<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 testing in gastric carcinoma is a new field, opening several opportunities: for patients with gastric cancer, this is a new promising therapeutic option; for pathologists, strengthening our role in therapy selection and emphasizing our duty of providing accurate and reproducible HER2 testing results; for all interested in understanding the biology of gastric and GEJ cancer and in discovering new possible molecular therapy targets.
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 status in gastric carcinoma is comparable to previous studies with good concordance between IHC and SISH; all IHC 2+ and unusual patterns should be assessed with ISH studies; heterogeneity of tumour HER2 overexpression/amplification is common with possible implications for HER2 testing; and HER2 overexpression appears sufficiently specific to be considered a potential diagnostic biomarker of dysplasia.
HER2 positivity found in 7.3 % of GCs was significantly associated with older age, male gender, intestinal histology, upper third in location, higher lymph node stage (p < .002), and advanced AJCC stage (p = .033).
HER2 testing in paired biopsy and excision specimens of gastric cancer: the reliability of the scoring system and the clinicopathological factors relevant to discordance.
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.