Abstract Details

Title An IDH Wildtype, EGFR Amplified and TERT Promoter Mutated Astrocytoma that is Clinically and Molecularly Incompatible with the Diagnosis of Glioblastoma, IDH Wildtype.

Topic Neuro-oncology

Presentation(s) P13 - Poster Session 13 (8:00 AM-9:00 AM)

Poster/Presentation
Number 4-001

Objective Molecular characterization of a clinically indolent IDH-wildtype astrocytoma

Background In the 2021 WHO Classification, IDH-wildtype, EGFR amplified, TERT promoter mutated diffuse astrocytic tumors are considered glioblastoma, IDH-wildtype. It has been reported that EGFR amplified, TERT promoter mutated IDH-wildtype gliomas have a 100% specificity for glioblastoma, IDH-wildtype on methylation profiling.

Design/Methods We report the case of a patient with a diagnosis of anaplastic astrocytoma, IDH-wildtype based on the 2016 WHO classification who underwent molecular profiling via the CLIA-certified, FDA-authorized next generation sequencing platform, MSK-IMPACT, and methylation profiling using the Illumina methylationEPIC/850K bead array platform.

Results We present a 66-year-old woman who was incidentally discovered to have a non-enhancing FLAIR abnormality in the left temporal lobe during an evaluation for headache in 2007. She remained under radiographic surveillance and was clinically stable for 12 years, until she presented with a seizure. Imaging revealed the previously identified non-enhancing, diffuse, expansile FLAIR lesion in the anterior temporal lobe. She elected to continue surveillance until 2021, at which time she underwent a subtotal resection and treatment with concurrent radiotherapy and temozolomide due to worsening of seizures. She was diagnosed with an anaplastic astrocytoma, IDH-wildtype based on the 2016 WHO Classification. Next generation sequencing revealed a TERT promoter mutation, EGFR amplification, and an EGFR-GARS fusion. The tumor did not match a methylation class on the methylation classifier developed by the German Cancer Research Center and Heidelberg University.

Conclusions While this tumor is a glioblastoma, IDH-wildtype by the 2021 WHO classification, the indolent behavior over 14 years and the absence of a match with tumor types recognized by the Heidelberg classifier suggest that this is not a glioblastoma. The presence of a TERT promoter mutation, EGFR amplification, and chromosome 7/10 alterations should be interpreted in the context of clinical behavior and other molecular analysis.

Authors/Disclosures
Marina Kushnirsky, MD PRESENTER	Dr. Kushnirsky has nothing to disclose.
Richard Hickman	No disclosure on file
Lauren Schaff, MD, FAAN (Memorial Sloan Kettering Cancer Center)	Dr. Schaff has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Guidepoint. Dr. Schaff has received personal compensation in the range of $500-$4,999 for serving as a Consultant for BTG, plc. The institution of Dr. Schaff has received research support from BTG, plc. Dr. Schaff has received personal compensation in the range of $500-$4,999 for serving as a Speaker with Ono.
	No disclosure on file
	No disclosure on file
Andrew L. Lin, MD (Memorial Sloan Kettering Cancer Center)	The institution of Dr. Lin has received research support from Bristol Myers Squibb. The institution of Dr. Lin has received research support from NantOmics. The institution of Dr. Lin has received research support from Society of Memorial Sloan Kettering Cancer Center.

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