Ependymoma in children under the age of 3 years: a report from the Canadian Pediatric Brain Tumour Consortium

Clinical Characteristics, Treatment, and Survival Outcome of Ependymoma in Infants

BACKGROUND

Treatment modalities of ependymoma in infants remain controversial. Postoperative adjuvant radiotherapy could prolong overall survival but has the potential to affect nervous system development in infants. The role of adjuvant chemotherapy in prolonging overall survival for infants with ependymoma is still unclear. Therefore we designed this study to explore the effect of treatment modalities on survival time of infants with ependymoma.

METHODS

We studied 72 infants with ependymoma from the Surveillance, Epidemiology, and End Results database in this retrospective analysis. Univariate and multivariate Cox proportional hazard models were adopted to determine hazard ratios and compare overall survival.

RESULTS

Among 72 infants with ependymoma, 35 were male (48.6%) and 37 were female (51.4%). The 5-year overall survival of all patients was 67%. Forty-six infants (63.9%) received gross total resection, 20 (27.8%) received subtotal resection, and 6 (8.3%) did not receive surgical resection or only autopsy. Twenty-one infants (29.2%) received radiotherapy, and 45 (62.5%) received chemotherapy. Multivariate analysis revealed that patients accepted surgical resection (No vs. gross total resection, P < 0.001; No vs. subtotal resection, P = 0.026) and chemotherapy (No vs. Yes, P = 0.024) are the independent prognostic factors for overall survival.

CONCLUSIONS

Treatment modality is associated with survival time in infants with ependymoma. The extent of resection and chemotherapy were independent prognostic factors for infants with ependymoma.

Supratentorial and Infratentorial Ependymoma

Ependymomas are the third most common intracranial tumor in children, presenting in both the supratentorial and infratentorial compartments. They may present in infants, young children, and adolescents with symptoms depending on size, location, and the age of the patient. The ideal imaging for evaluation and treatment is MRI. This is crucial for preoperative evaluation and planning, as well as postoperative assessment and evaluating the efficacy of treatment. Essentially without exception, aggressive surgery aimed at complete resection is the initial and most important factor in the long-term outcome of all these children. Histopathologic diagnosis for intracranial pediatric ependymoma has been narrowed to grade II and grade III, no longer characterized as classic and anaplastic. Subsequent conformal photon or proton beam irradiation is an established post-surgical therapy, with solid evidence that it benefits survival and offers lower toxicity to the normal brain of the young child. Although chemotherapeutic treatment has not been generally impactful, immunotherapeutic interventions may be on the horizon. Updated molecular subgrouping of ependymoma is changing the post-resection approach of these tumors with regard to both treatment and outcome. Excluding spinal ependymoma and subependymoma, there are four subtypes that are defined by genetic characteristics, two found in the supratentorial compartment, ST-EPN-YAP1 and ST-EPN-ZFTA, and two in the posterior fossa, PF-EPN-A and PF-EPN-B. Younger children harboring ZFTA fusion-positive supratentorial and type A posterior fossa tumors, regardless of histology, tend toward the poorest outcomes. On the contrary, older children with supratentorial YAP1 fusion-positive ependymomas and type B posterior fossa tumors may survive with surgery alone. The paradigm shift regarding the behavior of the various childhood ependymoma subtypes will hopefully lead to targeted, individualized therapies and improved outcomes.

Challenges in Treating Childhood Infratentorial Ependymoma: A Low- and Middle-Income Country Experience

PURPOSE

Patients and physicians in low- and middle-income countries (LMICs) face challenges owing to limited expertise and suboptimal access to appropriate diagnostic and treatment modalities. We report our experience in treating posterior fossa ependymoma (PFE) at MAHAK, a charity organization in Iran whose radiation oncology department is the only one exclusively dedicated to childhood cancer in the whole country.

