Atypical Teratoid Rhabdoid Tumor Research Articles

Brachyury Expression in Atypical Teratoid/Rhabdoid Tumor.

Atypical teratoid/rhabdoid tumor (AT/RT) is a rare, highly aggressive central nervous system tumor of childhood with variable morphologic features, which is characterized by alterations in SWI/SNF complex, such as SMARCB1/INI1 or SMARCA4/BRG1 loss. Poorly differentiated chordoma is the differential diagnosis, particularly in the infratentorial region of older children and the use of brachyury in such conditions is under debate. We investigated the brachyury expression in 44 samples of AT/RT from 40 patients. All AT/RTs except 2 infratentorial tumors were negative for brachyury (2 clones: A-4 and EPR18113). Both brachyury-positive tumors (one diffuse and one patchy expression) involved the clivus of children younger than 2 years old. The DNA methylation profile of one of these tumors showed epigenetic similarity to reference examples of chordoma in 2 public unsupervised and one supervised analysis systems. The second tumor exhibited a classical epigenetic microarray pattern found in samples with degraded DNA. We revised 2 initial AT/RT diagnoses as poorly differentiated chordoma based on the morphology, brachyury expression, topographical features, and methylation profile. Differentiating poorly differentiated chordoma from AT/RT could be challenging; brachyury expression can be useful in diagnosing poorly differentiated chordoma over AT/RT in suitable clinical and radiological settings.

Differential Replication and Oncolytic Effects of Zika Virus in Aggressive CNS Tumor Cells: Insights from Organoid and Tumoroid Models

Central nervous system (CNS) cancers are responsible for high rates of morbidity and mortality worldwide. Malignant CNS tumors such as adult Glioblastoma (GBM) and pediatric embryonal CNS tumors such as medulloblastoma (MED) and atypical teratoid rhabdoid tumors (ATRT) present relevant therapeutic challenges due to the lack of response to classic treatment regimens with radio and chemotherapy. Recent findings on the Zika virus’ (ZIKV) ability to infect and kill CNS neoplastic cells draw attention to the virus’ oncolytic potential. Studies demonstrating the safety of using ZIKV for treating malignant CNS tumors, enabling the translation of this approach to clinical trials, are scarce in the literature. Here we developed a co-culture model of mature human cerebral organoids assembled with GBM, MED or ATRT tumor cells and used these assembloids to test ZIKV oncolytic effect, replication potential and preferential targeting between normal and cancer cells. Our hybrid co-culture models allowed the tracking of tumor cell growth and invasion in cerebral organoids. ZIKV replication and ensuing accumulation in the culture medium was higher in organoids co-cultured with tumor cells than in isolated control organoids without tumor cells. ZIKV infection led to a significant reduction in tumor cell proportion in organoids with GBM and MED cells, but not with ATRT. Tumoroids (3D cultures of tumor cells alone) were efficiently infected by ZIKV. Interestingly, ZIKV rapidly replicated in GBM, MED, and ATRT tumoroids reaching significantly higher viral RNA accumulation levels than co-cultures. Moreover, ZIKV infection reduced viable cells number in MED and ATRT tumoroids but not in GBM tumoroids. Altogether, our findings indicate that ZIKV has greater replication rates in aggressive CNS tumor cells than in normal human cells comprising cerebral organoids. However, such higher ZIKV replication in tumor cells does not necessarily parallels oncolytic effects, suggesting cellular intrinsic and extrinsic factors mediating tumor cell death by ZIKV.

PATH-22. SINGLE-CELL RNA (SCRNA) SEQUENCING OF PAIRED PRIMARY AND RECURRENT ATYPICAL TERATOID/RHABDOID TUMORS (AT/RT) REVEALED MOLECULAR DIFFERENCES AND THERAPY-RESISTANT PRIMARY TUMOR CELLS

Abstract Atypical teratoid/rhabdoid tumors (AT/RT) are the most common malignant brain tumors during infancy. They split into four molecular types. The major three (AT/RT-SHH, AT/RT-TYR, and AT/RT-MYC) all carry mutations in SMARCB1, the fourth smaller type is characterized by SMARCA4 mutations (AT/RT-SMARCA4). AT/RT are associated with a dismal outcome, and 50% of the patients suffer a progress or recurrence of the tumor. Molecular mechanisms of disease recurrence are currently unclear. Here, we identified molecular characteristics of AT/RT primaries and recurrences, which could help to improve the therapy for relapsed patients. Previously, we investigated tumor tissue from 26 patients revealing signatures of recurrences in comparison to matched primary tumor samples using histology, DNA methylation analysis, and bulk RNA sequencing. To further identify mechanisms regarding tumor progression and recurrence, we performed single-cell RNA (scRNA) sequencing for five of these primary-recurrence pairs so far using formalin-fixed paraffin-embedded (FFPE) tissue. Using Uniform Manifold Approximation and Projection (UMAP) for dimensionality reduction, we observed a distinct separation in the gene expression profiles of primary and recurrent tumor cells. In addition, we aimed to identify primary tumor cells which potentially persisted after therapy and developed to recurrences. Therefore, we identified primary tumor cells showing highest similarity to recurrent tumor cells using CIBERSORT and trajectory analysis. Differentially expressed genes of these specific primary tumor cells were investigated. They are involved in cell migration, -adhesion, -proliferation, and -stability, among others. Overall, molecular characteristics that occur in the course of the disease were identified, which may help to define new therapeutic targets for AT/RT recurrences.

