EGFR and non-small cell lung carcinoma: Concerning brain metastases from NSCLC with EGFR (epidermal growth factor receptor) mutations (mainly exon 19 deletions or L858R missense substitutions), occurring in about 10–20% of Caucasians and at least 50% of Asians [105], the efficacy of first-generation inhibitors (gefitinib, erlotinib and icotinib) is limited, because of the limited penetration into CNS of these molecules (1.3% ± 7% for gefitinib and 4.4% ± 3.2% for erlotinib) and the emergence of a second EGFR mutation on exon 20 (T790M) as a resistance mechanism.