m-40403 and Hypotension

Despite increasing use of "targeted therapy," interleukin-2 (IL-2) is unique, because this cytokine can induce long-term remissions in 5% to 7% of patients with metastatic melanoma and renal cancer. Clinical use of IL-2 is limited by severe toxicities, such as hypotension and vascular leak syndrome (VLS). Nitric oxide seems to be involved in the pathogenesis of these toxicities. On the basis of previous studies, we hypothesized that the endothelial nitric oxide synthase (eNOS) is the major source of nitric oxide. Mice with a knockout of the eNOS isoenzyme were treated with IL-2 (800,000 IU twice daily for 5 d). Blood pressure and vascular leak were measured. Inhibitors of superoxide, nitric oxide, and soluble guanylate cyclase were used to probe the mechanism. These experiments showed that IL-2 treatment increased eNOS messenger ribonucleic acid expression and nitric oxide metabolite excretion in eNOS knockout mice. Unlike normal and inducible nitric oxide synthase knockout mice, eNOS knockout mice proved resistant to IL-2-induced hypotension and vascular leak. Although hypotension seems to be mediated by superoxide or peroxynitrite, vascular leak seemed to be mediated by nitric oxide. Inhibition of guanylate cyclase and cyclic guanylate monophosphate formation during IL-2 treatment using methylene blue (MB)-inhibited vascular leak. MB treatment did not interfere with IL-2-induced antitumor mechanisms. Our experiments established that eNOS is a key mediator of IL-2-induced VLS and hypotension. A clinical trial of MB infusion during IL-2 therapy is currently being planned.

Topics: Animals; Blood Pressure; Capillary Leak Syndrome; Carcinoma, Renal Cell; Cyclic GMP; Enzyme Inhibitors; Guanylate Cyclase; Humans; Hypotension; Interleukin-2; Manganese; Melanoma; Methylene Blue; Mice; Mice, Inbred Strains; Mice, Knockout; Nitric Oxide; Nitric Oxide Synthase Type III; omega-N-Methylarginine; Organometallic Compounds; Receptors, Cytoplasmic and Nuclear; RNA, Messenger; Soluble Guanylyl Cyclase; Superoxides

Dose limiting side effects of interleukin-2 (IL-2) include severe hypotension and vascular leak syndrome (VLS). Previous studies have shown that nitric oxide (NO) synthesis is strongly induced after IL-2 treatment of C3H/HeN mice (180,000 IU b.i.d. for 5 d). We employed knockout mice (on C57BL/6 background) to test the role of the inducible NO synthase (iNOS) in mediating IL-2 toxicity. In contrast to C3H/HeN mice, which developed hypotension and VLS after 10 doses of only 180,000 IU IL-2, C57BL/6 mice were far more resistant requiring increased doses of 800,000 IU IL-2 (b.i.d., 5 d) to induce hypotension and VLS. Serum interferon-gamma levels were significantly more elevated by IL-2 treatment in C3H/HeN mice than in C57BL/6, correlating with the severity of hypotension and VLS. Urinary excretion of NO metabolites was markedly reduced in iNOS knockout mice (C57BL/6 iNOS) after IL-2 treatment. A surprising finding was that these mice still developed profound hypotension and VLS. Similar findings were observed after administration of a iNOS specific inhibitor, L-N[6]-(1-iminoethyl)lysine (L-NIL). In contrast, a general NOS inhibitor, N-monomethyl-L-arginine, prevented both hypotension and vascular leak. The superoxide dismutase mimetic, M40403, reversed IL-2-induced hypotension but not VLS in knockout mice. Thus, peroxynitrite-mediated mechanisms are likely responsible for hypotension, whereas NO-induced changes in vascular permeability result in VLS. The iNOS enzyme is not necessary for pathogenesis of IL-2-induced cardiovascular toxicity. These results imply that other NOS isoforms, such as endothelial NOS, may play a major role in the development of IL-2-induced cardiovascular toxicity.