EPID-07. MAJOR CONGENITAL ANOMALIES AND RISK OF CHILDHOOD BRAIN TUMORS IN 9 STATES

Abstract Children with congenital anomalies have a higher risk of developing a childhood brain tumor (CBT), but it remains unclear if associations vary by cancer histology, which could inform our understanding of these associations. Thus, we characterized co-occurrences of major congenital anomalies with six CBTs. We leveraged a population-based registry linkage study of live births, congenital anomalies, and cancer from nine states. Dates of birth and last follow-up varied by state, ranging between January 1, 1990 to December 31, 2018, for a total of 22,599,099 live births. CBT classification was based on the International Classification of Childhood Cancer for children diagnosed up to age 18 years. Major congenital anomalies were classified based on the National Birth Defects Prevention Network Surveillance Guidelines. Children with any genetic anomalies were excluded. We used Cox regression to evaluate associations between major congenital anomalies and astrocytoma, medulloblastoma, ependymoma, atypical teratoid/rhabdoid tumor (ATRT), primitive neuroectodermal tumors (PNET), and mixed and unspecified gliomas (“mixed gliomas”), adjusting for sex, state, maternal education, maternal race/ethnicity, and maternal age. Sensitivity analyses were conducted stratifying by number of major anomalies (0, 1, 2+) and age at cancer diagnosis (<1, 1-4, 5-9, 10+ years). There were 5,685 diagnosed with any CBT. Having any major congenital anomaly was significantly associated with astrocytoma, ATRT, medulloblastoma, mixed glioma, and PNET (aHR range: 1.79-5.78) but not ependymoma. When stratified by number of major anomalies, effect estimates were similar. Due to small numbers when stratified by age at cancer diagnosis, unadjusted analyses were conducted. Associations were strongest in children diagnosed with astrocytoma, ATRT, medulloblastoma, mixed glioma, or PNET before age 1 (HR range: 3.03-5.47) compared to other age groups (HR range: 1.25-3.07). Children with any major congenital anomaly have an increased risk of developing astrocytoma, ATRT, medulloblastoma, mixed glioma, or PNET, particularly by 1 year.

CTNI-36. THE FEASIBILITY OF USING BORTEZOMIB WITH CHEMOTHERAPY IN ATYPICAL TERATOID/RHABDOID TUMORS

Abstract Atypical teratoid/rhabdoid tumors (ATRTs) are highly aggressive pediatric brain tumors with sensitivity to proteasome inhibitors in preclinical models. We evaluated the feasibility of combining the proteasome inhibitor bortezomib with chemotherapy. Patients aged 0-20 years with newly diagnosed ATRT were enrolled from January 2022 through December 2023. A modified Medical University of Vienna (MUV)-ATRT regimen was used. They were treated with bortezomib of 1.3 mg/m2/dose given intravenously or subcutaneously twice a week for 2 weeks concurrently with 6 cycles of chemotherapy and 2 additional cycles after high-dose chemotherapy. Radiation therapy was given prior to or at the end of chemotherapy. A total of 36 chemotherapy cycles with bortezomib in 6 patients were evaluated. The primary endpoint was grade 3 or higher non-hematologic toxicities. Numbers of cycles with grade 3+ toxicities included: AST/ALT elevation (1), hypokalemia (2), peripheral neuropathy (1), subdural hemorrhage (2), vomiting (2), oral mucositis (3), lung infection (2), urinary tract infection (8), sepsis (3), febrile neutropenia (20). No grade 3+ toxicities were considered bortezomib-related. Three patients completed 8 cycles of bortezomib treatment; 2 patients discontinued the study due to progressive disease after 2 and 4 cycles respectively; 1 patient completed 6 cycles of bortezomib and died of septic shock in complete remission after high-dose chemotherapy. Two patients had a surgical complete resection. Three patients were evaluable for response after bortezomib: 1 partial response and 2 stable disease. Two patients had progression-free survival for 16+ and 22+ months after diagnosis, respectively. Among the 3 patients with progressive disease, 2 had metastatic relapse and 1 had primary and metastatic relapse. There were 4 deaths due to metastatic PD (n=2), septic shock after high-dose chemotherapy (n=1), and septic shock after 2nd line treatment for PD (n=1). We conclude that adding bortezomib to standard and high-dose chemotherapy of ATRT was feasible with the occurrence of grade 3/4 toxicities no more than what was expected with chemotherapy alone. Metastatic relapse remains the major challenge of ATRT treatment.

