Approximately, 50% of NSCLC cases in Asia [26] and around 10% in Caucasian European population [27] carry activating mutations on the tyrosine kinase domain of EGFR. Tyrosine kinase inhibitors (TKI) are the cornerstone of treatment for NSCLC, but resistances frequently occur, which have been attributed to secondary mutations in EGFR, being the T790M base substitution the most widely reported. The gene discussed is EGFR; the disease is non-small cell lung carcinoma.