T-cell Senescence in the Tumor Microenvironment.

T-cell senescence occurs in the tumor microenvironment (TME) and influences cancer outcomes as well as the effectiveness of immunotherapies. The TME triggers this T-cell senescence via multiple pathways, including persistent stimulation with tumor-associated antigens, altered metabolic pathways, and activation of chronic inflammatory responses. Senescent T cells exhibit characteristics such as genomic instability, loss of protein homeostasis, metabolic dysregulation, and epigenetic alterations. Direct cross-talk between senescent T cells and other immune cells further exacerbates the immunosuppressive TME. This immune-tumor cell interaction within the TME contributes to impaired tumor antigen recognition and surveillance by T cells. The presence of senescent T cells is often associated with poor prognosis and reduced efficacy of immunotherapies; thus, targeting the tumor-promoting mechanisms of T-cell senescence may provide novel insights into improving tumor immunotherapy and patient outcomes. This review explores the contributors to tumor-derived T-cell senescence, the link between T-cell senescence and tumor prognosis, and the potential for targeting T-cell senescence to enhance tumor immunotherapy.