports uniform implementation of diagnostic biopsy in DIPG and mHGG to classify molecular risk groups and guide therapeutic strategy.

Electronic supplementary material

The online version of this article (doi:10.1186/s40478-015-0269-0) contains supplementary material, which is available to authorized users.

DIPG in Children - What Can We Learn from the Past?

Brainstem tumors represent 10–15% of pediatric central nervous system tumors and diffuse intrinsic pontine glioma (DIPG) is the most common brainstem tumor of childhood. DIPG is almost uniformly fatal and is the leading cause of brain tumor-related death in children. To date, radiation therapy (RT) is the only form of treatment that offers a transient benefit in DIPG. Chemotherapeutic strategies including multi-agent neoadjuvant chemotherapy, concurrent chemotherapy with RT, and adjuvant chemotherapy have not provided any survival advantage. To overcome the restrictive ability of the intact blood–brain barrier (BBB) in DIPG, several alternative drug delivery strategies have been proposed but have met with minimal success. Targeted therapies either alone or in combination with RT have also not improved survival. Five decades of unsuccessful therapies coupled with recent advances in the genetics and biology of DIPG have taught us several important lessons (1). DIPG is a heterogeneous group of tumors that are biologically distinct from other pediatric and adult high grade gliomas (HGG). Adapting chemotherapy and targeted therapies that are used in pediatric or adult HGG for the treatment of DIPG should be abandoned (2). Biopsy of DIPG is relatively safe and informative and should be considered in the context of multicenter clinical trials (3). DIPG probably represents a whole brain disease so regular neuraxis imaging is important at diagnosis and during therapy (4). BBB permeability is of major concern in DIPG and overcoming this barrier may ensure that drugs reach the tumor (5). Recent development of DIPG tumor models should help us accurately identify and validate therapeutic targets and small molecule inhibitors in the treatment of this deadly tumor.

Diffuse intrinsic pontine gliomas: treatments and controversies

Diffuse intrinsic pontine gliomas (DIPGs) are a fairly common pediatric brain tumor, and children with these tumors have a dismal prognosis. They generally are diagnosed within the first decade of life, and due to their location within the pons, these tumors are not surgically resectable. The median survival for children with DIPGs is less than 1 year, in spite of decades of clinical trial development of unique approaches to radiation therapy and chemotherapy. Novel therapies are under investigation for these deadly tumors. As clinicians and researchers make a concerted effort to obtain tumor tissue, the molecular signals of these tumors are being investigated in an attempt to uncover targetable therapies for DIPGs. In addition, direct application of chemotherapies into the tumor (convection-enhanced delivery) is being investigated as a novel delivery system for treatment of DIPGs. Overall, DIPGs require creative thinking and a disciplined approach for development of a therapy that can improve the prognosis for these unfortunate children.

Anaplastic ganglioglioma: a report of three cases and review of the literature

Gangliogliomas are rare tumors of the central nervous system that are thought to arise from a glioneuronal precursor and consist of both neuronal and glial elements. Grade III, or anaplastic ganglioglioma (AGG), most commonly affects children and young adults, generally arises in a supratentorial location, is highly epileptogenic, and often results in diffuse local and distant failure within the craniospinal axis. Pathologically, these tumors are graded by the degree of malignancy in their glial portion and radiologic diagnosis is difficult due to the wide variation in its degree of solid and cystic components, contrast uptake, and calcification patterns. This report presents three cases of AGG, with initial treatment including subtotal resection followed by conformal radiotherapy. In the case where the AGG developed in the setting of an existent low-grade astrocytoma, the patient received no chemotherapy. Both of the other de novo cases were managed with adjuvant chemoradiotherapy with temozolomide. Recurrence occurred at 6, 16, and 20 months following therapy. Two of the three patients experienced symptomatic decline at recurrence, but experienced Karnofsky performance status (KPS) improvement after salvage therapy, including the reduction of cranial neuropathy and balance. All patients had a significant reduction in presenting symptoms following salvage therapy. Patients died at 23, 20, and 22 months following initial surgical management, respectively. A review of anaplastic and malignant gangliogliomas is presented in the context of these three cases.

Surgical approaches for brainstem tumors in pediatric patients

PURPOSE

To analyze the pathways to brainstem tumors in childhood, as well as safe entry zones.

METHOD

We conducted a retrospective study of 207 patients less than 18 years old who underwent brainstem tumor resection by the first author (Cavalheiro, S.) at the Neurosurgical Service and Pediatric Oncology Institute of the São Paulo Federal University from 1991 to 2011.

RESULTS

Brainstem tumors corresponded to 9.1 % of all pediatric tumors operated in that same period. Eleven previously described "safe entry zones" were used. We describe a new safe zone located in the superior ventral pons, which we named supratrigeminal approach. The operative mortality seen in the first 2 months after surgery was 1.9 % (four patients), and the morbidity rate was 21.2 %.

CONCLUSIONS

Anatomic knowledge of intrinsic and extrinsic brainstem structures, in association with a refined neurosurgical technique assisted by intraoperative monitoring, and surgical planning based on magnetic resonance imaging (MRI) and tractography have allowed for wide resection of brainstem lesions with low mortality and acceptable morbidity rates.

