An overview of osimertinib as a treatment of non-small cell lung cancer (NSCLC): an update.

Introduction: Osimertinib is a third-generation anti-epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), that irreversibly binds to mutant EGFR, specifically to the T790M EGFR mutant non-small cell lung cancer (NSCLC). Since its approval, osimertinib has been tested in multiple scenarios, including the first-line and adjuvant setting of EGFR-mutant disease.Areas covered: The authors summarize the most recent evidence about osimertinib in NSCLC, covering its use as a first-line therapy, its activity on central nervous system metastatic disease, and in elderly patients. Moreover, the authors focus on resistance to this drug and on the therapeutic strategies that may be used to overcome this issue.Expert opinion: Osimertinib is a key player in the treatment ofEGFR mutant NSCLC and will probably be used in earlier clinical settings in the future, giving rise to an emerging variety of resistance mechanisms. These could be potentially overcome in several ways: e.g. as an oligo-progressive disease local therapy, maintaining osimertinib might be a reasonable option; however, for widespread progressive disease, a switch to chemotherapy should be considered. Finally, either liquid biopsy or tissue biopsy might be considered in patients progressing to osimertinib, as they can lead to the identification of potentially targetable resistance mechanisms.