METHODS AND MATERIALS

Pediatric patients with PFE referred to MAHAK between November 2008 and January 2016 were identified. Details on investigations and management done before referral were collected. Management at MAHAK and patient outcomes were analyzed.

RESULTS

Of 80 patients diagnosed as having ependymoma, 54 with PFE were identified. Forty-three patients received adjuvant radiation therapy, and 11 were irradiated initially after recurrence. At a median follow-up of 5.1 years (range, 0.3-9.7 years), the latter group had the worst outcome, with a 5-year overall survival (OS) rate of 27% (95% CI, 7%-54%). Patients who started radiation therapy within 77 days after initial surgery had a better outcome compared with those who started later (5-year OS: 74% vs 32%; P = .05). Compliance with follow-up recommendations was poor. Only 22% of the patients had at least 2 IQ test assessments, and 50% showed some decline over time. Three cases of growth hormone deficiency were detected, but none of the patients received replacement therapy.

CONCLUSIONS

Access to pediatric neurosurgery, anesthesia, and timely radiation therapy are among the most challenging obstacles to be overcome in LMICs. Our series confirmed that chemotherapy is not an appropriate option for delaying radiation therapy, especially in young children. The importance of long-term follow-up should be acknowledged by the parents and medical team.

Conformal Radiation Therapy for Ependymoma at Age ≤3 Years: A 25-Year Experience

PURPOSE

Adjuvant radiation therapy (RT) affects survival after surgery for young children (age <3 years) diagnosed with intracranial ependymoma. Conformal photon RT promised to spare normal tissue and was introduced more than 25 years ago to improve outcomes for these vulnerable patients. Long-term results for those first treated with conformal methods provide valuable information and serve as a comparison against newer methods.

METHODS AND MATERIALS

Between 1997 and 2018, 101 patients <3.1-years-old were treated with conformal and intensity modulated photon therapy after definitive surgery for intracranial ependymoma. The median age at RT was 2.1 years and the time from diagnosis to the start of RT was 10 weeks. The extent of resection was gross-total in 82%, and 38% underwent more than 1 attempt at resection. The total prescribed dose was 54 to 59.4 Gy at 1.8 Gy per fraction.

RESULTS

The 10-year event-free and overall survivals were 58.5% ± 5.0% and 72.6% ± 4.5%, respectively, with a median follow-up of 18.4 years (range, 4.2-23.3 years). Tumor progression occurred in 34 patients with a median time of 1.6 years. Death occurred in 34 patients from ependymoma (n = 24), secondary malignancy (n = 6), necrosis (n = 2), shunt failure (n = 1), and anaphylactic reaction (n = 1). Twenty-three patients developed a secondary tumor including 6 cases of fatal high-grade glioma. Of the surviving cohort and those ≥18 years old, 98% obtained a high school diploma, 64% had a current driver's license, 89% were students or employed full or part time, 32% were living independently, and 70% received higher education or training.

CONCLUSIONS

Long-term results of children treated using photon conformal RT after surgery demonstrate that adjuvant RT resulted in long-term disease control and functional independence. These results point to the need for new treatment strategies to improve tumor control and provide investigators hope that newer RT methods will further reduce complications.

EZHIP: a new piece of the puzzle towards understanding pediatric posterior fossa ependymoma

