HER2 mutation status in Japanese HER2-negative breast cancer patients.

Yumi Endo, Yu Dong, Nobuyasu Yoshimoto, Tomoko Asano, Yukari Hato, Hiroko Yamashita, Shinya Sato, Satoru Takahashi, Yoshitaka Fujii, Tatsuya Toyama

Index: Jpn. J. Clin. Oncol. 44(7) , 619-23, (2014)

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Abstract

Human epidermal growth factor receptor 2 (HER2) gene amplification is a major therapeutic target in breast cancer, and has been introduced as a predictive biomarker to identify patients who may benefit from therapy with anti-human epidermal growth factor receptor 2 agents. Human epidermal growth factor receptor 2 somatic mutations have been reported in patients without human epidermal growth factor receptor 2 gene amplification. Since these are activating mutations, these patients may also benefit from human epidermal growth factor receptor 2-targeted drugs.In this study, we searched for human epidermal growth factor receptor 2 mutations in a group of 286 Japanese breast cancer patients with human epidermal growth factor receptor 2-negative tumors. The activating mutations of human epidermal growth factor receptor 2 identified were analyzed by direct Sanger sequencing of two major areas: the extracellular domain at 309-310 and the kinase domain between 755 and 781.Two tumors were found to have a human epidermal growth factor receptor 2 somatic mutation; one with I767M mutation and another with D769Y. No mutation was observed in the extracellular domain. One of these patients with human epidermal growth factor receptor 2 mutation recurred early with liver metastasis.Better knowledge of human epidermal growth factor receptor 2 mutation status will help us to choose personalized molecular targeted therapy for use in human epidermal growth factor receptor 2-negative Japanese breast cancer patients.© The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.