Current therapy and the evolving molecular landscape of paediatric ependymoma

Sex Differences in Ependymoma Methylation by Methylation-Defined Subgroup

Ependymoma is the second most common malignant paediatric brain tumour composed of nine methylation-defined, clinically relevant subgroups. It is unclear if there are sex differences in methylation profiles within these subgroups which could guide future treatment options. We obtained available methylation data from the National Center for Biotechnology Information Gene Expression Omnibus (GEO). Differentially methylated probes (DMPs) between sexes were identified in each ependymoma sample and mapped to genes. Reactome pathways resulting from genes were identified. Survival was estimated for each sex within molecular subgroups. There were 492 cases included in the main analysis: PF-EPN-A (n = 238) PF-EPN-B (n = 52), PF-SE (n = 34), SP-MPE (n = 26), SP-EPN (n = 21), ST-EPN-RELA (n = 87), ST-EPN-YAP1 (n = 13) and ST-SE (n = 21). Females were observed to have better, but statistically nonsignificant, 5-year overall survival (OS) and better, marginally significant 5-year progression-free survival (PFS) than males. One subgroup, ST-EPN-RELA, showed significantly better OS in females. There was a difference in immune cell composition within tumour subgroups. One gene, RFTN1, was consistently differentially methylated by sex among all subgroups. There were biologic pathways identified from genes with differential methylation by sex in the following subgroups: PF-EPN-B, PF-SE, ST-EPN-RELA and ST-EPN-YAP1. Many of the identified pathways may be options for potential therapeutic targets.

Outcomes following management of relapsed pediatric posterior fossa ependymoma in the molecular era

PURPOSE

The overall survival and prognostic factors for children with multiply recurrent posterior fossa ependymoma are not well understood. We aimed to assess prognostic factors associated with survival for relapsed pediatric posterior fossa ependymoma.

METHODS

An institutional database was queried for children with a primary diagnosis of posterior fossa ependymoma from 2000 to 2019. Kaplan-Meier survival analysis and Cox-proportional hazard regression were used to assess the relationship between treatment factors and overall survival.

RESULTS

There were 60 patients identified; molecular subtype was available for 56, of which 49 (87.5%) were PF-A and 7 (12.5%) were PF-B. Relapse occurred in 29 patients (48%) at a mean time of 24 months following primary resection. Median 50% survival was 12.3 years for all patients and 3.3 years following diagnosis of first relapsed disease. GTR was associated with significantly improved survival following primary resection (HR 0.373, 95% CI 0.14-0.96). Presence of recurrent disease was significantly associated with worse survival (p < 0.0001). At recurrent disease diagnosis, disseminated disease was a negative prognostic factor (HR 11.0 95% CI 2.7-44) while GTR at first relapse was associated with improved survival HR 0.215 (95% CI: 0.048-0.96, p = 0.044). Beyond first relapse, the impact of GTR was not significant on survival, though surgery compared to no surgery was favorable with HR 0.155 (95% CI: 0.04-0.59).

CONCLUSIONS

Disseminated disease at recurrence and extent of resection for first relapsed disease were important prognostic factors. Surgery compared to no surgery was associated with improved survival for the multiply recurrent ependymoma cohort.

Photodynamic therapy for malignant brain tumors in children and young adolescents

Photodynamic therapy (PDT) targets tumor cell remnants after resection. Here, we evaluated the feasibility of PDT for malignant brain tumors in children and young adolescents. This was a single-center, non-randomized, phase I/II clinical study. The primary endpoints were the safety of treatment with talaporfin sodium (TS) (phase I) and overall survival (OS) after PDT (phase II). The secondary endpoint was progression-free survival (PFS) after PDT. The TS dose was determined by dose escalation from 10 to 20 to 40 mg/m² for every three cases starting from the initial enrolled case. Eight patients with a mean age of 170.2 months (129-214 months) at the time of PDT received nine procedures with a mean follow-up duration of 16.8 months (1-42 months) after PDT. Histopathological diagnoses included supratentorial anaplastic ependymoma (n = 2), anaplastic astrocytoma (n = 1), diffuse midline glioma with H3K27M mutation (n = 1), glioblastoma (n = 3), and pediatric high-grade glioma (n = 1). The outcome was survival in five patients and death in three patients. Recurrence occurred in six of the eight patients; the remaining two were recurrence-free after PDT. Therefore, OS and PFS were calculated as 21 and 6 months, respectively. Seizures and fevers, which were likely surgery-related symptoms, were commonly observed. Photosensitive skin rashes or liver dysfunction, which are common adverse effects in adults, were not observed. Our results showed that TS can be used safely in children at doses comparable to those used in adults, as there was no major complication associated with TS administration. However, we cannot make a definitive conclusion about the efficacy of PDT because of the small number of participants. Accumulating cases was difficult because of the rarity of pediatric brain tumors and the difficulty in making a preoperative differential diagnosis, considering the wide range of histopathological findings. Moreover, the psychological stress associated with light-shielding management in pediatric patients was more severe than initially expected. In conclusion, TS at doses comparable to those used in adults may be safe for use in children and young adolescents between the ages of 6 and 20 years. However, further studies are needed to clarify its efficacy.

Molecular testing for adolescent and young adult central nervous system tumors: A Canadian guideline

The 2021 World Health Organization (WHO) classification of CNS tumors incorporates molecular signatures with histology and has highlighted differences across pediatric vs adult-type CNS tumors. However, adolescent and young adults (AYA; aged 15–39), can suffer from tumors across this spectrum and is a recognized orphan population that requires multidisciplinary, specialized care, and often through a transition phase. To advocate for a uniform testing strategy in AYAs, pediatric and adult specialists from neuro-oncology, radiation oncology, neuropathology, and neurosurgery helped develop this review and testing framework through the Canadian AYA Neuro-Oncology Consortium. We propose a comprehensive approach to molecular testing in this unique population, based on the recent tumor classification and within the clinical framework of the provincial health care systems in Canada.

Supratentorial cortical ependymoma: A systematic literature review and case illustration

Cortical ependymomas are currently not considered a subgroup of supratentorial ependymomas; however, there is a growing body of literature investigating the natural history of these lesions compared to supratentorial ependymomas. We performed a systematic literature review of cortical ependymomas with a focus on the natural history, clinical characteristics, and clinical outcomes of these lesions as compared to supratentorial ependymomas. Our search revealed 153 unique cases of cortical ependymomas. The mean age on presentation was 21.2 years. Males and females comprised 58.8% (90/153) and 41.2% (63/153) of cases, respectively. The most common presenting symptom was seizure activity occurring in 44.4% of the cohort (68/153). The recently recognized C11orf95-RELA fusion was identified in 13.7% of the cohort (21/153) and 95.5% of cases (21/22) reporting molecular characterization. World Health Organization grades 2 and 3 were reported in 52.3% (79/151) and 47.7% (72/151) of cases, respectively. The frontal lobe was involved in the majority of cases (54.9%, 84/153). Gross total resection was achieved in 80.4% of cases (123/153). Tumor recurrence was identified in 27.7% of cases (39/141). Mean clinical follow-up was 41.3 months. Mean overall survival of patients who expired was 27.4 months whereas mean progression-free survival was 15.0 months. Comparatively, cortical ependymomas with C11orf95-RELA fusions and supratentorial ependymomas with C11orf95 RELA fusions exhibited differing clinical outcomes. Further studies with larger sample sizes are necessary to investigate the significance of RELA fusions on survival in cortical ependymomas and to determine whether cortical ependymomas with C11orf95-RELA fusions should be classified as a distinct entity.

