WO2006081249A2 - Conjugates of biologically active proteins having a modified in vivo half-life - Google Patents

Abstract

Disclosed are biologically active protein conjugates that comprise a biologically active polypeptide coupled via a peptide bond to a polypeptide comprising from 2 to about 500 units of a repeating peptide motif, wherein the biologically active protein conjugate exhibits a modified plasma half-life compared to the intrinsic half-life of the unconjugated biologically active polypeptide or protein. Also disclosed are methods of making and using the conjugated proteins, as well as methods for determining whether a given conjugate exhibits a modified half life relative to the intrinsic half life of the unconjugated polypeptide.

Description

BIOLOGICALLY ACTIVE PROTEINS HAVING A MODIFIED IN VIVO HALF-LIFE

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority under 35 U . S . C 119 (e) from United States Application No . 60/712 , 585, filed August 30 , 2005 and United States Application No . 60/647 , 119, filed January 25, 2005, the contents of which are incorporated by reference .

TECHNICAL FIELD

[0002] This invention relates generally to biologically active proteins , and more specifically to altering the half- life of biologically active proteins .

BACKGROUND OF THE INVENTION

[0003] Biologically active proteins often have undesirable half-lives when administered as human therapeutics . Their intrinsic half-lives impose administration schedules and dosing regimens that often result in less than optimal therapeutic efficacy, compliance problems and patient inconvenience .

[0004] In the manufacture of biologically active proteins for human therapeutics , the extension of the half-life of biologically active proteins has been attempted through physical means ( e . g. , altered route of administration, nanoparticle encapsulation and liposomal entrapment) , chemical modification ( e . g. , emulsions , pegylation and hyperglycosylation) and genetic modification ( e . g. , modification of primary protein structure, polymer tags , human serum albumin fusion, incorporation of post-translational modification) . See, for example, Lord, et al . , Clin . Cancer Res . 7: 2085-2090 ( 2001 ) , and van Der Auwera, et al . , Am. J. Hematol . 66: 245-251 (2001 ) . However, such approaches have resulted in other problems . Extension of biologically active protein half-life through physical means often introduces increased drug substance complexity with costly and time- consuming additional downstream processes during manufacturing . Chemical modification may alter the biological activity or safety profile of the biologically active protein . Where biologically active proteins are made via recombinant DNA synthesis methodology, the effect of the genetic modification on protein yield and purity in the particular cellular expression systems issues needs to be assessed for its intended use .

[0005] Accordingly, there is a need for other approaches for modifying the intrinsic half-life of biologically active proteins .

SUMMARY OF THE INVENTION

[0006] One aspect of the present invention is directed to a protein conj ugate comprising a biologically active polypeptide coupled via a peptide bond to a polypeptide (amino acid extension) that comprises from 2 to about 500 repeating units of a peptide motif . The motif comprises a maj or constituent and a minor constituent , in which the maj or constituent is two or more residues of one amino acid selected from GIy (G) , Asn

(N) and GIn (Q) , and the minor constituent is one or more residues of one amino acid selected from Ala (A) , Ser ( S ) , Thr

(T ) , Asp ( D) , GIn (Q) , GIu (E) , His (H) and Asn (N) , with the proviso that none of the amino acids is present in both the maj or constituent and said minor constituent, wherein the plasma half-life of the conjugate is modified relative to the intrinsic half-life of the unconj ugated biologically active polypeptide . The term "modified" , as used herein, refers to an increased or a decreased half-life relative to the plasma half-life of the unconjugated biologically active polypeptide or protein itself ( i . e . , the intrinsic half life) . By the phrase "intrinsic half-life" it is meant the half-life of the native biologically active polypeptide or the half-life of the polypeptide in unconj ugated form (thus including recombinant forms of the native polypeptide) .

[0007] In some embodiments , the peptide motif comprises 3-6 amino acid residues ( i . e . , 3 , 4 , 5 or 6) . In some embodiments , wherein the peptide motif contains 5 or 6 amino acid residues , the minor constituent comprises 1 amino acid residue of said peptide . In some embodiments , the peptide motif has a sequence consisting of N and T amino acid residues, N and E amino acid residues, Q and S amino acid residues , or N and Q amino acid residues . In some embodiments , the amino acid extension is N-terminal with respect to said biologically active polypeptide; in some embodiments , it is C-terminal with respect to said biologically active polypeptide; and in other embodiments , it is situated at both the N and C-terminus with respect to said biologically active polypeptide . In some embodiments , the biologically active polypeptide is a cytokine ( e . g. , granulocyte colony stimulating factor (G-CSF) , human growth hormone , or an interferon such as a beta-interferon or a gamma-interferon) , an antibody, antibody fragment, proteolytic antibody fragment or domain, single chain antibody, genetically or chemically optimized antibody or fragment thereof, a soluble gpl20 or gplβO glycoprotein, a coagulation factor, a soluble receptor such as a tumor necrosis factor

(TNF) -α type II receptor, a therapeutic enzyme or erythropoietin (EPO) . In some embodiments, the protein conj ugate has a modified half-life that is decreased relative to the intrinsic half-life of the unconjugated biologically active polypeptide, e . g. , wherein said biologically active polypeptide comprises a recombinant activated protein C or a recombinant Factor VII .

[0008] Another aspect of the present invention is directed to a composition comprising the protein conjugate and a carrier . In some embodiments , the composition is a pharmaceutical composition and the carrier is a pharmaceutically acceptable carrier .

[0009] Another aspect of the present invention is directed to a chimeric DNA molecule that encodes the protein conjugate described above, as well as a vector, together comprising the chimeric DNA molecule, and a cell transformed with the chimeric DNA molecule or a vector containing it . In some embodiments , the vector is a plasmid, e . g. , pCE2. In some embodiments , the cell is a mammalian cell e . g. , a Chinese hamster ovary (CHO) cell, or a bacterium e. g. , E. coli, or yeast .

[00010] Yet another aspect of the present invention is directed to a method of making a biologically active protein conjugate comprising a biologically active polypeptide coupled via peptide bond to a polypeptide comprising from 2 to about 500 units of a peptide comprising as a maj or constituent , two or more residues of one amino acid selected from GIy (G) , Asn

(N) and GIn (Q) , and as a minor constituent , one or more residues of one amino acid selected from Ala (A) , Ser ( S ) , Thr

(T ) , Asp ( D) , GIn (Q) , GIu (E) , His (H) and Asn (N) , provided that none of said amino acids is present in said maj or constituent and said minor constituent , such that said biologically active protein has a modified plasma half-life compared to intrinsic half-life of the unconjugated biologically active polypeptide, said method comprising : culturing- a cell transformed with a chimeric DNA molecule encoding said protein conjugate under conditions whereby said DNA is expressed, thereby producing said protein conj ugate ; and extracting an expression product of said chimeric DNA molecule from said cell .

[00011] A further aspect of the present invention is directed to a method of determining whether a given protein conjugate exhibits a modified plasma half-life compared to the intrinsic half-life of the unconj ugated biologically active polypeptide, comprising : a) preparing a protein conj ugate comprising a biologically active polypeptide coupled via a peptide bond to a polypeptide that comprises from 2 to about 500 repeating units of a peptide motif, wherein the motif comprises a maj or constituent and a minor constituent , in which the maj or constituent comprises or consists of two or more residues of one amino acid selected from the group consisting of GIy (G) , Asn (N) and GIn (Q) , and the minor constituent comprises or consists of one or more residues of one amino acid selected from the group consisting of Ala (A) , Ser ( S) , Thr (T) , Asp ( D) , GIn (Q) , GIu (E) , His (H) and Asn (N) , wherein none of the amino acids is present in both the maj or constituent and said minor constituent, and b) testing the protein conjugate to determine whether the protein conj ugate has a modified plasma half-life compared to the intrinsic half-life of the unconjugated biologically active polypeptide .

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a schematic representation of the PHO x pBSK vector .

[0011] Figure 2 is a schematic representation of the PHO-G- CSF-NN x pBSK vector .

[0012] Figure 3 is a schematic representation of the PHO-G- CSF- (NNT ) 65 x pBSK vector .

[0013] Figure 4 is a schematic representation of the PHO-G- CSF- (NNT) 155 x pBSK vector .

[0014] Figure 5 is a schematic representation of the PHO-G- CSF- (NNT ) 155 x pCE2 vector .

[0015] Figure 6 is a Western blot of several different G-CSF- polypeptide conj ugates and unconjugated G-CSF. [0016] Figure 7 is a Western blot of several different G-CSF- polypeptide conjugates and unconjugated G-CSF that were treated with PNGase F prior to electrophoresis .

[0017] Figure 8 is a Western blot of the G-CSF- (NNT) 155 and G-CSF- (NNT) 65 constructs (in duplicate ) that were expressed in CHOKl cells grown in PR0CH04-CDM media .

DETAILED DESCRIPTION

[0018] As used herein, the term "polypeptide" means a polymer of amino acids having no specific length, unless otherwise specified. Thus, peptides and proteins are included in the definition of "polypeptide" and these terms are used interchangeably throughout the specification, as well as in the claims . The term "polypeptide" does not exclude post- translational modifications , such as polypeptides having covalent attachment of glycosyl groups , acetyl groups , phosphate groups , lipid groups , hydroxylation of proline or lysine, and the like . Also encompassed by this definition of "polypeptide" are homologs thereof .

[0019] The term "purified" as used herein means that the biologically active protein conjugate has been purified to a level adequate for its intended use .

[0020] The present invention is directed, in a general aspect , to a protein conjugate comprising a biologically active polypeptide coupled via peptide bond to a polypeptide that comprises from 2 to about 500 units of a peptide motif that contains a maj or constituent of two or more residues of one amino acid selected from GIy (G) , Asn (N) and GIn (Q) , and a minor constituent of one or more residues of one amino acid selected from Ala (A) , Ser ( S) , Thr (T ) , Asp ( D) , GIn (Q) , GIu

(E) , His (H) and Asn (N) , provided that none of the amino acids is present as both a maj or constituent and minor constituent . The protein conjugates of the present invention have a plasma half-life greater than the corresponding unconj ugated biologically active polypeptide or protein .

[0021] The repeating unit of the motif generally contains 3-7 ( 3 , 4 , 5 , 6 or 7 ) amino acid residues . Representative peptide motifs having N (Asn) as the maj or constituent are described in Table 1.

[0022] Representative peptide motifs having G (GIy) as the maj or constituent are described in Table 2.

[0023] Representative peptide motifs having Q (GIu) as the maj or constituent are described in Table 3.

