CA2452582C - G-csf conjugates - Google Patents

Abstract

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 lowin 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-conjugates recombinant human G-CSF.

Description

G-CSF CONJUGATES

FIELD OF THE INVENTION

The present invention relates to new polypeptides exhibiting granulocyte colony-stimulating factor (G-CSF) activity, to conjugates between a polypeptide exhibiting G-CSF
activity and a non-polypeptide moiety, to methods for preparing such polypeptides or conju-gates and the use of such polypeptides or conjugates in therapy, in particular for the treatment of neutropenia or leukopenia.
BACKGROUND OF THE INVENTION

The process by which white blood cells grow, divide and differentiate in the bone marrow is called hematopoiesis (Dexter and Spooncer, Ann. Rev. Cell. Biol., 3:423, 1987).
Each of the blood cell types arises from pluripotent stem cells. There are generally three classes of blood cells produced in vivo: red blood cells (erythrocytes), platelets and white blood cells (leukocytes), the majority of the latter being involved in host immune defense. Proliferation and differentiation of hematopoietic precursor cells are regulated by a family of cytokines, in-cluding colony-stimulating factors (CSF's) such as G-CSF and interleukins (Arai et al., Ann.
Rev. Biochem., 59:783-836, 1990). The principal biological effect of G-CSF in vivo is to stimulate the growth and development of certain white blood cells known as neutrophilic granulocytes or neutrophils (Welte et al., PNAS-USA 82:1526-1530, 1985, Souza et al., Sci-ence, 232:61-65, 1986). When released into the blood stream, neutrophilic granulocytes func-tion to fight bacterial and other infection.
The amino acid sequence of human G-CSF (hG-CSF) was reported by Nagata et al.
Nature 319:415-418, 1986. hG-CSF is a monomeric protein that dimerizes the G-CSF receptor by formation of a 2:2 complex of 2 G-CSF molecules and 2 receptors (Horan et al. (1996), Biochemistry 35(15): 4886-96). Aritomi et al. Nature 401:713-717, 1999 have described the X-ray structure of a complex between hG-CSF and the BN-BC domains of the G-CSF
receptor.
3o They identify the following hG-CSF residues as being part of the receptor binding interfaces:
G4, P5, A6, S7, S8, L9, P10, Q11, S12, L15, K16, E19, Q20, L108, D109, D112, T115, T116, Q119, E122, E123, and L124. Expression of rhG-CSF in Escherichia coli, Saccharomyces cerevisiae and mammalian cells has been reported (Souza et al., Science 232:61-65, 1986, Na-gata et al., Nature 319: 415-418, 1986, Robinson and Wittrup, Biotechnol.
Prog. 11:171-177, 1985).
Leukopenia (a reduced level of white blood cells) and neutropenia (a reduced level of neutrophils) are disorders that result in an increased susceptibility to various types of infections. Neutropenia can be chronic, e.g. in patients infected with HIV, or acute, e.g. in can-cer patients undergoing chemotherapy or radiation therapy. For patients with severe neutro-penia, e.g. as a result of chemotherapy, even relatively minor infections can be serious and even life-threatening. Recombinant human G-CSF (rhG-CSF) is generally used for treating various forms of leukopenia/neutropenia. Thus, commercial preparations of rhG-CSF are avail-1o able under the names filgrastim (Gran and Neupogen ), lenograstim (Neutrogin and Granocyte ) and nartograstim (Neu-up ). Gran and Neupogen are non-glycosylated and produced in recombinant E. coli cells. Neutrogin and Granocyte are glycosylated and pro-duced in recombinant CHO cells and Neu-up is non-glycosylated with five amino acids sub-stituted at the N-terminal region of intact rhG-CSF produced in recombinant E.
coli cells.
Various protein-engineered variants of hG-CSF have been reported (e.g. US
5,581,476, US 5,214,132, US 5,362,853, US 4,904,584 and Riedhaar-Olson et al.
Biochemistry 35: 9034-9041, 1996). Modification of hG-CSF and other polypeptides so as to introduce at least one additional carbohydrate chain as compared to the native polypeptide has been sug-gested (US 5,218,092). It is stated that the amino acid sequence of the polypeptide may be modified by amino acid substitution, amino acid deletion or amino acid insertion so as to effect addition of an additional carbohydrate chain. In addition, polymer modifications of native hG-CSF, including attachment of PEG groups, have been reported (Satake-Ishikawa et al., Cell Structure and Function 17:157-160, 1992, US 5,824,778, US 5,824,784, WO
96/11953, WO
95/21629, WO 94/20069, EP 0612846 Al, WO 01/00011).
Bowen et al., Experimental Hematology 27 (1999), 425-432 disclose a study of the relationship between molecule mass and duration of activity of PEG-conjugated G-CSF
mutein. An apparent inverse correlation was suggested between molecular weight of the PEG
moieties conjugated to the protein and in vitro activity, whereas in vivo activities increased with increasing molecular weight. It is speculated that a lower affinity of the conjugates act to increase the half-life, because receptor-mediated endocytosis is an important mechanism regu-lating levels of hematopoietic growth factors.
The commercially available rhG-CSF has a short-term pharmacological effect and must therefore be administered once a day for the duration of the leukopenic state. A

molecule with a longer circulation half-life would decrease the number of administrations nec-essary to alleviate the leukopenia and prevent consequent infections. Another, more significant problem with currently available rG-CSF products is that patients become neutropenic after chemotherapy even after administration of G-CSF. For these patients, it is important to be able to reduce the duration and degree of the neutropenic state as much as possible in order to minimize the risk of serious infections. A further problem is the occurrence of dose-dependent bone pain. Since bone pain is experienced by patients as a significant side effect of treatment with rG-CSF, it would be desirable to provide a rG-CSF product that does not cause bone pain, either by means of a product that inherently does not have this effect or that is effective in a 1 o sufficiently small dose that no bone pain is caused. Thus, there is clearly a need for improved recombinant G-CSF-like molecules.
With respect to the half-life, one way to increase the circulation half-life of a pro-tein is to ensure that clearance of the protein, in particular via renal clearance and receptor-mediated clearance, is reduced. This may be achieved by conjugating the protein to a chemical moiety which is capable of increasing the apparent size, thereby reducing renal clearance and increasing the in vivo half-life. Furthermore, attachment of a chemical moiety to the protein may effectively block proteolytic enzymes from physical contact with the protein, thus pre-venting degradation by non-specific proteolysis. Polyethylene glycol (PEG) is one such chemi-cal moiety that has been used in the preparation of therapeutic protein products. Recently, 2o. G-CSF molecule modified with a single, N-terminally linked 20 kDa PEG
group (NeulastaTM) was approved for sale in the United States. This PEGylated G-CSF molecule has been shown to have an increased half-life compared to non-PEGylated G-CSF and thus may be adminis-tered less frequently than current G-CSF products, but it does not reduce the duration of neu-tropenia significantly compared to non-PEGylated G-CSF. Thus, there is still substantial room for improvement of the known G-CSF molecules.
A need therefore still exists for providing novel molecules exhibiting G-CSF
activity that are useful in the treatment of leukopenia/neutropenia, and which have are improved in terms of e.g. an increased half-life and in particular a reduction in the duration of neutropenia.
The present invention relates to such molecules.

BRIEF DISCLOSURE OF THE INVENTION

The present invention relates to specific conjugates comprising a polypeptide ex-hibiting G-CSF activity and a non-polypeptide moiety, methods for their preparation and their use in medical treatment and in the preparation of pharmaceuticals.
Accordingly, in a first as-pect the invention relates to various specific conjugates comprising a polypeptide exhibiting G-CSF activity and having an amino acid sequence that differs from the known amino acid se-quence of human G-CSF as shown in SEQ ID NO:1 in at least one specified altered amino acid residue comprising an attachment group for a non-polypeptide moiety, and having at least one io non-polypeptide moiety attached to an attachment group of the polypeptide.
These conjugates have, in addition to an increased in vivo half-life, a substantially reduced in vitro bioactivity compared to that of non-conjugated hG-CSF, which surprisingly has been shown to result in a more rapid neutrophil recovery.
In a further aspect the invention relates to polypeptides exhibiting G-CSF
activity and which form part of a conjugate of the invention. The polypeptides of the invention are con-templated to be useful as such for therapeutic, diagnostic or other purposes, but find particular interest as intermediate products for the preparation of a conjugate of the invention.
In a further aspect the invention relates to a polypeptide conjugate comprising a polypeptide exhibiting G-CSF activity, which comprises an amino acid sequence that differs from the amino acid sequence of hG-CSF (with the amino acid sequence shown in SEQ ID
NO: 1) in at least one amino acid residue selected from an introduced or removed amino acid residue comprising an attachment group for a non-polypeptide moiety, and a sufficient number or type of non-polypeptide moieties to provide the conjugate with an increased half-life and/or a more rapid neutrophil recovery compared to known recombinant G-CSF products.
In a particular aspect the invention relates to a polypeptide conjugate exhibiting G-CSF activity, comprising a polypeptide having the substitutions K16R, K34R, K40R, TI 05K, and S159K, and optionally a substitution in position H170, e.g. to R, K or Q, relative to the amino acid sequence of hG-CSF shown in SEQ ID NO:1, or in a corresponding position relative to an amino acid sequence having at least 80% sequence identity with SEQ ID NO: 1, 3o and having 2-6, typically 3-6 polyethylene glycol moieties with a molecular weight of about 1000-10,000 Da attached to one or more attachment groups of the polypeptide.
Where these substitutions are relative to a sequence with at least about 80% sequence identity with SEQ ID

NO: 1, the degree of sequence identity is typically at least about 90% or 95%, such as at least about 96%, 97%, 98% or 99%.
In still further aspects the invention relates to methods for preparing a conjugate of the invention, including nucleotide sequences encoding a polypeptide of the invention, ex-5 pression vectors comprising such a nucleotide sequence, and host cells comprising such a nu-.
cleotide sequence or expression vector.
In final aspects the invention relates to a composition comprising a conjugate or polypeptide of the invention, a method for preparing a pharmaceutical composition, use of a conjugate or composition of the invention as a pharmaceutical, and a method of treating a to mammal with such composition. In particular, the polypeptide, conjugate or composition of the invention may be used to prevent infection in cancer patients undergoing certain types of radia-tion therapy, chemotherapy, and bone marrow transplantations, to mobilize progenitor cells for collection in peripheral blood progenitor cell transplantations, for treatment of severe chronic or relative leukopenia, irrespective of cause, and to support treatment of patients with acute myeloid leukemia. Additionally, the polypeptide, conjugate or composition of the invention may be used for treatment of AIDS or other immunodeficiency diseases as well as bacterial infections.

DETAILED DISCLOSURE OF THE INVENTION
Definitions In the context of the present application and invention the following definitions apply:
The term "conjugate" is intended to indicate a heterogeneous molecule formed by the covalent attachment of one or more polypeptides, typically a single polypeptide, to one or more non-polypeptide moieties, in particular polymer molecules. In addition, the conjugate may be attached to one or more carbohydrate moieties, in particular by means of N- or 0-glycosylation. The term covalent attachment means that the polypeptide and the non-polypeptide moiety are either directly covalently joined to one another, or else are indirectly covalently joined to one another through an intervening moiety or moieties, such as a bridge, spacer, or linkage moiety or moieties. Preferably, the conjugate is soluble at relevant concentrations and conditions, i.e. soluble in physiological fluids such as blood. The term "non-conjugated polypeptide" may be used about the polypeptide part of the conjugate.

The term "polypeptide" may be used interchangeably herein with the term "pro-tein".
The "polymer molecule" is a molecule formed by covalent linkage of two or more monomers, wherein none of the monomers is an amino acid residue, except where the polymer is human albumin or another abundant plasma protein. The term "polymer" may be used inter-changeably with the term "polymer molecule". The term is intended to cover carbohydrate molecules, although, normally, the term is not intended to cover the type of carbohydrate molecule which is attached to the polypeptide by in vivo N- or O-glycosylation (as further de-scribed below), since such molecule is referred to herein as "an oligosaccharide moiety". Ex-i o cept where the number of polymer molecule(s) is expressly indicated every reference to "a polymer", "a polymer molecule", "the polymer" or "the polymer molecule"
contained in a polypeptide of the invention or otherwise used in the present invention shall be a reference to one or more polymer molecule(s).
The term "attachment group" is intended to indicate an amino acid residue group of the polypeptide capable of coupling to the relevant non-polypeptide moiety.
For instance, for polymer conjugation, in particular to PEG, a frequently used attachment group is the E-amino group of lysine or the N-terminal amino group. Other polymer attachment groups in-clude a free carboxylic acid group (e.g. that of the C-terminal amino acid residue or of an as-partic acid or glutamic acid residue), suitably activated carbonyl groups, oxidized carbohydrate moieties and mercapto groups. Useful attachment groups and their matching non-peptide moie-ties are apparent from the table below.

Attachment Amino acid Examples of non- Conjugation Reference group peptide moiety method/-Activated PEG
-NH2 N-terminal, Polymer, e.g. PEG, mPEG-SPA Shearwater Corp.
Lys, His, Arg with amide or imine Tresylated Delgado et al., critical group mPEG reviews in Therapeutic Drug Carrier Systems 9(3,4):249-304 (1992) -COOH C-term, Asp, Polymer, e.g. PEG, mPEG-Hz Shearwater Corp.
Glu with ester or amide group Oligosaccharide moi- In vitro coupling e -SH Cys Polymer, e.g. PEG, PEG- Shearwater Corp.
with disulfide, vinylsulphone Delgado et al., critical maleimide or vinyl PEG-maleimide reviews in Therapeutic sulfone group Drug Carrier Systems 9(3,4):249-304 (1992) Oligosaccharide moi- In vitro coupling ety -OH Ser, Thr, -OH, Oligosaccharide In vivo O-linked Lys moiety glycosylation PEG with ester, ether, carbamate, carbonate -CONH2 Asn as part of Oligosaccharide moi- In vivo N-an N- ety glycosylation glycosylation site Polymer, e.g. PEG
Aromatic Phe, Tyr, Trp Oligosaccharide moi- In vitro coupling residue ety -CONH2 Gln Oligosaccharide moi- In vitro coupling Yan and Wold, Bio-ety chemistry, 1984, Jul 31; 23(16): 3759-65 Aldehyde Oxidized Polymer, e.g. PEG, PEGylation Andresz et al., 1978, Ketone oligo- PEG-hydrazide Makromol. Chem.
saccharide 179:301, WO
92/16555, WO

Guanidino Arg Oligosaccharide moi- In vitro coupling Lundblad and Noyes, ety Chemical Reagents for Protein Modification, CRC Press Inc., Flor-ida, USA
Imidazole His Oligosaccharide moi- In vitro coupling As for guanidine ring ety For in vivo N-glycosylation, the term "attachment group" is used in an unconven-tional way to indicate the amino acid residues constituting an N-glycosylation site (with the sequence N-X'-S/T/C-X", wherein X' is any amino acid residue except proline, X" any amino acid residue which may or may not be identical to X and which preferably is different from proline, N is asparagine, and S/T/C is either serine, threonine or cysteine, preferably serine or threonine, and most preferably threonine). Although the asparagine residue of the N-glycosylation site is where the oligosaccharide moiety is attached during glycosylation, such attachment cannot be achieved unless the other amino acid residues of the N-glycosylation site io are present. Accordingly, when the non-peptide moiety is an oligosaccharide moiety and the conjugation is to be achieved by N-glycosylation, the term "amino acid residue comprising an attachment group for the non-peptide moiety" as used in connection with alterations of the amino acid sequence of the polypeptide of interest is to be understood as meaning that one or more amino acid residues constituting an N-glycosylation site are to be altered in such a man-ner that either a functional N-glycosylation site is introduced into the amino acid sequence or removed from said sequence.
In the present application, amino acid names and atom names (e.g. CA, CB, NZ, N, 0, C, etc.) are used as defined by the Protein DataBank (PDB) (www.pdb.org), which is based on the IUPAC nomenclature (IUPAC Nomenclature and Symbolism for Amino Acids and Peptides (residue names, atom names etc.), Eur. I Biochem., 138, 9-37 (1984) together io with their corrections in Eur. J. Biochem., 152, 1 (1985). The term "amino acid residue" is in-tended to indicate any naturally or non-naturally occurring amino acid residue, in particular an amino acid residue contained in the group consisting of the 20 naturally occurring amino acids, i.e. alanine (Ala or A), cysteine (Cys or C), aspartic acid (Asp or D), glutamic acid (Glu or E), phenylalanine (Phe or F), glycine (Gly or G), histidine (His or H), isoleucine (Ile or I), lysine (Lys or K), leucine (Leu or L), methionine (Met or M), asparagine (Asn or N), proline (Pro or P), glutamine (Gln or Q), arginine (Arg or R), serine (Ser or S), threonine (Thr or T), valine (Val or V), tryptophan (Trp or W), and tyrosine (Tyr or Y) residues.
The terminology used for identifying amino acid positions/substitutions is illus-trated as follows: F 13 indicates position number 13 occupied by a phenylalanine residue in the reference amino acid sequence. F 13K indicates that the phenylalanine residue of position 13 has been substituted with a lysine residue. Unless otherwise indicated, the numbering of amino acid residues made herein is made relative to the amino acid sequence of hG-CSF shown in SEQ ID NO:1. Alternative substitutions are indicated with a "/", e.g. Q67D/E
means an amino acid sequence in which glutamine in position 67 is substituted with either aspartic acid or glu-tamic acid. Multiple substitutions are indicated with a "+", e.g. S53N+G55S/T
means an amino acid sequence which comprises a substitution of the serine residue in position 53 with an as-paragine residue and a substitution of the glycine residue in position 55 with a serine or a threonine residue.
The term "nucleotide sequence" is intended to indicate a consecutive stretch of two or more nucleotide molecules. The nucleotide sequence may be of genomic, cDNA, RNA, semisynthetic or synthetic origin, or any combination thereof.

The term "polymerase chain reaction" or "PCR" refers to the well-known method for amplification of a desired nucleotide sequence in vitro using a thermostable DNA poly-merase.
"Cell", "host cell", "cell line" and "cell culture" are used interchangeably herein and all such terms should be understood to include progeny resulting from growth or culturing of a cell. "Transformation" and "transfection" are used interchangeably to refer to the process of introducing DNA into a cell.
"Operably linked" refers to the covalent joining of two or more nucleotide se-quences, by means of enzymatic ligation or otherwise, in a configuration relative to one an-io other such that the normal function of the sequences can be performed. For example, the nu-cleotide sequence encoding a presequence or secretory leader is operably linked to a nucleotide sequence for a polypeptide if it is expressed as a preprotein that participates in the secretion of the polypeptide: a promoter or enhancer is operably linked to a coding sequence if it affects the transcription of the sequence; a ribosome binding site is operably linked to a coding sequence if it is positioned so as to facilitate translation. Generally, "operably linked" means that the nucleotide sequences being linked are contiguous and, in the case of a secretory leader, con-tiguous and in reading phase. Linking is accomplished by ligation at convenient restriction sites. If such sites do not exist, then synthetic oligonucleotide adaptors or linkers are used, in conjunction with standard recombinant DNA methods.
The term "introduce" refers to introduction of an amino acid residue comprising an attachment group for a non-polypeptide moiety, in particular by substitution of an existing amino acid residue, or alternatively by insertion of an additional amino acid residue. The term "remove" refers to removal of an amino acid residue comprising an attachment group for a non-polypeptide moiety, in particular by substitution of the amino acid residue to be removed by another amino acid residue, or alternatively by deletion (without substitution) of the amino acid residue to be removed.
When substitutions are performed in relation to a parent polypeptide, they are preferably "conservative substitutions", in other words substitutions performed within groups of amino acids with similar characteristics, e.g. small amino acids, acidic amino acids, polar 3o amino acids, basic amino acids, hydrophobic amino acids and aromatic amino acids.
Preferred substitutions in the present invention may in particular be chosen from among the conservative substitution groups listed in the table below.

Conservative substitution groups:

1 Alanine (A) Glycine (G) Serine (S) Threonine (T) 2 Aspartic acid (D) Glutamic acid (E) 3 Asparagine (N) Glutamine (Q) 4 Arginine (R) Histidine (H) Lysine (K) 5 Isoleucine (I) Leucine (L) Methionine (M) Valine (V) 6 Phenylalanine (F) Tyrosine (Y) Tryptophan (W) The term "immunogenicity" as used in connection with a given substance is in-5 tended to indicate the ability of the substance to induce a response from the immune system.
The immune response may be a cell or antibody mediated response (see, e.g., Roitt: Essential Immunology (8th Edition, Blackwell) for further definition of immunogenicity).
Normally, re-duced antibody reactivity will be an indication of reduced immunogenicity. The reduced im-munogenicity may be determined by use of any suitable method known in the art, e.g. in vivo 10 or in vitro.
The term "functional in vivo half-life" is used in its normal meaning, i.e.
the time at which 50% of the biological activity of the polypeptide or conjugate is still present in the body/target organ, or the time at which the activity of the polypeptide or conjugate is 50% of the initial value. As an alternative to determining functional in vivo half-life, "serum half-life"
may be determined, i.e. the time in which 50% of the polypeptide or conjugate molecules cir-culate in the plasma or bloodstream prior to being cleared. Alternative terms to serum half-life include "plasma half-life", "circulating half-life", "serum clearance", "plasma clearance" and "clearance half-life". The polypeptide or conjugate is cleared by the action of one or more of the reticuloendothelial systems (RES), kidney, spleen or liver, by receptor-mediated degrada-tion, or by specific or non-specific proteolysis, in particular by the action of receptor-mediated clearance and renal clearance. Normally, clearance depends on size (relative to the cutoff for glomerular filtration), charge, attached carbohydrate chains, and the presence of cellular recep-tors for the protein. The functionality to be retained is normally selected from proliferative or receptor-binding activity. The functional in vivo half-life and the serum half-life may be deter-mined by any suitable method known in the art as further discussed in the Materials and Meth-ods section below.
The term "increased" as used about the functional in vivo half-life or serum half-life is used to indicate that the relevant half-life of the conjugate or polypeptide is statistically significantly increased relative to that of a reference molecule, such as a non-conjugated hG-CSF (e.g. Neupogen ) as determined under comparable conditions. For instance, the relevant half-life may increased by at least about 25%, such as by at least about 50%, e.g. by at least about 100%, 200%, 500% or 1000%.
The term "renal clearance" is used in its normal meaning to indicate any clear-ance taking place by the kidneys, e.g. by glomerular filtration, tubular excretion or tubular elimination. Renal clearance depends on physical characteristics of the conjugate, including size (diameter), symmetry, shape/rigidity and charge. Reduced renal clearance may be estab-lished by any suitable assay, e.g. an established in vivo assay. Typically, renal clearance is de-co termined by administering a labeled (e.g. radioactive or fluorescent labeled) polypeptide con-jugate to a patient and measuring the label activity in urine collected from the patient. Reduced renal clearance is determined relative to a corresponding reference polypeptide, e.g. the corre-sponding non-conjugated polypeptide, a non-conjugated corresponding wild-type polypeptide or another conjugated polypeptide (such as a conjugated polypeptide not according to the in-is vention), under comparable conditions. Preferably, the renal clearance rate of the conjugate is reduced by at least 50%, preferably by at least 75%, and most preferably by at least 90% com-pared to a relevant reference polypeptide.
Generally, activation of the receptor is coupled to receptor-mediated clearance (RMC) such that binding of a polypeptide to its receptor without activation does not lead to 20 RMC, while activation of the receptor leads to RMC. The clearance is due to internalization of the receptor-bound polypeptide with subsequent lysosomal degradation. Reduced RMC may be achieved by designing the conjugate so as to be able to bind and activate a sufficient number of receptors to obtain optimal in vivo biological response and avoid activation of more receptors than required for obtaining such response. This may be reflected in reduced in vitro bioactivity 25 and/or increased off-rate. In a preferred embodiment, the conjugates of the invention have a substantially reduced in vitro bioactivity compared to that of non-conjugated hG-CSF.
Typically, reduced in vitro bioactivity reflects reduced efficacy/efficiency and/or reduced potency and may be determined by any suitable method for determining any of these properties. For instance, in vitro bioactivity may be determined in a luciferase based assay 30 ("Primary assay 2"; see Materials and Methods). Another method for determining the in vitro bioactivity is to determine the binding affinity of a conjugate of the invention using the cell-based assay described in the Materials and Methods section ("Secondary assay").

