Hydroxypatite-targeting poly(ethylene glycol) and related polymers

• US 20040023852A1
• Filed: 08/06/2003
• Published: 02/05/2004
• Est. Priority Date: 10/18/2001
• Status: Active Grant

• Current Assignee: Nektar Therapeutics
• Original Assignee: Nektar Therapeutics
• Inventors: Roberts, Michael J., Kozlowski, Antoni
• Granted Patent: US 7,829,074 B2
• Time in Patent Office: Days
• US Class Current: 514/7
• CPC Class Codes: A61K 31/715 Polysaccharides, i.e. having more than five saccharide radicals attached to each other by glycosidic linkages; Derivatives thereof, e.g. ethers, esters
• CPC Class Codes: A61K 47/18 Amines; Amides; Ureas; Quaternary ammonium compounds; Amino acids; Oligopeptides having up to five amino acids
• CPC Class Codes: A61K 47/24 containing atoms other than carbon, hydrogen, oxygen, halogen, nitrogen or sulfur, e.g. cyclomethicone or phospholipids
• CPC Class Codes: A61K 47/60 the organic macromolecular compound being a polyoxyalkylene oligomer, polymer or dendrimer, e.g. PEG, PPG, PEO or polyglycerol
• CPC Class Codes: C08G 65/329 with organic compounds
• CPC Class Codes: C08G 65/3353 containing oxygen in addition to phosphorus
• CPC Class Codes: C08L 2203/02 for biomedical use

Abstract

Isolatable, hydroxyapatite-targeting polymeric structures, and biologically active conjugates thereof, are provided. The polymeric structure includes a linear or branched water-soluble and non-peptidic polymer backbone, such as a PEG backbone, having at least two termini, a first terminus being covalently bonded to a hydroxyapatite-targeting moiety, such as a bisphosphonate, and a second terminus covalently bonded to a chemically reactive group, wherein said chemically reactive group is protected or unprotected. Methods of preparing and using hydroxyapatite-targeting polymeric structures, and biologically active conjugates thereof, are also provided.

Claims

1. An isolatable hydroxyapatite-targeting polymeric structure comprising a linear or branched water-soluble and non-peptidic polymer backbone having at least two termini, a first terminus being covalently bonded to a hydroxyapatite-targeting moiety and a second terminus covalently bonded to a chemically reactive group, wherein said chemically reactive group is protected or unprotected.

2. A polymeric structure according to claim 1, wherein said hydroxyapatite-targeting moiety is selected from the group consisting of tetracycline, calcein, bisphosphonates, polyaspartic acid, polyglutamic acid, and aminophosphosugars.

3. A polymeric structure according to claim 1, wherein said hydroxyapatite-targeting moiety is a bisphosphonate.

4. A polymeric structure according to claim 3, wherein the bisphosphonate has the following structure:

5. A polymeric structure according to claim 4, wherein Y is —

NH(CH₂)p—

, p is about 2 to about 6, Z is —

OH, and each W is hydrogen.

6. A polymeric structure according to claim 1, wherein said chemically reactive group is selected from the group consisting of hydroxyl, protected hydroxyl, active ester, active carbonate, acetal, aldehyde, aldehyde hydrates, alkenyl, acrylate, methacrylate, acrylamide, active sulfone, amine, protected amine, hydrazide, protected hydrazide, thiol, protected thiol, carboxylic acid, protected carboxylic acid, isocyanate, isothiocyanate, maleimide, vinylsulfone, dithiopyridine, vinylpyridine, iodoacetamide, epoxide, glyoxals, diones, mesylates, tosylates, and tresylate.

7. A polymeric structure according to claim 1, wherein said chemically reactive group is a protected amine or a protected hydrazide, wherein the protecting group is selected from the group of t-Boc and Fmoc.

8. A polymeric structure according to claim 1, wherein said chemically reactive group is a protected thiol, wherein the protecting group is orthopyridyldisulfide.

9. A polymeric structure according to claim 1, wherein said chemically reactive group is a protected carboxylic acid or a protected hydroxyl, wherein the protecting group is benzyl.

10. A polymeric structure according to claim 1, wherein said chemically reactive group is selected from the group consisting of hydroxyl, protected hydroxyl, amine, protected amine, carboxylic acid, protected carboxylic acid, maleimide, active carbonates and active esters.

