Next, we investigated the correlation between PFKFB3 expression and the expression of immune checkpoint markers in pan-cancer, including programmed cell death 1 (PDCD1), programmed cell death 1 ligand 2 (PDCD1LG2), CD274, cytotoxic T-lymphocyte associated protein 4 (CTLA4), hepatitis A virus cellular receptor 2 (HAVCR2), lymphocyte activating 3 (LAG3), and sialic acid binding Ig like lectin 15 (SIGLEC15). The gene discussed is PDCD1; the disease is cancer.