It has been found that a relatively low in vitro bioactivity, compared to the activ-ity of hG-CSF (SEQ ID NO:1), is advantageous in terms of both a long plasma half-life and a high degree of stimulation of neutrophils. Surprisingly, it has been found that administration of G-CSF conjugates of the invention having a low in vitro bioactivity results in a faster neutro-phil recovery, i.e. a faster recovery of the neutrophil count to a normal level, than administra-tion of hG-CSF. Since it is critical to be able to reduce the duration of neutropenia as much as possible in patients having a reduced neutrophil level due to e.g.
chemotherapy or radiation therapy, this is an important finding. Thus, in a preferred embodiment, the in vitro bioactivity of a conjugate of the invention is in the range of about 2-30%, preferably about 3-25%, of the io bioactivity of hG-CSF (where the hG-CSF used as the reference polypeptide has SEQ ID
NO:1, optionally with an N-terminal methionine residue; the reference hG-CSF
may in particu-lar be Neupogen , i.e. non-glycosylated Met-hG-CSF) as determined by the luciferase assay described herein, or, alternatively, using the cell-based receptor binding affinity assay ("Secon-dary assay"). The in vitro bioactivity of the conjugate is thus preferably reduced by at least 70%, such as by at least 75%, e.g. by at least 80% or 85%, as compared to the in vitro bioactiv-ity of hG-CSF, determined under comparable conditions. Expressed differently, the conjugate may have an in vitro bioactivity that is as small as about 2%, typically at least about 3%, such as at least about 4% or 5%, of that of the wild-type polypeptide. For instance, the in vitro bio-activity may be in the range of about 4-20% of that of hG-CSF, determined under comparable conditions. In cases where reduced in vitro bioactivity is desired in order to reduce receptor-mediated clearance, it will be clear that sufficient bioactivity to obtain the desired receptor ac-tivation must nevertheless be maintained, which is why the bioactivity should be at least about 2% of that of hG-CSF and preferably slightly higher as explained above.
It has been found that amino acid alterations, in particular substitutions, in the he-lix regions of G-CSF, i.e. in an amino acid residue selected from amino acid position 11-41 (helix A), 71-95 (helix B), 102-125 (helix C), and 145-170 (helix D) (compared to SEQ ID
NO:1), result in a reduced receptor-mediated clearance and thus an increased in vivo half-life when the resulting polypeptides are conjugated to polyethylene glycol. In addition to a longer half-life, it has surprisingly been found that administration of such polypeptide conjugates is 3o able to stimulate production of white blood cells and neutrophils to the same degree as, or even better than, administration of the commercially available G-CSF products Neupogen and NeulastaTM. G-CSF conjugates having a reduced in vitro bioactivity may thus be prepared by altering, typically by substitution, one or more amino acid residues in a helix region of G-CSF, and by conjugating the resulting polypeptide to one or more non-polypeptide moieties such as polyethylene glycol.
Preferably, the off-rate between the polypeptide conjugate and its receptor is in-creased by a magnitude resulting in the polypeptide conjugate being released from its receptor before any substantial internalization of the receptor-ligand complex has taken place. The re-ceptor-polypeptide binding affinity may be determined as described in the Materials and Meth-ods section herein. The off-rate may be determined using the Biacore technology as de-scribed in the Materials and Methods section. The in vitro RMC may be determined by label-ing (e.g. radioactive or fluorescent labeling) the polypeptide conjugate, stimulating cells com-1o prising the receptor for the polypeptide, washing the cells, and measuring label activity. Alter-natively, the conjugate may be exposed to cells expressing the relevant receptor. After an ap-propriate incubation time the supernatant is removed and transferred to a well containing simi-lar cells. The biological response of these cells to the supernatant is determined relative to a non-conjugated polypeptide or another reference polypeptide, and this is a measure of the ex-is tent of the reduced RMC.
Normally, reduced in vitro bioactivity of the conjugate is obtained as a consequence of its modification by a non-polypeptide moiety. However, in order to further reduce in vitro bio-activity or for other reasons it may be of interest to modify the polypeptide part of the conju-gate further. For instance, in one embodiment at least one amino acid residue located at or near 20 a receptor binding site of the polypeptide may be substituted with another amino acid residue as compared to the corresponding wild-type polypeptide so as to obtain reduced in vitro bioac-tivity. The amino acid residue to be introduced by substitution may be any amino acid residue capable of reducing in vitro bioactivity of the conjugate. Conveniently, the introduced amino acid residue comprises an attachment group for the non-polypeptide moiety as defined herein.
25 In particular, when the non-polypeptide moiety is a polymer molecule such as PEG molecule, the amino acid residue to be introduced may be a lysine residue.
The term "exhibiting G-CSF activity" is intended to indicate that the polypeptide or conjugate has one or more of the functions of native G-CSF, in particular hG-CSF with the amino acid sequence shown in SEQ ID NO: 1, including the capability to bind to a G-CSF re-30 ceptor (Fukunaga et al., J. Bio. Chem, 265:14008, 1990). The G-CSF activity is conveniently assayed using the primary assay described in the Materials and Methods section hereinafter.
The polypeptide "exhibiting" G-CSF activity is considered to have such activity when it dis-plays a measurable function, e.g. a measurable proliferative activity or a receptor binding activ-ity (e.g. as determined by the primary assay described in the Materials and Methods section).
The polypeptide exhibiting G-CSF activity may also be termed "G-CSF molecule"
herein for the sake of simplicity, even though such polypeptides are in fact variants of G-CSF.
The term "parent G-CSF" or "parent polypeptide" is intended to indicate the molecule to be modified in accordance with the present invention. The parent G-CSF is nor-mally hG-CSF or a variant thereof. A "variant" is a polypeptide which differs in one or more amino acid residues from a parent polypeptide, normally in 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15 amino acid residues. Examples of rhG-CSF include filgrastim (Gran and Neupo-gen(g), lenograstim (Neutrogin and Granocyte ) and nartograstim (Neu-up ).
Conjugate of the invention As stated above, in a first aspect the invention relates to a conjugate comprising a polypeptide exhibiting G-CSF activity, which comprises an amino acid sequence that differs from the amino acid sequence of SEQ ID NO:1 in at least one amino acid residue selected from specified introduced or removed amino acid residues comprising an attachment group for a non-polypeptide moiety, and at least one non-polypeptide moiety attached to an attachment group of the polypeptide. The amino acid residues to be introduced and/or removed are de-scribed in further detail in the following sections. It will be understood that the conjugate itself also exhibits G-CSF activity.
By removing and/or introducing an amino acid residue comprising an attachment group for the non-polypeptide moiety it is possible to specifically adapt the polypeptide so as to make the molecule more susceptible to conjugation to the non-polypeptide moiety of choice, to optimize the conjugation pattern (e.g. to ensure an optimal distribution of non-polypeptide moieties on the surface of the G-CSF molecule and to ensure that only the attachment groups intended to be conjugated are present in the molecule) and thereby obtain a new conjugate molecule which has G-CSF activity and in addition one or more improved properties as com-pared to G-CSF molecules available today.
While the polypeptide may be of any origin, in particular mammalian origin, it is presently preferred to be of human origin, in particular a variant of a polypeptide having the 3o amino acid sequence of SEQ ID NO:1.
In preferred embodiments of the present invention more than one amino acid residue of the polypeptide with G-CSF activity is altered, e.g. the alteration embraces removal as well as introduction of amino acid residues comprising an attachment group for the non-polypeptide moiety of choice.
In addition to the amino acid alterations disclosed herein aimed at removing and/or introducing attachment sites for the non-polypeptide moiety, it will be understood that 5 the amino acid sequence of the polypeptide of the invention may if desired contain other altera-tions that need not be related to introduction or removal of attachment sites, i.e. other substitu-tions, insertions or deletions. These may, for example, include truncation of the N- and/or C-terminus by one or more amino acid residues, or addition of one or more extra residues at the N- and/or C-terminus, e.g. addition of a methionine residue at the N-terminus.
10 The conjugate of the invention has one or more of the following improved prop-erties as compared to hG-CSF, in particular as compared to rhG-CSF (e.g.
filgrastim, lenogras-tim or nartograstim) or known hG-CSF variants: increased ability to reduce the duration of neutropenia, increased functional in vivo half-life, increased serum half-life, reduced renal clearance, reduced receptor-mediated clearance, reduced side effects such as bone pain, and 15 reduced immunogenicity.
It will be understood that the amino acid residue comprising an attachment group for a non-polypeptide moiety, whether it be removed or introduced, will be selected on the ba-sis of the nature of the non-polypeptide moiety of choice and, in most instances, on the basis of the method by which conjugation between the polypeptide and the non-polypeptide moiety is to be achieved. For instance, when conjugation of polyethylene glycol to a lysine residue is to be achieved, a suitable activated molecule is e.g. mPEG-SPA from Shearwater Corp., oxycar-bonyl-oxy-N-dicarboxyimide-PEG (US 5,122,614), or PEG available from PolyMASC
Phar-maceuticals plc. The first of these will be illustrated further below.
In order to avoid too much disruption of the structure and function of the parent hG-CSF molecule, the total number of amino acid residues to be altered in accordance with the present invention, e.g. as described in the subsequent sections herein, (as compared to the amino acid sequence shown in SEQ ID NO:1) will typically not exceed 15. The exact number of amino acid residues and the type of amino acid residues to be introduced or removed de-pends in particular on the desired nature and degree of conjugation (e.g. the identity of the non-polypeptide moiety, how many non-polypeptide moieties it is desirable or possible to conjugate to the polypeptide, where conjugation is desired or should be avoided, etc.).
Preferably, the polypeptide part of the conjugate of the invention or the polypeptide of the invention comprises an amino acid sequence which differs in 1-15 amino acid residues from the amino acid se-quence shown in SEQ ID NO:1, typically in 2-10 amino acid residues, e.g. in 3-8 amino acid residues, such as 4-6 amino acid residues, from the amino acid sequence shown in SEQ ID
NO:1. Thus, normally the polypeptide part of the conjugate or the polypeptide of the invention comprises an amino acid sequence which differs from the amino acid sequence shown in SEQ
ID NO:1 in 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15 amino acid residues.
The polypeptide part of the conjugate will typically have an amino acid sequence with at least about 80% identity with SEQ ID NO: 1, preferably at least about 90%, such as at least about 95%, e.g. at least about 96%, 97%, 98% or 99% sequence identity with SEQ ID
NO: 1. Amino acid sequence homology/identity is conveniently determined from aligned se-1o quences, using e.g. the ClustalW program, version 1.8, June 1999, using default parameters (Thompson et al., 1994, ClustalW: Improving the sensitivity of progressive multiple sequence alignment through sequence weighting, position-specific gap penalties and weight matrix choice, Nucleic Acids Research, 22: 4673-4680) or from the PFAM families database version 4.0 (http://pfam.wustl.edu/) (Nucleic Acids Res. 1999 Jan 1; 27(1):260-2) by use of GENEDOC
version 2.5 (Nicholas, K.B., Nicholas H.B. Jr., and Deerfield, D.W. II. 1997 GeneDoc: Analy-sis and Visualization of Genetic Variation, EMBNEW.NEWS 4:14; Nicholas, K.B.
and Nicho-las H.B. Jr. 1997 GeneDoc: Analysis and Visualization of Genetic Variation).
In a preferred embodiment one difference between the amino acid sequence of the polypeptide and the amino acid sequence shown in SEQ ID NO:1 is that at least one and often more, e.g. 1-15, amino acid residues comprising an attachment group for the non-polypeptide moiety has been introduced, preferably by substitution, into the amino acid se-quence. Thereby, the polypeptide part is altered in the content of the specific amino acid resi-dues to which the non-polypeptide moiety of choice binds, whereby a more efficient, specific and/or extensive conjugation is achieved. For instance, when the total number of amino acid residues comprising an attachment group for the non-polypeptide of choice is altered to an op-timized level, the clearance of the conjugate is typically significantly reduced, due to the al-tered shape, size and/or charge of the molecule achieved by the conjugation.
Furthermore, when the total number of amino acid residues comprising an attachment group for the non-polypeptide of choice is increased, a greater proportion of the polypeptide molecule is shielded 3o by the non-polypeptide moieties of choice, leading to a lower immune response.
The term "one difference" as used in the present application is intended to allow for additional differences being present. Accordingly, in addition to the specified amino acid difference, other amino acid residues than those specified may be mutated.

In a further preferred embodiment one difference between the amino acid se-quence of the polypeptide and the amino acid sequence shown in SEQ ID NO: 1 is that at least one and preferably more, e.g. 1-15, amino acid residues comprising an attachment group for the non-polypeptide moiety has/have been removed, preferably by substitution, from the amino acid sequence. By removing one or more amino acid residues comprising an attachment group for the non-polypeptide moiety of choice it is possible to avoid conjugation to the non-polypeptide moiety in parts of the polypeptide in which such conjugation is disadvantageous, e.g. in amino acid residues located at or near a functional site of the polypeptide (since conju-gation at such a site may result in inactivation or reduced G-CSF activity of the resulting con-io jugate due to impaired receptor recognition). In the present context the term "functional site" is intended to indicate one or more amino acid residues which is/are essential for or otherwise involved in the function or performance of hG-CSF. Such amino acid residues are a part of the functional site. The functional site may be determined by methods known in the art and is pref-erably identified by analysis of a structure of the polypeptide complexed to a relevant receptor, such as the hG-CSF receptor (See Aritomi et al. Nature 401:713-717, 1999).
The conjugate of the invention will in general comprise a sufficient number and type of non-polypeptide moieties to provide the conjugate with an increased ability to reduce the duration of neutropenia as compared to hG-CSF, e.g. filgrastim, lenograstim or nartogras-tim, and preferably as compared to rhG-CSF comprising a single N-terminally attached 20 kDa PEG moiety. The increased ability to reduce the duration of neutropenia may be determined as described in the Materials and Methods section herein ("Measurement of the in vivo biological activity in rats with chemotherapy-induced neutropenia of conjugated and non-conjugated hG-CSF and variants thereof ').
The conjugate of the invention may comprise at least one non-conjugated, conju-gatable attachment group for the non-polypeptide moiety. In the present context the term "con-jugatable attachment group" is intended to indicate an attachment group that is located in a position of the polypeptide where it is accessible for conjugation, and that but for special pre-cautions is conjugated to the relevant non-polypeptide moiety when subjected to conjugation.
For instance, such attachment group may be part of an amino acid residue involved in or oth-3o erwise essential for the polypeptide to exert its activity. A convenient way to avoid conjugation of an otherwise conjugatable attachment group is to shield the attachment group by means of a helper molecule, e.g. as described in the section entitled "Blocking of the functional site". It will be understood that the number of non-conjugated, conjugatable attachment groups de-pends on the specific G-SCF polypeptide and the location of the conjugatable attachment groups. For instance, the polypeptide conjugate comprises one or two non-conjugated, conju-gatable attachment groups, and at least one, and preferably two or more conjugated attachment groups.
The four helices of G-CSF comprise amino acid residues 11-41 (helix A), 71-95 (helix B), 102-125 (helix C), and 145-170 (helix D) (Zink et al. (1994) Biochemistry 33: 8453-8463). Surprisingly, it has been found that advantageous results may be obtained when non-polypeptide moieties are attached to amino acid residues located in one or more of the helices of G-CSF, even though modification of protein helices, e.g. the helix structures of four-helix io bundle proteins such as G-CSF, is generally considered to be accompanied by a risk of distur-bance of protein function. In one embodiment, the polypeptide conjugate of the invention therefore comprises at least one non-polypeptide moiety attached to an attachment group of an amino acid residue located in one of the four helices, in particular in one or more of the B, C or D helices Conjugate of the invention wherein the non-polypeptide moiety is attached to a lysine residue In general, the polypeptide conjugate may comprise:
i) a polypeptide exhibiting G-CSF activity, comprising an amino acid sequence that differs from the amino acid sequence shown in SEQ ID NO: 1 in at least one substitution selected from the group consisting of T1K, P2K, L3K, G4K, P5K, A6K, S7K, S8K, L9K, P10K, Q1 1K, S12K, F13K, L14K, L15K, E19K, Q20K, V21K, Q25K, G26K, D27K, A29K, A30K, E33K, A37K, T38K, Y39K, L41K, H43K, P44K, E45K, E46K, V48K, L49K, L50K, H52K, S53K, L54K, 156K, P57K, P60K, L61K, S62K, S63K, P65K, S66K, Q67K, A68K, L69K, Q70K, L71K, A72K, G73K, S76K, Q77K, L78K, S80K, F83K, Q86K, G87K, Q90K, E93K, G94K, S96K, P97K, E98K, L99K, G100K, P101K, T102K, D104K, T105K, Q107K, L108K, D109K, A111K, D112K, F113K, T115K, T116K, W118K, Q119K, Q120K, M121K, E122K, E123K, L124K, M126K, A127K, P128K, A129K, L130K, Q131K, P132K, T133K, Q134K, G135K, A136K, M137K, P138K, A139K, A141K, S142K, A143K, F144K, Q145K, S155K, H156K, Q158K, S159K, L161K, E162K, V163K, S164K, Y165K, V167K, L168K, H170K, L171K, 3o A172K, Q173K and P174K, and ii) at least one non-polypeptide moiety attached to a lysine residue of the polypeptide, and op-tionally also the the N-terminal amino acid residue.

hG-CSF contains four lysine residues, of which K16 is located in the receptor-binding domain and the others are located in positions 23, 34 and 40, respectively, all relatively close to the receptor-binding domain. In order to avoid conjugation to one or more of these lysine resi-dues (since this may inactivate or severely reduce the activity of the resulting conjugate) it may s be desirable to remove at least one lysine residue, e.g. two, three or all of these residues. Ac-cordingly, in another, more preferred aspect the invention relates to a polypeptide conjugate as defined above, wherein at least one of the amino acid residues selected from the group consist-ing of K16, K23, K34 and K40 has been deleted or substituted with another amino acid resi-due. Preferably, at least K16 is substituted with another amino acid residue.
Examples of preferred amino acid substitutions include one or more of Q70K, Q90K, T105K, Q120K, T133K, S159K and H170K/Q/R, such as two, three, four or five of these substitutions, for example: Q70K+Q90K, Q70K+T105K, Q70K+Q120K, Q70K+T133K, Q70K+S159K, Q70K+H170K, Q90K+T105K, Q90K+Q120K, Q90K+T133K, Q90K+S159K, Q90K+H170K, T105K+Q120K, T105K+T133K, T105K+S159K, T105K+H170K, Q120K+T133K, Q120K+S159K, Q120K+H17OK, T133K+S159K, T133K+H170K, S159K+H170K, Q70K+Q90K+T105K, Q70K+Q90K+Q120K, Q70K+Q90K+T133K, Q70K+Q90K+S159K, Q70K+Q90K+H170K, Q70K+T105K+Q120K, Q70K+T105K+T133K, Q70K+T105K+S159K, Q70K+T105K+H170K, Q70K+Q120K+T133K, Q70K+Q120K+S159K, Q70K+Q120K+H170K, Q70K+T133K+S159K, Q70K+T133K+H170K, Q70K+S159K+H17OK, Q90K+T105K+Q120K, Q90K+T105K+T133K, Q90K+T105K+S159K, Q90K+T105K+H170K, Q90K+Q12OK+T133K, Q90K+Q12OK+S159K, Q90K+Q120K+H170K, Q90K+T133K+S159K, Q90K+T133K+H17OK, Q90+S159K+H17OK, T105K+Q12OK+T133K, T105K+Q120K+S159K, T105K+Q12OK+H170K, T105K+T133K+S159K, T105K+T133K+H170K, T105K+S159K+H170K, Q120K+T133K+S159K, Q120K+T133K+H170K, Q120K+S159K+H170K, T133K+S159K+H17OK, Q70K+Q90K+T105K+Q120K, Q70K+Q90K+T105K+T133K, Q70K+Q90K+T105K+S159K, Q70K+Q90K+T105K+H17OK, Q70K+Q90K+Q120K+T133K, Q70K+Q90K+Q120K+S159K, Q70K+Q90K+Q120K+H170K, Q70K+Q90K+T133K+S159K, Q70K+Q90K+T133K+H170K, Q70K+Q90K+S 159K+H170K, Q70K+T105K+Q12OK+T133K, Q70K+T105K+Q12OK+S159K, Q70K+T105K+Q12OK+H17OK, Q70K+T105K+T133K+S159K, Q70K+T105K+T133K+H170K, Q70K+T105K+S159K+H170K, Q70K+Q120K+T133K+S159K, Q70K+Q12OK+T133K+H17OK, Q70K+T133K+S159K+H170K, Q90K+T105K+Q12OK+T133K, Q90K+T105K+Q120K+S159K, Q90K+T105K+Q120K+H170K, Q90K+T105+T133K+S159K, Q90K+T105+T133K+H170K, Q90K+T105+S159K+H170K, 5 Q90K+Q120K+T133K+S159K, Q90K+Q120K+T133K+H17OK, Q90K+Q12OK+S159K+H17OK, Q90K+T133K+S159K+H170K, T105K+Q120K+T133K+S159K, T105K+Q12OK+T133K+H170K, T105K+Q120K+S159K+H170K, T105K+T133K+S159K+H170K or Q120K+T133K+S159K+H170K. In any of the variants listed above, the substitution Jo may instead be H170Q or H170R.
The polypeptide having at least one introduced and one removed lysine prefera-bly comprises at least one, such as one, two, three or four, of the substitutions selected from the group consisting of K16R, K16Q, K23R, K23Q, K34R, K34Q, K40R and K40Q, preferably at least the substitution K1 6R, whereby conjugation of this residue can be avoided. Preferably, is the polypeptide comprises at least one substitution selected from the group consisting of K16R+K23R, K16R+K34R, K16R+K40R, K23R+K34R, K23R+K40R, K34R+K40R, K16R+K23R+K34R, K16R+K23R+K40R, K23R+K34R+K40R, K16R+K34R+K40R and K16R+K23R+K34R+K40R. In one preferred embodiment, the polypeptide includes the substi-tutions K16R+K34R+K40R, while the lysine in position 23 is left unaltered. As indicated 20 above, it is contemplated that any of the individual substitutions or combinations listed in this paragraph for removal of a lysine residue may suitably be used with any of the other substitu-tions disclosed herein for introduction of lysine residues, in particular the substitutions listed in the paragraph above.
In a particular embodiment the polypeptide includes the substitutions K16R, K34R, K4OR, T105K and S159K and is conjugated to 2-6, typically 3-6 polyethylene glycol moieties with a molecular weight of about 1000-10,000 Da.
In one embodiment the conjugate of the invention has a glycosylation in T133, i.e. this position is unaltered from the wild-type hG-CSF. This is the natural glycosylation site.
Alternatively, the conjugate may be non-glycosylated, although glycosylated conjugates are preferred.
In particular, the conjugate may have 2-6, typically 3-6 polyethylene glycol moie-ties with a molecular weight of about 5000-6000 Da attached, e.g. mPEG with a molecular weight of about 5 kDa. Preferably, the conjugate has 4-5 polyethylene glycol moieties with a molecular weight of about 5000-6000 Da attached, e.g. 5 kDa mPEG.
In another embodiment, the conjugate may be produced so as to have only a sin-gle number of PEG moieties attached, e.g. either 2, 3, 4, 5 or 6 PEG moieties per polypeptide, or to have a desired mix of polypeptide conjugates with different numbers of PEG moieties attached, e.g. a mix having 2-5, 2-4, 3-5, 3-4, 4-6, 4-5 or 5-6 attached PEG
moieties. As indi-cated above, an example of a preferred conjugate mix is one having 4-5 PEG
moieties of about 5 kDa.
It will be understood that a conjugate having a specific number of attached PEG
io moieties, or a mix of conjugates having a defined range of numbers of attached PEG moieties, may be obtained by choosing suitable PEGylation conditions and optionally by using subse-quent purification to separate conjugates having the desired number of PEG
moieties. Exam-ples of methods for separation of G-CSF molecules with different numbers of PEG moieties attached are provided below. Determination of the number of attached PEG
moieties may e.g.
be performed using SDS-PAGE. For purposes of the present invention, a polypeptide conju-gate may be considered to have a given number of attached PEG moieties if separation on an SDS-PAGE gel shows no or only insignificant bands other than the band(s) corresponding to the given number(s) of PEG moieties. For example, a sample of a polypeptide conjugate is considered to have 4-5 attached PEG groups if an SDS-PAGE gel on which the sample has been run shows bands corresponding to 4 and 5 PEG groups, respectively, and only insignifi-cant bands or, preferably, no bands corresponding to 3 or 6 PEG groups.
As indicated above, it is preferred that the non-polypeptide moiety is a polymer mole-cule, preferably selected from the group consisting of linear or branched polyethylene glycol or another polyalkylene oxide. Preferred polymer molecules are e.g. mPEG-SPA (in particular SPA-mPEG 5000) from Shearwater Corp. or oxycarbonyl-oxy-N-dicarboxyimide PEG
(US
5,122,614).
It will be understood that any of the amino acid changes, in particular substitutions, specified in this section can be combined with any of the amino acid changes, preferably sub-stitutions, specified in the other sections herein disclosing specific amino acid modifications, in particular introduction and/or removal of glycosylation sites.

