In the FLAURA 3 study comparing osimertinib and first-generation EGFR TKIs, rare EGFR mutation was an exclusion criterion, but in phase 2 Korean study (KCSG-LU15-09), patients with rare mutations showed a better tumor response and progression-free survival with osimertinib treatment, which was confirmed in some small patient studies. Here, EGFR is linked to neoplasm.