Tumor growth and metastasis impacts a large number of people each year. In fact, it is estimated that well over 600,000 new cases of cancer will be diagnosed in the coming year in the United States alone (Varner, J. A., Brooks, P. C., and Cheresh, D. A. (1995) Cell Adh. Commun. 3, 367-374). Numerous studies have suggested that the growth of all solid tumors requires new blood vessel growth for continued expansion of the tumors beyond a minimal size (Varner et al. 1995; Blood, C. H. and Zetter, B. R. (1990) Biochim. Biophys. Acta. 1032:89-118; Weidner, N. et al. (1992) J. Natl. Cancer Inst. 84:1875-1887; Weidner, N. et al. (1991). N. Engl. J. Med. 324:1-7; Brooks, P. C. et al. (1995) J. Clin. Invest. 96:1815-1822; Brooks, P. C. et al. (1994) Cell 79:1157-1164; Brooks, P. C. et al. (1996). Cell 85, 683-693; Brooks, P. C. et al. (1998) Cell 92:391-400. A wide variety of other human diseases also are characterized by unregulated blood vessel development, including ocular diseases such as macular degeneration and diabetic retinopathy. In addition, numerous inflammatory diseases also are associated with uncontrolled neovascularization such as arthritis and psoriasis (Varner et al. 1995).
New blood vessels develop from pre-existing vessels by a physiological process known as angiogenesis (Varner et al. 1995; Blood and Zetter 1990; Weidner et al. 1992). This complex process requires cooperation of a variety of molecules including growth factors, cell adhesion receptors, matrix degrading enzymes and extracellular matrix components (Varner et al. 1995; Blood and Zetter 1990; Weidner et al. 1992). Thus, therapies designed to block angiogenesis may affect the growth of solid tumors. In fact, clear evidence has been provided that blocking tumor neovascularization can inhibit tumor growth in various animal models, and human clinical data is beginning to support this contention as well (Varner, J. A., Brooks, P. C., and Cheresh, D. A. (1995) Cell Adh. Commun. 3, 367-374).
It has also been proposed that inhibition of angiogenesis can be effected by (1) inhibition of release of “angiogenic molecules” such as βFGF (fibroblast growth factor), (2) neutralization of angiogenic molecules, such as by use of anti-βFGF antibodies, and (3) inhibition of endothelial cell response to angiogenic stimuli. This latter strategy has received attention, and Folkman et al., Cancer Biology, 3:89-96 (1992), have described several endothelial cell response inhibitors, including collagenase inhibitors, basement membrane turnover inhibitors, angiostatic steroids, fungal-derived angiogenesis inhibitors, platelet factor 4, thrombospondin, arthritis drugs such as D-penicillamine and gold thiomalate, vitamin D3 analogs, alpha-interferon, and the like that might be used to inhibit angiogenesis. For additional proposed inhibitors of angiogenesis, see Blood and Zetter 1990; Moses et al. (1990) Science 248:1408-1410; Ingber et al. (1988) Lab. Invest., 59:44-51; and U.S. Pat. Nos. 5,092,885, 5,112,946, 5,192,744, and 5,202,352.
To block angiogenesis, many investigators have also focused on growth factors and cytokines that initiate angiogenesis (Varner et al. 1995; Blood and Zetter 1990; Weidner et al. 1992; Weidner et al. 1991; Brooks et al. 1995; Brooks et al. 1994; Brooks et al. 1997). However, there is a large number of distinct growth factors and cytokines which have the capacity to stimulate angiogenesis. The therapeutic benefit of blocking a single cytokine may have only limited benefit due to this redundancy. Accordingly, what is needed is other anti-angiogenic targets for inhibiting angiogenesis and proteolysis.