EPID-33. EPITHELOID SARCOMA IN A LONG-TERM SURVIVOR OF AN ATYPICAL TERATOID / RHABDOID TUMOR WITH RHABDOID TUMOR PREDISPOSITION SYNDROME

Abstract INTRODUCTION Rhabdoid tumor predisposition syndrome (RTPS) predisposes to a high risk of developing Rhabdoid tumors in Brain, kidney; and is defined by a germline mutation in SMARCB1 (rarely SMARCA4) gene. The most frequent pediatric tumor associated with RTPS is atypical teratoid/rhabdoid tumor (ATRT), commonly diagnosed in children < 3 years of age. Epitheloid Sarcoma (ES) is a rare soft tissue sarcoma, arising in any age group and histologically defined by loss of SMARCB1 in tumor cells. METHODS We describe a long- term survivor of ATRT with RTPS presenting 12 years later with ES. Data was collected from medical chart review. RESULTS Our patient was diagnosed with ATRT and RTPS (SMARCB1) at 6 months of age and treated with chemotherapy as per ACNS0333 at diagnosis; by chemotherapy / focal radiation at first relapse and with alisertib on second relapse. At 10yrs of age she presented with multiple firm, skin-colored dermal nodules in both her hands (palms and fingers). She was diagnosed to have palmar warts and treated with topical cantharidin with a waxing and waning course. Subsequently the hand lesions were diagnosed as granuloma annulare and followed up with no therapy. At 12 years of age, lesion in tip of the right thumb increased in size and a punch biopsy was done which revealed ES with IHC showing loss of SMARCB1 in tumor cells. Staging CT of the chest showed multiple bilateral (b/l) small (<1cm) axillary lymph nodes with a negative PET scan. Bilateral axillary lymph node biopsies were negative for ES. She underwent excision of all the hand lesions with negative margins with no further therapy. CONCLUSION Based on our case and single case report in literature, we hypothesize that ES is likely a primary malignancy of RTPS and should be included in the spectrum of malignancies of RTPS.

Inhibiting EZH2 targets atypical teratoid rhabdoid tumor by triggering viral mimicry via both RNA and DNA sensing pathways

Inactivating mutations in SMARCB1 confer an oncogenic dependency on EZH2 in atypical teratoid rhabdoid tumors (ATRTs), but the underlying mechanism has not been fully elucidated. We found that the sensitivity of ATRTs to EZH2 inhibition (EZH2i) is associated with the viral mimicry response. Unlike other epigenetic therapies targeting transcriptional repressors, EZH2i-induced viral mimicry is not triggered by cryptic transcription of endogenous retroelements, but rather mediated by increased expression of genes enriched for intronic inverted-repeat Alu (IR-Alu) elements. Interestingly, interferon-stimulated genes (ISGs) are highly enriched for dsRNA-forming intronic IR-Alu elements, suggesting a feedforward loop whereby these activated ISGs may reinforce dsRNA formation and viral mimicry. EZH2i also upregulates the expression of full-length LINE-1s, leading to genomic instability and cGAS/STING signaling in a process dependent on reverse transcriptase activity. Co-depletion of dsRNA sensing and cytoplasmic DNA sensing completely rescues the viral mimicry response to EZH2i in SMARCB1-deficient tumors.

Pediatric Atypical Teratoid Rhabdoid Tumor of Central Nervous System: A Case Series with Review of Literature

Pediatric Atypical Teratoid Rhabdoid Tumor of Central Nervous System: A Case Series with Review of Literature

Diagnostic aspects of pediatric embryonal tumors of the central nervous system: what should know pediatrician

