IDO1 and neoplasm: A preclinical study investigating the effect of the IDO inhibitor (IDOi) epacadostat in combination with Ad-CEA, N-803, OX40 agonist, and GITR agonist demonstrated antitumor efficacy in a MC38-CEA murine tumor model that was associated with an expansion of splenic and tumor infiltrating CD8+ T cells (51).