Ependymomas (EPN) are tumors of the central nervous system (CNS) that can arise in the supratentorial brain (ST-EPN), hindbrain or posterior fossa (PF-EPN) or anywhere in the spinal cord (SP-EPN), both in children and adults. Molecular profiling studies have identified distinct groups and subtypes in each of these anatomical compartments. In this review, we give an overview on recent findings and new insights what is driving PFA ependymomas, which is the most common group. PFA ependymomas are characterized by a young median age at diagnosis, an overall balanced genome and a bad clinical outcome (56% 10-year overall survival). Sequencing studies revealed no fusion genes or other highly recurrently mutated genes, suggesting that the disease is epigenetically driven. Indeed, recent findings have shown that the characteristic global loss of the repressive histone 3 lysine 27 trimethylation (H3K27me3) mark in PFA ependymoma is caused by aberrant expression of the enhancer of zeste homolog inhibitory protein (EZHIP) or in rare cases by H3K27M mutations, which both inhibit EZH2 thereby preventing the polycomb repressive complex 2 (PRC2) from spreading H3K27me3. We present the current status of the ongoing work on EZHIP and its essential role in the epigenetic disturbance of PFA biology. Comparisons to the oncohistone H3K27M and its role in diffuse midline glioma (DMG) are drawn, highlighting similarities but also differences between the tumor entities and underlying mechanisms. A strong focus is to point out missing information and to present directions of further research that may result in new and improved therapies for PFA ependymoma patients.

Pediatric CNS imaging and long-term effects of irradiation in pediatric oncology patients

BACKGROUND

The aim of this study was to evaluate post-irradiation changes in the central nervous system (CNS) detected using magnetic resonance (MR) imaging.

METHODS

Magnetic resonance images of 15 children with CNS tumors treated through whole-brain irradiation over 10 years were reviewed retrospectively. Variables such as age at the time of irradiation, total radiation dose, treatment length, and time interval between irradiation and MR changes, were evaluated.

RESULTS

All patients included in the study had imaging abnormalities of the CNS. Eight patients (53%) developed CNS abnormalities within a short period of time - only a few months after irradiation (mean 4.8 months). Seven patients (47%) developed CNS abnormalities within a long time interval after treatment (mean 4.6 years). In almost all patients, a T2 increase in supra- and infratentorial white matter was observed. Follow-up examinations showed nine patients (60%) with cerebellar atrophy.

CONCLUSIONS

In this sample of pediatric patients who underwent whole-brain irradiation, the time receiving irradiation was not related to the severity of the MR changes. A correlation between the age of the child or the length of the radiotherapy and the extent of the changes could not be confirmed. However, we observed a trend towards stronger brain parenchymal degeneration with cystic changes in the younger age group of children in our sample. Older children who received irradiation seem to be more susceptible to vascular dysplasia with cavernous hemangiomas and microbleeding.

Intracranial ependymomas: molecular insights and translation to treatment

Ependymomas are primary central nervous system tumors (CNS), arising within the posterior fossa and supratentorial regions of the brain, and in the spine. Over the last decade, research has resulted in substantial insights into the molecular characteristics of ependymomas, and significant advances have been made in the establishment of a molecular classification system. Ependymomas both within and between the three CNS regions in which they arise, have been shown to contain distinct genetic, epigenetic and cytogenic aberrations, with at least three molecularly distinct subgroups identified within each region. However, these advances in molecular characterization have yet to be translated into clinical practice, with the standard treatment for ependymoma patients largely unchanged. This review summarizes the advances made in the molecular characterization of intracranial ependymomas, outlines the progress made in establishing preclinical models and proposes strategies for moving toward subgroup-specific preclinical investigations and treatment.

The value of high-dose radiotherapy in intracranial ependymoma

BACKGROUND

We sought to evaluate the impact of adjuvant radiotherapy dose on overall survival (OS) after surgical resection for localized intracranial ependymoma.

PROCEDURE

The National Cancer Database (NCDB) was queried from 2004 to 2015 for patients of all ages with intracranial WHO grade II to III ependymoma treated with surgery and 4500 to 7000 cGy of adjuvant radiotherapy. Pearson χ² test and multivariate logistic regression analyses were used to assess clinicodemographic factors and patterns of care. After propensity-score matching, OS was assessed with Kaplan-Meier analyses and doubly robust estimation with multivariate Cox proportional hazards modeling.

