Non-small cell lung cancer harboring a rare EGFR L747P mutation showing intrinsic resistance to both gefitinib and osimertinib (AZD9291): A case report.

The most common EGFR mutations in non-small cell lung cancer are exon 19 deletions and exon 21 point mutations, which are both sensitive to EGFR-tyrosine kinase inhibitors. However, rare EGFR mutations do exist and how these mutations respond to tyrosine kinase inhibitors is not well understood. A Chinese woman diagnosed with stage IV lung adenocarcinoma harbored a rare EGFR L747P (2239-2240 TT > CC) mutation, and treatment with gefitinib and osimertinib failed to achieve the desired effect. Herein, possible correlations between gene analysis and the outcomes of subsequent treatment are discussed.