Glycosylated conjugates of the invention In addition to having introduced and removed lysines as described above, the conjugate of the invention may contain one or more carbohydrate moieties as a consequence of the polypeptide being expressed in a glycosylating host cell to result in glycosylation at the natural glycosylation site of hG-CSF (T133) and/or at introduced glycosylation site(s). The conjugate may thus be a glycosylated polypeptide exhibiting G-CSF activity comprising an amino acid sequence that differs from that shown in SEQ ID NO:1 in that at least one non-naturally occurring glycosylation site has been introduced into the amino acid sequence by way of at least one substitution selected from the group consisting of L3N+P5S/T, P5N, A6N, io S8N+P1OS/T, PION, Q11N+F13S/T, S12N+L14S/T, F13N+L15S/T, L14N+K16S/T, K16N+Ll8S/T, E19N+V21SIT, Q20N+R22S/T, V21N+K23SIT, R22N+124S/T, K23N+Q25S/T, Q25N+D27S/T, G26N+G28S/T, D27N+A29S/T, A29N+L3 1 S/T, A30N+Q32S/T, E33N+L35S/T, A37N+Y39S/T, T38N+K40S/T, Y39N+L41SIT, P44N+E46S/T, E45N+L47S/T, E46N+V48S/T, V48N+L50S/T, L49N+G51 S/T, L50N+H52S/T, H52N+L54S/T, S53N+G55S/T, P60N, L61N, S63N+P65S/T, P65N+Q67S/T, S66N+A68S/T, Q67N+L69S/T, A68N+Q70S/T, L69N+ L71 S/T, Q70N+A72S/T, L71N+G73S/T, G73N+L75S/T, S76N+L78S/T, Q77N+H79S/T, L78N, S80N+L82S/T, F83N+Y85SIT, Q86N+L88S/T, G87N+L89S/T, Q90N+L92S/T, E93N+195S/T, P97N+L99S/T, L99N+P101S/T, P101N+L103S/T, T102N+D104S/T, D104N+Ll06S/T, T105N+Q107S/T, Q107N+D109S/T, L108N+V11OS/T, D109N+A111S/T, All IN+Fl13S/T, D112N+A114S/T, Fl13N, T115N+I117S/T, T116N+W118S/T, W118N+Q12OS/T, Q119N+M121S/T, Q120N+E122S/T, M121N+E123S/T, E122N+L124S/T, E123N+G125S/T, L124N+M126S/T, M126N+P128S/T, P128N+L130S/T, L130N+P132S/T, P132N+Q134S/T, T133N+G135S/T, Q134N+A136S/T, A136N+P138S/T, P138N+F14OS/T, A139N+A141S/T, A141N+A143S/T, S142N+F144S/T, A143N+Q145S/T, F144N+R146S/T, Q145N+R147S/T, R146N+A148S/T, R147N+G149S/T, S155N+L157S/T, H156N+Q158S/T, S159N+L161S/T, L161N+V163S/T, E162N, V163N+Y165S/T, S164N+R166S/T, Y165N+V167S/T, R166N+L168S/T, V167N+R169S/T, L168N+H170S/T, R169N+L171S/T and H170N+A172S/T, wherein S/T indicates an S or a T residue, preferably a T
residue.
It will be understood that in order to prepare a conjugate according to this aspect the polypeptide must be expressed in a glycosylating host cell capable of attaching oligosac-charide moieties at the glycosylation site(s) or alternatively subjected to in vitro glycosylation.

Examples of glycosylating host cells are given in the section further below entitled "Coupling to an oligosaccharide moiety".
Alternatively, the conjugate according to this aspect comprises a polypeptide exhibiting G-CSF activity, which comprises an amino acid sequence that differs from that shown in SEQ ID NO:1 in at least one substitution selected from the group consisting of P5N, A6N, P1ON, P60N, L6 IN, L78N, F113N and E162N, in particular from the group consisting of P5N, A6N, P1ON, P60N, L6 IN, F113N and E162N, such as from the group consisting of P60N, L6 IN, Fl13N and E162N.
Alternatively, the conjugate according to this aspect comprises a polypeptide ex-io hibiting G-CSF activity, which comprises an amino acid sequence that differs from that shown in SEQ ID NO:1 in at least one substitution selected from the group consisting of D27N+A29S, D27N+A29T, D104N+L106S, D104N+L106T, D109N+A111S, DI 09N+A111 IT, DI 12N+A114S and Dl 12N+A 114T, more preferably from the group consist-ing of D27N+A29S, D27N+A29T, D104N+L106S, D104N+L106T, D112N+A114S and D112N+Al 14T, such as from the group consisting of D27N+A29S, D27N+A29T, D 104N+L 106S and D 104N+L106T.

Methods for preparing a conjugate of the invention In the following sections, "Conjugation to a polymer molecule" and "Conjugation to an oligosaccharide moiety", conjugation to specific types of non-polypeptide moieties is de-scribed. In general, a polypeptide conjugate according to the invention may be produced by culturing an appropriate host cell under conditions conducive for expression of the polypeptide, and recovering the polypeptide, after which the polypeptide is subjected to conjugation to a non-polypeptide moiety in vitro. In the case of glycosylated polypeptides comprising at least one N- or O-glycosylation site, glycosylation is preferably obtained by use of a eukaryotic host cell capable of in vivo glycosylation.

Conjugation to a polymer molecule The polymer molecule to be coupled to the polypeptide may be any suitable polymer molecule, such as a natural or synthetic homo-polymer or heteropolymer, typically with a molecular weight in the range of about 300-100,000 Da, such as about 500-20,000 Da, more preferably in the range of about 1000-15,000 Da, even more preferably in the range of about 2000-12,000 Da, such as about 3000-10,000. When used about polymer molecules herein, the word "about" indicates an approximate average molecular weight and reflects the fact that there will normally be a certain molecular weight distribution in a given polymer preparation.
Examples of homo-polymers include a polyol (i.e. poly-OH), a polyamine (i.e.
poly-NH2) and a polycarboxylic acid (i.e. poly-COOH). A hetero-polymer is a polymer which comprises different coupling groups, such as a hydroxyl group and an amine group.
Examples of suitable polymer molecules include polymer molecules selected from the group consisting of polyalkylene oxide (PAO), including polyalkylene glycol (PAG), such as linear or branched polyethylene glycol (PEG) and polypropylene glycol (PPG), poly-io vinyl alcohol (PVA), poly-carboxylate, poly-(vinylpyrolidone), polyethylene-co-maleic acid anhydride, polystyrene-co-maleic acid anhydride, dextran, including carboxymethyl-dextran, or any other biopolymer suitable for reducing immunogenicity and/or increasing functional in vivo half-life and/or serum half-life. Another example of a polymer molecule is human albumin or another abundant plasma protein. Generally, polyalkylene glycol-derived polymers are bio-compatible, non-toxic, non-antigenic, non-immunogenic, have various water solubility proper-ties, and are easily excreted from living organisms.
PEG is the preferred polymer molecule, since it has only few reactive groups ca-pable of cross-linking compared to polysaccharides such as dextran. In particular, monofunc-tional PEG, e.g. methoxypolyethylene glycol (mPEG), is of interest since its coupling chemis-try is relatively simple (only one reactive group is available for conjugating with attachment groups on the polypeptide). Consequently, the risk of cross-linking is eliminated, the resulting polypeptide conjugates are more homogeneous and the reaction of the polymer molecules with the polypeptide is easier to control.
To effect covalent attachment of the polymer molecule(s) to the polypeptide, the hydroxyl end groups of the polymer molecule are provided in activated form, i.e. with reactive functional groups. Suitable activated polymer molecules are commercially available, e.g. from Shearwater Corp., Huntsville, AL, USA, or from PolyMASC Pharmaceuticals plc, UK. Alter-natively, the polymer molecules can be activated by conventional methods known in the art, e.g. as disclosed in WO 90/13540. Specific examples of activated linear or branched polymer molecules for use in the present invention are described in the Shearwater Corp. 1997 and 2000 Catalogs (Functionalized Biocompatible Polymers for Research and pharmaceuticals, Polyeth-ylene Glycol and Derivatives). Specific examples of acti-vated PEG polymers include the following linear PEGs: NHS-PEG (e.g. SPA-PEG, SSPA-PEG, SBA-PEG, SS-PEG, SSA-PEG, SC-PEG, SG-PEG, and SCM-PEG), and NOR-PEG), BTC-PEG, EPOX-PEG, NCO-PEG, NPC-PEG, CDI-PEG, ALD-PEG, TRES-PEG, VS-PEG, IODO-PEG, and MAL-PEG, and branched PEGs such as PEG2-NHS and those disclosed in US 5,932,462 and US 5,643,575.
5 Furthermore, the following publications disclose useful polymer molecules and/or PEGylation chemistries: US 5,824,778, US 5,476,653, WO
97/32607, EP
229,108, EP 402,378, US 4,902,502, US 5,281,698, US 5,122,614, US 5,219,564, WO
92/16555, WO 94/04193, WO 94/14758, WO 94/17039, WO 94/18247, WO 94/28024, WO
95/00162, WO 95/11924, W095/13090, WO 95/33490, WO 96/00080, WO 97/18832, WO
10 98/41562, WO 98/48837, WO 99/32134, WO 99/32139, WO 99/32140, WO 96/40791, WO
98/32466, WO 95/06058, EP 439 508, WO 97/03106, WO 96/21469, WO 95/13312, EP

131, US 5,736,625, WO 98/05363, EP 809 996, US 5,629,384, WO 96/41813, WO
96/07670, US 5,473,034, US 5,516,673, EP 605 963, US 5,382,657, EP 510 356, EP 400 472, 503 and EP 154 316.
15 The conjugation of the polypeptide and the activated polymer molecules is con-ducted by use of any conventional method, e.g. as described in the following references (which also describe suitable methods for activation of polymer molecules): R.F.
Taylor, (1991), "Pro-tein immobilisation. Fundamental and applications", Marcel Dekker, N.Y.; S.S.
Wong, (1992), "Chemistry of Protein Conjugation and Crosslinking", CRC Press, Boca Raton;
G.T. Herman-20 son et al., (1993), "Immobilized Affinity Ligand Techniques", Academic Press, N.Y.). The skilled person will be aware that the activation method and/or conjugation chemistry to be used depends on the attachment group(s) of the polypeptide (examples of which are given further above), as well as the functional groups of the polymer (e.g. being amine, hydroxyl, carboxyl, aldehyde, sulfydryl, succinimidyl, maleimide, vinysulfone or haloacetate). The PEGylation 25 may be directed towards conjugation to all available attachment groups on the polypeptide (i.e.
such attachment groups that are exposed at the surface of the polypeptide) or may be directed towards one or more specific attachment groups, e.g. the N-terminal amino group (US
5,985,265). Furthermore, the conjugation may be achieved in one step or in a stepwise manner (e.g. as described in WO 99/55377).
It will be understood that the PEGylation is designed so as to produce the opti-mal molecule with respect to the number of PEG molecules attached, the size and form of such molecules (e.g. whether they are linear or branched), and where in the polypeptide such mole-cules are attached. The molecular weight of the polymer to be used will be chosen taking into consideration the desired effect to be achieved. For instance, if the primary purpose of the con-jugation is to achieve a conjugate having a high molecular weight and larger size (e.g. to re-duce renal clearance), one may choose to conjugate either one or a few high molecular weight polymer molecules or a number of polymer molecules with a smaller molecular weight to ob-tain the desired effect. Preferably, however, several polymer molecules with a lower molecular weight will be used. This is also the case if a high degree of epitope shielding is desired. In such cases, 2-8 polymers with a molecular weight of e.g. about 5,000 Da, such as 3-6 such polymers, may for example be used. As the examples below illustrate, it may be advantageous to have a larger number of polymer molecules with a lower molecular weight (e.g. 4-6 with a io MW of 5000) compared to a smaller number of polymer molecules with a higher molecular weight (e.g. 1-3 with a MW of 12,000-20,000) in terms of improving the functional in vivo half-life of the polypeptide conjugate, even where the total molecular weight of the attached polymer molecules in the two cases is the same or similar. It is believed that the presence of a larger number of smaller polymer molecules provides the polypeptide with a larger diameter or apparent size than e.g. a single yet larger polymer molecule, at least when the polymer mole-cules are relatively uniformly distributed on the polypeptide surface.
It has further been found that advantageous results are obtained when the appar-ent size (also referred to as the "apparent molecular weight" or "apparent mass") of at least a major portion of the conjugate of the invention is at least about 50 kDa, preferably at least about 55 kDa, more preferably at least about 60 kDa, e.g. at least about 66 kDa. This is be-lieved to be due to the fact that renal clearance is substantially eliminated for conjugates having a sufficiently large apparent size. In the present context, the "apparent size" of a G-CSF conju-gate or polypeptide is determined by the SDS-PAGE method described in the examples section below.
The use of the term "major portion" is related to the fact that the polypeptide conjugates of the invention will typically comprise individual conjugates having varying num-bers of non-polypeptide moieties attached. For example, a given polypeptide subjected to PEG-ylation under a given set of PEGylation conditions may result in a composition in which most of the individual polypeptide conjugates have e.g. between 3 and 5 PEG groups attached, with 3o a majority of the conjugates having 4 PEG groups attached. It will be clear that the apparent molecular weight of these individual conjugate molecules will vary. In this example, if we as-sume that a G-CSF polypeptide is conjugated to PEG groups with a MW of 5 kDa, conjugates having only 3 PEG groups attached will be seen on an SDS-PAGE gel as a band that is likely to have an apparent molecular weight of less than about 50 kDa, while conjugates having 4 or 5 PEG groups attached will result in bands with progressively higher apparent molecular weights that most likely all are greater than about 50 kDa. Thus, in this example there would be 3 major bands on an SDS-PAGE gel, corresponding to conjugates with 3, 4 or 5 attached PEG groups, respectively. The term "major portion" in the context of the present specification and claims is therefore intended to refer to the fact that at least one of these major bands on an SDS-PAGE
gel will correspond to the indicated minimum apparent molecular weight.
Preferably, at least 50% of the individual conjugate molecules will have a minimum apparent size as described above. More preferably, at least 60% of the individual i o conjugate molecules with have such a minimum apparent size, still more preferably at least 70%, 75%, 80% or 85%. Most preferably, at least 90% of the individual conjugate molecules will have a minimum apparent size as described above, i.e. at least 50 kDa and preferably higher, such as at least 55 kDa or 60 kDa.
It will be understood that the apparent size in kDa of a conjugate or polypeptide is not necessarily the same as the actual molecular weight of the conjugate or polypeptide.
Rather, the apparent size is a reflection of both the actual molecular weight and the overall bulk. Since, in most cases, attachment of one or more PEG groups or other non-polypeptide moieties will result in a relatively large increase of the bulk of the polypeptide to which such moieties are attached, the polypeptide conjugates of the invention will normally have an appar-2o ent size that exceeds the actual molecular weight of the conjugate.
Therefore, in connection with renal clearance, a conjugate of the invention can easily exhibit properties characteristic of a polypeptide with a molecular weight above e.g. 66 kDa (corresponding to the apparent size) but have an actual molecular weight well below 66 kDa. This effect on apparent size is be-lieved to be responsible for the observation that attachment of, for example, four PEG groups each having a molecular weight of 5 kDa provides results that are superior to a corresponding polypeptide with a single 20 kDa PEG group attached.
While conjugation of only a single polymer molecule to a single attachment group on the protein is not preferred, in the event that only one polymer molecule is attached, it will generally be advantageous that the polymer molecule, which may be linear or branched, 3o has a relatively high molecular weight, e.g. about 20 kDa.
In a further preferred embodiment, the conjugates of the invention have 1) at least a major portion with an apparent molecular weight of at least about 50 kDa and 2) a re-duced in vitro bioactivity (reduced receptor binding affinity) compared to hG-CSF as described above. It has been found that such conjugates have both a low renal clearance as a result of the large apparent size and a low receptor-mediated clearance as a result of the low in vitro bioac-tivity (low receptor binding affinity). The overall result is excellent performance in terms of effective stimulation of neutrophils together with a significantly increased in vivo half-life and thus a long duration of action that provides important clinical advantages.
Normally, the polymer conjugation is performed under conditions aiming at re-acting as many of the available polymer attachment groups as possible with polymer mole-cules. This is achieved by means of a suitable molar excess of the polymer in relation to the polypeptide (number of attachment sites). Typical molar ratios of activated polymer molecules io to polypeptide attachment sites are up to about 1000-1, such as up to about 200-1 or up to about 100-1. In some cases, the ratio may be somewhat lower, however, such as up to about 50-1, 10-1 or 5-1, e.g. if a lower degree of polymer attachment is desired.
It is also contemplated according to the invention to couple the polymer mole-cules to the polypeptide through a linker. Suitable linkers are well known to the skilled person.
A preferred example is cyanuric chloride (Abuchowski et al., (1977), J. Biol.
Chem., 252, 3578-3581; US 4,179,337; Shafer et al., (1986), J. Polym. Sci. Polyrn. Chem.
Ed., 24, 375-378.
Subsequent to the conjugation residual activated polymer molecules are blocked according to methods known in the art, e.g. by addition of primary amine to the reaction mix-ture, and the resulting inactivated polymer molecules are removed by a suitable method (see Materials and Methods).
In a preferred embodiment, the polypeptide conjugate of the invention comprises a PEG molecule attached to some, most or preferably substantially all of the lysine residues in the polypeptide available for PEGylation, in particular a linear or branched PEG molecule, e.g.
with a molecular weight of about 1-15 kDa, typically about 2-12 kDa, such as about 3-10 kDa, e.g. about 5 or 6 kDa.
It will be understood that depending on the circumstances, e.g. the amino acid se-quence of the polypeptide, the nature of the activated PEG compound being used and the spe-cific PEGylation conditions, including the molar ratio of PEG to polypeptide, varying degrees of PEGylation may be obtained, with a higher degree of PEGylation generally being obtained with a higher ratio of PEG to polypeptide. The PEGylated polypeptides resulting from any given PEGylation process will, however, normally comprise a stochastic distribution of poly-peptide conjugates having slightly different degrees of PEGylation. If desired, such a mixture of polypeptide species having different numbers of PEG moieties attached may be subjected to purification, e.g. using the methods described in the examples below, to obtain a product hav-ing a more uniform degree of PEGylation.
In yet another embodiment, the polypeptide conjugate of the invention may com-prise a PEG molecule attached to the lysine residues in the polypeptide available for PEGyla-tion, and in addition to the N-terminal amino acid residue of the polypeptide.

Coupling to an oligosaccharide moiety The conjugation to an oligosaccharide moiety may take place in vivo or in vitro, preferably in vivo. In order to achieve in vivo glycosylation of a G-CSF
molecule comprising i o one or more glycosylation sites the nucleotide sequence encoding the polypeptide must be in-serted in a glycosylating, eukaryotic expression host. The expression host cell may be selected from fungal (filamentous fungal or yeast), insect or animal cells or from transgenic plant cells.
In one embodiment the host cell is a mammalian cell, such as a CHO cell, BHK
or HEK, e.g.
HEK 293, cell, or an insect cell, such as an SF9 cell, or a yeast cell, e.g.
S. cerevisiae or Pichia pastoris, or any of the host cells mentioned hereinafter. Covalent in vitro coupling of gly-cosides (such as dextran) to amino acid residues of the polypeptide may also be used, e.g. as described in WO 87/05330 and in Aplin et al., CRC Crit Rev. Biochem., pp. 259-306, 1981.
The in vitro coupling of oligosaccharide moieties or PEG to protein- and peptide-bound Gln-residues can be carried out by transglutaminases (TG'ases).
Transglutaminases catalyze the transfer of donor amine-groups to protein- and peptide-bound Gln-residues in a so-called cross-linking reaction. The donor-amine groups can be protein- or peptide-bound e.g. as the s-amino-group in Lys-residues or can be part of a small or large organic molecule. An ex-ample of a small organic molecule functioning as an amino-donor in TG'ase-catalyzed cross-linking is putrescine (1,4-diaminobutane). An example of a larger organic molecule function-ing as an amino-donor in TG'ase-catalyzed cross-linking is an amine-containing PEG (Sato et al., Biochemistry 35, 13072-13080).
Tg'ases are in general highly specific enzymes, and not every Gln-residue exposed on the sur-face of a protein is accessible to TG'ase-catalyzed cross-linking to amino-containing sub-stances. On the contrary, only a few Gln-residues function naturally as TG'ase substrates, but the exact parameters governing which Gln-residues are good TG'ase substrates remain un-known. Thus, in order to render a protein susceptible to TG'ase-catalyzed cross-linking reac-tions it is often a prerequisite to add at convenient positions stretches of amino acid sequence known to function very well as TG'ase substrates. Several amino acid sequences are known to be or to contain excellent natural TG'ase substrates e.g. substance P, elafin, fibrinogen, fi-bronectin, a2-plasmin inhibitor, a-caseins, and (3-caseins.

Blocking of the functional site 5 It has been reported that excessive polymer conjugation can lead to a loss of ac-tivity of the polypeptide to which the polymer is conjugated. This problem can be eliminated by e.g. removal of attachment groups located at the functional site or by blocking the func-tional site prior to conjugation so that the functional site is blocked during conjugation. The latter strategy constitutes a further embodiment of the invention (the first strategy being exem-io plified further above, e.g. by removal of lysine residues which may be located close to the functional site). More specifically, according to the second strategy the conjugation between the polypeptide and the non-polypeptide moiety is conducted under conditions where the func-tional site of the polypeptide is blocked by a helper molecule capable of binding to the func-tional site of the polypeptide.
is Preferably, the helper molecule is one which specifically recognizes a functional site of the polypeptide, such as a receptor, in particular the G-CSF receptor or a part of the G-CSF receptor. Alternatively, the helper molecule may be an antibody, in particular a mono-clonal antibody recognizing the polypeptide exhibiting G-CSF activity. In particular, the helper molecule may be a neutralizing monoclonal antibody.
20 The polypeptide is allowed to interact with the helper molecule before effecting conjugation. This ensures that the functional site of the polypeptide is shielded or protected and consequently unavailable for derivatization by the non-polypeptide moiety such as a polymer.
Following its elution from the helper molecule, the conjugate between the non-polypeptide moiety and the polypeptide can be recovered with at least a partially preserved functional site.
25 The subsequent conjugation of the polypeptide having a blocked functional site to a polymer, an oligosaccharide moiety, or any other compound is conducted in the normal way, e.g. as described above.
Irrespective of the nature of the helper molecule to be used to shield the func-tional site of the polypeptide from conjugation, it is desirable that the helper molecule is free of 30 or comprises only a few attachment groups for the non-polypeptide moiety of choice in part(s) of the molecule where the conjugation to such groups would hamper desorption of the conju-gated polypeptide from the helper molecule. Hereby, selective conjugation to attachment groups present in non-shielded parts of the polypeptide can be obtained and it is possible to reuse the helper molecule for repeated cycles of conjugation. For instance, if the non-polypeptide moiety is a polymer molecule such as PEG, which has the epsilon amino group of a lysine or N-terminal amino acid residue as an attachment group, it is desirable that the helper molecule is substantially free of conjugatable epsilon amino groups, preferably free of any ep-silon amino groups. Accordingly, in a preferred embodiment the helper molecule is a protein or peptide capable of binding to the functional site of the polypeptide, which protein or peptide is free of any conjugatable attachment groups for the non-polypeptide moiety of choice.
Of particular interest in connection with the embodiment of the present invention wherein the polypeptide conjugates are prepared from a diversified population of nucleotide sequences encoding a polypeptide of interest, the blocking of the functional group is effected in microtiter plates prior to conjugation, for instance by plating the expressed polypeptide variant in a microliter plate containing an immobilized blocking group such as a receptor, an antibody or the like.
In a further embodiment the helper molecule is first covalently linked to a solid is phase such as column packing materials, for instance Sephadex or agarose beads, or a surface, e.g. a reaction vessel. Subsequently, the polypeptide is loaded onto the column material carry-ing the helper molecule and conjugation carried out according to methods known in the art, e.g.
as described above. This procedure allows the polypeptide conjugate to be separated from the helper molecule by elution. The polypeptide conjugate is eluted by conventional techniques under physico-chemical conditions that do not lead to a substantive degradation of the polypep-tide conjugate. The fluid phase containing the polypeptide conjugate is separated from the solid phase to which the helper molecule remains covalently linked. The separation can be achieved in other ways: For instance, the helper molecule may be derivatized with a second molecule (e.g. biotin) that can be recognized by a specific binder (e.g. streptavidin).
The specific binder may be linked to a solid phase, thereby allowing the separation of the polypeptide conjugate from the helper molecule-second molecule complex through passage over a second helper-solid phase column which will retain, upon subsequent elution, the helper molecule-second molecule complex, but not the polypeptide conjugate. The polypeptide conjugate may be re-leased from the helper molecule in any appropriate fashion. Deprotection may be achieved by providing conditions in which the helper molecule dissociates from the functional site of the G-CSF to which it is bound. For instance, a complex between an antibody to which a polymer is conjugated and an anti-idiotypic antibody can be dissociated by adjusting the pH to an acid or alkaline pH.

