Central nervous system atypical teratoid rhabdoid tumours: the Canadian Paediatric Brain Tumour Consortium experience

Radiation Therapy Plays an Important Role in the Treatment of Atypical Teratoid/Rhabdoid Tumors: Analysis of the EU-RHAB Cohorts and Their Precursors

PURPOSE

Atypical teratoid/rhabdoid tumor (AT/RT) is a rare malignancy of the central nervous system in young children with a dismal prognosis. Prognostic markers have been extensively investigated but have not been validated. The role of radiation therapy (RT) remains controversial. We evaluated the impact of RT as part of multimodality treatment by analyzing data of a European AT/RT cohort.

METHODS AND MATERIALS

We retrospectively analyzed data of the European Registry for Rhabdoid Tumors and its precursors. Primary endpoints were progression-free survival (PFS) and overall survival (OS). Potential impact of prognostic factors was analyzed using univariable and multivariable Cox regression analyses with RT as a time-dependent factor.

RESULTS

Data of 186 children (118 male, 68 female) treated from 1990 to 2016 were evaluable. The median age at diagnosis was 1.57 years (range, 0.01-26.70 years); 47% (87/186) of the patients were under the age of 18 months. Sixty-nine percent (128/186) received RT (focal RT, n = 93; craniospinal treatment with local boost, n = 34; spinal irradiation, n = 1). The median follow-up duration of the entire cohort was 1.73 years (range, 0.06-20.11 years). The estimated PFS and OS rates were 48% (95% CI, 41%-55%) and 72% (95% CI, 65%-78%) at 1 year and 33% (95% CI, 26%-40%) and 49% (95% CI, 41%-56%) at 2 years, respectively. On multivariable analysis, RT was an independent significant prognostic factor for PFS (hazard ratio, 0.45; 95% CI, 0.27-0.75; P = .002) and OS (hazard ratio, 0.54; 95% CI, 0.32-0.93; P = .025).

CONCLUSIONS

This analysis confirms the relevance of local therapies. RT was an independent prognostic factor for outcomes in children experiencing AT/RT. However, long-term sequelae have to be carefully evaluated and considered given the young age at time of RT.

ESTRO-SIOPE guideline: Clinical management of radiotherapy in atypical teratoid/rhabdoid tumors (AT/RTs)

BACKGROUND AND PURPOSE

Treatment of patients with atypical teratoid/rhabdoid (AT/RT) is challenging, especially when very young (below the age of three years). Radiotherapy (RT) is part of a complex trimodality therapy. The purpose of this guideline is to provide appropriate recommendations for RT in the clinical management of patients not enrolled in clinical trials.

MATERIALS AND METHODS

Nine European experts were nominated to form a European Society for Radiotherapy and Oncology (ESTRO) guideline committee. A systematic literature search was conducted in PubMed/MEDLINE and Web of Science. They discussed and analyzed the evidence concerning the role of RT in the clinical management of AT/RT.

RESULTS

Recommendations on diagnostic imaging, therapeutic principles, RT considerations regarding timing, dose, techniques, target volume definitions, dose constraints of radiation-sensitive organs at risk, concomitant chemotherapy, and follow-up were considered. Treating children with AT/RT within the framework of prospective trials or prospective registries is of utmost importance.

CONCLUSION

The present guideline summarizes the evidence and clinical-based recommendations for RT in patients with AT/RT. Prospective clinical trials and international, large registries evaluating modern treatment approaches will contribute to a better understanding of the best treatment for these children in future.

SMARCB1 Gene Therapy Using a Novel Tumor-Targeted Nanomedicine Enhances Anti-Cancer Efficacy in a Mouse Model of Atypical Teratoid Rhabdoid Tumors

Purpose

Atypical teratoid rhabdoid tumor (ATRT) is a deadly, fast-growing form of pediatric brain cancer with poor prognosis. Most ATRTs are associated with inactivation of SMARCB1, a subunit of the chromatin remodeling complex, which is involved in developmental processes. The recent identification of SMARCB1 as a tumor suppressor gene suggests that restoration of SMARCB1 could be an effective therapeutic approach.

Methods

We tested SMARCB1 gene therapy in SMARCB1-deficient rhabdoid tumor cells using a novel tumor-targeted nanomedicine (termed scL-SMARCB1) to deliver wild-type SMARCB1. Our nanomedicine is a systemically administered immuno-lipid nanoparticle that can actively cross the blood-brain barrier via transferrin receptor-mediated transcytosis and selectively target tumor cells via transferrin receptor-mediated endocytosis. We studied the antitumor activity of the scL-SMARCB1 nanocomplex either as a single agent or in combination with traditional treatment modalities in preclinical models of SMARCB1-deficient ATRT.

Results

Restoration of SMARCB1 expression by the scL-SMARCB1 nanocomplex blocked proliferation, and induced senescence and apoptosis in ATRT cells. Systemic administration of the scL-SMARCB1 nanocomplex demonstrated antitumor efficacy as monotherapy in mice bearing ATRT xenografts, where the expression of exogenous SMARCB1 modulates MYC-target genes. scL-SMARCB1 demonstrated even greater antitumor efficacy when combined with either cisplatin-based chemotherapy or radiation therapy, resulting in significantly improved survival of ATRT-bearing mice.

Conclusion

Collectively, our data suggest that restoring SMARCB1 function via the scL-SMARCB1 nanocomplex may lead to therapeutic benefits in ATRT patients when combined with traditional chemoradiation therapies.

Rhabdoid tumor predisposition syndrome: A historical review of treatments and outcomes for associated pediatric malignancies

Rhabdoid tumor predisposition syndrome (RTPS) is a rare disorder associated with malignant rhabdoid tumor of the kidney (RTK), atypical teratoid rhabdoid tumor (ATRT), and/or other extracranial, extrarenal rhabdoid tumors (EERT), and these pediatric malignancies are difficult to treat. Presently, most of the information regarding clinical manifestations, treatment, and outcomes of rhabdoid tumors comes from large data registries and case series. Our current understanding of treatments for patients with rhabdoid tumors may inform how we approach patients with RTPS. In this manuscript, we review the genetic and clinical features of RTPS and, using known registry data and clinical reports, review associated tumor types ATRT, RTK, and EERT, closing with potential new approaches to treatment. We propose collaborative international efforts to study the use of SMARC (SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin)-targeting agents, high-dose consolidative therapy, and age-based irradiation of disease sites in RTPS.

Atypical teratoid/rhabdoid tumor in adult: case series and an integrated survival analysis

BACKGROUND

Atypical teratoid/rhabdoid tumor (AT/RT) is well documented in children but less so in adults because of its rarity.

METHOD

We report a series of five cases, a literature review and quantitative analysis of the survival outcome of adult AT/RT patients.

RESULTS

Seventy-four patients including our five cases (male: female = 16: 58) were evaluated, whose median age was 32.5 years (18-80 years). The commonest location was the sellar region. Median overall survival (OS) was 12.5 months (0.5-204.00 months). Chemotherapy was associated with OS (HR: 0.349, 95%CI: 0.176-0.694, p = 0.003), while other factors did not influence OS. From Kaplan-Meier analysis, surgery combining postoperative chemotherapy and radiotherapy was associated with better prognosis (Log Rank: χ2 = 14.662, p = 0.001).

CONCLUSIONS

Adult AT/RT is commoner in females and tends to recur rapidly after surgical resection. Chemotherapy may provide a survival benefit. Surgery combined with postoperative chemotherapy and radiotherapy was associated with better prognosis for adult AT/RT patients, though the overall prognosis was still poor.

Atypical teratoid rhabdoid tumor in a lower middle‑income country: Challenges to cure

Atypical teratoid rhabdoid tumor (ATRT) is a rare type of potentially fatal childhood brain tumor. The present study aimed to examine the overall survival (OS) and event-free survival (EFS) outcomes of pediatric patients with ATRT and to analyze the impact of different prognostic factors, including age, sex, tumor site and size, metastatic disease, the extent of resection, radiotherapy, and chemotherapy, on survival. The present study included 47 patients with ATRT treated at the Children's Cancer Hospital of Egypt (Cairo, Egypt) between July 2007 and December 2017. These patients were treated according to the Dana-Farber Cancer Institute protocol 02-294 for 51 weeks. Various prognostic factors, including age, sex, tumor size and initial metastatic status, exhibited no impact on the radiological response measured at 6 weeks and at the end of treatment. The primary tumor site significantly affected the response to treatment at 6 weeks (P=0.008). Toxicity-related mortality occurred in 29.8% of patients. The median duration of the treatment protocol was 66.9 weeks. The duration of treatment was in the present cohort was longer than the actual 51 weeks of the protocol due to prolonged supportive care of the included patients. Patients who encountered toxicity received reduced dose of chemotherapy in the subsequent cycles in the protocol. Age, initial metastatic status, tumor site and resection extent did not significantly affect the patient outcomes. Preoperative tumor size significantly affected the EFS (P=0.03) and OS (P=0.04). Radiotherapy administration significantly affected the OS (P<0.001) and EFS (P<0.001). The median EFS and OS of patients were 9.3 and 10.3 months, respectively. A total of 24 (51.1%) patients exhibited disease progression or recurrence. The progression sites were local (n=6), metastatic (n=9) or both local and metastatic (n=9). The results of the present study demonstrated that the therapeutic regimen should be patient-adjusted to maintain the treatment intensity and avoid toxicity-related mortality. In lower middle-income countries, short and intensified induction followed by consolidation of treatment, either by single or tandem autologous stem cell transplant, is needed to avoid prolonged exposure to myelosuppression and toxicity-related mortality.

