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. The component variations partially explained the survival variations between different ICI clusters. The gene discussed is CD8A; the disease is cancer.