Molecular classification of a complex structural rearrangement of the RB1 locus in an infant with sporadic, isolated, intracranial, sellar region retinoblastoma.

Retinoblastoma is a childhood cancer of the retina involving germline or somatic alterations of the RB Transcriptional Corepressor 1 gene, RB1. Rare cases of sellar-suprasellar region retinoblastoma without evidence of ocular or pineal tumors have been described. A nine-month-old male presented with a sellar-suprasellar region mass. Histopathology showed an embryonal tumor with focal Flexner-Wintersteiner-like rosettes and loss of retinoblastoma protein (RB1) expression by immunohistochemistry. DNA array-based methylation profiling confidently classified the tumor as pineoblastoma group A/intracranial retinoblastoma. The patient was subsequently enrolled on an institutional translational cancer research protocol and underwent comprehensive molecular profiling, including paired tumor/normal exome and genome sequencing and RNA-sequencing of the tumor. Additionally, Pacific Biosciences (PacBio) Single Molecule Real Time (SMRT) sequencing was performed from comparator normal and disease-involved tissue to resolve complex structural variations. RNA-sequencing revealed multiple fusions clustered within 13q14.1-q21.3, including a novel in-frame fusion of RB1-SIAH3 predicted to prematurely truncate the RB1 protein. SMRT sequencing revealed a complex structural rearrangement spanning 13q14.11-q31.3, including two somatic structural variants within intron 17 of RB1. These events corresponded to the RB1-SIAH3 fusion and a novel RB1 rearrangement expected to correlate with the complete absence of RB1 protein expression. Comprehensive molecular analysis, including DNA array-based methylation profiling and sequencing-based methodologies, were critical for classification and understanding the complex mechanism of RB1 inactivation in this diagnostically challenging tumor.

Synchronous Central Nervous System Atypical Teratoid/Rhabdoid Tumor and Malignant Rhabdoid Tumor of the Kidney: Case Report of a Long-Term Survivor and Review of the Literature.

BACKGROUND: Atypical teratoid/rhabdoid tumor (AT/RT) of the central nervous system (CNS) with synchronous or metachronous extra-CNS disease is a rare childhood malignancy with a dismal prognosis. CASE DESCRIPTION: We report a 7-week-old female with metastatic AT/RT and synchronous malignant rhabdoid tumor of the kidney who received an intensive multimodal approach combining surgical resection, intrathecal chemotherapy, and high-dose chemotherapy with autologous peripheral blood stem cell transplant (PBSCT). She is currently 24 months old without any evidence of disease. In addition, we completed an extensive literature review of cases with CNS AT/RT and synchronous or metachronous extra-CNS primary tumors. To date, 31 pediatric cases have been reported, and the median overall-survival was 6 months after diagnosis. The only 3 survivors received autologous PBSCT, and 2 of these patients had complete resection of their CNS tumor. CONCLUSIONS: The rarity of CNS AT/RT with extra-CNS primary disease and the lack of standard treatment contribute to its reported dismal prognosis. We report a case of a long-term survivor with metastatic AT/RT and synchronous extra-CNS primary tumor. Maximal surgical resection, intrathecal chemotherapy, and consolidative autologous PBSCT may improve prognosis and avoid radiation.

Brentuximab-vedotin maintenance following chemotherapy without irradiation for primary intracranial embryonal carcinoma in down syndrome.

BACKGROUND: Germ cell tumors (GCT) are the most common central nervous system (CNS) tumors in individuals with Down syndrome. Patients with Down syndrome treated with CNS irradiation are at increased risk of developing cerebrovascular complications such as moyamoya disease. Embryonal carcinoma components are recognized to be more resistant to conventional chemotherapy and radiotherapy and confer a very poor prognosis. CD30 is a member of the tumor necrosis factor-receptor superfamily. CD30+ has a limited expression in normal cells but is the defining marker for embryonal carcinoma. Brentuximab-vedotin is a novel antibody-drug conjugate consisting of the chimeric anti-CD30 antibody conjugated to an anti-tubulin synthetic analog monomethyl auristatin E. METHODS: A retrospective review of the patient's records was conducted in September 2017. RESULTS: We report upon our management of a teenage girl with Down syndrome and a suprasellar pure embryonal carcinoma utilizing an intensive chemotherapy regimen followed by brentuximab-vedotin without irradiation. The patient received two cycles of carboplatin and etoposide interspersed with one cycle of cyclophosphamide and etoposide for induction followed by three cycles of marrow-ablative thiotepa and carboplatin rescued by autologous hematopoietic stem cell. Finally, She received six cycles of intravenous brentuximab-vedotin. The patient continues without evidence of recurrent tumor by MRI and tumor marker surveillance 24 months since diagnosis, with no adverse sequelae of her treatment. CONCLUSIONS: Brentuximab-vedotin may provide a selective and safe alternative (or adjunct) to radiotherapy in the management of patients with CD30-positive CNS embryonal carcinoma, especially for those patients at high risk of developing irradiation-related complications.