Tie2 antagonist antibodies

Details Tie2 antagonist antibodies Tie2 antagonist antibodies

1999-09-27

2002-04-23

Huff, Sheela (Department: 1642)

Chemistry: natural resins or derivatives; peptides or proteins;

Proteins, i.e., more than 100 amino acid residues

Blood proteins or globulins, e.g., proteoglycans, platelet...

C530S387100, C530S387300, C530S388850, C425S326100

Reexamination Certificate

active

06376653

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to antagonist monoclonal antibodies (mAb) that bind to the Tie2 receptor and to the use of such antibodies for therapeutic purposes.
BACKGROUND OF THE INVENTION
Chronic proliferative diseases are often accompanied by profound angiogenesis, which can contribute to or maintain an inflammatory and/or proliferative state, or which leads to tissue destruction through the invasive proliferation of blood vessels. (Folkman, EXS 79:1-8, 1997; Folkman, Nature Medicine 1:27-31, 1995; Folkman and Shing, J. Biol. Chem. 267:16931, 1992).
Angiogenesis or neovascularisation is the process of development of new or replacement blood vessels. It is a necessary and normal process by which the vasculature is established in the embryo. Angiogenesis does not occur, in general, in most normal adult tissues, exceptions being sites of ovulation, menses and wound healing.
Many diseases, however, are characterized by persistent and unregulated angiogenesis. For instance, in arthritis, new capillary blood vessels invade the joint and destroy cartilage (Colville-Nash and Scott, Ann. Rheum. Dis., 51, 919,1992). In diabetes (and in many different eye diseases), new vessels invade the macula or retina or other ocular structures, and may cause blindness (Brooks et al., Cell, 79, 1157, 1994). The process of atherosclerosis has been linked to angiogenesis (Kahlon et al., Can. J. Cardiol. 8, 60, 1992). Tumor growth and metastasis have been found to be angiogenesis-dependent (Folkman, Cancer Biol, 3, 65, 1992; Denekamp, Br. J. Rad. 66, 181, 1993; Fidler and Ellis, Cell, 79, 185, 1994).
The recognition of the involvement of angiogenesis in major diseases has been accompanied by research to identify and develop angiogenesis inhibitors. Angiogenesis occurs in many stages and inhibitors are generally classified in response to discrete targets in the angiogenesis cascade, such as activation of endothelial cells by an angiogenic signal; synthesis and release of degradative enzymes; endothelial cell migration; proliferation of endothelial cells; and formation of capillary tubules. Literature reports indicate that inhibitors of angiogenesis, working by diverse mechanisms, are beneficial in diseases such as cancer and metastasis (O'Reilly et al., Cell, 79, 315, 1994; Ingber et al., Nature, 348, 555, 1990), ocular diseases (Friedlander et al., Science, 270, 1500, 1995), arthritis (Peacock et al., J. Exp. Med. 175, 1135, 1992; Peacock et al., Cell. Immun. 160, 178, 1995) and hemangioma (Taraboletti et al., J. Natl. Cancer Inst. 87, 293, 1995).
In recent years, it has become clear that while angiogenesis is a complex, multicellular phenomena, specific ligands and their receptors play a key role. In particular, a combination of studies suggest that the Tie2 receptor and its ligand are important in angiogenesis.
Tie2 receptor has been located in endothelial cells of all forming blood vessels and in the endocardium of mouse embryos (Korhonen et al., Blood 80:2548-2555, 1992). Selective patterns of expression in endothelial cells during embryonic development has also been demonstrated (Schlaeger et al., Development 121:1089-1098, 1995).
In adult tissues, Tie mRNA cannot be observed in skin, except at sites of active wound healing where the proliferating capillaries in the granulation tissue contain abundant Tie mRNA (Korhonen et al., Blood 80:2548-2555, 1992). Further, Tie receptor is expressed in the vascular endothelium of metastasizing melanomas (Kaipainen et al., Cancer Res. 54:6571-6577, 1994). While Tie receptor expression is down-regulated in the established vasculature, it is up-regulated in angiogenesis that occurs in the ovary during ovulation, in wounds and in tumor (breast, melanoma and renal cell carcinoma) vasculature, consistent with prevailing views that angiogenesis in the adult borrows from embryonic angiogenic mechanisms.
