A protein oligomer comprising at least two NC-1 monomers of human collagen 18 for use in treating or preventing an angiogenesis-related disease, wherein the NC-1 monomer of human collagen 18 comprises an oligomerization domain, a hinge region and an endostatin domain or fragments of said endostatin domain comprising the zinc binding site of endostatin and, optionally a recombinant protease cleavage site within the hinge region, wherein the oligomerization domain comprises a non-triple helical trimerization domain of human collagen 18 and an Fc domain of an immunoglobulin or a non-triple helical trimerization domain of human collagen 18 and an artificial oligomerization domain which comprises a single mutation at position 7 of the endostatin domain in which glutamine is replaced by cysteine, and wherein the angiogenesis-related disease is selected from the group consisting of angiogenesis-dependent cancer including solid tumors, melanomas, tumor metastases, blood born tumors such as leukemias, benign tumors such as hemangiomas, acoustic neuromas, neurofibromas, trachomas, pyogenic granulomas; rheumatoid arthritis; psoriasis; ocular angiogenic diseases such as diabetic retinopathy, retinopathy of prematurity, macular degeneration, corneal graft rejection, neovascular glaucoma, retrolental fibroplasias, rubeosis; Osler-Webber syndrome; myocardial angiogenesis; plaque neovascularization; telangiectasia; hemophiliac joints; angiofibroma; wound granulation; diseases of excessive or abnormal stimulation of endothelial cells such as intestinal adhesions, atherosclerosis, scleroderma, hypertrophic scars (keloids); cat scratch disease (Rochele minalia quintosa) and ulcers (Helicobacter pylori). wherein the NC-1 monomer of human collagen 18 comprises an oligomerization domain, a hinge region and an endostatin domain or fragments of said endostatin domain comprising the zinc binding site of endostatin and, optionally a recombinant protease cleavage site within the hinge region, wherein the oligomerization domain comprises a non-triple helical trimerization domain of human collagen 18 and an Fc domain of an immunoglobulin or a non-triple helical trimerization domain of human collagen 18 and an artificial oligomerization domain which comprises a single mutation at position 7 of the endostatin domain in which glutamine is replaced by cysteine, and wherein the angiogenesis-related disease is selected from the group consisting of angiogenesis-dependent cancer including solid tumors, melanomas, tumor metastases, blood born tumors such as leukemias, benign tumors such as hemangiomas, acoustic neuromas, neurofibromas, trachomas, pyogenic granulomas; rheumatoid arthritis; psoriasis; ocular angiogenic diseases such as diabetic retinopathy, retinopathy of prematurity, macular degeneration, corneal graft rejection, neovascular glaucoma, retrolental fibroplasias, rubeosis; Osler-Webber syndrome; myocardial angiogenesis; plaque neovascularization; telangiectasia; hemophiliac joints; angiofibroma; wound granulation; diseases of excessive or abnormal stimulation of endothelial cells such as intestinal adhesions, atherosclerosis, scleroderma, hypertrophic scars (keloids); cat scratch disease (Rochele minalia quintosa) and ulcers (Helicobacter pylori).