Advanced Neuroimaging Approaches to Pediatric Brain Tumors

Simple Summary

After leukemias, brain tumors are the most common cancers in children, and early, accurate diagnosis is critical to improve patient outcomes. Beyond the conventional imaging methods of computed tomography (CT) and magnetic resonance imaging (MRI), advanced neuroimaging techniques capable of both structural and functional imaging are moving to the forefront to improve the early detection and differential diagnosis of tumors of the central nervous system. Here, we review recent developments in neuroimaging techniques for pediatric brain tumors.

Abstract

Central nervous system tumors are the most common pediatric solid tumors; they are also the most lethal. Unlike adults, childhood brain tumors are mostly primary in origin and differ in type, location and molecular signature. Tumor characteristics (incidence, location, and type) vary with age. Children present with a variety of symptoms, making early accurate diagnosis challenging. Neuroimaging is key in the initial diagnosis and monitoring of pediatric brain tumors. Conventional anatomic imaging approaches (computed tomography (CT) and magnetic resonance imaging (MRI)) are useful for tumor detection but have limited utility differentiating tumor types and grades. Advanced MRI techniques (diffusion-weighed imaging, diffusion tensor imaging, functional MRI, arterial spin labeling perfusion imaging, MR spectroscopy, and MR elastography) provide additional and improved structural and functional information. Combined with positron emission tomography (PET) and single-photon emission CT (SPECT), advanced techniques provide functional information on tumor metabolism and physiology through the use of radiotracer probes. Radiomics and radiogenomics offer promising insight into the prediction of tumor subtype, post-treatment response to treatment, and prognostication. In this paper, a brief review of pediatric brain cancers, by type, is provided with a comprehensive description of advanced imaging techniques including clinical applications that are currently utilized for the assessment and evaluation of pediatric brain tumors.

SIOP Ependymoma I: Final results, long-term follow-up, and molecular analysis of the trial cohort-A BIOMECA Consortium Study

BACKGROUND

SIOP Ependymoma I was a non-randomised trial assessing event free and overall survival (EFS/OS) of non-metastatic intracranial ependymoma in children aged 3-21 years treated with a staged management strategy. A further aim was to assess the response rate (RR) of subtotally resected (STR) ependymoma to vincristine, etoposide, and cyclophosphamide (VEC). We report final results with 12-year follow-up and post hoc analyses of recently described biomarkers.

METHODS

Seventy-four participants were eligible. Children with gross total resection (GTR) received radiotherapy, whilst those with STR received VEC before radiotherapy. DNA methylation, 1q, hTERT, ReLA, Tenascin-C, H3K27me3, and pAKT status were evaluated.

RESULTS

Five- and ten-year EFS was 49.5% and 46.7%, OS was 69.3% and 60.5%. GTR was achieved in 33/74 (44.6%) and associated with improved EFS (P = .003, HR = 2.6, 95% confidence interval (CI) 1.4-5.1). Grade 3 tumours were associated with worse OS (P = .005, HR = 2.8, 95%CI 1.3-5.8). 1q gain and hTERT expression were associated with poorer EFS (P = .003, HR = 2.70, 95%CI 1.49-6.10 and P = .014, HR = 5.8, 95%CI 1.2-28) and H3K27me3 loss with worse OS (P = .003, HR = 4.6, 95%CI 1.5-13.2). Methylation profiles showed expected patterns. 12 participants with STR did not receive chemotherapy; a protocol violation. However, best chemotherapy RR was 65.5% (19/29, 95%CI 45.7-82.1), exceeding the prespecified 45%.

CONCLUSIONS

Participants with totally resected ependymoma had the best outcomes. RR of STR to VEC exceeded the pre-specified efficacy criterion. However, cases of inaccurate stratification highlighted the need for rapid central review. 1q gain, H3K27me3 loss, and hTERT expression were all associated with poorer survival outcomes.

Ependymoma: Evaluation and Management Updates

PURPOSE OF REVIEW

To review state of art and relevant advances in the molecular genetics and management of ependymomas of children and adults.

RECENT FINDINGS

Ependymomas may occur either in the brain or in the spinal cord. Compared with intracranial ependymomas, spinal ependymomas are less frequent and exhibit a better prognosis. The new WHO classification of CNS tumors of 2021 has subdivided ependymomas into different histomolecular subgroups with different outcome. The majority of studies have shown a major impact of extent of resection; thus, a complete resection must be performed, whenever possible, at first surgery or at reoperation. Conformal radiotherapy is recommended for grade 3 or incompletely resected grade II tumors. Proton therapy is increasingly employed especially in children to reduce the risk of neurocognitive and endocrine sequelae. Craniospinal irradiation is reserved for metastatic disease. Chemotherapy is not useful as primary treatment and is commonly employed as salvage treatment for patients failing surgery and radiotherapy. Standard treatments are still the mainstay of treatment: the discovery of new druggable pathways will hopefully increase the therapeutic armamentarium in the near future.

Ongoing Response in a Multiply Relapsed Metastatic Posterior Fossa Ependymoma A After Vorinostat and Concomitant Irradiation

Posterior fossa ependymomas A confer the worst prognosis among all subtypes. They demonstrate distinct epigenetic changes, which can be targeted with epigenetic modifiers like histone deacetylase inhibitors (Vorinostat). We describe a 3-year-old male diagnosed with a posterior fossa ependymoma who had a number of recurrences requiring multimodal therapy. Molecular analysis demonstrated a BCL-6 corepressor mutation, and methylation profiling matched with posterior fossa ependymomas A. He received craniospinal irradiation and focal boost with Vorinostat. Serial imaging after irradiation revealed a progressively decreasing tumor burden with nearly complete resolution of disease at 15 months. Histone deacetylase inhibitors demonstrate promise in treatment of carefully selected cases of ependymoma.

The multifaceted NF-kB: are there still prospects of its inhibition for clinical intervention in pediatric central nervous system tumors?

Despite advances in the understanding of the molecular mechanisms underlying the basic biology and pathogenesis of pediatric central nervous system (CNS) malignancies, patients still have an extremely unfavorable prognosis. Over the years, a plethora of natural and synthetic compounds has emerged for the pharmacologic intervention of the NF-kB pathway, one of the most frequently dysregulated signaling cascades in human cancer with key roles in cell growth, survival, and therapy resistance. Here, we provide a review about the state-of-the-art concerning the dysregulation of this hub transcription factor in the most prevalent pediatric CNS tumors: glioma, medulloblastoma, and ependymoma. Moreover, we compile the available literature on the anti-proliferative effects of varied NF-kB inhibitors acting alone or in combination with other therapies in vitro, in vivo, and clinical trials. As the wealth of basic research data continues to accumulate, recognizing NF-kB as a therapeutic target may provide important insights to treat these diseases, hopefully contributing to increase cure rates and lower side effects related to therapy.

Ultra high-risk PFA ependymoma is characterized by loss of chromosome 6q

BACKGROUND

Within PF-EPN-A, 1q gain is a marker of poor prognosis, however, it is unclear if within PF-EPN-A additional cytogenetic events exist which can refine risk stratification.

METHODS

Five independent non-overlapping cohorts of PF-EPN-A were analyzed applying genome-wide methylation arrays for chromosomal and clinical variables predictive of survival.

RESULTS

Across all cohorts, 663 PF-EPN-A were identified. The most common broad copy number event was 1q gain (18.9%), followed by 6q loss (8.6%), 9p gain (6.5%), and 22q loss (6.8%). Within 1q gain tumors, there was significant enrichment for 6q loss (17.7%), 10q loss (16.9%), and 16q loss (15.3%). The 5-year progression-free survival (PFS) was strikingly worse in those patients with 6q loss, with a 5-year PFS of 50% (95% CI 45%-55%) for balanced tumors, compared with 32% (95% CI 24%-44%) for 1q gain only, 7.3% (95% CI 2.0%-27%) for 6q loss only and 0 for both 1q gain and 6q loss (P = 1.65 × 10-13). After accounting for treatment, 6q loss remained the most significant independent predictor of survival in PF-EPN-A but is not in PF-EPN-B. Distant relapses were more common in 1q gain irrespective of 6q loss. RNA sequencing comparing 6q loss to 6q balanced PF-EPN-A suggests that 6q loss forms a biologically distinct group.

