CD274 and neoplasm: While many of the studies in Table 1 displayed inter-model heterogeneity in PD-L1 expression, they also showed intra-tumoral spatial heterogeneity across the entire tumor volumes in PET imaging (Figures 1A,B) (12, 21, 27, 29), and recent progress in computational approaches will be helpful to understand this complex heterogeneity of PD-L1 (37).