A third small molecule inhibitor of IDO (INCB024360, Incyte Corp.,Wilmington, DE, USA) has shown in vivo activity and limitation of tumor growth in animal models [93,94], and is being tested as monotherapy for ovarian cancer in a phase II clinical (NCT01685255), further underlining the translational value of IDO antagonists. Here, IDO1 is linked to ovarian carcinoma.