ERBB2 and gastric cancer: The spatial heterogeneity of immunohistochemical biomarkers was also reported for those currently used for GC: HER229, –31 and PD-L1.32,33 Since HER2-targeted therapy34 and anti-PD-1/PD-L135,36 are recommended for patients with unresectable, advanced gastroesophageal cancer, biopsies are often the only available tissue, and therefore studies have assessed the concordance with the paired resections.