Background. Early identification of pediatric central nervous system (CNS) tumors is important in relation to disease prognosis, as well as long-term treatment outcomes, which determine subsequent quality of life. The predominance of embryonal tumors (ETs) in early childhood actualizes the problem of timely verification of the diagnosis. Factors contributing to the extension of diagnostic time in the presented patient’s cohort include the inability to adequately verbalize complaints in young children, a wide range of clinical presentations, including nonspecific ones, the relatively low incidence of ET in the population and the low level of oncological alertness among specialists. This determines the need for a more careful assessment of the clinical manifestations and disease-associated symptoms by doctors of all specialties and, especially, primary care specialists. Aim. Analysis of clinical symptoms at the disease’s onset in pediatric CNS ET in order to determine their associations with the tumor’s characteristics (site, hystologic type) and the patient’s features. Materials and methods. A retrospective analysis of data from 124 pediatric patients with CNS ET who received treatment from 2010 to 2023 in the departments of pediatric oncology of the Almazov National Medical Research Center and the St. Petersburg Scientific Research Center for Medical Sciences (o) named after. N. P. Napalkov. The analyzed parameters were the age of manifestation, initial symptoms, duration of the anamnesis and the period before verification of the diagnosis, localization and histological type of tumors. For statistical analysis, Fisher’s exact test, modified Pearson test, Kruskal-Wallis and Mann-Whitney tests, as well as (to assess the duration of anamnesis) the Cox model were used. Results. The most common type of CNS ET in the study group was medulloblastoma (MB; 66.1%). The average age of patients, in general, was 61 months, boys predominated (58%). The median age varied depending on the histological tumor type: the maximum was 72 months in patients with medulloblastoma and the minimum was 9 months in children with atypical teratoid rhabdoid tumor (ATRT). Both medians are significantly different from the total median (29 months) of all other tumors (p = 6.53 ∙ 10-4 and p = 0.029, respectively). The most frequent symptoms in patients with ET were nausea and vomiting (68%), headache (50%), and gait disturbances (25.6%). Increased head circumference/bulging fontanel (p = 0.0016) and torticollis (p = 0.0057) were the most common symptoms associated with younger age. Headache (p = 1.30 ∙ 10-9), nausea and vomiting (p = 0.019), diplopia (p = 0.0057), weight loss (p = 0.017) and dizziness (p = 0.013) were associated with older age. Headache was predominated symptom in medulloblastoma (p = 2.60 ∙ 10-4) compared to other ETs, and less common in ATRT (p = 1.51 ∙ 10-4), which may be due to the patient’s age. Fontanel bulging in medulloblastoma, unlike other ET, was not observed, which is also associated with age. Seizures were observed in all cases of CNS neuroblastoma - significantly more often (p = 0.034) than in other ETs. The most common tumor location was the posterior cranial fossa (PCF) (83.6%). PCF localization was associated with headache (p = 0.05, borderline significance) and nausea/vomiting (p = 0.040). Parietal localization was associated with seizures (p = 0.041). Four patients in the cohort had asymptomatic disease’s manifestations. The diagnosis was established by a routine screening examination. The absence of symptoms was associated with location outside the PCF (p = 0.011) and with younger age (p = 0.053, borderline significance). The diagnosis was established in a significantly shorter time if children had symptoms such as nausea and vomiting (p=0.0017), paresis and paralysis (p=0.0059). Conclusion. In patients with CNS ETs, statistically significant relationships are revealed between age, histological type, tumor site and certain symptoms. Nevertheless, the absence of strictly specific clinical manifestation determines the indications for a careful assessment of the pediatric somatic and neurological status and timely neuroimaging in children when even potential symptoms typical for CNS tumors are identified.

RECAPITULATING THE POST-SURGICAL BRAIN MICROENVIRONMENT OF ATYPICAL TERATOID RHABDOID TUMOURS TO IDENTIFY MEMBRANE PROTEINS FOR TARGETED THERAPY

Abstract AIMS Atypical Teratoid Rhabdoid Tumours (AT/RT) are rare aggressive tumours primarily arising in the hind brain of children under three, conferring median survival of <12 months. Surgery remains the only standard treatment; however tumours recur from post-surgical residual disease. Decellularised human brain cerebellum aim to recapitulate AT/RT post-surgical brain microenvironments which retain extracellular matrix (ECM) ligands, and where AT/RT plasma membrane proteins are hypothesised to represent viable molecular therapy targets. METHOD AT/RT, astrocyte and human brain cerebellum (decellularised and non-decellularised) membrane protein fractions were extracted and analysed using liquid chromatography-mass spectrometry. Proteomic analysis tools were integrated to identify differential expressed proteins and identify shared correlations. RESULTS Decellularised cerebellar ECM exhibited an enriched membrane proteome relative to total proteome, evidence of complete removal of intracellular components. Furthermore, decellularised and non-decellularised cerebellar tissue expressed comparable levels of membrane proteins and protein networks, indicative of ECM ligand retention. AT/RT and astrocyte KEGG Pathway analysis revealed specific oncology-based pathway expression in membrane protein compared to total protein, reinforcing membrane proteins as more visible therapeutic targets. Between the top 20 expressed proteins, ATP1A1 was the only membrane protein shared exclusively between all AT/RT cells and astrocytes, suggesting a critical functional role. Membrane proteins showing shared expression when normalised against each AT/RT cell line included ATP1A1, HSPD1, GNA13 and SLC3A2, indicating biological similarities between AT/RT molecular subtypes, which may offer candidate ubiquitous therapy targets. Membrane proteins expressed similarly in AT/RT-MYC molecular subtypes include ATP1A1, SLC7A5 and EEF1A1. STRING membrane pathway analysis also identified shared proteins between AT/RT and astrocyte cell populations. CONCLUSION AT/RT membrane protein pathways provide ideal therapeutic targets directly amenable for drug repurposing. Future work prioritises proteomic analysis utilising 3D AT/RT spheroids and cerebellum brain tissue to maximise accurately recapitulating the AT/RT post-surgical microenvironment. Cerebellum decellularisation still permits retention of essential proteins and ligands.

