The acquired T790M resistance mutation accounts for more than half of the resistance mechanisms identified in NSCLC patients undergoing treatment with first- and second-generation TKIs; therefore, a third-generation treatment, osimertinib, has been developed, which is effective against both EGFR-TKI sensitizing and resistance mutations (T790M) and demonstrated activity in patients who acquired T790M mutations following previous EGFR-TKIs treatment [11]. This evidence concerns the gene EGFR and non-small cell lung carcinoma.