Osimertinib treatment response in a patient with lung adenocarcinoma harboring two rare EGFR mutations: A case report

Epidermal growth factor receptor (EGFR) mutations have emerged as the most well-studied oncogenic alterations in advanced non-small cell lung cancer. The presence of single common or rare EGFR mutations and extra complex EGFR mutations correlates with the response sensitivity to EGFR tyrosine kinase inhibitors. Therefore, given the lack of evidence for the emergence of rare EGFR mutation types, the pathogenic mechanisms of uncommon EGFR mutations and the optimal treatment strategies remain to be explored further. The present study describes the case of a patient diagnosed with lung adenocarcinoma (LUAD) carrying two rare EGFR exon 18 indel/G719C and exon 19 L747S mutations, in which persistent lesion shrinkage was exhibited within 16 months of osimertinib treatment. Given the paucity of clinical trials for the treatment of LUAD harboring complex EGER mutations, the present detailed case description may provide clinicians with effective clinical experience in treating patients.