Histamine-succinyl-glycyl hapten (HSG)

Histamine-succinyl-glycyl (HSG) is a synthetic, low-molecular-weight hapten primarily utilized in pre-targeted radioimmunotherapy (PRIT) and immuno-PET imaging (Goldenberg et al., 2012). It is not a naturally occurring biological target but rather functions as a capture moiety for bispecific antibodies (bsAbs) designed with one arm specific to a tumor-associated antigen (such as CEA or MUC1) and the other arm specific to the HSG hapten (Sharkey et al., 2003). In clinical applications, the bispecific antibody is administered first to localize at the tumor site, followed by the administration of a radiolabeled peptide containing the HSG moiety, such as IMP-288 (Schoffelen et al., 2013). This approach allows for high-contrast imaging and potent radiotherapy by decoupling the slow-clearing antibody from the fast-clearing radioactive ligand. By using this two-step method, clinicians can achieve high tumor-to-background ratios and reduce off-target radiation to healthy tissues, particularly the bone marrow. HSG-based systems have been extensively studied in the context of colorectal, pancreatic, and medullary thyroid cancers using antibodies like TF2 and TF10 (Boddeti et al., 2012).

Other names

HSGHistamine-succinyl-glycineHSG-haptenHistamine-succinyl-glycyl-lysine

Hapten-mediated capture in pre-targeted radioimmunotherapy (PRIT)