IFNG and neoplasm: The failed attempts to treat cancer patients with exogenous IFN-γ raised several concerns: the absence of tumor immunogenicity, the lack of IFN-γ-signaling components, the upregulation of IFN-γ signaling inhibitors, the immunosuppressive tumor microenvironment, the lack of effector T cells, or presence of anergic T cells and, in some cases toxicity.