PDCD1 and cancer: Immunotherapy has revolutionized cancer treatment, particularly with the advent of immune checkpoint inhibitors (ICIs) that target programmed cell death protein 1 (PD-1), programmed death-ligand 1 (PD-L1), and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) (Shiravand et al., 2022; Cai et al., 2024; Zhu et al., 2024; Cheng et al., 2024).