IFNA2 and hairy cell leukemia: The IL-2 has been approved for advanced renal cell carcinoma (RCC) therapy (37) and metastatic melanoma (38), while IFN-α has been approved for the treatment of hairy cell leukemia (HCL) (39), non-Hodgkin lymphoma (NHL) (40), melanoma (41), and AIDS-related Kaposi's sarcoma (42).