EGFR and non-small cell lung carcinoma: GEF and ERL are first-generation EGFR-TKIs whose therapeutic utility in NSCLC with EGFR harboring the exon 19 deletions or exon 21 (L858R) substitutions is beset by increasing rates of acquired resistance, resulting in shorter progression-free survival (PFS) periods, with median values ranging between 9 to 13 months [42].