Even pro-inflammatory interferon-γ (IFN-γ) activity could furnish bidirectional effects with respect to tumor growth by inducing and maintaining cellular anti-tumor immunity, while also downregulating anti-tumor immunity via IFN-γ-mediated stimulation of checkpoint molecule expression [9,10] and upregulation of indoleamine 2,3-dioxygenase-1 (IDO-1) activity [11,12]. Here, IDO1 is linked to neoplasm.