Tabriz University of Medical Sciences BioImpacts 2228-5652 9 1 2019 01 10 Indoleamine 2, 3-dioxygenase inhibitors in immunochemotherapy of breast cancer: challenges and opportunities 1 3 10.15171/bi.2019.01 EN Nastran Hashemzadeh Khosro Adibkia https://orcid.org/0000-0002-1053-5557 Jaleh Barar https://orcid.org/0000-0002-0105-919X EDITORIAL 10.15171/bi.2019.01 2018 10 07 2018 10 08 Trafficking of macromolecular immunotherapy agent into the tumor microenvironment (TME) is a challenging issue. In the TME, cancer cells exploit indoleamine 2, 3-dioxygenase (IDO), as a cytosolic enzyme that catalyzes the L-tryptophan (Trp) through the kynurenine (Kyn) pathway, which could negatively regulate the activity of T cells. Thus, Trp/Kyn pathway, can be targeted with novel treatment modalities such as IDO1 inhibitor to benefit patients with aggressive solid tumors.