EGFR and non-small cell lung carcinoma: These findings underpinned the development of osimertinib, a third-generation, irreversible, oral EGFR TKI that selectively inhibits both EGFR sensitizing and T790M resistance mutations by covalent binding to the C797 residue in the ATP-binding site of mutant EGFR9,10 In patients with EGFR T790M mutation positive NSCLC who progressed on earlier generation TKIs, osimertinib is associated with superior response rates (71% vs 31%) and improved PFS (median 10.1 vs 4.4 months) compared with platinum-doublet chemotherapy11.