Study of Tumor Samples From Patients With Ependymoma Treated on the Children's Oncology Group ACNS0121 Trial

PRIMARY OBJECTIVES:

I. To examine the prognostic role of histopathological variables, in particular cellular density, mitotic count, and tumor cell invasion in intracranial pediatric ependymomas.

II. To study whether hTERT expression and telomere dysfunction correlate with progression-free survival (PFS) and overall survival (OS) in pediatric intracranial ependymoma.

III. To perform a genome-wide copy number screen and validation of copy number abnormalities (CNAs) on formalin-fixed paraffin-embedded (FFPE) ependymomas using Affymetrix Molecular Inversion Probe (MIP) arrays and interphase fluorescence in situ hybridization (iFISH). IV. To evaluate associations between infiltration of immune markers and PFS as well as OS in pediatric ependymoma.

V. To examine the role of 1q gain and 9p deletion in pediatric ependymomas by exploring their association with PFS and OS in a multivariable model.

VI. To establish the frequency and clinicopathological associations of mutations in genes involved in Notch pathway signaling.

OUTLINE:

Archived tumor tissue samples are analyzed for cellular density, mitotic count, tumor cell invasion, hTERT expression, telomere dysfunction, 1q gain, 9p deletion, and genetic mutations by IHC, Affymetrix Molecular Inversion Probe (MIP) arrays, and fluorescence in situ hybridization (FISH). Results are then correlated with patient-outcome variables and known risk factors, namely gender, age at diagnosis, tumor location infratentorial vs. supratentorial), tumor grade (differentiated vs anaplastic), and extent of surgery as well as pathologic variables.

Inclusion criteria

• Diagnosed with ependymoma and treated on COG-ACNS0121
• Previously collected tumor samples banked at the Children Oncology Group BioPathology