Bond oracle HER2 IHC assay for identifying low to intermediate HER2-expressing breast cancer.

e11509 Background: HER2 targeted therapies are effective treatment for breast tumors that overexpress the HER2 protein to a high level (IHC score of 3+) or have amplification of the HER2 gene (HER2/CEP17 >2). However, the majority of breast tumors exhibit low to intermediate expression of HER2 (IHC 1+ and 2+), for which there are limited treatment options. A new cancer vaccine candidate, E75 or nelipepimut-S, offers prevention of reoccurrence in these patients by generating a specific immune response to a HER2 peptide. To date, no companion diagnostic test is validated to differentiate HER2 at these levels of expression. The BOND Oracle HER2 IHC assay (Leica Biosystems) is being validated to reliably identify IHC HER2 1+ and 2+ cases by correlating to independent analytical measures of HER2 expression. Methods: Quantitative PCR was used to determine HER2 DNA copy number and mRNA expression in eight breast cancer cell lines spanning HER2 IHC scores of 0 to 3+ and 45 formalin fixed, paraffin embedded (FFPE)...