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.