CD8A and melanoma: In several tumor models, it induced the proliferation of CD8 + T cells and B cells after CD40 engagement.37 A phase II clinical trial in which IL‐21 is used to treat melanoma, renal carcinoma and non‐Hodgkin lymphoma is ongoing.38 Based on their in vivo functions, it is a promising strategy to use these cytokines in combination with CAR‐T cells.