Interestingly, HHLA2 expression was correlated with five immune checkpoint genes in six tumors including DLBC, KIRP, LUAD, LUSC, SARC, and TGCT; was connected with six immune checkpoint genes in three tumors including GBM, KIRC, and THCA; was associated with seven immune checkpoint genes in three tumors including BLCA, BRCA, and LIHC; and was related to seven immune checkpoint genes in SKCM (Figure 10, Supplementary Table, 9). This evidence concerns the gene HHLA2 and glioblastoma.