ICOS and neoplasm: Furthermore, we compared the differences in the common immune checkpoints between subtype 1 and 2 and found the expression of ICOS, CTLA4 and TNFRSF8 were significantly elevated in subtype 1.It is well known that a significant mechanism of tumor cells evading immunosurveillance is activation of immune checkpoint pathways, which can suppress antitumor immune response93.