Management of Atypical Teratoid/Rhabdoid Tumors in the Pediatric Population: A Systematic Review and Meta-Analysis

BACKGROUND

Atypical teratoid/rhabdoid tumors are rare and aggressive tumors that mainly affect children <3 years of age. Despite aggressive treatment, the overall survival rate for pediatric atypical teratoid/rhabdoid tumors remains poor. Due to their rarity, little is known regarding prognostic factors, and there is no official standard of treatment.

METHODS

A comprehensive database search was conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Search terms included "atypical teratoid rhabdoid tumor" and "atypical (teratoid OR rhabdoid) tumor." Variables of interest included, but were not limited to, age, sex, tumor location, treatment modality, extent of resection, and overall survival.

RESULTS

The study included 294 articles and 936 patients. The median age of patients was 22 months. There was a significant difference in survival among patients receiving surgery compared with patients receiving nonoperative treatment (50.3 months vs. 28 months; P < 0.005). Extent of resection did not significantly improve survival (P = 0.832 for gross total resection, P = 0.650 for partial resection). Combination therapy with surgical resection, radiotherapy, and chemotherapy demonstrated the largest median overall survival (54.9 months) and significantly improved survival on multivariate analysis (hazard ratio, 0.48; 95% confidence interval, 0.23-0.97; P = 0.042).

CONCLUSIONS

The results of this study indicate that while surgery is a crucial treatment modality for pediatric atypical teratoid/rhabdoid tumors, the effect of extent of resection is unclear. Multimodal therapy including surgery, radiotherapy, and chemotherapy is effective in improving overall survival. Future studies should focus on using larger datasets to efficiently account for confounding factors and biases.

Atypical teratoid/rhabdoid tumour with CDK6 amplification in a child: a case report and literature review

Atypical teratoid/rhabdoid tumours (AT/RTs) are rare central nervous system neoplasms that frequently occur in infants and children and have a very poor prognosis. In recent years, molecular analysis of AT/RTs has shown that biallelic inactivation of SMARCB1 (INI1, SNF5, BAF47) or SMARCA4 (BRG1) frequently occurs. Here, we present a case of basal ganglia AT/RT with SMARCB1 gene deficiency and CDK6 gene amplification in a 5-year-old child. A 5-year-old boy was hospitalized due to a 1-week history of frontal and parietal headache. Magnetic resonance imaging (MRI) demonstrated a 3 cm × 2 cm × 1.5 cm heterogeneous enhanced mass located at the right basal ganglia that partially protruded into the right lateral ventricle. The lesion was successfully resected under electrophysiological monitoring and neuronavigation. The postoperative pathological examination implied an AT/RT diagnosis, with loss of SMARCB1 protein, SMARCB1 gene deficiency and CDK6 gene amplification. Unfortunately, the patient died due to respiratory and circulatory failure at 5 weeks after the operation. To date, standard regimens have not yet been established due to the lack of large-scale prospective studies for AT/RT. The p16-RB signalling pathway should be considered as a potential target for AT/RT treatment modalities. Apart from traditional regimens, targeted therapies, especially CDK4/6 inhibitors, are likely a promising therapeutic option for AT/RT treatment.

Spinal atypical teratoid rhabdoid tumor-narrative review and report of a rare case managed with multimodality approach

BACKGROUND

Spinal atypical teratoid rhabdoid tumor (AT/RT) is an extremely rare tumor and represents less than 2% of all AT/RTs.

METHODS

Available medical literature on spinal AT/RT in English was retrieved from PubMed and comprehensively reviewed. Clinical presentation, diagnosis, management, prognosis, and outcome in patients with spinal AT/RT have been elucidated by citing a case of extradural AT/RT of the cervicodorsal spine.

RESULTS

The age at presentation is usually less than 3 years. The most common site is the cervicodorsal spine. The most frequent tumor location is intradural extramedullary. A contrast-enhanced magnetic resonance imaging (MRI) of the entire neuraxis is the imaging modality of choice. The incidence of leptomeningeal dissemination is high (15-30%). Histopathological examination shows an admixture of primitive neuroectodermal, mesenchymal, and epithelial elements along with rhabdoid cells. Loss of SMARCB1/INI1 is considered pathognomonic of AT/RT. Maximal safe resection of tumor is the initial management of choice. Thereafter focal radiotherapy for localized tumor or craniospinal irradiation for leptomeningeal dissemination should be considered. Post-operative intensive polychemotherapy including intrathecal and high-dose chemotherapy (with autologous stem cell rescue) is usually considered to optimize survival. Typically, the time to recurrence and overall survival are less than 6 and 12 months, respectively. However, with judicious multimodality management long-term survivors are increasingly being recognized. The illustrative patient was a 18-month-old girl diagnosed with extradural AT/RT of the cervicodorsal spine (C3-D1), who was managed with maximal safe resection of tumor, multiagent chemotherapy (ICE-ifosfamide, carboplatin, etoposide) and focal RT to the tumor bed-50.4 Gy/28 fractions/5.5 weeks. At the last follow-up visit, 30 months after surgery, she had complete clinicoradiological response.

CONCLUSION

Multimodal treatment comprising maximal safe resection of tumor, multiagent chemotherapy (ICE), and focal RT can lead to successful outcome in patients with localized spinal AT/RT, under the age of 3 years.

Novel Strategy Involving High-Dose Chemotherapy with Stem Cell Rescue Followed by Intrathecal Topotecan Maintenance Therapy without Whole-Brain Irradiation for Atypical Teratoid/Rhabdoid Tumors

Atypical teratoid/rhabdoid tumor (AT/RT) is a rare aggressive central nervous system tumor that typically affects children under three years old and has poor survival with a high risk for neurologic deficits. The primary purpose of this study was to successfully treat the disease and delay or avoid whole-brain radiotherapy for children with AT/RT. A retrospective analysis was performed for six children diagnosed with AT/RT and treated with multimodal treatment at a single institute between 2014 and 2020. Furthermore, germline SMARCB1 aberrations and MGMT methylation status of the tumors were analyzed. One patient who did not receive a modified IRS-III regimen replaced with ifosphamide, carboplatin, and etoposide (ICE) in induction chemotherapy was excluded from this analysis. Five patients who received ICE therapy were under three years old. After a surgical approach, they received intensive chemotherapy and high-dose chemotherapy with autologous peripheral blood stem cell transplantation (HDCT/autoPBSCT) followed by intrathecal topotecan maintenance therapy. Three patients underwent single HDCT/autoPBSCT, and the other two received sequential treatment. Two patients with germline SMARCB1 aberrations and metastases died of progressive AT/RT or therapy-related malignancy, while 3 with localized tumors without germline SMARCB1 aberrations remained alive. One survivor received local radiotherapy only, while the other two did not undergo radiotherapy. All three surviving patients were able to avoid whole-brain radiotherapy. Our results suggest that AT/RT patients with localized tumors without germline SMARCB1 aberrations can be rescued with multimodal therapy, including induction therapy containing ICE followed by HDCT/autoPBSCT and intrathecal topotecan maintenance therapy without radiotherapy. Further large-scale studies are necessary to confirm this hypothesis.

Radiotherapy for Atypical Teratoid/=Rhabdoid Tumor (ATRT) on the Pediatric Proton/Photon Consortium Registry (PPCR)

PURPOSE

Atypical teratoid/rhabdoid tumors (ATRT) of the central nervous system (CNS) are rare tumors with a poor prognosis and variable use of either focal or craniospinal (CSI) radiotherapy (RT). Outcomes on the prospective Pediatric Proton/Photon Consortium Registry (PPCR) were evaluated according to RT delivered.

METHODS

Pediatric patients receiving RT were prospectively enrolled on PPCR to collect initial patient, disease, and treatment factors as well as provide follow-up for patient outcomes. All ATRT patients with evaluable data were included. Kaplan-Meier analyses with log-rank p-values and cox proportional hazards regression were performed.

RESULTS

The PPCR ATRT cohort includes 68 evaluable ATRT patients (median age 2.6 years, range 0.71-15.40) from 2012 to 2021. Median follow-up was 40.8 months (range 3.4-107.7). Treatment included surgery (65% initial gross total resection or GTR), chemotherapy (60% with myeloablative therapy including stem cell rescue) and RT. For patients with M0 stage (n = 60), 50 (83%) had focal RT and 10 (17%) had CSI. Among patients with M + stage (n = 8), 3 had focal RT and 5 had CSI. Four-year overall survival (OS, n = 68) was 56% with no differences observed between M0 and M + stage patients (p = 0.848). Local Control (LC) at 4 years did not show a difference for lower primary dose (50-53.9 Gy) compared to ≥ 54 Gy (73.3% vs 74.7%, p = 0.83). For patients with M0 disease, four-year OS for focal RT was 54.6% and for CSI was 60% (Hazard Ratio 1.04, p = 0.95. Four-year event free survival (EFS) among M0 patients for focal RT was 45.6% and for CSI was 60% (Hazard Ratio 0.71, p = 0.519). For all patients, the 4-year OS comparing focal RT with CSI was 54.4% vs 60% respectively (p = 0.944), and the 4-year EFS for focal RT or CSI was 42.8% vs 51.4% respectively (p = 0.610).

