A third-generation erythropoietic beta molecule created by integrating a large polymer chain into the molecule, thus increasing the molecular weight to twice that of epoetin at approximately 60 kDa; the methoxy-polyethylene glycol polymer chain is integrated via amide bonds between the N-terminal amino group or the e-amino group of lysine (predominantly lysine-52 or lysine-45), using a single succinimidyl butanoic acid linker; an erythropoiesis-stimulating agent for the treatment of anemia.