EGFR and glioblastoma: The combination of the two drugs was well tolerated by patients and resulted in improved survival.45 However, treatment with Erlotinib alone was not effective in patients with recurrent GBM.46 Gefitinib (ZD1839/Iressa) is also an EGFR tyrosine kinase inhibitor that has been shown to radiosensitize U251 GBM cells in vitro.