This critical function in regulating immune responses has positioned inhibitory receptors, such as programmed cell death protein 1 (PD-1), cytotoxic T-lymphocyte antigen-4 (CTLA-4), T cell immunoglobulin and mucin domain containing-3 (TIM-3), lymphocyte activation gene-3 (LAG-3), and others, as promising targets for immunotherapy, particularly in the setting of cancer treatment(Kozlowski et al. 2022; Shi et al. 2018). The gene discussed is PDCD1; the disease is cancer.