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Rhabdoid tumors (RTs) of the brain (atypical teratoid/rhabdoid tumor; AT/RT) and extracranial sites (most often the kidney; RTK) are malignant tumors predominantly occurring in children, frequently those with SMARCB1 germline alterations. Here we present data from seven RTs from three pediatric patients who all had multi-organ involvement. The tumors were analyzed using a multimodal molecular approach, which included exome sequencing of tumor and germline comparator and RNA sequencing and DNA array-based methylation profiling of tumors. SMARCB1 germline alterations were identified in all patients and in all tumors. We observed a second hit in SMARCB1 via chr22 loss of heterozygosity. By methylation profiling, all tumors were classified as rhabdoid tumors with a corresponding subclassification within the MYC, TYR, or SHH AT/RT subgroups. Using RNA-seq gene expression clustering, we recapitulated the classification of known AT/RT subgroups. Synchronous brain and kidney tumors from the same patient showed different patterns of either copy number variants, single-nucleotide variants, and/or genome-wide DNA methylation, suggestive of non-clonal origin. Furthermore, we demonstrated that a lung and abdominal metastasis from two patients shared overlapping molecular features with the patient’s primary kidney tumor, indicating the likely origin of the metastasis. In addition to the SMARCB1 events, we identified other whole-chromosome events and single-nucleotide variants in tumors, but none were found to be prognostic, diagnostic, or offer therapeutic potential for rhabdoid tumors. While our findings are of biological interest, there may also be clinical value in comprehensive molecular profiling in patients with multiple rhabdoid tumors, particularly given the potential prognostic and therapeutic implications for different rhabdoid tumor subgroups demonstrated in recent clinical trials and other large cohort studies.

BACKGROUND Rhabdoid predisposition syndrome is characterized by germline alterations in SMARCB1 or SMARCA4, leading to synchronous or metachronous central nervous system (CNS) and extra-CNS rhabdoid tumors. Rare survivors have been reported to date. METHODS We describe the molecular profiling and treatment regimen of three patients with synchronous atypical teratoid/rhabdoid tumor (ATRT) and malignant rhabdoid tumor of the kidney (MRT-K). All patients underwent radical nephrectomy of the kidney, and gross total resection of the primary CNS tumor was achieved for two patients. An intensive chemotherapy regimen was administered; an induction phase based on the modified Third Intergroup Rhabdomyosarcoma Study (IRS-III) for ATRT followed by a consolidation phase with three cycles of high-dose chemotherapy and autologous hematopoietic progenitor cell rescue, without irradiation. All three patients were enrolled on an institutional comprehensive genomic profiling protocol. RESULTS A germline focal 22q deletion, including SMARCB1, was detected in two patients, while the third patient had a maternally-inherited heterozygous frameshift variant in SMARCB1. Somatic loss of heterozygosity of 22q was identified in all patients, resulting in biallelic inactivation of SMARCB1. Divergent tumor subgroups were described using DNA methylation. The three MRT-K samples were classified as MYC subtype. One ATRT was classified as SHH while the other as TYR. One patient is currently three years off-therapy without evidence of disease, while the other two patients have completed the consolidation phase without recurrent disease. CONCLUSION Molecular profiling of CNS and extra-CNS rhabdoid tumors revealed different epigenetic subgroups. An intensive multimodal therapeutic approach without irradiation may achieve prolonged survival.

Primary spinal cord tumors contribute to ≤ 10% of central nervous system tumors in individuals of pediatric or adolescent age. Among intramedullary tumors, spinal ependymomas make up ~ 30% of this rare tumor population. A twelve-year-old male presented with an intradural, extramedullary mass occupying the dorsal spinal canal from C6 through T2. Gross total resection and histopathology revealed a World Health Organization (WHO) grade 2 ependymoma. He recurred eleven months later with extension from C2 through T1-T2. Subtotal resection was achieved followed by focal proton beam irradiation and chemotherapy. Histopathology was consistent with WHO grade 3 ependymoma. Molecular profiling of the primary and recurrent tumors revealed a novel amplification of the MYC (8q24) gene, which was confirmed by fluorescence in situ hybridization studies. Although MYC amplification in spinal ependymoma is exceedingly rare, a newly described classification of spinal ependymoma harboring MYCN (2p24) amplification (SP-MYCN) has been defined by DNA methylation-array based profiling. These individuals typically present with a malignant progression and dismal outcomes, contrary to the universally excellent survival outcomes seen in other spinal ependymomas. DNA methylation array-based classification confidently classified this tumor as SP-MYCN ependymoma. Notably, among the cohort of 52 tumors comprising the SP-MYCN methylation class, none harbor MYC amplification, highlighting the rarity of this genomic amplification in spinal ependymoma. A literature review comparing our individual to reported SP-MYCN tumors (n = 26) revealed similarities in clinical, histopathologic, and molecular features. Thus, we provide evidence from a single case to support the inclusion of MYC amplified spinal ependymoma within the molecular subgroup of SP-MYCN.