6791 Pituitary Apoplexy as Presentation of Atypical Teratoid/Rhabdoid Tumor

Abstract Disclosure: S.I. Babli: None. H. Alkubedan: None. N.M. Ali: None. R. Alqawahmed: None. M.M. Elhassan: None. Introduction: Pituitary apoplexy occurs in a pituitary adenoma; it migh occur in other less common types of tumors. The atypical teratoid/rhabdoid tumor (ATRT) is a very aggressive malignant tumor of the central nervous system and has a poor prognosis. It is rare to occur in adult and in the sellar region. Clinical Case: 32 years old male presented to ER with 4 days history of fever, headache and vomiting. He was conscious but confused. Vital signs Temperature 39 C, BP 120/80, HR 110 beats/min and Saturation of 95 %, Possibility of meningoencephalitis was raised, patient Brain CT showed Sellar and suprasellar mass with compression over the optic chiasma and invasion to the left cavernous sinus. Patient suddenly developed Generalize tonic-clonic convulsion and hypotension. He received IV midazolam, intubated and was started on noradrenaline and hydrocortisone, he was admitted to ICU as a case of meningoencephalitis and started on Ceftriaxone, Vancomycin and Acyclovir. Cerebrospinal fluid analysis showed RBC 175/cumm, WBC 20/cumm with 20% polymorph and 80% mononuclear cells, Protein 1.38 g/l (0.24-0.49) glucose 7.9 mmol/l with plasma glucose of 10 mmol/l. Repeated Brain CT showed Sellar and suprasellar mass with compression over the optic chiasma and invasion to the left cavernous sinus and with minimal heterogenicity and increased density suggestive of hemorrhagic components. Endocrine history revealed weight gain but no history to suggest acromegaly, Cushing’s syndrome or hypogonadism . Examinations: Patient was intubated and sedated BP 90/60 on Maximum inotropic support. Left oculomotor nerve palsy, Bilateral papilledema, he was having acanthosis nigricans with no signs of acromegaly, CS or hypogonadism. Laboratory finding: WBC17 with neutrophilia, Hgb 14.7 g/dl plt 360 Na 140 mmol/l, creatnin 180 mmol/, FT4 6.2 pmol/l, TSH 0.015, PROLACTINE 22, IGF1 29 ng/ml (41-246) Free testosterone index 2.13 (33-106), LH 0.5, FSH 0.3 .Patient had TTS and histopathology showed: SMARCB1 deficient malignant neoplasm, consistent with sellar atypical teratoid rhabdoid tumor. Post OP, patient had Ventilator associated pneumonia and recurrent attacks of seizures despite multiple antiepileptic medications. Patient was evaluated by medical and radiation oncologists but due to his general condition the treatment was postpone. One month after TSS, he developed intractable seizure new Brain CT showed interventricular haemorrhage with hydrocephalus and marked enlargement of hyperdense pituitary lesion which suggests haemorrhage. External ventricular drain was inserted but patient arrested and died. Conclusions: ATRT of the CNS usually affects young children. In the literature review performed in adults, only nine cases have occurred in the sellar or suprasellar region. Survival is variable in the different cases reported in the literature, with a mean of 26 months. Presentation: 6/2/2024

PDOC-03 CASE SERIES ON PEDIATRIC PATIENTS WITH LEPTOMENINGEAL METASTASES FROM VARIOUS PRIMARY BRAIN TUMORS: FROM CLINICAL PRESENTATIONS TO OUTCOMES

Abstract Leptomeningeal disease (LMD), also known as carcinomatous meningitis, is when cancer cells are found in the thin layers covering the brain and spinal cord, in the spaces between these layers, or in the fluid surrounding the brain and spinal cord. In children with brain tumors, LMD is rare, occurring in about 1% to 2% of cases. It’s most commonly seen in certain types of tumors like medulloblastoma and primary central nervous system lymphoma, but it can also occur in other types such as pineoblastoma, Atypical Teratoid Rhabdoid Tumor, and both low-grade and high-grade gliomas. Although pilocytic astrocytomas, a type of low-grade glioma, seldom spread, there have been a few reported cases of them spreading to the leptomeninges. The exact prevalence of LMD in pediatric brain tumors isn’t well-documented due to differences in how it’s screened for across different types of tumors and at different stages of the disease. Improved surgical methods and various treatments targeting specific areas or affecting the whole body have resulted in better survival rates for patients with LMD. Detecting LMD early is important for treatment options. It can be found either at the same time as the primary brain tumor, when the tumor comes back, or as LMD without an initial tumor. There’s concern that procedures to divert cerebrospinal fluid might spread cancer cells. MRI scans are important for diagnosing LMD, but it can still be challenging to diagnose based on these scans alone. Usually, confirmation is done by analyzing the fluid around the brain and spinal cord for cancer cells. Given that LMD is a complex and rare complication of pediatric brain tumors, more research is needed to improve diagnosis and treatment. In this article, we’ll discuss three cases of pediatric brain tumors with LMD, including how they were diagnosed, treated, and their clinical outcomes.

