Method for preparing a polymer conjugate
View Patent ↗Provided herein is a straightforward and efficient method for covalently attaching a polyethylene glycol polymer to docetaxel. The method involves, among other things, a step of reacting docetaxel with a polyethylene glycol polymer comprising a functional group reactive with a hydroxyl group within docetaxel in the presence of a coupling reagent and DPTS. The result of the reacting step is the formation of a polyethylene glycol-docetaxel conjugate having a single polyethylene glycol covalently attached, via an ester linkage, to the hydroxyl group within docetaxel.
1. A method for covalently attaching a polyethylene glycol polymer to docetaxel, said method comprising the step of:
reacting docetaxel with a polyethylene glycol comprising a functional group reactive with a hydroxyl group within docetaxel in the presence of a coupling reagent and 4-(dimethylamino)-pyridinium-p-toluenesulfonate (DPTS), under conditions effective to promote reaction between said docetaxel and said polyethylene glycol to thereby form a polyethylene glycol docetaxel conjugate having a single polyethylene glycol covalently attached, via an ester linkage, to the hydroxyl group within docetaxel.
2. The method of claim 1 , wherein said coupling reagent is a carbodiimide.
3. The method of claim 2 , wherein said coupling reagent is selected from the group consisting of dicyclohexylcarbodiimide (DCC), N,N′-diisopropylcarbodiimide (DIC), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDAC), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (EDC), N-tert-butyl-N′-m ethylcarbodiimide (TBMC), and N-tert-butyl-N′-ethylcarbodiimide (TBEC).
4. The method of claim 1 , wherein said coupling reagent is N,N′-diisopropylcarbodiimide.
5. The method of claim 1 , wherein said reacting step is carried out in an organic solvent selected from the group consisting of dichloromethane, chloroform, acetonitrile, and tetrahydrofuran.
6. The method of claim 5 , wherein said reacting step is carried out at a temperature ranging from 0° C. to 100° C.
7. The method of claim 6 , wherein said reacting step is carried out at room temperature.
8. The method of claim 1 , wherein the amount of DPTS in said reacting step ranges from about 0.05 to 0.75 equivalents relative to said hydroxyl group within docetaxel.
9. The method of claim 8 , wherein the amount of DPTS in said reacting step ranges from about 0.10 to 0.60 equivalents relative to said hydroxyl group within docetaxel.
10. The method of claim 1 , wherein the amount of said coupling reagent ranges from about 1.25 to 5 equivalents relative to said hydroxyl group within docetaxel.
11. The method of claim 1 , wherein said second functional group is carboxyl.
12. The method of claim 1 , wherein said single hydroxyl group within docetaxel is the 2′-hydroxyl group of docetaxel.
13. The method of claim 1 , wherein said polyethylene glycol is selected from the group consisting of linear, branched, forked, and multi-armed polyethylene glycol.
14. The method of claim 13 , wherein said polyethylene glycol comprises from 3 to 25 arms.
15. The method of claim 14 , wherein said polyethylene glycol comprises a number of arms selected from 3, 4, 5, 6, 7, 8, 9, and 10.
16. The method of claim 15 , wherein said polyethylene glycol comprises a polyol or a polyamine core.
17. The method of claim 16 , wherein said polyethylene glycol comprises a polyol core selected from glycerol, trimethylolpropane, sorbitol, hexaglycerol, and pentaerythritol.
18. The method of claim 1 , wherein said polyethylene glycol comprises from 1 to about 10 of said second functional groups.
19. The method of claim 18 , wherein said polyethylene glycol comprises a number of said second functional groups selected from 1, 2, 3, 4, 5, and 6.
20. The method of claim 19 , wherein said polyethylene glycol comprises a structure selected from:
wherein
n ranges from about 5 to about 400,
m ranges from 0 to 5, and
the total molecular weight of the multi-arm polymer ranges from about 1500 to about 60,000 daltons.
21. The method of claim 20 , said method lacking a protection step.
22. The method of claim 21 , wherein said polyethylene glycol is:
23. The method of claim 22 , wherein said reacting step forms a conjugate having docetaxel covalently attached to said polyethylene glycol at only its 2′ position.
24. The method of claim 23 , wherein said reacting step forms a conjugate possessing an average number of docetaxel molecules per polyethylene glycol ranging from about 2.1 to 3.75.
25. The method of claim 24 , wherein said reacting step forms a conjugate possessing an average number of docetaxel molecules per polyethylene glycol ranging from about 2.3 to 3.2.