Tirosh et al. identified core exhaustion signatures of T cells, including upregulation of coinhibitory (TIGIT) and costimulatory (TNFRSF9/4-1BB and CD27) receptors.172 In line with the findings for NSCLC and breast cancer,134,147 Li et al. noted that dysfunctional CD8+ T cells transitioned from early effector cells.173 Analysis of the TCR in peripheral blood mononuclear cells revealed dysfunctional processes at the tumor site. This evidence concerns the gene TNFRSF9 and breast cancer.