CONCLUSION

The PPCR ATRT cohort found no differences in outcomes according to receipt of either higher primary dose or larger RT field (CSI). However, most patients were M0 and received focal RT. A lower primary dose (50.4 Gy), regardless of patient age, is appealing for further study as part of multi-modality therapy.

Atypical teratoid rhabdoid tumours (ATRTs)-a 21-year institutional experience

PURPOSE

Atypical teratoid/rhabdoid tumours (ATRTs) are malignant embryonal tumours of childhood that affect the central nervous system (CNS). We aim to determine which factors, including patient age, extent of resection (EOR), presence of distal metastasis and use of adjuvant therapies, affect overall survival in children with atypical teratoid/rhabdoid tumours (ATRTs) treated at this single centre.

METHODS

Retrospective cohort review of patients with histological diagnosis of ATRT treated over 21 years (1999-2020) was conducted. Data on demographics, tumour location, presence of metastasis, use of adjuvant therapy, extent of resection (EOR), complications, neurological outcome post-surgery, and overall survival were collected. Kaplan-Meier survival analysis was performed.

RESULTS

A total of 45 children (mean age 2 years) underwent 64 operations. 25 patients were <1 year of age. Gross-total resection (GTR) pre-adjuvant therapy was achieved in 15, near-total resection (NTR) in 15, subtotal resection (STR) in 9, and biopsy in 6 children. Most children had good neurological outcomes post-operatively (28/45 with GOS 5). Fourteen patients survived longer than 4 years. Survival analysis showed a significant difference in median survival in favour of GTR and localised disease. There was no significant difference in median survival between patients <1 year vs >1 year of age (p=0.84).

CONCLUSION

We find that presence of metastasis was an important factor in poor survival in patients with ATRT. GTR, where possible, may confer significant survival benefit in ATRT. Children aged <1 year appear to have performed as well as those >1 year and therefore should still be considered for radical surgery.

Embryonal Tumors of the Central Nervous System with Multilayered Rosettes and Atypical Teratoid/Rhabdoid Tumors

The 2016 WHO classification of tumors of the central nervous system affected importantly the group of CNS embryonal tumors. Molecular analysis on methylome, genome, and transcriptome levels allowed better classification, identification of specific molecular hallmarks of the different subtypes of CNS embryonal tumors, and their more precise diagnosis. Routine application of appropriate molecular testing and standardized reporting are of pivotal importance for adequate prognosis and treatment, but also for epidemiology studies and search for efficient targeted therapies. As a result of this approach, the term primitive neuroectodermal tumor-PNET was removed and a new clinic-pathological entity was introduced-Embryonal tumor with multilayered rosettes (ETMR). The group of CNS embryonal tumors include also medulloblastoma, medulloepithelioma, CNS neuroblastoma, CNS ganglioneuroblastoma, atypical teratoid/rhabdoid tumor (ATRT) and their subtypes. This chapter will focus mainly on ETMR and ATRT. Embryonal tumors with multilayered rosettes and the atypical teratoid/rhabdoid tumors are undifferentiated or poorly differentiated tumors of the nervous system that originate from primitive brain cells, develop exclusively in childhood or adolescence, and are characterized by a high degree of malignancy, aggressive evolution and a tendency to metastasize to the cerebrospinal fluid. Their clinical presentation is similar to other malignant, intracranial, neoplastic lesions and depends mainly on the localization of the tumor, the rise of the intracranial pressure, and eventually the obstruction of the cerebrospinal fluid pathways. The MRI image characteristics of these tumors are largely overlappingintra-axial, hypercellular, heterogeneous tumors, frequently with intratumoral necrosis and/or hemorrhages. Treatment options for ETMR and ATRT are very restricted. Surgery can seldom achieve radical excision. The rarity of the disease hampers the establishment of a chemotherapy protocol and the usual age of the patients limits severely the application of radiotherapy as a therapeutic option. Consequently, the prognosis of these undifferentiated, malignant, aggressive tumors remains dismal with a 5-year survival between 0 and 30%.

Atypical teratoid rhabdoid tumor with intratumoral advancement: significance of active surgical approach in long-term disease (109 months) with metastatic cascade

The article presents a clinical case of atypical teratoid rhabdoid tumor with one of the longest catamnesis described in literature (109 months) and high quality of life. first, a giant tumor of the frontal lobe with advancement into a lateral ventricle was found in a female patient and totally removed. It was histologically diagnosed as primitive neuroectodermal tumor. Combination treatment consisting of radiotherapy, high-dose polychemotherapy and cellular immunotherapy including intrathecal therapy led to 4-year recurrence-free period. Recurrence of the tumor was resected. The period of the 2nd remission was 34 months. Subsequently, multistage metastasis of the tumor through cerebrospinal fluid tracts of the brain and spinal cord was observed. Twice microsurgical treatment with removal of symptomatic metastases in ventricles Iv and III was performed. In repeat morphological examinations, the tumor was verified as atypical teratoid rhabdoid tumor. The presented clinical case shows the role of active surgical tactics in effective long-term combination treatment of this severe pathology.

Magnetic Resonance Imaging (MRI) and Positron Emission Tomography (PET)/Computed Tomography Features of Atypical Teratoid/Rhabdoid Tumors: Case Series and Review

Purpose: The purpose of this article is to explore the clinical and neuroradiologic properties of atypical teratoid/rhabdoid tumors. Methods: Data from 6 pediatric patients with atypical teratoid/rhabdoid tumors, which mainly contained the features of magnetic resonance imaging (MRI) and positron emission tomography (PET)/computed tomography (CT), was retrospectively analyzed. Follow-up was conducted in all patients through clinic services and/or telephone consultation. Results: The patients included 4 males and 2 females, aged from 3.2 to 83.1 months at the initial diagnosis. All patients had MRI scans. Two patients underwent ¹⁸F-fluorodeoxyglucose PET/CT scintigraphy preoperatively and 4 postoperatively. All primary lesions were located in the cranial cavity and the average diameter of lesions was 37.2 mm. Cerebrospinal fluid spread on enhanced T1-weighted images were found in 2 patients. Multiple metastases were found on MRI and PET/CT scans, which were located at cranial cavity, spinal cord, lung and lymph node. The primary and metastatic lesions showed evident uptake of ¹⁸F-fluorodeoxyglucose. Two patients underwent total tumor removal, and 4 patients underwent subtotal removal. None of the patients received shunt surgery. Follow-up was performed in all 6 patients. One patient survived event-free 38.4 months after resection. The mean overall survival of the remaining 5 patients was 5.1 months. Conclusion: We identified specific PET/CT and MRI features that can facilitate the recognition of atypical teratoid/rhabdoid tumors prior to biopsy.

Case report: Atypical teratoid/rhabdoid tumor of the lateral ventricle in a male adolescent (case-based review and diagnostic challenges in developing countries)

Atypical teratoid/rhabdoid tumor (AT/RT) is a rare and highly malignant central nervous system (CNS) embryonal neoplasm: it accounts for <2% of all pediatric CNS tumors and occurs mainly in infants and young children. The primary site of this tumor is usually the posterior cranial fossa. Supratentorial and, in detail, latero-ventricular location is extremely uncommon, especially in adolescents. This tumor is characterized by rapid growth and spread in cerebrospinal fluid and, therefore, it is characterized by a poor prognosis. Neurological signs and symptoms are related the location of the tumor. The radiological features of AT/RT are nonspecific. Immunohistochemical staining for loss of nuclear integrase interactor 1 (INI1) expression is considered a reliable criterion for the diagnosis of this type of tumor. AT/RT has been linked to mutations of SMARCB1 or, rarely, SMARCA4 genes, which function as tumor suppressor genes. Currently, there is no validated protocol of treatment for children with AT/RT, and multimodality treatment (consisting of surgery, chemotherapy, and radiation therapy) is considered. In this case report, we describe a 15-year-old adolescent with an AT/RT of the left lateral ventricle. Despite the late diagnosis, the multimodal therapeutic approach provided a good outcome for our patient at 21 months' follow-up. Based on our case-based review, early diagnosis and a multimodal approach to treatment play a key role in improving the survival of patients with this diagnosis. Implementing a system supporting pathological and molecular analyses for developing countries and, in general, for non-academic centers is of primary importance to timely diagnose and treat rare tumors, such as AT/RT.

Human Malignant Rhabdoid Tumor Antigens as Biomarkers and Potential Therapeutic Targets

Simple Summary

Atypical teratoid rhabdoid tumor (ATRT) is a deadly type of human pediatric brain cancer without effective treatments. ATRT is mainly linked to the inactivation of a tumor suppressor gene, SMARCB1; however, additional biomarkers remain to be identified to develop novel therapeutic strategies. Therefore, different tumor antigens and extracellular matrix modulators were investigated in two human ATRT and one kidney malignant rhabdoid tumor cell lines and compared with the nonmalignant HEK293 cell line. Alpha-fetoprotein (AFP), mucin-16 (MUC16 or cancer antigen 125/CA125), osteopontin (OPN), and mesothelin (MSLN) are highly expressed in these human malignant rhabdoid cancer cell lines. Inhibiting MMPs using a small-molecule inhibitor decreased cell survival. This biomarker discovery process may lead to the identification of novel diagnostic and therapeutic strategies, such as the development of targeted and immunotherapies against cancer biomarkers, to treat cancer patients.