CONCLUSIONS

We have identified an ultra high-risk PF-EPN-A ependymoma subgroup, which can be reliably ascertained using cytogenetic markers in routine clinical use. A change in treatment paradigm is urgently needed for this particular subset of PF-EPN-A where novel therapies should be prioritized for upfront therapy.

An Insight into Pathophysiological Features and Therapeutic Advances on Ependymoma

Simple Summary

Although biological information and the molecular classification of ependymoma have been studied, the treatment systems for ependymoma are still insufficient. In addition, because the disease occurs infrequently, it is difficult to obtain sufficient data to conduct large-scale or randomized clinical trials. Therefore, this study is intended to emphasize the importance of understanding its pathological characteristics and prognosis as well as developing treatments for ependymoma through multilateral studies.

Abstract

Glial cells comprise the non-sensory parts of the central nervous system as well as the peripheral nervous system. Glial cells, also known as neuroglia, constitute a significant portion of the mammalian nervous system and can be viewed simply as a matrix of neural cells. Despite being the “Nervenkitt” or “glue of the nerves”, they aptly serve multiple roles, including neuron repair, myelin sheath formation, and cerebrospinal fluid circulation. Ependymal cells are one of four kinds of glial cells that exert distinct functions. Tumorigenesis of a glial cell is termed a glioma, and in the case of an ependymal cell, it is called an ependymoma. Among the various gliomas, an ependymoma in children is one of the more challenging brain tumors to cure. Children are afflicted more severely by ependymal tumors than adults. It has appeared from several surveys that ependymoma comprises approximately six to ten percent of all tumors in children. Presently, the surgical removal of the tumor is considered a standard treatment for ependymomas. It has been conspicuously evident that a combination of irradiation therapy and surgery is much more efficacious in treating ependymomas. The main purpose of this review is to present the importance of both a deep understanding and ongoing research into histopathological features and prognoses of ependymomas to ensure that effective diagnostic methods and treatments can be developed.

In Vivo and Ex Vivo Pediatric Brain Tumor Models: An Overview

After leukemia, tumors of the brain and spine are the second most common form of cancer in children. Despite advances in treatment, brain tumors remain a leading cause of death in pediatric cancer patients and survivors often suffer from life-long consequences of side effects of therapy. The 5-year survival rates, however, vary widely by tumor type, ranging from over 90% in more benign tumors to as low as 20% in the most aggressive forms such as glioblastoma. Even within historically defined tumor types such as medulloblastoma, molecular analysis identified biologically heterogeneous subgroups each with different genetic alterations, age of onset and prognosis. Besides molecularly driven patient stratification to tailor disease risk to therapy intensity, such a diversity demonstrates the need for more precise and disease-relevant pediatric brain cancer models for research and drug development. Here we give an overview of currently available in vitro and in vivo pediatric brain tumor models and discuss the opportunities that new technologies such as 3D cultures and organoids that can bridge limitations posed by the simplicity of monolayer cultures and the complexity of in vivo models, bring to accommodate better precision in drug development for pediatric brain tumors.

Multiplatform Molecular Profiling Reveals Epigenomic Intratumor Heterogeneity in Ependymoma

Ependymomas exist within distinct genetic subgroups, but the molecular diversity within individual ependymomas is unknown. We perform multiplatform molecular profiling of 6 spatially distinct samples from an ependymoma with C11orf95-RELA fusion. DNA methylation and RNA sequencing distinguish clusters of samples according to neuronal development gene expression programs that could also be delineated by differences in magnetic resonance blood perfusion. Exome sequencing and phylogenetic analysis reveal epigenomic intratumor heterogeneity and suggest that chromosomal structural alterations may precede accumulation of single-nucleotide variants during ependymoma tumorigenesis. In sum, these findings shed light on the oncogenesis and intratumor heterogeneity of ependymoma.

Tumor heterogeneity poses a barrier to cancer treatment. Liu etal. investigate radiographically distinct regions of an ependymoma tumor using transcriptomic, genetic, and epigenomic profiling and discover axes of gene expression programs that recapitulate normal brain development in addition to phylogenies that shed light on the tumorigenesis of ependymoma.

Bioinformatics analysis of microarray data reveals epithelial-mesenchymal-transition in pediatric ependymoma

The objectives of this study were to explore the possible mechanisms of pediatric ependymoma using bioinformatics methods and provide potential genes and signaling pathways for pediatric ependymoma study. The data of GES74195 from Gene Expression Ominibus was analyzed by R language for pediatric ependymoma study. The differentially expressed genes were explored using gene set enrichment analysis, search tool for the retrieval of interacting genes, Cytoscape as well as other mainstream bioinformatics methods. Extracellular matrix-receptors interaction pathways and focal adhesion pathway were demonstrated as the key signaling pathway for pediatric ependymoma. The potential hub genes enriched in the two signaling pathways were regarded as final hub genes for this microarray analysis. The development and progression of pediatric ependymoma were associated with epithelial-mesenchymal-transition. Various potential hub genes and potential key signaling pathways in order to further explore their values in the diagnosis and treatment of this disease in the future.

Intracranial ependymomas: The role of advanced neuroimaging in diagnosis and management

Intracranial ependymomas represent a rare subgroup of glial tumours, showing a wide variety of imaging characteristics, often representing a challenging diagnosis for neuroradiologists. Here, we review the most recent scientific Literature on intracranial ependymomas, highlighting the most characteristic computed tomography and magnetic resonance imaging features of these neoplasms, along with epidemiologic data, recent classification aspects, clinical presentation and conventional therapeutic strategies. In addition, we report an illustrative case of an 18-year-old girl presenting with an intracranial supratentorial, anaplastic ependymoma, with the aim of contributing to the existing knowledge and comprehension of this rare tumour.

Assessment of Cannabidiol and Δ9-Tetrahydrocannabiol in Mouse Models of Medulloblastoma and Ependymoma

Simple Summary

Phytocannabinoids Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) have been demonstrated to exhibit anti-cancer activity in preclinical models of brain cancer leading to new clinical trials for adults with glioblastoma. We describe here the first report that has investigated a role for THC and CBD in pediatric brain cancer. Cannabinoids had cytotoxic activity against medulloblastoma and ependymoma cells in vitro, functioning in part through the inhibition of cell cycle progression and the induction of autophagy. Despite these effects in vitro, when tested in orthotopic mouse models of medulloblastoma or ependymoma, no impact on animal survival was observed. Furthermore, cannabinoids neither enhanced nor impaired conventional chemotherapy in a medulloblastoma mouse model. These data show that while THC and CBD do have some effects on medulloblastoma and ependymoma cells, are well tolerated, and have minimal adverse effects, they do not appear to elicit any survival benefit in preclinical models of pediatric brain cancer.

