HHLA2 and cancer: We further explored correlations between CMTM6 expression and immune checkpoint-associated genes, including IDO1, LAG3, CTLA4, TNFRSF9, ICOS, CD80, TIGIT, CD70, TNFSF9, ICOSLG, CD86, PDCD1, IDO2, CD276, CD40, HHLA2, CD274, CD27, BTLA, CD28, and HAVCR2 across 33 types of cancer from the TCGA cohort.