[0024] The number of the peptide motifs ranges from 2 to about 500. Thus , the motifs including the specific peptide motifs set forth herein, may be present in the polypeptide in the following number of units : 2, 3, 4 , 5, 6, 7 , 8 , 9, 10, 11,

12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26,

27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36, 37 , 38 , 39, 40 , 41 ,

42 , 43 , 44 , 45, 46, 47 , 48 , 49, 50, 51, 52 , 53, 54 , 55, 56,

57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66, 67 , 68 , 69 , 70 , 71 ,

72 , 73 , 74 , 75 , 76, 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 ,

87 , 88 , 89, 90, 91, 92 , 93 , 94 , 95, 96, 97 , 98 , 99, 100 101,

102 , 103 , 104 , 105 , 106, 107 , 108 , 109 , 110 , 111 , 112 , 113 ,

114 , 115 , 116, 117 , 118 , 119 , 120 , 121 , 122 , 123 , 124 , 125 ,

126, 127 , 128 , 129, 130, 131, 132 , 133 , 134 , 135, 136, 137 ,

•138 , 139 , 140 , 141 , 142 , 143 , 144 , 145 , 146, 147 , 148 , 149 ,

150 , 151 , 152 , 153 , 154 , 155, 156, 157 , 158 , 159, 160 , 161 ,

162 , 163 , 164 , 165 , 166, 167 , 168 , 169, 170 , 171 , 172 , 173 ,

174 , 175 , 176, 177 , 178 , 179, 180 , 181 , 182 , 183 , 184 , 185 ,

186, 187 , 188 , 189, 190, 191, 192 , 193 , 194 , 195, 196, 197 ,

198 , 199 , 200 201 , 202 , 203 , 204 , 205 , 206, 207 , 208 , 209 ,

210 , 211 , 212 , 213 , 214 , 215 , 216, 217 , 218 , 219 , 220 , 221,

222 , 223, 224 , 225, 226, 227 , 228 , 229, 230 , 231, 232 , 233,

234 , 235 , 236 , 237 , 238 , 239, 240 , 241 , 242 , 243 , 244 , 245 ,

246, 247 , 248 , 249, 250 , 251 , 252 , 253 , 254 , 255 , 256 , 257 , 258 , 259, 260 , 261, 262 , 263, 264 , 265, 266, 267 , 268 , 269,

270 , 271 , 272 , 273 , 274 , 275 , 276, 277 , 278 , 279 , 280 , 281 ,

282 , 283 , 284 , 285 , 286, 287 , 288 , 289 , 290 , 291 , 292 , 293 ,

294 , 295 , 296, 297 , 298 , 299, 300 301 , 302 , 303 , 304 , 305 ,

306, 307 , 308 , 309, 310 , 311 , 312 , 313 , 314 , 315 , 316, 317 ,

318 , 319, 320 , 321, 322 , 323, 324 , 325, 326, 327 , 328 , 329,

330 , 331 , 332 , 333 , 334 , 335 , 336, 337 , 338 , 339 , 340 , 341 ,

342 , 343 , 344 , 345 , 346, 347 , 348 , 349, 350 , 351 , 352 , 353 ,

354 , 355 , 356 , 357 , 358 , 359, 360 , 361 , 362 , 363 , 364 , 365 ,

366, 367 , 368 , 369 , 370 , 371 , 372 , 373 , 374 , 375 , 376, 377 ,

378 , 379, 380 , 381, 382 , 383, 384 , 385, 386, 387 , 388 , 389,

390 , 391 , 392 , 393 , 394 , 395 , 396, 397 , 398 , 399, 400 401 ,

402 , 403 , 404 , 405 , 406, 407 , 408 , 409, 410 , 411 , 412 , 413 ,

414 , 415 , 416 , 417 , 418 , 419, 420 , 421 , 422 , 423 , 424 , 425 ,

426, 427 , 428 , 429 , 430 , 431 , 432 , 433 , 434 , 435 , 436, 437 ,

438 , 439, 440 , 441, 442 , 443, 444 , 445, 446, 447 , 448 , 449,

450 , 451 , 452 , 453 , 454 , 455 , 456, 457 , 458 , 459 , 460 , 461 ,

462 , 463 , 464 , 465 , 466, 467 , 468 , 469 , 470 , 471 , 472 , 473 ,

474 , 475 , 476 , 477 , 478 , 479, 480 , 481 , 482 , 483 , 484 , 485 ,

486, 487 , 488 , 489 , 490 , 491 , 492 , 493 , 494 , 495 , 496, 497 ,

498 , 499 and 500 (thus including any subrange thereof) .

[0025] As described above, the polypeptide conjugated to the biologically active polypeptide may also be referred to as an amino acid or polyamino extension (hereinafter "amino acid extension" ) of the biologically active polypeptide . The amino acid extension may be situated at the N-terminus , at the C- terminus or at both the N- and C-termini, with respect to the biologically active polypeptide sequence .

[0026] Without intending to be bound by theory, Applicants believe that the amino acid extensions do not adopt stable conformations and as such, do not interfere with or otherwise influence the activity of the protein . Also, limiting the amino acid extension to two different amino acids is believed to reduce the chemical complexity of the amino acid extension, which helps minimize the potential for immunogenicity, as well as allowing for the modulation of physicochemical properties far more extensively than is possible through the use of just one type or kind of amino acid .

[0027] Broadly, the biologically active polypeptide includes any protein ( including native polpeptides ( i . e . , as they exist in vivo) or polypeptides produced recombinantly, such as recombinant human G-CSF (rh-G-CSF) for which a modified plasma half-life would be . desirable from some standpoint , particularly from a therapeutic standpoint, meaning that when delivered to a vertebrate organism, treats, e. g. , cures, ameliorates , or lessens the symptoms of, a given disease in that vertebrate , or alternatively, prolongs the life of the vertebrate by slowing the progress of a terminal disease . Types of biologically active proteins include cytokines , chemokines , lymphokines , ligands , receptors , hormones , apoptosis-inducing polypeptides, enzymes , antibodies and antibody fragments , and growth factors . Examples of receptors include TNF type I receptor, IL-1 receptor type II , IL-1 receptor antagonist, IL-4 receptor and any chemically or genetically modified soluble receptors . Examples of enzymes include activated protein C, factor VII , collagenase ( e . g. , marketed by Advance Biofactures Corporation under the name Santyl) ; agalsidase-beta ( e . g. , marketed by Genzyme under the name Fabrazyme) ; dornase-alpha ( e . g. , marketed by Genentech under the name Pulmozyme) ; alteplase ( e . g. , marketed by Genentech under the name Activase) ; pegylated-asparaginase

( e . g. , marketed by Enzon under the name Oncaspar) ; asparaginase ( e . g. , marketed by Merck under the name Elspar) ; and imiglucerase ( e . g. , marketed by Genzyme under the name Ceredase) . Examples of specific polypeptides or proteins include, but are not limited to granulocyte macrophage colony stimulating factor (GM-CSF) , granulocyte colony stimulating factor (G-CSF) , macrophage colony stimulating factor (M-CSF) , colony stimulating factor (CSF) , interferon beta ( IFN-β ) , interferon gamma (IFNγ) , interferon gamma inducing factor I ( IGIF) , transforming growth factor beta (TGF-β) , RANTES

( regulated upon activation, normal T-cell expressed and presumably secreted) , macrophage inflammatory proteins ( e . g. , MIP-1-α and MIP-1-β ) , Leishmania elongation initiating factor

(LEIF) , platelet derived growth factor ( PDGF) , tumor necrosis factor (TNF) , growth factors , e . g. , epidermal growth factor

(EGF) , vascular endothelial growth factor (VEGF) , fibroblast growth factor, ( FGF) , nerve growth factor (NGF) , brain derived neurotrophic factor (BDNF) , neurotrophin-2 (NT-2 ) , neurotrophin-3 (NT-3 ) , neurotrophin-4 (NT-4 ) , neurotrophin-5

(NT-5 ) , glial cell line-derived neurotrophic factor (GDNF) , ciliary neurotrophic factor (CNTF) , TNF α type II receptor, erythropoietin (EPO) , insulin and soluble glycoproteins e . g. , gpl20 and gpl60 glycoproteins . The gpl20 glycoprotein is a human immunodeficiency virus (HIV) envelope protein, and the gpl60 glycoprotein is a known precursor to the gpl20 glycoprotein.

[0028] In some embodiments , it is desirable to modify the half-life of a biologically active polypeptide such that it is decreased relative to the intrinsic half life, is desirable . Such embodiments include recombinant activated protein C

( e . g. , marketed by Eli Lilly under the name Xigris ) and recombinant Factor VII (marketed by Novo Nordisk under the name NovoSeven) .

[0029] Biologically active polypeptides may be used to treat diseases such as Parkinson ' s disease, cancer, and heart disease . In addition, therapeutic polypeptides may be used to treat autoimmune disorders such as multiple sclerosis ; Sjogren ' s syndrome; sarcoidosis ; insulin dependent diabetes mellitus ; autoimmune thyroiditis ; arthritis ( e. g. , osteoarthritis , rheumatoid arthritis, reactive arthritis, and psoriatic arthritis) ; ankylosing spondylitis ; and scleroderma . Also, therapeutic polypeptides of the present invention can be used to treat acute and chronic inflammatory disorders , to promote increase in stature, to promote wound healing, and to prevent rej ection after transplantation of cells , tissues , or organs .

[0030] In some preferred embodiments , the polypeptide is G- CSF. G-CSF induces rapid proliferation and release of neutrophilic granulocytes to the bloodstream, thereby providing a therapeutic effect in fighting infection . As explained in U . S . Patent 6, 831 , 158 , recombinant human (rh) -G- CSF is generally used for treating various forms of leukopenia

(a reduced level of white blood cells ) and neutropenia (a reduced level of neutrophils ) . Leukopenia and neutropenia result in an increased susceptibility to various infections .

[0031] Commercial preparations of rh-G-CSF are available 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 produced in recombinant CHO^' cells . NEU-UP^® is non-glycosylated with five amino acids substituted at the N-terminal region of intact rh-G-CSF produced in recombinant E. coli cells .

[0032] Aside from G-CSF, per se, G-CSF analogs that are biologically functional or have biological activity are also useful . Methods of preparing rh-G-CSF are disclosed in U . S . Patent 4 , 810 , 643. Various G-CSF analogs are also reported in U . S . Patent 4 , 810 , 643. The polynucleotide encoding rh-G-CSF and the amino acid structure of rh-G-CSF are both provided in U . S . Patent 5, 985, 265.

[0033] A representative example of an amino acid sequence (and the corresponding polynucleotide sequence) of a protein conjugate of the present invention is shown in Table 4. The PHO leader sequence is included .

[0034] In the amino acid sequence, the PHO leader sequence is from amino acids 1 to 18 , G-CSF is from amino acids 19 to 192 , and the NNT₁₅₅ amino acid extension is from amino acids 193 to 347. The stop codon is denoted by the "*" symbol .

[0035] As depicted in the polynucleotide sequence, nucleic acids 1 to 54 encode the PHO leader sequence, nucleic acids 55 to 576 encode G-CSF, and nucleic acids 577 to 1041 encode the NNTi₅₅ amino acid extension . Nucleic acids 1042 to_. 1044 (TAG) constitute the stop codon .

[0036] In some embodiments , the number of repeating peptide units is between 75 and 225. Thus , in the case of a protein conj ugate containing G-CSF linked to a polypeptide containing repeating units of peptide motif having the sequence NNT, embodiments of the present invention may include any of the following protein conjugates : G-CSF- (NNT) ₇₅, G-CSF- (NNT) ₇₆, G- CSF- (NNT) ₇₇, G-CSF- (NNT ) ₇₈, G-CSF- (NNT) ₇₉, G-CSF- (NNT) ₈₀, G-CSF- (NNT ) ₈₁, G-CSF- (NNT) ₈₂, G-CSF- (NNT) ₈₃, G-CSF- (NNT) ₈₄, G-CSF-

(NNT ) ₈₅, G-CSF- (NNT) ₈₆, G-CSF- (NNT) ₈₇, G-CSF- (NNT) ₈₈, G-CSF- (NNT) ₈₉, G-CSF- (NNT) ₉₀, G-CSF- (NNT) ₉₁, G-CSF- (NNT) ₉₂, G-CSF- (NNT ) ₉₃, G-CSF- (NNT) ₉₄ , G-CSF- (NNT) ₉₅, G-CSF- (NNT ) ₉₆, G-CSF- (NNT) ₉₇, G-CSF- (NNT) ₉₈ , G-CSF- (NNT) ₉₉, G-CSF- (NNT) ₁₀₀, G-CSF-

