PDCD1 and cancer: Prolonging the normalization window also improves the antitumor immune responses by increasing effector T-cell infiltration (54), ECM remodeling (55), and reprogramming of immunosuppressive TME to enhance the therapeutic efficacy of cancer immunotherapies (39, 54), including immune checkpoint blockers (ICBs) by blocking immune checkpoints, programmed death-ligand 1 (PD-L1), and PD-L2 in tumor cells and cytotoxic T-lymphocyte–associated protein 4 (CTLA-4) and programmed cell death protein 1 (PD-1) expressed on T cells (56).