Classification of HER2/neu Status in Gastric Cancer Using a Breast-Cancer Derived Proteome Classifier

HER2-testing in breast and gastric cancers is mandatory for the treatment with trastuzumab We hypothesized that imaging mass spectrometry (IMS) of breast cancers may be useful for generating a classifier that may determine HER2-status in other cancer entities irrespective of primary tumor site A total of 107 breast (n = 48) and gastric (n = 59) cryo tissue samples was analyzed by IMS (HER2 was present in 29 cases) The obtained proteomic profiles were used to create HER2 prediction models using different classification algorithms A breast cancer proteome derived classifier, with HER2 present in 15 cases, correctly predicted HER2-status in gastric cancers with a sensitivity of 65% and a specificity of 92% To create a universal classifier for HER2-status, breast and nonbreast cancer samples were combined, which increased sensitivity to 78% and specificity was 88% Our proof of principle study provides evidence that HER2-status can be identified on a proteomic level across different cancer types suggesting that HER2 overexpression may constitute a unique molecular event independent of the tumor site Furthermore these results indicate that IMS may be useful for the determination of potential drugable targets as it offers a quicker cheaper and more objective analysis than the standard HER2 testing procedures immunohistochemistry and fluorescence in situ hybridization