Over time, this persistent stimulation results in the upregulation of inhibitory receptors, leading to the characteristic exhausted T cell phenotype.3 These receptors, such as PD-1, CTLA-4, and TIM-3, limit T cell activity, preventing excessive immune responses that can damage host tissues.68 However, regarding chronic infections and cancers, the regulation of T cell activity by these inhibitory receptors contributes to a state of functional impairment, wherein T cells exhibit diminished proliferation, reduced cytokine production, and an overall decline in effector functions. Here, PDCD1 is linked to cancer.