Comparing the Sensitivity of HER2 Epitope Detection of HercepTest mAb pharmDx (Dako Omnis, GE001) and Ventana PATHWAY Anti-HER-2/neu (4B5) Using IHC Calibrators.

Accurate assessment of HER2 expression levels is paramount for determining eligibility for targeted therapies. HER2 immunohistochemistry provides a semiquantitative measurement of HER2 protein overexpression. Historically, little focus has been on the lower end of the HER2 expression range. The advent of novel therapeutic molecules that require fewer membrane epitopes to be effective has prompted a reevaluation of the current immunohistochemistry testing protocols, with special emphasis on the detection limit. Here, we have used Boston Cell Standards technology to determine the sensitivity of 2 commercially available HER2 immunohistochemistry assays, including a lower limit of detection.