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Abstract Details

AbstractDetails

Abstract Date: 5/1/2016

Author(s):
Ganesh Mani Shankar, MD
Matthew Meyerson, MD, PhD
Jay Loeffler, MD
Jeffrey Wisoff, MD
Priscilla Brastianos, MD
John Shin, MD
Ann-Christine Duhaime, MD
Michael Taylor, MD, PhD
David Louis, MD
Daniel Cahill, MD, PhD
William Curry, MD (Boston, MA)

Introduction

Intramedullary spinal cord neoplasms represent 2-4% of central nervous system tumors, of which astrocytic gliomas represent 80%. Histologic grading can be challenging in spinal cord astrocytomas because of the often relatively small samples obtained at the time of the surgical procedure. To address the hypothesis that genomic alterations could segregate spinal cord astrocytoma histologic grades, we performed sequencing of cancer-related genes in a cohort of 17 tumors.


Methods

Spinal cord astrocytomas from children and adults were obtained as formalin-fixed, paraffin-embedded (FFPE) specimens from Massachusetts General Hospital, the University of Toronto, and New York University. Targeted sequencing of 560 cancer related genes and 39 translocation events was performed on DNA extracted from these specimens. Data was analyzed for somatic nucleotide variants, copy number changes and rearrangement analysis.


Results

The most recurrent findings in Grade I spinal cord astrocytomas were a BRAF-KIAA1549 translocation (n=4/10) and BRAF copy number gain (n=5/10). WHO grade II astrocytomas were similarly characterized by alterations involved in the MAPK-ERK or PI3K pathways, including BRAF amplification (n=2/3).  In addition, we observed that all four Grade III and IV astrocytomas in the discovery cohort shared the H3F3A K27M mutation. Further targeted Sanger sequencing of H3F3A was performed in five additional specimens and revealed the K27M mutation in 2/3 spinal Grade IV astrocytomas and 0/2 Grade I astrocytomas.

Conclusion:

The findings described here represent the first genomic characterization of spinal cord astrocytomas. In summary, our observations indicate that BRAF alterations and histone H3F3A K27M mutations are grade-related features of spinal cord astrocytomas that should enter routine initial evaluation of spinal cord gliomas and provide a potential foundation for adjuvant therapeutic strategies.

Keywords:

Article ID: AA-34923


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