Medical College of Georgia Research Institute, Inc.

Augusta University Research Institute, Inc.

Georgia Regents Research Institute, Inc.

Medical College of Georgia

Georgia Health Sciences University

Andrew L Mellor

David Munn

Jeffrey Roberts Lee

The present invention provides improved treatment methods by the administration of both an inhibitor of indoleamine-2,3-dioxygenase in addition to the administration of an additional therapeutic agent.

Use of inhibitors of indoleamine-2,3-dioxygenase in combination with other therapeutic modalities

The present invention discloses pharmaceutical compositions containing 1-methyl-D-tryptophan and its utility to enhance rejection of tumor or virus-infected cells or to delay the progression of tumor growth. The present invention shows that pharmaceutical compositions containing 1-methyl-D-tryptophan enhance the efficacy of alternative antitumor or antiviral treatments such as chemotherapy, vaccination or cytokine therapy.

Pharmaceutical compositions containing 1-methyl-D-tryptophan

A mechanism of macrophage-induced T cell suppression is the selective elimination of tryptophan and/or increase in one or more tryptophan metabolites within the local macrophage microenvironment. Studies demonstrate that expression of IDO can serve as a marker of suppression of T cell activation, and may play a significant role in allogeneic pregnancy and therefore other types of transplantation, and that inhibitors of IDO can be used to activate T cells and therefore enhance T cell activation when the T cells are suppressed by pregnancy, malignancy or a virus such as HIV. Inhibiting tryptophan degradation (and thereby increasing tryptophan concentration while decreasing tryptophan metabolite concentration), or supplementing tryptophan concentration, can therefore be used in addition to, or in place of, inhibitors of IDO. Similarly, increasing tryptophan degradation (thereby, decreasing tryptophan concentration and increasing tryptophan metabolite concentration), for example, by increasing IDO concentration or IDO activity, can suppress T cells. Although described particularly with reference to IDO regulation, one can instead manipulate local tryptophan concentrations, and/or modulate the activity of the high affinity tryptophan transporter, and/or administer other tryptophan degrading enzymes. Regulation can be further manipulated using cytokines such as macrophage colony stimulating factor, interferon gamma, alone or in combination with antigen or other cytokines.

Regulation of T cell-mediated immunity by tryptophan

The present invention is based on the discovery antigen-presenting cells (APCs) may be generated to have predetermined levels of expression of the intracellular enzyme, indoleamine 2,3-dioxygenase (IDO). Because expression of high levels of IDO is correlated with a reduced ability to stimulate T cell responses and an enhanced ability to induce immunologic tolerance, APCs having high levels of IDO may be used to increase tolerance in the immune system, as for example in transplant therapy or treatment of autoimmune disorders. Also disclosed are kits for assessing the relative risk of tumor progression in a subject. For example, disclosed are kits for assessing the relative risk of tumor progression in a subject and having reagents for detection of the enzyme indoleamine 2,3-dioxygenase (IDO) in a sample of tissue from a tumor or tumor draining lymph node from a subject, wherein the reagents are packaged in at least one individual container. The kits may include reagents for detection of cell surface or immunohistochemical markers associated with high IDO expression by APCs such as DO, CD123, CD11c or CCR6.

Kits to assess the risk of tumor progression

The present invention provides methods and compositions to reduce immune tolerance at specific sites. In one aspect, the present invention comprises methods and compositions to reduce tumorigenicity. In an embodiment, the present invention reduces recruitment of tolerance-inducing antigen presenting cells (APCs) or their precursors to a tumor and/or tumor draining lymph node by decreasing binding of at least one tumor-associated ligand to a chemokine receptor present on the tolerance-inducing APCs or APC precursors. In an embodiment, the chemokine receptor is CCR6 and the tumor-associated ligand is mip-3&#x3b1;. In another aspect, the present invention comprises methods and compositions to reduce immune tolerance to a virus. In an embodiment, the virus is HIV. The present invention further provides for the development of CCR6 antibodies and antagonists as therapeutic agents to prevent or reduce immune tolerance.

Chemokine receptor antagonists as therapeutic agents

A mechanism of macrophage-induced T cell suppression is the selective elimination of tryptophan and/or increase in one or more tryptophan metabolites within the local macrophage microenvironment Studies demonstrate that expression of IDO can serve as a marker of suppression of T cell activation, and may play a significant role in allogeneic pregnancy and therefore other types of transplantation, and that inhibitors of IDO can be used to activate T cells and therefore enhance T cell activation when the T cells are suppressed by pregnancy, malignancy or a virus such as HIV. Inhibiting tryptophan degradation (and thereby increasing tryptophan concentration while decreasing tryptophan metabolite concentration), or supplementing tryptophan concentration, can therefore be used in addition to, or in place of, inhibitors of IDO. Similarly, increasing tryptophan degradation (thereby , decreasing tryptophan concentration and increasing tryptophan metabolite concentration), for example, by increasing IDO concentration or IDO activity, can suppress T cells. Although described particularly with reference to IDO regulation, one can instead manipulate local tryptophan concentrations, and/or modulate the activity of the high affinity tryptophan transporter, and/or administer other tryptophan degrading enzymes. Regulation can be further manipulated using cytokines such as macrophage colony stimulating factor, interferon gamma, alone or in combination with antigen or other cytokines.

A mechanism of macrophage-induced T cell suppression is the selective elimination of tryptophan and/or increase in one or more tryptophan metabolites within the local macrophage microenvironment Studies demonstrate that expression of IDO can serve as a marker of suppression of T cell activation, and may play a significant role in allogeneic pregnancy and therefore other types of transplantation, and that inhibitors of IDO can be used to activate T cells and therefore enhance T cell activation when the T cells are suppressed by pregnancy, malignancy or a virus such as HIV. Inhibiting tryptophan degradation (and thereby increasing tryptophan concentration while decreasing tryptophan metabolite concentration), or supplementing tryptophan concentration, can therefore be used in addition to, or in place of, inhibitors of IDO. Similarly, increasing tryptophan degradation (thereby, decreasing tryptophan concentration and increasing tryptophan metabolite concentration), for example, by increasing IDO concentration or IDO activity, can suppress T cells. Although described particularly with reference to IDO regulation, one can instead manipulate local tryptophan concentrations, and/or modulate the activity of the high affinity tryptophan transporter, and/or administer other tryptophan degrading enzymes. Regulation can be further manipulated using cytokines such as macrophage colony stimulating factor, interferon gamma, alone or in combination with antigen or other cytokines.

A high affinity and extremely selective tryptophan transport system present in human monocyte-derived macrophages is disclosed. Human monocyte-derived macrophages include two distinct transporters, a high affinity (Km&equals;290&plusmn;160 nM) transporter that is highly specific for tryptophan and a low affinity (Km&equals;27&plusmn;4 &mgr;M) transporter that is less specific for tryptophan, consistent with the known system L. The tryptophan transport system is predominantly (86%) sodium-independent. The high-affinity system is very specific for tryptophan and shows no transport of any other essential amino acids in the tryptophan transport concentration range. This high-affinity system is expressed at very low levels in fresh monocytes, but undergoes a 10-30 fold induction during macrophage differentiation. This high affinity, tryptophan-selective transport system allows macrophages to take up tryptophan efficiently under conditions of very low substrate concentration, such as can occur at sites of inflammation.

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Martinez, GA, United States of America

Andrew L Mellor