Topics: Animals; Capillary Leak Syndrome; Capillary Permeability; Genetic Predisposition to Disease; Hypotension; Interferon-gamma; Interleukin-2; Lysine; Manganese; Mice; Mice, Inbred C3H; Mice, Inbred C57BL; Mice, Knockout; Nitric Oxide; Nitric Oxide Synthase Type II; omega-N-Methylarginine; Organometallic Compounds

Interleukin-2 (IL-2) is used to treat metastatic renal cell carcinoma and malignant melanoma, but its use is limited by the severe hypotension it produces. We have shown here that M40403, a superoxide dismutase (SOD) mimetic, blocked IL-2-induced hypotension and allowed the dose of IL-2 to be increased in mice. The reversal of IL-2-mediated hypotension was associated with an increase in plasma catecholamines. In addition, M40403 increased lymphokine-activated killer (LAK) cell cytotoxicity in vitro and in vivo, through inhibition of macrophage superoxide production. Treatment of methylcholanthrene-induced (Meth A) ascites tumors with IL-2 and > or =3 mg per kg body weight M40403 induced 50% complete remissions lasting for more than 200 d, which was longer than those of untreated mice (15-d median survival) or mice treated with IL-2 alone (22-d median). Growth of subcutaneous implants of RENCA renal carcinoma was also inhibited by the combination of IL-2 and M40403. These results established that M40403 prevented IL-2 from causing dose-limiting hypotension, while enhancing its anticancer activity.

Topics: Animals; Antineoplastic Agents; Catecholamines; Dose-Response Relationship, Drug; Female; Humans; Hypotension; Interleukin-2; Kidney Neoplasms; Killer Cells, Natural; Lymphocyte Activation; Macrophages; Manganese; Melanoma; Mice; Mice, Inbred C3H; Mice, Inbred C57BL; Molecular Mimicry; Molecular Structure; Organometallic Compounds; Superoxide Dismutase; Survival Rate

A major feature of septic shock is the development of a vascular crisis characterized by nonresponsiveness to sympathetic vasoconstrictor agents and the subsequent irreversible fall in blood pressure. In addition, sepsis, like other inflammatory conditions, results in a large increase in the production of free radicals, including superoxide anions (O(2)) within the body. Here we show that O(2) reacts with catecholamines deactivating them in vitro. Moreover, this deactivation would appear to account for the hyporeactivity to exogenous catecholamines observed in sepsis, because administration of a superoxide dismutase (SOD) mimetic to a rat model of septic shock to remove excess O(2) restored the vasopressor responses to norepinephrine. This treatment with the SOD mimetic also reversed the hypotension in these animals; suggesting that deactivation of endogenous norepinephrine by O(2) contributes significantly to this aspect of the vascular crisis. Indeed, the plasma concentrations of both norepinephrine and epinephrine in septic rats treated with the SOD mimetic were significantly higher than in untreated rats. Interestingly, the plasma concentrations for norepinephrine and epinephrine were inversely related to the plasma concentrations of adrenochromes, the product of the autoxidation of catecholamines initiated by O(2). We propose, therefore, that the use of a SOD mimetic represents a new paradigm for the treatment of septic shock. By removing O(2), exogenous and endogenous catecholamines are protected from autoxidation. As a result, both hyporeactivity and hypotension are reversed, generation of potentially toxic adrenochromes is reduced, and survival rate is improved.

Topics: Adrenochrome; Animals; Blood Pressure; Catecholamines; Disease Models, Animal; Dose-Response Relationship, Drug; Epinephrine; Hypotension; Kinetics; Lipopolysaccharides; Male; Manganese; Norepinephrine; Organometallic Compounds; Rats; Rats, Sprague-Dawley; Shock, Septic; Superoxide Dismutase; Superoxides; Vasoconstriction; Vasoconstrictor Agents