PDCD1 and neoplasm: On the molecular level, the treatment relies on the PD-L1 on the cancer cell membrane binding with PD-1 on the macrophage lymphocytes T and B, thereby preventing the formation of an immunosuppressive tumour microenvironment mediated by suppressive cells such as tumour-associated macrophages (TAMs) and regulatory T lymphocytes (Tregs) [26].