(NNT) ₁₀₁, G-CSF- (NNT) ₁₀₂, G-CSF- (NNT) ₁₀₃, G-CSF- (NNT) ₁₀₄, G-CSF- (NNT) ₁₀₅, G-CSF- (NNT) ₁₀₆, G-CSF- (NNT) ₁₀₇, G-CSF- (NNT) ₁₀₈, G-CSF- (NNT) ₁₀₉, G-CSF- (NNT) ₁₁₀, G-CSF- (NNT) ₁₁₁, G-CSF- (NNT) ₁₁₂, G-CSF- (NNT) ₁₁₃, G-CSF- (NNT) i₁₄, G-CSF- (NNT) ₁₁₅, G-CSF- (NNT) ₁₁₆, G-CSF- (NNT) ₁₁₇, G-CSF- (NNT ) ₁₁₈ , G-CSF- (NNT) ₁₁₉, G-CSF- (NNT) ₁₂₀, G-CSF- (NNT ) ₁₂₁, G-CSF- (NNT) ₁₂₂, G-CSF- (NNT) ₁₂₃, G-CSF- (NNT) ₁₂₄, G-CSF- (NNT ) ₁₂₅, G-CSF- (NNT) ₁₂₆, G-CSF- (NNT) ₁₂₇, G-CSF- (NNT) ₁₂₈, G-CSF- (NNT) ₁₂₉, G-CSF- (NNT) ₁₃₀, G-CSF- (NNT) ₁₃₁, G-CSF- (NNT) ₁₃₂, G-CSF- (NNT) ₁₃₃, G-CSF- (NNT) ₁₃₄, G-CSF- (NNT) ₁₃₅, G-CSF- (NNT) ₁₃₆, G-CSF- (NNT) ₁₃₇, G-CSF- (NNT) ₁₃₈, G-CSF- (NNT) ₁₃₉, G-CSF- (NNT) ₁₄₀, G-CSF- (NNT) ₁₄₁, G-CSF- (NNT) ₁₄₂, G-CSF- (NNT) ₁₄₃, G-CSF- (NNT) ₁₄₄, G-CSF- (NNT) ₁₄₅, G-CSF- (NNT) _I46, G-CSF- (NNT) ₁₄₇, G-CSF- (NNT) ₁₄₈, G-CSF- (NNT ) ₁₄₉, G-CSF- (NNT) I₅₀, G-CSF- (NNT) ₁₅₁, G-CSF- (NNT) ₁₅₂, G-CSF- (NNT) ₁₅₃, G-CSF- (NNT) ₁₅₄, G-CSF- (NNT) ₁₅₅, G-CSF- (NNT) ₁₅₆, G-CSF- (NNT ) ₁₅₇, G-CSF- (NNT ) ₁₅₈, G-CSF- (NNT) ₁₅₉, G-CSF- (NNT ) ₁₆₀, G-CSF- (NNT) ₁₆₁, G-CSF- (NNT ) ₁₆₂, G-CSF- (NNT) ₁₆₃, G-CSF- (NNT ) ₁₆₄, G-CSF- (NNT)₁₆₅, G-CSF- (NNT) ₁₆₆, G-CSF- (NNT) ₁₆₇, G-CSF- (NNT) ₁₆₈, G-CSF

(NNT)_169, G-CSF- (NNT) ₁₇₀, G-CSF- (NNT) ₁₇₁, G-CSF- (NNT) ₁₇₂, G-CSF

(NNT)_173, G-CSF- (NNT) ₁₇₄, G-CSF- (NNT) ₁₇₅, G-CSF- (NNT) ₁₇₆, G-CSF

(NNT)_177, G-CSF- (NNT) ₁₇₈, G-CSF- (NNT) ₁₇₉, G-CSF- (NNT) ₁₈₀, G-CSF

(NNT) _i8i, G-CSF- (NNT) ₁₈₂, G-CSF- (NNT) ₁₈₃, G-CSF- (NNT) ₁₈₄, G-CSF

(NNT)_185, G-CSF- (NNT) ₁₈₆, G-CSF- (NNT) ₁₈₇, G-CSF- (NNT) ₁₈₈, G-CSF

(NNT)_189, G-CSF- (NNT) ₁₉₀, G-CSF- (NNT) ₁₉₁, G-CSF- (NNT) ₁₉₂, G-CSF

(NNT)_193, G-CSF- (NNT) ₁₉₄, G-CSF- (NNT) ₁₉₅, G-CSF- (NNT) ₁₉₆, G-CSF

(NNT)_197, G-CSF- (NNT) ₁₉₈, G-CSF- (NNT) ₁₉₉, G-CSF- (NNT) ₂₀₀, G-CSF

(NNT)_201, G-CSF- (NNT) ₂₀₂, G-CSF- (NNT) ₂₀₃, G-CSF- (NNT) ₂₀₄, G-CSF

(NNT)_205, G-CSF- (NNT) ₂₀₆, G-CSF- (NNT) ₂₀₇ , G-CSF- (NNT) ₂₀₈, G-CSF

(NNT)_209, G-CSF- (NNT) ₂₁₀, G-CSF- (NNT) ₂₁₁, G-CSF- (NNT) ₂₁₂, G-CSF

(NNT)_213, G-CSF- (NNT) ₂₁₄, G-CSF- (NNT) ₂₁₅, G-CSF- (NNT) ₂₁₆, G-CSF

(NNT)_217, G-CSF- (NNT) ₂₁₈, G-CSF- (NNT) ₂₁₉, G-CSF- (NNT) ₂₂₀, G-CSF

(NNT)_221, G-CSF- (NNT) ₂₂₂, G-CSF- (NNT) ₂₂₃, G-CSF- (NNT) _{224 and G}

CSF- (NNT) 225

[0037] In other preferred embodiments, the polypeptide is EPO. As explained in Krantz , Blood 77: 419 ( 1991 ) , naturally occurring EPO stimulates the division and differentiation of committed erythoid progenitors in the bone marrow and exerts its biological activity by binding to receptors and erythroid precursors . EPO has been manufactured biosynthetically using recombinant technology as the product of a cloned human EPO (hEPO) gene inserted into and expressed in Chinese hamster ovary (CHO) cells . See Egrie, et al . , Immunobiol . 72: 213-224 ( 1986 ) . The primary structure ( i . e . , amino acid sequence) of the predominant, fully processed form of hEPO is illustrated in U . S . Patent 6, 583 , 272. In EPO, there are two disulfide bridges between Cys⁷ - Cys¹⁶¹ and Cys 29 Cys 33 The molecular weight of the polypeptide chain of EPO without the sugar moieties is 18 , 236 DA. In the intact EPO molecule, approximately 40% of the molecular weight is accounted for by carbohydrate groups that glycosylate the protein at glycosylation sites on the protein . See Sasaki, et al . , J. Biol . Chem. 262: 12059 ( 1987 ) . [0038] Because hEPO is essential in red blood formation, the hormone is useful in the treatment of blood disorders characterized by low or defective red blood cell production . Clinically, EPO is used in the treatment of anemia in chronic renal failure (CRF) patients . See Eschbach, et al . , NEJM 315: 73-78 ( 1987 ) ; Eschbach, et al . , Ann . Intern . Med . 111 : 992

( 1989) ; Egrie, et al . , Kidney Intl . 33: 262 ( 1988 ) ; and Lim et al . , Ann . Intern . Med . 110: 108-114 (1989) . EPO has also been used for the treatment of anemia in Acquired Immune Deficiency Syndrome (AIDS) and cancer patients undergoing chemotherapy. See R. P . Danna, et al . , Erythropoietin In Clinical Applications - An International Perspective 301-324 (M. B . Garnick, ed. , Marcel Dekker 1990) .

[0039] Amino acid and corresponding nucleotide sequences of EPO, as well as other biologically active polypeptides useful in the present invention, are set forth in Table 5. Two other amino acid sequences of EPO are set forth in Table 6.

[0040] The protein conjugate may further comprise one or more affinity tags . Generally, an affinity tag is a polypeptide segment that facilitates isolation, purification or detection of the fusion protein containing the affinity tag . In principle , any peptide or protein for which an antibody or other specific binding agent is available can be used as an affinity tag . Representative affinity tags include a poly- histidine tract, protein A (Nilsson, et al . , EMBO J. 4: 1075 , ( 1985 ) ; Nilsson, et al . , Methods Enzymol . 198: 3 , ( 1991 ) ) , glutathione S transferase (Smith et al . , Gene 67: 31 ( 1988 ) ) , maltose binding protein (Kellerman et al . , Methods Enzymol . 90 : 459-463 ( 1982 ) ; Guan, et al . , Gene 67: 21-30 ( 1987 ) ) , GIu- GIu affinity tag (Grussenmeyer, et al . , Proc . Natl . Acad. Sci . USA 82: 7952-4 ( 1985 ) ; see oNDEPHO-lR) , substance P, Flag™ peptide (Hopp, et al . , Biotechnology 6: 1204-10 ( 1988 ) ) , streptavidin binding peptide, thioredoxin, ubiquitin, cellulose binding protein, T7 polymerase, or other antigenic epitope or binding domain . See , in general, Ford, et al . _r Protein Expression and Purification 2: 95-107 ( 1991) . DNAs encoding affinity tags are available from commercial suppliers ( e . g. , Pharmacia Biotech, Piscataway, New Jersey; New England Biolabs , Beverly, Massachusetts ; and Eastman Kodak, New Haven, Connecticut ) .

[0041] As in the case of the amino acid extension, the affinity tag may be situated at the N-terminal, C-terminal, or both N-terminal and C-terminal with respect to the biologically active polypeptide sequence .

[0042] The present invention is also directed to a method of making the protein conj ugates . The method involves culturing a cell transformed with a chimeric DNA molecule encoding the protein conj ugate under conditions whereby the DNA is expressed, thereby producing the protein conj ugate; and extracting an expression product of the chimeric DNA molecule from the cell or culture medium (or a milleau from the cell culture) . In contrast to protein conj ugates formed by chemical means ( e . g. , the commercial product NEULASTA ( PEG-G- CSF, which is a covalent conj ugate of recombinant methionyl human G-CSF and monomethionyl polyethylene glycol) , the conj ugation in the present invention is performed recombinantly as opposed to through physical or chemical means , resulting in the production of the biologically active protein and the polypeptide as components of a continuous protein . A linker, e . g. , about 10-20 amino acids in length, may be used to j oin the protein with the amino acid extension .

[0043] The chimeric DNA molecule includes a gene or polynucleotide fragment that encodes a protein portion and one or more gene fragments e. g. , oligonucleotides that together encode the polypeptide or amino acid extension . Oligonucleotides encoding the peptide motifs contained in the amino acid extension (and which encode the peptide motifs specifically disclosed herein) are set forth in Table 7. (The one-letter symbols used in Table 7 are explained in Table 8. ) The DNA molecules may further contain fragments that encode affinity tags , linkers , as well as 5 ' and 3' regulatory elements . The gene or polynucleotide that encodes a protein portion may be any gene or polynucleotide known to encode the desired protein or polypeptide of the protein portion . Such genes and polynucleotides, and the primers used to generate them, are protein or polypeptide specific and well known in the art . The ligated oligonucleotides encoding the polypeptide portion may be produced according to procedures set forth above and described in Example 1. The oligonucleotides may be of any length, but are preferably designed to avoid the use of repetitive DNA sequences that are known to inhibit transcription . For instance, ligated oligonucleotides containing combinations of two glutamate codons are less likely to adopt a structural configuration that impedes gene expression than a polynucleotide made up of only one glutamate codon . The chimeric DNA molecule encoding the protein conjugate of the present invention may be engineered to contain codons encoding methionine (M) and/or proline (P) amino acid at its 5' end to facilitate expression.

[0044] The conj ugates of the present invention are made via standard recombinant techniques in molecular biology . In some embodiments , a gene or polynucleotide encoding the biologically active protein is first cloned into a construct , e . g. , a plasmid or other vector . Then, the oligonuleotides that encode the repeating units of the polypeptide portion are cloned into the construct through a ligation or multimerization scheme, in which the oligonucleotides are ligated together to form a polynucleotide that encodes the polypeptide portion . In this manner, the oligonucleotides are added to the gene or polynucleotide that encodes the protein portion, thereby producing the chimeric DNA molecule within the construct . As an option, the chimeric DNA molecule may be transferred or cloned into another construct that is a more appropriate expression vector . At this point, a host cell capable of expressing the chimeric DNA molecule is transformed with the chimeric DNA molecule . The transformation may occur with or without the utilization of a carrier, such as an expression vector . Then, the transformed host cell is cultured under conditions suitable for expression of the chimeric DNA molecule, resulting in the encoding of the protein conjugate .

[0045] Methods of ligation or multimerization useful in the present invention are well known . See, Joseph Sambrook, et al . , Molecular Cloning : A Laboratory Manual, 2^nd ed. , 1.53

(Cold Spring Harbor Laboratory Press 1989) .

[0046] The cloning process may take place through "directional cloning" , which is well known in the art . Directional cloning refers to the insertion of a polynucleotide into a plasmid or vector in a specific and predefined orientation . Once cloned into a vector, a polynucleotide sequence can be lengthened at its 3 ' end or other polynucleotides inserted at its 5' and/or 3 ' ends . Such a design provides an efficient and relatively easy way to create large polymers without having to perform multiple rounds of ligation . The vector preferably contains restriction sites upstream of a cloned polynucleotide, but downstream of regulatory elements required for expression to facilitate the insertion of the second polynucleotide .

