Non-small-cell lung cancer with ERBB2 mutation in non-tyrosine kinase domain benefits from pyrotinib: A case report.

Tyrosine kinase domain (TKD) mutation and particularly exon 20 insertion mutations of erb-b2 receptor tyrosine kinase 2 (ERBB2/HER2) have been extensively reported in non-small cell lung cancer (NSCLC). Nevertheless, the clinical significance of non-TKD mutations remains unknown. To date, no clinical trials have revealed that tyrosine kinase inhibitors are effective in NSCLC patients with non-TKD ERBB2 mutations. Here we report a patient with advanced lung adenocarcinoma harboring non-TKD mutation of ERBB2, S335C, without other actionable alterations benefited from pyrotinib. After first-line treatment of pyrotinib monotherapy, a pan-HER inhibitor, the patient achieved a durable partial response with good tolerance. This case powerfully illustrates that pyrotinib might be a promising first-line treatment strategy for NSCLC patients with non-TKD mutation of ERBB2.