IDO1 and neoplasm: The glycolysis inhibitory effect and apoptosis promoting effect of IDO1 inhibitors (RY103, INCB024360, and 1‐methyl‐l‐tryptophan [1‐MT]) were elucidated in vivo by using orthotopic and tumor‐bearing PC mice, and the therapeutic efficacy of IDO1 and GLUT1 inhibitors combination against PC was evaluated.