[0047] To facilitate directional cloning, "adapter oligonucleotides" may be ligated to the 5 ' and 3' ends of the chimeric DNA molecule encoding the protein conjugate . Preferably, the adapters contain restriction sites that are compatible with those present in the expression vector . The 3 ' adapter oligonucleotide may also comprise a stop codon to designate the end of the encoding sequence to which it is ligated . The oligonucleotides encoding the polypeptide portion are preferably added in excess of the adapter oligonucleotides to increase the likelihood that a long polynucleotide is generated after ligation .

[0048] The methodology is not limited to any particular cloning strategy . The skilled artisan may use any variety of cloning strategies to produce a construct that comprises a chimeric DNA molecule of the present invention .

[0049] The chimeric DNA molecule can be introduced into the host cells in accordance with known techniques well known to those skilled in the art . These techniques include , but are not limited to, transformation using calcium phosphate co- precipitated chimeric DNA molecules , lipidic reagent co- transfection ( i . e. , Lipofectamine) , electroporation, transduction by contacting the cells with a virus , or microinj ection of the chimeric DNA molecules into the cells . The host cell can be a higher eukaryotic cell , such as a mammalian cell , or a lower eukaryotic cell , such as a yeast cell , or the host cell can be a prokaryotic cell , such as a bacterial cell . Suitable prokaryotic hosts for transformation include E. coli, Bacillus subtilis, Salmonella typhimurium and various species within the genera Pseudomonas_r Streptomyces, and Staphylococcus, although others may also be employed as a matter of choice .

[0050] A wide variety of host/expression vector combinations are employed in expressing the protein conj ugates of the present invention . Generally, recombinant expression vectors will include origins of replication and selectable markers permitting transformation of the host cell ( e . g. , dihydrofolate reductase or neomycin resistance for eukaryotic cell culture, or such as tetracycline or ampicillin resistance in E. coli, or the S. cerevisiae TRPl gene) , and a promoter derived from a highly-expressed gene to direct transcription of a downstream structural sequence . Such promoters can be derived from operons encoding glycolytic enzymes such as 3- phosphoglycerate kinase ( PGK) , A-factor, acid phosphatase, or heat shock proteins , among others . The heterologous structural sequence is assembled in appropriate phase with translation initiation and termination sequences , and in some embodiments , a leader sequence capable of directing secretion of translated protein conjugate . The vector will further comprise an origin of replication to ensure maintenance of the vector and to, if desirable, provide amplification within the host .

[0051] Useful expression vectors that can be used include, for example , segments of chromosomal, non-chromosomal and synthetic DNA sequences . Suitable vectors include, but are not limited to, derivatives of SV40 and pcDNA and known bacterial plasmids such as col EI , pCRl, pBR322 , pMal-C2 , pET, pGEX as described by Smith, et al . , Gene 57: 31-40 ( 1988 ) , pMB9 and derivatives thereof, plasmids such as RP4 , phage DNAs such as the numerous derivatives of phage I such as NM989, as well as other phage DNA such as M13 and filamentous single stranded phage DNA; yeast plasmids such as the 2 micron plasmid or derivatives of the 2m plasmid, as well as centomeric and integrative yeast shuttle vectors ; vectors useful in eukaryotic cells such as vectors useful in insect or mammalian cells ; vectors derived from combinations of plasmids and phage DNAs , such as plasmids that have been modified to employ phage DNA or the expression control sequences ; and the like . The requirements are that the vectors are replicable and viable in the host cell of choice . Low- or high-copy number vectors may be used as desired.

[0052] For example in a baculovirus expression system, both non-fusion transfer vectors , such as, but not limited to pVL941 {BamHI cloning site, available from Summers, et al . , Virology 84 : 390-402 (1978 ) ) , pVL1393 (BamHI , Smal , Xbal, EcoRI , IVotl , Xmalll , BgIII and Pstl cloning sites ; Invitrogen) , pVL1392 (BgIII, Pstl , Not!, XmaIII , EcoRI, Xball , Smal and BamHI cloning site; Summers , et al . , Virology 84 : 390- 402 ( 1978 ) and Invitrogen) and pBlueBacIII {BamHI , BgIII , Pstl , Ncol and HindiII cloning site, with blue/white recombinant screening, Invitrogen) , and fusion transfer vectors such as, but not limited to, pAc700 (BamHI and Kpnl cloning sites, in which the BamHI recognition site begins with the initiation codon; Summers , et al . , Virology 84 : 390-402 (1978 ) ) , pAc701 and pAc70-2 (same as pAc700 , with different reading frames ) , pAc360 [BamHI cloning site 36 base pairs downstream of a polyhedrin initiation codon; Invitrogen ( 1995 ) ) and pBlueBacHisA, B, C (three different reading frames with BamHI , BgIII , Pstl , Ncol and HindIII cloning site, an N- terminal peptide for ProBond purification and blue/white recombinant screening of plaques ; Invitrogen (220 ) can be used.

[0053] Mammalian expression vectors will comprise an origin of replication, a suitable promoter and enhancer, and also any necessary ribosome binding sites , polyadenylation site, splice donor and acceptor sites , transcriptional termination sequences , and 5 ' flanking nontranscribed sequences . DNA sequences derived from the SV40 splice, and polyadenylation sites may be used to provide the required nontranscribed genetic elements . Mammalian expression vectors contemplated for use in the invention include vectors with inducible promoters , such as the dihydrofolate reductase promoters , any expression vector with a DHFR expression cassette or a DHFR/methotrexate co-amplification vector such as pED ( Pstl, Sail , Sbal, Smal and EcoRI cloning sites, with the vector expressing both the cloned gene and DHFR; Randal J. Kaufman, 1991, Randal J. Kaufman, Current Protocols in Molecular Biology, 16, 12 (1991) ) . Alternatively a glutamine synthetase/methionine sulfoximine co-amplification vector, such as pEE14 (Hindlll, Xball, Smal , Sbal, EcoRI and Sell cloning sites in which the vector expresses glutamine synthetase and the cloned gene ; Celltech) . A vector that directs episomal expression under the control of the Epstein Barr Virus (EBV) or nuclear antigen (EBNA) can be used such as pREP4 {BamHI _r SfH , Xhol , NotI , Nhel , HindiII , NheI , PvuII and Kpnl cloning sites , constitutive RSV-LTR promoter, hygromycin selectable marker; Invitrogen) , pCEP4 {BamHI , SfH , Xhol , NotI , Nhel , Hindlll , Nhel , PvuII and Kpnl cloning sites , constitutive hCMV immediate early gene promoter, hygromycin selectable marker; Invitrogen) , pMEP4 (.Kpnl , Pvul , Nhel , Hindlll , NotI , Xhol , Sfil , BamHI cloning sites , inducible methallothionein Ha gene promoter, hygromycin selectable marker, Invitrogen) , pREP8 {BamHI , Xhol , NotI , Hindlll , Nhel and Kpnl cloning sites , RSV-LTR promoter, histidinol selectable marker; Invitrogen) , pREP9 (Kpnl , Nhel , Hindlll , NotI , Xhol , Sfil , BamHI cloning sites , RSV-LTR promoter, G418 selectable marker; Invitrogen) , and pEBVHis (RSV-LTR promoter, hygromycin selectable marker, N-terminal peptide purifiable via ProBond resin and cleaved by enterokinase; Invitrogen) .

[0054] Selectable mammalian expression vectors for use in the invention include, but are not limited to, pRc/CMV (Hindlll , BstXI , NotI , Sbal and Apal cloning sites , G418 selection, Invitrogen) , pRc/RSV (HindII, Spel, BstXI , NotI , Xbal cloning sites, G418 selection, Invitrogen) and the like . Vaccinia virus mammalian expression vectors ( see, for example, Randall J. Kaufman, Current Protocols in Molecular Biology 16.12

( Frederick M . Ausubel , et al . , eds . Wiley 1991 ) that can be used in the present invention include, but are not limited to, pSC11 { Smal cloning site, TK- and β-gal selection) , pMJ601

( Sall , Smal , AflI , Narl, BspMlI , BamHI , Apal, Nhel, SacII, Kpnl and Hindlll cloning sites ; TK- and β-gal selection) , pTKgptFlS (EcoRI , Pstl , SaIII, Accl , HindII , Sbal, BamHI and Hpa cloning sites , TK or XPRT selection) and the like .

[0055] Yeast expression systems that can also be used in the present include , but are not limited to, the non-fusion pYES2 vector (XJbal , Sphl , Shol , NotI , GstXI , EcoRI , BstXI , BamHI , Sad , Kpnl and Hindlll cloning sites , Invitrogen) , the fusion pYESHisA, B, C (Xball , Sphl , Shol , NotI , BstXI , EcoRI , BamHI , Sad , Kpnl and HindiII cloning sites , N-terminal peptide purified with ProBond resin and cleaved with enterokinase; Invitrogen) , pRS vectors and the like .

[0056] One particularly preferred vector for use in the present invention is the plasmid pCE2. The pCE2 plasmid may be obtained by any method known in the art . One such method, which was utilized in Example 2.A. , is described in Leung, et al . , Proc . Natl . Acad. Sci . USA 52: 4813-4817 ( 1995 ) .

[0057] In a preferred embodiment, the chimeric DNA molecules can be inserted into an expression vector that already contains the necessary elements for the transcription and translation of the inserted chimeric DNA molecule .

[0058] In addition, the expression vector containing the chimeric DNA molecule may include drug selection markers . Such markers aid in cloning and in the selection or identification of vectors containing chimeric DNA molecules . For example, genes that confer resistance to neomycin, puromycin, hygromycin, dihydrofolate reductase ( DHFR) , guanine phosphoribosyl transferase (GPT) , zeocin, and histidinol are useful selectable markers . Alternatively, enzymes such as herpes simplex virus thymidine kinase (tk) or chloramphenicol acetyltransferase (CAT) may be employed. Immunologic markers also can be employed. Any known selectable marker may be employed so long as it is capable of being expressed simultaneously with the nucleic acid encoding a gene product . Further examples of selectable markers are well known to one of skill in the art and include reporters such as enhanced green fluorescent protein (EGFP) , beta-galactosidase ( β-gal) or chloramphenicol acetyltransferase (CAT) .

[0059] Consequently, mammalian and typically human cells, as well as bacterial, yeast, fungi, insect, nematode and plant cells can used in the present invention as host cells and may be transformed by the expression vector as defined herein . In some cellular hosts, such as mammalian cells, the cell containing the chimeric DNA molecule may be "isolated" in that it is removed from its original environment ( e . g. , the natural environment if it is naturally occurring) . In other embodiments , such as plants , the cells do not have to be isolated in that the whole plant may be used rather than a culture of plant cells or parts .

[0060] Examples of suitable cells include, but are not limited to, VERO cells , HELA cells such as ATCC No . CCL2 , CHO cell lines such as ATCC No . CCLβl , COS cells such as COS-7 cells and ATCC No . CRL 1650 cells , W138 , BHK, HepG2 , 3T3 such as ATCC No . CRL6361, A549, PC12 , K562 cells, 293 cells , Sf9 cells such as ATCC No . CRL1711 and CvI cells such as ATCC No . CCL70.

[0061] Other suitable cells that can be used in the present invention include, but are not limited to, prokaryotic host cells strains such as Escherichia coli , { e . g. , strain DH5-α) , Bacillus subtilis, Salmonella typhimurium, or strains of the genera of Pseudomonas, Streptomyces and Staphylococcus. Further suitable cells that can be used in the present invention include yeast cells such as those of Saccharomyces such as Saccharomyces cerevisiae.