11. A polymeric structure according to claim 1, wherein said polymer backbone is selected from the group consisting of poly(alkylene glycol), poly(oxyethylated polyol), poly(olefinic alcohol), poly(vinylpyrolidone), poly(hydroxypropylmethacrylamide), poly(α

-hydroxy acid), poly(vinyl alcohol), polyphosphazene, polyoxazoline, and copolymers, terpolymers, derivatives and mixtures thereof.

12. A polymeric structure according to claim 1, wherein said polymer backbone is poly(alkylene glycol).

13. A polymeric structure according to claim 12, wherein said polymer backbone is poly(ethylene glycol).

14. A polymeric structure according to claim 12, wherein the poly(alkylene glycol) backbone comprises a hydrolytically or enzymatically degradable linkage.

15. A polymeric structure according to claim 14, wherein the degradable linkage is selected from the group consisting of imine, carbonate, carboxylate ester, phosphoester, orthoester, acetal, carbamate, disulfide, and peptide.

16. A polymeric structure according to claim 1, wherein said polymer backbone has from 2 to about 300 termini.

17. A polymeric structure according to claim 1, wherein the polymeric structure has the following structure:

Q-POLY-L-T

wherein POLY is a water-soluble and non-peptidic polymer, Q is a protected or unprotected chemically reactive group, L is a linker, and T is a hydroxyapatite-targeting moiety.

18. A polymeric structure according to claim 17, wherein POLY is selected from the group consisting of poly(alkylene glycol), poly(oxyethylated polyol), poly(olefinic alcohol), poly(vinylpyrolidone), poly(hydroxypropylmethacrylamide), poly(a-hydroxy acid), poly(vinyl alcohol), polyphosphazene, polyoxazoline, and copolymers, terpolymers, derivatives and mixtures thereof.

19. A polymeric structure according to claim 17, wherein L is selected from the group consisting of ether linkages, thio-ether linkages, amide linkages, amine linkages, urea linkages, and carbamate linkages.

20. A polymeric structure according to claim 17, wherein POLY is a poly(ethylene glycol) having an average molecular weight from about 200 Da to about 100,000 Da.

21. A polymeric structure according to claim 17, wherein T is selected from the group consisting of tetracycline, calcein, bisphosphonates, polyaspartic acid, polyglutamic acid, and aminophosphosugars.

22. A polymeric structure according to claim 17, wherein T is a bisphosphonate.

23. A polymeric structure according to claim 17, wherein Q is selected from the group consisting of hydroxyl, protected hydroxyl, active ester, active carbonate, acetal, aldehyde, aldehyde hydrates, alkenyl, acrylate, methacrylate, acrylamide, active sulfone, amine, protected amine, hydrazide, protected hydrazide, thiol, protected thiol, carboxylic acid, protected carboxylic acid, isocyanate, isothiocyanate, maleimide, vinylsulfone, dithiopyridine, vinylpyridine, iodoacetamide, epoxide, glyoxals, diones, mesylates, tosylates, and tresylate.

24. A polymeric structure according to claim 17, wherein Q is selected from the group consisting of hydroxyl, protected hydroxyl, amine, protected amine, carboxylic acid, protected carboxylic acid, maleimide, active carbonates and active esters.

25. A polymeric structure according to claim 1, having the following structure:

Q-PEG-L-T

wherein PEG is a poly(ethylene glycol) having an average molecular weight from about 200 Da to about 100,000 Da, Q is a protected or unprotected chemically reactive group selected from the group consisting of hydroxyl, protected hydroxyl, active ester, active carbonate, acetal, aldehyde, aldehyde hydrates, alkenyl, acrylate, methacrylate, acrylamide, active sulfone, amine, protected amine, hydrazide, protected hydrazide, thiol, protected thiol, carboxylic acid, protected carboxylic acid, isocyanate, isothiocyanate, maleimide, vinylsulfone, dithiopyridine, vinylpyridine, iodoacetamide, epoxide, glyoxals, diones, mesylates, tosylates, and tresylate, L is a linker, and T is a bisphosphonate.

26. A polymeric structure according to claim 25, wherein L is selected from the group consisting of ether linkages, thio-ether linkages, amide linkages, amine linkages, urea linkages, and carbamate linkages.