Conjugation of a tagged polypeptide In an alternative embodiment the polypeptide is expressed as a fusion protein with a tag, i.e. an amino acid sequence or peptide stretch made up of typically 1-30, such as 1-20 amino acid residues. Besides allowing for fast and easy purification, the tag is a conven-ient tool for achieving conjugation between the tagged polypeptide and the non-polypeptide moiety. In particular, the tag may be used for achieving conjugation in microtiter plates or other carriers, such as paramagnetic beads, to which the tagged polypeptide can be immobi-lized via the tag. The conjugation to the tagged polypeptide in e.g.
microtiter plates has the io advantage that the tagged polypeptide can be immobilized in the microtiter plates directly from the culture broth (in principle without any purification) and subjected to conjugation. Thereby, the total number of process steps (from expression to conjugation) can be reduced. Further-more, the tag may function as a spacer molecule, ensuring an improved accessibility to the immobilized polypeptide to be conjugated. The conjugation using a tagged polypeptide may be to any of the non-polypeptide moieties disclosed herein, e.g. to a polymer molecule such as PEG.
The identity of the specific tag to be used is not critical as long as the tag is capa-ble of being expressed with the polypeptide and is capable of being immobilized on a suitable surface or carrier material. A number of suitable tags are commercially available, e.g. from Unizyme Laboratories, Denmark. For instance, the tag may consist of any of the following sequences:
Met-Lys-His-Gln-His-Gln-His-Gln-His-Gln-His-Gln-His-Gln-Gln (SEQ ID NO:5) His-His-His-His-His-His (SEQ ID NO:9) Met-Lys-His-His-His-His-His-His (SEQ ID NO: 10) Met-Lys-His-His-Ala-His-His-Gln-His-His (SEQ ID NO: 11) Met-Lys-His-Gln-His-Gln-His-Gln-His-Gln-His-Gln-His-Gln (SEQ ID NO: 12) or any of the following:
EQKLI SEEDL (SEQ ID NO:13) (a C-terminal tag described in Mol. Cell. Biol.
5:3610-16, 1985) 3o DYKDDDDK (SEQ ID NO:14) (a C- or N-terminal tag) YPYDVPDYA (SEQ ID NO:15) Antibodies against the above tags are commercially available, e.g. from ADI, Aves Lab and Research Diagnostics.

A convenient method for using a tagged polypeptide for PEGylation is given in the Materials and Methods section below. The subsequent cleavage of the tag from the poly-peptide may be achieved by use of commercially available enzymes.

Methods for preparing a polypeptide of the invention or the polypeptide part of the conjugate of the invention The polypeptide of the present invention or the polypeptide part of a conjugate of the invention, optionally in glycosylated form, may be produced by any suitable method known in the art. Such methods include constructing a nucleotide sequence encoding the polypeptide to and expressing the sequence in a suitable transformed or transfected host.
However, polypep-tides of the invention may be produced, albeit less efficiently, by chemical synthesis or a com-bination of chemical synthesis or a combination of chemical synthesis and recombinant DNA
technology.
A nucleotide sequence encoding a polypeptide or the polypeptide part of a conju-gate of the invention may be constructed by isolating or synthesizing a nucleotide sequence encoding the parent G-CSF, such as hG-CSF with the amino acid sequence shown in SEQ ID
NO:1, and then changing the nucleotide sequence so as to effect introduction (i.e. insertion or substitution) or deletion (i.e. removal or substitution) of the relevant amino acid residue(s).
The nucleotide sequence is conveniently modified by site-directed mutagenesis in accordance with conventional methods. Alternatively, the nucleotide sequence is prepared by chemical synthesis, e.g. by using an oligonucleotide synthesizer, wherein oligonucleotides are designed based on the amino acid sequence of the desired polypeptide, and preferably selecting those codons that are favored in the host cell in which the recombinant polypeptide will be produced. For example, several small oligonucleotides coding for portions of the desired poly-peptide may be synthesized and assembled by PCR, ligation or ligation chain reaction (LCR) (Barany, PNAS 88:189-193, 1991). The individual oligonucleotides typically contain 5' or 3' overhangs for complementary assembly.
Alternative nucleotide sequence modification methods are available for produc-ing polypeptide variants for high throughput screening, for instance methods which involve 3o homologous cross-over such as disclosed in US 5,093,257, and methods which involve gene shuffling, i.e. recombination between two or more homologous nucleotide sequences resulting in new nucleotide sequences having a number of nucleotide alterations when compared to the starting nucleotide sequences. Gene shuffling (also known as DNA shuffling) involves one or more cycles of random fragmentation and reassembly of the nucleotide sequences, followed by screening to select nucleotide sequences encoding polypeptides with desired properties. In or-der for homology-based nucleic acid shuffling to take place, the relevant parts of the nucleotide sequences are preferably at least 50% identical, such as at least 60%
identical, more preferably s at least 70% identical, such as at least 80% identical. The recombination can be performed in vitro or in vivo.
Examples of suitable in vitro gene shuffling methods are disclosed by Stemmer et al. (1994), Proc. Natl. Acad. Sci. USA; vol. 91, pp. 10747-10751; Stemmer (1994), Nature, vol. 370, pp. 389-391; Smith (1994), Nature vol. 370, pp. 324-325; Zhao et al., Nat. Biotech-lo nol. 1998, Mar; 16(3): 258-61; Zhao H. and Arnold, FB, Nucleic Acids Research, 1997, Vol.
25. No. 6 pp. 1307-1308; Shao et al., Nucleic Acids Research 1998, Jan 15;
26(2): pp. 681-83;
and WO 95/17413. An example of a suitable in vivo shuffling method is disclosed in WO
97/07205. Other techniques for mutagenesis of nucleic acid sequences by in vitro or in vivo recombination are disclosed e.g. in WO 97/20078 and US 5,837,458. Examples of specific is shuffling techniques include "family shuffling", "synthetic shuffling" and "in silico shuffling".
Family shuffling involves subjecting a family of homologous genes from different species to one or more cycles of shuffling and subsequent screening or selection. Family shuffling tech-niques are disclosed e.g. by Crameri et al. (1998), Nature, vol. 391, pp. 288-291; Christians et al. (1999), Nature Biotechnology, vol. 17, pp. 259-264; Chang et al. (1999), Nature Biotech-2o nology, vol. 17, pp. 793-797; and Ness et al. (1999), Nature Biotechnology, vol. 17, 893-896.
Synthetic shuffling involves providing libraries of overlapping synthetic oligonucleotides based e.g. on a sequence alignment of homologous genes of interest. The synthetically gener-ated oligonucleotides are recombined, and the resulting recombinant nucleic acid sequences are screened and if desired used for further shuffling cycles. Synthetic shuffling techniques are 25 disclosed in WO 00/42561. In silico shuffling refers to a DNA shuffling procedure which is performed or modelled using a computer system, thereby partly or entirely avoiding the need for physically manipulating nucleic acids. Techniques for in silico shuffling are disclosed in WO 00/42560.
Once assembled (by synthesis, site-directed mutagenesis or another method), the 3o nucleotide sequence encoding the polypeptide is inserted into a recombinant vector and opera-bly linked to control sequences necessary for expression of the G-CSF in the desired trans-formed host cell.

It should of course be understood that not all vectors and expression control se-quences function equally well to express the nucleotide sequence encoding a polypeptide de-scribed herein. Neither will all hosts function equally well with the same expression system.
However, one of skill in the art may make a selection among these vectors, expression control s sequences and hosts without undue experimentation. For example, in selecting a vector, the host must be considered because the vector must replicate in it or be able to integrate into the chromosome. The vector's copy number, the ability to control that copy number, and the ex-pression of any other proteins encoded by the vector, such as antibiotic markers, should also be considered. In selecting an expression control sequence, a variety of factors should also be con-1o sidered. These include, for example, the relative strength of the sequence, its controllability, and its compatibility with the nucleotide sequence encoding the polypeptide, particularly as regards potential secondary structures. Hosts should be selected by consideration of their com-patibility with the chosen vector, the toxicity of the product coded for by the nucleotide se-quence, their secretion characteristics, their ability to fold the polypeptide correctly, their fer-15 mentation or culture requirements, and the ease of purification of the products coded for by the nucleotide sequence.
The recombinant vector may be an autonomously replicating vector, i.e. a vector, which exists as an extrachromosomal entity, the replication of which is independent of chro-mosomal replication, e.g. a plasmid. Alternatively, the vector is one which, when introduced 20 into a host cell, is integrated into the host cell genome and replicated together with the chromo-some(s) into which it has been integrated.
The vector is preferably an expression vector in which the nucleotide sequence encoding the polypeptide of the invention is operably linked to additional segments required for transcription of the nucleotide sequence. The vector is typically derived from plasmid or 25 viral DNA. A number of suitable expression vectors for expression in the host cells mentioned herein are commercially available or described in the literature. Useful expression vectors for eukaryotic hosts include, for example, vectors comprising expression control sequences from SV40, bovine papilloma virus, adenovirus and cytomegalovirus. Specific vectors are, e.g., pCDNA3.1(+)\Hyg (Invitrogen, Carlsbad, CA, USA) and pCI-neo (Stratagene, La Jolla, CA, 30 USA). Useful expression vectors for yeast cells include the 2 plasmid and derivatives thereof, the POT1 vector (US 4,931,373), the pJSO37 vector described in Okkels, Ann.
New York Acad. Sci. 782, 202-207, 1996, and pPICZ A, B or C (Invitrogen). Useful vectors for insect cells include pVL941, pBG311 (Cate et al., "Isolation of the Bovine and Human Genes for Mullerian Inhibiting Substance And Expression of the Human Gene In Animal Cells", Cell, 45, pp. 685-98 (1986), pBluebac 4.5 and pMelbac (both available from Invitrogen).
Useful expres-sion vectors for bacterial hosts include known bacterial plasmids, such as plasmids from E.
coli, including pBR322, pET3a and pET12a (both from Novagen Inc., WI, USA), wider host range plasmids, such as RP4, phage DNAs, e.g. the numerous derivatives of phage lambda, e.g.
NM989, and other DNA phages, such as M13 and filamentous single stranded DNA
phages.
Other vectors for use in this invention include those that allow the nucleotide se-quence encoding the polypeptide to be amplified in copy number. Such amplifiable vectors are well known in the art. They include, for example, vectors able to be amplified by DHFR ampli-io fication (see, e.g., Kaufman, U.S. Pat. No. 4,470,461, Kaufman and Sharp, "Construction Of A
Modular Dihydrafolate Reductase cDNA Gene: Analysis Of Signals Utilized For Efficient Ex-pression", Mol. Cell. Biol., 2, pp. 1304-19 (1982)) and glutamine synthetase ("GS") amplifica-tion (see, e.g., US 5,122,464 and EP 338,841).
The recombinant vector may further comprise a DNA sequence enabling the vec-tor to replicate in the host cell in question. An example of such a sequence (when the host cell is a mammalian cell) is the SV40 origin of replication. When the host cell is a yeast cell, suit-able sequences enabling the vector to replicate are the yeast plasmid 2 replication genes REP
1-3 and origin of replication.
The vector may also comprise a selectable marker, e.g. a gene whose product complements a defect in the host cell, such as the gene coding for dihydrofolate reductase (DHFR) or the Schizosaccharomyces pombe TPI gene (described by P.R. Russell, Gene 40, 1985, pp. 125-130), or one which confers resistance to a drug, e.g.
ampicillin, kanamycin, tet-racyclin, chloramphenicol, neomycin, hygromycin or methotrexate. For Saccharomyces cere-visiae, selectable markers include ura3 and leu2. For filamentous fungi, selectable markers include amdS, pyrG, arcB, niaD and sC.
The term "control sequences" is defined herein to include all components which are necessary or advantageous for the expression of the polypeptide of the invention. Each con-trol sequence may be native or foreign to the nucleic acid sequence encoding the polypeptide.
Such control sequences include, but are not limited to, a leader sequence, polyadenylation se-3o quence, propeptide sequence, promoter, enhancer or upstream activating sequence, signal pep-tide sequence, and transcription terminator. At a minimum, the control sequences include a promoter.

A wide variety of expression control sequences may be used in the present inven-tion. Such useful expression control sequences include the expression control sequences asso-ciated with structural genes of the foregoing expression vectors as well as any sequence known to control the expression of genes of prokaryotic or eukaryotic cells or their viruses, and vari-ous combinations thereof.
Examples of suitable control sequences for directing transcription in mammalian cells include the early and late promoters of SV40 and adenovirus, e.g. the adenovirus 2 major late promoter, the MT-1 (metallothionein gene) promoter, the human cytomegalovirus immedi-ate-early gene promoter (CMV), the human elongation factor l a (EF- l a) promoter, the Dro-io sophila minimal heat shock protein 70 promoter, the Rous Sarcoma Virus (RSV) promoter, the human ubiquitin C (UbC) promoter, the human growth hormone terminator, SV40 or adenovi-rus Elb region polyadenylation signals and the Kozak consensus sequence (Kozak, M. JMo1 Biol 1987 Aug 20;196(4):947-50).
In order to improve expression in mammalian cells a synthetic intron may be in-serted in the 5' untranslated region of the nucleotide sequence encoding the polypeptide. An example of a synthetic intron is the synthetic intron from the plasmid pCI-Neo (available from Promega Corporation, WI, USA).
Examples of suitable control sequences for directing transcription in insect cells include the polyhedrin promoter, the P 10 promoter, the Autographa californica polyhedrosis virus basic protein promoter, the baculovirus immediate early gene 1 promoter, the baculovirus 39K delayed-early gene promoter, and the SV40 polyadenylation sequence.
Examples of suit-able control sequences for use in yeast host cells include the promoters of the yeast a-mating system, the yeast triose phosphate isomerase (TPI) promoter, promoters from yeast glycolytic genes or alcohol dehydrogenase genes, the ADH2-4c promoter, and the inducible GAL pro-moter. Examples of suitable control sequences for use in filamentous fungal host cells, include the ADH3 promoter and terminator, a promoter derived from the genes encoding Aspergillus oryzae TAKA amylase triose phosphate isomerase or alkaline protease, an A.
niger a-amylase, A. niger or A. nidulans glucoamylase, A. nidulans acetamidase, Rhizomucor miehei aspartic proteinase or lipase, the TPI1 terminator and the ADH3 terminator. Examples of suitable con-trol sequences for use in bacterial host cells include promoters of the lac system, the trp sys-tem, the TAC or TRC system, and the major promoter regions of phage lambda.
The presence or absence of a signal peptide will, e.g., depend on the expression host cell used for the production of the polypeptide to be expressed (whether it is an intracellular or extracellular polypeptide) and whether it is desirable to obtain secretion.
For use in filamentous fungi, the signal peptide may conveniently be derived from a gene encoding an Aspergillus sp.
amylase or glucoamylase, a gene encoding a Rhizomucor miehei lipase or protease or a Humi-cola lanuginosa lipase. The signal peptide is preferably derived from a gene encoding A.

oryzae TAKA amylase, A. niger neutral a-amylase, A. niger acid-stable amylase, or A. niger glucoamylase. For use in insect cells, the signal peptide may conveniently be derived from an insect gene (cf. WO 90/05783), such as the Lepidopteran manduca sexta adipokinetic hormone precursor, (cf. US 5,023,328), the honeybee melittin (Invitrogen), ecdysteroid UDPglucosyl-transferase (egt) (Murphy et al., Protein Expression and Purification 4, 349-357 (1993) or hu-1 o man pancreatic lipase (hpl) (Methods in Enzymology 284, pp. 262-272, 1997). A preferred signal peptide for use in mammalian cells is that of hG-CSF or the murine Ig kappa light chain signal peptide (Coloma, M (1992) J. Imm. Methods 152:89-104). For use in yeast cells suitable signal peptides have been found to be the a-factor signal peptide from S.
cereviciae (cf. US
4,870,008), a modified carboxypeptidase signal peptide (cf. L.A. Valls et al., Cell 48, 1987, pp.
887-897), the yeast BART signal peptide (cf WO 87/02670), the yeast aspartic protease 3 (YAP3) signal peptide (cf. M. Egel-Mitani et al., Yeast 6, 1990, pp. 127-137), and the syn-thetic leader sequence TA57 (W098/32867). For use in E. coli cells a suitable signal peptide has been found to be the signal peptide ompA.
The nucleotide sequence of the invention encoding a polypeptide exhibiting G-CSF activity, whether prepared by site-directed mutagenesis, synthesis, PCR
or other meth-ods, may optionally also include a nucleotide sequence that encodes a signal peptide. The sig-nal peptide is present when the polypeptide is to be secreted from the cells in which it is ex-pressed. Such signal peptide, if present, should be one recognized by the cell chosen for ex-pression of the polypeptide. The signal peptide may be homologous (e.g. be that normally as-sociated with hG-CSF) or heterologous (i.e. originating from another source than hG-CSF) to the polypeptide or may be homologous or heterologous to the host cell, i.e. be a signal peptide normally expressed from the host cell or one which is not normally expressed from the host cell. Accordingly, the signal peptide may be prokaryotic, e.g. derived from a bacterium such as E. coli, or eukaryotic, e.g. derived from a mammalian, or insect or yeast cell.
Any suitable host may be used to produce the polypeptide or polypeptide part of the conjugate of the invention, including bacteria, fungi (including yeasts), plant, insect, mam-mal, or other appropriate animal cells or cell lines, as well as transgenic animals or plants. Ex-amples of bacterial host cells include gram-positive bacteria such as strains of Bacillus, e.g. B.

brevis or B. subtilis, or Streptomyces, or gram-negative bacteria, such as strains of E. coli or Pseudomonas. The introduction of a vector into a bacterial host cell may, for instance, be ef-fected by protoplast transformation (see, e.g., Chang and Cohen, 1979, Molecular General Genetics 168: 111-115), using competent cells (see, e.g., Young and Spizizin, 1961, Journal of Bacteriology 81: 823-829, or Dubnau and Davidoff-Abelson, 1971, Journal of Molecular Biol-ogy 56: 209-221), electroporation (see, e.g., Shigekawa and Dower, 1988, Biotechniques 6:
742-75 1), or conjugation (see, e.g., Koehler and Thorne, 1987, Journal ofBacteriology 169:
5771-5278). Examples of suitable filamentous fungal host cells include strains ofAspergillus, e.g. A. oryzae, A. niger, or A. nidulans, Fusarium or Trichoderma. Fungal cells may be trans-lo formed by a process involving protoplast formation, transformation of the protoplasts, and re-generation of the cell wall in a manner known per se. Suitable procedures for transformation of Aspergillus host cells are described in EP 238 023 and US 5,679,543. Suitable methods for transforming Fusarium species are described by Malardier et al., 1989, Gene 78: 147-156 and WO 96/00787. Examples of suitable yeast host cells include strains of Saccharomyces, e.g. S.
cerevisiae, Schizosaccharomyces, Klyveromyces, Pichia, such as P. pastoris or P. methanolica, Hansenula, such as H. polymorpha or Yarrowia. Yeast may be transformed using the proce-dures described by Becker and Guarente, In Abelson, J.N. and Simon, M.I., editors, Guide to Yeast Genetics and Molecular Biology, Methods in Enzymology, Volume 194, pp 182-187, Academic Press, Inc., New York; Ito et al., 1983, Journal ofBacteriology 153:
163; Hinnen et al., 1978, Proceedings of the National Academy of Sciences USA 75: 1920: and as disclosed by Clontech Laboratories, Inc, Palo Alto, CA, USA (in the product protocol for the YeastmakerTM
Yeast Transformation System Kit). Examples of suitable insect host cells include a Lepidop-tora cell line, such as Spodoptera frugiperda (Sf9 or Sf21) or Trichoplusioa ni cells (High Five) (US 5,077,214). Transformation of insect cells and production of heterologous polypep-tides therein may be performed as described by Invitrogen. Examples of suitable mammalian host cells include Chinese hamster ovary (CHO) cell lines, (e.g. CHO-Kl; ATCC
CCL-61), Green Monkey cell lines (COS) (e.g. COS 1 (ATCC CRL-1650), COS 7 (ATCC CRL-1651));
mouse cells (e.g. NS/O), Baby Hamster Kidney (BHK) cell lines (e.g. ATCC CRL-1632 or ATCC CCL-10), and human cells (e.g. HEK 293 (ATCC CRL-1573)), as well as plant cells in tissue culture. Additional suitable cell lines are known in the art and available from public de-positories such as the American Type Culture Collection, Rockville, Maryland.
Methods for introducing exogeneous DNA into mammalian host cells include calcium phosphate-mediated transfection, electroporation, DEAE-dextran mediated transfection, liposome-mediated trans-fection, viral vectors and the transfection method described by Life Technologies Ltd, Paisley, UK using Lipofectamin 2000. These methods are well known in the art and e.g.
described by Ausbel et al. (eds.), 1996, Current Protocols in Molecular Biology, John Wiley & Sons, New York, USA. The cultivation of mammalian cells is conducted according to established meth-5 ods, e.g. as disclosed in (Animal Cell Biotechnology, Methods and Protocols, Edited by Nigel Jenkins, 1999, Human Press Inc, Totowa, New Jersey, USA and Harrison MA and Rae IF, General Techniques of Cell Culture, Cambridge University Press 1997).
In the production methods of the present invention, the cells are cultivated in a nutrient medium suitable for production of the polypeptide using methods known in the art. For io example, the cell may be cultivated by shake flask cultivation, small-scale or large-scale fer-mentation (including continuous, batch, fed-batch, or solid state fermentations) in laboratory or industrial fermenters performed in a suitable medium and under conditions allowing the poly-peptide to be expressed and/or isolated. The cultivation takes place in a suitable nutrient me-dium comprising carbon and nitrogen sources and inorganic salts, using procedures known in 15 the art. Suitable media are available from commercial suppliers or may be prepared according to published compositions (e.g., in catalogues of the American Type Culture Collection). If the polypeptide is secreted into the nutrient medium, the polypeptide can be recovered directly from the medium. If the polypeptide is not secreted, it can be recovered from cell lysates.
The resulting polypeptide may be recovered by methods known in the art. For 20 example, the polypeptide may be recovered from the nutrient medium by conventional proce-dures including, but not limited to, centrifugation, filtration, extraction, spray drying, evapora-tion, or precipitation.
The polypeptides may be purified by a variety of procedures known in the art in-cluding, but not limited to, chromatography (e.g., ion exchange, affinity, hydrophobic, chro-25 matofocusing, and size exclusion), electrophoretic procedures (e.g., preparative isoelectric fo-cusing), differential solubility (e.g., ammonium sulfate precipitation), SDS-PAGE, or extrac-tion (see, e.g., Protein Purification, J.-C. Janson and Lars Ryden, editors, VCH Publishers, New York, 1989). Specific methods for purifying polypeptides exhibiting G-CSF
activity are described by D. Metcalf and N. A. Nicola in The hemopoietic colony-stimulating factors, p.
30 50-51, Cambridge University Press (1995), by C. S. Bae et al., Appl.
Microbiol. Biotechnol, 52:338-344 (1999) and in US 4,810,643.

