Organic compounds -- part of the class 532-570 series – Organic compounds – Carbohydrates or derivatives
Reexamination Certificate
2000-06-16
2002-12-17
Wilson, James O. (Department: 1623)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbohydrates or derivatives
C536S028700, C536S028800
Reexamination Certificate
active
06495677
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of nucleoside compounds and nucleoside analog compounds.
BACKGROUND OF THE INVENTION
A nucleoside comprises two parts: a) a heterocyclic nitrogenous base portion, termed a purine or pyrimidine; and b) a sugar portion. Nucleoside analogs are compounds that are similar in structure and composition to nucleosides, but one or more of the substituents differ from naturally occurring nucleosides.
Ribavirin (1-&bgr;-D-ribofuranosyl-1,2,4-triazole-3-carboxamide) is a nucleoside analog that has demonstrated efficacy in treating viral diseases both as monotherapy (respiratory syncytial virus, Hall, C. B.; McBride, J. T.; Walsh, E. E.; Bell, D. M.; Gala, C. L.; Hildreth, S.; Ten Eyck, L. G.; W. J. Hall. Aerosolized ribavirin treatment of infants with respiratory syncytial viral infection.
N. Engl. J Med
. 1983, 308, 1443-1447), and in combination therapy with interferon-alpha (hepatitis C virus, Reichard, O.; Norkrans, G.; Fryden, A.; Braconier, J-H.; Sonnerborg, A.; Weiland, O. Randomized, double blind, placebo controlled trial of interferon alpha 2B with and without ribavirin for chronic hepatitis
C. Lancet
1998, 351, 83-87). Recently reported studies indicate that the in vivo utility of ribavirin can result not only from direct inhibition of viral replication, but also from its ability to enhance T cell-mediated immunity (Hultgren, C.; Milich, D. R.; Weiland, O.; Sallberg, M. The antiviral compound ribavirin modulates the T helper Type1/Type2 subset balance in hepatitis B and C virus-specific immune responses.
J. Gen. Virol
. 1998, 79, 2381-2391; Ning, Q.; Brown, D.; Parodo, J.; Cattral, M.; Fung, L.; Gorczynski, R.; Cole, E., Fung, L.; Ding, J. W.; Liu, M. F.; Rotstein, O.; Phillips, M. J.; Levy, G. ribavirin inhibits viral-induced macrophage production of tumor necrosis factor, interleukin-1, procoagulant activity fg12 prothronibinase and preserves Th1 cytokine production but inhibits Th2 cytokine response.
J. Immunol
. 1998, 160, 3487-3493; Martin, M. J.; Navas, S.; Quiroga, J. A.; Pardo, M.; Carreno, V. Effects of the ribavirin-interferon alpha combination on cultured peripheral blood mononuclear cells from chronic hepatitis C patients.
Cytokine
1998, 79, 2381-2391. This immunomodulatory effect of ribavirin is demonstrable in vitro by measuring the levels of Type 1 cytokines produced by activated T cells from both humans and mice (Tam, R. C.; Pai, B.; Bard, J.; Lim, C.; Averett, D. R.; Phan, U. T.; Milovanovic, T. ribavirin polarizes human T cell responses towards a Type 1 cytokine profile.
J. Hepatol
. 1999, 30, 376-382), and by other measures. The induction of a Type 1 cytokine bias by ribavirin is functionally significant in vivo in murine systems (Tam, R. C.; Lim, C.; Bard, J.; Pai, B. Contact hypersensitivity responses following ribavirin treatment in viva are influenced by Type 1 cytokine polarization, regulation of IL-10 expression and costimulatory signaling.
J. Immunol
. 1999, 163, 3709-3717).
Mammalian immune systems contain two major classes of lymphocytes: B lymphocytes (B cells), which originate in the bone marrow; and T lymphocytes (T cells) that originate in the thymus. B cells are largely responsible for humoral immunity (i.e., antibody production), while T cells are largely responsible for cell-mediated immunity.
T cells are generally considered to fall into two subclasses, helper T cells and cytotoxic T cells. Helper T cells activate other lymphocytes, including B cells and cytotoxic T cells, and macrophages, by releasing soluble protein mediators called cytokines that are involved in cell-mediated immunity. As used herein, lymphokines are a subset of cytokines.
