CD274 and neoplasm: It is also important to note that gastro-oesophageal adenocarcinoma appears to display both temporal and spatial heterogeneity in terms of TMB and PD-L1 expression before and after chemotherapy.104,105 Maron et al.105 found that the genomic landscape identified by ctDNA next-generation sequencing (NGS) was similar, but not identical, to tumour NGS suggesting that using ctDNA alongside tumour NGS may provide a mechanism to identify early and target intra-patient heterogeneity.