Abstract

Children with medulloblastoma and ependymoma are treated with a multidisciplinary approach that incorporates surgery, radiotherapy, and chemotherapy; however, overall survival rates for patients with high-risk disease remain unsatisfactory. Data indicate that plant-derived cannabinoids are effective against adult glioblastoma; however, preclinical evidence supporting their use in pediatric brain cancers is lacking. Here we investigated the potential role for Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) in medulloblastoma and ependymoma. Dose-dependent cytotoxicity of medulloblastoma and ependymoma cells was induced by THC and CBD in vitro, and a synergistic reduction in viability was observed when both drugs were combined. Mechanistically, cannabinoids induced cell cycle arrest, in part by the production of reactive oxygen species, autophagy, and apoptosis; however, this did not translate to increased survival in orthotopic transplant models despite being well tolerated. We also tested the combination of cannabinoids with the medulloblastoma drug cyclophosphamide, and despite some in vitro synergism, no survival advantage was observed in vivo. Consequently, clinical benefit from the use of cannabinoids in the treatment of high-grade medulloblastoma and ependymoma is expected to be limited. This study emphasizes the importance of preclinical models in validating therapeutic agent efficacy prior to clinical trials, ensuring that enrolled patients are afforded the most promising therapies available.

Reevaluating surgery and re-irradiation for locally recurrent pediatric ependymoma—a multi-institutional study

Background

The goal of this study was to evaluate extent of surgical resection, and timing and volume of re-irradiation, on survival for children with locally recurrent ependymoma.

Methods

Children with locally recurrent ependymoma treated with a second course of fractionated radiotherapy (RT2) from 6 North American cancer centers were reviewed. The index time was from the start of RT2 unless otherwise stated.

Results

Thirty-five patients were included in the study. The median doses for first radiation (RT1) and RT2 were 55.8 and 54 Gy, respectively. Median follow-up time was 5.6 years. Median overall survival (OS) for all patients from RT2 was 65 months. Gross total resection (GTR) was performed in 46% and 66% of patients prior to RT1 and RT2, respectively. GTR prior to RT2 was independently associated with improved progression-free survival (PFS) for all patients (HR 0.41, P = 0.04), with an OS benefit (HR 0.26, P = 0.03) for infratentorial tumors. Median PFS was superior with craniospinal irradiation (CSI) RT2 (not reached) compared to focal RT2 (56.9 months; log-rank P = 0.03). All distant failures (except one) occurred after focal RT2. Local failures after focal RT2 were predominantly in patients with less than GTR pre-RT2.

Conclusions

Patients with locally recurrent pediatric ependymoma should be considered for re-treatment with repeat maximal safe resection (ideally GTR) and CSI re-irradiation, with careful discussion of the potential side effects of these treatments.

Ependymoma, NOS and anaplastic ependymoma incidence and survival in the United States varies widely by patient and clinical characteristics, 2000-2016

BACKGROUND

Ependymoma is a rare CNS tumor arising from the ependymal lining of the ventricular system. General differences in incidence and survival have been noted but not examined on a comprehensive scale for all ages and by histology. Despite the rarity of ependymomas, morbidity/mortality associated with an ependymoma diagnosis justifies closer examination.

METHODS

Incidence data were obtained from the Central Brain Tumor Registry of the United States in collaboration with the Centers for Disease Control and Prevention and the National Cancer Institute, and survival data from Surveillance Epidemiology and End Results, from 2000 to 2016 for anaplastic ependymoma and ependymoma, not otherwise specified (NOS). Age-adjusted incidence rates (IRs) per 100 000 person-years were analyzed by age, sex, race, and location. Survival analysis was performed with Kaplan-Meier curves and multivariable Cox proportional hazards models.

RESULTS

Incidence of anaplastic ependymoma was highest in ages 0 to 4 years. African American populations had lower incidence but had a 78% increased risk of death compared to white populations (hazard ratio [HR]: 1.78 [95% CI, 1.30-2.44]). Incidence was highest for anaplastic ependymoma in the supratentorial region. Adults (age 40+ years) had almost twice the risk of death compared to children (ages 0-14 years) (HR: 1.97 [95% CI, 1.45-2.66]). For ependymoma, NOS, subtotal resection had a risk of mortality 1.86 times greater than gross total resection ([HR: 1.86 [95% CI, 1.32-2.63]).

CONCLUSIONS

African American populations experienced higher mortality rates despite lower incidence compared to white populations. Extent of resection is an important prognostic factor for survival. This highlights need for further evaluation of treatment patterns and racial disparities in the care of patients with ependymoma subtypes.

Retrosigmoid Approach for Resecting a Giant Lateral Pontine Ependymoma: Two-Dimensional Operative Video

Ependymoma is one of the most common pediatric tumors in central nervous system, for which gross total resection has been the most favorable prognostic factor. 12 However, surgery of ependymomas located in brain stem is significantly challenging. This video demonstrates the microsurgical removal of an ependymoma originating from ependymal cells of the lateral recess of fourth ventricle via retrosigmoid approach in an 11-year-old female. The patient presented with a 6-month history of continues headache and vomiting. On examination, she had a walking instability and an emaciated body. Neuroimaging revealed a right lateral pontine lesion extending to the cerebellopontine angle region. The patient underwent a suboccipital craniotomy, followed by excellent exposure for the tumor. Petrosal vein encased by the tumor mass and close adhesion of the tumor and the initial segments of facial and acoustic nerves adjoined brain stem could be seen operatively. While preserving trigeminal nerve, facial and acoustic nerves, posterior cranial nerves, anterior inferior cerebellar artery, labyrinth artery, posterior inferior cerebellar artery, and petrosal vein, gross total resection was achieved under the careful operation along arachnoid spaces together with intratumoral decompression. The patient tolerated the procedure well without any neurological deficits. Histological examination confirmed the tumor as an ependymoma (WHO II). The cytology measurement of the cerebrospinal fluid did not find any tumor cells. Postoperative computed tomography and magnetic resonance imaging scan depicted complete resection of the tumor, and adjuvant radiotherapy was recommended. She remained symptom-free without any evidence of recurrence during the follow-up period of 1 year. Informed consent was obtained from the patient.

The link to the video can be found at: https://youtu.be/sZ9GhUeltwc .

EZHIP/CXorf67 mimics K27M mutated oncohistones and functions as an intrinsic inhibitor of PRC2 function in aggressive posterior fossa ependymoma

BACKGROUND

Posterior fossa A (PFA) ependymomas are one of 9 molecular groups of ependymoma. PFA tumors are mainly diagnosed in infants and young children, show a poor prognosis, and are characterized by a lack of the repressive histone H3 lysine 27 trimethylation (H3K27me3) mark. Recently, we reported overexpression of chromosome X open reading frame 67 (CXorf67) as a hallmark of PFA ependymoma and showed that CXorf67 can interact with enhancer of zeste homolog 2 (EZH2), thereby inhibiting polycomb repressive complex 2 (PRC2), but the mechanism of action remained unclear.

METHODS

We performed mass spectrometry and peptide modeling analyses to identify the functional domain of CXorf67 responsible for binding and inhibition of EZH2. Our findings were validated by immunocytochemistry, western blot, and methyltransferase assays.

RESULTS

We find that the inhibitory mechanism of CXorf67 is similar to diffuse midline gliomas harboring H3K27M mutations. A small, highly conserved peptide sequence located in the C-terminal region of CXorf67 mimics the sequence of K27M mutated histones and binds to the SET domain (Su(var)3-9/enhancer-of-zeste/trithorax) of EZH2. This interaction blocks EZH2 methyltransferase activity and inhibits PRC2 function, causing de-repression of PRC2 target genes, including genes involved in neurodevelopment.

CONCLUSIONS

Expression of CXorf67 is an oncogenic mechanism that drives H3K27 hypomethylation in PFA tumors by mimicking K27M mutated histones. Disrupting the interaction between CXorf67 and EZH2 may serve as a novel targeted therapy for PFA tumors but also for other tumors that overexpress CXorf67. Based on its function, we have renamed CXorf67 as "EZH Inhibitory Protein" (EZHIP).