Pharmaceutical composition of the invention and its use In a further aspect, the present invention comprises a composition comprising a polypeptide or conjugate as described herein and at least one pharmaceutically acceptable car-rier or excipient.
The polypeptide, the conjugate or the pharmaceutical composition according to the invention may be used for the manufacture of a medicament for treatment of diseases, in particular prevention of infection in cancer patients undergoing certain types of chemotherapy, radiation therapy and bone marrow transplantations, mobilisation of progenitor cells for collec-tion in peripheral blood progenitor cell transplantations, treatment of severe chronic or relative i o leukopenia, treatment of patients with acute myeloid leukaemia, treatment of AIDS or other immunodeficiency diseases, and for antifungal therapy, in particular for treatment of systemic or invasive candidiasis.
In another aspect the polypeptide, the conjugate or the pharmaceutical composi-tion according to the invention is used in a method of treating a mammal having a general haematopoietic disorder, including those arising from radiation therapy or from chemotherapy, in particular neutropenia or leukopenia, AIDS or other immunodeficiency diseases, comprising administering to a mammal in need thereof such a polypeptide, conjugate or pharmaceutical composition. In particular, the method is aimed at increasing the level of neutrophils in a pa-tient suffering from an insufficient neutrophil level, for example due to chemotherapy, radia-tion therapy, or HIV or another viral infection.
The polypeptides and conjugates of the invention will be administered to patients in a "therapeutically effective" dose, i.e. a dose that is sufficient to produced the desired effects in relation to the condition for which it is administered. The exact dose will depend on the dis-order to be treated, and will be ascertainable by one skilled in the art using known techniques.
The polypeptides or conjugates of the invention may e.g. be administered at a dose similar to that employed in therapy with rhG-CSF such as Neupogen . A suitable dose of a conjugate of the invention is contemplated to be in the range of about 5-300 microgram/kg body weight (based on the weight of the protein part of the conjugate), e.g. 10-200 microgram/kg, such as 25-100 microgram/kg. It will be apparent to those of skill in the art that an effective amount of 3o a polypeptide, conjugate or composition of the invention depends, inter alia, upon the disease, the dose, the administration schedule, whether the polypeptide or conjugate or composition is administered alone or in conjunction with other therapeutic agents, the serum half-life of the compositions, the general health of the patient, and the frequency of administration. Preferably, the polypeptide, conjugate, preparation or composition of the invention is administered in an effective dose, in particular a dose which is sufficient to normalize the number of leukocytes, in particular neutrophils, in the patient in question. Normalization of the number of leukocytes may be determined by simply counting the number of leukocytes at regular intervals in accor-dance with established practice.
The polypeptide or conjugate of the invention is preferably administered in a composition including one or more pharmaceutically acceptable carriers or excipients. The polypeptide or conjugate can be formulated into pharmaceutical compositions in a manner known per se in the art to result in a polypeptide pharmaceutical that is sufficiently storage-io stable and is suitable for administration to humans or animals. The pharmaceutical composition may be formulated in a variety of forms, including as a liquid or gel, or lyophilized, or any other suitable form. The preferred form will depend upon the particular indication being treated and will be apparent to one of skill in the art.
Accordingly, this invention provides compositions and methods for treating vari-ous forms of leukopenia or neutropenia. In particular the polypeptide, conjugate or composi-tion of the invention may be used to prevent infection in cancer patients undergoing certain types of radiation therapy chemotherapy and bone marrow transplantations, to mobilize pro-genitor cells for collection in peripheral blood progenitor cell transplantations, for treatment of severe chronic or relative leukopenia and to support treatment of patients with acute myeloid leukaemia. Additionally, the polypeptide, conjugate or composition of the invention may be used for treatment of AIDS or other immunodeficiency diseases and for antifungal therapy, in particular for treament of systemic or invasive candidiasis, and for the treatment of bacterial infections.
Since the polypeptide conjugates of the invention have a long in vivo half-life and have been found to reduce the duration of neutropenia and leukopenia by administration of a single dose, in contrast to hG-CSF which must be administered daily, the conjugates of the invention are well-suited for administration e.g. on a weekly basis for the prevention and/or treatment of neutropenia. In one embodiment, the polypeptide conjugate or pharmaceutical composition of the invention is for the prevention and/or treatment of neutropenia due to che-motherapy. In the case of chemotherapy administered at intervals, e.g. on a weekly basis by intravenous injection or by another type of injection, such as subcutaneous or intramuscular injection, it will normally be sufficient to administer the conjugate of the invention in a single dose per chemotherapy treatment, i.e. given either before, after or simultaneously with the chemotherapy. In other cases where the chemotherapy is administered differently, for example orally on a daily basis or over an extended period of time by means of an infusion pump, the conjugates of the invention may be administered in a similar manner, e.g. once a week, or, in the case of chemotherapy sessions given less frequently than once a week, once per session.
Drug form The polypeptide or conjugate of the invention can be used "as is" and/or in a salt form thereof. Suitable salts include, but are not limited to, salts with alkali metals or alkaline earth metals, such as sodium, potassium, calcium and magnesium, as well as e.g. zinc salts.
io These salts or complexes may by present as a crystalline and/or amorphous structure.
Excipients "Pharmaceutically acceptable" means a carrier or excipient that at the dosages and concentrations employed does not cause any untoward effects in the patients to whom it is administered. Such pharmaceutically acceptable carriers and excipients are well known in the art (see Remington's Pharmaceutical Sciences, 18th edition, A. R. Gennaro, Ed., Mack Publish-ing Company [1990]; Pharmaceutical Formulation Development of Peptides and Proteins, S.
Frokjaer and L. Hovgaard, Eds., Taylor & Francis [2000] ; and Handbook of Pharmaceutical Excipients, 3rd edition, A. Kibbe, Ed., Pharmaceutical Press [2000]).

Mix of drugs The pharmaceutical composition of the invention may be administered alone or in conjunction with other therapeutic agents. These agents may be incorporated as part of the same pharmaceutical composition or may be administered separately from the polypeptide or conjugate of the invention, either concurrently or in accordance with another treatment sched-ule. In addition, the polypeptide, conjugate or pharmaceutical composition of the invention may be used as an adjuvant to other therapies.

Patients A "patient" for the purposes of the present invention includes both humans and other mammals. Thus the methods are applicable to both human therapy and veterinary appli-cations.

Administration route The administration of the formulations of the present invention can be performed in a variety of ways, including, but not limited to, orally, subcutaneously, intravenously, in-tracerebrally, intranasally, transdermally, intraperitoneally, intramuscularly, intrapulmonary, vaginally, rectally, intraocularly, or in any other acceptable manner. The formulations can be administered continuously by infusion, although bolus injection is acceptable, using techniques well known in the art. Typically, the formulation will designed for parenteral administration, e.g. by the subcutaneous route.

1o Parenterals An example of a pharmaceutical composition is a solution designed for parenteral administration. Although in many cases pharmaceutical solution formulations are provided in liquid form, appropriate for immediate use, such parenteral formulations may also be provided in frozen or in lyophilized form. In the former case, the composition must be thawed prior to use. The latter form is often used to enhance the stability of the active compound contained in the composition under a wider variety of storage conditions, as it is recognized by those skilled in the art that lyophilized preparations are generally more stable than their liquid counterparts.
Such lyophilized preparations are reconstituted prior to use by the addition of one or more suit-able pharmaceutically acceptable diluents such as sterile water for injection or sterile physio-logical saline solution.
In case of parenterals, they are prepared for storage as lyophilized formulations or aqueous solutions by mixing, as appropriate, the polypeptide having the desired degree of pu-rity with one or more pharmaceutically acceptable carriers, excipients or stabilizers typically employed in the art (all of which are termed "excipients"), for example buffering agents, stabi-lizing agents, preservatives, isotonifiers, non-ionic detergents, antioxidants and/or other miscellaneous additives.
Buffering agents help to maintain the pH in the range which approximates physiological conditions. They are typically present at a concentration ranging from about 2 mM to about 50 mM Suitable buffering agents for use with the present invention include both organic and inorganic acids and salts thereof such as citrate buffers (e.g., monosodium citrate-disodium citrate mixture, citric acid-trisodium citrate mixture, citric acid-monosodium citrate mixture, etc.), succinate buffers (e.g., succinic acid-monosodium succinate mixture, succinic acid-sodium hydroxide mixture, succinic acid-disodium succinate mixture, etc.), tartrate buff-ers (e.g., tartaric acid-sodium tartrate mixture, tartaric acid-potassium tartrate mixture, tartaric acid-sodium hydroxide mixture, etc.), fumarate buffers (e.g., fumaric acid-monosodium fu-marate mixture, fumaric acid-disodium fumarate mixture, monosodium fumarate-disodium fumarate mixture, etc.), gluconate buffers (e.g., gluconic acid-sodium glyconate mixture, glu-5 conic acid-sodium hydroxide mixture, gluconic acid-potassium glyuconate mixture, etc.), ox-alate buffer (e.g., oxalic acid-sodium oxalate mixture, oxalic acid-sodium hydroxide mixture, oxalic acid-potassium oxalate mixture, etc.), lactate buffers (e.g., lactic acid-sodium lactate mixture, lactic acid-sodium hydroxide mixture, lactic acid-potassium lactate mixture, etc.) and acetate buffers (e.g., acetic acid-sodium acetate mixture, acetic acid-sodium hydroxide mixture, io etc.). Additional possibilities are phosphate buffers, histidine buffers and trimethylamine salts such as Tris.
Preservatives are added to retard microbial growth, and are typically added in amounts of about 0.2%-1% (w/v). Suitable preservatives for use with the present invention include phenol, benzyl alcohol, meta-cresol, methyl paraben, propyl paraben, octadecyldi-15 methylbenzyl ammonium chloride, benzalkonium halides (e.g. benzalkonium chloride, bro-mide or iodide), hexamethonium chloride, alkyl parabens such as methyl or propyl paraben, catechol, resorcinol, cyclohexanol and 3-pentanol.
Isotonicifiers are added to ensure isotonicity of liquid compositions and include polyhydric sugar alcohols, preferably trihydric or higher sugar alcohols, such as glycerin, 20 erythritol, arabitol, xylitol, sorbitol and mannitol. Polyhydric alcohols can be present in an amount between 0.1 % and 25% by weight, typically I% to 5%, taking into account the relative amounts of the other ingredients.
Stabilizers refer to a broad category of excipients which can range in function from a bulking agent to an additive which solubilizes the therapeutic agent or helps to prevent 25 denaturation or adherence to the container wall. Typical stabilizers can be polyhydric sugar alcohols (enumerated above); amino acids such as arginine, lysine, glycine, glutamine, aspar-agine, histidine, alanine, omithine, L-leucine, 2-phenylalanine, glutamic acid, threonine, etc., organic sugars or sugar alcohols, such as lactose, trehalose, stachyose, mannitol, sorbitol, xyli-tol, ribitol, myoinisitol, galactitol, glycerol and the like, including cyclitols such as inositol;
30 polyethylene glycol; amino acid polymers; sulfur-containing reducing agents, such as urea, glutathione, thioctic acid, sodium thioglycolate, thioglycerol, a-monothioglycerol and sodium thiosulfate; low molecular weight polypeptides (i.e. <10 residues); proteins such as human se-rum albumin, bovine serum albumin, gelatin or immunoglobulins; hydrophilic polymers such as polyvinylpyrrolidone; monosaccharides such as xylose, mannose, fructose and glucose; di-saccharides such as lactose, maltose and sucrose; trisaccharides such as raffinose, and polysac-charides such as dextran. Stabilizers are typically present in the range of from 0.1 to 10,000 parts by weight based on the active protein weight.
Non-ionic surfactants or detergents (also known as "wetting agents") may be pre-sent to help solubilize the therapeutic agent as well as to protect the therapeutic polypeptide against agitation-induced aggregation, which also permits the formulation to be exposed to shear surface stress without causing denaturation of the polypeptide. Suitable non-ionic surfac-tants include polysorbates (20, 80, etc.), polyoxamers (184, 188 etc.), Pluronic polyols, poly-lo oxyethylene sorbitan monoethers (Tween -20, Tween -80, etc.).
Additional miscellaneous excipients include bulking agents or fillers (e.g.
starch), chelating agents (e.g. EDTA), antioxidants (e.g., ascorbic acid, methionine, vitamin E) and cosolvents.
The active ingredient may also be entrapped in microcapsules prepared, for ex-ample, by coascervation techniques or by interfacial polymerization, for example hydroxy-methylcellulose, gelatin or poly-(methylmethacylate) microcapsules, in colloidal drug delivery systems (for example liposomes, albumin microspheres, microemulsions, nano-particles and nanocapsules) or in macroemulsions. Such techniques are disclosed in Remington's Pharma-ceutical Sciences, supra.
Parenteral formulations to be used for in vivo administration must be sterile.
This is readily accomplished, for example, by filtration through sterile filtration membranes.
Sustained release preparations Suitable examples of sustained-release preparations include semi-permeable ma-trices of solid hydrophobic polymers containing the polypeptide or conjugate, the matrices hav-ing a suitable form such as a film or microcapsules. Examples of sustained-release matrices include polyesters, hydrogels (for example, poly(2-hydroxyethyl-methacrylate) or poly(vinylalcohol)), polylactides, copolymers of L-glutamic acid and ethyl-L-glutamate, non-degradable ethylene-vinyl acetate, degradable lactic acid-glycolic acid copolymers such as the ProLease technology or Lupron Depot (injectable microspheres composed of lactic acid-glycolic acid copolymer and leuprolide acetate), and poly-D-(-)-3-hydroxybutyric acid. While polymers such as ethylene-vinyl acetate and lactic acid-glycolic acid enable release of mole-cules for long periods such as up to or over 100 days, certain hydrogels release proteins for shorter time periods. When encapsulated polypeptides remain in the body for a long time, they may denature or aggregate as a result of exposure to moisture at 37 C, resulting in a loss of biological activity and possible changes in immunogenicity. Rational strategies can be devised for stabilization depending on the mechanism involved. For example, if the aggregation mechanism is discovered to be intermolecular S-S bond formation through thio-disulfide inter-change, stabilization may be achieved by modifying sulfhydryl residues, lyophilizing from acidic solutions, controlling moisture content, using appropriate additives, and developing spe-cific polymer matrix compositions.

The invention is further described in the non-limiting examples below.
DESCRIPTION OF THE DRAWINGS

Figure 1: The in vivo half-lives of rhG-CSF (Neupogen ) and SPA-PEG 5000-conjugated hG-Figure 2: The in vivo half-lives of rhG-CSF (Neupogen ) and SPA-PEG 5000-conjugated hG-Figure 3: The in vivo biological activities in healthy rats of rhG-CSF
(Neupogen ), SPA-PEG
5000-conjugated hG-CSF K16R K34R K40R Q70K Q120K and SPA-PEG 5000-conjugated hG-CSF K16R K34R K40R Q70K Q90K Q120K.

Figure 4: The in vivo biological activities in healthy rats of rhG-CSF
(Neupogen ), SPA-PEG
5000-conjugated hG-CSF K16R K34R K40R Q70K Q120K T133K and SPA-PEG 5000-conjugated hG-CSF K16R K34R K40R Q90K Q120K T133K.

3o Figure 5: The in vivo biological activities in healthy rats of rhG-CSF
(Neupogen ), SPA-PEG
12000-conjugated hG-CSF K16R K34R K40R and different doses of SPA-PEG 5000-conjugated hG-CSF K16R K34R K40R Q70K Q90K Q120K.

Figure 6: The in vivo biological activities in healthy rats of rhG-CSF
(Neupogen ), SPA-PEG
5000-conjugated hG-CSF K16R K34R K40R Q70K Q90K Q120K, SPA-PEG 5000-conjugated hG-CSF K1 6R K34R K40R Q90K TI 05K S159K and SPA-PEG 20000-conjugated hG-CSF K1 6R K34R K40R T105K S159K.

Figure 7: The in vivo biological activities in rats with chemotherapy-induced neutropenia of rhG-CSF (Neupogen ), SPA-PEG 5000-conjugated hG-CSF K16R K34R K40R Q70K Q90K
T105K, SPA-PEG 20000-conjugated hG-CSF K16R K34R K40R Q90K.

io Figure 8: The in vivo biological activities (white blood cell count) in rats with chemotherapy-induced neutropenia of rhG-CSF (Neupogen ), SPA-PEG 5000-conjugated hG-CSF

K34R K40R T105K S159K, and SPA-PEG 5000-conjugated hG-CSF K16R K34R K40R
Q90K T105K S159K.

Figure 9: The in vivo biological activities (absolute neutrophil count) in rats with chemother-apy-induced neutropenia of rhG-CSF (Neupogen ) and SPA-PEG 5000-conjugated hG-CSF
K1 6R K34R K40R TI 05K S159K.

Figure 10: The in vivo biological activities (white blood cell count) in rats with chemotherapy-induced neutropenia of rhG-CSF (Neupogen ), rhG-CSF with a 20 kDa N-terminal PEG
group (NeulastaTM), and SPA-PEG 5000-conjugated hG-CSF K1 6R K34R K40R T105K

S 159K produced in yeast and in CHO cells.

Figure 11: The in vivo biological activities (absolute neutrophil count) in rats with chemother-apy-induced neutropenia of rhG-CSF (Neupogen ), rhG-CSF with a 20 kDa N-terminal PEG
group (NeulastaTM), and SPA-PEG 5000-conjugated hG-CSF K16R K34R K40R T105K

S 159K produced in yeast and in CHO cells.
SEQUENCE LISTING
3o The appended sequence listing contains the following sequences:
SEQ ID NO:1: The amino acid sequence of human G-CSF.

SEQ ID NO:2: A synthetic DNA sequence encoding human G-CSF, with codon usage opti-mized for expression in E. coli.
SEQ ID NO:3: The amino acid sequence of the OmpA signal sequence.
SEQ ID NO:4: A synthetic DNA sequence encoding the OmpA signal sequence.
SEQ ID NO:5: A synthetic histidine tag.
SEQ ID NO:6: A synthetic DNA sequence encoding the histidine tag of SEQ ID
NO:5.
SEQ ID NO:7: The amino acid sequence of a human G-CSF signal peptide.
SEQ ID NO:8: A synthetic DNA sequence encoding human G-CSF, including the signal pep-tide of SEQ ID NO:7, with codon usage optimized for expression in CHO cells.
to SEQ ID NO:9-15: Various synthetic tags MATERIALS AND METHODS

Methods used to determine the amino acids to be modified Accessible Surface Area (ASA) A 3D ensemble of 10 structures determined by NMR spectroscopy (Zink et al.
(1994) Biochemistry 33: 8453-8463) is available from the Protein Data Bank (PDB) (www.resb.org_/pdb/). This information can be entered into the computer program Access (B.

Lee and F.M. Richards, J. Mol. Biol. 55: 379-400 (1971)) version 2 ( 1983 Yale University) and used to compute the accessible surface area (ASA) of the individual atoms in the structure.
This method typically uses a probe size of 1.4A and defines the Accessible Surface Area (ASA) as the area formed by the centre of the probe. Prior to this calculation all water mole-cules and all hydrogen atoms should be removed from the coordinate set as should other atoms not directly related to the protein.

Fractional ASA of side chain The fractional ASA of the side chain atoms is computed by division of the sum of the ASA of the atoms in the side chain with a value representing the ASA of the side chain 3o atoms of that residue type in an extended ALA-x-ALA tripeptide. See Hubbard, Campbell &
Thornton (1991) J.Mol.Biol.220, 507-530. For this example the CA atom is regarded as a part of the side chain of glycine residues but not for the remaining residues. The values in the fol-lowing table are used as standard 100% ASA for the side chain:

Ala 69.23 A2 Leu 140.76 A2 Arg 200.35 A2 Lys 162.50 A2 Asn 106.25 A2 Met 156.08 A2 Asp 102.06 A2 Phe 163.90 A2 Cys 96.69 A2 Pro 119.65 A2 Gln 140.58 A2 Ser 78.16 A2 Glu 134.61 A2 Thr 101.67 A2 Gly 32.28 A2 Tip 210.89 A210 His 147.00 A2 Tyr 176.61 A2 Ile 137.91 A2 Val 114.14 A2 15 Residues not detected in the structure are defined as having 100% exposure as they are thought to reside in flexible regions.

Determining distances between atoms:
The distance between atoms is most easily determined using molecular graphics soft-20 ware, e.g. Insightll v. 98.0, MSI INC.

General considerations regarding amino acid residues to be modified As explained above, amino acid residues to be modified in accordance with the pre-sent invention are preferably those whose side chains are surface exposed, in particular those 25 with more than about 25% of the side chain exposed at the surface of the molecule, and more preferably those with more than 50% side chain exposure. Another consideration is that resi-dues located in receptor interfaces are preferably excluded so as to avoid or at least minimize possible interference with receptor binding or activation. A further consideration is that resi-dues that are less than 10A from the nearest Lys (Glu, Asp) CB-CB (CA for Gly) should also 3o be excluded. Finally, preferred positions for modification are in particular those that have a hydrophilic and/or charged residue, i.e. Asp, Asn, Glu, Gln, Arg, His, Tyr, Ser and Thr, posi-tions that have an arginine residue being especially preferred.

Identifying G-CSF amino acid residues for modification 35 The information below illustrates the factors that generally should be taken into con-sideration when identifying amino acid residues to be modified in accordance with the present invention.

Three-dimensional structures have been reported for human G-CSF by X-ray crystal-lography (Hill et al. (1993) Proc.Natl.Acad.Sci.USA 90: 5167-5171) and by NMR
spectros-copy (Zink et al. (1994) Biochemistry 33: 8453-8463). As mentioned above, Aritomi et al.
(Nature 401:713-717, 1999) have identified the following hG-CSF residues as being part of the receptor binding interfaces: G4, P5, A6, S7, S8, L9, P10, Q11, S12, L15, K16, E19, Q20, L108, D109, Dl 12, Tl 15, T116, Q119, E122, E123, and L124. Thus, although it is possible to modify these residues, it is preferred that these residues are excluded from modification.
Using the 10 NMR structures of G-CSF identified by Zink et al. (1994) as input struc-tures followed by a computation of the average ASA of the side chain, the following residues io have been identified as having more than 25% ASA: MO, Tl, P2, L3, G4, P5, A6, S7, S8, L9, P10, Q11, S12, F13, L14, L15, K16, C17, E19, Q20, V21, R22, K23, Q25, G26, D27, A29, A30, E33, K34, C36, A37, T38, Y39, K40, L41, H43, P44, E45, E46, V48, L49, L50, H52, S53, L54, 156, P57, P60, L61, S62, S63, P65, S66, Q67, A68, L69, Q70, L71, A72, G73, C74, S76, Q77, L78, S80, F83, Q86, G87, Q90, E93, G94, S96, P97, E98, L99, G100, P101, T102, D104,T105,Q107,L108,D109,Alll,D112,F113,T115,T116,W118,Q119,Q120,M121, E122, E123, L124, M126, A127, P128, A129, L130, Q131, P132, T133, Q134, G135, A136, M137, P138, A139, A141, S142, A143, F144, Q145, R146, R147, S155, H156, Q158, S159, L161, E162, V163, S164, Y165, R166, V167, L168, R169, H170, L171, A172, Q173, P174.
Similarly, the following residues have more than 50% ASA: MO, Ti, P2, L3, G4, P5, A6, S7, S8, L9, P10, Qil, S12, F13, L14, L15, K16, C17, E19, Q20, R22, K23, G26, D27, A30, E33, K34, T38, K40, L41, H43, P44, E45, E46, L49, L50, S53, P57, P60, L61, S62, S63, P65, S66, Q67, A68, L69, Q70, L71, A72, G73, S80, F83, Q90, G94, P97, E98, P101, D104, T105, L108, D112, F113, T115, T116, Q119, Q120, E122, E123, L124, M126, P128, A129, L130, Q131, P132, T133, Q134, G135, A136, A139, A141, S142, A143, F144, R147, S155, S159, E162, R166, V167, R169, H170, L171, A172, Q173, P174.
The molecular graphics program InsightII v.98.0 was used to determine residues having their CB atom (CA in the case of glycine) at a distance of more than 15A from the nearest amine group, defined as the NZ atoms of lysine and the N atom of the N-terminal resi-due Ti. The following list includes the residues that fulfill this criteria in at least one of the 10 3o NMR structures. G4, P5, A6, S7, S8, L9, P10, Q11, L14, L15, L18, V21, R22, Q25, G26, D27, G28, A29, Q32, L35, C36, T38, Y39, C42, H43, P44, E45, E46, L47, V48, L49, L50, G51, H52, S53, L54, G55,156, P57, W58, A59, P60, L61, S62, S63, C64, P65, S66, Q67, A68, L69, Q70, L71, A72, G73, C74, L75, S76, Q77, L78, H79, S80, G81, L82, F83, L84, Y85, Q86, G87, L88, L89, Q90, A91, L92, E93, G94,195, S96, P97, E98, L99, G100, P101, T102, L103, D104, T105, L106, Q107, L108, D109, V110, All 1, D112, F113, A114, TI 15, T116,1117, W118, Q119, Q120, M121, E122, E123, L124, G125, M126, A127, P128, A129, L130, Q131, P132, T133, Q134, G135, A136, M137, P138, A139, F140, A141, S142, A143, F144, Q145, R146, R147, A148, G149, G150, V151, L152, V153, A154, 5155, H156, L157, Q158, 5159, F160, L161, E162, V163, S164, Y165, R166, V167, L168, R169, H170, L171, A172, Q173, P174.
The InsightII v.98.0 program was similarly used to determine residues having their CB atom (CA atom in the case of glycine) at a distance of more than 10A from the nearest i o acidic group, defined as the CG atoms of aspartic acid, the CD atoms of glutamic acid and the C atom of the C-terminal residue P 174. The following list includes the residues that fulfill this criteria in at least one of the 10 NMR structures. MO, Ti, P2, L3, G4, P5, A6, S7, S8, L9, P10, Q11, S12, F13, L14, T38, Y39, K40, L41, C42, L50, G51, H52, S53, L54, G55,156, P57, W58, A59, P60, L61, S62, S63, C64, P65, S66, Q67, A68, L69, Q70, L71, A72, G73, C74, L75, S76, Q77, L78, H79, S80, G81, L82, F83, L84, Y85, Q86, G87, L88, I117, M126, A127, P128, A129, L130, Q131, P132, T133, Q134, G135, A136, M137, P138, A139, F140, A141, S142, A143, F144, Q145, R146, R147, A148, G149, G150, V151, L152, V153, A154, S155, H156, L157, V167, L168, R169, H170, L171.
By combining and comparing the above lists, it is possible to select individual amino acid residues for modification to result in a list containing a limited number of amino acid resi-dues whose modification in a given G-CSF polypeptide is likely to result in desired properties.
Methods for PEGylation of hG-CSF and variants thereof PEGylation of hG-CSF and variants thereof in solution Human G-CSF and variants thereof are PEGylated at a concentration of 250 g/m1 in 50 mM sodium phosphate, 100 mM NaCl, pH 8.5. The molar surplus of PEG is 50-100 times with respect to PEGylation sites on the protein. The reaction mixture is placed in a thermo mixer for 30 minutes at 37 C at 1200 rpm. After 30 minutes, quenching of the reaction is ob-tained by adding a molar excess of glycine.
Cation exchange chromatography is applied to remove excess PEG, glycine and other by-products from the reaction mixture. The PEGylation reaction mixture is diluted with 20 mM
sodium citrate pH 2.5 until the ionic strength is less than 7 mS/cm. pH is adjusted to 2.5 using N HCI. The mixture is applied to a SP-sepharose FF column equilibrated with 20 mM so-dium citrate pH 2.5. Unbound material is washed off the column using 4 column volumes of equilibration buffer. PEGylated protein is eluted in three column volumes by adding 20 mM
sodium citrate, 750 mM sodium chloride. Pure PEGylated G-CSF is concentrated and buffer 5 exchange is performed using VivaSpin concentration devices, molecular weight cut-off (mwco): lOkDa.

