To increase the therapeutic effectiveness and facilitate the use of IL-15 in the immunotherapy of cancer and chronic infection, an IL-15 N72D superagonist/IL-15RαSushi-Fc fusion complex (IL-15SA/IL-15RαSu-Fc; ALT-803) has been developed to address some of the limitations of IL-15–based therapeutics. The gene discussed is IL15; the disease is cancer.