Effective Management of EGFR L718Q Mutation Revealed by Liquid Biopsy Using 30 mg Afatinib after Osimertinib Treatment Failure

Sheng-Bin Fan；Chih-Jen Yang

afatinib ； osimertinib ； EGFR L718Q mutation ； non-small cell lung cancer

胸腔醫學

39卷3期（2024 / 09 / 01）

234 - 240

英文

Developing resistance to tyrosine kinase inhibitors poses a significant challenge in treating EGFR-mutated non-small cell lung cancer. One known cause of resistance to osimertinib is the EGFR L718Q mutation, which interferes with the drug's binding efficacy and consequently leads to resistance. We reported an 81-year-old female patient who was diagnosed with adenocarcinoma in the left lower lung, exhibiting distant metastasis and an EGFR L858R mutation. Treatment with osimertinib led to a 25-month progression-free period before the disease progressed with an enlarged liver metastatic tumor. Although the tissue biopsy yielded inadequate samples, a liquid biopsy identified an EGFR L718Q mutation. This discovery led to the patient being switched to 30 mg of afatinib. Remarkable shrinkage in liver metastases was observed after 5 months of afatinib treatment, without notable adverse reactions. Presently, the patient continues to exhibit stable disease status during ongoing follow-up.