<b>Background and Purpose:</b> Although trastuzumab has shown considerable activity in the treatment of HER2-positive breast and gastric cancers, a significant proportion of patients do not respond to trastuzumab.
<b>Introduction</b>: CT-P6 (trastuzumab-pkrb, Herzuma) is a trastuzumab biosimilar approved for use in HER2 positive breast cancer and HER2 positive gastric cancer.
Gastric cancer (GC) has also been slow to benefit from biomarker discovery and development and the successful utilisation of targeted therapies, with the exception of trastuzumab in HER2 positive cancers.
HER-2/neu-overexpressing tumors detected by immunohistochemistry amounted to 19% of primary gastric cancers and HLA-A2-positive patients with gastric cancer were 31% of primary gastric-cancer cases.
HER2 has been identified as a potential candidate for targeted therapy in gastric cancers displaying HER2 gene amplification and protein overexpression.
HER-2/neu (c-erbB-2, HER2) gene amplification and protein overexpression have been associated with poor prognosis in several solid tumors, including breast and gastric cancer.
Human epidermal growth factor receptor 2 (HER2, alias ERBB2)-targeted therapy in breast and gastric cancers depends on the reliable assessment of HER2 protein expression and (in equivocal cases) the quantitative evaluation of HER2 gene amplification.
HER2 overexpression is observed in ∼6-35% of all gastric cancers, while co-amplification of topoisomerase IIα occurs in ∼32-90% of all cancers with HER2 amplification.
HER2 status in gastric cancer: a comparison of two novel in situ hybridization methods (IQ FISH and dual color SISH) and two immunohistochemistry methods (A0485 and HercepTest™).
HER2 testing in breast and gastric cancer is critical not only as a prognostic tool but also as a predictive marker for response to the humanized monoclonal antibody trastuzumab.