CD4+ naive T cells (cluster 0 and cluster 2) at the core of the tumor express more immune checkpoint molecules, such as CTLA4, which has been used in clinical practice, and LAG3, HAVCR2, and TNFRSF9/CD137, which are currently undergoing clinical trials (Figure 3C) than those at other locations. Here, HAVCR2 is linked to neoplasm.