Pretargeting with labeled bivalent peptides allowing the use of four radionuclides: (111)In, (131)I, (99m)Tc, and (188)Re.

Purpose: The therapeutic effect of directly labeled antibodies in solid tumors is limited, mainly due to the relatively low uptake of the radiolabeled antibody in tumors as compared with their blood level. In previous studies, we have shown that renal cell carcinoma (RCC) can be targeted very effectively with the (111)In-labeled bivalent peptide di-diethylenetriamminepentaacetic acid diDTPA-FKYK, after pretargeting the tumor with a bispecific antibody. In this study, we further developed this pretargeting approach for radioimmunotherapy of renal cell cancer.