Despite the lack of definitive evidence, an anti-tumor role of IL-15 has been suggested by results obtained from a phase I single-arm multicenter study, which reported increased activation and expansion of both CD8+ T cells and NK cells when ALT-803, an IL-15 superagonist complex, was administered to patients who relapsed more than 60 days post-allo-HSCT [43]. Here, IL15 is linked to neoplasm.