RESUMEN
Interleukin-21 (IL-21) is a recently discovered cytokine with immunomodulatory activity. It is a new member of the IL-2 family and mainly secreted by the activated CD4~+ T cells. IL-21 can promote proliferation, differentiation and function of T cells, natural killer (NK) cells, and B cells after binding with its receptor, thereby effectively strengthen the innate immunity and acquired immunity. The antitumor activity of IL-21 has been demonstrated in several tumor models. Its phase Ⅱ trials is being carried out in metastatic melanoma and renal cell carcinoma. IL-21 has a broad application prospects in the treatment of malignant tumors. Here, we review the anti-tumor effects of IL-21 and the application foreground of combination of IL-21 with other drugs in future tumor immunotherapy.