A case of multiple primary lung adenocarcinoma with a CD74‐NRG1 fusion protein and HER2 mutation benefit from combined target therapy

Neuregulin 1 (NRG1) gene fusion is a rare oncogenic driver gene in multiple tumor types, leading to the activation of the epidermal growth factor receptor (ErbB)‐mediated pathway. Therefore, afatinib, a pan‐ErbB family inhibitor, may be a therapeutic candidate for NRG1 fusion‐driven tumors. In this case, we report a multiple primary lung adenocarcinoma patient harboring the CD74‐NRG1 fusion, epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (ERBB2) mutation simultaneously. The patient received afatinib and pyrotinib combination therapy and showed a significant treatment response with a progression‐free survival of 5 months. Our case further supports the use of targeted therapy for NRG1 fusion‐positive non‐small‐cell lung cancer.