Lutetium-177 and iodine-131 loaded chelating polymer microparticles intended for radioembolization of liver malignancies

We describe the synthesis, characterization and radiochemical studies on macroporous chelating polymer beads as carriers of beta-emitters lutetium-177 and iodine-131 intended for radioembolization of liver tumors. The starting poly(glycidyl methacrylate-co-ethylene dimethacrylate) (bead size 20-40 μ) was reacted with ammonia or methylamine to introduce primary and secondary amino groups, respectively. The primary amino groups containing polymer was used for the attachment of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) moieties, while quinoline-8-ol or 8-hydroxyquinoline-5-sulfonic acid moieties, respectively, were introduced onto the secondary amino groups containing polymer. All the polymers were labeled quantitatively by lutetium-177 in ammonium acetate buffer, DOTA containing beads however required heating to 80 °C while the quinoline-8-ol or 8-hydroxyquinoline-5-sulfonic acid moieties containing polymers were quantitatively radiolabeled within 1 h at room temperature. The quinoline-8-ol groups containing polymer was radioiodinated in 95% yield by a chloramine method. Both lutetium-177 and iodine-131 radiolabels were stable in an in vitro study in rat blood plasma. Quinoline-8-ol or 8-hydroxyquinoline-5-sulfonic acid moieties are thus more suitable for the radiolabeling of macroporous beads with lutetium-177 for radioembolization purposes than well-established DOTA moieties and in addition, quinoline-8-ol also allows radiolabeling with iodine-131.