IDO1 and neoplasm: There are preclinical evidences that IDO1 inhibition can disrupt acquired immune tolerance, enhance tumor-specific killing (Jinushi et al., 2014), and significantly increase the immune response induced by various chemotherapeutic and immunotherapeutic agents (Zamanakou et al., 2007; Katz et al., 2008; Prendergast, 2008; Liu et al., 2010).