Camptothecin-binding moiety conjugates
The invention relates to therapeutic conjugates with improved ability to target various diseased cells containing a targeting moiety (such as an antibody or antibody fragment), a linker and a camptothecin as a therapeutic moiety, and further relates to processes for making and using the said conjugates.
1. A method for delivering a camptothecin drug, comprising administering to a subject a composition comprising a conjugate of a camptothecin drug and a targeting moiety of the formula:
TM-[L3]-[L2]-[L1] m AA n -CPT, where TM is a targeting moiety selected from the group consisting of a murine, chimeric, primatized, humanized, and human monoclonal antibody (MAb), and said antibody is an intact antibody, an antibody fragment selected from the group consisting of Fab, Fab′, F(ab)2 and F(ab′)2, or a single-chain construct antibody sub-fragment; CPT is camptothecin or an analog thereof; L3 is a component of a cross-linker comprising an antibody-coupling moiety; L2 comprises a defined PEG (polyethylene glycol) with 1-12 monomeric units attached to L3 at one end with a triazole moiety, is attached to L1 at the other end by an amide, hydrazide, carbonate or ester bond, or to CPT by a carbonate bond when L1 and AA are absent, or attached to AA by an amide bond when L1 is absent; L1 comprises a collapsible linker, or a peptidase-cleavable moiety optionally attached to a collapsible linker, or an acid-cleavable moiety; AA is an amino acid; m is an integer with values of 0 or 1, and n is an integer with values of 0, 1, 2, 3, or 4; and when n is >1, the amino acids represented by AA can be the same or different.
2. The method of claim 1 , wherein L2 comprises a defined PEG with 12 monomeric units.
3. The method of claim 1 , wherein L2 comprises a defined PEG with 11 monomeric units.
4. The method of claim 1 , wherein L2 comprises a defined PEG with 10 monomeric units.
5. The method of claim 1 , wherein L2 comprises a defined PEG with 9 monomeric units.
6. The method of claim 1 , wherein L2 comprises a defined PEG with 8 monomeric units.
7. The method of claim 1 , wherein L2 comprises a defined PEG with 7 monomeric units.
8. The method of claim 1 , wherein L2 comprises a defined PEG with 6 monomeric units.
9. The method of claim 1 , wherein L2 comprises a defined PEG with 5 monomeric units.
10. The method of claim 1 , wherein L2 comprises a defined PEG with 4 monomeric units.
11. The method of claim 1 , wherein L2 comprises a defined PEG with 3 monomeric units.
12. The method of claim 1 , wherein L2 comprises a defined PEG with 2 monomeric units.
13. The method of claim 1 , wherein L2 comprises a defined PEG with 1 monomeric unit.
14. The method of claim 1 , wherein the conjugate is administered in combination with one or more other therapeutic agents selected from the group consisting of unconjugated antibodies, radiolabeled antibodies, drug-conjugated antibodies, toxin-conjugated antibodies, a drug, a chemotherapeutic agent, a toxin, an immunomodulator, a cytokine, a chemokine, a hormone, an oligonucleotides, an RNAi and an siRNA.
15. The method of claim 14 , wherein the immunomodulator is selected from the group consisting of a cytokine, a chemokine, a lymphokine, a monokine, an interleukin, an interferon and tumor necrosis factor.
16. The method of claim 1 , wherein said antibody is an IgG1, IgG2a, IgG3 or IgG4.
17. The method according to claim 1 , wherein said antibody-coupling moiety is thiol-reactive and is selected from the group consisting of maleimide, vinylsulfone, bromoacetamide, and iodoacetamide.
18. The method according to claim 1 wherein said CPT is selected from the group consisting of CPT, 10-hydroxy camptothecin, SN-38, topotecan, lurtotecan, 9-aminocamptothecin, 9-nitrocamptothecin, and derivatives thereof.
19. The method according to claim 18 , wherein said CPT is SN-38.
20. The method according to claim 19 , wherein the 10-hydroxy position of SN-38 is protected as 10-O-ester or 10-O-carbonate derivative using a ‘COR’ moiety where the R group is selected from substituted alkyl residue “N(CH 3 ) 2 —(CH 2 ) n —” where n is 2-10 and wherein the terminal amino group is optionally in the form of a quaternary salt for enhanced aqueous solubility, or simple alkyl residue “CH 3 —(CH 2 ) n —” where n is 0-10, or alkoxy residues “CH 3 —(CH 2 )n-O—” where n is 0-10 or “N(CH 3 ) 2 —(CH 2 ) n —O—” where n is 2-10, or “R 1 O—(CH 2 —CH 2 —O) n —CH 2 —CH 2 —O—” where R 1 is ethyl or methyl and n is an integer with values of 0-10.
21. The method according to claim 1 , wherein the cleavable polypeptide is selected from the group consisting of Phe-Lys, Val-Cit, Ala-Leu, Leu-Ala-Leu, and Ala-Leu-Ala-Leu (SEQ ID NO: 5).
22. The method according to claim 1 , wherein said MAb is multispecific or bispecific.
23. The method of claim 1 , wherein the targeting moiety is a fusion protein.
24. The method of claim 1 , wherein the composition comprises a conjugate of a camptothecin drug and a targeting moiety of a formula selected from the group consisting of MAb-CL1-SN-38, MAb-CL2-SN-38, MAb-CL3-SN-38, MAb-CL4-SN-38, MAb-CL5-SN-38 and having a structure selected from: