Histamine-succinyl-glycine (HSG) binding site of anti-CEA x anti-HSG bispecific antibody (HSG-binding site)

The Histamine-succinyl-glycine (HSG) binding site on the anti-HSG arm of a bispecific antibody is a synthetic molecular target designed for pre-targeted radioimmunotherapy (PRIT) and immuno-PET imaging. This system typically employs a bispecific monoclonal antibody (bsAb), such as TF2, which is engineered using Dock-and-Lock technology to possess dual specificity for a tumor-associated antigen, most commonly Carcinoembryonic Antigen (CEA), and the synthetic HSG hapten (Schoffelen et al., 2013; PMID: 23303603). The clinical utility of this target lies in its ability to decouple the slow-clearing antibody targeting phase from the delivery of the effector molecule. In practice, the bsAb is administered first to saturate tumor-associated CEA; once cleared from the circulation, a small, fast-clearing HSG-conjugated peptide carrying a radioactive or therapeutic payload is injected and captured by the localized antibody (Goldenberg et al., 2012; PMID: 22407824). This approach significantly improves the tumor-to-background ratio and reduces radiation-induced bone marrow toxicity compared to conventional radioimmunotherapy (Sharkey et al., 2003; PMID: 12960133). This target system is primarily investigated for the treatment and detection of CEA-expressing malignancies, including colorectal, pancreatic, and medullary thyroid cancers.

Other names

HSG-binding armanti-HSG armHSG-binding siteTF2 anti-HSG armm679-derived binding siteHistamine-succinyl-glycine hapten-binding site

Pre-targeted delivery of diagnostic or therapeutic payloads via high-affinity capture of HSG-labeled peptides by a pre-localized bispecific antibody.