First-in-human phase 1 clinical study of the IL-15 superagonist complex ALT-803 to treat relapse after transplantation

Key Points Single-agent IL-15/IL-15Rα-Fc (ALT-803) therapy was well tolerated and resulted in clinical responses in patients who relapsed post-HCT. First-in-human use of ALT-803 promoted NK and CD8+ T-cell expansion and activation in vivo without stimulating regulatory T cells.