RESULTS

Of the 1153 patients meeting criteria, 529 (46%) received ≤ 5400 cGy and 624 (54%) received > 5400 cGy. At a median follow-up of 54.5 months, an OS benefit was observed for > 5400 cGy in pediatric patients aged 2-18 years (hazard ratio [HR] 0.53; 95% confidence interval [CI] 0.28-0.99, P = 0.047). No OS difference was found between ≤ 5400 cGy and > 5400 cGy in pediatric patients aged < 2 years (P = 0.819) or in adults (P = 0.180). Increasing age, WHO grade III, subtotal resection, and receipt of chemotherapy portended worse OS. Age 2 to 18 years, WHO III grade, supratentorial location, and receipt of chemotherapy were associated with receiving > 5400 cGy.

CONCLUSION

Adjuvant radiotherapy dose > 5400 cGy was associated with improved OS for children aged 2-18 years with WHO grade II-III intracranial ependymoma. No OS benefit was found with > 5400 cGy in adults or children less than two years of age.

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.

Therapeutic Impact of Cytoreductive Surgery and Irradiation of Posterior Fossa Ependymoma in the Molecular Era: A Retrospective Multicohort Analysis

PURPOSE

Posterior fossa ependymoma comprises two distinct molecular variants termed EPN_PFA and EPN_PFB that have a distinct biology and natural history. The therapeutic value of cytoreductive surgery and radiation therapy for posterior fossa ependymoma after accounting for molecular subgroup is not known.

METHODS

Four independent nonoverlapping retrospective cohorts of posterior fossa ependymomas (n = 820) were profiled using genome-wide methylation arrays. Risk stratification models were designed based on known clinical and newly described molecular biomarkers identified by multivariable Cox proportional hazards analyses.

RESULTS

Molecular subgroup is a powerful independent predictor of outcome even when accounting for age or treatment regimen. Incompletely resected EPN_PFA ependymomas have a dismal prognosis, with a 5-year progression-free survival ranging from 26.1% to 56.8% across all four cohorts. Although first-line (adjuvant) radiation is clearly beneficial for completely resected EPN_PFA, a substantial proportion of patients with EPN_PFB can be cured with surgery alone, and patients with relapsed EPN_PFB can often be treated successfully with delayed external-beam irradiation.

CONCLUSION

The most impactful biomarker for posterior fossa ependymoma is molecular subgroup affiliation, independent of other demographic or treatment variables. However, both EPN_PFA and EPN_PFB still benefit from increased extent of resection, with the survival rates being particularly poor for subtotally resected EPN_PFA, even with adjuvant radiation therapy. Patients with EPN_PFB who undergo gross total resection are at lower risk for relapse and should be considered for inclusion in a randomized clinical trial of observation alone with radiation reserved for those who experience recurrence.

Final results of the second prospective AIEOP protocol for pediatric intracranial ependymoma

BACKGROUND

This prospective study stratified patients by surgical resection (complete = NED vs incomplete = ED) and centrally reviewed histology (World Health Organization [WHO] grade II vs III).

METHODS

WHO grade II/NED patients received focal radiotherapy (RT) up to 59.4 Gy with 1.8 Gy/day. Grade III/NED received 4 courses of VEC (vincristine, etoposide, cyclophosphamide) after RT. ED patients received 1-4 VEC courses, second-look surgery, and 59.4 Gy followed by an 8-Gy boost in 2 fractions on still measurable residue. NED children aged 1-3 years with grade II tumors could receive 6 VEC courses alone.

RESULTS

From January 2002 to December 2014, one hundred sixty consecutive children entered the protocol (median age, 4.9 y; males, 100). Follow-up was a median of 67 months. An infratentorial origin was identified in 110 cases. After surgery, 110 patients were NED, and 84 had grade III disease. Multiple resections were performed in 46/160 children (28.8%). A boost was given to 24/40 ED patients achieving progression-free survival (PFS) and overall survival (OS) rates of 58.1% and 68.7%, respectively, in this poor prognosis subgroup. For the whole series, 5-year PFS and OS rates were 65.4% and 81.1%, with no toxic deaths. On multivariable analysis, NED status and grade II were favorable for OS, and for PFS grade II remained favorable.

