Targeting of glycoprotein therapeutics
Methods of making ligand-decorated polymer conjugates of therapeutic glycoproteins are described. Improved targeting of glycoproteins to specific tissues is achieved by masking the natural carbohydrate and other surface determinants with high molecular weight polymers, such as, e.g., PEG, polysialic acid, etc., which in turn are decorated with target-specific ligands. In some embodiments, acid-labile linkages in such conjugates or rapidly degradable masking groups allow for the intracellular release of the polymer from the glycoprotein, for example, under conditions found in lysosomes.
1. A method of treating a lysosomal storage disorder in a mammal, comprising administering to the mammal a pharmaceutical composition comprising:
(i) a conjugate comprising:
(1) a therapeutic glycoprotein (G),
(2) a masking moiety (M) capable of reducing or blocking binding of the glycoprotein to its cognate receptor, wherein the masking moiety is covalently linked to the glycoprotein through a first linker (L 1 ), and
(3) a targeting moiety (T) covalently linked to the masking moiety through a second linker (L 2 ),
wherein the conjugate has formula G(L 1 -M(L 2 -T) n ) m ,
wherein 2≦m≦16, and n<1 or 1<n≦20,
wherein the glycoprotein is released from the conjugate under lysosomal conditions, and
(ii) a pharmaceutically acceptable excipient.
2. The method of claim 1 , wherein:
the therapeutic glycoprotein is α-galactosidase A,
the masking moiety is polysialic acid (PSA), and
L 1 and L 2 each comprises a disulfide group.
3. The method of claim 1 , wherein M is covalently linked to an oligosaccharide side chain of the glycoprotein through L 1 .
4. The method of claim 1 , wherein M is covalently linked to an amino acid residue of the glycoprotein through L 1 .
5. The method of claim 4 , wherein the amino acid residue is a lysine residue.
6. The method of claim 1 , wherein the glycoprotein is a nonviral protein selected from the group consisting of an enzyme and an antibody.
7. The method of claim 6 , wherein the enzyme is a lysosomal enzyme.
8. The method of claim 7 , wherein the lysosomal enzyme is selected from the group consisting of α-galactosidase A, acid ceramidase, acid α-L-fucosidase, glucocerebrosidase, acid β-galactosidase, iduronate-2-sulfatase, α-L-iduronidase, galactocerebrosidase, acid α-mannosidase, acid β-mannosidase, arylsulfatase B, arylsulfatase A, N-acetylgalactosamine-6-sulfate sulfatase, acid sphingomyelinase, acid α-glucosidase, β-hexosaminidase B, heparan N-sulfatase, α-N-acetylglucosaminidase, acetyl-CoA:α-glucosaminide N-acetyltransferase, N-acetylglucosamine-6-sulfate sulfatase, α-N-acetylgalactosaminidase, sialidase, β-glucuronidase, and β-hexosaminidase A.
9. The method of claim 8 , wherein the lysosomal enzyme is selected from the group consisting of acid α-glucosidase, acid sphingomyelinase, α-galactosidase A, and glucocerebrosidase.
10. The method of claim 1 , wherein the masking moiety is degradable under lysosomal conditions.
11. The method of claim 1 , wherein the masking moiety comprises 2-10 functional groups for conjugation to the glycoprotein and the targeting moiety.
12. The method of claim 11 , wherein the masking moiety comprises 3, 4, or 5 functional groups for conjugation to the glycoprotein and the targeting moiety.
13. The method of claim 1 , wherein n<1.
14. The method of claim 1 , wherein 1<n≦20.
15. The method of claim 1 , wherein the masking moiety is a polymer selected from the group consisting of polyethylene glycol (PEG), polyvinylpyrrolidone (PVP), polymethacrylate (PMA), polysialic acid (PSA), hyaluronic acid (HA), albumin, immunoglobulin (IgG), dextran sulfate, polyethyleneimine (PEI), polyacrylamide, α,β-poly(N-hydroxyethyl)-DL-aspartamide (PHEA), poly(vinylpyrrolidone-co-dimethyl maleic anhydride (poly(VP-co-DMMAn), N-(2-hydroxypropyl)methacrylamide) (HPMA), and hydroxy alkyl starch (HAS).
16. The method of claim 15 , wherein the masking moiety is a PEG selected from the group consisting of a star-PEG and a pendant-PEG.
