IDO1 and metastatic neoplasm: For example, the expression of LAG-3 and VTCN-1 is indicative of lung cancer metastasis; TIM-3, CD47, and OX-40L are predictive of the prognosis of metastatic tumors such as prostate cancer, NHL, and melanoma; CD276 is associated with the survival of patients with renal cell carcinoma; and IDO-1 may be associated with the therapeutic effect of nivolumab.