Response to tyrosine kinase inhibitors in lung adenocarcinoma with the rare epidermal growth factor receptor mutationS768IandG724S: A case report and literature review

Mutations in the epidermal growth factor receptor (EGFR) are drivers of a subset of lung cancers. In recent years, the treatment of non-small cell lung cancer (NSCLC), especially with EGFR inhibitors, has made rapid progress, and the median progression-free survival (PFS) of patients withEGFRgene-sensitive mutations has been significantly prolonged. However, the response effect of some uncommonEGFRmutations to tyrosine kinase inhibitors (TKIs) remains unclear. Here, we present a patient with multipleEGFRmutations that highlights tumor heterogeneity leading to a mixed molecular response to targeted drugs and emphasizes the complexity of EGFR-driven lung cancer. He received chemotherapy and molecular-targeted treatment including icotinib, afatinib, osimertinib and afatinib + osimertinib. In conclusion, patients with lung adenocarcinoma harboring theEGFRS768I and G724S mutations appear less sensitive to icotinib than patients with sensitive EGFR. However, the patient in our report benefited from treatment with afatinib. Here, we hope to provide information for the treatment of rare and compound mutations in patients.