IL4 and melanoma: Since IL-10 is an anti-inflammatory cytokine that supports melanoma cell proliferation and inhibits anti-tumor responses, and as production of IL-4 can induce IL-10 secretion [43], the production of these anti-inflammatory cytokines after application of CAR-T cells in the patient could lead to an inhibition of tumor-reactive T cells and prevent effective recognition and lysis of cancer cells and even promote melanoma growth and should therefore be avoided.