Upon exit from the LN, activated T-cells expressing PD-1 can also be tolerized by PD-L1 expressed on major histocompatibility complex (MHC)-presenting lymphatic endothelial cells (LECs) in efferent lymph vessels and LNs [12,13,14], as well as on tumor, immune, and stromal cells in the TME. Here, PDCD1 is linked to neoplasm.