Lymphodepletion has broad benefits, including killing of immunosuppressive regulatory T-cells (Tregs) and myeloid derived suppressor cells (MDSCs), elimination of T-cells with cytokine receptors that function as homeostatic cytokine sinks resulting in increased levels of cytokines like IL-7, IL-15, and IL-21 necessary for in vivo ACT expansion (187), and direct modulation of tumor IDO (indoleamine 2,3-dioxygenase) (188), all of which together beneficially support T-cell persistence and cytotoxic activity (189). The gene discussed is IDO1; the disease is neoplasm.