Tagrisso 40 mg tablets Tagrisso contains Osimertinib, an irreversible, third-generation Epidermal Growth Factor Receptor (EGFR) tyrosine kinase inhibitor (TKI). It selectively targets both EGFR-tyrosine kinase inhibitor sensitizing mutations (EGFRm, such as Exon 19 deletion and L858R) and the T790M resistance mutation, while exhibiting lower activity against wild-type EGFR. By binding covalently to cysteine residues (C797) within the ATP-binding site of EGFR, it inhibits downstream signal transduction pathways responsible for tumor cell growth and proliferation. It is indicated for the adjuvant treatment of adult patients with early-stage EGFR-mutated non-small cell lung cancer (NSCLC) post-resection, and for the first-line or second-line treatment of patients with locally advanced or metastatic EGFR T790M mutation-positive NSCLC.