Decoding pediatric spinal tumors: a single-center retrospective case series on etiology, presentation, therapeutic strategies, and outcomes

IntroductionSpinal tumors (ST) often result in dire prognosis, carrying risks such as permanent paralysis, sensory loss, and sphincter dysfunction. Data on their incidence and etiology in pediatric populations are markedly scant. Our study investigates the etiology, clinical manifestation, treatment, and outcomes of pediatric ST.MethodsWe conducted a retrospective review of our institutional pediatric oncology and neurosurgery database, examining 14 patients under 18 years admitted with ST due to oncological diseases since 2005. We analyzed the clinical presentations, evaluations, molecular diagnostics and treatments for these patients.ResultsThe study spanned 15 years and included 14 pediatric patients, each diagnosed with distinct spinal tumor entity. The mean patient age was approximately 19.6 ± 10.1 months. Severe axial pain along the vertebral column was observed in 13 patients, while acute neurological deterioration manifested in 7 patients. As a first-line intervention, 13 patients underwent decompressive surgery through laminectomy and tumor resection, and only one patient received chemotherapy solely. Before surgery, seven patients were unable to walk; post-surgery, six of them regained their ability to ambulate. The diagnosis encompassed a range of neoplasms: two instances of Ewing sarcoma, 3 instances of teratoma, one case presenting an atypical teratoid Rhabdoid tumor, two instances each of low-grade astrocytoma and neuroblastoma, and single instances of ependymoma, meningioma, rhabdomyosarcoma, and embryonal tumors with multilayered rosettes (ETMRs). Three patients succumbed two years after initiating therapy.ConclusionDespite their rarity, intraspinal tumors in pediatric patients pose substantial therapeutic challenges. The intertwined complexities of the disease entity and the patient’s neurological status demand swift initiation of an individualized therapeutic strategy. This crucial step helps optimize outcomes for this patient cohort, who frequently grapple with debilitating health conditions. Inclusion of these patients within a registry is mandatory to optimize treatment outcomes due to their rarity in pediatric population.

Gemcitabine therapeutically disrupts essential SIRT1-mediated p53 repression in atypical teratoid/rhabdoid tumors

Atypical teratoid/rhabdoid tumors (ATRTs) are highly malignant embryonal tumors of the central nervous system with a dismal prognosis. Using a newly developed and validated patient-derived ATRT culture and xenograft model, alongside a panel of primary ATRT models, we found that ATRTs are selectively sensitive to the nucleoside analog gemcitabine. Gene expression and protein analyses indicate that gemcitabine treatment causes the degradation of sirtuin 1 (SIRT1), resulting in cell death through activation of nuclear factor κB (NF-κB) and p53. Furthermore, we discovered that gemcitabine-induced loss of SIRT1 results in a nucleus-to-cytoplasm translocation of the sonic hedgehog (SHH) signaling activator GLI2, explaining the observed additional gemcitabine sensitivity in SHH-subtype ATRT. Treatment of ATRT xenograft-bearing mice with gemcitabine resulted in a >30% increase in median survival and yielded long-term survivors in two independent patient-derived xenograft models. These findings demonstrate that ATRTs are highly sensitive to gemcitabine treatment and may form part of a future multimodal treatment strategy for ATRTs.

Cortically-based Brain Tumors in Children: A Decision-tree Approach in the Radiology Reading Room.

Cortically-based brain tumors in children constitute a unique set of tumors with variably aggressive biological behavior. As radiologists play an integral role on the multidisciplinary medical team, a clinically useful and easy-to-follow flowchart for the differential diagnoses of these complex brain tumors is essential.This proposed algorithm tree provides the latest insights into the typical imaging characteristics and epidemiologic data that differentiate the tumor entities, taking into perspective the 2021 World Health Organization's classification and highlighting classic as well as newly identified pathologic subtypes using current molecular understanding.ABBREVIATIONS: Astroblastoma=AB) Angiocentric glioma (AG) Atypical teratoid rhabdoid tumor (ATRT) Central Nervous System tumor (CNS) CNS neuroblastoma FOXR2-activated (NB-FOXR2) Desmoplastic infantile glioma/astrocytoma (DIG/DIA) Diffuse hemispheric glioma, H3 G34-mutant (DHG) Diffuse glioneuronal tumor with oligodendroglioma-like features and nuclear clusters (DGONC) Dysembryoplastic neuroepithelial tumor (DNET) Embryonal Tumors with Multilayered Rosettes (ETMR) Ependymoma (EP) Focal cortical dysplasia (FCD) Ganglioglioma/gangliocytoma (GG) Infant-type hemispheric glioma (IHG) Intracranial pressure (ICP) Long-term epilepsy-associated tumors (LEATs) Pediatric diffuse low-grade gliomas (pLGG) MR spectroscopy (MRS) Multinodular and vacuolating neuronal tumor (MVNT) Overall survival (OS) Pediatric diffuse high-grade gliomas (pHGG).

