IDO expression has been detected in biopsies of patients with different malignancies such as esophageal (Von Bergwelt-Baildon et al., 2006), squamous cell carcinoma (McGee-Lawrence et al., 2011), non-small cell lung carcinoma (Sim et al., 2012), and melanoma amongst others (Munn and Mellor, 2007). This evidence concerns the gene IDO1 and melanoma.