Yang GJ, Li J, Li HS, et al. - Among Chinese advanced non-small cell lung cancer (NSCLC) patients harboring epidermal growth factor receptor (EGFR) exon 20 insertion (ex20 in.) mutations, researchers assessed the real effectiveness of osimertinib. The data of metastatic NSCLC patients with EGFR ex20 in. mutations who were treated with osimertinib 80 mg or 160 mg once daily were used ibn this analysis. This study involved 62 cases with EGFR ex20 in. mutations; D770_N771insSVD and V769_D770insASV (45.1%) was identified as the major insertion variant. Most frequently, concurrent TP53 mutation was detected. Numericaly longer median progression-free survival was noted in patients harboring A763_Y764insFQEA/ D770delinsGY variants vs those with other variants. Overall, it was concluded that a better response to osimertinib might be achieved in the presence of the unique insertion variant A763_Y764insFQEA and D770delinsGY vs other ex20 in. subtypes. Less activity of osimertinib, either 80 mg or 160 mg once daily, was evident in Chinese NSCLC patients harboring diverse EGFR ex20 in. mutations.