Pediatric atypical teratoid/rhabdoid tumor in the cauda equina with rapid tumor progression: illustrative case.

Atypical teratoid/rhabdoid tumor (AT/RT) is an uncommon malignant neoplasm and rarely occurs in the spinal space, especially in the cauda equina. Only 8 cases of pediatric AT/RT of the cauda equina have been reported. Therefore, its clinical behavior and optimal treatment remain unclear. The authors describe the case of a 9-year-old boy who presented with progressive back and left leg pain. Initial magnetic resonance imaging showed an intradural extramedullary lesion at the L3-4 level, which progressed rapidly to the L2-5 level within a month. He underwent partial resection of the tumor with an L2-5 laminectomy. The histopathological diagnosis was AT/RT. He received adjuvant chemotherapy and radiotherapy, and his gait disturbance improved postoperatively. At 6 months' follow-up, disease recurrence was not observed. Although extremely rare, AT/RT should be included in the differential diagnosis for prompt therapeutic intervention. Safe resection with minimal functional impairment, followed by postoperative chemoradiation, can lead to tumor control and improve neurological function. https://thejns.org/doi/10.3171/CASE24219.

Features of Vascular Endothelial Growth Factor А (Vegf-А) Expression in Atypical Teratoid-Rhabdoid Tumor of the Central Nervous System in Children

Atypical teratoid rhabdoid tumors (AT/RT) are highly malignant neoplasms composed of poorly differentiated germline cells and a variable number of rhabdoid cells that can differentiate into different cell types. A key diagnostic factor for AT/RT is the absence of nuclear expression of the INI1 protein (SMARCB1 gene product) when tested with an anti-INI1 antibody in an immunohistochemical study. Currently, there is no standard treatment for AT/RT, but treatment approaches have become more aggressive and multimodal. In one study, AT/RT was found to be positive for VEGF. The purpose of our study was to examine the expression of VEGF-A in AT/RT in the central nervous system of children. We analyzed biopsy samples from 6 male patients aged 3 months to 8 years (average age 4.5 years). The level of VEGF-A expression was measured by counting the number of brown pixels in the cytoplasm of tumor cells using the PhotoM program in 1 mm2 of tumor tissue. Immunohistochemistry (IHC) revealed varying levels of cytoplasmic staining with an antibody to VEGF-A in 5 out of 6 patients, with the youngest patient (No. 6) showing staining only in endothelial cells. In conclusion, children with AT/RT exhibit different patterns of VEGF-A expression, potentially dependent on the molecular subgroup. Identifying this marker in these highly aggressive tumors could aid in developing new treatment protocols and determining which patients would benefit most from treatment.

Outcomes for children with recurrent/refractory atypical teratoid rhabdoid tumor: A single-institution study with molecular correlation.

Survival data for recurrent pediatric atypical teratoid rhabdoid tumor (ATRT) and its association to molecular groups are extremely limited. Single-institution retrospective study of 64 children less than 21years old with recurrent or treatment-refractory (progressive disease [PD]) ATRT treated at St. Jude Hospital from January 2000 to December 2020. Demographic, clinicopathologic, treatment, molecular grouping (SHH, TYR, and MYC) and germline data were collected. Progression-free survival (PFS2: time from PD to subsequent first progression) and overall survival (OSpostPD: time from PD to death/last follow-up) were estimated by Kaplan-Meier analysis. Median age at and time from initial diagnosis to PD were 2.1years (range: 0.5-17.9years) and 5.4months (range: 0.5-125.6months), respectively. Only five of 64 children (7.8%) are alive at median follow-up of 10.9 (range: 4.2-18.1) years from PD. The 2/5-year PFS2 and OSpostPD were 3.1% (±1.8%)/1.6% (±1.1%) and 20.3% (±4.8%)/7.3% (±3.5%), respectively. Children with TYR group (n=10) had a better OSpostPD compared to those with MYC (n=11) (2-year survival estimates: 60.0%±14.3% vs. 18.2%±9.5%; p=.019), or those with SHH (n=21; 4.8%±3.3%; p=.014). In univariate analyses, OSpostPD was better with older age at diagnosis (p=.037), female gender (p=.008), and metastatic site of PD compared to local or combined sites of PD (p<.001). Two-year OSpostPD for patients receiving any salvage therapy (n=39) post PD was 33.3%±7.3%. Children with recurrent/refractory ATRT have dismal outcomes. Older age at diagnosis, female gender, TYR group, and metastatic site of PD were associated with relatively longer survival in our study.