[0062] Host cells containing the polynucleotides of interest can be cultured in conventional nutrient media ( e . g. , Ham' s nutrient mixture) modified as appropriate for activating promoters , selecting transformants or amplifying genes . The culture conditions , such as temperature, pH and the like, are those previously used with the host cell selected for expression, and will be apparent to the ordinarily skilled artisan . Cells are typically harvested by centrifugation, disrupted by physical or chemical means, and the resulting crude extract retained for further purification . Microbial cells employed in expression of proteins can be disrupted by any convenient method, including freeze-thaw cycling, sonication, mechanical disruption, or use of cell lysing agents, all of which are well known to those skilled in the art . Embodiments that involve cell lysis may entail use of a buffer that contains protease inhibitors that limit degradation after expression of the chimeric DNA molecule . Suitable protease inhibitors include leupeptin, pepstatin or aprotinin. The supernatant then may be precipitated in successively increasing concentrations of saturated ammonium sulfate .

[0063] The protein conj ugates product may be purified via one or more techniques . Typically, purification entails combinations of individual procedures such as gel filtration, affinity purification, salt fractionation, ion exchange chromatography, size exclusion chromatography, hydroxylapatite adsorption chromatography, hydrophobic interaction chromatography and gel electrophoresis . Protein refolding steps can be used, as necessary, in completing configuration of the protein conjugate . High performance liquid chromatography (HPLC) is often useful for final purification steps . See, in general, Robert K. Scopes, Protein Purification : Principles and Practice (Charles R. Castor, ed. , Springer-Verlag 1994 ) and Joseph Sambrook, Molecular Cloning : A Laboratory Manual, 2^nd edition (Cold Spring Harbor Laboratory Press 1989) . Examples of multi-step purification separations are also described in Baron, et al . , Crit . Rev. Biotechnol . 10: 179-90 ( 1990 ) and Below, et al . , J. Chromatogr . A. 679: 67-83 (1994 ) .

[0064] The conjugates are tested prior to use to determine whether they exhibit modified plasma half-life compared to the unconj ugated protein . For example, in experiments conducted with G-CSF and various amino acid extensions such as (NNT) , Applicants found that the half-life was increased in one case, and in other cases , was decreased. The tests may be conducted in accordance with standard techniques in pharmacokinetics , as shown in example 3. This procedure entails administration of a predetermined dose of the conjugate to an animal, preferably 01

a laboratory animal such as a rodent, e . g. , mouse, collect plasma from the animal at predetermined intervals, and analyze the plasma e. g. , via Enzyme-Linked Immunosorbent Assay ( "ELISA" ) , to determine concentration of the conjugate, until concentration was no longer measurable . The half-life may be calculated via a non-compartmental pharmacokinetic analysis ( e . g. , using WINNonLin software version 4.1) . In addition to the last time at which the conjugate concentration was measurable (t_f) , the analysis includes observation or calculation of the following main parameters : λ_z, apparent terminal rate constant associated to the apparent terminal phase , estimated by linear regression analysis of the logarithm of the plasma concentrations versus time in the monoexponential terminal part of the curve, ti_/2, z? apparent terminal half-life , calculated according to the following equation : ti_/2, _z=ln (2 ) / λ_z; AUC, area under the plasma concentration-time curve from time zero to infinity; AUC/D, area under the plasma concentration-time curve per unit of dose; MRT, mean residence time calculated as the ratio between the area under the first moment curve, AUMC, and AUC; CL, systemic clearance, calculated as CL=D/AUC; and V_ΞS, steady state volume of distribution, calculated as V_SS=CL*MRT .

[0065] A further aspect of the present invention relates to a composition comprising the protein conj ugate and a carrier . Broadly, the carrier may be a culture medium or a matrix

( e . g. , a purification matrix) . In some embodiments , the carrier is a pharmaceutically acceptable carrier, in which case the composition is useful for preventing or treating disorders and/or diseases in a human or animal, most preferably in a mammal, or for diagnostic purposes . As an active ingredient of the composition, the protein conjugate is preferably in a soluble form.

[0066] Generally, the composition comprises a pharmaceutically effective amount of the protein conjugate which achieves the desired effect e . g. , therapeutic or diagnostic . Pharmaceutically effective amounts can be estimated from cell culture assays . For example, a dose can be formulated in animal models to achieve a circulating concentration range that includes or encompasses a concentration point or range having the desired effect in an in vitro system. See, e . g. , Molineux, et al . , Exp . Hematol . 27: 1724-34 ( 1999) . This information can thus be used to accurately determine the doses in other mammals , including humans and animals . In general , dosage amounts range from about 1 ng/kg to about 10 mg/kg based on weight of the subject .

[0067] Toxicity and therapeutic efficacy of such compounds can be determined by standard pharmaceutical procedures in cell cultures or in experimental animals . See, e . g. , Molineux, et al . , Exp . Hematol . 27: 1724-34 ( 1999 ) . For example, the LD50 (the dose lethal to 50% of the population) as well as the ED50 (the dose therapeutically effective in 50% of the population) can be determined using methods known in the art . The dose ratio between toxic and therapeutic effects is the therapeutic index that can be expressed as the ratio between LD50 and ED50 compounds that exhibit high therapeutic indices .

[0068] The data obtained from the cell culture and animal studies can be used in formulating a range of dosage of such compounds which lies preferably within a range of circulating concentrations that include the ED50 with little or no toxicity .

[0069] The compositions can be administered via any suitable route such as locally, orally, systemically, intravenously, intramuscularly, mucosally, transdermally ( e . g. , via a patch) . They may be encapsulated in liposomes , microparticles , microcapsules, nanoparticles and the like . Techniques for formulating and administering biologically active polypeptides are also disclosed in Remington : The Science and Practice of Pharmacy (Alfonso R. Gennaro, et al . , eds . Philadelphia College of Pharmacy and Science 2000) . [0070] In order to fully illustrate the present invention and advantages thereof, the following specific examples are given, it being understood that the same are intended only as illustrative and in no way limitative .

EXAMPLE 1

Cloning Of Chimeric DNA Molecule

[0071] For ease of downstream protein purification, it was decided that the G-CSF-polymer proteins were secreted into the cell culture medium. Prior experience using bacterial (ST2 ) secretion signals with various cytokine-polymer constructs showed low secretion efficiency in both prokaryotic and eukaryotic systems . However, the use of the Schizosaccharomycen pombe secretion signal sequence of the phol+ acid phosphatase ( PHO) for the secretion of heterologous proteins (GFP and HPV 16 E7 ) into a medium was known . Therefore, this secretion signal was tested with the G-CSF- polymer constructs described below in a CHO cell expression system. Also described below are the vectors that were synthesized for the production of G-CSF-polymer constructs and expression of G-CSF-polymers .

l . A. Production Of PHO x pBSK Construct

PHO x pBSK Construct

[0072] The first construct synthesized was simply the PHO leader sequence cloned into the bacterial cloning vector pBSK. The amino acid sequence of the PHO secretion signal is listed below .

M F L Q N L F L G F L A V V C A N A

[0073] The PHO secretion signal was synthesized by fusing two sets of complementary DNA oligonucleotides together and cloning them into pBSK . The most important consideration that went into the design of the oligonucleotides was that the fusion of the leader sequence to the N-terminus of the G-CSF- polymer be direct , without any intervening sequence . This ensured that the entire secretion signal was clipped from the molecule during processing, resulting in a secreted form of G- CSF with no amino-terminal modification when compared to naturally occurring and clinically available versions of G- CSF . By preparing the constructs in this manner, not only could direct comparisons to G-CSF and PEG-G-CSF be made, but this also limited any potential immunogenicity by introducing additional amino acids into the recombinant G-CSF protein . By incorporating restriction sites into the oligonucleotides for cloning the PHO leader into pBSK, as well as the subsequent cloning G-CSF into PHO x pBSK, these requirements were satisfied . The oligonucleotides that were used are listed below .

oNDEPHO-lF : 5' - GGCCGCCATATGTTCTTGCAAAATTTATTCCTTGGCT - 3 '

ONDEPHO-IR: 5' - CCAAAAAGCCAAGGAΔTAAATTTTGCAAGAACATATGGC -3'

ONDEPHO-2F: 5' - TTTTGGCCGTTGTTTGCGCAAACGCGTCCCGCAGGTG - 3 '

ONDEPHO-2R: 5' - GATCCACCTGCGGGACGCGTTTGCGCAAACAACGG - 3 '

[0074] A diagram of the PHO x pBSK vector is shown in Figure 1. The PHO leader ( PhoA) was cloned into pBSK using NotI and BamHI . The sequence for mature G-CSF was cloned into this construct utilizing the BspMl and BamHI sites . This vector confers ampicillin resistance (bla) when grown in bacteria .

Method Of Construction

[0075] Complementary pairs of oligonucleotides (oNDEPHO-lF and oNDEPHO-lR) and (oNDEPHO-2F and ONDEPHO-2R) were phosphorylated using T4 Polynucleotide Kinase ( PNK) . The T4 PNK was heat-inactivated and the oligonucleotide pairs were allowed to slowly anneal on ice . The reactions were diluted in TE and used in a ligation with pBSK previously digested using Notl and BamHI . Ligation products were electroporated into ToplO competent cells and grown on LB-ampicillin plates . Minipreps were performed on ampicillin resistant colonies to isolate DNA and diagnostic digests identified putative clones . Sequence analysis determined which of the putative clones were correct .

l . B . Production Of PHO-G-CSF-NN x pBSK Construct

PHO-G-CSF-NN x pBSK Construct

[0076] This construct resulted from the cloning of PCR amplified material corresponding to the coding sequence of mature G-CSF into the PHO x pBSK vector using BspML and BamHI . As stated previously, the oligonucleotides used for this purpose were designed to ensure that the junction between PHO and G-CSF had no intervening sequence by utilizing the restriction enzyme BspMl . Furthermore , the C-terminus of G- CSF had a direct fusion of two asparagine residues (NN) and restriction sites for the enzymes Bjbsl and BamHI . Bbsl was subsequently utilized to directly add the NNT polymer to the C-terminus of G-CSF, while BamHI was used to clone GCSF-NN into the vector .

[0077] The oligonucleotides that were synthesized to amplify G-CSF are as follows :

oBspMIGCSF: 5' - CGATCGACCTGCAAGTCGCGACTCCGCTGGGTCCAGCTA-S' oGCSFBbsBam: 5 ' -CGGGATCCGAAGACGTGTTGTTAGGCTGGGCAAGGTGGC-S'

[0078] A diagram of the PHO-G-CSF-NN x pBSK vector is shown in Figure 2. The sequence for mature G-CSF-NN was cloned into PHO x pBSK using BspMI (destroyed) and BamHI . The subsequent addition of an NNT polymer utilized the Bbsl and BamHI sites indicated on the plasmid map . This vector confers ampicillin resistance (bla) when grown in bacteria .

Method Of Construction

[0079] G-CSF was amplified by PCR using oBspMIGCSF and oGCSFBbsBam oligonucleotides . The * 520 bp band corresponding to mature G-CSF was excised from an agarose gel and purified. The purified fragment was digested with BspMI and BamHI , purified and ligated into PHO x pBSK cut with the same enzymes . The ligation products were electroporated into ToplO competent cells and grown on LB-ampicillin plates . Minipreps were performed on ampicillin resistant colonies to isolate DNA and diagnostic digests identified putative clones . Sequence analysis determined which of the putative clones were correct .

l . C . Production Of PHO-G-CSF- (NNT) 65 x pBSK Construct

PHO-G-CSF- (NNT) 65 x pBSK Construct

[0080] The amino acid composition of this polymer encodes for the consensus mammalian N-linked glycosylation site, N-X-

( S/T) . Therefore, the polymer may be glycosylated on the threonine residues of the polymer extension when this construct is expressed in CHO cells . The expectation was that the polymeric increase in translated product size and posttranslational modification would modulate the pK parameters of G-CSF, conferring upon the protein-enhanced half-life in serum without decreasing its biological activity.

