Interleukin-2 receptor-directed therapies: antibody-or cytokine-based targeting molecules.

With the exception of certain hematologic malignancies, the high affinity interleukin-2 (IL-2) receptor is only transiently expressed during the brief antigen-triggered proliferative burst of lymphocytes. Hence, we wondered whether administration of anti-IL-2 receptor (IL-2R) monoclonal antibody (mAb) or chimeric IL-2 toxins would provide a utilitarian way to achieve immunosuppression aimed directly at activated lymphocytes, or whether this approach could be used to treat IL-2R+ leukemia/lymphoma. Studies in preclinical autoimmune and transplant models indicate that this approach can be effective. The results of open, uncontrolled studies provide preliminary evidence that a chimeric IL-2 toxin is well tolerated at doses that may induce improvement in patients with IL-2R+ leukemia/lymphoma, as well as in patients with refractory rheumatoid arthritis or new-onset diabetes mellitus.