High molecular weight biodegradable gelatin-doxorubicin conjugate

1. A high molecular weight compound comprising gelatin and doxorubicin, wherein the gelatin is covalently linked to doxorubicin through a cleavable linker, and wherein the average molecular weight of the compound is at least 40 kDa.

2. The compound of claim 1 , wherein the cleavable linker comprises a cleavable portion selected from a group consisting of: a pH-sensitive portion, a heat-sensitive portion, a light-sensitive portion, an enzymatically-cleavable portion, and a combination thereof.

3. The compound of claim 2 , wherein the pH-sensitive portion comprises a hydrazone bond, an ester, —S—S—, a carbamate, a vinyl ether, a silyl ether, or a combination thereof.

4. The compound of claim 1 , wherein the cleavable linker further comprises a spacer.

5. The compound of claim 1 , wherein the linker comprises a hydrazine bond and glycylglycine.

6. The compound of claim 1 , corresponding to Formula (I):

wherein x is determined by the molecular weight of the compound.

7. A method of preparing a compound comprising gelatin and doxorubicin, the method comprising reacting a gelatin-linker conjugate with doxorubicin in formamide, wherein

the gelatin-linker conjugate is reacted with the doxorubicin in pH less than 7.

8. The method of claim 7 , further comprising:

(i) reacting gelatin dissolved in formamide with a linker to form the gelatin-linker conjugate; and

(ii) precipitating the gelatin-linker conjugate with an alcohol.

9. The method of claim 8 , wherein the linker is cleavable.

10. The method of claim 9 , wherein the linker comprises a cleavable portion selected from a group consisting of: a pH-sensitive portion, a heat-sensitive portion, a light-sensitive portion, an enzymatically-cleavable portion, and a combination thereof.

11. The method of claim 10 , wherein the linker comprises a hydrazine bond.

12. The method of claim 7 , wherein the gelatin-linker conjugate is a gelatin-glycylglycine-hydrazide conjugate.

13. The method of claim 12 , further comprising:

(i) reacting gelatin dissolved in formamide with glycylglycine to form a gelatin glycylglycine conjugate;

(ii) precipitating the gelatin-glycylglycine conjugate with a first alcohol;

(iii) reacting the gelatin-glycylglycine conjugate with hydrazine in formamide to form the gelatin-glycylglycine-hydrazide conjugate; and

(iv) precipitating the gelatin-glycylglycine-hydrazide conjugate with a second alcohol.

14. The method of claim 13 , further comprising adding 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) in step (i) or further comprising adding EDC in step (iii).

15. The method of claim 13 , wherein glycylglycine is attached to a solid support in step (i).

16. The method of claim 12 , wherein the gelatin-glycylglycine-hydrazide conjugate is reacted with doxorubicin in pH less than 7 and in the presence of a drying agent.

17. A method of preparing a compound comprising gelatin and doxorubicin, the method comprising reacting an amino-blocked doxorubicin-hydrazide-glycylglycine conjugate with high molecular weight gelatin in formamide in pH of less than 7.

18. The method of claim 17 , further comprising;

(i) reacting doxorubicin with an amine to form an amino-blocked doxorubicin;

(ii) reacting the amino-blocked doxorubicin with hydrazine to form an amino-blocked doxorubicin-hydrazide conjugate; and

(iii) reacting the amino-blocked doxorubicin-hydrazide conjugate with glycylglycine to form the amino-blocked doxorubicin-hydrazide-glycylglycine conjugate.

19. A method of treating cancer in a subject, the method comprising administering a pharmaceutically-effective amount of a compound of claim 1 to the subject.

20. The method of claim 19 , wherein the administering is local or systemic.

21. A pharmaceutical composition comprising a compound of claim 1 and a pharmaceutically acceptable carrier.