Other novel immune checkpoints include T cell immunoreceptor with immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domain (TIGIT), which is also expressed on activated CD4+ and CD8+ T cells, NK cells, follicular helper T cells, and natural killer T cells and is particularly highly upregulated in tumor-infiltrating Tregs [43]. This evidence concerns the gene CD8A and neoplasm.