IHC revealed HHLA2 staining in tumor, stromal, and immune cells, and the median score of HHLA2 expression in the tumor compartment was significantly higher than in the stromal compartment (31.5% compared with 7.35%), indicating stronger HHLA2 expression in the tumors (p < 0.0001) [42]. This evidence concerns the gene HHLA2 and neoplasm.