A NOVEL METHOD FOR THE NONCHROMATOGRAPHIC PURIFICATION OF TC-99M-LABELED MONOCLONAL-ANTIBODIES - A STUDY WITH B72.3 MONOCLONAL-ANTIBODY

A cleaning resin has been developed for the non-chromatographic purifi cation of Tc-99m-labeled monoclonal antibodies (MAbs). The resin used is a modified form of thiopropylsepharose 6B resin, in which its sulfh ydryl groups have been tinylated with stannous chloride. The method re quires only simple stirring of the radiolabeling reaction mixture with this tinylated resin and subsequent separation of it from the resin b y filtration to obtain a Tc-99m-labeled MAb of radiopharmaceutical pur ity. The method provides an alternative to chromatographic purificatio n of the radiolabeled MAb (i.e. gel filtration or anion exchange chrom atography) which has been used in other Tc-99m-MAb preparations. For c omparison studies, we labeled the B72.3 MAb with NeoRx's diamide dimer captide chelate radiolabeling kit, split the reaction mixture into two equal portions and then purified one portion with anion exchange chro matography (NeoRx's chosen method) while the other portion was purifie d with our cleaning resin. Comparison of HPLC chromatograms, percent T c-99m-bound to MAb, biodistribution and scintigraphic results show tha t our cleaning resin methodology provides a Tc-99m-labeled MAb of esse ntially equal purity and utility as does the established, chromatograp hic one.