IFNA1 and hairy cell leukemia: Clinical trials were also done examining the effects of IFN treatment on malignant melanoma, multiple myeloma and acute granulocytic leukemia and chronic lymphatic leukemia, all showing some activity as marked by tumor regression or delay in tumor growth but the malignancy with the distinction of being the first licensed application of IFN-α was Hairy Cell Leukemia (HCL) which occurred in 1986.