Is H3K27me3 status really a strong prognostic indicator for pediatric posterior fossa ependymomas? A single surgeon, single center experience

PURPOSE

Posterior fossa ependymomas (PFE) are among the most frequently occurring solid tumors in children. Their definitive treatment is surgical excision and adjuvant radio-chemotherapy. This study aimed to investigate prognostic effects of age, H3K27me3 status, extent of resection, radiation treatment (RT), Ki67 index, WHO grade, and ATRX and H3K27M mutations in PFE patients.

METHODS

This retrospective study included 42 pediatric patients with PFE who had undergone operation at our institution between 1996 and 2018. Patient demographics and treatment information were obtained from patient notes. Information on radiological location of tumors (median vs paramedian), extent of tumor resection, and recurrence was obtained from preoperative and postoperative magnetic resonance imaging. Formalin-fixed paraffin-embedded tumor samples were evaluated for H3K27me3 immunostaining, Ki67 index, WHO grades, and ATRX and H3K27M mutations. Tumor samples with global reduction in H3K27me3 were grouped as posterior fossa ependymoma group A (PFA) and those with H3K27me3 nuclear immunopositivity as posterior fossa ependymoma group B (PFB). We evaluated the cohort's 5-year progression-free survival (PFS) and overall survival (OS).

RESULTS

There were 20 (47.6%) female and 22 (52.4%) male patients in the cohort. The mean age of patients was 4.4 (range, 0.71-14.51) years. Overall, tumors in 31 (73.8%) and 11 (26.2%) patients were found to be PFA and PFB, respectively. There was no statistically significant age or sex difference between PFA and PFB. All patients received chemotherapy, whereas only 28 (66.6%) received RT. The WHO grades of PFA were statistically higher than those of PFB. There was no significant difference between PFA and PFB in terms of extent of resection, disease recurrence, and survival parameters. Nine of 42 tumor samples had ATRX mutations. One patient with PFA showed H3K27M mutation. Age, WHO grade, H3K27me3 status, and RT had no effect on patients' PFS and OS. Patients with total surgical excisions had significantly better PFS and OS rates. Those with Ki67 < 50% also had better OS rates.

CONCLUSIONS

Determining H3K27me3 status by immunohistochemistry is a widely accepted method for molecular subgrouping of PFEs. Most of the reports in the literature state that molecular subgroups of PFEs have significantly different clinical outcomes. However, in our present series, we have shown that the extent of surgical excision is still the most important prognostic indicator in PFEs. We also conclude that the prognostic effect of H3K27me3 status-based molecular subgrouping may be minimized with a more aggressive surgical strategy followed in PFAs.

Locoregional delivery of CAR T cells to the cerebrospinal fluid for treatment of metastatic medulloblastoma and ependymoma

Recurrent medulloblastoma and ependymoma are universally lethal, with no approved targeted therapies and few candidates presently under clinical evaluation. Nearly all recurrent medulloblastomas and posterior fossa group A (PFA) ependymomas are located adjacent to and bathed by the cerebrospinal fluid, presenting an opportunity for locoregional therapy, bypassing the blood-brain barrier. We identify three cell-surface targets, EPHA2, HER2 and interleukin 13 receptor α2, expressed on medulloblastomas and ependymomas, but not expressed in the normal developing brain. We validate intrathecal delivery of EPHA2, HER2 and interleukin 13 receptor α2 chimeric antigen receptor T cells as an effective treatment for primary, metastatic and recurrent group 3 medulloblastoma and PFA ependymoma xenografts in mouse models. Finally, we demonstrate that administration of these chimeric antigen receptor T cells into the cerebrospinal fluid, alone or in combination with azacytidine, is a highly effective therapy for multiple metastatic mouse models of group 3 medulloblastoma and PFA ependymoma, thereby providing a rationale for clinical trials of these approaches in humans.

Perioperative Cardiothoracic and Vascular Risk in Childhood Cancer and its Survivors

CHILDREN with cancer and survivors of childhood cancer have an increased risk of cardiovascular disease, and this risk in the perioperative period must be understood. During diagnosis and treatment of pediatric cancer, multiple acute cardiovascular morbidities are possible, including anterior mediastinal mass, tamponade, hypertension, cardiomyopathy,and heart failure. Childhood cancer survivors reaching late childhood and adulthood experience substantially increased rates of cardiomyopathy, heart failure, valvular disease, pericardiac disease, ischemia, and arrhythmias. Despite considerable advances in the understanding and therapeutic options of pediatric malignancies, cardiac disease remains the most common treatment-related, noncancer cause of death in childhood cancer survivors. Increasingly, molecularly targeted agents, including small molecule inhibitors, are being incorporated into pediatric oncology. The acute and chronic risks associated with these newer therapeutic options in children are not yet well-described, which poses challenges for clinicians caring for these patients. In the present review, the unique risks factors, prevention strategies, and treatment of cardiovascular toxicities of the child with cancer and the childhood cancer survivor are examined, with an emphasis on the perioperative period.

Extent of re-excision, sequence/timing of salvage re-irradiation, and disease-free interval impact upon clinical outcomes in recurrent/progressive ependymoma

PURPOSE

To report clinical outcomes of salvage re-irradiation (re-RT) in recurrent/progressive ependymoma.

METHODS

Medical records of patients treated with curative-intent re-RT as multi-modality management for recurrent/progressive ependymoma were analyzed retrospectively. The linear-quadratic model was used to provide estimates of biologically effective dose (BED) of irradiation using an α/β value of 2 for late CNS toxicity for each course of irradiation and summated to derive cumulative BED without correcting for the assumed recovery.

RESULTS

A total of 55 patients (median age 10 years at index diagnosis) treated with curative-intent re-RT between 2010 and 2018 were included. Median time to first recurrence was 29 months with an inter-quartile range (IQR) of 16-64 months. Majority (n = 46, 84%) of patients underwent surgical re-excision of recurrent disease. Median interval from first course of irradiation (RT1) to second course (RT2) was 35 months (IQR = 26-66 months) with a median re-RT dose of 54 Gy in 30 fractions (range 40-60 Gy), resulting in median cumulative equivalent dose in 2 Gy fraction (EQD2) of 106.2 Gy (range 92.4-117.6 Gy). Volume of re-RT was based on location and pattern of relapse, comprising uni-focal (n = 49, 89%), multi-focal (n = 3, 5.5%), or craniospinal irradiation (CSI) in 3 (5.5%) patients respectively. Thirty-six (66%) patients received platinum-based salvage chemotherapy either before or after RT2. At a median follow up of 37 months (range 6-80 months), the Kaplan-Meier estimates of 3-year progression-free survival (PFS) and overall survival (OS) for the entire study cohort were 40% and 51% respectively. Gross total resection at recurrence; early salvage re-RT (prior to chemotherapy, if any); and longer (> 2 years) disease-free interval (DFI) were associated with better survival outcomes. Salvage re-RT was generally well tolerated with only 3 (5.5%) patients developing symptomatic radiation necrosis necessitating corticosteroids.

CONCLUSION

Extent of re-excision, sequence/timing of re-RT, and DFI impact upon outcomes in curative-intent, multi-modality salvage therapy for recurrent ependymoma.

Molecularly Targeted Agents in the Therapy of Pediatric Brain Tumors

Pediatric brain tumors are the leading cause of cancer-related death in children. Recent advances in sequencing techniques, and collaborative efforts to encode the mutational landscape of various tumor subtypes, have resulted in the identification of recurrent mutations that may present as actionable targets in these tumors. A number of molecularly targeted agents are approved or in development for the treatment of various tumor types in adult patients. Similarly, these agents are increasingly being incorporated into pediatric clinical trials, allowing for a targeted approach to treatment. However, due to the genetic heterogeneity of these tumors, focused clinical trials in pediatric patients are challenging and regulatory hurdles may delay access to therapeutic compounds that are in regular use in adult patients. The tumor site-agnostic clinical development of TRK inhibitors for pediatric solid tumors is a current example of how the combination of genetic testing and innovative clinical trial design can accelerate the clinical development of targeted agents for pediatric patients.

