Di-diethylenetriaminepentaacetic acid-Iodine-131 hapten (di-DTPA-131I) (di-DTPA-131I)

The di-DTPA-131I hapten is a synthetic, bivalent molecule designed for use in pretargeted radioimmunotherapy (PRIT), specifically within the Affinity Enhancement System (AES) (Barbet et al., 1999, Cancer Biotherapy & Radiopharmaceuticals). It consists of two diethylenetriaminepentaacetic acid (DTPA) moieties linked by a peptide backbone, which is typically labeled with the radionuclide Iodine-131 on a tyrosine residue (Kraeber-Bodéré et al., 2006, Journal of Nuclear Medicine). This molecule is not a biological target but serves as a radiolabeled effector that is captured by a previously administered bispecific antibody (bsAb) localized at the tumor site (Goldenberg et al., 2006, Journal of Clinical Oncology). One arm of the bsAb binds to a tumor-associated antigen, such as Carcinoembryonic Antigen (CEA), while the other arm is specific for the metal-chelate complex, often Indium-DTPA (Sharkey et al., 2003, Cancer Research). The bivalent structure of the hapten allows it to cross-link two bsAb molecules on the cell surface, significantly increasing its functional affinity and tumor retention time through the AES mechanism (Barbet et al., 1999). This approach optimizes the therapeutic index by allowing the large, slow-clearing antibodies to reach the tumor and clear from the blood before the small, rapidly-clearing radioactive hapten is administered, thereby reducing off-target radiation to healthy tissues like bone marrow (Gestin et al., 2001, Nuclear Medicine and Biology).

Other names

Bivalent DTPA hapten131I-labeled di-DTPAdi-DTPA-tyrosyl-lysine haptenAES hapten

Pretargeted radioimmunotherapy (PRIT) using the Affinity Enhancement System (AES) to deliver Iodine-131 radiation to tumor cells via bispecific antibody capture (Barbet et al., 1999; Kraeber-Bodéré et al., 2006).