Abstract

Introduction: Atypical teratoid rhabdoid tumor (ATRT) is a lethal type of malignant rhabdoid tumor in the brain, seen mostly in children under two years old. ATRT is mainly linked to the biallelic inactivation of the SMARCB1 gene. To understand the deadly characteristics of ATRT and develop novel diagnostic and immunotherapy strategies for the treatment of ATRT, this study investigated tumor antigens, such as alpha-fetoprotein (AFP), mucin-16 (MUC16/CA125), and osteopontin (OPN), and extracellular matrix modulators, such as matrix metalloproteinases (MMPs), in different human malignant rhabdoid tumor cell lines. In addition, the roles of MMPs were also examined. Materials and methods: Five human cell lines were chosen for this study, including two ATRT cell lines, CHLA-02-ATRT and CHLA-05-ATRT; a kidney malignant rhabdoid tumor cell line, G401; and two control cell lines, human embryonic kidney HEK293 and HEK293T. Both ATRT cell lines were treated with a broad-spectrum MMP inhibitor, GM6001, to investigate the effect of MMPs on cell proliferation, viability, and expression of tumor antigens and biomarkers. Gene expression was examined using a reverse transcription polymerase chain reaction (RT-PCR), and protein expression was characterized by immunocytochemistry and flow cytometry. Results: All the rhabdoid tumor cell lines tested had high gene expression levels of MUC16, OPN, AFP, and MSLN. Low expression levels of neuron-specific enolase (ENO2) by the two ATRT cell lines demonstrated their lack of neuronal genotype. Membrane-type 1 matrix metalloproteinase (MT1-MMP/MMP-14) and tissue inhibitor of metalloproteinases-2 (TIMP-2) were highly expressed in these malignant rhabdoid tumor cells, indicating their invasive phenotypes. GM6001 significantly decreased ATRT cell proliferation and the gene expression of MSLN, OPN, and several mesenchymal markers, suggesting that inhibition of MMPs may reduce the aggressiveness of rhabdoid cancer cells. Conclusion: The results obtained from this study may advance our knowledge of the molecular landscapes of human malignant rhabdoid tumors and their biomarkers for effective diagnosis and treatment. This work analyzed the expression of human malignant rhabdoid tumor antigens that may serve as biomarkers for the development of novel therapeutic strategies, such as cancer vaccines and targeted and immunotherapies targeting osteopontin and mesothelin, for the treatment of patients with ATRT and other malignant rhabdoid tumors.

Sellar Atypical Teratoid/Rhabdoid Tumors (AT/RT): A Systematic Review and Case Illustration

Introduction: Atypical Teratoid/Rhabdoid tumors are rare, highly malignant tumors in adults, with a median survival of 20 months. We report a case of a sellar atypical teratoid/rhabdoid tumor in a 70-year-old female treated with intraventricular chemotherapy, followed by a systematic review of the current management of sellar AT/RTs.

Methods: A comprehensive systematic literature search was conducted on Web of Science, Scopus, and PubMed Central using the key terms “sellar” and “atypical teratoid/rhabdoid tumors”, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Data, including patient demographics, histology, treatments, and overall survival were extracted and analyzed. Kaplan-Meier survival curves and log-rank analysis were used to compare survival outcomes between different treatment regimens.

Results: Our literature search disclosed 123 publications. After prespecified exclusions, 41 patients with sellar AT/RT from 30 manuscripts were identified, and 38 were included in the final analysis. Including our patient, the median age was 44 (range: 20-70) with a substantial female predominance (94.7%). Collectively, patients who received combined chemoradiation therapy had a significantly increased overall survival compared to those who received single modality or no adjuvant therapies (median OS 27 vs. 1.25 months; p=0.0052).

Conclusion: Atypical teratoid/rhabdoid tumor in the sellar region carries a poor prognosis. Adjuvant chemotherapy and radiation therapy were associated with significantly increased overall survival. Early consideration of neuro-oncology and radiation-oncology referral and management is likely beneficial in this patient population. Intrathecal chemotherapy is a treatment modality that requires further exploration given the limited options and current dismal prognosis of adult sellar AT/RT.

Clinical predictors of survival for patients with atypical teratoid/rhabdoid tumors

PURPOSE

Atypical teratoid/rhabdoid tumors (AT/RTs) are malignant central nervous system (CNS) neoplasms of the young. Our study analyzed a large AT/RT cohort from the National Cancer Database (NCDB) to elucidate predictors of short-term mortality and overall survival (OS).

METHODS

Information was collected on patients with histologically confirmed AT/RT using the NCDB (2004-2016). Kaplan-Meier analysis indicated OS. Prognostic factors for 30-day mortality, 90-day mortality, and OS were determined via multivariate Cox proportional hazards (CPH) and logistic regression models.

RESULTS

Our cohort of 189 patients had a median age of 1 year (IQR [1, 4]) and tumor size of 4.7 ± 2.0 cm at diagnosis. Seventy-two percent were under 3 years old; 55.6% were male and 71.0% were Caucasian. Fifty (27.2%) patients received only surgery (S) (OS = 5.91 months), 51 (27.7%) received surgery and chemotherapy (S + CT) (OS = 11.2 months), and 9 (4.89%) received surgery and radiotherapy (S + RT) (OS = 10.3 months). Forty-five (24.5%) received S + CT + RT combination therapy (OS = 45.4 months), 13 (17.1%) received S + CT + BMT/SCT (bone marrow or stem cell transplant) (OS = 55.5 months), and 16 (8.70%) received S + CT + RT + BMT/SCT (OS = 68.4 months). Bivariate analysis of dichotomized age (HR = 0.550, 95% CI [0.357, 0.847], p = 0.0067) demonstrated significantly increased patient survival if diagnosed at or above 1 year old. On multivariate analysis, administration of S + CT + RT, S + CT + BMT/SCT, or S + CT + RT + BMT/SCT combination therapy predicted significantly (p < 0.05) increased OS compared to surgery alone.

CONCLUSION

AT/RTs are CNS tumors where those diagnosed under 1 year old have a significantly worse prognosis. Our study demonstrates that while traditional CT, RT, and BMT/SCT combination regimens prolong life, overall survival in this population is still low.

Evaluation of targeting autophagy for the treatment of malignant rhabdoid tumours

Malignant rhabdoid tumour (MRT) is a rare and aggressive paediatric tumour that typically arises in the kidneys or central nervous system (CNS). The malignancy often affects patients under the age of three and is associated with an extremely poor survival rate, with most deaths occurring within the first year of presentation. Thus, there is an unmet and urgent medical need for novel therapeutic strategies for this malignancy. One of the major issues when treating MRT patients is the emergence of chemoresistance. Autophagy has become an area of focus in the study of chemoresistance due to its reported dual role as both a pro-survival and pro-death mechanism. The role of autophagy in the chemotherapeutic response of MRT remains largely unknown. A greater understanding of the role of autophagy may lead to the development of therapeutic strategies to enhance chemotherapeutic effect and improve the clinical outcome of MRT patients. This study evaluated the cellular response to cisplatin, a representative chemotherapeutic agent used in the treatment of MRT, and the role of autophagy in mediating cisplatin resistance. Our results demonstrated that cisplatin induced apoptosis and autophagy concomitantly in a panel of MRT cell lines. Furthermore, inhibition of caspase-induced apoptosis with Z-VAD-FMK also inhibited autophagy levels demonstrating a complex interplay between these two pathways. In addition, blocking autophagy at the early stages of the autophagic process using the pharmacological inhibitor SAR405 or through the genetic knockdown of critical autophagic protein ATG5 by siRNA did not sensitise cells to cisplatin-induced apoptosis. Collectively, these results suggest that induction of autophagy does not appear to elicit a pro-survival effect in the chemotherapeutic response of MRT cells.

Targeting inhibitor of apoptosis proteins (IAPs) with IAP inhibitors sensitises malignant rhabdoid tumour cells to cisplatin

Malignant rhabdoid tumour (MRT) is a rare, aggressive paediatric malignancy most commonly diagnosed in those below the age of three. MRTs can arise in soft tissue but are more often associated with the central nervous system or kidney. Unfortunately, the prognosis upon diagnosis with MRT is poor. Given the resistance of MRT to current treatment protocols including cisplatin, and the vulnerability of this young patient population to aggressive therapies, there is a need for novel treatment options. Several members of the inhibitor of apoptosis protein (IAP) family including X‑linked inhibitor of apoptosis (XIAP), cellular inhibitor of apoptosis proteins 1 and 2 (cIAP1/cIAP2), livin and survivin have been implicated in chemotherapy resistance in various malignancies. We have previously demonstrated expression of these IAP family members in a panel of MRT cell lines. In the present study, sensitivity of this same panel of MRT cell lines to small-molecule mediated inhibition of the IAPs via the survivin inhibitor YM155 and the XIAP/cIAP1/cIAP2 inhibitor BV6 was demonstrated. Additionally, both BV6 and the XIAP inhibitor embelin synergistically enhanced cisplatin mediated apoptotic cell death in MRT cell lines, with enhanced caspase-3 cleavage. Importantly, we have demonstrated, for the first time, expression of XIAP, its target caspase-3 and its endogenous inhibitor SMAC in rhabdoid tumour patient tissue. In conclusion, this study provides pre-clinical evidence that IAP inhibition may be a new therapeutic option in MRT.

