Koopman T, et al. - Given that treatment with anti-HER2-therapy could be useful for subjects with HER2-positive endometrial and ovarian clear cell carcinoma (CCC), the researchers analyzed HER2 overexpression by immunohistochemistry (IHC) utilizing three different antibodies, including concordance with amplification by in situ hybridization (ISH). Using SP3, 4B5 and HercepTest antibodies, IHC was performed and was scored by two independent observers. They found that there was a considerable difference in HER2 overexpression by different IHC antibodies and marked discordance with ISH in ovarian and endometrial CCC. For determining HER2 status in CCC, no single antibody can be considered conclusive. As per data, the lack of predictive value of different HER2 testing methods could be explained.