Detection of wild-type EGFR amplification and EGFRvIII mutation in CSF-derived extracellular vesicles of glioblastoma patients
Figueroa JM, Skog J, Akers J, Li H, Komotar R, Jensen R, Ringel F, Yang I, Kalkanis S, Thompson R, LoGuidice L, Berghoff E, Parsa A, Liau L, Curry W, Cahill D, Bettegowda C, Lang FF, Chiocca EA, Henson J, Kim R, Breakefield X, Chen C, Messer K, Hochberg F, and Carter BS. Detection of wtEGFR Amplification and EGFRvIII Mutation in CSF-Derived Extracellular Vesicles of Glioblastoma Patients. Neuro Oncol 2017; 19(11):1494-1502.
Background: RNAs within extracellular vesicles (EVs) have potential as diagnostic biomarkers for patients with cancer and are identified in a variety of biofluids. Glioblastomas (GBMs) release EVs containing RNA into cerebrospinal fluid (CSF). Here we describe a multi-institutional study of RNA extracted from CSF-derived EVs of GBM patients to detect the presence of tumor-associated amplifications and mutations in epidermal growth factor receptor (EGFR).
Methods: CSF and matching tumor tissue were obtained from patients undergoing resection of GBMs. We determined wild-type (wt)EGFR DNA copy number amplification, as well as wtEGFR and EGFR variant (v)III RNA expression in tumor samples. We also characterized wtEGFR and EGFRvIII RNA expression in CSF-derived EVs.
Results: EGFRvIII-positive tumors had significantly greater wtEGFR DNA amplification (P = 0.02) and RNA expression (P = 0.03), and EGFRvIII-positive CSF-derived EVs had significantly more wtEGFR RNA expression (P = 0.004). EGFRvIII was detected in CSF-derived EVs for 14 of the 23 EGFRvIII tissue-positive GBM patients. Conversely, only one of the 48 EGFRvIII tissue-negative patients had the EGFRvIII mutation detected in their CSF-derived EVs. These results yield a sensitivity of 61% and a specificity of 98% for the utility of CSF-derived EVs to detect an EGFRvIII-positive GBM.
Conclusion: Our results demonstrate CSF-derived EVs contain RNA signatures reflective of the underlying molecular genetic status of GBMs in terms of wtEGFR expression and EGFRvIII status. The high specificity of the CSF-derived EV diagnostic test gives us an accurate determination of positive EGFRvIII tumor status and is essentially a less invasive "liquid biopsy" that might direct mutation-specific therapies for GBMs.
Medical Subject Headings
Adult; Aged; Aged, 80 and over; Biomarkers, Tumor; Brain Neoplasms; ErbB Receptors; Extracellular Vesicles; Female; Follow-Up Studies; Gene Amplification; Gene Expression Regulation, Neoplastic; Glioblastoma; Humans; Male; Middle Aged; Mutation; Prognosis; Signal Transduction; Young Adult