The responsive tumour harboured EGFR amplification and was EGFRvIII-negative, whereas the progressive tumour was EGFRvIII-positive.223 Although there are several possible explanations for this observation, it is clear that small molecule EGFR inhibitors have limited efficacy in glioblastoma patients due to the complex nature of EGFR activity in glioblastoma tumours. This evidence concerns the gene EGFR and neoplasm.