Details for Patent: 7,786,221

Title:	Multi-armed, monofunctional, and hydrolytically stable derivatives of poly (ethylene glycol) and related polymers for modification of surfaces and molecules
Abstract:	Multi-armed, monofunctional, and hydrolytically stable polymers are described having the structure ##STR00001## wherein Z is a moiety that can be activated for attachment to biologically active molecules such as proteins and wherein P and Q represent linkage fragments that join polymer arms poly.sub.a and poly.sub.b, respectively, to central carbon atom, C, by hydrolytically stable linkages in the absence of aromatic rings in the linkage fragments. R typically is hydrogen or methyl, but can be a linkage fragment that includes another polymer arm. A specific example is an mPEG disubstituted lysine having the structure ##STR00002## where mPEG.sub.a and mPEG.sub.b have the structure CH.sub.3O--(CH.sub.2CH.sub.2O).sub.nCH.sub.2CH.sub.2-- wherein n may be the same or different for poly.sub.a- and poly.sub.b- and can be from 1 to about 1,150 to provide molecular weights of from about 100 to 100,000.
Inventor(s):	Harris; J. Milton (Huntsville, AL), Veronese; Francesco Maria (Padua, IT), Caliceti; Paola (Padua, IT), Schiavon; Oddone (Padua, IT)
Assignee:	Nektar Therapeutics (San Carlos, CA)
Filing Date:	Sep 18, 2008
Application Number:	12/284,357
Claims:	1. A monofunctional water-soluble polymer having the structure: ##STR00039## where: R is H, C is carbon, Z is a moiety comprising a single reactive site, X, at its terminus, poly.sub.a and poly.sub.b are each independently CH.sub.3O(CH.sub.2CH.sub.2O).sub.nCH.sub.2CH.sub.2--, where n in each of poly.sub.a and poly.sub.b ranges from 1 to 1150, and P and Q are each independently a hydrolytically stable linker fragment comprising from 1 to 10 atoms, each linker fragment (i) joined to poly.sub.a or poly.sub.b, respectively, by an ether linkage, and (ii) absent an aromatic ring. 2. The monofunctional water soluble polymer of claim 1, having the structure: ##STR00040## wherein Z is --R.sub.z--X, where R.sub.z is a linear linkage fragment attached to the central carbon, C, and X is the terminal reactive site. 3. The monofunctional water soluble polymer of claim 2, wherein R.sub.z comprises an amide linkage. 4. The monofunctional water soluble polymer of claim 3, wherein R.sub.z comprises an amide linkage covalently attached to an alkylene chain. 5. The monofunctional water soluble polymer of claim 1, wherein --P--CH(Q-)Z is formed from an alcohol having more than two hydroxyl groups. 6. The monofunctional water soluble polymer of claim 2, wherein --P--CH(Q-)Z is formed from an alcohol having more than two hydroxyl groups. 7. The monofunctional water soluble polymer of claim 4, wherein --P--CH(Q-)Z is formed from an alcohol having more than two hydroxyl groups. 8. The monofunctional water soluble polymer of claim 1, wherein P is an alkyl fragment joined to poly.sub.a by an ether linkage. 9. The monofunctional water soluble polymer of claim 2, wherein P is an alkyl fragment joined to poly.sub.a by an ether linkage. 10. The monofunctional water soluble polymer of claim 4, wherein P is an alkyl fragment joined to poly.sub.a by an ether linkage. 11. The monofunctional water soluble polymer of claim 2, wherein the reactive site is selected from carboxyl and activated carboxyl. 12. The monofunctional water soluble polymer of claim 10, wherein the reactive site is selected from carboxyl and activated carboxyl. 13. The monofunctional water soluble polymer of claim 2, wherein the reactive site is selected from active esters, active carbonates, and maleimide. 14. The monofunctional water soluble polymer of claim 10, wherein the reactive site is selected from active esters, active carbonates, and maleimide. 15. The monofunctional water soluble polymer of claim 14, wherein the reactive site is selected from N-hydroxysuccinimidyl ester and maleimide. 16. The monofunctional water soluble polymer of claim 1 covalently attached via the single reactive site of Z to a biologically active molecule. 17. The monofunctional water soluble polymer of claim 16, wherein said biologically active molecule is a protein. 18. The monofunctional water soluble polymer of claim 10 covalently attached via the single reactive site of Z to a biologically active molecule. 19. A conjugate formed by reacting the monofunctional water soluble polymer of claim 1 with a biologically active molecule. 20. The monofunctional water soluble polymer of claim 1 wherein P and Q are the same. 21. The monofunctional water soluble polymer of claim 1 wherein P and Q are different.