IL21 and metastatic colorectal cancer: Although IL-21 enhances the development of colitis-associated colon cancer and leads to inflammation in head and neck squamous cell carcinoma (92, 93), several clinical phase I/II studies (94–96) and preclinical results continue to indicate that IL-21 can stabilize disease and induce stronger anti-tumor activity in many cancers, including B-cell Hodgkin’s lymphoma, melanoma, renal cancer, metastatic colorectal cancer, ovarian cancer and non-small cell lung cancer (97).