Personalizing age-specific survival prediction and risk stratification in intracranial grade II/III ependymoma

BACKGROUND

Models for estimation of survival rates of patients with intracranial grade II/III ependymoma (EPN) are scarce. Considering the heterogeneity in prognostic factors between pediatric and adult patients, we aimed to develop age-specific nomograms for predicting 3-, 5-, and 8-year survival for these patients.

METHODS

A total of 1390 cases (667 children; 723 adults) of intracranial grade II/III EPNs diagnosed between 1988 and 2015 were extracted from the Surveillance, Epidemiology, and End Results (SEER) database for our study. Univariable and multivariable Cox analyses were employed to identify independent prognostic predictors. Age-specific nomograms were developed based on the results of multivariate Cox analyses. We also evaluated the performance of these predictive models by concordance index, calibration curves, time-dependent receiver operating characteristic curves, and decision curve analyses.

RESULTS

Considerable heterogeneity in prognostic factors was highlighted between pediatric and adult patients. Age, sex, tumor grade, surgery treatment and radiotherapy were identified as significant predictors of overall survival for children, and age, tumor grade, tumor size, surgery treatment, and marital status for adult. Based on these factors, age-specific nomogram models were established and internally validated. These models exhibited favorable discrimination and calibration characteristics. Nomogram-based risk classification systems were also constructed to facilitate risk stratification in EPNs for optimization of clinical management.

CONCLUSIONS

We developed the first nomograms and corresponding risk classification systems for predicting survival in patients with intracranial grade II/III EPN. These easily used tools can assist oncologists in making accurate survival evaluation.

Notch pathway in ependymoma RELA-fused subgroup: upregulation and association with cancer stem cells markers expression

RELA-fused supratentorial (ST) ependymoma (EPN) is an aggressive subgroup with poor prognosis. Considering the putative role of Notch signaling in the maintenance of the cancer stem cells (CSC) phenotype in RELA-fused EPN, we investigated the expression of Notch pathway and its target genes in this subgroup. We also evaluated the effects of two Notch inhibitors (DAPT and RO4929097) on cell proliferation, apoptosis, colony formation, and CSCs markers gene expression on EPN cell line of the RELA-fused subgroup (BXD-1425). In addition, in silico signatures of the Notch genes and CSCs markers were analyzed on a large clinical dataset from GSE64415 study. We found that among the ST-EPN subgroups the Notch signaling (NOTCH1, JAG1, JAG2, and HES4) is specifically activated in the ST-EPN-RELA. Furthermore, treatment of the RELA-fused EPN cell line with the Notch inhibitors impaired the Notch signaling expression and revealed that Notch axis is not essential for cell proliferation and survival in this setting. NOTCH1 expression in ST-EPN was correlated with the CSCs markers VEGFA and L1CAM overexpression and JAG1 expression was correlated with the CCND1 and CDK6 overexpression. In addition, in vitro treatment with Notch inhibitors induced downregulation of CSCs markers. These findings indicate that Notch signaling can be involved in the ST-EPN-RELA CSCs maintenance by modulating the expression of genes responsible for cell phenotype and cell fate.

Clinicopathological and Genetic Features of Supratentorial Cortical Ependymomas

OBJECTIVE

Supratentorial cortical ependymomas (CEs) are rare. These lesions, selectively occurring in the superficial cortex, have not been fully characterized. We analyzed the clinicopathological and genetic features of CEs.

METHODS

Eight patients with CEs from our institution and 84 other reported CE cases were included in the present study. We retrospectively reviewed their clinical characteristics, imaging findings, treatment methods, pathological features, molecular status, and clinical outcomes.

RESULTS

The median age at diagnosis of our 8 patients was 7.5 years. The mean tumor diameter was 70 mm. All the tumors had a cystic appearance, and calcification was observed in 6. Gross total resection was achieved in 6 patients and subtotal resection in 2 patients. Of the 8 tumors, 7 were World Health Organization grade III and 1 was World Health Organization grade II. Six tumors were immunopositive for L1 cell adhesion molecule (L1CAM). We investigated the presence of C11orf95-RELA fusion in 5 patients, all of whom exhibited it. Postoperative radiotherapy was performed for all patients with grade III tumors, except for children aged <3 years. Although 4 patients developed recurrence, all were alive throughout the follow-up period. Compared with previously reported CEs, our patients were younger and had larger tumors; however, the clinical outcomes did not differ significantly.

CONCLUSIONS

Although most CEs in our group were immunopositive for L1CAM and showed C11orf95-RELA fusion, which have been associated with a poor prognosis in supratentorial ependymomas, all our patients had good outcomes. Gross total resection and adjuvant radiotherapy contributed to the relatively favorable prognosis of CEs compared with other supratentorial ependymomas.

Central nervous system ependymoma: clinical implications of the new molecular classification, treatment guidelines and controversial issues

Ependymoma is an uncommon neuroepithelial tumor that may arise anywhere within the neuroaxis, both in children and in adults. It has been classically graded upon histopathological features, yet with limited clinical utility. Recently, DNA methylation profiling has provided a novel classification of ependymoma in nine molecular subgroups. This stratification method harbors prognostic value with supratentorial RELA-fusion and posterior fossa group A tumors showing a significantly shorter survival compared to the rest. Currently, the treatment of choice involves maximal safe resection and, in cases of residual disease, adjuvant conformal radiotherapy. Second-look surgery is also a feasible and recommended option for incompletely resected tumors. The role of chemotherapy is not yet established and can be considered in infants and children with relapsing disease or prior to re-intervention. Although targeted agents do not seem to play a role as adjuvant therapy, they are currently being tested for recurrent disease.

Conformal Radiation Therapy for Pediatric Ependymoma, Chemotherapy for Incompletely Resected Ependymoma, and Observation for Completely Resected, Supratentorial Ependymoma

PURPOSE

The Children's Oncology Group trial ACNS0121 estimated event-free survival (EFS) and overall survival for children with intracranial ependymoma treated with surgery, radiation therapy, and-selectively-with chemotherapy. Treatment was administered according to tumor location, histologic grade, and extent of resection. The impacts of histologic grade, focal copy number gain on chromosome 1q, and DNA methylation profiles were studied for those undergoing surgery and immediate postoperative conformal radiation therapy (CRT).

METHODS

ACNS0121 included 356 newly diagnosed patients (ages 1 to 21 years). Patients with classic supratentorial ependymoma were observed after gross total resection (GTR). Those undergoing subtotal resection received chemotherapy, second surgery, and CRT. The remaining patients received immediate postoperative CRT after near-total resection or GTR. CRT was administered with a 1.0-cm clinical target volume margin. The cumulative total dose was 59.4 Gy, except for patients who underwent GTR and were younger than age 18 months (who received 54 Gy). Patients were enrolled between October 2003 and September 2007 and were observed for 5 years. Supratentorial tumors were evaluated for RELA fusion; infratentorial tumors, for chromosome 1q gain. Classification of posterior fossa groups A and B was made by methylation profiles.

