Peg-modified erythropoietin

Abstract

The present invention provides a polyethylene glycol-conjugated erythropoietin (PEG-conjugated EPO) prepared by PEG conjugation on the lysine residue at position 52 of native erythropoietin (native EPO). In order to achieve more sustained efficacy without losing physiological activities of native EPO, a glycoprotein rich in sugar chains, there has been a need to develop a PEG-conjugated EPO with significantly sustained efficacy by introducing a controlled number of PEG molecules at controlled positions. This PEG-conjugated EPO addresses such a need and provides more sustained efficacy.

1 . A mono-PEG-conjugated EPO, which comprises native human erythropoietin (native EPO) chemically conjugated with polyethylene glycol (PEG).  
     
     
         2 . The mono-PEG-conjugated EPO according to  claim 1 , wherein PEG conjugation occurs on the lysine residue at position  52  of the native EPO.  
     
     
         3 . The mono-PEG-conjugated EPO according to  claim 1  or  2 , wherein the polyethylene glycol (PEG) used for conjugation of the native human erythropoietin (native EPO) has a molecular weight of 5 to 40 kDa and the apparent molecular weight of said mono-PEG-conjugated EPO in an aqueous medium is 100 to 900 kDa per molecule, as measured by gel filtration column chromatography.  
     
     
         4 . A mono-PEG-conjugated EPO composition, which comprises the mono-PEG-conjugated EPO according to any one of  claims 1  to  3 .  
     
     
         5 . A PEG-conjugated EPO composition, which further comprises a PEG-conjugated EPO having PEG molecules attached to at least two amino acid residues in the mono-PEG-conjugated EPO according to any one of  claims 1  to  3  and/or native EPO, wherein the apparent molecular weight of said PEG-conjugated EPO in an aqueous medium is 100 to 900 kDa per molecule, as measured by gel filtration column chromatography.  
     
     
         6 . A sustained-action erythropoietin formulation, which comprises the PEG-conjugated EPO according to any one of  claims 1  to  3  as an active ingredient.  
     
     
         7 . A sustained-action erythropoietin formulation, which comprises the PEG-conjugated EPO composition according to  claim 4  or  5  as an active ingredient.  
     
     
         8 . A method for preparing the PEG-conjugated erythropoietin composition according to  claim 4 , which comprises reacting native EPO with a succinimidyl ester derivative of PEG.