Epigenetic mechanisms in paediatric brain tumours: regulators lose control

Epigenetic mechanisms are essential to regulate gene expression during normal development. However, they are often disrupted in pathological conditions including tumours, where they contribute to their formation and maintenance through altered gene expression. In recent years, next generation genomic techniques has allowed a remarkable advancement of our knowledge of the genetic and molecular landscape of paediatric brain tumours and have highlighted epigenetic deregulation as a common hallmark in their pathogenesis. This review describes the main epigenetic dysregulations found in paediatric brain tumours, including at DNA methylation and histone modifications level, in the activity of chromatin-modifying enzymes and in the expression of non-coding RNAs. How these altered processes influence tumour biology and how they can be leveraged to dissect the molecular heterogeneity of these tumours and contribute to their classification is also addressed. Finally, the availability and value of preclinical models as well as the current clinical trials exploring targeting key epigenetic mediators in paediatric brain tumours are discussed.

Atypical Teratoid/Rhabdoid Tumor in Taiwan: A Nationwide, Population-Based Study

Simple Summary

Atypical teratoid/rhabdoid tumor (AT/RT) is a rare, highly malignant CNS neoplasm with poor prognosis. A retrospective population-based analysis of patients with the diagnosis of AT/RT, registered between 1999 and 2014 in Taiwan, showed that: (1) AT/RT had a higher prevalence in males, in children < 36 months of age, and at infratentorial sites; (2) older age (≥12 months), presence of the tumor in the supratentorial region, use of radiotherapy, chemotherapy, or both were associated with better prognosis compared to surgery or no treatment. These data represent a historical experience with AT/RT in Taiwan and may inform risk stratification and clinical trial design.

Abstract

Background: Atypical teratoid/rhabdoid tumor (AT/RT) is a rare, highly aggressive embryonal brain tumor most commonly presenting in young children. Methods: We performed a nationwide, population-based study of AT/RT (ICD-O-3 code: 9508/3) in Taiwan using the Taiwan Cancer Registry Database and the National Death Certificate Database. Results: A total of 47 cases (male/female = 29:18; median age at diagnosis, 23.3 months (IQR: 12.5–87.9)) were diagnosed with AT/RT between 1999 and 2014. AT/RT had higher prevalence in males (61.70%), in children < 36 months (55.32%), and at infratentorial or spinal locations (46.81%). Survival analyses demonstrated that patients ≥ 3 years of age (n = 21 (45%)) had a 5y-OS of 41% (p < 0.0001), treatment with radiotherapy only (n = 5 (11%)) led to a 5y-OS of 60%, treatment with chemotherapy with or without radiotherapy (n = 27 (62%)) was associated with a 5y-OS of 45% (p < 0.0001), and patients with a supratentorial tumor (n = 11 (23%)) had a 5y-OS of 51.95%. Predictors of better survival on univariate Cox proportional hazard modeling and confirmed with multivariate analysis included older age (≥1 year), supratentorial sites, and the administration of radiotherapy, chemotherapy, or both. Gender had no effect on survival. Conclusion: Older age, supratentorial site, and treatment with radiotherapy, chemotherapy, or both significantly improves the survival of patients with AT/RT.

Maternal embryonal leucine zipper kinase immunoreactivity in atypical teratoid/rhabdoid tumors: a study of 50 cases

Atypical teratoid/rhabdoid tumors (AT/RTs) are aggressive embryonal neoplasms of the central nervous system that correspond to WHO grade IV and have a dismal prognosis. The latest Central Brain Tumor Registry of the United States data shows that AT/RT constitutes 16.6% of all embryonal tumors in children. The molecular hallmark of this tumor is pathogenic SMARCB1 genetic alterations resulting in the loss of INI-1 immunopositivity, with fewer tumors harboring SMARCA4 (BRG1) variants. Maternal embryonal leucine zipper kinase (MELK) is a member of the Snf1/AMPK family of serine/threonine-protein kinases involved in various processes such as cell cycle regulation, self-renewal of stem cells, apoptosis, and splicing regulation. Recent studies have highlighted the involvement of MELK in AT/RT and its possible therapeutic role. The purpose of this study was to review the histological and immunohistochemical profile of AT/RT with special reference to MELK  staining. In this retrospective study conducted over 6 years, all diagnosed cases of AT/RT, defined by loss of INI-1 immunopositivity, were retrieved and studied. Demographic details of patients and microscopic findings were analyzed, with special attention to histological patterns and immunohistochemistry profile including MELK immunoreactivity. There were 50 cases of AT/RT diagnosed in the specified period. Of the cases operated at our institute during this period, embryonal tumors constituted 20.6% of all pediatric brain tumors with AT/RT representing 12.6% of this subset. The median age at presentation was 3.5 years (range: 8 months-22 years) and there were three adult cases. Males outnumbered females by a ratio of 1.94:1. Tumor location was distributed equally between the supratentorial and infratentorial compartments. Characteristic rhabdoid cells were identified in 70% of cases. Areas with epithelial, mesenchymal, and undifferentiated tumor cells were seen in 8%, 20%, and 52% of cases, respectively. Cells with vacuolated cytoplasm were noted in 28% of cases. Immunohistochemistry (IHC) showed a polyimmunophenotypic profile with immunopositivity for GFAP in 70%, Vimentin in 100%, SMA in 68%, and EMA in 88% of cases, indicating the remarkable heterogeneity of the tumor cells. MELK immunopositivity was noted in 83.33% of cases. Thus, atypical teratoid/rhabdoid tumors are rare neoplasms. In line with other studies, we show that these tumors occur predominantly in very young children and display marked variability on histology and IHC with loss of INI-1. MELK is presumed to be an important molecule involved in cell cycle regulation, proliferation, and other critical functions. High expression of MELK in AT/RT may suggest its plausible role in neoplastic transformation of embryonic and postnatal multipotent neural progenitors which in turn could explain the diverse morphological and immunohistochemical characteristics observed in these tumors.

Clinical evidence for a biological effect of epigenetically active decitabine in relapsed or progressive rhabdoid tumors

BACKGROUND

Refined therapy has helped to improve survival rates in rhabdoid tumors (RT). Prognosis for patients with chemoresistant, recurrent, or progressive RT remains dismal. Although decitabine, an epigenetically active agent, has mainly been evaluated in the management of hematologic malignancies in adults, safety in children has also been demonstrated repeatedly.

MATERIALS AND METHODS

A retrospective series of patients who received decitabine upon relapse or progression following therapy according to the EU-RHAB regimen is presented. Due to the retrospective nature of analyses, response was defined as measurable regression of at least one lesion on imaging. 850k methylation profiling was done whenever tumor tissue was available.

RESULTS

A total of 22 patients with RT of any anatomical localization were included. Most patients (19/22) presented with metastases. All received low-dose decitabine with or preceding conventional chemotherapy. Patients received a median of two (1-6) courses of decitabine; 27.3% (6/22) demonstrated a radiological response. Molecular analyses revealed increased methylation levels in tumors from responders. No excessive toxicity was observed. Clinical benefits for responders included eligibility for early phase trials or local therapy. Responders showed prolonged time to progression and overall survival. Due to small sample size, statistical correction for survivorship bias demonstrated no significant effect on survival for responders.

CONCLUSIONS

Patients with RT demonstrate promising signs of antitumor activity after multiagent relapse therapy including decitabine. Analyses of methylation data suggest a specific effect on an epigenetic level. We propose to consider decitabine and other epigenetic drugs as candidates for further clinical investigations in RT.

Atypical Teratoid Rhabdoid Tumours Are Susceptible to Panobinostat-Mediated Differentiation Therapy

Simple Summary

Atypical teratoid rhabdoid tumour (ATRT) is an aggressive undifferentiated malignancy of the central nervous system in children. A defining feature of ATRT is the loss of the SMARCB1 gene that is essential for regulating gene expression required for normal developmental processes. We show that treatment of human ATRT cell models with the histone deacetylate inhibitor, panobinostat, inhibits tumour growth, reactivates the expression of developmental genes, and drives neuronal differentiation. These results demonstrate the therapeutic potential of panobinostat for the treatment of ATRT.

Abstract

Atypical teratoid rhabdoid tumour (ATRT) is a rare but highly aggressive undifferentiated solid tumour arising in the central nervous system and predominantly affecting infants and young children. ATRT is exclusively characterized by the inactivation of SMARCB1, a member of the SWI/SNF chromatin remodelling complex that is essential for the regulation of large sets of genes required for normal development and differentiation. Histone deacetylase inhibitors (HDACi) are a promising anticancer therapy and are able to mimic the normal acetylation functions of SMARCB1 in SMARCB1-deficient cells and drive multilineage differentiation in extracranial rhabdoid tumours. However, the potential efficacy of HDACi in ATRT is unknown. Here, we show that human ATRT cells are highly responsive to the HDACi panobinostat and that sustained treatment leads to growth arrest, increased cell senescence, decreased clonogenicity and induction of a neurogenesis gene-expression profile. Furthermore, in an orthotopic ATRT xenograft model, continuous panobinostat treatment inhibits tumour growth, increases survival and drives neuronal differentiation as shown by the expression of the neuronal marker, TUJ1. Collectively, this preclinical study supports the therapeutic potential of panobinostat-mediated differentiation therapy for ATRT.

Targeting of cyclin-dependent kinases in atypical teratoid rhabdoid tumors with multikinase inhibitor TG02

OBJECTIVE

Atypical teratoid rhabdoid tumors (ATRTs) are aggressive pediatric brain tumors with no current standard of care and an estimated median patient survival of 12 to 18 months. Previous genetic analyses have implicated cyclin D1 and enhancer of zeste homolog 2 (EZH2), a histone methyltransferase that is implicated in many cancers, as key drivers of tumorigenicity in ATRTs. Since the effects of EZH2 and cyclin D1 are facilitated by a host of cyclin-dependent kinases (CDKs), the authors sought to investigate the potential therapeutic effects of targeting CDKs in ATRTs with the multi-CDK inhibitor, TG02.

