IDO1 and sarcoma: In a pilot study, researchers at the University of California, Davis (UC Davis) have recently used the combination of a Toll-like receptor 9 (TLR9) agonist, indoleamine 2,3-dioxygenase (IDO) inhibitors, and radiation therapy (8 Gy weekly for a total of 32 Gy) on the primary site for canine patients presenting with diffuse oral melanoma (four patients) or sarcoma (one patient).