17. The method of claim 15 , wherein the masking moiety is a polysialic acid (PSA).
18. The method of claim 17 , wherein the masking moiety is a polysialic acid (PSA) comprising 2-10 functional groups for conjugation to the glycoprotein and the targeting moiety.
19. The method of claim 1 , wherein the targeting moiety is a transducing peptide, a non-endogenous protein, a receptor-binding peptide, an antibody to a receptor, or a natural receptor ligand.
20. The method of claim 1 , wherein at least one of L 1 and L 2 comprises amido.
21. The method of claim 1 , wherein at least one of L 1 and L 2 comprises at least one group that is labile under lysosomal conditions.
22. The method of claim 21 , wherein L 1 comprises at least one group that is labile under lysosomal conditions.
23. The method of claim 21 , wherein at least one of L 1 and L 2 comprises at least one acid-labile group.
24. The method of claim 23 , wherein the at least one acid-labile group is selected from the group consisting of hydrazone, imino, and ester.
25. The method of claim 24 , wherein the at least one acid-labile group is a hydrazone group.
26. The method of claim 21 , wherein at least one of L 1 and L 2 comprises a disulfide group.
27. The method of claim 26 , wherein at least one of L 1 and L 2 comprises a formula selected from the group consisting of:
wherein:
2≦p≦12.
28. The method of claim 26 , wherein the disulfide of L 1 , L 2 , or both is formed with the terminal sulfur atom of a formula selected from the group consisting of:
and a sulfur atom of G, M, or T.
29. The method of claim 21 , wherein at least one of L 1 and L 2 comprises at least one acid-labile group and a disulfide group.
30. The method of claim 29 , wherein at least one of L 1 and L 2 comprises a formula selected from the group consisting of:
31. The method of claim 21 , wherein:
L 1 comprises the formula
wherein 2≦p≦12, and
L 2 comprises the formula
wherein 2≦q≦12.
32. The method of claim 1 , wherein the conjugate comprises a formula selected from the group consisting of:
33. The method of claim 1 , wherein at least one of the linkers L 1 and L 2 comprises a formula selected from the group consisting of:
wherein 2≦p≦12.
34. The method of claim 1 , wherein at least one of the linkers L 1 and L 2 comprises the formula
35. The method of claim 1 , wherein at least one of the linkers L 1 and L 2 comprises a formula selected from the group consisting of:
36. The method of claim 1 , wherein:
L 1 further comprises the formula
wherein 2≦p≦12, and
L 2 further comprises the formula
wherein 2≦q≦12.
37. The method of claim 1 , wherein at least one of the linkers L 1 and L 2 further comprises a formula selected from the group consisting of:
38. A method of treating a lysosomal storage disorder in a mammal, comprising administering to the mammal a pharmaceutical composition comprising:
(i) a conjugate comprising:
(1) a therapeutic glycoprotein (G),
(2) a masking moiety (M) capable of reducing or blocking binding of the glycoprotein to its cognate receptor, wherein the masking moiety is covalently linked to the glycoprotein through a first linker (L 1 ), and
(3) a targeting moiety (T) covalently linked to the masking moiety through a second linker (L 2 ),
wherein:
the conjugate has formula G(L 1 -M(L 2 -T) n ) m , wherein 2≦m≦16, and n<1 or 1<n≦20,
the therapeutic glycoprotein is α-galactosidase A,
the masking moiety is polysialic acid (PSA),
L 1 and L 2 each comprises a disulfide group, and
the targeting moiety comprises the amino acid sequence of SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:5, or SEQ ID NO:6, and
wherein the glycoprotein is released from the conjugate under lysosomal conditions; and
(ii) a pharmaceutically acceptable excipient.
39. The method of claim 27 , wherein one or more of the terminal atoms of the formula are derived from the element G, M, or T to which the atoms are attached.
40. The method of claim 30 , wherein one or more of the terminal atoms of the formula are derived from the element G, M, or T to which the atoms are attached.
41. The method of claim 32 , wherein any one or more of the terminal atoms of the formula between elements G and M and between elements M and T are derived from the element to which the atoms are attached.
42. The method of claim 33 , wherein any one or more of the terminal atoms of formulas XIX and XX are derived from the element G, M, or T to which the formula is attached.
43. The method of claim 34 , either or both of the terminal atoms of the formula being derived from the element G, M, or T to which the atoms are attached.