RESULTS

The 5-year EFS rates were 61.4% (95% CI, 34.5% to 89.6%), 37.2% (95% CI, 24.8% to 49.6%), and 68.5% (95% CI, 62.8% to 74.2%) for observation, subtotal resection, and near-total resection/GTR groups given immediate postoperative CRT, respectively. The 5-year EFS rates differed significantly by tumor grade (P = .0044) but not by age, location, RELA fusion status, or posterior fossa A/posterior fossa B grouping. EFS was higher for patients with infratentorial tumors without 1q gain than with 1q gain (82.8% [95% CI, 74.4% to 91.2%] v 47.4% [95% CI, 26.0% to 68.8%]; P = .0013).

CONCLUSION

The EFS for patients with ependymoma younger than 3 years of age who received immediate postoperative CRT and for older patients is similar. Irradiation should remain the mainstay of care for most subtypes.

Survival and functional outcomes of molecularly defined childhood posterior fossa ependymoma: Cure at a cost

BACKGROUND

Posterior fossa ependymoma (PFE) comprises 2 groups, PF group A (PFA) and PF group B (PFB), with stark differences in outcome. However, to the authors' knowledge, the long-term outcomes of PFA ependymoma have not been described fully. The objective of the current study was to identify predictors of survival and neurocognitive outcome in a large consecutive cohort of subgrouped patients with PFE over 30 years.

METHODS

Demographic, survival, and neurocognitive data were collected from consecutive patients diagnosed with PFE from 1985 through 2014 at the Hospital for Sick Children in Toronto, Ontario, Canada. Subgroup was assigned using genome-wide methylation array and/or immunoreactivity to histone H3 K27 trimethylation (H3K27me3).

RESULTS

A total of 72 PFE cases were identified, 89% of which were PFA. There were no disease recurrences noted among patients with PFB. The 10-year progression-free survival rate for all patients with PFA was poor at 37.1% (95% confidence interval, 25.9%-53.1%). Analysis of consecutive 10-year epochs revealed significant improvements in progression-free survival and/or overall survival over time. This pertains to the increase in the rate of gross (macroscopic) total resection from 35% to 77% and the use of upfront radiotherapy increasing from 65% to 96% over the observed period and confirmed in a multivariable model. Using a mixed linear model, analysis of longitudinal neuropsychological outcomes restricted to patients with PFA who were treated with focal irradiation demonstrated significant continuous declines in the full-scale intelligence quotient over time with upfront conformal radiotherapy, even when correcting for hydrocephalus, number of surgeries, and age at diagnosis (-1.33 ± 0.42 points/year; P = .0042).

CONCLUSIONS

Data from a molecularly informed large cohort of patients with PFE clearly indicate improved survival over time, related to more aggressive surgery and upfront radiotherapy. However, to the best of the authors' knowledge, the current study is the first, in a subgrouped cohort, to demonstrate that this approach results in reduced neurocognitive outcomes over time.

Heterogeneity within the PF-EPN-B ependymoma subgroup

Posterior fossa ependymoma comprise three distinct molecular variants, termed PF-EPN-A (PFA), PF-EPN-B (PFB), and PF-EPN-SE (subependymoma). Clinically, they are very disparate and PFB tumors are currently being considered for a trial of radiation avoidance. However, to move forward, unraveling the heterogeneity within PFB would be highly desirable. To discern the molecular heterogeneity within PFB, we performed an integrated analysis consisting of DNA methylation profiling, copy-number profiling, gene expression profiling, and clinical correlation across a cohort of 212 primary posterior fossa PFB tumors. Unsupervised spectral clustering and t-SNE analysis of genome-wide methylation data revealed five distinct subtypes of PFB tumors, termed PFB1-5, with distinct demographics, copy-number alterations, and gene expression profiles. All PFB subtypes were distinct from PFA and posterior fossa subependymomas. Of the five subtypes, PFB4 and PFB5 are more discrete, consisting of younger and older patients, respectively, with a strong female-gender enrichment in PFB5 (age: p = 0.011, gender: p = 0.04). Broad copy-number aberrations were common; however, many events such as chromosome 2 loss, 5 gain, and 17 loss were enriched in specific subtypes and 1q gain was enriched in PFB1. Late relapses were common across all five subtypes, but deaths were uncommon and present in only two subtypes (PFB1 and PFB3). Unlike the case in PFA ependymoma, 1q gain was not a robust marker of poor progression-free survival; however, chromosome 13q loss may represent a novel marker for risk stratification across the spectrum of PFB subtypes. Similar to PFA ependymoma, there exists a significant intertumoral heterogeneity within PFB, with distinct molecular subtypes identified. Even when accounting for this heterogeneity, extent of resection remains the strongest predictor of poor outcome. However, this biological heterogeneity must be accounted for in future preclinical modeling and personalized therapies.

Identification of FDA-Approved Oncology Drugs with Selective Potency in High-Risk Childhood Ependymoma

Children with ependymoma (EPN) are cured in less than 50% of cases, with little improvement in outcome over the last several decades. Chemotherapy has not affected survival in EPN, due in part to a lack of preclinical models that has precluded comprehensive drug testing. We recently developed two human EPN cell lines harboring high-risk phenotypes which provided us with an opportunity to execute translational studies. EPN and other pediatric brain tumor cell lines were subject to a large-scale comparative drug screen of FDA-approved oncology drugs for rapid clinical application. The results of this in vitro study were combined with in silico prediction of drug sensitivity to identify EPN-selective compounds, which were validated by dose curve and time course modeling. Mechanisms of EPN-selective antitumor effect were further investigated using transcriptome and proteome analyses. We identified three classes of oncology drugs that showed EPN-selective antitumor effect, namely, (i) fluorinated pyrimidines (5-fluorouracil, carmofur, and floxuridine), (ii) retinoids (bexarotene, tretinoin and isotretinoin), and (iii) a subset of small-molecule multireceptor tyrosine kinase inhibitors (axitinib, imatinib, and pazopanib). Axitinib's antitumor mechanism in EPN cell lines involved inhibition of PDGFRα and PDGFRβ and was associated with reduced mitosis-related gene expression and cellular senescence. The clinically available, EPN-selective oncology drugs identified by our study have the potential to critically inform design of upcoming clinical studies in EPN, in particular for those children with recurrent EPN who are in the greatest need of novel therapeutic approaches. Mol Cancer Ther; 17(9); 1984-94. ©2018 AACR.

Pediatric Supratentorial Ependymoma: Surgical, Clinical, and Molecular Analysis

BACKGROUND

Pediatric supratentorial ependymomas (SEs) have distinct molecular and behavioral differences from their infratentorial counterparts.

OBJECTIVE

To present our experience with pediatric SEs over a 24-yr period.

METHODS

Clinical, operative, and radiographic information was abstracted retrospectively. Our primary outcomes were progression-free survival (PFS) and overall survival (OS). Detection of C11orf95-RELA rearrangement was performed using interphase fluorescence in situ hybridization (iFISH).

RESULTS

Seventy-three patients were identified (41 female, 32 male); median age was 6.7 yrs (range, 1 mo-18.8 yr); median follow-up was 8.3 yrs (range, 2.0-26.3). Fifty-eight (79.5%) of 73 patients underwent gross total resection (GTR); no patient with subtotal resection had greater than 1 cm3 of residual tumor; 42 patients (57.5%) experienced subsequent disease progression with 17 patients ultimately dying of their disease. Median PFS was 3.7 yrs. Molecular analysis was available for 51 patients (70%). On bivariate analysis, PFS and OS were not statistically affected by age, tumor grade, or extent of resection, although there was a clinically significant trend for the latter in favor of aggressive resection on PFS (P = .061). Children with RELA fusion had significantly higher PFS (P = .013) than those without, although there was no difference in OS when compared with those with no C11orf95-RELA fusion or C11orf95 gene rearrangement alone.

CONCLUSION

In our series, GTR may be associated with better PFS, but did not impact OS. Surprisingly, RELA fusion was not found to be a negative prognostic factor, raising the possibility that the deleterious effects may be overcome by aggressive resection.

