Combining genomic analyses with tumour-derived slice cultures for the characterization of an EGFR-activating kinase mutation in a case of glioblastoma.

Background: Epidermal growth factor receptor (EGFR) gene alterations and amplification are frequently reported in cases of glioblastoma (GBM). However, EGFR-activating mutations that confer proven sensitivity to tyrosine kinase inhibitors (TKIs) in lung cancer have not yet been reported in GBM.

Case Presentation: Using next-generation sequencing, array comparative genomic hybridization and droplet digital PCR, we identified the p.L861Q EGFR mutation in a case of GBM for the first time. The mutation was associated with gene amplification. L861Q may be a clinically valuable mutation because it is known to sensitize non-small-cell lung cancers to treatment with the second-generation EGFR TKI afatinib in particular. Furthermore, we used slice culture of the patient's GBM explant to evaluate the tumour's sensitivity to various EGFR-targeting drugs. Our results suggested that the tumour was not intrinsically sensitive to these drugs.

Conclusions: Our results highlight (i) the value of comprehensive genomic analyses for identifying patient-specific, targetable alterations, and (ii) the need to combine genomic analyses with functional assays, such as tumour-derived slice cultures.