Denileukin diftitox is a recombinant fusion protein of human interleukin-2 (IL-2) attached to diphtheria toxin fragments A and B that is used as an antineoplastic agent to treat cutaneous T cell lymphomas that express IL-2 receptors. High doses of denileukin diftitox can cause mild-to-moderate elevations in serum enzymes and bilirubin, but rarely result in clinically significant acute liver injury.