PEGylation in microtiter plates of a tagged polypeptide with G-CSF activity A polypeptide exhibiting G-CSF activity is expressed with a suitable tag, e.g.
any of the 1o tags exemplified in the general description above, and culture broth is transferred to one or more wells of a microtiter plate capable of immobilising the tagged polypeptide. When the tag is Met-Lys-His-Gln-His-Gln-His-Gln-His-Gln-His-Gln-His-Gln-Gln, a nickel-nitrilotriacetic acid (Ni-NTA) HisSorb microtiter plate commercially available from QIAGEN can be used.
After immobilization of the tagged polypeptide to the microtiter plate, the wells are washed in a buffer suitable for binding and subsequent PEGylation followed by incubating the wells with the activated PEG of choice. As an example, M-SPA-5000 from Shearwater Corp. is used. The molar ratio of activated PEG to polypeptide should be optimized, but will typically be greater than 10:1, e.g. up to about 100:1 or higher. After a suitable reaction time at ambient temperature, typically around 1 hour, the reaction is stopped by removal of the activated PEG
solution. The conjugated protein is eluted from the plate by incubation with a suitable buffer.
Suitable elution buffers may contain imidazole, excess NTA or another chelating compound.
The conjugated protein is assayed for biological activity and immunogenicity as appropriate.
The tag may optionally be cleaved off using a method known in the art, e.g.
using diaminopep-tidase the Gln in pos -1 can be converted to pyroglutamyl with GCT
(glutamylcyclotrans-ferase) and finally cleaved off with PGAP (pyro-glutamyl-aminopeptidase), giving the untagged protein. The process involves several steps of metal chelate affinity chromatography.
Alternatively, the tagged polypeptide may be conjugated.

PEGylation of a polypeptide exhibiting hG-CSF activity and having a blocked receptor-3o binding site In order to optimize PEGylation of hG-CSF in a manner excluding PEGylation of lysi-nes involved in receptor recognition, the following method has been developed:

Purified hG-CSF is obtained as described in Example 4. A homodimer complex con-sisting of an hG-CSF polypeptide and the soluble domain of the G-CSF receptor in a 2:2 sto-chiometry is formed in a phosphate-buffered saline solution (PBS) buffer at pH
7. The concen-tration of hG-CSF polypeptide is approximately 20 pglml or 1 pM and the receptor is present s at an equimolar concentration.
M-SPA-5000 from Shearwater Corp. is added at 3 different concentration levels corre-sponding to a 10, 25 and 50 molar excess to the number of attachment sites in hG-CSF poly-peptide. The reaction time is 30 min at room temperature. After the 30 min reaction period, the pH of the reaction mixture is adjusted to pH 2.0 and the reaction mixture is applied to a VydacTM
1o C18 column and eluted with an acetonitrile gradient essentially as described (Utsumi et al., J.
Biochem., Vol. 101, 1199-1208, (1987). Alternatively, an isopropanol gradient can be used.
Fractions are analyzed using the primary screening assay described herein and active PEGylated hG-CSF polypeptide obtained by this method is stored at -80 C in PBS, pH 7 containing 1 mg/ml human serum albumin (HSA).

Methods used to characterize conjugated and non-conjugated hG-CSF and variants thereof Determination of the molecular size of hG-CSF and variants thereof The molecular weight of conjugated or non-conjugated hG-CSF or variants thereof is de-termined by either SDS-PAGE, gel filtration, matrix assisted laser desorption mass spectrometry or equilibrium centrifugation. As explained above, SDS-PAGE provides information on the "ap-parent molecular weight". The actual molecular weight can advantageously be determined using mass spectrometry. SDS-PAGE is carried out using the NuPAGE kit (Novex high-performance pre-cast gels) from Invitrogen . 15 gl of the samples are loaded onto NuPAGE 4-12% Bis-Tris gels (Cat. Nr. NP0321) and eluted in NuPAGE MES SDS running buffer (Cat. Nr.
NP0002-02) for 35 minutes at 200 V and 120 mA.

Determination ofpolypeptide concentration The concentration of a polypeptide can be measured using optical density measure-ments at 280 nm, an enzyme-linked immunoadsorption assay (ELISA), a radio-immunoassay (RAA), or other such immunodetection techniques well known in the art.
Furthermore, the polypeptide concentration in a sample can be measured with the Biacore instrument using a Biacore chip coated with an antibody specific for the polypeptide.

Such an antibody can be coupled covalently to the Biacore chip by various chemis-tries. Alternatively, the antibody can be bound non-covalently e.g. by means of an antibody 5 specific for the Fc portion of the anti-polypeptide antibody. The Fc specific antibody is first coupled covalently to the chip. The anti-polypeptide antibody is then flowed over the chip and is bound by the first antibody in a directed fashion. Furthermore, biotinylated antibodies can be immobilized using a streptavidin coated surface (e.g. Biacore Sensor Chip SA ) (Real-Time Analysis of Biomolecular Interactions, Nagata and Handa (Eds.), 2000, Springer Verlag, To-1o kyo; Biacore 2000 Instrument Handbook, 1999, Biacore AB).
When the sample is flowed over the chip the polypeptide will bind to the coated anti-body and the increase in mass can be measured. By using a preparation of the polypeptide in a known concentration, a standard curve can be established and subsequently the concentration of the polypeptide in the sample can be determined. After each injection of sample the sensor 15 chip is regenerated by a suitable eluent (e.g. a low pH buffer) that removes the bound analyte.
Generally, the applied antibodies will be monoclonal antibodies raised against the wild type polypeptide. Introduction of mutations or other manipulations of the wild type polypeptide (extra glycosylations or polymer conjugations) may alter the recognition by such antibodies.
Furthermore, such manipulations that give rise to an increased molecular weight of the poly-20 peptide will result in an increased plasmon resonance signal. Consequently, it is necessary to establish a standard curve for every molecule to be tested.

Methods used to determine the in vitro and in vivo activity of conjugated and non-conjugated hG-CSF and variants thereof Primary assay 1- in vitro G-CSF activity assay Proliferation of the murine cell line NFS-60 (obtained from Dr. J. Ihle, St.
Jude Chil-dren's Research Hospital, Tennessee, USA) is dependent on the presence of active G-SCF in the growth medium. Thus, the in vitro biological activity of hG-CSF and variants thereof can 3o be determined by measuring the number of dividing NFS-60 cells after addition of a G-CSF
sample to the growth medium followed by incubation over a fixed period of time.
NFS-60 cells are maintained in Iscoves DME Medium containing 10% w/w FBS
(fetal bovine serum), 1 % w/w Pen/Strep, 10 g per litre hG-CSF and 2 mM Glutamax.
Prior to sam-ple addition, cells are washed twice in growth medium without hG-CSF and diluted to a con-centration of 2.2 x 105 cells per ml. 100 l of the cell suspension is added to each well of a 96 well microtiter plate (Coming).
Samples containing conjugated or non-conjugated G-CSF or variants thereof are diluted to concentrations between 1.1 x 10-6 M and 1.1 x 10-13 M in the growth medium.
10 l of each sample is added to 3 wells containing NFS-60 cells. A control consisting of 10 l of mammal-ian growth medium is added to 8 wells on each microtiter plate. The cells are incubated for 48 hours (37 C, 5% C02) and the number of dividing cells in each well is quantified using the WST-1 cell proliferation agent (Roche Diagnostics GmbH, Mannheim, Germany).
0.01 ml io WST-1 is added to the wells followed by incubation for 150 min. at 37 C in a 5% CO2 air atmosphere. The cleavage of the tetrazolium salt WST-1 by mitochondrial dehydrogenases in viable cells results in the formation of formazan that is quantified by measuring the absorbance at 450 run. Hereby, the number of viable cells in each well is quantified.
Based on these measurements, dose-response curves for each conjugated and non-conjugated G-CSF molecule or variants thereof are calculated, after which the EC50 value for each molecule can be determined. This value is equal to the amount of active G-CSF protein that is necessary to obtain 50% of the maximum proliferation activity of non-conjugated hu-man G-CSF. Thus, the EC50 value is a direct measurement of the in vitro activity of the given protein, a lower EC50 value indicating a higher activity.

Primary assay 2 - in vitro G-CSF activity assay The murine hematopoietic cell line BaF3 is transfected with a plasmid carrying the hu-man G-CSF receptor and the promoter of the transcription regulator, fos, in front of the luciferase reporter gene. Upon stimulation of such a cell line with a G-CSF
sample, a number of intracellular reactions lead to stimulation offos expression, and consequently to expression of luciferase. This stimulation is monitored by the Steady-Glo M Luciferase Assay System (Promega, Cat. No. E2510) whereby the in vitro activity of the G-CSF sample may be quanti-fied.
BaF3/hGCSF-R/pfos-lux cells are maintained at 37 C in a humidified 5% CO2 atmos-phere in complete culture media (RPMI-1640/HEPES (Gibco/BRL, Cat. No. 22400), 10% FBS
(HyClone, characterized), 1 x Penicillin/Streptomycin (Gibco/BRL, Cat. No.
15140-122), lx L-Glutamine (Gibco/BRL, Cat. No. 25030-081), 10% WEHI-3 conditioned media (source of muIL-3), and grown to a density of 5 x 105 cells/mL (confluent). The cells are reseeded at about 2 x 104 cells/mL every 2-3 days.
One day prior to the assay, log-phase cells are resuspended at 2 x 105 cells/mL in starv-ing media (DMEM/F-12 (Gibco/BRL, Cat. No. 11039), 1% BSA (Sigma, Cat. No.
A3675), lx Penicillin/Streptomycin (GibcoBRL, Cat. No. 15140-122), lx L-Glutamine (Gibco/BRL, Cat.
No. 25030-081), 0.1 % WEHI-3 conditioned media) and starved for 20 hours. The cells are washed twice with PBS and tested for viability using Trypan Blue viability staining. The cells are resuspended in assay media (RPMI-1640 (phenol-red free, GibcoBRL, Cat. No.
11835), 25 mM HEPES, 1% BSA (Sigma, Cat. No. A3675), Ix Penicillin/Streptomycin (Gibco/BRL, Cat.
to No. 15140-122), lx L-Glutamine (Gibco/BRL, Cat. No. 25030-081) at 4 x 106 cells/mL, and 50 L are aliquotted into each well of a 96-well microtiter plate (Coming).
Samples containing conjugated or non-conjugated G-CSF or variants thereof are diluted to concentrations between 1.1x10"7 M and 1.1x10-12 M in the assay medium. 50 l of each sample is added to 3 wells con-taining BaF3/hGCSF-R/pfos-lux cells. A negative control consisting of 50 l of medium is added to 8 wells on each microtiter plate. The plates are mixed gently and incubated for 2 hours at 37 C. The luciferase activity is measured by following the Promega Steady-G1oTM
protocol (Promega Steady-GloTm Luciferase Assay System, Cat. No. E2510). 100 L of sub-strate is added per well followed by gentle mixing. Luminescence is measured on a TopCount luminometer (Packard) in SPC (single photon counting) mode.
Based on these measurements, dose-response curves for each conjugated and non-conjugated G-CSF molecule or variants thereof are calculated, after which the EC50 value for each molecule can be determined.

Secondary assay - binding affinity of G-CSF or variants thereof to the hG-CSF
receptor Binding of rhG-CSF or variants thereof to the hG-CSF receptor is studied using stan-dard binding assays. The receptors may be purified extracellular receptor domains, receptors bound to purified cellular plasma membranes, or whole cells - the cellular sources being either cell lines that inherently express G-CSF receptors (e.g. NFS-60) or cells transfected with cDNAs encoding the receptors. The ability of rhG-CSF or variants thereof to compete for the 3o binding sites with native G-CSF is analyzed by incubating with a labeled G-CSF-analog, for instance biotinylated hG-CSF or radioiodinated hG-CSF. An example of such an assay is de-scribed by Yamasaki et al. (Drugs. Exptl. Clin. Res. 24:191-196 (1998)).

The extracellular domains of the hG-CSF receptor can optionally be coupled to Fc and immobilized in 96 well plates. RhG-CSF or variants thereof are subsequently added and the binding of these is detected using either specific anti-hG-CSF antibodies or biotinylated or ra-dioiodinated hG-CSF.
Measurement of the in vivo half-life of conjugated and non-conjugated rhG-CSF
and variants thereof An important aspect of the invention is the prolonged biological half-life that is ob-tained by construction of a hG-CSF with or without conjugation of the polypeptide to the to polymer moiety. The rapid decrease of hG-CSF serum concentrations has made it important to evaluate biological responses to treatment with conjugated and non-conjugated hG-CSF and variants thereof. Preferably, the conjugated and non-conjugated hG-CSF and variants thereof of the present invention have prolonged serum half-lives also after i.v.
administration, making it possible to measure by e.g. an ELISA method or by the primary screening assay. Measure-ment of in vivo biological half-life was carried out as described below.
Male Sprague Dawley rats (7 weeks old) were used. On the day of administration, the weights of the animals were measured (280-3 10 gram per animal). 100 .tg per kg body weight of the non-conjugated and conjugated hG-CSF samples were each injected intravenously into the tail vein of three rats. At 1 minute, 30 minutes, 1, 2, 4, 6, and 24 hours after the injection, 500 l of blood was withdrawn from the eyes of each rat while under CO2 -anaesthesia. The blood samples were stored at room temperature for 1 %2 hours followed by isolation of serum by centrifugation (4 C, 18000xg for 5 minutes). The serum samples were stored at -80 C until the day of analysis. The amount of active G-CSF in the serum samples was quantified by the G-CSF in vitro activity assay (see primary assay 2) after thawing the samples on ice.
Another example of an assay for the measurement of in vivo half-life of G-CSF
or vari-ants thereof is described in US 5,824,778.

Measurement of the in vivo biological activity in healthy rats of conjugated and non-conjugated hG-CSF and variants thereof Measurement of the in vivo biological effects of hG-CSF in SPF Sprague Dawley rats (purchased from M & B A/S, Denmark) is used to evaluate the biological efficacy of conjugated and non-conjugated G-CSF and variants thereof.

On the day of arrival the rats are randomly allocated into groups of 6. The animals are ac-climatized for a period of 7 days wherein individuals in poor condition or at extreme weights are rejected. The weight range of the rats at the start of the acclimatization period is 250-270g.
On the day of administration the rats are fasted for 16 hours followed by subcutaneous in-jection of 100 g per kg body weight of hG-CSF or a variant thereof. Each hG-CSF sample is injected into a group of 6 randomized rats. Blood samples of 300 l EDTA
stabilized blood are drawn from a tail vein of the rats prior to dosing and at 6, 12, 24, 36, 48, 72, 96, 120 and 144 hours after dosing. The blood samples are analyzed for the following haematological parameters:
Haemoglobin, red blood cell count, haematocrit, mean cell volume, mean cell haemoglobin con-1 o centration, mean cell haemoglobin, white blood cell count, differential leucocyte count (neutro-phils, lymphocytes, eosinophils, basophils, monocytes). On the basis of these measurements the biological efficacy of conjugated and non-conjugated hG-CSF and variants thereof is evalu-ated. Further examples of assays for the measurement of in vivo biological activity of hG-CSF
or variants thereof are described in US 5,681,720, US 5,795,968, US 5,824,778, US 5,985,265 and by Bowen et al., Experimental Hematology 27:425-432 (1999).

Measurement of the in vivo biological activity in rats with chemotherapy-induced neutropenia of conjugated and non-conjugated hG-CSF and variants thereof SPF Sprague Dawley rats were purchased from M & B A/S, Denmark. On the day of arri-val the rats are randomly allocated into groups of 6. The animals are acclimatized for a period of 7 days wherein individuals in poor condition or at extreme weights are rejected.
The weight range of the rats at the start of the acclimatization period is 250-270 g.
24 hours before administration of the hG-CSF samples the rats are injected i.p. with 50 or 90 mg per kg body weight of cyclophosphamide (CPA). The PEGylated hG-CSF
variants are given as a single dose injected s.c. at day 0, while non-conjugated hG-CSF is injected s.c. either in a single dose at day 0 or on a daily basis. For hG-CSF or variants given in a single dose at day 0, the dosage is 100 g per kg body weight. For non-conjugated hG-CSF (Neupogen ) given on a daily basis, the dosage varied and is given in the examples below. Each hG-CSF
sample is in-jected into a group of 6 randomized rats. Blood samples of 300 l EDTA
stabilized blood are 3o drawn from a tail vein of the rats prior to dosing and at 6, 12, 24, 36, 48, 72, 96, 120, 144 and 168 hours after dosing. The blood samples are analyzed for the following haematological parameters:
hemoglobin, red blood cell count, haematocrit, mean cell volume, mean cell haemoglobin concen-tration, mean cell haemoglobin, white blood cell count, differential leucocyte count (neutrophils, lymphocytes, eosinophils, basophils, monocytes). On the basis of these measurements the bio-logical efficacy of conjugated and non-conjugated hG-CSF and variants thereof is evaluated.
Determination ofpolypeptide receptor-binding affinity (on- and off-rate) 5 The strength of the binding between a receptor and ligand can be measured using an enzyme-linked immunoadsorption assay (ELISA), a radio-immunoassay (RIA), or other such immunodetection techniques well known in the art. The ligand-receptor binding interaction may also be measured with the Biacore instrument, which exploits plasmon resonance detec-tion (Zhou et al., Biochemistry, 1993, 32, 8193-98; Faegerstram and O'Shannessy, 1993, In 1o Handbook of Affinity Chromatography, 229-52, Marcel Dekker, Inc., NY).
The Biacore technology allows one to bind receptor to a gold surface and to flow ligand over it. Plasmon resonance detection gives direct quantification of the amount of mass bound to the surface in real time. This technique yields both on- and off-rate constants and thus a ligand-receptor dissociation constant and an affinity constant can be directly determined.

In vitro immunogenicity test of hG-CSF conjugates The reduced immunogenicity of a conjugate of the invention can be determined by use of an ELISA method measuring the immunoreactivity of the conjugate relative to a reference molecule or preparation. The reference molecule or preparation is normally a recombinant hu-man G-CSF preparation such as Neupogen or another recombinant human G-CSF
prepara-tion, e.g. an N-terminally PEGylated rhG-CSF molecule as described in US
5,824,784. The ELISA method is based on antibodies from patients treated with one of these recombinant G-CSF preparations. The immunogenicity is considered to be reduced when the conjugate of the invention has a statistically significant lower response in the assay than the reference mole-cule or preparation.

Neutralisation of activity in G-CSF bioassay The neutralisation of hG-CSF conjugates by anti-G-CSF sera is analyzed using the G-CSF bioassay described above.
Sera from patients treated with the G-CSF reference molecule or from immunized ani-mals are used. Sera are added either in a fixed concentration (dilution 1:20-1:500 (pt sera) or 20-1000 ng/ml (animal sera)) or in five-fold serial dilutions of sera starting at 1:20 (pt sera) or 1000 ng/ml (animal sera). HG-CSF conjugate is added either in seven fold-dilutions starting at nM or in a fixed concentration (1-100 pM) in a total volume of 8O 1 DMEM
medium +
10% FCS. The sera are incubated for 1 hr. at 37 C with hG-CSF conjugate.
The samples (0.01 ml) are then transferred to 96 well tissue culture plates containing NFS-60 cells in 0.1 ml DMEM media. The cultures are incubated for 48 hours at 37 C in a 5%
5 C02 air atmosphere. 0.01 ml WST-1 (WST-1 cell proliferation agent, Roche Diagnostics GmbH, Mannheim, Germany) is added to the cultures and incubated for 150 min.
at 37 C in a 5% CO2 air atmosphere. The cleavage of the tetrazolium salt WST-1 by mitochondrial dehy-drogenases in viable cells results in the formation of formazan that is quantified by measuring the absorbance at 450 nm.
10 When hG-CSF conjugate samples are titrated in the presence of a fixed amount of se-rum, the neutralising effect is defined as fold inhibition (Fl) quantified as EC50(with se-rum)/EC50(without serum). The reduction of antibody neutralisation of G-CSF
variant proteins is defined as (Fl variant -1) (1- )x100%
(Flwt-1) Construction and cloning of synthetic genes encoding hG-CSF

The following DNA fragments were synthesized following the general procedure de-scribed by Stemmer et al. (1995), Gene 164, pp. 49-53:
Fragment 1, consisting of a Bam HI digestion site, a sequence encoding the YAP3 sig-nal peptide (WO 98/32867), a sequence encoding the TA57 leader sequence (WO
98/32867), a sequence encoding a KEX2 protease recognition site (AAAAGA), a sequence encoding hG-CSF with its codon usage optimized for expression in E. coli, (SEQ ID NO:2) and a Xba I
digestion site.
Fragment 2, consisting of a Bam HI digestion site, a sequence encoding the YAP3 sig-nal peptide (WO 98/32867), a sequence encoding the TA57 leader sequence (WO
98/32867), a sequence encoding a histidine tag (SEQ ID NO:5), a sequence encoding a KEX2 protease rec-ognition site (AAAAGA), a sequence encoding hG-CSF with its codon usage optimized for expression in E. coli, (SEQ ID NO:2) and a Xba I digestion site.

Fragment 3, consisting of a Nde I digestion site, a sequence encoding the OmpA
signal peptide (SEQ ID NO:3), a sequence encoding hG-CSF with its codon usage optimized for ex-pression in E. coli, (SEQ ID NO:2) and a Bam HI digestion site.
Fragment 4, consisting of a Bam HI digestion site, the Kozak consensus sequence (Ko-zak, M. JMo1 Biol 1987 Aug 20;196(4):947-50), a sequence encoding the hG-CSF
signal pep-tide (SEQ ID NO:7) and hG-CSF with its codon usage optimized for expression in CHO cells (SEQ ID NO:8) and a Xba I digestion site.
DNA fragment 1 and 2 were inserted into the Bam HI and Xba I digestion sites in plas-mid pJSO37 (Okkels, Ann. New York Acad. Sci. 782:202-207, 1996) using standard DNA
io techniques. This resulted in plasmids pG-CSFcerevisiae and pHISG-CSFcerevisiae.
DNA fragment 3 was inserted into the Nde I and Bam HI digestion sites in plasmid pETl2a (Invitrogen) using standard DNA techniques. This resulted in plasmid pG-CSFcoli DNA fragment 4 was inserted into the Bam HI and Xba I digestion sites in plasmid pcDNA3.1(+) (Invitrogen) using standard DNA techniques. This resulted in plasmid pG-CSFCHO.

Expression of hG-CSF in S. cerevisiae and E. coli Transformation of Saccharomyces cerevisiae YNG318 (available from the American Type Culture Collection, VA, USA as ATCC 208973) with either plasmid pG-CSFcerevisiae or pHISG-CSFcerevisiae, isolation of transformants containing either of the two plasmids, and subsequent extracellular expression of hG-CSF without and with the HIS tag, respectively, was performed using standard techniques described in the literature.
Transformation of E. coli BL21 (DE3) (Novagen, Cat. No. 69387-3) with pG-CSFcoli, isolation of transformants con-taining the plasmid and subsequent expression of hG-CSF in the supernatant and in the perip-lasm of the cell was performed as described in the pET System Manual (8th edition) from No-vagen.
Expression of hG-CSF by S. cerevisiae and E. coli was verified by Western Blot analy-sis using the ImmunoPure Ultra-Sensitive ABC Rabbit IgG Staining kit (Pierce) and a poly-clonal antibody against hG-CSF (Pepro Tech EC Ltd.). It was observed that the protein had the correct size.

The expression levels of hG-CSF with and without the N-terminal histidine tag in S.
cerevisiae and E. coli were quantified using a commercially available G-CSF
specific ELISA
kit (Quantikine Human G-CSF Immunoassay, R&D Systems Cat. No. DCS50). The measured values are listed below.
Expression system Expression level (mg G-CSF per L) hG-CSF in S. cerevisiae 30 hG-CSF with histidine tag in S. cerevisiae 25 hG-CSF in E. coli 0.05 Generation of a stable CHO-KI G-CSF producer The day before transfection the CHO K1 cell line (ATCC #CC1-61) is seeded in a flask in 5 ml DMEM/F-12 medium (Gibco # 31330-038) supplemented with 10% FBS
and peni-cillin/streptomycin. The following day (at nearly 100% confluency) the transfection is prepared:
90 l DMEM medium without supplements is aliquoted into a 14 ml polypropylene tube (Corn-ing). 10 l Fugene 6 (Roche) is added directly into the medium and incubated for 5 min at room temperature. In the meantime 5 pg plasmid pG-CSFCHO is aliquoted into another 14 ml poly-propylene tube. After incubation the Fugene 6 mix is added directly to the DNA
solution and incubated for 15 min at room temperature. After incubation the whole volume is added drop-wise to the cell medium.
The next day the medium is exchanged with fresh medium containing 360 pg/ml hygro-mycin (Gibco). Every day hereafter the selection medium is renewed until the primary transfec-tion pool has reached 100% confluency. The primary transfection pool is sub-cloned by limited dilution (300 cells seeded in five 96-well plates).