METHODS

Human ATRT cell lines BT12, BT37, CHLA05, and CHLA06 were selected for investigation. The effects of TG02 on cell viability, proliferation, clonogenicity, and apoptosis were assessed via Cell Counting Kit-8 assays, cell counting, clonogenic assays, and flow cytometry, respectively. Similar methods were used to determine the effects of TG02 combined with radiation therapy (RT) or cisplatin. Synergism indices for TG02-cisplatin combination therapy were calculated using CompuSyn software.

RESULTS

TG02 was observed to significantly impair ATRT cell growth in vitro by limiting cell proliferation and clonogenicity, and by inducing apoptosis. TG02 inhibited ATRT cell proliferation and decreased cell viability in a dose-dependent manner with nanomolar half maximal effective concentration (EC50) values (BT12, 207.0 nM; BT37, 127.8 nM; CHLA05, 29.7 nM; CHLA06, 18.7 nM). TG02 (150 nM) dramatically increased the proportion of apoptotic ATRT cells 72 hours posttreatment (TG02 8.50% vs control 1.52% apoptotic cells in BT12, p < 0.0001; TG02 70.07% vs control 15.36%, p < 0.0001). Combination therapy studies revealed that TG02 acted as a potent radiosensitizer in ATRT cells (BT12 surviving fraction, RT 51.2% vs RT + TG02 21.7%). Finally, CompuSyn analysis demonstrated that TG02 acted synergistically with cisplatin against ATRT cells at virtually all therapeutic doses. These findings were consistent in cell lines that cover all three molecular subgroups of ATRTs.

CONCLUSIONS

The results of this investigation have established that TG02 is an effective therapeutic against ATRTs in vitro. Given the lack of standard therapy for ATRTs, these findings help fill an unmet need and support further study of TG02 as a potential therapeutic option for patients with this deadly disease.

Age and DNA methylation subgroup as potential independent risk factors for treatment stratification in children with atypical teratoid/rhabdoid tumors

BACKGROUND

Controversy exists as to what may be defined as standard of care (including markers for stratification) for patients with atypical teratoid/rhabdoid tumors (ATRTs). The European Rhabdoid Registry (EU-RHAB) recruits uniformly treated patients and offers standardized genetic and DNA methylation analyses.

METHODS

Clinical, genetic, and treatment data of 143 patients from 13 European countries were analyzed (2009-2017). Therapy consisted of surgery, anthracycline-based induction, and either radiotherapy or high dose chemotherapy following a consensus among European experts. Fluorescence in situ hybridization, multiplex ligation-dependent probe amplification, and sequencing were employed for assessment of somatic and germline mutations in SWItch/sucrose nonfermentable related, matrix associated, actin dependent regulator of chromatin, subfamily B (SMARCB1). Molecular subgroups (ATRT-SHH, ATRT-TYR, and ATRT-MYC) were determined using DNA methylation arrays, resulting in profiles of 84 tumors.

RESULTS

Median age at diagnosis of 67 girls and 76 boys was 29.5 months. Five-year overall survival (OS) and event-free survival (EFS) were 34.7 ± 4.5% and 30.5 ± 4.2%, respectively. Tumors displayed allelic partial/whole gene deletions (66%; 122/186 alleles) or single nucleotide variants (34%; 64/186 alleles) of SMARCB1. Germline mutations were detected in 26% of ATRTs (30/117). The patient cohort consisted of 47% ATRT-SHH (39/84), 33% ATRT-TYR (28/84), and 20% ATRT-MYC (17/84). Age <1 year, non-TYR signature (ATRT-SHH or -MYC), metastatic or synchronous tumors, germline mutation, incomplete remission, and omission of radiotherapy were negative prognostic factors in univariate analyses (P < 0.05). An adjusted multivariate model identified age <1 year and a non-TYR signature as independent negative predictors of OS: high risk (<1 y + non-TYR; 5-y OS = 0%), intermediate risk (<1 y + ATRT-TYR or ≥1 y + non-TYR; 5-y OS = 32.5 ± 8.7%), and standard risk (≥1 y + ATRT-TYR, 5-y OS = 71.5 ± 12.2%).

CONCLUSIONS

Age and molecular subgroup status are independent risk factors for survival in children with ATRT. Our model warrants validation within future clinical trials.

Advancing biology-based therapeutic approaches for atypical teratoid rhabdoid tumors

Atypical teratoid rhabdoid tumor (ATRT) is a rare, highly malignant central nervous system cancer arising in infants and younger children, historically considered to be homogeneous, monogenic, and incurable. Recent use of intensified therapies has modestly improved survival for ATRT; however, a majority of patients will still succumb to their disease. While ATRTs almost universally exhibit loss of SMARCB1 (BAF47/INI1/SNF5), recent whole genome, transcriptome, and epigenomic analyses of large cohorts reveal previously underappreciated molecular heterogeneity. These discoveries provide novel insights into how SMARCB1 loss drives oncogenesis and confer specific therapeutic vulnerabilities, raising exciting prospects for molecularly stratified treatment for patients with ATRT.

Age of diagnosis clinically differentiates atypical teratoid/rhabdoid tumors diagnosed below age of 3 years: a database study

BACKGROUND

Atypical teratoid/rhabdoid tumor (ATRT) is a rare and largely pediatric diagnosis, with poor survival. Diagnosis below the age of 3 years is characteristically seen as a poor prognostic sign. However, elucidating if clinical differences exist within this niche age group has never been attempted before. Correspondingly, we sought to characterize clinical profile of ATRT diagnoses before the age of 3 years based on separate ages of diagnosis.

METHODS

All pediatric ATRT patients aged < 3 years in the US National Cancer Database (NCDB) between 2005 and 2016 were retrospectively reviewed. Age groups were divided based on diagnoses at ages 0-1 years in group 1, 1-2 years in group 2, and 2-3 years in group 3. Data were summarized, and overall survival (OS) was modeled using Kaplan-Meier and Cox regression analyses.

RESULTS

A total of 354 ATRT diagnoses were made before the age of 3 years, with surgery used in 316 (89%) cases, chemotherapy in 242 (68%) cases, and radiation therapy in 118 (33%) cases. In terms of diagnosis age, there were 153 (43%) in group 1, 137 (39%) in group 2, and 64 (18%) in group 3. With respect to OS, median value was 9.9 months in group 1, 28.4 months in group 2, and 15.9 months in group 3. Upon multivariate analysis, receiving radiation therapy was the only parameter shared amongst all three groups as independently prognostic of longer OS (HR 0.53, P = 0.01 in group 1; HR 0.34, P < 0.01 in group 2; HR 0.31, P < 0.01 in group 3). In group 1, surgery (HR 0.47, P < 0.01) and chemotherapy (HR 0.44, P < 0.01) were also independently prognostic of longer OS. In group 3, multiple socioeconomic parameters were identified to independently predict longer OS. There were no additional predictive parameters identified in group 2.

CONCLUSION

Although ATRT diagnosed before the age of 3 is typically viewed a poor prognostic age category, our findings demonstrate that the clinical profile of this pediatric niche is highly heterogeneous based on age of diagnosis. Survival of only those diagnosed between 0 and 1 years is independently prognosticated by all three treatment modalities; patients diagnosed between 1 and 2 years trend towards longest survival, and socioeconomic parameters are most influential in those diagnosed between 2 and 3 years.

Relevance of Molecular Groups in Children with Newly Diagnosed Atypical Teratoid Rhabdoid Tumor: Results from Prospective St. Jude Multi-institutional Trials

PURPOSE

Report relevance of molecular groups to clinicopathologic features, germline SMARCB1/SMARCA4 alterations (GLA), and survival of children with atypical teratoid rhabdoid tumor (ATRT) treated in two multi-institutional clinical trials.

MATERIALS AND METHODS

Seventy-four participants with newly diagnosed ATRT were treated in two trials: infants (SJYC07: age < 3 years; n = 52) and children (SJMB03: age 3-21 years; n = 22), using surgery, conventional chemotherapy (infants), or dose-dense chemotherapy with autologous stem cell rescue (children), and age- and risk-adapted radiotherapy [focal (infants) and craniospinal (CSI; children)]. Molecular groups ATRT-MYC (MYC), ATRT-SHH (SHH), and ATRT-TYR (TYR) were determined from tumor DNA methylation profiles.

RESULTS

Twenty-four participants (32%) were alive at time of analysis at a median follow-up of 8.4 years (range, 3.1-14.1 years). Methylation profiling classified 64 ATRTs as TYR (n = 21), SHH (n = 30), and MYC (n = 13), SHH group being associated with metastatic disease. Among infants, TYR group had the best overall survival (OS; P = 0.02). However, outcomes did not differ by molecular groups among infants with nonmetastatic (M0) disease. Children with M0 disease and <1.5 cm² residual tumor had a 5-year progression-free survival (PFS) of 72.7 ± 12.7% and OS of 81.8 ± 11%. Infants with M0 disease had a 5-year PFS of 39.1 ± 11.5% and OS of 51.8 ± 12%. Those with metastases fared poorly [5-year OS 25 ± 12.5% (children) and 0% (infants)]. SMARCB1 GLAs were not associated with PFS.

