IDO1 inhibition has been demonstrated to increase conversion of Foxp3+ Tregs to Th17-like cells in tumor-draining lymph nodes in mice bearing B16-F10 tumors.42 However, when treating mice with epacadostat, we did not detect any significant differences in effector T-cells or T-regulatory cells in the lymph node, and instead the major effects of epacadostat therapy on immune cell phenotypes was observed within the tumor microenvironment. This evidence concerns the gene IDO1 and neoplasm.