Overview of Tumor Immunotherapy based on Indoleamine 2,3 Dioxygenase Inhibitors

Tumor immunotherapy is one of the most attractive fields and direction for scientific researchers due to its promising clinical efficacy. While there are still many biomedical obstacles hindering the efficacy of this treatment. Indoleamine 2,3 dioxygenase (IDO) is a key suppressive factor in the tumor microenvironment. Therefore, Inhibition of IDO is strongly effective in some preclinical researches and some IDO inhibitors are in clinical research now. Moreover, IDO-based nano-drug delivery system in anticancer therapy is playing important role. The tumor microenvironment and current research progress of IDO inhibitors and nano-drug delivery systems in tumor immunotherapy are illustrated in this review.