27. A polymeric structure according to claim 1, having the following structure:

T-L-POLY_a-R(-POLY_b-X)_q

wherein POLY_a and POLY_b are water-soluble and non-peptidic polymer backbones that may be the same or different;

each X is independently selected from the group consisting of alkyl, substituted alkyl, aryl, substituted aryl, hydroxyl, protected hydroxyl, active ester, active carbonate, acetal, aldehyde, aldehyde hydrates, alkenyl, acrylate, methacrylate, acrylamide, active sulfone, amine, protected amine, hydrazide, protected hydrazide, thiol, protected thiol, carboxylic acid, protected carboxylic acid, isocyanate, isothiocyanate, maleimide, vinylsulfone, dithiopyridine, vinylpyridine, iodoacetamide, epoxide, glyoxals, diones, mesylates, tosylates, tresylate, and L-T, with the proviso that at least one X is not a hydroxyapatite-targeting moiety;

R is a central core molecule;

L is a linker;

T is said hydroxyapatite-targeting moiety; and

q is an integer from 2 to about 300.

28. A polymeric structure according to claim 27, wherein POLY_a and POLY_b are poly(ethylene glycol).

29. A polymeric structure according to claim 27, wherein R is selected from the group consisting of trimethylolpropane, di-trimethylolpropane, glycerol, pentaerythritol, sorbitol, lysine, and di-lysine.

30. A polymeric structure according to claim 27, wherein L is selected from the group consisting of ether linkages, thio-ether linkages, amide linkages, amine linkages, urea linkages, and carbamate linkages.

31. A hydroxyapatite-targeting, biologically active polymeric structure comprising a linear or branched water-soluble and non-peptidic polymer backbone having at least two termini, a first terminus being covalently bonded to a hydroxyapatite-targeting moiety and a second terminus covalently bonded to a biologically active agent through a linker, wherein at least one of the polymer backbone and the linker comprise a hydrolytically or enzymatically degradable linkage.

32. A polymeric structure according to claim 31, wherein the degradable linkage is selected from the group consisting of imine, carbonate, carboxylate ester, phosphoester, orthoester, acetal, carbarrate, disulfide, and peptide.

33. A polymeric structure according to claim 31, having the following structure:

D-L′

-POLY-L-T

wherein POLY is a water-soluble and non-peptidic polymer, D is a biologically active agent, L and L′

are linkers which may be the same or different, and T is a hydroxyapatite-targeting moiety, and wherein at least one of POLY, L, and L′

comprise a hydrolytically or enzymatically degradable linkage.

34. A polymeric structure according to claim 33, wherein T is a bisphosphonate.

35. A polymeric structure according to claim 31, having the following structure:

T-L-POLY_a-R(-POLY_b-L′

-A)_q

wherein POLY_a and POLY_b are water-soluble and non-peptidic polymer backbones that may be the same or different;

each A is independently selected from the group consisting of hydroxyapatite-targeting moieties and biologically active agents, with the proviso that at least one A is a biologically active agent;

R is a central core molecule;

L and L′

are linkers which may be the same or different;

T is a hydroxyapatite-targeting moiety;

q is an integer from 2 to about 300; and

wherein at least one of POLY_a,

POLY_b, L and L′

comprises a hydrolytically or enzymatically degradable linkage.

36. A polymeric structure according to claim 35, wherein POLY_a and POLY_b are poly(ethylene glycol).

37. A polymeric structure according to claim 31, having the following structure:

D-L′

-POLY-L-T

wherein POLY is poly(ethylene glycol), D is a biologically active agent having at least one hydroxy group, L is a hydrolytically stable linkage, L′

is a hydrolytically degradable linkage, and T is a bisphosphonate moiety.

38. A polymeric structure according to claim 37, wherein L′

is selected from the group consisting of ester, carbamate, carbonate, and acetal.

39. A polymeric structure according to claim 37, wherein L is selected from the group consisting of ether, thio-ether, amide, and carbamate.

40. A method of preparing an isolatable hydroxyapatite-targeting polymeric structure, comprising:

providing a polymeric structure comprising a linear or branched water-soluble and non-peptidic polymer backbone having at least two termini, a first terminus covalently bonded to a first protected chemically reactive group and a second terminus covalently bonded to a second chemically reactive group selected from the group consisting of active carbonates and active esters; and

reacting the second chemically reactive group with a hydroxyapatite-targeting moiety to form a hydroxyapatite-targeting polymeric structure.

41. A method according to claim 40, wherein the first protected chemically reactive group is selected from the group consisting of protected hydroxyl, protected amine, protected carboxylic acid, protected hydrazide, and protected thiol.

