Clinical activity of the tyrosine kinase inhibitor osimertinib in -mutant glioblastoma.

Glioblastoma (GBM) is the most common primary malignant brain tumor in adults and carries a dismal prognosis. The gene is among the most commonly deranged genes in GBM and thus an important therapeutic target. We report the case of a young female with heavily pretreated -mutated GBM, for whom we initiated osimertinib, an oral, third-generation tyrosine kinase inhibitor that irreversibly inhibits EGFR and has significant brain penetration. We then review some of the main challenges in targeting EGFR, including lack of central nervous system penetration with most tyrosine kinase inhibitors, molecular heterogeneity of GBM and the need for enhanced specificity for the mutations relevant in GBM.