Children are not just little adults: recent advances in understanding of diffuse intrinsic pontine glioma biology

Diffuse intrinsic pontine glioma (DIPG) is a high-grade glioma that originates in the pons and is seen exclusively in children. Despite numerous efforts to improve treatment, DIPG remains incurable with 90% of children dying within 2 y of diagnosis, making it one of the leading causes of death in children with brain tumors. With the advent of new genomic tools, the genetic landscape of DIPG is slowly being unraveled. The most common genetic alterations include a K27M mutation in H3.3 or H3.1, which are found in up to 78% of DIPGs, whereas p53 mutations are found in up to 77%. Other recently discovered alterations include amplification of components of the receptor tyrosine kinase/Ras/phosphatidylinositol 3-kinase signaling pathway, particularly platelet-derived growth factor receptor A. Recapitulating such alterations, genetically engineered DIPG preclinical models have been developed, and DIPG xenograft models have also been established. Both models have strengths and weaknesses but can help with the prioritization of novel agents for clinical trials for children with DIPG. As we move forward, it is important that we continue to study the complex and unique biology of DIPG and develop improved preclinical models to increase our understanding of DIPG pathogenesis, allowing translation into successful therapies in the not too distant future.

Implementation of a multi-institutional diffuse intrinsic pontine glioma autopsy protocol and characterization of a primary cell culture

AIMS

Diffuse intrinsic pontine glioma (DIPG) is a fatal paediatric malignancy. Tumour resection is not possible without serious morbidity and biopsies are rarely performed. The resulting lack of primary DIPG material has made preclinical research practically impossible and has hindered the development of new therapies for this disease. The aim of the current study was to address the lack of primary DIPG material and preclinical models by developing a multi-institutional autopsy protocol.

METHODS

An autopsy protocol was implemented in the Netherlands to obtain tumour material within a brief post mortem interval. A team of neuropathologists and researchers was available at any time to perform the autopsy and process the material harvested. Whole brain autopsy was performed and primary DIPG material and healthy tissue were collected from all affected brain areas. Finally, the study included systematic evaluation by parents.

RESULTS

Five autopsies were performed. The mean time interval between death and time of autopsy was 3 h (range 2-4). All tumours were graded as glioblastoma. None of the parents regretted their choice to participate, and they all derived comfort in donating tissue of their child in the hope to help future DIPG patients. In addition, we developed and characterized one of the first DIPG cell cultures from post mortem material.

CONCLUSION

Here we show that obtaining post mortem DIPG tumour tissue for research purposes is feasible with short delay, and that the autopsy procedure is satisfying for participating parents and can be suitable for the development of preclinical DIPG models.

Diffuse intrinsic pontine glioma: poised for progress

Diffuse intrinsic pontine gliomas (DIPGs) are amongst the most challenging tumors to treat. Surgery is not an option, the effects of radiation therapy are temporary, and no chemotherapeutic agent has demonstrated significant efficacy. Numerous clinical trials of new agents and novel therapeutic approaches have been performed over the course of several decades in efforts to improve the outcome of children with DIPG, yet without success. The diagnosis of DIPG is based on radiographic findings in the setting of a typical clinical presentation, and tissue is not routinely obtained as the standard of care. The paradigm for treating children with these tumors has been based on that for supratentorial high-grade gliomas in adults as the biology of these lesions were presumed to be similar. However, recent pivotal studies demonstrate that DIPGs appear to be their own entity. Simply identifying this fact releases a number of constraints and opens opportunities for biologic investigation of these lesions, setting the stage to move forward in identifying DIPG-specific treatments. This review will summarize the current state of knowledge of DIPG, discuss obstacles to therapy, and summarize results of recent biologic studies.

Adult brainstem gliomas

Brainstem gliomas are uncommon in adults and account for only 1%-2% of intracranial gliomas. They represent a heterogeneous group of tumors that differ from those found in their pediatric counterparts. In adults, a low-grade phenotype predominates, which is a feature that likely explains their better prognosis compared to that in children. Because biopsies are rarely performed, classifications based on the radiological aspect of magnetic resonance imaging results have been proposed to establish treatment strategies and to determine outcomes: (a) diffuse intrinsic low-grade, (b) enhancing malignant glioma, (c) focal tectal gliomas, and (d) exophytic gliomas. Despite significant advances in neuroradiology techniques, a purely radiological classification remains imperfect in the absence of a histological diagnosis. Whereas a biopsy may often be reasonably avoided in the diffuse nonenhancing forms, obtaining histological proof seems necessary in many contrast-enhanced brainstem lesions because of the wide variety of differential diagnoses in adults. Conventional radiotherapy is the standard treatment for diffuse intrinsic low-grade brainstem gliomas in adults (the median survival is 5 years). In malignant brainstem gliomas, radiotherapy is the standard treatment. However, the possible benefit of combined radiotherapy and chemotherapy (temozolomide or other agents) has not been thoroughly evaluated in adults. The role of anti-angiogenic therapies in brainstem gliomas remains to be defined. A better understanding of the biology of these tumors is of primary importance for identifying homogeneous subgroups and for improving therapy options and outcomes.