Homozygous mice with a Tie2 knockout, or carrying a transgene encoding a “dominant-negative” Tie2 receptor, confirmed that the Tie2 receptor is critical for embryonic development (Dumont et al., Genes Dev. 8:1897-1909, 1994; Sato et al., Nature 376:70-74, 1995). Embryonic death in these mice occurred due to vascular insufficiency and there were dramatically reduced numbers of endothelial cells. Vasculogenesis—that is the differentiation of endothelial cells and the in situ formation of vessels—appeared relatively normal in mice lacking Tie2. The subsequent sprouting and remodeling resulting in formation of vessel branches (angiogenesis) was drastically reduced in the Tie2 mutant mice embryos. This lack of sprouting and angiogenesis resulted in substantial growth retardation, particularly of the brain, neural tube and heart, resulting in lack of viability. These results exemplify the critical importance of Tie2 in angiogenesis. This is significant, as angiogenesis is regulated by a number of growth factors. Interestingly, Flk1 (VEGF receptor) knockout mice exhibit embryo lethal defects in vasculogenesis, that occur earlier than those of Tie2 disruption. Disruption of the Tie1 receptor yields a much different, and later, defective phenotype; the mouse embryo dies late in development due to hemorrhage resulting from defective integrity of an otherwise well-formed vasculature. Taken together, these studies suggest that the VEGF/Flk1 and Tie systems operate in sequential fashion, with Tie2 having a critical role in angiogenesis.
Recently, two ligands for the Tie2 receptor have been reported. Angiopoietin-1 binds and induces the tyrosine phosphorylation of Tie2 and its expression in vivo is in close proximity with developing blood vessels (Davis et al., Cell 87:1161-1169,1996). Mice engineered to lack Angiopoietin-1 display angiogenic deficits reminiscent of those previously seen in mice lacking Tie2 receptors, demonstrating that Angiopoietin-1 is a primary physiologic ligand for Tie2 and that Tie2 has critical in vivo angiogenic actions (Suri et al., Cell 87:1171-1180, 1996). Angiopoietin-2 was identified by homology screening and shown to be a naturally occurring antagonist for Tie2 receptors. Transgenic overexpression of Angiopoietin-2 disrupts blood vessel formation in the mouse embryo (Maisonpierre et al., Science 277:55-60, 1997). Together, these results support a role for Tie2 receptors in angiogenesis.
The Tie1 and Tie2 receptors are single-transmembrane, tyrosine kinase receptors (Tie stands for Tyosine kinase receptors with immunoglobulin and EGF homology domains). They are the only receptor tyrosine kinases, other than those receptors for VEGF, that are largely restricted to endothelial cells in their expression. Both have been cloned and reported by several groups (Dumont et al., Oncogene 8:1293-1301, 1993; Partanen et al., Mol. Cell Biol. 12:1698-1707, 1992; Sato et al., Proc. Natl. Acad. Sci. USA 90:9355-9358, 1993).
The Tie receptors are proteins of approximately 125 kDa, with a single putative transmembrane region. The extracellular domain of these receptors is uniquely divided into three regions that have a pattern of cysteine expression found in EGF-like domains; two regions that have some weak homology to and structural characteristics of immunoglobulin-like domains; and three regions with homology to the fibronectin III repeat structure. The intracellular portion of Tie2 is most closely related (~40% identity) to the kinase domains of FGF-R1, PDGF-R and c-kit. The intracellular portions of Tie2 contain all of the features of tyrosine kinases, including a GXGXXG ATP binding site consensus sequence and typical tyrosine kinase motifs (i.e., HRDLAARN and DFGL).
Based upon the importance of Tie2 receptors in angiogenesis, inhibition of Tie2 activity is predicted to interrupt angiogenesis, providing disease-specific therapeutic effects. Recently, Lin et al. (J. Clin. Invest. 100:2072-2078, 1997) has shown that exogenously administered soluble Tie2 receptor inhibited angiogenesis and cancer growth in animal models. Clearly, there is a need to develop high affinity, potent antagonist antibodies to the Tie2 receptor which will have suffi

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