Current Molecular and Clinical Landscape of ATRT - The Link to Future Therapies

What is New in Pediatric Hepatic Neoplasms

The goal of this review is to provide a practical update on hepatic lesions affecting the pediatric population and is not meant to be an exhaustive summary of each entity. Hepatoblastoma is purposely not discussed as recent comprehensive reviews on this topic are available; instead, a discussion on rhabdoid tumor and the evolving concept of small cell undifferentiated hepatoblastoma and blastemal hepatoblastoma is included.

Effects of Induced Pluripotent Stem Cell-Derived Astrocytes on Cisplatin Sensitivity in Pediatric Brain Cancer Cells

Background: ATRTs and DIPGs are deadly pediatric brain tumors with poor prognosis. These tumors can develop resistance to chemotherapies, which may be significantly influenced by their microenvironment. Since astrocytes are the most abundant glial cell type in the brain microenvironment and may support tumor growth and chemoresistance, this study investigated the effects of induced pluripotent stem cell-derived astrocytes (iPSC-astrocytes) on cisplatin sensitivity in CHLA-05-ATRT and SF8628 (DIPG) cells. iPSCs provide an unlimited and standardized source of nascent astrocytes, which enables modeling the interaction between childhood brain tumor cells and iPSC-astrocytes within a controlled coculture system. Methods: To study the effects on tumor growth, the iPSC-astrocytes were cocultured with tumor cells. Additionally, the tumor cells were exposed to various concentrations of cisplatin to evaluate their chemosensitivity in the presence of astrocytes. Results: The paracrine interaction of iPSC-astrocytes with tumor cells upregulated astrocyte activation markers GFAP and STAT3 and promoted tumor cell proliferation. Moreover, the cisplatin treatment significantly decreased the viability of CHLA-05-ATRT and SF8628 cells. However, tumor cells exhibited reduced sensitivity to cisplatin in the coculture with iPSC-astrocytes. During cisplatin treatment, DIPG cells in particular showed upregulation of resistance markers, ERK1, STAT3, and MTDH, which are associated with enhanced proliferation and invasion. They also had increased expression of APEX1, which is involved in the base excision repair pathway following cisplatin-induced DNA damage. Conclusion: These findings underscore the significance of the tumor microenvironment in modulating tumor cell survival and chemosensitivity.

Case report: Molecular characterization of adult atypical teratoid rhabdoid tumor and review of the literature

Background and importance

Atypical teratoid rhabdoid tumors (ATRTs) are typically aggressive pediatric tumors with a median survival of 11 months. Due to the paucity of cases in adults, the clinical behavior of these pathologies is not well understood. Here we present the case of a 41-year-old female patient with postoperative hyperprogression of a sellar ATRT and provide a detailed description of the molecular composition of this tumor, the protocol used to treat this patient, and the ultimate outcome of this patient.

Clinical presentation

The patient is a 41-year-old woman who presented with headaches and double vision. MRI revealed a sellar/suprasellar mass with involvement of bilateral cavernous sinuses. Following the quick symptom progression, resection of the tumor with exploration of the bilateral cavernous sinuses was performed, with a final pathologic diagnosis of ATRT-MYC, a known subtype of ATRT. The tumor recurred within 1 month of surgery, attaining a size equivalent to its preoperative state. Postoperatively, the patient received craniospinal radiation and adjuvant chemotherapy with an excellent response but had a recurrence of the tumor in the brainstem 1 year after her diagnosis and died 13 months after presentation.

Discussion

Sellar ATRT in adults is an exceedingly rare entity. The detailed description of our case highlights the aggressiveness of these tumors and the utility of postoperative chemotherapy and radiation, but also the inevitable progression of these tumors along the craniospinal axis.

Conclusion

Sellar ATRTs should be considered in the differential diagnosis of a sellar/suprasellar mass, especially in women in their 40s. Emphasis should be placed on accurate diagnosis and quick postoperative recovery with early initiation of adjuvant radiation and chemotherapy.

Mesenteric SMARCA2-Deficient Yet SMARCA4-Preserved Aggressive Undifferentiated Tumor: A Case Report

INTRODUCTION

The SWItch Sucrose Non-Fermentable (SWI/SNF) chromatin remodeling complex, which includes components such as SMARCA4 and SMARCA2, regulates gene expression by controlling chromatin compaction and accessibility in an ATP-dependent manner. These components are also implicated in carcinogenesis. Thoracic SMARCA4-deficient undifferentiated tumor is a recently introduced category in the fifth edition of the WHO classification in 2021, typically exhibiting rhabdoid morphology in adults. In contrast, rhabdoid tumors occurring within the abdominal cavity in adults are rare and sporadic, with limited detailed documentation, making them relatively less understood compared to their thoracic counterparts.

CASE PRESENTATION

A man in his 70s was admitted to our hospital with a chief complaint of fever. He was diagnosed with a mesenteric solid tumor measuring 6 cm in maximum diameter. Shortly after the hospitalization, bowel obstruction became evident, accompanied by the rapid tumor progression, and then surgical treatment was attempted. A soft, bulky tumor situated in the mesentery accompanied by extensive tumor dissemination was found intraoperatively. The tumor was resected along with the obstructed terminal ileum, aiming to restore intestinal patency and obtain tissue samples. Histopathologically, the tumor represented morphological features resembling a rhabdoid tumor along with a high Ki67 labeling index (50%). Immunohistochemistry revealed SMARCA2 deficiency with preserved SMARCA4 expression. The absence of Claudin-4 expression further supported the diagnosis of a mesenteric SMARCA2-deficient yet SMARCA4-preserved undifferentiated tumor. The patient succumbed 20 days after surgery due to aggressive peritonitis carcinomatosis.

CONCLUSIONS

To the best of our knowledge, this is the first case report of a mesenteric undifferentiated tumor with rhabdoid cytomorphology due to SWI/SNF chromatin remodeling complex deficiency caused by isolated SMARCA2 deficiency. The tumor, in our case, arose in the abdominal organs and appears to share a similar oncogenic process with the category of thoracic SMARCA4-deficient undifferentiated tumors in the WHO classification. Further research is required to improve our understanding of its clinical features, underlying mechanisms, and optimal management strategies.

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.

High-Grade Atypical Teratoid/Rhabdoid Tumor in the Pituitary Region

Atypical teratoid/rhabdoid tumors (AT/RTs) are embryological tumors of the central nervous system (CNS). They are typically found in children, with rare presentations in adults. We describe the presentation of an AT/RT in the pituitary region of a 37-year-old female. The patient presented with a two-week history of intractable cephalgia with sudden onset of monocular diplopia and left-sided cranial nerve VI palsy. The patient underwent transsphenoidal resection of their mass, which revealed the diagnosis. She then underwent systemic therapy with chemotherapy as well as radiation. She ultimately died 14 months after treatment completion due to unrelated events. The case highlights the rarity of AT/RT in adults, emphasizing the challenge of establishing standardized treatment protocols due to its rarity in adult presentations.