[0081] The construction of this polymer was achieved using an oligonucleotide ligation/multimerization scheme . By cutting the PHO-G-CSF-NN x pBSK construct with Bbsl , a four base underhang (GTTG) was created in the two asparagines residues added to the C-terminus of G-CSF. By designing complementary sets of oligonucleotides that code for repeating NNT triplets as well as anneal to the GTTG underhang, it was possible to multimerize the oligonucleotides that code for 9 amino acids into longer chains . Short adaptors containing a stop codon, a Bbsl site for future extension of the polymer and a BamHI site were added in low ratios to terminate the multimerization and allow for cloning of the BbsI-BamHI polymer fragment into PHO- G-CSF-NN x pBSK. [0082] The oligonucleotides used to synthesize the (NNT) 65 polymer are listed below :

Polymer Backbone Oligonucleotides

O3NNTF : 5 ' - CAACACCAACAATACCAACAATACAAA-3'

O3NNTR: 5' - GTTGTTTGTATTGTTGGTATTGTTGGT-3'

Adaptor Oligonucleotides

oDent3F : 5 ' -CAACTAGTCTTCG-S '

oDent3R: 5 ' -GATCCGAAGACTA-S '

[0083] The following sequence (NTNNTNNTN) was the repeating unit of the NNT polymer that was produced using the polymer backbone oligonucleotides of o3NNTF and o3NNTR, which show a CAAC overhang and GTTG underhang respectively that were used to multimerize the polymer .

N T N N T N N T N

5' -C AAC ACC AAC AAT ACC ΔAC AAT ACA AA-3' (o3NNTF) 3' -TGG TTG TTA TGG TTG TTA TGT TTG TTG-5' (o3NNTR)

[0084] The following is the terminating adaptor molecule that completed the polymer and included a stop codon, Bbsl site for future extension of the polymer and a BamHI site that is necessary for cloning .

Terminating Adaptor Molecule

N *

5' -C AAC TAG TCT TCG-3' (oDent3F) 3' -ATC AGA AGC CTA G-5' (oDent3R) βjbsl BamHI

[0085] A diagram of the PHO-G-CSF-NNT65 x pBSK vector is shown in Figure 3. The addition of NNT65 polymer utilized the Bbsl site (destroyed) that was located at the C-terminus of G-CSF and BamHI . As shown in Figure 3 , the Bbsl site was regenerated at the end of the NNT65 polymer for future extension of length . This vector confers ampicillin resistance (bla) when grown in bacteria .

Method Of Construction

[0086] Complementary pairs of polymer backbone oligonucleotides (o3NNTF and o3NNTR) and adaptor oligonucleotides (oDent3F and oDent3R) were phosphorylated using T4 PNK. The T4 PNK was heat-inactivated and the oligonucleotide pairs were allowed to slowly anneal on ice . Polymer multimerization was performed by mixing polymer and adaptor duplexes at 20 : 1 and 40 : 1 ratios with T4 Ligase . The T4 ligase was heat-inactivated and the entire ligation reactions were digested with BamHI overnight . Both reactions were precipitated and ran on an acrylamide gel . Material between 250 bp - 800 bp was excised and gel purified.

[0087] This material was used in a ligation with PHO-G-CSF-NN x pBSK that had been digested with BJbsI and BamHI . Chemically competent Stbl2 cells were transformed with the ligation products and grown on LB-ampicillin plates . Minipreps were performed to isolate DNA and diagnostic digests identified putative clones . Sequence analysis determined which of the putative clones were correct .

[0088] The longest clone isolated from this strategy was PHO- G-CSF-NNT65 x pBSK .

l . D. Production Of PHO-G-CSF- (NNT) 155 x pBSK Construct

PHO-G-CSF- (NNT) 155 x pBSK Construct

[0089] The construction of this clone required the addition of additional NNT residues to the PHO-G-CSF- (NNT) 65 x pBSK construct using the same oligomerization scheme . The nucleotide composition of the oligonucleotides used in this extension was altered to identify the j unction between the original polymer and the extension . These alterations maintained the original NNT composition of the polymer and utilized the same GTTG underhang and CAAC overhang strategy . By digesting PHO-GCSF- (NNT ) 65 with Bbsl and BamHI , it was possible to extend the length of the polymer using the same oligonucleotide multimerization strategy as before .

[0090] The oligonucleotides used to extend the (NNT) 65 polymer to (NNT) 155 are listed below :

Polymer Backbone Oligonucleotides

o3NNTextF: 5' - CAACACCAATAATACCAACAATACAAA-3'

o3NNTextR: 5' - GTTGTTTGTATTGTTGGTATTATTGGT-3'

Adaptor Oligonucleotides

oDent3F: 5' -CAACTAGTCTTCG-3 '

oDent3R: 5 ' -GATCCGAAGACTA-S '

[0091] As with the production of the PHO-G-CSF- (NNT) 65 x pBSK Construct, NTNNTNNTN was the repeating unit of the NNT polymer extension that was produced using the polymer backbone oligonucleotides of o3NNTextF and o3NNTextR, in which the CAAC overhang and GTTG underhang were still used to multimerize the polymer and the amino acid composition was unchanged from the original NNT65 polymer .

N T N N T N N T N

5' -C AAC ACC AAT AAT ACC AAC AAT ACA AA-3' (o3NNTextF)

3' -TGG TTA TTA TGG TTG TTA TGT TTG TTG-5' (θ3NNTextR)

[0092] The above underlined nucleotides of o3NNTextF and o3NNTextR differed from the nucleotides in the same position in o3NNTF and o3NNTR respectively .

[0093] The following is the terminating adaptor molecule that completed the NNT155 polymer and included the BamHI site necessary for cloning . oDent3F and oDent3F are the same oligonucleotides that were used for the initial NNT65 polymer .

Terminating Adaptor Molecule

N *

5 ' -C AAC TAG TCT TCG-3' (oDent3F) 3 ' -ATC AGA AGC CTA G-5' (oDent3R) Bbsi BamHI

[0094] A diagram of the PHO-G-CSF- (NNT) 155 x pBSK vector is shown in Figure 4. The extension of the NNT65 polymer by 90AA utilized the Bbsl site (destroyed) that was located at the C- terminus of PHO-G-CSF-NNT65 x pBSK and BamHI . It was noted that the Bbsl site was regenerated at the end of the NNT155 polymer for future extension of length . This vector confers ampicillin resistance [bla) when grown in bacteria .

Method Of Construction

[0095] Complementary pairs of polymer backbone oligonucleotides o3NNTextF and o3NNTextR, and adaptor oligonucleotides oDent3F and oDent3R were phosphorylated using T4 PNK . The T4 PNK was heat-inactivated and the oligonucleotide pairs were allowed to slowly anneal on ice . Polymer oligimerization was performed by mixing polymer and adaptor duplexes at 20 : 1 and 40 : 1 ratios with T4 Ligase . The T4 Ligase was heat-inactivated and the entire ligation reactions were digested with BamHI overnight . Both reactions were precipitated and ran on an acrylamide gel . Material between 250 bp to 800 bp was excised and gel purified . This material ligated into PHO-G-CSF-NNT65 x pBSK digested with Bbsl and BamHI . Chemically competent Stbl2 cells were transformed with the ligation products and grown on LB- ampicillin plates . Minipreps were performed to isolate DNA and diagnostic digests identified putative clones . Sequence analysis determined which of the putative clones were correct . [0096] The longest clone isolated from this strategy was PHO- G-CSF- (NNT) 155 x pBSK .

EXAMPLE 2

Transformation Of Host Cell And Expression Of Chimeric DNA Molecule

2. A. Production Of PHO-G-CSF- (NNT) 155 x pCE2 Construct

Preparation Of Vector pCE2

[0097] The plasmid pCE2 was derived from the plasmid pREP7b, through the following manipulations . First, the 2000 bp EBNA coding region was deleted. Next, pBR322ori was replaced with pKS-ori . Then, the RSV promoter region was replaced by the CMV enhancer and the elongation factor-la (EF-Ia) promoter and intron .

[0098] The CMV enhancer was derived from a 380 bp Xbal-Sphl fragment produced by the polymerase chain reaction (PCR) from pCEP4 ( Invitrogen, San Diego, CA) using the following primers :

5 ' -GGCTCTAGAT ATTAATAGTA ATCAATTAC-3 ' ; and 5 ' -CCTCACGCAT GCACCATGGT AATAGC-3 ' .

[0099] The EF-Ia promoter and intron (Uetsuki, et al . , J. Biol . Chem. 264 : 5791-5798 ( 1989) ) were derived from a 1200 bp SpM-Λsp718I fragment produced by PCR from human genomic DNA using the following primers :

5 ' -GGTGCATGCG TGAGGCTCCG GTGC-3 ' ; and 5 ' -GTAGTTTTCACGGTACCTGAAATGGAAG-S ' .

[0100] The two fragments were ligated into a XbaI/Λsp718I digested vector derived from pREP7b to generate pCE2.

PHO-G-CSF- (NNT) 155 x pCE2 Construct [0101] In order to express PHO-G-CSF- (NNT) 155 in mammalian cells , it was necessary to move the construct into the vector pCE2. This vector contained the minimal promoter and the first intron for the human elongation factor-1-α flanked by the immediate-early CMV enhancer . The vector also contained the hygromycin B resistance marker for mammalian selection.

[0102] A diagram of the PHO-G-CSF- (NNT) 155 x pCE2 vector is shown in Figure 5. The promoter that drives expression in CHO cells is Pcmv/ef-la . The vector was linearized for electroporation into CHO cells using Sail . This vector confers resistance to hygromycin B in mammalian cells and ampicillin resistance (bla) when grown in bacteria .

Method Of Construction

[0103] This construct was produced by isolating and gel purifying the 1100 bp Notl-BamHI fragment from PHO-G-CSF-

(NNT) 155 x pBSK. This material was ligated into pCE2 that had been digested with Notl and BamHI . Chemically competent Stbl2 cells were transformed with the ligation products and grown on LB-ampicillin plates . Minipreps were performed to isolate DNA and diagnostic digests identified putative clones . Large- scale maxipreps were performed to isolate microgram quantities of the plasmid for CHO cell transformation.

2. B . Production Of Transfectant Cell Lines

[0104] In order to produce the polymers described above, mammalian cells were used as host cells for expression . In this instance, Chinese hamster ovary (CHO) cell lines were chosen . CHO cells are widely used in the pharmaceutical industry to express recombinant protein therapeutics including G-CSF and EPO . As described below, expression cultures of G- CSF-polymer constructs in CHO cells were established .

Establishment Of Adherent Cultures [0105] The PHO-G-CSF- (NNT) 155 x pCE2 vector was linearized using the enzyme Sail . The digest was precipitated and re- suspended in 50 μL of TE . One ( 1) μg of this plasmid was used in an electroporation along with 5 x 10⁶ CHO cells . Adherent CHO cells were grown in Ham' s Nutrient Mixture F-12 ( F-12 Ham' s media) containing 10% FBS . The cells were allowed to recover overnight , and the next day media containing 700 μg/mL of hygromycin B was added to begin selection of resistant cells . The media was changed every 2-3 days as needed over the course of 2-3 weeks . Bulk pools of resistant cells were isolated and passaged two additional times in the presence of hygromycin B .

[0106] To test these cells for the secretion of PHO-G-CSF- (NNT) 155 into the media, the cells were grown in Ham' s media containing low serum media ( 0.5% ) for 3-5 days . The media was isolated and used in Western blots that were probed using a polyclonal antibody against G-CSF . The blots are reproduced in Figures 6 and 7. The difference between the blots is that the samples in Figure 7 were additionally subj ected to Peptide : N Glycosidase F ( PNGase F) treatment . As shown in Figure 6, the blots showed immunoreactive material migrating at apparent molecular weight ≈ 95 kDa . As shown in Figure 7 , digestion of these same samples with PNGase F, a glycosidase that removes N-linked glycosylation chains , reduced the immunoreactive material to apparent molecular weight ≈ 49 kDa . This corresponded approximately to the theoretical size of unmodified G-CSF- (NNT) 155 protein . Native G-CSF migrates electrophoretically at ≈ 18 kDa; the addition of the NNT polymer to the C-terminus adds substantial mass to the recombinant , polymeric molecule . The expression also appeared quite stable; no appreciable proteolytic degradation was observed for the unpurified protein present in conditioned medium. Further, as shown in Figure 7 , the decrease in size of the constructs after PNGase F treatment suggested the recombinant protein constructs were subj ect to a substantial amount of glycosylation .

Establishment Of Suspension Cultures

[0107] To facilitate purification of G-CSF- (NNT) 155 found in the conditioned media of established CHO cultures , cells were grown in a chemically defined, low protein, serum-free media ( PROCHO4-CDM, Cambrex) . In the process of adapting the cells to this media, the cells adapted from adherent to suspension growth .