A kinome drug screen identifies multi-TKI synergies and ERBB2 signaling as a therapeutic vulnerability in MYC/TYR subgroup atypical teratoid rhabdoid tumors.

Atypical teratoid rhabdoid tumor (ATRT) is a rare, devastating, and largely incurable pediatric brain tumor. Although recent studies have uncovered 3 molecular subgroups of ATRTs with distinct disease patterns, and signaling features, the therapeutic profiles of ATRT subgroups remain incompletely elucidated. We examined the effect of 465 kinase inhibitors on a panel of ATRT subgroup-specific cell lines. We then applied multiomics analyses to investigate the underlying molecular mechanism of kinase inhibitor efficacy in ATRT subgroups. We observed that ATRT cell lines are broadly sensitive to inhibitors of the PI3K and MAPK signaling pathways, as well as CDKs, AURKA/B kinases, and polo-like kinase 1. We identified 2 classes of multikinase inhibitors predominantly targeting receptor tyrosine kinases including PDGFR and EGFR/ERBB2 in MYC/TYR ATRT cells. The PDGFRB inhibitor, Dasatinib, synergistically affected MYC/TYR ATRT cell growth when combined with broad-acting PI3K and MAPK pathway inhibitors, including Rapamycin and Trametinib. We observed that MYC/TYR ATRT cells were also distinctly sensitive to various inhibitors of ERBB2 signaling. Transcriptional, H3K27Ac ChIPSeq, ATACSeq, and HiChIP analyses of primary MYC/TYR ATRTs revealed ERBB2 expression, which correlated with differential methylation and activation of a distinct enhancer element by DNA looping. Significantly, we show the brain penetrant EGFR/ERBB2 inhibitor, Afatinib, specifically inhibited in vitro and in vivo growth of MYC/TYR ATRT cells. Taken together, our studies suggest combined treatments with PDGFR and ERBB2-directed TKIs with inhibitors of the PI3K and MAPK pathways as an important new therapeutic strategy for the MYC/TYR subgroup of ATRTs.

ATRT-15. COMBINING THE PI3K INHIBITOR PAXALISIB WITH NUCLEOSIDE ANALOG GEMCITABINE TO IMPROVE SURVIVAL OF ATYPICAL TERATOID/RHABDOID TUMORS

Abstract BACKGROUND Atypical teratoid/rhabdoid tumors (ATRT) have a dismal overall survival. Targeting the mTORC1/2 pathway kills ATRT tumor cells and increases the survival of mice bearing orthotopic xenografts. Paxalisib is a brain penetrant PI3K inhibitor that is in pediatric clinical trials for diffuse midline glioma. Paxalisib activates the integrated stress response (ISR) in ATRT. Consistent high-level activation of the ISR leads to cell death. We hypothesize paxalisib will synergize with the DNA-damaging agent gemcitabine, which also triggers the ISR, to over-activate this pathway and drive ATRT apoptosis. METHODS We analyzed ISR gene expression following mTOR inhibition via RNA-seq. Children’s Brain Tumor Network (CBTN) provided comparative data on ISR genes in ATRT and other pediatric brain tumors. Paxalisib/gemcitabine effects were evaluated through cell-based assays, western blot for ISR markers, and survival in three murine models. RESULTS ATRT have high baseline expression of ISR genes (CBTN: ATF4, eIF2α), and mTOR inhibition leads to activation of ISR genes (ATF4, CHOP, PPP1R15A, p&amp;lt;0.05). Paxalisib monotherapy significantly extends median survival in murine models compared to vehicle controls (CHLA-06: 40 to 54 days, p=0.001; BT-12: 21 to 35 days, p=0.05). Paxalisib/gemcitabine therapy synergized to slow cell growth and induce cell death (SynergyFinder BLISS score in five ATRT cell lines). Combination therapy leads to ISR activation (western blot: p-eIF2α, ATF4, CHOP). Combination slowed tumor growth (bioluminescent imaging) and led to significant extension of survival in orthotopic xenograft models (CHLA-06: 22 to 82.5 days; BT-37 56-day vehicle median survival while undefined combination survival). A third model is ongoing and showing similar results. CONCLUSIONS Paxalisib/gemcitabine therapy shows potential for targeting ATRT by over-activating the ISR. Our findings prompted the Pediatric Neuro-Oncology Consortium to consider this combination for inclusion in an upcoming clinical trial targeting relapsed/refractory ATRT, offering a novel approach to treat this aggressive tumor.