Preparation of 188Re-MAG3-Lym-1 and 188Re-HYNIC-Lym-1 immunoconjugates for radioimmunotherapy

For radioimmunotherapy, it is important that rapid labeling, high labeling yield and good stability. To prepare 188Re immunoconjugates for radioimmunotherapy, monoclonal antibody, Lym-1, was indirectly radiolabeled with 188Re by MAG3 chelate or HYNIC-lym-1 conjugate prepared radiolabeled with 188Re-tricine. These 188Re-lym-1 immunoconjugates were compared with the preparation and in vitro Stability. 188Re-MAG3 and 188Re-MAG3-TFP was radiolabeled with 98% yield. Radiolabeling yield of lym-1 with 188Re-MAG3 was 23%. 188Re-Tricine was radiolabeled with 96.5% yield. HYNIC coupling ratio to a molecule of lym-1 was 3.6. 188Re-HYNIC-lym-1 was prepared by 20% labeling yield and non-specific labeling of 188Re-Tricine with lym-1 was < 1%. Radiochemical purity of purified 188Re-MAG3-lym-1 and 188Re-HYNIC-lym-1 were maintained at >80% after 16hr standing at 4.deg. C. Both 188Re-MAG3-lym-1 and 188Re-HYNIC-lym-1 immunoconjugates showed 20% labeling yield and >80% stability. Radiolabeling of lym-1 with HYNIC chelate than MAG3 was more simple and time-saving method. Antibody radiolabeling with 188Re using HYNIC chelate can be used for the preparation of radioimmunoconjugate for radioimmunotherapy