[0108] Cells were grown in F-12 Ham' s 4- 10% FBS to near confluency in T-185 flasks , trypsinized and suspended in PROCHO4-CDM media . 107 cells were added to 50 mL of PROCHO4- CDM and incubated in T-185 flasks . After 4-5 passages , approximately 90% of the cells were no longer adherent and grew as a mixture of single cell and aggregated cell clumps . For conditioned media collections , typically 60 mL of fresh PROCHO4-CDM media was incubated with 7-8 mL of a high cell density culture for 5-6 days . Cells were removed from the media by centrifugation and the media was subsequently clarified using a 0.2 micron filter . The media was quantitated for yield of G-CSF- (NNT) 155 by western blot

(typically 100-200 μg/L) and stored until needed.

2. C . Expression Of G-CSF-NNT Constructs In PROCHO4-CDM

[0109] Samples were conditioned media from the foregoing bulk CHO cell lines grown for 6 days in PROCHO4-CDM. Western blots were probed using polyclonal antibody against G-CSF . As shown in Figure 8 , the size of both constructs were the same as was seen in Ham' s media (as described above) and there was no degradation observed in the G-CSF (NNT) 155 cell lines .

2. D . Optimization Of Expression

[0110] Various chemical and nutrient additives as well as various environmental parameters were tested in an attempt to determine growth conditions necessary to maximize expression of the desired product . The following approaches resulted in an increase in protein accumulation .

Chemical Additives

[0111] Although it was known that not all chemical additives result in an increase in protein production, published literature indicated that the addition of adenosine or AMP to 2.5 mM leads to cell cycle arrest; effectively prolonging cell culture viability with a concomitant increase in protein accumulation . The effect of AMP was tested on CHO- mediated production of G-CSF- (NNT) 155 production in ProCH04 chemically defined medium (CDM) . AMP was added at a final concentration of 1 mM in ProCH04 CDM. No decrease in cell viability compared to control was observed . The addition of AMP resulted in a slight increase in protein production .

Environmental Parameters

Temperature Changes

[0112] Reduced incubation temperatures for CHO cultures can lead to markedly enhanced levels of protein production . As was found with other protein production enhancement methods , the observed effect is due to enhanced protein production during cell cycle arrest . The effect of reducing the incubation temperature of the recombinant CHO line from 37⁰C to 28⁰C was examined. Although cultures maintained at 28⁰C remained viable considerably longer than those at 37⁰C, the lower temperature did not result in higher recombinant protein production .

Adaptation To Suspension Culture

[0113] The bulk CHO population was converted to spinner flask culture conditions . Adaptation to suspension culture was mediated by growth in ProCH04 CDM. Following adaptation, cells were expanded in T-flasks and seeded into spinner flasks containing ProCH05 CDM at various densities . A marked increase in protein production was observed during adaptation to suspension culture in ProCHOδ CDM, regardless of whether the cells were grown in static or spinner cultures .

Use Of Different Cell Lines As Hosts

[0114] One approach to optimization of expression may be to use a new cell line for host cells . Accordingly, a new shipment of CHO-Kl from ATCC was obtained . The new population was propagated and banked at an early passage for future use . This defined culture was used to generate stable clonal cell lines expressing the recombinant protein of interest . Briefly, CHO-Kl cells were electroporated with the vector of interest and selected for stable expression of hygromycin . 92 colonies were isolated and evaluated for expression of the recombinant protein of interest . Many of these colonies exhibited expression levels that were markedly higher than that of the original transfected population, described above .

Results

[0115] A very slight enhancement of expression was observed when cultures were treated with 1 mM AMP . Reduced culture temperatures increased the longevity of the cultures , but there was no enhancement of protein expression . Adaptation to suspension culture conditions in ProCH05 CDM dramatically enhanced expression of the recombinant protein . Also, isolated clones from an ATCC-defined CHO-Kl cell line expressed the desired protein at significantly higher levels than the originally isolated population .

Example 3

Pharmacokinetic Evaluation Of G-CSF- (NNT) 155 Conjugate

[0116] The pharmacokinetic parameters of the G-CSF- (NNT) 155 protein conj ugate was evaluated . Three other compounds were included as positive controls . The controls were Neulasta ( PEG-G-CSF) , Neupogen ( rh-G-CSF) and G-CSF compounds . The compounds were tested by single intravenous (i . v. ) administration to mice and blood was collected up to 72 hours post-dosing . The plasma was analyzed by the ELISA method .

3. A. Analytical Method

[0117] The assay employed the quantitative sandwich enzyme immunoassay technique . A monoclonal antibody specific for G- CSF had been pre-coated onto a microplate . Standards and samples were pipetted into the wells . Any G-CSF present was bound by the immobilized antibody . After washing away any unbound substances , an enzyme-linked polyclonal antibody specific for G-CSF was added to the wells . Following a wash to remove any unbound antibody-enzyme reagent , a substrate solution was added to the wells and color developed in proportion to the amount of G-CSF bound in the initial step . The color development was stopped and the intensity of the color was measured .

Reagents

[0118] The following reagents and material were used :

G-CSF Microplate : 96 well polystyrene microplate ( 12 strips of 8 wells ) coated with a murine monoclonal antibody against G-CSF .

G-CSF conj ugate : 21 mL of polyclonal antibody against G-CSF conj ugated to horseradish peroxidase, with preservative .

G-CSF standard : 2 vials ( 25 ng/mL) of recombinant human G-CSF in a buffered protein base with preservative, lyophilized .

Assay Diluent RDlA: 11 mL of a buffered protein base with preservative . Calibrator Diluent RD5 : 21 rαL of a buffered protein base with preservative . For cell culture supernate samples .

Calibrator Diluent RDβA: 21 mL of animal serum with preservative . For serum/plasma samples .

Wash Buffer Concentrate : 21 mL of a 25-fold concentrated solution of buffered surfactant with preservative .

Color Reagent A: 12.5 mL of stabilized hydrogen peroxide .

Color Reagent B : 12.5 mL of stabilized chromogen (tetramethylbenzidine) .

Stop Solution : βmL of 2N sulfuric acid.

Plate Covers : 4 adhesive strips .

Reagent Preparation

[0119] 20 mL of Wash Buffer Concentrate was diluted into deionized or distilled water to prepare 500 mL of Wash Buffer . The G-CSF Standard was reconstituted with 1 mL deionized or distilled water . This reconstitution produced a stock solution of 25000 pg/mL . The G-CSF standard was allowed to sit for a minimum of 15 minutes with gentle agitation prior to making dilutions . Nine hundred ( 900 ) μL of Calibrator Diluent RDβA was pipetted into a 2500 pg/mL tube . 600 μL of the same diluent was pipetted into the remaining 4 tubes . The stock solution was used to produce a dilution series : 25000 pg/mL

( 1 : 10 ) → 2500 pg/mL and 25000 pg/mL ( 1 : 3 ) → 833.3 pg/mL ( 1 : 3) → 277.8 pg/mL ( 1 : 3) → 92.6 pg/mL ( 1 : 3 ) → 30.9 pg/mL . Each tube was mixed thoroughly before the next transfer . The 2500 pg/mL standard served as the high standard . The Calibrator Diluent RDβA served as the zero standard (0 pg/mL) . The standard curve was performed with 6 point : 2500-833.3- 277.8-92.6-30.9-0 pg/mL, double well for each point . For the substrate solution, Color Reagent A and B was mixed together in equal volumes within 15 minutes of use . The reagents were protected from light .

Assay Procedure

[0120] All reagents and samples were brought to room temperature before use . All reagents and working standards were prepared. One hundred ( 100 ) μL of Assay Diluent RDlA were added to each well , 100 μL of standard and an appropriate volume of sample were also added to each well . The wells were covered with an adhesive strip and incubated for 2h at room temperature . Each well was aspirated and washed with 400 μL of wash buffer, which was repeated twice for a total of three washes . After the last wash, any remaining wash buffer was removed by aspirating or decanting . The plate was inverted and blotted against clean paper towels . 200 μL of G-CSF conjugate was added to each well . The wells were covered with a new adhesive strip . The wells were incubated for 2h at room temperature . The aspiration/wash described above was repeated . Two hundred (200 ) μL of Substrate Solution was added to each well . The wells were incubated for 20 min . at room temperature . The wells were protected from light . Then, 50 μL of stop solution were added to each well . Finally, the optical density of each well within 30 min . was determined using a microplate reader (VersaMax -Molecular Device) set to 450nm with correction to 570nm (OD 450nm - OD 570nm) .

Pharmacokinetic Analysis

[0121] A non-compartmental pharmacokinetic analysis (WINNonLin software version 4.1 ) was applied. The following main parameters were observed or calculated for each GCSF construct : t_f, last time at which each compound concentration was measurable ; λ_z, apparent terminal rate constant associated to the apparent terminal phase, estimated by linear regression analysis of the logarithm of the plasma concentrations versus time in the mono-exponential terminal part of the curve ; ti_/2, _z, apparent terminal half-life, calculated according to the following equation : ti_/2, _z=ln (2 ) / λ_z; AUC, area under the plasma concentration-time curve from time zero to infinity; AUC/D, area under the plasma concentration-time curve per unit of dose; MRT, mean residence time calculated as the ratio between the area under the first moment curve, AUMC, and AUC; CL, systemic clearance, calculated as CL=D/AUC; and V_ss, steady- state volume of distribution, calculated as V_SS=CL*MRT .

Results

[0122] As shown in Table 9 , pharmacokinetic studies in mice showed that G-CSF- (NNT) 155 possessed a longer half-life ( 6.2h) than either the G-CSF Control ( 1.53h) , NEUPOGEN compound

( 1.13h) or the NEULASTA compound ( 3.04h) . G-CSF- (NNT) 155' s longer half-life corresponded to a more sustained duration of effect compared to all three controls . A corresponding substantial decrease of systemic clearance was observed for G- CSF- (NNT) 155, accounting for the 9.5 mL/h/kg systemic clearance . Other conjugates containing amino acid extensions disclosed herein exhibited a decreased half-life relative to control .

Example 4

Bioavailability And Efficacy Of G-CSF- (NNT) 155 Conjugate

[0123] Neutropenia, a low absolute count of neutrophils , is a serious condition that can impede the fight against infections . To stimulate a peripheral increase in neutrophil counts , granulocyte colony stimulating factor (G-CSF) may be used as a therapy for neutropenia or in combination with other stimulating factors in collection of cells for transplant . The bioavailability of partially purified G-CSF- (NNT) 155, PEG- G-CSF (NEULASTA) and rh-G-CSF (NEUPOGEN) was determined and compared via i . v. ( intravenous) and s . c . ( subcutaneous) administration . The NEUPOGEN compound is a recombinant methionyl human G-CSF. The NEULASTA compound is a covalent conjugate of recombinant methionyl human G-CSF and monomethoxypolyethylene glycol . As described above, G-CSF- (NNT) 155 is an amino acid lengthened and/or glycosylated form of G-CSF .

4. A. Testing For Bioavailability Through ELISA

[0124] To evaluate the bioavailability of G-CSF- (NNT) 155 , an ELISA analysis was performed on plasma samples obtained from mice that were given doses of G-CSF- (NNT) 155, PEG-G-CSF and rh-G-CSF through i . v. and s . c . administration.

[0125] Test and control articles were as follows : partially purified G-CSF- (NNT) 115, PEG-G-CSF (NEULASTA) , rh-G-CSF

(NEUPOGEN) and the vehicle control (150 mM NaCl + 20 mM NaOAc + 0.004% Tween-20) ; each manufactured in a manner that was acceptable for use in animals via the designated routes of administration, i . v . and s . c .

[0126] Mice were given doses of G-CSF- (NNT) 155 , PEG-G-CSF, rh-G-CSF (each in the amount of 125 μg/kg) and a vehicle control through i . v and s . c . administration . Mouse plasma samples were isolated . If required, the mouse plasma samples were diluted .