42. A method according to claim 40, wherein the polymer backbone is selected from the group consisting of poly(alkylene glycol), poly(oxyethylated polyol), poly(olefinic alcohol), poly(vinylpyrolidone), poly(hydroxypropylmethacrylamide), poly(α

-hydroxy acid), poly(vinyl alcohol), polyphosphazene, polyoxazoline, and copolymers, terpolymers, derivatives and mixtures thereof.

43. A method according to claim 40, wherein the second chemically reactive group is selected from the group consisting of N-hydroxysuccinimidyl esters, 1-benzotriazolyl esters, N-hydroxysuccinimidyl carbonates and 1-benzotriazolyl carbonates.

44. A method according to claim 40, wherein said providing step comprises providing a polymeric structure having the following structure:

X—

O—

CH₂CH₂O—

(CH₂CH₂O)_n—

CH₂CH₂—

CO₂Y′

wherein X is an active carbonate or an active ester, Y′

is benzyl, and n is about 3 to about 2000.

45. A method according to claim 40, wherein the hydroxyapatite-targeting moiety is selected from the group consisting of tetracycline, calcein, bisphosphonates, polyaspartic acid, polyglutamic acid, and aminophosphosugars.

46. A method according to claim 40, further comprising the steps of:

deprotecting the first protected chemically reactive group;

converting the deprotected first chemically reactive group to an active carbonate or an active ester;

reacting the active carbonate or active ester with a biologically active agent such that the biologically active agent is attached to the polymeric structure.

47. A method according to claim 46, wherein the biologically active agent is selected from a group consisting of peptides, proteins, enzymes, small molecule drugs, dyes, nucleosides, oligonucleotides, lipids, phospholipids, cells, viruses, liposomes, microparticles and micelles.

48. A method of utilizing a bone surface in an organism as a reservoir for a releasable biologically active agent, comprising:

providing a hydroxyapatite-targeting, biologically active polymeric structure comprising a linear or branched water-soluble and non-peptidic polymer backbone having at least two termini, a first terminus being covalently bonded to a hydroxyapatite-targeting moiety and a second terminus covalently bonded to a biologically active agent through a linker, wherein at least one of the polymer backbone and the linker comprise a hydrolytically or enzymatically degradable linkage; and

administering a therapeutically effective amount of the polymeric structure to a bone-containing organism such that at least a portion of the polymeric structure is bonded to a bone surface by the hydroxyapatite-targeting moiety.

49. A method according to claim 48, wherein the degradable linkage is selected from the group consisting of imine, carbonate, carboxylate ester, phosphoester, orthoester, acetal, carbamate, disulfide, and peptide.

50. A method according to claim 48, wherein the hydroxyapatite-targeting, biologically active polymeric structure has the following structure:

D-L′

-POLY-L-T

wherein POLY is a water-soluble and non-peptidic polymer, D is a biologically active agent, L and L′

are linkers which may be the same or different, and T is a hydroxyapatite-targeting moiety, and wherein at least one of POLY, L and L′

comprises a hydrolytically or enzymatically degradable linkage.

51. A method according to claim 50, wherein POLY is a poly(ethylene glycol) having an average molecular weight from about 200 Da to about 100,000 Da.

52. A method according to claim 50, wherein T is a bisphosphonate.

53. A method according to claim 48, wherein the hydroxyapatite-targeting, biologically active polymeric structure has the following structure:

T-L-POLY_a-R(-POLY_b-L′

-A)_q

wherein POLY_a and POLY_b are water-soluble and non-peptidic polymer backbones that may be the same or different;

each A is independently selected from the group consisting of hydroxyapatite-targeting moieties and biologically active agents, with the proviso that at least one A is a biologically active agent;

R is a central core molecule;

L and L′

are linkers which may be the same or different;

T is a hydroxyapatite-targeting moiety; and

q is an integer from 2 to about 300; and

wherein at least one of POLY_a,

POLY_b, L and L′

comprises a hydrolytically or enzymatically degradable linkage.

54. A method according to claim 53, wherein POLY_a and POLY_b are poly(ethylene glycol).

55. A method according to claim 48, wherein said administering step comprises administering the polymeric structure by a route selected from the group consisting of oral, pulmonary, intravenous, subcutaneous, intramuscular, buccal, nasal, ocular, and rectal.

56. A method according to claim 48, wherein said administering step comprises administering the polymeric structure with at least one pharmaceutically acceptable carrier, excipient or diluent.