PDCD1LG2 and neoplasm: To visualize the co-expression of PD-L1/PD-L2 of all patients for whom all parameters were available (n = 48), a heat map was created based on copy number and mRNA/protein expression in the tumor and groups could be divided into four clusters: 1) patients with high expression of both PD-L1 and PD-L2; 2) patients with intermediate PD-L1-expressing samples and without or low PD-L2 expression; 3) patients without or with low PD-L1 expression but with high PD-L2 expression; and 4) patients without or with low expression of both PD-L1 and PD-L2 (Figure 3E).