Purification of hG-CSF and variants thereof from S. cerevisiae culture supernatants Purification of hG-CSF was performed as follows:

Cells are removed by centrifugation. Cell depleted supernatant is then filter sterilized through a 0.22 m filter. Filter sterilized supernatant is diluted 5 fold in 10mM sodium acetate pH 4.5. pH is adjusted by addition of 10 ml concentrated acetic acid per 5 liters of diluted su-pernatant. The ionic strength should be below 8mS/cm before application to the cation ex-change column.
Diluted supernatant is loaded at a linear flow rate of 90cm/h onto a SP-sepharose FF
(Pharmacia) column equilibrated with 50mM sodium acetate, pH 4.5 until the effluent from the column reaches a stable UV and conductivity baseline. To remove any unbound material, the column is washed using the equilibration buffer until the effluent from the column reaches a io stable level with respect to UV absorbance and conductivity. The bound G-CSF protein is eluted from the column using a linear gradient; 30 column volumes; 0-80%
buffer B (50mM
NaAc, pH 4.5, 750mM NaCl) at a flow rate of 45cm/h. Based on SDS-polyacryl amide gel electrophoresis, fractions containing G-CSF are pooled. Sodium chloride is added until the ionic strength of the solution is more than 80mS/cm.
The protein solution is applied onto a Phenyl Toyo Pearl 650S column equilibrated with 50mM NaAc, pH 4.5, 750mM NaCl. Any unbound material is washed off the column using the equilibration buffer. Elution of G-CSF is performed by applying a step gradient of MilliQ wa-ter. Fractions containing G-CSF are pooled. By using this 2-step down stream processing strat-egy, more than 90% pure G-CSF can be obtained. The purified protein is then quantified using spectrophotometric measurements at 280nm and/or by amino acid analysis.
Fractions containing G-CSF are pooled. Buffer exchange and concentration is per-formed using VivaSpin concentrators (mwco: 5kDa).

Identification and quantification of non-conjugated and conjugated hG-CSF and variants thereof SDS-PolyaMl Amide Gel Electrophoresis The purified, concentrated G-CSF was analyzed by SDS-PAGE. A single band having 3o an apparent molecular weight of approx. 17kDa was dominant.

Absorbance An estimate of the G-CSF concentration is obtained by spectrophotometric methods.
By measuring the absorbance at 280 nm and using a theoretically extinction coefficient of 0.83, the protein concentration can be calculated.

Amino Acid Analysis A more accurate protein determination can be obtained by amino acid analysis.
Amino acid analysis performed on a purified G-CSF revealed that the experimentally determined amino acid composition is in agreement with the expected amino acid composition based on 1 o the DNA sequence.

MALDI-TOF mass spectrometry of PEGylated wt G-CSF and G-CSF variants 15 MALDI-TOF mass spectrometry was used to evaluate the number of PEG-groups at-tached to PEGylated wt G-CSF and to selected PEGylated G-CSF variants.
Wt G-CSF contains 5 primary amines that are the expected attachment sites for SPA-PEG (the N-terminal amino-group and the c-amino-group on K16, K23, K34 and K40).
Following PEGylation of wt G-CSF with SPA-PEG 5000, MALDI-TOF mass spectrometry 20 showed the presence of species of wt G-CSF with mainly 4, 5 and 6 PEG-groups attached. In addition, wt G-CSF with 7 PEG-groups attached was clearly seen although in minor amounts.
The G-CSF variant having the substitutions K1 6R, K34R, K40R, Q70K, Q90K, and Q120K also contains 5 primary amines (the N-terminal amino-group and the F--amino-group on K23, K70, K90 and K120). Following PEGylation of this G-CSF variant with SPA-PEG5000, 25 MALDI-TOF mass spectrometry showed the presence of species of the G-CSF
variant with mainly 4, 5 and 6 PEG-groups attached. In addition, the G-CSF variant with 7 PEG-groups attached was clearly seen although in minor amounts.
The G-CSF variant having the substitutions K16R, K34R, and K40R contains 2 pri-mary amines (the N-terminal amino-group and the c-amino-group on K23).
Following PEGy1a-30 tion of this G-CSF variant with SPA-PEG 12000, MALDI-TOF mass spectrometry showed the presence of species of the G-CSF variant with mainly 2 and 3 PEG-groups attached. In addi-tion, the G-CSF variant with 4 PEG-groups attached was clearly seen although in minor amounts.

These observations clearly show that in addition to amino acid residues containing amine groups, other amino acid residues are sometimes PEGylated under the PEGylation con-ditions used. It also shows that it is of some importance for the PEGylation where amine groups are introduced. This has also been observed using SDS-PAGE analysis of wt G-CSF
and G-CSF variants.
As described in Example 12, it has been shown that histidine 170 is fully PEGylated when the SPA-PEG chemistry is used. Furthermore, K23 and S 159 are partly PEGylated. This explains the presence of 1-2 extra PEGylation sites besides the primary amines in hG-CSF and the variants that have been made.

Peptide mapping of PEGylated and non-PEGylated G-CSF variants In order to map the additional attachment sites for SPA-PEG on G-CSF and G-CSF
variants the following strategy was used.
A G-CSF variant with a low number of amine groups was chosen in order to reduce the number of expected PEGylation sites to a minimum. The G-CSF variant chosen has the substi-tutions K16R, K34R, K40R and H170Q. Apart from the s-amino-group on K23 that previous data had shown not to be PEGylated to any large extent, this variant only contains one primary amine at the N-terminal. Thus, the background PEGylation on amine groups is significantly reduced in this G-CSF variant. The G-CSF variant was PEGylated using SPA-PEG
5000. Fol-lowing PEGylation, the G-CSF variant was denatured, the disulphide bonds reduced, the result-ing thiol groups alkylated, and the alkylated and PEGylated protein degraded with a glutamic acid-specific protease. Finally, the resulting peptides were separated by reversed phase HPLC.
Parallel with this, the non-PEGylated version of the G-CSF variant with the substitu-tions K16R, K34R, and K40R was treated identically in order to create a reference HPLC
chromatogram.
Comparison of the HPLC chromatograms of the degradation of the PEGylated G-CSF
variant and the non-PEGylated G-CSF variant should then reveal which peptides disappear upon PEGylation. Identification of these peptides by N-terminal amino acid sequencing of the peptide from the non-PEGylated G-CSF variant then indirectly points to the positions that are PEGylated.

In principle, it would have been preferable to use the non-PEGylated version of the G-CSF variant having all the substitutions K16R, K34R, K40R and H170Q, but for all practi-cal purposes this does not matter.
More specifically, approximately 1 mg of the PEGylated G-CSF variant having the substitutions K16R, K34R, K40R and H170Q and approximately 500 g of the non-PEGylated G-CSF variant having the substitutions K1 6R, K34R, and K40R were dried in a SpeedVac concentrator. The two samples were each dissolved in 400 l 6 M guanidinium, 0.3 M Tris-HCI, pH 8.3 and denatured overnight at 37 C. Following denaturation, the disulfide bonds in the proteins were reduced by addition of 50 l0.1 M DTT in 6 M guanidinium, 0.3 M Tris-io HCI, pH 8.3. After 2 h of incubation at ambient temperature the thiol groups present were alky-lated by addition of 50 l 0.6 M iodoacetamid in 6 M guanidinium, 0.3 M Tris-HCI, pH 8.3.
Alkylation took place for 30 min at ambient temperature before the reduced and alkylated pro-teins were buffer changed into 50 mM NH4HCO3 using NAPS columns. The volumes of the samples were reduced to approximately 200 l in a SpeedVac concentrator before addition of 20 g and 10 g glutamic acid-specific protease, respectively. The degradations with glutamic acid-specific protease were carried out for 16 h at 37 C. The resulting peptides were separated by reversed phase HPLC employing a Phenomenex Jupiter C18 column (0.2 * 5 cm) eluted with a linear gradient of acetonitrile in 0.1 % aqueous TFA. The collected fractions were ana-lyzed by MALDI-TOF mass spectrometry and subsequently selected peptides were subjected to N-terminal amino acid sequence analysis.
Comparison of the HPLC chromatograms of the degradations of the PEGylated G-CSF
variant and the non-PEGylated G-CSF variant revealed that only two fractions disappear upon PEGylation. N-terminal amino acid sequence analysis of the two fractions from the non-PEGylated G-CSF variant showed that the peptides both were derived from the N-terminal of G-CSF. One peptide consisted of amino acid residues 1-11 generated by an unexpected cleav-age following Glnl 1. The other peptide consisted of amino acid residues 1-19 generated by an expected cleavage following Glu19.
It was expected that the N-terminal peptide of G-CSF would be identified using this approach, as the N-terminal amino group is easily PEGylated. However, none of the additional 3o attachment sites for SPA-PEG 5000 were identified using this approach.
An alternative to the indirect identification of PEG 5000 attachment sites is direct iden-tification of the attachment sites in PEGylated peptides. However, the fractions containing the PEGylated peptides in the HPLC separation of the degraded PEGylated G-CSF
variant are poorly separated from each other and from several fractions containing non-PEGylated pep-tides. Thus, N-terminal amino acid sequence analysis of these fractions did not result in any useful data except for an indication that K23 could be partially PEGylated.
To overcome these problems, two pools of PEGylated peptides were made from the fractions from the first HPLC separation. These two pools were dried in a SpeedVac concentra-tor, dissolved in 200 1 freshly prepared 50 mM NH4HCO3 and further degraded with I g of chymotrypsin. The resulting peptides were separated by reversed phase HPLC
employing a Phenomenex Jupiter C18 column (0.2 * 5 cm) eluted with a linear gradient of acetonitrile in 0.1 % aqueous TFA. The collected fractions were analyzed by MALDI-TOF mass spectrometry 1o and subsequently selected peptides were subjected to N-terminal amino acid sequence analysis.
From the N-terminal amino acid sequence determinations it could be determined that K23 as well as S159 are partially PEGylated. It was not possible to determine the exact degree of PEGylation at these two positions, but the PEGylation is only partial as peptides where K23 and S 159 are unmodified were identified and sequenced from the initial HPLC
separation.

Glycosylation of wt G-CSF and G-CSF variants A consistent observation when analyzing purified wt G-CSF and G-CSF variants by MALDI-TOF mass spectrometry is the presence of an additional component with a mass ap-proximately 324 Da larger than the mass of the G-CSF molecule analyzed. As the component with the lowest mass invariantly has the mass of the G-CSF molecule and because the G-CSF
molecules have the correct N-terminal amino acid sequence, it was concluded that the addi-tional component is a modified G-CSF molecule carrying two hexose residues. In many cases the unmodified G-CSF molecule gives rise to the most intense signal but in some cases the intensity of the signal for the modified G-CSF molecule is the most intense.
During the analysis of the peptides generated with the aim of identifying the additional PEGylation sites, two peptides of interest for identifying the site of glycosylation were identi-fied in each of the degradations.
In both HPLC separations, the two peptides elute next to each other and MALDI-TOF
mass spectrometry shows a mass difference between the two peptides of approximately 324 Da. The mass spectrometry data indicates that the peptide covers amino acid residues 124-162.
N-terminal amino acid sequence analysis of all four peptides showed that this assignment is correct and that Thr133 is the only site of modification. In the peptides with the mass of the unmodified peptide, Thr133 is clearly seen in the sequence, while no amino acid residue can be assigned at position 133 in the peptides with an additional mass of 324 Da. As all other amino acid residues could be assigned in the sequence, it was concluded that Thrl33 is the only site of modification. This glycosylation site was previously reported to be used in recombinant G-CSF expressed in CHO cells, although the glycan is different from the one attached by yeast.
The non-glycosylated wt G-CSF has been separated from the glycosylated wt G-CSF, employing reversed phase HPLC using a Vydac C18 column (0.21 * 5 cm) isocratically eluted with 51 % acetonitrile in 0.1 % TFA, as a fraction shown by MALDI-TOF mass spectrometry to only to contain the non-glycosylated form of wt G-CSF.

Separation of G-CSF molecules with different numbers of PEG molecules covalently attached Separation of G-CSF molecules covalently attached to 4, 5 or 6 PEG-groups was ob-tained as follows. PEGylated protein in 20mM sodium citrate, pH 2.5 was applied to an SP-sepharose FF column equilibrated with 20mM sodium citrate pH 2.5. Any unbound material was washed off the column. Elution was performed using a pH gradient.
PEGylated G-CSF
began to elute from the column at approx. pH 3.8 and continued to elute in fractions covering a pH span from 3.8 to 4.5.
The fractions were subjected to SDS-PAGE and mass spectrometric analysis.
These analyses indicate that G-CSF having the highest degree of PEGylation is located in the "low pH fractions". PEGylated G-CSF having a lower degree of PEGylation is eluted in the "high pH fractions".
Amino acid analysis performed on PEGylated G-CSF showed good consistency be-tween the theoretically and the experimentally determined extinction coefficient.

Construction of hG-CSF variants Specific substitutions of existing amino acids in hG-CSF to other amino acid residues, e.g. the specific substitutions discussed above in the general description, were introduced using standard DNA techniques known in the art. The new G-CSF variants were made using plasmid pG-CSFcerevisiae containing the gene, encoding hG-CSF without the HIS tag, as DNA tem-plate in the PCR reactions. The variants were expressed in S. cerevisiae and purified as de-scribed in Example 4. Some of the constructed G-CSF variants are listed below (see Examples 12 and 13).

Covalent attachment of SPA-PEG to hG-CSF or variants thereof Human G-CSF and variants thereof were covalently linked to SPA-PEG 5000, SPA-PEG 12000 and SPA-PEG 20000 (Shearwater) as described above ("PEGylation of 1o hG-CSF and variants thereof in solution"). The in vitro activities of the conjugates are listed in Example 13.

Identification of SPA-PEG attachment sites in G-CSF by site-directed mutagenesis followed by 15 PEGylation of the purified variants SPA-PEG may be attached to other amino acid residues than lysine in G-CSF. In order to determine whether SPA-PEG was attached to histidines, serines, threonines and arginines, variants were made in which these amino acids were substituted to lysine, alanine or glutamine.
20 The variants were expressed in S. cerevisiae, purified and PEGylated followed by analysis of the number of attached SPA-PEG molecules on SDS-PAGE. This analysis was performed by visual inspection of the SDS-PAGE gels, all of which contained three major bands. The degree of PEGylation was estimated to the nearest 5% for each band based on the relative size of the bands. A reduction in the number of attached SPA-PEG molecules after substitution of a given 25 amino acid with glutamine or alanine strongly indicates that this amino acid is PEGylated by SPA-PEG, and this observation is further supported by an unchanged degree of PEGylation after substitution of the amino acid to lysine. The analyzed variants are listed below.

G-CSF variant No. of attached PEG groups hG-CSF 10% 4 PEG, 75% 5 PEG, 15% 6 PEG
K23R 10% 4 PEG, 85% 5 PEG, 5% 6 PEG
H43Q 10% 4 PEG, 75% 5 PEG, 15% 6 PEG
H43K 10% 5 PEG, 75% 6 PEG, 15% 7 PEG
H52Q 10% 4 PEG, 75% 5 PEG, 15% 6 PEG
H52K 10% 5 PEG, 75% 6 PEG, 15% 7 PEG

H156Q 10% 4 PEG, 75% 5 PEG, 15% 6 PEG
H156K 10% 5 PEG, 75% 6 PEG, 15% 7 PEG
H170Q 10% 3 PEG, 75% 4 PEG, 15% 5 PEG
H170K 10% 4 PEG, 75% 5 PEG, 15% 6 PEG
K16/34R 10% 2 PEG, 75% 3 PEG, 15% 4 PEG
K16/34R R22K 10% 3 PEG, 75% 4 PEG, 15% 5 PEG
K16/34R R22Q 10% 2 PEG, 75% 3 PEG, 15% 4 PEG
K16/34R S142A 10% 2 PEG, 75% 3 PEG, 15% 4 PEG
K16/34/40R 10% 1 PEG, 75% 2 PEG, 15% 3 PEG
K16/34/40R S53K 10% 2 PEG, 75% 3 PEG, 15% 4 PEG
K16/34/40R S53A 10% 2 PEG, 75% 3 PEG, 15% 4 PEG
K16/34/40R S62K 10% 2 PEG, 75% 3 PEG, 15% 4 PEG
K16/34/40R S66K 10% 2 PEG, 75% 3 PEG, 15% 4 PEG
K16/34/40R S80K 10% 2 PEG, 75% 3 PEG, 15% 4 PEG
K16/34/40R T105K 10% 2 PEG, 75% 3 PEG, 15% 4 PEG
K16/34/40R T133K 10% 2 PEG, 75% 3 PEG, 15% 4 PEG
K16/34/40R S 142K 10% 2 PEG, 75% 3 PEG, 15% 4 PEG
K16/34/40R R147K 10% 2 PEG, 75% 3 PEG, 15% 4 PEG
K16/34/40R S155K 10% 2 PEG, 75% 3 PEG, 15% 4 PEG
K16/34/40R S159K 10% 2 PEG, 85% 3 PEG, 5% 4 PEG
K16/34/40R S170K 10% 1 PEG, 75% 2 PEG, 15% 3 PEG

The data show that besides the N-terminus, K16, K34 and K40, SPA-PEG also is cova-lently bound to H 170. Furthermore, the data show that only 10% of the available K23 amino acid residues are PEGylated, and that approximately 10% of S 159 is PEGylated.

In vitro biological activity of non-conjugated and conjugated hG-CSF and variants thereof The in vitro biological activities of conjugated and non-conjugated hG-CSF and vari-1 o ants thereof were measured as described above in "Primary assay 2 - in vitro hG-CSF activity assay". The in vitro bioactivities, represented by the measured EC50 values for each variant with and without conjugation of SPA-PEG 5000 to the available PEGylation sites, are listed below. The values have been normalized with respect to the EC50 value of non-conjugated hG-CSF (Neupogen ), i.e. the values in the table indicate % activity relative to the activity of non-conjugated hG-CSF. This value was measured simultaneously with the variants each time un-der identical assay conditions. The EC50 value of hG-CSF in the described assay is 30 pM.

EC50 (% of hG-CSF) EC50 (% of hG-CSF) G-CSF variant non-conjugated conjugated to G-CSF with N-terminal Histidine tag 10 Not determined G-CSF without N-terminal Histidine tag 100 0.1 23Q 80 0.1 23R 100 0.1 K1 6/34/40R E45K Expressed at low levels Not determined K16/34/40R S53K 5 0.5 K16/34/40R S62K 10 0.5 K16/34/40R Q67K 10 0.2 K16/34/40R S80K 10 0.2 K16/34/40R E98K Expressed at low levels Not determined K16/34/40R D104K 10 0.9 K16/34/40R Q131K Expressed at low levels Not determined K16/34/40R Q134K 10 0.2 K1 6/34/40R Q70K Q90K Not determined 20 K16/34/40R Q90K S159K 45 Not determined The data show that substitution of K23 to arginine does not increase the activity of the conjugated protein. This is due to the fact that only 10% of K23 is PEGylated, whereby the conjugated K23R variant has essentially the same number of PEG groups attached to it and has the same location of the PEGylation sites as hG-CSF. Removal of the remaining lysines at po-sition K16, K34 and K40 resulted in a G-CSF variant with significant activity after PEGyla-tion. Conjugation of SPA-PEG 5000 to this variant does not decrease the activity significantly as compared to the non-conjugated variant. Thus, PEGylation of the N-terminus and H170 with SPA-PEG 5000 (see Example 12) does not decrease the activity of hG-CSF. It was decided to 1o use hG-CSF K16R K34R K40R as the backbone for insertion of new PEGylation sites. 24 new PEGylation sites between residues L3 and H 159 were introduced in this backbone. These resi-dues are distributed over the parts of hG-CSF that do not interact with the G-CSF receptor.
Introduction of new PEGylation sites at positions L3, Q70, S76, Q90, T105, Q120, T133 and S 142 resulted in hG-CSF variants that retained a significant amount of activity after PEGyla-tion by SPA-PEG 5000. Thus, some of these new PEGylation sites were combined in hG-CSF
variants that had 2 or 3 new PEGylation sites.

Furthermore, SPA-PEG 12000 and SPA-PEG 20000 were attached to a group a se-lected hG-CSF variants. The in vitro activities are listed below (% of Neupogen ).

EC50 (% of hG-CSF) EC50 (% of hG-CSF) G-CSF variant conjugated to conjugated to K1 6/34/40R Q90K Not determined 7 K1 6/34/40R Q70K Q90K 8 Not determined K16/34/40R Q90K T105K 1 <1 K1 6/34/40R Q90K T105K S1 59K 1 <1 In vivo half-life of non-conjugated and conjugated hG-CSF and variants thereof The in vivo half-lives of non-conjugated hG-CSF (Neupogen ), SPA-PEG 5000 conju-gated hG-CSF K16R K34R K40R Q70K Q90K Q120K and SPA-PEG 5000 conjugated io hG-CSF K16R K34R K40R Q90K TI 05K S159K were measured as described above ("Meas-urement of the in vivo half-life of conjugated and non-conjugated rhG-CSF and variants thereof'). The results are shown in Figures 1 and 2. The in vivo half-life of Neupogen was determined to be 2.01 hours and 1.40 hours, respectively. In an earlier, similar experiment (US
5,824,778), the in vivo half-life of hG-CSF was determined to be 1.79 hours.
The results of the experiments described herein can therefore be directly compared to that experiment. The in vivo half-lives of SPA-PEG 5000 conjugated hG-CSF K16R K34R K40R Q70K Q90K

and SPA-PEG 5000 conjugated hG-CSF K16R K34R K40R Q90K T105K S 159K were deter-mined to be 12.15 hours and 16.10 hours, respectively. Thus, introducing new PEGylation sites in hG-CSF and conjugating SPA-PEG 5000 to them has resulted in a significant increase in the in vivo half-life.
In the earlier experiment described above (US 5,824,778), the in vivo half-life of hG-CSF conjugated to a larger N-terminally attached PEG molecule (10 kDa) was determined to be 7.05 hours. Thus, SPA-PEG 5000 conjugated hG-CSF K16R K34R K40R Q70K

Q120K and SPA-PEG 5000 conjugated hG-CSF K16R K34R K40R Q90K T105K S159K

have significantly longer half-lives than both Neupogen and hG-CSF with a 10 kDa N-terminally conjugated PEG molecule. SPA-PEG 5000 conjugated hG-CSF K16R K34R

Q70K Q90K Q120K and SPA-PEG 5000 conjugated hG-CSF K16R K34R K40R Q90K
T105K S159K both have three removed endogenous PEGylation sites and three new intro-duced PEGylation sites and thus are identical in size. The only difference between the two compounds is the in vitro activity, which is 12% and 5%, respectively, of that of Neupogen .
5 This difference results in a longer in vivo half-life of SPA-PEG 5000 conjugated K16R K34R
K40R Q90K T105K S159K compared to SPA-PEG 5000 conjugated K16R K34R K40R Q70K
Q90K Q120K. Since the in vitro activities correlate with the receptor binding affinities of the compounds, it can be concluded that the receptor-mediated clearance of SPA-PEG
5000 conju-gated K16R K34R K40R Q90K T105K S159K is slower than that of SPA-PEG 5000 conju-io gated K16R K34R K40R Q70K Q90K Q120K. Thus, a combination of increasing the size and reducing the in vitro activity of G-CSF results in G-CSF compounds with significantly longer in vivo half-lives than previously described compounds.

15 In vivo biological activity in healthy rats of non-conjugated and conjugated hG-CSF and vari-ants thereof The in vivo biological activities of non-conjugated hG-CSF (Neupogen ), SPA-PEG
5000 conjugated hG-CSF K16R K34R K40R Q70K Q120K, SPA-PEG 5000 conjugated 20 hG-CSF K16R K34R K40R Q70K Q90K Q120K, SPA-PEG 5000 conjugated hG-CSF K16R
K34R K40R Q70K Q120K T133K and SPA-PEG 5000 conjugated hG-CSF K16R K34R
K40R Q90K Q120K T133K were measured as described above ("Measurement of the in vivo biological activity in healthy rats of conjugated and non-conjugated hG-CSF
and variants thereof'). The results are shown in Figures 3 and 4.
25 No activity of Neupogen could be detected at 48 hours after injection of 100 g per kg body weight at t=0 hours. Activity of SPA-PEG 5000 conjugated hG-CSF K16R

K40R Q70K Q120K, SPA-PEG 5000 conjugated hG-CSF K16R K34R K40R Q70K Q120K
T133K and SPA-PEG 5000 conjugated hG-CSF K16R K34R K40R Q90K Q120K T133K
could be detected until 72 hours after the initial injection, while SPA-PEG
5000 conjugated 3o hG-CSF K16R K34R K40R Q70K Q90K Q120K remained active in vivo until 96 hours after the initial injection. Thus, it was shown that all of these conjugated variants had a longer in vivo biological activity than Neupogen and that SPA-PEG 5000 conjugated hG-K34R K40R Q70K Q90K Q120K remained active twice as long in vivo as Neupogen .
SPA-PEG 5000 conjugated hG-CSF K16R K34R K40R Q70K Q120K T133K and SPA-PEG 5000 conjugated hG-CSF K16R K34R K40R Q90K Q120K T133K, both with an in vitro activity of 2% of Neupogen (Example 13), did not induce the same level of white blood cell formation during the initial 12 hours after administration as observed after administration of Neupogen , SPA-PEG 5000 conjugated hG-CSF K16R K34R K40R Q70K Q120K and SPA-PEG 5000 conjugated hG-CSF K16R K34R K40R Q70K Q90K Q120K. Thus, the compounds with an in vitro activity of 2% or less compared to that of Neupogen were unable to stimulate full for-mation of white blood cells immediately after administration.