CONCLUSIONS

In a multicenter collaboration, this trial accrued the highest number of patients published so far, and results are comparable to the best single-institution series. The RT boost, when feasible, seemed effective in improving prognosis. Even after multiple procedures, complete resection confirmed its prognostic strength, along with tumor grade. Biological parameters emerging in this series will be the object of future correlatives and reports.

Posterior fossa tumors in infants and neonates

INTRODUCTION

Management of posterior fossa tumors in infants and neonates is challenging. The characteristics of the young babies make surgery very difficult, sometimes precluding a safe complete removal.

METHODS

A review of the literature was undertaken to examine the incidence, histology, surgical aspects, and prognosis of posterior fossa tumors in the first year of life. Therapeutical strategies of the most frequent tumor types are also discussed in detail.

RESULTS

Histology is dominated by tumors with aggressive behavior, such as medulloblastomas, atypical teratoid/rhabdoid tumors, and anaplastic ependymomas. The most important surgical considerations in small children are the small circulating blood volume; the poor thermoregulation; and incomplete maturation of the brain, of the skull, and of the soft tissue. Treatment toxicity is inversely related to the age of the patients. Radiation therapy is usually considered as contraindicated in young children, with few exceptions. Proton therapy is a promising tool, but access to this kind of treatment is still limited. The therapeutic limitations of irradiation render resection of this tumor and adjuvant chemotherapy often the only therapeutic strategy in many cases.

CONCLUSIONS

The overall prognosis remains dismal because of the prevalent aggressive histologies, the surgical challenges, and the limitations of adjuvant treatment. Nevertheless, the impressive improvements in anesthesiology and surgical techniques allow, in the vast majority of the cases, complete removal of the lesions with minor sequelae in high-volume referral pediatric centers.

EphB2 activation is required for ependymoma development as well as inhibits differentiation and promotes proliferation of the transformed cell

Our intracranial implantation mouse model of ependymoma clearly demonstrates overexpression of the ephrin receptor EphB2 in Ink4a/Arf^(−/−) supratentorial embryonic neural stem cells (STeNSCs) to be essential for transformation and disease development; however the requirement for and consequence of receptor activation on transformation and neural stem cell function were not examined. We definitively illustrate the necessity for receptor activation in cellular transformation and the importance of implantation site and microenvironment in directing ependymoma development. In vitro assays of EphB2 overexpressing Ink4a/Arf^(−/−) STeNSCs showed no changes in their neural stem cell characteristics (stem cell marker expression and self-renewal) upon receptor activation, but EphB2 driven tumor cells were inhibited significantly in differentiation and exhibited increased tumorsphere formation and cellular proliferation in response to ephrin-B ligand mediated receptor activation. Additionally, we observed substantial differences in the phosphorylation state of several key proteins involved in Ras and p38 MAPK signaling when comparing EphB2 overexpressing Ink4a/Arf^(−/−) STeNSCs and tumor cells with relatively little change in total protein levels. We propose that EphB2 mediated ependymoma development is a multifactorial process requiring microenvironment directed receptor activation, resulting in changes in the phosphorylation status of key regulatory proteins, maintenance of a stem-like state and cellular proliferation.

The molecular landscape of pediatric brain tumors in the next-generation sequencing era

Pediatric brain tumors are a leading cause of cancer-related death in children. In recent years, the application of next-generation sequencing and other high-throughput technologies to analysis of pediatric brain tumors has generated an abundance of molecular information. This has provided an unprecedented understanding of their biology and is refining tumor classification into clinically relevant subgroups. In this review, we provide an overview of our evolving molecular knowledge of the commonest pediatric brain tumors, pilocytic astrocytomas, ependymomas, medulloblastomas, and pediatric glioblastomas, as well as the biological and potential clinical implications of this new knowledge. Studies aimed at investigating intratumoral heterogeneity are also discussed.