Aside from IFN-α and IL-2, other cytokines such as the tumor necrosis factor (TNF), interleukin-12 (IL-12), interleukin-15 (IL-15), interleukin-21 (IL-21), and granulocyte-macrophage colony stimulating factor (GM-CSF) have been undergoing the safety and efficacy evaluation for cancer treatments in multiple clinical trials. This evidence concerns the gene IL21 and cancer.