PDCD1 and glioma: Specifically, we found that, as IGFBP5 levels increased, the expression of the seven immune checkpoint genes (BTLA, CD274, CTLA4, HAVCR2, LAG3, PDCD1, and PDCD1LG2) were increased and a large positive correlation was observed between IGFBP5 and these immune checkpoints in glioma.