IL2 and neoplasm: In addition, the upregulation of membrane-tethered IL-15/IL-21 co-expression in engineered T cells [253], the selective expression of homodimeric IL-21R replaced by CD34 extracellular structural domain [254], and the fusion protein of IL-2 with IL-2Rα with selective affinity [255], can all effectively reduce the exhaustion of therapeutic T cells and enhance their anti-tumor function in different preclinical murine solid tumor models.