Prognostic and microRNA profile analysis for CD44 positive expression pediatric posterior fossa ependymoma

BACKGROUND

Ependymoma is the third most common pediatric brain tumor and occurs most frequently in the posterior fossa. However, the lack of immortalized cell lines, xenografts, or animal models has significantly hindered the study of pediatric posterior fossa ependymoma (P-PF-EPN) pathogenesis. This prompted us to use clinical big data to study this rare disease.

METHODS

Application of the robust rank aggregation method revealed CD44 as a reliable biomarker in P-PF-EPN. 120 P-PF-EPN samples after surgical resection were selected for Kaplan-Merier and Cox proportion hazard regression survival analysis. Immunohistochemical analysis was performed to assess CD44 expression in the tumor samples. The miRNA profile was determined using a whole-genome miRNA microarray. The expression patterns of related mRNAs, miRNAs and proteins were validated by qRT-PCR or Western blotting.

RESULTS

CD44 was found to be an independent predictor of prognosis in survival analysis. It improved the accuracy of using LAMA2/NELL2 for classifying P-PF-EPN molecular subgroups. Fourteen miRNAs were underexpressed, and one miRNA was overexpressed in CD44-positive P-PF-EPNs. miR-543, miR-495-3p, miR-299-3p, miR-139-5p and miR-128-3p were identified to have CD44 positively co-regulated potential target oncogenes. Two PI3K-Akt signaling pathway related potential target oncogenes (VEGFA, CSF1) for miR-299-3p and miR-495-3p were validated overexpression in CD44 positive P-PF-EPNs. Abnormal activation of the PI3K-Akt pathway was confirmed in CD44-positive cases.

CONCLUSIONS

CD44 is of great clinical significance as a prognostic biomarker. The survival difference between CD44 positive and negative P-PF-EPN is determined by a complex functional miRNA-mRNA-signaling pathway regulatory network.

Resistance-promoting effects of ependymoma treatment revealed through genomic analysis of multiple recurrences in a single patient

As in other brain tumors, multiple recurrences after complete resection and irradiation of supratentorial ependymoma are common and frequently result in patient death. This standard-of-care treatment was established in the pregenomic era without the ability to evaluate the effect that mutagenic therapies may exert on tumor evolution and in promoting resistance, recurrence, and death. We seized a rare opportunity to characterize treatment effects and the evolution of a single patient's ependymoma across four recurrences after different therapies. A combination of high-depth whole-genome and exome-based DNA sequencing of germline and tumor specimens, RNA sequencing of tumor specimens, and advanced computational analyses were used. Treatment with radiation and chemotherapies resulted in a substantial increase in mutational burden and diversification of the tumor subclonal architecture without eradication of the founding clone. Notable somatic alterations included a MEN1 driver, several epigenetic modifiers, and therapy-induced mutations that impacted multiple other cancer-relevant pathways and altered the neoantigen landscape. These genomic data provided new mechanistic insights into the genesis of ependymoma and pathways of resistance. They also revealed that radiation and chemotherapy were significant forces in shaping the increased subclonal complexity of each tumor recurrence while also failing to eradicate the founding clone. This raises the question of whether standard-of-care treatments have similar consequences in other patients with ependymoma and other types of brain tumors. If so, the perspective obtained by real-time genomic characterization of a tumor may be essential for making effective patient-specific and adaptive clinical decisions.

Establishing a Preclinical Multidisciplinary Board for Brain Tumors

Purpose: Curing all children with brain tumors will require an understanding of how each subtype responds to conventional treatments and how best to combine existing and novel therapies. It is extremely challenging to acquire this knowledge in the clinic alone, especially among patients with rare tumors. Therefore, we developed a preclinical brain tumor platform to test combinations of conventional and novel therapies in a manner that closely recapitulates clinic trials.Experimental Design: A multidisciplinary team was established to design and conduct neurosurgical, fractionated radiotherapy and chemotherapy studies, alone or in combination, in accurate mouse models of supratentorial ependymoma (SEP) subtypes and choroid plexus carcinoma (CPC). Extensive drug repurposing screens, pharmacokinetic, pharmacodynamic, and efficacy studies were used to triage active compounds for combination preclinical trials with "standard-of-care" surgery and radiotherapy.Results: Mouse models displayed distinct patterns of response to surgery, irradiation, and chemotherapy that varied with tumor subtype. Repurposing screens identified 3-hour infusions of gemcitabine as a relatively nontoxic and efficacious treatment of SEP and CPC. Combination neurosurgery, fractionated irradiation, and gemcitabine proved significantly more effective than surgery and irradiation alone, curing one half of all animals with aggressive forms of SEP.Conclusions: We report a comprehensive preclinical trial platform to assess the therapeutic activity of conventional and novel treatments among rare brain tumor subtypes. It also enables the development of complex, combination treatment regimens that should deliver optimal trial designs for clinical testing. Postirradiation gemcitabine infusion should be tested as new treatments of SEP and CPC. Clin Cancer Res; 24(7); 1654-66. ©2018 AACR.

EANO guidelines for the diagnosis and treatment of ependymal tumors

Ependymal tumors are rare CNS tumors and may occur at any age, but their proportion among primary brain tumors is highest in children and young adults. Thus, the level of evidence of diagnostic and therapeutic interventions is higher in the pediatric compared with the adult patient population.The diagnosis and disease staging is performed by craniospinal MRI. Tumor classification is achieved by histological and molecular diagnostic assessment of tissue specimens according to the World Health Organization (WHO) classification 2016. Surgery is the crucial initial treatment in both children and adults. In pediatric patients with intracranial ependymomas of WHO grades II or III, surgery is followed by local radiotherapy regardless of residual tumor volume. In adults, radiotherapy is employed in patients with anaplastic ependymoma WHO grade III, and in case of incomplete resection of WHO grade II ependymoma. Chemotherapy alone is reserved for young children <12 months and for adults with recurrent disease when further surgery and irradiation are no longer feasible. A gross total resection is the mainstay of treatment in spinal ependymomas, and radiotherapy is reserved for incompletely resected tumors. Nine subgroups of ependymal tumors across different anatomical compartments (supratentorial, posterior fossa, spinal) and patient ages have been identified with distinct genetic and epigenetic alterations, and with distinct outcomes. These findings may lead to more precise diagnostic and prognostic assessments, molecular subgroup-adapted therapies, and eventually new recommendations pending validation in prospective studies.

H3 K27M mutations are extremely rare in posterior fossa group A ependymoma

BACKGROUND

Mutations in the tail of histone H3 (K27M) are frequently found in pediatric midline high-grade glioma's but have rarely been reported in other malignancies. Recently, recurrent somatic nucleotide variants in histone H3 (H3 K27M) have been reported in group A posterior fossa ependymoma (EPN_PFA), an entity previously described to have no recurrent mutations. However, the true incidence of H3 K27M mutations in EPN_PFA is unknown.

METHODS

In order to discern the frequency of K27M mutations in histone H3 in EPN_PFA, we analyzed 151 EPN_PFA previously profiled with genome-wide methylation arrays using a validated droplet digital PCR assay.

RESULTS

We identified only 1 case out of 151 EPN_PFA harboring the K27M mutation indicating that histone mutations are extremely rare in EPN_PFA. Morphologically, this single mutated case is clearly consistent with an ependymoma, and the presence of the K27M mutation was confirmed using immunohistochemistry.

DISCUSSION

K27M mutations are extremely rare in EPN_PFA. Routine evaluation of K27M mutations in EPN_PFA is of limited utility, and is unlikely to have any bearing on prognosis and/or future risk stratification.