[0127] Then, the mouse samples were analyzed with G-CSF ELISA. The main purpose of analyzing the plasma samples via ELISA was for qualitative purposes only, and not for quantitative purposes ( i . e. , not to obtain extremely precise blood plasma level concentrations ) . The G-CSF ELISA results either provided a qualitative affirmation that the test article was present in the plasma or a qualitative repudiation that the test article was not in the plasma . The plasma samples were analyzed in triplicate, using two dilutions . [0128] The results were that intravenously administered G- CSF- (NNT) 155 could be detected out to 72 hours, whereas PEG-G- CSF could only be detected out to 24 hours . In addition, both subcutaneously administered G-CSF- (NNT) 155 and PEG-G-CSF could be detected out to 72 hours . Subcutaneously administered rh- G-CSF could be detected at the 15-minute and 2-hour sampling time points .

4. B . A Single Dose Comparison Of G-CSF- (NNT) 155 and PEG-G-CSF On The Hematopoietic Effects In Mice

[0129] In another evaluation of the bioavailability and efficacy of G-CSF- (NNT) 155 , hematology analysis involving white blood cell and neutrophil count measurements was performed on plasma samples obtained from mice that were given doses of G-CSF- (NNT) 155, PEG-G-CSF and rh-G-CSF through i . v. and s . c . administration.

[0130] Test and control articles were the same as for the above G-CSF ELISA evaluation . The procedures for obtaining plasma samples were also the same as for the G-CSF ELISA evaluation . Hematology analysis results were as follows .

[0131] The white blood cell count mean data for the vehicle control ranged from 0.76 x 10³/μL to 4.35 x 10³/μL and 1.27 x 10³/μL to 4.25 x 10³/μL for the i . v . and s . c . administration, respectively . The mean absolute neutrophil count data for the vehicle control ranged from 0.11 x 10³/μL to 0.55 x 10³/μL and 0.29 x 10³/μL to 0.35 x 10³/μL for the for i . v. and s . c . administration, respectively .

[0132] The mean white blood cell count for G-CSF- (NNT) 155 increased from 1.44 x 103/μL, 15 minutes post-dose to 11.45 x 10³/μL, 72 hours post i . v. administration . The mean white blood cell count for G-CSF- (NNT) 155 increased from 3.15 x 10³/μL, 15 minutes post-dose to 11.45 x 10³/μL, 72 hours post s . c . administration !. Similarly, mean absolute neutrophil count data for G-CSF- (NNT) 155 increased from 0.04 x 10³/μL, 15 minutes post-dose to 4.24 x 10³/μL, 72 hours post i . v . administration . The mean absolute neutrophil count for G-CSF- (NNT) 155 increased from 0.25 x 10³/μL, at 15 minutes post-dose to 2.04 x 10³/μL, at 72 hours post administration and decreasing to 0.14 x 10³/μL for the s . c . route of administration at 120 hours post administration .

[0133] The mean white blood cell count for PEG-G-CSF (Neulasta) increased from 1.36 x 10³/μL, at 15 minutes post- dose to 6.03 x 10³/μL, at 24 hours post administration, and then decreased to 3.01 x 10³/μL, at 72 hour post i . v. administration . The mean white blood cell count for PEG-G-CSF (Neulasta) increased from 1.47 x 10³/μL, at 15 minutes post- dose to 4.58 x 10³/μL, at 24 hours post administration, and then decreased to 2.47 x 10³/μL, at 120 hours post s . c . administration . The mean absolute neutrophil count for PEG-G- CSF (Neulasta) increased from 0.05 x 10³/μL, at 15 minutes post-dose to 1.83 x 10³/μL, at 24 hours post administration, and then decreased to 0.20 x 10³/μL, at 72 hours post i . v . administration . The mean absolute neutrophil count for PEG-G- CSF (Neulasta) increased from 0.18 x 10³/μL, at 15 minutes post-dose to 1.04 x 10³/μL, at 24 hours post administration and then decreased to 0.22 x 10³/μL, 120 hours post s . c . administration .

[0134] The mean white blood cell count for rh-G-CSF (Neupogen) decreased from 1.30 x 10³/μL, at 15 minutes post- dose to 1.19 x 10³/μL at 2 hours post s . c . administration . The mean absolute neutrophil count for rh-G-CSF (Neupogen) increased from 0.11 x 10³/μL, at 15 minutes post-dose to 0.49 x 10³/μL at 2 hours post s . c . route of administration .

[0135] The result showed that intravenous administration of G-CSF- (NNT ) 155 demonstrated a substantial increase in white blood cell counts , through 72 hours post-dose, which correlated directly to an increase in absolute neutrophil counts . This mean increase exceeded the white blood cell count of the vehicle control by approximately 260% . Similarly, a mean increase in the white blood cell count for the s . c . administration of G-CSF- (NNT) 155 exceeded that of both the vehicle control and PEG-G-CSF by approximately 295% , 72 hours post-dose . However, both the mean white blood cell count and the mean absolute neutrophil count returned to that of both the vehicle control and PEG-G-CSF at 120 hours post- dose .

[0136] In some embodiments , the peptide contains the sequence NNT, NNNNT or NNNNNT, and n is an integer of about 150 to about 160. In some of these embodiments , the biologically active protein is G-CSF.

[0137] All publications cited in the specification are indicative of the level of skill of those skilled in the art to which this invention pertains . All these publications are herein incorporated by reference to the same extent as if each individual publication were specifically and individually indicated as being incorporated by reference .

[0138] Although the invention herein has been described with reference to particular embodiments , it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention . It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims . TABLE 1

TABLE 2

TABLE 3

TABLE 4

TABLE 4 (Continued)

TABLE 5

01

TABLE 6

TABLE 7

-

TABLE 8

TABLE 9

Claims

1. A biologically active protein conjugate comprising a biologically active polypeptide coupled via a peptide bond to a polypeptide comprising from 2 to about 500 units of a peptide comprising as a maj or constituent, two or more residues of one amino acid selected from GIy (G) , Asn (N) and GIn (Q) , and as a minor constituent , one or more residues of one amino acid selected from Ala (A) , Ser ( S ) , Thr (T) , Asp ( D) , GIn (Q) , GIu (E) , His (H) and Asn (N) , provided that none of said amino acids is present in said maj or constituent and said minor constituent, such that said biologically active protein conj ugate has a modified plasma half-life compared to the intrinsic half-life of the unconjugated biologically active polypeptide .

2. The protein conjugate of claim 1, wherein said peptide comprises 3-6 amino acid residues .

3. The protein conjugate of claim 1, wherein said peptide comprises 3 amino acid residues .

4. The protein conjugate of claim 1 , wherein said peptide comprises 4 amino acid residues .

5. The protein conjugate of claim 1, wherein said peptide comprises 5 amino acid residues .

6. The protein conj ugate of claim 5 , wherein said minor constituent comprises 1 amino acid residue of said peptide .

7. The protein conj ugate of claim 1 , wherein said peptide comprises 6 amino acid residues .

8. The protein conjugate of claim 7 , wherein said minor constituent comprises 1 amino acid residue of said peptide .

9. The protein conjugate of claim 1 , wherein said peptide has a sequence consisting of N and T amino acid residues .

10. The protein conj ugate of claim 1 , wherein said peptide has a sequence consisting of N and E amino acid residues .

11. The protein conjugate of claim 1, wherein said peptide has a sequence consisting of Q and S amino acid residues .

12. The protein conjugate of claim 1 , wherein said peptide has a sequence consisting of N and Q amino acid residues .

13. The protein conj ugate of claim 1 , wherein said polypeptide is N-terminal with respect to said biologically active polypeptide .

14. The protein conjugate of claim 1, wherein said polypeptide is C-terminal with respect to said biologically active polypeptide .

15. The protein conj ugate of claim 1 , wherein said polypeptide is situated at both the N and C-terminus with respect to said biologically active polypeptide .

16. The protein conj ugate of claim 1 , wherein said biologically active polypeptide is a cytokine .

17. The protein conjugate of claim 16, wherein said cytokine is granulocyte colony stimulating factor (G-CSF) .

18. The protein conj ugate of claim 16 , wherein said cytokine is human growth hormone .

19. The protein conj ugate of claim 16, wherein said cytokine is an interferon .

20. The protein conjugate of claim 19 , wherein said interferon is a beta-interferon.

21. The protein conj ugate of claim 19, wherein said interferon is a gamma-interferon .

22. The protein conjugate of claim 1, wherein said biologically active polypeptide comprises an antibody, antibody fragment, proteolytic antibody fragment or domain, single chain antibody, genetically or chemically optimized antibody or fragment thereof .

23. The protein conjugate of claim 1, wherein said biologically active polypeptide comprises a soluble gpl20 or gpl60 glycoprotein .

24. The protein conjugate of claim 1 , wherein said biologically active polypeptide comprises a coagulation factor .

25. The protein conj ugate of claim 1, wherein said biologically active polypeptide comprises a soluble receptor .

26. The protein conjugate of claim 25, wherein said soluble receptor comprises a tumor necrosis factor (TNF) -α type II receptor .

27. The protein conjugate of claim 1, wherein said biologically active polypeptide comprises erythropoietin .

28. The protein conjugate of claim 1, having a modified half-life that is decreased relative compared to the intrinsic half-life of the unconj ugated biologically active polypeptide .

29. The protein conjugate of claim 28 , wherein said biologically active polypeptide comprises a recombinant activated protein C .

30. The protein conjugate of claim 28 , wherein said biologically active polypeptide comprises a recombinant Factor

VII .

31. The protein conjugate of claim 1, wherein said biologically active polypeptide is a therapeutic enzyme .

32. A composition comprising the protein conjugate of claim 1 and a carrier .

33. The composition of claim 32 , wherein said carrier is a pharmaceutically effective carrier .

34. A chimeric DNA molecule encoding the protein conjugate of claim 1.

35. A vector comprising the chimeric DNA molecule of claim 34.

36. The vector of claim 35, which is a plasmid.

37. The vector of claim 36, wherein said plasmid is pCE2.

38. A cell transformed with the vector of claim 35.

39. The cell of claim 38 , which is a mammalian cell .

40. The cell of claim 39, wherein said mammalian cell is a Chinese hamster ovary (CHO) cell .

41. The cell of claim 38 , which is a bacterium.

42. The cell of claim 41, wherein the bacterium is E. coli .

43. The cell of claim 38 , which is yeast .

44. A method of making a biologically active protein conjugate comprising a biologically active polypeptide coupled via peptide bond to a polypeptide comprising from 2 to about 500 units of a peptide comprising as a maj or constituent, two or more residues of one amino acid selected from GIy (G) , Asn (N) and GIn (Q) , and as a minor constituent, one or more residues of one amino acid selected from Ala (A) , Ser ( S) , Thr (T ) , Asp ( D) , GIn (Q) , GIu (E) , His (H) and Asn (N) , provided that none of said amino acids is present in said maj or constituent and said minor constituent , such that said biologically active protein has a modified plasma half-life compared to intrinsic half-life of the unconj ugated biologically active polypeptide, said method comprising :

culturing a cell transformed with a chimeric DNA molecule encoding said protein conjugate under conditions whereby said DNA is expressed, thereby producing said protein conjugate; and

extracting an expression product of said chimeric DNA molecule from said cell .

45. The method of claim 44 , wherein said chimeric DNA molecule is introduced into said cell through insertion of said chimeric DNA molecule into a vector which is then transformed into said cell .

46. A method of determining whether a given protein conj ugate exhibits a modified plasma half-life compared to the intrinsic half-life of the unconjugated biologically active polypeptide, comprising :

a) preparing a protein conj ugate comprising a biologically active polypeptide coupled via a peptide bond to a polypeptide that comprises from 2 to about 500 repeating units of a peptide motif, wherein the motif comprises a maj or constituent and a minor constituent , in which the maj or constituent comprises or consists of two or more residues of one amino acid selected from the group consisting of GIy (G) , Asn (N) and GIn (Q) , and the minor constituent comprises or consists of one or more residues of one amino acid selected from the group consisting of Ala (A) , Ser (S) , Thr (T) , Asp ( D) , GIn (Q) , GIu (E) , His (H) and Asn (N) , wherein none of the amino acids is present in both the maj or constituent and said minor constituent , and

b) testing the protein conj ugate to determine whether the protein conjugate has a modified plasma half- life compared to the intrinsic half-life of the unconjugated biologically active polypeptide .