The variability in PD-L1 expression can be influenced by various factors, such as (i) the genetics of the tumor, where some mutations in signaling pathways, such as the PI3K/AKT pathway, can result in increased PD-L1 expression [38]; (ii) the tumor microenvironment, where inflammatory or anti-inflammatory cytokines, such as IFN-γ and IL-10, are potent inducers of PD-L1 expression in cells [39]; and (iii) the interaction of neoplastic cells with the immune system [40]. The gene discussed is IFNG; the disease is neoplasm.