Indoleamine 2,3-dioxygenase: a new target in multidimensional therapy mode for malignant tumors

Indoleamine 2,3-dioxygenase (IDO) is a primary rate-limiting enzyme of extra-hepatic tryptophan metabolism. Through breakdown of tryptophan and producing toxic catabolites in tumor microenvironment, IDO can regulate the antitumor immune function of organism and support evolution of the inflammatory environment in tumor as well as promote tumor angiogenesis. Furthermore, IDO inhibitors have achieved favorable outcomes in the clinical trials for treatment of various malignant tumors, especially combined with radiotherapy, chemotherapy and immunotherapy. Therefore, under the background of multidimensional therapy mode for malignant tumors, the role of IDO in pathogenesis of malignant tumors and the therapeutic value of IDO inhibitors in the treatment of malignant tumors are worth further investigating. DOI:10.3781/j.issn.1000-7431.2016.55.930