The effect of afatinib and radiotherapy on a patient with lung adenocarcinoma with a rare EGFR extracellular domain M277E mutation and high PD-L1 expression.

In non-small cell lung cancer (NSCLC), about 15% of epidermal growth factor receptor (EGFR) mutations are rare. Herein, we report a 39-year-old male with stage IV NSCLC with a rare EGFR M277E mutation and high PD-L1 expression. The patient first underwent gamma-knife treatment for brain metastasis; then, he was started on 40 mg afatinib daily in combination with two cycles of chemotherapy. The clinical effect was stable disease (SD), so the patient underwent intensity-modulated radiation therapy guided by cone beam computed tomography on the lesion in the lower lobe of the right lung. A combination therapy with afatinib and chemotherapy was employed as the first-line therapy. A palliative radiotherapy to the primary pulmonary tumor was added, resulting in a significant response based on the next computerized tomography (CT) scan. To date, this is the first presented case of NSCLC with EGFR p.M277E mutation and its corresponding clinical outcome to combination therapies.