Chemoembolisation

1. A composition comprising microspheres having a matrix of water-swellable water-insoluble polymer and, absorbed in the matrix, a water-soluble therapeutic agent, wherein the polymer has an overall anionic charge at a pH in the range 6 to 8, wherein the microspheres, when swollen to equilibrium in water have particle sizes in the range 40-1500 μm, wherein the therapeutic agent is an anthracycline compound having at least one amine group, and wherein the polymer is a polymer of ethylenically unsaturated monomers including anionic monomer and di- or higher-functional cross-linking monomer in amounts to obtain polymer having an anionic charge at a level of 1 to 10 meq/g.

2. A composition according to claim 1 in which the anion is a carboxylate, carbonate, sulphonate, sulphate, nitrate, phosphonate or phosphate group.

3. A composition according to claim 1 wherein the anion is a carboxylate group.

4. A composition according to claim 1 wherein the anion is a sulphonate group.

5. A composition according to claim 1 in which the anthracycline is a compound of the general formula II

6. A composition according to claim 5 wherein the compound of general formula II is doxorubicin.

7. A composition according to claim 1 wherein the microspheres are swollen with and suspended in an aqueous liquid.

8. A composition according to claim 7 further comprising an imaging agent.

9. A composition according to claim 8 wherein the imaging agent is a radiopaque agent.

10. Method of treatment of a solid tumour in which a composition according to claim 7 is mixed with a contrast agent and the mixture is then administered into a blood vessel of a patient to embolise the solid tumour.

11. Method according to claim 10 wherein the tumour is hepatocellular carcinoma.

12. A composition according to claim 1 wherein the microspheres are in the form of a pumpable slurry comprising particles swollen with aqueous liquid, substantially free of extra particulate liquid.

13. A composition according to claim 12 , which is filled into a storage container and is sterile.

14. A composition according to claim 13 wherein the storage container is a syringe.

15. A composition according to claim 1 which is substantially dry.

16. Process for producing a composition according to claim 1 comprising the steps:

providing microspheres of a water-swellable, water-insoluble polymer, wherein the polymer has an overall anionic charge at a pH in the range 6 to 8, wherein the microspheres, when swollen to equilibrium in water have particle sizes in the range 40-1500 μm and wherein the water-swellable water insoluble polymer is a polymer of ethylenically unsaturated monomers including anionic monomer and di- or higher-functional cross-linking monomer in amounts such that it has an anionic charge at a level of 1 to 10 meq/g; and

contacting the microspheres with a solution of an anthracycline having at least one amine group in the presence of water; and

absorbing anthracycline into the matrix of the polymer.

17. Process according to claim 16 in which the contacting is carried out by suspending the microspheres in an aqueous solution of the anthracycline.

18. Process according to claim 17 comprising the further step of recovering the microspheres of polymer with anthracycline absorbed in the matrix from the suspension.

19. A process according to claim 18 comprising the further step of drying the microspheres.

20. A process according to claim 19 wherein the drying is freeze-drying.

21. A process according to claim 18 wherein said step of recovering the microspheres consists of:

separating the swollen microspheres from supernatant liquid;

transferring the microspheres while still swollen by the swelling liquid into a storage container;

sterilising the container containing the microspheres; and

storing the microspheres in the container.

22. A process according to claim 21 wherein the container is a syringe.

23. Method of treatment of a solid tumour in which a composition according to claim 1 is mixed with a contrast agent and the mixture is then administered into a blood vessel of a patient to embolise the solid tumour.

24. Method according to claim 23 wherein the tumour is hepatocellular carcinoma.