IL4 and neoplasm: Previous studies have demonstrated that enhancing CAR-T-cell efficacy through the addition of interleukin-7 receptor (IL7R) signaling, by incorporating IL-7 secretion, expression of constitutively activated IL7R, or inverted cytokine receptor IL-4 to IL-7 can be an effective strategy for enhancing CAR-T cell function and restoring antitumor activity in the immunosuppressive tumor microenvironment [13–16, 35, 49].