Extracellular Domain Mutation of ErbB2 Status in Japanese Lung Cancer Patients

Purpose: The erbB pathway involves a family of tyrosine kinases and has contributed to resistance or sensitivity for chemotherapy in many tumor types. Somatic mutations of the erbB family receptor gene at kinase domain were found in lung cancer patients. However, the incidence of extracellular domain mutation of erbB2 in Japanese patients has been rarely described. We report on the incidence of these mutations and clinical factors associated with these mutations. Material and Methods: We have investigated extracellular domain mutations of erbB2 status in non-small cell lung cancer (NSCLC) patients by reverse transcript polymerase chain reaction (RT-PCR) and direct sequencing. The study included 210 surgically removed EGFR or ALK gene wild type lung cancer cases from Nagoya City University Hospital. Results: One G309E erbB2 mutation case was found from squamous cell carcinoma. Within adenocarcinoma, no erbB2 mutation was found in extracellular domain. We have previously detected six erbB2 mutations at kinase domain all in adenocarcinomas. Among the 7 erbB2 gene mutation cases, one case with kinase domain mutation was Hercep test positive. Conclusion: The extracellular domain mutation of erbB2 was rare in Japanese population. Although this mutation is rare, its identification could result in more precise treatment of patients.