EGFR (epidermal growth factor receptor) mutations are among the most common actionable alterations in non-small cell lung cancer (NSCLC), particularly in adenocarcinoma histology and in non-smokers, women, and East Asian populations.
Common EGFR mutations include exon 19 deletions, exon 21 L858R point mutations, and exon 20 insertions. The first three are generally sensitive to EGFR tyrosine kinase inhibitors (TKIs) such as erlotinib, gefitinib, afatinib, osimertinib, and others.
Osimertinib, a third-generation EGFR TKI, is now a preferred first-line treatment for EGFR-mutant NSCLC because it is effective against both classic mutations and the T790M resistance mutation, and it crosses the blood-brain barrier.