Chemoembolisation

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 particles, 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.