CEACAM5 and colonic neoplasm: A humanized bispecific fusion protein of the two Fv portions from an anti-CEA mAb (hMN-14; labetuzumab) and another antibody, which recognizes an inert hapten peptide (histamine-succinyl-glycine; HSG), was explored for localizing 99mTc-labeled HSG to human colonic tumors in a xenograft model (Sharkey et al. 2005; Sharkey et al. 2003).