Because of the unresponsive hypotension and loss of response to exogenously administered vasopressors, 20-50% of the patients receiving high dose IL-2 therapy require ICU management. These dose-limiting side effects frequently necessitate curtailing the full period of IL-2 dosing in order to reverse the hypotension and prevent subsequent renal dysfunction. Thus, hemodynamic toxicities have limited the usefulness of IL-2 therapy. A course of IL-2 therapy requires long hospitalization and intense patient monitoring during administration. As a consequence, despite favorable long-term response, few sites offer this treatment.