In addition to studies in ovarian cancer models, research on potential therapies to eliminate, impede function of, or inhibit MDSC migration to the tumor microenvironment include; PDE5 inhibitors, STAT3 inhibitors, tyrosine-kinase inhibitors, chemotherapies, CCL2 inhibitors, CCR5 antagonists, VEGF inhibitors, IDO inhibitors, COX2 inhibitors, MET inhibitors, ARG-1 inhibitors, NO-releasing aspirin, ATRA, CCR2 inhibitors, anti-CXCR2 antibodies, anti-TNF-related apoptosis-inducing ligand (TRAIL) death receptor R2 antibody, and with use of an anti-CSF1R antibody. The gene discussed is IDO1; the disease is ovarian cancer.