Yu et al. further demonstrated in a mouse model that the disruption of the STAT3–NF-κB–IDO1 axis using a small-molecule inhibitor of STAT3 led to a significant downregulation of IDO1 expression in tumor-suppressing myeloid cells and a reduction in the size of BrCa tumors [34]. The gene discussed is STAT3; the disease is invasive breast carcinoma.