Notably, it is reported that PD-L1-positive TILs are associated with increased levels of activated TILs [28], reflecting an active anti-tumor immunity that, despite being balanced by the PD-1/PD-L1/PD-L2 pathway, is sufficient to generate an inflamed and immunosuppressive tumor microenvironment, capable of damaging tissues, thus leading to ulcer formation and contributing to tumor progression. Here, PDCD1 is linked to neoplasm.