Helper T cells are also generally considered to fall into two subclasses, Type 1 and Type 2. Type 1 cells produce interleukin 2 (IL-2), tumor necrosis factor (TNF&agr;) and interferon gamma (IFN&ggr;), and are responsible primarily for cell-mediated immunity such as delayed type hypersensitivity and antiviral immunity. In contrast, Type 2 cells produce interleukins, IL4, IL5, IL-6, IL-9, IL-10 and IL-13, and are primarily involved in assisting humoral immune responses such as those seen in response to allergens, e.g. IgE and IgG4 antibody isotype switching (Mosmann, 1989
, Annu Rev Immunol
. 7:145-173).
As used herein, the terms Type 1 and Type 2 “responses” are meant to include the entire range of effects resulting from induction of Type 1 and Type 2 lymphocytes, respectively. Among other things, such responses include variation in production of the corresponding cytokines through transcription, translation, secretion, and possibly other mechanisms, increased proliferation of the corresponding lymphocytes, and other effects associated with increased production of cytokines, including motility effects.
Previous applications (e.g., 09/291903, now U.S. Pat. No. 6,130,326) which is incorporated herein by reference, relates to aspects of our recent discoveries involving the effect of various nucleosides (which are defined herein to include derivatives and analogs of native nucleosides) on selectively modulating lymphocyte responses relative to each other. Among other things, we have shown that either of Type 1 and Type 2 responses can be selectively suppressed while the other is either induced or left relatively unaffected, and either of Type 1 or Type 2 responses can be selectively induced while the other is either suppressed or left relatively unaffected. We have also discovered the surprising fact that some nucleosides effective in selectively modulating Type 1 and Type 2 responses relative to one another tend to have a bimodal effect. Among other things, some nucleosides that tend to generally suppress or induce both Type 1 and Type 2 activity at a relatively higher dose tend to selectively modulate Type 1 and Type 2 relative to each other at relatively lower doses.
Viramidine (1-&bgr;-D-ribofuranosyl-1,2,4-triazole-3-carboxamidine hydrochloride) has been shown active in ten different viruses that are comparable to ribavirin. (J. T. Witkowski, R. K. Robins, G. P. Khare, R. W. Sidwell,
J. Med. Chem
., 16, 935-937, 1973; R. W. Sidwell, J. H. Huffman, D. L. Barnard, D. Y. Pifat,
Antiviral Research
, 10, 193-208, 1988; B. Gabrielsen, M. J. Phelan, L. Barthel-Rosa, C. See, J. W. Huggins, D. F. Kefauver, T. P. Monath, M. A. Ussery, G.
N. Chmurny, E. M. Schubert, K. Upadhya, C. Kwong, D. A. Carter, J. A. Secrist III, J. J. Kirsi, W. M. Shannon, R. W. Sidwell, G. D. Kini, R. K. Robins,
J. Med. Chem
., 35, 3231-3238, 1992). In addition, Viramidine™, like ribavirin, is an inhibitor of IMP dehydrogenase (R. C. Willis, R. K. Robins, J. E. Seegmiller,
Molecular Pharmacology
, 18, 287-295, 1980). Furthermore, preliminary toxicology studies suggest that Viramidine™ is less toxic than ribavirin (D. Y. Pifat, R. W. Sidwell, P. G. Canonico,
Antiviral Research
, 9, 136, 1988). Also, recent studies at our lab (R. Tam, K. Ramasaniy, ICN Pharmaceuticals, Inc., unpublished results,
1999
) revealed that Viramidine™ and ribavirin exhibited similar immunomodulatory properties. These results coupled with low bioavailability and the toxicity associated with ribavirin prompt us not only to develop Viramidine™ for other viral diseases but also to prepare other derivatives of viramidine, including the synthesis of prodrugs of viramidine, and screen them as potential antiviral agents.
Ribavirin and Levovirin™ are similar with respect to structure, except that Levovirin™ is the L-configuration of the compound and has a substantially reduced toxicity. For example, while oral administration of ribavirin in rats at 180 mg/kg over four weeks produced significant hemolytic anemia and leukopenia, Levovirin™ did not produce any observable clinical pathology. Furthermore, it is contemplated that treatment of a viral disease with Levovirin™ is predominantly based on the modulation of the Th1/Th2 balance towards a Th1 dominated response, and not predominantly based an a direct antiviral effect. The term “direct antiviral” effect or activity as used herein refers to a
Lau Johnson
Ramasamy Kanda S.
Wang Guangyi
Crane Lawrence E
Fish Robert D.
Rutan & Tucker LLP
Wilson James O.
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