Distinct progression and efficacy of first-line osimertinib treatment according to mutation subtypes in metastatic non-small-cell lung cancer harboring EGFR mutations

•Osimertinib has limited efficacy in patients with the L858R point mutations and uncommon mutations compared to those with the 19 deletions mutation.•Osimertinib was less effective against central nervous system metastasis in patients with L858R point mutations compared to those with the 19 deletions mutation.•Concomitant disease progression involving the central nervous system was significantly more common in patients with L858R point mutations.•Concomitant disease progression involving primary lesions was significantly more common in patients with the 19 deletions mutation(p=0.01).