EGFR and glioblastoma: GBM PDOX models suggest osimertinib has limited impact on both 18F-FDG uptake (+ 9.8%–+25.9%) and survival (+ 15.5%; P = .01), which may be explained by insufficient exposure in the brain (Kpuu: 0.30) required to robustly inhibit the EGFR alterations found in GBM.