IFNA1 and hairy cell leukemia: Reports of the clinical significance of the development of neutralizing antibodies in patients with Hairy Cell Leukemia, Chronic Myelogenous Leukemia and Renal Cell Carcinoma as well as carcinoid tumors, show that 63% of those who developed neutralizing antibodies to IFN-α experienced relapse or develop resistance to the interferon used for initial treatment [131].