Briefly, melanoma cells can evade immune detection through a reduction of the expression of immunogenic tumor antigens, a reduction of the histocompatibility complex class I (MHC I), the alteration of the antigen process, the recruitment of the immunosuppressive cells such as T reg and suppressor cells derived from myeloid cells, and the reduction of immunosuppressive molecules such as TGFß, Vascular-Endothelial Growth Factor (VEGF), adenosine, or Indoleamin 2,3-dioxygenase enzyme (IDO) [32, 44–46]. The gene discussed is IDO1; the disease is melanoma.