EGFR and non-small cell lung carcinoma: However, since osimertinib is considered standard first-line therapy for NSCLC patients with EGFR mutations (66), some patients on osimertinib would inevitably develop new mutations (detected in ctDNA), including EGFR C797S mutation, MET amplification, HER2 exon 20 insertions, BRAFV600E mutation, PIK3CA mutation, and EGFR amplification and thus be resistant to the drug (67–71).