Glioblastoma (GBM, IDH-wildtype) frequently shows amplification of EGFR with a specific truncation mutation in the extracellular domain. This variant, most commonly amplified in GBM, is:

• A EGFRvII (deletion of exon 14-15)
• B EGFR L858R point mutation
• C EGFR exon 19 deletion
• D EGFRvIII (deletion of exons 2-7 of EGFR) ✓

Explanation

EGFRvIII is the most common EGFR mutation in GBM, consisting of an in-frame deletion of exons 2-7 encoding part of the extracellular ligand-binding domain. This results in a constitutively active receptor that signals without ligand binding and cannot be downregulated by internalization. EGFRvIII is found in ~25-50% of EGFRamp GBMs and is GBM-specific (not found in other tissues), making it an attractive therapeutic target. EGFR L858R and exon 19 deletions are the common sensitizing mutations in non-small-cell lung adenocarcinoma.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.