Chemoembolisation

1. A composition comprising particles having a matrix of water-swellable water-insoluble polymer and, absorbed in the matrix, a water-soluble therapeutic agent, and is characterised in that the polymer has an overall anionic charge at a pH in the range 6 to 8, in that the particles, when swollen to equilibrium in water have particle sizes in the range 40-1500 μm and in that the therapeutic agent is an anthracycline compound having at least one amine group, wherein the level of anion in the polymer matrix is in the range of 0.1 to 10 meq/g, the polymer comprises poly(vinyl alcohol) and the particles are microspheres.

2. A composition according to claim 1 in which the polymer is covalently cross-linked.

3. A composition according to claim 1 in which the polymer comprises cross-linked poly(vinyl alcohol).

4. A composition according to claim 3 formed by copolymerising poly(vinyl alcohol) macromer having at least two pendant ethylenically unsaturated groups per molecule with ethylenically unsaturated monomers including anionic monomer.

5. A composition according to claim 4 in which the anionic monomer has the general formula I

Y 1 BQ

in which Y 1 is selected from

CH 2 ═C(R)—CH 2 —O—, CH 2 ═C(R)—CH 2 OC(O)—, CH 2 ═C(R)OC(O)—, CH 2 ═C(R)—O—, CH 2 ═C(R)CH 2 OC(O)N(R 1 )—, R 2 OOCCR═CRC(O)—O—, RCH═CHC(O)O—, RCH═C(COOR 2 )CH 2 —C(O)—O—

wherein

R is hydrogen or a C 1 -C 4 alkyl group;

R 1 is hydrogen or a C 1 -C 4 alkyl group;

R 2 is hydrogen or a C 1-4 alkyl group or BQ where B and Q are as defined below;

A is —O— or —NR 1 —;

K 1 is a group —(CH 2 ) r OC(O)—, —(CH 2 ) r C(O)O—, —(CH 2 ) r OC(O)O—, —(CH 2 ) r NR 3 —, —(CH 2 ) r NR 3 C(O)—, —(CH 2 ) r C(O)NR 3 —, —(CH 2 ) r NR 3 C(O)O—, —(CH 2 ) r OC(O)NR 3 —, —(CH 2 ) r NR 3 C(O)NR 3 — (in which the groups R 3 are the same or different), —CH 2 ) r O—, —(CH 2 ) r SO 3 —, or, optionally in combination with B 1 , a valence bond and r is from 1 to 12 and R 3 is hydrogen or a C 1 -C 4 alkyl group;

B is a straight or branched alkanediyl, oxaalkylene, alkanediyloxaalkanediyl, or alkanediyloigo(oxaalkanediyl) chain optionally containing one or more fluorine atoms up to and including perfluorinated chains or, if Q or Y 1 contains a terminal carbon atom bonded to B a valence bond; and

Q is an anionic group.

6. A composition according to claim 5 in which Y 1 is CH 2 ═CRCOA in which R is H or methyl, A is NH, and in which B is C 1-12 alkanediyl.

7. A composition according to claim 5 in which Q is a carboxylate, carbonate, sulphonate, sulphate, nitrate, phosphonate or phosphate group.

8. A composition according to claim 4 in which the poly(vinyl alcohol) macromer has average molecular weight in the range 1,000 to 500,000 D.

9. A composition according to claim 4 in which the pendant ethylenic groups are linked via cyclic acetal linkages with oxygen atoms from adjacent hydroxyl groups.

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

preferably doxorubicin.

11. A composition according to claim 1 in which the particles are swollen with and suspended in an aqueous liquid.

12. A composition according to claim 11 further comprising an imaging agent.

13. A composition according to claim 12 , wherein the imaging agent is a radiopaque agent.

14. A method of embolotherapy of a patient having a solid tumour, in which the composition of claim 1 is administered to form an embolus in the circulation.

15. Process for producing a composition according to claim 1 in which particles of a polymer are contacted with a solution of the anthracycline in the presence of water whereby anthracycline is absorbed into the matrix of the polymer.

16. Process according to claim 15 in which the contacting is carried out by suspending the polymer particles in an aqueous solution of the anthracycline.

17. Process according to claim 16 in which the particles of polymer with anthracycline absorbed in the matrix are recovered from the suspension and dried.

18. A composition according to claim 1 , wherein the water-insoluble water-swellable polymer has an equilibrium water content measured by gravimetric analysis in the range of 40-99 wt %.

19. A composition according to claim 1 , wherein the water-insoluble water-swellable polymer has an equilibrium water content measured by gravimetric analysis in the range of 75-95 wt %.

20. A composition according to claim 1 , wherein the anthracycline is doxorubicin.

21. A composition according to claim 1 , wherein the particles are swollen with and suspended in an aqueous liquid.

22. A composition according to claim 21 , further comprising an imaging agent.

23. A method for treatment comprising administering the composition of claim 22 , to a patient suffering from a solid tumor, whereby an embolus is formed containing the particles.

24. A composition according to claim 22 , wherein the imaging agent is a radiopaque agent.

25. A method of embolotherapy of a patient having a solid tumour, in which an anthracycline compound having at least one amine group is delivered from a composition comprising particles having a matrix of water-swellable water-insoluble polymer and, absorbed in the matrix, the anthracycline compound, and is characterised in that the polymer has an overall anionic charge at a pH in the range 6 to 8, in that the particles, when swollen to equilibrium in water have particle sizes in the range 40-1500 μm, wherein the level of anion in the polymer matrix is in the range of 0.1 to 10 meq/g, the polymer comprises poly(vinyl alcohol) and the particles are microspheres,

and wherein the polymer matrix is formed by the copolymerisation of a poly(vinyl alcohol) macromer having at least 2 pendant ethylenically unsaturated groups per molecule and an ethylenically unsaturated anionic monomer.