Some immunotherapy approaches under investigation include vaccine therapy, cytokine therapy, and most recently, immune checkpoint blockade (ICB) therapy, also known as immune checkpoint inhibition (ICI), which targets cell membrane receptors (such as programmed cell death protein 1, PD-1, programmed cell death protein 1 ligand 1, PD-L1, and cytotoxic T lymphocyte antigen 4, CTLA4) expressed on the surface of tumor cells and tumor-infiltrating immune cells, and whose interactions regulate anti-tumor immune responses [6,7,8,9,10]. Here, PDCD1 is linked to neoplasm.