Figure 2.

MRI scans showing a typical prolonged response to single-agent erlotinib in a patient with progressive GBM. The image in the left panel is consistent with a partially necrotic enhancing mass and surrounding peri-tumoral edema. The image on the right, obtained 16 months after the initiation of erlotinib, reveals a decrease in the mass and associated edema. The patient was on high-dose dexamethasone treatment (to control cerebral edema) at the time of erlotinib treatment initiation and was off all dexamethasone at the time of the follow-up scan.

Abbreviations: GBM, glioblastoma multiforme; MRI, magnetic resonance imaging.