Nevertheless, IFN-α and IL-2 were clinically approved for the treatment of different malignancies such as hairy cell leukemia, follicular non-Hodgkin lymphoma, melanoma, and Kaposi's sarcoma (IFN-α) or renal cell carcinoma and melanoma (IL-2) (180, 181). This evidence concerns the gene IL2 and hairy cell leukemia.