Diffuse intrinsic pontine glioma-current status and future strategies

INTRODUCTION

Diffuse intrinsic pontine gliomas which constitute 15% of all childhood brain tumors are inoperable and response to radiation and chemotherapy has not improved long-term survival. Due to lack of newer effective therapies, mean survival after diagnosis has remained less than 12 months. Trials investigating chemotherapy and/or radiation have proven disappointing. As biopsy of these tumors are rarely performed due to the high eloquence of the brain stem, information about the pathology and biology remains elusive hindering development of novel biologic agents. Poor access of most chemotherapeutic agents to these tumors due to the blood-brain barrier continues to undermine therapeutic efficacy. Thus, to date, we remain at a virtual standstill in our attempts to improve the prognosis of children with these tumors.

METHODS

An extensive review of the literature was performed concerning children with diffuse brain stem gliomas including clinical trials, evolving molecular biology, and newer therapeutic endeavors.

CONCLUSION

A pivotal approach in improving the prognosis of these tumors should include the initiation of biopsy and encouraging families to consider autopsy to study the molecular biology. This will help in redefining this tumor by its molecular signature and profiling targeted therapy. Continued advances should be pursued in neuroimaging technology including identifying surrogate markers of early disease progression. Defining strategies to enhance local delivery of drugs into tumors with the help of newer surgical techniques are important. Exhaustive research in all these aspects as a multidisciplinary approach could provide hope to children with these fatal tumors.

Radiotherapy with concurrent and adjuvant temozolomide in children with newly diagnosed diffuse intrinsic pontine glioma

The purpose of this study is to evaluate the efficacy and toxicity of radiation therapy (RT) with concurrent temozolomide (TMZ) chemotherapy followed by adjuvant TMZ in children with diffuse intrinsic pontine glioma (DIPG). Newly diagnosed patients younger than 18 years with histologically proven DIPG were treated with focal radiotherapy to a dose of 54 Gy in 30 fractions along with concurrent daily TMZ (75 mg/m(2)/day). Four weeks after completing the initial RT-TMZ schedule, adjuvant TMZ (200 mg/m(2)/day, days 1-5) was given every 28 days up to six cycles. Responses/progressions were assessed by clinical and 2-monthly MRI follow-up studies. Between September 2005 and September 2009, 21 patients with newly diagnosed histologically confirmed DIPG were eligible for this study. Median age at diagnosis was 6.4 years (range 4-16 years). At last update in August 2010, 17 children have died, 1 child was alive with progressive disease and 3 with stable disease. Metastatic relapse was documented in the cerebral site in two patients and in spinal cord in two cases. The median time to progression was 7.5 months (range 28 days-14.5 months) and the median survival was 11.7 months (range 26 days-17.5 months). The 1-year PFS and the 1-year OS were 33 and 50%, respectively. Five patients presented radiological findings compatible with pseudoprogression during the treatment. Haematological toxicity (Grade III/IV thrombocytopenia and leucopenia) was the most commonly found and led to dose reductions of TMZ in 58% of the patients. TMZ with radiation therapy has not yielded any significant improvement in outcome of children with DIPG and is associated with higher toxicity compared with radiotherapy alone. Novel treatment modalities are needed to improve the outcome of these patients.

Magnetic resonance spectroscopic detection of lactate is predictive of a poor prognosis in patients with diffuse intrinsic pontine glioma

Diffuse brainstem glioma has a poor prognosis, and there are few long-term survivors. We looked for clinical, conventional magnetic resonance (MR), and MR spectroscopic (MRS) findings predictive of the prognosis of patients with brainstem glioma. Our institutional review board approved this retrospective study of 23 patients with diffuse intrinsic pontine or diffuse medullary brainstem glioma treated during the period 2000-2009. To evaluate prognostic values, we performed a Kaplan-Meier survival analysis (log-rank test) that incorporated the patients' age and sex, symptom duration, the presence or absence of cranial nerve palsy, long tract sign, ataxia, and cysts, the chemotherapeutic regimen, Gd enhancement, longitudinal and cerebellar extension, basilar artery encasement, and MRS parameters. Of the 23 diffuse brainstem gliomas, 19 were located at the pons (ratio of male to female patients, 1.1:1). The mean age of the 23 patients was 15.9 years (range, 4-50 years); 16 were aged <20 years. The duration of overall survival was 19.7 months; in patients with diffuse intrinsic pontine glioma, it was 16.6 months, and in patients aged <20 years, it was 11.8 months. Clinical and conventional MR findings at presentation were not predictive of the prognosis in children with diffuse intrinsic pontine glioma. In addition, a patient age <20 years and the detection of lactate by MRS were poor prognostic factors. The MRS detection of lactate is a prognostic factor in patients with diffuse intrinsic pontine glioma. Additional studies of larger patient populations using other imaging modalities are needed.