Natural and modified IL-2 for the treatment of cancer and autoimmune diseases.

Interleukin-2 (IL-2) is a pleiotropic cytokine required for both effector lymphocyte proliferation/differentiation and regulatory T cell expansion/survival. Ability to receive IL-2 signals is defined by the affinity to distinct IL-2-receptor-complexes expressed on each subset of cells. While IL-2 targets anti-tumor cytotoxic lymphocytes (CTLs) for the treatment of patients with melanoma or renal cell carcinoma, IL-2 directed at regulatory T (Treg) cells could have potential therapeutic value in several immune-related diseases including chronic graft-versus-host disease (cGVHD), type 1 diabetes (T1D) and systemic lupus erythematosus (SLE). A variety of IL-2 alteration has been made to deliver IL-2 to the proper target, including mutant IL-2, IL-2-fusion proteins and anti-IL-2 antibodies. Experimental and clinical trials using IL-2 are expanding to diverse group of diseases including solid organ transplantation. Although the sustainability and efficiency of IL-2-responding cells in controlling disease activity are still not fully understood, the results of clinical trials will provide a basis of the most effective regimen for each disease.