We reviewed the details of infiltrating immune cells in each ICI cluster and found that anti-cancer immune cells, such as CD8 T cells, activated memory CD4 T cells and M1 macrophages, were elevated in ICI cluster A, and the volume of immune-regulating cell-like regulatory T cells (Tregs) was increased in ICI cluster C. These results partially explain the survival variations between the different ICI clusters and highly correlate with previous studies (8, 9, 26). Here, CD4 is linked to cancer.