The present invention is concerned with a protein oligomer comprising at least two NC-1 monomers of human collagen 18 or fragments of an NC-1 monomer of human collagen 18 for use in the treatment or prevention of an angiogenesis-related disease. The invention further pertains to a fusion protein comprising a NC-1 monomer of human collagen 18 and a Fc domain of an immunoglobulin. The invention also relates to a fusion protein comprising: a) an endostatin peptide or endostatin-derived peptide and b) the RGD motif and/or PHSRN motif of Fibronectin. The invention further relates to a kit comprising the protein oligomer or fusion proteins of the invention.