The clinical use of IL-2 is currently limited by development of dose-dependent hypotension (systolic blood pressure (SBP) < 90 mm Hg). The overall outcome is constant across sites with 20-50% of the patients requiring ICU management because of unresponsive hypotension and hyporeactivity (loss of response to vasoconstrictors). Because of the dose-limiting side effects, the duration of IL-2 dosing is frequently curtailed. Thus, hemodynamic toxicities have limited the usefulness of IL-2 therapy. M40403 has prevented both the hypotension and hyporeactivity associated with IL-2 treatment in preclinical studies. This trial will study the safety and efficacy of M40403 in the prevention or reduction of hypotension in patients receiving IL-2 therapy.