Large panel genomic profiling using CancerPlex to reveal candidates for HER2 targeted therapies in colorectal cancer.

e13125Background: Human epidermal growth receptor type 2 (HER2) overexpression/amplification is associated with the efficacy of HER2 targeted therapies in breast and gastric cancers, where candidates for its targeted therapies are selected by immunohistochemistry (IHC) and/or fluorescence in situ hybridization (FISH) testing. However, the HER2 status in colorectal cancer (CRC) has not been fully investigated to date. CancerPlex is a comprehensive next-generation sequencing-based test that evaluates 400-plus genes for mutations and copy number changes, including HER2. In the present study, we aimed to clarify the association between HER2 status and HER2 gene alteration detected with CancerPlex in CRC. Methods: This retrospective study included 100 patients with Stage I-IV CRC, who were evaluated HER2 status and HER2 gene alteration. IHC for HER2 was classified as 4 grades according to the immunoreactivity. The patients with IHC2+ were further tested with FISH. IHC3+/IHC2+ and FISH positive patients were de...