It is known that, as a membrane-bound molecule, PD-L1 is expressed on the cell surface of many tumor types and the PD-1/PD-L1 pathway is considered to be a critical mechanism for immune escape and tumor progression (Quail and Joyce, 2013; Yu et al., 2016; Kakavand et al., 2017; Kythreotou et al., 2018; Cha et al., 2019). The gene discussed is PDCD1; the disease is neoplasm.