G-CSF conjugates
Polypeptide conjugates with G-CSF activity comprising a polypeptide having at least one introduced lysine residue and at least one removed lysine residue compared to the sequence of human G-CSF, and which are conjugated to 2-6 polyethylene glycol moieties. The conjugates have a low in vitro bioactivity, a long in vivo half-life, a reduced receptor-mediated clearance, and provide a more rapid stimulation of production of white blood cells and neutrophils than non-conjugated recombinant human G-CSF.
1. A method for increasing the level of neutrophils in a patient suffering from an insufficient neutrophil level, comprising administering to the patient a therapeutically effective amount of a composition comprising
a polypeptide conjugate exhibiting G-CSF cell proliferation activity, comprising a polypeptide comprising an amino acid sequence consisting of SEQ ID NO:1 with the substitutions K16R, K34R, K40R, T105K, and S159K, and at least two polyethylene glycol moieties each covalently attached to an attachment group of the polypeptide, wherein the attachment group is the N-terminal amino group or a lysine residue, and a pharmaceutically acceptable carrier of excipient.
2. The method of claim 1 , wherein the polypeptide further comprises a methionine at the N-terminus.
3. The method of claim 1 , wherein the polyethylene glycol moieties each have a molecular weight of about 5 kilodaltons.
4. The method of claim 1 , wherein the polypeptide conjugate comprises 3-6 polyethylene glycol moieties.
5. The method of claim 1 , wherein the polyethylene glycol moieties are attached to the N-terminal amino group and to one or more lysine residues.
6. The method of claim 5 , wherein the one or more lysine residues are selected from Lys23, Lys105, and Lys159.
7. The method of claim 6 , wherein the polyethylene glycol moieties each have a molecular weight of about 5 kilodaltons.
8. The method of claim 1 , wherein the insufficient neutrophil level is due to chemotherapy or radiation therapy.