Fetoplacental neuroblastoma metastasis has been postulated as a mechanism accounting for concordant cases where one twin develops a primary tumour and the second twin manifests the disease without an identifiable primary site. These tumours may originate and spread concomitantly due to the same genetic background shared by monozygotic twins. This study investigated the molecular profile of stage MS neuroblastoma presenting concomitantly in monozygotic twins. Comparative genomic hybridisation (aCGH) was done for each of the twin liver tumour and peripheral blood samples at diagnosis. Comparison of copy-number variation (CNV) regions revealed a set of CNVs that were common to both tumour specimens and not apparent in the blood. The CNV signature in both twins’ tumours was highly similar, suggesting a common clonal origin. Additional findings included large deletion of chromosome 10 and amplification of chromosome 17. Notably, both liver samples had amplification of a short region involving DEIN (chromosome 4q34.1). Similar CNVs strongly support a common clonal origin and metastatic spread from one twin to the other. DEIN is a long-coding RNA (IncRNA) that has been found highly expressed in stage MS neuroblastoma and is likely involved in biological processes such as cell migration and metastasis.

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BACKGROUND: MRI-guided laser interstitial thermal therapy (LITT) is a minimally invasive, cytoreductive surgery useful for managing unresectable brain tumors. LITT disrupts the blood brain barrier (BBB) and facilitates chemotherapy delivery. We report the toxicity and outcome for pediatric brain tumors treated on a pilot trial of LITT and chemotherapy. The primary objectives were to quantify peritumoral BBB disruption following LITT and evaluate toxicity and efficacy. METHODS: The trial had two arms, A: patients with newly diagnosed gliomas underwent LITT followed by standard of care management, and B: patients with relapsed malignant brain tumors received 6 weeks of weekly doxorubicin post-LITT followed by maintenance etoposide. RESULTS: Between 2015 – 2018, six patients were enrolled: five on arm A (four with low-grade gliomas, one with high-grade glioma), one on Arm B with progressive anaplastic astrocytoma. All patients tolerated the procedure well; four experienced a transient hemiparesis post-LITT. The Arm B patient progressed and died of disease 2 months and 22 months post-LITT, respectively. The HGG patient received standard therapy and remains without disease progression 44 months post-LITT. One patient with LGG required additional treatment for disease progression 14 months post-LITT. Two patients with LGGs did not require additional therapy, now 51 and 41 months post-LITT. One patient was alive 24 weeks post-LITT and subsequently lost to follow-up. Peritumoral BBB disruption was analyzed in two ways: serum abundance of brain-derived proteins and MRI Dynamic contrast enhancement (DCE). Neuron-specific enolase were measurable in the serum of all patients, using ELISA up to 84 days post-LITT. DCE 2 weeks post-LITT demonstrated increased enhancement and FLAIR signal, consistent with BBB disruption and vasogenic edema. This effect was evident up to 4 months post-procedure. CONCLUSION: LITT is safe in children with brain tumors and can be combined with chemotherapy. DCE and serum brain-derived proteins can measure BBB disruption.

INTRODUCTION: Congenital intracranial teratomas (CITs) are rare tumors occurring in the first 60 days of life, often associated with dismal prognosis, posing challenges in both oncologic and surgical management. METHODS: We report a patient with a congenital mature teratoma diagnosed prenatally, who underwent successful surgical resection following neoadjuvant chemotherapy. We also performed an updated literature review on CIT outcomes. RESULTS: A newborn female, diagnosed prenatally with a complex midline intracranial echogenic mass, underwent postnatal brain MRI which demonstrated a supratentorial large complex enhancing mass with solid and cystic components, with associated obstructed hydrocephalus. Serum alpha-fetoprotein (AFP) and beta-human chorionic gonadotropin were normal for age. Tumor biopsy revealed mature teratoma. AFP obtained from cyst fluid during fenestration was significantly elevated at 8 weeks of life. Due to concerns for possible malignant transformation and in an attempt to alter tumor vascularity facilitating surgical resection, the patient received two cycles of neoadjuvant carboplatin and etoposide, followed by tumor resection without significant intraoperative bleeding. There was no evidence of immature components on final pathology. The patient remains without tumor recurrence, now 9 months, since surgical resection. Review of literature yielded 76 cases of CITs: eight patients with mature teratoma, of which six remained alive following tumor resection. Five patients with immature teratoma received chemotherapy prior to resection; three remained alive post-resection (follow-up range 3-20 years). DISCUSSION: CITs are typically associated with poor prognosis, with reported one-year survival of 7.2-12%. Surgical excision is the mainstay of treatment, often limited by intraoperative hemorrhage. Neoadjuvant chemotherapy has been employed as a successful strategy to reduce tumor volume and vascularity in a variety of pediatric brain tumors; more specifically, carboplatin and etoposide are utilized as neoadjuvant chemotherapy for non-germinomatous germ cell tumors to facilitate excision in older children. Their role in CITs requires further evaluation.