In the immune checkpoint examination, a significant negative correlation existed between PCSK9 and CD163, V-set and Ig domain-containing 4 (VSIG4), and membrane spanning 4-domains A4A (MS4A4A), which encode proteins exhibited on the surface of M2 macrophages, indicating the relationship with M2 macrophage polarization in the tumor microenvironment (41, 42). Here, PCSK9 is linked to neoplasm.