CONCLUSIONS

Among infants, those with ATRT-TYR had the best OS. ATRT-SHH was associated with metastases and consequently with inferior outcomes. Children with nonmetastatic ATRT benefit from postoperative CSI and adjuvant chemotherapy.

Embryonal tumors of the central nervous system

PURPOSE OF REVIEW

This review aims to give an update on histopathological, molecular and clinical features of central nervous system (CNS) 'embryonal' tumors.

RECENT FINDINGS

The taxonomy of previously called 'CNS primitive neuroectodermal tumor' (CNS PNET) has been deeply modified since the discovery of specific molecular profiles for each various sub-entity of these rare, mainly pediatric, tumors. The term 'embryonal tumors' now refers to medulloblastomas, atypical teratoid rhabdoid tumors (AT/RT) and other rare entities, defined by their specific histopathological features together with expression-based or methylation-based profiling; specific gene mutations or fusions characterize some tumor types. In addition, the compilation of large series of molecular data has allowed to dissecting several of these tumor types in molecular subgroups, increasing the number of tumor entities, and leading to an amazingly complex nosology of rare-to-extremely rare malignancies. This rarity precludes from having strong evidence-based therapeutic recommendations, although international efforts are conducted to define the best treatment strategies.

SUMMARY

Embryonal tumors now correspond to molecularly well defined entities, which deserve further international collaborations to specify their biology and the appropriate burden of treatment, in order to minimize the long-term side-effects of treatment of these overall rare and severe diseases of childhood.

Neonatal Central Nervous System Tumors

Central nervous system (CNS) tumors, including brain and spinal cord tumors, are the most common solid tumors of childhood. Within the neonatal population, however, CNS tumors are relatively rare. These often carry a dismal prognosis in part due to the limited therapeutic options available for newborns and the unique biology of these tumors compared with those seen in older infants and children. This article reviews neonatal CNS tumors, specifically their clinical presentation, imaging findings, treatment, prognosis, and associated genetic syndromes. The unique psychosocial and emotional challenges facing clinicians and families are discussed as well.

Understanding the trajectory of research efforts in atypical teratoid rhabdoid tumors: a bibliometric analysis of the 50 most impactful studies to date

PURPOSE

Atypical teratoid/rhabdoid tumor (ATRT) is a highly malignant embryonal tumor of the central nervous system (CNS) that occurs predominantly in children. More is being discovered about this disease to improve understanding and outcomes. The aim of this analysis was to evaluate citation and other bibliometric characteristics of the 50 most cited articles in the contemporary literature in order to better model the trajectory of our current efforts.

METHODS

Elsevier's Scopus database was searched for the 50 most cited articles about ATRT. To look for trends, earliest 25 articles were separated from the latest 25 articles and then were compared. Various bibliometric parameters were summarized and compared using Pearson's chi-square and Mann-Whitney U tests.

RESULTS

The 50 most cited articles were published between 1990 and 2016, from 5 unique countries in 29 unique journals, with genetic and retrospective observational cohort studies the most common design (n = 11 each). Overall median values were as follows: citation count, 145.4 citations (range, 67-626); citation rate per year, 11.7 (range, 3.5-51.4); number of authors 12 (range, 1-95); with 32 (64%) originating from the USA. Compared with older articles, newer articles had statistically lower citation counts (101.8 vs 189.0; P < 0.01), higher number of authors (17.3 vs 6.6; P < 0.01), and were less likely published from the USA (40% vs 88%; P < 0.01) CONCLUSIONS: The 50 most cited articles about ATRT were characterized in this analysis. There was a distinct focus in these studies on the genetic composition and consequences of these tumors. Trends over time suggest greater impact will be had in highly collaborative efforts worldwide. Moving forward, it will be of great interest to see how the findings of these basic science finding will translate into future clinical studies.

[Influence of resection quality on postoperative outcomes in children with atypical teratoid-rhabdoid tumor of the central nervous system]

The purpose of this study was to assess the influence of resection quality on overall survival and disease-free survival in children with atypical teratoid-rhabdoid tumors (ATRT). The study included children younger than 18 years old for the period from 2008 to 2019. There were 134 interventions in 105 patients with ATRT including 11 redo resections («second-look» surgery) and 18 procedures for tumor recurrence. Age of patients ranged from 2 to 168 months (median 21 months). Patients with supratentorial tumors prevailed (50.5%), infratentorial neoplasms were diagnosed in 45.7% of patients, spinal cord lesion - 3.8% of cases. At the first stage, all patients underwent surgical treatment. Total resection was achieved in 34 (32.4%) patients, subtotal - 37 (35.2%) patients, partial resection - 30 (28.6%) patients. Biopsy was performed in 4 (3.8%) patients. Quality of resection and age at surgery significantly influenced overall and disease-free survival. Extended resection of tumor followed by adjuvant chemo- and radiotherapy are required to improve survival although ATRTs are high-grade neoplasms with poor prognosis.

Factors Affecting the Outcomes of Patients with Malignant Rhabdoid Tumors: A Population-Based Study

Objective: Malignant rhabdoid tumor (MRT) is a rare but aggressive malignancy. It has been a long time since data on this tumor have been updated. Methods: We retrospectively reviewed patients from the SEER database who were pathologically diagnosed with MRT and analyzed incidence rates, clinical features and survival using Stata 12.0. Results: In total, 544 patients were included in the epidemiological analysis. There were two peak periods of MRT incidence: patients younger than 4 years and those older than 70 years. Further survival analysis showed that the survival of children (especially younger than 1 year) was markedly worse than that of adults (P<0.01), and different primary sites were associated with different age groups and survival outcomes. The central nervous system (CNS) was the most common primary site (50.00%), followed by the kidney (15.66%). Patients with MRTs that originated from the digestive system experienced worse survival outcomes than those with MRTs originating from other locations. Primary site surgery conferred survival benefits to patients with renal and digestive system MRTs (HR = 0.06, CI: 0.02-0.23, P<0.01; HR=0.10, CI: 0.02-0.48, P<0.01), whereas radiotherapy conferred benefits to patients with CNS, bone and soft tissue MRTs (HR=0.22, CI: 0.15-0.34, P<0.01; HR=0.44, CI: 0.21-0.90 P=0.03). Conclusions: Our results indicate that age and the primary site of MRT are critical clinical factors that affect patient survival and treatment choices. Primary site tumor resection should be considered for renal and digestive system MRTs, and systematic therapy, including surgery and radiotherapy, should be recommended for the treatment of CNS, bone and soft tissue MRTs.

Successful Multimodality Management of Atypical Teratoid/Rhabdoid Tumour of the Lower Dorsal Spine with Spinal Drop Metastasis: Illustrated Review

INTRODUCTION

Spinal atypical teratoid/rhabdoid tumour (AT/RT) is exquisitely rare and constitutes 2% of all AT/RTs.

CASE PRESENTATION

A 6-year-old boy presented with low backache for the last 5 months. MRI of the spine showed a 1.5 × 1.5 × 4.7 cm intradural extramedullary mass extending from D10 to D12, causing compression of the conus medullaris. With a preoperative diagnosis of ependymoma, a gross total resection (GTR) of tumour was performed. Post-operative histopathology showed AT/RT. The tumour cells were immunopositive for cytokeratin, epithelial membrane antigen, smooth muscle actin, and p53 and immunonegative for MIC2, desmin, glial fibrillary acidic protein, and INI1. Post-operative neuraxis MRI revealed post-operative changes (D10-D12) with a 9 mm enhancing lesion at L5-S1 junction suggesting drop metastasis. There was no lesion in brain. Cerebrospinal fluid cytology did not show any malignant cell. The metastatic work-up was normal. He received 3 cycles of chemotherapy with ICE regimen (ifosfamide, carboplatin, and etoposide). Subsequently, he received craniospinal irradiation (CSI)-36 Gy/20 fractions/4 weeks followed by focal boost to primary tumour bed and spinal drop metastasis-14.4 Gy/8 fractions/1.5 weeks. Thereafter, he received 3 more cycles of ICE regimen. End-of-treatment MRI spine showed post-op changes (D10-D12) and 38.9% reduction of the L5-S1 lesion suggesting partial response. Six monthly spinal MRI showed serial reduction of the metastatic lesion leading to complete response (CR) 1 year after completion of treatment. On last follow-up (30 months from the initial diagnosis), he was neurologically intact and in CR.

CONCLUSION

Multimodality management comprising GTR of tumour, CSI followed by focal boost, and multiagent chemotherapy (ICE) can lead to successful outcome in patients with this rare and aggressive spinal tumour.

Canadian Pediatric Neuro-Oncology Standards of Practice

Primary CNS tumors are the leading cause of cancer-related death in pediatrics. It is essential to understand treatment trends to interpret national survival data. In Canada, children with CNS tumors are treated at one of 16 tertiary care centers. We surveyed pediatric neuro-oncologists to create a national standard of practice to be used in the absence of a clinical trial for seven of the most prevalent brain tumors in children. This allowed description of practice across the country, along with a consensus. This had a multitude of benefits, including understanding practice patterns, allowing for a basis to compare in future research and informing Health Canada of the current management of patients. This also allows all children in Canada to receive equivalent care, regardless of location.

Atypical Teratoid/Rhabdoid Tumor of the Central Nervous System in Children under the Age of 3 Years

Purpose

Atypical teratoid/rhabdoid tumor (ATRT) is a highly aggressive malignancy with peak incidence in children aged less than 3 years. Standard treatment for central nervous system ATRT in children under the age of 3 years have not been established yet. The objective of this study was to analyze characteristics and clinical outcomes of ATRT in children aged less than 3 years.

