Which of afatinib and gefitinib/erlotinib is the better EGFR-TKI to be followed by osimertinib?

Background: In epidermal growth factor receptor (EGFR) mutation-positive non-small cell lung cancer (NSCLC), there are various treatment challenges. Most patients develop resistance and relaps within 1-1.5 years after first-line EGFR- tyrosine kinase inhibitor (TKI) treatment [1st- and 2nd- generation (G) TKIs]. Some studies suggest that afatinib may overcome the tumor heterogeneity.