Furthermore, the in vivo biological activities of Neupogen , SPA-PEG 12000 conju-io gated hG-CSF K16R K34R K40R and different doses of SPA-PEG 5000 conjugated hG-CSF
K16R K34R K40R Q70K Q90K Q120K were measured as described above ("Measurement of the in vivo biological activity in healthy rats of conjugated and non-conjugated hG-CSF and variants thereof'). The results are shown in Figure 5. As observed earlier, no activity of Neu-pogen could be detected 48 hours after the initial injection of 100 g per kg body weight.

Administration of 5 pg per kg body weight of SPA-PEG 5000 conjugated hG-CSF

K34R K40R Q70K Q90K Q120K resulted in a slightly longer in vivo biological activity than Neupogen , while administration of 25 pg per kg body weight and 100 g per kg body weight of this compound resulted in hG-CSF activity until 72 and 96 hours, respectively, after the ini-tial injection. Thus, the duration of action of the SPA-PEG conjugated hG-CSF
compounds can be controlled by increasing or decreasing the standard dosing regimen. SPA-PEG
12000 con-jugated hG-CSF K16R K34R K40R remained active in vivo until 72 hours after administration of 100 g per kg body weight. As described in Example 6, SPA-PEG 12000 conjugated hG-CSF K16R K34R K40R has 2 or 3 SPA-PEG 12000 groups attached while SPA-PEG

conjugated hG-CSF K16R K34R K40R Q70K Q90K Q120K has 5 or 6 SPA-PEG 5000 groups attached. Thus, the molecular weights of the two compounds are 42-54 kDa and 43-48 kDa, respectively. The in vitro activities of the two compounds are 30% and 12%, respectively, of that of Neupogen . The longer in vivo biological activity of SPA-PEG 5000 conjugated hG-CSF K16R K34R K40R Q70K Q90K Q120K as compared to SPA-PEG 12000 conjugated hG-CSF K16R K34R K40R with essentially the same molecular weight suggests that when the size of the G-CSF compounds is increased above a certain molecular weight through PEG-ylation, the duration of action can only be increased further by reducing the specific activity of the G-CSF compounds and thus, the receptor-mediated clearance (see Example 14).

Furthermore, the in vivo biological activities of Neupogen , SPA-PEG 5000 conju-gated hG-CSF K16R K34R K40R Q70K Q90K Q120K, SPA-PEG 5000 conjugated hG-CSF
K16R 34R 40R Q90K T105K S159K and SPA-PEG 20000 conjugated hG-CSF K16R 34R
40R TI 05K S 159K were measured as described above ("Measurement of the in vivo biological activity in healthy rats of conjugated and non-conjugated hG-CSF and variants thereof'). The results are shown in Figure 6.
As observed earlier, the conjugated hG-CSF variants had a significant longer duration of action than Neupogen . Administration of each of these three conjugated hG-CSF variants resulted in formation of white blood cells at the same rate and to the same level as observed io after administration of Neupogen during the initial 12 hours after administration. The in vitro activities of SPA-PEG 5000 conjugated hG-CSF K16R K34R K40R Q70K Q90K Q120K, SPA-PEG 5000 conjugated hG-CSF K16R 34R 40R Q90K TI 05K S159K and SPA-PEG
20000 conjugated hG-CSF K1 6R 34R 40R T1 05K S159K are 12%, 5% and 5%, respectively, of that of Neupogen , and thus, a hG-CSF compound with 5% of Neupogen activity in vitro is able to induce full white blood cell formation after administration.

The apparent size on SDS-PAGE of Neupogen , SPA-PEG 5000 conjugated hG-CSF
K16R K34R K40R Q70K Q90K Q120K, SPA-PEG 5000 conjugated hG-CSF K16R 34R 40R
Q90K T105K S159K and SPA-PEG 20000 conjugated hG-CSF K16R 34R 40R T1 05K S159K
is 18 kDa, 60 kDa, 60 kDa and >100 kDa, respectively. SPA-PEG 5000 conjugated hG-CSF
K16R 34R 40R Q90K T105K S159K and SPA-PEG 20000 conjugated hG-CSF K16R 34R
40R TI 05K S 159K have almost identical durations of action in vivo, showing that the duration of action is not increased by increasing the molecular size of the conjugated hG-CSF com-pounds above an apparent size of about 60 kDa. Instead, when the apparent size of the conju-gated hG-CSF compounds is above about 60 kDa, the duration of action may be increased be reducing the in vitro activity and hence, the receptor binding affinity of the compound. An ad-ditional example of this (see above) can be observed by comparing the in vivo duration of ac-tion of SPA-PEG 5000 conjugated hG-CSF K16R 34R 40R Q70K Q90K Q120K and SPA-PEG 5000 conjugated hG-CSF K16R 34R 40R Q90K T105K S159K. The two compounds both have an apparent size of 60 kDa, while the in vitro activities are 12%
and 5%, respec-tively. This difference is reflected directly in the in vivo duration of action of the two com-pounds, which is 96 hours and 144 hours, respectively.

In vivo biological activity in rats with chemotherapy-induced neutropenia of non-conjugated and conjugated hG-CSF and variants thereof The in vivo biological activities in rats with chemotherapy-induced neutropenia of non-conjugated hG-CSF (Neupogen ), SPA-PEG 5000 conjugated hG-CSF K16R K34R
K40R Q70K Q90K T105K and SPA-PEG 20000 conjugated hG-CSF K16R K34R K40R
Q90K were measured as described above ("Measurement of the in vivo biological activity in rats with chemotherapy-induced neutropenia of conjugated and non-conjugated hG-CSF and io variants thereof') using 50 mg per kg body weight of CPA and a single dose (100 g per kg body weight) of G-CSF. The results are shown in Figure 7. The three compounds induced an initial formation of white blood cells with identical rates. Thus, an in vitro activity of 4% of that of Neupogen is sufficient for a conjugated hG-CSF compound to give full stimulation of white blood cell formation in vivo immediately after administration. After 36 hours the number of white blood cells (WBC) in the Neupogen -treated rats dropped to the level that was ob-served in the untreated group (<3x109 cells per litre). At this point the rats were neutropenic.
The level of WBC in both groups reached normal levels (9x109 cells per litre) after 144 hours.
The level of WBC in the two groups treated with SPA-PEG 5000 conjugated hG-CSF K16R K34R K40R Q70K Q90K T105K and SPA-PEG 20000 conjugated hG-CSF
K1 6R K34R K40R Q90K dropped to a minimum of 4x109 cells per litre after 48 hours and then immediately started to increase. The WBC levels in both groups were back to normal after 96 hours. Thus, the two conjugated hG-CSF compounds were able to both relieve the degree of neutropenia and to reduce the time until the WBC levels were back to normal (the duration of neutropenia) significantly from 112 hours in the Neupogen -treated group to 48 hours in the groups treated with either SPA-PEG 5000 conjugated hG-CSF K16R K34R K40R Q70K
Q90K T105K and SPA-PEG 20000 conjugated hG-CSF K16R K34R K40R Q90K.
SPA-PEG 5000 conjugated hG-CSF K16R K34R K40R Q70K Q90K T105K
more efficiently shortened the duration of neutropenia as compared to SPA-PEG
20000 conju-gated hG-CSF K16R K34R K40R Q90K. Since the apparent size of both molecules is above 60 kDa (60 kDa and 80 kDa, respectively ) this cannot be explained by a lower renal clearance of SPA-PEG 5000 conjugated hG-CSF K16R K34R K40R Q70K Q90K T105K than SPA-PEG 20000 conjugated hG-CSF K1 6R K34R K40R Q90K. The in vitro activity of SPA-PEG
5000 conjugated hG-CSF K16R K34R K40R Q70K Q90K T105K and SPA-PEG 20000 con-jugated hG-CSF K16R K34R K40R Q90K are 4% and 7% of Neupogen , respectively.
This means that the receptor binding affinity and thus, the receptor-mediated clearance, of SPA-PEG 5000 conjugated hG-CSF K16R K34R K40R Q70K Q90K T105K is lower than for SPA-PEG 20000 conjugated hG-CSF K16R K34R K40R Q90K in the initial 48 hours after admini-s stration where the white blood cell levels are increased. Hence, when the rats become neutro-penic after 48 hours, the in vivo concentration of SPA-PEG 5000 conjugated hG-K34R K40R Q70K Q90K TI 05K is higher than SPA-PEG 20000 conjugated hG-CSF K16R
K34R K40R Q90K. Since a relatively low in vitro G-CSF activity of 4-5% of that of Neupo-gen is sufficient to obtain full activation of the G-CSF receptors on the neutrophil progenitor 1o cells (see above), this higher G-CSF concentration after 48 hours explains the faster increase in WBC levels in the SPA-PEG 5000 conjugated hG-CSF K16R K34R K40R Q70K Q90K
T 1 05K-treated group. Thus, in rats with chemotherapy-induced neutropenia, a conjugated G-CSF compound of the invention with an apparent size of at least about 60 kDa and an in vitro activity of 4% of that of Neupogen is superior to similar size compounds with a higher 15 in vitro activity.

Purification of G-CSF from S. cerevisiae culture supernatants 20 This example provides an alternative purification procedure to that of Example 4 for purification of hG-CSF and G-CSF variants.
Cells are removed by centrifugation, 5000 rpm, 10 min, 4 C, and the clarified supernatant is filtered through a 0.22 m filter. The clarified and filtered supernatant is concen-trated and diafiltered into 50 mM sodium acetate, pH 4.5, by Tangential Flow Filtration using 25 10 kDa membranes.
The resulting ultra filtrate is applied onto an SP-sepharose column (200 ml packed bed) equilibrated with at least 5 column volumes of 50 mM sodium acetate. Samples are loaded at a flow rate of approx. 20 ml/min. The column is washed using the equilibration buffer until a stable effluent is obtained as determined by absorbance at 280 rim. Using a step-30 wise buffer gradient (e.g. 10%, 20%, 30% and 35% buffer), G-CSF is eluted at 35% buffer at ambient flow rate, where the buffer is 750 mM NaCl in 50 mM sodium acetate.
This one-step method yields >95% pure G-CSF (as determined by SDS-PAGE).

Separation of multi-PEGylated species of G-CSF

Example 9 above describes a method for separation of G-CSF molecules with 5 different numbers of PEG groups attached. This example provides an alternative procedure for separation of such multi-PEGylated G-CSF species in order to obtain a G-CSF
product with a desired degree of uniformity in terms of the number of attached PEG groups.
A mixture of PEGylated G-CSF, covalently linked to e.g. SPA-PEG 5000 (Shearwater) as described above ("PEGylation of hG-CSF and variants thereof in solution"), is io diluted with 20mM citrate buffer, pH 2.5. The conductivity should be < 3.5 mS/cm. The pH is adjusted to 2.5 as necessary using dilute HCI. The following buffers are used for the separa-tion:
Buffer A: 20 mM sodium citrate, pH 2.5 (equilibration and washing buffer).
Buffer B: 20 mM sodium citrate, pH 2.5; 750 mM sodium chloride (elution buffer) 15 The sample to be separated is loaded onto an equilibrated SP-sepharose HP
col-umn (7 ml) at a flow rate of 2 ml/min. The column is washed with Buffer A
until a stable base-line is obtained as monitored by A280.
Multi-PEGylated species are separated by applying a linear gradient of 0-50%
Buffer B for 180 minutes at a flow rate of 4 ml/min and collecting 2 ml fractions. The collected 20 fraction are analyzed by SDS-PAGE, and fractions having a desired number of attached PEG
groups are pooled. This allows purification of a PEGylated G-CSF mixture comprising species initially having, e.g., 3-6 attached PEG groups to result in a product having e.g. only 4 or 5 PEG groups attached, or a product having only a single number of attached PEG
groups.

Peptide mapping Using a similar procedure to that described above in Example 7, but based on degradation with trypsin, the PEGylation pattern of a G-CSF conjugate of the invention was 3o determined by peptide mapping. In this case, the polypeptide was produced in CHO cells (see Example 3) and had the substitutions K1 6R, K34R, K40R, TI 05K and S159K
relative to the sequence of native human G-CSF. It was PEGylated with 5 kDa SPA-PEG as described above, resulting in modified proteins carrying predominantly 3, 4 or 5 PEG moieties, and to a small extent 6 PEG moieties. Five of the six possible PEG attachment sites are known, these being the N-terminal amino group, Lys23, Lysl05, Lys159 and Hisl70.
This peptide mapping analysis showed that the conjugated protein was essentially fully PEGylated at the N-terminal and at Lys105 and Lys 159, while Lys23 was partially PEG-ylated. Although His 170 has been shown to be partially PEGylated in previous experiments, this was surprisingly not found in this experiment. One possible explanation for this observa-tion is that the bond between the PEG and the His 170 residue may be unstable during the sam-ple preparation carried out prior to the peptide mapping. A possible unstable PEGylation such as may be the case here may be avoided by substituting the histidine residue with another resi-1 o due, in particular a lysine residue if a more stable PEGylation is desired, or a glutamine or ar-ginine residue if PEGylation is to be avoided.

In vivo biological activity in rats with chemotherapy-induced neutropenia The in vivo biological activity of two PEGylated G-CSF variants of the invention was tested in rats with chemotherapy-induced neutropenia. The variants had, relative to SEQ
ID NO:1, the amino acid substitutions K16R, K34R, K40R, T105K and S159K
(referred to below as "105/159") and K16R, K34R, K40R, Q90K, TI 05K and S159K (referred to as "90/105/159"), respectively. Both variants were produced in yeast (S.
cerevisiae) and were conjugated with SPA-PEG-5000 as described above. The in vivo biological activity of a single dose of the two variants was tested against the activity of daily doses of non-conjugated hG-CSF (Neupogen ) and a control (vehicle).
24 hours before administration of the G-CSF samples, the rats were given 50 mg per kg body weight of CPA. The PEGylated variants of the invention were administered as a sin-gle dose of 100 g per kg body weight at time 0, while Neupogen was administered in daily doses of 30 gg per kg body weight for 5 days (from 0 hours to 96 hours).
The in vivo biological activity was measured as described above ("Measurement of the in vivo biological activity in rats with chemotherapy-induced neutropenia of conjugated 3o and non-conjugated hG-CSF and variants thereof'). The results are shown in Figure 8 (white blood cell count, WBC) and in Figure 9 (absolute neutrophil count, ANC).

As seen in Figure 8, administration of 105/159, 90/105/159 and Neupogen all resulted in an initial increase in white blood cell levels in the first 12 hours, after which the white blood cell levels fell as a result of the chemotherapy, reaching a minimum after about 48 hours. After 48 hours, the numbers of white blood cells increased for all three treatment groups, although the rate of increase was clearly greater for the group treated with the two PE-Gylated variants of the invention than for the group treated with Neupogen .
Treatment with the PEGylated variants 105/159 and 90/105/159 resulted in a normal level of white blood cells (over 10x109/1) after 96 hours, while the Neupogen treated group still had a white blood cell level under 10x109/1 after 120 hours. Since the last of the five daily Neupogen treatments was given at 96 hours, the white blood cell level in this group fell again after 120 hours. In contrast, the white blood cell level in the two groups treated with a single dose of the PEGylated vari-io ants of the invention was relatively stable at just over 1 Ox 109/1 from 96 hours and for the dura-tion of the experiment until 216 hours.
A similar pattern for the numbers of neutrophils is seen in Figure 9, which shows that the neutrophil level for the group treated with the PEGylated variant 105/159 increased significantly faster than for the group treated with Neupogen (ANC was not determined for the 90/105/159 group).

In vivo biological activity in rats with chemotherapy-induced neutropenia The in vivo biological activities of non-conjugated hG-CSF (Neupogen ) and hG-CSF with a single N-terminally linked 20 kDa PEG group (NeulastaTM) were compared to two PEGylated G-CSF variants of the invention in rats with chemotherapy-induced neutro-penia. These two variants, which were produced in yeast (S. cerevisiae) and CHO cells, respec-tively, had the same amino acid substitutions relative to the sequence of hG-CSF, namely K16R, K34R, K40R, T105K and S159K, and were conjugated to SPA-PEG 5000. The PEG-ylated variants of the invention, which initially consisted of multi-PEGylated species having 3-6 PEG moieties attached, were separated to give a more uniform product having only 4-5 PEG moieties attached. These variants are referred to below as "G20" (produced in yeast) and "G21" (produced in CHO cells).
The G-CSF samples were administered 24 hours after administration of CPA (90 mg per kg body weight). The PEGylated variants, i.e. NeulastaTM, G20 and G21, were adminis-tered as a single dose of 100 g per kg body weight, while Neupogen was administered in daily doses of 10 gg per kg body weight for seven days.

The in vivo biological activity was measured as described above ("Measurement of the in vivo biological activity in rats with chemotherapy-induced neutropenia of conjugated and non-conjugated hG-CSF and variants thereof'). The results are shown in Figure 10 (white blood cell count, WBC) and Figure 11 (absolute neutrophil count, ANC).
Figures 10 and 11 show that all of the G-CSF compounds induced an initial formation of white blood cells and neutrophils at approximately identical rates during the first 12 hours, after which the levels of white blood cells and neutrophils fell as a result of the chemotherapy. After 96 hours, the levels of white blood cells and neutrophils increased once again in all cases, but the rate of increase was significantly higher for rats treated with G20 or to G21 than for rats treated with either Neupogen or NeulastaTM. Figure 10 shows that the white blood cell levels of rats treated with G20 or G21 reached a normal level of approximately 109/1 after 144 hours, while the rats treated with Neupogen or NeulastaTM did not reach this level until after 168 hours. As shown in Figure 11, the same pattern is seen when looking at the neutrophil count, i.e. the neutrophil count of rats treated with G20 or G21 reach a normal level approximately 24 hours before rats treated with Neupogen or NeulastaTM reach a similar level. It may thus be concluded that these PEGylated G-CSF variants of the invention are able to reduce the duration of chemotherapy-induced neutropenia in rats by about 24 hours compared to treatment with the currently available G-CSF products Neupogen and NeulastaTM.

SEQUENCE LISTING
<110> Maxygen Holdings Ltd.

<120> G-CSF conjugates <130> 0258 <150> US 09/904,196 <151> 2001-07-11 <150> DK PA 2002 00447 <151> 2002-03-22 <150> DK PA 2002 00708 <151> 2002-05-08 <160> 15 <170> Patentln version 3.1 <210> 1 <211> 174 <212> PRT
<213> Homo sapiens <400> 1 Thr Pro Leu Gly Pro Ala Ser Ser Leu Pro Gln Ser Phe Leu Leu Lys Cys Leu Glu Gln Val Arg Lys Ile Gln Gly Asp Gly Ala Ala Leu Gln Glu Lys Leu Cys Ala Thr Tyr Lys Leu Cys His Pro Glu Glu Leu Val Leu Leu Gly His Ser Leu Gly Ile Pro Trp Ala Pro Leu Ser Ser Cys Pro Ser Gln Ala Leu Gln Leu Ala Gly Cys Leu Ser Gln Leu His Her Gly Leu Phe Leu Tyr Gln Gly Leu Leu Gln Ala Leu Glu Gly Ile Ser Pro Glu Leu Gly Pro Thr Leu Asp Thr Leu Gln Leu Asp Val Ala Asp Phe Ala Thr Thr Ile Trp Gln Gln Met Glu Glu Leu Gly Met Ala Pro Ala Leu Gln Pro Thr Gln Gly Ala Met Pro Ala Phe Ala Ser Ala Phe Gln Arg Arg Ala Gly Gly Val Leu Val Ala Ser His Leu Gln Ser Phe Leu Glu Val Ser Tyr Arg Val Leu Arg His Leu Ala Gln Pro <210> 2 <211> 525 <212> DNA
<213> Artificial <220>
<221> misc feature <223> DNA sequence encoding hG-CSF, with codon usage for E. coli <400> 2 acccctctgg gcccggccag cagtctgcct cagagttttt tactgaaatg cttagaacag 60 gtgcgtaaaa tccagggcga tggcgcggcc ctgcaggaaa aactgtgcgc gacctataaa 120 ctgtgccatc ctgaagaact ggtcctgtta ggccatagct taggcatccc gtgggcgcct 180 ctgagtagct gcccgagtca ggccctgcag ctggccggct gcctgagtca gttacatagt 240 ggcttatttt tatatcaggg cttactgcag gcgttagaag gcattagtcc ggaactgggc 300 ccgaccctgg ataccttaca gttagatgtc gcggattttg ccaccaccat ttggcagcag 360 atggaagaat taggcatggc gcctgcgtta cagcctaccc agggcgccat gcctgcgttt 420 gcgagtgcgt ttcagcgtcg cgccggcggc gtgttagtgg ccagccatct gcagagcttt 480 ctggaagtga gttatcgtgt gttacgccat ctggcccagc cttaa 525 <210> 3 <211> 21 <212> PRT
<213> Escherichia coli <400> 3 Met Lys Lys Thr Ala Ile Ala Ile Ala Val Ala Leu Ala Gly Phe Ala Thr Val Ala Gln Ala <210> 4 <211> 63 <212> DNA

<213> Artificial <220>
<221> misc feature <223> DNA sequence encoding the OmpA signal sequence <400> 4 atgaaaaaga cagctatcgc gattgcagtg gcactggctg gtttcgctac cgtagcgcag 60 gcc 63 <210> 5 <211> 15 <212> PRT
<213> Artificial <220>
<221> PEPTIDE
<222> (1)..(15) <223> Synthetic tag <400> 5 Met Lys His Gln His Gln His Gln His Gln His Gln His Gln Gln <210> 6 <211> 45 <212> DNA
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<213> Homo sapiens <220>
<221> SIGNAL
<222> (1)..(30) <223>

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Claims (17)

THE EMBODIMENTS OF THE INVENTION FOR WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A polypeptide conjugate exhibiting granulocyte colony stimulating factor (G-CSF) activity, comprising a polypeptide with an amino acid sequence that differs in up to 15 amino acid residues from the amino acid sequence of hG-CSF shown in SEQ ID
NO:1, the polypeptide comprising the substitutions K16R, K34R, K40R, T105K and S159K relative to the amino acid sequence of hG-CSF shown in SEQ ID NO:1, the conjugate having 2-6 polyethylene glycol moieties with a molecular weight of about 1000-about 10,000 Da attached to attachment groups of the polypeptide.

2. The polypeptide conjugate of claim 1, further comprising the substitution H170K, H170Q or H170R.

3. The polypeptide conjugate of claim 1 or 2, wherein the amino acid sequence of the polypeptide differs in up to 10 amino acid residues from SEQ ID NO:1.

4. The polypeptide conjugate of claim 3, wherein the amino acid sequence of the polypeptide differs in up to 8 amino acid residues from SEQ ID NO:1.

5. The polypeptide conjugate of any one of claims 1 to 4, wherein at least one of the polyethylene glycol moieties is attached to a lysine residue.

6. The polypeptide conjugate of claim 5, wherein a polyethylene glycol moiety is attached to the N-terminal amino group.

7. The polypeptide conjugate of any one of claims 1 to 6, which is glycosylated at T133.

8. The polypeptide conjugate of any one of claims 1 to 7, having 3-5 attached polyethylene glycol moieties.

9. The polypeptide conjugate of claim 8, having 3-5 polyethylene glycol moieties with a molecular weight of about 5000-about 6000 Da attached.

10. The polypeptide conjugate of claim 9, having 3 polyethylene glycol moieties of about kDa attached.

11. The polypeptide conjugate of any one of claims 1 to 10, having an in vitro bioactivity in the range of about 2 to about 30% of the bioactivity of non-conjugated hG-CSF as determined by an in vitro G-CSF activity assay.

12. A composition comprising the polypeptide conjugate of any one of claims 1 to 11 and at least one pharmaceutically acceptable carrier or excipient.

13. The polypeptide conjugate of any one of claims 1 to 11 for use as a pharmaceutical.

14. Use of the polypeptide conjugate of any one of claims 1 to 11 for the preparation of a pharmaceutical composition for the treatment of an insufficient neutrophil level.

15. Use according to claim 14, wherein the pharmaceutical composition is for the prevention and/or treatment of neutropenia due to chemotherapy or radiation therapy.

16. Use of an effective amount of the polypeptide conjugate of any one of claims 1 to 11 for the treatment of an insufficient neutrophil level.

17. Use according to claim 16, wherein the insufficient neutrophil level is due to chemotherapy or radiation therapy.