IDO1 and melanoma: For example, we reported a canine clinical trial in metastatic sarcoma and melanoma testing a novel immunotherapy combination including local radiotherapy (RT), intratumoral CpG oligodeoxynucleotides (immune stimulatory toll-like receptor 9 agonists), and systemic administration of indolamine-2,3 dioxygenase (IDO) blockade with 1-Methyl-Tryptophan (to circumvent immune suppressive pathways) [98].