A rare epidermal growth factor receptor T790M/cis-C797S/L718Q compound mutation in a lung adenocarcinoma patient who did not derive any benefit from combination therapy with afatinib and bevacizumab.

The most common mutations in epidermal growth factor receptor () are exon 19 deletions and exon 21 L858R mutations, both of which respond effectively to tyrosine kinase inhibitors. However, the efficacy of tyrosine kinase inhibitors against rare mutations remains controversial. Many patients eventually develop resistance to tyrosine kinase inhibitors. Here, we encountered the case of a 62-year-old male with lung adenocarcinoma and a history of hypertension, who harbored a rare EGFR L858R/T790M/cis-C797S/L718Q compound mutation and showed resistance to osimertinib. The patient showed a partial response to treatment with a combination of afatinib and bevacizumab lasting 2 months. Although this case did not demonstrate a clear benefit from dual therapy with afatinib and bevacizumab, it provides a valuable therapeutic reference for patients with rare compound mutations and offers insights for future studies.