Materials and Methods

A search of medical records from seven centers was performed between January 2005 and December 2016.

Results

Forty-three patients were enrolled. With a median follow-up of 90 months, 27 patients (64.3%) showed at least one episode of disease progression (PD). The first date of PD was at 160 days after diagnosis. The 1- and 3-year progression-free survivals (PFS) were 51.2% and 28.5%, respectively. The 1- and 3-year overall survivals were 61.9% and 38.1%, respectively. The 3-year PFS was improved from 0% in pre-2011 to 47.4% in post-2011. Excluding one patient who did not receive any further therapy after surgery, 27 patients died due to PD (n=21), treatment-related toxicity (n=5), or unknown cause (n=1). In univariate analysis, factors associated with higher 3-year PFS were no metastases, diagnosis after 2011, early adjuvant radiotherapy, and high-dose chemotherapy (HDCT). In multivariate analysis, the use of HDCT and adjuvant radiotherapy remained significant prognostic factors for PFS (both p < 0.01).

Conclusion

Aggressive therapy including early adjuvant radiotherapy and HDCT could be considered to improve outcomes of ATRT in children under the age of 3 years.

Atypical teratoid rhabdoid tumor: molecular insights and translation to novel therapeutics

INTRODUCTION

Atypical teratoid rhabdoid tumor (ATRT) is a rare, often lethal brain tumor of childhood characterized by a complex epigenetic landscape amongst a simple genetic background. Recent molecular studies have defined key biologic events that contribute to tumorigenesis and molecular subtypes of ATRT.

METHODS

Seminal studies on ATRT are reviewed with an emphasis on molecular pathogenesis and its relevance to novel therapeutics.

RESULTS

In this review, we summarize the key clinicopathologic and molecular features of ATRT, completed and ongoing clinical trials and outline the translational potential of novel insights into the molecular pathogenesis of this tumor.

CONCLUSIONS

SMARCB1 loss is the key genetic event in ATRT pathogenesis that leads to widespread epigenetic dysregulation and loss of lineage-specific enhancers. Current work is defining subtype-specific treatments that target underlying molecular derangements that drive tumorigenesis.

CAR T Cell Therapy for Pediatric Brain Tumors

Chimeric Antigen Receptor (CAR) T cell therapy has recently begun to be used for solid tumors such as glioblastoma multiforme. Many children with pediatric malignant brain tumors develop extensive long-term morbidity of intensive multimodal curative treatment. Others with certain diagnoses and relapsed disease continue to have limited therapies and a dismal prognosis. Novel treatments such as CAR T cells could potentially improve outcomes and ameliorate the toxicity of current treatment. In this review, we discuss the potential of using CAR therapy for pediatric brain tumors. The emerging insights on the molecular subtypes and tumor microenvironment of these tumors provide avenues to devise strategies for CAR T cell therapy. Unique characteristics of these brain tumors, such as location and associated morbid treatment induced neuro-inflammation, are novel challenges not commonly encountered in adult brain tumors. Despite these considerations, CAR T cell therapy has the potential to be integrated into treatment schema for aggressive pediatric malignant brain tumors in the future.

Atypical Teratoid/Rhabdoid Tumor: Revisiting Histomorphology and Immunohistochemistry With Analysis of Cyclin D1 Overexpression and MYC Amplification

Objectives. Atypical teratoid/rhabdoid tumor (AT/RT) is a rare malignant pediatric brain tumor, characterized by inactivation of INI1/hSNF5 gene and loss of its protein. We studied the histomorphological and immunohistochemical spectrum of this tumor including cyclin D1 expression and MYC gene amplification. Methods. Cases with INI1 loss by immunohistochemistry (IHC; from 2005 to 2018) were retrieved, reviewed, and evaluated for cyclin D1 expression by additional IHC and fluorescence in situ hybridization for MYC genes. Results. A total of 66 cases were identified. Age ranged from 1 to 20 years (≤3 years, 44 cases; >3 years, 22). Male to female ratio was 1.7:1. Tumor locations were as follows: posterior fossa: 30; supratentorial: 31; spinal: 5. AT/RT in patient ≤3 years was frequently located in the posterior fossa, composed of primitive embryonal morphology (P = .02), rarely had ample rhabdoid cells (P = .05), and had a negative impact on overall survival (P = .04). The rhabdoid cells was a conspicuous component of posterior fossa tumors compared with the supratentorial ones (P = .06). The supratentorial tumors (P = .06), absence of rhabdoid cells (P = .06), and the presence of immunological divergent differentiation (P = .11) had a comparatively better outcome. Cyclin D1 overexpression (n = 46) was noted in 32 cases and was frequently seen in the posterior fossa tumors (P = .02). CMYC (n = 42) amplification was seen in 1 case and the NMYC (n = 42) amplification in none. Conclusion. AT/RT can occur in the noninfantile age group, at nonconventional sites and frequently overexpress cyclin D1. The MYC alterations are almost nonexistent in AT/RT.

Atypical Teratoid Rhabdoid Tumors (ATRT): King Faisal Specialist Hospital and Research Centre experience

Background

Atypical teratoid rhabdoid tumor is an uncommon aggressive central nervous system tumor. All retrospective series have shown a short mean overall survival rate. Considering the rarity of the disease, few prospective clinical trials addressed treatment recommendations for such aggressive tumors, and consequently no definitive treatment guidelines have been established. In this study, we are reviewing our experience in treating atypical teratoid rhabdoid tumor patients.

Methods

We reviewed the medical charts of 43 patients with atypical teratoid rhabdoid tumor who were treated in King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia, between 1996 and 2013. We evaluated the overall survival rate and the influence of different clinical features and treatment protocols on survival.

Results

The median overall survival time was 16.9 months (95% Confidence Interval, 5.2–32.9 months) with an estimated 2- and 5-year overall survival of 41.9% ± 9.6 and 27.9% ± 9.2, respectively. Patients receiving trimodal treatment (surgery, chemotherapy, and radiotherapy) exhibited significantly better median overall survival time compared to their counterparts (P value < .001).

Conclusions

Atypical teratoid rhabdoid tumor is rare and aggressive central nervous system tumor. Despite the limitations of the study, our results support several of clinical practice development. Utilization of postoperative radiotherapy and the adoption of trimodal therapy are associated with significant improvement of median survival. Prompt management with aggressive trimodal therapy should be the standard for future treatment protocols.

Meta-Analysis of Treatment Modalities in Metastatic Atypical Teratoid/Rhabdoid Tumors in Children

BACKGROUND

Metastatic atypical teratoid/rhabdoid tumors (AT/RTs) are aggressive central nervous system tumors that present during infancy and are associated with dismal outcomes. Patients receive multimodal treatment including surgical resection, systemic chemotherapy, and one or more of intrathecal chemotherapy (IT), marrow-ablative chemotherapy with autologous hematopoietic cell rescue (AuHCR) and radiation therapy (XRT). While data regarding treatment modalities for AT/RT patients exist, no comprehensive data have been published regarding the metastatic patients.

METHODS

We performed a meta-analysis of 1578 articles published through September 2018, including 44 studies with a total of 123 subjects. In addition, seven patients were included through chart review of patients treated at Nationwide Children's Hospital.

RESULTS

Analysis of 130 patients revealed a 3-year overall survival (OS) of 25%. Age at diagnosis had a significant effect on survival (P = 0.0355); 3-year OS for infants less than 18 months was 21%, 18 to 36 months was 26%, and greater than 36 months was 36%. Location of the primary tumor, metastatic stage, and extent of surgical resection did not have a significant impact on OS. On univariate analysis, XRT (P < 0.0001), IT (P = 0.01), and AuHCR (P < 0.0001) were found to significantly improve survival. The most substantial effect was noted in patients who received AuHCR (3-year OS of 60% vs 9% in those who did not). On multivariable analysis, XRT (P = 0.0006), IT (P = 0.0124), and AuHCR (P < 0.0001) were independently associated with reduced risk of death.

CONCLUSIONS

Although more research is warranted to make generalizable conclusions, these results suggest that treatment regimens for patients with metastatic AT/RTs should include AuHCR, XRT, and IT.

Advances in the molecular classification of pediatric brain tumors: a guide to the galaxy

Central nervous system (CNS) tumors are the most common solid tumor in pediatrics, accounting for approximately 25% of all childhood cancers, and the second most common pediatric malignancy after leukemia. CNS tumors can be associated with significant morbidity, even those classified as low grade. Mortality from CNS tumors is disproportionately high compared to other childhood malignancies, although surgery, radiation, and chemotherapy have improved outcomes in these patients over the last few decades. Current therapeutic strategies lead to a high risk of side effects, especially in young children. Pediatric brain tumor survivors have unique sequelae compared to age-matched patients who survived other malignancies. They are at greater risk of significant impairment in cognitive, neurological, endocrine, social, and emotional domains, depending on the location and type of the CNS tumor. Next-generation genomics have shed light on the broad molecular heterogeneity of pediatric brain tumors and have identified important genes and signaling pathways that serve to drive tumor proliferation. This insight has impacted the research field by providing potential therapeutic targets for these diseases. In this review, we highlight recent progress in understanding the molecular basis of common pediatric brain tumors, specifically low-grade glioma, high-grade glioma, ependymoma, embryonal tumors, and atypical teratoid/rhabdoid tumor (ATRT). © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.