Radio-pharmaceutical complexes

1. A tissue-targeting complex comprising

a tissue targeting moiety selected from the group consisting of a monoclonal or polyclonal antibody, an antibody fragment, a construct of said antibody or fragment, and an antibody mimetic,

an octadentate hydroxypyridinone-containing ligand comprising four chelating 3,2-HOPO moieties of formula I

wherein R 1 is a hydroxyalkyl moiety; groups R 4 to R 6 are each H, R 3 is OH, and R 2 is ═O,

and the 4+ion of the alpha-emitting thorium radionuclide 227 Th.

2. The complex as claimed in claim 1 wherein the N-substituents on each of the four HOPO groups are each independently chosen from HOCH 2 —, HOCH 2 CH 2 —, HO—CH 2 CH 2 CH 2 —, HO—CH(CH 3 )CH 2 —, HO—CH 2 CH 2 CH 2 CH 2 —, HO—CH(CH 3 )CH 2 CH 2 —, HO—CH(CH 2 CH 3 )CH 2 —, HO—C(CH 3 ) 2 CH 2 —, HO—CH(CH 3 )CH(CH 3 )—and HOCH 2 CH(CH 2 CH 3 )—.

3. The complex as claimed in claim 1 comprising a ligand moiety of formula VI:

wherein R L is a linker moiety for attachment of the ligand moiety to the tissue targeting moiety.

4. A complex as claimed in claim 1 wherein the antibody fragment (is a Fab, a F(ab′) 2 , a Fab′, or a scFv.

5. A method of treatment of a human or non-human animal in need thereof comprising administration of

a tissue targeting moiety selected from the group consisting of a monoclonal or polyclonal antibody, an antibody fragment, a construct of said antibody or fragment, and an antibody mimetic,

an octadentate hydroxypyridinone-containing ligand comprising four chelating 3,2-HOPO moieties of formula I

wherein R 1 is a hydroxyalkyl moiety; groups R 4 to R 6 are each H, R 3 is OH, and R 2 is ═O,

and the 4 +ion of the alpha-emitting thorium radionuclide 227 Th.

6. The method as claimed in claim 5 for the treatment of hyperplastic or neoplastic disease, a carcinoma, a sarcoma, a myeloma, leukemia, a lymphoma or a mixed type cancer.

7. A pharmaceutical composition comprising a tissue-targeting complex as defined in claim 1 together with at least one pharmaceutical carrier or excipient.

8. A kit for use in a method according to claim 5 , said kit comprising a tissue targeting moiety, conjugated or conjugatable to an octadentate hydroxypyridinone-containing ligand comprising four 3,2-HOPO moieties, where all four HOPO moieties are substituted at the N-position with a hydroxyalkyl solubilising group, said kit including the alpha-emitting thorium radionuclide 227 Th.

9. A method of formation of a tissue-targeting complex, said method comprising coupling a tissue targeting moiety to an octadentate hydroxypyridinone-containing ligand in aqueous solution, the complex comprising four 3,2-HOPO moieties and the ion of an alpha-emitting thorium radionuclide, where all four HOPO moieties are substituted at the N-position with a hydroxyalkyl solubilising group.

10. The method of claim 9 comprising preparing a first aqueous solution of octadentate hydroxypyridinone-containing ligand and a second aqueous solution of said tissue targeting moiety and contacting said first and said second aqueous solutions.

11. The method of claim 10 wherein said contacting is conducted at below 40° C.

12. The method of claim 10 wherein said contacting is conducted in the substantial absence of any organic solvent.

13. The method of claim 9 wherein said coupling yields an amide, ester, ether or amine bond between the ligand moiety and the targeting moiety.

14. The method of claim 13 wherein said amide or ester linkage is formed by means of at least one activated ester group.

15. The method as claimed in claim 5 , wherein said antibody fragment is a Fab, a F(ab′) 2 , a Fab′, or a scFv.

16. The method of claim 13 , wherein said amide or ester linkage is formed by means a N-hydroxy maleimide, carbodiimide, or azodicarboxylate coupling reagent.