Profiling of circulating tumor cells isolated from 105 metastatic gastric cancer patients revealed HER2 overexpression/activation for potential use in clinical setting.

Abstract

10535 Background: Gastric cancer (GCA) is the second leading cause of cancer mortality in the world. Survival of patients with advanced GCA treated with chemotherapy remains low. New targeted therapies are urgently needed. There is mounting evidence of the role of HER2 overexpression in patients with GCA, and it has been highly correlated to poor outcomes with more aggressive disease. The ability to accurately determine HER2 status by testing circulating tumor cells (CTCs) may improve patient treatment by allowing ongoing assessment of HER2 status during treatment and/or identifying additional patients who could potentially benefit from HER2- targeted therapy. Methods: The Collaborative Enzyme Enhanced Reactive-immunoassay (CEER) was utilized to determine the expression and activation (phosphorylation) levels of HER2 in CTCs isolated from blood specimens obtained from 105 metastatic GCA patients. Results: Utilizing the CEER platform, the levels of HER2 expression and phosphorylation were determined for CTCs isolated from metastatic GCA patients. Evaluable CTCs were found in 33% (35/105) of enrolled patients. Out of 35 patients, 7 patients (20%) have high HER2 over expression, 6 patients (17%) have moderate HER2 expression and 11 patients (31%) have HER2 activation (phospho positive) with no HER2 over-expression. Conclusions: When CTCs were present, the CEER assay identified varying levels of HER2 involvements in 68% of metastatic GCA patients. HER2 positive CTCs could serve as a prognostic and/or predictive marker in patients with advanced GCA and CTC-HER2 profile shifts can be utilized to monitor the treatment efficacy.